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Cornell University Library 
 
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Cornell University 
 Library 
 
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 tine Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924031238730 
 
LOCKWOOD'S 
 
 DICTIONAEY OF 
 
 MECHANICAL ENGINEERING TEEMS. 
 
RECBNTL Y PUBLISHED. 
 
 With upwards of Three Hundred and Seventy Illustrations. 
 Crown 8vo, price 7s. 6d., Cloth. 
 
 PATTERN MAKING. A Practical Treatise, 
 
 embracing the Main Types of Engineering Construction, 
 and including Gearing, both hand and machine made, 
 Engine Work, Sheaves and Pulleys, Pipes and Columns, 
 Screws, Machine Parts, Pumps and Cocks, the MouidiDg of 
 Patterns in Loam and Greensand, &c., together with the 
 methods of Estimating the "Weight of Castings ; to which is 
 added an Appendix of Tables for Workshop Keferenoe. 
 
 BY 
 
 A FOREMAN PATTERN-MAKER. 
 
 "A well-written lechnical gnide, ev'dentlywrit'en by a man who under- 
 stands and has practised what he has written about ; he says what he has 
 to say in a plain, straightforward manner. We cordially recommend the 
 treatise to eng-ineering- students, young journeymen, and others desirous 
 of being initiated into the mysteries of pattern-making."— fiuiWer. 
 
 "This work is of an eminently practical character, and gives the most 
 detailed instmetione for the pi oduc'^ion of the patterns of the component 
 parts of every type of mechanism which are formed by casting. No b'jnk 
 with which we are acquainted goes into such minute del ails on the sub- 
 ject as this volume ; in fact, it supplies the apprentice or beginner with 
 a complete coui-se of instruction in his art. It is an honest and thoroughly 
 trustworthy work." — Knowle ige. 
 
 " More than 870 ilbistrations help to explain the text, which is, however, 
 alwiya clear and explicit thus rendering the work an excellent vnde memin 
 for the apprentice who desires to become master of his trade." — English 
 Mechanic. 
 
 *'This is a very good book, anrl will be useful not only Ki pattern mnkers, 
 but also to s' udeni s of engineer ng and to draughtsmen, 1 o whom a general 
 
 knowledge of pattern-making is dfisir>itile On the whole we 
 
 have read this book with much pleasure, and recommend it to iho-.f^ of 
 our re ; ders %yhose businers invoUesa knowledge of pattern-making." — 
 
 Industries. 
 
 CEOSBY LOCKWOOD & SON, 7, Sta.tioner3' Hall Coltit, Lokdon. 
 
LOCKWOOD'S 
 
 DICTIONARY OF TERMS 
 
 USED IN TEE FSACTICE OF 
 
 MEOHANICAL ENGINEERING 
 
 EMBRACING TSOSE CmtFENT IN THE ER AWING OFFICE, 
 
 FATTEFN SKOF, FOUNERT, FITTING, TURNING, 
 
 SUITES' ANE BOIEER SEOPS, 
 
 ETC., ETC, 
 
 COMPBISING 
 
 "glpttjarSs of ^i^ ^§ottsatt6 Peftntfions 
 
 EDITED ET 
 
 A FOREMAN PATTERN-MAKER 
 
 ATJTHOE or " PATTEEN MAKING," " PEACTIOAI lEON EOTJICDHf O, " " METAIi 
 TDENINa," "THE AMATEUe's "WOEKSHOP," ETC. 
 
 SECOND edition; revised, witb additions 
 
 ■ LONDON 
 CROSBY LOCKWOOD AND SON 
 
 .7, STATIONEES' HALL COUET, LUD0ATE HILL 
 
 1892 
 
 [All rights reaerved'} 
 
LONDON : 
 
 PRINTED BY J. S. YIUTUE AND CO., LIMITED, 
 
 CITY KOAD. 
 
PREFACE. 
 
 In this little book I propose to offer to the Draughtsman, Pattern- 
 maker, Moulder, Smith, Boiler-maker, Fitter, Turner, Erector, 
 and Engineer's Storekeeper a ready means of obtaining or verify- 
 ing the meaning of terms in use in other departments than his 
 own, and which, owing to the ever-widening gulf which separates 
 one class of workmen from the rest, are seldom familiar to 
 those outside of that particular department in which the terms 
 are in\use. 
 
 I ventiire to think that the engineer's pupil beginning his 
 practical studies, and the amateur worker, neither of whom 
 can possibly know the sense of many of the terms which they 
 meet with in their technical books and journals, will also find 
 it profitable to turn to a book of this character for definite 
 information thereupon. 
 
 My claim to the possession of the special knowledge necessary 
 for this task is, that I have been in the factory, engaged in 
 practical duties, during aU my working life of twenty-seven years. 
 The drawing office, pattern-shop, foundry, fitting, turning, 
 smith's, and boiler-shops are familiar to me in my capacity as 
 foreman ; therefore I have drawn in this work on the experi- 
 ences of my daily life, coupled with some necessary amount of 
 Belf-cultttre. I have endeavoured to discard aU fanciful and 
 unusual terms coined by individual workmen, or which are only 
 current in a single shop or district, and to give only those which 
 ore of luuTereal, or of moderately wide application. 
 
VI PBBFAOB. 
 
 In a work involving more than six thousand definitions, I can 
 scarcely hope, notwithstanding much care, that all errors wiU be 
 eliminated, or that there will be no omission of important terms. 
 I shall, therefore, be gratified at receiving through the publishers 
 any hints or corrections, to be incorporated or borne in miud in 
 future editions. 
 
 NOTE TO SECOND EDITION. 
 
 A NEW Edition of this book having been called for, I have taken 
 the opportunity of adding an Appendix of over two hundred 
 definitions, and of efEecting a few slight corrections and refer- 
 ences in the body of the Dictionary. I trust that its value to 
 those for whom it has been written will be increased by this 
 addition and revision. 
 
DICTIONAEY OF TERMS 
 
 trSED IN 
 
 MECHANICAL ENGINEERING. 
 
 Abele (^Fopultes alia), or White Poplar. — A species of poplar sometimes used 
 by pattern-makers. It is of a reddish colour, light and porous, and 
 moderately hard. Sp. gr. '32 to '51. A cubic foot weighs from 20 to 
 31-8 lbs. 
 
 About Sledge. — Signifies the ordinary swinging of a smith's sledge-hammer 
 in a circle for the delivery of heavy blows, as distinguished from the 
 lifting it through a small arc only, or uphand (q.v.), for light blows. 
 
 Abrasion. — The process or act of grinding, as opposed to that of cut- 
 ting. This is of great economical importance in work-shop practice, 
 since all emery-wheels and grindstones are employed for the abrasion 
 of metals in cases where the employment of cutting tools would be 
 inadmissible, being either too slow in their action, or too inaccurate 
 in their results, or would fail altogether to attack the harder varieties of 
 metal. 
 
 Absolute Pressure. — It is customary to estimate the pressure of steam in 
 lbs. above the atmosphere, but it is also the practice in some cases to 
 reckon it from the point of no pressure, or the point of perfect vacuum. 
 This is called absolute or total pressure. 
 
 Absolute Strength. — The actual breaking strength (q.v.) of a bar or 
 structure, as distinguished from the safe or working load. 
 
 Absolute Temperature. — Temperature measured from absolute zero (q.v.), 
 and useful in dealing with gases. The temperature of steam is often 
 given in degrees of absolute temperature. These may be translated 
 into degrees Fahrenheit by adding 460° to the degrees on that scale, 
 or into degrees Centigrade by adding 273 J° to the degrees on that scale. 
 
 Absolute Zero. — Corresponds with the bottom of the air thermometer at 
 which the volume of the air is imagined to have been reduced to nothing. 
 It has of course no existence in fact, but is deduced from theoretical 
 considerations based on the expansion of gases. It corresponds with 
 -459-13'' P. or — 272-85° C. 
 
 Absorbing Power.^-The capacity of timber for absorbing the preserva- 
 tive fluid used in its impregnation (q.v.). The absorbing power varies 
 with the nature of the wood subjected thereto. 
 
 Abutments. — The surfaces of support of an arch, beam, or bridge, which 
 sustain the reactions due to the load. 
 
 Acacia. — The true acacia is the wood called sabacu, which though used 
 in shipbuilding is scarcely, if at all, employed by engineers. The 
 
 V 
 
2 DICTIONARY OF TERMS USED IN 
 
 timber known popularly as acacia is the wood of the locust-tree (HoMnta 
 pseudacacia), or false acacia. Both woods belong to the order Legu- 
 minosta. The locust-tree grows in America and in Europe, and the 
 wood is of a greenish j'ellow colour. It works very much like oak, 
 though not so hard, and is used for the cogs of mortice-wheels. A cubic 
 foot weighs when dry 51 lbs. Sp. gr. -82. 
 
 Accident Crane. — A break-down crane (q.v.). 
 
 Accumulated Work. — Work done upon a body or system of bodies over 
 and above that necessary to enable them to overcome external resist- 
 ance. The fly-wheel of an engine affords a famOiax example of ac- 
 cumulated work. 
 
 Accumulator. — The cylinder into which water is forced or accuanulated 
 under pressure, in order to furnish the motive power necessary for 
 lifting the weight case (q.v.) in hydraulio machines of various kinds. 
 
 Acid Bath. — A large shallow bath used for fixing phototypes (q.v.). 
 The liquid is composed of one part of hydrochloric acid to nine parts 
 of water. See Blue Bath. 
 
 Acidity. — See OUs. 
 
 Acid Process.— The early process of steel making in the Bessemer conver- 
 ter (q.v.) as practised previous to the introduction of the Basic process 
 (q.v.). The silicious or " acid "lining (ganister) originally employed for 
 the converters rendered it impossible to effect the removal of the phos- 
 phorus present in the pig, because silioa has a greater affinity for the 
 oxide of iron which is expelled with the slags than phosphorus has ; 
 the silica displaces therefore phosphoric anhydride. Pa Os, as soon as 
 formed, and permits of its immediate reduction to phosphorus and 
 oxygen again. Hence the necessity for a strong basic lining, by whose 
 employment the free oxidation and elimination of phosphorus is rendered 
 possible. 
 
 Acid Pump.^A pump whose barrel and valves are made of glass in order 
 that they may remain unaffected by the action of the acid liquors 
 which have to pass thi'oi" 3-h them. 
 
 Acid Steel. — Steel prepared by the acid process (q.v.). 
 
 Acidulated Water. — Water in which acids have been generated, and 
 which produces corrosion in steam boilers. The acids usually are the 
 result of the decomposition of oils and fats carried over from the cylin- 
 der through the condenser, or from tallow introduced into the boiler in 
 injudicious quantity with a view to the prevention of incrustation. 
 
 Action. — The action of an engine or machine denotes its mode of working. 
 In mechanics it is an axiom that action and re-action are equal and 
 opposite. 
 
 Actual Horse-Power, or Available H.P.— Sometimes called Dynametri- 
 cal H.P. The net useful power given out by an engine. Its amount 
 is estimated by subtracting the power absorbed by the engine itself 
 from the.indicated H.P. (q.v.). The actual H.P. may average ■^ or -S 
 of the indicated H.P. 
 
 Acute Angle. — One which is less than a right angle. 
 
 Adamson's Flanged Joint. — See Flanged Seam. 
 
 Addendum. — Sometimes used to signify the point or face of the tooth of 
 a gear-wheel, lying without the pitch circle. 
 
 Adhesive Power, or Adhesion. — The amount of bite or friction of the 
 driving wheels of locomotives upon the rails, or of the coupled wheels 
 in heavy engines. When the adhesive power is less than the tractive 
 force (q.v.) the wheels slip. With clean and dry rails the adiesiou ig 
 
MECHANICAL ENGINEERING. 3 
 
 about one-fifth, or one-sixth of the weight — with greasy rails one-tenth 
 or one-twelfth. 
 
 Adiabatio Curve. — The curve wh'ioh represents the expansion of a gas 
 within a vessel, through whose substance no heat is supposed to escape, 
 notwithstanding that the gas is doing actual work during its expansion. 
 It is useful in estimating the economical efficiency of steam, air, and 
 gas engines. 
 
 Adjustable Eccentric. — An eccentric sheave which is so constructed that 
 it can be moved relatively to its shaft into a position for either forward 
 or backward gear as required. There are numerous forms in use. 
 Most eccentrics, however, are now fixed. See Fixed Eccentric. 
 
 Adjustable Footstep. — See Footstep Bearing. 
 
 Adjustable Level. — A spirit-level (q.v.) wMch is capable of adjustment 
 for reliable indication, irrespective of any inaccuracy which may be 
 present in the stock itself. The bubble tube is attached to a casing of metal 
 which is hinged at one end, and provided with a screw for adjustment 
 at the end opposite. By turning the adjusting screw which elevates or 
 depresses the casing and simultaneously packing up the stock, until the 
 bubble remains in the same position on the reversal of the stock, or end 
 for end, very great accuracy may be attained. 
 
 Adjustable Stroke. — The stroke or amount of travel of the ram of a 
 shaping or of a slotting machine, whose length can be varied according 
 to the work in hand. It is made adjustable by causing one end of the 
 connecting-rod of the ram to move across the face of the driving cog- 
 wheel, or of the throw disc, nearer to, or farther from its centre, and 
 clamping it at the particular radius desired. 
 
 Adjusting Screw. — A set-screw by means of which the position of machine 
 parts is adjusted or regulated more minutely than would be possible of 
 attainment by the mere setting to dimensions. 
 
 Adjustment. — The placing and setting of engine and machine parts in 
 position. Or the more exact and precise regulation of the positions of 
 parts already set approximately. 
 
 Adjustment Strips. — Strips of metal by means of which the exact bearing 
 of sliding surfaces is accurately adjusted, the precise shade of contact 
 being effected by pressure imparted to the strips from set or adjustment 
 screws. The sliding faces and edges of machine parts are thus ad- 
 justed. Vee strips (q.v.) are the commonest form in which they occur. 
 
 Adjutage, or Ajutage. — Aji outlet in the side of a tank or vessel for the 
 eflux of fluids. See Vena Contracta — Compound Adjutages. 
 
 Admiralty Eule. — What is known as the Admiralty rule for the nominal 
 horse power of engines is (1st), Multiply seven times the area of the 
 cylinder in inches by the mean velocity of the piston in feet per minute, 
 and divide the product by 33,000. (2nd), Square the diameter of the 
 cylinder in inches, and multiply by the mean velocity of the piston in 
 feet per minute, and divide the product by 6,000. 
 
 Admission. — The period or instant at which the steam enters an engine 
 cylinder. Or the act of entrance. Or the whole period of time during 
 which steam is entering, from the initial point to the moment of cut 
 off (q.v.). 
 
 Admission Corner. — That comer of an indicator diagram which corres- 
 ponds with the period of the entry of steam into an engine cylinder. 
 If this is much rounded or sloping it shows that the steam enters 
 the cylinder too slowly, and that there is therefore too little, or no lead 
 (q.v.). 
 
4 DICTIONARY OF TERMS USED IN 
 
 Admission Line. — That side of an indicator diagram whicli corresponds 
 ■with the rise of pressure due to the entering steam in an engine cylin- 
 der. The nearer the line approaches to the vertical the better ; a 
 sloping admission line indicates a too early or a too late admission, 
 according as it slopes at an obtuse or at an acute angle, with the atmo- 
 spheric Une. In the first case there is too much, in the second, too little 
 lead. 
 
 Admission Port. — The steam port or passage through which the entering 
 steam gains access to an engine cylinder. In engines of ordinary con- 
 struction, each port is alternately supply and exhaust, though it is 
 usual to apply the latter term only to the port which exhausts dii-ectly 
 into the atmosphere. 
 
 Advance. — See Angular Advance. 
 
 Adze. — A wood-cutting tool, whose cutting edge stands transversely or at 
 right angles with the handle. Its bevel is ground on the inner face 
 only. The entire outer face is slightly rounding. 
 
 Adze Block. — A sohd oblong block, square in section, of iron or steel, 
 which carries the cutters or plane irons of a wood-planing machine. It 
 is fmmished with slots to allow of endlong adjustment of the irons. 
 
 African Oak. — See Teak. 
 
 After Blow. — The blowing of air into a Bessemer converter (q.v.) after 
 the carbon has been burnt out, in order to oxidise the phosphorus. 
 The metal is said to be overblown when the operation is continued too 
 long. Overblown metal possesses similar characteristics to those of 
 burnt iron (q.v.). In the basic process the result of overblowing is not 
 so deleterious to the iron as in the acid process, for while in the latter 
 overblowing produces oxidation of the iron, in the former the result is 
 mainly the more complete oxidation of the phosphorus. 
 
 Aggregate Motion. — Motion whose origin is of a compound character. 
 In other words, motion which is produced by the concentration of two or 
 more independent motions upon one spot at the same instant. 
 
 Agitator. — A mechanical stirrer designed for the admixture of the spiege- 
 leisen and molten metal on its removal from the Bessemer converter to 
 the ladle. The stirrer is attached to the bottom end of a vertical 
 spindle, and is coated with loam to protect it from the high temperature. 
 It is revolved at the rate of about 100 revolutions per minute. The 
 agitator runs in iixed bearings, the ladle being brought underneath it. 
 
 Agricultural Locomotive. — See Portable Engine. 
 
 Aich Metal, or Gedge's Metal. — An alloy of copper, RO ; zinc, 38'2 ; and 
 iron, 1-8. It is capable of being cast, hammered, rolled or drawn. 
 
 Air. — A knowledge of the properties of atmospheric air is requisite to the 
 engineer, since it plays an essential part in the working of pumps and 
 pump connections, engines both condensing and non-condensing, air 
 engines and air compressors, and gas engines. Air possesses the 
 properties of a perfect gas, and as such comes under the law of Boyle 
 and Marriott (q.v.). Air is a mechanical mixture essentially of 79 
 volumes of nitrogen, with 21 volumes of oxygen. The oxygen alone 
 is capable of promoting combustion, so that when air is forced into a 
 blast furnace or boiler grate 79 volumes out of every 100 are inert, and 
 count for nothing. The pressure of the atmosphere at sea level is 
 14'7 lbs. per square inch, put roughly at 15 lbs. in ordinary calcula- 
 tions, that being the weight of a column of mercury one square inch in 
 section, and thirty inches high, which column wiU just balance the 
 atmospheric pressure. Air is a bad conductor of heat. 
 
MECHANICAL ENGINEERING. S 
 
 Air Bag. — The presser (q.v.) of a pneumatic moulding machine (q.v.). 
 Consists of bugs inflated -with air, by which an elastic and equal 
 pressure is imparted to the sand. 
 
 Air Belt. — In common cupolas the blast enters the tuyeres directly from 
 the blast pipes, but the more modem practice is to surround the tuyere 
 zone with an annular ring or ease into which the air enters from the 
 blast pipe or pipes, and from which it is deUvered through six or eight 
 tuyere holes into the cupola. This is termed an air belt or wind chest, 
 and its advnntage is that the tuyeres being arranged equidistantly 
 within it, the blast is diffused more regularly than under the older 
 method. 
 
 Air Brake. — A brake actuated either by compressed air, or by the pro- 
 duction of a vacuum. 
 
 Air Casing. — An enclosed space enveloping a reservoir of heat in order to 
 prevent loss therefrom by radiation. The uptakes of marine boilers are 
 for this reason often provided with air casings. 
 
 Air Chamber. — See Air Vessel. 
 
 Air Channels. — Shallow channels or thin spaces underneath the hearths 
 and fire bridges of reverberatory furnaces (q. v.) , their function being to 
 protect the foundations from injury by the high temperature of the 
 furnaces. 
 
 Air Compressor. — A machine by which atmospheric air is compressed in 
 volume in order to be used for purposes of ventilation, or as a motive 
 power for driving machinery, rook drills, &c. , in situations where the 
 presence of exhaust steam would be objectionable. One form of air 
 compressor is used for filling the air chambers of Whitehead torpedoes.. 
 
 Ail Crucible Furnace. — An ordinary brass furnace (q.v.) as distinguished 
 from a reverberatory furnace, in which metal is melted without the use 
 of crucibles. 
 
 Air Cylinder. — The air pressure cylinder, or the cylinder in which the air 
 is compressed in an air compressor. The term is used to distinguish it 
 from the steam or other cylinder by whose agency the compression ia 
 effected. 
 
 Air Engine. — See Hot Air Engine. 
 
 Air Furnace. — A term denoting generally any furnace in which no arti- 
 ficial blast is employed. Reverberatory and brass furnaces therefora 
 come under this designation. 
 
 Air Gate. — A riser (q.v.). 
 
 Air Hole. — A small hole drilled in the closed metal moulds used for 
 pressing cup leathers (q.v.) and simQar works, as a provision for the 
 exit of the air, which, but for this precaution would become com- 
 pressed, and prevent the complete contact of the joints. Also when 
 shafts or pins are driven into bored holes closed at one end, air holes 
 are provided in the closed ends. 
 
 Air Jet. — A jet or blast of atmospheric air introduced into a gas producer 
 to effect a more complete combustion of the fuel, and an increase in the 
 volume of the combustible gases. 
 
 Air Pump. — A pump employed with condensing engines, both of the 
 marine and land types, for the purpose of pumping out the water of 
 condensation which accumulates in the condenser. Since the air min- 
 gled with the condensed water is exhausted by the same means, and 
 a vacuum is thereby produced, the term air pump is employed. Air 
 pumps are worked from an eccentric in oscillating engines, and from a 
 rocking lever in engines of the inverted cylinder type. 
 
6 DICTIONARY OF TERMS USED IN 
 
 Air Eeceiver. — An intermediate reservoir of air placed sometimes iu the 
 course of tHe blast main, between tlie blast furnace and the blowing 
 engines, in order to render the blast pressure uniform. Air receivers 
 are not required when the blast mains are long, and of large capacity * 
 nor when two engines are employed in alternate strokes. 
 
 Air Regenerator. — The regenerator (q.v.) through which atmospheric 
 air passes to be heated on its way to the furnace hearth of a reheating 
 or steel melting furnace. It is larger than the corresponding gas re- 
 generators. 
 
 Air Spaces. — The openings between the fire bars of engine boilers are 
 termed the air spaces. It is essential that these should not be too con- 
 tracted, else the bars wiU become unduly heated and twisted out of 
 shape. 
 
 Air Tap. — A tap fixed in the air pipe in hot- water apparatus, to allow of 
 the escape of air from the series, which without this means of exit 
 woiild accumulate therein. The air tap is placed at the highest point 
 in the series of pipes. Air taps in pumps and engines are called pet 
 cocks (q.v.). 
 
 Air Thermometer. — See Thermometer. 
 
 Air Vessel.— A domed, globular, or egg-shaped vessel, attached to force 
 pumps, long suction and delivery pipes, and hydrauKc rams, for the 
 equalisation of the flow of the liquid. The air which becomes en- 
 tangled in the pipes and mingled with the water is driven into the 
 vessel, and accumulates in its upper area under pressure, becoming an 
 elastic cushion or buffer tending to neutralise the shocks due to the 
 reversal of suction and delivery. Pet cocks (q.v.) are necessarily at- 
 tached to all air vessels. 
 
 Ajutage. — See Adjutage. 
 
 Alder {Alnus glutinosa). — A genus of plants of the natural order Betul- 
 acem. The wood is of a reddish-yeUow colour, and soft. It is used 
 for friction-blocks, for patterns occasionally, and in parts of wooden 
 pumps, being but slightly affected by moisture. Sp. gr. "Se. A cubic 
 foot weighs 34-9 lbs. 
 
 Algebraical Signs, or Symbols. — Conventional combinations of figures, 
 letters, signs, brackets, &o., by which certain processes in arithmetical 
 and geometrical calculations are indicated and understood. 
 
 Alignment. — This term signifies the linear accuracy, uniformity, or coinci- 
 dence of the centres of the fast and loose poppets of a lathe. It is also 
 applied to the axial continuity of shafting and shaft bearings in general. 
 
 Alligator Shears, or Crocodile, or Cropping Shears. — Shears used for 
 cutting off puddled bars in lengths suitable for piling, and also the 
 crop ends of bars in general. There is a fixed lower jaw, and an upper 
 movable jaw, whose fulcrum is set at the inner end of the cutting 
 portion. Behind the fulcrum the lever is prolonged, and attached to a 
 connecting-rod which receives its oscillatory movement from a crank or 
 eccentric. 
 
 Alligator Squeezer, or Crocodile Squeezer. — A form of squeezer used for 
 the expidsion of the cinder from, and the consolidation of the puddled 
 ball. An upper jaw, pivoted at one end, is alternately elevated and 
 depressed at the other by an arm worked from a crank. Between this 
 and the lower fixed jaw the puddled ball is operated upon. The 
 specific term is given it by reason of the serrations which are imparted 
 to the upper jaw for the purpose of increasing its bite. Double aUi- 
 gator squeezers are also made, containing two pairs of jaws. 
 
MECHANICAL ENGINEERING. 7 
 
 All Mine Pig. — Pig iron of tte ordinary Mnd which is smelted entirely 
 from ore, as distinguished from ciader pig (q. v.) . 
 
 Alloy. — A homogeneous combination of two or more metals, effected by 
 fusion, for the purpose of obtaining certain quaUtiea more suitable for 
 special purposes than those possessed by the original constituent metala 
 themselves. 
 
 Alternate Cones. — -When two equal cones are arranged on parallel shafts, 
 with their bases facing in reverse directions, they are said to be alter- 
 nate, and their mutual function is the production of variable motion by 
 means of a shifting belt made to travel from end to end. 
 
 Alternate Stresses. — See OsciHatrng Stresses. 
 
 Alumina.— Symb. AI2 O3. Sp. gr. 3-9. The only oxide of the metal 
 aluminium. It is the main ingredient in emery, and is an essential 
 constituent of aH clays, determining their basic character, and suita- 
 bility for furnace linings. 
 
 Aluminium Symb. Al. Sp. gr. 2-6. Comb, weight, 27-3. A white 
 
 malleable sHvery-looVing metal, unaffected by the atmosphere. It is 
 a widely diffused metal, existing never in the free state, but in 
 combination with sOicou and oxygen, in which condition it enters into 
 the essential formation of all clays. The uses of aluminium as a 
 metal are restricted owing to the cost of extraction. 
 
 Aluminous Bricks. — Fire-bricks whose basis is alumina. They are 
 employed in those portions of hearths and furnace linings where con- 
 tact between the bricks and metaUio oxides would occur, silica bricks 
 being unsuitable for use in these situations. 
 
 American Eock Elm. — See Elm. 
 
 Analysis. — The determination of the percentage proportions of the 
 elements existing in a compound material. The analysis is then said 
 to be quantitative. Qualitative analysis simply demonstrates the 
 presence of certain elements by their reactions on other elements or 
 bodies, without determining their relative proportions. Analysts are 
 employed in aU large iron and steel works. 
 
 Anchor. — A chaplet (q.v.). 
 
 Anchor Bracket. — A bracket, or block, to which the fast end of a brake- 
 strap, or that farthest away from the lever, is attached. 
 
 Angle. — An angle is formed by the inclination of two lines towards one 
 another. The angle is plane, if the lines are straight ; curvilinear, i£ 
 the lines are curved. A right angle is formed where one line is per- 
 pendicular to another, an acute angle when the meeting lines form less 
 than a right angle, an obtuse angle when they make more than a right 
 angle. The dimensions of angles are given in degrees of arc included 
 by the converging lines. 
 
 Angle Bearing. — ^A crank-shaft bearing attached to an engine bed, the 
 centre line of its joint being placed at an angle of about 4o° with the 
 bed, the purpose of which is to effect that disposition of the metal best 
 calculated to withstand the strains due to the motion of the crank and 
 connecting-rod. 
 
 Angle Board. — A board upon which pattern-makers plane their angles 
 and hoUows (q.v.). It is traversed longitudinally with vee'd grooves 
 of different depths to suit angles of different sizes, in which grooves the 
 stuff is laid while being planed, a transverse strip near the end acting 
 as a stop. 
 
 Angle Bracket. — K bracket, two of whose faces abut against the angular 
 faces of a structure, while the third face or hypothenuse forms an 
 
8 DICTIONARY OF TERMS USED IN 
 
 angle theremtli of 45° or otherwise. Angle brackets are of cast iron of 
 various designs, or are built up -with angle irons and plates, and are used 
 as stays, supports, stiffeners, connections, braces. 
 
 Angle Chuck. — ^An angle plate (q.v.) 
 
 Angle Iron. — Angle irons are rolled malleable iron bars, whose section is 
 liat of the letter |_. Their cross sectional dimensions are given as the 
 widths of each side, and their thicknesses, thus ; — 3 in. by 4 in. by J in. , 
 or 3 in. by 3 in. by f in. as the case may be. Angle irons are equal 
 sided when the two webs are of equal width, as 3 in. by 3 in. by f in. ; 
 unequal sided when one web is wider than the other, as 2 in. 
 by 8 J in. by -^ in., or 5 in. by 4 in. by J in. ; square edged when the 
 outer edges are square in section instead of rounding, the last being 
 most commonly the case ; obtuse angled when the two webs are 
 not at right angles, as is also most usual, but inclined at an obtuse 
 angle ; round backed when the angle formed by the meeting of the 
 webs is not sharp but rounded oil instead ; bulbed when the edge of 
 one web is beaded or bulbous in section. Angle irons, or angles, as 
 they are called for shortness, are used in almost all kinds of con- 
 structive engineering works in wrought iron and steel. 
 
 Angle Iron Furnace. — A reverberatory furnace used in boiler-makers' 
 and platers' sheds for the purpose of heating angle irons, preparatory 
 to bending and welding. 
 
 Angle Iron Shears.— Vee-shaped shears attached to shearing machines 
 for the cutting ofi of angle irons, the outside faces of the angle iron 
 being laid in the bottom vee. 
 
 Angle Iron Smith. — A workman in a boiler shop, whose special task con- 
 sists in bending the angle irons of boiler and other plated work, and 
 generally in preparing the angle irons of roofs, bridges, and similar 
 built up structures in readiness for riveting. 
 
 Angle Joint. — A joint made by the meeting of plates at an angle with 
 each other. The plates may either be distinct, or a single plate may be 
 bent round at an angle. Joints of separate plates are coumionly made 
 with angle iron (q.v.) ; but welded joints and flanged joints, the latter 
 being either riveted or bolted, are also usual. 
 
 Angle Motion. — See Canting Motion. 
 
 Angle of Advance. — See Angular Advance. 
 
 Angle of Flexure. — The angle measured in degrees through which torsion 
 deflects a shaft. It varies as the length, and inversely as the diameter. 
 
 Angle of Friction. — See Angle of Eepose. 
 
 Angle of Inclination. — The angle which the thread of a screw makes with 
 ttie axis of its body. 
 
 Angle of Belief. — The angle formed between the back or lower part or 
 face of a cutting tool, and the face of the material upon which it 
 operates. An angle of relief is necessary to prevent the setting up of 
 undue friction or grinding action between the tool and the work. It 
 varies from about 3° in some metal-cutting tools to 25° in planes for 
 wood working. 
 
 Angle of Eepose, or Argle of Friction. — The angle of a plane surface 
 incliued relatively to the horizon, upon which a body will, under 
 specific conditions, just begin to slide. It varies widely with the 
 nature of the particular materials placed in contact and with the pre- 
 sence or absence of unguents. 
 
 Angle of Upset. — ^The angle which the longitudinal centre line of the 
 upper works of 3. balance qrane of the portable type makes with the 
 
MECHANICAL ENGINEERING. 9 
 
 longitudinal centre line of the truck -when it would just begin to upset 
 or overturn -with the weight of the load. See Blocking Girders, Eail 
 Chps. 
 
 Angle Plate, or Angle Chuck. — A special machine part or adjunct, of 
 cast iron, being formed of two ribs of metal, standing at right angles 
 with each other, and pierced with slot holes for the reception of bolts. 
 Angle plates are used for the attachment of various work to the teds 
 of planing machines and shaping machines, and to the chucks or beds 
 of lathes, one face being bolted to the bed or chuck, the other receiving 
 the work which is to be operated upon. 
 
 Angles. — Strengthening pieces running round the angular portions of 
 castings. HoUows (q.v.) answer the same purpose and have a neater 
 appearance. Angle irons (q.v.). 
 
 Angles of Cutting Tools, or Cutting Angles. — These are measured between 
 the surfaces of the materials upon which they operate, and their cut- 
 ting faces. They vary from about 15° in spokeshaves to 120° in 
 broaches. 
 
 Angular Advance. — The angle which the centre of an eccentric sheave 
 makes with a line which is set 90° in advance of the crank-pin. The 
 amount of the angular advance governs the extent of the lap (q.v.) and 
 lead (q.v.) of the valve. 
 
 Angular Brace. — A drilling brace which is jointed to permit of the drill- 
 ing of work at an angle in confined situations. 
 
 Angular Deflection.— Equivalent to the angle of flexure (q.v.). 
 
 Angular Displacement. — Is expressive of the distance travelled by a body 
 which is moving in a circle, the distance being given in angular 
 measure of the radii of the moving body. 
 
 Angular Fence. — See Fence. 
 
 Angularity of Connecting-rod. — See Obliquity of Connecting-rod. 
 
 Angular Pattern Die-Stock. — That form of die-stock in which the 
 handles are placed at an angle with the longitudinal axial centres of the 
 dies, in order to permit of the set-screw wMoh tightens the dies thrust- 
 ing in the line of their axial centres. 
 
 Angular Thread. — A screw thread whose cross section is that of a 
 triangle, as distinguished from a square thread. 
 
 Angular Velocity. — A body travelling in a circle moves through a certain 
 distance away from its starting point in one unit of time, or say in 
 one second. If lines are drawn from the extreme points of its travel 
 to the common centre of its radii, a definite angle is enclosed thereby. 
 The angular velocity is measured in terms of this angle, not in degrees, 
 but in the ratio which the arc described in one second bears to the 
 radius. 
 
 Anhydrous. — Free from wat€r, that is not only free from waterin a state of 
 mechanical mixture, but also as chemically combined. Unslaoked lime, 
 for example, Ca 0, is anhydrous ; but mixed with water, chemical com- 
 bination takes place, and Ca HO results. Compounds of this kind 
 are then said to be hydrated. Thus brown haematite is a hydrated 
 ferric oxide Fea O3 SHj O. The term auhydi'ide is used to designate 
 an anhydrous substance ; as for instance, carbonic acid, or carbon 
 dioxide, is very properly termed carbonic anhydride CO2, since an acid, 
 strictly speaking, must contain water. 
 
 Anhydrous Tar. — Tar which has been boiled to expel the water. It is 
 mixed with burnt dolomite (q.v.) to form a paste for the lining of Ees- 
 eemer converters (q.v.). 
 
10 DICTIONARY OF TERMS USED IN 
 
 Animal Cila. — Lubricating oils for maohinery obtained from animal 
 souroea, and being found in tie adipose tissues, — the principal being 
 sperm, ordinary -whale, neats-foot, seal, and though not popularly 
 termed oils, the solid fats, lard, taUow, &c. They are aU highly valu- 
 able to the engineer for purposes of lubrication, and are noted under 
 their several headings. Excluding those which are erroneously termed 
 the fish oils, as sperm, whale, seal, the animal oils do not dry (see 
 Drying OUs), and therefore do not gum (see Gumming), but they decom- 
 pose and generate fatty acids which corrode the metal work with which 
 they come in contact, and produce also residual deposits (see Glutting). 
 Of the animal oils, sperm and taUow are those most largely used, and 
 when obtained pure, are excellent types of lubricants of light and 
 heavy body (see Body) respectively ; but the tendency is now rather 
 towards the employment of compound oils (q.v.). 
 
 Animal Power. — Varies with the mode of its application, and its period of 
 duration. It is estimated as units of work (q.v.), or as a definite task 
 prolonged through a definite time. 
 
 Annealing. — The subjection of materials which are either naturally 
 brittle and non-elastio, or which have been rendered so by necessaxy 
 processes in (iieir manufacture, or by fatigue (see Fatigue of Materials), 
 to the action of long-continued heat, the effect of such heating being 
 to rearrange the ultimate molecules. The material thus becomes more 
 homogeneous and tougher, and consequently better able to withstand 
 strain and shock than it was previous to annealing. Steel castings, 
 hammered works, old chains, and rods which have been a long time in 
 use, and a multitude of other articles are subjected to the annealing 
 process. Plates and bars newly rolled, and whose fibrous condition has 
 therefore never depreciated or been subject to strain and fatigue, are, 
 on the contrary, subject to a diminution ot tensile strength by anneal- 
 ing. Hence the properties of homogeneity and ductility are in most 
 instances obtained by a direct sacrifice of rigidity and tenacity. See 
 also Tests. 
 
 Annealing Oven. — A section of a crucible cast-steel melting furnace, in 
 which the crucibles are slowly baked after preliminary drying. One 
 end of the melting house is provided with rectangular ovens or chambers 
 of fire brick, each holding from twenty to thirty crucibles, which have 
 been previously dried and seasoned. The crucibles are placed mouth 
 downwards upon fire bars covered with fuel, and their interspaces 
 filled up with small coke. They are then slowly raised to redness, and 
 afterwards allowed to cool to a black or low red, previous to removal 
 to the melting holes. The term is properly applied to any furnace 
 used for anneaUng. The wheels of railway cars are, in America, made 
 of chilled cast iron, and are cooled in annealing ovens or pits of various 
 forms. 
 
 Annealing Pots. — Pots of wrought or cast iron, or steel, varying in size 
 and shape with the work which requires annealing, their function being 
 the preservation of plates, sheets, &c., from the action of the atmo- 
 sphere during the process of annealing. They are run into an annealing 
 furnace, and exposed to the action of the heat for several hours or 
 days. The pots are hermetically closed and properly luted to preserve 
 the contents from oxidation. Plates of maUeahle iron are annealed in 
 pots measuring 10 ft. in length, and 3 ft. 6 in. in width, and o ft. 6 in. 
 in depth ; iron sheets in pots much smaller. Plates remain in the 
 furnaces about 2i hours, and are then withdrawn and allowed to cool 
 
MECHANICAL ENGINEERING. ii 
 
 during a period of four days, still, lioweyer, pi-otoeted from tlie air. 
 Articles in malleable cast ii'on are annealed in cast-iron cylinders about 
 12 in. in diameter, by about 16 in. Mgh, fitted with loose covers. 
 
 Annual Bings. — The circumferential layers of wood seen in a cross section 
 of timber, and which represent the yearly additions to the woody 
 fibres. In good timber the rings are narrow and closely packed, in in- 
 f srior timber they are wide and open, estimated of course relatively to 
 the characteristic and normal growth of the particular timber under 
 consideration. 
 
 Annular Engine. — A steam engine, the cross section of whose cyUnder is 
 that of a ring, the piston being also annular in plan. Being of this 
 form, therefore there are two cylinders, the outer or working one, and 
 the inner cylinder, within which works the cross-head to which the 
 lower end of the connecting-rod is attached. The connecting-rod 
 passes thence upwards to the crank overhead. The communication 
 between the piston and the cross-head is made by two rods passing to 
 prolongations of the cross-head above. The advantage of this engine, 
 which was designed by Maudslay, is the possession of a long connecting- 
 rod in a restricted space. 
 
 Annular Gear. — Circular racks, curb rings, &c., with their pinions. 
 
 Annular Seating. — A seating ring-shaped in plan, upon which a circular 
 pump valve rests. 
 
 Annular Valve. — A circular disc valve which rests upon an annular seat- 
 ing, and which is therefore a hft valve (q.v.). 
 
 Annular Wlieel. — A cog-wheel whose teeth are fixed to its internal 
 diameter ; called also an internal wheel. An annular wheel always re- 
 volves in the same direction as that of its pinion. 
 
 Annular Wind Engine. — A windmill (q.v.). 
 
 Anthracitic Coals. — Hard lustrous non-caking coals, rich in carbon, 
 decrepitating and burning with difficulty, requiring a strong draught 
 for perfect combustion, but giving out an intense heat. They consist 
 almost entirely of free carbon, and their sp. gi'avities range from 
 l'3o to 1*92. Pure anthracite is the hardest coal known, is of a deep 
 black colour, brittle, and clean to the fingers. The anthracitic coals 
 BO called embrace many kinds approaching to the qualities of pure 
 anthracite, but possessing the caking property in slight degrees. 
 
 Anti-fouling Compositions. — See Incrustation. 
 
 Anti-friction Grease. — A general term appHed to mixtures of tallow, 
 pahn oil, plumbago, and other lubricants. 
 
 Anti-friction Metal. — Babbitt's metal (q.v.), or white metal (q.v.), uaed 
 for lining the steps and bearings of shafts and axles, and the faces of 
 slide valves and similar moving parts. So called because of its low 
 coeffioient of friction (q.v.). The term " white brass " is sometimes 
 appUed to anti-friction metal. 
 
 Anti-friction Motion. — Motion, the amount of whose friction is reduced 
 to a minimum by the employment of special mechanism, or of superior 
 lubrication. 
 
 Anti-friction Boilers, — Freely revolving, or live rollers (q.v.), which sus- 
 tain the pressure of a revolving spindle or shaft. The oranlc axles of 
 foot lathes, and the spindles of some light running machines are often 
 furnished with bearings consisting of such rollers. 
 
 Anti-Incrustation. — Relates to the remedies employed for preventing in- 
 crustation (q.v.) in steam boilers. 
 
 Antimony. — SymbolSb. comb, weight 122. Sp.gr. 6-71. A bluish white, 
 
12 DICTIONARY OF TERMS USED IN 
 
 very brittle, and readily fusible metal, whose value consists in the 
 hardness which it imparts to certain alloys of tin and lead, forming 
 white metals. The presence of antimony in wrought iron is injurious, 
 proportions so small as 0'3, or 0'2 per cent, producing both cold 
 shortness (q.v.) and red shortness (q.v.). 
 
 Anti-priming Pipe. — A pipe attached to the steam supply within a boiler. 
 It is furnished with a perforated plate occupying its transverse section, 
 from which the spray driven upwards by the steam is thrown back into 
 the boiler instead of mingling with the steam in the supply pipes. 
 See Priming. 
 
 Antiquarian. — A drawing paper of very excellent quality, measuring 
 53 in. by 31 in. It may be obtained either unmounted, or mounted on 
 brown hoUand. 
 
 Anvil. — The block upon which the operations of smith's work are per- 
 formed. The ordinary anvil is of wrought iron, faced on its upper 
 portion with hardened steel about half an inch in thickness. Smiths' 
 anvils weigh from one hundredweight upwards. For some special 
 classes of work anvils are made of cast iron, either chilled or faced with 
 cast steel. Small steel anvils of a few pounds weight only are also 
 made for bench use. 
 
 Anvil Block. — A massive block of cast iron which is placed beneath the 
 anvils of steam and other heavy hammers, and whose mass absorbs 
 much of the vibration due to the blows. It is embedded in masonry or 
 on concrete, or is laid on piles. 
 
 Anvil Chisel. — See AnvU Cutter. 
 
 Anvil Core. — The main body of a smith's anvil, to which the comers and 
 beak are welded. 
 
 Anvil Cutter, or Anvil Chisel. — A chisel-like tool or set, provided with a 
 shank for fitting loosely into the square hole on the face of an auvU, 
 the cutting edge being uppermost. Iron rods and bars are laid across 
 this, and nicked and cut off, both when hot and cold. 
 
 Anvil Head. — The upper portion of the body or core of a smith's anvil. 
 
 Anvil Stand. — The square cast-iron frame which supports a smith's anvil. 
 
 Aperture. — SpeoifioaUy, denotes the extent of area of a discharging orifice 
 (q.v.), or mouthpiece (q.v.) for liquids. 
 
 Apex. — The summit of a cone, pyramid, or conical figure generally. In 
 engineering, it signifies the points of the triangles in a lattice, or Warren 
 girder, or those portions of the braces which intersect with the flanges, 
 either at top or bottom. 
 
 Apple Tree (Pyrus mains). — A tree of the natural order Hosaccai, sub 
 order Foma. It produces a fine, close, straight-grained, hard wood, of 
 a reddish brown colour. Its chief use in engineering is for the cogs of 
 mortice wheels, for which, when thoroughly seasoned, it stands unri- 
 valled. The crab apple is mostly used. Sp. gr. -73. A cubic foot 
 weighs 45 '5 lbs. 
 
 Appolt Oven. — See Coke. 
 
 Apprentices. — Are usually bound until the age of 21 years, commencing at 
 14, 15, or 16, seldom later. The apprenticeship system is not universal 
 many of the best firms refusing to take them. The alternative arrange- 
 ment then is that a lad shall come into the shop, paying no premium 
 but be taught his trade so long as he contiaues to behave himself, and 
 that this tacit engagement shall be terminable at pleasure on either 
 side. Actually the lads usually stay out the ordinary term, and re- 
 ceive the ordinary wages ; they behave better, learn their trades more 
 
MECHANICAL ENGINEERING. 13 
 
 rapidly, and often receive substantial additions in tlie shape of piece 
 ■work balances. This system is therefore far preferable to the hard and 
 fast e-igagements of the apprenticeship indenture system. 
 
 Approximately. — A word in frequent use when describing the capabilities 
 of machines, and their dimensions, and also specifically, their shipping 
 ■weights (q.v.). In many instances, strict exactitude, if not actually 
 impossible of attainment, is either not requisite, or could only be at- 
 tained by an expenditure of trouble out of proportion to the value of 
 the results. 
 
 Apron. — The vertical fixing in the front part of the slide rest of a sore^w- 
 cutting lathe -which carries the clasp nut (q.v.). The term also desig- 
 nates the vertical slide of a punching or sheariag machine. See also 
 Breastplate. 
 
 Arbor. — A small shaft or spindle. 
 
 Arbor Chuck. — A lathe chuck used for turning the outside diameters and 
 faces of cylindrical -work after the hole has been just bored, the hole 
 fitting over a mandrel or spindle ■which insures concentricity of outer 
 and inner diameters. Engineers usually terra arbor chucks, mandrels 
 simply ; hence the term expanding mandrel (q.v.). 
 
 Arc. — The arc of a circle is any portion of its circumference. 
 
 Arch. — A curved structure designed to resist external pressure. 
 
 Arched Beam. — A beam whose shape is that of an arch. Used for the 
 support of roofing. 
 
 Arch Head. — The ends of the timber beams of those pumping-engines 
 ■which were constructed previously to the introduction of parallel 
 motions (q.v.). The ends of the beams were simply struck to a radius 
 aroujid which the chains attached to the piston and the pump-rods 
 accommodated themselves. 
 
 Arcliimediaii Drill, or Persian Drill. — A drill stock whose shank is 
 formed into a quick multiple thread, over which a nut, to which a 
 handle is attached by means of a hinge, slides freely. By the sliding 
 of the nut up and do^wn the thread the shank is rotated from left to 
 right, and from right to left alternately — the motion of the drill being 
 therefore of a reciprocal character. Pressure is applied to a knob at the 
 end of the shank. This drill is suitable only for light work, centering, 
 model making, &c. 
 
 Arch Joint. — The joint plates of a rule which are hoUowed into the form 
 of an arch. 
 
 Arc of Approach. — In toothed gearing, is that portion of the arc of 
 contact (q.v.) along which the flank of the driving-wheel is in contact 
 ■with the face of the driven wheel. 
 
 Arc of Contact. — In toothed gearing, is the space included between those 
 two points where the contact of a single pair of wheel teeth begins and 
 ends, the measurement being taken on the pitch line to which those 
 points are projected. The larger the arc of contact the more perfect 
 the bearing of the teeth, and the greater the number of teeth in gear 
 at one time. In belt gearing, it is the length of arc measured in 
 degrees, through which a belt is in actual contact with its pulley. Thus 
 an arc of contact of 180° signifies that the belt is in contact with the 
 pulley around half of its circumference. 
 
 Arc of Recess. — In toothed gearing, is that portion of the arc of contact 
 (q.v.) through which the face of the driving-wheel acts upon the flank 
 of the driven wheel. 
 
 Arc Pitch, — The pitch of wheel teeth measured between the pitch points 
 
14 DICTIONARY OF TERMS USED IN 
 
 arouud the arc of the pitch line, aa distinguished from chord pitch 
 
 Are. — A French measure of surface, being equivalent to one hundred 
 square metres, or one square decametre. Its English equivalent is 
 1076-41 square feet. See Centiare. 
 
 Area. — The superficies, or superficial extent of a figure. TCn owing the 
 bounding dimensions of any figure, the area can be calculated there- 
 from by simple mensuration. There are certain relations subsisting 
 between the areas of figures which it is convenient to remember. 
 
 Argillaceous Iron Ore. — See Clay-band. 
 
 Arithmetical Mean.— The number which is equally distant between two 
 others. 
 
 Arithmetical Progression. — See Progression. 
 
 Arm. — A term signifying a rod, or a radial bar of metal. Thus we speak 
 of the arm of a lever or of a wheel. 
 
 Arsenic. — Symbol As. comb, weight 74'9. A non-metallic substance, 
 though closely alUed to the metals, whose presence in small quantity 
 in iron is valuable for the purpose of chilliDg (q.v.). It likewise in- 
 creases the hardness of steel, though diminishing its toughness. Arsenic 
 in combiaation with oxygen as arsenious acid Asu O3 is a bye product 
 also in some smelting operations. 
 
 Articled Pupil. — See Pupil. 
 
 Artificial Grindstone. — See Grindstone. 
 
 Artificial Seasoning. — Timber is seasoned artificially by exposing it in 
 a suitable chamber to a current of hot air, delivered either from a fan, 
 or by a natural draught. Small blocks can be roughly and quickly 
 seasoned by boiling them in water for two or three hours, and then 
 allowing them to dry. 
 
 Asbestos. — A mineral compound composed chiefly of sihca and magnesia, 
 existing as varieties of hornblende, augite, and serpentine. The com- 
 mercial asbestos comes from Italy and Canada. It is a silky, fibrous 
 substance, owing its value as a heat-resisting body to the presence of 
 silica. It is used in various preparations for making the steam joints 
 of flanges, as yarn for glands, and as grease for lubrication. For the 
 latter purpose it is made into a paste and termed asbestohne. Although 
 but a few years have now elapsed since its introduction for these pur- 
 poses, it is rapidly supplanting the hempen and other forms of packing, 
 and the millboard hitherto in use. 
 
 Ascending Eoom. — See Lift. 
 
 Ash (Fraximis excelsior). — Sp. gr. 0-84. Alight-coloured, coarse-grained 
 wood, employed for the spokes and feUoes of wheels, for smith's 
 hammer-shafts, for the rings upon which the cleading of boilers is 
 fastened, and generally in work requiring great flexibility combined 
 with moderate strength. Ash becomes more brittle with age. Its 
 idtimate tenacity averages about 17,000 lbs. per square inch of cross- 
 section. A cubic foot weighs fi2-4 lbs. 
 
 Ash Pan. — A pan placed underneath the furnace grate or firebox in 
 boilers of the portable type, to receive the falling ashes. 
 
 Ash Pit. — That portion of the furnace of a stationary boiler lying below 
 the fire bars, and immediately in front of the furnace doors, which 
 receives ashes that fall through the bars, and through which much of 
 the draught necessary for combustion enters. 
 
 Ash Plate.— A term sometimes applied to the back plate of a boiler 
 furnace. 
 
MECHANICAL ENGINEERING. ij 
 
 A-Standard. — A vertical framing shaped as its name implies, and used as 
 an attachment, either singly or when placed in pairs for the parts of 
 pumps and engines. 
 
 Atlas Drawing Paper. — A dra-wing paper measuring 33J in. by 26 in. 
 
 Atmosphere. — See Atmospheric Pressure. 
 
 Atmospheric Engine. — See Single-acting Engine. 
 
 Atmospheric Gas Engine. — See Gas Engine. 
 
 Atmospheric Line. — The line on an indicator diagram which divides the 
 steam area above from the vacuum area below, and which corresponds 
 with the height of the pointer before the indicator-cock is opened. 
 
 Atmospheric Pressure. — The pressure of the atmosphere is a vital factor 
 in all questions relating to the pressures in engine cylinders, pumps, 
 &c. The barometer is the instrument by which it is measured. Engi- 
 neers also measure the amount of atmospheric pressure present in con- 
 densers, boilers, engine cylinders, &c., by means of the vacuum-gauge 
 (q.v.). Its pressure is equal to 14'7 lbs. at sea level, equivalent to that 
 of a column of mercury at 32° F.,29'022 in. high, or a column of water 
 at 62° E. 33-9 ft. high. 
 
 Atmospheric Pump. — See Lift Pump. 
 
 A-tiuss. — A roof truss whose outhne is that of the letter A spread out. It 
 is either a simple truss, consisting of two rafters and a tie beam only, 
 or it is a braced truss. 
 
 Attachment Screw. — A screw employed for fastening portions of mechan- 
 ism together, in contradistinction to adjustment screws (q.v.) and guide 
 screws (q.v.) 
 
 Anger. — A wood-boring instrument of large size for bolt holes. Augers 
 are either "shell" or "twisted," the former being the stronger, the 
 latter boring more accurately. 
 
 Australian Copper. — Copper pyrites (q.v.) and malachite (q.v.) imported 
 from Australia. 
 
 Autogenous Soldering. — The union of metals effected without the inter- 
 vention of solder, by the mere ftision of the surfaces in contact. See 
 Burning on. Welding. 
 
 Automatic. — An action or movement is said to be automatic when it is 
 effected without the direct intervention of the hand, being due to some 
 special portion of the machine designed to effect that action or 
 movement. 
 
 Automatic Expansion. — ^Expansion (q.v.) of steam effected by the gover- 
 nors of an engine, the grade of expansion being diminished when 
 increased work is thrown upon the engine, and vice versd. The advan- 
 tages of its employment are economy of working, regularity of motion, 
 and the maintenance of the full boiler pressure in the cylinders. = 
 
 Automatic Expansion Gear, — The arrangements of gear by which auto- 
 matic expansion (q.v.) is effected. 
 
 Auxiliary. — Small auxiliary engines are usually provided for the supply 
 of boilers with feed water while the larger engine with its pumps is 
 standing idle. Auxiliary parts are carried to sea in case of break- 
 downs. An auxiliary screw or screw-blade is often taken in the event 
 of the fracture of a blade. 
 
 Available Horse-Power. — See Actual Horse-Power. 
 
 Avoirdupois. — The name given to the English system of weights and 
 measures of which the grain and the pound are xmits. The pound is 
 the tenth part of the weight of a gallon of distilled water taken at 6 2° P. 
 and 14'7 barometric pressure. The pound is also equal to 7,000 troy 
 
t5 DTCTIONARY OP TERMS USED IN 
 
 grains. The various -weights and measures are arbitrary quantities 
 having no mutual inter-dependenoe as in the metric system (q.v.) 
 
 Axe. — A ■wood-cutting tool whose cutting edge is parallel "with the axis 
 of the handle, and whose bevels or cutting angles are symmetrical on 
 each side. 
 
 Axial Pitch. — The pitch of a screw or helix measured in a direction 
 parallel with the axis. The term is specially applied to many threaded 
 screws, to distinguish the pitch of a single helix only, from that termed 
 divided axi'd pitch (q.v.). and from normal pitch. 
 
 Axis. — Signifies a central line considered in relation to certain geometrical 
 or mechanical relations. The axis of a cylinder or sphere is the right 
 line which passes through the centre of all the corresponding parallel 
 sections of the same. The axis of a parabola, ellipse, or hyperbola 
 likewise divides the curves symmetrically. See also Axis of Sym- 
 metry, Neutral Axis. 
 
 Axis of Symmetry. — An imaginary central line around which a sym- 
 metrically developed body is formed, and in which the centre of gravity 
 is found. 
 
 Axle. — A shaft which carries the driving, travelling, or truck wheels of a 
 locomotive, railway waggon, or trolly. 
 
 Axle Box. — The complete bearing arrangements for an axle. It com- 
 prises an outer casing of cast iron with internal adjustable brass bear- 
 ings or bushes, and grease or oil chambers. The whole structure is 
 sustained by springs, and guided by horn plates. Axle boxes are called 
 oil axle boxes, or grease axle boxes, as they are constructed for using 
 one or the other lubricant. Also denotes the outer casting only which 
 contains the bearings or bushes for an axle. 
 
 Axle Grease. — A special preparation used for the lubrication of axles. 
 Numerous mixtures are employed into which tallow, palm oil, sper 
 maceti, plumbago, in various proportions enter. 
 
 Axle Guard. — See Horn Plate. 
 
 Axle Keep. — See Keeper. 
 
 Axle Wad — A washer of papier-mache, or of wood, placed in the back 
 part of an axle box, to protect the axle from the entry of dust and dirt. 
 It is divided across the middle with bevelled edges 
 
 B 
 
 B.— See Best. 
 
 Babbitting. — The process of lining bearings with Babbitt's metal (q.v.), 
 or with white metal. 
 
 Babbitt's Metal. — An alloy used for lining the bearing parts of engines 
 and machines which are subject to much friction. There are many 
 inferior kinds of such metal sold, but the proper composition is as 
 follows : 4 lbs. of copper, 12 lbs. of Banca tin, 8 lbs. regulus of anti- 
 mony, and 12 lbs. more of tin while the mixture is in a molten condi- 
 tion. Pour the antimony into the tin, and mix with the copper in 
 a separate pot off the fire. This is termed the hardening, and the 
 actual lining metal is composed of 1 lb. of this mixture to 2 lbs. of 
 Banca tin, so that the final composition is i lbs. copper, 8 lbs. regulus oi 
 antimony, and 96 lbs. tin. 
 
MECHANICAL ENGINEERING. 17 
 
 Back Balance. — ^A oiroular diso or plate, formerly much used, and still 
 employed to a limited extent in tne engines of river and other slow- 
 running steamers, for assisting th,e reversal of the eccentric for forward 
 or backward gear. The eccentric is loose upon its shaft, and the hack 
 balance diso maintains it in equilibrium against the catches or stops. 
 
 Back Centre. — The pivot or dead centre upon which the back or tail end 
 of the mandrel of a lathe headstook runs. 
 
 Back Cut-off Valve. — A sliding plate, moving on the back face of the 
 main slide-valve of an engine for the purpose of regulating the point 
 of cut-ofi for the steam, and by which its grade of expansion is 
 governed. It is worked independently of the main slide from a separate 
 eccentric, and is usually made capable of adjustment relatively to the 
 steam passages in the main slide. 
 
 Back Firing. — The escape of a portion of the gaseous charge of a gas 
 engine at the ports. This is prevented by the rapid closing of the slide 
 immediately after ignition. 
 
 Back Gear. — ^An arrangement of toothed wheels by which the power of a 
 driving-belt is proportionally increased. The term is understood as 
 applying to lathes for metal- turning, and to driUing and other machines 
 of similar character. Taking it as it occurs in the lathe, the main or 
 driving mandrel is hollow, and while its outer portion or quill A carries 
 the driving-cones B and a pinion-wheel C, an inner spindle D carries 
 the mandrel nose and centres and a cog-wheel E. This cog-wheel gears 
 into " pinion F, similar to the one upon the cone spindle, but which 
 runs upon another or back spindle G-, set parallel with the first. This 
 second spindle also carries a wheel H similar to the one E upon the 
 mandrel, and working into the mandrel pinion C. The wheel and 
 pinion on the back spindle are rigidly connected together, and this hinder 
 spindle is capable of receiving a backward movement to throw it out of 
 gear. When out of gear the larger wheel E on the main mandrel is 
 coupled to the cone pulley B on the quill, and the lathe is driven only 
 from the belt, in a direct manner. But when the cone pulley B and the 
 mandrel wheel E are uncoupled, and the wheels of the back spindle are 
 thrown into gear, the lathe is driven through the cones B to the pinion 
 C on the quUl, thence to the wheel H on the back spindle, and through 
 its pinion E back to the wheel E upon the main mandrel. The power 
 gained is calculated ly taking the product of the number of teeth in 
 the pinions and of those in the wheels, and dividing the latter by the 
 former. Treble back gear is made use of for some lathes of special 
 construction, where very slow speeds and great powers are required. 
 
 Back Gear Eccentric. — See Backward Eccentric. 
 
 Back Guys. — The timbers which connect the tops of the masts of derrick 
 cranes (q.v.) with their sleepers. AI.SO the hinder ropes or chains of 
 shear legs. 
 
 Backing Off. — The cutting or bevelUng away of the hinder or "leaving " 
 portion of a screw tap, in order to allow the ' ' entering ' ' or cutting 
 part to work more freely. The effect of backing off is to reduce the 
 amount of friction and consequent grinding between the sides of the 
 tapped hole, and of those portions of the tap which do not actually cut. 
 
 Backing Out. — The running back of a tap or die after the thread has been 
 cut. 
 
 Backlash. — The backward surge of a pair or of a train of toothed wheels 
 when the driving pressure is variable in amount. Its amount is equal 
 to the "clearance" allowance between the flanks of the teeth which 
 
 
 
i8 DICTIONARY OF TERMS USED IN 
 
 are in gear. Excessive 'backlash should he avoided as causing shook 
 and producing much noise. Its remedy is minimum of tooth clearance 
 and regular running. 
 
 Back Link. — The second link which is attached to the beam of a beam 
 engine, or between the main link (q.v.) and the centre of the beam, in 
 the arrangement of levers known as parallel motion. 
 
 Back Flate. — ^A plate of cast iron bolted against the back or outer edges 
 of the bars of moulding boxes which have to be put in the foundry pit 
 for casting vertically. The purpose of the employment of back plates 
 is to prevent the pressure of the head of liquid metal from forcing the 
 sand outwards, and so allowing the metal to run away from the mould. 
 
 Back Pressure. — The pressure on the piston due to the steam left in the 
 end of an engine cylinder and in the exhaust passages on the com- 
 mencement of the return stroke, and which offers a certain amount of 
 resistance to the piston. The amount of back pressure can never be 
 less in non-condensing engines than the atmospheric pressure, nor in 
 condensing engines than that of the imperfect vacuum present in the 
 condenser. It is always more than these because of the friction which 
 the passages oppose to the steam ; hence passages should be short 
 and direct, if long and tortuous they injuriously increase the back 
 pressure. The amount of back pressure should not exceed from 2 to 3 
 pounds per square inch, reckoned above the atmosphere in non-con- 
 densing engines, and above the vacuum-gauge in condensing engines. 
 Also termed counterpressure. 
 
 Back Pressure Valve. — A valve which is used for preventing the reflux 
 of fluid or liquid in a pipe. Hence it is a retaining, or foot valve (q.v.). 
 Wlien applied to a steam boiler it is termed a check- valve (q.v.). 
 
 Back Saw. — Any saw whose plate or blade is stiffened with a metaUio 
 back. Tenon and dovetail saws are back saws. 
 
 Back Shaft. — The shaft which runs at the rear of a self-acting lathe along 
 its whole length, and through which motion is transmitted from the 
 headstock to the slide-rest. It is used for sliding and surfacing only, 
 and is capable of reversal for traversing the saddle up or down. See 
 Eeversing Motion. 
 
 Back Stay. — See Back Steady Rest. 
 
 Back Steady Best. — A lathe traversing rest, distinct from the slide rest, 
 used for ihe support of long shafts, and of slight cylindrical pieces of 
 work generally which are being turned up. A common form consists 
 of an internal bearing or angle block attached to a vertical carrier or 
 bracket, the bearing being adjusted both above and behind the shaft so 
 that the latter lies in its angle. The bracket is bolted to the saddle of 
 the sUde rest, and travelling therefore with it, follows the cutting tool 
 and provides a constant support to the shaft immediately behind the tool 
 where the tendency to spring is greatest during the turning process. 
 Also called a back stay ; or back following stay ; or following steady. 
 
 Backward Eccentric. — The eccentric which opens the slide-valve to steam 
 supply when its engine is required to run backward. Also called back 
 gear eccentric. 
 
 Backward Gear. — An engine is said to be in backward gear when the 
 relative arrangement of eccentrics, slot links, levers, and rods is such, 
 that the engine wiU on the admission of steam, run backward. 
 
 Baffle Plates, or Bafflers — Plates of metal so disposed in the fire-boxes 
 and flues of steam boilers as to throw the flame and hot gases against 
 the surfaces most suitable for the economic and complete generation of 
 
MECHANICAL ENGINEERING. 19 
 
 steam — that is against the best heating surfaces. Also a plate of thia 
 sheet iron attached at a little distance away from the inner face of a 
 furnace door to admit air ahove the fire, the air entering through a re- 
 volving or sliding grid in the door. The use of the plate is also to 
 prevent burning and buckling of the door, the efficiency of the protec- 
 tion being due to the interposition of the film of air between the door 
 and the baffle plate. 
 
 Bafflers.— See Baffle Plates. 
 
 Balance. — In order that bodies should balance each other there must be 
 eqnihbrium or equality of moments ; that is, the svim of the forces 
 tending to move any body in one direction must be equal to the sum of 
 the forces tending to turn the body in the opposite direction. 
 
 Balance Ball. — A spherical weight which is attached to a crane chain 
 just above the hook for the purpose of overhauling it. It fulfils the 
 same purpose as a pear weight (q.v.), but is employed for the smaller 
 cranes chiefly. 
 
 Balance Box. — The box which counterbalances the load lifted by a 
 balance crane. It is usually a cast-iron box loaded with small weights 
 or "kentledge." 
 
 Balance Crane. — A crane in which the load is counterbalanced by a 
 weight attached to the tail or hinder end, the amount of weight de- 
 pending on the radius at which the load is lifted, the length of the tail, 
 and the disposition of the mass of the crane itself. Balance cranes are 
 made both fixed and portable, and are worked by hand or steam. See 
 also Blocking Girders. 
 
 Balance Cylinder, or Balancing Cylinder. — A small steam cylinder at- 
 tached to the top of the slide-chest in some large marine engines, which 
 performs the double function of acting as a guide to the valve-rod, and 
 of relieving the valve gear of the weight of the valve and valve-rod. A 
 piston moves in the cylinder, and is open to steam below derived from 
 the valve chest and to the condenser vacuum abovs. The valve there- 
 fore moves in equilibrium. Also a small steam cylinder or cylinders at- 
 tached to the bottom cover of large marine engines for the purpose of 
 counteracting the dead weight of the piston. A rod passes from the 
 piston of the main cylinder to the piston of the balance cylinder, and 
 the pressure of steam introduced underneath the latter is the counter- 
 balancing agency. 
 
 Balanced Crank. — See Disc Crank. 
 
 Balanced Valve. — An equilibrium valve (q.v.). 
 
 Balanced Wheel. — A rapidly rotating wheel which is balanced by the 
 turning of its rim true, and by the drilling of holes in or near the rim 
 if found necessary, so that the wheel turns equally free or comes to 
 rest in any position indifEerently. All high-speed wheels and pulleys 
 are, or should be, thus balanced. The term is also applied to a wheel 
 which is counterbalanced by the addition of a weight to a portion of 
 the rim which lies opposite to another part with which it is connected, 
 such as a crank or connecting-rod, its function being to balance or 
 counterpoise the weight of the crank or connecting-rod. 
 
 Balance Spring. — See Spring Balance. 
 
 Balance Weight. — (1) The weights placed in the driving-wheels of locomo- 
 tives are termed balance weights. (2) A weight slid over the end of a 
 lever and attached thereto by a set screw, its use being to counter- 
 balance a moving part. The function of the weight is not always that 
 of counterbalancing merely, but also in addition the lifting of the 
 
20 DICTIONARY OF TERMS USED IN 
 
 workiugpaTt — tie lever, drill, brake, chisel, or whatever it may happen 
 to be — out of or away from its place without the intervention of the 
 workman or attendant. (3) Applied generally to any weight used as a 
 counterpoise, such as on the driving-wheel of a foot lathe, or on a 
 crank, or on reversing gear. (4) Also the small weights put into a 
 balance box (q.v.). 
 
 lalancing. — The removal of irregularities in weight from those portions 
 of a revolving body where it is in excess, in order to equahse the 
 strains upon it due to momentum and centrifugal force. Hence 
 rapidly revolving pulleys and wheels are, where possible, turned all 
 over. When that is not practicable they are hung on a free spindle, 
 and the weight of the heaviest sides reduced in succession by drilling 
 out holes, or in other ways removing superfluous metal. Such a pulley 
 or wheel is then said to be balanced. Another mode of balancing is 
 when a balance weight (q.v.) is attached to a driving or a fly-wheel, 
 to coTjnterbalauce the mass of a crank, or an eccentric sheave, or similar 
 projecting portion on the axle. AJl good mechanism and rapidly 
 revolving parts are thus balanced. 
 
 Balancing Cylinder. — A balance cylinder (q.v.). 
 
 Balk. — A squared log of timber. 
 
 Ball. — The mass of spongy puddled iron which is just ready to be with- 
 drawn from a puddling furnace to be passed to the squeezers or ham- 
 mer, as the case may be. A puddled ball weighs from 60 to 80 pounds. 
 
 Ballast. — The foundation for permanent way laid on the formation level 
 (q.v.). It is about 1 ft. 7 in. in depth, and is variously composed of 
 gravel, shingle, broken brick, burnt clay, or slag. It requires to be 
 hard, to allow of the passage of rolling stock without the crushing of 
 its materials, and well drained and porous to prevent the accumulation 
 of water. The material which is placed in the balance box of a balance 
 crane is also called ballast. It may consist of iron balance weights, or 
 blocks of stone, or masses of rubble or scrap iron. 
 
 Bailer. — ^The workman at the balling or reheating furnace (q.v.). 
 
 Balling. — See Balling Up. 
 
 Balling Furnace. — The puddling furnace in which the process of balling 
 (q.v.) is performed. 
 
 Balling Tip, or Balling, — The last stage of the puddling process in 
 which the pasty mass of iron is gathered together in lumps or balls on 
 the furnace bed, being sufficiently self-coherent to be rolled towards 
 the bridge of the furnace, to be withdrawn through the working door 
 for subsequent shingling. 
 
 Ball Joint. — A universal joint, sometimes employed for piping. The 
 globular end is retained in its hollow seating with a gland screwed over 
 it. This form of joint is used with the connections of centrifugal and 
 other pumps. 
 
 Balloon Boiler, or Haystack Boiler. — A squat circular vertical boiler of 
 large di m ensions, with a hemispherical crown. It is fallen nearly into 
 disuse. 
 
 Ballooning. — The Htting up of the fine impalpable mud and scale in 
 steam boilers to the surface of the water by the ebullition of the bubbles 
 of steam. In large boilers, scum troughs (q.v.) are provided for the 
 collection of this sediment. 
 
 Ball Pane. — See Pane. 
 
 Ball Valve. — A lift- valve of globular form which closes an annular seat- 
 ing. It is employed in quick-running force pumps, and its advantage 
 
MECHANICAL ENGINEERING. Ji 
 
 consists in tlie fact that as it continually sMf ts its position on its axis 
 its wear is nearly uniform. It is enclosed in a cage open on four 
 sides, tlie cage being sufficiently Mgh to permit the requisite amount 
 of lift, the internal height of the cage limiting the Hft of the ball. The 
 cage consists of an upper and lower portion, which are screwed together 
 after the insertion of the hall. 
 
 Banca Tin. — Straits tin (q.v.). It is sold in blocks weighing from 40 Ihs. 
 to 120 lbs. each. 
 
 Band — ^A term which taken in its strictest sense designates a flat belt, 
 though both terms are loosely applied in a general way to the cords 
 and belts used for driving purposes. See Belt. 
 
 Banding, or Bonding. — The embracing and securing of the lagging (q.v.) 
 around steam cylmders and boilers with broad bands of sheet brass or 
 of hoop iron. 
 
 Band Pulley.— See Pulley. 
 
 Band Saw. — An endless saw mnning on revolving pulleys, and used for 
 cutting curved work both in wood and iron. A tension apparatus 
 (either a spring or a weighted lever) maintains the saw at its proper 
 degree of strain, and a canting table allows of the work being sawn 
 either square or upon the bevel. Band saws vary from ^ in. to 
 4 in. and 5 in. in width, and travel on an average at the rate of 4,000 ft. 
 per minute. 
 
 Banjo Frame.— A bow connecting-rod (q.v.). 
 
 Banking Tip. — (1) The beating down of green coal (q.v.) around the central 
 portions of a smith's fire, or around a piece of forging laid therein. 
 (2) The covering up of the fire of an engine boiler in order to check or 
 moderate the formation of steam for a time, either because ihe 
 engines have to be slowed down or stopped for a while. Banking up 
 is effected by pushing the fuel back towards the bridge (q.v.) and 
 covering it over with small coal, wetted and beaten down. 
 
 Bar. — (1) The bridge of metal which separates a valve port or steam 
 passage from its adjacent port in the valve faces of steam cylinders. 
 Also the similar bridges in double and treble ported slide valves. The 
 thickness of the port bars is of httle importance, if the slide valve is 
 acconamodated thereto, but they commonly measure a trifie more than 
 the thickness of metal between the passages. (2) The flat or round or 
 other sections in which wrought iron and steel are sold. They are 
 described under their specific names. The bars are brought to their 
 required shape by rolling. (3) The stays or bridges in foundry mould- 
 ing boxes which afford support to the sand enclosing the pattern. 
 Vertical or cope bars as a rule have their edges kept \ in. away from 
 the pattern, and f in. from the joint of the box. Flat or drag bars do 
 not follow the outline of the pattern, being used in the bottom half of 
 the mould or in the drag-box. Bars are purposely cast as rough as 
 possible to ensure the adherence of the sand, which adherence is 
 further assisted by washing them with clay water, and also frequently 
 by hanging lifters (q.v.) from their top edges. 
 
 Bar Clamp. — A tool used for the purpose of clamping or squeezing closely 
 together long timber joints, which are glued or dowelled, the jaws of 
 the clamp operating on the outer edges of the wood. It consists essen- 
 tially of a long bar of iron of rectangular section, having a fixed head 
 or jaw at one end, carrying a square threaded pinching screw and a 
 movable head or jaw sliding along the bar, and capable of being set in 
 any position at distances of from 2 in. to 4 in. apart by means of a pin, 
 
a DICTIONARY OF TERMS USED IN 
 
 or of ratotet teeth. The movable head being set in the approximate 
 position required for various vpidths of board, the pinching up of the 
 clamping screw in the fixed head affords the necessary degree of 
 pressure. 
 
 Bare. — A workshop term which signifies that a dimension is very slightly 
 under a definite size. In most cases it will mean a difference so slight 
 as to be unappreciable by a rule measurement, and only to be detected 
 by cahpers or gauge. A jV in. or a -^f in. is a definite dimension, but 
 " bare " would signify something less than this, or say the difference 
 between a slack and a driving fit. 
 
 Barffed. — Ironwork which has undergone Barff's process (q.v.) is some- 
 times said to he barffed. Thus the iron plugs of plug cocks so treated 
 are termed " BarfEed plugs." 
 
 Barff's Process. — A patented process employed for the protection of the 
 surfaces of iron from rust, effected by artificially coating them with a 
 film of magnetic oxide. The iron is first heated to redness, and steam 
 is then passed over it. The iron decomposes the steam, liberating 
 oxygen, which latter immediately attacks the iron, form i ng magnetic 
 or black oxide, FesOi. 
 
 Barker's Mill, — A piece of mechanism which illustrates the power of the 
 reaction of water. It consists of an upright tube to whose lower end 
 two horizontal tubes, set opposite to one another, are attached, open- 
 ings being provided therein near their ends and in the reverse direction 
 to one another. When water is poured into the vertical tube it issues 
 from the side openings in the horizontal tubes, and drives the null round 
 in a direction contrary to that of the effiuent water. See Turbine. 
 
 Bar Lathe. — A lathe whose bed is made in a single piece, usually of a 
 triangular section, one side of the triangle being beneath and hori- 
 zontal. Used only for lathes of Mght construction. 
 
 Bar Mill. — A rolling mill where rectangular iron bars are manufactured. 
 
 Barometer. — An instrument used for measuring the pressure of the at- 
 mosphere. It consists of a glass tube containing mercury, and standing 
 in a vessel containing mercury, so that while the atmosphere presses 
 on the surface of the mercury in the vessel there is nothing above 
 that in the tube save its own vapour, the amount of whose pressure 
 is disregarded. The height to which the mercury rises in the tube is 
 called the height of the barometer. It is used for comparison with the 
 vacuum-gauge (q-v.) in order to ascertain the amount of perfection 
 existing in the vacuum present in the condenser of a steam-engine. 
 
 Barometric Pressure. — The amount of pressure of the atmosphere as 
 measured by the barometer. It is measured in atmospheres, and 
 fractions of atmospheres. The pressure of a single atmosphere is 
 equal to 29-905 in. of mercury at 32° F. at London, or 14f lbs. 
 on the square inch, or by the metric system, 760 millimetres of mercury 
 at 0° C. at Paris, equivalent to 1'033 Mlos per square centimetre. 
 
 Barrel. — (1) The body of a pump within which the piston moves. (2) Tho 
 cylindrical shell of a locomotive or portable engine boiler. (3) The drum 
 or cylinder around which the chain is wound in hoisting machinery. 
 Barrels are either plain or grooved spirally, and the grooves may either 
 be made to take the flat of alternate links or the links continuously, 
 but lying at an angle. 
 
 Barring Engiae. — ^An engine used for the initial turning of larger engines. 
 
 Barrow ladle. — A foundry ladle mounted on a low carriage provided 
 with two wheels in front, and handles and legs at the hinder pan. 
 Used for wheeling melted metal about the foundry. 
 
MECHANICAL ENGINEERING. 23 
 
 Sarrow Fnmp. — A force pump mounted on a hand barrow for portability, 
 and fumislied -with tose pipe for suction and delivery. Frequently 
 termed California pump, because of its value in mining and agricultural 
 districts. 
 
 Bar Stays — Boiler stays (q.v.) -vrhich are solid rods screwed at their ends, 
 as distinguished from tube stays or stay tubes (q.v.) . 
 
 Base Circle. — See Fundamental Circle. 
 
 Base Plate, or Bed Plate. — The foundation plate or support for a piece 
 of machinery. It consists usually of a comparatively thin plate, well 
 stayed and stifBened with deep outer and inner ribs or flanges, and 
 furnished with all necessary facings for the attachment of accessory 
 portions, and also with lugs for holding or bolting it down. 
 
 Basicity, — Refers to the proportion of metallic oxide present in, and the 
 absence of sUioon from a furnace lining, a cinder, flux, or slag. The 
 fettling (q.v.) of a puddling furnace depends for its ef&cacy on its basic 
 character, as does also the magnesian limestone of a Bessemer converter. 
 
 Basic Process. — The process of Messrs. Thomas & G-ilchrist, by means of 
 which the prosphoms and sulphur are eliminated from the pig iron in 
 the Bessemer converter. It consists in the substitution of magnesian 
 limestone or dolomite, which is composed almost entirely of metallic 
 oxides, and is therefore highly " basic," for the siUcious ganister which 
 is used as a lining in the acid process (q.v.). See App. 
 
 Basic Steel. — Steel produced by the basic process (q.v.). 
 
 Basil. — A term sometimes applied to denote the bevelled edge of a drill or 
 chisel. 
 
 Basket. — A small rose or strainer for suction hose pipe. 
 
 Bass Scrubs. — Brashes made of ordinary bass, used by feltlers for brush- 
 ing the sand off castings when they leave the foundry. See Fettling. 
 
 Bastard Cut. — A very coarsely-cut file, a trifle iiner than the rough or 
 first cut. In a twelve-inch bastard-out file the lines of teeth would 
 number eight to the linear inch. 
 
 Bastard Pitch. — The pitch of a toothed wheel which is not of a definite 
 dimension, but is either over or under an exact pitch. 
 
 Bastard Wheel. — Occasionally used to denote a bevel wheel whose 
 amount of bevel is so slight that it approaches very nearly to a right 
 angle or to a spur wheel. Also one acconmiodated to an existing wheel, 
 though not absolutely correct. 
 
 Bath. — The mass of boiling metal in a steel melting furnace of the open 
 hearth type. 
 
 Battens. — Sawn pine timber measuring not more than 9 in. by 3 in. in 
 cross section, or not less than 6 in. in width ; when in sizes less than 
 that being termed BcantUng or quartering ; 7 in. by 2 in. is the common 
 section of battens. Gleets are also termed battens. See Gleet. 
 
 Battering Off. — The finishing of the surface of forged work, effected by 
 the hammer while the iron is becoming of a low red or black heat. 
 
 Battery of Boilers. — Steam boilers arranged in series, for the supplying 
 of power to a large factory, one or two of the boilers being spare or 
 auxiliary, for use when either of the others are undergoing repairs. 
 
 Bauxite. — A hydrated aluminous ferric oxide. It contains about 60 per 
 cent, of alumina, 20 per cent, of ferric oxide, 15 to 20 per cent, of water, 
 and from 1 to 3 per cent, of silica. It is a highly refractory body, and 
 is used in the manufacture of Bauxite bricks (q.v.). 
 
 Bauxite Bricks. — Refractory iire-bricks used for the lining of furnaces of 
 various kinds. They are made by mixing calcined bauxite (q.v.) with 
 clay or pliunbago. 
 
24 DICTIONARY OP TERMS USED IN 
 
 Bay. — In a lattice, or a Warren girder, the space included between two 
 adjacent apices is called a bay. 
 
 Bayonet Engine. — A horizontal engine is said to be of the bayonet type 
 ■vrhen the bed-plate is curved round to one side of the crank. The 
 curved portion carries the bearing for the crank-shaft. This outline is 
 by a stretch of the imagination supposed to be similar to that of a 
 bayonet, hence the term. 
 
 Baywood. — See Mahogany. 
 
 B.B. — See Best, Best. 
 
 B.B.B.— See Best, Best, Best. 
 
 Beach Chuck. — ^A common form of die chuck containing three dies slid- 
 ing in a hollow cone which is tightened or relaxed upon them. Used 
 for holding small drills and pieces of wire or rod. 
 
 Bead, or Beading. — (1) The thickened edge of a sheet of metal, thickened or 
 turned over to stiffen and strengthen it. (2) An ornamental fillet or strip 
 curved around the edge of a easting for the same purpose. (3) The semi- 
 circular termination of the spigot end of a pipe. Its ftmction is to form 
 a stop for the material used in caulking (q.v.). (4) Angles (q.v.) and 
 hollows are frequently called beads. 
 
 Beaded Tube. — The ends of boiler tubes, after being riveted over the 
 tube plates, are beaded or rounded, for the sake of appearance, with a 
 beading tool (q.v.), just as rivet heads are finished with a die or snap. 
 The process is termed beading. 
 
 Beading. — See Bead, Beaded Tube. 
 
 Beading Tool. — A tool used by boiler-makers for finishing off the riveted 
 ends of boiler tubes (q.v.). Its shape is similar to that of a drift (q.v.), 
 except that at a short distance behind its narrow end it is shouldered 
 out into a hollow curve which is the counterpart of the bead it is 
 designed to mould on the ends of the tubes. The beading tool is struck 
 by a hand hammer. 
 
 Bead Sleekers. — Moulders' sleeking tools, rounded in the direction of 
 their length and also rounded in their cross section similarly to a plain 
 semicircular bead bent around a cylinder. Used for smoothing the im- 
 pressions of beaded work in the sand moulds. Also called bead tools. 
 
 Bead Tools, — (1) Bead sleekers (q.v.). (2) Metal turners' scraping or 
 finishing tools made hollow, or the exact reverse of the shape of a 
 round-nose tool, and used for finishing the circiilar edges of headings. 
 
 Beak Iron. — The conical-shaped piece which projects from the end of a 
 smith's anvil. Also termed beck. 
 
 Beam. — A piece of timber or other material, or a built up structure, 
 whose length is greater than its width or depth, and whose strains 
 are those due to leverage, or tension, or compression. Beams are made 
 in a vast variety of cross sections, and are solid beams or built-up beams, 
 symmetrical or unsymmetrioal, semi beams, compound beams, Warren 
 and other girders, &c. The term beam does not necessarily imply that 
 the material is subjected to transverse strain only, since a tie-beam 
 (q.v.) is only in tension. The term girder (q.v.) is understood to refer 
 to beams subject to transverse stress, and either resting on a single 
 support, as a cantilever, or on both extremities. The term beam is 
 applied to so many different kinds of struotures, both elementiiry and 
 compound, that it is always necessary to denote by some specific term 
 the structure under consideration, and under their specific names the 
 typical beams in use with engineers will be found described. 
 
 Beam Compass. — See Trammels. 
 
MECHANICAL ENGINEERING. 25 
 
 Seam Engine. — A steam-engine in which the connection between the 
 piston and connecting-roda is made through a beam whose point of 
 oscillation is set midway between the centres of the two rods. Beam 
 engines, except for pumping and some special work, are becoming 
 obsolete. 
 
 Beams,— relative strength of. — The strength of beams depends — their 
 cross-sections remaining the same — upon the manner in which their 
 loads are applied. Takmg the strength of a beam supported at one 
 end and loaded at the other as unity, a similar beam having the same 
 load equally distributed would suffer only half the stress. If the same 
 beam be supported at both ends and loaded in the centre, it will be 
 subject to one-fourth only of the stress. If supported at both ends 
 and the load distributed, it will receive but one-eighth of the stress it 
 sustains in the first instance. 
 
 Bean Shot Copper. — Globules of copper obtained by pouring the melted 
 metal through a perforated ladle into a vessel of hot water. 
 
 Bear. — See Punching Bear. 
 
 Bearer. — (1) The cheek of a lathe-bed. (2) The support or bearing-bar 
 which carries the firebars of an engine boiler. 
 
 Bearing. — The support or carrier of a rotating shaft. 
 
 Bearing Metals. — Anti-friction and white metals, brass, and gnn- 
 metals, and the various alloys used for making or lining the bearings 
 of journals. 
 
 Bearing Neck. — The portion of a rotating shaft which is in contact with 
 its bearing. 
 
 Bearing Bing. — A ring welded up from iron bar of square section which 
 forms the bearer or support for the firebars in a vertical boiler. 
 
 Bearing Springs. — The springs which support the wfeight of an engiue or 
 truck, as distinguished from buffer and draw-bar springs. 
 
 Bearing Surface. — (1) The area of the surface upon which a shaft rotates. 
 (2) The surfaces of bearing parts which are in mutual contact. The 
 larger the total bearing surface the less the amount of friction per unit 
 of surface, since pressure is then distributed over a larger area. 
 
 Beating. — A term applied to the regular thudding soimd produced by the 
 engines of a locomotive or a steam vessel. 
 
 Beaumontagne. — This term is applied in the shops to any compound 
 employed for the filling up of holes for purposes of concealment. It is 
 applied to the chalk and varnish compoimd of the pattern-maker, to the 
 white metal of the founder, and to the salammoniac and borings of the 
 fitter. As used for filling up blow-holes (q.v.) in castings, it consists 
 of beeswax, resin, lamp-black and iron borings. 
 
 Beck. — A beak iron (q.v.). 
 
 Bed. — A term of general application, as engine-bed (q.v.), coke-bed 
 (q.v.), a base-plate (q.v). 
 
 Bed Charge. — The quantity of coke which forms the coke-bed (q.v.) of a 
 cupola. 
 
 Bedding. — (1) The bringiag of a piece of mechanism to a close and proper 
 fit upon its base or foundation. (2) Or the material or structure on 
 which a piece of mechanism rests. (3) A seating. (4) The laying of a 
 piece of machinery on its foundation. 
 
 Bedding In. — The simplest method of iron moulding in which the pat- 
 tern, instead of being rammed on each side in a jointed box and rolled 
 over, is laid or embedded in the sand of the foundry floor. The sand 
 is then tucked in and rammed around and over it. 
 
26 DICTIONARY OF TERMS USED IN 
 
 Bed Plate. — See Base Plate. 
 
 Beech {Fa</iis sijlmtica). — A genus of tte order Cupuliferm. A light- 
 brown coloured wood, hard and close-grained, used chiefly by engineers 
 for the cogs of mortice-wheels. Its sp. gr. ranges from -75 to -85. Its 
 ultimate tenacity ranges from 11,500 to 22,200 lbs. per square inch of 
 section. A cubic foot weighs from 46-8 to 53 lbs. 
 
 Bee-hive Oven. — See Coke. 
 
 Beeswaxing. — The coating over of iron patterns while warm with a 
 thin film of beeswax, for the purpose of importing a glossy sMn to 
 their surfaces, and thus facilitating their withdrawal from the sand. 
 
 Beetle Head. — The moiikey of a pile-driver. 
 
 Bell Centre Punch. — A centre punch (q.v.) which is self-centering. The 
 actual punch is enclosed within a tube whose lower end or mouth is 
 expanded or tapered downwards, resembling a bell. This being 
 dropped over and embracing the end of a round bar ensures that the 
 enclosed punch shall pop on the exact centre of the bar. The mouth 
 adapts itseK to bars of dafEering diameters. 
 
 Bell Chuck. — A cup chuck (q. v.) . 
 
 Bell Crank Lever, — A lever having two arms which meet at an angle of 
 90°, the fulcrum being situated in the meeting point of the angle. 
 Employed much in machine work when motion has to be conveyed to 
 rods which lie 90° apart. 
 
 Bellied. — Curved underneath, the depth increasing towards the centre. 
 The term is therefore applied to plated and ribbed portions of machinery 
 and structures which have this outline. 
 
 Bellied Core. — See Chambered Core. 
 
 Bellied File. — The ordinary taper file (q.v.), so called because it is 
 rounded very much on its edge, and slightly in the thiclcness, so that 
 the greatest thickness is about in the middle. Taper files are used more 
 for the opening out of small holes than for ordinary flat surface filing. 
 See Hand FUe. 
 
 Bellied Girder, — A fish-bellied girder (q.v.). 
 
 Bell Metal. — A hard, brittle, sonorous alloy of copper 16, and tin 5. 
 
 Bell Mouthed. — ^When the open end of a vessel or pipe expands or spreads 
 out with an increasing diameter, resembling a beU, this term is applied 
 to it. Also called trumpet-mouthed. 
 
 Bellows. — A smith's bellows consists of two chambers separated by a dia- 
 phragm, so that while the motion of the bottom board is intermittent, 
 the blast is nearly continuous. Ordinary Idtchen bellows are used in 
 the foundry for blowing away the parting sand from the faces of pat- 
 terns, and also for disposing of superfluous blacking or loose particles 
 of sand from the moulds. 
 
 Belly. — The belly of a blast furnace is a narrow zone at the junction of 
 the two truncated cones which form the body and the boshes. 
 
 Belly Helve. — See Helve Hammer. 
 
 Belt. — (1) A band or strap, sufficiently flexible to act as a transmitter of 
 power over smooth pulleys. A belt acts by friction only. Tho 
 materials for belting are leather, iadia-rubber, gutta-percha, and cot- 
 ton, described under their specific headings. (2) Head metal on a 
 cylinder or pipe. 
 
 Belt Coupling. — The union of the ends of a belt. It is effected by the 
 aid of laces or of belt screws. 
 
 Belt Dressing. — Leather belts are apt to become hard and crack in dry 
 situations, and various dressings are used as preservatives to maintain 
 
MECHANICAL ENGINEERING. 27 
 
 them supple. Pure tallo-w dried into the belt by the heat of the sun 
 or in a warm room is a good preservative. Some apply castor-oU. 
 One recipe gives castor-oil 2 quarts, tallow 1 lb., powdered resin, 1 oz., 
 hard soap 2 oz. , melted together. For belts which have already become 
 hard, neatsfoot oil and resin are recommended. Resin mixed with 
 tallow is also recommended for use with belts which have to run in 
 damp places. 
 
 Belt Fork, or Strap Fork. — A pair of prongs standing out from a strap 
 bar and enclosing a space within which the belt or strap of a machine 
 fitted with fast and loose pulleys runs. The edges of the belt either run 
 against the sides, if plain iron rods, or against freely-revolving rollers 
 slid over the rods as spindles, the latter method diminishing friction. 
 
 Belting.— See Belt. 
 
 Belt Lacing. — See Lacing. 
 
 Belt Perch. — A bar of wood or a metal rod placed alongside a belt-pulley 
 on which to rest the belt when unshipped for repairs, in order to 
 prevent the latter from becoming hitched in the revolving shaft, and 
 being itself damaged or inflicting damage on the machine or at- 
 tendant. 
 
 Belt Pipe. — ^Applied to a steam or exhaust pipe when it surroimds its 
 cylinder. 
 
 Belt Pulley.— See Pulley. 
 
 Belt Punch. — A pher-shaped punch used for piercing holes in belting for 
 the reception of the laces or screws used for the coupling together of 
 the ends. 
 
 ielt Rivets. — Copper rivets used for fastening the joints in leather 
 belting. 
 
 Belt Screws. — Male and female screws used for uniting the overlapped 
 joints of belts. Used in preference to laced joints. 
 
 Belt Shifter. — A bar of iron carrying a pair of forks or prongs, used for 
 shifting a belt backwards and forwards between loose and fast pulleys. 
 
 Belt Shipper, — Usually a length of round bar iron or of gas tubing held 
 from below, by which an overhead belt is slipped over its pulley. 
 Patent belt shippers are also used. 
 
 Belt Shipping. — The placing of belts on their pulleys, or the transference 
 of a belt from one pulley to another, usually performed while the 
 pulleys are in motion. 
 
 Belt Stretcher. — ^A piece of mechanism employed for stretching new 
 leather belts in readiness for use. But belts are very commonly sus- 
 pended in a loop from the roof, and loaded only with ordinary weights. 
 AU new belts must be stretched, otherwise they would soon have to 
 be taken up and relaced, ' 
 
 Belt Tension. — The ultimate strength of leather belts varies from 3,000 
 to 5,000 lbs. per square inch. But at laced joints the strength is 
 only '3 of those values, or from 900 to 1,500 lbs. per square inch. 
 The working tension should not exceed about 300 lbs. per square inch. 
 A good rule is 20 lbs. per inch of width for each -^g inch iu thickness 
 of the belt. The tensile strain is found by multiplying the num- 
 ber of the H.P. tfl be transmitted by 33,000 and dividing the pro- 
 duct by the velocity of the pulley in feet per minute. This repre- 
 sents the strain in pounds upon the driving side, independently of the 
 initial tension producing adhesion between the pulley and the belt. 
 This initial tension should be sufficient in amount to prevent slipping 
 on either of the pulleys at the moment of starting. 
 
28 DICTIONARY OF TERMS USED IN 
 
 Belt Tightener. — ^A contrivance used for puUing the ends of belts together 
 for coupling up. Clamps are attached to the opposing free ends of 
 the belt and then drawn together by means of screws and nuts. 
 
 Bench. — ^A strong support or table, more or less massive, upon which 
 certain Muds of work are performed. See Pattern Bench, Core Bench, 
 Brass Bench, Fitters' Bench, Vice Bench. 
 
 Bench Drilling Machine. — A small drilling machine made to bolt to a 
 work bench, and actuated by hand. These are of numerous types and 
 sizes, and are made either single, double, or treble geared. The hand 
 wheel or winch handle is sometimes placed at the back, more com- 
 monly at the side of the machine, and drives the drfll-spindle through 
 bevel-wheels. The left hand only is free to manipulate the work. 
 
 Bench Hook. — A stop for sawing light work on the bench without 
 damagiag the bench itself. It is a block of wood about 12 in. long, 
 furnished with a projecting stop at each end placed on opposite faces of 
 a central web. One face of the web being laid on the bench, the lower 
 stop is pressed against the bench edge, while the upper one takes the 
 thrust of the wood which is being cut by the saw. 
 
 Bench Lathe. — ^A light lathe fitted with short standards to permit of its 
 being bolted upon an ordinary work bench. 
 
 Bench Flanes. — The planes which are always kept on the bench as being 
 in constant use. They are jack, trying, and smoothing planes. 
 
 Bench Banuner. — A small round-ended rammer (q.v.) provided with a 
 short handle (12 in. to 15 in.), used for making cores of moderate size, 
 or those which can be made on the core bench, or the smaller moulds 
 whose flasks are laid upon a work bench. 
 
 Bench Work. — Used to distinguish work carried on at the bench or vice 
 as distinguished from lathe work, and also to distinguish the work of 
 the fitter (q.v.) from that of the erector (q.v.). 
 
 Bend. — The curved part of a pipe by which its direction of motion is 
 changed. " Quarter bends " include fovir in the circle ; eighth bends, 
 eight to the circle ; and sixteenth bends, sixteen to the circle. Their 
 angles are 90°, 45°, and 22^' respectively. When practicable, bends 
 should be of large radius to diminish the friction of the liquids which 
 they convey. 
 
 Bending, or Flexure. — The curvature of a beam about its axis or cen- 
 tral plane. (See Neutral Axis.) The amount of bending action is 
 measured by the bending moment (q.v.). The safe or working load 
 must be estimated in reference to the intensity of the stresses due to 
 bending, so that the moment of resistance of any section must be equal 
 to the bending moment at that section. Diagrams and formulas are 
 given in most engineer's reference books for obtaining the bending 
 moments and working loads of beams of various sections, variously 
 supported or .fixed. 
 
 Bending Machine. — See Straightening Machine. 
 
 Bending Momrtit. — The resultant or sum of the straining forces acting 
 upon each side of a given section. The bending moment of the ex- 
 ternal forces at either side of any cross section equals the moment of 
 resistance of that section. 
 
 Bending of Pipes, — See Pipe Bending. 
 
 Bending EoUs. — Heavy roUers of cast iron or steel set in strong stand- 
 ards, and used either for the straightening of crooked plates or for 
 bending them into arcs of circles or into complete cylinders. The 
 centres of the rolls are made adjustable relatively to each other with 
 
MECHANICAL ENGINEERING. 29 
 
 this object, their bearings running in strong housings, the upper pair 
 of which are elevated or depressed at pleasure by means of a screw. 
 The ordinary bending rolls contain three rollers, but are typical of 
 numerous machines of modified characters used for bending, straight- 
 ening, and rolling iron of various sections, both hot and cold. 
 
 Bending Strain. — See Transverse Strain. 
 
 Bent Gouge. — An outside firmer gouge curved in the direction of its 
 length, and used by pattern-makers for hollowing out the concave 
 portions of core-boxes. A spoon gouge is a short, more quickly curved 
 form of bent gouge. 
 
 Bent Lever. — A form of the lever in which the arms are iuclined at an 
 angle towards each other. In estimating the mechanical efficiency, 
 instead of taking the lengths of the actual arms, the lengths of the 
 perpendiculars from the fulcrum to the lines of directions of the forces 
 are taken. 
 
 Bessemer Converter. — The vessel employed for the production of mild 
 steel directly from oast iron, by the patented process of its inventor. 
 The converter is a pear-shaped vessel lined with a refractory material 
 ■ — ganister (q.v.) or magnesian limestone (q.v.) — and provided with 
 twyers for tiie blowing in of air under pressure. It swivels upon 
 trunnions, by means of which it is tilted up and the molten steel poured 
 out when the process is complete. The blowing in of air oxidises the 
 carbon to carbonic oxide. Speigeleisen is then added in sufEcient 
 amount to impart the quantity of carbon requisite to make steel of a 
 definite degree of carburisation. 
 
 Bessemer Pig. — Pig-iron of a special quality prepared for conversion into 
 Bessemer steel made by the acid process. It is made from haematite ores, 
 and contains not less than 2 per cent, of siKcon, from 3 to 5 per cent. 
 of graphitic carbon, not more than 0-1 per cent, of phosphorus, about 
 1 per cent, of manganese, and as little as possible of sulphur and 
 copper. White iron is unsuitable. The use of silicon consists in the 
 high calorific power generated by its oxidation. Bessemer pig is classed 
 in Nos. 1, 2, and 3. For the basic process pig rich in phosphorus and 
 manganese and poor in silicon is preferred. 
 
 Bessemer Plant. — The plant used in the production of Bessemer steel 
 (q.v.). It usually consists of a pair of converters, a casting pit, 
 hydraulic cranes, ladle, slag pit, cupola for melting the speigeleisen, 
 and the cupolas for melting the pig in readiness for running into tho 
 converter. 
 
 Bessemer Process. — The process of the decarburisation of cast iron 
 effected by blowing atmospheric air through it while in a fluid con- 
 dition, followed by a measured amount of recarburisation. (See 
 Bessemer Converter.) The acid process (q.v.) originally introduced 
 has been superseded by the basic process (q.v.). The Bessemer pro- 
 cess is sometimes termed the pneumatic process, in allusion to the 
 blowing through of atmospheric air. See App. 
 
 Bessemer Skulls. — Skulls (q.v.) formed around the lining and the mouth 
 of a Bessemer converter. Their formation is due to what is known as 
 a cold blow, that is, there is not sufficient sOicon in the pig to maintain by 
 its oxidation the heat necessary for perfect fluidity. See Bessemer Pig. 
 
 Bessemer Steel. — The mild steel produced directly from the pig in the 
 Bessemer converter (q.v.). Used for boilers, rails, tyres, girder 
 work, general smith's work, &c. 
 
 Best, or E. — A brand of wrought-iron plate or bar equivalent to No. 3 
 
30 DICTIONARY OF TERMS USED IN 
 
 quality, or that grade 'wHoli is only just superior to the commonest. 
 It is obtained by piling, reheating, and rerolling either No. 1 and No. 2 
 iron, or all No. 3 brands. The "best" plates of thefirst-classhousesare, 
 however, equal to the "best, best " and "treble best " of other firms. 
 
 Best, Best, or B.B. — A brand of wrought-iron plate or bar indicating 
 a superior quaUty obtained by piling, reheating, and rerolling " best " 
 or No. 3 bars. 
 
 Best, Best, Best, or Treble Best, B.B.B. — A brand of -wrought-iron plate 
 or bar indicating the best quality of plate made. It is obtained by re- 
 piLing, reheating, and rerolling the " best, best" quality. 
 
 Beton. — Concrete (q.v.). 
 
 Betty. — A crowbar (q.v.). 
 
 Between Centres. — Signifies the chucking of lathe work between the 
 centres of the headstock and poppet, as distinguished from the attach- 
 ment of work to face and other chucks. The centres are either the 
 dead centres or the prong chuck and dead centre. 
 
 Bevel, or Bevel Square. — A tool used for testing the accuracy of work 
 which is cut to an angle or bevel. It consists of a stock and blade. 
 The blade is movable and is fixed or set by a screw. In the best bevels 
 the blade is also capable of movement along the screw by means of a 
 slot. 
 
 Bevel Gearing. — Gearing comprising combinations of bevel- wheels (q.v.). 
 
 Bevelled Washers, — See Timber Washers. 
 
 Bevel Ring. — A ring or washer u.sed for insertion between the flanges of 
 abutting pipes which do not stand parallel with each other. When 
 thin it is made of lead, if thick of cast iron. See also India-rubber 
 "Washer. 
 
 Bevel Square. — See Bevel. 
 
 Bevel Wheels. — Toothed wheels the pitch planes of whose teeth meet in 
 the common centre of their axes. In most bevel-wheels these axes are 
 at right angles with each other, but in some instances they are set at 
 other than right angles. When the wheels are of equal diameter and 
 the bevel of the pitch plane is 45°, they are termed mitre-wheels. 
 
 Bib Cock. — A cock whose nozzle is bent downwards after the fashion of 
 an ordinary cistern tap. 
 
 Bicarbonate of Lime. — See Carbonate of Lime. 
 
 Bight. — The hanging loop of a chain or rope which falls below the 
 pulleys in lifting taclde. 
 
 Bilge Pipes. — The pipes through which bilge water on board ship is 
 removed by means of the bUge pump (q.v.). They are made of lead. 
 
 Bilge Pump. — A pump attached to marine engines for pumping out the 
 bUge water in the event of excessive leakage. 
 
 Billets. — Short rectangular lengths of pOed bar or welded scrap iron used 
 for producing the smaller sections of finished iron in the roDing-miU, or 
 for smith's use. Ordinary billets may measure about 18 in. long by 
 3 in. square. 
 
 Billeting Bolls, — See Houghing Rolls. 
 
 Binding Straps. — The loops which secure the cutting tool against the 
 face of the tool-box of a planing or shaping machine. The straps are 
 attached to the tool-plate and encircle the shank of the tool, which is 
 then pinched by a clamping screw. 
 
 Binding Wire, — Iron or brass wire of small gauge used for binding joints 
 which have to be brazed, or for fastening india-rubber hose around 
 brass unions. For brazing purposes the term binding wire may signify 
 
MECHANICAL ENGINEERING. 31 
 
 either the iron -wire used to confine the jointed pieces or the brass 
 ■wire which acts as the solder. 
 
 Bisecting Scale. — A flat scale fully and symmetrically divided on each 
 side of its centre line. It is usuaDy graduated for \ in., J in., and 
 1 in. scales. 
 
 Bismuth. — Symhol Bi. Comb, weight 210, sp. gr. 9-8. A pinlrish 
 white metal which does not oxidise at the ordinary temperature. It is 
 chiefly useful as an alloy with other metals to form antifriction com- 
 pounds for bearings, and to produce alloys which expand in cooUng. 
 
 Bit. — (1) The jaw of a smith's tongs. (2) A copper bit (q.v.). See also Bits. 
 
 Bite. — (1) The grasping power of the jaws of lathe-chucks, vices, nippers, 
 wrenches, tongs, and similar tools. (2) The friction of a rope around a 
 piJley or capstan. (3) Signifies gripping action in general. 
 
 Bits. — Boring tools for wood, comprising centre, shell, nose, gouge, counter- 
 sini, and other forms. They are actuated by the brace or stock. 
 
 Bit Stock Drill. — A drill whose shank is square tapered to fit into the 
 socket of a common brace. 
 
 BituminOTts Coal. — Smoky burning, non-caMng, or caking and coking 
 coals, containing more hydrogen and oxygen than the anthracites, but 
 less than the lignites. The bituminous caking coals are only suitable 
 for gas and coke making, but the semi-bituminous, non-caMng, free 
 burning coals are largely used for steam boilers, either alone or mixed 
 with anthracitic coals (q.v.). The semi-bituminous coals bum readily, 
 and give out much smoke. 
 
 Bituminous Paint, or Tar Varnish. — A protective coating used for pipes 
 and structures which are laid under water. It is variously made, but 
 is composed essentially of the bituminous products of coal niixed with 
 mineral oils. One recipe gives 30 gallons of coal tar, fresh with all 
 its naphtha retained, 6 lbs. of tallow, \\ lbs. of resin, 3 lbs. of lamp- 
 black, 30 lbs. of fresh slaked lime finely sifted. Mix immediately and 
 apply hot. 
 
 Black Baud Ore. — This ore is of the same essential composition as the clay 
 band (q.v.), but it contains in addition a quantity of bituminous matter 
 intermixed therewith. It is mined in Scotland and in Prussia. 
 
 Black Copper. — Fine metal (q.v.), which, not being of sufiicient purity, 
 or containing only about 60 parts of copper to the 100, is subjected 
 to the processes of recalcining and resmelting. Black copper, as 
 it is then called, contains from 70 to 80 per cent, of copper. 
 
 Black Diamond.^See Carbonado. 
 
 Blackening. — See Blacking. 
 
 Blackening of Screws.— Small set screws in model and other work are 
 often blackened to protect them from rust. They are heated to a black 
 heat and dipped in a bath of oil. 
 
 Blacking, or Blackening. — Ground charcoal, coal or coke dust, or plum- 
 bago, used by moulders for the purpose of preventing sand burning 
 (q.v.). It is sleeked over the suirface of the mould with a brush and 
 trowel, or simply dusted over. It prevents the immediate contact of 
 the heated metal with the sand through the generation of a film of 
 carbonic oxide, or of carbonic acid gas produced by the union of the 
 oxygen with the carbon constituting the bulk of the blacking. Black- 
 ing is also mixed in certain proportions with the sands used in green 
 sand moulds. 
 
 Blacking Bag. — A porous muslin or calico bag used for containing foundry 
 blackmg (q.v.), which is then dusted finely over the faces of the moulds. 
 
3a DICTIONARY OF TERMS USED IN 
 
 Blacking Mill. — ^A large revolving closed cylinder, contaiinng heavy 
 rollers rotating freely upon its internal diameter, by whose crushing 
 action small coal or coke is ground into blacking (q.v.) for foundry use. 
 Instead of cylindrical rollers some blacking nulls are furnished with 
 ordinary spherical balls revolving in a corresponding annular groove. 
 Sometimes called coal or coke mill. 
 
 Blacklead. — This is used for imparting a smooth skin or coating to some 
 foundry patterns to facilitate delivery. Also for coating the faces of 
 cast-iron chilling moulds, with or without the addition of oil. Mixed 
 with soft soap it is used as a lubricant for wood which is revolving in 
 a lathe steady during turning. 
 
 Black Nuts. — Nuts (q.v.) which are not polished but left rough as forged. 
 They are used for common and out-door work, and for those portions of 
 machine work which are concealed. See Bright Nuts. 
 
 Black Oils. — Crude mineral oils of good body which have been subjected 
 to one series of purifications only to remove their mechanical impurities, 
 and volatile oils, but which have not been filtered to improve the 
 colour. They are used for cylinder lubrication. 
 
 Black Oxide of Copper ^An ore of copper containing about 80 per cent. 
 
 of pure copper. It is found in ChiU. 
 
 Black Pin. — Signifies a stud or pin which is not turned but left black from 
 the forge. Black pins are often used in the rougher kinds of work, 
 and particularly in those joints which are simply coim.ections, and not 
 pivots. 
 
 Black Plates. — Plates of thin sheet iron rolled and cut to size, ready to be 
 brightened for the tinning process in the manufacture of tin plates (q.v.). 
 
 Black Print. — See Phototype. 
 
 Black Red Heat. — Denotes that temperature of wrought iron or steel in 
 which the red colour is just visible by daylight. It may be roughly 
 taken as correaponding with 1,000° P. 
 
 Black Sand. — Old sand (q.v.). 
 
 Black Smoke. — See Smoke. 
 
 Black Tin. — Tin ore which has been calcined and washed, and is thus 
 prepared ready for smelting. It contains about 60 per cent, of tin. 
 
 Black Varnish. — Ordinary shellac varnish stained by the addition of lamp- 
 black. It is used by pattern-makers. 
 
 Black Wash, or Wet Blacking. — ^A solution which is used in loam moulds 
 (q.v.) and dry sand moulds for the same purpose as blacking (q.v.) 
 is used for green sand moulds. It consists of a mixture of clay water, 
 and ground charcoal or coal, applied with a swab or brush, and dried 
 in the stove. 
 
 Black Work. — Work which has not been machined or polished. In some 
 instances the term would apply to metal work which had been machined 
 on a bearing section, but not elsewhere. And in other cases where 
 no portion, working or otherwise, had been machined. 
 
 Blade. — A thin lamina or plate, as the blade of a square or of a screw. 
 
 Blank. — ^A piece of metal prepared specially to be shaped or ground to 
 some particular shape. Thus, gear-wheels whose teeth are cut out of 
 the solid are cut from prepared "blanks," and the term is generally 
 applied to block-like castings or forgings which are to be definitely 
 shaped by means of machinery. 
 
 Blank Bolts. — The rough forgings of the bolts previous to screwing. 
 
 Blank Cap. — A covered cap used for screwing into the open end of a hose 
 union when not in use. 
 
MECHANICAL ENGINEERING. 33 
 
 Blank End. — The end of a pipe or cylindrical casting whioli is closed up 
 so that no through passage exists. 
 
 Blank Flange. — A solid flange used for bolting to the end of a pipe at 
 cylinder for the purpose of closing it up permanently, or for a temporary 
 purpose only. 
 
 Blank Holes. — Eiyet holes in boiler, ship, bridge, and other plated works 
 ■which are so very inaccurate that when the plates are placed in position 
 the holes do not correspond within a distance equal to their own 
 diameters. In such cases the holes have to be redriHed, or the work 
 condemned. 
 
 Blank Socket. — A stop end (q.v.). 
 
 Blast. — The volume of air forced into those furnaces whose combustion is 
 quickened by artificial means. They embrace blast furnaces, cupolas, 
 locomotives, and some marine boilers. See Blast Furnace, Cupola, 
 Blast Pipe, Forced Draught, Tuyere. Also Bessemer Converter. 
 
 Blast Fan. — See Fan. 
 
 Blast Furnace. — The furnace employed for the smelting of iron from its 
 ores. Its longitudinal section is that of two truncated cones of unequal 
 height placed base to base. (See Boshes, Throat.) Blast furnaces vary 
 from forty to one hundred feet in height, and have a capacity of from 
 10,000 to 50,000 cubic feet. They are built of brick or of sheet iron 
 lined with a refractory material. Once lit they are kept in blast 
 for several years. Their details of structure vary with the nature and 
 quality of the ore and fuel available. The blast, from which the furnace 
 derives its name is either cold blast (q.v.) or hot blast (q.v.). It varies 
 in amount and pressure with the character of the ore and fuel, and 
 quality of pig to be produced. Eoughly, from five to sLk tons weight 
 of air may be required per ton of iron produced, at a pressure of from 
 two to six lbs. per square inch. The blast is urged by blowing 
 engines (q.v.), through a blast main into the tuyeres. 
 
 Blast Kain. — The pipe which conveys the blast (q.v.) from the blowing 
 cylinders to the tuyeres of blast furnaces. Its capacity is large in order 
 to prevent the current from being spasmodic in character. 
 
 Blast Nozzle. — The extreme end of a blast pipe or tuyere which is pierced 
 with the blast orifice. 
 
 Blast Orifice. — ^The mouth or opening of the blast pipe (q.v.) of a loco- 
 motive, through which the exhaust steam finds exit into the chinmey. 
 The diameter of the orifice is often made capable of variation. See 
 Variable Blast. 
 
 Blast Pipe. — The pipe which conveys the exhaust steam from the cylin- 
 ders of a locomotive or similar high-pressure engine into the chimney. 
 The introduction of the blast pipe marked a most important era in the 
 history of steam locomotion, its agency in producing a rapid forced 
 draught being of vital importance. The escape of exhaust steam through 
 a contracted orifice, by creating a partial vacuum in the chinmey, causes 
 the heated gases from the furnace to traverse the tubes with an ac- 
 celeration of speed, with the immediate effect of producing more rapid 
 combustion. See Variable Blast. 
 
 Blast Pressure Gauge. — A gauge used to indicate the pressure of the 
 blast in the blast mains of smelting furnaces and cupolas. It is placed 
 in communication with the current by means of a stop cock, and the 
 height to which a column of mercury is raised thereby indicates the 
 blast pressure. The graduations are those of ounces of pressure on the 
 
 D 
 
34 DICTIONARY OF TERMS USED IN 
 
 . square incli, or of inolies of -water, or of botli in combination ia the 
 same gauge. 
 
 Blast Stove. — See Hot Blast Stove. 
 
 Blazed Pig, or Glazed Pig. — An inferior class of pig iron, highly siliceous, 
 ■which is frequently produced after the first blowing in of a. blast 
 furnace, as well as under certain conditions of regular worMng. Its 
 inferior quality is due to the presence of silicon in large quantity 
 derived from an excess of fuel. 
 
 Blazing Off. — ^A term used in tempering operations, signifying the deter- 
 mination of a definite tempering heat, by the flashing point (q.v.) of a 
 grease or fat in which the article to be tempered is quenched. 
 
 Bleeding. — The red streaks of rust which weep through the scale ad- 
 herent to the insides of boilers, and which reveal the presence of corrosion 
 
 > in the plates underneath. 
 
 Blende, or Zinc Blende. — An ore of zinc, occurring as a sulphide in black 
 or brown lustrous crystals — hence its name. It contains 67 parts of 
 zinc to the hundred. It is found in veins in many English districts, 
 and ia Europe and North America. 
 
 Blind Holes. — Bivet holes which are punched so inaccurately that when 
 the plates are brought together the holes do not coincide withia the 
 extent of an entire diameter. See also Half Bliud Holes. 
 
 Blister Copper. — Metallic copper obtained by the roasting of fine metal 
 (q.v.) in order to expel the sulphur, the metal being then run into sand 
 moulds. Its blistered appearance is due to the ebullition and escape of 
 sulphurous acid gas, S03 
 
 Blisters. — Are defects present in boiler plates of inferior quality due to the 
 non-expulsion of cinder or sand in the original rolhng process. 
 
 Blister Steel. — That quality of cast steel prepared by the cementing or 
 converting process. So oaUed because its surface is covered with 
 minute blisters or bubbles caused by the expansion of carbonic oxide 
 gas, the gas having been generated by the action of oxide of iron upon 
 carbon. 
 
 Block. — The bearing cheeks or pieces, either wood or metal, which carry the 
 pulleys in Mfting tackle. The term also commonly includes the pulleys. 
 
 Block Carriage. — The traveUing frame which carries the chain sheaves 
 upon the horizontal jib of a crane. It is travelled or racked along the 
 jib by racking gear (q.v.). 
 
 Blocking, or Packing. — Short lengths and odd ends of timber balks, 
 planks, deals, and battens which are used in the works, when erecting 
 machinery and various other structures, the blocks being employed for 
 packing up portions of the same. 
 
 Blocking Girders. — The girders which are attached to the under side of 
 the truck frames, both back and front, of travelling cranes. They are 
 made considerably longer than the width of the frames, and are placed 
 in a transverse du-ection to prevent overturning of the crane when 
 lifting cross-ways with a full load, an accident which would happen 
 without the broader base afforded by the girders. The girders are 
 supported upon blocking placed underneath their projecting ends. See 
 Angle of Upset. 
 
 Blocking tip. — The elevating and supporting of masses of machinery by 
 means of cranes, jacks, and blocking. 
 
 Block Setting Crane. — A Hercules (q.v.), or a Titan crane (q.v.), because 
 
 - - designed specially for the setting of concrete blocks in harbour works. 
 
 Block Tin, — See Doubles. 
 
MECHANICAL ENGINEERING. 35 
 
 Bloom. — ( 1 ) Literally a lump, from the Saxon ' ' bloma. ' ' Signifying there- 
 fore, any mass of iron prepared and purified in readiness for the 
 formation of a special forging. (2) A mass of puddled ball -which has 
 undergone the process of sMngHng or squeezing. (3) A mass of piled 
 iron brought into an outline of a shape and size roughly corresponding 
 with that of the article which has to be rolled therefrom. 
 
 Bloomery. — See Finery. 
 
 Blooming Down. — The rolling down of steel ingots into blooms. 
 
 Blooming Mill. — ^A Shingling Mill (q.v.). 
 
 Blooming KoUs. — See Puddlmg Eolk. 
 
 Bloom Steel. — Steel made by the open hearth processes, and rolled into 
 blooms. 
 
 Blow. — ^The forcing of the blast into the tuyeres of blast furnaces and of 
 cupolas, for the purpose of reducing ore in the former, and of melting 
 the iron in the latter, is called the blow, or blowing, or the blast. The 
 forcing of air through the molten metal in a Bessemer converter is also 
 called the blow, but has reference to a definite period of the process, 
 that period during which the carbon is being oxidised or burnt out. 
 A blow is, in foundry language, caused by the imprisonment of air and 
 gas in the metal of a mould. See Blow Hole. 
 
 Blowers. — Machines employed for the production of artificial currents of 
 air, and utilised for the production of blast, ventilation, c&c. They are 
 for the most part either blowing cylinders (q.v.) and pistons, or rotary 
 blowers (q.v.). The advantage of blowers over fans is that they can 
 be driven at a much slower speed, with a corresponding economy of 
 motive power, and increased safety, and that the amount of blast which 
 they will deliver is of a. positive character, and therefore measurable 
 and under control. 
 
 Blow Hole. — Blow holes are hollow cavities in castings, caused by the 
 presence of air or gas in the moulds into which the castings were run, 
 and which become entangled among the molten metal, in consequence 
 of imperfect venting. Blow holes of a bluish colour imply the presence 
 of sulphur in the metal. 
 
 Blowing. — The application of the blast to a foundry cupola. 
 
 Blowing Cylinders. — Cylinders employed for pumping the air under 
 pressure into the blast main (q.v.). They are double acting, having 
 valves in both top and bottom. A large blowing cylinder will discharge 
 
 ■ as much as 50,000 cubic feet per minute under a pressure of from two 
 to ten lbs. per square inch. 
 
 Blowing Engine. — An engine used for driving blowers. ITor blowing 
 cylinders the engine will be of a reciprocating type, for rotary blowers 
 a rotary engine (q.v.) will be used, or a three -cylmder engine (q.v.). 
 
 Blowing Fan. — An ordinary fan used for blowing. 
 
 Slowing Off. — The periodical driving out of the lower portions of the 
 water of a steam boiler, in order to prevent accumulation of solid 
 matters, and consequent incrustation (q.v. ) . 
 
 Blowing Through. — The sending of a jet of steam through the cylinders, 
 valve.'!, and condenser of a condensing steam engine in order to create a 
 vacuum before starting. In high-pressure engines, blowing through is 
 accomplished through the ports and pet cocks to clear the oyhnders of 
 the water of condensation. 
 
 Blown. — A casting is said to be blown when it is honeycombed with blow 
 , holes (q.v.). 
 
 Blown In. — Blast furnaces are said to be "blown in," or to be "in 
 
36 DICTIONARY OF TERMS USED IN 
 
 blast ' ' when they are in full working order. They remain so except when 
 repairs are needed, or trade is too bad to make them pay. Blowing in 
 is an operation which takes three or four weeks to fuUy effect. 
 Blown Out. — Blast furnaces are blown out, or "out of blast," when they 
 are doiug no work, being extinguished either through badness of trade 
 or want of repairs. 
 Blow Oif. — The pipe and cook used for emptying an engine boiler of its 
 contents. It is situated at the lowest part of the boiler. The practice 
 of blowing off is one preventive of incrustation (q.v.). 
 Blow-off Bend. — A bend pipe which connects the blow-off cock (q.v.) with 
 the blow-off seating (q.v.) in a Lancashire or Cornish boiler, and 
 through which the blowing off takes place into the ash pit. 
 Blow-off Cock. — A plug cock, by whose opening the blowing off of a boiler 
 
 is effected. 
 Blow-off Seating. — ^The blow-off cock, or its bend, is attached to a 
 separate casting called a seating, in Lancashire and Cornish boilers. 
 The seating is fitted to the curve of the boiler, and furnished with a 
 flange for the attachment of the bend or cock. 
 Blows. — Signifies the number of charges (q.v.) which are drawn from a 
 
 blast furnace, or a cupola in a given time. 
 Blow-through Valve. — A valve in use with condensing marine engines. 
 Its purpose is the clearing of the cylinder, condenser, and air-pump of 
 the air which they contain, and the supplying its place with steam, which 
 being immediately condensed, creates a vacuum. This is necessary 
 before the engines can be started. The valve when opened makes a 
 communication between the steam in the valve casing and the con- 
 denser. 
 Blue. — See Prussian Blue. 
 
 Blue Bath. — A bath of dilute hydrochloric acid, containing 8 or 9 per 
 cent, of acid, in which phototypes (q.v.) are bleached after having been 
 developed in the prussiate bath, and washed in the water tray. It 
 becomes blue through contact with the prussiate of potash. Also 
 called acid bath. TMs bath is lined with gutta-percha. 
 Blue Billy. — A fettling (q.v.) used for puddling furnaces in the Cleveland 
 district. It is a residual product derived from the roasting of copper 
 pyrites. 
 Blueing. — The heating up or letting down of the temper of steel until it 
 assumes a blue colour. A dark blue corresponds with a temperature of 
 about 570° F., and is the colour for springs. 
 Blue Line Phototype. — See Phototype. 
 Blue Lines. — See Dimension Lines. 
 Blue Metal.— See Pine Metal. 
 
 Blue Print.— A phototype (q.v.) in which white lines appear on the blue 
 ground. 
 
 Blue Process See Phototype. 
 
 Blunt File.— A file which is nearly but not quite parallel throughout its 
 length. The term blunt relates to the point, sometimes called "blunt 
 pointed," to distinguish it from a taper file (q.v.). 
 Board.— Thin timber as distinguished from planks. Anything below 
 about two inches in thickness would be called a board, above that a 
 plank. Strictly speaking, however, a plank should not measure less 
 than three inches in thickness. 
 Bob.— The pear-shaped or globular weight depending from a plumb-line. 
 Sometimes applied to the beam of an engine. 
 
MECHANICAL ENGINEERING. 37 
 
 Bob lever,— See Rocking Handle. 
 
 Body. — (1) The main portion of a pattern, casting, or forging, as distin- 
 guished from its auxiliary or subsidiary portions. (2) As applied to oils, 
 signifies the degree of consistence or viscosity of the oil. A heavy oil is 
 one with much body, a light oil signifying, on the other hand, a thin fluid 
 oil. The mineral oils when purified have little body, so also has sperm ; 
 "while castor oil and some of the vegetable and animal oils and fats, as 
 lard and tallow, have a good body. Body must not, however, be con- 
 founded with resinous properties which some of the vegetable oils 
 possess and which cause gumming (q.v.). The oils having most body 
 are used for heavy shafts, for engine cylinders, and for high tempera- 
 tures ; those having less body for light machinery. The fluidity of an 
 oil increases with increase in temperature, and with light oils firing and 
 evaporation frequently take place at comparatively low temperatures. 
 
 Body Core. — The main or principal core in a mould, as distinguished from 
 branch or smaller cores. The body core of a cylinder is that which 
 forms the bore, in opposition to the passage cores. The body core of a 
 pipe is that in the main pipe itself, as distinguished from branch or 
 Tee cores. 
 
 Bogie. — A swivelling framework which carries the axle of a pair of loco- 
 motive or carriage wheels, and by means of which the main framing is 
 enabled to acconunodate itself to curves of short radius. A bogie truck is 
 a short truck resting on four wheels, and pivoted at its centre to the 
 frames of an engine or carriage, a truck being pivoted at one, or at 
 each end, of the engine or carriage. See Bogie Engine. Its use is to 
 enable the engine or carriage to niu round sharp curves, which it effects 
 by substituting its own short wheel base (q.v.) for the ordinary long 
 wheel base. 
 
 Bogie Engine. — A locomotive provided with a bogie. In the single bogie 
 engines the leading wheels are the bogies, in the double bogie or 
 Fairlie engines the leading and trailing wheels are bogies. 
 
 Boil. — The period during which the carbon is being burnt out of the iron 
 in a Bessemer converter (q.v.). The carbon during this period is being 
 oxidized to carbonic oxide CO, and bums at the mouth of the con- 
 verter. 
 
 Boiled Oil. — See Linseed Oil. 
 
 Boiler. — The vessel in which the steam used in the driving of an engine is 
 generated. Forms and details are numerous and varied. Cornish 
 boilers have one fire flue, Lancashire boilers have two flues. Loco- 
 motive boilers and those of portable engines are multitubular. Vertical 
 boilers are those in which the circular section is in a horizontal plane. 
 Boilers require setting when of the Cornish or Lancashire type, the 
 setting consisting of brickwork and an arrangement of flues built 
 therein. Vertical boilers require no setting. Where there are no 
 smoke tubes, as in Lancashire and vertical boilers, there are cross 
 tubes passing through the fire-box for the purpose of exposing a larger 
 surface to the action of the fire. Marine boilers are a type by them- 
 selves, consisting chiefly of the return multitubular class. Sectional 
 boilers are those in which the steam is generated in a multitude of 
 distinct tubes communicating with one steam chest or receiver. Details 
 of these and of other types of boilers will be found under their speoifio 
 headings. 
 
 Boiler Bear. — See Punching Bear. .. ,.■> 
 
 Boiler Capacity. — See Heating Surface. \ 
 
38 DICTIONARY OF TERMS USED IN 
 
 Boiler Circulation. — See Circulation. 
 
 Boiler Coating. — Non-conducting compositions are used to prevent tho 
 radiation of heat from steam boilers. Such compositions are smeared 
 over -while in a plastic state and become hardened by the heat. Various 
 materials are employed, comprising felt, silicate cotton, cements, sOicate 
 compositions, asbestos, &c. They are mostly patented preparations. 
 
 Boiler Corrosion. — Is either internal or external. Internal corrosion wiU 
 result either from the presence of acidulated water (q.v.) attacking the 
 plates below the water level, or from superheated steam in the steam 
 chamber. External corrosion is the result of leakage, and of contact 
 with damp foundations and seatings. 
 
 Boiler Crown. — The uppermost plate in tie shell of a vertical boiler. It 
 is of a hollow discoid shape, flanged around the edges, and riveted to 
 the outer shell plates. Sometimes it is of a flat form only and stayed. 
 The boiler crown proper is that belonging to the outer shell. The fire- 
 box crown is that over the top of the furnace or inner shell. 
 
 Boiler Dome. — The superheatiog chamber of a multitubular boiler. It is 
 usually of one piece, welded up and flanged at top and bottom, and 
 encased in a brass mounting. 
 
 Boiler Explosions. — These are almost invariably due to overpressure (q.v.) 
 of steam, the overpressure taking place by reason of the boiler being 
 taxed beyond its capacity ; the chief sources of overpressure being weak- 
 ness due to faulty original design, to weakness caused by wear and 
 tear, by bad workmanship, by sudden strains put upon a structure, 
 which, though strong enough to withstand ordinary pressures, is not 
 able to sustain a sudden and excessive stress applied thereto. Unstayed 
 or imperfectly stayed surfaces are examples of bad design, as are also the 
 use of plates, stays and rings too weak for the pressures which they 
 are designed to carry. Corrosion and grooving are examples of wear 
 and tear. Among the errors of bad materials and workmanship may be 
 classed the use of laminated and pitted, or of brittle plates, excessive 
 diifting, hard caulking, &c. ; while overheating, with the consequent 
 weakening due to increase in temperature, the accumulation of deposit 
 over the fire, lowness of water, are illustrations of sudden straining ; 
 and also the too rigid attachment of boilers to their seatings or foun- 
 dations cause overstraining by preventing freedom of expansion and 
 contraction. 
 
 Boiler Feed. — The water supply of a boUer. 
 
 BoUer Feeder. — (1) The agency by which the water supply of a boiler ia 
 maintained, tlsually it takes the form of a force pump (q.v.) or of an 
 injector (q.v.). (2) The reservoir from which the supply of water for a 
 boiler is diawn. (3) A feed water heater (q.v.). (4) An old-fashioned 
 arrangement for regulating the water supply consisted of a float at the 
 water level connected by a chain with a lever attached to a valve, which 
 last, being lifted by the lowering of the float, allowed a definite amount 
 of water to flow into the boiler. 
 
 Boiler Fittings. — Those additional portions of boiler work which, thouo'h 
 not considered as parts of the shell, are yet essential to its completion. 
 They are usually charged for extra, and comprise man-hole and mud- 
 hole doors, fire bars and their bearers or rings, furnace doors, dampers 
 and frames, the various fittings being subject to modification by the 
 special type of boiler to which they are attached. 
 
 Boiler Float. — In old egg-end and waggon boilers feed was regulated . 
 
MECHANICAL ENGINEERING. 39 
 
 by means of a float and chain, whicli rising and falling witli fluctua- 
 tions in level indicated tie height of the water. 
 
 Boiler Incrustation. — See Incrustation, Soda, Carbonate of Lime, &o. 
 
 Boiler leakage. — See Leakage. 
 
 Boiler Maker. — The work of a boiler maker consists in marking out the 
 plates of boilers to size and shape, in marking and punchiag the rivet 
 holes, in riveting together and caulking up the seams, in fitting tubes, 
 gussets, stays, strengthening rings and steam chests. Here his work 
 ends, and the boiler is handed over to the engine fitter to receive its 
 fittings and mountings. 
 
 Boiler Makers' Dolly. — See DoUy. 
 
 Boiler Mountings. — Those additional portions of boiler work, extraneous 
 to the shell, but which are essential to the proper working of the boiler. 
 They are usually charged for extra, and comprise safety and stop 
 valves, blow-off cock, steam and water gauges, try cocks, back pressure 
 valve, and fusible plugs. 
 
 Boiler Plate. — The plate from which steam boilers are manufactured. It 
 is not a special brand of plate, but ordinary best best, or treble best, or 
 Lowmoor plates. Usually treble best is used for the shell, and 
 Lowmoor or other similar quality for the flre-box. Sometimes the 
 crown fire-box plates are Lowmoor, and the body treble best. The 
 specification always fixes the quality of plates used in contract boilers, 
 though usually leaving the manufacturer to make his choice from 
 several houses. The tensile strength of ordinary wrought-iron plates 
 should be 21 tons per square inch with the grain, that is in the direction 
 in which the plates are rolled. Lowmoor plates will bear a strain of 
 24 tons with the grain. The tensile strength of mild steel plates should 
 range from 26 to 32 tons. 
 
 Boiler Pressure. — The pressures in steam boilers vary with the type, the 
 age, and the condition of the boiler. In externally fired, waggon, and 
 egg-ended boilers they will vary from 15 to 20 lbs. per square inch 
 above the atmosphere. In new Cornish and Lancashire boilers, well 
 stayed, from 45 to 60 lbs., reduced when worn to 25 or 35. In loco- 
 motives and portables, from 120 to 150 lbs., gradually reduced with age 
 to 100, or less. In marine return tube boilers, from 100 to 180, 
 according to sae and construction. The pressure is adjusted with the 
 safety valve, and indicated by the pressure gauge. 
 
 Boiler Prover, — A force pump and pressure gauge combined, employed 
 for testing boUers by hydraulic pressure. 
 
 Boiler Scaling Hammer. — See Scahng Hammer. 
 
 Boiler Section. — See Effective Section, and Gross Section. 
 
 Boiler Shell. — The outer body, or casing, pertaining to a boiler ; which 
 encloses the water and fire spaces in internally fired boilers ; and the 
 water space only in externally fired boilers. 
 Boiler Shop. — A lofty building in which the work of boiler making and 
 the construction of works in angle iron and plate is carried on. A few 
 forges are ranged down one side, the whole of the central portion being 
 left free for the building up of work, which is moved about by a 
 powerful overhead traveller. The machines are placed in an open part 
 of the shop to allow freedom of manipulation for the bars, angles, and 
 plates. 
 Boiler Smithy. — A department of the boUer shop containing smiths' 
 forges, where angle iron, tubes, and the lighter work of that class are 
 bent and welded. 
 
40 DICTIONARY OF TERMS USED IN 
 
 Boilers, Setting of. — The laying of stationary boUers upon suitably pre- 
 pared foundations of brickwork. The flues are built in the brickwork 
 to form either a split draught (q.v.) or a wheel draught (q.v.), and a 
 certain amount of inclination (q.v.) is given to the boilers. 
 
 Boiler Stays. — Screwed rods or smooth tubes which connect and stay the 
 flat ends of steam boilers. Bar stays (q.v.) are screwed into the ends 
 of shells or fire-boxes, and are either secured with nuts or riveted over. 
 Tube stays (q.v.) are riveted and beaded over. Gusset stays (q.v.l are 
 riveted. Copper, steel, and wrought iron are the materials used for 
 
 Boiler Testing. — The testing of the strength of steam boilers, or their 
 capacity to withstand the internal stresses due to steam pressure, is 
 mostly performed by the pressure of water produced by a test pump, 
 the amount of pressure being recorded by one or more dial gauges 
 placed in communication with the interior of the boiler. The test 
 pressure is usually from one and a half to twice that of the actual 
 pressure to which it is intended to work the boiler. The test should 
 continue for about half an hour, during which time the pressure gauge 
 should not go back at all. If it goes back, that indicates leakage. 
 During the time of the test, the boiler should be carefully examined to 
 detect leakage at the seams and rivet heads ; any alterations in diameter 
 of the shell, or in the shape of the end plates radicating bulging stresses 
 should also be recorded, and noted, and compared with the condition of 
 the boiler when the test pressure is removed, to ascertain the amount 
 of permanent set, and also to detect sections of inherent weakness 
 of structure. Boilers are sometimes also tested with steam, a practice 
 which was formerly universal, but ia now resorted to chiefly in the case 
 of locomotive and portable boilers, it being considered that testing 
 by steam causes the test to approximate more nearly to the conditions 
 of actual practice. 
 
 Boiler Tubes. — Tubes used for increasing the efficiency of a steam boiler 
 by the enlargement of its heating surface (q.v.) without increasing its 
 bulk. See Field Tubes, Galloway Tubes, Multitubular Boiler, Tube 
 Stays. 
 
 Boiling. — The process of purifying tin by holding stakes of wet wood 
 under the molten metal while it is in the refining basin. The steam 
 evolved causes an ebullition of the metal to the surface where the im- 
 purities present therein become oxidised. After being allowed to settle 
 the metal is ladled out and cast into ingots. The upper stratum is 
 called refined tin, the lower common tin. 
 
 Boiling Point. — The temperature at which a liquid throws ofB bubbles of 
 vapour or steam, producing an ebullition at the surface. Pure water in 
 an open vessel, at a pressure of 30 inches of mercury, boils at 212° F. 
 or 100° 0. The presence of sohds in solution or an increase of pressure 
 raises the boiling point. The boiling point is lowered by a reduction 
 in pressure. 
 
 Bollard. — A cast-iron pillar used for the mooring of vessels on quay 
 walls. Also the pillars of cast iron bolted to the bulwarks of vessels 
 for the coiling of a rope when paying out or heaving to. 
 
 Bolster. — (1) A plate or disc of metal which sustains articles of wrought 
 iron or steel through which holes are being punched. A hole in the 
 bolster a trifle larger than the punch permits the button to pass through, 
 while its adjacent edges by sustaining the edges of the plate around 
 the punched hole prevent buckling or bending of the same. (2) The 
 
MECHANICAL ENGINEERING. 41 
 
 bearings that fit ■within the housings (c[-t.) in forge and mill rolls, and 
 which sustain the roUs. 
 
 Salt. — A fastening employed hy engineers. In the ordinary form of bolt 
 the head is forged with the shank — the end opposite or the tail being 
 screwed to receive the nut by which the bolt is secured. Both heads 
 and nuts may be either rectangular or hexagonal in form. To prevent 
 the tendency to turn round, the shoulder or neck underneath the head is 
 often made rectangular to fit into a square hole. The various forms of 
 bolts will be found described under their respective headings. 
 
 Bolt Cutter. — A machine for cutting the heads of bolts, worked by 
 hand or by pi iwer. 
 
 Bolt Head. — The flattened expansion at one end of a bolt. It is usually 
 rectangular or hexagonal in form, its shape generally corresponding 
 with that of the nut. 
 
 Bolt Machine. — A machine used in the smithy for the forging of the tails 
 or shanks of bolts. It consists essentially of a series of stamps or dies, 
 the lower pieces being fixed, the upper ones movable in a vertical 
 direction. The movable dies are actuated by eccentrics turned on the 
 main driving spindle above, and the spindle is provided with a fly wheel 
 for the equalisation of the motion. The diameters of the stamps vary, 
 in descending order, so that the bolts are drawn down by being passed 
 along a succession of dies of diminishing diameters. 
 
 Bolt Oliver. — See Oliver. 
 
 Bomontague. — See Beaumontague. 
 
 Bonding. — See Banding. 
 
 Bonnet. — (1 ) The movable cap or cover which is made removable to permit 
 of the introduction of a pump valve into, or its withdrawal from, its 
 seating. (2) The hood of a smith's forge. 
 
 Bonneted Safety Valve. — A safety valve covered with a casing or bonnet 
 enclosing the valves and communicating with a waste pipe, through 
 which the waste steam is conveyed away without the building. The 
 bonnet and waste pipe prevent the steam from filling the shed or 
 building when the boiler is closely roofed in. 
 
 Boom. — (1) A term applied to the jib of a derrick crane (q.v.). (2) The 
 upper or lower flange of a built-up girder, lattice or otherwise. 
 
 Borax, or Tincal. — Symbol Naa B4 O7 + 10 Hj 0. A sodium compound 
 of the element boron. Used for welding mixtures in steel and iron, 
 and for brazing gun metal and copper. It is also added in small 
 quantity to the zinc thrown last of all into the brass melting-pot or 
 crucible to prevent its oxidation and loss in vapour. It is prepared for 
 use by previous driving off of the water of crystallisation at a high 
 temperature. 
 
 Bore. — (1) The internal diameter of a pipe or cylinder whether it be a 
 rough or a machined casting. (2) Also signifies to turn the internal 
 diameter of hollow cylindrical work. (3) The bore of a wheel is the size 
 of the hole or eye which receives the shaft, and designates the diameter 
 after it has been bored out. (4) The bore of a pipe is the internal 
 diameter as a rough casting. The dimensions of pipes are never given 
 otherwise than as the bore and length. 
 
 Boring. — The operation of making or finishing circular holes in wood or 
 metal. See App. 
 
 Boring Bar. — A stiff cylindrical bar provided with a screw feed to the 
 cutter head. Used for boring cylinders. The bar isfixed in sta:idards 
 
42 DICTIONARY OF TERMS USED IN 
 
 or between latte centres, and revolves -when cutting, the -work being 
 bolted down to tbe bed. 
 
 Boring Collar. — See Cone Plate. 
 
 Boring Flange. — See Drill Plate. 
 
 Boring Head, or Cutter Head. — The ring wbicli carries the cutters of a 
 boring bar. It is actuated by a screw sunk in a recess in the bar itself, 
 and driven by gearing from one end. A boring head may also be fixed 
 on a mandrel, and revolved without endlong movement, the work being 
 made to travel by means of a slide rest against the cutters. 
 
 Boring Lathe. — See Boring Machine. 
 
 Boring Machine. — (1) A machine specially constructed for boring holes in 
 eyhnders, bosses, bearings, and the like. It may be horizontal or 
 vertical in type. The cutter in the former revolves in a circle whose 
 axis is horizontal ; in the latter, in a circle whose axis ia vertical. 
 
 (2) Boring machines are used for wood with brace bits ; for metal, with 
 drills and cutters. Lathes are also boring machines, the work being 
 either fixed or in motion. When the work is fixed, a boring bar set 
 between centres holds the tool and carries it round. When the work 
 revolves the tool is held ia the slide rest. (3) In boring mills the tool ia 
 attached to a bar, being passed through a slot therein and secured with 
 wedges, and both revolves and travels, the bar passing through a hol- 
 low mandrel in the headstock. (4) For boring large cylinders the axis 
 of the cutter is vertical, the cylinders standing on end. 
 
 Boring Mill. — See Boring Machine. 
 
 Boring Kest. — A lathe rest whose outline is that of the letter L, the hori- 
 zontal arm, which is uppermost, being slotted to take the flat of a boring 
 tool or drill, and so prevent it from turning round. The binder end 
 of the boring tool is centred on the poppet mandrel, and by it fed 
 along to its work. Such rests are used with ordinary lathes, and also 
 with lathes of special construction called boring lathes, in which the 
 poppet mandrel is fed forward automatically, through the medium of a 
 back shaft and gearing. 
 
 Borings. — See Turnings. 
 
 Boring Tools. — Brace bits and similar tools for wood, and turning tools 
 and cutters for metal, embracing a large number of types. The ordi- 
 nary boring tool consists of an ordinary roughing or finishing tool, 
 cranked or turned round at the end, right or left handed ; the shank 
 being rounded for a few inches behind the cutting point. Boring and 
 drilling differ in this respect — that boring is performed by a cutter 
 having a single cutting edge, while drilling ia performed by two cutting 
 edges placed on opposite sides of the axis of the tool. Boring is also 
 performed by cutters set in boring heads and boring bars. 
 
 Bosh. — See Water Bosh. 
 
 Boshes. — That area or section of a blast furnace (q.v.) which extends 
 from the section where the diameter is widest down to the crucible. 
 The section of the boshes taken vertically is that of a truncated cone, 
 and the angle is dependent upon the character of the ore and of the 
 fuel, the condition being that the charge shall not sink down too 
 rapidly. 
 
 Boss. — (1) The centre or hub of a wheel. (2) In a more general sense the 
 circular bearing parts of castings which carry shafts, pins, or studs. 
 
 (3) A circular disc pierced with a central hole and cast on framed work 
 fo r increasing the length of bearing parts without adding unnecessarily 
 to the thickness of the remaining or plated portion of the structure. 
 
MECHANICAL ENGINEERING. 43 
 
 Bossed TTp. — A forging is bossed up wlien a circular disc of a sensible 
 tMckness is formed upon its face, being either made from the solid iron 
 by upsetting and finishing to outline, or by -welding on. Turniag the 
 edges of such bosses in the lathe, for the production of bright work, is 
 also called bossing up. 
 
 Bossing machine. — A steam hammer used for welding the bosses on the 
 "wheels for roUing stock. 
 
 Betting. — Closing the tap hole of a cupola with clay after a ladle of 
 molten metal has been tapped out. 
 
 Bottle Jack. — A screw jack of light construction, which is slightly coni- 
 cal in elevation, and provided with a handle at the side, by which it is 
 carried. Its shape is, therefore, not unlike that of a jug or bottle, 
 hence the name applied to it. 
 
 Bottle Tight. — Signifies that the seams, rivets, fittings and mountings of a 
 steam boiler make such close and perfect joiats that there is not the 
 slightest leakage when tested under water or steam. 
 
 Bottling Tip. — The temporary confinement of the steam in the tubes of a 
 sectional boiler, due to its too rapid generation. The steam accu- 
 mulates until it acquires suffioient energy to force its way to the steam 
 dome. When this occurs, cool water rushes in to supply its place, and 
 undue strain is put upon the tubes due to the sudden change in 
 temperature. 
 
 Bottom Board. — The hoard upon which the joint of a pattern is laid while 
 being rammed up. Its purpose is either to stay and sustain a weak 
 pattern, or to make the moulder's sand-joint, hence called joint board. 
 
 Bottom Card. — An indicator card, taken from the bottom of a vertical or 
 oscillating cylinder. In a bottom card the lead Kne (q.v.) is on the 
 right-hand side. 
 
 Bottom Face. — That face of a mould or casting which is downwards 
 when pouring. The bottom face is always sounder than the top face 
 (q.v.), since the sullage floats to the top, and the liquid pressure conso- 
 lidates the lower metal. 
 
 Bottom Flue. — A flash flue (q.v.). 
 
 Bottom Fuller. — A fullering tool (q.v.) which is laid on the anvil, or set 
 in the square hole near its end. 
 
 Bottoming. — The rubbing or grinding of the points of wheel teeth in the 
 roots of the teeth of the wheels into which they gear. It is due to 
 want of bottom clearance or to badly-fitting shafts. 
 
 Bottoming Tap. — A plug tap which is not rounded off at all at the end, 
 but finishes with square edges in order that it may cut its thread per- 
 fectly to the bottom of a drilled hole. 
 
 Bottom Part. — The lower part or section of a foundry moiilding box. 
 "With bedded-in work the bottom part would signify the portion of the 
 mould in the foundry floor. 
 
 Bottom Bake. — The angle of relief (q.v.) in cutting tools. 
 
 Bottoms. — An impure aUoy of copper with antimony, tin, lead, iron and 
 sulphur, which results when fine metal (q.v.) is roasted for the purpose 
 of obtaining a pure regulus from which to manufacture best selected 
 copper. 
 
 Bottom Tool. — The lower half of a fullering tool (q.v.). 
 
 Bott Stick. — A light iron rod of about five or six feet in length, having a 
 small disc-like expansion at one end which receives the stopper of clay 
 used for hotting (q.v.). The other or pointed end of the rod is used for 
 tapping the hole for the egress of the metal. 
 
44 DICTIONARY OF TERMS USED IN 
 
 Bouche. — A tush (q.v.). 
 
 Bourdon's Gauge. — See Dial Gauge. 
 
 Bow Compass. — See Spring Bows. 
 
 Bow Conneotinff-Eod, or Kite Connectiag-Eod, or Banjo Frame. — A 
 form of connecting-rod employed in steam pumps, where compactness 
 of arrangement is sought after. It is triangular in outline, and the 
 crank which drives the fly-wheel is enclosed by the bow. 
 
 Bow Drill. — A fiddle drill. Made by stretching a cord between the 
 ends of a rod curved like a bow. The drill is inserted in a reel or small 
 pulley around which the cord is twisted. The drawing of the bow 
 backwards and forwards revolves the reel and with it the drill in 
 opposite directions alternately. Bow drills are useful only for light 
 work, and are employed in engineers' workshops chiefly for drilling 
 up the ends of shafts and other cylindrical work which has to be 
 centred in the lathe. 
 
 Bower's Process. — Has for its object the same result as BarfB's process 
 (q.v.), but air instead of steam is the oxidising agent employed. 
 
 Bow File. — A riffler (q.v.). 
 
 Bowling Hoop. — A ring whose single section is that of an arch with side 
 expansions or flanges for the reception of rivets. Employed for xmiting 
 the sections of furnace shells in horizontal boilers. 
 
 Bowling Iron. — Iron plate produced by the Bowling Iron Company, in 
 Yorkshire. Its quality is considered about equal to that of Lowmoor 
 (q.v.) and is therefore often substituted for the latter for the crowns of 
 the fire-boxes of boilers, and other work where first-class material is in 
 request. 
 
 Bowl Sleepers. — ^Pot sleepers (q.v.). 
 
 Bows. — Short drawing compasses, similar in shape to those of larger 
 dimensions excepting that the head is made circular in order that it may 
 be rolled with facility between the thumb and forefinger. See Spring 
 Bows. 
 
 Bow Saw. — A narrow-frame saw, held in tension hy the leverage afforded 
 by the twisting of a cord. These saws are used for cutting curves, 
 hut the band saws have mostly superseded them in workshops. 
 
 Bowstring Girder. — A girder in which the outward or horizontal thrust 
 of a carved beam is sustained by a horizontal tie beam forming the 
 chord of the arc. 
 
 Box. — (1) A bearing for a shaft. (2) A box coupling (q.v.). 
 
 Box Coupling. — A shaft coupling made as a hoUow cylinder to fit over 
 the abutting ends of the shafts to be coupled together, and held in 
 place with keys. Sometimes called muff coupling. 
 
 Box End. — A connecting-rod end having no loose strap end (q.v.), but 
 in which, instead, the brasses are thrust into a slot from one side and 
 slid along to their seatings, the side flanges on one face being removed 
 to permit of their sliding in. The brasses are tightened with a 
 cottar (q.v.). 
 
 Box Filling. — The filling up of a moulding box with its body of sand 
 enclosing a pattern. This is usually labourer's work, and is distinct 
 from the ramming. The moulder rams while the labourer is engaged 
 in filling in. 
 
 Box Girder. — A wrought-iron girder buUt up with two parallel joists or 
 girders of I-iron, of equal depth, united at top and bottom with flat 
 plates, riveted to the flanges of the joists. Also termed a tubular 
 girder. 
 
 Boxing ITp. — The construction of heavy patterns by a process of reot- 
 
MECHANICAL ENGINEERING. 45 
 
 angular framing together of thin boards in preference to cutting them 
 from solid planking. 
 
 Box Link. — A slot lirik (q.v.) Trhose internal faces are recessed, so that 
 the shifting-block is partly embraced by the edges as -well as by the 
 internal faces. 
 
 Box Metal. — Sometimes applied to the metal used for bearings ; it may 
 be gun metal, or a white metal. One recipe gives copper 32, tin 6 : 
 another gives zinc 75, tin 18, lead 4-5, antimony 2-5. 
 
 Box Nut. — A nut made for the covering and protection of the end of a 
 bolt. It is similar to an ordinary nut, with the addition thereto of a 
 dome-shaped closed end. The screwed part is also terminated 
 internally in a circular recess larger in diameter than the deepest 
 portion of the Vee of the thread, in order that the cutting tap shall 
 clear itself. Box nuts are used on the covers of locomotive cylinders 
 and in similarly exposed situations. The screwed bolt ends and their 
 nuts are thus both alike protected from rust or accident, hence there is no 
 difficulty in slackening back when necessary. Also termed cup nut. 
 
 Box Safety- Valve. — A bonneted safety-valve (q.v-). 
 
 Box Spanner. — A spanner used for those bolts whose heads are sunk 
 below the surface of the material into which they are inserted. The 
 box-spanner end is circular without and square or hexagonal within to 
 receive the nut. The circular portion drops into a round hole somewhat 
 larger than the head of the nut and bored concentrically around it. 
 
 Box Standard, or Boxed Standard. — The standard, or main framework, 
 of a machine or engine, which is hollowed internally to obtain 
 the maximum of strength with the minimum of material. See Hollow 
 Structures. 
 
 Box "Wood [Buxus sempervirens). — Sp. gr. ]'04. A hard, tough, close- 
 grained wood of a pale yellow colour, belonging to the order 
 Muphorbiaeece. Its valuable properties of hardness, toughness, and 
 freedom from susceptibility to warping and shrinking, have led to its 
 employment in the manufacture of rules and scales for workshop and 
 office use. Previous to being worked up it undergoes several years of 
 Beasoning. It is also employed for some small tools as planes and 
 spokeshaves, and for tool handles. A cubic foot weighs 64:'8 lbs. 
 
 Boyle and Marriott, Law of. — The law of Boyle and Marriott, so named 
 after its discoverers, is that the volume of a gas varies inversely as the 
 pressure to which it is subjected. In engineering this law has its 
 application in the expansive working of steam in a closed cylinder, and 
 in calculations pertaining to gas and air engines. 
 
 Brace. — A tool used for actuating bits and drills for boring wood or 
 metal, and varying in character with the class of work which it is 
 designed to do. The brace for boring wood is made of wood and iron 
 in combination, or entirely of iron. It is turned directly by the hand 
 alone. For light drQUng in metal, a brace having a couple of bevel 
 wheels to actuate the drOl is used. Tor heavier work a smith's brace 
 is employed, turned, as in the first instance, by hand, but the requisite 
 pressure is imparted by a screw at the top. For the heaviest drilling a 
 ratchet brace is used, in which the drill is moved by a long lever, and 
 the pressure is derived from an arm which receives the reaction of the 
 drill, the feed being imparted by a screw and nut. 
 
 Brace Bits. — The ordinary bits used for wood boring, and having square 
 tapered shanks to fit in the socket of a common brace. 
 
 Braced Girder. — A built-up lattice girder. 
 
46 DICTIONARY OF TERMS USED IN 
 
 Braced Truss. — A truss, either braced witli single braces or counter- 
 braced with diagonal ties and struts, to sustain the stress of il moving 
 load -without deformation. See Bracing, Counter Bracing. 
 
 Braced Work. — See Bracing. 
 
 Bracing. — The staying or supporting of inherently weak structures with 
 rods and ties. The object of bracing is the conversion of transverse 
 stresses into those of a longitudinal character. Tensile or compressive' 
 braces take the form of triangles, since that is the only figure which 
 maintains its foitu xmaltered while the lengths of its sides remain con- 
 stant. Bracing is practised in all built-up structures, as bridges, roofs, 
 cranes, girders of various kinds, and the calculation of the strains on 
 the different members comprising the structure is obtained readily by 
 graphic methods, or by the method of moments. 
 
 Bracket. — A rib occupying an angle in a casting, or in built-up wroiight- 
 iron work and placed there for the strengthening of a plate or flange. 
 The term, however, is one of very wide apphcation in engineering, 
 being used to denote castings themselves which have a resemblance, 
 however remote, to the typical bracket. It is often employed to. 
 denote bearings of many different kinds, as, for instance, those which 
 are bolted to walls to carry plummer blocks for shafting, or those- 
 which depend from timber, also to carry shafting, and castings bolted 
 upon bed plates, and so on. 
 
 Bracket Pedestal. — A wall bracket (q.v.). 
 
 Brad. — A cut naU, rectangular in section and having a head or lip on one 
 side only. Used for pattern work and by moulders for mending and 
 staying broken and weak sand. See Sprigging. 
 
 Brad Awl. — A boring tool used pre-vious to the insertion of brads and 
 nails. It first di-vides the fibres by means of its cutting edge, and 
 then thru.sts them aside, but does not extract them. 
 
 Brad Punch. — A blunt pointed steel rod used for hammering the heads of 
 nails slightly below the surface of the wood into which they have been 
 driven, when, for the sake of appearance, it is undesirable that the 
 heads of the nails should be seen, the head of the punch being struck 
 by the hammer, similarly to the centre punch. 
 
 Brake. — (1) The mechanism by which a train is brought rapidly to a 
 standstUl. {'!) The frictional arrangement by which the de-jcent of 
 Heavy loads is regulated. The ordinary brake consists of a flexible 
 strap of -wrought iron, lined with wooden blocking, embracing the 
 periphery of a smoothly turned iron wheel, and is made capable of 
 being tightened round the iron by the intervention of a lever, or of a 
 hand wheel and screw. 
 
 Brake Blocks. — The short blocks of wood which arc screwed to a hooped 
 iron strap to form a flexible brake around the rim of a brake wheel. 
 
 Brake Cylinder. — The cylinder of a steam or of a water brake. 
 
 Brake Drum. — A large wooden drum used for -winding the rope or chain 
 which lifts and lowers the cages or the trucks on colhery or quarry 
 works. Called also a winding drum. " Brake drum" refers to the 
 method by which its action is controlled, being that of a brake. 
 
 Brake Handle. — The handle of a brake lever. 
 
 Brake Horse-Power. — The horse-power of an engine or machine taken off 
 a brake attached thereto. The instrument employed for the purpose is 
 the friction dynamometer (q.v.), and the advantage of its employment 
 is that the net useful work given out is then directly obtained, whereas 
 when the horse -power is taken by the indicator, a doubtful allowance 
 
MECHANICAL ENGINEERING. 47 
 
 has to be made and deducted for the power absorbed by the engine 
 itseK, due to friction and other losses. 
 
 Brake Lever. — The lever by means of which the action of a brake is con- 
 trolled. It may be a hand or a foot lever. 
 
 Brake Power. — The frictional resistance developed by a brake. It is 
 expressed in any convenient units, or as an equivalent to a definite 
 amount of mechanical force against which it is set off. 
 
 Brake Shoe. — The block of wood which is thrust against a trolly or truck 
 wheel by the brake levers to arrest its motion. 
 
 Brake Strap. — The enoircliag band of hoop iron to which the brake 
 blocks (q.v.) are screwed in the friction brake of a crane or hoisting 
 machine. 
 
 Brake Wheel. — A wheel whose periphery is turned to receive the pressure 
 of the brake strap and blocks, the whole with the necessary levers 
 constitutiag a friction brake. The brake wheel may be either a 
 distinct casting or a ring simply cast on the face of one of the toothed 
 wheels. 
 
 Braking. — The application of brake power to a machine. 
 
 Bramah's Press. — The hydraulic press (q.v.) as first invented, embodying 
 the practical application of the principle that hydraulic pressure is 
 directly proportional to the head and to the area of surface. 
 
 Bran. — Is used for rubbing over the plates of sheet iron used in tin-plate 
 manufacture, in order to dry them after the pickling process. 
 
 Branch. — ^An offset from a pipe which diverts the contents of the pipe into 
 another channel, or which conducts into the pipe. 
 
 Branch Pipe. — A. pipe having offsets or branches, that is, short outlet 
 pipes attached to the main axis. 
 
 Brands, — (1) Certain marks used to distinguish the qualities of wrought 
 iron and steel plates and bars. They are not uniform tests, since the 
 similar brands of different makers will often indicate different qualities 
 of iron. By the distinguishing marks cast or stamped by manufac- 
 turers upon the materials of construction, their own special quaUties 
 of iron, and the blast furnaces or rolling miUs at which they are pro- 
 duced, are at once apparent. Sometimes the initials of the firm or 
 company are given, often the initials are quite arbitrary, often fanci- 
 ful, like telegraphic code words, frequently there is a heraldic device in 
 addition — a Hon, a tortoise, a gun, &o. These then indicate some 
 definite qualities of iron, even though the B B or B B B themselves are 
 omitted. Crown quality is often represented by the drawing of a 
 crown to which the letter B, or B B are added. Keys to all the brands 
 used by all the houses in the kingdom are supplied in Eyland's well- 
 known Directory of the iron trades. (2) Brands, or branding-letters, are 
 block projecting letters cast upon the ends of hght rods or handles, and 
 used for burning manufacturers' initials and names into timber, packing 
 cases, &c. 
 
 Brasque. — A mixture of coke or coal dust, with or without powdered gas 
 carbon and coal-tar. Used for the lining of various furnaces to pre- 
 vent the corrosion of certain slags. 
 
 Brass. — (1) An alloy of copper and zinc, or copper, zinc and lead. It is 
 used for the cheaper kinds of cocks, lubricators and pumps. The term 
 is, however, used rather loosely, being also applied to gun metal (q.v.). 
 (2) The term is commonly applied to the bearings for the journals of 
 shafting, the half bearing being termed a brass, the two bearings a pair 
 of brasses, and the bearings with their seatings a plummer block or 
 
48 DICTIONARY OF TERMS USED IN 
 
 pillow Wook. 1 heee 'bearmgs are not actually made in brass, but in 
 gun metal, -wHch is harder and more durable. 
 
 Brass Bench. — The bench of the brass moulder consists of a plain table, 
 either of wood or iron, upon which the moulding flasks are manipu- 
 lated, and of a bin or trough containing the sand. 
 
 Brass Borings. — The borings and turnings of brass castings collected in 
 the shops are separated from those of iron by magnetting (q.v.) to be 
 remelted. 
 
 Brass Contraction. — See Contraction, Contraction-rule. 
 
 Brasses. — See Brass. 
 
 Brass Finishing. — The later stages of the manufacture of brass cocks, 
 valves, lubricators, and similar engine and pump fittings. It is a 
 special branch carried on in a department or in a factory by itself. 
 It combines turning, milling, grinding and burnishing. 
 
 Brass Foundry. — The department in which brass moulding is performed 
 is usually either separate from, or a section divided off from the iron 
 foundry, special materials and appHances being employed therein. 
 
 Brass Furnace. — The furnace in which brass and gun metal are melted. It 
 is an air furnace (q-v.), or an " air crucible furnace " (q.v.), and is built 
 in brickwork partly below and partly above the level of the foundry floor, 
 the draught passing through it from a grating in front to the chimney 
 behind. It is usually made to hold but one crucible at a time, an 
 increase in melting power being obtained by increasing the number of 
 furnaces, which are then ranged side by side. The crucibles are lifted 
 out of the mouth or top of the furnace with the crucible tongs. When 
 large castings are required a reverberatory furnace is often employed. 
 
 Brass Moulder. — The work of moulding and casting brass is a special 
 department of foundry practice, almost invariably performed by a 
 workman specially trained to it, who seldom touches iron mouldmg. 
 Good brass moulders receive higher wages than ordinary green sand 
 moulders, and do much of their work by the piece. 
 
 Brass Sieve. — See Sieve. 
 
 Brass Tubing. — Is used to a slight extent in engineering for cutting off 
 into hand railing, sheathing, distance pieces, &c. Its thickness is 
 given by the wire gauge. The common tube is soldered or brazed ; 
 but the best tubes used for condensers are solid drawn, and usually 
 made of an alloy of brass. See Muntz Metal. 
 
 Brass Wire. — Is put to a variety of uses in engineer's work. It is hard 
 when unannealed, soft when annealed. Its dimensions are those of the 
 wire gauge. 
 
 Brasswork. — The small mountings of steam boilers, gauges, hose unions, 
 cocks, valves, whistles, and similar works are made in common brase, 
 various mixtures being employed. When mixing brass, care must be 
 taken to use the same mixtures for work which is in immediate proxi- 
 mity, since the colours vary with the mixtures. Brass is sometimes 
 variously named according to its colour, as red brass, yellow brass, 
 white brass. 
 
 Brazed Joint. — A joint united by brazing (q.v.) as distinguished from a 
 soldered joint, a weld, or a riveted or screwed joint. 
 
 Brazing, — The union of metaUio surfaces by means of a film of an alloy 
 interposed. The joints to be brazed are cleaned, bound with wire, put 
 into a clear fire, sprinkled with borax, and heated until the alloy melts. 
 Also called hard soldering. 
 
 Brazing Metal. — An alloy composed of 98 parts of copper and 2 of tin, 
 
MECHANICAL ENGINEERING. 49 
 
 nsed for casting the flanges of copper steam pipes, and the facings of 
 sluice Talves which have to be cast to their iron casings. It is neces- 
 sary that the proportion of copper should be high, else the flanges 
 ■would melt at the temperature required for brazing. 
 
 Brazing Wire. — Soft brass wire of small gauge used for binding around 
 joints which have to be brazed. The joint being heated and sprinkled 
 with borax, the wire melts and runs in. 
 
 Break. — A brake (q.v.). 
 
 Breakdown. — A breakdown is said to happen when some portion of an 
 engine or machine fails or gives out, so that the mechanism depending 
 thereon is either partially or wholly brought to a standstill. Break- 
 downs frequently call into play the highest ingenuity and ready 
 resource of the workman or attendant. Breakdowns at sea are, from 
 the circumstances of the case, more troublesome than those on land, 
 and they are more especially so in the case of crank shafts, and 
 similarly massive portions, for which auxiliary (q.v.) and spare parts 
 (q.v.) cannot be taken. 
 
 Breakdown Crane. — ^A form of crane, especially constructed for railway 
 use, to be employed in clearing the line after accidents, hence called, 
 ** accident crane." It is made compact and strong, and cast iron is 
 employed as little as possible in its construction, in order to lessen the 
 risk of fracture by rapid transit and the shocks of shunting, &o. It is 
 necessarily a balance crane (q.v.), but the balance-box is made to slide 
 inwards, or to haul backwards as required, and the whole is mounted 
 upon tyred wheels, with springs, axle-boxes, bufiers and draw-bars, as 
 in ordinary rolling stock. 
 
 Breaking. — ^When molten iron is poured into a ladle, its surface shows a 
 multitude of continually varying curves, due to the rising up of the 
 metal from beneath. Different qualities of metal have different aspects 
 of striation, so that a founder can distinguish between hard and soft 
 iron while yet in the ladle, and can also roughly judge of its tempera- 
 ture. This striation is termed the breaking of the metal. 
 
 Breaking Down. — The sawing of logs of timber into planking. 
 
 Breaking-down Bolls. — Koughing-dowu rolls (q.v.). 
 
 Breaking Joint. — (1) Used in reference to the joints in metaUio piston 
 rings. The joints of the rings alternate one over the other to pre- 
 vent escape of the steam. Sometimes called cross joint. (2) The 
 separation of the joints of steam and water pipes, sockets, flanges, 
 cylinders, &e., for purposes of repair. (3) The placing of the longi- 
 tudinal seams of cylindrical riveted structures alternately in relation to 
 each other, in order that the plates shall afford each other mutual sup- 
 port. This practice is common in the barrels of steam boUers. 
 (4) Where a fagot or pUe is so built up that the layers of which it is 
 composed are not continuous over the whole width, but are made in 
 different widths, so that the joints overlap, they are said to break joint. 
 
 Breaking Pieces, or Spindles. — Short lengths of shafting used for coupling 
 up the engine with the bottom roUs of a forge train, or the rolls with 
 each other. The breaking pieces are made weaker than the necks of the 
 roUs in order that, in the event of overstrain, they will break and 
 60 prevent damage to the machinery, hence their name. They are 
 coupled to the journal ends, by means of wabblers (q.v.). 
 
 BreaMng Strength. — Corresponds with that amount or limit of stress at 
 which a structure or beam gives way, or is ruptured. 
 
 Breaking Weight. — ^The load necessary to break a beam or a structure 
 
so DICTIONARY OF TERMS USED IN 
 
 The actual breakmg -weight is a variable quantity even for the fiama 
 particular class of materials, depending partly upon the quaUty 
 selected, and also essentially upon the manner in which it is applied, 
 whether suddenly by impact (q.v.), or gradually, or as the last in a long 
 series of variable loads. See Dead Load, Fatigue of Materials, Live 
 Load, Variable Load. 
 
 Break Lathe. — A lathe of large size, whose bed is deepened in front of 
 the headstock to receive wheels and other work of large diameter, and 
 the length of whose gap or break is capable of variation by sliding the 
 bed along a base plate. 
 
 Breast Brace. — Any brace (q.v.) which is furnished with a knob in order 
 that the pressure on the drill or bit may be communicated thereto by 
 the breast of the workman. 
 
 Breast Hole. — The arched hole in front of and just above the base of a 
 foundry cupola, where the fire is lit, and through which the cinder and 
 slag are extracted after the casting work is over. It is closed by a 
 sheet-iron door or breast plate during the time that the blow is on. 
 
 Breast Plate. — (1) The plate of sheet iron which covers the breast hole of 
 a cupola. (2) A sheet of metal laid against the breast to receive the 
 thrust of the drill spindle used with the fiddle driU. 
 
 Breast Wheel. — A water-wheel in which the water meets the buckets 
 near the horizontal liae which passes through the axis of the wheel. 
 When the water fiows in at a point above the horizontal line, the 
 wheel is termed high breast, and when at a point below, low breast. 
 
 Breeches Pipe. — A bend pipe having two legs or branches running 
 either parallel with each other, or divergent. The branches unite into 
 one at their point of bifurcation. The casting which connects a single 
 inlet suction pipe with the two barrels of a lifting pump furnishes an 
 illustration of a breeches pipe. 
 
 Breeze. — Small or dust coke. Used sometimes for grinding into blacking 
 and facing for foundry use. 
 
 Brick. — Common clay bricks are used in foundries to form the framework 
 or backing upon which the loam is plastered in loam moulding. Curved 
 bricks specially made are used in the smaller cylindrical work. See 
 Bauxite Bricks, Dinas Brick, Fire-Brick, for those kinds which 
 are used for the linings of furnaces. Iron moulders use bricks made of 
 loam (see Loam Brick), in certain sections of their work. 
 
 Brick Arch. — An arch bmlt up of fiare-brick placed transversely across the 
 fire-box of a locomotive boiler, in front of the tubes, and sloping down- 
 wards and backwards towards the fire-bars, its purpose being to deflect 
 the flame and hot gases backwards and so prevent them from passing 
 into the tubes too rapidly. 
 
 Bricking Tip. — The building up of the outline of a loam mould with 
 course* or layers of bricks. See Brick, Loam Brick, Loam Mould. 
 
 Bridge. — (1) A structure by which a road or railway is carried over 
 a river. Bridges are sometimes made of cast iron, seldom of timber, 
 though both materials were largely employed formerly. Wrought 
 iron is the material now chiefly used. (2) An arched guide casting 
 attached to the cover of a lift pump or a force pump, and through 
 whose central boss the free end of the piston or plunger-rod travels. 
 (3) In a reverberatory furnace, the wall which divides the fuel chamber 
 from the hearth. (4) The barrier which stretches across the fire-box 
 of an engine boiler, at the farther end of the fire-grate. It is usually 
 built of brick laid upon a girder-like casting, or upon a bar of wrought 
 
MECHANICAL ENGINEERING. 51 
 
 iron. Its purpose ia to throw tte flame upwards to tlie heating sur- 
 face and to prevent too rapid escape of the heated gases. 
 
 Bridge Cylinder. — See Foundation Cylinder. 
 
 Bridge Plates. — A cheap quality of iron similar to ship plates. Its ten- 
 sile strength is low, ahout 18 tons, or even less, to the inch, and it is 
 brittle, having but 2 or 3 per cent, of ultimate set (<l.v.). 
 
 Bridge Eail. — See Mat Bottomed Kail. 
 
 Bridle. — (1) The loop which is forged on a slide-valve rod to embrace the 
 back of the valve. It maybe square or circular in plan. (2) Sometimes 
 applied to the strips in a steam chest between which the valve travels. 
 (3) A loop or clip used for holding test pieces in a testing machine. 
 
 Bridle Bod. — See Radius Hod. 
 
 Bright Nuts. — ^Nuts whose^ends and faces are polished for the sake of 
 appearance. All nuts exposed to view on machines, and on good indoor 
 work are bright. Their ends are turned in a centering machine, and 
 their facets are planed while strung on a bar in a planing machine, or 
 they are done with a milling cutter, or on a special machine. 
 
 Bright Eed Heat. — A stage of temperature in smith's work when the black 
 scales on the surface of iron are thrown into relief against the red back- 
 groxmd, and which corresponds roughly with a temperature of 1800° P. 
 
 Bright Work. — ^Denotes those portions of metallic surfaces which are 
 polished, either to diminish the friction of bearing parts, or for the sake 
 of appearance. The brightening is effected by machine cutters of 
 various kinds, or by files, emery-wheels, emery-papers, or powders. 
 
 Brine Pump. — A pump used for drawing oS a certain portion of the 
 water periodically from a marine boiler to prevent excessive saturation. 
 
 Brine Valve. — Sometimes applied to the blow-ofE valve of a marine boiler, 
 
 Brittleness. — In the materials of engineering this is usually a concomi- 
 tant of hardness. The hardest and most highly tempered steel is the 
 most brittle ; white iron is more brittle than grey, and chilled iron than 
 any other. But brittleness is also a sign of inferiority, as in wrought 
 iron and nuld steel. The brittleness of castings and malleable work is 
 reduced by annealing (q.v.). 
 
 Broach. — A boring tool, employed for the purpose both of enlarging 
 and imparting accuracy to tapered and parallel holes. Broaches are 
 made of various sectional forms, and their cutting angles range from 
 90° to 130'. Sometimes called rose reamers. See also Rose Bit. 
 
 Broaching. — ^The enlarging and smoothing, and truing of drilled holes 
 by means of a broach or reamer. Broaching is chiefly done in a 
 drilling machine or a lathe. 
 
 Broad Brush. — A draughtsman's colour brush, broad and thin, used for 
 tinting over large areas. 
 
 Broad Gauge. — Seven feet between rails, introduced by Brunei on the 
 Great Westem Railway. 
 
 Brob. — A spike driven alongside of a butt-jointed timber standing at 
 right angles with another timber. Brobs are driven into the longi- 
 tudinal piece to prevent the abutting timber from slipping sideways. 
 
 Broche. — A broach (q.v.). 
 
 Broken Glass. — Frequently thrown on the surface of molten brass whilo 
 yet in the crucible, in order to prevent oxidation from taking place. 
 
 Bronze.— See Gun Metal. 
 
 Broom. — A large oblong wire brush (q.v.) used for brushing the sand from 
 iron and steel castings. 
 
 Brown Hsematite, — A hydrated oxide of iron, embracing ores widely 
 
£2 DICTIONARY OF TERMS USED IN 
 
 difiering both in appearance and in quality. Tlisy receive different 
 specific names in different districts, but all agree in being composed 
 essentially of peroxide of iron. Fe^ O3, and water. 
 
 Bubble Tube, or Spirit Glass. — The tube of a spirit-level (q.v.) which con- 
 taias the enclosed spirit. 
 
 Bucket. — (1) Asooop-shaped vessel or grab (q.v.) used in dredging opera . 
 tions, and for the hauling of grain. (2) A mud bucket (q.v.). (3) Tho 
 piston of a lift pump. (See Pump Bucket.) (4) The outlets for water in 
 turbines. (5) The receptacles for the water in over-shot and breast 
 wheels. These were formerly made of wood, but iron is now employed. 
 Their section also is curved instead of being angular, as was the case 
 when wood was the material used. (6) Ordinary galvanized iron 
 buckets are used by moulders for damping and re -mixing sand which 
 has become dried and friable by being cast in. The intimate mixture 
 of the sand and water is effected by turning it about with the shovel. 
 
 Bucket Air Pump. — The ordinary form of marine engine air pump, pro- 
 vided with piston, foot and head valves. 
 
 Bucket and Plunger Pump. — A form of double-action pump in which a 
 bucket and plunger are combined on a single rod, the plunger being 
 uppermost. By its combined action half the contents of the barrel are 
 discharged during the up, and half during the down stroke. The 
 volume of liquid ejected at each stroke is equal to the displacement of 
 the plunger. 
 
 Bucket Valve. — The flap valve (q.v.) of the bucket of a Hft pump (q.v.). 
 
 Buckle. — The localised inequalities of a plate of wood or metal caused by 
 unequal and localised strains, and tensions. Moisture or dryness, or 
 want of homogeneity of grain, wfll produce buckling in timber. Un- 
 equal internal stress due to different densities, or qualities, or rates of 
 cooling, wOl cause buckle in metals. 
 
 Buckled. — See Crippling. 
 
 Buckled Plates. — Plates of cast or wrought iron having a curved or slightly 
 angular section if taken transversely in any direction, the rise of the 
 angle or curve being uppermost. The object of buckling is to 
 strengthen the plate by placing it in the condition of an arch, and so to 
 enable it to withstand the injurious effects due to the vibration of 
 moving loads. Buckled plates are used in bridge construction for 
 supporting the foot ways. 
 
 Buckling. — See Crippling. 
 
 Budding Spanner — A shifting spanner in which the movable jaw is 
 adjusted by means of a small skew rack and wheel on the back of the 
 lever handle. 
 
 Buff. — An appliance for polishing and finishing metallic surfaces. Usually 
 a cylindrical body, having a covering of emery. The emery is 
 cemented with glue or other composition, and the buff runs on a spindle. 
 
 Buffer, — An elastic spring by which the shock of contact between rail- 
 way waggons is deadened. 
 
 Buffer Bar. — See Buffer Beam. 
 
 Buffer Beam, or Buffer Bar, — A beam of timber or wrought iron which 
 carries the buffers in locomotives and rolling stock. 
 
 Buffer Box. — The casing which encloses the buffer spring and buffer rod. 
 
 Buffer Disc. — The spheroidal disc against which the contact of buffers 
 takes place. 
 
 Buffer Plunger. — A buffer rod (q.v.). 
 
 Buffer Eod. — The rod which carries the buffer digs. 
 
MECHANICAL ENGINEERING. 53 
 
 Buffer Spring. — A strong coiled steel spring enclosed in the buffer box. 
 wliicli resists and deadens the force due to the coUieion of buffers. 
 
 Buffing. — The process of polishing by means of leather and emery, or 
 other po"\vder. 
 
 Buff Wheel.— See Buff. 
 
 Building Up. — (1) Patterns are said to be built up when they are con- 
 structed by laying several courses of segments one above the other. 
 (2) "Works in -wrought iron and steel are built up by the piling (q.v. ) of 
 small bars, or "when numerous pieces are welded together, as dis- 
 tinguished from drawing down, upsetting, or otherwise manipulating 
 in a single piece. See App. 
 
 Built-TIp Pulleys. — See Wrought-Iron Pulleys. 
 
 Bulb Angles. — See Angle Iron. 
 
 Bulb Bars. — Rolled iron bars having a bulb, or bead on one edge. They 
 range from 6 in. by -fs in., with 7j lbs. weight per foot, to 12 in. by 
 -fa in., with 22 lbs. per foot. 
 
 Bulb Tees. — Rolled tee-iron having a bulb or bead on the centre web. They 
 range from 6 in. by 4 in., by 1% in., to 12 in. by &xk ™- hy J in. 
 
 Bulger Bam. — A round-ended ram employed in forcing metal plates into 
 apertures, in experiments on bulging stress (q.v.). 
 
 Bulging Stress. — The stress to which flat plates are subjected when 
 supported around their edges, and strained at the centre. Or the stress 
 of cylinders when subjected to internal pressxire. 
 
 Bull Dog. — The material used for the lining or fettling (q.v.) of puddling 
 furnaces. It is a mixture of oxide of iron, chiefly ferric oxide, though 
 ferrous is present in small quantity, with silicon and titanic acid. 
 
 Bullet Compasses, or Cone Compasses. — Compasses having a bullet at the 
 end of one leg for setting in a central hole from which a circle has to be 
 scribed. 
 
 Bullock Gear. — Mechanism for the utilisation of animal power in the 
 driving of well and other pumps, and for much light work besides of a 
 general character. It consists of the long poles to which the cattle are 
 attached, and which by their leverage drive a pair of bevel- wheels, and 
 through these the machinery connected thereto. Also termed, indis- 
 criminately, cattle gear, and horse gear. 
 
 Bunker. — The enclosed space which contains the furnace coal or coke for 
 the use of an engine boiler. Sometimes called coal bimk. 
 
 Bunker Plate, — A plate of sheet iron which encloses the area utilised for 
 the deposit of boiler fuel. 
 
 Burden. — The charge of a furnace. See Charge. Light Burden, Heavy 
 Burden denotes the excess of fuel or of ore respectively, 
 
 Burnett's Fluid. — A fluid used for the impregnation (q.v.) of timber. 
 It is composed of chloride of zinc diluted with water, and applied under 
 pressure. 
 
 Burning. — "Wrought iron becomes burned when it is allowed to remain in 
 the fire too long at a temperature equal to or greater than that of the 
 welding heat (q.v.). It can then barely be utilised by repeated reheat- 
 ings and hammerings, but is best discarded. 
 
 Burning On. — The process by which a broken-off or incomplete portion of 
 a casting is made good, or replaced. A sand mould of the portion 
 to be burned on is made and placed in proper juxtaposition to the old 
 casting in the bed of the foundry floor. The molten metal is then 
 poured in, but at the same time permitted to run away through a gate 
 or outlet at the side. By this device the molten metal is aUowed to 
 
54 DICTIONARY OF TERMS USED IN 
 
 flow for a certain time over tte broken face of the old casting until 
 that portion is in a state of local fusion, -when the outlet is stopped with 
 sand, and the flow of metal arrested. When cold, perfect amalgamation 
 will he found to have taken place. 
 
 Burnish. — (1) To poUsh a metallic surface by the friction of another 
 metallic surface thereon. (2) The envelopment of a body by the bend- 
 ing over of a metaUic ring around its edges. (3) Sometimes applied to 
 the process of buffing (q.v.). 
 
 Burnisher. — (1) A half-round file ground smooth, or a piece of steel of 
 similar section used to burnish metaUio surfaces with. (2) A blunt tool 
 by which pressure is imparted against sheet metals during the opera- 
 tion of spinning. 
 
 Burnishing. — See Spuming. 
 
 Burnt. — See Sand Burnt. 
 
 Burnt Casting. — See Sand Burnt. 
 
 Burnt Iron. — Cast iron which has been long subjected to the action of 
 heat is said to be burnt, and becomes rotten, and red in colour, owing to 
 the absorption of oxygen. 
 
 Burnt Steel. — Cast steel which has been overheated so that its nature as 
 steel has been abstracted, due probably to the absorption of carbon and 
 the formation of oxides. Burnt steel is considered valueless, but there 
 are methods sometimes adopted for improving it by bringing it into 
 contact with certain physics, or by reheating and hammering. But its 
 lost tenacity can never be fully restored, and it is scarcely worth the 
 wMle to attempt it, because the burnt end can be broken off and thrown 
 away, leaving the remaining portion good. 
 
 Burr. — (1) The tumed-over undetached line or edge of metal which 
 results when a metallic edge or surface is subjected to abrasion. 
 (2) The tumed-up edge of metal which commonly results from the 
 operation of punching or drilling, and cutting operations in general. 
 
 Burra Burra Copper. — Malachite (q.v.) obtained in Australia. 
 
 Bursting. — (1) The breaking asunder of a rapidly revolving pulley when 
 the stresses due to centrifugal force overcome the cohesive strength of 
 the material. (2) The bursting of a boiler or hydraulic cylinder is ,due 
 to the excess of internal pressure, as distinguished from that of col- 
 lapsing pressure (q.v.). 
 
 Bursting Pressure. —The pressure necessary to produce actual rupture in 
 a closed vessel, as a boiler or pipe. 
 
 Bush. — The internal cyUndrioal lining of a bearing. Usually of brass, 
 or gun metal, or some kind of antifriction metal. Bushes are used 
 either for purposes of economy, as when lining an inferior metal with 
 one more expensive, or for convenience, so that they may be replaced 
 when worn, without replacing the main casting. A bush is undivided, 
 while a brass is divided. 
 
 Bushing. — The fitting and driving in of bushes into their seatings. 
 
 Butt Coupling. — The ordinary form of box coupling used for connecting 
 shafting, the abutting ends of the shafts being enclosed by the box 
 keyed around them. See Box Coupling. 
 
 Butterfly Valve. — A pair of flap valves (q.v.) arranged back to back. 
 
 Butt Joint. — A smith's welded joint, made by the abutting together of 
 two pieces of metal. Butt joints are sometimes strengthened witli 
 doweUs or " stuck in " pieces. 
 
 Butt Measurement. — The measurement of a dimension by thrusting one 
 end of a rule against the portion whence the measurement is taken. 
 
MECHANICAL ENGINEERING. 55 
 
 The term is employed to distinguisli it from measurements taken ivitli 
 
 trammels, compasses, or dividers, or measurements set ofi by marking 
 
 from the rule divisions themselves. 
 Button. — The circular disc of metal pushed through a plate by punching. 
 Button-Headed Screws. — Small set or attachment screvrs whose heads 
 
 are hemispherical in outHne. They are driven in with a screw driver. 
 Button Sleekers. — Egg sleekers (q.v.). 
 Buttress Thread. — A screw thread whose section is triangular, but which 
 
 has one face at right angles with the axis of the screw, the second face 
 
 alone being sloped. These threads are only employed in cases where 
 
 they have to resist a force always acting in one direction. 
 Butt Riveted Joint. — See Butt Riveting. 
 Butt Eiveting. — When the edges of two plates are brought one against 
 
 the other, and are riveted into a covering plate or strip embracing 
 
 the two ; the term butt riveting is used to distinguish it from lap 
 
 riveting (q.v.). 
 Butt Strip. — The covering strip used for the coimeotion of the plates in 
 
 butt riveting (q.v.). 
 Butt-Welded Tubes. — Malleable iron tubes whose joints are simply 
 
 abutted in welding, as distinguished from lap-welded tubes. 
 Buzz Saw. — A term sometimes applied to a circular saw, derived from 
 
 the buzzing sound which it produces. 
 B. W. G. — Birmingham wire gauge. See "Wire Gauges. 
 
 c 
 
 Cab. — ^The hood or covering which arches over the footplate of a loco- 
 motive engine. 
 
 Cabinet Nest. — A palette (q.v.) containing several independent saucers, 
 circular in plan, and fitting closely one above another, to prevent drying 
 up of the ink or colour when not required for immediate use. 
 
 Cable-laid Eope. — A rope composed of three common ropes instead of 
 strands, laid or twisted from left to right, or in the reverse direction to 
 the strands in the several ropes composing it. 
 
 Cage. — See Lift. 
 
 Cage Valve.^A ball valve (q.v.). 
 
 Caisson.— A water-tight casing sunk into the bed of a stream and used in 
 the construction of the foundations of bridges and structures laid under 
 water, the work of excavation being carried on within it. 
 
 Caking Coal. — Coal which has the property of giving ofi abundance of 
 gas, and hardening subsequently. The caking coals are largely used in 
 smiths' fires, and for gas making. 
 
 Calamine. — The principal ore of zinc. It consists of the oxide in 
 combination with carbonic acid contaminated with oxide of iron. It 
 is found in Flintshire, the Mendip Hills, Alston Moor, and in many 
 parts of Europe. 
 
 Calcination, or Calcining, or Roasting. — The heating of metaUic ores in 
 order to expel some of the foreign and injurious ingredients^ingled 
 therewith, preparatory to their reduction to .the metallic condition. 
 The ores of irpn are roasted in Idlns, to drive off the carbonic acid and 
 water present. In the extraction of copper the roasting of the ores is 
 
S6 DICTIONARY OF TERMS USED IN 
 
 effected in a reverberatory furnace to expel arsenic and sulphur. The 
 arsenic combines with oxygen to form arsenious acid, the sulphur 
 yields sulphurous acid gas, or remains in small quantity in the ore aa 
 sulphate of copper. The calcination of tin ore is also effected in a 
 sirmlar furnace, and for the same object. 
 
 Calcining. — See Calcination. 
 
 Calcining Furnace.^The reverberatory furnace in which the calcination 
 (q.v.) of ores is carried on. 
 
 Calcium. — Symbol Ca. Comb, weight 39-9. Sp. gr. 1-58. One of the 
 metals of the alkaline earths, the metallic base of lime, CaO, and 
 carbonate and sulphate of lime, of the limestones, mortars, and con- 
 cretes. The metal calcium does not occur in the free state in nature, 
 being too readily oxidizable, but its yarious compounds are of immense 
 utility and interest to the engLneer. 
 
 Calender Boilers. — The heavy grooved rollers which feed the timber 
 along to the saws, or to the cutters, in frame saws, and planing 
 machines for wood. 
 
 California Pump. — See Barrow Pump. 
 
 Caliper. — An instrument used for measuring the diameter of circular 
 work, at sections intermediate from the ends, where rule measurement 
 is impracticable. Calipers are termed "outside" when they are 
 bellied for measuring outer diameters — "inside" when the legs are 
 straight and only bent round at the points to measure internal 
 diameters. See Combination Caliper. 
 
 Caliper Rule. — A short steel rule, a portion of which is attached to a well 
 fitting slide, both rule and slide being graduated into minute portions 
 of an inch. The slide is drawn out until an object such as a bar or 
 plate can be embraced between the opposing portions of the divided 
 rule, and the thickness read off directly from the dimensions on 
 the slide. 
 
 Calking. — Caulking (q.v). 
 
 Caloric. — A term used by the older writers on mechanics, which ex- 
 pressed a false and misleading theory. Caloric was applied to signify 
 the material principle of heat — heat being long believed to be a subtle 
 elastic fluid which permeated the molecules of all bodies. See Heat. 
 
 Caloric Engine. — See Hot Air Engine. 
 
 Calorie. — The French practical unit of heat. It is the quantity necessary 
 to raise one kilogramme of water 1° C, the temperature being taken 
 between 0° and 4" C. 
 
 Calorific Intensity. — The actual value of a fuel as a thermal agent. It 
 signifies the net available amount of heat given out by the combustion 
 of a definite quantity of fuel in a given time after the modifying 
 influences of the presence of moisture, the nature and action of the 
 chemical constituents of the fuel relatively to each other, the nature 
 and specific heats of the ultimate products of combustion, and the way 
 in which the fuel is burnt, are allowed for. These arithmetical calcula- 
 tions are so much affected by these modifying influences that the 
 calorific intensities of various fuels are ascertained instead by means of 
 direct experiment. 
 
 Calorific Power. — Signifies the amount of heat given out by a substance 
 during combustion, independently of its rate of combustion. 
 
 Calorimeter. — The sectional area of a boiler flue, given in square inches 
 is sometimes termed the calorimeter of the boiler. 
 
 Cam. — A plate or cylinder which transmits variable reciprocal motion to 
 
MECHANICAL ENGINEERING. 57 
 
 a piece of mechanism. Cams which are plates are provided either with 
 an edge of definite and special outline, Tolute, or heart-shaped for 
 example, or with an irregular definitely shaped groove on one face. 
 Cams which are cylinders have a groove cut on the periphery, which, 
 instead of being circular in one plane moves to the right or left as it 
 passes around. 
 
 Camber.— The amount of curve given to an arched bar or structure. It 
 is applied specifically to the leading and trailing springs of locomotives 
 and trucks. It is given in terms of the versed sine of the arc, and 
 usually with the load on. 
 
 Camel Hair. — Largely employed for manufacturing driving belts. 
 
 Campaign. — The life of a blast furnace lining, estimated by the number 
 of months or years during which it remains in blast. 
 
 Cam Shaft. — The shaft in a cam-worked punching and shearing machine, 
 which actuates the sUdes. Usually, however, in machines of modern 
 manufacture, an eccentric is employed instead of cams or wipers. 
 Similarly applied to any shaft which carries cams or wipers. 
 
 Candles. — See Puddlers' Caudles. 
 
 Cannon. — A hollow spindle or shaft which has a motion of its own, and 
 
 ' which also permits of the independent motion of a shaft through its 
 internal diameter. Its applications to machinery are numerous. Some- 
 times termed a quill. 
 
 Cantilever. — A beam fixed at one end and loaded at the other, or loaded 
 uniformly. Sometimes called a semi-beam. 
 
 Canting Fence. — See Fence. 
 
 Canting Motion, or Angle Motion. — The provision for placing the table 
 of a band, or the fence of a circular saw at an angle with the saw for 
 the purpose of cutting bevels. 
 
 Canvas Hose. — Hose piping (q.v.) made of woven canvas. It is not so 
 durable as the rubber hose (q.v.). 
 
 Canvas Packing. — Steam packing formed of canvas, with a core of 
 india rubber. 
 
 Cap. — The upper or loose portion of the bearing of a shaft. Made either 
 in iron or brass, and screwed in place with bolts or with studs. The 
 bore of the cap may be in actual contact with the shaft, or its function 
 may be simply that of confining the top half of a divided brass bearing 
 in place. 
 
 Capacity. — Another term for yield. Thus the capacity of a manufac- 
 turing firm will be, say, 200 or 300 tons per week, or perhaps given as 
 so many tons per furnace. 
 
 Capillarity. — The capillarity of fluids is taken advantage of for the 
 lubrication of bearings, the oil being fed into the bearings along a fila- 
 ment of cotton wick. The capillarity of any oil is therefore a recom- 
 mendation, if not obtained at a sacrifice of some other more important 
 property. 
 
 Capping. — The shrouding (q.v.) of gear wheels. 
 
 Capstan. — A cone-shaped drum used for hauling in ropes or chains. A 
 warping cone (qv.). 
 
 Capstan Lathe. — A lathe provided with a capstan tool rest (q.v.). 
 
 Capstan Tool Best. — A thick perforated disc or circular tool holder, 
 attached to the upper part of a lathe rest and used for carrying drilla 
 and tools of various kinds. The drills are set radially in the holes 
 around the periphery of the disc and fixed by set-screws put in from 
 the top. Any number of duplicate pieces of work can thus be operated 
 
S8 DICTIONARY OF TERMS USED IN 
 
 upon with diflferent sized tools, witli precisely similar results in each 
 case, by slewing round the capstan and bringing the desired tools 
 into aUgninent with the axis of the work centred in the lathe. Also 
 called from its shape, a turret or turret-rest. 
 
 Carbide of Iron. — White iron (q.T.). 
 
 Carbon.^Symbol C. Comb, weight, 11-97. A non-metaUio element, whoso 
 various combinations with iron chiefly produce the essential diilercuces 
 between the quahties of that metal. It is also the sohd element of com- 
 bustion. Carbon is aJlotropic. See Graphite, Combined Carbon, Char- 
 coal, Hydro -carbons, &c. 
 
 Carbonado, or Black Diamond. — ^An uncrystaUized variety of carbon 
 found in Brazil. It is as hard as the diamond, but free from its liability 
 to split. It is used for turning down and truing emery-wheels. 
 
 Carbonate of Copper. — See Malachite. 
 
 Carbonate of Lead. — Symbol Pb CO3. A compound of carbonic acid with 
 lead oxide, thus Pb -\- CO2. White lead is essentially a combination 
 of the carbonate with the hydroxide, thus 2Pb CO3 -j- Pb H2 O2. The 
 white lead of commerce is invaluable as the basis of oil paints. 
 
 Carbonate of Lime. — Symbol Ca CO3. The principal compound to whose 
 deposition the incrustation of steam boilers and water pipes is due. It 
 is in the first place held in solution in the water as a bicarbonate, the 
 excess of carbonic acid holding it in solution. This excess being driven 
 off by heat, the carbonate of 1ime remains as a iloury or muddy deposit, 
 its precise condition varying with the nature of the salts with which it 
 is usually accompanied. In the presence of heat it hardens and forma 
 an injurious scale. See Clark's Process, Soda, Washing-out, &c. 
 
 Carbonate of Hagnesia. — This carbonate is held in solution in some 
 feed-waters and on becoming deposited produces incrustation (q.v.). 
 It is usually present in smaller quantity than is the case with the 
 salts of lime. See also Dolomite. 
 
 Carbonates. — Salts formed by the union of carbonic acid with bases. The 
 carbonates always effervesce when brought into contact with acids, with 
 the evolution of COz- The carbonates of iron, lead, copper, magnesia, 
 and lime are those which chiefly concern the engineer. 
 
 Carbon Ceres. — Cores of sohd carbon prepared for foundry use, and 
 employed where heavy Kquid pressures have to be resisted. 
 
 Carbon Dioxide. — See Carbonic Acid. 
 
 Carbonic Acid, Carbon Dioxide, or Carbonic Anhydride. — Symbol COj. 
 Produced by the combustion of carbon in excess of air; hence it 
 plays an important part in combustion and in smelting operations. In 
 the presence of reducing agents it gives up one atom of its oxygen, 
 being thus reduced to the lower oxide CO. See Carbonic Oxide. 
 
 Carbonic Oxide. — Symbol CO. A gas produced by the combustion of 
 carbon in a limited supply of air. It owes its value to the metallurgist 
 to its power as a reducing agent, appropriating an atom of oxygen 
 from metallic ores, thus reducing them to the metaUio condition, itself 
 being converted into carbonic acid (q.v.). 
 
 Carbonization. — See Carburization. 
 
 Carburizaticn. — This refers to the quantity of carbon present in iron. 
 The limit of carburization for cast iron is about 4' 7 per cent. ; in the 
 best wrought iron not more than -01 ; while the many varieties of cast 
 iron and steel occupy positions intermediate with these. 
 
 Cards. — See Indicator Cards. 
 
 Card Wire. — A brush made of very fine steel wire, used in combing 
 
MECHANICAL ENGINEERING. 59 
 
 cotton wool. A strip of tMs when nailed to a piece of wood is used by- 
 fitters for cleaning the teeth of files which have become choked up with 
 particles of abraded metal. 
 
 Carnot's Principle. — This principle is, that the amount of work done by 
 a heat-engine is independent of the nature of the intermediary agent 
 employed, being dependent upon its temperature alone. 
 
 Carpentry. — Carpentry occupies a secondary position in most engineering 
 works, being confined chiefly to the framing together of heavy struc- 
 tures in wood ; to the making of packing-cases and the cutting out of 
 templets for boiler makers and erectors ; the making of blocks for the 
 iron turners and the general repairs about the factory. In raUway 
 works, however, the carpentry and joinery department is one of the 
 most important. 
 
 Carriage Hoist, or locomotive Hoist. — This consists of a set of shear legs 
 (q.v.), erected in repairing sheds for the purpose of lifting the trucks or 
 engines ofE their axles when repairs are necessary. The ends of the 
 shear legs are sunk in cast-iron shoes buried in the ground. 
 
 Carriage Ladle. — A foundry ladle mounted on a low carriage for conve- 
 nience of portability. 
 
 Carriage Traverser. — See Traverser. 
 
 Carrier. — ^A looped, or heart-shaped, iron or steel forging, or a steel cast- 
 ing, made to clip a piece of metal rod which has to be turned between 
 the dead centres of a lathe. It is tightened upon the rod by an adjust- 
 ing screw, and is itself driven by means of a short projecting pin affixed 
 either to a face or catch plate, or to the mandrel itself. See Driver. 
 
 Carrier Wheel. — An idle wheel (q.v.). 
 
 Cartridge Paper. — The commonest drawing-paper used in offices for rough 
 work. It is made in sheets measuring 30 in. by 22 in., and 40 in. by 
 27 in., and in continuous lengths of 54 in. wide. 
 
 Case Hardening. — A process by which a thin film of hardened steel is 
 formed on the surface of wrought iron. It is of especial value in cases 
 where a hard bearing surface is wanted without the expense of em- 
 ploying steel, or without the risk of the warping and curving which 
 steel almost invariably sufEers during hardening. Case hardening is 
 effected by heating the iron to a bright red in contact with substances 
 rich in carbon, or carbonaceous matters, and then quenching in cold 
 water. Small articles are heated while enclosed in iron boxes in con- 
 tact with leather clippings, horns, hoofs, bones, and other nitrogenous 
 matters, the depth to which the hardening penetrates being dependent 
 on the duration of the period of their exposure to a high temperature. 
 A surface filTn is often imparted by heating the iron, rubbing it over 
 with the yellow prussiate (ferrocyanide) of potash, placing it in the fire 
 for a few moments and then quenching in water. 
 
 Case Hardening Bos. — ^A box of cast iron, circular or square in shape, 
 provided with a cover and suitable handles for lifting. Articles to be 
 case hardened are placed in this, together with nitrogenous substances, 
 and the box put into a furnace for a definite period, lasting from a few 
 hours to several days, according to the depth of hardening required ; 
 the hardened sldn extending from the thickness of a mere film to 
 Tj^j in. or iV in. 
 
 Cast. — (1) The twisting, curving, and warping of timber. (2) The run- 
 ning of molten metal into moulds. 
 
 Cast Holes. — Holes are cast for several reasons. It is the custom to cast 
 all holes which have to receive black bolts, the holes being more cheaply 
 
6o DICTIONARY OF TERMS USED IN 
 
 cast, than drUled, and a close fit being non-essential. Cast holes are 
 made larger to the extent of from i^ in. to f in. than the bolts which 
 they are to receive. Holes are also cast to lessen the labour of driUing, 
 being cast smaU, and broached or rymered out afterwards. Large 
 lightening and clearing holes are always cast. Core prints usually in- 
 dicate the positions of cast holes on patterns. Cast holes are neces- 
 sarily rough, and their accuracy not quite reliable. 
 
 Casting. — (1) The art of making metal work by the pouring it, while in 
 the liquid condition, into moulds of sand, or metal, or plaster of 
 Paris. (2) The metal work which is produced by the pouring of the 
 same into its mould, in contradistinction to that which is forged, or 
 drawn out under the hammer. 
 
 Casting Ladle, — A foundry ladle (q.v.) More specifically the ladle which 
 receives the metal from a Bessemer converter, whence it ia poured into 
 the ingot moulds. 
 
 Casting On. — The process of uniting cast to wrought-iron work, by pour- 
 ing the former around the latter, while arranged in due position. Itia 
 chiefly resorted to in light ornamental work. See also Burning On. 
 
 Casting on End. — See Casting Upright. 
 
 Casting Pit. — A pit in which are arranged the moulds for the casting of 
 steel ingots. See also Pig Mould and Foundry Pit. 
 
 Casting Upright, or Casting on End. — This signifies the pouring of metal 
 into a foundry mould, the latter being set in a vertical position the while. 
 It is practised in the ease of long cylindrical work which is wanted of 
 special soundness, either for the purpose of withstanding heavy strains or 
 having to be turned or bored with a clean surface free from blowholes. 
 Work cast on end is sunk into the foundry pit (q.v.), a head (q.v.) ia 
 cast on, and the metal, though poured of necessity from the top, 
 is often led down a vertical ingate or runner to the bottom of 
 the mould, whence it rises upwards. This is preferable in certain 
 cases to pouring from the top, as less damaging to the mould, and 
 also producing a sounder casting, since the faUing metal would carry 
 down and enclose air-bubblea with it. 
 
 Ca.t-irou. — ytrictly speaking, a compound of iron and carbon ; in pure 
 iron, soft iron, or malleable iron the amount of carbon being nil. It ia 
 on the percentage of carbon present that the diiferent qualities of cast 
 iron mainly consist. The two extremes of quality in cast iron are the 
 grey and the white. The former contains sometimes as much as 4'7 per 
 cent, of carbon, mainly in the graphitic condition, the latter containing 
 2 or more per cent. , chiefly in chemical combination. Between these 
 extremes occur the various shades of grey and mottled, each suitable for 
 its specific purpose. The presence of graphitic carbon imparts fluidity 
 to the iron and renders it soft, so that it is readily turned and filed. 
 Cast-iron scrap is mixed with foundry pig to impart toughness or other 
 qualities as desired. Cast iron is affected by the presence of foreign 
 elements, as sUicon, sulphur, phosphorus, manganese, as noted under 
 those terms. See App. 
 
 Cast-iron Pipe. — Used for steam and water, and for fluids generally. Its 
 thickness is always excessive in amount, to allow of a sufiiciently large 
 margin of safety after it becomes weakened by corrosion. It is cast 
 around a core (q.v.), and flanges, sockets and spigots, as required, are 
 cast on. 
 
 Castor Oil. — An excellent lubricant for heavy bearings, having much 
 body or viscosity, bnt becoming dry or gummy after long exposure to 
 
MECHANICAL ENGINEERING. 61 
 
 the atmosphere. Its sp. gr. is ahout 960, taking water at 1,000, and 
 its flashing point 550° F. Cold-drawn oil is that expressed with- 
 out the aid of heat, and is the best ; in the preparation of the second 
 quality the heat of steam is employed. Castor oil is adulterated with 
 black poppy or other inferior oils, hut the adulteration may be 
 detected by mixing with absolute alcohol, in which the castor oil is 
 completely soluble, leaving the inferior admixture as a deposit. The 
 castor oil plant {Hicinus communis) belongs to the natural order 
 Huphorbiacece, and grows in the south of Europe and other warm 
 regions. 
 
 Cast Steel. — Blister steel (q.v. ) which has been broken into small pieces, 
 melted in a crucible, and poured into ingots. See App. 
 
 Cataract. — A vessel containing water, a plunger, and valves by which 
 the valves in the steam passages ia pumping engines are opened and 
 closed automatically. 
 
 Cataract Rod. — A vertical rod attached to the lever of a cataract and 
 which directly actuates the levers for the opening and closing of the 
 steam passages of pumping engines. 
 
 Catch. — See Hitch. 
 
 Catch Pawl. — See Dog. 
 
 Catch Plate. — ^A miniature face-plate which carries the driver (q.v.) of a 
 turning lathe. 
 
 Catch Water. — See Interceptor. 
 
 Catenary. — The curve assumed by a cord suspended freely from two 
 points. 
 
 Cattle Gear. — See Bullock Gear. 
 
 Caulking. — (1) Making a joint water or steam tight by fiUing it in with 
 rust cement (q.v.). (2) Burring or driving up the edges of boUer plates 
 along the riveted seams to make them steam and water tight. 
 
 Caulking Biug. — A caulking strip (q.v.) of circular form. 
 
 Caulking Strip. — A strip of sheet metal interposed between the body of 
 a wrought or oast-iron structure and a oast-iron piece attached thereto. 
 Its employment is rendered necessary by the impossibility of caulking 
 the cast iron itself. Caulking strips are used between boiler shells, 
 and the flanges of cast-iron man-hole, safety valve, and stop valve 
 
 Caulkiiig Tool. — ^A blunt-ended rectangular strip of steel used for closing 
 up the edges of boiler plates. It is driven against them by sharp 
 blows from a hammer. 
 
 Caustic Soda. — Symbol Na. HO. A hydrate of soda. It is used in solu- 
 tion for cleansing the outsides of condenser tubes from the accumula- 
 tions of grease and oil deposited thereon by the steam exhausted from 
 the cylinder. See Soda. 
 
 Cement. — Few cements are used in mechanical engineering. Under this 
 head may he classed the glue (q.v.) of the patternmaker, the black 
 wash (q.v.) of the moulder, the iron cement (q.v.) for hydrauhc work, 
 and the concrete (q.v.) of the hydraulic engineer, and cements for 
 leather and other materials. 
 
 Cementation. — (1) The process of making steel from malleable iron by heat- 
 ing the latter in contact with carbon in a furnace. Bars of malleable 
 iron are broken off and placed in layers in pots or troughs having inter- 
 mediate layers of charcoal powder sifted over and between them. The 
 surface is lastly covered over with wheel swarf (q.v.), and the whole 
 mass is heated together during several days, a. portion of the carbon 
 
62 DICTIONARY OF TERMS USED IN 
 
 being transferred to tte iron. The oliarooal powder ia called cement, 
 hence the derived name. The process is also termed the converting 
 process. This is the first stage in the manufacture of cast steel (q.v.) . 
 (2) Also applied to the manufacture of malleable cast-iron goods. 
 
 Cement Copper. — Copper extracted from the water which is pumped out 
 of copper mines. The water being pumped into tanks containing scrap 
 iron, the siilphate of copper in the water exchanges its sulphur with the 
 scrap iron, forming sulphate of iron, and copper deposited. It is there- 
 fore almost in a state of chemical purity. 
 
 Cement Tester. — A form of testing machine (q.v.) used especially for the 
 testing of the tensile and crushing strengths of cements, the specimen, 
 specially moulded for the purpose, being clipped by shacHes for tensile 
 stress, and a hydraulic machine being employed for crushing tests. 
 
 Center. — See Centre. 
 
 Centiare. — A Rrench measure of surface, comprising one square 
 metre (q.v.). 
 
 Centigrade. — See Thermometer. 
 
 Centigramme. — A French' measure of weight, being the one-hundredth 
 part of a gramme (q.v.), and equivalent to the -ISIS part of an 
 English grain. 
 
 Centilitre. — A French measure of capacity equal to the one-hundredth of 
 a litre (q.v.) and corresponding with •0176 of an English pint. 
 
 Centimetre. — A French measure of length, being the one-hundredth part 
 of a metre (q.v.), and the •3937 part of an English inch. 
 
 Central Forces. — A body revolving around its axis has a tendency to fly 
 off from the centre — this is its centrifugal force. The force which pre- 
 vents it from thus flying off is called the centripetal force. These are 
 central forces, and are, of course, equal and opposite. 
 
 Centre, sometimes spelt Center. — (l) That fixed point about which the 
 radius of a circle or of an arc of a circle moves. (2) A wheel centre 
 (q.v.). (3) See also specific heads following. 
 
 Centre-bit. — A boring bit for wood, comprising centre point, nicker and 
 cutter attached to a shank, the nicker and cutter revolving about the 
 centre point and being actuated by a brace. See App. 
 
 Centre Dab. — A centre pop. See Centre Punch. 
 
 Centre Gauge, or Screw Cutter's Gauge. — A thin metal gauge having 
 angular recesses cut in its edges, and used for a variety of purposes. Its 
 angles are 55°. Hence it becomes a templet for turning the cone points 
 of lathes, for grinding the angles of screw tools, for setting those tools 
 in the shde rest, and for determining the number of threads per inch of 
 a screw. 
 
 Centre Line. — A line scribed, or otherwise marked off, upon a piece of 
 work as a basis from which to obtain other dimensions, equally divided 
 or symmetrical on both sides. A centre Hne may, of course, be either 
 rectilinear or curved. Dimensions are almost invariably taken from 
 centre Unes, seldom from edges or outer faces. 
 
 Centre of Compression. — The hne where is located the resultant of the 
 compressive forces in the lower section of a beam. 
 
 Centre of Gravity.— The centre of gravity of a body is that point about 
 which it will be balanced though placed in any position, hence it is the 
 centre of parallel pressures. It may be determined experimentally by 
 suspending the body in different successive positions and hanging a 
 plumb line against the face. The common point of the numerous in- 
 tereeotions of the plumb line will correspond with the centre of gravity. 
 
MECHANICAL ENGINEERING. 63 
 
 In regular figures or soKda the centre of gravity corresponds with their 
 geometrical centre. The conunon centre of gravity of two bodies is in 
 a point which divides the distance between their individual centres of 
 gravity in the inverse ratio of their weights. The common centre of 
 gravity of more than two bodies combined in one system is found by 
 first obtaining the common centre of any two of them, and then obtain- 
 ing the common centre of those two with a third, and so on till all are 
 included. 
 
 Centre of Gyration. — That point in a revolving body in which its mo- 
 mentum is concentrated. 
 
 Centre of Homents. — That point in a rigid body about which the moments 
 or forces act, or the fulcrum. 
 
 Centre of Oscillation. — That point in the axis of a vibrating body in which , 
 if the whole matter were concentrated, the body would continue to 
 vibrate in the same tune. It lies in the same axis as the centre of 
 gravity, but is necessarily situate farther from the point of suspension. 
 
 Centre of Percussion. — That point in a body revolving about an axis at 
 which, if it struck an immovable obstacle, all its motion would be 
 destroyed. 
 
 Centre of Tension. — The line where is located the resultant of the tensUe 
 forces in the upper section of a beam. 
 
 Centre Flates. — Plates of wrought iron or of brass, which are used for 
 the purpose of temporarily securing jointed and dowelled patterns 
 while they are being turned between lathe centres. The plates are 
 usually screwed to both halves of the pattern at its ends, but some 
 small plates are held with clamp -like teeth only. 
 
 Centre Punch. — A steel punch about three or four inches long having one 
 end ground conical, and terminating at its apex in a sharp point. 
 It is used for indenting small circular ' ' pops ' ' or depressions upon 
 the ends and surfaces of metal work, as a guide for centring in the 
 lathe, as well as for drillers, machine hands, or fitters in cutting to out- 
 line. See Bell Centre Punch. 
 
 Centres. — (1) A term of wide appHcation in the workshop. Dimensions 
 are almost invariably given and taken from centres, and not from 
 edges. Centres are obtained by the intersections of Hnes, by compass 
 measurement, by scribing blocks, by trammels, and rules. (2) The centres 
 of lathes are the common axis of the headstock and poppet. The point 
 chucks or dead points are also called centres. (3) We constantly speak of 
 valve centres, trunnion centres, centres of motion, centres of shafting, of 
 connecting-rods, &c. The term has therefore an infinity of applications. 
 
 Centres of Motion. — The centres around which wheels or levers turn. 
 Centres of motion may be fixed centres (q.v.) or movable centres (q.v.) 
 
 Centre Square. — A tool used for finding the centre of a. circle, or of an 
 arc of a circle without compasses or geometry. It comprises a straight- 
 edge and two pins, or the pins may be absent, and their place be taken 
 by edges, the essential being that the straight-edge shall be normal to 
 the lines joining the pins, that is radial from the centre of a circle, whose 
 periphery would touch the pins or edges as the case may be. When 
 the pins are placed against the circumference of a circle, the radial 
 straight-edge points towards its centre. By sliding the pins to different 
 points around the circumference a sufficient number of intersections are 
 obtained by means of the straight-edge to determine the position of the 
 centre. 
 
 Centre -weighted GoTernor. — A high-speed governor, having » heavy 
 
64 DICTIONARY OF TERMS USED IN 
 
 weight sliding on the central spindle, -whose gravity has to he over* 
 come by the centrifugal force of the balls. It is sensitive, and a small 
 governor has the efficiency of a much larger governor of the common 
 type. 
 
 Centrifugal Force. — See Central Forces. 
 
 Centrifugal Pump. — A type of pump by which water or liquid is drawn 
 in, and delivered in a continuous stream by the rotation of a fan, or a 
 combination of radial vanes enclosed in a well-fitting casing. 
 
 Centring. — (1) A temporary structure of woodwork, upon which the 
 operations of bridge or arch building are carried on, and which is re- 
 moved on the completion of the work. (2) Marking off the centres 
 upon work which has to go into the lathe to be turned. 
 
 Centring Chuck. — A piece of mechanism for obtaining and punching the 
 exact centres on the ends of bars of circular and square section, which 
 have to be put between centres in the lathe. It consists of a self- 
 centring scroll chuck, to be held in a vice, fastened to a bench 
 or dropped over the end of the shaft ; when the shaft is centred it is 
 struck with a punch set in the centre of the chuck. 
 
 Centring Machine. — A machine in which iron bars are clipped by a self- 
 centring chuck or jaws, while cutters set on a revolving cone or 
 spindle face the ends and mark the centres. 
 
 Centring Eest. — A rest, whose outUne is that of the letter |_, used in con- 
 junction with a square centre (q.v.) for marking countersunk centres in 
 the ends of cylindrical rods. Being screwed on the slide rest it is made 
 to thrust the revolving bar into «. position truly concentric, while the 
 square centre cuts, or rymers its way into the end of the bar, central 
 with the outside. 
 
 Centripetal Force. — See Central Forces. 
 
 Chain. — Chain is made by the welding together of oval or circular loops. 
 Chains are either open link (q.v.) or stud link (q.v.). The sizes of chains 
 are given in terms of the diameter of the iron from which they are made ; 
 thus inch-chain signifies that the diameter of the bar from which the 
 link is made is one inch in diameter. The strength of a chain is esti- 
 mated by the area of the cross section, that is of two bars of the material 
 in the hnk. The length and width of a link always bears a definite 
 proportion to the diameter of its iron. Thus the length of an ordinary 
 short-link chain is 5^ times its diameter, and its width is 3^ times, the 
 proportions of links varying with their types. 
 
 Chain Barrel. — See Barrel. 
 
 Chain Feed. — A mode of feeding balks of timber along to frame saws by 
 means of an endless chain led around sheave wheels. 
 
 Chain Joint. — ^A riveted joint where the ends of two outer plates overlap 
 and embrace the ends of a central plate. 
 
 Chain Pump. — A lift pump consisting of a series of rectangular or circular 
 discs, connected at short intervals to a chain, and traveUing within a 
 closed pipe in the direction in which the water is to be lifted. The 
 plates travel at a rapid rate, and fit so closely to the pipe that little 
 waste takes place at the sides. 
 
 Chain Eiveting. — Hows of rivets placed in parallel lines, both in the 
 longitudinal and transverse directions. 
 
 Chair. — A cast-iron seating or support for metal raila. It is spiked down to 
 the sleeper, and the rail is wedged into it by wedges driven in sideways. 
 
 Chalk. — Essentially a carbonate of lime, Ca CO3, though usually contami- 
 nated with particles of eihoon, alumina, or magnesia. It is used much 
 
MECHAmCAL EMGlNEMRWa. 65 
 
 by engineers for •whitening rough or dark metallic surfaces to render 
 centre and dimension lines clearly -visible ; for trausf en'ing the mark from 
 a chalk hue (q.v.), for whitening one of two opposite surfaces when joint- 
 ing, for marMng the edges of straight-edges, and for numerous kindred 
 purposes. 
 
 Chalk Line. — A piece of fine twine wound upon a reel. It is used for 
 marking straight chalked lines upon timber. Being unwound and 
 whitened with chalk, and strained from each end of the board, the 
 central portion of the string is lifted, and allowed to rebound sharply 
 upon the timber, some portion of the chalk being thereby transferred 
 from the taut line to the board. 
 
 Chambered Core. — A core (q.v.) whose diameter is enlarged in its central 
 portion, either for the sake of lessening the weight of metal around it 
 or to save time in boring the hole, which is then bored only near the 
 ends. Or if the core is thin, and especially if it is both thin and square, 
 to obTiate the disadvantage of a probable bending of the core, and con- 
 sequent difficulty of fitting a bar through it, a chambered core is very 
 commonly employed. Also termed bellied or belly core, or roach beUy 
 core. 
 
 Chamfer. — A bevel imparted to edges otherwise rectangular. 
 
 Chamfering Machine. — A machine by which the bevels of nuts and the 
 rounding ends of bolts are formed. It is usually a centring machine 
 (q.v.) in which the various cutters are inserted as required. 
 
 Change Wheels. — Cog-wheels of fine pitch, whose function is the trans- 
 mission of motion from the mandrel of a lathe head to the guide screw, 
 for the cutting of screws of various pitches. The wheels are inter- 
 changeable, both on the mandrel, the guide screw, and the intermediate 
 stud ; hence their name. A combination of change wheels may consist 
 either of a single or of a compound train (q.v.). The pitch of change 
 wheels is not usually estimated in parts of an inch, but by numbers 
 ranging from 14 to 6, and called 14 pitch, 6 pitch. The former is equal 
 to iHr in. full, the latter to ^ in. full. (See Diametral Pitch.) A set of 
 change wheels consists of 22, commencing at 20 teeth, and rising by fives 
 to 120, and one 60 or 90 wheel extra, for cutting a screw of equal pitch 
 with the guide screw. But wheels go as low as 15 and rise to 150 or 
 200, and some of these are often added to lathes, over and above 
 the set so called. 
 
 Changing Hook. — A ram's horn hook used in foundries for changing or 
 transferring ladles of molten metal from one crane to another con- 
 tiguous thereto. 
 
 Channel Iron. — Rolled wrought iron bar, whose section is that of three 
 sides of a parallelogram [J, used in bridge and girder work, and for 
 structural purposes generally. 
 
 Chaplet, or Stud. — A metallic support, or stay, given to a core within a 
 mould, as an aid to, or altogether independently of prints. Chaplets are 
 used underneath cores to support them, or above, or at their sides, to 
 sustain upward or lateral pressure due to the head and flow of metal. 
 Chaplets are of various forms, noted under their specific headings. 
 
 Chaplet Block. — A pyramidal block of wood driven into the sand of a 
 mould to sustain the thrust of a chaplet nail (q.v.) . It afEords the 
 breadth of base necessary in the yielding sand. See Tinned NaU. 
 
 Chaplet Nail, or Moulders' Kail. — A nail having a broad flat head, used 
 as a chaplet (q.v.) for the lighter kinds of work. 
 
 Cbarcoal, — Wood which has been desiccated and carbonised, v/hUe 
 
 V 
 
6.6 DICTIONARY OF TERMS VS^t) W 
 
 heated to a temperature of about 650° F. in the absence of air, by 
 which process of dry distillation the volatile ingredients, water, wood 
 spirit, pyroligneoua acid, tar, and various gases are driven o£B. It is 
 employed sparingly in some smelting operations. Foundry moulds, 
 when small, are skin-dried (q.v.) by means of charcoal. It is used 
 also for charcoal blacking (q.v.). 
 
 Charcoal Blacking. — Blacking (q.v.) for moulders' use, made from oak 
 charcoal, as distinguished from coke blacking, coal dust, prepared 
 blackings, and plumbago. 
 
 Charcoal Furnace. — A blast furnace in which charcoal is the fuel em- 
 ployed. Its use is confined to Sweden. 
 
 Charcoal Iron. — Iron which has been smelted with wood charcoal as fuel. 
 It is the best iron, its superiority consisting in its freedom from sulphur, 
 which is never wholly absent from that smelted witli coal or coke. 
 
 Charcoal Plate. — Tin plate for which the sheet iron has been refined with 
 charcoal, as distinguished from coke plate (q.v.). It is superior in 
 quahty to the coke plate. 
 
 Charge. — (1) The gaseous or combustible mixture brought together in the 
 cylinder or explosion chamber of a gas engine. It usually consists of a 
 mixture of from nine to twelve parts of air to one of gas. (2) The mass 
 of material, ore, fuel, and fiux, or metal, fuel, and flux, which is intro- 
 duced into a blast furnace, or into a cupola at one time. Also called 
 the burden. 
 
 Chargeman. — A workman who has charge of a contract job, and who 
 allots to the men under him their separate portions of work, and 
 is responsible for the correctness of the work when done. AH large 
 jobs are let to chargemen, who, being competent men, are little inter- 
 fered with by the foreman. 
 
 Charging. — (1) The supplying of furnaces with their ores and fuels. 
 (2) The priming or fetching of a pump with water. 
 
 Charging Door. — (1 ) The door through which the charge is introduced into 
 a reverberatory furnace. The charging door is situated to one side of 
 the furnace. (2) The door of a blast furnace, or a cupola, situated near 
 the top, and level with the charging platform. 
 
 Charging Platform. — The platform from which the charge (q.v.) is de- 
 livered into a blast furnace or a cupola. 
 
 Charles, Law of. — May be expressed thus : That the volumes of gases 
 under constant pressure increase by equal fractional amounts, no matter 
 what the nature of the gases. Sometimes termed the law of Guy Lus- 
 sac, or the law of Dalton. 
 
 Chaser. — (1) Ordinary screwing dies are sometimes called chasers. (2) The 
 actual cutting dies or screwing tools, which are gripped and set by the 
 coUets (q.v.) in a screwing machine. (3) A comb-Hke tool of steel, whose 
 edge is a counterpart of a screw section. It is employed for strildng 
 or cutting screws by hand in a lathe, or for smoothing and finishing 
 them when already cut by other means. Chasers are internal or ex- 
 ternal, according as they are used for cutting inside or outside threads. 
 Chasing. — The act of cutting screw threads with a chaser, or of smooth- 
 ing and finishing threads which have already been cut by other means. 
 It is effected by pressing the chaser against the revolving metal, and 
 giving it a longitudinal travel at the same time, corresponding in amount 
 with the pitch of the screw. 
 Chatter. — Caused in machine work by want of rigidity in the cutting 
 
 , tools. It occurs chiefly in cutters set in a revolving' cutter bar, where 
 
MECHANICAL ENGINEERING. 67 
 
 the bar ia not sufficiently stifB, or where the cutters stand out to too 
 great a distance, or ia wide scraping tools. 
 Check. — (1) A check is a joint composed of two'portions, male and female, 
 fitting the one into the other, and so forming a guide or steady. A 
 dowel fitting loosely into a hole, a shallow stud or pin fitting into a 
 recess, are illustrations of checks. The mitre-wheels of the tool boxes 
 of planing machines are checked together ; so also are couplings, and 
 frequently flanges. Numerous illustrations of checking occur in ma- 
 chine work. Loam boards (q.v.) furnish an illustration of indirect 
 checking, the halves of the loam mould being checked, the boards there- 
 fore being cut in the reverse direction. (2) A round brass disc of about 
 the size of a half-crown, stamped with a definite number, and provided 
 with a hole for hanging upon a nail on a board called a check-board. 
 The number corresponds with the name of a workman. See Check 
 
 Checked In. — This term signifies the employment of a check in parts 
 fitted together. 
 
 Checking In. — The fitting together of corresponding parts or checks (q.v. ) . 
 
 Check Hut. — A lock nut (q.v). 
 
 Check Eail. — On railway curves of very quick radius it is sometimes the 
 practice to lay an extra rail on the inner side of the inner rail of the 
 curve, leaving just sufficient space for the flange of the wheel to pass 
 freely between. This relieves the pressure of the wheel flange against 
 the outer rail and prevents it from mounting the rail. Hence called a 
 check raO.. 
 
 Check System. — ^A system of keeping workmen's time, which is largely 
 used in the more important factories. Details differ, but the method 
 is essentially this. A board is hung just without the entrance gates, 
 upon which are hung a number of checks (q.v.) corresponding with the 
 number of workmen in the place. Each workman as he passes in takes 
 off his particular check and drops it into a box called the check-box, 
 which is a proof that he has gone in to work. The gate-keeper collects 
 the checks from the box, and by comparing their numbers with the 
 numbers in the book giving the names and numbers of the workmen, is 
 able to enter each man as in or out, as the case may be. He returns 
 the checks to the board in time for the next bell-ringing. 
 
 Check Valve. — A wing valve, inserted in a feed pipe between the boiler 
 and feed pump of an engine in order to prevent the return of the water 
 from the boiler to the pump. It is free to open towards the boiler for 
 the passage of water, but is closed by the boiler pressure. 
 
 Cheeks. — A term having a wide and varied apphcation in engineering. 
 In general it signifies the flanks or side supports for pieces of mechan- 
 ism. Thus it is applied to the bearers of a lathe, the standards of pumps 
 and engines, side frames (q.v.), the jaws of a vice, &e. 
 
 Cheese Head Eivet. — ^A rivet, the shape of whose head is that of a short 
 solid cylinder. 
 
 Cheese Head Screw. — A screw whose head is cylindrical in form, and 
 nicked or slotted across to receive a screw driver. It is used in the 
 lighter parts of machine work. 
 
 Chemical Change. — This denotes an interchange between the ultimate 
 atoms of the elementary bodies from which substances of whoUy different 
 characters are formed ; differing in this respect from mechanical mix- 
 tures, in which the arrangement of atoms remains the same. Heat is 
 the agent which usually produces or quickens chemical action. The 
 
38 DICTIONARY OP TERMS USED IN 
 
 reaotiona wMoli go on in the various melting furnaces are essentially 
 due to chemical changes, new bodies being formed from the elements 
 reduced from their original compounds. 
 
 Chec[ueriiig. — (1 ) The roughing over of footplates to prevent the foot from 
 slipping upon them. Diamond-shaped chequers are formed upon cast- 
 iron footplates, -while on those in wrought-iron crossing ridges are 
 stamped. (2) The brickwork in regenerative furnaces (q.v.) a>nd stoves, 
 through which the products of combustion pass. 
 
 Cliec[uer Plates. — Footplates of cast or wrought iron whose surfaces are 
 covered with chequering (q.v.). 
 
 Cherry Eed. — Bright Eed Heat (q.v.). 
 
 Cherry-wood (Cerasm). — A hard, reddish or brownish coloured wood, close 
 grained, and of small size, the logs averaging 10 or 12 inches in 
 diameter. If well seasoned it is suitable for cutting and turning small 
 patterns, and as such is used in country districts. Sp. gr. 'TIS. A cubic 
 foot weighs 45 lbs. 
 
 Cheval Vapeur, or Force de Cheval, or French Horse-Power. — The French 
 unit of work done by engines. It is equal to 75 kilogrammetres (q.v.) 
 per second, 4,500 kilogrammetres per minute, or 542'4825 English foot 
 pounds per second, or 32,549 foot pounds per minute. Expressed 
 decimally one cheval vapeur equals -9863 Enghsh horse-power. 
 
 Chili Copper. — Black oxide of copper obtained in Chih. 
 
 Chill. — The metaUic mould into which specially mixed molten iron is 
 run to produce a chilled casting. See Chilling. 
 
 Chilled Box. — A wheel boss whose central hole has been chilled against 
 an iron core. 
 
 Chilled Roller. — A roller chilled around its circumference. Employed 
 where durability and smooth hard surfaces are required, as in bending 
 and metal rolls of various kinds. See Chilling. 
 
 Chilled Wheels. — A wheel chilled around its periphery or "tread." 
 Employed for contractors' waggons running on raUs, for the trucks of 
 portable cranes, and similar work. In America they are used for 
 railway cars. 
 
 Chilling. — The hardening of the surfaces of iron castings by pouring cer- 
 tain mixtures of naetal (whose qualities and proportions are learned by 
 experience only) into cold metallic moulds. The graphitic carbon in 
 the metal is beheved to enter into chemical combination with the iron 
 at the surface, producing a steely skin. ChUhng will penetrate from 
 ^ in. to 1 in. inwards from the surface, contingent entirely upon the 
 character of the mixtures employed. Chilling insures great durabihty 
 of wearing surface. 
 
 Chimney. — The tube or funnel for the exit of waste steam or smoke from 
 an engine or boiler. It should bear a definite proportion to the fire- 
 grate area, the proportion varying with the type of engine. 
 
 CMnese Ink. — The finest quality of the ink which generally goes under 
 the name of Indian Ink. It is used for mechanical drawings. Chinese 
 ink dries glossy ; Indian ink dries dead black. 
 
 Chinese Windlass. — ^A contrivance by means of which a large weight may 
 be raised very slowly by a slight expenditure of power. Two drums, 
 or cylinders, differing but slightly in diameter, are contained on one 
 axis, and a single coil of rope is wound in opposite directions on each, 
 so that while it is winding on the larger cylinder it is being unwound 
 from the smaller, and vice versd. The nearer the diameters of the 
 barrels approximate to one another, the gi'eater the mechanical gain, 
 
MECHANICAL ENGINEERING. 69 
 
 with of course the necessary loss in time corresponding thereto. See 
 Differential Principle. 
 
 Chipping. — The removal of minute particles or chips of metal from 
 surface faces Qr from edges, both in cast and wrought iron, gun metal, 
 copper, &c. It is effected by means of a chipping chisel (ci..v.), and is 
 resorted to when the metal to be removed is too large in quantity to be 
 attacked Tvith the file alone. 
 
 Chipping Chisel, or Cold Chisel. — A tool used by fitters, boiler-makers, 
 smiths, and engineers generally. It is made from steel rod, ranges 
 from 4 in. to 10 in. or 12 in. in length, for different purposes ; its 
 cutting faces are ground to a double bevel to an angle of about 45°, 
 and highly tempered. It is used for cutting metal by the force of the 
 impact derived from the blows of a chipping hammer. 
 
 Chipping Face. — The face of a chipping strip (q.v.). 
 
 Chipping Hammer. — A fitter's hammer weighing about a pound, com- 
 monly used to deliver the blows upon the head of a chipping chisel. 
 
 Chipping Piece. — ^A chipping strip (q.v.). 
 
 Chipping Strips. — Narrow and thin metal strips cast around the edges or 
 across the face of those portions of castings where a good face bearing 
 is necessary, the casting having its bearing upon the faces of the strips 
 only. They are used to lessen the labour of fitting large metallic 
 surfaces. Called chipping strips because they are usually chipped over 
 with a chisel instead of being shaped in a machine. 
 
 Chisel. — The type of the cutting tools, whose essential principle is that of 
 the wedge. Specifically, — chipping, cross-cut, firmer, paring, mortice 
 chisels, described under their respective headings. 
 
 Chisel Eod. — Steel rod of a flat section with rounded edges, made 
 expressly for the forging of cold chisels. It is out off by the tool 
 smith and drawn down to the proper wedge shape. 
 
 Chloride of Mercury. — See Kyanising. 
 
 Chloride of Zinc. — See Salammoniao, Burnett's Muid. 
 
 Chops, or Chaps. — The jaws of a vice. 
 
 Chord. — The straight Ime which unites the ends of an arc of a circle. 
 
 Chord Fitch. — The pitch (q.v.) of a wheel measured along the chord of 
 the arc between the pitch points. Arc pitch (q.v.) is that usually 
 employed. 
 
 Chords, Line of. — One of the sectorial scales (see Sector) by means of 
 which angles are obtained and measured. It consists of two diagonal 
 lines, each divided into sixty equal parts and marked C. To obtain an 
 angle therefrom the sector is opened out until the distance between the 
 brass centres at the terminations of the lines corresponds with the 
 radius of the arc of the circle to be taken. Then, if under 60°, the 
 direct measurement for the chord is taken across or transversely to the 
 legs to those division numbers which correspond with the number of 
 degrees in the angle required If over 60^ two or more successive 
 measurements are necessary. 
 
 Chords, Scale of. — ^A scale of chords is obtained by striking an arc of 90°, 
 dividing it out into degrees, drawing chords from one extremity of the 
 arc to each division in succession, and transferring them to a straight 
 line. The 60° division in the scale wUl always be the radius by which 
 an arc is to be struck when it is desired to take ofi the length of any 
 particular chord from which to obtain an angle. 
 
 Chuck, — Any attachment through the medium of which work is secured 
 (X) the mandrel of the headstock of a lathe for the purpose of turning. 
 
70 DICTIONARY OF TERMS USED IN 
 
 The commonest forms are the fork, the bell or cup, the drill, self- 
 centring, and face chucks in their various modifications. They are 
 made to fit the mandrel by a female screw -which fits accurately to 
 that on the mandrel nose. There are, besides, the various compKcated 
 geometric and ornamental chucks ■which do not come "within the range 
 of the engineer's appliances. 
 
 Chucking. — The process or act of attaching lathe-work to the various 
 chucks. FacUe and correct chucking is an art which, though appa- 
 rently simple, is only to be attained by long practice, and the economy 
 of a metal turner's time is largely dependent upon his skill in this 
 respect. 
 
 Chucking Eeamer, or Straight Shank Eeamer. — A reamer whose shank is 
 circular and parallel, to be used in a self-centring chuck. 
 
 Chute. — An enclosed trough which conducts the water to a water-wheel. 
 
 Cinder Bed. — A coke bed (q.v.). 
 
 Cinder Frame. — Wire work sometimes placed in front of the tubes of loco- 
 motives for foreign use, to arrest tie passage of fragments of ignited 
 fuel. 
 
 Cinder Pig. — A very inferior class of pig iron, obtained by smelting slag 
 and cinder of puddling or reheating furnaces, together with propor- 
 tions of inferior ore. The slag is rich in oxide of iron, but contains 
 also a large proportion of phosphorus and silicon, which yields an 
 inferior product. 
 
 Cinematics. — See Kinematics. 
 
 Circle. — A plane figure described by a right Une moving around a fixed 
 point called the centre. 
 
 Circular Inch. — The area of a circle of one inch in diameter, as dis- 
 tinguished from a square inch. The pressures in steam cylinders are 
 frequently calculated in circular inches. To obtain the number of 
 circular inches in a given diameter it is only necessary to square the 
 diameter. 
 
 Circular Motion. — The circular motion of a shaping machine is that 
 arrangement of tool box parts and feed gear by which the outline of an 
 arc of a circle is imparted to the ends of lever rods and similar articles, 
 which cannot be shaped in a lathe. The circular motion is given by 
 means of an endless screw actuating a quadrant rack on the tool box. 
 
 Circular Nut. — ^A nut whose outline is circidar instead of hexagonal. 
 Circular nuts are provided with a round hole or holes for the insertion 
 of a tommy (q.v.), by which they are tightened up. 
 
 Circular Pillar Drilling Machine. — A drilling machine in which the table 
 embraces and swings around a circular pillar which carries the gear. A 
 toothed rack is hoEowed at the back to fit the pillar, and is itself 
 embraced by the table. Into whatever position the table is slewed the 
 rack is also carried round, so that the pinion which gears with it, and 
 which has its bearings in the table, is always in gear, and always 
 therefore in a position for lifting the table. A worm and worm-wheel 
 actuate the pinion spindle. 
 
 Circular Pitch, or Circumferential Pitch.— The ordinary method of 
 estimating the pitch of toothed wheels by dividing the circumference 
 at the pitch line by the number of teeth in the wheel. The term, is 
 used in opposition to diametral pitch (q.v.). 
 
 Circular Plane, or Compass Plane. — ^A plane used for working out hollow 
 sweeps whose curves run in the direction of the length of the plane. It 
 is either made of wood, with its face' rounded longitudinally and pro- 
 
MECHANICAL ENGINEERING. 71 
 
 vjded ■with a front adjustable stop to alter tlie curve within narroTV 
 limits, or it is an iron plane whose face is an elastic strip of steel, the 
 amount of whose curve is regulated by a screw and iaterlocldng levers. 
 In this last form the curve can be made external or internal at pleasure. 
 
 Circular Saw, sometimes called Buzz Saw. — A saw whose teeth are divided 
 around the edge of a circular disc running upon a central spindle. 
 These saws vary from a few inches in diameter to 7 feet. They are 
 used chiefly for the rougher kinds of sawing. Circular saws are also 
 used for cuttiag off iron, both cold and red hot. Then they are as 
 much as f or J in. in thickness, their teeth are short and square across, 
 and their lower portions run in water for cold sawing. 
 
 Circular Table. — A circular cast-iron plate, which sustains the work which 
 is being operated upon in drilling and slotting machines. 
 
 Circular Valve. — A valve circular in plan, as distinguished from a slide 
 valve. 
 
 Circulating Fump. — ^The pump which circulates water through the tubes 
 in the surface condensers of marine and other condensing engines. The 
 cold water is drawn through the tubes by the suction of the pump. The 
 pump is worked from the engine itself, or from a separate engine. Some- 
 times a centrifugal pump is used for circulating. 
 
 Circulating Tubes. — The inside smaller tube in Field's tubes (q.v.), or 
 the cross tubes (q..v.) of vertical boilers, or G-alloway tubes (q,.v.), or the 
 ordinary forms used in multitubular boilers or in surface condensers. 
 
 Circulation. — The circulation in a steam boiler is due to the bubbhng 
 up of the lighter boiling water from the heating surfaces through the 
 cooler water at the upper portions, which latter then descends to take 
 its place. The efficient circulation of the water is necessary to the rapid 
 generation of steam and the prevention of deposit and incrustation 
 (q.v.). It is promoted by the introduction of water tubes, so arranged 
 that convection shall readily take place from then- surfaces, and by 
 keeping as small a quantity of water as possible below the heating sur- 
 faces. The circulation of water in a condenser is necessary for the 
 rapid condensation of the exhaust steam, and is effected by iie circu- 
 lating pump (q.v.). See also Hot-water Apparatus, Surface Condensa- 
 tion, Jacketing. 
 
 Circumference. — The circumference of a circle is the line described by the 
 radius (q.v.) moving about the centre. 
 
 Circumferential Pitch. — (1) This pitch is, in a screw wheel, the distance 
 between the points in which a plane at right angles with the axis cuts 
 two contiguous threads. (2) Circular Pitch (q.v.). 
 
 Clack. — That portion of a pump-valve or bucket which is lifted by the 
 action of the water or air. It is made of leather stiffened with plates 
 of brass or iron. Applied more specially to a flap-valve (q. v.). 
 
 Clack Box. — The box or chamber in which the clack (q.v.) of a pump 
 works, or that portion which contains the valves that open and close to 
 suction and delivery. 
 
 Clam. — See Vice Clamps. 
 
 Clam Nut. — ^A clasp nut (q.v.). 
 
 Clamp. — Clamps are tools used for holding portions of work together, both 
 in wood and metal. 
 
 Clamping Screw. — ^Any screw by which a piece of work or a tool is 
 pinched or held in place. The screws wHch confine the cutting tool 
 in the binding straps of planing and shaping machine tool boxes ara 
 illustrations oi clamping screvs. 
 
72 DICTIONARY OF TERMS USED IN 
 
 Clark's Process. — A process wHoh has teen adopted to a limited extent 
 for the purification of the hard feed-waters of steam boilers from the 
 lime held in solution. It depends for its efficacy on the action of lime 
 on carhonic acid, -with which it readily combines. In water which oon- 
 taius bicarbonate of lime in solution, the lime is held in solution by 
 the carbonic acid present, which being driven off by boiling deposits 
 the lime on the boiler plates. But if lime be added to the water in 
 sufficient quantity it will combine readily with the carbonic acid, neu- 
 tralizing it, and will be precipitated as carbonate, together with tlie 
 carbonate disengaged by its action. In the carrying out of this process 
 tanks have to be provided for the filtration of the purified water. 
 
 Clasp Nail. — A malleable iron naU, rectangular in section, whose head is 
 formed by two opposite projections pointing downwards. XTsed by 
 pattern-makers for the temporary holding down of segments when 
 bmlding up work, the toughness of the wrought iron permitting of 
 their extraction after the glued joints have set. 
 
 Clasp Nut. — The movable nut by which the sHde-rest of a screw-cutting 
 lathe is put into connection with, or released from the leading screw. 
 It is worked by n. cam plate when double ; by an eccentric pin when 
 single. Sometimes termed clam nut and clip nut. 
 
 Claw Coupling. — A loose coupling (q.v.) used in cases where shafts require 
 instant connection or disconnection. It is somewhat similar in outline 
 to a flange coupling (q.v.), but instead of being plain, projections or 
 claws are cast upon each face, which engage in corresponding recesses 
 in the faces opposite. The claws usually number two or three. The 
 coupling is thrust in and out of gear through a pin or a fork taking 
 easily into a groove turned in the circumference of a bossed up hinder 
 portion. It is often termed a claw clutch. 
 
 Claw Nut. — The clasp nut (q.v.) of a lathe. 
 
 Claw Wrench. — A wrench having a loose jaw, pivoted in such a manner 
 that its bite increases with the pressure put upon it. Its principle is 
 that of the pipe wrench (q.v.), and it is used both as a spanner and 
 also for pulling the core rods and wires out of castings in the task of 
 fettling (q.v.). 
 
 Clay. — Essentially a silicate of aluminium resulting from the decom- 
 position of felspar. Used for making bricks, clay wash, and clay 
 water, for the linings of furnaces and ladles, for stopping tap holes, 
 and making crucibles, its value consisting in its plasticity, its quality 
 of hardening, and its refractory nature. 
 
 Clay Band. — A carbonate of iron mixed with clay. It is mined in 
 Staffordshire, Yorkshire, Derbyshire, and South Wales. Its com- 
 position is variable. It is the chief ore of iron worked in England. 
 Called also argillaceous iron ore, and clay iron-stone. 
 
 Clay Iron-stone. — See Clay Band. 
 
 Clay Pit, — A pit from which the clay used in foundry operations is dug. 
 
 Clay Plug.— See Plug. 
 
 Clay Wash, or Clay Water. — A solution of clay in water. Used in 
 foundry work for painting over the bars and lifters of moulding boxes, 
 to cause the adhesion of the sand thereto ; and for cores. 
 
 Clay Water. — See Clay Wash. 
 
 Cleading, — The covering put around a boiler or engine cylinder for the 
 purpose of preventing the radiation of its heat into the surrounding 
 atmosphere. The cleading consists of wood strips tongued together 
 with hoop iron, and bonded with hoop iron or br^sa. Often thin sheet 
 
MECHANICAL ENGINEERING. 73 
 
 iron is substituted for tlie wood cleading'. There is a space between 
 the boiler or cylinder and the cleading, filled with felt, or similar good 
 non-conductiag material. See Lagging. 
 
 Clean Boiler. — A steam boiler free from incrustation, scale, or muddy 
 deposits. 
 
 Clean Casting. — A casting having a clean sHn (q.v.). To produce a 
 clean casting, the mould must be properly vented, sand suitable for the 
 nature of the casting must be used, and the surface sleeked over with 
 plumbago. 
 
 Clean Cut. — A cutting tool is said to produce a clean cut when the cut 
 surface is not grooved, or wavy, or ridged, but continuous and smooth. 
 The cleanness of a cut depends on the proper cutting angle being main- 
 tained, on the degree of force applied to the tool, too much pressure 
 causing rough cutting ; and partly on the nature and homogeneity of 
 the material itself. 
 
 Cleaner. — A moulder's tool of steel or brass, used for smoothing and 
 dressing the various irregularly shaped portions of sand moulds. The 
 typical cleaner is a thin long flat tool, its blade running in a longi- 
 tudinal direction, while a short end is turned up at right angles thereto. 
 The latter is used as a lifter. The term cleaner is applied to tools of 
 various shapes. 
 
 Clean Fire. — A boiler fire free from clinkers and ashes. 
 
 Clean Hole. — A hole which is drilled or bored without showing a wavy 
 or ridged outline. Clean drilling is effected by having a drill properly 
 ground, and by cutting at a definite speed, and at a moderate rate of 
 feed only. Cleanness of surface is increased by broaching or rymering, 
 or by lapping. 
 
 Cleaning. — Engines and machines are cleaned by rubbing over their 
 bright portions with sponge cloths (q.v.) or waste (q.v.), and oil. 
 
 Cleaning Up. — Smoothing over the surface of a foundiy mould with 
 trowel and cleaners, and blackening in readiness for closing and casting. 
 
 Glean Lift. — When a pattern is withdrawn or lifted from a foundiy 
 mould, the lift is said to be clean when the edges and sides are not torn 
 away, or are torn away to a very slight extent only. The cleaner the 
 lift, the less the amount of mending up necessary. 
 
 Clean ISetal. — Applied to metals in general to indicate the absence of 
 scoriEe, scurf, scale, oxide and similar foreign matters which detract 
 from their value as metals. 
 
 Clean Mould. — A foundry mould which is properly sleeked and blackened, 
 and from which all loose particles of sand are removed, in readiness for 
 closing and casting. 
 
 Clean Scrap. — Forged scrap, from which all traces of cinder have been 
 removed by hammering. 
 
 Clean Skin. — A casting or forging is said to have a clean skin when its 
 exterior surface is free from scabs, pits, blisters, or other excrescences 
 or depressions. 
 
 Clean Thread. — The thread of a screw is said to be clean when it is 
 smooth and sharp, instead of being ragged, imperfect, and coarsely cut. 
 
 Clean Water. — The feed water of boilers is said to be clean when it is 
 free from mud and other visible sedimentary matters. Clean water may 
 nevertheless be hard, and produce scale, though not muddy deposit. 
 
 Clearance. — A term in frequent use, meaning generally the amount of 
 space, open or free, between contiguous parts. Thus clearance of 
 wheels means tte space between contiguous teeth, clearance of brasses 
 
74 DICTIONARY OF TERMS USED IN 
 
 the space between their shoulders or flanges and the collars upon their 
 shafts. Clearance of steam means freedom to exhaust. The differ- 
 ence between the distance across the flanges or throats of railway 
 wheels and the gauge of the rails, is also termed clearance. Tliis is 
 equal to f in. or 1 in., and is necessary to allow of end play in running 
 round curves, and also for inaccuracy in the rails. 
 
 Clearance Angle. — The angle of relief (q.v.). 
 
 Clearing Hole. — The term is used ia opposition to tapping hole (q.v.). It 
 signifies a hole full to the specified size, so that a turned stud or bolt 
 of the same nominal diameter will pass freely yet closely through it. 
 
 Clear Oils, or Pale Oils. — Lubricating oils which have been subjected to 
 filtration and purification to free them from their dark natural colour. 
 See Black Oils. 
 
 Cleet. — A block of wood which furnishes a steady point of attachment for 
 a part of a structure, as a batten. 
 
 Cleft. — ^A shake in a balk of timber which is radial or running along the 
 course' of the medullary rays. 
 
 Clenching, or Clinching. — The turning and hammering over of the points 
 of naDs against a wood face to secure their adhesion under rough 
 usage. The clenching transforms the naUs into rude clamps. 
 
 Click. — The detent or catch of a small ratchet wheel. When of large 
 size it is termed a paul (q.v.). 
 
 Click Wheel, — ^A small ratchet wheel (q.v.). 
 
 Clinching. — See Clenching. 
 
 Clinker. — The slag, or vitrified material which accumulates from the fuel 
 in a smith's or a boiler fire. 
 
 Clinkering. — The periodical removal of the clinkers from a smith's or 
 from a boUer fire. 
 
 Clips. — (1) Slight castings provided with side flanges or ears placed on 
 opposite sides to each pther. The clips are curved between the ears to 
 embrace the outside of a hose pipe, and are used to effect a rapid 
 imion between the hose and the metal nozzles. The flanges are cast in ■ 
 brass, and clasped together with screw bolts . (2) Thin, flat, rectangular, 
 washer-like castings, or more generally castings having one end 
 rounded, and recessed slightly on their front, or straight edges, to 
 clip, or cover the edge of the flat bottom flange of a rail. A fang bolt 
 or a spike passes through a hole iu the clip, enabling the latter to retain 
 the raU in place. 
 
 Clip Drum. — See Clip Pulley. 
 
 Clip Nut.— See Clasp Nut. 
 
 Clip Pulley, or Clip Drum. — A rope pulley whose rim, of a vee-section, is 
 constructed of movable clips instead of rigid sides. The clips are three 
 or four inches long, and are hinged on pins whose axes are ranged in 
 the direction of the periphery of the puUey. The positions of the pins 
 are such that when a rope bites between the clips the effect is to pull 
 them towards each other with the result of increasing the bite of the 
 rope, the amount of which bite is, therefore, in direct proportion to the 
 pull of the rope. Clip pulleys are used for hauhng at steam ploughing 
 implements, for mines and inclined planes, and for the transmission of 
 power through long distances, especially in those cases where winding 
 drums are not convenient. 
 
 Clogging. — The thickening of lubricating oils due to the absorption of 
 oxygen, and to the presence of dust. Machinery is said to clog when 
 its lubricating oil becomes thick and dry. 
 
MECHANICAL ENGINEERING. 75 
 
 Closed Stokehold. — The stokehold of a steamer -which is closed to all ad- 
 mission of air, save that -which is supplied through blo-wing fans. The 
 advantages claimed for closed stokeholds are increased efficiency of 
 boilers, due to the more rapid combustion obtainable, permitting of a 
 diminution in their bulk, and the exact adjustment and regulation of 
 the air supply under calm, -weather and in any direction of the -wind. 
 
 Close Grained. — Iron is close grained -when its crystals are of moderate 
 size and densely packed . The term is, however, relative, since all hea-vy 
 castings -which are not cast under pressure are some-what open and 
 porous in their central portions. It is customary in specifications to 
 stipulate for close-grained iron for special classes of -work, as, for ex- 
 ample, engine cylmders and bright -working parts. Timber is close 
 grained when of slow gro-wth, as e-ridenced by the small size of the 
 annual rings. 
 
 Close Link Chain.— Ordinary open link chain, the length of whose links 
 does not exceed five times the diameter of the iron from which it is 
 made. Its width is three and a-half diameters. Called close link to 
 distinguish it from circular linlr chain. 
 
 Close Mouth. — Applied to punching bears and"punching machines which 
 are open back and front for the passage of bars, but closed at the sides. 
 Used for rails and bars. The term is used in opposition to open 
 mouth (q.v.). 
 
 Close Topped Furnace. — ^The modem form of blast furnace in which the 
 mouth is closed by a cup or cone or some other suitable arrangement, 
 the waste gases being led do-wn to heat the blast. 
 
 Closing Hammer. — A hammer used for closing the seams of boiler plates. 
 
 Closing Tip. — (1) The riveting or burring over of a rivet head, either by hand 
 or by hydraulic pressure. The length of rivet required for closing up 
 in hand riveting is IJ times the diameter, for snap head and conical 
 rivets ; once the diameter for countersunk rivets, and a trifle more than 
 these, an J in. or J in. in machine riveting. (2) Covering up or 
 placing on of the top box or cope of a found^ mould in readiness for 
 casting. 
 
 Clothing. — The felting and wood coverings placed around steam pipes and 
 boilers to prevent radiation and loss of heat therefrom. See Cleading. 
 
 Clout Nail. — ^A strong malleable iron nail, having a large flat head. 
 Used for fastening leather on wood. These nails are also often 
 employed, after cutting off their heads -with a cold chisel, as pins for 
 securing the cogs of mortice wheels in place. 
 
 Clutch. — The medium by which a temporary connection is made between 
 separate spindles or portions of shafting. It may be a claw clutch, 
 having claws, two or more in number, which take into corresponding 
 recesses in the opposite haK, or it may be some form of smooth friction 
 clutch (q.v.). Also termed disengaging coupling. 
 
 Clyburn Spanner. — An adjustable spanner, one of whose jaws receives 
 movement by means of a screw and milled head. 
 
 Coach Scre-w. — A wood screw -with a coarse vee-thread and a square head, 
 used generally for bolting timber work together. 
 
 Coal. — ^Used in smelting operations, for engine fires, in the manufacture 
 of coke, for mixing -with foundry sands, and for foundry blacking. Coals 
 are authracitic or bituminous, caking or non-caking. 
 
 Coal Box. — (1) The box or bunier which carries the coal in a locomotive 
 which is not provided -with a tender. (2) The trough or receptacle for 
 the ooal used in the smith's fire. 
 
76 DICTIONARY OF TERMS USED IN 
 
 Coal Bunk. — Sf 3 Bunker. 
 
 Coal Dust. — (1) Ordinary coal pulverized in a blacking mill. It is used 
 for admixture with foundry sand to the extent of 8 or 10 per cent. 
 When the coal hecomes oxidized the sand is said to be burnt. (2) Used 
 also for facing moulds, both as a dust and in the form of black wash 
 (q.T.). 
 
 Coal Mill.— See Blacking- Mm. 
 
 Coarse Feed. — The feed of a machine tool set for heavy cutting. The 
 term is relative, but in ordinary light work anything over -jV would be 
 coarse feed. In massive work | in. or 1 in. feed is common. 
 
 Coarse Fibre.— The fibre of wrought metal which is large and rough, 
 indicating a low tensile strength. 
 
 Coarse Grain. — The crystallization of metal when the crystals are of large 
 size. 
 
 Coarse Grit. — Tlie texture of an emery-wheel or grindstone which is 
 suitable for uugh grinding only. 
 
 Coarse Hard. — A class of emery-wheel used for edge-griuding, for trim- 
 ming castings, and in general for rough work. 
 
 Coarse Metal. — See Copper Matt. 
 
 Coarse Pitch. — The pitch or size of wheel teeth considered in relation to 
 other teeth. 
 
 Coble Ores. — Eed copper ores (q.v.) imported from Cuba. 
 
 Cock. — A cylindrical valve, consisting essentially of a shell, plug, and 
 cover. A passage-way is formed through the plug, which being 
 brought opposite to the entrance and discharge openings, allows the 
 fluid to pas.! through. When the plug-openings are brought opposite 
 the blank w'Hs of the shell, the cock is closed. Cocks are of various 
 kinds, as bib, ilanged, gland, socket, two-way, three-way, foui-way, 
 described in their sections. Sometimes the term cock is extended to 
 include any valve which is opened or closed by hand. 
 
 Cock Metal. — Sometimes used to designate the metal used in the very 
 commonest brasswort, as the cheaper class of cocks and valves. 
 
 Cock-wheel. — See Idle-wheel. 
 
 Coefficients. — (1) Numerical values deduced from experiments, and used in 
 engineering formulae and calculations. Hence there are coefiicients for 
 friction, for elasticity, for tension, for the flow of water, &c. Thus, for 
 example, the weight necessary to elongate an elastic bar of any material 
 and of uniform section to double its length is called the coefficient of 
 elasticity for that material. (2) Any factor or factors of an algebraical 
 product regarded in relation to the other factors. If a figure, it is 
 called the numerical coefficient. 
 
 Cog. — The tooth of a gear-wheel. More properly used to distinguish the 
 wooden teeth of mortice-wheels from those of iron. 
 
 Cogged Bloom. — A bloom or crude mass of steel which has been passed 
 through the cogging mill in readiness for roUing into raOa or other 
 sections. 
 
 Cogging. — (1) The fitting in and working of the cogs of mortice- wheels. 
 (2) The rolling of steel blooms from ingots. 
 
 Cogging Engine. — An ordinary rail-mill engine used for driving tha 
 cogging mill. 
 
 Cogging Mill. — A rolling mill in which steel blooms are roUed out. It is 
 similar to a blooming mill. 
 
 Cogwheel. — A toothed wheel. Sometimes used to disting^uish a mortiog« 
 wbeel (q.v.) from a wheel whose teeth are of iron, 
 
MECHANICAL EMGIlsrEEkmQ. ;7 
 
 Cohesive Strength. — Tlie strength of a material resisting forces tending 
 to rupture it by tension. 
 
 Coiled Spring. — A spiral spring (q. v.). 
 
 Coils. — Coils of iron piping conveying steam are used for the heating of 
 ■workshops. The pipes are often provided with rings or collars, large 
 and thin, for the better radiation of the heat. 
 
 Coke. — The solid residuum produced by the destructive distillation of 
 coal. It is either a residual product of gas -making, then called gas 
 coke, or the chief product, and termed oven coke or hard coke. The 
 making of oven coke is sometimes performed in kilns of rectangular 
 shape, but usually in ovens. The beehive ovens consist of a row of 
 chambers which are either circular or square, and as much as ten feet 
 in diameter in some cases. The coal is charged into these, and the 
 heat necessary to effect its decomposition is obtained by passing air 
 over the upper surface of the incandescent pile, so that the process of 
 coking is effected downwards and inwards, from the top of the mass. 
 Essentially the objects to be obtaiued are, the introduction of « proper 
 amount of air to bum the gases, but not the carbonaceous matters, 
 uniform and rapid coking, and the prevention of loss of heat by 
 radiation. The beehive ovens are those chiefly used, but Appolt, 
 Carves, Coppee and Pemolet ovens are also employed. Sulphur is the 
 most deleterious body present in coke, and one which cannot be 
 removed by any process at present known. A good soke should be 
 hard, brilliant, crystalline, free from sulphur and from dark and dirty 
 patches. 
 
 Coke Basket. — See Moulder's Basket. 
 
 Coke Bed. — (1) The first layer of coke which is introduce? into a cupola, 
 previous to the throwing in of the iron. Its weight beais a definite rela- 
 tion to that of the iron to be melted, but varies with the condition of the 
 furnace. (2) Before moulding and casting pieces of work, plates, &c., 
 having large superficies, and which are bedded in, provision is made for 
 carrying off the gas generated in the mould by mears of a coke bed. 
 This is a porous stratum of coke and clinker in pieces c i various sizes, 
 laid to a depth of several inches below the mould ; the porosity of 
 which allows the gas to escape as into a reservoir, to be drawn off by 
 vent pipes (q.v.). 
 
 Coke Dust. — Used by moulders for the same purpose as ccl dust (q.v.). 
 
 Coke Furnace. — A blast furnace in which coke is used as iuel. 
 
 Coke Mill.— See Blacking Mfll. 
 
 Coke Oven. — See Coke. 
 
 Coke Plate. — Tin plate for which the sheet iron has been refined with 
 coke, as distinguished from charcoal plate (q.v.). " Coke plate " now 
 commonly refers to plate made from puddled iron. This is inferior to 
 charcoal plate. 
 
 Cold Air Machine. — See Refrigerator. 
 
 Cold Bend.— See Forge Test. 
 
 Cold Blast. — Iron smelting furnaces were originally univa-sally fed with 
 a current of air at the ordinary atmospheric temperature. But in the 
 year 1828, at the Clyde works, NeUson introduced the practice of 
 heating the blast before feeding it into the furnace. Hence the 
 distinguishing term "Cold blast" as opposed to hot blast. Iron 
 produced under the old system is called ' ' cold-blast i'on, ' ' and is of 
 superior quality, and much sought after by iron founders for scrap. 
 Cold-blast iron is now made to a very limited extent only, and is 
 
?8 biCTIONARY OF TERMS USED W 
 
 expensive, its manufaoture being confined to about a dozen firms in 
 the kingdom. 
 Cold Blast Iron,— See Cold Blast. 
 Cold Chisel. — A chipping chisel (q.v.). The term is probably used to 
 
 distinguish it from a smith's chisel used for hot iron. 
 Cold Iron Saw. — A circular saw, thick iu proportion to its diameter, 
 having short teeth, sharpened square across the edge of the disc. It 
 runs at a slow speed, and is usually driven by power, though saws 
 worked by hand by the intervention of bevel gearing are in use for 
 portable purposes. A small circular saw is employed for cutting slits 
 in the heads of screws, and other articles where shallow and narrow 
 grooves are required. 
 Cold Riveting. — Small rivets in thin plates are hammered up without 
 
 being heated in the fire, hence the term. 
 Cold EoUed. — Bars and plates rolled without being previously heated. 
 Cold Soiling. — The practice of rolling iron plates cold produces a mate- 
 rial having a high tensile strength, but with a corresponding sacrifice of 
 ductility and toughness. Its effect is, therefore, the reverse of anneal- 
 ing. The surface of iron when cold rolled acquires a greater smooth- 
 ness and polish than when rolled hot. 
 Cold Sand. — See Hot Sand. 
 
 Cold Sawing. — The sawing of iron while cold with a cold iron saw (q.v.). 
 Cold Set. — A smith's set, or chisel-like tool made thicker than the hot set 
 
 (q.v.), and used for nicking cold metal. 
 Cold Shortness, — That condition of wrought iron and steel in which it is 
 impossible to work it below a dull red heat without fracture or crack- 
 ing at the edges, by reason of its brittleness. This condition is due to 
 the presence of phosphorus, silicon, arsenic, and antimony, the first- 
 named being the most common cause of the quahty described. 
 Cold Shorts.— See Cold Short. 
 
 Cold Short. — (1) Wrought iron or steel having the quality of cold shortness 
 (q.v.). (2) When cast metal pours dead or thick it sometimes happens 
 that in those portions of the mould where the mass is thin, or comes into 
 contact with the sand, that section of the metal will, if poured too slowly, 
 soon began to thicken and partly solidify, so that the metal which 
 comes after does not amalgamate properly therewith, but forms instead 
 an imperfectly united contiguous or superimposed layer. The surfaces 
 in contact form a " cold shut," and complete fracture is always liable 
 to take place there. Running short of metal in the ladle, and slight 
 delay in emptying the contents of a second ladle into the mould, is also 
 a fruitful source of cold shuts. Also termed cold shorts and cold shots. 
 Cold Tests. — The testing of the tensile strength of iron and steel bars and 
 plates, by bending, while cold, to a certain angle, both with and across 
 the grain without fracture. 
 Cold Water Fump. — An ordinary lift or force pump, as distinguished from 
 
 a hot water pum.p (q.v.). 
 Cold Water Test. — The ordinary hydraulic test, for pressure only, to 
 which steam boilers are subjected, as distinguished from a hot water 
 test (q.v.). 
 Collapse. — The failure of a tube or cylinder due to the stress of pressure 
 
 applied externally. 
 Collapsible Core Bar. — See Core Bar. 
 
 Collapsing Pressure.— The pressure which, applied to the outside of a 
 tube, causes it to fail by bending or crumpling inwards. In its usuaJ 
 
Mechanical mngineMrIng. fg 
 
 application, it has reference to the tubes and fire-boxes of steam 
 bo&ers. 
 
 Collar. — A ring formed on a shaft, either by forging in the solid, or by 
 being made as a separate casting or forging, bored or turned, and held 
 in place with a set scre-w or a split pin. The use of a ooUar is to pre- 
 vent endlong play in the shaft by providing a face that shall work 
 against the bearing flanges of brasses, or to retain loosely running 
 gear, or gear not otherwise confined endways, in place relatively to the 
 longitudinal direction of the shaft. 
 
 Collar Bearing. — A bearing provided with several rings or collars, to take 
 the thrust of a shaft (see Thrust Bearing), or in the case of a vertical 
 shaft to provide adequate surfaces for lubrication. 
 
 Collar Gauge. — See Cylindrical Gauge. 
 
 Collaring. — The clinging to and wrapping of a rolled bar around the 
 bottom roU of a rolling mill. See Stripping Plate. 
 
 Collar Tools. — See Swage Tools. 
 
 Collecting Vessel. — A cylindrical vessel enclosed in a steam boiler for the 
 purpose of collecting the muddy ingredients contained in the water, 
 and which would otherwise produce scale and cause incrustation. The 
 vessel is perforated to admit the water which bubbles over into it, 
 carrying over also the sediment, the last settling down into the smooth 
 water within the vessel, to be subsequently blown out at intervals. 
 
 Collet. — The disc or ring, as the case may be, by which screwing dies are 
 held fast. Also the clip by which nuts are held in a screwing machine. 
 
 Colour Brushes. — The brushes used by draughtsmen are camel hair, 
 Siberian, or sable hair, mounted in crow, duck, goose, swan, or eagle 
 quills, their value increasing in the same order. See Broad Brush, 
 Softener, "Wash Brush. 
 
 Columbier Drawing Paper. — A paper measuring 34J in. by 24 in. 
 
 Column, — A column may be considered as a beam set on end, and 
 receiving pressure in the direction of its longitudinal axis. But the 
 conditions of these vary with the length. (See Long Column, Short 
 Column.) The resistance of a column to flexure is diminished by 
 rounding the ends, increased by flattening them, stOl further increased 
 by extending their area, and by fixing them both. 
 
 Combination Caliper. — A caliper pivoted near the centre of the two legs, 
 making thus four movable ends. Of these the two to the one side of 
 the pivot are used for inside, and the two on the other for outside 
 measurements. 
 
 Combination Chuck. — A universal chuck (q.v.) which is also endowed 
 with the property of independent action of the jaws. It is the geared 
 form of chuck principally which is made for combination by a cam move- 
 ment through which the pinions are thrown out of gear with the rack. 
 
 Combination Gauge, or Compound Gauge. — ^A dial gauge which has two 
 sets of registers, as pressure and vacuum, pressure and head of water, 
 pressure and heat of steam. 
 
 Combination Machines, or Compound Machines. — Machines designed and 
 adapted for performing several different processes, either at different 
 periods of time or simultaneously. 
 
 Combined Carbon. — Carbon which has entered into true chemical combina- 
 tion with iron to form white iron, chilled iron, or steel. The com- 
 pounds so formed are sometimes termed carbides of Iron. Sea 
 Graphitic Carbon. 
 
 pombined Steam. — Superheated steam (q.v.) and wet steam (q.v.) allowed 
 
86 DICTIONARY OF TERMS tlSEt) IN' 
 
 to mmgle together before use. It is advantageous to employ steam of 
 this character in order to diminish the evils of toiler corrosion on the 
 one hand, and of priming on the other. Its temperature should not 
 exceed 310° F. 
 
 Comb Tools. — Chasers (q.v.). 
 
 Combustible Mixture. — See Charge. 
 
 Combustion. — The chemical union of bodies with oxygen. It is accom- 
 panied by the evolution of heat, sometimes, though not necessarily 
 with light, since the slow rusting or oxidation of iron is combustion as 
 truly as the vaporisation of a metal in the electric arc. Combustion 
 results in various well-defined products. (See Products of Combustion.) 
 There may be partial or complete combustion (q.v.). The laws of 
 combustion receive practical application in calculations bearing on the 
 air supplies of furnaces, fuel, fire-grate areas, calorific power and 
 intensity, specific heat, and kindred subjects. 
 
 Combustion Chamber. — That portion of a boiler flue ia which the hot 
 gases are burnt. It is situated between the fire-grate and the smoke- 
 flue proper. 
 
 Combustion, Products of. — See Products of Combustion. 
 
 Coming to Nature. — A term used by puddlers to signify the stage of the 
 accession to the pasty condition of the ball of iron undergoing the 
 operation of puddling. Also called drying. 
 
 Common Jaw Chuck. — A lathe face chuck whose jaws are stepped in three 
 sections, that being the ordinary form. 
 
 Common Safters. — The lighter rafters which lie between the principals or 
 principal rafters and cross the purlins in a roof structure. 
 
 Common Slide Valve. — The ordinary plain D-slide valve in which the 
 amount of openings of the ports, both for steam and exhaust, are equal, 
 as distinguished from the exhaust relief valve (q.v.). 
 
 Common Thread. — An ordinary Whitworth screw thread as distinguished 
 from a gas thread. 
 
 Common Tin. — See Boiling. 
 
 Compass. — ^A drawing instrument used for measuring and transferring 
 distances, and for describing arcs and circles. It consists of two legs 
 movable about a sector joint. The legs may be single or double 
 jointed, and may each be an integral portion of the compass, or one 
 may be removable to permit of the substitution of separate legs for pen, 
 pencil, or point, and for a lengthening bar (q.v.). Workmen's com- 
 passes are either made plain without any means of tightening or setting 
 minutely, or they are wing compasses. See also Bows, Dividers, 
 Hair ' Compass, Spring Bows, Proportional Compasses, Triangular 
 Compasses, Wholes and Halves. 
 
 Compass Caliper. — A scribing tool having one leg caliper shaped, the 
 other straight like a compass and pointed. It is used for scribing lines 
 from the end of a piece of work, the curved leg being slid along in 
 contact with the end, while the point of the straight leg scribes a line 
 parallel therewith. 
 
 Compass Saw. — A short narrow saw, tapering towards the point, used for 
 cutting sweeps and curves by hand. Sometimes termed a table saw. 
 
 Compensating Collars. — Annular rings or collars inserted on the spindles 
 of drilling machines between the feed screw and the grooved spindle, to 
 form hard wearing surfaces, and by whose adjustment the wear of the 
 spindle and collars can be taken up. 
 
 Complement. — The complement of an angle is its difference from 90°, 
 
MECHANICAL ENGINEERING. 8i 
 
 CoMplete Comtustion. — Combustion, -where all the elements contained ia 
 fuel, or in gaseous charges, enter fully into chemical combination with 
 atmospheric air. In chemical language their atoms are fully satisfied. 
 The regulation of the fuel and air supply of furnaces should, for 
 economical reasons, approximate as nearly as possible to these condi- 
 tions. 
 
 ComponeDfc. — The components of a force are the various forces which 
 combine to make the resultant (q.v.). 
 
 Composition of Forces. — The process or method of ascertaining the resul- 
 t>ant (q.v.) of a series of single forces from a consideration of the magni- 
 tudes and directions of those forces. It is effected either by calculation 
 or by a graphic method, Unea being drawn whose relative lengths 
 represent the magnitudes, and whose directions represent the directions, 
 of the various single forces. 
 
 Composition of levers See Compound Lever. 
 
 Compound Adjutages. — Adjutages, where the shape of the pipe is modi- 
 fied to increase the flow of liquid, the head remaining the same. See 
 Vena Contraota, Converging Mouthpiece. 
 
 Compound Engine. — An engine romprising two or more cylinders with 
 their parts. The steam, after doing work in the smaller or high-pres- 
 sure cylinder, is allowed to exhaust into a larger or low-pressure 
 cylinder, or cylinders, and to do useful work under expansion. The 
 advantage obtained is that the irregularity of motion and the liquefac- 
 tion of steam which occur when the variations of initial and terminal 
 pressures are confined to one cylinder, are minimised by dividing them 
 among two or more cyhnders, so that both pressure and temperature 
 become more equahsed. High ratios of expansion are also obtained 
 without the employment of complicated cut-ofl; gear. 
 
 Compound Expression. — An algebraical expression consisting of more 
 than one term. Compound expressions consisting of two, three, or 
 more terms are called binomial, trinomial, and multinomial respec- 
 tively . 
 
 Compound Gauge. — See Combination Gauge. 
 
 Compounding. — The addition of a low-pressure cylinder to an engine 
 which has hitherto possessed a high -pressure cylinder only. 
 
 Compound Lever. — A system of levers by whose combination great 
 power is developed within a restricted space, the mechanical gain 
 equalling the product of all the long arms divided by that of all the 
 short arms. A testing-machine (q.v.), a wheel train (q.v.), and a 
 weigh-bridge (q.v.) afford examples of compound levers. 
 
 Compound ItEachine. — See Combination Machines. 
 
 Compound Oils. — The advantage of a compound oil is beHeved to consist 
 in this : that certain advantages of single oils are gained and their dis- 
 advantages neutralized, thus — an animal oil alone is liable to develop 
 acid, to the consequent corrosion of the bearings with which it is in 
 contact ; a vegetable oil alone is apt to dry and gum, or become sticky 
 and clog the bearing ; a mineral oil alone is usually thin, has a low 
 firing point, and is Uable to become squeezed out and evaporated or 
 volatilized. But by a combination of the three, the body of the animal 
 oil ia retained while its tendency to decomposition is lessened, the good 
 lubricating property of the vegetable is utilieed without much gumming 
 taking place, and the flashing point of the mineral is raised or coun- 
 teracted, while its fluidity and its cleansing action are utHiaed. 
 
 Compound Screw. — A differential screw (q.v.). 
 
 O 
 
82 DICTIONARY OF IE RMS USED IN 
 
 Compound Sliding Table, or Compound Table. — The table belonging to a 
 macbine tool which is used for bolting the work upon, and provided 
 ■with at least two movements, one longitudinal, the other transverse. 
 Commonly a circular movement aroujid its vertical axis is also included. 
 The table of a slotting machine furnishes an illustration of such a com- 
 bination. 
 
 Compound Stress. — A stress of two kinds acting at a single time upon a 
 structure, as torsion and bending, or bending and tension. 
 
 Compound Surface-condensing Engine. — A compound engine (q.v.) pro- 
 vided with the means of surface-condensation (q.v.). Most marine 
 engines are of this type. 
 
 Compound Table. — See Compound Sliding Table. 
 
 Compound Tallow Cup. — A grease cup furnished with two cocks, one 
 leading from the cup into a globular intermediate chamber, the other 
 from the chamber into the cylinder or steam-chest, thus keeping the 
 tallow clean and preventing waste. 
 
 Compound Train. — A train of change-wheels (q.v.) used in screw-cutting, 
 in which there are two or more intermediary wheels on the stud. All 
 screws of fine pitch, or say over about ten to the inch, are out with 
 compound trains. 
 
 Compressed-air Lift, or Pneumatic Lift. — A form of lift or hoist in which 
 air takes the place of water as a motive power, the cage being sup- 
 ported by an air cylinder. It is used for the charging of blast furnaces. 
 
 Compressed Steel. — Cast steel subjected, while in a metallic ingot mould, 
 to hydraulic or steam pressure, being compressed while still in a molten 
 condition. The pressure applied varies from 6 to 20 tons per square 
 inch, depending on circumstances. It is compressed to the extent of 
 about IJ inch per foot of length, its specific gravity being increased 
 thereby. The object of compression is the production of a sounder 
 ingot than can be obtained in an open mould. 
 
 Compressibility. — That property of gases — as air, steam, carbonic acid, 
 &c. — according to which their volumes are reduced by pressure. Pres- 
 sures and volumes vary in inverse proportions in all true gases. Liquids 
 are practically incompressible, though not absolutely so. Solids are 
 compressible in different degrees. 
 
 Compressing Cylinder. — (1) The cylinder of an air-compressor within 
 which the compression of the air takes place. (2) A cylinder used in some 
 gas engines for compressing the air used in the charge, and distinct from 
 the worldng cylinder (q.v.) in which the charge is exploded. 
 
 Compression. — (1) A body is in compression when it is subject to forces 
 tending to crush it in the direction of that axis which is continuous with 
 the line of direction of the pressure. (2) The resistance of the steam left 
 in the end of an engine cylinder and the passage leading thereto on the 
 return stroke of the piston, and which is due to the early closing of the 
 port. This is also termed cushioning. The compression of steam in an 
 engine cylinder should never be allowed to rise above the initial pres- 
 sure of the steam, otherwise the compressed steam wfll force its way 
 against the entering steam into the steam-chest, reducing the pressure. 
 (3) The pressure exercised during its instroke by the piston of a gas 
 engine, on the combustible mixture admitted behind it. 
 
 Compression Bar. — A bar which is being subjected to compression stress. 
 
 Compression Coupling, — See Cone Vice Coupling. 
 
 Compression Engines. — Those gas engines in which the mixed charge is 
 subject to compression previous to ignition. The advan tage of employ- 
 
MECHANICAL ENGINEERING. 83 
 
 ing compression is that a smaller percentage of gas is consumed therety 
 than is the case when the charge is ignited at atmospheric pressure. 
 
 Compression Line. — The line on an indicator diagram which shows the 
 rise of pressure near the termination of the piston-stroke due to com- 
 pression. The presence of a loop at the termination of the line 
 indicates that the steam has been compressed above its initial pressure. 
 
 Compression Strength. — The strength necessary to enable a bar or struc- 
 ture to resist compression or crushing. 
 
 Compression Stress. — The stress due to compression. 
 
 Concentrated Load. — ^A load localised upon a beam, or girder, or struo- 
 tore. Under the same conditions of fixing, a concentrated load wiU 
 produce twice as much stress as a distributed load (q.v.) will produce. 
 
 Concentric Chuck. — A concentric jaw chuck (q.v.). 
 
 Concentric Jaw Chuck. — ^A chuck in which all the jaws are moved uni- 
 formly towards, or from the centre by a common mechanism, thus 
 avoiding the trouble of testing the accuracy of the work by the trial 
 and error method. Concentric jaw chucks are usually of small size, and 
 are made both for lathes and for screwing machines. 
 
 Concrete, or Beton. — Hydraulic lime, sand, and gravel, whose propor- 
 tions vary with circumstances. 
 
 Concrete Block. — A rectangular block of concrete or artificial stone, 
 employed for the foundations of breakwater and harbour works. Such 
 blocks are made by mixing the concrete, depositing it in moulds, and 
 allowing it to set. They are often made to 40 tons weight. 
 
 Concrete Ilizer. — ^A revolving vessel of cast or wrought iron, used for 
 mising the cement, sand, gravel, and water, which form the ingredients 
 in concrete blocks. There are several patented mixers constructed with 
 the view of throwing the materials over from one side to the other, on an 
 average four times during each revolution. 
 
 Condensation. — The reduction of gaseous bodies to the condition of 
 liquids by the influence of cold and of pressure, acting either singly or 
 in combination. 
 
 Condenser. — ^A vessel in which the condensation of gases is effected. 
 Specifi-cally, the vessel in which the condensation of the exhaust steam 
 from an engine cylinder is effected. It is either a jet condenser (q.v.), 
 or a surface condenser (q.v.). 
 
 Condenser Door. — The rectangiilar or round-ended cast-iron plate which 
 closes the end of a surface condenser near the ends of the tubes. When 
 the door is unscrewed and removed, the ends of the tubes are open to 
 inspection. 
 
 Condenser Tubes. — Tubes which traverse the condensers of marine and 
 other engines of the surface condensation type, having steam without, 
 and cold water circulating through their interiors. They are usually 
 drawn tubes of brass or Muntz metal, about -}§ in. thick and from one 
 to two inches in diameter. 
 
 Condensing Engine. — An engine whose exhaust steam is sent into a 
 condenser, instead of being exhausted into the atmosphere. 
 
 Condensing Surface — See Condensing Tube Surface. 
 
 Condensing Tube Surface, or Condensing Surface. — The total area of the 
 internal diameters of the tubes in surface condensers. This area bears 
 a definite relation to the engine power, but varies with circum- 
 stances. 
 
 Conduction. — The transfer of heat from the hotter to the colder parts of a 
 body. Hence conduction depends upon the fact of inequality in 
 
84 DICTIONARY OF TERMS USED IN 
 
 temperature existing in the several portions of the body. The transfer 
 of heat through sohds, as through boiler plates, is due to conduction. 
 See also Convection, Radiation, Transmission of Heat. 
 
 Cone. — ( 1 ) A round pyramid having a circular base. Its sections are : from 
 vertex to base, a triangle ; transversely and parallel with the base, a 
 circle ; if obliquely through both sides, an ellipse ; on a plane parallel 
 ■with the side, a parabola ; when the plane makes a greater angle with 
 the base than the cone, a hyperbola. (2) A driving pulley used for 
 belting, and formed into steps or sections of various diameters, for the 
 governiug of different speeds. (3) The top of a blast furnace is often 
 furnished with a cone for the purpose of preventing the escape of the 
 waste gases into the air, and also for regulating the quantity of 
 the charge. 
 
 Cone Bearing. — Cone bearings are adopted for the mandrels of lathes 
 partly from motives of economy, partly for convenience of taking up 
 the wear. The cones are made distinct from the headstock, and driven 
 into holes bored in the main castings. They are made of hardened 
 steel or of gun metal, occasionally in white metal. In small lathes, 
 there is a single cone only, and a back centre ; in larger ones lliere are 
 two cones, usually placed in a direction reverse to one another. Their 
 wear is taken up with back nuts, pressing against the movable cone at 
 the tail of the headstock. 
 
 Cone Clutch. — A common form of friction clutch in which the power 
 necessary for driving is effected by the bite of smooth turned conical 
 surfaces, male and female respectively, tightened against each other, 
 either by the application of lever or of screw pressure. 
 
 Coned ITeck. — Applied to that portion of a lathe mandrel which runs in 
 the front cone bearing. 
 
 Cone Gear. — Cone clutches (q.v.) employed in hoisting machinery to drive 
 the lifting drum, gears, &c., by the simple friction of their surfaces. 
 
 Cone Key. — A form of key used for retaining a wheel or puUey in place 
 when the hole in the wheel is larger than that portion of the shaft upon 
 which it is keyed. The wheel is bored slightly conical and a conical 
 ring turned to fit in the bored hole and to embrace the shaft. It is 
 then slotted into three parts, forming three separate keys. The wheel 
 is thus maintained concentric with the shaft, and will pass over a larger 
 to a smaller section without the necessity for splitting it. 
 
 Cone Plate, or Boring Collar. — ^A lathe appendage used for boring holes 
 in the ends of work, such as spindles, shafts, mandrels, &c. , which are 
 too long to be centred and held firmly by a giip or face chuck, and 
 which cannot be placed between centres because one end is wanted free 
 for boring. It consists of a small poppet-like bearing, bolted to the 
 lathe bed, and carrying a circular plate or disc perforated with a series 
 of holes conical in section. The plate is centred on the poppet so that 
 by the slacking of a central screw any one of the holes can be brought 
 into coincidence with the lathe centre, and there tightened. The holes 
 being of different diameters, and tapered in section, wOl adapt them - 
 selves to spindles of different diameters. The boring tool is held in the 
 slide rest, and is fed forward into the spindle when boring. 
 
 Cones (1) Sometimes used for producing variable motion in shafting. 
 
 (See Alternate Cones.) And (2) as friction clutches. (See Cone Clutch.) 
 (3) The nozzles of injectors are called after their functions — steam cones 
 and water cones. 
 
 Cone Tubes. — G-alloway tubes (q.v.) 
 
MECHANICAL ENGINEERING. 85 
 
 Cone Vice Coupling'. — A form of box coupling- (q.T.) consisting of an 
 outer barrel whose interior diameter is bored doubly conical, and two 
 sleeves turned without to fit the conical portions of the barrel, and 
 within to fit the shafts. These sleeves are slotted through on one side 
 to provide for their compression inwards, which compression is effected 
 by three screw bolts passing through both, pulling them together so 
 that they tighten on the barrel and on the shaft simultaneously. Some- 
 times called Compression CoupHng. 
 
 Congelationi — The thickening of lubricating oils in cold weather ; hence 
 the necessity for selecting oils with reference to the climate in which 
 they are to be used. 
 
 Conical Rivet. — A rivet whose head is conical in section. It is easier to 
 hammer than the ordinary rivet in a restricted space where a small 
 hammer only can be brought into requisition. 
 
 Conical Spring. — A helical spring (q.v.). 
 
 Conical Turning. — The turning of tapered work in the lathe. It is 
 accomplished between centres by setting over the poppet, and upon the 
 face chuck either by setting over the headstock, or more usually by 
 swivelling the top slide of the slide rest to the angle required. 
 
 Conical Valve. — A form of lift valve for a pump. Its sides are cone- 
 shaped in section and it fits on an annular seating, and has no wings. 
 It sometimes takes the place of the common lift valve with parallel 
 wings. 
 
 Conic FruBtra. — The development of tubular boiler plates is that of the 
 frustra of cones. 
 
 Coning. — The turning of the taper on the diameters of railway wheels and 
 crane and turntable rollers. The object in coning railway wheels is, 
 that as the train runs round a curve, and the wheels are thrown outwards 
 by centrifugal force, the outer wheel may run on the rail where its 
 diameter is greater, and the inner where the diameter is less, so that 
 the difPerence in length of inner and outer curves shall be compensated 
 for by the differences in the diameters of the wheels. 
 
 Conjugate Axis. — The right line which crosses the transverse axis of a 
 curve at right angles. It is the shortest diameter in the case of an oval 
 or an ellipse, and is parallel with the base in that of a parabola. 
 
 Conneoting-Eod. — The rod which converts the rectilinear motion of a 
 piston-rod into the rotating motion of a crank. 
 
 Connecting-Bod. — Marine pattern. See Marine Pattern Connecting-Eod. 
 
 Connecting-Sod. — Obliquity of. See Obliquity of Connectiug-Eod. 
 
 Conservation of Energy. — The principle of the conservation of -energy is, 
 that force is never lost or wasted — that potential and kinetic energy 
 mutually replace each other. Motion is convertible into heat, heat again 
 produces motion ; the diminution of friction renders more power avail- 
 able for useful work, heat dissipated in engines and furnaces is useful 
 work lost. The engineer, of all men, should never forget that energy 
 is indestructible, and his aim should be to utilise and to translate it 
 into the forms, and by the methods most economical for his purposes. 
 
 Consolidated Emery -Wheels. — Sohd emery-wheels (q.v.). 
 
 Constant. — A number deduced from actual experiments made upon the 
 strength of a particular material, and used as a basis in calculations 
 affecting the strength of structures made in that material, but differing 
 in dimensions. Knowing, for example, the weights required to break 
 off, or to induce permanent set in a test bar of cast iron measuring 
 3 in. by 2 in. by 1 in., we can use those weights as constants, by 
 
86 DICTIONARY OF TERMS USED IN 
 
 wHoli to estimate tlie stresses in structures of tte same material, but 
 differing: in length, breadth, and depth. 
 
 Constant Load. — A dead load (q.T.). 
 
 Constant Travel. — The travel of a slide valve which is not rendered capa- 
 ble of variation for purposes of variable out off. See Varying' Travel. 
 
 Continuous Beam. — A beam -which rests on more than two supports. 
 
 Continuous Break, — A break which acts upon a series of wagons simul- 
 taneously, as distinguished from the separate brakes formerly applied 
 to each truck. 
 
 Continuous Feed. — (1) Usually means a delivery of feed water which is not 
 intermittent, as from an injector, or from a pump provided with an air 
 vessel. (2) The feed given to a machine tool, or the work, by means of 
 cog or worm-wheels, and a screw, as opposed to intermittent feed (q.v.). 
 
 Continuous Paper. — Drawing paper and tracing paper, prepared and sold 
 in long roUs instead of in sheets. Any length can then be out for 
 specially long drawings. 
 
 Contracted Vein. — See Vena Contracta. 
 
 Contraction. — The diminution in length which all metals (bismuth and 
 some alloys of bismuth alone excepted) undergo in cooling down from 
 their fusing points. The amount of contraction for different qualities 
 of the same metal varies, as also does the contraction of the same qua- 
 lity under different conditions of mass and of cooling. The contractions 
 of cast and wrought iron, steel, brass, gun-metal, lead, tin, &o., are 
 very variable, and a knowledge of the amounts to be anticipated under 
 varying conditions is indispensable. 
 
 Ccntraction of Area. — The reduction which a bar undergoes in diameter 
 or area previous to fracture, when elongated by tension. The greater 
 the amount of contraction the better the quality of the bar. It varies 
 from about ten per cent, in plates, to twenty per cent, in round and 
 square bars. 
 
 Contraction Kule. — A rule used for the construction and measurement of 
 foundry patterns, whose length exceeds that of the ordinary or standard 
 rule by the amount due to the contraction (q.v.) either of iron or brass. 
 A contraction rule for iron is longer than the standard in the ratio of 
 J in. in 15 in. ; one for brass in the ratio of f in. in 10 in. 
 
 Contract Note. — A piece-work note (q.v.). 
 
 Convection. — The setting up of currents by the heating of a liquid in a 
 vessel. The portions in direct contact vrith the source of heat, being 
 first warmed, become lighter than the others, and rise from the heat- 
 ing surface, allowing colder currents to take their place, which in 
 turn become warmed and give place to others. Hence convection is 
 entirely due to differences in Sp. gravity. The heating of the water in 
 steam boilers is the cause of its circulation, and the greater the heating 
 surface, or the surface suitable for convection, the quicker the circula- 
 tion, and the more rapid the generation of steam. The circulation also 
 in hot water apparatus is due to convection, and the greater the expan- 
 sion the greater the upward force of the ascending currents. 
 
 Converging Mouthpiece. — A mouthpiece placed against the side or the 
 bottom of a vessel for the passage of liquid. Its longitudinal section 
 is that of a truncated cone, and its function is the prevention of 
 the loss of effect due to Vena Contracta (q.v.). The larger apertui-e is 
 next the vessel, and the smaller aperture is equal in diameter to that of 
 the actual jet of water which has to be delivered. 
 
 Converter. — See Bessemer Converter. 
 
MBCHAmCAL nNGINEERING. 87 
 
 Converting. — The term applied generally to tlie manufacture of steel 
 made by the cementation process. Also to the Bessemer process for 
 the direct production of nuld steel. 
 
 Converting Furnace, — See Cementation. 
 
 Converting Pots. — The troughs in which bar iron imdergoes the process 
 of cementation (q- v.) . 
 
 Converting Process. — The process of cementation. 
 
 Cooling. — By the judicious Cooling of the heavier portions of castings the 
 setting up of internal stresses is avoided or minimised. Thus the 
 bosses of wheels are often cooled by raking the sand away from them 
 while the casting is yet white hot. Thick flanges and ribs are cooled 
 in like manner. "Without such precautions, numbers of castings would 
 be lost, owing to the heavier portions, which remain hot longest, 
 continuing to contract after the lighter portions had set fast, and so 
 tearing them asunder. A massive casting when well proportioned 
 should always be allowed to cool down while enveloped in its sand, 
 rather than be stripped and exposed to the air. 
 
 Cooling Surface. — The superficial area in a condenser which is exposed to 
 steam on the one side and to water upon the other. The area of cool- 
 ing surface may be, roughly, one-half or three-quarters that of the 
 heating surface of the engine. 
 
 Cope. — Used to designate the upper portion of a loam mould, or the top 
 flask used in green sand moulding. 
 
 Cope Off. — Signifies the lifting of a loose pattern piece in the top box, or 
 cope (q.v.). 
 
 Cope Eing. — The ring which carries the bricks and loam forming the 
 cope (q.v.) of a loam mould. It is of cast iron furnished with lugs 
 around its circumference for the attachment of chains or links for 
 lifting. 
 
 Copper. — Symbol Cu. Comb, weight, 63. Sp. gr. 8-93. A metal em- 
 ployed for a variety of purposes by engineers. It is not strong, but ia 
 tough. It is used for pump-rods, boiler tubes, rivets, steam pipes, wire, 
 fire-boxes, &c. It is of especial value in the formation of alloys. 
 
 Copper Bit, or Soldering Iron. — A pointed piece of copper riveted to a 
 cleft rod of iron to the opposite end of which a wooden handle is 
 attached. 
 
 Copper Drift. — A short cyUndrieal piece of copper held with a twisted 
 hazel-rod, and struck with a hammer, its use being to prevent the ends 
 of shafts or similar portions of bright finished work from being bruised 
 and burred over, which would happen if they were struck directly with 
 a steel-faced hammer. The copper, therefore, acts as an elastic medium 
 or cushion. 
 
 Copper Glance. — A valuable ore containing copper and sulphur. It is 
 mined in Cornwall. 
 
 Copper Hammer. — A flat paned, double-ended hanmier, made of copper, 
 and employed for the same purpose as a copper drift (q.v.). 
 
 Copper Lining. — A copper bush or liner, driven into the working barrels 
 (q.v.) of iron pumps, to prevent the formation of rust. 
 
 Copper Matt. — See Matt. 
 
 Copper Pipe. — Copper is used for the steam and various other pipes of 
 large engines, its utility consisting in the readiness with which it can 
 be curved to any foim, and in the ease with which it accommodates 
 itself by expansion and contraction to variations of temperature, with- 
 out risk of tearing off the flanges. The flanges of copper pipes are 
 
88 DICTIONARY OP TERMS USED IN 
 
 brazed on (see Brazing Metal), a hole teing bored tlTougb the flang-e 
 to receive the pipe. Copper pipes are filled with molten lead before 
 being bent, in order to prevent wriniling up, and the bending is per- 
 formed in the case of large pipes in a screw press. 
 
 Copper Pyrites. — The most important ore of copper, consisting of copper, 
 sulphur, and iron. It is mined in Cornwall and Devon, Sweden, 
 Siberia, and other parts. 
 
 Copper Wire. — Kne copper wire of about 20 B. W. G. is used for making 
 flanged joiats steam or water tight. It is coiled spirally a few times 
 over the face of the flange, and the ends lapped. The tightening up of 
 the bolts flattens it out, and makes a perfect joint, which has also the 
 advantage of being more readily broken than a red-lead joint. 
 
 Copy. — See Former. 
 
 Copying Frame. — See Printing IVame. 
 
 Copying Machines. — 4^ large class of machines whose purpose is the pro- 
 duction of many similar articles from a single templet, or copy. Of this 
 class are the various tracing, and housing, and spoke and handle turn- 
 ing machines, in which the cutters are affixed to blocks which move 
 simultaneously with a guide, following the outline of the copy, which 
 last is generally made in metal where a very large number of articles 
 are required. 
 
 Copying of Drawings. — See Phototype, Tracing. 
 
 Copying Paper, or Ferro-prussiate Paper. — A sensitised paper used for 
 the reception of prototypes {q. v.). It is prepared as follows : ammonia 
 citrate of iron, I part ; water, 5 parts. Ferrocyanide of potassium, 1 
 part ; water, 4 parts. Mix together in equal quantities. The pajier 
 saturated with this has a yellowish hue, and owing to the various wash- 
 ings which it has to undergo is made very stout. 
 
 Copying Principle. — The principle embodied in the construction of copy- 
 ing machines (q v.). 
 
 Corbels. — Short cantilevers built into, and projecting from the walls of 
 workshops to support the rails for the traveUing wheels of overhead 
 travelling cranes. 
 
 Cordage. — See Hopes. 
 
 Core, — (1) A central portion. (2) In foundry work a body of sand, either 
 green or dried, which takes out the central or inner portions of a cast- 
 ing. Cores are either made in boxes called core-boxes, or if cu-cular 
 and of large size, are struck to shape upon a revolving bar, a mixture 
 of loam being used for the body, and its due outline being imparted to 
 the mass by revolving it against the bevelled or chamfered edge of a 
 templet board, called a core board, or a loam board. When the core is 
 finished and dried, it is put into the moiJd and the metal poured 
 between it and the outer mould. After the casting has cooled, the core 
 is withdrawn from its interior. (3) The central portion of a core pack- 
 ing (q.v.). (i) The body of a smith's anvil. (.5) The wood removed by 
 a boring tool. (6) A wooden or iron model of the interior of the lining 
 of a Bessemer converter, between which and the outer casing the sluri'y 
 used for lining the converter is rammed. 
 
 Core Bar. — A stout iron bar upon which a circular core is struck up. The 
 bar is made to revolve ol the bearings of core trestles (q.v.) and foundry 
 loam is laid upon it and struck to shape against the edge of a board cut 
 to the required outline. Wlien large in diameter it is called a core 
 barrel. Core bars will vary in diameter with the sizes of the cores 
 which they are to receive, ranging from half an inch to a foot or more. 
 
Mechanical sngineerimg. 8g 
 
 For cores of largest size they are encircled with core plates (q.T.). AH 
 bars are hollow tubes, and are pierced with numerous holes for the 
 escape of the gases generated in casting. Light core bars are made 
 from gas pipe, heavier ones are made of cast iron. Good bars should 
 have bearing necks turned at their ends to run in the trestles. Bars 
 are revolved with a wiach handle turned by a core 1" j (q.v.). In the 
 case of pipes of large diameter whose production is a speciality, the core 
 bars are made collapsible, in order to their more ready withdrawal from 
 the casting, and also to save the cost and labour of putting on hay bands, 
 the loam being daubed directly on the bars. An ordinary collapsible 
 bar consists of three longitudinal segments, maintained circular in sec- 
 tion during the striking of the core, by means of internal cones wedging 
 them outwards. After the easting is cooled, the cones are knocked 
 back, and two of the segments collapse or fall inwards, so that the 
 whole bar is loose in its hole. 
 
 Core Barrel. — See Core Bar. 
 
 Core Bench. — A bench consisting of a flat plate of iron, upon which small 
 foundry cores are rammed up in their boxes. A small heap of core 
 sand occupies one portion of the bench, leaving the remainder free for 
 manipulation of the boxes. 
 
 Core Board. — The board against whose edge a core is struck up on a 
 revolving bar. It is commonly termed a loam board, loam being the 
 material employed. 
 
 Core Box. — A box commonly made in wood, though often of iron or 
 brass, in which the core for a hollow casting is rammed up. The box 
 is in its interior a counterpart of the shape of the core, and is so con- 
 structed that when the latter is finished the box can be separated and 
 withdrawn piecemeal, leaving the core intact. 
 
 Core Boy. — A boy who rams up the smaller cores in foundries and turns 
 the core bars for the core-makers. In all foun'li-fs of moderate 
 size there are several such boys, and as little resp'~] -""ibility attaches 
 to the work it is the first task the moulder's appre.jf it is set to per- 
 form. 
 
 Core Carriage. — A low carriage upon which are laid the cores, and the 
 loam patterns of moulds which are to be run into the drying stove. 
 
 Cored Hole. — (1) A cast hole which is cored with adrysan-l core instead of 
 dehvering as a hole directly from the pattern. (2) Gener- 'J y any hole in a 
 casting which is not bored in the machine shop. It is customary in 
 drawings to distinguish rough cast holes from those which are to be 
 bored, by this term. 
 
 Core Irons, or Core Bods. — Rods of wrought iron from i inch or ^ to J inch 
 in diameter, according to the size of core, which I'mu a skeleton or 
 framework upon which a foundry core is made and dric i. Slender cores 
 would fall to pieces, apart from the assistance derived from core irons. 
 After the castings are made the irons are withdrawn by the hand or by 
 pincers. 
 
 Core-maker. — A workman employed in foundries, whose duty is the 
 striking up or ramming up of cores. The core-maker is usually a 
 moulder who has taken to this special department of the work, and 
 having acquired the distinctive knowledge relative 'I'loreto does not 
 quit it. 
 
 Core Oven. — A small oven built over an ordinary stove fire or over a brass 
 furnace, and used for drying small cores. 
 
 Core-packing. — Packing both for steam and water, which is stiffened 
 
50 DICTIONARY OF TERMS USED m 
 
 and rendered more durable by tbe introduction into it of a core, usually 
 of india-rubber. 
 
 Core Plates. — Circular plates, cast in open sand, for fitting upon a core 
 bar -wben the core is of large diameter. The plates form a skeleton or 
 framework, supporting a large mass of hayband and loam, without 
 unduly increasing the weight of the bar. They are secured to the 
 central bar with wedges. To get them out of the casting they are 
 usually broken to pieces by blows delivered from a bar or a hammer. For 
 this reason they are cast thin. They are also pierced with holes to allow 
 a free passage to the gases, and to render their fracture easy. 
 
 Core Sing. — A ring of cast iron which carries the core for a loam mould. 
 
 Core Rods. — See Core Irons. 
 
 Core Sand. — Sand used for making cores. It is a mixture of various sands 
 whose names and qualities vary with the localities in which they are 
 found. It has the property of hardeniag when dried. Horsedung is 
 mixed with it to render it sufficiently porous for the escape of the gases 
 generated during casting. 
 
 Core Stove. — See Foundry Stove. 
 
 Core Trestles. — Strong cast-iron trestles having vee'd-bearings upon their 
 upper edges for the reception of revolving core bars. The core bar is 
 turned by a boy set at a handle inserted into its end, the vees forming 
 a sufficiently good bearing for its journals. 
 
 Coring out. — The taking out or forming of the interior portions of cast- 
 ings with cores, as distinguished from self-deHvery (q. v.). 
 
 Coring up. — The placing of the cores in their positions in a foundry mould, 
 in readiness for casting. 
 
 Cork. — ^Used for glass-paper rubbers. See Rubber. 
 
 Corliss Engine. — A very economical type of engine, the working of whose 
 valves is controlled in an automatic manner from the governor. The 
 inlet and exhaust valves are distinct from each other, and whUe the 
 latter are always opened to their full extent, the former are only opened 
 so much as is permitted by the position of the governors. The valves 
 are moved by rods from a disc or wrist-plate, but are disconnected at 
 every stroke of the engine, and are then closed instantaneously by a 
 dash-piston and spring. The advantages of Corliss engines are that they 
 are strictly automatic in action, the steam supply being proportioned 
 to the requirements of the engine at the moment, and that the steam 
 passages are extremely short, preventing loss due to back pressure 
 (q.v.) and the waste inseparable from long passages, and that the 
 sudden or positive cut-off of the valves is substituted for the gradual 
 cut-off of the ordinary shde-valve. 
 
 Corliss Valve. — The valve of a Corliss engine. The valve forms a seg- 
 ment of a circle and revolves through an arc of a circle in an annular 
 seating, alternately covering and uncovering the steam port. The 
 supply valve is closed by means of a dash-piston (q.v.). 
 
 Corner Sleekers. — Square comer sleekers (q.v.). 
 
 Cornish Boiler. — An internally fired, horizontal, cylindrical stationary 
 boiler, having one furnace flue only. 
 
 Cornish Engine. — A beam engine of massive type, used among the mining 
 districts of Cornwall, and which, variously improved and modified, has 
 taken rank as a standard form for pumping engines in general. For- 
 merly all Cornish engines were single acting, but they are now made 
 double acting, and worked expansively. 
 
 Cornish Valve. — See Double Beat Valve. 
 
MECHANICAL ENGINEERING. 91 
 
 Corollary. — A theorem or problem deduced from a previous related pro- 
 position. 
 
 Corrective Gauge. — See Standard Corrective Gauge. 
 
 Corrosion. — The rusting or oxidation of metals by contact and chemical 
 union -with oxygen in a damp atmosphere. Iron-work is protected 
 from corrosion in many -ways. A common method is to heat it to a 
 temperature of about 31)0° F., and apply to it a coating of pitch or tar. 
 Another is to apply linseed oil cold. Oil paint, when not objection- 
 able, is largely used. Coating with magnetic oxide by BanS's process 
 (q.v.), or Bower's process (q.v.), is employed for bright work. Tallow 
 is also rubbed over bright work when leaving the shops. A coat of pure 
 white lead paint is often given. Galvanizing is resorted to for work 
 which has to be exposed to the weather. See also BoUer Corrosion. 
 
 Corrugated Furnace Tubes, or Fox's Corrugated Tubes. — Pumace tubes 
 for boilers, both land and marine, corrugated in their longitudinal sec- 
 tions. They have come into very general use, their superiority con- 
 sisting in the fact that the strains tending to bulge the end boiler plates 
 are prevented or minimised by the yielding character of the corruga- 
 tions which absorb the linear expansion due to heat. 
 
 Corrugated Iron. — Thin sheet iron, of from 18 to 26 B.W.G. It is rolled 
 out in alternate equal curves of elevation and depression, or ridges and 
 valleys, by which corrugation the rigidity of the sheets is increased. 
 The pitch, or distance between the centres of alternate curves, varies 
 from 3 in. to 5 in. Corrugated iron is used principally for light roof- 
 ing, being united with small bolts passing through the summits of the 
 ridges. 
 
 Corundum. — Crystalline alumina, of which emery (q.v.) is a variety. 
 
 Cos. — The cosine of an angle. 
 
 Cosec. — The cosecant of an angle. 
 
 Cot. — The cotangent of an angle. 
 
 Cottar, or Cutter. — ^A tapered rod or pin, either flat or round in section, 
 used for the purpose of wedging the ends of rods, or of pins into bosses, 
 or of strap ends (q.v.) over their rods. Cottars pass through slotted holes 
 prepared for their reception through the rods and bosses, or the strap 
 ends, as the case may be, and in consequence of the clearance given to 
 the holes on their opposite sides afford a means both of tightening rods, 
 and of taking up the wear of bearings. They are held by their own 
 friction simply when the amount of taper is small, or are kept with set- 
 screws, or have their ends or "tails" screwed and tightened with a 
 nut when the taper is considerable in amount. The gib and cottar 
 arrangement is that in which the cottar is formed in two parts, whose 
 outer faces are parallel with each other, the requisite taper being given 
 to their inner or sliding faces. The fixed half is then termed the gib. 
 
 Cottar Files. — Narrow files, used for the cleaning out of grooves, key- 
 ways, cottar-ways, and similar narrow passages. They are made in 
 three degrees of coarseness. Cottar files are either parallel or tapered 
 in their length ; in the latter case they are called entering files, because 
 they enter into and enlarge or open out small narrow holes. 
 
 Cottar Way. — The oblong slot which receives a cottar (q.v.). Its sides 
 are parallel with each other, but its ends are slightly tapered, to allow 
 of the tightening action of the cottar, the total taper being from about 
 1 in 30 to 1 in 15. 
 
 Cotton. — Cotton is used for steam packing, for ropes for the transmission 
 of power at high speeds, and to a limited extent for belting. 
 
92 DICTIONARY OF TERMS USED IN 
 
 Cotton Card.— See Card Wire. 
 
 Cotton Cords. — Driving cords used f or worliing- overhead travellers. They 
 are about J in. or f in. in diameter, and are remarkably soft and 
 pliable. They run in grooved puUeys, and under similar conditions 
 to ropes (q.v.). 
 
 Cotton Tapes. — Strands of cotton used for purposes of lubrication, the oil 
 feeding along the tapes by capillarity alone. 
 
 Cotton Waste. — See "Waste. 
 
 Counterbalancing. — The addition of a definite amount of "weight to a 
 moving mass, usually a "wheel or crank, in order to equalise the forces 
 or moments around a revolving shaft. Counterbalancing is an im- 
 portant factor in rapidly revol"ving mechanism . It is frequently, though 
 not quite in strictness, termed balancing (q.v.). 
 
 Counterbore. — A kind of flat countersink, used for boring the seatings 
 for cheese-headed screws (q.v.). It is attached to a pin, shank, or 
 mandrel "which fits the hole drilled for the body of the scre"w. See App. 
 
 Connterhraced Brace. — A brace is counterbraced "when it is capable of act- 
 ing both as a strut and a tie. See Counterbracing, Eolling Load. 
 
 Counterbraced Girder. — A girder -which is pro"vided "with counterbracing 
 (q.v.), in order to enable it to withstand the action of a rolling load. 
 
 Counterbracing, or Cross Bracing. — Diagonal bracing introduced into a 
 truss or a girder, for the purpose of giving additional support to the 
 beam and relieving it of transverse stress. 
 
 CounterpresBure. — Back pressure (q.v.). 
 
 Counter Shaft. — A short shaft, intermediate, or between the line or main 
 shafting in a workshop, and the particular machine or machines which 
 it has to drive, its use being to transmit the rotation of the line shaft- 
 ing to the machine, and to modify the speed. Countershafts are neces- 
 sary, because of the different speeds at which different machines require 
 to be driven. 
 
 Countersink. — (1) A hole recessed conicaUy for the head of a screw or rivet, 
 in order that the head shall lie level with the surface of the material 
 into which it is fitted. (2) The bit "with which a hole is countersunk. 
 It is often called a rose bit. 
 
 Countersinking. — The recessing of the orifice of a hole by drills or coun- 
 tersink bits, to receive the heads of screws and rivets. 
 
 Countersunk. — A hole recessed with a countersink bit is said to be coun- 
 tersunk. 
 
 Counter"wreigh.t. — A balance weight (q.v.). 
 
 Country Cut. — Timber which baa been sa"wn into planks and boards in 
 the districts where itwas felled. Itis usually unequalin thickness, and 
 the saw teeth being coarse leave the surfaces of the boards rough, so 
 that working it up is a wasteful process. 
 
 Couple. — A mechanical couple consists of two forces which are equal and 
 opposite, and therefore in equilibrium. 
 
 Coupled Wheels. — Locomotive running wheels are coupled or connected 
 with coupling rods, in order to ensure uniform running ; that is, the 
 weight necessary for adhesion is distributed equally between all the 
 coupled wheels. They are called four, six, or eight coiipled, according 
 as the wheels on two, three, or four axles are thus united. 
 
 Coupler. — The ring or loop which is slid along and tightened over and 
 around the handles of smiths' tongs, in order to make them take a 
 firm grip on the work. See also Hooks and Eyes. 
 
 Coupling. — (1) A drawbar (q.v.). (2) The uniting together of lengths of 
 
MECHANICAL ENGIXEERING. g;; 
 
 shafting or pieces of meolianisin, wheels or engines. (3) Tlie medium 
 through which shafting, &c., is united. Shafting is united by flange 
 couplings (q.T.) or box couplings (q.v.). (4) Engines are said to be 
 coupled, when in a compound arrangement, high and low-pressure cylin- 
 ders are not made to di c mnect and work independently of one another. 
 (5) The coupling for railway trucks consists of two links of wrought 
 iron united by a right and left-handed screw. The screw being fed by 
 a pendent lever, the coupling is either tightened or extended. 
 
 Conpling Boxes. — Loose, freely fitting boxes used fur coupling together 
 the breaking pieces (q v.) of puddling roUs with the roU necks. They 
 fit, one-half over the roll neck, and one-half over the breaking piece, 
 and are held with stops. 
 
 Coupling Eod. — A connecting-rod which couples or unites the motions of 
 two cranks, rendering their action simultaneous. 
 
 Cover. — Lap (q.v.). 
 
 Covering of Pipes. — Steam pipes are clothed with numerous non-conduct- 
 ing compositions to prevent coohng and condensation by the atmo- 
 sphere. Felt, fossil meal, slagwool, sawdust, asbestos, and numerous 
 patent compositions are employed, and the leaving of air spaces in com- 
 bination with wool, cotton, or felt is also practised. 
 
 Covering Strip. — The strip of metal plate which covers a butt riveted 
 joint. Called also welt, and fish plate. 
 
 Cover Plate. — A term of general application, signifying any plate which 
 covers in an open space, or a portion of a machine. 
 
 Coversin. — The coversed sine of an angle. 
 
 Cowburn Valve, or Dead-Weight Safety-Valve. — A form of safety-valve 
 in which no lever or spring is employed, but the valve is instead held 
 down by what are termed pendent weights, that is, annular weights 
 dropped over a casing attached to the upper portion of the valve. These 
 valves have not so neat an appearance as the ordinary types, but 
 possess the advantage of having an amount of weight directly corre- 
 sponding with the pressure in the boiler. Grouped valves are those in 
 which, instead of having a single opening as is usual in ordinary valves, 
 the total area is divided between several smaller areas of one square 
 inch each, each separate valve opening being therefore weighted to as 
 many pounds of dead weight as the required pressure, so that for 
 50 lbs. pressure there would be 60 lbs. on each separate valve of 1 in. 
 square. 
 
 Cow Hair. — This is used for loam moulds for the same purpose as horse 
 dung (q.v.). 
 
 Cow-mouthed Chisel. — A round-nosed chisel ground to a thick angle and 
 used for chipping hollows in metal work. 
 
 Cowper Stove. — A stove, constructed on the regenerative principle, and 
 employed for increasing the temperature of the blast (see Hot Blast) for 
 smelting purposes. The hot waste gases which come off from the top 
 of the blast furnace are brought over and made to combine with air in 
 a vertical tube, whence the heated products of combustion pass dovm 
 through a chequer work of brick by which the temperature is regulated, 
 and thence into the blast main. 
 
 Cowrie Pine. — See Kauri Pine. 
 
 Crab. — (1) A low type of hoisting crane which has no jib, but is provided 
 with a snatch block or running pulley, dependent from the barrel. Cr 
 the lifting chain passes from the barrel to a snatch block dependent 
 from shear legs (q.v.). Crabs are made to work by hand or by steam, 
 
94 DICTIONARY OF TERMS USED IN 
 
 and are fixed to the ground, or travel on gantry beams. They are of 
 all sizes, and single, double, and treble geared. (2) A claw clutch ia 
 called a crab. 
 
 Crab Winch. — A crab (q.v.). 
 
 Cradle. — (1) The end girders of overhead travelling cranes which carry the 
 running wheels are termed cradles. (2) The term ia also appUed 
 generally to carriages and movable bearings running beneath a beam. 
 
 Cramp. — A tool for squeezing, made both in wood and metal. 
 
 Crane. — A machine used for the hoisting of heavy weights by the inter- 
 vention of gear-wheels, chaia barrel, chain, and jib. The jib (q.v.) is a 
 beam or strut standing at an angle with the ground Hue, and the lifting 
 chain runs over a pulley at its top end, and depending therefrom sus- 
 tains, and lifts, and lowers the load. Cranes are worked either by hand, 
 steam, or hydraulic pressure. See details under specific headings. 
 
 Crane Chain. — Ordinary close link chain (q.v.). 
 
 Crane Hook. — The hook which depends from the Ufting chain, and to 
 which the load or the sling chain (q.v.) is attached. In a properly 
 shaped hook the centre of gravity of the load should be suspended 
 immediately beneath the centre of the swivel. See also Kam's Horn. 
 
 Crane Jib. — See Jib. 
 
 Crane Ladle. — A foundry ladle (q.v.) of the largest type, and which ia 
 therefore slung in the crane. It may hold from four or five to twelve 
 or fifteen tons of metal, according to the requirements of the foundry. 
 
 Crane Post. — The pillar upon which the stresses due to the load on a crane 
 are mainly concentrated. At its head it sustains the tension of the ties 
 and at the ground line (q.v.) the thrust of the jib. Its strains are 
 therefore those of a cantilever tending to break off across the ground 
 line. Hence it is the custom to make the longitudinal outline of a post 
 conical or paraboHc in form, tapering from the ground line upwards. 
 All types of cranes are not alike provided with posts, crabs and over- 
 head travelling cranes of various types being the exceptions. 
 
 Crank, — A lever which rotates about the axis of a shaft. The usual form 
 of engine crank is that which consists of a web of metal stiffened with 
 a rib or ribs, a boaa to receive the crank shaft (q.v.), and a smaller boss 
 to take the crank pin (q.v.). Often the crank ia a simple bending In 
 the crank shaft, or axle. Sometimes a crank is circular, in which case 
 it is termed a disc crank (q.v.). 
 
 Crank Axle. — The axle of a locomotive upon which the cranks are 
 formed. 
 
 Crank Circle. — The circle described by the crank pin. Specially the circle 
 in a valve diagram (q.v.) which represents the path of the crank. See 
 Orank Path. 
 
 Crank Disc. — See Disc Crank. 
 
 Crank Handle. — A small lever having a handle at one end and a boss at 
 the other, the latter being made to fit over the squared ends of spindles, 
 so that they may be rotated by the turning of the handle. 
 
 Cranking. — In cutting tools, cranking signifies the hollowing or curving 
 of the tool immediately behind the cutting edge. It is performed in 
 order that the tool shall have a tendency to spring back and out, 
 rather than hitch into the work under the stress of a heavy cut, 
 and also to give a body of metal for grinding, to prevent the need 
 of frequent reforging. In principle the cutting edge should not stand 
 higher than the face of the tool shank. 
 
 Crank Path. — The circle described by the crank pin (q.v.). 
 
MECHANICAL ENGINEERING. 95 
 
 Crank Pin. — The piu or movable journal wHoli unites the connecting- 
 rod of an engine or pump with the crank. 
 
 Crank Plate. — See Disc Crank. 
 
 Crank Shaft. — The shaft upon which the main boss of a crank is keyed, and 
 "which, therefore, receives and transmits the circular motion of the crank. 
 
 Crank Weh. — The central plated portion of an ordinary cast-iron crank, 
 ■n-hich contains the bosses and is stitEened vrith a rib or ribs. 
 
 Crank Wrist. — A crank pin (q.v.). 
 
 Creaking. — The peculiar sound emitted by a bar of tin when bent 
 alternately backwards and forwards. 
 
 Creaser. — A fuller (q.v.). 
 
 Creases. — A term applied to the moulding tools of the coppersmith which 
 fulfil the same purpose as the top and bottom tools (q.v.) of the smith. 
 
 Creasing Tool. — A tool used by coppersmiths for making beads and tubes. 
 It is of a X-shape, having the horizontal portion furnished with grooves 
 of various sizes. 
 
 Creeping. — The very slight loss of speed which results when drums are 
 driven by rope gearing, due to the slipping of the rope. This, though 
 almost infinitesimal in amount, is sufficient to cause a sHght difference 
 in the number of revolutions performed by the driving and driven drums 
 when a considerable space of time — an hour, for example, is taken into 
 account. In some instances, as in the case of belting, creeping is 
 probably also due to the elasticity of the belt itself, which stretches on 
 the tension side and contracts on the slack side, so causing a slight 
 amount of loss. 
 
 Creosoting. — The injection of timber which has to be exposed to atmo- 
 spheric influences, with creosote, in order to increase its durability. The 
 timber is first deprived of its moisture, which is then replaced with 
 creosote. The durability of the wood is enhanced thereby fourfold, 
 or more. 
 
 Creosoting Cylinder. — A strong wrought-iron cylinder, in which raOway 
 timbers, sleepers, &c., are exhausted of their moisture in vacuo^ and 
 saturated with creosote pumped in under pressure. 
 
 Creosoting Plant. — The apphances used in the saturation of timber with 
 creosote, consisting of cylindrical receivers, vacuum and pressure pipes 
 and connections. 
 
 Crimson Lake. — The colour used to distinguish steel in sectional drawings. 
 
 Crippling. — ^When the elasticity of a beam or structure is destroyed so 
 that it becomes permanently and excessively bent and wrinkled, with- 
 out, however, undergoing actual fracture, it is said to be crippled, or 
 buckled. 
 
 Crocodile Shears. — See Alligator Shears. 
 
 Crocodile Squeezer. — See Alligator Squeezer. 
 
 Crook Bit Tongs, — Smith's tongs whose jaws are bent round at right 
 angles with the handles, one jaw being furnished with a bit or nib to 
 prevent the slipping of the work. These tongs allow rods to be held 
 and to be passed alongside of and parallel with the handles. 
 
 Crop Ends, — The ends cut off from rails after they leave the roUing mill. 
 
 Cropping, — (1) The cutting or shearing off of puddled bar into lengths 
 suitable for piling (q.v.). (2) The sawing ofE of the rough ends of bars 
 and rails. 
 
 Cropping Machine. — A shearing machine used for the cutting off of ends 
 and short lengths of iron bars. 
 
 Cropping Shears. — Alligator Shears (q.v.). 
 
gS DICTIONARY OF TERMS USED IN 
 
 C?ross. — (1) A four-armed beam used in foundries for lifting heavy moulding 
 boxes and loam moulds about, the -weights being suspended in links 
 slung from tf^e ends of the arms. (2) A wrought-iron pipe connection 
 having four .\ ays or openings arranged in the form of a cross, for eon- 
 neoting four pipes meeting at right angles. 
 
 Oross-bending, or Cross-bending Strain. — As usually understood, signifies 
 the strain acting in a transverse direction on horizontal-engine beds, 
 pump beds, and base plates, due to the thrusts of the rods. To reduce 
 this to a minimum the centres of the cylinders and rods are kept as low 
 down as pos.-i-lle, lessening the leverage thereby. 
 
 Cross-bracing - - jSee Counterbracing. 
 
 Cross-breaking. — The actual fracture of a beam or structure due to tensile 
 forces operating thereon. 
 
 CrosB-cut Chisel. — A chipping or cold chisel, which is very narrow, or 
 from \ inch to f inch wide. It is used for cutting grooves in various 
 directions across a plane surface, in order to facilitate the work of sub- 
 sequent chip_ jrg. 
 
 Cross-out Saw. — ^A saw provided with two handles, one at each end, and 
 used for cutting heavy timber — as deals, balks, &c. — across the grain. 
 The teeth a" ; of the shape of an equilateral triangle, so that the thrust 
 is given froi • t aoh end of the saw alternately, the cutting being equally 
 efficient in \>iia. directions. 
 
 Cross-cutting. — The removal of material in a transverse direction. Com- 
 monly appUed to the action of a cliisel or a saw. 
 
 Crossed-arm Governor. — A governor in which the points of suspension 
 of tb . ■ 'ods from which the balls depend are on the opposite sides of the 
 centicil axis around which they revolve. See Parabolic Governor. 
 
 Crossed Belt. — A driving-belt which undergoes a twist between the 
 driving and driven pulleys, passing from the upper side of one to the 
 lower side of the other. With a crossed belt the pulleys revolve in 
 opposite directions. 
 
 Crossed Bods. — When the eccentric rods of reversing-engines cross each 
 other on their way to join the ends of the slot-link, the centres of the 
 sheaves being between the axle and the link, this term is applied to 
 them ; when they do not cross, the rods are said to be open. 
 
 Cross Girder. — Any transverse girder or beam which unites longitudinal 
 girders, side frames, or standards together, and becomes at the same 
 time a distance-piece, stretcher, or strengthening beam, or the sup- 
 port also, or base, for machinery. Examples occur in the cross or central 
 girders of steam cranes. 
 
 Cross Grain. — Signifies a section of timber taken at a low angle with 
 the direction of the longitudinal growth of the fibres. Or when cutting 
 action takes place in such a direction as to produce a tendency to tear 
 up the grain ; as, for instance, vrhen the front of a plane moves in the 
 same direction as the downward slope of the grain fibres, the tool 
 is said to work against the grain, or cross-grain. The term cross- 
 grain or cr';.-->! -grained also alludes to a curly or interlacing condition 
 of fibres, in^io noticeable in hard than in soft woods, so much so in 
 many specimens that an ordinary plane wUl tear up the fibres when 
 applied in any direction. 
 
 Cross Head. — (1) That portion of an engine or pump which unites the 
 piston and connecting rods and slide-blocks together. (2) The upper or 
 transverse beam of an hydraulic press, which transmits the pressiu-e to 
 the weight to be lifted. (3) A cast-iron plate attached to the top of the 
 
Mechanical engineering. 97 
 
 plTlnger of an accumulator, and to whioh the weight case is fastened. 
 (4) The end of a wheel press (q.v.) . 
 Crossings. — Gaps in the rails of permanent way, through which the 
 
 flanges of wheels can pass where one hne of rails crosses another. 
 Cross Joint. — See Breaking Joint. 
 
 Cross-over Koad. — A short diagonal hne of raUs on permanent way, pro- 
 vided with a pair of points or switches at each end, and connecting two 
 parallel lines of rails together. 
 Cross Pane. — See Pane. 
 
 Cross Section. — A transverse section, always understood, unless otherwise 
 noted, to be at right angles with the longitudiaal axis of the piece of 
 work or drawing through which the section is taken. 
 Cross Slide. — The horizontal shde or bridge which carries the tool box of 
 a metal planing machine. The tool box is traversed across it by means 
 of a horizontal screw, and the slide is elevated and depressed with vertical 
 screws actuated by bevel- wheels. 
 Cross Tail. — In a side-lever engine (q.v.) the rod which unites the side 
 
 levers with the connecting-rod. 
 Cross Tubes. — The heating tubes in a steam boiler — usually applied to 
 boilers of the vertical type. The tubes pass through the fire box, the 
 fire therefore surrounding them, and assist in maintaining a rapid cir- 
 culation of the water. A mud door is placed opposite the end of each 
 tube, so that it may be cleaned readily. 
 Cross Tube Boiler. — An ordinary vertical boiler (q.v.) provided with 
 
 cross tubes (q.v.). 
 Crow. — See Crow Bar. 
 
 Crow Bar, Crow, or Pinch Bar. — A roimd iron bar flattened to a ohisel-like 
 expansion at one end, and used for raising a heavy weight through a 
 short distance, for pinching trollies and wagons along a line of metals 
 through a limited distance, and generally for the application of a large 
 leverage for a temporary purpose. 
 Crown of Boiler. — See Boiler Crown. 
 
 Crown Plate. — The commonest quality of wrought-irou plate manufac- 
 tured. 
 Crown Wlieel. — ^A bevel-wheel upon a vertical shaft, having its teeth 
 
 facing uppermost. 
 Crow's Feet, or Ticks. — The angular lines < > which are used in draw- 
 ing, to indicate the points between which a dimension is given. 
 Crucible. — (1) Crucibles are deep cup -shaped vessels used for melting brass, 
 steel, and other metals. They are manufactured of fire clay, or of 
 plumbago. The clay is ground, sifted, and mixed with water, and 
 with a certain proportion of burnt clay obtained from old crucibles, and 
 kneaded and wrought into shape. They are either wrought into shape 
 by hand, or pressed into moulds made of plaster of Paris, which absorbs 
 the water from the surface of the crucible. Afterwards they are dried 
 and heated up to redness. Crucibles should stand the strongest heat 
 to which they may be subjected without fusion, or cracking, or much 
 wasting away ; they should also withstand the corrosive action of the 
 materials melted in them, and resist the pressure of the tongs and the 
 weio'ht of the contained metal. The nature of the constituents 
 employed in their construction varies therefore with the materials 
 which they are to melt. (2) The lower portion of a blast furnace, 
 into which the reduced metal sinks, is called the crucible, or the 
 throat. 
 
98 DICTIONARY OF TERMS USED IN 
 
 Crucible Cast Steel. — Ordinary oast steel (q..T.), as distinguished from 
 Bessemer and other mild steels. 
 
 Crucible Tongs. — Tongs used by brass and steel founders for the lifting 
 of crucibles out of the melting furnace. They embrace the sides of the 
 crucible, and the handles are clamped with a coupler (q.v.). 
 
 Crude Oil. — Oil newly expressed, and nnpurified. 
 
 Crushing Strain. — The strain necessary to cause the failure of a material 
 by compression only. With rigid metals (q.v.), as cast iron and steel, 
 and short specimens, the crushing strain produces sheariug at an angle. 
 With flowing metals (q.v.) the specimens give way by bulging. 
 
 Crushing Strength. — The crushiag strength of a material is assumed to 
 he equal to the weight which will just crush a prism of one inch square, 
 and from one, or one and a half, to four or five diameters, in height 
 only. 
 
 Crutch. — The cross, or transverse arm of a foundry ladle. 
 
 Crutch-handle Shovel. — ^An ordinary foundry shovel, the head of whose 
 handle is in the form of a letter "X, or hie the head of a crutch. 
 
 Crystallization of Iron. — This is affected by the conditions under which 
 it is cooled. If cooled rapidly against a cold metallic surface it becomes 
 chilled, and the crystals are long and needle-like. If cooled slowly the 
 crystals are large and the grain is coarse. Crystals which are near the 
 sujface always arrange themselves at right angles to the surface. 
 Crystals near the surface are always smaller than those nearer the cen- 
 tral portions. The crystals of graphite mingled among those of the iron 
 are also affected by the conditions of cooling, remaining uncombined in 
 metal cooled slowly, but entering into chemical combination when cooled 
 rapidly. 
 
 Cube. — (1) A square prism, bounded by six equal faces, perpendicular to 
 each other. (2) The cube of a number is the product of the number 
 multiplied twice into itself. 
 
 Cube Eoot. — The cube root of a number is the number which multiphed 
 twice into itself would produce its cube. 
 
 Cup Chuck, or Bell Chuck. — A hollow cylindrical chuck, made in various 
 modifications and sizes for turning work. Cup chucks for metal turn- 
 ing are provided with set-screws for pinching rods and bars during 
 turning. For wood turning the timber is driven into the cylindrical 
 hole, and holds by its own friction. Small chucks are made of brass, 
 large ones of iron. 
 
 Cup-head Bolt, — A bolt having a hemispherical or cup-shaped head. It 
 is used chiefly on timber work, and is prevented from turning either by 
 a lip underneath the head, or a square-shouldered shank. 
 
 Cup-head Eivet. — See Snap-head Kivet. 
 
 Cup Leather. — Aleather packing used for the pistons of hydraulicm.achines. 
 Its cross section between the sides of the plunger and the bore of the 
 cylinder is U -shaped, so that the sides of the leather are pressed both 
 against the sides of the plunger and of the oyHuder with increasing force 
 as the pressure of the water increases. Cup leathers and hat leathers 
 (q.v.) are made by being pressed into moulds of cast iron. See Cup 
 Leather Press. 
 
 Cup Leather Press. — The mould in which cup leathers (q.v.) and hat 
 leathers (q.v.) are moulded into shape. It consists of two blocks, an 
 upper and a lower, of cast iron turned trvdy, the space between the two 
 blocks corresponding with the intended sectional shape of the leather. 
 The latter is softened in warm water, and squeezed between the two 
 
MECitAtflCAL ENGINEERING. 99 
 
 halves of the mould, by means of a central bolt, and allowed to harden 
 in place. 
 
 fcup Nut.— See Box Nut. 
 
 Cupola. — The furnace in whioh cast iron is melted for foundry use. It is a 
 tall cylindrical hoUow structure, circular in plan, made of wrought-iron 
 plates riveted together, and lined with fii-e -brick. It is provided with 
 charging hole, breast hole, tapping hole, tuyeres, and hearth. Cupolas 
 vary in dimensions with foundry requirements, or from two to four 
 and iive feet in diameter, the height being from five to six diameters. 
 
 Cupola Blast Furnace. — A term applied to the Ughter blast furnaces con- 
 structed in recent years, as distinguished from the older and more solid 
 forms. Cupola blast furnaces are built of wrought iron cased with 
 brickwork. 
 
 Cupola Fan. — An ordinary fan provided with radial vanes, used for 
 supplying the tuyeres of a cupola with air. 
 
 Cup Shake. — A shake in a balk of timber which is circumferential, sepa- 
 rating the annual rings. 
 
 Curb, or Curb King. — ^An internal ring of teeth used for turning or slew- 
 ing cranes around. A pinion revolving in a iixed bearing on the upper 
 portion of the crane, is, by suitable gearing, made to travel round the 
 curb ring, carrying the crane along with it. 
 
 Curb Sing. — See Curb. 
 
 Curved Boof. — A roof arched in end view. Curved roofs are usually 
 covered with corrugated iron. 
 
 Curve of Expansion. — The curve which represents the expansion of a, gas 
 or vapour under diminished pressure. 
 
 Curvilinear. — A line or a path of motion which is curved. 
 
 Curving of Patterns. — Foundry patterns which are long, narrow, and 
 ribbed are curved in the direction of their length to compensate for the 
 curving of their castings, due to the unequal cooliug produced by 
 unequal distribution of metal. The direction and amount given to the 
 curving is always the reverse of that which is expected to take place in 
 the casting. Its direction and amount is solely a matter of experience. 
 
 Cushioning: — A piston is said to be cushioned when the valve is opened to 
 lead. Cushioning takes place just before the end of the stroke and the 
 lead may average -j^ in. in engines running at moderate speeds. 
 
 Cut. — The removal of a shaving from a piece of work in the lathe, or in 
 planing, boring, and similar machines. Thus, it is common to speak of 
 the breadth, length, and depth of a cut. Iron turners and machinists 
 speak of the progress of an automatically cuttiag tool as the cut ; thus 
 the cut is said to be "on," or " off," according as the tool is cutting 
 or not cutting. 
 
 Cut-off. — The termination of the period of admission of steam into an 
 engine cylinder. Cut-o£E took place in the older engines only at the 
 termination of the stroke, but is now effected at fractional parts of it, as 
 I", f , J, &c. The point of cut-off is regulated by the amount of lap on 
 the slide valve. 
 
 Cut-off Plate. — ^A cut-off valve (q.v.). 
 
 Cut-off Valve, or Cut-off Plate. — The second valve in the arrangement 
 for working steam expansively by means of a separate slide. The cut-off 
 valve is usually a plate provided with cross bars and ports, or is solid. 
 
 Cut Sprigs, or Cut Brads. — Used by moulders for mending up broken 
 sand, the sprigs binding the sand together. They are also used 
 
150 DICTIONARY OP T£RMS USED IN 
 
 for thrusting into tlie thinner and weaker portions of moulds to 
 support tile sand. 
 
 Cutter. — ( 1 ) Any cutting tool fixed in a machine, for the automatic cutting 
 of wood or metal. The angles of cutting tools and their shapes vary 
 with tlie nature of the materials to be operated upon. Cutters are held 
 fast in cutter blocks, tool boxes, and cutter bars. (2) Sometimes 
 applied to a cottar (q.v.). 
 
 Cutter Bar.— See Tool Holder. 
 
 Cutter Block. — That portion of a wood-working machine which carries 
 the cutter or tool. The cutter block may be rectangular, or circular, 
 or discoid, in shape, according to the class of machine to which it 
 belongs. Cutters are almost invariably held in place with screws in 
 preference to wedges. 
 
 Cutter Head. — A boring head (q.v ). 
 
 Cutter Holder. — A tool holder (q.v.). 
 
 Cutter Pin Drill. — A modified pin drill (q.v.) in which the pin becomes 
 the guide for a cutter, the extent of whose radius is independent of the 
 size of the body of the drill itself. That part of the body immediately 
 above the pin is swelled into a socket slotted through transversely for 
 the reception of the cutter, whose shank is cottared into the slot, and 
 whose cutting edge turns down at right angles therewith. A hole 
 being drilled for the pin in the first place, the cutter describes a circle 
 around this, and removes a ring of metal equal in radius to the radius 
 of the cutter. Cutter pin driUs are used for holes of two or three inches 
 and upwards in diameter, and are particularly useful for making the 
 holes in iron and steel boiler-plates for the reception of the tubes. 
 
 Cutting Angle. — See Angles of Cutting Tools. 
 
 Cutting Blast. — A cupola blast of too high velocity for the nature 
 of the fuel and charge. A cutting blast will blow away much of the 
 fuel. The pressure should seldom exceed 2 inches of mercury. 
 
 Cutting Edge. — The edge of a cutting tool against which the division of 
 the shaving takes place. On the proper formation of the edge depends 
 the efiioiency of the instrument, and the angles which produce the edge 
 vary with the material to be cut. See Angles of Cutting Tools. 
 
 Cutting Face. — That face of a cutting tool against which the material is 
 removed, and along which it curls or is thrust aside. Commonly the 
 cutting face is the top face. 
 
 Cutting Gauge. — A gauge furnished with a narrow knife-like cutter in 
 place of the ordinary marking point, and used for cutting off narrow 
 parallel strips of thin stuff. 
 
 Cutting Nippers. — A pincer-like tool, having sharp edges of hardened 
 steel, and used for cutting ofi: wire of small gauge. 
 
 Cutting-oif Machine. — A machine used for cutting ofE lengths of bar iron 
 in the smithy, by which the labour of marking off, nicking, breaking, 
 and squaring up is saved. The iron is passed through a hollow mandrel, 
 is stopped by a gauge plate, and is parted by cutters. 
 
 Cutting Pliers. — Pliers (q.v.) which, in addition to the flat and roughened 
 jaws, are furnished with a pair of sharp nippers placed to one side for 
 cutting off wire. 
 
 Cutting Tools. — Tools which shear, or scrape, or cut shavings from 
 materials, in opposition to those which abrade or grind away. Thus 
 chisels and gouges, planes, turning tools in all their forms and modifi- 
 cations may be taken as types of cutting tools. 
 
 Cutting Tools (Speed of).— The speeds of cutting tools vary within 
 
MECHANICAL ENGINEERING. lOJ 
 
 extremely wide limits, teing qtiickest for wood-vorking machinery and 
 slowest for the hardest metals ; thus bearing out the mechanical axiom, 
 that speed and power are in inverse ratios to each other. 
 
 Cutting-up. — The gashing of the broken edges or faces of a sand mould 
 preparatory to adding fresh sand for mending-up. 
 
 Cyanogen. — A compound of carbon with nitrogen, which is believed to 
 play an important part in the transference of carbon to malleable iron 
 in the process of steel making and in the case-hardening of iron. 
 
 Cycle. — A cycle of operations signifies the complete circle of work gone 
 through by an engine in one complete revolution, embracing the admis- 
 sion of steam, its expansion and condensation. 
 
 Cycloid. — A curve formed by a point in the circumference of a generating 
 circle, rolling upon another circle as a base line. 
 
 Cyoloidal Teeth. — "Wheel teeth whose curves are cyoloidal in foinn. 
 
 Cylinder. — (1) A solid whose ends are circles and whose cross sections at 
 any intermediate points are also circles. It may be conceived to be 
 formed by the rotation of a line around the circular ends. (2) In engine 
 work the closed receiver in which the power of the steam, or gas, or 
 water, is made to actuate a disc or piston . 
 
 Cylinder Bit, or Half-round Bit. — A boring tool used for metal or wood, 
 whose section at the cutting face is that of a semicircle. Its cutting 
 face is sloped at an angle of about 4°. It is employed for the boring 
 of very long holes where much accuracy is essential. It is entered 
 first into a shallow hole prepared for its reception with a gouge or a 
 drfll. Also termed a D-bit. 
 
 Cylinder Bore. — The internal diameter of an engine cylinder when finished 
 in readiness to receive the piston. The bore and the length of a piston 
 stroke are among the necessary factors for estimating the horse-power 
 of an engine. 
 
 Cylinder Cock. — See Pet Cock. 
 
 Cylinder Covers. — The covers or ends of an engine cylinder made sepa- 
 rately from the body of the cylinder itself, for convenience of casting, 
 boring, repairs, and examination of the latter. Sometimes the bottom 
 end is cast solid with the cyUnder, and the top or front cover only 
 bolted on. The top cover is always furnished with the necessary 
 stuSing box and gland for the piston rod. In large engines the covers 
 are dished or buckled, the better to withstand the enormous steam 
 pressure. Covers are attached to the cylinder flanges by bolts or 
 studs. 
 
 Cylinder Escape Valve. — A valve supported by a spiral spring, attached 
 to the ends of marine cylinders to permit of the escape of the water of 
 condensation, and of priming. It is enclosed in a cap of metal, to pro- 
 tect the engmeer and attendants from becoming scalded in case of a 
 sudden blow-off of the hot water. Also termed Relief Valve. 
 
 Cyl'nder Flanges. — The flanges cast upon an engine cylinder to which 
 the covers are bolted. They are always external, except in some few 
 cylinders of special construction, where a bottom flange is internal and 
 a top flange external. 
 
 Cylinder lubrication. — Engine cylinders are too often lubricated with 
 tallow of inferior quality, by whose employment destructive corrosion 
 is set up. Animal fats and oils are not suitable for cylinders, but 
 specially prepared hydro-carbon oils should be used. See Oils. 
 
 Cylinder lubricator. — It is necessary that the pistons of engine cylinders 
 should be freely lubricated, and yaiious lubricators are employed for 
 
102 DICTIONARY OF TERMS USED IN 
 
 tlie purpose, iDOtli single and compound tallow-cups, and self-acting 
 lubricators and impermeators (q.v.). 
 
 Cylinder Mandrel. — The mandrels of all lathe poppets of good workman- 
 ship are made hollow, so that the traversing screw is contained therein 
 and travels within the body. Hence termed Cylinder Mandrels. 
 
 Cylinder Metal. — Strong or slippery iron (q.v.) used specially for steam 
 cylinders and liners. Blfenavon, Madeley Wood, and haematite iron, 
 mixed with selected scrap in varying proportions, make good cylinder 
 metal. 
 
 Cylinder Oil. — Oil prepared specially for the lubrication of the pistons of 
 engine cylinders, in preference to tallow, which decomposes, forming 
 fatty acids that corrode the iron. 
 
 Cylinder Passages. — See Port. 
 
 Cylindrical Gauge. — A gauge composed of two pieces, a plug gauge or 
 solid cylinder furnished with a handle, and a collar gauge or hollow 
 cylinder into which the plug gauge fits. These gauges are used as 
 templets for boring and turning parts of machines which are required 
 to correspond in dimensions, the plug gauge being inserted into a bored 
 hole and the collar gauge being slid over the spindle or shaft which 
 is required to fit the bored hole. The use of gauges is not subject 
 to the errors incidental to the handling of calipers. See DiEEerence 
 Gauge. 
 
 Cylindrical Mouthpiece. — The passage of effluent liquid through short 
 parallel tubes produces less contraction than in a thin plate (see 
 Vena Contracta), the coefBcient of discharge for different tubes vary- 
 ing with the length. Thus the coeflScient for a tube whose bore is 
 \or \ the length is -81, where the bore is \ to -^ the length -77, and 
 from Tpy to -^g, '68. If the tubes are not parallel the coefEoients are 
 different : for a converging mouthpiece, the angle of whose sides is 
 13J, the coefficient for the narrow end is -94. "With a diverging mouth- 
 piece, angle 5°, the coefficient for the narrow end is -92, for the broad 
 end -55. 
 
 D. 
 
 Dahhirg On — Specially applied to the making of some forms of butt joints 
 (q.v ). Thus the spoke ends of railway wheels are dabbed on. 
 
 Damper. — A plate, valve, cover, or other suitable contrivance for regu- 
 lating the amount of draught in a boiler or furnace flue. 
 
 Damper Weight. — A weight used to counterbalance that of the damper 
 of a steam boiler in order to render it easy of adjustment. 
 
 Damping. — See "Watering. 
 
 Damping Down. — Slacking down (q.v.). 
 
 Damp Steam. — "Wet steam (q. v.) . 
 
 Dam Plate. — A cast-iron plate which forms the backing or support for 
 the dam stone (q.v.). 
 
 Dam Stone. — A stone occupying one side of the hearth of a blast furnace 
 over which the slag flows, and through which the molten metal is 
 tapped. 
 
 Dangerous Section. — That section of a bar at which the bending moment 
 (q.v.) is greatest. 
 
 Dash Piston. — The piston sliding in the dash pot (q.v.) of a Corliss 
 
MECHANICAL ENGINEERING. ro} 
 
 engine, Tvliose release ty a spring closes the steam or exhaust valves, 
 and whose concussion is deadened by the springs or buffers enclosed in 
 the dash pot. 
 
 Dash Flates, or Division Plates. — Plates sometimes fixed in a marine 
 boHer in line with, and over, the tubes, iu order to prevent the crown 
 plates of the fire-box from being exposed to the action of the flame 
 when the ship heels over heavily. But for these plates the water in. the 
 boiler woiild run to the lee side, and leave the plates temporarily 
 baje. 
 
 Dash Pot. — A smaU cylinder forming a portion of engines of the Corliss 
 and similar types, whose function is that of a buffer case to the sharp 
 closing of the steam and exhaust valves. It is furnished with 
 springs of steel or India rubber, which deaden the blow of the dash 
 piston (q.v.). 
 
 Datum Line. — Any base or fundamental line from which dimensions are 
 taken, or graphic calculations made. 
 
 Day Work. — ^Work done without any definite price being given for quan- 
 tity, the workmen being occupied only so many hours at it. Day work is 
 chiefly done iu pattern shops and iu foundries, and in the other depart- 
 ments on jobbing work, and work which wiH not admit of accurate 
 estimate of cost, or which is required of first-class excellence. But in 
 foundries and other shops where machine work is done, day work is not 
 the rule. See Piece "Work. 
 
 D-Bit. — A cylinder bit (q.v.). 
 
 Dead. — (1) A common term of emphasis, as dead level, deadsquare, dead 
 true, &e. (2) Molten metal is said to be dead when it pours thick, 
 sluggish, and viscid, due to insnfRcient melting, or to having remained 
 too long in the ladle. Dead metal is liable to produce cold shuts (q.v.), 
 though for heavy classes of work it must not be poured too hot. (3) 
 Timber is dead when the woody walls of the vessels become partially 
 decomposed, turning brown and friable. Alternate exposure to dryness 
 and moisture is the most fruitful source of dry-rot. 
 
 Dead Axle. — An axle which is not a driving axle (q.v.). 
 
 Dead Blow. — (1) A blow which is not of an elastic character. To strike 
 a dead blow the handle of the hammer must be grasped firmly. (2) 
 Indicates the nature of the blow given by those steam hammers in 
 which no steam is introduced between the piston and the cylinder end 
 for cushioning. See Elastic Blow. 
 
 Dead Centre Lathe. — ^A lathe whose front point centre does not revolve 
 with a mandrel, as is the case with ordinary lathes. The work alone is 
 revolved between dead centres. Dead centre lathes are only used for 
 work requiring such accuracy that the revolution of the mandrel 
 would be objectionable. 
 
 Dead Centres, or Dead Points. — (1) In a reciprocating engine or pump, 
 when the axis of the piston-rod, the crank shaft, and the crank pin are 
 all in line, the engine or pump is said to be on dead centres. Hence 
 an engine on dead centres cannot be started by the steam pressure 
 alone, but requires extraneous help to turn it partly round, and start it 
 on its rotation. In a double engine having cranks at right angles, if 
 one is on dead centres the other is in the best position for starting, so 
 that, practically, there can be no dead centres in the case of such an 
 engine. (2) The plain conical centres of the headstock and poppet 
 mandrels of a lathe. These centres are used when long cylindrical 
 worlf is being turned, the eniis being centre punched and slightly 
 
104 DICTIONARY OF TERMS USED IN 
 
 drilled to receive the centre points. The work is then revolved by a 
 carrier and driver. 
 
 Dead Eyes. — Bearings without any line of division or jointure, such as 
 exists in a plununer block ; the hole being bored through sohd metal. A. 
 dead eye answers the same purpose as a plummer block, but is capable 
 of no adjustment for wear, except by rebushing, and is consequently 
 used for rougher and more temporary kinds of work. 
 
 Bead Head. — (1) Head metal (q. v.). (2) The metal in the runner (q.v.) 
 of a mould. (3) The feeduig head (q-v.). (4) The poppet (q.v.) of a 
 lathe. 
 
 Dead Level. — Simply used iu the sense of being perfectly or quite level. 
 A term of emphasis. 
 
 Dead Load. — A load whose pressure is steady and invariable, neither 
 being removed, dimiaished, nor increased at any time. Structures 
 subject to a dead load undergo less stress than those on which the load 
 is variable (see Live Load) and therefore a lower factor of safety (q.v.) 
 suffices. 
 
 Dead Load Safety-valve, or Cowburn Valve. — A type of valve which is 
 loaded without the interposition of a lever or spring, the load consist- 
 ing of annular weights which are dropped over a cylindiioal seating. 
 The weight on the valve is iaoreased or diminished according to the 
 number of rings employed. 
 
 Dead Melting. — The perfect fusion of metal, obtained by allowing it to 
 remain in the furnace in the fluid state for some little time previous to 
 withdrawal, and so increasing its temperature some 200° or 300° above 
 the melting point. 
 
 Dead Parallel File.— See Parallel File. 
 
 Dead Plate. — The cast-iron plate immediately within the furnace door of 
 an engine boiler, which receives the fuel before it is passed onwards to 
 the grate surface. The function of the dead plate is the caking and 
 partial coking of the coal. 
 
 Dead Points. — See Dead Centres. 
 
 Dead Pouring. — The pouring of metal which has been allowed to 
 thicken or become dead (q.v.). It is adopted vrith the heavier castings. 
 
 Dead Size. — The exact or precise size or length, that is, exclusive of any 
 allowances for contingencies or for machining. A finished dimension, 
 or the opposite of a rough dimension. 
 
 Dead-smooth File. — The finest-cut file made. A 12-in. file of this descrip- 
 tion would contain 88 lines of teeth to the linear inch. 
 
 Dead Spindle. — The mandrel of the poppet (q.v.) of a lathe, as distin- 
 guished from the live spindle (q.v.). 
 
 Dead Water. — The water which lies below the heating surface in a 
 steam boiler, and where circulation is extremely sluggish. In Cornish 
 and Lancashire boilers the flues are brought forwards under the bottom 
 to heat the dead -water. 
 
 Dead-weight Safety Valve. — See Cowbum Valve. 
 
 Dead-weight Test. — A test to which rails, bars, and machinery are sub- 
 jected, the load being a dead load (q.v.). 
 
 Dead Wheel. — In an epicyclio train (q.v.) tho wheel around whose centre 
 the remainder of the train revolves is called the dead wheel. 
 
 Deal Frame. — A reciprocating or frame sawing-machine used for the 
 cutting of deals and boards. It is smaller than the similar frame saw 
 for cutting logs. The driving or feed rollers also revolve in a vertical 
 instead of in a horizontal axis. 
 
MECHANICAL ENGINEERING. 105 
 
 Seals. — Sawn pine timber measuring usually not less than 9x3 and not 
 more than 1 2 x 3 in cross section. Timber exceeding 11 in. in "vvidth 
 is often conventionally termed deals, but properly comes under the head 
 of planking. 
 
 Decagramme. — A !French measure of -weight containing 10 grammes 
 (q.T.), and equivalent to 154-34 English grains. 
 
 Decalitre. — A French measure of capacity containing 10 litres (q.v.), or 
 2-201 English gallons. 
 
 Decametre. — Ten French metres (q.v.), corresponding vrith 393-7079 Eng- 
 lish inches. 
 
 Decarburization. — The removal of carbon from combination with metals 
 in the processes of the manufacture of malleable iron in the puddling 
 furnace, and of steel in the Bessemer converter. (See Carbiu-ization.) 
 The decarburization of malleable iron castings is effected by the pre- 
 sence of a cementing material, as red hsematite iron ore. 
 
 Decigramme. — A French measure of weight, being the tenth part of a 
 gramme (q.v.), and containing 1-5434 English grains. 
 
 Decilitre. — A French measure of capacity, being one-tenth of a litre 
 (q.v.), and corresponding -with •1761 of an EngUsh pint. 
 
 Decimal. — See Fraction. 
 
 Decimal Equivalent. — A decimal nuniber, — integer and fraction com- 
 bined, or fraction alone, -which corresponds in value -with an integer and 
 vulgar fraction, or vulgar fraction alone. It is useful for facilitating 
 calculations invol-ving the assistance of fractions. 
 
 Decimal Gauge. — See Wire Gauges. 
 
 Decimal Pitches — Millimetre Pitches (q.v.). 
 
 Decinet."e — A French measure of length, being the tenth part of a 
 metre (q.v.), and equivalent to 3-93707 EngUsh inches. 
 
 Deck Crane. — A fixed crane used on board sMp. The central part of the 
 post is fixed tightly in a plate which is bolted to the deck, and its lower 
 end is dropped into a step or toe plate, fastened to a lower deck. The 
 gearing, side frames, and jib of the crane are made to slew around the 
 post. 
 
 Deck Winch. — A steam winch (q.v.) bolted to the deck of a ship for 
 hoisting or lowering goods from, or into the hold, and generally for 
 doing work whereby manual power can be saved. 
 
 Deep-well Pump. — A pump specially constructed for deep-well opera- 
 tions, the term ha-ving reference to the nature of the pump connections 
 — as strainers, retaining valves, &o. — rather than to any particular type 
 of pump. 
 
 Deflection. — The bending of a beam or structure under an applied load, 
 and which may be increased until the breaking strain is reached. The 
 deflection may be small in amount, and the beam or structure return to 
 its original form, or it may increase and accumulate, becoming perma- 
 nently set (q.v.), or it may go farther and lead to the crippling of the 
 beam. A slight amount of permanent set is not injurious, but crippling 
 is utterly ruinous. 
 
 Deflector. — This in a general sense denotes a bridge, or a bell, or trumpet- 
 mouthed opening, used for deflecting hot gases or liquids out of a 
 straight course, and having its applications in boiler conatruction. 
 
 Deformation. — The alteration in form which a structure undergoes when 
 subjected to the action of a load, the load producing either an elastic 
 strain (q.v.), or a permanent set (q.v.). 
 
 I eJi /er. — A term sig-nifying the manner in which a pattern leaves or lifts 
 
io6 DICTIONARY OF TERMS USED IN 
 
 from tlie sand. If the mould remains unbroken it is said to be a good 
 delivery, and the contrary when it tears the sand in the act of "with- 
 drawal. See Taper. 
 
 Delivery. — See Deliver. 
 
 Delivery Box. — The npper or delivery chamber of a series of two or three 
 throw pumps, into which the liquid is lifted by the pistons and from 
 which it is delivered. 
 
 Delivery Pipes. — The series of pipes through which the liquida drawn up 
 by pumping machinery are ejected. 
 
 Delivery Valve, or Discharge Valve. — The pump valve through which 
 the pump contents are ejected into the dehvery pipes. 
 
 Demy Drawing Paper. — The smallest size made in sheets, measuring 
 20 in. by \h\ in. 
 
 Density. — Density has reference to the amount of matter contained in a 
 body. Density and specific gravity are proportional. Specific density of 
 a body is its density estimated in relation to that of another body. 
 Platinum is the densest, hydrogen the rarest, element. 
 
 Deoxidation. — The removal of oxygen from metaUic oxides, effected 
 during the processes of calcination, smelting, puddUng, and converting, 
 the gaseous products being carbonic oxide and carbonic acid. 
 
 Dephosphorization. — The removal of phosphorus from combination with 
 iron and steel. In the blast furnace it is scarcely eliminated at all ; in 
 the puddling furnace it is removed by the basic materials used for 
 fettlmg, combined with exposure to the action of the air ; in the Besse- 
 mer converter by the basic Kning. 
 
 Dephosphorization Process. — The basic process (q.v.). 
 
 Deposit. — See Incrustation. 
 
 Depreciation. — The loss in value which machinery sustains with the lapse 
 of time, which amount has to be written off the prime cost annually. 
 The loss due to wear and tear is added to this. The total amount is 
 usually taken at 6 per cent, for engines, 10 for boilers, 8 for machines, 
 5 or 6 for mUlwork and gearing, 45 for belting. 
 
 Derrick. — A form of crane in which the radius of the jib is rendered 
 capable of alteration by means of chains or guys passing over the top 
 of the mast. Derrick cranes proper are fixed cranes (q.v.), but portable 
 cranes, both hand and steam, are provided with movable jibs, whose 
 mechanism for derricking is made in various types. 
 
 Derrick Chains, — The chains by which the jib of a derrick crane is raised 
 or lowered. They are wound and unwound off a barrel called the der- 
 rick barrel, the engine power being the motive power used. 
 
 Derrick Gear. — The arrangement of chains, barrel, and worm gearing by 
 which the jib of a derrick crane is raised and lowered. 
 
 Derricking. — The act of raising or lowering the jib of a derrick crane. 
 
 Design. — (1) The drawing out of a machine or stnicture. (2) The work- 
 ing out of mechanical ideas. The art of designing is not so original as 
 some would suppose, since few engineers dare to strilce out new and 
 untried paths. The study of new designs and the records of the Patent 
 OfB.ce show that a design is in most cases the utilisation of previous 
 experiences, and the application of old principles to new modiiicationa 
 in practice. 
 
 Desnlphurization. — The removal of sulphur from combination with iron 
 and steel. It is largely removed during the calcination of the ore ; 
 its elimination in the blast furnace depends on the nature of the flux. 
 With an excess of lime a portion of the sulphur unites with the slag ; 
 
MECHANICAL ENGINEERING. 107 
 
 if silica be largely present, the sulphur, instead of uniting with the 
 lime, -will remain in the pig. A high temperature is also favourable 
 to the elimination of sulphur, so that the grey irons which are produced 
 at a higher temperature than the white irons contain less sulphur than 
 the latter. In the puddling furnace sulphur is removed by the oxygen 
 in the fettling, in the Bessemer converter by the oxygen in the air 
 which is blown through. 
 
 Detail Drawing. — One which is not a general drawing (q.v.), but em- 
 braces some portion or section only of a maoMne. 
 
 Determinable Quantity. — ^A quantity whose value or amount can he 
 determined or fixed from other quantities already known. Thus, the 
 temperature and pressure of any given vapour being known, its volume 
 can be determined, and is therefore a determinate quantity. 
 
 Detruding Action. — When a hole is punched in a plate the action is that 
 of detrusion, and the plate is strained more than if the hole were 
 drilled. 
 
 Development. — (1) A drawing is said to be developed when certain 
 working details are drawn in full. Thus a propeller blade is developed 
 when the various transverse sections are shown ; the section of a turbine 
 is developed when the curves of the vanes are fully drawn ; a plate or 
 templet is developed when it is so marked out that if cut to the 
 developed lines and then bent, it will form the envelope of some 
 definite geometrical figure, as a frustrum of a cone, a segment of a 
 sphere, the knee of a pipe, &e. (2) Iron or steel nicked and bent sud- 
 denly shows a crystalline fracture, but when bent slowly the fracture 
 is of a fibrous character. This latter mode of fracture is termed its 
 development, and the fibres are said to be developed, or drawn out. 
 
 Deyil. — A light iron lattice-work frame, either circular or rectangular in 
 outline, filled with burning charcoal, and used in foundries for diying 
 the surfaces of green sand moulds. It is either suspended in the mould, 
 or laid upon iron rods placed over it. 
 
 Diagonal. — A straight line joining opposite angles in a triangular, 
 quadrangular, or polygonal figure. 
 
 Diagonals. — Bracings placed at an angle across rectangular framings, to 
 prevent alteration taking place in the shape of the frames. Hence 
 the braces, or struts and ties of a lattice girder, are its diagonals. 
 
 Diagonal Scale. — A scale used for drawing purposes, which has, in addi- 
 tion to the primary divisions, one or both end divisions corresponding 
 in length with the primary ones, divided into ten equal parts. Eleven 
 equidistant and parallel lines are also drawn in a longitudinal direc- 
 tion, and diagonals drawn from the tenth division on one outer longi- 
 tudinal to the ninth on the other, and so on in succession. With this 
 scale one hundredth-parts of the primary divisions can be taken off. 
 
 Diagonal Stays. — Stays used for stiff ening the end plates of steam boilers, 
 in preference to, or to assist, the longitudinal stays. They reach from 
 the inner face of the plate to that of the shell, in a diagonal direction. 
 
 Diagonal Winch. — A steam winch whose cylinders are placed diagonally 
 on the side frames. 
 
 Diagram. — An outline drawing, or graphic construction, made for the 
 purpose of illustrating or elucidating some problem in mechanical or 
 aritbmetioal study. 
 
 Diagram of Work. — It is customary to estimate the work done on a body 
 by, a graphic method. A parallelogram is constructed and a curve 
 tTieloeed therein represents the ratio between pressures and volumes, 
 
io8 DICTIONARY OF TERMS USED IN\ 
 
 The parallelogram is divided by crossed lines perpendicular to each 
 other, termed respeotiyely lines of pressure and lines of volume. 
 
 Dial Gauge. — A dial having an index hand actuated by, a bent spring, 
 through which the amount of pressure in a boiler, or of/the vacuum in 
 a condenser, is indicated, the dial being graduated accordingly. All 
 gauges of this kind are made on Bourdon's spring principle. 
 
 Diameter. — The diameter of a circle is a line passing th^iough its centre, 
 and uniting the circumference or sides. ' 
 
 Diametral Pitch. — A mode of expressing the pitch of toothed wheels in 
 terms of their diameter. It is obtained by dividing the number of teeth 
 by the pitch diameter. Thus the diametral pitch of a wheel 6 in. 
 in diameter, and containing 48 teeth, would be 8. Conversely, the 
 diametral pitch being given, the number of teeth divided by the pitch 
 gives the diameter at the pitch line. It is the rule to give the sizes of 
 change wheels for lathes in diametral pitch. See App. 
 
 Diamond Point. — (1) A pointed tool used by pattern makers for turning 
 the inner faces of work which, owing to their obliquity, or to their 
 being bounded by cylindrical walls, could not be reached by ordinary 
 chisels. The cutting edges of a diamond-pointed tool will stand at an 
 angle of from 20° to iO" with the body, both edges being ground sym- 
 m.etrically, so that in plan they form the shape of a letter y. (2) A 
 naiTower tool but of similar shape is used by metal turners. (3) A tool 
 in which the cutting angles are more obtuse is used by fitters and 
 boiler makers for the purpose of cutting holes in boilers and other thin 
 plates, and for nicking round pipes and tubes which have to be 
 broken off. 
 
 Diaphragm. — A built-up distance piece of plate and angle-iron which 
 unites two parallel girders together. 
 
 Die. — (1) A female or internal screw used for cutting outside screw 
 threads. It is made of hardened steel, and fluted, to present two, 
 three, or four separate cutting edges. The larger dies or those above 
 \ in. in diameter, are made in halves and set in a die stock. The 
 smaller dies are cut in a screw plate. Also termed screw dies, or 
 screwing dies. (2) The movable block embraced by a slot link (q.v.). 
 (3) An iron or steel mould used by smiths for the forging of eyes, 
 bosses, tie-rod ends, truss-rod ends, &c. The die or matrix may be 
 in one piece only, or it may comprise an upper and a lower portion, 
 planed or checked together. The tvork is generally moulded in the 
 dies under a steam or drop hammer. 
 
 Die Box. — The box of a screwing jmachine by which the dies are 
 embraced. s 
 
 Die Chuck. — A lathe chuck fumished;;with steel Jaws or dies sliding in 
 grooves, and pinched or slackened |with screws. The pinching jaws 
 are Veed or bevelled, and one or afll the jaws may be moved in some 
 chucks at pleasure, so that work (^an be chucked either centrally or 
 eccentrically. Die chucks are also, self- centring, and usually contain 
 two or three dies. 
 
 Die Forging. — The practice of forging repetition work in dies. See App. 
 
 Die Stock, or Screw Stock. — The fralae which encloses the dies used for 
 screw cutting. It is furnished with lever handles for turning it in the 
 circular direction, and with a set-screw for regulating the distance 
 between the halves of the dies. Die stocks are made in various and 
 well-known forms. 
 
 Difference G^uge. — A cylindrical ga^ige (q.v.) is sometimes furnished 
 
MkCtlANtCAL ENGINEERING. 105 
 
 "with t*o plug gauges to one collar gauge, one of the plugs heing 
 sKghtly larger in diameter than the other ; the difference between the 
 two being just that -which is sufficient to permit of easy movement, or 
 of tight fitting of a mandrel in a cylinder. 
 
 Differential Motion The motion of one part to or from another, the 
 
 two parts forming a mechanical combination. It is a motion whereby 
 mechanical gain is obtained. The Chinese windlass, where two axles 
 of unequal size move together, embodies the differential principle. 
 
 Differential Pulley Block. — A pulley block which owes its efficiency to 
 the ^ght difference in the sizes of two sheaves fixed together on one 
 axis. An endless chain embraces the two sheaves and a movable pulley 
 below. The mechanical gain is proportional to the diiference in the 
 diameters of the two sheaves. A most valuable property of this pulley 
 block is that, owing to the excessive amount of friction set up, the load 
 cannot nm down, but remains stationary in any position in which it 
 happens to be left suspended. 
 
 Differential Screw. — Two screws of unequal pitch cut on the same spindie. 
 On turning the spindle a nut on one of the screws moves by an amount 
 equal to the difference in the pitches. 
 
 Differential Strains. — The strains due to a variable load. 
 
 Digger. — A term sometimes applied to a grab (q-v.) used for excavations. 
 
 Digging Shovel. — A round-mouthed or pointed-end shovel used in foun- 
 dries for digging the sand in the floor. The square-ended and crutch- 
 handled shovels are used for box fiUing and sand wetting. 
 
 Dimension, — A definite measurement shown on a mechanical drawing, as 
 length, width, thickness. Dimensions are given on all working draw- 
 ing's, whether drawn to scale or not, but dimensions are not inserted in 
 shaded and general drawings. 
 
 Dimension Lines. — Those lines upon an engineer's drawing which indi- 
 cate to what parts or lines the dimensions figured have reference. They 
 are never drawn in black, but usually in blue, sometimes in red ink. 
 
 Dimension Saws. — Applied to a couple of circular saws mounted radially 
 from a common spindle, one for cross cutting, the other for ripping. 
 The saws are moved upwards or downwards as required with a worm 
 and worm-wheel. 
 
 Diminishing Socket. — A wrought-iron socket inserted between, and con- 
 necting two pipes of different bores. 
 
 Dinas Brick. — A refractory brick made from a highly sUiceous clay found 
 in the Vale of Neath, and used for the roofs of reverberatory furnaces. 
 
 Dip. — The amount by which the upper edge of a paddle-wheel blade is 
 immersed beneath the surface of the water when the blade is in the 
 vertical position. 
 
 Dip Crank Shaft. — A crank shaft in which the crank is formed by the 
 simple bending of the bar, instead of being slotted out of the soUd. It 
 is stronger than the slotted form because of the continuity of the fibres. 
 
 Direct Acting. — An engine is said to be direct acting when the action of 
 the piston is transmitted directly to the crank shaft. Nearly all engines 
 are therefore direct acting. 
 
 Direct-acting Slide Valve. — A slide valve whose length of travel is the 
 same in amount as that of the throw of the eccentric, as opposed to the 
 indirect-acting slide valve (q.v.). 
 
 Direction of Force. — The Hne along which a force acts, whether it be 
 productive of actual motion or of pressures or tensions only. Forces 
 are assumed to act in straight lines only. 
 
116 DiCTIONARY OF TERMS USED IN 
 
 Direct Process. — (1) The method of producing malleable iron direct' from 
 the ores ■srithout prelimiuary smelting into pigs. (2) The proceea of 
 making steel in the Bessemer converter by bringing the ii'on direct 
 from the smelting furnace. 
 
 Disc Area. — See Screw Area. 
 
 Disc Crank, or Crank Disc, or Crank Plate, — A crank of circular outiline 
 in which the metal is so disposed that the varying motion of the con- 
 necting-rod is suitably balanced. The crank shaft is keyed into a boss 
 in the centre of the disc, and the crank pin is riveted into a hole near 
 the periphery. The half of the disc upon the side opposite to the crank 
 pin is thickened up to act as a counterbalance to the rod. Its action 
 is more regular therefore than that of a common crank. 
 
 Discharge. — The liquid ejected from a pump or from the vanes of a 
 turbine (q.v.). See Vena Contracta, Cylindrical Mouthpiece, Nozzle. 
 
 Discharge Valve. — (1) A delivery valve (q.v.) (2) A self-acting valve 
 attached to the side of a steamer, through which the water is discharged 
 from the circulating pump, hence called side discharge valve. 
 
 Discharging Tube. — An adjutage (q.v.). 
 
 Disconnecting Engine. — A double engine, usually of the compound typ^ 
 in which the cylinders can either be used in combination, or each 
 separately from the other. 
 
 Disc Valve. — A modification of the flap valve (qv.) used extensively in 
 large pumps, andof which the air pump of a condensing engine furnishes 
 a fanuliar type. It consists of an india-rubber disc hinged at tho 
 centre, resting on a perforated grid, through which the water obtains 
 ingress, and lifts the valve. The disc is prevented from lifting too high 
 by a superimposed perforated guard-plate dished or hollowed in the 
 upward direction. 
 
 Disc Wheel. — A wheel having its central portion solid or plated instead 
 of being provided with arms. The disc may be fiat as in change 
 wheels, and the lighter classes of toothed wheels generally, or it maybe 
 dished as in the wheels of tracks and trollies. The latter form ia 
 strong, because it will accommodate itself to the expansion and con- 
 traction due to changes in temperature, or to internal and to external 
 stresses. 
 
 Disengaging Clutch. — A clutch whose function is the throwing of a line 
 of shafting, or a train of wheels, into and out of gear. 
 
 Disengaging Coupling. — A chitch (q.v.). 
 
 Disengaging Gear. — The mechanism used for throwing clutches into and 
 out of gear. It is usually either a lever or a hand wheel and screw. 
 
 Disengaging Nut. — The clasp nut of a lathe, being disengaged when 
 not required for use or for screw cutting. 
 
 Dishing. — The hollowing and rounding of the surface of a disc, to render 
 it more elastic or stronger. 
 
 Displacement. — The quantity of liquid discharged from a plunger pump 
 at each double stroke is equal to the amount displaced by the plunger. 
 
 Displacement Cylinder. — An auxiliary cylinder belonging to some gas 
 engines, by which the constituents of the charge are forced into the 
 working or power cylinder. 
 
 Displacement Lubricator. — A lubricator which acts by the diEBerence ia 
 the sp. gr. of oil and of water. An impermeator (q.v.) is one form of 
 displacement lubricator. 
 
 Displacer Piston. — ^An auxiliary piston in some gas engines whose 
 function is the expelUng of the residual gases or products of combustion 
 
MECHANICAL ENGINEERING. ill 
 
 from the cylinder. lu other cases a flushing charge (q.v.) is used for 
 the same object. 
 
 Distance Piece. — Any casting whose chief or only function is to maititaia 
 engine or machine parts at a fixed distance asunder. 
 
 Distress. — A beam or structure is iu distress when it is subjected to undue 
 or excessive stress, or to an amount exceeding the working stress. 
 
 Distributed Load. — When a load is spread evenly over the whole extent 
 of surface of a beam or structure it is termed a distributed load. A 
 girder will sustain a distributed load of twice the total weight which it 
 would sustain if concentrated. See Concentrated Load. 
 
 Diverging Mouthpiece. — A mouthpiece for the discharge of liquid, whose 
 longitudinal section is that of the frustrum of a cone, the smaller 
 diameter being placed next its tank. See Cylindrical Mouthpiece. 
 
 Divided Axial Pitch. — In multiple threaded screws the axial pitch (q.v.) 
 is divided into as many portions as there are threads, and the distance 
 between any of these divisions is called the divided axial pitch, that is, 
 where the centre of each successive helix cuts the axial line. 
 
 Divided Bearing. — Any bearing which is not solid, and which contains, 
 therefore, provision for adjustment for wear. Bearings are commonly 
 divided into two portions, but in some special cases into three. 
 
 Divided Normal Pitch. — The distances between the centres of the suc- 
 cessive helices of many-threaded screws, measured perpendicularly to 
 the threads. It is, therefore, less than the divided axial pitch (q.v.). 
 
 Divided Steam Chest, — A steam chest divided, either through the centre 
 of the stuf&ng-box parallel with the cylinder bore, or obliquely, that is, 
 at an angle with the bore. The object of dividing is for convenience 
 of removing the cover for examination and repairs, without the neces- 
 sity of removing the valve and valve rod — the rod in the first case 
 passing through the joint of the divided box ; in the second, through 
 the box, which is cast whoUy with the cylinder. 
 
 Dividers. — A form of compass used for taking off or setting out minute 
 and exact dimensions, being suited for more delicate adjustment than 
 common compasses. These are of various kinds, and employed both in 
 the drawing-of&ce and in the workshops. See Spring Dividers. 
 
 Dividing Engine. — A machine, constructed in various forms, for the 
 exact marking off of degrees, points of equal division, wheel teeth, &c. 
 
 Division Peg. — ^A peg of hardened steel, attached to an elastic rod called 
 the index spring, and used in conjunction with a division plate (q.v.). 
 The peg fits into any of the holes drilled in the plate, and holds it in 
 steadily while operations of drilling or shaping are being performed. 
 
 Division Plate. — (1) A plate of brass fastened to the front of the driving 
 pulley of a lathe headstock. It is pierced with numerous concentric 
 circles of holes ; those in the best and most complete lathes numbering 
 360, 192, 144, 120, U2, 96, 60, 12. By means of these almost any 
 number of divisions that are required can be obtained. A division 
 peg (q.v.) sets the pulley in any position, while the work in the lathe 
 is being operated upon by drills or cutters set in the cutter frame and 
 driven from overhead gear. (2) The plate of a wheel-moulding, or of 
 a wheel-cutting machine, through which the handle shaft passes, and 
 which is notched for setting the handle at quarter, half, three-quarter, 
 or full turns. See also Dash Plate. 
 
 Division Plate Wheel. — The change wheel on the handle shaft of a wheel- 
 moulding or of a wheel-cutting machine. 
 
 Dog. — (1) One of the jaws or chps of a jaw chuck (q.v.). (2) The carrier 
 
112 DICTIOMAkY OF TERMS USED IN 
 
 (q.v.) of a latte. (3) The catch which prevents the -winch shaft of a 
 crane from sliding along when the gears are changed. Called also 
 Catch Paul. (4) A spike (q.v.). 
 
 Dog Chuck. — See Jaw Chuck. 
 
 Bogtail Trowel. — A small heart-shaped moulders' trowel, provided with 
 a curved metal handle, the handle being imagined to resemble a 
 dog's taQ. 
 
 Dog Wheel See Ratchet "Wieel. 
 
 Dog Wrench. — A form of spanner whose handle is turned around simi- 
 larlj to a winch handle. 
 
 Dolly. — A tool used by boUer-makers for holding under the heads of rivets 
 during the act of riveting. It consists of a round iron bar, furnished 
 with a head, flat or cup-shaped ; the size, shape, and angle of inclina- 
 tion of the bar varying with the size and shape of the rivets, and their 
 position relatively to the work. It is used for the same purpose as the 
 holdiag-up hammer (q.v.). 
 
 Dolomite. — Magnesian limestone (q.v.). 
 
 Dome. — See Steam Dome. 
 
 Dome Cover. — The brass covering which encases the steam dome of a loco- 
 motive. 
 
 Donkey. — A donkey-engine (q.v.). 
 
 Donkey-Boiler. — A small boiler, usually of the vertical type, used for 
 driving small engines. 
 
 Donkey-Engine. — An auxiliary engine used on board ship for pumping, 
 or other light work, independently of the main engines. 
 
 Donkey-Pump. — The independent feed pump of a steam boiler driven 
 directly by a small engine, the whole being attached to a single base- 
 plate which is bolted to the boUer. 
 
 Douhle-Acting Engine. — An engine ia which the steam acts upon both 
 sides of the piston alternately, either against atmospheric pressure, or 
 against a vacuum produced by condensation. All engines are now 
 made double-acting, just as formerly all were made single-acting. 
 
 Double-Acting Piston. — A piston acted upon by gaseous or fluid pressure 
 on both sides alternately. The pistons of engine cylinders and of 
 double-acting pumps are of this type. 
 
 Double-Acting Steam Hammer. — A steam hammer which admits steam 
 above the piston as well as below. 
 
 Double-Action. — Double action is in pr'nciple that of an alternate re- 
 ciprocal pressure or movement. A series of actions equal and alter- 
 nate in opposite directions. 
 
 Double-Action Pump. — One which throws water at each stroke, as dis- 
 tinguished from a lift pump. 
 
 Double-Armed Iull3y. — A puUey which has two sets of arms. Pulleys 
 over ten or twelve inches in width have commonly a double set of arms. 
 They are set parallel with each other at a little- distance within the 
 outer edges of the rim which they support, and the boss may either be 
 continuous between the arms, or a clear space may exist between the 
 bosses of each set. 
 
 Double-beat Valve. — A ring-shnped lift valve ha-ring two seating faces, 
 by which the steam is admitted on both sides at once, hence called an 
 equilibrium valve. In our ordinary slide steam valve the steam pressure 
 is unequal, because the area on the steam chest side is greater than the 
 area open to the port side, and this pressure has to be overcome before 
 the valve can be moved. The double beat being in equilibrium is mora 
 
MECHANICAL ENGINEERING. 113 
 
 easily moved. It is also termed a Cornish valve, beoanse used exten- 
 sively in the large pumping engines of that district. 
 
 Double Belting. — Bolting formed of two thicknesses of leather. It varies 
 from J to J an inch in thickness, and is employed for heavy driving, as 
 for main driving pulleys, and the more powerful class of machines. It 
 is made by cementing two thicknesses of leather together, and then 
 sewing or riveting. 
 
 Double Bogie Engine. — See Bogie Engine. 
 
 Double Butt Strips. — ^Two covering strips employed in making a butt 
 riveted joint, one strip being placed on each side of the abutting plates. 
 These are much stronger than the joints with single butt strips (q.v.). 
 
 Double Cards, — Indicator cards taken from both ends of an engine cylmder. 
 
 Double Contraction, or Double Shrinkage, — Where a wood pattern is made 
 for the casting of a metal pattern, from which the actual mould is to 
 be taken, two amounts of contraction are allowed on the wood pattern. 
 Thus if the contraction of the casting is \ in. per foot, \ in. per foot is 
 allowed in the first or wood pattern. 
 
 Doable Cut. — This refers to the crossing of the lines of teeth of files at an 
 angle, as distinguished from the single or float-out files. 
 
 Double-cutting Drill . — A drill which is ground to cut with equal f acUity in 
 a right or left-hand direction. The cutting edge Hes therefore in the 
 longitudinal axis and the angles are symmetrical on both sides. These 
 drills form but a small class. 
 
 Double-cylinder Engine. — A steam engine having two cylinders. Its 
 action is steadier than that of a single-acting engine owing to the 
 relative arrangement of the pistons and cranks. One piston is at half, 
 while the other is at full stroke, and the cranks being therefore at 
 right angles with each other, the dead points are passed with little of 
 the jerky motion which accompanies the revolution of a single-cylinder 
 engine. 
 
 Double Driver Chuck, — A driver chuck which has two stems or pins for 
 driving, so that the pressure of one is counterbalanced by that of the 
 other. It is used for work requiring special accuracy. 
 
 Double Disc Valve. — A tapered plug valve having two faces fitting 
 against two opposite seatings. 
 
 Double Elephant, — A drawing paper of good quality measuring 40 in. by 
 27 in. It may be had rough or smooth, and either unmounted, or 
 mounted on brown holland. 
 
 Double-ended Boiler. — A marine boiler having furnaces and flue doors 
 at each end, and fired therefore from each end. 
 
 Double-ended Bolt. — A bolt having no solid head, being screwed at each 
 end alike for the reception of nuts. 
 
 Double-ended Hachine. — Applied to those punching and shearing 
 machines in which two sets of operations can be carried on at one time. 
 
 Double-faced Hammer. — A hammer is double faced when both sides of 
 the head are ahke flatted, so that there is no pane. 
 
 Double Fagoted. — Iron which has been subjected twice ever to the 
 process of fagoting (q.v.) for the purpose of increasing its density, 
 homogeneity, and tensile strength. 
 
 Double-flshed Joint, — A fished joint having two fish plates, or covering 
 strips laid against opposite faces, as distinguished from a single- 
 fished joint (q.v.). 
 
 Double-flued Boiler. — See Lancashire Boiler. 
 
 Double Gear, — The employment of two pinions and two wheels in com- 
 
 I 
 
114 DICTIONARY OF TERMS USED IN 
 
 bination for the purpose of gaining meclianical efficiency, as in the 
 lifting gear of cranes. Back gear (q.v.) is often termed double gear. 
 See Double Geared. 
 
 Double Geared. — A lathe or drilling machine is said to be double geared 
 when it is prorided with the ordinary back gear ; that is having a 
 single back gear spindle and set of wheels only, as opposed to an un- 
 geared or plain haud-tuming lathe on the one hand, and to a treble- 
 geared lathe on the other. Double geared does not mean that double 
 power is garaed thereby, since the power gained is usually about nine 
 to one, but refers only to the employment of the second spindle and 
 wheels. The term double geared is also applied to drilling machines 
 haTing back gear not of the ordinary form, but wheels which can be 
 slid up and down on a vertical spindle into, or out of gear with the 
 wheels on the main spindle. 
 
 Double-handed Tool. — A tool furnished with two handles, as ordinary 
 die stocks and cross cut saws. 
 
 Double-headed Kail. — A rail for permanent way, the shapes of whose 
 top and bottom sections are alike, so that when one face becomes worn 
 the rail is turned over in the chair and the opposite edge utilised. 
 
 Double-helical Gear. — See Helical Gear. 
 
 Double-ported Slide Valve. — An exhaust relief, or equilibrium valve. 
 It is designed for nearly equal steam pressure on both sides and to give 
 a greater area of opening to exhaust than to supply, and this is 
 efieoted by allowing steam to enter the cylinder through passages in 
 the pierced body of the valve as well as at the ends, and to exhaust 
 into the hollow, or D> of the valve which contains the ports through 
 which the steam gains entry. Having separate ports for supply and 
 exhaust, it is obvious that by giving to the latter an increase of area 
 over that of the former, and by adjusting the travel, the escaping steam 
 will be allowed greater freedom of exit. Having double openings 
 for steam, the cylinder is necessarily double ported, that is, there 
 are two ports on each side of the exhaust instead of one, and the travel 
 of the valve is only half that which it would be with single ports. 
 
 Double Puddling Furnace. — See Puddling Furnace. 
 
 Double Purchase. — A term used to designate the mechanical efficiency 
 obtained by the employment of double gear (q.v,). It is equal to the 
 product of the radii of the wheels divided by that of the pinions. 
 
 Double Reading Scale. — A draughtsman's scale on which there are two 
 primary divisions, one at each end, subdivided. 
 
 Doable Riveting. — Where there are two lines of rivets in a lap joint, or 
 four in a butt joint, the term double riveting is employed, as distin- 
 guished from a single line in the former and two lines in the latter. 
 
 Doubles. — Sheet iron plates prepared for tinning. Their thickness 
 ranges betweenNo. 20, B.W.G. (-035 in.) to No. 25, B.W.G. (-020 in.). 
 The term is also applied to the plates already tinned, to which an extra 
 thick coating has been given, and which, besides, have been hammered 
 between a polished hammer and a polished anvil to render the union of 
 the metals more intimate. Also termed Block Plates. 
 
 Double Shaper. — A shaping machine having two rams and two tool boxes, 
 for a double set of operations. Sometimes one head is made for straight 
 cutting only, the other for circular cutting. 
 
 Double Shear. — Arivet which unites a joint made with double fish-plates 
 will have two sections subject to shearing strain ; hence the term. See 
 Single Shear. 
 
MECHANICAL ENGINEERING. 115 
 
 DouWe Shear Steel. — Shear steel (q.v.), in -which the process of ■welding' is 
 repeated by reheating the bars, doubhng them up, and -welding them 
 together once more. 
 
 Double Shrinkage. — See Double Contraction. 
 
 Double Stroke. — Two piston strokes, or one forward and one backward. 
 A term used in calculations relating to the po-wer of steam engines. 
 
 Double-threaded Screw. — A screw- comprising two distinct helioes, 
 -winding parallel -with each other around the body. Employed to giTS 
 an increase in the rate of travel. 
 
 Double Valve Box. — A valve, or clack box, provided -with two valves 
 only. Having no intermediate valve (see Treble Clack Box) the stream 
 delivered is intermittent. 
 
 Double-webbed Girder. — A box girder (q.v.), having two webs or plates 
 connecting the top and bottom flanges. 
 
 Double-welt Joint. — A double-fished joint (q.v.). 
 
 Dovetail. — An interlocking joint used for wood-work, so called from the 
 fancied resemblance which the pin bears to the tail of a dove. 
 
 Dovetailing Machines. — Those used in the cutting of dovetaUa. They 
 are of two types, according as the cuts are made by spindles or by 
 saws. In the former a revolving bit cuts away the wood, in the latter 
 it is removed by a circular saw set at an angle while the work is being 
 passed before it through a measured distance. 
 
 Dowels. — ^Pins either of wood or metal used by pattern-makers to retain 
 portions of patterns temporarily in position during the process of 
 moulding, which portions, if firmly nailed or screwed, would prevent 
 good delivery from the sand. Dowels are now mostly made of metal, 
 either malleable iron or brass, the better sort being cast attached to flat 
 plates, which are recessed into the pattern joints flush with their sur- 
 faces, and there screwed. 
 
 Down. — See Running Do-wn. \ 
 
 Do-wn-comer, or Down-take. — The vertical pipe which conducts the 
 waste gases from the top of a close-mouthed blast furnace into the 
 blast main. 
 
 Down-take. — (1) The short passage leading from the back end of the fire 
 flue of a Cornish boiler to the brickwork or smoke flues which pass to 
 the front of the boiler. (2) A do-wn-oomer (q. v.) . 
 
 Downward-flow Turbine. — See Turbine. 
 
 Draft. — A drawing. Dra-wing is often termed drafting. 
 
 Drag. — ^The bottom part or section of a founder's moulding box. 
 
 Drag Bar. — The rod by which a locomotive and its tender, or railway 
 wagons, are coupled together. 
 
 Drag Bolt. — The bolt which couples up drag bars. 
 
 Drag Hook. — The hook attached to back and front of locomotives and 
 railway wagons for couphnar up. 
 
 Drag Link. — (1) A link employed for connecting or disconnecting the 
 cranks of coupled engines. (2) The rods by which the slot links of 
 valve gears are moved over for forward or backward gear are called 
 drag links. 
 
 Drag Plate. — The casting which forms the footplate or platform of a 
 locomotive. It is bolted between the frames, and carries the drag bar 
 and other attachments. Iti s made heavy to equalise the weight on 
 the wheels, averaging about three tons. 
 
 Drag Hope. — A rope used for the purpose of pulUng logs of timber up to 
 a circular saw. It is coiled around a drum which is driven through 
 
ii6 DICTIONARY OF TERMS USED IN 
 
 intermediate gearing from a pulley on the saw spindle, by ■srHch means 
 the speed of the rope is reduced with a corresponding increase of power. 
 
 Drag Spring. — A spring attached to a drag bar (ct.T.) to lessen the shock 
 of concussion. 
 
 Drag Surface. — The forward face of a screw propeller, or that from which 
 the water glides off. 
 
 Drain Cock. — A pet cock (q.v.). 
 
 Drain Pipe. — A small copper or brass pipe leading from the pet cock of 
 an engine cylinder. The drain pipes are led away to any convenient 
 spot for discharging the water of condensation. On board ship they 
 are led into the bUge or the hot well. 
 
 Draught. — (1) The tapering or gradual thinning down of the vertical 
 sides of foundry patterns, to permit of their deUvery from the sand. 
 (2) The quantity of air which passes through a furnace in a given 
 time is termed its draught. Natural draught is that produced by the 
 exhaustion of air from the furnace and the creation of a partial vacuum 
 therein. This is attained by the rapid ascent of the highly heated 
 gases. Forced draught is that produced by the iniection of a jet of 
 st«am into the chimney, which hastens the escape of the gaseous pro- 
 ducts of combustion. In draught by compressed air the pressure is 
 produced by various forms of fans and blowers. 
 
 Draught Bar. — A drag bar (q.v.). 
 
 Draughtsman. — The engineer upon whom the task of designing machin- 
 ery, and of making both general and working drawings, devolves. A 
 draughtsman, to be practical, must have an intimate knowledge of the 
 conditions of work in the several departments of the factory, and should 
 be able to combiae with this the best theories and fair mathematical 
 acquirements. A designer, and a copyist or tracer, though both alike 
 called draughtsmen, stand on very different footings, the first being 
 a true engineer, the second being rated below an ordinary mechanic. 
 
 Drawback. — A plate or a skeleton framework of cast and wrought iron, 
 used for carrying some portion of a founder's mould, which has to be 
 temporarily removed, either for the proper withdrawal of the pattern 
 or for the convenience of the cleaning up of the mould faces. The plate 
 with its contained sand is lifted or drawn back, and afterwards replaced 
 in its original position, in readiness for casting. 
 
 Draw Bar. — See Drag Bar. 
 
 Draw Bench. — The bench used by wire drawers. 
 
 Draw Cock. — ^A pet cock (q.v.). 
 
 Draw Filing. — The polishing of a metallic surface by drawing a smooth 
 file along it ; the file moving to and fro in a direction transversely to 
 its own longitudinal axis, so that the cutting action of the teeth scarcely 
 comes into play. Also called poker filing. 
 
 Draw Hook. — The central hook of a railway wagon attached to the da'aw 
 bar, and flanked by side hooks. 
 
 Drawing. — (1) The delineation of machinery and machine parts in 
 plans, elevations, and sections to proportional scales. In these there 
 can be no perspective, hence they are conventional drawings only, and 
 do not represent truly correct views to a spectator standing in any fixed 
 position. But for convenience of measurement, such scaled drawings 
 are the only ones which are of use in the workshops. (See Phototype, 
 Hand Sketch, Tracing.) (2) The manufacture of mre, piping, and 
 tubing, by pulling or ctawing the material of which they are composed 
 through perforated plates. 
 
MECHANICAL ENGINEESINCP, it? 
 
 Drawing Soard. — Jl) A board used in the drawing office for pioning 
 down or stretoMng drawing paper upon. The cheaper hoards are 
 clamped at the two ends only ; the better ones are panelled, or enclosed 
 in an entire frame. Grood boards should be tongued in addition, and 
 those of the largest size should have adjustable joints to permit of the 
 expansion and contraction of the wood. Pine and mahogany are the 
 materials used for drawing boards. Their dimensions are given simi- 
 larly to those of the various drawing papers, but a little extension in 
 size is made. (2) The workshop boards, on which portions of 
 mechanism are drawn to full size, are mostly of large dimensions, 
 several feet square, and the pencil drawings are made directly upon 
 the boards themselves, whose surfaces are whitened with chalk to show 
 up the lines. 
 
 Drawing Down. — The reducing or thinning down of forged work under 
 the hammer ; hammers, fullers, and flatters, being employed for the 
 purpose. Wien drawing down, the dimensions of the cross section 
 may be diminished all around alike, or be diminished in one direction 
 and increased in the other. 
 
 Drawing Fires. — The raking out of the furnace fires of an engine boiler. 
 
 Drawing In. — A cutting tool is said to draw in when it cuts deeper than 
 it should do. This is due to malformation of the same kind as that which 
 produces a hitch or catch. See Hitch. 
 
 Drawing of Castings, — The setting up of internal molecular stresses in 
 castings, due to bad proportioning, or to unequal cooling, or to both in 
 combination, the tension being variable in adjacent sections. See 
 Cooling, Feeding, &c. 
 
 Drawing Office. — The office or department of an engineer's factory in 
 which the work of the draughtsman is carried on. It is furnished 
 with sloping desks, stools, boards, paper, &o., and with nests of 
 drawers for the storage of the drawings. 
 
 Drawing of Patterns, — The lifting (q.v.) of foundry patterns from the 
 sand. See also Rapping, Delivery, &c. 
 
 Drawing of Temper. — The heating of a steel article to redness, and 
 allowing it to cool slowly in air. This is the reverse of hardening or 
 tempering. 
 
 Drawing of Tubes. — See Tube Drawing. 
 
 Drawing Paper. — This comprises several varieties, their qualities increas- 
 ing in the following order : Cartridge, Imperial, Double Elephant, Anti- 
 quarian, and Emperor; and their dimensions as follows : Demy, Medium, 
 Royal, Super-royal, Elephant, Imperial, Columbier, Atlas, Double 
 Elephant, Antiquarian. See sizes under those headings. Paper is 
 either hot pressed, or not pressed at all, or else is rough ; the latter 
 being for general or ordinary drawing, the first for pencil drawing, 
 and the medium quaUty for common work. 
 
 Drawing Pen. — A pen formed of two blades of steel, approaching at the 
 points, and adjustable with a milled-headed screw, the ink being 
 enclosed between the blades. Used for marking ink lines of uniform 
 width upon drawings. Two suih pens mounted side by side for draw- 
 ing distinct but parallel lines form what is called a road pen. 
 
 Drawing Pins. — Short, broad-headed pins, used for holdiug down both 
 drawing and tracing paper upon drawing boards. 
 
 Draw Xnife or Drawing Knife. — A wood-cutting tool, having a long 
 and narrow blade, attached at the ends to two handles, which stand at 
 right angles therewith. The handles are of wood, and the tangs, into 
 
ii8 DICTIONARY OF TERMS USED IN 
 
 wHch. tte ends of the blade are prolonged, are passed right through 
 these, and riveted over brass plates at their ends. The tool being 
 drawn by the handles towards the workman cannot come loose, — the 
 handles being held firmly by the rivets. The tool is used for cutting 
 thick and ieavy chips off the rough edges of boards in order to lessen 
 the labour of the plane. 
 
 Drawn On or Pulled On. — This refers to the method commonly practised of 
 attaching wheels, pulleys, &c., to their axles or shafts when theirmass 
 of metal is such that the blows of a hammer would have no useful effect. 
 Long bolts, whose heads are held in a massive cross attached to one end 
 of the axle, pass on the outside of or else through the wheels between 
 the arms, and the tightening of their nuts against a bar or washer plate 
 stretched across the wheel face slowly but effectively pulls the latter 
 along the shaft into its required position. By the same means wheels 
 are drawn off their shafts. Hydraulio presses are also used. 
 
 Draw Plate. — ^A plate of hardened steel, or of ruby, used ia wire and tube 
 drawing. 
 
 Dredger. — A machine used for removing mud and sand from the bed of 
 a stream or harbour, either by means of scoops or by suction. See 
 Grab, Ladder, Mud Bucket. 
 
 Dresser. — A smith's tool with a round top face and flat sides, over which 
 the forked ends of connecting and other rods are finished to shape. It 
 fits by a square shank into a hole in the anvil. 
 
 Dressing. — See Belt Dressing. 
 
 Dressing off. — Fettling (q.v.). 
 
 Drift. — (1) A steel tool, commonly of rectangular but often also of some 
 special section, used for the purpose of enlarging and of finishing 
 parallel or tapered holes. Drifts are either smooth, or serrated on their 
 flanks, acting by compression in the first case, and by shearing and 
 abrasion in the second. (2) A rectangular strip of steel slightly curved 
 in its length, used for driving keys out of their beds. (3) A cylin- 
 drical tapered pimch used for pulling rivet holes whose boundaries 
 overlap into coincidence with each other. Excessive drifting is to be 
 condemned because of the strain which it puts upon the plates. 
 
 Drifting. — (1) The shaping and enlarging of holes by the use of a drift. 
 ^2) The pulling of overlapping rivet holes into line with each other. 
 
 Drill. — A tool for boring holes in metal or in wood, and revolved either 
 by some form of hand brace or by a special machine. Drills may bo 
 flat towards the point and simply bevelled, or else of the twist lype. 
 The flat drills may have either single or double cutting edges. 
 
 Drill Bow. — The bow of a bow drill (q.v.). 
 
 Drill Boz. — The reel of a bow drill (q.v.). 
 
 Drill Chuck, — A lathe chuck made for the special function of holding 
 drills. The hole for the drill is sometimes square tapered only, but 
 the better chucks have circular ^holes, while the best are also self- 
 centring. 
 
 Drilled Holes. — Holes are drilled in all the best work in preference to 
 being cast. Holes are always drilled for bright bolts notwithstanding 
 that in cast iron the holes may have been first cored small. The best 
 boiler plates are drilled in preference to being punched, but drilling 
 leaves a burr which has to be removed to insure close frictional 
 adherence of the plates. Holes are drilled both by hand and by 
 machine. 
 
 Drilled Plates. — This has reference to the mode in which the holes are 
 
MECHANICAL ENGINEERING. 119 
 
 pierced througli boiler and other plates. In the best boilers, and in 
 some special classes of work, the rivet boles are specified to be drilled 
 instead of being punched. By drilling, the tenacity of the plates ia 
 slightly increased, whereas by punching they are weakened. 
 
 Driller, — A machinist who attends to a drilling machine, maintaining it 
 in working order, setting and iixing the work on its table, and in some 
 shops grinding the driLLs and regulating their speed. 
 
 Drill Feed. — The cutting feeds for drilling machines are of several kinds. 
 They usually consist of a screw and hand wheel, or of a screw and cog- 
 wheel whose boss forms the nut of the screw, or of a rack and pinion, 
 actuated by hand gear, or of a ratchet and paul. 
 
 Drilling Cramp. — ^A pair of rods suspended from a cross bar of which 
 they form a rigid connection. The rods are curved at their lower ends 
 to receive pipe lengths, which rest in the hollows of the curves, as in 
 cradles. They are drilled from above while thus held, the thrust of the 
 drill being taken by the cross bar. Drilling cramps are used specially 
 for outdoor work where a machine is not available. 
 
 Drilling Machine. — A machine which holds and actuates a drill. The 
 forms of these are exceedingly numerous, and are described under their 
 distinctive headings. Essentially a drilling machine consists of a table, 
 a drilling spindle, driving gear, and suitable feed motion. Machines 
 vary in size from those of massive proportions driven by power, to light 
 structures driven by the foot only. 
 
 Drilling Oil. — ^A cheap oil used for the lubrication of the edges of drOls 
 and drill-like cutters. 
 
 Drilling Pillar. — A vertical pillar clamped to a work-bench, and furnished 
 with a sliding adjustable arm from which pressure is exerted through 
 the medium of a screw on a drill revolving between the screw and the 
 work lying on the bench. 
 
 Drilliag Spindle.— See Drill Feed, Drill Spindle. 
 
 Drilling Table. — The table of a drilling machine upon which work is 
 either laid or clamped while being dnUed. It is ordinarily made ad- 
 justable for height, frequently also for lateral movement, and is fur- 
 nished with slots for the reception of the bolts used for holding down 
 the work, and the angle-plates to whose sides small work is frequently 
 bolted. 
 
 Drilling Templet. — ^A templet (q.v.) of cast or wrought iron, which becomes 
 a guide for the drilling of holes. The templet is attached to its work, 
 and the drill is guided in its movements through holes drilled in the 
 templet itself. 
 
 Drill Plate. — A circular plate which is fitted over the mandrel nose of a 
 lathe poppet to receive the pressure of a drill revolving in the drill- 
 chuck, the work which is being drilled resting against the plate. 
 
 Drill Socket. — The socket which receives the shank of a drill, either on 
 the lower end of the drilling spindle of a machine or in the drill chuck 
 of a lathe. 
 
 Drill Spindle. — The vertical spindle of a drilling machine, which carries 
 the drill, and revolves ; and through whose vertical movement the feed 
 is operated. It is a compound structure consisting of the actual spindle 
 which revolves, and the mechanism, usually a screw, or a rack, or lever 
 motion, which imparts its feed. The upper and lower portions are 
 connected with a swivel joint, having hardened compensating collars, 
 or the lower part ia bored to receive the actual spindle which slides 
 through it. 
 
no DICTIONARY OP TERMS USED IN 
 
 Drill Stock. — A drill holder used in tand-drilling ; that is, it includes 
 the socket which receives the drill shank, together with the plain body 
 to which it is attached. 
 
 Drip Can. — See Soap Water Can. 
 
 Drip Cup, or Drip Pan. — A light shallow tray of tin or iron, placed under- 
 neath a bearing or machine to catch the waste oil and prevent it from 
 dirtying subjacent parts. 
 
 Drip Oil Can.— See Soap Water Can. 
 
 Drip Pan. — See Drip Cup. 
 
 Driven. — In gearing signifies the wheel, or wheels, actuated by a driver 
 (q.v.). In calculations involving trains of gearing the product of the 
 series is in geometrical, not arithmetical ratio. Hence the rule is : 
 Multiply the radii of all the drivers together and the radii of all the 
 driven, and divide the latter by the former for the mechanical efficiency. 
 
 Drive Pipe. — The feed or inlet pipe of a hydraulic ram (q.v.). 
 
 Driver. — (1) In gearing signifies the wheel which drives another. (See 
 Driven. (2) A projecting piece of metal used when tumiug between 
 dead centres, to impart rotation to the work. It is either attached to 
 a face plate, or is carried in a slot in the point centre, and bearing 
 against a projection on the carrier which embraces the end of the work, 
 BO drives it round. 
 
 Driver Chuck, or Running Centre Chuck. — A point chuck in the head- 
 stock mandrel which carries work being turned between centres. 
 
 Driving Axle. — An axle which communicates motion ; hence called a live 
 axle, in opposition to a dead axle (q.v.). The axle of a locomotive to 
 which the motion of the connecting-rods is directly communicated is 
 an illustration. 
 
 Driving Band, — See Belt. 
 
 Driving Chain. — A pitch chain (q.v.) ; or an ordinary chain whose links 
 fit into suitable recesses cast around the periphery of an ordinary 
 
 Driving Chuck. — (1) A lathe chuck fitted with a driver (q.v.) for actuating 
 the carrier (q. v.) . The chuck is either a cu'cular-f ace plate, having a 
 pin projecting from its face ; or it is a dead centre enlarged at the neck, 
 and pierced with a slot for the reception of an |_- shaped driving piece. 
 (2) Sometimes applied to the cup chuck, because the wood is driven into 
 it by blows from a hammer. 
 
 Driving Fit. — A bush, a shaft, or spindle is said to le a driving fit, 
 when the blows of a hammer are required to send it down into the. 
 hole bored for its reception. The amount of force required will vary 
 with circumstances. It must not be so much as to burst the metal 
 around the hole, nor so slight that the fitting will wear or work loose 
 in time. 
 
 Driving Gear. — A term of general application, signifying the immediate 
 arrangement of wheels, pulleys, belts, levers, &c., by which motion is 
 communicated. 
 
 Driving Home. — A shop term which signifies the driving of a wheel or a 
 shaft, or any portion of mechanism, to its permanent position and final 
 resting place. 
 
 Driving Side. — That side of a belt which drives its pulley. The side 
 most suitable for driving will depend upon the relative positions of the 
 driving and driven pulleys. In a horizontal arrangement it is the 
 lower or slack side ; m pulleys arranged vertically either side may be 
 the driver. When belts pass over guide pulleys placed at different 
 
MECHANICAL ENGINEERING. 121 
 
 angles from tlie main puUey, they can only drive on the sides which 
 are in the same plane. 
 
 Driving Springs. — The springs -which carry the axle boxes of the driving 
 axles of locomotives. They are frequently volute springs instead of 
 being built np, and a pair are put under each axle box. 
 
 Driving Surface. — The after face of a propeller blade, or that which 
 thrusts against the water. 
 
 Driving Wheels. — The wheels of a locomotive which are attached to the 
 driving axle. 
 
 Drop, — (1) That stage of the pig-boiling (q.v.) process in which the 
 ebullition or boU ceases. (2) Also that stage of the process of the 
 manufacture of steel in the Bessemer converter at which the flame 
 suddenly shortens, indicating the complete decarburisation of the metal, 
 and which is the signal for the shutting off of the blast. See Boil. 
 
 Drop Bottom Boxes. — Boxes used in the laying or deposition of blocks of 
 artiiicial stone or concrete by gravity alone. The bottoms of the boxes 
 are made to unfold and open downwards, allowing the enclosed block 
 to drop into its place. 
 
 Drop Bottom Cupola. — The bottoms of many ciipolas are now furnished 
 with hinged doors made to fall downwards by the knocking away of a 
 pin. The advantage of their use is, that the labour of raking out the 
 fire after the blowing is avoided, the whole mass falling bodily on the 
 dropping of the doors. Such cupolas are necessarily supported on 
 short columns, to give sufficient space for the embers underneath. 
 
 Drop Bottom Skip. — See Skip. 
 
 Dross. — The sullage, scurf, oxide, 'and other impurities which are skimmed 
 ofl: the top of molten metals, or which accumulate in the head or in 
 the riser. 
 
 Drum. — (1) A large barrel which coils the chain in lifting-tackle. (2) A 
 wide plain belt pulley. (3) A stepped belt pulley, for driving at 
 different speeds. 
 
 Drum Head. — The upper portion of a capstan. 
 
 Drummer. — A term applied to a smith's hammerman in many parts of 
 the country. 
 
 Drunken Saw. — A circular saw tightened on its spindle, at an angle with 
 the axis of the spindle, by means of bevelled collars. The turning round 
 of the collars through an arc of the circle allows of variation of the 
 angle within certain hmits. These saws are used for the cutting of 
 grooves in tiniber, and the angle at which the saw is placed governs 
 the width of the groove. Sometimes called the wabble saw. 
 
 Drunken Screw. — ^A screw whose outline is irregular or wavy. 
 
 Dry Bottom. — A puddling furnace is said to have a dry bottom when the 
 slag is not allowed to accumulate, but is drawn ofi: as frequently as 
 possible. 
 
 Dry Brush. — Iron-moulders term the brush with which they sweep the 
 sand away from the joints of moulds and of patterns a dry brush, to 
 distinguish it from the wet or water brush (q.v.). 
 
 Dry Copper. — See Poling. 
 
 Drying. — (1) Drying has the same signification as coming to nature (q.v.). 
 (2) The expelling of the moisture from a mould or a core, in a drying- 
 stove, previous to casting. 
 
 Drying Oils. — Certain vegetable oils which become dry and solid on expo- 
 sure to the oxygen of the air. Linseed, hemp, poppy, ahnond, and 
 colza are drying oils. The presence of litharge or lead oxide hastens 
 
122 DICTIONARY OF TERMS USED IN 
 
 the drying process. Drying oils are therefore used for paints. (See 
 Liuaeed Oil.) Owing to this rapid absorption of oxygen, spontaneous 
 combustiou (q.v.) has frequently taken place. 
 
 Drying Stove. — A stove used for the drying of foundry moulds and of 
 large cores. It is a brick-built chamber of rectangular form adjoining 
 the foundry, of which it forms a part. Into it run lines of rails for 
 carrying the core carriages. It is heated by a coke lire made in a pit 
 in the floor, the doors being hermetically sealed, and the smoke pass- 
 ing away through a flue at the back. The temperature of the stove 
 should not exceed about 400° Fahr., else the cores wiU become burnt. 
 The time during which a mould or core should remain in the stove wUl 
 vary from two or three hours to as many days, being dependent 
 entirely on its bulk. 
 
 Dry Moulding. — Moulding in dry sand (q.v.). 
 
 Dry Puddling. — Puddling carried on in the reverberatory furnace, where 
 deoarburisation and oxidation are chiefly effected by the oxygen of 
 the air. It is so called because the metal is never allowed to pass 
 beyond the pasty condition. It is now almost superseded by the 
 process of pig boOing (q.v.). See App. 
 
 Dry Sand. — Foundry sand consisting of a mixture of strong sands, coal 
 dust, and dung. Called dry because moulds made in it are dried in the 
 stove, in contradistinction to green sand which is not dried. (See Green 
 Sand, Skin Drying.) Drying is always resorted to when castings of 
 superior quaHty are desired. 
 
 Dry Sand Moulding. — The moidding of work in dry sand (q.v.). The 
 distinction between dry sand moulding and loam moulding (q.v.) is 
 that the latter is always effected without the use of a f uU pattern, whUe 
 in the former a pattern is employed, and also that the sand in the 
 former case is mixed and manipulated like ordinary green sand, while 
 in loam work it is mixed with water to render it plastic. 
 
 Dry Steam. — Steam which has neither been superheated (q.v.) on the one 
 hand, nor mixed with the water of priming on the other, but remains in 
 the normal condition, which experience has proved to be the most 
 suitable for use in engine cylinders. Called also saturated steam. 
 
 Dry Uptake. — When the uptake of a marine boiler is placed without the 
 shell away from contact with water and steam it is termed dry, to dis- 
 tinguish it from a wet uptake (q.v.). 
 
 Dry Wood. — Timber from which the sap has been removed by seasoning. 
 It should be allowed to remain in the log or balk for two or three years 
 after felling. When sawn into boards it should be piled in a rack on 
 an open buUding exposed to currents of air, thin strips of wood placed 
 crosswise alternating 'with the boards in the piles, to allow of the access 
 of air to both sides of the timber. The boards thus " stripped " should 
 remain a twelvemonth or two years, depending on thickness, before 
 being used. 
 
 Ductility. — That property of metals in virtue of which they can be drawn 
 out into wires. Tliis property depends partly upon maUeabihty, but 
 chiefly upon the tenacity of the particles composing the metal. 
 
 Dull. — A tool is said to be dull when it outs or abrades with difficulty. 
 
 Dull Metal. — Cast nietal is said to be dull when it is allowed to part 
 with some considerable portion of its heat in the ladle before being 
 poured, so as to enter the mould in a somewhat thick condition. 
 Dull metal is used by preference for heavy work, since it shrin&s less, 
 crystallises larger, and cools sounder than hot metal. The limit to th^ 
 
MECHAmCAL ENGINEBRinG. 123 
 
 use of duU metal is tLat at wMcli cold shuts form, and the metal does 
 not possess sufficient fluidity to fill the minor ramifications of the 
 mould. Metal is dulled by being alloived to stand in the ladle, or by 
 the throwing of cold runner heads into the molten mass. 
 
 DuU Eed Heat. — This corresponds with a temperature of about 1290° F. 
 
 Duodecimals. — A system of multipKcation to obtain the superficial and 
 solid areas of rectangular figures, by the use of units of square feet, 
 square inches, superficial primes, solid primes, solid feet, solid inches, 
 solid seconds ; the multiplication taking place crosswise ; the product 
 of feet into inches giving primes. A prime is 12 superficial inches, 
 that is, a piece 12 in. long and 1 in. broad. It is used in timber 
 measurement, and in rectangular measurement of tanks, &c. 
 
 Duplex Bear. — A punching bear (q.v.) which is actuated by a screw 
 moving double levers. 
 
 Duplex Lathe. — A self-acting lathe furnished with two rests, one on 
 each side of the bed, for the taking of two cuts at one time oil a piece 
 of work. The hinder tool is therefore inverted. 
 
 Duplex machines. — Machines in which two sets of similar operations are 
 performed at one time. 
 
 Duplex Planing Machine. — A double planing machine having two beds 
 and two tables. 
 
 Dutch Wheel Crane. — A whip crane (q.v.). 
 
 Duty. — The duty of a steam engine is the number of pounds raised one 
 foot high by the burning of a bushel of Welsh or Cornish coal. The 
 average duty is 60,000,000 of pounds raised one foot high, or 
 60,000,000 of foot pounds. 
 
 D-Valve. — ^Applied to the common slide valve, because the face of the 
 valve is hoUowecl ia the form of a letter " Q, " and the outside rounded 
 to the same outline. 
 
 Dwarf Pillar. — A very short piUar. Dwarf pillars are used for the sup- 
 port of the beds of reverberatory furnaces and the sides of blast furnaces. 
 
 Dying In. — The merging of a hollow radius into a plane surface is so 
 termed by workmen to distinguish it from the meeting of abrupt 
 angles. 
 
 Dynametrical Horse-Power. — See Actual Horse-Power. 
 
 Dynamical Values. — Theoretical values converted into terms of work 
 units. Thus thermal values (q.v.) multiphed by foot pounds (q.v.) 
 give dynamical or practical values in foot pounds. Yet since in esti- 
 matittg these dynamical values no allowance is made for losses due to 
 imperfection of mechanism, and loss of heat and work consequent 
 thereon, a percentage only of the calculated dynamical values can be 
 taken in practice. 
 
 Dynamic Fatigue. — The fatigue of materials (q.v.) which results from a 
 dynamic load. 
 
 Dynamic Load. — A rolling or a moving load, as distinguished from a, 
 dead load. 
 
 Dynamics. — That branch of mechanics which treats of the laws of forces 
 that produce motion in the bodies and structures upon which they act. 
 See Statics. 
 
 Dynamometer. — An instrument for measuring the intensity of a force ; 
 usually consisting of some form of bent or spiral, spring, whose 
 strength has been tested and registered. A special form of dynamo- 
 meter is that contrived by Prony, for determining the friction of a 
 shaft. A pair of friction blocks, capable of being tightened around a 
 
124 DICTIONARY OF TERMS USED IN 
 
 revolving shaft by means of tolts, are attaclied to a lever. The 
 amount of friction of the shaft for any given pressure is determined by 
 the product of a weight suspended from the lever, and just sufficient , 
 in amount to counteract the tendency to revolution, into the length of 
 the lever itself. 
 
 E. 
 
 E. — The modulus of elasticity (q.v.). 
 
 Ear. — A lug (q.v.). 
 
 Early Cut Off. — This term relates to the ratio of the expansion of steam 
 in an engine cylinder. Any cut off under one-half the stroke may be 
 properly termed early. 
 
 Ebonite. — A compound of india-rubber with sulphur and other ingre- 
 dients. It ia used for draughtsmen's set squares and scales, for which 
 its qualities of hardness, moderate elasticity, and smoothness of surface 
 render it suitable. Ebonite differs essentially from vulcanised rubber 
 in being charged with an excess of sulphur, and subjected to a greater 
 heat for a longer period of time. 
 
 Eccentric. — A piece of mechanism employed in engines for converting the 
 rotatory motion of the crank shaft into a reciprocating rectilinear motion 
 upon the shde valve or the feed pump. It is eifected by giving to a 
 ring upon the shaft a definite '* throw " or eccentricity, equal in amount 
 to the half of the travel of the valve, or of the plunger stroke. Eccen- 
 trics are also much used in general machine construction. Sometimes 
 spelt excentric. 
 
 Eccentric Hoop. — See Eccentric Strap. 
 
 Eccentricity. — The deviation of the centres of two circles from one 
 another. 
 
 Eccentric Lug. — The projecting portion of an eccentric strap, to which 
 the eccentric rod is attached. 
 
 Eccentric Rod. — The rod which receives the motion of the eccentric strap 
 and transmits it to the valve, or pump, or other rod to which movement 
 is to be imparted. 
 
 Eccentric Sheave. — The body of an eccentric, or the actual eccentric itself, 
 which is forged or keyed directly upon the crank shaft, and whose 
 throw is communicated to the eccentric strap. 
 
 Eccentric Strap or Eccentric Hoop, — The belt which encircles the eccen- 
 tric sheave, and transmits its motion to the eccentric rod. It is grooved 
 on its inner face to fit into a corresponding groove on the rim of the 
 eccentric, without which it would sKp off sideways. Being grooved, 
 therefore, it is made in two pieces, which embrace the sheave, and are 
 held with bolts passing through projecting lugs. Straps are made in 
 iron or in gun metal, sometimes iron castings are employed, having gun- 
 metal liners. 
 
 Eccentric Throw Out, — The motion by which the wheels on the hinder 
 mandrel of a back-geared lathe are thrown out of gear, a small eccen- 
 tric made fast to the mandrel being used for the purpose. The term 
 distinguishes this form of throw-out gear from a backward or linear 
 throw-out motion, in which the mandrel bearings slide in linear guides, 
 and also from an endlong linear motion, by which the teeth are slid 
 out of contact in their longitudinal directions. 
 
MECHANICAL ENGINEERING. 125 
 
 Dconomiser.' — An apparatus, or arrangement of pipes or reserroirs, in 
 -ffhioh the feed water for steam boEers is heated up to, or higher than, 
 the boiling point. Feed water heaters, therefore, are economisers. 
 
 Edge-Planing Machine. — See Plate Edge Planing Machine. 
 
 Edge Eunners. — Loam and mortar nulla are so called, because the rolls 
 run on edge. 
 
 Edge Tools. — Cutting tools. 
 
 Eduction, — The escape of the exhaust steam from a cylinder. 
 
 Eduction Overlap. — Exhaust lap (q.v.). 
 
 Eduction Port. — An exhaust port (q.v.). 
 
 Eduction Trunnion. — The trunnion of an osciUatuig cylinder through 
 ■which the exhaust steam passes on its way to the condenser. 
 
 Effective Area. — The effective area of a screw blade is that obtained by 
 the projection of the blade on a plane at right angles with its axis. It 
 is, therefore, less than the superficial area. 
 
 Effective Heating Surface. — See Heating Surface. 
 
 Effective Pressure. — The net amount of pressure upon the piston of an 
 engine, over and above that which is necessary to balance the pressure 
 of the atmosphere. 
 
 Effective Section. — The effective section of the shell of a steam boiler is 
 a fractional portion of the gross section (q.v.) obtained by deducting 
 therefrom the loss of strength due to the riveted seams. 
 
 Efficiency. — The efficiency of a joint, structure, machine, or part, is 'the 
 ratio which such bears to some understood standard of reference. The 
 efficiency of a riveted joint is its percentage strength, estimated rela- 
 tively to that of the solid plate. The efficiency of a machine is its 
 modulus (q.v.). 
 
 Egg-end Boiler. — ^A horizontal, cylindrical, externally fired steam boiler, 
 having hemispherical ends. It is now little used. 
 
 Egg Sleekers. — Moulder's tools, whose faces are a segment of a sphere. 
 IJsed for cleaning the hoUow faces of work of hemispherical sections. 
 Also termed button sleekers. 
 
 Eighth Bend. — A bend pipe having socketed and spigoted ends, whose 
 length equals one-eighth of the circumference of the circle to whose 
 radius the curve of the bend is struck. 
 
 Ejector. — See Injector. 
 
 Ejector Condenser, — A condenser in which the water is drawn from the 
 feed tank into the condensing chamber by the action of the steam 
 itself. 
 
 Elastic. — Strictly speaking aU bodies are elastic, since aU when subject 
 to stress experience strain. But it is customary to divide bodies into 
 elastic, and non-elastic or rigid, according to their amount of sensible 
 elasticity ; so that a body when subjected to a given stress at a given 
 temperature, which does not increase when the stress is prolonged, and 
 disappears when the stress is removed, is called an elastic body. See 
 Elastic Limit. 
 
 Elastic Blow. — (1) A blow from a hammer which is not firm and dead. 
 (2) Signifies the nature of the blow given by that class of steam ham- 
 mers where steam is introduced between the piston and the cylinder 
 ends to produce cushioning. 
 
 Elastic Core Packing. — A packing sometimes used for stuffing boxes, 
 consisting of india-rubber enclosed in canvas, the india-rubber consti- 
 tuting the elastic core. Sometimes called elastic steam packing. 
 
 Elastic Force. — That property which steam possesses in common with 
 
126 DICTIONARY OF TERMS USED IN 
 
 gaseous bodies generally of undergoing expansion and compression, 
 •witli corresponding diminution and increase of pressure. 
 
 Elasticity. — This has reference .specifically to the extent to which a bar or 
 structure miy be elongated by tensile stresses, without remaining per- 
 manently extended on the removal of the tensile force. 
 
 Elasticity, Modulus of. — See Modulus of Elasticity. 
 
 Elastic Limit. — That poiut at which the molecular actions within a bar 
 or structure tending to resist deformation cease to balance the strains 
 imposed thereon ; in other words, when the straining action is so great 
 as to produce permanent change of form. Materials should neyer be 
 strained to this limit.' See Permanent Set. 
 
 Elastic Nut. — A form of nut by which compensation is made for the wear 
 of the nut and its screw. An elastic nut may either be sprung, by 
 sawing a longitudinal groove through one side of it, and hammering it 
 upwards, or it may consist of two separate nuts, one above the other, 
 kept pressing ia opposite directions on the screw by an interposed sprhig 
 ring. 
 
 Elastic Steam Packing. — See Elastic Core Packing. 
 
 Elastic Strain. — The amount of strain imposed upon a structure by a load 
 not sufficiently great to cause the material of the structure to exceed 
 the elastic limit (q.v.). 
 
 Elastic Strength. — The greatest stress which a bar or structure is 
 capable of sustaiaing within the elastic limi t 
 
 Elastic Washer. — (1) A form of washer employed ia place of a locknut. It 
 consists of a split steel ring whose faces near the split ends are turned 
 slightly upwards and downwards, thereby diverging from a true plane. 
 These are sprung or compressed level by the pressure of the nut, and 
 their elasticity prevents the latter from slacking back. (2) Washers of 
 vulcanised india-rubber, employed chiefly in pump work. 
 
 Elbow. — ^A bend pipe whose direction of outHne is abruptly angular, with- 
 out any radius or rounding of one portion into the other. The two 
 arms of the elbow meet at 90° of angle. Employed chiefly for connect- 
 ing wrought-iron piping. 
 
 Elephant. — A drawing paper, measuring 28 in. by 23 in. and weighing 
 72 lbs. to the ream. 
 
 Elevation. — In drawing signifies that view of a structure which it bears 
 to an observer standmg beside it and looking against its vertical face. 
 A sectional elevation supposes the structure cut vertically through the 
 centre, and the observer standing as before. 
 
 Ellipse. — One of the conic sections, the curves of whose ends are equal, 
 and whose centres, or foci, lie in the conjugate axis at equal distances 
 from the centre. 
 
 Ellipsoidal Eivet. — A rivet the section of whose head is eUiptioal in 
 form. 
 
 Elm [Ulmus campesiris). — A tree of the natural order TJlmacece. It is a 
 coarse, open-grained wood, much given to warping, and is very spar- 
 ingly used in engineers' works. It is employed for foundry strickles, 
 being used to strike the wet loam to shape. Its tenacity is about 
 14,000 lbs. per square inch. A cubic foot weighs S^-S lbs. Sp. gr. -65. 
 TTie American ehn ( Ulmus Americana) is whiter and harder than the 
 English elm, and also more straight-grained. 
 
 Elongation. — See Reduction of Area. 
 
 Emery. — A species of corundum composed of oxide of iron, alumina, 
 silica, and a small proportion of Hme. It is crushed and pounded to 
 
MECHANICAL ENGINEERING. 127 
 
 different degrees of fineness, made into a variety of preparations, and 
 used for different purposes, its value depending upon its hardness. 
 
 Emery Euff. — A wood roller, having emery powder glued upon its peri- 
 phery and side faces for the poHshing of metaUic 'work. It is revolved 
 at a high speed. 
 
 Emery Cloth. — Powdered qmery glued on thin cloth, and used for remov- 
 ing file marks, and for polishing metallic surfaces. 
 
 Emery Grinder. — An emery wheel (q.v.). 
 
 Emery Grinding. — The abrasion of metallic surfaces upon an emery wheel, 
 buff, or lap. 
 
 Emery Lap. — See Lap. 
 
 Emery Paper. — Powdered emery glued on paper and used for polishing 
 metallic surfaces. It is not so flexible as the emery cloth. 
 
 Emery Planer. — ^An emery surfacer (q.v.). 
 
 Emery Powder. — Crushed emery passed through sieves of different mesh, 
 superfine flour emery being the finest, com emery the coarsest used by 
 engineers. Used for abrading and polishing metallic surfaces. 
 
 Emery Stick. — See Lap. 
 
 Emery Surfacer. — ^A form of emery grinder (q.v.) in which a broad solid 
 emery wheel is employed as a substitute for the cutting tools of 
 shaping machines. The work to be surfaced is af&sed to a sliding 
 table, and passed underneath the revolving wheel. 
 
 Emery Wheel. — A wheel made of powdered emery cemented together, or 
 of emery cemented to a wood centre. It is revolved at a high speed, 
 and is used for grinding. An emery buff (q.v.) is also a wheel, but is 
 of fine texture and used for polishing only. Emery wheels are 
 cemented together with a silioate iasoluble in water. They are made 
 in about ten grades of coarseness. 
 
 Emperor. — A drawing paper of finest quality. It is made in sheets 
 measuring 72 in. by 48 in. 
 
 Empirical Bule. — Aoy rule or equation which is not deduced from purely 
 mathematical or physical considerations, but which is based upon 
 experience, convenience, or custom. It is therefore not scientifically, 
 but only practically and approximately accurate. IVEost of the formulae 
 employed by engineers are empirical in that they are based chiefly on 
 the results of previous experiment and practice. 
 
 Enamelling. — The coating of water pipes internally with a smooth 
 paint in order to diminish the friction of the fluid, and loss of head 
 consequent thereon. 
 
 Encastre. — Encaatre signifies the firm fixing of the end of a cantUever, or 
 the ends of a beam in a wall or other support. A beam is stronger 
 when encastre than when simply supported. 
 
 Enclosed Wheels. — Reaction wheels (q.v.). 
 
 End Elevation, or End View. — A view on a dravdng showing the end of 
 a structure, as distinguished from its side view. 
 
 End Grain, — That face of a piece of timber exposed by the cutting 
 of its fibres transversely to their course. 
 
 Endless Chain, — A chain united at the ends and used as a carrier of 
 power, such as a pitch chain (q.v.), or an ordinary chain which is made 
 to fulfil the purpose of a pitch chain by fitting into recessed chain 
 wheels. 
 
 Endless Eope. — A rope united at the ends, and used as a carrier of power, 
 as when the traversing motion is given to an overhead travelling crane 
 by a man hauling at the rope below. Endless ropes ran in smooth 
 
128 DICTIONARY OF TERMS USED IN 
 
 sheaves, or in wave wheels, the effect of the last-named form being to 
 increase the bite of the rope. 
 
 Endless Saw. — A band saw (q.v.). 
 
 Endless Screw. — A worm (q.v.), so called because it drives continually in 
 one direction, without reversal of its motion. 
 
 End Links. — The links which terminate the standard lengths, usually 
 15 fathoms long, of chain as ordinarily manufactured. They are there- 
 fore used as shutting links (q.v.), being about two-tenths thicker than 
 the ordinary links. 
 
 End Measurement. — Measurement taken with a caliper or micrometer 
 gauge, as opposed to line measurement (q.v.). This is far more 
 accurate than line measurement. 
 
 End Play. — The play at the ends of a revolving part, that is, play in a 
 longitudinal direction. It is essential in some cases, in others it is an 
 evil. End play is necessary in the crank pins of oscDlating cylinders, 
 while in the back centres of lathes it is an evil. 
 
 End View. — See End Elevation. 
 
 Energy. — The capacity for performing work, or, using an older term, vu 
 viva. It may be potential energy, or that which remains in abeyance 
 until called into exercise, such as the energy present in fuel, or in a 
 machine which is wound up, or in a lifted weight, or in the steam in a 
 boiler. It may be kinetic energy, or energy in motion, or actual 
 energy, doing tangible work. The energy of a moving body is pro- 
 portional to the square of its velocity. 
 
 Engine. — A motor or prime mover (q.v.), automatic in its action, as 
 distinguished from a machine which can only receive motion from a 
 motor external to itself. 
 
 Engine Beam. — The beam of a beam engine. 
 
 Engine Boiler. — See Boiler. 
 
 Engine Counter. — See Counter. 
 
 Engine Cylinder. — See Cylinder. 
 
 Engineering. — See Mechanical Engineering. 
 
 Engine Fire. — The fire underneath an engine boiler. 
 
 Engine Friction. — The total friction developed by an engine indepen- 
 dently of that of any machinery which it has to drive. "Wide bearing 
 surfaces, balanced valves, and proper lubrication are the means whereby 
 its amount is reduced. It ranges from about 10 to 50 per cent., the 
 last being an excessive amount, and only to be met with in engines of 
 bad construction., 
 
 Engine Lathe. — A somewhat vague term, but as generally used signifies 
 a lathe of moderate or large size, designed to perform the operations of 
 engineer's work, and driven by the motive power derived from the 
 engine. 
 
 Engine Pit. — A pit from 2 ft. 6 in. to 3 ft. 6 in. deep, dug between the 
 rails in locomotive repairing sheds, and over which the engines are 
 brought in order that the workmen may be able readily to get at the 
 under work. 
 
 Engine Power. — The power of an engine is obtained by multiplying the 
 piston speed into the total average pressure upon the piston. Erom the 
 product the amount of engine friction has to be deducted, and the 
 resiilt is a remainder which divided by 33,000 gives the net horse- 
 power. 
 
 Engine Register. — A counter (q.v.). 
 
 Engine Shaft. — The driiTng or crank shaft of an engine. 
 
MECHAtflCAL ENGINESRING. 129 
 
 fiagiae Work. — The mechanical detaOs connected witli the construction 
 of engines, as distinguislied from other classes of machine work. 
 
 Entablature.— An overliead table or frame sustained by -vertical columns 
 arising from a base plate, and between which and the base plate 
 certain machine parts are carried, as the working parts of forging 
 presses, pumps, &c. 
 
 Entering File. — See Cottar Files. 
 
 Entering Tap. — A taper tap (q.v.). 
 
 Envelope. — (1) The coveriug of a solid. (2) The setting out or develop- 
 ment of plates, and boiler-makers' work may be regarded as the deve- 
 lopment of the envelopes of solid bodies. 
 
 Epieyclic Train. — A train of gearing in which the centres of motion 
 (q.v.) are not fixed, but movable in space. 
 
 Epicycloid. — A cyoloidal curve which is formed by a generating circle 
 rolling upon and without a fundamental circle. The faces of external 
 or spur-wheel teeth are so formed. 
 
 Equal Forces. — Forces which act in opposite directions and balance each 
 other. 
 
 Equality of Moments, — The condition of equilibrium in a system of 
 forces, by which when power is gained time is lost, and vice versd. 
 When opposing forces balance one another, so that equilibrium results, 
 there is said to be equality of moments. 
 
 Equalling File. — A very thin, flat, and generally parallel file, sometimes 
 also furnished with one safe edge. 
 
 Equal-sided Angles. — See Angle Irons. 
 
 Equation. — An assemblage of quantities and signs, which placed to right 
 and left of each other, and separated by the sign = , are numerically 
 equivalent to each other. 
 
 Equation of Moments. — The representation of the various moments of 
 force about a structure, put into the form of an equation. 
 
 Equilibration. — The application of balance weights to the driving wheels 
 of locomotives and other rapidly revolving bodies, in order to produce 
 steadiness of motion. 
 
 Equilibrium. — (1) Forces are in equilibrium when they neutralise each 
 other's influence. (2) A body resting upon its base is in equilibrium 
 when its centre of gravity lies vertically over the base on which it is 
 supported. See Stable, and Unstable Equilibrium. 
 
 Equilibrium Governor. — A governor whose balls and arms are counter- 
 balanced. 
 
 Equilibrium King. — A metallic ring attached to the back of the slide 
 valve in large engines generally, for the purpose of lessening the 
 amoxont of its friction, which friction becomes excessive in large valves 
 exposed on the one side to the fuU steam pressure, and on the other 
 to atmospheric pressure, or to the vacuum of the condenser. The ring 
 encloses a space on the back of the valve equal in area to that of the 
 exhaust port, into which space, therefore, no steam can gain admit- 
 tance. The ring is commonly and properly put into a recess turned on 
 the inside face of the valve casing, occasionally, however, on the back 
 of the valve itself. It is kept pressed against the face by means of set- 
 screws thrusting against india-rubber rings and metallic springs. 
 
 Equilibrium Slide Valve. — A slide valve which is provided with an equi- 
 librium ring (q.v.) upon the back. Or a valve which is of the gridiron, 
 double or treble ported type, the steam having free access to the outer 
 and inside hollow portions See Double-ported Slide Valve, 
 
130 DICTIONARY OF TERMS VSED- IN 
 
 Equilibrium Valve. — A valve in wliicli the pressures on each face ars 
 equalised, or nearly equalised, so that it moves ■with the least expendi- 
 ture of power and the minimum of friction. See Double-heat Valve, 
 Equilibrium King, Equilibrium Slide Valve. 
 
 Equivalent. — A number or quantity numerically equal to another number 
 or quantity, hut expressed in different terms. 
 
 Erecting. — The final building up of machines or engines in their entirety 
 in readiness for -working. All the vrork of the turners, planers, slotters, 
 drillers, and fitters is brought to the erector, presumably ready to go 
 together, little or no adjustment being necessary at his hands. He 
 therefore builds or erects the work which has been prepared in the 
 other departments. 
 
 Erecting Shop. — A large, lofty, roomy building used for the erecting 
 (q.v.) of engine and machine work. It may be a building separate from 
 the fitting and machine shops, or a section adjoining these. It is pro- 
 vided with vices, a powerful overhead traveller, and rails, pits, founda- 
 tion and base plates, or other conveniences, according to the nature of 
 the engines and machines which are manufactured. 
 
 Ersctor. — A fitter or working engineer whose special task is that of 
 erecting (q.v.). 
 
 Escape Valve. — See Cylinder Escape Valve. 
 
 Estimate. — See Tender. 
 
 Evaporation.. — The conversion of a fluid into vapour" 
 
 Evaporative Value. — Denotes the relative capacities for vaporising water 
 possessed by different types of steam boilers, by various arrangements 
 of heating surfaces, or by fuels of different characters. These values 
 are expressed either in horse-powers, or in units of work, or in thermal 
 units. 
 
 Even Pitch. — A screw is said to be of even pitch when the number of 
 threads per inch in it either corresponds with, or is some aliquot part of, 
 the pitch of the threads of the leading screw of the lathe in which it is 
 being cut. Thus with a leading screw of 4 threads to the inch, 4, 8, 
 12, &c., threads per inch would be even pitches, and the tool is in the 
 right position for cutting in any position of the clasp nut. 
 
 Excavator. — A term applied to a class of machines whose function is the 
 digging out and removal of earthy material in the preparation of foun- 
 dations and harbour works. See Grab. 
 
 Excentric. — See Eccentric. 
 
 Exhaust. — The passage through which the spent steam of an engine 
 cylinder obtains egress to the outer air, or to the condenser. 
 
 Exhaust Edges. — The inner edges, or the edges of the hollow or Q por- 
 tion of a slide valve, by which the exhaust steam is cut off. 
 
 Exhausting Fan. — Essentially an ordinary fan (q.v.), but having the 
 sides enclosed to form an exhaust pipe. 
 
 Exhaustion. — The escape of spent steam through the exhaust pipe (q.v.). 
 Sometimes termed eduction. 
 
 Exhaust Lap. — The reduction or narrowing of the inner faces of a slide 
 valve to less than that distance which would correspond with a length 
 measured between the inner edges of the steam ports, by which dif- 
 ference the ports are closed earlier than they would be if their edges 
 coincided exactly with those of the arch of the valve. The result i? 
 that the steam is cushioned or compressed. The term exhaust lap, or 
 its equivalent, eduction over-lap, is used in contradistinction to steam 
 lap (q.v.). 
 
MECHANICAL ENGINEERING. 131 
 
 Ezhanst Iiine. — The bottom line of an indicator diagram, wHoli repre- 
 sents the manner of the exhaustion of steam in an engine cylinder. 
 
 Exhaust Pipe. — The pipe which conveys away the exhaust steam from 
 the exhaust port from an engine cylinder. 
 
 Exhaust Port. — The opening or means of exit provided for the escape of 
 the exhaust steam from an engine cylinder. Its area exceeds by about 
 one -half that of the steam ports in order to diminish the evil of back 
 pressure. Sometimes called the eduction port. 
 
 Exhaust Relief Valve. — A shde valve whose construction is such that a 
 greater width is opened to exhaust than to steam ; in other words, the 
 port is fully opened to exhaust, biit only partly opened to steam. 
 
 Exhaust Steam. — The steam which, having spent its force and accom- 
 plished its work in a cyliader, is allowed to pass away into the atmo- 
 sphere or into the condenser. 
 
 Expanding. — Boiler tubes are expanded when their ends are opened out, 
 and tightened in their tube plate. See Tube Expander. 
 
 Expanding Bit. — A boring bit, having a cutter or cutters capable of 
 radial adjustment to enable the one tool to bore holes of different 
 diameters. 
 
 Expanding Mandrel. — A form of lathe chuck, which is made to expand 
 within the work, instead of, as is usually the case, to clip it upon the 
 outside. The work is therefore bored first and turned afterwards. 
 With this chuck, work of various diameters, within the range of the 
 mandrel, can be centred truly, and when turned can be released without 
 the risk attendant upon driving off with a hammer. The commonest 
 form is that of two cones, or rather, frustra of cones, whose apices point 
 towards each other, and between wMoh the work is grasped by the 
 tightening up of a bolt. There are several patent mandrels. 
 
 Expanding Metal. — ^Bismuth, and alloys of bismuth, which are therefore 
 employed for the close filling up of holes. 
 
 Expanding Ring Clutch. — A form of clutch, or coupKng, in which the 
 friction of a spht ring against a bored hole, or recess, is the effective 
 agent. The female portion of the clutch contains a parallel bored hole. 
 Within this fits a metaUic ring divided transversely, and capable of 
 being forced outwards against the sides of the hole by means of a 
 wedge, the wedge being actuated by a lever or a screw. On the release 
 of the wedge frictional contact ceases. 
 
 Expansion. — (1) The period during which the steam in an engine cylin- 
 der is increasing in volume, extending from the instant of admission or 
 out off to that of release. (2) The increase of steam in volume, corre- 
 sponding with diminishing pressure. (3) The extension of bodies corre- 
 sponding with increase of temperature, the extension being linear, super- 
 ficial, or cubical, being in the ratios one, two, and three respectively. 
 
 Expansion Coupling. — ^A form of coupling in which two thin sheets of 
 steel corrugated circumferentially are interposed between two ordinary 
 flanged coupling faces which they connect, so that a certain amount of 
 end play within the limits of the elasticity of the steel discs takes place. 
 Other expedients are also made use of. 
 
 Expansion Curve. — The falling curve in an indicator diagram which cor- 
 responds with the falling pressure due to the expansive working of the 
 steam in the cylinder, and which reaches therefore from the point of 
 cut ofi to the commencement of exhaust. 
 
 Expansion Gear. — The whole of the arrangements by which the expansion 
 of steam in an engine is accomplished and regulated. 
 
132 DICTIONARY OP TERMS USED IN 
 
 Expansion Engine. — A steam engine -worked expansively. See Expan- 
 sive Working. 
 
 Expansion Hoop. — A ring wMch forma an expansion joint in a boiler flue, 
 usually a Bo^vling hoop (q.v.). 
 
 Expansion Joint. — (1) A sliding joint inserted in a series of steam pipes 
 in order to prevent the fracture which would result from the expansion 
 and contraction of rigidly fixed pipes under changes of temperature. A 
 turned spigot end of pipe passes through a socket-like joint (reaUy a 
 stuffing box) into the pipe beyond. A gland is fitted around the spigot 
 end and within the stufB.iig box, packed with tow or gasket, to render 
 it steam or water tight. The spigot pipe and gland are, therefore, free 
 to slide one over the other, and so accommodate themselves to the expan- 
 sions and contractions of the entire series of pipes. In a very long 
 series, or where there are several bondings in the series, there will be 
 several expansion joints. (2) The expansion of long boiler tubes is 
 allowed for by a Bowling hoop, or an Adamson's flanged seam. 
 
 Expansion Plates.— See Cut-oif Plate. 
 
 Expansion Bing. — See Expansion Hoop. 
 
 Expansion Rollers. — Rollers placed underneath the ends of long iron 
 girders and roof principals, to allow of freedom of movement under the 
 expansion and contraction due to heat. See also Pipe RoU. 
 
 Expansion Tank. — In apparatus for heating by hot water, the supply 
 cistern is increased in capacity beyond that necessary for actual supply, 
 in order to allow of the expansion of water due to heat without the risk 
 of overflovring. 
 
 Expansion Valve. — The valve or valves used in the steam chest of an 
 engine cylinder worked expansively. "When a single valve only is used 
 and the cut-off effected by the direct adjustment of the eccentric, it is, 
 strictly speaking, an expansion valve, but the term is more properly 
 used to designate an arrangement of two valves, that is a main valve 
 having a cut-off valve (q.v.) behind it. 
 
 Expansive Working. — When steam in an engine cylinder, instead of being 
 allowed to enter the cylinder at full pressure until the termination of 
 the stroke, is out off at some fractional portion of the stroke, and so 
 caused to do work by its own expansion simply, the term expansive 
 working is apphed to it. The steam may be expanded in one only, or 
 in two or more cylinders. See Compound Engine. 
 
 Explosion. — (1) In gas engines the result of the mixture in the presence 
 of heat, of the combustible gases hydrogen and oxygen in definite pro- 
 portions, the hydrogen being the ordinary coal gas, or otherwise derived 
 from the immediate decomposition of some of the hydrocarbons, the 
 oxygen being derived from the air. (2) In steam boilers the result of 
 internal steam pressure exceeding in amount the tensile strength of the 
 boiler plates, or that of their seams. 
 
 Explosion Chamber. — The hinder extension of the cylinder of a gas 
 engine in which the charge is exploded. 
 
 Exponent. — ^See Index. 
 
 Exposure. — The placing of a sheet of ferro-pruasiate, or copying paper 
 (q.v.), in a printing frame, with a negative print in the printing " 
 frame (q.v.), employed in the development of phototypes. The time of 
 exposure varies with the weather and the natiu-e of the print, the blue 
 line phototype requiring less time than the white Hne. In sunshine an 
 exposure of less than a minute suffices for blue lines ; in white line 
 Tinder similar conditions, from five minutes to half an hour. In dull 
 
MECHANICAL ENGINEERING. 133 
 
 weather, for blue lines, from half an hour to three-quarters ; for white 
 
 lines, from one to two hours. Fine cloth tracings copy best, tracings 
 
 next best, paper drawings worst of all. 
 Expression. — A combination or assemblage of algebraical symbols. 
 External Forces. — Forces which act upon bodies, or systems of bodies, 
 
 from without. These are, therefore, the forces which produce strains. 
 Externally Fired. — Applied to those steam boilers which have no internal 
 
 fire box or furnace flue. They embrace the egg-end, balloon, and 
 
 wagon boilers. 
 External Screw, or External Thread. — A screw cut upon the outside of a 
 
 cylinder, therefore a male screw. 
 External Screw Tool. — A screw tool or a chaser of the form adapted for 
 
 cutting external screws. 
 External Thread. — An external screw (q.v.). 
 Extrados, — The back or upper surface of an arch. 
 Eye. — (1) The looped or ringed end of a rod or lever, used as a medium of 
 
 connection with another rod or lever, by means of a joint pin (q.v.). 
 
 (2) The eye of a wheel or pulley is the central hole or bore through 
 
 which its shaft or axle passes. (3) The eye of a furnace is that spot or 
 
 area embraced or commanded by the sight holes (q.v.). 
 Eye Bolt. — A bolt provided with a hole or eye at one end, instead of the 
 
 usual head. The eye is sHpped over a round pin or stud, which receives 
 
 the pull of the bolt. 
 
 F. 
 
 Face.— The face of a cog-wheel signifies the breadth of the teeth ; the 
 face of a belt pulley, the breadth of the rim. The face of an anvil is its 
 upper surface. The face of a casting is that surface which is turned or 
 polished. 
 
 Face Chuck. — A face plate (q.v.) 
 
 Face Lathe. — ^A lathe chiefly or exclusively used for surfaoing(q. v.). These 
 lathes are generally a distinct class, having short beds, or only so much 
 bed as is sufficient to sustain the saddle of the rest ; deep gaps reaching 
 as low as the foot of the bed, or frequently lower stiU, being extended 
 into a deep pit sunk into the floor of the workshop, so that wheels, and 
 rings, turntables, &c., of twenty or thirty feet in diameter, can be 
 turned. 
 
 Face Plate, or Face Chuck. — ^An intermediate metal plate, which is fltted 
 between the mandrel nose of a lathe and chucks of the best class. It 
 is attached to the chuck by screws, or by a taper plug (see Taper Plug), 
 and to the mandrel nose by a screw, or by a taper plug. Often called a 
 flange chuck. But the term face plate is more commonly applied in the 
 shops to the ordinary face chucks, which are provided either with slots 
 for bolts, or with movable dogs or jaws. See Jaw Chuck. 
 
 Face Plate Coupling. — See Flanged CoupUDg. 
 
 Facing. — A portion of a machine elevated above the general surface 
 or area, for the attachment of another piece which has to be bolted 
 thereto accurately. The amount of planing, filing, or chipping neces- 
 sary to produce a fit between the two parts is thereby confined to the 
 exact extent of surface where it is rec[uired, without reference to the 
 general level of the casting, 
 
134 DICTIONARY OF TERMS USED IN 
 
 racing Machine. — ^A centring maclmie (q.T.), wMoli ty tte insertion 
 
 of suitable cutters is employed for the facing of bolt heads, axles, 
 
 studs, &a. 
 racing Sand. — Sand used in iron foundries to line the faces of the moulds 
 
 with a protective coating, in order that the molten metal shall not, by 
 
 combining "with the ordinary sand, form a skin of hard rough sihoate. 
 
 Facing sand is composed of coal dust, mixed with proportions of new 
 
 or unused sand, and black or old sand. It is rammed against the face 
 
 of the pattern, to the depth of about an inch. 
 Factor. — A single number -which is multiplied into another number or 
 
 numbers to form a product. 
 Pactor of Safety. — ^Wlen a calculation of the ultimate strength (q.v.) of 
 
 a structure, or a portion of a structure, has been made, it is necessary 
 
 to provide for contingencies dependent upon inferior material, -wear and 
 
 tear, sudden and unexpectedly applied loads, &o., and this provision 
 
 takes the form of a multiplier, and is called the factor of safety. It 
 
 ■wiU range from four to eight or ten in difBerent classes of work. 
 
 Sometimes termed margin of safety. See App. 
 Fagot. — ^A mass of piled iron prepared in readiness for reheating and 
 
 welding. It is eillier puddled bar of uniform, or of various sections, 
 
 or scrap ; and arranged in definite grouping according to the purpose 
 
 for which the fagot is required. 
 Fagoted Scrap. — The ends, cuttings, orremnantsof VTrought-ironbarand 
 
 plate of the smithy and boiler shop, piled into fagots and welded under 
 
 the steam hammer. It is tougher than ordinary bar and is used for the 
 
 best work. Sometimes called hammered scrap. 
 Fagoting. — (1) The laying of lengths of puddled bar in bundles or fagots 
 
 for the purpose of reheating and rolling. (2) Likewise the making up 
 
 of a fagot (q.v.) of any kind. 
 Fahrenheit. — See Thermometer. 
 Failure. — Materials and structures are commonly said to fail when they 
 
 are unable to endure or accomplish the work for which they were 
 
 selected and designed ; whether they become crippled merely or 
 
 undergo complete fracture. 
 Fair. — This has the same meaning as flush (q.v.). 
 Fairbairn Crane. — A fixed well crane whoso jib is arched in order to 
 
 obtain sufficient clearance beneath for the lifting of bulky loads. The 
 
 section of the jib is that of a box girder (q.v.). 
 Fairlead. — A casting which takes the friction of the rope during the 
 
 mooring of vessels. 
 Fairlie Engine. — See Bogie Engine. 
 
 Fall. — The amount of the descent of water to a mill wheel. 
 Falling Weight. — The dead weight of a steam hanamer tup, piston rod, 
 
 and head, irrespective of momentum or of steam pressure. 
 Falling Weight Test. — A test to which rails and bars are subjected, the 
 
 loads being impulsive loads (q.v.), produced by the faUing of weights. 
 
 Eaila and some test bars are subjected to this test. 
 Fall Pipe. — A drive pipe (q.v.). 
 False Bottom. — The bottom of a loam miU (q.v.) or mortar mill, formed 
 
 of loose plates in order to permit of their removal, when worn out, 
 
 without the necessity of replacing the entire pan. 
 False Core. — A term applied by brass moulders to a drawback (q.v.). 
 False Key. — A turned pin driven into a hole drilled, one half in the end 
 
 of a spindle, and the other half into a boBs, by which it is embraced, 
 
MECHANICAL ENGINEERING. 135 
 
 the centre of the pin 'bemg on the oircimif erenoe of the spindle or shaft. 
 Sometimes it is only put in for a temporary purpose, to be removed for 
 the insertion of a permanent key. Also termed a glut. 
 
 False Water. — When steam is generated very rapidly in a boiler, the 
 immediate effect is a rapid rising of the water level in the gauge cocks, 
 due to the increase iu volume caused by admisture of steam. This 
 sudden increase is termed false water. 
 
 Fan. — A blowing machine, either of rotary or centrifugal type, and used 
 for the production of furnace blast or for ventilation. (See Exhaust Fan.) 
 It is considered better that the fan should be placed eccentrically in its 
 case to allow for the accumulation of an increasing volume of air in the 
 direction of the exit. The disadvantage of a fan in comparison with a 
 blower is that it has to be driven at an excessively high, almost at a 
 dangerous speed, with a great expenditure of motive power ; that its 
 quantity of blast is not so measurable or invariable as that of a 
 blower ; that the friction of its bearings is excessive, and that its 
 working is not so much under control as that of the blower. 
 
 Fang Bolt. — A bolt in which the nut is a triangular plate with teeth for 
 biting into timber, the bolt being tightened by revolving the head and 
 shank. Fang bolts are used for attaching ironwork to wood. 
 
 F. A. S. — lYee alongside ship. Engages to deliver goods on the wharf 
 without extra charge. 
 
 Fast Coupling. — A shaft coupling united in a permanent manner with 
 bolts or keys, as distinguished from loose sliding couplings. 
 
 Fastening Down. — The securing of the various parts of a foundry flask 
 or moulding box together with cottar or screw bolts, to prevent their 
 separation by the liquid pressure of the molten metal. 
 
 Fast Feed. — A quick feed (q. v.). 
 
 Fast Head. — ^A term sometimes applied to the headstock of a lathe, as 
 opposed to the movable head or poppet. 
 
 Fast Pulley. — A pulley which is employed to transmit motion through 
 the medium of a belt to a machine. It is keyed upon its shaft, and is 
 called fast to distinguish it from the loose pulley which is not keyad 
 on, and which simply carries the belt when the machine is not in use. 
 
 -Fathom. — 6 ft. or -001336 of a mile, and equivalent to 1-8287 metres. 
 Chains and ropes are sold by the fathom. 
 
 Fats. — See Oils. 
 
 Fatigue of Materials. — Materials which have been long subjected to 
 severe stiaining actions, or to moderate straining actions often repeated, 
 deteriorate in strength, and will then break under loads which they had 
 previously sustained with safety. This appears to be due to mole- 
 cular change and to the accumulation of permanent set (q.v.) to such 
 an amount as precludes the possibOity of further elongation. In cases 
 where this fatigue has supervened it is customary to subject the mate- 
 rial to a process of annealing by heating to a red heat in a furnace. 
 Crane chains are frequently treated thus, with the result of restoring 
 their lost tenacity. 
 
 Faucet. — The socket (q.v.) of a pipe. A term frequently applied to a 
 water cock of small or moderate size . 
 
 Feather, or Sunk Key. — A parallel key which is partly sunk into a recess 
 in its shaft, so as to form an integral part of the shaft, and over which 
 its wheel or clutch slides. Feathers are used when machine parts have 
 to be thrown into and out of gear, the wheel or clutch being driven by 
 the feather, but having freedom of motion longitudinally. 
 
136 DICTIONARY OF TERMS USED IN 
 
 Taatliermg Board. — See Feathering Float Paddles. 
 
 Feathering Float Paddles. — Paddle-wheels (q.v.) provided with float 
 boards free to move eccentrically in relation to the main wheel, so that 
 the boards shall dip into and leave the water as near as possible in a 
 vertical direction, thus economising power. 
 
 Feathering Screw. — A propeller screw whose blades are rendered movable, 
 so that they can be placed parallel with the line of the keel when it is 
 desirable that the vessel shall sail under canvas alone. 
 
 Feed. — The amount or distance of the transverse of a lathe or other 
 machine cutter taken transversely to the depth of the cut. The term is 
 also applied to the feed gear itself. 
 
 Feeder. — (1) A head of metal cast over a disproportionately heavy part of 
 a casting-, in order to supply the necessary metal to compensate for the 
 sinking in of the heavy section, due to shrinkage. Sometimes called a 
 shrinking head. (2) The opening made in a foundry mould for the 
 introduction of the feed rod. 
 
 Feeder Head. — Head metal. The mass of metal which has been utilised 
 for feeding a mould. See Feeder, Feeding. 
 
 Feeding. — As a mass of molten metal solidifies the outside will set first, 
 the inner continuing fiuid for some time after. As the inner portion 
 cools it will contract, and as a consequence shrink upon itself, leaving 
 a depression on the top outside face. To avoid this evil it is customary 
 to feed the heavier portions of castings by inserting a small metal rod 
 through the runner or riser, as the case may be, and by its motion 
 keep a passage open for the inflow of fresh metal to compensate for the 
 contraction. Feeding is continued until the mass becomes too pasty 
 to allow of the rod being moved any longer. The feeding metal is 
 either supplied in small quantities from time to time by a hand ladle or 
 by having a sufficient mass of molten metal in the head in the first place. 
 
 Feeding Head. — See Feeder Head. 
 
 Feeding Rod. — The rod used for feeding (q.v.), usually J in. or | in. in 
 diameter, and about 3 or 4 ft. long. 
 
 Feed Pipe. — The pipe which conveys the feed water from the feed pump 
 to the boiler of an engine. 
 
 Feed Pump. — (1) A force pump which supplies steam boilers with feed 
 water. (2) A force pump used for supplying gas engines with the 
 necessary supply of air. 
 
 Feed Rod.— See Feeding Eod. 
 
 Feed Screw. — The screw by means of whose rotation through an arc of 
 a circle an exact and measurable amount of feed is imparted to the 
 cutting tool of a machine. 
 
 Feed Tank. — The tank which contains the supply of feed water for a 
 steam boiler. 
 
 Feed Water. — The water used for the supply of a steam boiler. Some- 
 times it is used quite cold, sometimes warmed in a feed water-heater 
 (q.v.). In condensing engines it is warmed in the condenser. As the 
 durability of the boiler depends largely upon the character of the feed 
 water, it should be chosen, if possible, with reference to its softness ,• 
 hard water promoting incrustation (q.v.). 
 
 Feed Water-Heater. — A kind of boiler in which the supply water for a 
 steam boiler is heated, prehminary to being taken up by the pump or 
 injector. It consists usually of an arrangement of tubes enclosed in 
 a cylindrical sheU, the exhaust steam being employed as the heating 
 agent. 
 
MECHANICAL ENGINEERING. 137 
 
 Felt. — Used as a non-conducting' sheatlimg for steam boilers and engine 
 cylinders. It is of a dart brown colour, and consists of the wooEen 
 refuse from paper mills. Felt owes its property of matting, or "felting," 
 to the weU-known jagged character of animal hairs, as seen through 
 the microscope. 
 
 Telting. — The covering of steam pipes with felt to prevent loss of heat by 
 radiation. The felt is either retained in place by coEs of wire, or by 
 wood lagging. 
 
 Female. — The recessed portion of any piece of work into which a dowel 
 or a stud fits is called the female portion. 
 
 Female Screw. — A screw which is cut in a hole or on a hollow surface. 
 
 Female Gauge. — An internal or bored gauge. 
 
 Fence. — A metal plate attached to a saw-bench for the guidance of the 
 stuff edgeways, and the insuring of parallelism in the cut. Fences are 
 made to stand at right angles, but are capable of an angular adjust- 
 ment, or side cant, for bevel sawing. Hence called canting-pieces. 
 
 Fencing In. — The enclosure of machinery and revolving parts, in order to 
 diminish the risk of accidents. Fencing in is compulsory. Belting, 
 gearing, shafts, &o., when they are in proximity to workmen are 
 fenced in. 
 
 Ferric Oxide. — The peroxide of iron, Fe2 O3, is the condition in which 
 iron occurs in the red hsematites, and, combined with water, in the 
 brown htematites. It is also the condition in which the black band 
 and clay band (q.v.) ores are fed into the blast furnace, the carbonate 
 and an atom of oxygen having been driven off by the process of 
 calcination. 
 
 Ferro. — See Ferro-Manganese. 
 
 Ferro-Manganese. — A variety of pig-iron which contains a large pro- 
 portion of manganese. It differs from spiegeleisen in the larger per- 
 centage of manganese present, the term ferro-manganese being applied 
 to those pigs containing upwards of 20 per cent, of manganese. 
 Usually termed ferro, simply. 
 
 Ferro-Prussiate Paper. — See Copying Paper. 
 
 Ferrous Carbonate, — The spathic iron ores, the clay and black band ores, 
 which are by far the most important ores of iron reduced in smelting 
 furnaces, are essentially ferrous carbonates — Fe CO3, that is ferrous 
 oxide, FeO, combined with carbonic acid, CO2, thus, FeO X C02=: 
 Fe CO3. During calcination the carbonic acid is driven off, and partial 
 oxidation taking place also leaves the ore in a ferric condition. 
 
 Ferrous Oxide. — See Ferrous Carbonate. 
 
 Ferrule. — A ring of hoop iron enclosing a round core print, and left in 
 the mould to receive the core. The reason of using a ferrule is to pre- 
 vent the sand from being pushed away by the entrance of the core in 
 oases where the latter is thrust in after the final closing of the mould ; 
 and the founder is therefore not able to see the interior of the mould 
 afterwards in order to ascertain if the core has carried in any sand with 
 its passage downwards. The ferrule prevents the core from coming 
 in contact with the sand and so removes the risk referred to. (2) Rings 
 of hard wood used for holding condenser tubes in their plates. The 
 ferrule fits between the outside of the tube and the hole in the plate, 
 and being swelled by the action of the water renders the tubes 
 water-tight. (3) Rings of metal enclosing and confining the wood 
 around the tangs of edge tools to prevent splitting. 
 
 Fettlers. — The menivhose business it js to clean ofl tbe foundry castings. 
 
138 DICTIONARY OF TERMS USED IN 
 
 They are paid by the piece, from three to five shiUings per ton acoordiag 
 as the castings are heavy or light. There are special rates for brass 
 fettlers. 
 
 Fettling. — (1) The dressing-ofE of castings after they leave the foundry 
 sand, including the chipping off of runners, joint marks, fins and scabs, 
 the cleaning out of cores, and the brushing ef all sand off their 
 surfaces. The tools used are chisels and hammers, files, rods and wire 
 brashes. Also called trimming. (2) The infusible lining or coating of 
 osides of iron employed for the protection of puddling furnaces and 
 purification of the iron. See Bull Dog, Wheel Swarf, &c. 
 
 Fibre. — Malleable iron which has been subjected to the process of rolling 
 develops a fibrous structure, and is stronger in the longitudinal direction 
 than in the transverse, in the proportion of about twenty-three to seven- 
 teen. Yet, though a Ijar of wrought iron will show a distinct fibrous 
 structure if drawn out or bent slowly, it wiU if nicked and broken off 
 sharply show a crystalline fracture, as though the fibre were only deve- 
 loped in the process of bending. 
 
 Fibrous Iron. — Bar iron, whose fibrous texture results from the inter- 
 mixture of layers of cinder, and is therefore a source of weakness and 
 a mark of inferiority. 
 
 Fiddle Drill.— See Bow DrOl. 
 
 Field's Tubes. — Vertical boiler tubes employed for circulation and heat- 
 ing purposes. They are open at the top or water end, and closed at 
 the lower or fire end, are suspended from the furnace crown, and 
 descend into the fire which plays all around them, excepting at the end 
 whence the steam and water have egress. Within the outer, or water 
 tube, a second smaller tube is dropped, being suspended from a conical 
 casting resting in the upper end of the outer tube. The efficiency of 
 Field's tubes depends on the fact that a heated column of water is 
 lighter than a colder column. The heated water rises in the outer tube, 
 and the cooler water descends through the inner one to supply its place. 
 The two waters are prevented from mingUug at the top by the conical 
 or bell- mouthed deflector attached to the top of the inner tube. 
 
 File. — A tool for removing particles of metal or other material by abra- 
 sion, or by the cutting of a multitude of fine points. Files are made in 
 a vast number of sizes, and shapes, and degrees of coarseness, and are 
 cut by hand or by sand blast. See details under special headings. 
 
 File Handle. — A short stout handle, into which the tang of a file is 
 driven. A file handle should be large and globular at the end or heel 
 which fits into the hollow of the hand, as any other shape soon tires 
 the muscles. 
 
 Filing. — The art of filing is such that it can be acquired by practice alone, 
 the difficulty consisting mainly in producing a flat surface, the tendency 
 invariably being to produce one of rounding contour. The economic 
 importance of filing in the shops has been much diminished by the uni- 
 versal employment of planing, shaping, and milling machines, and of 
 emery wheels. 
 
 Filing Block. — A piece of board laid upon a work bench, or held ia a 
 vice, upon which thin portions of metal are laid flat while being filed. 
 
 Filings. — The minute particles of metal abraded by the teeth of a file. 
 
 Filled Bail. — A point rail, or a stock rail, which has one or both sides 
 filled up flush, to give excess of strength to compensate for the cutting 
 away or tapering of the point rail, or the weakness of the stock rail 
 due to the cutting out of the gap for the crossing. 
 
MECHANICAL ENGINEERING. 139 
 
 Fillet. — A term loosely applied to many diverse meanings. HoUotts 
 (q.T.) are often called fillets; mouldings, headings, flanges, cHpping 
 strips, and similar parts are designated thus. In a general way it 
 applies to any thin strips used either for strength or ornament. 
 
 Filling In.— See Box FiUiag. 
 
 Fin. — ^Any thin -wafer-lLke expansion of metal occurring on the side or 
 edge of a larger portion. Fins occur on the joints of castings, and of 
 forgings pressed in dies. 
 
 Final Pressure. — The pressure at which the steam is exhausted, or dis- 
 charged from an engine cylinder. Also called terminal pressure. 
 
 Fine Feed. — The feed of a machine cutter is fine when minute in quantity. 
 
 Fine Grain. — The crystaUisation of fractured metal is fine when the 
 crystals are of small si^e. 
 
 Fine Grit, — A grade of emery wheel, or grindstone, in which the particles 
 are of small size, and suitable for the later and more delicate processes 
 of abrasion. 
 
 Fine Hard. — ^A quality of emery wheel useful for grinding tools, and for 
 light work in general. 
 
 Fine Metal, — Copper matt which results from the fusion of calcined 
 coarse metal with slags and ores. It is called blue metal when it con- 
 tains sixty to seventy per cent, of copper, white metal from seventy- 
 five to seventy-eight per cent., and pimple metal above seventy-eight 
 per cent. See Matt, Refined Iron. 
 
 Fine Pitch. — ^A toothed wheel is said to be of fine pitch when the teeth 
 and teeth spaces are of smaR dimensions. The term is relative. 
 
 Finery. — A puddling furnace (q.v.). 
 
 Fine Soft. — The finest quality of emery wheels (q.v.) used for polishiag 
 brass work, and for sharpening tools. 
 
 Fine Teeth. — The teeth of saws, wheels, files, &o., are fine when of small 
 dimensions, estimated relatively to other teeth. 
 
 Finger. — A narrow projection used as a guide or index in various kinds 
 of work, foundry or otherwise. 
 
 Finished Dimensions. — The dimensions of a piece of work after turning, 
 boring, planing, &o., as distinguished from rough dimensions (q.v.). 
 
 Finishing Cnts. — After the major thiclmeBS of metal has been removed 
 from the surfaces of castings and forgings, it is usual in aU but the 
 roughest classes of work to take a last fine or finishing cut with a 
 scraper or spring tool. 
 
 Finishing EoUs.— See Puddling EoUs, Mill EoUs, Plate MUl. 
 
 Finishing Tools. — Commonly applied to those cutting tools used by metal 
 turners, whose cutting edges are broad and straight, for the removal of 
 the ridges left upon work by the roughing tools (q.v.). They include 
 square and right and left hand side tools, and spring tools. 
 
 Fir. — See Spruce, and Pine Wood. 
 
 Fire Bars. — The grate bars of the furnace of an engine or other boiler. 
 Single gratings would be too large and cumbrous, hence separate bars 
 are used, and replaced as they bum out. 
 
 Fire Box. — That part of a boUer which receives the fuel and the water 
 tubes. It is commonly applied to the furnaces of boilers of the loco- 
 motive type, and to those of vertical form. 
 Fire Box Crown. — The upper plate of the furnace in a vertical or loco- 
 motive boiler. It is flanged, and riveted to the outer plate of the 
 fire box. 
 Fire Box Shell. — The plates composing a fixe box (q. v. ) , The shell is double 
 
140 DICTIONARY OF TERMS USED IN 
 
 in looomotive and portable boilers, comprising inner and outer por- 
 tions, the outer being of iron, the inner, "which is exposed to the fire, of 
 copper, and the two are maintained apart by means of short stays pass- 
 ing through the water space. The sides of the inner shell are tapered 
 upwards to facilitate the disengaging of the steam from the surface, 
 the water space therefore being an iuch or more in width at the upper 
 than at the lower portion. 
 
 Fire Brick. — Fu-e bricks of various shapes are employed for the permanent 
 liniug of cupolas, blast, reverberatory, and other furnaces. Over these 
 is a lining of clay, ganister, or other highly refractory material. 
 
 Fire Brick Arch. — A curved arch set at' an angle to the tube plate of a 
 locomotive fire box in order to deflect the flame before it passes into the 
 tubes. See Brick Arch. 
 
 Fire Bridge. — See Bridge. 
 
 Fire Clay. — Fire clays are very numerous, but they consist essentially of 
 silica, alumina, and water in various proportions. They are found in 
 the coal measures chiefly ; Stourbridge, in Worcestershire, being espe- 
 cially noted for its clays, and from them are manufactured bricks and 
 crucibles for foundry use. 
 
 Fire Door. — (1) A furnace door. (2) The door of a steam bofler through 
 which the fuel and firing irons are iutroduced. 
 
 Fire Flues. — The flues of Lancashire and Cornish boilers. Strictly speak- 
 ing, the front portions of those flues which contain the grate bars. 
 
 Fire Hardening. — See Hardening. 
 
 Fire Hole, — The door of a furnace, or that portion of the grate immedi- 
 ately within the door through which the stoking is effected. 
 
 Fire Tube Boiler. — A multitubular boUer (q.v.) as distinguished from a 
 water tube, or sectional boiler. 
 
 Fire Hole Bing. — A ring of wrought iron encircling the fire hole of a 
 locomotive or portable boiler, and serving to unite the inner and outer 
 fire boxes. 
 
 Firing. — (1) The application to, or the quickening of the source of heat 
 in a steam boiler is termed iiring, or " firing up." (2) The ignition of 
 a charge in a gas engine. (3) A wooden brake is said to fire when the 
 heat of friction produces sparks. (4) A bearing is said to fire when 
 it becomes red-hot. (5) Oil is said to fire when it spontaneously 
 ignites. 
 
 Firing Chamber, or Lighting Chamber. — The small cavity or chamber 
 through which the charge of a gas engine is ignited. At the moment 
 of firing it is shut offi from communication with the outer air. 
 
 Firing Hole. — The door in the side of a reverberatory furnace through 
 which the fuel is introduced to the grate area. 
 
 Firing Tools. — The ordinary tools used in stoking. See Hook, Rake, 
 Slice. 
 
 Firmer Tools. — The ordinary short chisels and gouges of wood workers, 
 so termed in order to distinguish them from paring tools (q.v.). 
 
 First Motion. — A term of general application, as first motion shafts, first 
 motion belts, first motion wheel, &o., meaning the one which iirst 
 receives, and then communicates, power to its successors. 
 
 Fish-bellied Girders and ribs are said to be bellied (q.v.), or fish- 
 
 beUied, when they are curved underneath, the depth of curve increas- 
 ing towards the centre. 
 
 Fish-bellied Girder. — A form of girder, whose under side forms a droop- 
 ing curve, the girder being deeper in the centre than at the ends, 
 
MECHANICAL ENGINEERING. 14 1 
 
 Fish-'bellied girders are usually built up of -wTought-iron plates and 
 angles, and require no trussing. 
 
 Fish Bolt. — A bolt employed for fastening fish plates and rails together. 
 
 Fish Joint, or Fished Joint, — A joint made between raDs through tho 
 medium of fishplates (q.v.)- 
 
 Fish Oils. — Oils used for lubrication, embracing sperm, Tvhale, seal, cod, 
 &c. See Animal Oils, Oils, &c. 
 
 Fish Plate. — A plate of metal covering the butt joints of boilers, rails, 
 and other work. Any plate covering a riveted joint is called a fi.sh 
 plate. 
 
 F. I. T. — Free in truck. Engages to load goods in railway trucks without 
 extra charge. 
 
 Fitter, or Engine Fitter. — A working engineer whose duties consist in the 
 fitting together of machine or engiae parts, after the preliminary stages 
 of turning, planing, drilling, &c., have been accomplished. 
 
 Fitter's Bench. — A stout wooden bench, to which is attached the vice or 
 vices, and a drawer for the reception of tools. The bench is low 
 enough to give a proper working height to the vice jaws. 
 
 Fitting. — That section of mechanical engineeiing devoted to the bringing 
 together and adjusting of the different portions of engines, machines, 
 &c., after they have left the hands of the turners and machinists. In 
 a limited sense, however, the working up and finishing of the smaller 
 portions of metal work which cannot be done in the machines. 
 
 Fittings. — Commonly applied to the essential parts or adjuncts of an 
 engine, or boiler, or machine. Specially applied to boiler fittings 
 (q.v.). 
 
 Fitting Shop, — The shop in which the operations of fitting are carried on. 
 It may occupy a ground fioor, or an upper storey, and may be separate 
 from the machine and erecting shops, or combined with these in one 
 building. Its chief feature consists in the parallel vices bolted to long 
 benches, ranged around the shop against the windows, each fitter 
 having a distinct vice, and separate drawer in which are kept his files 
 and necessary small tools. Each fitter has usually a small surface plate 
 against his vice, and in addition there are large plates in various parts 
 of the shop. These, and a few light wall cranes, and one or more light 
 overhead travellers, nearly complete the equipment of a fitting shop. 
 
 Fix. — The fettling (q.v.) of a furnace. 
 
 Fixed Centre. — A centre whose position is localised in space, in opposi- 
 tion to a movable centre (q.v.). 
 
 Fixed Crane, — A crane set down for use only in one place, in opposition to 
 portable cranes, or those which are constructed to travel. 
 
 Fixed Cutters. — Plane iron cutters of great width set in a box, or shoe, 
 and used for facing, planing, and match boarding. The cutters are 
 fixed in the bed of a machine, and the stuff is pushed over them at a 
 rate of about one hundred feet per minute. 
 
 Fixed Eccentric, — An eccentric sheave fixed upon its shaft, the move- 
 ment for forward or backward gear being given through the link work. 
 Eixed eccentrics have mostly superseded the old adjustable eccentric 
 
 Fixed Expansion. — That expansion which is constant, being due only to 
 
 lap on the valve. 
 Fixed Head. — The head or tool box of a shaping machine, which is 
 
 attached to the ram, and has motion only in the direction of its stroke. 
 Fixed Oils. — See Oils. 
 
I4J DICTIONARY OF TERMS USED IN 
 
 Fized Pulley. — A pulley (q.v.) wliose axis is fixed in space, the pulley 
 revolving thereon. 
 
 name Box. — Sometimes applied to that portion of the shell of a steam 
 boiler which contains the smoke or flame tubes. 
 
 Flame Furnace. — A reverberatory furnace (q.v.). 
 
 Flame Plates. — The top or crown plates of a boiler flue, or fire box. 
 These being exposed to the action of the flame are usually of Low Moor 
 (q.v.) or Bowling (q.v.) iron. 
 
 Flanoh. — See flange. 
 
 Flange. — A rib, or offset on a casting, used either for the purpose of im- 
 parting steadiness of base, or of providing for bolt attachments through 
 holes cast or drilled therein. Cast-iron flanges are also bolted, riveted, 
 or screwed to structures of wrought iron. Occasionally spelt flanoh. 
 
 Flanged Bend. — A bend pipe furnished with a flange at each end. 
 
 Flanged Chuck. — A face plate (q.v.). 
 
 Flanged Coupling. — The ordinary shaft coupling in which the abutting 
 shafts are keyed into the bossed portion of each half coupling, and boltg 
 passing through the flanges maintain the two halves in position. Also 
 called face-plate coupling. 
 
 Flanged Beam. — A rolled beam. See Joists. 
 
 Flanged Girder. — A flanged beam (q.v.). 
 
 Flanged Joint. — See Flanged Seam. 
 
 Flanged Nut. — A nut having a broad flange turned solid with its bottom 
 face. It is used instead of employing a separate washer, its purpose 
 being the covering over of holes of large diameter. 
 
 Flanged Pipe. — A steam or water pipe, which is provided with flanges at 
 the ends as a means of attachment to other pipes or connections. In 
 cast-iron pipes the flanges are a part of the casting. In wrought-iron 
 pipes they are separate castings screwed over the pipe ends upon their 
 outside diameters. 
 
 Flanged Seam. — A seam used in furnace tubes, by which the tubes are 
 materially strengthened, and compensation made for their endlong ex- 
 pansion. It may consist of a ring of "f-ifou riveted to the tube plates 
 on each side. Or it may be formed by the riveting of a ring, arched or 
 corrugated, with a single corrugation in the section ; the flue tubes being 
 attached to narrow borders or flanges spreading out from the base of 
 the arch. Or it may be an Adamson's flanged seam, in which the ends 
 of the flue tubes are curved or dished outwards, and riveted together 
 through an intermediate ring. The first form allows of no endlong ex- 
 pansion. The last two permit of free expansion longitudinally. 
 
 Flanged Socket. — A very short pipe, having a flange at one end and a 
 socket at the other. 
 
 Flanged Spigot. — A very short pipe, having a flange at one end and a 
 spigot at the other. 
 
 Flanged Wheel. — A truck or trolly wheel, having a flange or flanges at 
 the edges to keep it on the rails. It may either have one flange, being 
 then a single-flanged wheel, or two flanges, or a double-flanged wheel. 
 
 Flange Kail. — A flat-bottomed or flat rail, as distinguished from a double- 
 headed rail. 
 
 Flange Washer. — See India-rubber Washer. 
 
 Flanging. — The bending over of the edges of wrought-iron and steel 
 plates to form narrow flanges for the purpose of attachment to other 
 plates, either by riveting or by welding. Flanging is mostly done hot, 
 and the edge is beaten over by wooden mallets or iron hammers, or 
 
MBCtTAmCAL ENGWEERWO. 143 
 
 ■where a quantity of similar work tas to be aooomplislied, in dies, 
 screwed doTvn or squeezed together under a forging press. Hanging is 
 toiler -makers' "work. 
 
 Flanging Hachine. —A machine used for bending over the flanged por- 
 tions of boilers and other built-up structures in wrought iron and steel. 
 These machines are actuated by steam power, or by hydraulic pressure, 
 and the laborious operation of flanging by hand is saved by their em- 
 ployment. 
 
 Flanks. — (1) The sides of wheel teeth lying below the pitch hue. (2) The 
 sides of an arch. 
 
 Flap Valve. — ^A hinged valve, circular or rectangular in outline, and 
 usually made of leather, stiffened with iron or brass plates riveted in 
 each face. Flap valves are used in ordinary Ufting pumps, both in the 
 piston and at tiie suction end of the barrel. The disc valve (q.v.) of 
 an air pump may be considered a flap valve hinged at the centre and 
 lifting aroimd the circumference. 
 
 Flash Flue. — The flue underneath an egg-end, or similar externally 
 fired boiler. 
 
 flashing Point. — The constant temperature at which an oil or fat bursts 
 forth into flame. A good oil should not flash below 500° or 600° F. 
 Some oils flash below 200° F. 
 
 Flask, or Moulding Box. — The frame enclosing the founder's work. The 
 box receives the sand in which the pattern is rammed up, and from 
 which it is withdrawn, leaving the mould ready for the inflow of metal. 
 Flasks are parted into two or more horizontal sections to enable the 
 moulder not only to withdraw the pattern, but to clean and black the 
 faces of the mould. They are held together temporarily while the 
 metal is being poured, by pins passing through lugs cast upon their 
 sides; and the various parts are secured by heavy weights or by 
 cottared bolts. See Fastening Down, and Weighting Down. 
 
 Flat Bar Iron. — Wrought iron of rectangular cross section. Its sections 
 range from 1 in. X i in. upwards. 
 
 Flat Bit Tongs. — Smith's tongs whose jaws are flat and parallel. 
 
 Flat-bottomed Sail. — A railway rail whose base is spread out into a 
 broad flat flange of from 5 in. to 5J in. wide, to be spiked directly to 
 the sleepers, or to be wedged into chairs. When the rail is solid 
 throughout it is termed a Vignoles rail ; when it is arched like a bridge 
 and hollow underneath it is termed a bridge raU. 
 
 Flat File. — A file of rectangular section whose width is greater than its 
 thickness. It is either a tapered or a parallel file. 
 
 Flat Gouge. — One which has the least amount of curvature given to 
 gouges, the amount of curvature varying, however, with the width. 
 See Middle Flat Gouge, Quick Gouge. 
 
 Flat Iron. — See Flat Bar Iron. 
 
 Flat Eammer. — A flat-ended iron tool used in foundries for ramming 
 over large surfaces of sand. It is furnished with a stout handle of 
 three or four feet in length, and the workman, holding this in front 
 of him, with both hands gives repeated blows downwards upon the 
 sand bed, finishing the surface therewith. 
 
 Flat Eope. — See Wire Hope. 
 
 Flats. — Flat Bar Iron (q.v.). 
 
 Flat Sweep. — A flat sweep or curve signifies one which is relatively of 
 less curvature than others with which it may be compared. 
 
 Flatter, — A species of hammer used by smiths. It is like a set hammer 
 
r44 DICTIONARY OF TERMS USED IN 
 
 (q.T.) but broader on the face. It is held by a handle upon the -^ork 
 and struck with the sledge. Its use is to finish over broad surfaces 
 ■which have been brought to size by the sledge and set hammer. 
 
 Flaw. — A crack or incipient fracture in a casting or forging. Flaws are 
 often difficult to detect by inspection alone, but their presence is 
 usually found by ringing with a hammer, as sound metal always has a 
 sonorous ring. 
 
 Flax. — Used for steam packing (q.v.). 
 
 Flesh Side. — The rough side of a leather belt. 
 
 Flexible Ball Coupling. — See Flexible Coupling. 
 
 Flexible Coupling. — The flexible ball coupling consists of two discs 
 attached to the shaft ends, and hollowed on their faces to embrace a 
 ball placed beween the two. Projecting jaws on the faces of each 
 coupling also fit loosely into corresponding recesses on the opposite disc 
 face and drive the shafts. The coupling faces are retained in contact 
 by means of screw bolts passing loosely through them, and rendered 
 flexible endways by elastic washers under their nuts. The coupling 
 with its shafts is therefore perfectly free to turn through moderate 
 angles around the ball as an axis. 
 
 Flexible Crank Shaft. — A crank shaft in which the strains due to the 
 rigidity of an unyielding mass compelled to revolve under conditions 
 of strain due to the want of alignment of its bearings, are reduced and 
 minimised by the introduction of flexible joints in its length. The 
 joints consist of a modification of the flexible ball coupKng, but a bush 
 and ring plate, convex and concave, are introduced instead into the 
 crank web, and so form a flexible pivot or centre around which the 
 straight shafts may rotate through a small angle. 
 
 Flexible Hose. — Piping made either of india-rubber or leather, and used 
 for the conveyance of liquids where metal pipes would be unsuitable by 
 reason of their rigidity. 
 
 Flexure. — See Bending. 
 
 Flitch. — A plate of metal or of wood bolted to an otherwise weak and 
 unstayed beam or structure in order to strengthen and support it. 
 
 Flitch Beam. — A combination beam in which outer timbers enclose a 
 central joist of rolled iron, screw bolts passing through the whole to 
 bolt the members together. 
 
 Flitch Plate. — A broad thin plate or rolled bar used in building up flitch 
 beams and plated work. The width may range from 6 to 24 inches. 
 
 Float. — A buoy which is used to indicate the height of the water, either in 
 tanks or boilers. In ordinary cold-water tanks it consists of a disc, or 
 block of light wood, attached by a piece of jack chain, running over a 
 pulley, to an indicator set in a convenient position for observation. In 
 steam boOers it is made of some heavier substance, as stone or iron, 
 which is unaffected by the liquid, and which is rendered buoyant by 
 the attachment of a counterpoise on the outside, the counterpoise being 
 80 proportioned in reference to the specific gravity of the float as to 
 render it as susceptible to the variations in water level as a float of 
 wood. 
 
 Float Boards. — (1) The rectangular boards attached to the arms of a 
 paddle wheel (q.v.). (2) The boards which receive the impulse of the 
 water in an undershot wheel (q.v.J. 
 
 Float Cut. — This signifies a file having single lines of cutting teeth only, 
 as distinguished from double-cut files, or those with crossing rows of 
 teeth. 
 
MECHANICAL ENGINEERING. 145 
 
 Float Gange. — A water gauge, -where tlie height of water in a steam 
 
 boiler is registered by means of a float (q-v.). 
 Floating. — When the lever of a weigh-bridge or of a testing machine is 
 
 in equal balance it is said to be floating. 
 Floating Derrick. — ^A derrick crane placed on board a floating hull for 
 
 transferring goods to and from vessels, independently of proper wharf 
 
 and dock accommodation. 
 Floating Mill Wheel. — A water wheel, having its bearings in a boat 
 
 moored in the stream of a rapidly flowing river, which turns the wheel 
 
 and performs work for which it is suitable. 
 Flogging Chisel. — A chipping chisel of large size, which is struck with 
 
 a Eght sledge, one man holding the chisel while another strikes. It is 
 
 a tool which is now seldom used. 
 Floor. — The sand bed of a foundry is termed the floor, and the work is 
 
 said to He on the floor, the men kneel on the floor, patterns are bedded 
 
 in the floor, &c. 
 Floor Plates. — Foot plates. 
 Floor Best. — In large pattern-makers' lathes, used for wheels and similar 
 
 work of large diameter, a rest is provided, which is carried on a heavy 
 
 standard, resting upon the floor. The pattern-maker then has more 
 
 control over the work than with the ordinary bed rest. 
 Flour of Sulphur.— Used frequently mixed with sal ammoniac and iron 
 
 borings, for the making of rust joints. Its presence in large quantities 
 
 makes the cement more slowly setting. 
 Flow Gate. — A term sometimes applied to a riser (q.v.). 
 Flowing metals. — Metals of the ductile class which yield to, and change 
 
 their form, under impact, or tensile or compressive strain. Wrought 
 
 iron, mild steel, lead, copper are the flowing metals regarded from the 
 
 point of view of an engineer. 
 Flue. — The flues of boilers are those parts which carry off the smoke 
 
 and waste gases, and produce the draught necessary for combustion. 
 
 Cornish boilers have one, Lancashire boOers two internal flues ; besides 
 
 which they are embedded in brickwork, through which external flues 
 
 are constructed to produce what is called a split draught (q.v.), the 
 
 draught being capable of regulation by means of dampers. (See also 
 
 Wheel Draught.) The copper tubes of a locomotive, or portable boUer, 
 
 and the short stack answer to the flues of ordinary boilers, while the 
 
 action of the blast pipe compensates for the shortness of the tubes. 
 Flue Bridge. — A bridge of brick enclosing a hollow frame of cast iron, 
 
 which passes transversely across a reverberatory furnace between the 
 
 hearth and the stack. 
 Flue Plates. — The ends of a horizontal boiler to which the flues are 
 
 fastened, or the flre-box crowns (q.v.) of vertical boilers. 
 Flue Surface. — The area of the flues of a boiler, as distinguished from 
 
 the grate surface ; being exposed to the action of hot gases, though 
 
 not to actual flame. 
 Flue Tube. — A furnace tube (q.v.). 
 Fluffy. — Timber is said to be fluffy when the sawdust, is stringy, and 
 
 moist or greasy instead of granular and sharp. 
 Fluid. — ^A body or substance which yields to any pressure imposed upon 
 
 it from without, and therefore cannot sustain a longitudinal pressure 
 
 in any direction without receiving corresponding lateral support. In 
 
 fluids at rest the pressure is therefore equal in all directions. Muids 
 
 are either liquids or gases. 
 
 s 
 
146 DICTIONARY OF TERMS USED IN 
 
 riuid Compressed Steel. — See Compressed Steel. 
 
 Fluidity. — The various brands of cast iron possesses different degrees of 
 fluidity when melted. No. 1 Scotch is the most fluid of all, and is 
 therefore used for thin, finely marked and ornamental -work. It is also 
 mixed -with stronger brands to increase their flowing properties. 
 "White iron runs thick and pasty. Metal can be rendered less fluid, as 
 is sometimes desirable, by allowing it to cool in the ladle previous to 
 casting. As a general rule the metal is run hot and fluid for thia cast- 
 ings, cool and thick for heavy ones. 
 
 riuid Pressure. — Pressure is transmitted by fluids in all directions alike ; 
 the transmitted pressure is equal in all directions, and it is directly 
 proportional to the area of the surfaces. 
 
 Flume. — A channel conducting the water to a water wheel. 
 
 Fluor Spar. — A compound of fluorine and calcium, used in some metal- 
 lurgical operations as a flux. Its fluorine combines with silicon, form- 
 ing fluoride of silicon, while the calcium enters into combination with 
 oxygen to form Hme, which again combines with silica to form a 
 sUioate of lime, and is then able to form a flux with the clay and oxide 
 of iron present in the furnace. 
 
 Flush. — Parts are said to be flush or fair when their surfaces are on the 
 same level. 
 
 Flush Bolt. — A bolt whose head is let into a countersunk hole so that 
 its top face stands level with the face of the plate into which it is sunk. 
 
 Flushing Charge. — A charge of air or water swept through the com- 
 bustion chambers of gas engiues to remove the residual gases or products 
 of combustion. Sometimes a displaoer piston is employed instead. 
 
 Flush Topped. — ^A term applied to the firebox casing of a locomotive 
 boiler when it forms a continuous line with the boiler casing instead of 
 being shouldered upward. 
 
 Fluted Eeamer, — A reamer fluted longitudinally, to out at its sides, to dis- 
 tinguish it from a rose reamer or broach (q.v.). 
 
 Flutes. — Grooves, semicircular in section, which are cast in ornamental 
 columns. 
 
 Flux. — The substance thrown into a smelting or a melting furnace for 
 the purpose of combining with those infusible and other matters which 
 require to be separated from the metal, and which alone could not be 
 rendered fluid at the temperature of furnaces. The flux most widely 
 used is limestone in some one of its forms, though with some highly 
 calcareous ores a clayey flux is added. 
 
 Fly. — (1) The loaded lever which actuates the screw of a fly press. (2) 
 Cast iron is said to fly when it breaks through unequal contraction due 
 to bad proportioning, producing internal stresses, or to the effects of 
 cold or of heat acting upon it, or to both in combination. 
 
 Fly Cutters. — Cutters set in a cutter block or chuck held in a lathe or in 
 a facing and chamfering machine, and used for shaping the ends of 
 metal rods presented thereto. The cutting edges are set in a diagonal 
 direction, sloping towards the centre. Also applied in general to any 
 revolving cutters which are used for shaping definite sections, as those of 
 wheel teeth, beads, and other irregular forms whose sections are uniform. 
 
 Fly Nut.— See Wing Nut. 
 
 Fly Press. — A punching machine employed generally for stamping out 
 any thin works in metal, and for pimching and guUeting out sawteeth. 
 The punch is actuated by a vertical screw and lever, the lever being 
 weighted with heavy balls to impart due momentum. 
 
MECHANICAL ENGINEERING. 147 
 
 Fly Wheel. — ^A teavy wheel used in machinery where reciprocal motion 
 is converted into motion of a circular kind. The fly wheel, by absorb- 
 ing some of the ris viva of the machine, carries the disc or crank over 
 dead centres, and also maintains uniformity of motion by alternately 
 absorbing and giving out work. Fly wheels are used with engiaes, 
 pumps, reciprocating or frame saws, jigger saws, &o. 
 
 Foam Cock. — A scum cock (q.v.). 
 
 Foam Collector. — A scum trough (q.v.). 
 
 Foaming. — Priming (q.v.). 
 
 F.O.B. — Free on board. An engagement to deliver goods on board ship 
 without extra charge. 
 
 Foci. — The centres from which the end curves of eUiptical figures are 
 struck. They are set in the transverse axis (q.v.). 
 
 Follower. — A wheel which is driven by another wheel. See Driver, 
 Driven. 
 
 Following Edge. — That edge of the blade of a screw propeller which 
 leaves the water behind it, as distinguished from the leading edge 
 (q.v.). 
 
 Following Joints. — The rings of which cylindrical boilers are buUt, being 
 lap jointed, fit one within the other. Instead, therefore, of being 
 parallel cylinders, they are necessarily frustra of cones, and as the 
 joints all lap in one direction, they are termed following joints. 
 
 Following Steady. — A steady (q.v.) which is attached to the back of the 
 side rest of a lathe, and which embraces the work behind or after the 
 tool and follows it along with the rest. See Back Steady Rest. 
 
 Foot. — (1) A base or flange which sustains a casting or structure. (2) A 
 common standard of measurement. 
 
 Foot Board. — See Treadle. 
 
 Foot Brake. — A brake which is applied or released by means of a lever 
 actuated by the pressure of the foot. 
 
 Foot Bridge. — An arched bridge which carries a footstep bearing. 
 
 Foot Drill. — A light drilling machine driven by a treadle (q.v.). 
 
 Foot Lathe. — A light lathe of from three to six inch centres, driven from 
 a treadle and crank actuated by the foot. Foot lathes are seldom 
 employed in engineers' shops, and then only for special classes of work, 
 models, &c. 
 
 Foot Lever. — A lever worked by the pressure of the foot alone. Foot 
 levers, as a rule, are provided with a balance or counterweight to throw 
 back the lever automatically when the pressure of the foot is with- 
 drawn, and the part on which the foot presses is flattened out and 
 roughed up to prevent slipping. 
 
 Foot Pound. — ^A unit of work used in calculations, signifying one pound 
 lifted one foot high. See Units. 
 
 Foot Step, or Footstep Bearing. — ^A bearing closed at its bottom end, 
 to sustain the end thrust of a vertical shaft or spindle. It is, therefore, 
 a bearing socket, called also a step, and toe step. Footstep bearings are 
 sometimes made adjustable by placing the beiring in the centre of a 
 ring casting provided with a bridge carrying a set-screw below and 
 four set-screws around the ring. By slackening and tightening the 
 set-screws, the bearing is adjusted both sideways and vertically. 
 
 Footstep Bearing. — See Footstep. 
 
 Foot Ton. — A unit used in calculation, signifying one ton lifted one foot 
 high. See Units. 
 
 Foot Valve. — The lowermost valve in a piuup. 
 
148 DICTIONARY OF TERMS USED IN 
 
 F.O.B. — lYee on rail. Signifies the placing of goods on the rail-way with 
 out extra charge. 
 
 F.O.T. — Free on truck. The same as F.I.T. (q.v.). 
 
 Eorce. — The power or cause which impresses or tends to impress motion 
 on matter. 
 
 Torced Draught. — Forced draught is used on steamers, with or without the 
 employment of the closed stokehold (q.v.). The latter, however, permits 
 of a better and equable regulation of the forced draught, which is then 
 compelled to pass into the furnaces. The draught is fed by a fan or 
 fans, and the pressure is equal to about IJ in. of water. The advantage 
 of the adoption of forced draught is that large ventilating pipes on 
 deck can be reduced greatly in size, and the supply of air be rendered 
 nearly imiffirm under all conditions of weather and wind. 
 
 Force de Cheval. — See Cheval Vapeur. 
 
 Force, moment of. — The moment of a force is the product of the force 
 into the perpendicular distance of its direction from a given point. The 
 moment represents its effect or leverage on a body moving about the 
 given point. 
 
 Force Pump. — A pump in which the water is lifted by the force due 
 to atmospheric pressure acting against a vacuum, but in which it is 
 expelled again by a plunger ram instead of by a bucket. The back- 
 ward motion or withdrawal of the plunger in its cylinder produces a 
 vacuum into which the water rushes ; then, by the forward motion of 
 the plunger, the aperture through which the water entered is closed by 
 a foot valve (q.v.), and the water is forced out through an upper or 
 delivery valve. Also termed a plunger pump. 
 
 Fore Carriage. — The framing or bogie which carries the two front wheels 
 of a portable engine. 
 
 Fore Gear Eccentric. — See Forward Eccentric. 
 
 Forehearth. — That portion of the hearth of a blast furnace which lies to 
 the front of the hearth proper, beneath the tymp arch and behind the 
 dam plate. 
 
 Foreman. — The individual who has charge of a department of work. In 
 engineering factories there are foremen of pattern-makers, moulders, 
 fitters, turners, erectors, smiths, boiler-makers, carpenters, and la- 
 bourers. A working foreman is one who divides his time between 
 supervision and «uanual labour, and is therefore little more than a 
 leading hand. Foremen are always recruited from the ranks. 
 
 Fore Plane. — ^A plane intermediate in size between a jack and a smoothing 
 plane. 
 
 Fore Plate. — A plate extending ia front of the bottom roughing and 
 finishing roUs used in puddling, to receive the shingled bloom from the 
 bogie on which it is brought to the roUs. 
 
 Forge. — (1) The structure upon which a smith's fire is built, consisting; 
 of hearth, tuyere, chimney, bonnet, water and coal troughs. Forges 
 are either fixed or portable, and are either made whoUy of iron, or of 
 iron and brick combined. (2) Also applied to the mill where the rolling 
 of puddling bar is carried on. 
 
 Forgeahility. — The capacity of a metal for being drawn down and 
 worked into a definite shape on the anvil. See Red Short, Cold Short. 
 
 Forge Crane. — Similar in type to a foundry crane (q.v.). 
 
 Forged Scrap. — The odds and ends of wrought-iron scrap in a smithy 
 are commonly reheated and balled up under the steam hammer into 
 slabs for use. This is economical not only because of the saving in 
 
MECHANICAL ENGINEERING. 149 
 
 material and the superior quality of the scrap over new bars, but also 
 because tlie men are able to make it a stock job during times of tempo- 
 rary slackness of orders. 
 
 Forged Work. — Work in wrought or malleable iron, as distinguished 
 from founder's or cast work. 
 
 Forge Fire. — (1) A smith's fire. (2) A puddling furnace (q.v.). 
 
 Forge Pigs. — Pigs of iron most suitable for puddling purposes, consisting 
 of the white irons in which the carbon is entirely in the combined 
 condition. 
 
 Forge Soils. — The train of rolls by which slabs and blooms are converted 
 into puddled bars. 
 
 Forge Scale. — The flakes of black oxide of iron which form rapidly on 
 malleable iron exposed at a red heat to the action of the air. It is 
 called forged scale because it accumulates at the smith's forge, being 
 struck off on the anvil. 
 
 Forge Test. — A bending test applied to plates of wrought iron and steel. 
 The plates are bent both hot and cold, and also with and across the 
 grain ; and the angles to which they are to be bent in each case with- 
 out fracture are mentioned in the specification relating thereto. Plates 
 of Lowmoor and Bowling iron are often excepted from forge tests, their 
 brands being sufficient guarantee of their quality. A good boiler plate 
 of any thickness should bend hot with the grain to an angle of 125° 
 without fracture, and across the grain to an angle of 100°. If bent 
 cold, a \ in. plate should bend to 35° with the grain, and 16° across. 
 
 Forge Train. — The series of puddle rolls employed for rolling out shingled 
 bloom after it leaves the steam hammer. The rolls are grooved in 
 diminishing series, and their action is reversed when two roUs only are 
 employed, or the driving power is in one direction, when three high 
 roUs are used. Termed puddling-roUs, as distinguished from mill- 
 rolls (q.v.). 
 
 Forging. — (1) The art of making forged, or smith's work. (2) The work 
 produced by the smith. 
 
 Forging Machine. — A machine in which an upper row of stamps, ham- 
 mers, or dies is actuated by eccentrics upon a single power-driven 
 shaft. Fixed dies are set below, corresponding with those on the 
 upper row, and between these work is swaged into shape. The 
 dies and stamps can be changed at pleasure. Sometimes called a bolt 
 machine. 
 
 Forging Press. — (See Hydraulic Forging Press ) The advantages of a 
 forging-press over a steam hammer are, that being lower it permits of 
 the use of overhead travelling cranes, is less likely to break down, its 
 action being quiet, and is therefore less expensively kept in working 
 order. 
 
 Fork. — See Strap Pork. 
 
 Fork Chuck. — See Prong Chuck. 
 
 Forked Connecting-Eod. — A connecting-rod having a forked end (q.v.), 
 so that the cross head is enclosed by it, instead of being itself enclosed, 
 as in the solid- ended form. 
 
 Forked End. — The end of a lever, or of a connecting-rod, is forked when 
 it bifurcates or divides into arms, in order to receive the end of another 
 lever or rod within its bifurcation, the two being connected with a 
 joint pin (q.v.). 
 
 Forked Strap. — The cleft end of a pump-rod, which embraces the end of 
 a wooden rod or spear. 
 
I JO DICTIONARY OF TERMS USED IN 
 
 Formation level. — The level of the tops of the embankments and bottoms 
 of the cuttings of a railway upon, -which the ballast is laid. 
 
 Former, or Copy. — The templet used for the cutting of wheel teeth, and 
 other works in copying machines. 
 
 Formula. — ^An arithmetical or algebraical assemblage of figures, letters, 
 signs, and symbols, arranged in a conventional manner, by means of 
 which, processes of calculation are obvious by simple inispection without 
 verbal explanation. 
 
 Forward Eccentric. — The eccentric which opens the slide valve to steam 
 when the engine is to run forward. Sometimes called fore-gear 
 eccentric. 
 
 Forward Gear. — An engine is said to be in forward gear when the eccen- 
 trics, slot Unks, and levers are arranged for the running forward of the 
 engiae. 
 
 Fouling. — (1) The incrustation of steam boilers, and steam and water- 
 pipes with scale. (2) The interference of machine or structural parts 
 generally with each other, hindering their action ; being due to errors 
 in design or in construction. 
 
 Foundation Bolts. — Bolts employed for holding or screwing down base 
 plates, beds, steps, machines, cranes, engines, pumps, and similar work 
 to the foundations in which they are to be held. Also termed hold-down 
 bolts. 
 
 Foundation Cylinder. — (1) The foundations of fixed cranes (q.v.) are often 
 laid in concrete, where the natural soil is not sufficiently rocky to sus- 
 tain the upward puU. The concrete is sometimes enclosed in a cylinder 
 of cast iron sunk in the ground, and termed a foundation cylinder. (2) 
 Foundation cylinders are used for sinking into the beds of rivers for the 
 support of bridge piers. They are made in cast iron, having internal 
 flanges for bolting together. Their length is about equal to their dia- 
 meters, which may measure four, six, or eight feet. 
 
 Foundation Ring. — A foundation cylinder (q.v.). 
 
 Foundations. — See Machine Poundations. 
 
 Founding. — See Moulding. 
 
 Foundry. — The shed or workshop in which the operations of moulding and 
 casting are carried on. It is usually confined to a ground floor covered 
 to a depth of about two feet with sand, and furnished with cranes, 
 boxes, sand bins, the necessary tools, drying stoves, and cupolas ; 
 the latter being without the building, but having their tap holes open- 
 ing within the wall. Brass foundries are smaller, and their appli- 
 ances are hghter in character, and the furnaces are within the build- 
 ing. 
 
 Foundry Crane. — A crane employed in foundries for lifting about mould- 
 ing boxes, ladles of metal, cores, &c. The framework is of timber or 
 wrought iron. The jib stands horizontally, and carries a block carriage, 
 the post makes a right angle with the jib, and takes the gearing whose 
 shafts revolve in cast-iron cheeks bolted thereto, and the thrust beam 
 makes an angle of about 45° with the post and jib. Large foundry 
 cranes are centred at top and bottom in shoes or steps in which they 
 also swivel, and stand in the centre of the shop. Small cranes are 
 attached to the foundry walls. Por the lightest class of work small 
 cranes are made without footsteps, being simply hinged to the wall in 
 order to leave the floor space clear for work. In large foundries, over- 
 head traveUing cranes are superseding the old fixed cranes. 
 
 Foundry Ladle. — See Ladle. 
 
MECHANICAL ENGINEERING. 151 
 
 Foundry Mould. — See' Mould, Moulding, and details under tieir head- 
 ings. 
 
 Foundry Pig. — ^Foundry pigs are those suitable only for maMng castings, 
 being grey or mottled, as distinguished from forge pig (q.T.). 
 
 Foundry Pit. — A large and deep pit sunk in a foundry floor, and lined 
 "with cast-iron plates, or bricks. Used for the reception of moulds 
 which have to be placed on end for the purpose of sound casting. Foun- 
 dry pits are either sand pits, or open pits. Open pits are simply 
 circular flat-bottomed excavations in the foundry floor for the recep- 
 tion of moulds which require no support, beyond that afforded by the 
 flasks ; and -which, having no sand rammed around them, are called 
 open. They are used merely for the convenience of keeping the pour- 
 ing gate low enough down to receive the molten metal poured from the 
 crane. The walls of pits are built of stone, brick, or iron. Sand pits 
 are so termed because the mould is of so weak a character as to require 
 the support of sand rammed around in the space between it and the 
 walls of the pit. All pits must be quite dry. 
 
 Foundry Sand. — The material into which molten metal is run in order to 
 impart the definite outlines required in castings. Sand is used in pre- 
 ference to other substances because its refractory nature resists the 
 destructive influence of metal at high temperatures, because its porosity 
 permits of the free escape of the gases generated in casting, and because 
 of its compact and adhesive nature by virtue of which it can not 
 only be moulded into any shape, but is also able to resist great liquid 
 pressure. The more silica present in the sand, the greater its suitabjlity 
 for foundry purposes ; alumina and magnesia should also be present in 
 small quantity. The sands employed in moulding are those from the 
 coal measures and the new red sandstone, also from the greensand and 
 chalk. The sands are named according to the localities in which they 
 are found, as London, Belfast, Falkirk, Worcester, Cheshire ; or red 
 yellow, green, according to their colours. Foundry sand is always 
 rammed damp, though sometimes dried, before the pouring of the metal. 
 See also Green Sand, Dry Sand, Core Sand, Coal Dust, Facing Sand, 
 Parting Sand, Silica, &c. 
 
 Foundry Stove. — See Drying Stove. 
 
 Four-Cutter Machine. — ^Machines for planing wood, having four sets of 
 cutters, one top, one bottom, and one on each side, for planing all 
 four faces of the stufE at once. 
 
 Four-Cylinder Engines. — Compound engines in which two cylinders are 
 high and two low pressure. 
 
 Four- Way Cock. — k. cock having four branches. 
 
 Foxey. — Timber is said to be foxey when there ia an excessive proportion 
 of green sapwood present in it. 
 
 Fraction. — A part of anything. A vulgar fraction is represented by two 
 numbers, one placed over the other, the one above the line being the 
 numerator, the one below the denominator. A proper fraction is one 
 whose numerator is less than its denominator, an improper fraction one 
 whose numerator is greater than its denominator. A mixed number con- 
 tains integer and fraction combined. A decimal fraction is one whose 
 denominator is done away with, a dot, the decimal point, being placed 
 before the numerator, and placing a figure to the right of the dot makea 
 the fraction a tenth of what it was before. The denominator is always, 
 therefore, 10, 100, 1,000, or some other power of ten. 
 
 Fractional Pitches, — The pitches of screw threads which are not aliquot 
 
152 DICTIONARY OP TERMS USED IN 
 
 parts of the inch, and therefore not directly divisible by, or into, the 
 pitch of the leading screTV in the length of one inch. To obtain the 
 change wheels for cutting these screws it is necessary to multiply the 
 integer and the number which represents the pitch of the leading 
 screw by the denominator of the fraction, thus : Supposing it were 
 required to cut a screw of 6 J threads per inch with a leading screw of 4 
 
 threads to the inch, we have — j. X 4 = — and deduce the change 
 
 wheels (q.v.) then in the ordinary way ; as, for instance, by factors 
 
 16 4X4 40 X 40 
 
 —. r= , , = — — , and thence get wheels in an ordinary train 
 
 25 6 X 5 50 X 50' ® ^ 
 
 40 X 20 
 which are not equals — — — , and these will cut the fractional pitch. 
 ^ 50 X 25' ^ 
 
 Irame Saw. — See Bow Saw, Deal Prame. 
 
 Framing The skeleton of a locomotive which sustains the boiler, 
 
 machinery, and axles. It is a plate framing, when plates of sheet iron 
 are used in its construction, a bar framing when iron bars are employed. 
 The latter type is seldom used in England, but it is the American practice. 
 
 Free Burning Coal. — Non-caMng or but slightly caking coals. Anthra- 
 cite is difficult to bum, but the anthraoitic and the semi-bituminous 
 coals bum easily. 
 
 Free End. — In a cantilever the end which is not fixed is always desig- 
 nated the free end. 
 
 Free Piston Gas Engine. — A form of gas engine in which the piston is 
 driven in an upward direction by an explosion of gas and air in a 
 closed cylinder below. As the pressure of the gas diminishes with its 
 increase of volume, the piston descends by the weight of the atmo- 
 sphere pressing upon it. This is known as Otto and Langen's patent, 
 but has mostly fallen into disuse. 
 
 Free Sand, — Sand used in the making of foundry cores or moulds. Being 
 free or open, it permits of the escape of the gases, and requires little 
 venting. 
 
 Freezing Point. — The temperature at which water passes into the solid 
 state. It is determined by placing a thermometer in a vessel con- 
 taining pounded ice or snow well moistened with water. The latent 
 heat (q-T.) of the mixture prevents alteration of the temperature until 
 the ice is all melted, or the water all frozen. It corresponds with 
 32° F. or 0° C. 
 
 French Curves. — Curves or sweeps out in thin pear wood. They are 
 radial, but of varying sweeps, blending together, and are used for 
 laying on drawings in order to obtain curves which will present a 
 graceful appearance without the trouble of drawing them by hand. 
 They are made in useful sets of a dozen each. 
 
 French Horse-Power. — See Cheval Vapour. 
 
 Fretting. — The abrasion of the edge of a cutting tool in the process of 
 sharpening on an oil-stone. 
 
 Friction. — The resistance to motion which is set up when two rough 
 surfaces are moved one over the other. The amount of friction is inde- 
 pendent both of the rate of motion of a body and of the extent of 
 surfaces in contact. 
 
 Frictional Gearing. — See Friction Gearing. 
 
 Frictional Resistance. — In a general sense, the resistance of surfaces due 
 to friction. Specially applied to the resistance to slipping of riveted 
 joints by the contraction of the rivets. 
 
MECHANICAL ENGINEERING. 153 
 
 rriction Block. — A brake block (q.v.) or any block of ^00(1, the friotional 
 resistance of whose surface is utilised in the arrestiug of motion. 
 
 Friction Brake. — See Dynamometer, Brake. 
 
 Friction Clutch. — A friction ooupUng (q.v.). 
 
 Friction, Co-efficient of. — This signifies the ratio het-n^een the perpendicular 
 pressure, or the load, and the friction existing between surfaces in con- 
 tact. Thus the friction divided by the load gives the co-eflBcient, and 
 from the co-efficient multiplied by the load the friction can be deduced. 
 The co-efficient may be expressed in lbs. per ton necessary to move 
 a load, or as a vulgar fraction. But it is customary to employ 
 decimal numbers. The co-efficient of friction is denoted by the Greek 
 letter fi. 
 
 Friction Coupling — Consists essentially of discs or rings of wood, or metal, 
 or both combined, whose surfaces are brought into close contact by 
 screw pressure. The commonest existiag forms are bevelled ; that is, 
 they form frustra of cones fitting one to the other ; sometimes also an 
 internal split metallic ring is pressed outwards by a lever agaiast a re- 
 cess bored in an encircling plated ring. 
 
 Friction Disc. — ^A contrivance similar in principle to cone gear, but in 
 which frictional surfaces are substituted for toothed gearing. A pair 
 of revolving discs, and furnished with a limited movement also 
 longitudinally with their axes, enclose a smooth turned wheel whose 
 axis is at right angles therewith. This last wheel is keyed to a spindle 
 but receives no motion save through the disc wheels, and then only when 
 contact is made by moving the inner face of one or the other disc wheels 
 into contact with the periphery of the fspiudle wheel. Evidently the 
 shaft of the disc wheels moving in one direction, the effect of bringing 
 first one and then the other disc into contact is to cause the driven 
 wheel and spindle to rotate in opposite directions. This form of gearing 
 is conveniently used for reversing the motion of traversing cranes. 
 The working faces of the discs are blocks formed of alder or other suit- 
 able wood held in place with a bevelled retaining ring. 
 
 Friction Gearing. — (1) Gearing, whose driving force is produced by the 
 friction only of the peripheries of the wheels. The driving faces are 
 either of wood, or millboard, or leather. This gearing is seldom used, 
 being unsuitable for the transmission of much power. (2) In some 
 forms of this gearing the wheels are provided with turned rings and 
 grooves on their circumferences which are the counterparts of each 
 other, and in which, therefore, the amount of bite is increased, 
 
 Friction Hoist. — A light hoist driven by the friction of the smooth turned 
 surfaces of pulleys, the proportion between the diameters of the pulleys 
 being the same as though toothed gearing were employed, so that their 
 velocity ratios still depend upon their relative diameters. 
 
 Friction of Motion. — The power required to keep a moving body in 
 motion. This is less in quantity than the friction of repose (q.v.V 
 
 Friction of Bepose. — The power necessary to set a body moving from a 
 state of quiescence. This is greater in quantity than the friction of 
 motion (q.v.). 
 
 Friction Bing. — A loose elastic metaUio ring used in some forms of 
 friction clutches. It is divided in one portion of its circumference and 
 pressed outwards against a female portion by means of a lever. 
 
 Friction Boilers, or Friction Wheels.— Small rollers which revolve in 
 bearings, and sustain an axle in the depression formed by the contiguity 
 of the upper portion of their peripheries. They are used for light 
 
154 DICTIONARY OF TERMS USED IN 
 
 ninnmg macHnery, as the crank axles of lathes. In these there is no 
 sliding friction (q.v.). 
 
 Friction Strap Brake. — See Strap Brake. 
 
 Friction Wheel. — ^Any wheel which drives or is driven hy friction, as 
 when contact only takes place between smooth or gTooved surfaces 
 without the intervention of teeth. 
 
 Front Top Rake.— See Top Rake. 
 
 Frosting. — Ornamental scraping performed for the sake of good appear- 
 ance only, by a series of light finishing cuts performed at different 
 crossing angles to reflect the light at those angles. It is done either 
 with a scrape, or with a bit of oU-stone, and is performed on most light 
 machines and engine parts exposed to view. It is so shght in amount 
 that it does not affect the truth of the surface in the least degree after 
 the scraping proper is completed. 
 
 Frustrum. — The solid included between two transverse sections of a cone 
 or wedge, or parabolio figure ; the sections being taken at different 
 heights. 
 
 Fnels. — Fuels play an important part in engineering processes, both in 
 the first smelting of the metal and in subsequent remeltings, puddling, 
 the heating of steam boilers, &c. Fnels are soHd, as coal, coke, and 
 charcoal, or liquid, or gaseous, or patent fuels. 
 
 Fulcrum. — The point on which a lever turns. 
 
 Fulcrum Plate. — In an ordinary lift pump worked by hand and attached 
 to a back board, the metal plate which receives the stud about which 
 the handle moves is called the fulcrum plate. 
 
 Full. — (1) A workshop term which signifies that a dimension is slightly 
 larger than it should be, but to so slight an extent that it is to be 
 detected by calipers rather than by rule measurement. (2) The full of 
 an eccentnc is the portion of the sheave which is situated at the 
 greatest distance from the crank shaft upon which it is fixed. 
 
 Full Bore. — See Full Waterway. 
 
 Fullering. — The process of forming grooves in smith's work, both as 
 simple grooves merely, and as a series of grooves for flattening out a 
 surface. Also a mode of caulking adopted for boiler plates, which, 
 however, differs from cauHdng proper in that the whole of the edge 
 of the plate is hammered or burred over instead of a portion of the edge 
 only. Fullering is less likely to groove the face of tite adjoining plato 
 than the ordinary caulking. 
 
 Fullering Tool. — A round-faced smith's tool used for fullering. See Top 
 Fuller, Bottom Fuller. 
 
 Full Gate, — ^When the governor or regulator of a turbine is opened to its 
 full extent so that the whole width of the vanes is utilised for the 
 reception of the water, and the turbine works to its limit of efficiency, 
 it is said to be at fuU gate. 
 
 Full Gear. — In an engine furnished with reversing gear when the die 
 blocks are at either of the extreme ends of the slot links, so that the 
 valves are set in their extreme positions for forward or backward 
 running, the engine is said to be in fuU gear. If worked in any other 
 position of the die blocks excepting mid-gear (q.v.), the position is de- 
 noted by the fractional portion of the cut off, as J, f , f , I, &c. 
 
 Full Shrouding. — See Shrouding. 
 
 Full Size. — A term used to distinguish drawings made to the actual size of 
 the work which they represent, from those made to a smaller scale. 
 The term full size is usually written on the sheet. 
 
MECHANICAL ENGINEERING. 153 
 
 Full TlirC/ad. — A screw thiead wHoli is out clean and sHarply to its 
 proper depth, instead of being merely scratched into a fractional depth 
 only. 
 
 TuU Waterway, or Full Bore, or Full Way. — A waterway is said to be 
 full when the area of the opening- given in the valve or plug, as the case 
 may be, is equal in extent to the area of the suction bore. 
 
 Full Way.— See FuU "Waterway. 
 
 Fully Divided Scale. — A scale (q. v. ) used for dravring purposes on which 
 all the primary divisions are subdivided. See Open Divided Scale. 
 
 Fundamental Circle, or Base Circle.^ — A curve which is rolled over by a 
 generating circle in the production of cycloidal curves, used in the 
 striking of wheel teeth. 
 
 Funnel. — The furnace chimney of a marine engine, built of sheet iron 
 plate riveted together. Its area bears a definite proportion to the engine 
 power. 
 
 Furnace. — A general term which may signify any structure in which 
 metal is melted, refined, or remelted. (See Air, Blast, Reverberatory, 
 Brass, Steel, Puddling Furnaces, &o., and Cupola.) Also an engine or 
 other fire. 
 
 Furnace Bars. — See Fire Bars. 
 
 Furnace Grate. — See Grate. 
 
 Furnace Hoist. — A light hoist used for elevating the metal, fuel, and 
 limestone to the platform of a cupola or melting furnace. 
 
 Furnace Lining. — A coating of refractory material used as a pro- 
 tection between the casing of a furnace and the intense heat of the 
 fuel. The linings vary with the classes of furnaces. Cupolas arerelined 
 with fire clay or sand at every hghting of the fire. Blast furnaces are 
 lined with a refractory fire clay ; converter bottoms are lined with 
 ganister, or with magnesian limestone, the lining being removed at 
 every few heats, or from about five to ten. The liuing bums away 
 most rapidly round the tuyeres (q.v.). See Fettling, Tuyeres. 
 
 Furnace Shell. — The shell (q.v.) of the furnace, or fire box, of a steam 
 boiler. 
 
 Furnace Tube. — The tube within which the fuel is enclosed in an internally 
 fired boiler (q.v.) . 
 
 Furring Tip. — The partial closing of steam or water pipes by the deposi- 
 tion of solid matters which were previously held in suspension in the 
 steam or water. 
 
 Furrowing. — See Grooving. 
 
 Fusibility. — The readiness with which metals pass from the solid into the 
 liquid condition. 
 
 Fusible Alloy, — An alloy so compounded as to melt at a definite and low 
 temperature. See Fusible Plug. 
 
 Fusible Plug. — A plug composed of soft and easily melted metal or aUoy 
 inserted in a brass casing which is screwed into the furnace crown of a 
 steam boiler, and which melts when the water level falls as low as that 
 of the crown, and so allows of the escaping water and steam to ex- 
 tinguish the fire and to give timely notice of the shortness of water. It 
 melts at a low red heat. 
 
 Fusing Point. — The temperature at which a metal or an alloy melts; 
 potassium comes lowest, platinum highest in the scale. 
 
1S6 DICTIONARY OF TERMS USED IN 
 
 G. 
 
 G. — In meolianioal and mattematloal calculations G- stands for the force of 
 graTity (q^.v.) at any particular latitude. It may be defined as a number 
 expressing- the velocity produced in a falling body in imit of time, or a 
 number expressing twice the distance through -which a body falls in 
 unit of time ; or a number expressing the -w-eight of the unit of mass 
 in absolute measure. 
 
 Gab. — A hook, or open notch, in a rod or lerer, -which drops OTer a 
 spiadle, and forms a temporary connection between valve or other 
 motions. 
 
 Gable. — The outer ends of the cranked portion of a crank shaft. Dressing 
 this do-wn square is termed cutting the gable. 
 
 Gab Lever. — Generally any lever which is connected up by means of a 
 gab. Specifically the lever which forms the connection between the 
 slide valve spindle and the eccentric rod in some forms of marine 
 engine valve. 
 
 Gage. — See Gauge. 
 
 Gager. — See Gaggers. 
 
 Gaggers, or Gagera. — Short conical or pyramidal projections, cast upon 
 core plates and the plates for loam moulds, to assist the adhesion of the 
 loam. The term is sometimes applied also to lifters (q.v.). 
 
 Gain. — Although no machine, actual or ideal, can give out more work 
 than is actually put into it, yet it is customary when speaking of 
 mechanical exchanges to use the term gain, or mechanical gain, when 
 one form of energy is exchanged for another. 
 
 Galena. — The most important ore of lead. It is a sulphide, that is, a. 
 compound^ of lead -with sulphur — Pb S, containing eighty-six and a 
 half per cent, of lead. It occurs in veins, has a metaUio lustre, and 
 a dark colour, and is very hea-vy. Sp. gr. 7-5. It is found abundantly 
 in various parts of England, Scotland, Spain, Saxony, and the United 
 States. Argentiferous galena is an ore from which silver can be 
 profitably extracted, though it may contain bat two parts of silver in 
 the thousand. 
 
 Galloway Boiler. — A horizontal, internally fired boiler, which is a 
 modification of the Lancashire boiler. The two flues pass at their hinder 
 end into a broad single flue containing a number of Galloway tubes 
 (q.v.) arranged in a vertical manner, which absorb the heat from the 
 flues, and so increase the efficiency of the boiler. The hinder flue in 
 boilers of more recent construction has its upper and lower curved 
 faces struck from a common centre. The Galloway tubes may number 
 thirty or more, according to the size of boiler. 
 
 Galloway Tubes. — ^Water tubes of a conical form longitudinally, circular 
 in cross section, and flanged outwards at the ends ; placed across the 
 tubes of Lancashire and Cornish boilers to increase the circulation and 
 the heating surface, and also as a secondary consideration, to assist in 
 staying the tubes. 
 
 Galvanic Action. — The action upon one another of electro -positive and 
 electro-negative metals, causing wasting away of the positive metal. 
 It is particularly noticeable where iron and copper, or zinc and copper, 
 or brass and iron, are in contact in the presence of acidulated water. 
 
 Galvanized Iron.— Iron, which after ha-ving undergone preliminary 
 
MECHANICAL ENGINEERING. 157 
 
 cleansing, has been dipped in a bath of molten zinc. The process has 
 nothing to do with galvanic action. 
 
 Galvanizing. — The coating of iron with a film of molten zinc. 
 
 Gamboge. — The yellow colour used to indicate brass and gun metal on 
 drawings. 
 
 Gang Saws. — ^A number of saws arranged in parallel positions in a swing 
 frame (q..T.). Used for sawing logs, or balks of timtjer, into planks and 
 boards. 
 
 Gangne. — Is a term applied to the earthy matter of iron and other ores. 
 It consists chiefly of clay. 
 
 Ganister. — A refractory material used for the lining of Bessemer 
 converters (q.v.), and of steel moulds. It consists of a highly siliceous 
 material cemented with fire clay ; the silica equalling about ninety 
 per cent. 
 
 Gantry. — The trussed beams, or the girders, as the case may be, which 
 carry the crab, or crane, in overhead travelling cranes. 
 
 Gantry Crane. — An overhead travelling crane carried on a gantry (q.v.). 
 
 Gap Bed. — A lathe bed having a portion recessed out in front of and 
 below the headstock, to receive work larger in diameter than the height 
 of the lathe centres, under ordinary conditions, wiU allow of. The 
 bed is strengthened correspondingly below the gap. The gap, when not 
 in use, is filled up with a gap bridge (q.v.) 
 
 Gap Bridge. — The piece of casting or the bridge which closes up the gap 
 of the bed of a lathe, when not required for use. 
 
 Gap Lathe. — A lathe provided with a gap bed (q.v.). 
 
 Gas. — A fluid (q.v.) which possesses the property of indefinite expan- 
 sion in all directions, so that it immediately fills any vessel into which it 
 is introduced (see Liquid, Boyle and Marriott — law of) . A perfect gas 
 is one which expands at a uniform rate with uniform increase in 
 temperature. Saturated vapours do not absolutely fulfil the conditions 
 of perfect gases. 
 
 Gas Coke. — The soft coke which results from the dry distillation of coal 
 in gas works. It is too friable for use in cupola furnaces, but owing to 
 its cheapness it is employed in the drying stoves in foundries. 
 
 Gas Engine. — A general term denoting any motor which is actuated by 
 the explosive force generated by the compression and subsequent 
 ignition of gaseous compounds. Commonly, coal gas and air are 
 employed, but various hydrocarbons have also been made use of. In 
 gas engines the extremes of temperature are greater than in steam 
 engines, hence under suitable working conditions the greater should be 
 the duty obtainable from them. 
 
 Gaseous Tuel. — See Producer Gas. 
 
 Gaseous Mixture. — The charge (q.v.) of a gas engine. 
 
 Gaseous Steam, — Superheated steam (q.v.) . 
 
 Gas rnmace. — See App. 
 
 Gasket. — Plaited rope well greased with tallow, and used for the packing 
 of stuffing boxes and pistons in engine and pump work. 
 
 Gas Flyers. — Two-jawed tongs, usually having two sizes of serrated or 
 grooved circular holes, for the holding or gripping of gas pipe which 
 is being manipulated. 
 
 Gas Ports. — The inlet passages by which the gas obtains access to the 
 cylinder of a gas engine. 
 
 Gas Producer. — A gas- making furnace in which coal gas is obtained by 
 the distillation of fuel for the special purpose of heating ingot and 
 
158 DICTIONARY OF TERMS USED IN 
 
 otlier furnaces. The gas is mixed with air before being burnt. See 
 
 Producer Gas. 
 Gas Pump. — A small force pump used ia some gas engines for forcing gas 
 
 into the combustion chamber. 
 Gas Regenerator. — The regenerator (q.v.) through -which producer gas 
 
 passes on its way to the furnace hearth, in a reheating or a steel-melting 
 
 furnace. It is smaller than the corresponding air regenerator. 
 Gas Slide, — The slide valve of a gas engine, by means of which the access 
 
 of gas to the combustion chambers is regulated. 
 Gas Stocks and Dies. — Taps and dies made specially for cutting gas 
 
 threads, beiag of a finer pitch than engineers' stocks and dies. 
 Gas Tap. — See Gas Stocks and Dies. 
 Gas Thread. — A screw thread of fine pitch, employed for wrought iron 
 
 and brass tubes. 
 Gas Tongs. — See Pipe Tongs. 
 Gas Tubing. — See Wrought-irou Pipe. 
 Gate. — (1) The orifice by which molten metal is poured into a mould. 
 
 (2) The annular opening through which the water passes into the vanes 
 of a turbine (ci..t.). 
 
 Gauge. — (1) The distance between the inner edge of rails or tramways, 
 or permanent way. It ranges from IS inches to 7 feet. (2) A term 
 apphed to a multitude of measuring tools. (See Cutting, Cylindrical, 
 Marking, Mortice, Pressure, Screw, Vacuum, and Wire Gauges.) 
 
 (3) Mixed gauge refers to the laying down of two lines of rails — a broad 
 and a narrow gauge — side by side. The instrument by which the 
 distance between rails is measured, is termed a gauge. It is a bar of 
 iron having two ofi:sets at right angles to the bar, the distance between 
 the offsets, which lies between the rails, giving the gauge. 
 
 Gauge Cocks. — The cocks attached to the upper and lower portions of the 
 water gauge npon a boiler, and which are opened periodically to test 
 the freedom or otherwise of the water passage from obstruction. 
 
 Gauge Glass. — A stout, well-annealed glass tube, attached to the front of 
 an engine boiler to indicate the height or level of the water within. 
 Unions above and below, with cock attachments, connect the glass tube 
 with the steam and water spaces respectively, and allow of either con- 
 nection being shut off in case of a glass becoming broken. 
 
 Gauge Plate. — An adjustable plate fixed to shearing, cropping, and cut- 
 ting-off machines, for insuring the uniform length of short pieces of 
 bar or plate which are to be cut off in large numbers. 
 
 Gauge Rod. — A rod of iron from J in. to J in. in diameter, and used for 
 measuring the internal diameters of portions of work in cases where 
 great accuracy is essential. Thus, when internally fired cylindrical 
 steam boilers are being subjected to the hydraulic test, it is usual to 
 gauge the internal diameters of the flue in various portions of the cir- 
 cumference, to ascertain if there be any material distortion, or tendency 
 to assume an oval shape xmder pressure. Also, when shafts have to be 
 turned to fit the eyes of wheels or pulleys, or pistons have to be turned to fit 
 engine cylinders, the pulleys, wheels, or cyhiiders being away from the 
 workshop, gauge-rods are filed to fit the bores exactly, and the shafts or 
 pistons turned to the lengths of the rods. The ends of the rods are filed 
 oft tapered, or nearly to a point, to afford a very narrow point of con- 
 tact only. 
 
 Gear. — A term of very general application, signifying arrangements of 
 toothed wheels, valve motions, pump work, ropes, lifting tackle, &o. 
 
MECHANICAL ENGINEERING. 159 
 
 Gear Cutters. — Cutters of hardened steel formed on the edge of a circular 
 disc whose section is that of the tooth spaces which they are intended 
 to cut. Sometimes a single cutter is set in a revolving block. See 
 Mining Wheels. 
 
 Gear Cutting. — The formation of the teeth of wheels by means of revolving 
 cutters. 
 
 Geared Brace. — See Geared Hand DriU. 
 
 Geared Chuck, — A form of universal chuck (q.v.). 
 
 Geared Engine. — An engine in which gearing is interposed between the 
 crank shaft and the first-motion shafting, either for the purpose of 
 increasing power and diminishing speed, or the reverse. 
 
 Geared Fly Wheel. — A fly wheel furnished with teeth on its periphery. 
 Used with Corhss and other engines. 
 
 Geared Hand-Drill, or Geared DriU, or Geared Brace. — A form of drill- 
 stock held against the breast, but in which the drill is revolved by a 
 pair of bevel-wheels worked by hand. 
 
 Geared Headstock. — A headstock provided with back gear (q.v.). 
 
 Geared Ladle. — A safety ladle (q.v.). 
 
 Geared Pump. — A pump which is driven by an engine through the medium 
 of gearing, usually with a reduction of speed. 
 
 Gearing. — This has the same general meaning as gear (q.v.), but is more 
 properly applied to gear-wheels (q.v.). Gearing, or to gear a wheel, 
 also signifies the driving in and working of the wooden cogs of mortice 
 "wheels. 
 
 Gearing Chain. — See Pitch Chain. 
 
 Gearing Down. — Signifies the reduction of speed from a prime mover to 
 the mechanism which it actuates, by the intervention of gear wheels, 
 with, of course, an accompanying gain in power. 
 
 Gear 'Wheel. — ^Any form of toothed wheel, as distinguished from running 
 wheels, pulleys, fly wheels, friction wheels, &o. 
 
 Geat. — ^A gate (q.v.). 
 
 Gedge's Metal. — Aich metal (q.v.). 
 
 General Drawing. — ^A complete drawing of an engine or machine, iu 
 which many matters of detail may be omitted but iu which the main 
 outlines of its construction are apparent. 
 
 General Joiner.^A combination machine used in wood-working. It is 
 furnished with saws and cutters for sawing, planing, tenoning, mould- 
 ing, boring, grooving, and all the ordinary operations of the workshop. 
 
 Generating Circle. — The circle, which rolling upon a fundamental circle 
 (q.v.), generates, by means of a point iu its circumference, a cycloidal 
 curve. Used in the striking out of wheel teeth. 
 
 Generating Surface. — Heating surface (q.v.). 
 
 Geometrical Mean. — The geometrical mean of two numbers is obtained by 
 multiplying the two numbers together and extracting the square root 
 of the product. 
 
 Geometrical Progression. — See Progression. 
 
 Gib. — The fixed portion of the gib and cottar arrangement, in which the 
 bearing is kept in place by a loose strap end. The gib is the portion 
 provided with hook ends, whose function is to prevent the straps from 
 spreading or opening out. See Cottar. 
 
 Gib and Cottar. — See Cottar, Gib. 
 
 Gibbet. — The triangular framework of a crane, consistrng of post, jib, 
 and strut. 
 
 Gib-Headed Key. — A key having a set-off standing at right angles with 
 
i6o DICTIONARY OF TERMS USED IN 
 
 the tMcker end, for oonvenienoe of drawing it back in situations where 
 the use of a drift is not practicable. 
 
 Giffard's Injector. — See Injector. 
 
 Gimbal Joint. — A Hooke's joint. See TTniTersal Joint. 
 
 Gimlet. — A boring tool which prepares the way for the entrance of wood 
 screws. Its point is that of a taper screw and its body that of a cylin- 
 der having a spiral groove, hence called a twist gimlet ; or a hollowed, 
 nearly semi-cylindrical shell, called therefore a shell gimlet. 
 
 Gimp Nail. — A gimp pin. A small, round-headed upholsterers' naU, useful 
 to pattern-makers for fastening pattern letters to name-plates (q.v.). 
 
 Gin. — A rude portable, yet effective, hoisting machine, the well-known 
 tripod form, from whose apex the pulleys and gin-block (q.v.) for Hft- 
 ing are suspended for working heavy tackle. A barrel and winch are 
 fixed between the two legs which form the shears. 
 
 Gin Block. — A siagle-sheave pulley of a hoUow-rim section, having its 
 bearings in a skeleton frame suspended from a hook. A rope is passed 
 over the pulley, one end of which is held by a man, the load being 
 attached to the end opposite. There is thus no gain in power but only 
 an alteration in the direction of m6tion. Called also whip-gins, rub- 
 bish pulleys, monkey wheels. 
 
 Gin Pulley. — The pulley of a gin block (q.v.). 
 
 Girder. — A beam, usually of timber or of cast or wrought iron, used for 
 supportiug a superstructure. Girders are of various sections, the com- 
 moner^form, when in cast iron, having a section like the letter I, in 
 which, however, the bottom flange where the metal is in tension is 
 much wider than the top. In wrought iron, the Warren, or trussed 
 girder, is that usually employed. Girders act as levers in which, the 
 cross sections being the same, their strength is in inverse proportion 
 to their length, but the conditions of strength vary with the mode in 
 which the load is distributed, and with the way in which the ends of 
 the beams are fixed. (See Beams, Relative Strength of.) Girders are 
 imderstood to be subject to transverse or bending strains only. 
 
 Girder Stays, or Eooflng Stays. — Used to stiffen the fire-box roofs of 
 locomotive and portable boilers. Two plates of wrought iron are riveted 
 together at a little distance apart, distance pieces being interposed to 
 allow of the passage of bolts between, and then placed edgeways across 
 the fire-box roof. From these, bolts provided with clip-washers depend, 
 and are fastened iaside the fire box. There wUl be several such stays 
 on the roof, at a pitch, or distance apart, of about 4 in. ^Formerly a 
 thicker solid plate, pierced with holes for the bolts, was employed, but 
 is superseded by the lighter buUt-up girder. Girder stays rest on the 
 fire box only near the ends, so that there is a hollow water space of 
 about 1 in. in depth underneath them, which permits of circulation and 
 prevents the accumulation of deposit and burning of the fire-box crown. 
 
 Girt. — The circumference of round timber. 
 
 Girth.— The circumferential measurement of a rope is termed the girth. 
 
 Git. — A gate (q.v.). 
 
 Give.— A joint, riveted or otherwise, is said to give, when it slips, or 
 slides, or breaks away. 
 
 Gland. — The small casting which closes the mouth of the stuffing box in 
 engines and pumps, and deceives the wear of the piston rod. When 
 the rod is in place the sorewiag down of the gland presses the packing 
 close around the rod, and prevents leakage of steam or of water. 
 
 Gland Bolt.— A stud bolt (see Stud) which has a bearing collar or flange 
 
MECHANICAL ENGINEERING. l6l 
 
 turned upon it. It is sore-wed down until the lower shoulder of the 
 coUar bears against the flange or face of the stuffing box. Sometimes 
 called a pillar holt. 
 
 Crland Cock, — A plug cock, in which the plug is packed with a gland over 
 it. These are superior to the common plug cocks. 
 
 Glass. — Broken glass is sometimes used as a flux for hard gun-metal. 
 
 Glass Barrel Pump. — See Acid Pump. 
 
 Glass Gauge. — See Gauge Glass. 
 
 Glass Paper. — The abrading and smoothing material used by wood workers. 
 It is made from crushed bottle glass, sifted to assort it iuto sizes ; the 
 powder is then dusted through a sieve on to stout paper, one of whose 
 surfaces is moistened with glue. Formerly sand was the material em- 
 ployed, hence the term sand-paper. 
 
 Glass-papering Machines. — Machines for glass-papering the surfaces of 
 wood-work. They consist, in one form, of a table underneath which 
 revolves a cylinder around which the glass-paper is rolled, and which 
 projects just above the surface of the table through a slit. The work 
 in being slid over the table is brought into contact with the periphery of 
 the cyhnder. In the other form the glass-paper is attached to a disc 
 revolviag at the end of a radial movable arm, and the work being laid 
 upon a table imderneath, the disc is brought to bear upon any portion 
 of the surface where it may be required. 
 
 Glass-paper Bnhber. — See Eubber. 
 
 Glazed Pig.— See Blazed Pig. " 
 
 Glazing. — The filling up of the interstices of the surface of a grindstone 
 or emery-wheel with the minute abraded particles detached ia grind- 
 ing. The surface has then a smooth and polished appearance, and 
 ceases to out efficiently. Glazing arises from several causes, as an in- 
 sufficient supply of water, or the griuding of substances for which the 
 nature of the stone or emery-wheel is unsuitable, or from bringiug so 
 broad a surface to be ground that the abraded particles are imprisoned 
 thereby, and forced or squeezed between the rigid particles composing 
 the stone or wheel. 
 
 Glenboig Brick. — A ih:e-brick used for regenerative furnaces. 
 
 Globe Valve. — A valve whose casing is of a spherical shape. Sometimes 
 called diaphragm valve, because an annular valve seating contained 
 within parts the chamber into two portions. The term globe valve 
 relates only to its outline ; its applications are numerous, but they are 
 chiefly those of a stop or regulatiug valve. 
 
 Glue. — ^A cement for wood made by boiling down the intestines of animals. 
 Russian glue is the best. It is prepared for use by boiling with water, 
 the glue contained in an inner vessel, being surrounded by the water 
 contained in an outer vessel. See Marine Glue, Glue Cement, Hydraulic 
 Glue. 
 
 Glue Cement. — A waterproof cement used for attaching paper labels to 
 castings which are to be shipped abroad. It is composed of glue, four 
 parts, boiled oil one part, oxide of iron one part. The whole well 
 boiled and mixed, and applied while hot. 
 
 Glue Heater, — A tank, or water bath, containing steam and hot water, by 
 means of which glue is heated and kept warm iu the workshop. 
 
 Gluing. — (1) The art of gluing consists in malring a good joint of the 
 surfaces in apposition, then after the application of the glue to rub 
 out all that can be rubbed out by moderate pressure, combined 
 •with sUdiug motion, before setting the joint. (2) The sticking of oil 
 
 M 
 
i62 DICTIONARY OF TERMS USED IN 
 
 in . and about bearings, due to its oxidation or drying. Also termed 
 gumnmig. 
 
 Glue Pot. — The double vessel used intbe preparation of glue. It consists 
 of an outer pot containing the boiling -water, and an inner one contain- 
 ing tbe glue. The glue is thus never aUowed to become burnt, which 
 burning would impair its adhesive property. 
 
 Glut. — A gun-metal bloci having a face hollowed out to fit against the 
 bossed-up end of the valve-rod in a knuckle joint, and by which the 
 wear is continually being taken up, the glut being tightened by a wedge 
 and screw, or by a cottar. See also False Key. 
 
 Glutting — The choking, or partial stoppage, of engine cylinders and 
 passages, and of condenser tubes, with a carbonaceous deposit from 
 inferior oils used in lubrication. Animal oils, including tallow, 
 suet, and lard, are found to produce both glutting and corrosion, the 
 decomposition of the fats causing the formation of fatty acids, and the 
 deposition of carbon. These objections do not apply to the use of 
 mineral oils. 
 
 Glycerine. — (1) Glycerine is used for mixing with pipeclay (q.v.) in making 
 models of ornamental castings, when it is desirable that the clay shall 
 not set too quickly. (2) Glycerine is also the basis in lubricating oils. 
 
 Goliath Crane, — A crab mounted on a gantry, which gantry is attached 
 to end standards provided with flanged driving wheels, so that the 
 whole structure travels bodily upon rails laid upon sleepers ; the dif- 
 ference between a goliath and a traveller therefore is, that the former 
 travels in the mass while the latter travels only to the limited extent 
 permitted by the end beams. Gohaths, Uke travellers, are worked both 
 by hand and by steam power. 
 
 Goose Neck. — The bent rod by which the tap hole in a casting ladle is 
 opened and closed. 
 
 Gorge. — ^A term sometimes applied to signify the groove of a sheave 
 pulley in which the rope or chain runs. 
 
 Gouge. — Gouges are either long paring, or short firmer tools, the former 
 being ground on the inner or hollow curve, the latter on the outer or 
 convex face. They range from ^ in. to 2 in. in width. Smith's gouges 
 or ' ' hollow sets ' ' are curved tools embraced by the ordinary withy 
 handles, and struck by the sledge hammer. 
 
 Gouge Bit. — A bit used for boring holes in wood. Its cross section is that 
 of a gouge, and it is simply rounded at the cutting point, without 
 having a nose or lip. 
 
 Gouge Slip. — A thin slip of oil-stone, whose edges are rounding in cross 
 section for the purpose of abrading the internal or hollow faces of 
 gouges when sharpening. 
 
 Governor. — A piece of mechanism by which the speed of a steam engine, 
 or turbine, or water-wheel, or other motor is regulated. The forms of 
 governors vary much, but the essential principle is that of heavy balls 
 caused to rotate by the motion of the engine, and which by the opera- 
 tion of central forces open or close a throttle valve. See Pendulum 
 Governor, Crossed -arm Governor, ParaboUo Governor, High-speed 
 Governor, Weighted Pendulum Governor. 
 
 Governor Arms. — The rods which are attached to the governor sleeve on 
 the one end and to the governor balls on the other. 
 
 Governor Balls. — Suspended, freely revolving balls of oast iron, through 
 whose centrifugal force the opening of the throttle valve of nn engine 
 cr other motor is regrulated. 
 
MUCRANtCAL ENGINEERING. :6j 
 
 Governor Cut-off. — See Automatic Expansion. 
 
 Governor Sleeve. — The hollow cylinder wMch slides vertically on a gover- 
 nor spindle and carries the governor arms. 
 
 Governor Spindle. — The vertical pillar or spindle wMch carries tte gover- 
 nor sleeve, and around vrhich it revolves. 
 
 Governor Valve Gear. — The arrangement of valve gear throngh whicli 
 governors are made to regulate the opening and closing of the induc- 
 tion valve in automatic expansion (q..v.). 
 
 Grab. — A form of dredger bucket used in the minor and more local opera- 
 tions of excavation. It consists of two half buckets meeting in the 
 centre, and actuated by an arrangement of chains, and hooks, and other 
 special tackle, in such combinations that the grab closes on the earth, 
 and the jaws bite the more firmly the harder the upward pull of the 
 chains. Also the grab being lifted and coming in contact with a ring 
 or other arrangement suspended overhead, it is automatically opened 
 and discharges its contents. Grabs are half tine or whole tine accord- 
 ing [to the length of the steel jaws with which they are furnished ; 
 they are termed buckets simply when there are no serrations, but only 
 smooth meeting edges ; the former are used for rocky and gravelly and 
 stiff mud bottoms, the latter for soft mud and grain. 
 
 Grade. — (1) A term often applied to the steps of belt pulleys. (2) The 
 various commercial qualities of irons and steels. 
 
 Gradual Load. — ^A load gradually applied to a structure, and which 
 therefore furnishes the most favourable condition of stress. 
 
 Grain. — (1) The arrangement of the woody fibres in timber. With the 
 grain, signifies longitudinally in the course of the fibres as the tree 
 grows. Across the grain, signifies a transverse section. Crooked grain, 
 or cross-grain, denotes a wavy and interlacing condition of the fibres ; 
 open - grain, wood of a soft and rapid growth ; close grain, the 
 reverse ; harsh grain, coarse and gritty in nature. (2) The grain of 
 iron signifies the disposition of its crystals and laminae, and we may 
 say in some cases its cinder or scale. The grain of timber runs in the 
 direction of its growth; that of iron is irregular when cast, fibrous 
 when rolled, the fibre being developed in the direction of the rolling. 
 The grain of wood and of rolled iron are alike strongest in the direction 
 of their length. Boiler plates are rolled in the direction of their length 
 for this reason. The forge test (q.-v.) also recognises this difference of 
 grain. 
 
 Grain EoUs. — ^KoUa made of a tough quality of cast iron not chilled, to 
 distinguish them from chilled roUs. 
 
 Grain Side. — The hair or smooth side of a leather belt. With a smooth 
 tirmed pulley this should be used as the driving side, since it makes a 
 closer fit with the rim, to the consequent exclusion of air. 
 
 Grain Tin. — Refined tin of purest quality, which is obtained by heating 
 the ingots and allowing them to fall from a height, when they break 
 up into irregular prismatic fragments. Grain tin is used in tin-plating. 
 
 Gramme, or Gram. — The standard French measure of weight. It is the 
 weight of a cubic centimetre (q. v. ) of pure water of the temperature of 
 4° C, taken at Paris. It is equivalent to 15-4323 English grains. 
 
 Granular Iron. — Bar iron which shows a granular fracture due to the 
 absence of cinder, and is therefore a guarantee of its strength and 
 parity. 
 
 Granulated Copper.— See Matt. 
 
 Graphic Methods. — The methods employed for ascertaining strains upon 
 
164 DICTIONARY OP TEAMS USMD W 
 
 etruottires, velocity ratios, and such like, ty the laying down of lines 
 to a uniform scale. Used to distinguish it from the mathematical and 
 geometrical methods of ohtaining similar results. 
 
 Graphic Statics. — See Graphic Methods. 
 
 Graphite. — Carbon in an uncombined state. It is found in most 
 abundance in the grey variety of cast iron, and is readily distinguished 
 on the face of a fractiu'e, as flakes, or crystals, darker in colour than 
 the metal, and distributed over its surface. 
 
 Graphitic Carbon. — See Carbon, Graphite. 
 
 Grasshopper Engine. — A term applied to an old and scarce type of beam 
 engine, in -which the working beam, instead of being pivoted at the 
 centre, is pivoted at one end. The connecting-rod is thus attached at a 
 point midway between the pivoted end and the end which is actuated by 
 the piston-rod ; and the friction on the pivot is correspondingly reduced. 
 
 Grate. — The area which contains the burning fuel in the furnace of a 
 steam-engine boiler, or of a reverberatory furnace, or air oven. 
 
 Grate Area, or Grate Surface. — The area in square feet covered by the 
 fire-bars of an engine boiler. That is, equivalent to the area over 
 which full combustion can take place in consequence of the due access 
 of air to the fuel. As a very broad rule, one foot of grate area per 
 nominal horse-power is allowed in Cornish and Lancashire boilers. It 
 is usual to estimate the grate area in relation to the weight of coal 
 burnt ; hence, it becomes the reciprocal of the rate of combustion. 
 Cornish and Lancashire boilers, with good draught, will require '07 
 square feet per lb. of coal, while locomotives will only require '01 square 
 feet per lb. 
 
 Grate BarB. — Fire-bars (q.v.). 
 
 Grate Surface.— See Grate Area. 
 
 Grating. — The perforated plate in a foot valve, or air pump, whose 
 function is to prevent the entry of solid matters along with the water. 
 
 Graver. — A hand tool for metal-turning, formed of a square bar, and 
 ground from one of the edges to an angle of about 45°. This gives two 
 cutting faces of 60° each, right and left respectively, in addition to the 
 point formed by the angle of the bar and the face. 
 
 Gravity — The force which draws all bodies towards the centre of the earth 
 or to its surface, in a direction perpendicular to that surface. 
 
 Gravity Wheel. — A water-wheel in whish the weight of the water alone 
 is utilised ; the water resting in the buckets until discharged. Over- 
 shot wheels (q.v.) are gravity wheels. 
 
 Grease. — See Tallow. 
 
 Grease Axle Box. — See Axle Box. 
 
 Grease Box. — The upper portion of an axle box (q.v.), which is made the 
 receptacle for the grease used in lubrication. 
 
 Grease Cock. — A cup, with pipe, and stop cook, screwed into the cover or 
 body of an engine cylinder, and which receives and regulates the supply 
 of grease used for the purpose of lubricating the piston. 
 
 Grease Cup. — An oil cup (q.v.). 
 
 Greasy Steam. — Steam which becomes its own lubricant by a mechanical 
 admixture of grease therewith. The grease is mingled with the steam 
 before its entry into the cylinder, by means of an impermeator (q.v.) 
 fixed on the steam chest. 
 
 Green Coal. — The small coal newly laid on a smith's fire. 
 
 Green Heart. {Neotandra Sodiai.) — Sp. gr. 1-05 to 1-09. A hard, tough, 
 a id rigid timber, of the natural order Lauracea, used largely in 
 
MECHANICAL ENGINEERING. 165 
 
 engineering worka. It Ls imported from Britisli Guiana, and is of a 
 yellowish, or greenisli-yellow colour, and very durable. A cubio foot 
 ■weighs from 65 to 68 lbs. 
 
 Green Sand. — Ordinary foundry sand moistened with water and not 
 dried, aa distinguished from dry sand (q.v.) and loam (q.v.). 
 
 Green Sand Moulding. — The moulding of work from patterns, in green 
 sand (q.v.). See App. 
 
 Green Wood. — Timber from which the sap has not been removed by 
 seasoning and drying. 
 
 Grey Copper Ore. — An abundant ore of copper, containing copper, iron, 
 sulphur, antimony, and arsenic, in variable quantities. It is mined in 
 Cornwall and Frieburg. 
 
 Grey Iron. — Pig, or cast iron, which, on being fractured, has a grey 
 coarsely crystalline structure. It is a moderately strong and very 
 fluid iron, suitable for fine castings, and for admixture with scrap, to 
 produce a good, tough, and very strong quality for ordinary foundry use. 
 
 Grid. — (1) A skeleton-like frame of cast iron, which is used to carry a 
 core, or drawback, or some other portion of a mould. (2) The grating 
 of an air-pump valve. 
 
 Gridiron Valve. — A type of slide-valve in which the ports are subdivided 
 transversely by narrow bars or bridges, the ports in the cylinder face 
 being similarly subdivided also, the object of the divisions being to 
 obtain the necessary steam-way with a diminished amount of travel 
 of the valve. Gridiron valves may be double ported (q.v.), or treble 
 ported (q.v.). 
 
 Grinder. — (1) Any appliance by which work is shaped or finished by 
 grinding. Usually it is applied more particularly to lead-laps and 
 emery-wheels rather than to actual grindstones. (2) The workman who 
 has the emery-wheels of a workshop, and their special work, under his 
 charge. 
 
 Grinding. — The abrasion of metallic surfaces on a grindstone, or emery- 
 wheel, or lead-laps, or grinders. Grinding is resorted to not only for 
 the roughest but for the finest works, not only to remove metal in 
 quantity but to render more accurate work which has already been 
 shaped carefully in lathes and other machines. AU cutting tools are 
 ground, so also are lathe mandrels and cylindrical gauges. Grinding, 
 especially since the introduction of emery-wheels, occupies a higher 
 economical importance in the workshop than ever. 
 
 Grinding Clamps. — A divided lap (q.v.) used for grinding mandrels and 
 cylindrical holes. The halves of the clamps are capable of adjustment 
 by means of set-screws. See Grinder, Grinding, &c. 
 
 Grinding-in, — The bringing of the conical bearing surfaces of plugs and 
 cocks of a circular shape to an exact fit by means of emery-powder. 
 The powder is strewn over the surfaces along with a little oil, and is 
 made to abrade them by turning the plug through portions of a revo- 
 lution, each two or three successive turns commencing at difi:erent 
 starting-points in the circle in order to make the wear more equable. 
 
 Grinding line. — A line marked along the twist of a twist-drill, coincident 
 with its axis, as a guide to the grinder in maintaining the cutting point 
 in exact position. 
 
 Grinding machines. — Machines of various types employed for the abrasion 
 and shaping, and truing-up of metaUic surfaces, emery-wheels of 
 various qualities being the grinding agents. Spindles and mandrels 
 are ground while revolving between centres by means of a revolving 
 
166 DICTIONARY OF TERMS USED IN 
 
 and traversing wheel, or a lap ; surfaces are ground while being 
 traversed underneath a revolving emery-wheel. Irregular works ara 
 ground whilst held against ordinary wheels mounted on spindles. 
 Taps and cutters of various kinds are also treated in these machines. 
 
 Grinding Rest. — A support, or a guide, for a cutting tool during the 
 process of grinding on a stone. In the turning or fitting shop it 
 generally consists of a bar, or a bridge, of square iron, laid across the 
 top of the water-trough in front of the stone, and upon which the 
 tools are laid. For grinding wood-cutting tools various forms of rests 
 have been devised, but except for the knives of rotary cutters workmen 
 do not hold them in much value. See also Twist Drill Grinder. 
 
 Grindstone. — A revolving stone against which tools and materials are 
 abraded by grinding. Grindstones are natural sandstones, Newcastle 
 being the best ; they are also artificial compositions. Grindstones 
 revolve in troughs containing water, but should not run actually in the 
 water, as that softens them and causes them to wear unequally. The 
 water should be fed on to them from a drip-can. For ordinary tools 
 they should make about 90 or 100 revolutions per minute. 
 
 Grindstone Truer. — Grindstones are trued, or turned up, by hand by 
 means of a pointed bar of steel, which is constantly rotated to present 
 a new cutting point to the stone. Grindstones are trued mechanically 
 by means of a threaded roller of steel, clamped in a frame and allowed to 
 rotate against the surface of the stone. 
 
 Grip Chuck. — A jaw chuck (q.v.). 
 
 Grit. — Grindstones are specified as of hard grit or soft grit, according to 
 their density or texture. 
 
 Grit Stone. — A natural grindstone as distinguished from an artificial or 
 composition stone. 
 
 Gromet Washer. — A grummet washer (q.v.). 
 
 Grooving, or Turrowing. — (1) An action which injuriously affects certain 
 portions of boiler plates. It is the cutting round, or corroding away, 
 of those parts which are subject to continual leverage, and the grooving 
 action is partly due to mechanical strains constantly repeated, and 
 partly to the attacks of acids in the Hues of strain. It is particularly 
 observable in the seams of those plates which are not properly stayed. 
 (2) The recessing of the edges of hoards to receive the tongues of 
 corresponding boards. Grooving is performed by revolving cutters, or 
 by a small thick circular saw having widely-spaced teeth. 
 
 Grooving Saw. — A drunken saw (q.v.). 
 
 Gross Indicated Horse-power. — See Indicated Horse-power. 
 
 Gross Pressure. — Absolute pressure (q.v.). 
 
 Gross Section. — The gross section of a steam boiler is the total number of 
 inches contained in its circumference. If it were a solid plate this 
 would also be its effective section (q.v.). 
 
 Ground Line. — The horizontal Une along which the strains in a crane post 
 (q.v.) tending to break it off are concentrated in greatest force. This 
 is not necessarily on a level with the ground, hut coincides with the 
 upper face of the foundation-plate or ring in which the post is fixed, in 
 a fixed crane, or in which the rollers revolve in a portable crane. 
 
 Ground Wheels. — The running, or travelling wheels of a portable crane. 
 
 Grouped Safety-valve. — See Cowbum Valve. 
 
 Grout. — A coarse mortar used for cementing iron work into stone. 
 
 Grouting. — The fastening of ironwork, as bolta and eyes, into masonry 
 by the aid of grout (q.v.). 
 
MECHANICAL ENGINEERING. 167 
 
 Gru'b Screw. — A screw -Brhioli has neither nut nor head of any kind, but 
 ■nrhich is simply slotted across the top end for the insertion of a scre"w- 
 driver, by means of "which it is driven home. 
 
 Grummet Washer, or Gromet Washer. — A washer made of a strand of 
 rope, or spun yam, or tar twine, twisted into the form of a ring. It is 
 employed for insertion under the heads of sc^uare- shouldered bolts, in 
 built up oast-iron water tanks ; its purpose being to prevent leakage 
 round the heads where the rust caulking does not completely fill up. 
 
 Guard.— See Shield. 
 
 Guard Plate. — The curved plate in an india-rubber disc valve, which pre- 
 vents the india-rubber feom opening or lifting beyond the distance 
 limited by the plate. 
 
 Guard Bail, — In permanent way, a short rail laid down at a crossing near 
 the outer rail to guide the wheel flanges. It fulfils a similar purpose 
 as a check rail (q.v.) on a curve. 
 
 Guard Strap. — The strips of sheet iron which arch over the tops of the 
 wheels of locomotives, as a protection against injury to the drivers. 
 
 Gudgeon. — The cross shaft which stands at right angles to a piston-rod, 
 or pump-rod, and which forms the medium of communication between 
 the rod and the crosshead, or slipper blocks. 
 
 Guide. — (1) Any attachment or contrivance by which a crosshead, or slipper 
 block, or pin of an engine, pump, or piece of mechanism, is coerced to 
 travel in one path only, whether linear or curvihnear, is termed a guide 
 or guide-rod, guide-bar, or slide-bar. (2) A chisel-shaped attachment 
 to rolling mOls, which lifts the rail or bar o£E the rolls on the leaving 
 side. Without the guide, the bar would turn around the roll. 
 
 Guide Bars. — See Slide Bars. 
 
 Guide Blocks.— See Slide Blocks. 
 
 Guide Iron. — A piece of iron rod, about J in. square, which being bent to 
 the contour of a curved pattern pipe, becomes a guide by which the 
 core maker strickles up its core without requiring a core-box. It is 
 equally available for striking up a pipe pattern in loam. 
 
 Guide Plate. — See Kamps. 
 
 Guide Pulley. — A pulley which neither acts as a driver or a driven, but 
 simply as a guide for changing the direction of motion, or to take up 
 the slack or strain on an extensible belt or cord. 
 
 Guide Hod. — See Gruide. 
 
 Guide Screw. — The leading screw of a self-acting lathe. Used for tra- 
 versing the sKde rest, and for initiating the threads of screws. 
 
 Guillotine Shears. — A special type of shearing machine, used for the cut- 
 ting up of puddled bars and slabs ready for piling (q.v.). The shears 
 are similar to those of ordinary shearing machines, but instead of being 
 set transversely to, they are parallel with, theplane of the machine frame- 
 work. 
 
 GuUeting. — The deepening of the roots of the teeth of circular and guUet 
 saws. 
 
 GuUet Saw. — A saw whose teeth are deepened andhoUowed in their roots. 
 Most circular and pit saws are gulleted, and the dust runs away with 
 greater freedom from such saws, the guUets being sloped outwards on 
 alternate sides. 
 
 Gullet Teeth. — The teeth of a gullet saw (q.v.). 
 
 Gumming. — Lubricating oils are gumming or non-gumming, as they 
 become thick and sticky, or otherwise. See Saw Gumming. 
 
 Gun Metal. — ^Au alloy of copper and tin in various proportions, employed 
 
I68 DICTIONARY OF TERMS USED IN 
 
 largely in engineering constniction. It is tougher than oast iron, does 
 not heat rapidly with friction, and is easily turned and planed. Its 
 tensile strength ia less than that of wrought iron, but greater than that 
 of cast iron, and equals about 1 1 tons per square inch of section. It is 
 employed for bearings, and in pump work where the use of iron would 
 be objectionable, by reason of its liabiHty to rust. Gun-metal is hard 
 or soft as it contains greater or less proportions of tin. Called also 
 bronze. A tough mixture contains copper 90, tin 10 parts. 
 
 Gusset. — An angle-iron bracket used to stiffen an angular portion of a 
 structure. See Gusset Stay. 
 
 Gusset Plates. — The webs or plated portions of gusset stays (q.v.), as dis- 
 tinguished from their angle-irons. 
 
 Gusset Stay, or Gusset. — A triangular plate of wrought iron or steel, 
 whose function is to support the inherently weak flat ends of Cornish 
 and Lancashire boilers. In large boilers about five gusset stays are 
 attached to each end, being secured to the shell and to the end-plates 
 by angle-irons. 
 
 Gut Bands. — Gut bands are used for driving some of the smaller foot- 
 lathes. They are united by hooks and eyes, sometimes hy splicing. 
 Gut is prepared from the intestines of the sheep, but sometimes from 
 those of the horse, ass, or mule ; never from the cat. 
 
 Gutta Percha. — A vegetable exudation which is largely employed by 
 hydraulic engineers for the valves of hydrants and other water valves. 
 It is used for taking impressions of ornamental work for which foundry 
 models have to be made. The gutta-percha is placed in cold water to 
 cool, to prevent its contraction. 
 
 Guys. — -The tension ropes or chains which act as braces or supports to 
 shear legs, or which sustain the mast or boom of a derrick crane. 
 
 Gyration, Centre of. — See Centre of Gyration. 
 
 H. 
 
 Hack Hammer. — A chisel-shaped oross-paned hammer (see Pane), attached 
 to a stout handle, and used for the purpose of hacking (q.v.) grind- 
 stones. 
 
 Hacking. — The dressing off of the projections upon the face of a grind- 
 stone with a hack hammer (q.v.). When a stone becomes very uneven 
 it is difficult to use the ordinary pointed grinding tool with effect. The 
 hack hammer renders the task easier, by first reducing the chief pro- 
 jections by a series of cross hatchings, or chequered cuts. 
 
 Hack Saw. — A light frame saw used for cutting metal. The saw has a 
 thin narrow blade, and equilateral triangular-shaped teeth, and is 
 stretched between a frame of wrought iron, the requisite tension being 
 imparted to the saw by means of a thumbscrew. A handle is affixed to 
 one end of the frame, and downward pressure is imparted by laying the 
 left hand upon the back or top of the frame. This saw is in constant 
 use by fitters and machinists, for cutting off odds and ends of metal 
 where the concussion of a chipping chisel would be objectionable, and 
 for cutting fine slits in work of the exact width of the saw thickness. 
 
 Hsematite. — See Brown Haematite, Eed Hsematite. 
 
 Hair Compass. — A drawing compass in which provision is made for 
 minute adjustment for distance. The upper portion of one of the legs 
 
MECHANICAL ENGINEERING. i6q 
 
 is formed into a spring to which a screw, having a milled head, is 
 attached, and by means of which the exact amount of the required 
 movement is regulated. 
 
 Hair Eelt.— See Felt. 
 
 Hair Side. — The grain side (q.v.) of a leather belt. 
 
 Half-blind Holes.— See HaU-lap Holes. 
 
 Half-centre. — Half-centre is sometimes used to denote the position of the 
 crank-pin of an engine when midway between the two dead centres or 
 dead points. The rotational effect is greatest at half-centre. 
 
 Half-crossed Belting. — Belting is said to be half-crossed when it drives 
 between two pulleys whose axes are at right angles with each other. 
 Such belts can only run in one direction. 
 
 Half-lap Coupling. — A box coupling in which the liability of the shafts 
 to slip is prevented by making a short length of one shaft overlap a corre- 
 sponding length on the other, one-half the sectional area being removed 
 in each case. The diameter at the joint is increased to maintain equal 
 strength, and a little taper is imparted to the lapped parts. 
 
 Half-lap Holes, or Half-Blind Holes. — Rivet holes in boOer and other 
 plates which are punched so inaccurately that when the plates are 
 brought together they do not correspond within the extent of one-half 
 their diameters, the edge of one coming to the centre of its fellow when 
 the plates are in position. In this case the holes should be broached or 
 rymered out, and larger rivets inserted, though it is too often the custom 
 to pull them together with a drift. See Drift, Blind Holes. 
 
 Half-lap Joint. — See Halving. 
 
 Half-lattice Girder. — A Warren girder (q.v.). 
 
 Half Pattern, — One of the halves of a pattern which is jointed through 
 the centre for convenience of moulding. 
 
 Half-rip Saw. — A hand-saw, from 28 in. to 30 in. long, containing about 
 three and a half teeth to the inch. It is used for cutting with the 
 grain chiefly. 
 
 Half-round Bit.— See Cylinder Bit. 
 
 Half-round Chisel. — See Hound-nose Tool. 
 
 Half-round File. — A fUe which is flat on one side and convex on the other, 
 the amount of convexity never, however, equalling the half of a circle, 
 being always much less, though variable in amount. The amount of 
 convexity is indicated by the terms, " round-edged flat," " extra thin 
 flat," "flat," and "high-backed half-round." 
 
 Half-round Iron. — Rolled wrought-iron bar used in various engineering 
 constructions. Itis either solid half round, the section being that of a solid 
 hemisphere, or hollow half round, the section being that of a semi-cylin- 
 der. SoUd half rounds are made from about 1 Jin. X fin. to 3 Jin. X If in., 
 and hollow half rounds from 1 J in. Xfin. thickness to 3Jin. X lin. thick- 
 ness. 
 
 Half Section. — A sectional view which terminates at the centre line divid- 
 ing the object represented into two symmetrical portions. Where a 
 half section is given, the complementary half is usually an outside view 
 or elevation. 
 
 Half Shrouding. — See Shrouding. 
 
 Halving. — The making of joints in pattern work, effected by cutting half 
 the thickness from the face of one piece, and the other half from the 
 back of its fellow, so that when brought half to half their outer surfaces 
 are flush. 
 
 Hammer. — There are not many different types of hammers used in fao- 
 
170 DICTIONARY OF TERMS USED IN 
 
 tories, and those being ordinary fitter's hammers, the smith's hammers, 
 hand and sledge. Hammers are sold by weight, and range from half 
 a pound to lilbs. 
 
 Hammer Block. — The steel face of a steam hammer which is attached to 
 the tnp (q.v.) by means of a dovetailed joiat. 
 
 Hammer Hardening. — ^When cold sheet metal is subjected to long-con- 
 tinued hammering, its fibres are thereby rendered dense, hard, and 
 brittle. This is termed hammer hardening in order to distinguish it 
 from fire hardening. It is therefore the reverse of the process of an- 
 nealing (q.v.). 
 
 Hammer Head. — The hammer itself as distinguished from its handle. 
 
 Hammerman. — A smith's striker or mate, the man who hammers the 
 heavier work upon the anvU with a sledge. 
 
 Hammer Marks, — The marks of the hammer left on smith's work. Pree- 
 dom from hammer marks is one of the tests of good work. The use of 
 fiatters tends to obliterate these marks. 
 
 Hammer Scale. — The scale squeezed out from a bloom of puddled iron 
 under the steam hammer. It is employed for coating the bottom or 
 hearth of the puddling furnace, because of its richness in oxygen, and 
 consequent value as a deoarburising agent. 
 
 Hammer Shaft. — The handle of a sledge hammer. 
 
 Hammer Tongs. — Smith's tongs bent round at right angles with the 
 main axis, for the chpping of pieces of punched work. The opening or 
 loop enclosed by the jaws is of large area. Called hammer tongs be- 
 cause used in the manipulation of hammers in course of manufacture. 
 
 Hand. — A word commonly used as afBx and prefix, as hand screw, hand 
 feed, hand shears, hand hole, right hand, left hand, c&o. 
 
 Hand Brace. — See Brace. 
 
 Hand Brake. — A brake which is applied or released by means of a lever 
 held in the hand, as opposed to a foot, steam, or water brake. 
 
 Hand Crane. — A crane whose motive power is suppUed by the energy of 
 a man or men turning the handle or winch. 
 
 Hand Drill. — A drilling machine worked by hand power. Or a drill 
 actuated by a bow, or a hand brace, or a ratchet brace. 
 
 Hand Drilling. — The drilling of holes by means of a ratchet brace, or 
 other suitable hand drill, as distinguished from machine or power dril- 
 ling. The practice of hand drilling is of necessity resorted to in all 
 outdoor work, but also to a considerable extent in the workshop where 
 the use of machines is available, as in cases where work is in course of 
 erection and cannot he brought to the machines, or where an individual 
 piece, as a long column, or a girder, or large awkward casting, is too 
 ungainly or bulky to be placed under the machine at all, or without an 
 expenditure of trouble and time out of proportion to the cost of drilling 
 the holes by hand. Where the proportion of cost of transit and setting 
 of work under the machine is heavy, hand-drilling specially performed 
 by a man accustomed to it is cheaper. 
 
 Hand Expansion Gear. — Variable expansion gear, adjustable by hand, 
 usually consisting of two screws, right and left-handed respectively, 
 by which the positions of a pair of cut-ofE valves are adjusted relatively 
 to the slide-valve. 
 
 Hand Feed. — (1) The feed (q.v.) of the cutting tools of machines of 
 various kinds, which is effected by the hand of the workman alone, in 
 opposition to power feed (q.v.). (2) The passing of a board over the 
 cutters of a wood-planing machine by hand, as distinguished from 
 
MECHANICAL ENGINEERING 171 
 
 roller or automatic feed. (3) The thrusting of timber through a cir- 
 cular saw, in opposition to the mode of feeding by drag ropes or 
 rollets. 
 Hand File. — Or flat file. The ordinary engineer's file, which, though 
 slightly rounding or bellied lengthways, is fiatter than the bellied file 
 
 . (q-v.). 
 
 Hand Fitted. — Metal work and machine work fitted by hand labour, as 
 opposed to work performed by machines. 
 
 Hand Gear. — Gear, usually toothed, worked by a winch handle, in con- 
 tradistinction to power gear. 
 
 Hand Hammer. — An ordinary fitter's or smith's light hammer, weigh- 
 ing from one to one and a half pounds. 
 
 Hand Holes. — Holes cut in the shells of steam boilers, through which 
 the hand is passed for purposes of cleaning and repairs. They are em- 
 ployed when the use of a mud hole is iaadinissible. 
 
 Hand Hook. — A hook wrench (q.v.). 
 
 Handing. — Making symmetrical work right and left hand respectively, 
 and altering patterns from left to right hand and vice versd. 
 
 Handing Sound. — The turning round of the handles of a die stock (q.T.) 
 which in the larger kinds is done by two men who pass, or hand round 
 the handles from one to the other. 
 
 Hand Ladle. — Or hand shank ladle. A small ladle used in foundries 
 for carrying molten metal to the moulds. It is called a hand ladle be- 
 cause it is carried by one man without assistance. It holds about a half - 
 hundredweight, and is provided with a handle about three feet in 
 length. 
 
 Handles. — See Tool Handles. 
 
 Hand Lever. — ^A light lever worked by hand power only. Hand levers 
 are employed in hundreds of machines and for an infinity of purposes. 
 The part grasped by the hand is usually turned to a shape convenient 
 for the grasp. 
 
 Hand Lift. — A lift (q.v.) worked by the hand hauling at an endless 
 rope ; the rope passes over a sheave and thus actuates a worm, worm- 
 wheel, and suitable spur-gearing. The whole of the gearing is placed 
 at the head of the Hft. 
 
 Hand Eammer. — A roxmded hammer-Kke tool furnished with a short 
 iron handle, and used in foundries for ramming the sand round pat- 
 terns, and into core-boxes. 
 
 Hand Best. — A tee-rest (q-v.), so called because used for unassisted 
 hand- turning, as distinguished from an automatic or slide rest. 
 
 Hand Bivetting. — The turning over of the heads of rivets by men 
 • working hand hammers only, with or without the intervention of a 
 die or snap, as opposed to machine rivetting. 
 
 Hand Saw. — A saw about 26 in. in length, the ordinary one-handled saw 
 of the largest size used in the workshop. It is used for the common work 
 of sawing stuff of moderate thickness both longitudinally and across. 
 Eip, half rip, and panel saws may be considered modified hand saws, 
 from which they differ in the size of the teeth, and to a slight amount 
 in length. A hand saw proper contains from five to six teeth to the inch. 
 
 Hand Screw. — ^A pair of small wooden vice chops, tightened by two wooden 
 hand screws, and used for the temporary clamping together of jointed 
 pieces of wood. 
 
 Hand Shank Ladle. — A hand ladle (q.v.). 
 
 Hand-shearing Machine. — ^A small machine used for cutting tin plate 
 
172 DICTIONARY OF TERMS USED IN 
 
 and thin sheet iron by steariag action. These machines are all worked 
 by means of levers, one blade being fixed, the other movable ; but they 
 differ in details of construction. 
 
 Hand Sketch, or Sketch simply. — A rough kind of free-hand drawing 
 made without rule or compasses, and therefore, though not to scale, it is 
 a working sketch because furnished with necessary dimensions. Hand 
 sketches are used for rough and temporary purposes, or for those jobs 
 which win not pay for the making of regular drawings. 
 
 Hand Surfacing. — See Surfacing. 
 
 Hand Tap. — A tap worked with a tap-virench by hand, as distinguished 
 from a machine tap. The shank of a hand tap always terminates in a 
 rectangle or in a flat expansion, to enter the hole in the tap- wrench. 
 
 Hand Tools. — AU the tools, cutting and otherwise, actuated by the hand 
 alone, as distinguished from machine tools. 
 
 Hand Traverse. — A traverse or cross movement of a machine part which 
 is efEected through mechanism actuated by the hand alone. It is there- 
 fore the opposite of automatic. 
 
 Hand Traversing. — See Traversing. 
 
 Hand Turning. — Turning accomplished by the unassisted aid of hand 
 tools, both for wood and metal, as distinguished from turning done 
 by the aid of the slide-rest in self-acting lathes. 
 
 Hand Vice. — A small spring vice held in the hand and used for the 
 manipulation of wire and of small and light work in general. 
 
 Hand Wheel. — A wheel turned by the hand for the purpose of actuating 
 screws, worm-gearing, clutches, levers, &o., by which motion is im- 
 parted to some portion or portions of a machine beyond the immediate 
 reach of the attendant. 
 
 Hand-wheel Feed. — Any feed motion imparted to the feed-screw by 
 means of a hand wheel. It is chiefly in drUling machines that the 
 spindle is fed by means of a hand wheel. Sometimes the hand wheel 
 moves vertically, carrying the screw along with it ; in other cases the 
 screw alone moves through the boss of the hand wheel, the latter being 
 stationary. See Stationary Hand-wheel Feed. 
 
 Hang. — The particular style, or angle, or fashion,, at which a smith or a 
 fitter holds his hammer. 
 
 Hang Down, or Hanger. — A bearing suspended from a roof or beam for 
 the journal of a shaft, hence its name. It is held in place with bolts, and 
 the bearing parts consist of brasses and a cap in the usual fomis. 
 
 Hanger. — See Hang Down. 
 
 Hangers. — The looped suspension rods which depend from the transverse 
 beam attached to a foundry crane, and which receive the swivels of a 
 moulding-box slung therefrom. 
 
 Hanging. — Hanging means the fixing of a puUey, fly-wheel, grindstone, 
 &c., upon its shaft or axle. Wben the central hole is bored to the 
 same diameter as its shaft there is practically no hanging required, so 
 that the term is oiJy strictly appKcable in cases where the hole is 
 larger than the axle, as in those of rectangular and polygonal sections, 
 and where therefore the pulley, or stone, or wheel has to be adjusted 
 and set by means of wedges or keys. 
 
 Hanging Tube Boiler. — A type of vertical boiler in which a number of 
 small water-tubes closed at the lower end hang from the firebox crown 
 and are exposed directly to the play of the fire and hot gases. See 
 Field's Tubes. 
 
 Hang To. — A term having several applications. A file hajigs to its work 
 
MECHANICAL ENGIMEBRING. 173 
 
 irlien it cuts without slip. A saw hangs to, when it feels as though 
 heing drawn into the timher. A pattern hangs to the sand when it 
 delivers with difficulty. 
 
 Hard Brass. — (1) Brass which has not heen annealed after drawing or roll- 
 ing. It is highly elastic, and is therefore used for springs and work of 
 a similar character. (2) Hammered brass, and brass which contains 
 a large proportion of tin. Gun-metal is often called hard brass, and 
 is therefore suitable for bearings. 
 
 Hard Coke. — Oven coke (q.v.). 
 
 Hardening. — Hardening is the result of an increase in the density of a 
 metal. The hardening of steel is effected by heating it to a tempera- 
 ture higher than that which it is to receive permanently, and then sud- 
 denly cooling it in oil, or water, or other suitable solution. The 
 temperature for hardening is controlled by the quality of the steel and 
 the purposes to which it is to be applied. See also Case Hardening, 
 Hammer Hardening, Babbitting. 
 
 Hardening Mixtures. — Fluids or semi-fluids employed for hardening and 
 tempering works in steel. Pure spring water is the best for general 
 purposes, but for special work a multitude of media are used, and most 
 workmen have some special mixture of their own -which they deem 
 endowed with peculiar virtues. The water is frequently medicated 
 with common salt, or with other ingredients, and is used either cold or 
 slightly lukewarm. For small delicate works and tools, oils and fats 
 are used in preference to water. See Blazing Off. For special work 
 fusible metallic alloys are employed. 
 
 Hard Firing. — Rapid stoking of engine fires and quick succession of 
 charges. 
 
 Hard Grit. — Hard grit signifies a grindstone or emery wheel of hard 
 texture. 
 
 Hard Iron. — Cast iron, which is dense and close grained. It is obtained 
 by making suitable mixings of various brands with scrap, and is used 
 for wearing parts, the liners of engine cylinders, and cog-wheels. 
 
 Hard Lead. — Lead which has been smelted but not ' ' improved. ' ' The 
 hardness is due to the presence of antimony, copper, and iron in 
 minute proportions, which united, render the lead unsuitable for the 
 purposes for which it is commonly employed. 
 
 Hard Metal.— See Soft Metal. 
 
 Hardness. — See Toughness. 
 
 Hard Kanuning. — Hard Ramming relates to the amount of pressure em- 
 ployed when n m ning foundry sand around patterns embedded therein. 
 Excessively hard ramming is productive of scabs. Too soft or too 
 light ramming results in lumpy and swollen castings, because the pres- 
 sure of metal causes the sand to yield before it. Ramming should be 
 harder at a distance away from the pattern th.an in its immediate 
 vicinity. The proper amount of pressure varies therefore, and is a 
 matter for the exercise of experience and judgment. 
 
 Hard Solders. — The solders used in brazing (q.v.) and generally for 
 uniting the harder and more infusible metals. 
 
 Hard Tap. — When the clay which closes the tap hole of a cupola is 
 pierced with difficulty it is said to be a hard tap. 
 
 Hard Water. — Water containing a large quantity of carbonate and sul- 
 phate of lime i]i solution. Hard waters are objectionable for use in 
 water piping and in steam boUers, since they produce calcareous 
 deposition. 
 
17H DICTIONARY OP TERMS USED IN 
 
 Hard Wood. — Of tBe woods employed in engineering construotion, oak, 
 ash, beech, elm, mahogany may be considered hard. 
 
 Hatch. — A slnioe ; usually applied to a sluice of large size set in the 
 coxirse of a stream for regulating the supply of water to a miH wheel. 
 
 Hatchet. — A double bevelled cutting tool whose edge is parallel with the 
 axis of its handle, and is actuated by percussive force only. 
 
 Hatchet Stake. — A tool used by coppersmiths for bending their thin 
 sheets. Its edge is sharp, somewhat like that of a hatchet, hence its 
 name, and the sheet metal is turned over the edge. 
 
 Hat Leather. — The leather ring packing used for hydraulic pistons. It 
 ia of the same section which would be produced by bending a strip of 
 angle iron into a ring with one edge facing inwards. Sometimes it is 
 called a cup leather (qv.), though strictly speaking this term has refer- 
 ence to a leather of quite a diflterent form. Hat leathers are co mm only 
 used in pairs, or back to back. 
 
 Hawse Pipe or Hawser Pipe. — (1) A stout cast-iron pipe or tube with well- 
 rounding edges which lines the hawse or chain hole in a ship's side. 
 (2) A pipe which guides the barrel chain in some forms of grabs. 
 
 Hawser Eope. — A cable laid rope (q.v.). 
 
 Hay. — See Hay Band. 
 
 Hay Band. — Common hay spun into bands of IJ in. or 1 J in. diameter, 
 and of several yards in length is used in the making of foundry cores. 
 The band ia wrapped closely round a core bar, and the thickness of loam 
 struck upon it. The hay then forms a porous mass through which the 
 gases generated in casting readily find egress from the mould. 
 
 Hay Band Spinner, — A long lantern wheel made of wood, and set spin- 
 ning on an axle fixed in a wall, and on which the core maker or core 
 boy spins his bands. It is rotated by one hand, while the hay is fed 
 on to it and twisted with the other. 
 
 Hay Eope. — Hay Band (q.v.). 
 
 Haystack Boiler. — A balloon boiler (q.v.). 
 
 Hazel. [Corylus avellana). — An English wood of the order Ctipuliferie, 
 whose quaUties of toughness and elasticity render it invaluable to 
 smiths for the handles of flatters, swages, chisels, &;c., where metalHc 
 handles would produce a painful jar in the hands due to the hammer 
 blows. See Hazel Eods. 
 
 Hazel Bods. — The rods or handles of smiths' small tools are made by 
 binding hazel rods of about J in. in diameter around the head and 
 twisting them tightly. The rods are supplied in bundles, and are 
 soaked in water and warmed previous to being bent. 
 
 Head. — (1) A term of wide application, signifying the broad end or ex- 
 pansion of screws, nails, bolts, &c., hammer heads, head metal, &c. 
 (2) The height of a column of liquid, or the pressure equivalent to that 
 height. This enters into all calculations concerning the pressure on 
 mains and valves, the power of turbines and water wheels. (3) The 
 head of a rail is the upper surface upon which the wheels travel. 
 
 Headers, — Headers refer to the laying of courses of bricks for the linings 
 of blast and cupola furnaces ; being set with their heads or ends to- 
 wards the body of the furnace, thus giving the maximum of thickness 
 to the lining. 
 
 Heading Tool. — A smith's tool used for shaping the heads of screw bolts. 
 The tail of the bolt passes through a hole in a plate, and the bar while 
 white hot is flattened out over the surface to form the head. 
 
 Head Metal, or Dead Head. — A mass of metal, usually in the form of a 
 
MECHANICAL ENGINEERING. t?s 
 
 ring cast on the upper end of cylindrical -work to foiTU a receptacle for 
 the dross, sullage, scorite, &o., -which collects upon the top of molten 
 metal. When the casting is removed from the mould the head metal 
 is turned oS, leaving the actual casting smooth and free from these 
 foreign impurities. 
 
 Headstock. — (1) The fixed head or poppet of a lathe which carries the 
 revolving mandrel and rigger. The poppet proper or the hack poppet 
 is sometimes called the movahle headstock. (2) The end timbers in the 
 under frame of a railway truck. 
 
 Head Valve. — The uppermost or deUvery valve of an air pump, so termed 
 in opposition to the foot or suction valve. 
 
 Heart and Sc[uare Trowel. — A donhle-ended moulder's trowel, whose 
 two ends are united by a metallic handle, one trowel being heart- 
 shaped, the other rectangular. They are made in small, medium, 
 medium large, and large sizes. 
 
 Heart Cam. — A cam heart-shaped in form, used for the conversion of 
 rotary into rectilinear motion. 
 
 Hearth. — (1) That portion of a reverberatory furnace (q.v.) upon which 
 the ore or metal, as the case may be, is exposed to the action of the 
 flame which reaches it from the fireplace after passing over the bridge. 
 (2) The conical portion of a blast furnace which lies below the boshes, 
 and into which the molten metal descends. (3) The bottom of a cupola 
 upon which the coke bed is laid. (4) The open area of a smith's forge 
 in front of the tuyere upon which the fuel is placed. 
 
 Hearth Sack. — A plate of cast iron which forms the back of a smith's 
 hearth. It is suppUed with a nozzle for the entry of the nozzle of the 
 water tuyere, and with holes for bolting up into place. 
 
 Hearth Plate. — A cast-iron plate which sometimes covers a furnace 
 hearth. 
 
 Heart Trowel. — A moulder's trowel, whose outline is cordate or heart- 
 shaped. It is named long or broad, according to its proportions. 
 
 Heart Wood. — The wood in, and immediately around the centre of a tree. 
 The heart wood is best in young timber ; in old trees it is of little value. 
 
 Heat. — (1) Heat is produced by the motion of the ultimate molecules of 
 matter, which motion results either from mechanical action, the friction 
 of bearing surfaces for example, or from chemical affinity, as the union 
 of the carbon or hydrogen in fuel with the oxygen of the air, or from 
 electricity. Heat is convertible into mechanical work, and work, con- 
 versely, into heat. The more rapid the vibration of the material 
 particles, the greater their separation and expansion and the greater 
 the quantity of heat evolved. Hence heat is simply a mode of motion, 
 and not a material substance, as was formerly supposed. (2) A term 
 commonly employed in smithies and boiler shops to signify the getting 
 hot of any piece of metal which is to be operated on. Thus a man will 
 be said to get so many heats in a definite time, which represents there- 
 fore the amount of work which he is able to do. Or he will shape a 
 definite section of a forging at a single heat, that is, without reheating 
 the work in the fire. The same term is applied by puddlers to the 
 working through of a single charge of iron. 
 
 Heater. — See Feed Water Heater. 
 
 Heating Apparatus. — The apparatus by means of which buildings are 
 warmed up to a definite temperature. The heating is effected by the 
 circulation of hot water in pipes due to convection, or of steam in steam 
 pipes provided with radiating plates. 
 
176 DICTIONARY OF TERMS USED IN 
 
 Heating of Bearings. — Bearings are said to heat when their temperature 
 rises so mnoh above the normal that their axles either stick fast or are 
 subject to great extra friotional strain, or are themselves rapidly- 
 abraded. The temperature may be such that the hand can barely 
 tolerate, or so high as a low red heat. Heating is due to want of 
 lubrication, and the remedy is to slacken the bolts, and pour on water 
 first and oil afterwards. If the bearing is very hot, the first applica- 
 tion of water should be hot, since cold water might produce fracture. 
 The presence of sulphur also assists the oooUng action of the oil. 
 
 Heating Surface. — (1) The entire superficies of a steam boiler exposed to 
 the flame and incandescent gases on the one side, and to the water upon 
 the other. (See Transfer of Heat.) (2) The total area of the brick 
 chequering or partitioning in regenerative furnaces. (3) The pipe 
 surface in a pipe stove (q.v.). 
 
 Heat, XTnit of. — The British practical unit of heat is 772 foot pounds, or 
 the Joule. See also Thermal Units. 
 
 Heavy Cut. — The work of a cutting tool on metal is said to he heavy 
 when it is removing thick and broad shavings. The term is relative, 
 because what would be a heavy cut in small work would be a light cut 
 in work of larger dimensions. 
 
 Heavy Eiring. — Close or thick firing. 
 
 Heavy Oil.— Thick oil (q.v.). 
 
 Heavy Bunning — The reverse of light running (q.v.). 
 
 Hectare. — A iFrench measure of surface, being equivalent to one hundred 
 square area (see Are), or ten thousand square metres (q.v.). 
 
 Hectogramme. — A French measure of weight, containing one hundred 
 grammes (q.v.), and equivalent to 3'5274 English ounces. 
 
 Hectolitre. — A French measure of capacity, containing one hundred litres 
 (q.v.), and being equivalent to 22'009 English gallons. 
 
 Hectometre. — One himdred metres (q.v.), or 3937-079 English inches. 
 
 Heel. — The thick or broad end of a wedge-shaped piece, the broad end of 
 a railway switch for example. 
 
 Heel Tool. — A turning tool for metal which was commonly employed 
 before the use of the slide-rest became general. The cutting end re- 
 sembled in shape that of a boot, the heel being supported upon the rest, 
 the toe being the actual cutting edge. The handle rested in an oblique 
 direction against the shoulder of the workman. 
 
 Helical Gear. — Toothed gear in which the wheel-teeth instead of being at 
 right angles with th^eir faces are set at some other angle therewith. 
 Such gear may be single or double ; in the former the teeth being in one 
 diagonal plane only across the wheel, in the latter they are in two diag- 
 onal planes placed symmetrically on each side of a plane cutting trans- 
 versely through the axis of the wheel, and midway between its faces, 
 the last form being mostly employed. Helical gears are a modification 
 of the old stepped gears-, the steps being blended into one continuous 
 face, hence the teeth slide do-wn one another with more regularity than 
 is the case with ordinary wheels. In principle they are screw gears. 
 
 Helical Teeth. — See Helical Gear. 
 
 Helical Spring. — See SpiraJ. Spring. 
 
 Helve. — (1) The handle ofan axe, hatchet, or adze. (2) A helve hammer 
 (q.v.). 
 
 Helve Hammer. — ^An antiquated form of smiths' hammer, sometimes called 
 tilt or trip hammer, in which the hammer is attached to a lever lifted 
 by cams or -wipers, and allowed to faU with the force due to its owu 
 
MECHANICAL ENGINEERING. 177 
 
 momentum. Helve hammers are of two kinds ; one, the nose or frontal 
 helve, in which the cams act upon the lever which carries the hammer, at 
 the extreme end, or opposite to the fulcrum ; the other, or heUy helve, 
 where the cams act upon the lever hetween the hammer head and the 
 fulcrum. The latter gives more room for the manipulation of the 
 forging or of the hloom than the former. 
 
 Hemp, or Tow, — Hemp or tow is used in foundries hy core makers for 
 winding on small core bars previous to the daubing and sticking on of 
 the loam. It fulfils the same purpose as the hay-bands in larger cores, 
 becoming a rough basis for the attachment of the loam, and also a porous 
 mass through which the gases generated by easting escape into the 
 hoUow of the bar. Hemp is also largely used by moulders for jfilling 
 up the interstices of cores which are laid irnaUy in their places, the mould 
 being yet unfinished, the object being the prevention of the accidental 
 falling in of dust and sand into the lower, or already finished portions. 
 The hemp is removed just previously to the final closing of the mould. 
 
 Hempen Sopes. — Ordinary ropes for the transmission of power, and for 
 haulage, &c., are made of coarse hemp, chiefly imported from Russia, 
 hence the ropes are frequently termed Russian ropes. The ropes are 
 usually tarred, and are thus djstinguished from white or untarred ropes. 
 (See Manilla Ropes.) The prepared hemp is first spun into yams, 
 these into strands, the twist of the strand being in an opposite direction 
 to that of the yams, and the strands laid or twisted into the rope. 
 Tallin J, when practised, is effected when the yarns are spun, and before 
 thtya^e twisted into the strands. The hemp genus belongs to the 
 natural order Cannabinacecs. 
 
 Hercules Crane. — A crane of a large and powerful type, used in harbour 
 works for the setting of concrete blocks. It is mounted on a travelling 
 framework, and has a horizontal jib which slews either through a 
 portion of, or the whole of a revolution. Steam is the motive power 
 used. 
 
 Hexagon Nut. — The ordinary six-sided form of nut which has superseded 
 the primitive square form, owing to its superior neatness, and to the 
 fact of its being more readily turned in a narrow space, the handle of 
 the spanner being moved through a smaller arc to obtain a fresh bite. 
 
 High Breast Wheel. — See Breast Wheel. 
 
 High Plashing Point. — An oil is said to have a high flashing point when 
 it win take fire at a high temperature only. 
 
 High Press. — A workshop abbreviation employed to signify the high- 
 pressure cylinder in a compound engine. 
 
 High-pressure Engine. — (1) An engine which exhausts its steam directly 
 into the atmosphere. (2) Any engine, condensing or non-condensing, 
 which is driven by high-pressure steam. 
 
 High-pressure Cylinder. — The smaller cylinder of a compound engine 
 which receives the steam direct from the boiler, and in which it is 
 first expanded, and from which it is exhausted into the adjacent low- 
 pressure cylinder. 
 
 High-pressure Steam. — Steam whose pressure is sufficiently above that 
 of the atmosphere to enable it if required to drive an engine which is 
 unprovided with a condenser. 
 
 High Speed. — A term having various applications in practice, being of 
 general rather than of special signification. High-speed engines may 
 be considered to embrace any engines making over 200 to 300 revo- 
 lutions per minute ; or, putting it in another way, exceeding a piston 
 
 N 
 
1/8 DICTIONARY OF TERMS USED IN 
 
 speed of 300 feet per minute. All rotary and three-cylinder engines 
 also are termed high speed without special reference to any definite 
 rate of revolution. High-speed belting applies to belts for fans, wood- 
 ■worting machinery, centrifugal pumps, &c., in opposition to those for 
 line and counter, and other slowly driving shafts. 
 
 High Speed Bearings. — Bearings whose length exceeds their diameter by 
 from four to six times. Their value consists in the distribution of the 
 excessive friction of rapidly revolving shafts over a large extent of sur- 
 face, with a consequent diminution of heating. They are made in 
 various forms ; in one of the commonest the actual bearing is made to 
 swivel in its plummer block or hanger, and is thus rendered capable of 
 accommodating itself to shght inequalities in the line of the shafting, 
 or to inaccuracy in the setting of the main block or hanger. 
 
 High Speed Engine. — See High Speed. 
 
 Hippopotamus Hide. — Sometimes used for the covering of buff wheels, 
 being more elastic and durable than leather. 
 
 H Iron. — EoUed wrought-iron bar whose section is that of the letter I. 
 Used extensively for bmlding up engineering structures. 
 
 Hitch, — A cutting tool moving automatically in a tool holder is said to 
 hitch or catch when it is pulled into the work to a depth greater than 
 it is intended to cut. Hitching is due either to malformation of the 
 tool, to an unsuitable cutting angle, or to an improper position of the 
 cutting point relatively to the shank. 
 
 Hob, or Hub. A master tap. 
 
 Hogger Pump. — The upper portion of a deep mine pump. 
 
 Hogging. — The curving or distortion of the furnace tubes of boilers, 
 caused by the local expansion of the plates due to heat. Hogging is 
 chieily observable immediately after the lighting of the fire, and before 
 the temperature has become approximately uniform. 
 
 Hoist. — See Lift. 
 
 Hoisting Crab. — See Crab. 
 
 Hoisting Engine. — ^An engine specially fitted up for ordinary hoisting or 
 lifting purposes. It is usually attached to its vertical boiler, and to- 
 gether with a hoisting drum and suitable gearing is secured to a low 
 truck having unflanged wheels for convenience of portability. The 
 truck is drawn by horses to the locality where the services of the crane 
 are required. The lifting chain passes from the drum to a gin or pulley 
 block suspended from temporary shear legs or other convenient support. 
 
 Hold-down Bolts. — See Foundation Bolts. 
 
 Holding up. — The maintaining of a firm pressure against the heads of 
 rivets while their closing up is being effected, a holding-up hammer 
 being used for the purpose. 
 
 Holding-up Hammer. — An ordinary hammer used for holding up (q.v.). 
 The handle is of ash, and is pressed against a convenient fulcrum, the 
 ham m er being held against the rivet head, not directly, but with the 
 force due to the leverage exerted on the handle. 
 
 Hold up. — A term commonly used to express the capacity of a piece of 
 wood or metal to finish to a particular size. If it is under size, or its 
 surface is too winding to permit of finishing to thiclmess ; or if circular, 
 if its diameter is too small ; or if, though originally large enough, it 
 has not been centred truly, it is said not to hold up. 
 
 HoUiper. — See Oliver. 
 
 Hollows. — The inside curves imparted to the otherwise angular parts of 
 castings. They are inserted in order that the crystals of the metal 
 
MECHANICAL ENGINEERING. 179 
 
 may arrange themselves in tlie strongest position, tliat is, radially to 
 the face, which in a easting having purely right angles would leave a 
 line of break, and consequent source of weakness. Pattern hollows are 
 made in wood, metal, or leather. 
 
 Hollow Blows. — Blows delivered by a hanamer upon a substance which 
 is either unsupported, or insufiieiently supported by an opposing block. 
 The blows axe consequently elastic in character. 
 
 Hollow Golunm. — (1) A hollow column which contains the same quantity 
 of metal as a given solid column, is stronger than the solid column, and 
 the strength nearly equals the difference between that of two solid 
 columns whose diameters are equal to the external and internal 
 diameters of the hollow column, (2) The transverse strength of a thin 
 hollow cylinder is to that of a soHd cylinder of equal weight as the 
 diameter of the former is to the radius of the latter. 
 
 Hollow Half Eounds. — See Half-round Iron. 
 
 Hollow Mandrel lathe. — A lathe whose headstock mandrel is made hol- 
 low throughout to allow of the turning ofi of short pins, screws, or 
 other cylindrical work from a long piece of rod. The rod is slid 
 through the hollow mandrel as each successive pin or screw is turned 
 and cut off. 
 
 Hollow Moulding. — A term sometimes employed to designate the cylin- 
 drical and hollow forms of foundry work, as distinguished from flat 
 moulding. 
 
 Hollow Plane. — A plane whose face and cutting iron are hollowed out, 
 and which therefore planes rounding in section. Used for working the 
 rounding portions of beads and edges. 
 
 Hollow Set. — ^A smith's gouge, used for dres.sing off the circular portions 
 of forged work. 
 
 Hollow Spindle. — Applied to those lathes, screw-cutting, and cutting-ofE 
 machines in which the bar that furnishes the materials for use, is made 
 to traverse to an exact and measurable distance at a time through the 
 mandrel of the headstock, which is made hollow for that purpose. See 
 Hollow Mandrel Lathe. 
 
 Hollow Structures. — The larger machine frames, standards, parts, &c., 
 are made hollow from motives of economy. A given amount of mate- 
 rial properly disposed in a hollow form will possess more strength than 
 the same quantity solidly arranged. It is for this reason that machine 
 framings, base plates, columns, box girders, &c., are made hollow. 
 
 Hollow Tools. — Bottom swages (see Swage) are termed hoUow tools. 
 
 Homogeneous. — Of the same quality throughout. Cast metal is homo- 
 geneous when the crystals are as nearly as possible of the same size, 
 wrought metal when the fibre is clean throughout, and not an intermix- 
 ture of various qualities together with layers of scale and rubbish inter- 
 vening. Again, piled works, as iron rails for example, usually lack the 
 quality of perfect homogeneity by reason of the different qualities of 
 puddled bar and slab employed in their construction, the presence of 
 cinder, scale, or oxide, and imperfect welding ; while steel works rolled 
 from the ingot have the qnahty of homogeneity in perfection. 
 
 Hone, or Oil-stone. — A slaty stone used for whetting edged tools after 
 they have left the grindstone, to impart the keen and fine edge required 
 for clean cutting. The qualities of hones vary greatly, some being soft 
 and therefore fretting quickly, but producing a coarse edge ; others 
 being hard and slow of action, but giving a keener edge. For ordinary 
 shop vise, a Turkey or a Chamley Forest hone are the best, but Washita 
 
i8o DICTIONARY OF TERMS USED IN 
 
 and Grecian tones are in frequent demand, ttough not so reliable as 
 the first named. 
 
 HoneycomMng. — That kind of hoiler corrosion which takes the form of 
 numerous minute recesses, or small blank holes or pits, due to the 
 action of acids, or to want of uniformity in the quality of the plates, 
 or to galvanic action, or to all combined. 
 
 Hood, or Bonnet. — The upper covering or canopy over a smith's forge 
 ■which conducts the smoke into the chimney. 
 
 Hook. — A firing tool having a narrow prolongation of the end of a 
 long bar, turned down at right angles therewith, and used for clearing 
 the interspaces of the fire bars of boilers, of clinkers and ashes. 
 
 Hook Bolt. — ^A bolt which, instead of a square head, has an end hooked 
 or turned round at right angles. These bolts are often placed against 
 the outside faces of the work which they hold together. 
 
 Hooked Tommy. — A tommy used for turning round-headed screws and 
 circular nuts, when, owing to the shallowness of their holes, an ordinary 
 tommy would not hold sufficiently well. A hooked tommy is therefore 
 curved to follow the circular shape of the heads. 
 
 Hooke's Joint See Universal Joint. 
 
 Hooks and Eyes. — Cylindrical belt fasteners used for leather or gut belts 
 of circular section. 
 
 Hook Tool. — A form of tool used for vertical slotting, which is placed 
 transversely to the axis of the ram of the machine. 
 
 Hook Wrench, or Set, or Hand Hook. — A smith's tool used for taking 
 work out of winding or out of twist. It is formed of a piece of iron 
 bent round to form three sides at right angles with each other suc- 
 cessively, two being short and one of the two parallel sides being pro- 
 longed to form a handle. It is slipped around the work like a span- 
 ner, and the handle serves as a lever to pull out the twist. 
 
 Hooped Spindle. — A spindle provided with an eye at one end, either cir- 
 cular or rectangular in outline, which eye embraces a boss cast upon a 
 valve. Often applied to slide valves in place of the ordinary valve rod 
 with lock nut arrangements. 
 
 Hoop Iron. — Thin iron used for securing the comers of packing cases. It 
 is made in widths ranging from f in. to 2^ in., its thicknesses being 
 given ia the numbers of B.W.G-., ranging from No. 21 to 12. 
 
 Hoop L. — The trade mark of the Swedish malleable iron from the Dannc- 
 mora mines, so called from the letter L being placed in the centre of a 
 circle. 
 
 Hoop Tongs. — Smith's tongs whose jaws are bent at right angles with 
 the handles. The jaws lay parallel with each other for the embracing 
 of rings and hoops of flat bar iron. 
 
 Hooter. — A steam whistle used instead of a factory bell to summon the 
 men to work. Hooters can be heard a dozen miles away in a still 
 morning. 
 
 Hopper. — A box or receiver used for the purpose of feeding supplies of 
 materials to machines or furnaces of various kinds. It is often fur- 
 nished with sloping sides, and a valve or cover provides the means of 
 regulating the fall of the contents. Concrete mixers, blast furnaces, 
 gas producers, are furnished with hoppers. 
 
 Horizontal Boiler. — A boiler, the longitudinal axis of whose barrel is hori- 
 zontal. Horizontal boilers embrace Cornish, Lancashire, Galloway, 
 Wagon, and marine types. 
 
 Horizontal Boring Machine. — See Boring Machine. 
 
MECHANICAL ENGINEERING. I8i 
 
 Horizontal Crane. — A portable steam balance crane whose cylinders are 
 set in a horizontal direction, and whose gearing is kept aa low down as 
 possible. See Vertical Crane. 
 
 Horizontal Engine. — ^An engine the longitudinal axis of whose cylinder 
 and piston rod is horizontal. 
 
 Horizontal Lathe. — A boring machine whose axis is set in a vertical 
 direction for the purpose of boring large engine and other cylinders, 
 and rings which would sink and become distorted by their own weight 
 if laid upon their sides in an ordinary lathe or boring machine. 
 
 Horizontal Water Wheel. — A water motor composed of two wheels placed 
 horizontally one above the other, the upper one remaining fixed, the 
 lower one being made to revolve by the pressure due to the head of 
 water. The water passing through curved buckets or vanes in the 
 upper wheel is directed by them against a series of buckets in the lower 
 wheel, the latter being free to revolve on a vertical spindle. Horizontal 
 wheels are mostly superseded by turbines. 
 
 Horizontal Winch. — A steam winch (q.v.) in which the cylinders are 
 placed horizontally on the side frames. 
 
 Hornbeam. (Carpinus.) — A wood of the natural order Cupuliferm. It is of 
 a light colour, very stringy, tough, and of moderate hardness. Used 
 by engineers for the cogs of mortice wheels. A cubic foot weighs 
 47 lbs. Sp. gr. 0-76. 
 
 Hornblock. — A casting of steel or iron riveted to a locomotive framing to 
 receive the axle box, and by means of which the latter is constrained 
 to move in a vertical plane only. 
 
 Horn Centres. — Small transparent discs of horn used by draughtsmen to 
 place the points of their compasses upon when describing circles, to 
 avoid piercing the paper itself. 
 
 Horn Plates. — The wrought-iron or steel frames whose internal edges act 
 as guides to the axle boxes of rolling stock. They are bolted to the 
 truck frames. Also termed axle guards, pedestals, and housings. 
 
 Horns. —The curved levers which are pivoted at the side of a planing 
 machine, and which being knocked over by the tappets give the neces- 
 sary feeds to the tool, and the reversing movement to the table. 
 
 Horse Dung. — This is used in foundries for mixing with the sand from 
 which cores are struck up. It owes its value to the quantity of undi- 
 gested hay which it contains, for this, being desiccated by the drying 
 in the stove, leaves a network of porous channels in the core or loam 
 through which the gases generated by casting find exit. 
 
 Horse Gear. — See Bullock Gear. 
 
 Horse Hair. — Sometimes mixed with loam for the same purpose as horse 
 dung (q.v.). 
 
 Horse Hair Cushion. — A cushion of horse hair placed in the bottom of 
 some types of axle boxes, and which being saturated with oil, forms a 
 reservoir for a worsted pad (q.v.) placed above. 
 
 Horse-Power. — A conventional term whose significations require to be 
 defined to have any practical use. See Actual, Indicated, Nett Indi- 
 cated, and Nominal Horse-Powers. 
 
 Horse-Power transmitted. — The powers which belts, wheels, shafting, 
 &c., are capable of carrying or transmitting from the prime movers to 
 the mechanism which they have to drive, this power being expressed 
 in the unit of 33,000 foot pounds. 
 
 Horseshoe Gauge. — A fixed gauge used for caUpering metal work. It is 
 really a fixed caliper, being out from a solid piece of metal, and its 
 
1 82 DICTIONARY OF TERMS USED IN 
 
 outline approximates to that of a horseshoe, its internal narrowed 
 portion being the part where the measurement is taken. These gauges 
 are kept as standards for repetition work. 
 
 Hose. — Flexible piping of leather or of india-rubber used for the convey- 
 ance of water from force and other pumps where the employment of a 
 rigid channel of transmission would be inadmissible or inconvenient. 
 Leather hose is generally fastened down the seam with copper rivets. 
 India-rubber hose is also cemented entire and seamless at a high tem- 
 perature, iu combination with pressure. 
 
 Hose Coupling. — The mode of jointing together of the ends of hose pipes. 
 Screwed flanges of brass, male and female, are attached to the abutting 
 ends by means of copper wire bound around them. Or ilanges with 
 bolts are simUarly attached. Or brass clips only are made to grasp 
 them. Or a third screwed collar slips over and unites the independent 
 ends. See Union. 
 
 Hose Clip. — See Hose CoupHng. 
 
 Hose Pipe. — India-rubber hose pipe is formed by the alternate winding of 
 friction sheet india-rubber around a mandrel, and subjecting the whole 
 to the vulcanising process. 
 
 Hose Seel. — A drum mounted upon wheels, around which flexible hose is 
 wound for convenience of transit. 
 
 Hot Air Engine. — A motor in which heated air is the agent employed, 
 and of which the essential principle is the alternate heating and cooling 
 of the air used. It contains provision for the rapid heating of the air, 
 which being expanded does work, giving motion to a piston called the 
 power piston ; the air is then allowed to escape and passes through a 
 regenerator (q.v.) to the compression cylinder, where it is rapidly cooled ; 
 thence back through the regenerator to the power cylinder to undergo 
 the same cycle. The methods by which the heating and cooling are 
 effected and the types of regenerators constructed vary in different 
 types of engines, but the principles are the same in all cases. 
 
 Hot Blast, — tlntil the year 1828 it had been the universal practice among 
 ironmasters to smelt the ore by the aid of a current of cold air poui'ed 
 into the tuyeres. But in that year Neilson, of Carron Foundry, in 
 Scotland, introduced the practice of raising the temperature of the 
 blast, with a resulting economy of fuel, hence the distinguishing term 
 "hot blast." The temperature as now used ranges from 700° P. to 
 1,300°P. The iron is inferior and weaker than cold blast iron smelted 
 from the same ores, owing to the presence of silicious compounds in 
 larger quantity, and cold blast scrap is always eagerly sought after by 
 the dealers. 
 
 Hot Iron Saw. — A circular saw made of thick plate and provided with 
 short dumpy teeth, which is used for cutting off iron bars. The bars 
 are previously heated to a low red heat, and the lower portion of the 
 saw runs in cold water. 
 
 Hot Liquor Pump. — A lifting pump (q.v.) which is placed below the hot 
 liquid being pumped, in order that the presence of steam may not in- 
 terfere with the production of a vacuum, which is the case with pumps 
 working under ordinary conditions. Feed pumps for boilers never pump 
 so great a quantity when the feed water is warm as when it is cold. 
 
 Hot Metal. — Molten iron and brass are said to be hot when their tem- 
 perature is higher than that required for the class of work for which 
 they are intended. If too hot the sand becomes oxidised and produces 
 a rough casting. If too cold, the metal does not fill up the mould 
 
MECHANICAL ENGINEERING. 183 
 
 properly and probatly teoomes cold shut (q. v.). Thin works require 
 hotter metal than thicker ones to counteract the chilling influence of 
 the mould. Hot metal scintillates more than cooled or dead metal, 
 and the founder judges of the temperature by its appearance. See 
 Breaking. 
 
 Hot Sand. — Foundry sand which has been watered and mixed immediately 
 after being knocked out of a flask in which a recent casting has been 
 made. The use of hot sand is injurious both to the pattern and to the 
 mould ; the sand sticking to the pattern and producing a bad delivery, 
 and the steam in the mould causing risk of a spongy casting. Hence 
 sand should be allowed to become cold before being used over again. 
 
 Hot Set. — A smith's set, or chisel-hke tool, made thinner than the cold 
 set (q.T.), and used for the nicking and cutting of hot metal. 
 
 Hot Short. — A condition of wrought iron in which it becomes brittle at a 
 welding heat, so that it either does not weld at all, or welds with diffi- 
 culty. It is due to the presence of sulphur. 
 
 Hot Tests. — The testing of the tensile strength of iron and steel bars and 
 plates, by bending them hot to a certain angle, both with and across 
 the grain, without fracture. 
 
 Hot Water Apparatus. — The principle is the circulation of hot water in 
 pipes due to the difEerence in the sp. gr. of columns of water at different 
 temperatures. The cold water being the heavier drives the heated 
 water before it. 
 
 Hot Water Test. — A test to which steam boilers are subjected, the use of 
 hot water foUowiag that of the cold water test. The hot water by 
 expanding the plates tests the soundness of the caulked joints. 
 
 Hot Well. — A reservoir for the hot water pumped out of an engine con- 
 denser by the air pump. 
 
 Housings. — (1) The framings which support the rolls in rolling mills 
 (q.v.). (2) Horn plates (q.v.). 
 
 Housing Screws. — The screws which pass through the caps of rail mill 
 housings for the adjustment of the rolls. 
 
 H.P. — See Horse-Power. 
 
 Hub. — (1) A master tap (q.v.). (2) A term sometimes applied to the 
 boss of a wheel. 
 
 Hunting Cog. — A device of the old millwrights to prevent the unequal 
 wearing of teeth which is supposed to result when the same teeth on 
 wheel and pinion come successively into gear without variation. In 
 other words, when the required number of teeth to produce the neces- 
 sary velocity ratio is determined on, an extra tooth is thrown into 
 wheel or pinion so that they may be primes to each other, or have no 
 common divisor. Thus 72 and 24 should be 73 and 24, or 72 and 25. 
 The extra tooth is termed a hunting cog. 
 
 Hydrated. — See Anhydrous. 
 
 Hydraulic Bear. — A punching bear (q.v.) in which the punch is actuated 
 by the power of water under pressure. It consists of a small cistern of 
 water, a force pump, and ram, with levers. The ojstem is uppermost 
 and incloses the force pump, the ram is below it, and immediately over 
 the pxmch which it actuates. One lever works the pump, another lifts 
 the ram and punch after the hole has been pierced. 
 
 Hydraulic Belt. — ^An endless belt, made of woollen material, which 
 absorbs and holds water readily. The lower bight or bend runs in 
 water, the upper bend passes over a pulley. The belt travels at a high 
 speed, and so lifts the water to the pulley, whence it is discharged. 
 
i84 DICTIONARY OP TERMS USED IN 
 
 Hydraulic Crane. — A crane in which the pressure due to a head of water, 
 or to water pressure obtained by pumping water into an accumulator, 
 is utilised for the Kfting of loads. The water is allowed to flow from 
 the accumulator into a hydraulic cylinder, or cylinders, to whose ram 
 one end of the lifting-chain is attached ; the chain passes thence over 
 pulleys to the jib and the load, the purpose of the pulleys being to 
 increase the speed of lift beyond that of the rate of travel of the ram. 
 The increase in the rate may be 5 or 6 to 1. Hence there is a corre- 
 sponding loss of power, such loss being allowed for in the original 
 designing of the crane. Neither is there any gearing, but the chain 
 passes directly from the sheave pulleys to the jib over the top of the 
 post. It is usual to work several cranes from a single accumulator. 
 
 Hydraulic Cylinder. — The lifting cylinder of a hydraulic press into which 
 the water is pumped under pressure, lifting the enclosed piston. 
 
 Hydraulic Engine. — See "Water Pressure Engine. 
 
 Hydraulic Force Pump, or Hydraulic Fump. — A small brass force pump, 
 made specially strong for pumping water under great pressure for 
 testing purposes, or for hydi-aulic presses. It is essentially an ordinary 
 force pump, but is provided with a safety valve, and attached to the 
 cover of a tank of supply water. 
 
 Hydraulic Forging Press, — A form of hammer used for stamping iron 
 or steel articles to definite shapes in dies. The moving head, which 
 corresponds with the tup (q.v.) of a steam hammer, is actuated by 
 water stored in an accumulator, hence the force exerted is of a com- 
 pressive nature rather than that due to impact. The working faces 
 may be either flat surfaces, or dies, according to the class of work in 
 hand. 
 
 Hydraulic Gauge. — A dial pressure gauge, constructed to sustain and to 
 indicate very high pressures. Usually gauges of this description are 
 made for a maximum pressure of five or of ten tons to the inch, or, 
 reckoned in pounds, of from to 6,000, or 10,000, or 20,000 lbs. per 
 square inch. Also, and more correctly, termed a hydrostatic 
 gauge. 
 
 Hydraulic Glue. — Glue which has the property of partially resisting the 
 action of moisture. It is made by dissolving glue in skiimned milk, or 
 by adding a httle linseed oil and oxide of iron to ordinary glue. 
 
 Hydraulic Hammer. — A hydraulic forging press (q.v.). 
 
 Hydraulic Jack. — A lifting jack actuated by a small force pump inclosed 
 within it, and worked by a lever from the outside. Such jacks lift 
 either from the foot or from the top. 
 
 Hydraulic Leather. — A cup leather (q.v.) 
 
 Hydraulic lift. — A lift worked by water power, the necessary head being 
 obtained from a tank situated in the top of the building where it is 
 erected. The water pressure actuates a ram or plunger moving water- 
 tight in a cylinder. The cage is attached to the head of the ram, the 
 accumulator (q.v.) being sunk in the ground. A lift is direct-acting 
 when the stroke of Ihe accumulator piston is equal to the extreme 
 travel of the lift ; or indirect when the stroke of a short plunger is 
 multiphed by sheave wheels and ropes. The weight of the lift itself is 
 counterbalanced by weights. 
 
 Hydraulic Motor. — A motor whose source of energy is derived from the 
 power of water. 
 
 Hydraulic Pipe Prover. — A piece of apparatus employed for testing pipes 
 by water pressure. The pipe to be tested is made fast between standards, 
 
MECHANICAL ENGINEERING. 185 
 
 the flange faces being rendered -water-tight by means of india-rubber 
 ■washers, and the water pumped to the required pressure by means of a 
 force pump having an escape valve, and a weighted lever for the regu- 
 lation of the exact amount of pressure requii-ed. 
 
 Hydraulic Piston. — A plunger piston used in force pumps and hydrauUo 
 cylinders generally. It is a soKd piston, no liquid passing through its 
 body. 
 
 Hydraulic Press. — A machine in which the incompressibility and pressure 
 of water are utOised to produce an immense effect with Uttle expendi- 
 ture of power. It comprises the pressing area, actuated by a plunger 
 or ram moving in a water-tight cylinder, and a force pump by which 
 the pressure is imparted. See Hydraulic Force Pump. Hydraulic 
 presses are used for compressing articles for exportation and for 
 squeezing oils, &c. , out of their seeds. 
 
 Hydraulic Pump. — See Hydraulic Force Pump. 
 
 Hydraulic Kam or Water Ram. — A machine in which water is raised from 
 a lower to a higher level by its own momentum. Water is allowed to 
 flow with the velocity due to its head into a horizontal drive pipe sup- 
 plied with two valves opening in opposite directions. The momentum 
 of the water soon closes the farthest valve which is made to open inwards, 
 and the arrested fluid then opens the other valve outwards and passes 
 into a supply pipe provided with an air vessel. Being thus relieved of 
 pressure, the inward opening valve falls and the water passes tlirough 
 it until it has again acquired sufficient momentum to open the supply 
 valve once more. An efficiency of about 70 per cent, is obtained from 
 hydraulic rams. 
 
 Hydraulic Eiveter. — A riveting machine consisting of one movable and 
 one lever jaw at whose extreme ends the dies are placed. The movable 
 jaw is actuated by cylinders placed in communication — the one with an 
 
 . accumulator and the other with an exhaust cistern of water. 
 
 Hydraulics, or Hydrodynamics. — Treats of the motion of Kquids, as 
 opposed to hydrostatics. All questions and problems relating to the 
 flow and effiux of water or other liquids in pipes, from orifices, rams, 
 friction of liquids, &c., are embraced by hydraulios. 
 
 Hydraulic Shearing Machine. — A shearing machine in which water is the 
 motive power. 
 
 Hydraulic Test. — The testing of the strength of structures which have to 
 sustain high pressures by the forcing in of water from a force pump. 
 Pipes, air vessels, steam boilers, &o., are thus tested to about double 
 their anticipated working pressure. 
 
 Hydraulic Tube. — The stoutest solid drawn wrought-iron tube made. It 
 is about twice as thick as common tubing, and is used for hydraulic 
 pump connections and for high steam pressures. 
 
 Hydraulic Wheel Press. — A wheel press in which hydraulic pressure 
 is employed instead of that of screw bolts for pulling wheels on or 
 off their axles. It embraces cylinder and ram, pump, and gear for 
 drawing back. 
 
 Hydro - Carbons. — Compounds of hydrogen and oxygen, either solid, 
 liquid, or gaseous. They are organic compounds, highly inflammable, 
 and are important constituents in fuels and in lubricating oils. 
 
 Hydro-Carbon Oils. — Mineral oils (q.v.). 
 
 Hydrochloric Acid. — Symbol, H CI. A compound of chlorine and hydro- 
 gen, with water. It is used as a flux for soldering. Dilute H CI. is used 
 sometimes for rusting metal patterns and the faces of chilling moulds, 
 
t86 DICTIONARY OF TERMS USED IN 
 
 and for dissolving the scale from boiler plates. CaEed also muriatio 
 acid, and spirits of salts. 
 
 Hydrodynamics. — See Hydraulics. 
 
 Hydrogen. — Symbol, H. Comb, weight, 1 . A gas possessing high calorific 
 power when in union with oxygen. It is the hghtest body known, all 
 other elements being referred to it as unity. It is formed in foundry 
 moulds by the decomposition of the moistm-e contained therein, and 
 bums at the Tent holes with its characteristic blue flame. 
 
 Hydrostatic Gauge. — A hydraulic gauge (q.v.). 
 
 Hydrostatic Press. — A hydraulic press (q.T.). 
 
 Hydrostatics. — Treats of the equilibriuin and pressures of fluids at rest. 
 
 Hygroscopic Water. — ^Water which is not in the condition of chemical 
 combination. Applied to flie-olays and other absorbent bodies. It is 
 capable of being driven off by the application of a moderate amount of 
 heat. 
 
 Hyperbola. — One of the conic sections cutting the side of the cone at an 
 angle less than a parabola. The curve of expansion of a gas under the 
 conditions of Boyle and Marriott's law is that of a hyperbola. 
 
 Hyperbolic Logarithm. — The conunon logarithm of a number multipKed 
 by 2-3025So05. Conversely the hyperbolic logarithm multiplied by 
 •43429448 gives the common logarithm. Hyperbolic logarithms are 
 employed to facilitate calculations relative to the expansive working of 
 steam. 
 
 Hypocycloid. — A cycloidal curve formed on the interior of a base or 
 fundamental circle. The curves of the flanks of wheel teeth are com- 
 monly hypocycloids. 
 
 Hypotheneuse. — The diagonal which joins the sides of a right-angled 
 triangle. 
 
 I. — The usual algebraic expression employed ia mechanical calculations 
 to designate the moment of inertia (cl.v.). 
 
 Ideal Engine. — See Perfect Engine. 
 
 Idler.— See Idle Wheel. 
 
 Idle Wheel, or Idler. — A wheel introduced into a train of gearing for the 
 purpose of filling up an hiatus, or of changing the direction of motion 
 without influencing the velocity ratio. Called also a cock wheel. 
 
 Igniter. — The agent by which the gaseous charge of a gas engine is 
 ignited. It is either a jet of gas or a spiral of platinum wire rendered 
 incandescent by electricity or by a gas jet, or some refractory materia] 
 kept constantly heated to a sufficiently high temperature. 
 
 Ignition. — The lighting of the charge in gas engines, effected directly 
 either by a jet of gas or by an electric spark, or indirectly through the 
 heating of platinum wire. 
 
 Ignition Slide. — An ignition valve (q.v.). 
 
 Ignition, Speed of. — See Speed of Ignition. 
 
 Ignition Valve. — The valve of a gas engine which opens to permit of the 
 ignition of the charge, but closes as soon as this is effected. 
 
 I.H.P. — Indicated horse-power (q.v.). 
 
 Impact. — The sudden fall of a load upon a beam or structure. The deflec- 
 tion of beams varies nearly as the velocity of impact. 
 
 Impact Wheel. — ^A water wheel which is driven by the percussive force 
 
MECHAmCAL ENGINEERING. 187 
 
 of -water acting at right angles to the floats, and at a tangent to the 
 circumference of the wheel. Turbines (c[.t.) are impact wheels. 
 
 Imperial. — A drawing paper of ordinaiy quality, sold in sheets measur- 
 ing SO inches by 22 inches. It can be had either rough or smooth. 
 
 Impermeator. — A form of self-acting lubricator used for engine cylinders. 
 It charges the steam with greasy matter, and depends for its efEoiency 
 on the difference in the specific gra-rities of water and oil. It is screwed 
 into the steam pipe or the valve chest, and consists of a brass cylinder 
 containing in tiie top a chamber and cock for filling in the oil, and in 
 the bottom two valves, one communicating with the steam chest down- 
 wards and with a small tube of brass reaching upwards nearly to the 
 top of the interior of the brass cylinder, and the other leading direct 
 from the steam chest into the bottom of the brass cylinder. The 
 cylinder having been nearly iiUed with oQ, the first valve is opened ; 
 steam rushing up through the tube, condenses, and, forming water, falls 
 to the bottom, floating the oil up to the top, which overflows iato the 
 brass pipe, and so affords a constant supply through its valve as long as 
 any oil remains in the vessel. In some forms a glass index gauge 
 affixed to the outside of the impermeator indicates the height of the fluid. 
 
 Imposed Load. — The load which is extraneous to a structure, as distin- 
 guished from that due to the structure itself. 
 
 Impregnation. — Timber for outdoor use is impregnated with various fluids 
 or salts, to enable it the better to resist the decomposing influences of 
 the atmosphere. See Burnett's lluid, Greosoting, Kyanising. 
 
 Improving rnrnaoe. — A reverberatory furnace in which the foreign com- 
 ponents found ia hard lead (q.v. ) are oxidised out. 
 
 Impulse. — The term is apphed to the motion of the piston of a gas engine 
 which is due directly to the explosion of the charge ; thus an impulse is 
 said to occur at each revolution, or an impulse at every two revolutions, 
 as the case may be. 
 
 Impulsive load. — A load applied suddenly to a structure. The structure 
 is thus subject to the accumulation of energy due to the impact of the 
 load, or that gathered in its motion, ia addition to its actual dead 
 weight. 
 
 Inch. — The English standard of length, usually subdivided iato eighths and 
 subdivisions of the eighth, as sixteenths, thirty-seconds, &c. The im- 
 portance of the inch in engiaeering cannot be overestimated. Areas, 
 cubical contents of volumes, are estimated in terms of the square and 
 cubic inch. Heads, pressures, are estimated in inches. The weight of 
 the solid contents of materials is deduced from the number of cubic 
 inches which they contain. The sections of materials are given in 
 inches when calculating their strains and stresses. 
 
 Inch Pound. — A unit of calculation signifying one pound lifted one inch 
 high. See Units. 
 
 Inch Ton. — A unit of calculation denoting one ton lifted one inch high. 
 
 Inclination of Boilers. — Lancashire and Gomish boilers are incHned for- 
 wards about half an inch in ten feet to ensure proper draiaage through 
 the blow-off cock. Fire bars are inclined backwards about one in 
 ten to allow of the fuel being moved rapidly away from the dead 
 plate. 
 
 Inclined Cylinder Engine. — A type of marrae engine in which the cylin- 
 ders are inclined towards each other at an angle of about 102°, making 
 a triangle with the base or ground liae. They are connected by cranks 
 to a common crank shaft. 
 
i88 DICTIONARY OF TERMS USED IN 
 
 Inclined Plane. — A plane wHoh is inclined to tlie plane of the horizon, 
 the angle -wliich it makes therewith being termed its inclination. In 
 the inclined plane the power hears the same relation to the weight 
 which it will sustain that the height of the plane bears to its length. 
 Hence the greater the height in relation to the length the greater the 
 power which will be required to sustain a given weight. The wedge 
 and screw are each examples of common applications of the principle of 
 tile inclined plane. 
 
 lucompressibility. — A property of liquids which is utilised for the trans- 
 mission of power in hydraulic cranes, lifts, pistons, &c. The com- 
 pressibility of water under the pressure of one atmosphere is '000048, 
 an amount altogether inappreciable in practice. 
 
 Increase Twist Brill. — A twist driU in which the angle of the twisted 
 groove increases as it recedes from the point in order to adiord greater 
 freedom of delivery to the abraded fragments. 
 
 Increasing Pitch. — A screw is said to be of increasing pitch when the 
 distance between each blade, or rather between each successive turn of 
 the helix, supposing the blades were thus prolonged, increases in 
 amount ; or the pitch may increase in the direction of the length of the 
 blade from the centre to the circumference. 
 
 Incrustation. — The coating of the internal portions of an engine boiler 
 with carbonate and sulphate of Hme, and other sohds deposited from the 
 feed water. Various remedies are employed to prevent and to remove 
 this as far as possible. 
 
 Independent Jaw Chuck. — A dog or jaw chuck whose jaws move inde- 
 pendently of each other, as distinguished from a concentric jaw chuck 
 
 (q-v.). 
 
 Independent Machines. — Alludes to the practice now becoming common 
 of driving boilermakers' and the larger kinds of engineers' machines by 
 a small independent engine, so that each machine can be stopped and 
 started independently of a main line of shafting. 
 
 Independent AVhip Crane. — See Platform Crane. 
 
 Index. — (1) The figure above and to the left of an algebraic symbol, which 
 expresses the number of times by which it has to be multiplied into 
 itself. Also called the exponent. (2) The finger or pointer of a float 
 gauge, which indicates the height of the water level in a steam boiler 
 or tank. 
 
 Index Peg. — A division peg (q.v.). 
 
 Indian Ink. — The lines of mechanical drawings are done with indian ink 
 in preference to common ink, as being less liable to run, and not soon 
 fading. It is sold in cakes, and also fluid in bottles ready for use. 
 
 India-rubber, or Caoutchouc. — The natural juice of a tree called the 
 syringe tree [Siphonia elastica) , found in Cayenne and about the lower 
 part of the Amazon River, in South America. It dries on exposure to 
 the air, and its property of elasticity renders it highly useful for an 
 infinity of purposes. It is chiefly used in the vulcanised form, which is 
 a preparation of the gum with sulphur, and also variously with sulphate 
 of zinc, plaster of Paris, pitch, whiting. In this condition it is used 
 for belting, hose pipe, washers, air pump, and other valves, &c. See 
 also Ebonite. 
 
 Ind'a-rubber Belting. — Belting made by subjecting several thicknesses 
 or plys of india-rubber cloth to heat and pressure combined, the required 
 temperature being about 280° P. 
 
 India-rubber Core Packing — Packing which is provided with an internal 
 
MECHANICAL ENGINEERING. 189 
 
 core of india-rubber ; it is made by painting strips of friction cloth 
 with rubber solution, and rolling them around an india-rubber or other 
 core. 
 
 India-rubber Insertion Sheet. — See Insertion Sheet. 
 
 India-rubber Pipe.— See Hose Pipe. 
 
 India-rubber Bing, — Rings of solid india-rubber of circular cross section 
 are used as steam and water tight packings for gauge glasses, and 
 sometimes also for condenser tubes and pipe flanges. 
 
 India-rubber Bing Joint. — A pipe joint in which a ring of india-rubber 
 supplies the place of ordinary caulking. Accumulator and hot water 
 pipes are Jointed with india-rubber rings. 
 
 India-rubber Spring. — Buffer springs (q.v.) are often made of india-rubber. 
 
 India-rubber Tube. — Solid india-rubber tube is made by pressing rubber, 
 rendered plastic by means of heat, through a funnel-shaped receptacle, 
 at the termination of which is a die corresponding in diameter with that 
 of the pipe required, the bore being formed by a centre core in a similar 
 manner to lead pipe. It is afterwards vulcanised, a metal mandrel 
 being inserted to preserve the shape. 
 
 India-rubber Washer. — Used for hydraulic work. A flange washer is a 
 flat ring ; a socket washer a ring of circular cross section ; a bevel 
 washer a flat ring washer, whose faces are bevelled in relation to each 
 other ; a joint washer, one made to any outline required. 
 
 Indicated Horse-Power. — (1) The mean effective pressure of the steam in 
 an engine cylinder multiplied by the area of the piston in square inches 
 and by the piston speed in feet per minute, and the product divided 
 by 33,000, gives the Gross I.H.P., or the power exerted by the steam. 
 To obtain the net horse-power, the friction of the engine has to be 
 deducted therefrom. (2) The power as denoted by the indicator (q.v.). 
 
 Indicating. — Indicating an engine signifies the taking of an indicator 
 diagram (q.v.) and deducing the horse-power therefrom. 
 
 Indicator. — An instrument used for showing the pressure and behaviour 
 of the steam in an engine cyhnder. It consists of a piston working 
 freely yet closely in a cylinder, the area of the piston being exactly half 
 a square inch. A spiral spring of definite strength is placed above the 
 piston, and the piston rod is connected by levers to a pencil of brass 
 wire. A drum of 2-in. diameter forms a part of the instrument, and 
 this drum receives a semi-rotatory motion from the engine during its 
 forward stroke, being pulled back by a spring during the backward 
 stroke. The instrument is screwed into the cylinder in any convenient 
 spot, usually at the covers, and by means of a stop-cock the inner por- 
 tion of the indicator cylinder can be opened to the steam in the cylinder 
 or to the atmosphere ; the upper side of the piston is always open to the 
 air. When the under side is open to the air the line which the pencil 
 traces on the paper on the drum is horizontal, giving the atmospheric 
 line ; when the steam is admitted below the piston the latter is forced 
 up, and the pencil traces a line around the moving paper, which indi- 
 cates the action of the steam, and from which the pressure at any point 
 of the stroke and the mean pressure can be deduced. 
 
 Indicator Card. — The slip of prepared paper wliich is wound upon the 
 drum or cylinder of an indicator (q.v.), and upon which the indicator 
 diagram (q.v.) is traced. 
 
 Indicator Cock. — The cock by which a communication is made or broken 
 between the piston of the indicator and the engine cylinder into which 
 it is screwed. 
 
igo DICTIONARY OF TERMS USED IN 
 
 Indicator Diagram. — A diagram of work traced by the pencil of the in- 
 dicator upon an indicator card. IVom it are deduced both the behaviour 
 and the mean effective pressure of the steam in the cylinder, and thence 
 the indicated horse-power. To obtain the mean effective pressure the 
 area of the card is divided transversely by equidistant ordinates, ten or 
 more as most convenient, perpendicular to tiie atmospheric line, whose 
 average lengths are measured, and the whole added together and divided 
 by the number of divisions. 
 
 Indifferent Equilibrium. — The equilibrium of a body which is neither 
 stable nor unstable. If when a body is moved longitudinally the 
 centre of gravity moves in a horizontal line, as in a sphere, the equi- 
 libriiuu is said to be indifferent. 
 
 Indirect Acting Slide Valve. — A slide valve whose motion is not derived 
 directly from the eccentric throw and rod, but from an intermediate 
 rocHng shaft or double-ended lever, attached, one end to the valve 
 rod, and the other end to the die block of the slot link. This form of 
 valve gear is used on some locomotives. 
 
 Indirect Action. — The motion of parts whose linear stroke or travel is 
 not the same as that of the portion of mechanism from which they 
 derive their motion. The motion is therefore derived indirectly through 
 the medium of levers, as distinguished from direct action. 
 
 Indirect Process. — The mode of production of malleable iron from pig 
 iron, as distinguished from the direct process. The indirect processes 
 include the open hearth or wet puddlmg treatment, and the ordinary 
 dry puddling in the reverberatory furnace. Inferior ores can be 
 reduced better in the indirect, than in the direct processes. 
 
 Induction. — The admission of steam iato a cyUnder. 
 
 Induction Port. — The port which is open to the admission of steam into 
 a cylinder for the time being. Each of the steam ports are termed 
 induction ports, in opposition to the exhaust port, or the one through 
 which the exhaust steam escapes into the atmosphere. 
 
 Inertia. — That property of matter in virtue of which it resists the 
 tendency of forces impressed upon it from without to cause it to change 
 its position. 
 
 Inertia, Moment of. — See Moment of Inertia. 
 
 Ingate. — The opening or orifice through which the molten metal is 
 poured into a mould. Frequently termed a gate simply. Sometimes 
 used to include the whole of the passage or runner (q.v.). 
 
 In Gear. — -Wheels are said to be in gear when their teeth are mutually 
 engaged with each other, pitch line to pitch line. 
 
 Ingot. — (1) Metal after being purified by melting is run into metaUio 
 moulds usually containing the founder's brand. These moulds are 
 oblong in shape, and the rectangular block of metal ready for re- 
 melting is called an ingot. (2) Cast steel before being hammered or 
 rolled is melted and poured into an ingot mould (q.v.) to render it 
 homogeneous. 
 
 Ingot Crane, — A crane used for lifting steel ingots into the soaking pits 
 (q.v.). 
 
 Ingoting. — The melting of brass or gun-metal scrap and pouring it into 
 ingots for the piirpose of future remelting. The object of ingoting is 
 the preparatory purification of the metal by tlie removal of the dross 
 from its surface when molten. 
 
 Ingot Mould. — The mould in which ingots are cast, varying from the 
 small branded moulds for copper and brass to the large and massive 
 
MECHANICAL ENGINEERING. 191 
 
 moulds made for casting- ordinary steel ingots. These last are conical in 
 form, used for the casting of the steel from the ladle or converter 
 before it is passed on to the rolling mills. Such moulds are made in 
 cast iron, averaging from 4 to 6 in., or more in thickness, according to 
 the size of the ingot. They are accurately bored. The ingots may 
 ■weigh from five to six tons each. Sir Joseph Whitworth oasts some 
 ingots ujider a hydraulic pressure of several tons to the square inch, 
 for Tvhich the moulds are made of special construction — an outer 
 cylinder of steel banded with steel hoops, enclosing an inner lining 
 of cast-iron lagging, -which contains -within it again a lining of 
 refractory material. Some moulds also are oblong in section. 
 
 Initial Condensation. — The condensation -which steam undergoes when 
 issuing from -fche boiler into a cylinder colder than itself. Jacketing 
 (q.v.) prevents this from taking place. The term is employed to dis- 
 tinguish it from condensation which takes place in an unjacketed 
 cylnider, both on the first entry and during subsequent expansion and 
 doing of work. See also Ee-evaporation. 
 
 Initial Pressure. — The pressure at which steam is admitted into a 
 cylinder. 
 
 Injection. — (1) The dra-wing or induction of water into a steam boiler by 
 means of an injector (q.v.). (2) The pumping of water into the condenser 
 of a steam engine. 
 
 Injection Cock. — The cock through which the supplies of water to the 
 condensers of marine engines pass. 
 
 Injection Condenser. — See Jet Condenser. 
 
 Injection Orifice. — The orifice of the injection pipe in a jet condensing 
 engine. Its diameter is estimated in reference to the quantity of water 
 requisite to effect the condensation of the steam. Its area may bie 
 roughly taken at 3^5- of a square inch per cubic foot of water evaporated 
 from the boiler. 
 
 Injection Pipe. — The pipe which conveys the water to a jet condenser 
 (q.v.). 
 
 Injection Valve. — See Injection Cock. 
 
 Injection Water. — The water pumped into a jet condenser. It is drawn 
 either from the sea or from the bUge. 
 
 Injector.— An instrument used for afiording a continuous supply of feed 
 water to a steam boiler. It depends for its efSciency on the principle 
 that a jet of high pressure steam, issuing from a boiler at a high 
 velocity, -will induce a current of cold water to flow into the same boiler 
 against the pressure of the water in the boiler ; aU injectors, however 
 their details may vary, act by producing an induced current of feed 
 water in this way. 
 
 Inlet Valve. — A foot valve (q.v.). 
 
 In Line. — "Work is said to be in line when it is in the same centre, or in 
 the same plane. To get several distant points in line, measurement is 
 taken from a kno-wn level surface, spirit levels are tried upon straight 
 edges, or a fine chalk line is strained tightly, or a theodolite is employed. 
 
 Insertable Teeth, — A practice introduced of making teeth of large circular 
 saws distinct from the saw plate itself, attaching them thereto with 
 screws. Its advantage is supposed to consist in the readiness with which 
 broken teeth are replaced. 
 
 Insertion Joint. — A joint rendered steam or water tight by the insertion 
 of an india-rubber disc or ring. 
 
 Insertion Kubber. — Vulcanised india-rubber, in which layers of rubbe;' 
 
192 DICTIONARY OF TERMS USED IN 
 
 alternate with layers of canTas. It is named 2, 3, 4, 5, 6, fee, ply, 
 according to the number of layers of which it is composed. 
 
 Insertion Sheet. — Thin sheeting composed of india-rubber and brass 
 wire. Used for making steam joints. 
 
 Inside Calipers. — See Caliper. 
 
 Inside Crank. — An engine crank whose position lies between the crank- 
 shaft bearings. 
 
 Inside Cylinders. — Locomotive cylinders placed within the framing and 
 smoke box and connected up to the cranks. 
 
 Inside Fire Box, — The actual fire box of a locomotive boiler, which en- 
 closes the fuel and flame. It is usually of copper, and is stayed to the 
 outside irre box (q.v.) with short stays. 
 
 Inside Framing. — A form of locomotive framing where the wheels are 
 inside the main frames. 
 
 Inside Gouge. — A paring gouge, so called because it is ground on the 
 inside or hollow face. See Paring Gouge. 
 
 Inside Jaw. — The jaw of a lathe chuck which is outside of the work 
 which it clips. 
 
 Inside Lap. — Exhaust lap (q.v.). 
 
 Inside Lead, or Internal Lead. — The lead to exhaust in an engine cylin- 
 der, produced by making the length of the hollow of the slide valve 
 measure in the direction of its travel more than the distance between 
 the exhaust edges of the ports. Its purpose is to allow of the free 
 escape of the exhaust steam from the passage. 
 
 Inside Screw Tool. — See Internal Screw Tool. 
 
 Inside Tool. — A turning tool bent at a right angle for getting at the 
 internal portions of turned work. 
 
 Inspection, — ALL the larger and more important works erected by engi- 
 neers have to pass inspection by a properly appointed person before 
 the contract is declared completed. The inspection in the larger con- 
 tracts proceeds continuously with the progress of the work, but in many 
 cases is done only when the order is declared by the contractors to be 
 completed. Inspection to be thorough, embraces the testing of the 
 quality of the materials used, the suitability of the minor details of 
 construction to the purposes for which they are designed, the excellence 
 of workmanship, both general and minute, and the capability of the 
 structure or machine. Inspectors are usually men who have had a prac- 
 tical as wen as a theoretical training, and large power of altering and 
 amending minor details, and of condenaning bad material and work- 
 manship, are vested in them. In almost all specifications it is stipu- 
 lated unconditionally that all work is to be executed to the satisfaction 
 of the inspector, and that he shall have the power of ordering such 
 alterations as he may deem necessary. 
 
 Inspection of Boilers. — See Boiler Testing. 
 
 Instantaneous Centre. — The momentary centre around which a system of 
 bodies or Unks in a piece of mechanism may be supposed to rotate for 
 an instant. Notwithstanding that the relative positions of such bodies 
 or links may be constantly changing, yet at any instant they will be 
 turning round a common centre, which centre, however, shifts in 
 space with each new relative position of the links. The determination 
 of the virtual centre, as it is sometimes called, is of use in estimating 
 the relative velocity, ratios, and forces acting upon bodies. The 
 instantaneous axis is perpendicular to this centre ; the cenirode is the 
 curve described in space by the instantaneous centre as it travels from 
 
MECHANICAL ENGINEERING. t93 
 
 one position to another. The term instantaneous is used to diatinguiah 
 it from a, permanent centre, or one which is fixed in space. 
 
 InstantaueouB Grip Vice, or Sudden Grip Vice. — A vice wliich is provided 
 with levers, a toggle-joint, and rack, by means of which it is enabled to 
 clasp work without the loss of time iavolved in turning a screw. 
 
 Instroke. — In a gas engine, is the reverse of an outstroke (q.v.). 
 
 Instrumental Arithmetic. — Mathematical results obtained either by simple 
 inspection, or by simple calculations aided by inspection, instead of by 
 elaborate calculations. The slide rule, the sector, and the various com- 
 puting scales are the aids to instrumental arithmetic. 
 
 Interceptor. — ^A T"Shaped cylindrical vessel employed in connection with 
 marine engines to prevent particles of water from being carried over 
 with the steam into the cylinders. The steam in its passage through the 
 interceptor meets with a diaphragm plate by which the water is thrown 
 down, to be subsequently let off by a drain cock. Called also catch water. 
 
 Interchangeable. — In the best work where several machines or engines of 
 the same type are being ordered, it is the custom to stipulate that all 
 parts shaUbe interchangeable, so that the delay of marking each section 
 and selecting the special parts for each machine or engine is saved. 
 Also the manufacturer is better able to supply spare parts at a future 
 time for the repair of any one of the machines or engines. When any 
 kinds of machines are made in large quantities by a firm, their sections 
 are also interchangeable, so that a piece can be taken from one machine 
 and attached to any other of similar type and size. 
 
 Intermediate. — A term applied to a shaft, pipe, lever, flange, or any 
 portion of mechanism placed between other portions of the same 
 character with which it is immediately connected. 
 
 Intermediate Receiver. — A vessel or casing employed on some compound 
 engines as a steam chamber or reservoir between the high and low pres- 
 sure cylinders. It is rendered necessary when the cranks of the two 
 cylinders are set at right angles with each other, so that when one 
 piston is at full the other is at mid-stroke. Its efEect is also to equalise 
 the back pressure in the high pressure cylinder, and to diminish the 
 variations in its temperature. 
 
 Intermediate Shaft. — ^A shaft placed between first and third motion gear- 
 ing, acting as a carrier of motion between the two, with or without 
 change of power. 
 
 Intermittent Feed. — The feed given to a machine tool, or to the work, by 
 means of a pawl and ratchet movement, as distinguished from con- 
 tinuous feed (q.v.). 
 
 Intermittent Load. — A live load (q.v.). 
 
 Internal Calipers See Caliper. 
 
 Internal Corrosion. — See Boiler Corrosion. 
 
 Internal Flange. — A flange running round the inner diameter of a pipe 
 or cyUnder. Used on foundation, and other large cylinders and pipes. 
 
 Internal Flue. — The flue of an internally fired boiler, which is therefore 
 enclosed within the shell. Examples occur in Lancashire, and Cornish, 
 and marine boilers. 
 
 Internal Forces. — Forces which act between the different parts of a body 
 cr systems of bodies taken as a whole. These, therefore, are distin- 
 guished from external forces, and produce stresses. 
 
 Internal Gear. — When spur wheels or pinions engage with teeth set on 
 the internal diameter of a ring, the gear is called internal. This is the 
 reverse of epur gearing ((J-t.). 
 
 
 
194 DICTIONARY OP TERMS USEt) IN 
 
 Internal lead. — See Inside Lead. 
 
 Internally Fired Boiler. — A toiler whose fuel is tumt in a tute or tutes 
 ■within the boiler itself. Of this type are the Cornish, with one flue, 
 and the Lancashire, with two flues, the smaller double flues giving the 
 same amount of heating surface without the weakness of the larger 
 single one. The marine return flue boiler, and the locomotive and 
 portable with internal tubes, and the vertical with uptake and cross 
 tubes, or !Field tubes, are also internally fired. 
 
 Internal Pressure. — The pressure on the interior of a cylinder is obtained 
 by multiplying the pressure in pounds per square inch into the area of 
 a plane, which divides it longitudinally through its largest diameter, 
 the forces acting on each side of that plane. In a cylindrical shell 
 the intensity of longitudinal stress is only half as great as that in the 
 circumferential direction. In a thin spherical shell the stress is only 
 half as great as in a cylindrical shell taken under similar conditions of 
 diameter, thickness, and pressure. 
 
 Internal Screw, or Internal Thread. — A screw-thread cut upon an inside 
 cylinder. 
 
 Internal Screw Tool, or Inside Screw Tool. — A chaser or a screw tool 
 (q.v.) cranked or bent at right angles, and used for cutting or chasing 
 the threads of internal screws (q.v.). 
 
 Internal Stresses. — Stresses set up in the internal portions of castings, 
 and due to unequal contraction caused by differences in their mass. 
 The stresses are tensilo in character. To prevent internal stress, 
 regard must be had to suitable proportioning of parts and to proper 
 cooling (q.v). 
 
 Internal 'WTieel. — See Annular Wheel. 
 
 Intrados, or Soffit. — The interior or under surface of an arch. 
 
 Inverse Squares. — The principle or law of inverse squares is of very 
 general application in engineers' calculations relating to beams, bars, 
 and structures. 
 
 Inverted Cylinder. — An engine cylinder in which the piston rod is vertical, 
 and passes downwards through the bottom cover. 
 
 Inverted Cylinder Engine. — A vertical engine in which the cylinder is 
 inverted, and therefore above the piston rod, connecting rod, and crank. 
 Sometimes called the steam-hammer pattern. Most maiine engines are 
 now buUt on this type. 
 
 Involute Teeth. — Teeth whose flanks are formed by the unwinding of a 
 cord from a base line. They differ from cycloidal teeth in this, that the 
 centres of a pair of such wheels may be varied within certain limits 
 without affecting their true contact and regularity of motion. They 
 are used chiefly in rolling mills where the centres of the rolls are 
 variable. Owing to the small angle of their tangent lines, it is impos- 
 sible to use small pinions with this gear. 
 
 Inward Flow Turbine. — See Turbine. 
 
 Iron. — Symbol, Fe. Comb, weight, 56. The mostvaluahle metal in existence. 
 It is never found absolutely pure, ovring to its avidity for oxygen, with 
 which it combines in three proportions, forming Ferrous oxide Fe 0, 
 Ferric oxide Fez O3, and the Magnetic oxide Fes O4. It combines with 
 chlorine, forming Ferrous chloride Fe CI2, Ferric chloride Fez Cle ; with 
 sulphur, forming Ferrous sulphate Fe SO4 -}- 7 H3 0, Ferrous sulphide 
 Fe S, and Ferric sulphate Fez (804)3 ; with carbonic acid to form Fer- 
 rous carbonate Fe CO3. See Cast Iron, "Wrought Iron, MaUeablo Cast 
 Iron, Steel, &o. 
 
MECHANICAL ENGINEERING. rgs 
 
 Iron Borings. — ^The borings from tie machine shops are preserved and 
 used for the caiilking (q.v.) of -water-tight joints. 
 
 Iron Cement. — The material used for making rust joints (q.v.) It consists 
 of iron borings (q.v.), passed through an |- or J sieve (depending on the 
 thickness of the joint space), and mixed with sal-ammoniac (about an 
 oz. to the hxmdred-weight of borings) and damped. Sulphur is some- 
 times added. 
 
 Iron Contraction. — See Contraction, Contraction Rule. 
 
 Iron Founding. — See Moulding. 
 
 Ironing. — The sleeking or smoothing over of the face of a founder's mould. 
 
 Iron Man. — A term applied by boiler-makers and platers to a riveting 
 machine. 
 
 Iron Moulder. — See Moulder. 
 
 Iron Moulding. — See Moulding. 
 
 Iron Ore. — The ores of iron are numerous, comprising the magnetic, the red 
 and brown haematites, and the various ironstones. The haematites 
 yield the best irons, but the clay and black band ironstones afford the 
 largest commercial products. Fop details see the various headings. 
 
 Iron Oxide. — See Bust, Ferric Oxide, &o. 
 
 Iron Oxide Faint. — Paint used as a protective coating for castings, pre- 
 pared from an iron oxide earth originally found at Srixham, in Devon- 
 shire. It is prepared for use by mixing with linseed oil, and is cheaper 
 than lead paints, while its affinity for iron renders it more suitable as a 
 protection for that metal than the ordinary lead paints. 
 
 Iron Pattern. — See Metal Pattern. 
 
 Iron Plates. — See Plate. 
 
 Iron Eopes. — See Wire Ropes. 
 
 Iron Sheets. — See Sheets. 
 
 Iron Stone. — A generic term applied to several ores of' iron, having 
 cUfflerent compositions, but possessing the common characteristics of 
 being largely admixed with earthy matters. These are the principal 
 sources of commercial iron of English manufacture. See Black Baud 
 Ore, Clay Band. 
 
 Iron Tubing. — Wrought-iron tubing which is either welded or soKd 
 drawn (q.v). Welded tube is either butt, or lap welded, is thin and un- 
 suitable for withstanding high pressures, and is, therefore, employed 
 for gas and water, steam at comparatively moderate pressures, also for 
 plain handrailing and a multitude of misoeUaneous purposes besides. 
 Sohd drawn (q.v.) tubes vary very much in thickness, and being homo- 
 geneous are more reliable. 
 
 Iron Turner. — Iron turning is quite a distinct section of engineering, the 
 turner seldom or never leaving the lathe to go to the vice, either for 
 fitting or erecting. His skill consists in proper grinding and setting of 
 tools, quick and secure chucking, and a knowledge of the most suitable 
 speeds at which to drive work in different materials and of different dimen- 
 sions. A good iron turner commands as high wages as a fitter, but boys 
 at low wage now do a vast quantity of the repetition work of the shops. 
 
 Iron Turning. — Iron turning is a most important branch of engineering 
 work, since all circular bearing parts and revolving and close fitting 
 work have to be turned in the lathe. Most iron turning as now done 
 is effected in slide rest lathes, and the number of men skUled in hand- 
 turning is diminishing proportionately. Special turning is done in 
 special lathes, from the Ught 4 or 6 in. screw cutting lathes, to the 
 large break lathes employed in wheel turning. 
 
106 DICTIONARY OF TERM^ USED IN 
 
 Iron Wire. — See Wire. 
 
 laoclironous. — Literally, equal timed. Signifies the passing of apendnlran 
 governor through arcs of different lengths in equal time. The nearer 
 the governor of a steam engine or other motor approaches to isoohronism 
 the greater its value as a regulator of motion. 
 
 Isosceles Triangle. — A triangle having two sides only of equal length. 
 This is the form of triangle formed by the bracing of lattice girders. 
 
 Isothermal Curve. — The curve which represents the expansion of a per- 
 fect gas in a closed vessel. A perfect gas, it may be noted, is one whose 
 pressure at a constant temperature varies inversely as the space it occu- 
 pies. An isothermal curve follows the law of Boyle and Marriott (q.v.). 
 
 Isothermal Lines. — Lines of equal temperature, as opposed to adiabatio 
 curves (q.v.) ; produced on diagrams of work under varying pressure 
 with constant temperature. 
 
 J. 
 
 J. — See Joule. 
 
 Jack. — A piece of mechanism employed for lifting heavy loads through 
 short distances with a minimum of expenditure of manual power. See 
 Screw Jack, Hydraulic Jack, Bottle Jack, Tripod Jack. 
 
 Jacket. — See Steam Jacket. 
 
 Jacket Casing. — The casing which encloses the steam or water used in 
 jacketiug ; or more simply the Jacket. See Steam Jacket. 
 
 Jacketing. — The fitting of a steam jacket (q.v.) to a cylinder for tho 
 greater economy of heat. Li some large cylinders the covers also are 
 jacketed by being made hollow, to receive steam, and hollow pistons are 
 made with the same object. 
 
 Jacking Up. — (1) The elevation of masses of machinery and heavy struc- 
 tures by means of jacks. Blocking pieces and wedges are inserted as 
 the work advances. (2) The planing off the rough outsides of boards 
 with the jack plane is also called jacking up. 
 
 Jack in the Box. — The tool box in jim crow machines (q.v.). 
 
 Jack Plane. — The first plane used by wood-workers for roughing down 
 timber, the cutting iron being more curved than in the other fmishing 
 planes. It takes coarse and narrow shavings ofE. 
 
 Jag. — A roughed-up, or barbed, or projecting portion of metal produced 
 by nicking underneath, or in front of it, with a cold chisel, or with a 
 smith's cMsel, or by casting. 
 
 Jag Bolt. — A tail bolt whose shank or tail is roughed up by jagging. 
 
 Jaggers. — Eough projections or studs of a pyramidal or conicalform, cast 
 on loam plates for foundry use. They are simply stamped into the 
 mould of the plate, their efficiency depending partly upon their 
 roughness. Sometimes called prods. 
 
 Jagging. — When a wrought-iron bar, a shaft, or an eye, is ca.st into a 
 piece of work, the portion which is embraced by the casting is 
 serrated or notched in order to prevent it from being pulled out sub- 
 sequently. This serration is termed jagging. 
 
 Jammer. — A spring chaplet. 
 
 Jamming. — The sticking of cocks and safety valves in their seatings, due 
 to a wedging action induced by various circumstances. Safety valves 
 jam by reason of corrosion or distortion ; cocks through too slight an 
 angle being given to their plugs, and also to corrosion. 
 
MECHANICAL ENGINEERING. 197 
 
 Jam Nut. — A look nut (q.v.). 
 
 Jaw. — Aa opposing piece in a macliine or tool, used for clamping, or 
 crushing, or cutting. Vice jaws, the jaws of shearing machines, of 
 pliers and pincers, of tongs, and of spanners, are cases in point. 
 
 Jaw Chuck. — A lathe chuck, consisting of a face plate furnished with 
 movable clips or jaws, the jaws being moved to or from the centre with 
 screws, and held fast with clamping screws. Called also dog chucks, 
 and the jaws, dogs. 
 
 Jaw Nut. — A look nut (q.v.). 
 
 Jemmy. — A short crowbar (q.v.). 
 
 Jenny. — See Block Carriage. 
 
 Jet. — The current of water which issues from an adjutage (q.v.). 
 
 Jet Condenser. — The older form of condenser in which the steam is 
 condensed in a closed box, by means of a spray of injection water 
 scattered from a jet. 
 
 Jib. — The strut or thrust member of the framing of a crane. It is 
 always in compression. It is either made in wood or in wrought iron ; 
 either rolled joist iron, or braced angle iron framework, or a combination 
 of both being employed. 
 
 Jib Crane. — A crane provided with a jib or compression beam, as dis- 
 tinguished from an overhead crane, or shear legs, or a crab, or a 
 winch. 
 
 Jib Legs. — Timber legs pivoted to the jib pin of an accident crane, and 
 reaching to the ground ; they afford a firm and broad base to the 
 jib when lifting, and so prevent the crane from overturning. When 
 not in use they are shipped over the side frames. 
 
 Jigger Saw, or Jig Saw. — A thin narrow-bladed saw to which a reciprocat- 
 ing motion in the vertical direction is imparted by a crank and levers, 
 used for the same purposes as band saws. In workshops the latter have 
 mostly superseded the former, and small jig saws are now almost 
 entirely relegated to the use of the fret worker. 
 
 Jil Barrow. — ^A barrow without sides, being simply aflat carrying surface 
 provided with handles and a wheel, or wheels. Used for carrying 
 ca,stings from the foundry, and about the shops. 
 
 Jim Crow. — A portable rail straightener or rail bender (q.v.). 
 
 Jim Crow Macliiues. — Metal planing machines, driven by a screw and by 
 pulleys and wheels of equal sizes, and in which, the table having no 
 quick return, the tool box is revolved round by cords, to out in both 
 directions. Jim crow alludes to the rapid whisking round of the tool 
 box at the termination of the stroke. Sometimes called jack-in-the- 
 box machines. 
 
 Jimmy. — A short crowbar (q.v.). 
 
 Jinny. — The travelling or block carriage of an overhead traveller from 
 which the bight of the chain, and the snatch block depend. 
 
 Joggle. — A projecting pin on a casting for the purpose of affording 
 steadiness to it when set in place. Used chiefly in castings which are 
 bolted upon timber, the timber having a shallow mortice cut to receive 
 the joggle. The latter, as a rule, is of a rectangular form. A raised 
 ridge which receives the thrust of a plummer block or other beariug is 
 also called a joggle. 
 
 John Bull. — ^A strong bar of wrought iron having a flat square foot at 
 one end, and a short movable bar sliding at right angles along the 
 body and carrying a set screw for adjustment. It is used to take the 
 tteuat of a ratchet b^r^oe during hand drilling, the foot being bolted to 
 
1 98 DICTIONARY OF TERMS USED IN 
 
 the work or tc a tench, and the movable bar receiving the thrust oi 
 the end of the trace. 
 
 Joints. — Very many kinds of .joints are made in engineers' work, for 
 wood, and metal, and moulds, including glued, dovetailed, red lead, 
 rust, planed, riveted, welded, sand joints, &c., described in their 
 places. 
 
 Joint Board. — A tiun-over board, used not so much for the purpose 
 of keeping a pattern true during the process of ramming up, as to save 
 the moulder's time in making sand joints, though the te'" i is applied 
 loosely to turn-over boards and bottom boards. The pavtem is laid 
 upon the board, and the face oi the board without the pattern is made 
 to the contour of the intended joint, and the sand in the flask being 
 rammed thereon receives the joint contour. 
 
 Jointing.. — (I) In moulders' work, jointing- signifies the dividing off of the 
 various portions of which the mould is composed. This is commonly done 
 by the intervention of a thin layer of sand between the mould parts, of a 
 different quality from that used in the body of the mould itself. Joints 
 of drawbacks are sometimes made with sheets of interposed brown 
 paper. (2) The jointing cl iron pipes is done with red lead and boiled 
 oO when flange faces are brought together ; jointing of sockets is effected 
 with melted lead, or with gasket, or with india-rubber rings. Hydraulic 
 joints are made with sal-ammoniac and iron borings, piston joints for 
 hydraulic work are made with leather pressed into the form of a cup, 
 piston joints for steam with a metallic expanding ring. 
 
 Joint Pin. — A pin connecting the two parts of a kiuokle joint (q.v.). It 
 is prevented from moving out of place by a split pin (q.v.). 
 
 Joint Blng. — A ring employed for the making of water-tight pipe joints. 
 It is usually a ring of lead whose faces are slightly hoUowed out, 
 so that whefi the ring is squeezed between opposing flange faces 
 by screw bolts it is sUghtly flattened and fills up all tmeveimess on the 
 surface. 
 
 Joint 'Washer. — See India-rubber "Washer. 
 
 Joists. — EoUed wrought-iron girders of an I section, employed for a 
 variety of purposes in constructive engineering. 
 
 Joule. — The unit of heat, so called after the experimentalist who demon- 
 strated the relations between heat and work. A joule is equal to 772 
 foot pounds and is designated by a J in mathematical calculations. 
 
 Journals. — The turned portions of shafts, or those parts which revolve in 
 the bearings. 
 
 Journal Box. — Sometimes applied to a bearing or an axle box. 
 
 Joy's Gear. — A form of valve gear in which no eccentrics are employed, 
 the valve rod being worked directly through a coupling rod or link 
 from the connecting rod. The necessary travel is imparted by causing 
 the up and down or oval movement of the coupling linlj to move a 
 die block to which one end of the valve rod is attached, that end sfiding 
 up and down in a slot link moving in a fixed centre, and placed at an 
 angle with the rod. The reversal of the engine is effected by alter- 
 ing the direction of the angle of the slot link about its fixed centre. 
 
 Jumper, or Monkey. — (1) A smith's hammer, cylindrical and soHd in 
 form, suspended from a chain and swung therefrom, battering-ram 
 fashion. It is used for dealing blows against the ends of rods laid 
 horizontally for the purpose of jumping them up or upsetting them. 
 (2) The sparks or scintillations which fly off from molten iron in the 
 ladle are also termed jumpers. 
 
MECHANICAL ENGINEERING. 199 
 
 Jumping In. — The forcing or springing in of the paoMng, or spring 
 ring of an engine piston into its cyEnder. 
 
 Jumping TJp. — The same as upsetting (q.v.), in allusion to the repeated 
 knocking of the end of a bar of iron down upon the anvil in order to 
 tMoken or increase the diameter of the heated portion. 
 
 Jump Joint. — A. telt joint made by bringing the ends together end to end, 
 and then lacing ; it is therefore a butt joint. 
 
 Junction Valve. — An ordinary two-way valve which unites two pieces of 
 piping. 
 
 Junk Bing. — A ring of cast or wrought iron screwed down on one face 
 of the piston of a steam engine or pump, and by means of wMch the 
 gasket or rope packing which surrounds tlie piston is pressed against 
 the cylinder bora rendering the contact water or steam tight. 
 
 K. 
 
 Eauri Pine, often spelt Kowrie, Cowrie, Kaurie, Cowdie. (Dammara Aus- 
 tralis). — ^A New Zealand wood of the natural order Comfera. It is an 
 excellent wood for pattern work, being large, straight grained, silky 
 and smootb in fibre, and standing well. A cubic foot weighs 32 lbs. 
 Sp. gr. -512. 
 
 Keelsons. — A name given to the wrought-iron saddles or standards upon 
 which marine boilers rest. 
 
 Keeper. — The lower movable step or bearing in an axle box. There is no 
 bearing of the axle on the keeper excepting when the engine or truck 
 is lifted up for repairs. Hence it is hollowed out internally. 
 
 Kentledge. — The loose balance weights supplied with a balance crane. 
 
 Kerf. — The width of the cut produced by the teeth of a saw, the cut itself 
 being termed a saw kerf. The width of the kerf depends on the 
 amount of set (q.v.) given to the saw teeth. 
 
 Key. — (1) The wedge-shaped strip of iron or steel used for preventing 
 wheels from slipping round upon their axles. A flat is filed upon the 
 shaft and a groove cut through the eye of the wheel, and these are brought 
 opposite to each other so that the key prevents the one from slipping over 
 the other. There is no wedging action sideways but only radially. A 
 sunk key is one which is sunk into a recess in the shaft instead of simply 
 lying upon a flat surface, and is used where great tension is present. A 
 key wMch allows^ of a wheel sliding along it for the purpose of being 
 thrown in and out of gear is called a feather. (2) Keys are the wooden 
 wedges which are driven between a rail and its chair. The timber of 
 which keys are made is compressed before being cut, for the same reason 
 that trenails are compressed so that they may swell by the subsequent 
 absorption of moisture from the atmosphere, and so hold tightly. (3) A 
 square spanner or wrench used for tightening the screws of lathe chucks 
 and other parts. (4) A two-pointed prong by which the joints of draw- 
 ing compasses are tightened. 
 
 Key Bed See Key Way. 
 
 Key Boss. — A small swell or projection cast on the outside of the boss of 
 a wheel or pulley, opposite and outside the key way, in order to main- 
 tain the same thickness of metal around that as around the central hole. 
 Without this addition the cutting of the ksy wav would become a 
 Bouice of weakaesa. 
 
200 DICTIONARY OF TERMS USED IN 
 
 Key Omck. — A Jaw chuck whose screws are actuated by a key or actuate 
 spanner turning the square heads of the screws. 
 
 Key Hole Saw. — See Pad Saw. 
 
 Key Screw. — A spanner or screw wrench. 
 
 Key Seating. — A key way (q-T.). 
 
 Key Stone. — The centre vousaoir or crown of an arch. 
 
 Key Way, or Key Bed, or Key Seating. — A shallow recess out through the 
 eye or bore of a wheel for the reception of the key (q.v.). 
 
 Key Way Tool. — A slotting machine tool used for the vertical cutting of 
 key ways, the wheel lying horizontally upon the table of the machine. 
 The tool is cranked so that the cutting edge stands out in front of the 
 shank, and the width of the cutting edge is the same as that of the 
 key way to be cut. 
 
 Key Wrench. — A screw wrench or spanner (q.v.). 
 
 Killing. — The addition of zinc to spirits of salts or hydrochloric acid 
 (q.v.) to form a chloride of zinc, as a flux to remove the oxide from sur- 
 faces which have to be soldered. 
 
 Kiln. — A furnace in which the ores of iron are calcined in order to drive 
 off the carbonic acid previous to smelting. 
 
 Kilo. — Abbreviation for kilogramme. 
 
 Kilogramme. — A standard French measure of weight containing a thou- 
 sand grammes (q.v.). It is equivalent to 2-2046 English pounds. 
 
 Kilogrammetre. — A French unit of work, being equivalent to a kilo- 
 gramme lifted one metre high. 
 
 Kilolitre. — A French measure of capacity, containing a thouaand litres 
 (q.v.), and being equivalent to 220-09 English gallons. 
 
 Kilometre. — One thousand French metres (q.v.), corresponding with 
 39,370-79 English inches, or 3280-9 feet. 
 
 Kinematics. — The study of the laws which regulate the actions of bodies 
 in motion. 
 
 Kinetic Energy.^See Energy. 
 
 King Post. — The central upright in a roof truss against which the rafters 
 abut, and which supports the tie beam. 
 
 King Bod. — An iron tension rod which in an iron roof truss takes the 
 place of the king post in a wooden roof truss, depending from the ridge 
 and uniting with the tie rod. 
 
 Kingstone Valve. — A wing valve used on board ship for condenser water 
 suction, and for boiler blow-off. It opens towards the sea, but is self- 
 closing in case of fracture of the spindle. 
 
 King Truss. — A truss formed with a king post. 
 
 Kink. — A sharp bend or angle produced in a piece of metal by a blow or 
 a strain. Also the getting out of place of chain links, so that they 
 form a knot or bunch. 
 
 Kish. — The name given to the black scales of graphite, which separate 
 and float on the surface of a slowly cooling mass of molten iron. The 
 whole of the scum is also called kish. 
 
 Kite Connecting Rod. — See Bow Connecting Rod. 
 
 Knee. — An elbow pipe. The difference between a knee and a bend is that 
 in a knee the branches meet in an angle, in a bend they merge into 
 each other with a curve. (1) A curved or angular piece of timber or iron 
 connecting two portions of work together. (2) Atoggle joint (q.v.). 
 
 Knife Edges. — The bearing edges of weighbridge levers. They are made 
 of hardened steel, and the edges are formed by the meeting of two 
 faces sloping towards one another at an angle of about 90°. 
 
MECHANICAL ENGINEERING. 201 
 
 Knife File. — A file of triangular or tHu wedge-shaped section, similar to 
 that of a knife. 
 
 Knife Key. — A key with prongs for tightening the joints of compasses, 
 but containing, in addition, a rigid knife blade at the opposite end, and 
 a file placed intermediately. 
 
 Knocker Out. — A term often applied to the horns (q.v.) of a planing 
 machine, against which the tappets strike. 
 
 Knocking. — The noise caused in a pump on the reversal of the motion for 
 suction and delivery when no air vessel, or an air vessel of insufficient 
 area, is provided. 
 
 Knotting. — A compound used for filling or covering knots to prevent 
 absorption of oil paint. It is composed either of shellac and methylated 
 spirit, or naphtha, or of red lead and glue. 
 
 Knuckle Joint. — One in which an eye at the end of a rod is embraced by the 
 forked end of a second rod, the two being connected with a joint pin (q. v.). 
 
 Kowrie Pine. — See Kauri Pine. 
 
 Kyanizing. — The preservation of timber by impregnation vrith a solution 
 of corrosive sublimate or chloride of mercury, Hg CI2. The propor- 
 tions are one pound of sublimate to ten gallons of water for maximum 
 strength, or one pound to fifteen gallons as a minimum. About twenty- 
 four hours per inch of thickness are req.uired for saturation. 
 
 L. 
 
 Labourers. — Unskilled labour is largely employed in most of the depart- 
 ments of engineering. In the foundry the labourers turn out the cast- 
 ings, water and mix the sand, haul about the flasks or moulding boxes, 
 attend to the cranes, do the box filling, &c. In the tiiming, fitting, 
 and erecting shops, they wait on the mechanics, attend to the cranes 
 and haulage generally. In the boiler shops they hold up the dollys, 
 and lift and hold up the plates at the machines. In the smiths' shop 
 the hammer-man or striker is the sole labourer. In the yard the work 
 connected with the package and haulage of finished work is done by 
 them. 
 
 lac. — See Shellac. 
 
 Lace. — A strip or thong of white leather used for uniting the free ends of 
 leather belting. See Leather. 
 
 Lacing.— The union by means of laces of the ends of leather belting used in 
 driving machines. The distance around the pulleys being taken, the 
 belt is made to overlap in a loop somewhat smaller than that given by 
 the actual measurement in order to allow for after stretching, and 
 the overlapping ends are pierced with holes through which the lace is 
 threaded. Belt screws have, however, largely superseded laces for this 
 purpose. 
 
 Lacquer. — A varnish applied to metal work to protect it from the tarnish- 
 ing influences of the atmosphere. Its basis is shellac (q.v.), which is 
 dissolved in spirits of wine ; colouring matters are added. The article 
 to be lacquered is warmed and the solution applied with a camel-hair 
 brush. A recipe for a brass lacquer is as follows : shellac, 8 ozs. ; 
 sandarac, 2 ozs. ; aimatto, 2 ozs. ; dragon's-blood resin, \ oz. ; spirits 
 of wine, 1 gallon. 
 
 ladder. — A series of ro«d buckets (q.v.) which are corned up find down 
 
202 DICTIONARY OF TERMS USED IN 
 
 in an oblique direotion, for emptying and refilling in dredging 
 operations. 
 
 Ladle. — An open iron vessel lined with some heat-resisting substance, as 
 fire-clay. Used in foundries for pouring the molten metal into the 
 moulds. Ladles vary in size from those holding half-a-hundredweight 
 to those carrying twelve tons or more. The smaller sizes are hand 
 ladles, the larger ones are moved by the crane. The difference between 
 a ladle and a crucible is that in the latter the metal is not only melted 
 but poured therefrom, while the former is only a temporary receptacle 
 for metal which has been melted elsewhere. 
 
 Lagging. — This has several significations. When boilers and engine cyliu- 
 ders are cleaded (See Cleadiag) with wood strips, the strips are called 
 lagging or lagging strips. The strips of oak which extend from end 
 to end, and form the peripheries of large winding drums, are termed 
 lagging. The similar pieces with which the patterns of engine cylin- 
 ders and pipes are built up, are so designated. The process of fitting 
 of such strips is also termed lagging, or lagging-up. 
 
 Lake and Gamboge. — Used in combination to indicate copper on sectional 
 drawings. 
 
 Laminated. — ^Denotes generally the condition of thin sheets, fibres, plates, 
 strips. Frequently applied to the character of the fibres of iron, and 
 of metallic bodies, and structures. 
 
 Laminated Plates. — Plates of wrought iron are said to be laminated when 
 there is a lack of homogeneity and perfect union of the various layers 
 of which they are composed. Laminated plates are apt to blister when 
 used for steam boilers. The presence of imperfect union can be tested 
 by tapping with a hammer. 
 
 Laminated Spring. — A cirrved spring composed of thin plates superimposed 
 one over the other, as distiaguished from helical and coiled springs. 
 
 Lamp Bend. — A wrought-iron bend pipe, one of whose arms departs from 
 a curve, being straight for some distance. Its form is such that the 
 pipes which it connects stand at an angle greater than a right angle. 
 
 Lancashire Boiler. — A horizontal, cylindrical, internally fired boiler, 
 having two flues. 
 
 Lancashire Files. — The smaller classes of files are made in Lancashire, 
 but most of the ordinary files come from Sheffield. 
 
 Laud Boiler. — Used in contradistinction to marine boiler, but more com- 
 monly understood of boilers bmlt into brickwork, as of the Cornish and 
 Lancashire type, rather than of locomotives and portables, which are a 
 type in themselves. 
 
 Land Engines. — A term frequently employed to distinguish ordinary 
 stationary engines from those of marine and locomotive types. It 
 designates no type of engine in particular, whether horizontal, vertical, 
 beam, or otherwise, or high or low pressure ; but the term, as originally 
 employed, had more special reference to the various forms of condensing, 
 beam, and pumping engines. 
 
 Lantern Brass. — A hollow brass sometimes introduced into the stuffing 
 boxes of engines, and supplied with steam, so that in the event of leakage 
 occurring it shall be that of steam instead of air. 
 
 Lantern Frame Pattern. — A type of inverted cylinder engine in which the 
 cyhnder standard is columnar or cylindrical in. outline, hollow within 
 and pierced at the sides with openings reaching nearly to the guide 
 facings. The crosshead works in the bore of the column, and the crank 
 bearings are cast in the base. It is a rigid and cheap form of standard- 
 
MECHANICAL ENGINEERING. 203 
 
 Lantern Wheel. — An old-fasMoned type of cog-wheel used in mills. It 
 was formed by round pins or staves, arranged equidistantly between two 
 discs of hard wood, which discs were kept at a distance apart, exceeding 
 by a small amount the width of the teeth of another, or mortice wheel, 
 which engaged with the staves. The staves are driven fast into holes 
 bored in the disc. Sometimes called a trundle or trundle wheel. 
 
 Lap. — (1) A body of soft metal, such as lead, tin, or brass, which forms the 
 matrix or support for the emery powder or pumice powder used in 
 grinding surfaces of hardened steel, chiUed iron, or other substances too 
 hard to be attacked with ordinary cutting tools. It is usual to make the 
 lap of the same outline as the work to be ground. For the commonest 
 work, laps made of lead are employed, for the better class tin is used, 
 while the finest laps are made of soft brass. (2) The amount by which 
 a elide valve covers the steam port at the termination of the piston 
 stroke, consequently the lap of a valve indicates the amount of cut- 
 off of the steam in the cylinder. (See Exhaust Lap and Outside Lap.) 
 (3) The extent to which the joints of riveted plates pass one over the other. 
 The amount of lap should not be more than one and a half times the 
 diameter of the rivet, measured from the centres of rivets to the edge of 
 the plate. (4) A single turn of a rope or chain around a barrel. 
 
 Lap Circle. — The circle on a lap diagram (q.v.), whose radius represents 
 the lap (q.v.) of the valve. If the laps are unequal there wiO. be two 
 lap circles. 
 
 Lap Joint. — ^A joint produced by the overlapping of contiguous faces of 
 metal. 
 
 Lapped Valve. — A shde valve provided with lap (q.v.). AIL valves as now 
 made have lap, but in the early days of the steam engine there was no 
 expansive working and consequently no lap. Hence the term. 
 
 Lapping. — The polishing and truing up of spindles, bearings, and circular 
 hearing parts generally, with laps of lead or other material. 
 
 Lap Eiveting. — When the edges of two plates are placed one over the 
 other and riveted, this is termed lap riveting, to distinguish it from butt 
 riveting (q.v.). 
 
 Lap Weld. — A joint which is welded by the overlapping of plates, the 
 overlapping edges being thinned down for the purpose of maintaining 
 an even thickness. 
 
 Lap-welded Tube. — ^Malleable iron tubes for steam and water pipes are 
 lap welded, that is, the plates overlap one another at their joints, instead 
 of merely abutting at the weld. 
 
 Lard. — ^Used as a lubricant of good body, either alone or in combination 
 with a hghter oU. 
 
 Last Coat. — The smooth or finishing coat of loam applied to a loam 
 pattern, mould, or core. See Rough Coat. 
 
 Latent Heat. — The quantity of heat which can he communicated from 
 one body to another without changing its temperature ; or that amount 
 of heat which does not raise the temperature of a body but effects its 
 fusion simply. Hence called the latent heat of fusion. 
 
 Lateral Strain. — A strain which bears against the side of a structure, 
 being essentially a transverse strain. 
 
 Lateral Traverse. — The amount of end play (q.v.) allowed to the traiUng 
 axles (q.v.) of locomotives in order to facilitate their running round 
 sharp curves. It may average 1 J". 
 
 Lath. — A strip of wood used for the precise marking off of distances, 
 centres, &o., directly from, or upon work, in preference to rule measure- 
 
204 DICTIONARY OF TERMS USED IN 
 
 ment. Measiu-ement is not taken from the ends, but from one line to 
 another scribed across the face of the strip. Thus engineers take laths 
 of Talve faces and cylinder ports for comparison, and as a permanent 
 record of dimensions. 
 
 Lathe. — A machine employed for the production of circular work. The 
 work is either suspended between the centres of fast and movable 
 heads, or attached to the fast head or headstock alone, through the 
 intervention of chucks of various kinds. The cutting tools are either 
 actuated by hand, or are held in a slide rest, which is either moved by 
 hand, or is automatic. The heads and the rest are supported on a bed 
 or bearers. Lathes are actuated by the foot alone, or by power, and 
 they are constructed for hand turning, or are self-acting. The size of a 
 lathe is given in the height of the centre above the face of the bed, and 
 in the length of the bed. Almost all mechanical operations can be per- 
 formed in the lathe : turning, boring, drilling, shaping, screw cutting, 
 dividing, besides those outside the range of engineer's work and which 
 come under the head of ornamental turning. 
 
 Lathe Bearers. — The sides or cheeks of a lathe bed. 
 
 Lathe Bed. — The longitudinal support for the heads and the rest of a 
 lathe. Lathe beds are made in wood or metal, and usually consist of 
 two hearers, cheeks, or shears. When made in wood they are of 
 rectangular section, but when in iron are of I or girder section, united 
 into one casting by cross pieces or ribs. The top faces and edges of the 
 cheeks are planed, and in lathes fitted with self-acting slide rests, the 
 outer edges are of a Vee'd section, so forming a guide for the saddle of 
 the rest. Occasionally small lathe beds are formed of a single shear of 
 a triangular bar section. Beds rest at their ends upon standards. 
 
 Lathe Can. — A soap suds can (q.v.). 
 
 Lathe Ceutre Grinder, — An emery-wheel driven from overhead, and used 
 for grinding the hardened conical points of lathe centres in place. 
 
 lathe Cheeks. — The sides of a lathe bed. 
 
 Lathe Dog. — A carrier (q.v.). 
 
 Lathe Heads. — The headstock (q.v.) and poppet (q.v.) of a lathe. 
 
 Lathe Planer, — A piece of mechamsm sometimes attached to a lathe for 
 the surfacing of metal by rectilinear cutting. There are several forms 
 of lathe planers, mostly cumbersome, not very accurate, adopted almost 
 exclusively by amateurs, and mostly unnecessary, since plain surfacing 
 can be done on the ordinary face chucks. 
 
 Lathe Shears. — The sides of a lathe bed. 
 
 Lathe Standards. — Stout A frames of oast iron provided with ribs, 
 flanges, and feet, to form the supports of lathe beds. They rest on the 
 ground and are bolted tothe under side of the bed at the ends. In the 
 larger lathes there may be one or more intermediate standards besides. 
 
 Lathe Tools. — The tools used especially in connection with lathe work, 
 embracing not only those special to the lathe, but many others besides. 
 For wood work they embrace the gouge, chisel, round nose, side tools, 
 diamond points, and parting tools. For metal work, roughing down, 
 and finishing toola of various shapes, and ground to different angles 
 for the turning of cast and wrought iron, steel, and brass. Besides these 
 there are various gauges, calipers, punches, drUls, reamers, &c. 
 
 Lathe Work. — Has reference to the work commonly accomplished in the 
 lathe, which embra,ces practically almost all branches of mechanical 
 operations. See Lathe. 
 
 Lattens.— See Trebles, 
 
MBCHANtCAL ENGINEERmO. 205 
 
 lattice. — Diagonal Ibracing, forming struts and ties. 
 
 lattice Bars. — The bars forming t£e strata and ties of a lattice or open 
 frame girder. 
 
 Lattice Girders Girders of -wrouglit-iron made by uniting top Jand 
 
 bottom angle irons with, lattice work or diagonal bracing, the other 
 ilanges of the angle irons being attached by riveting to top and bottom 
 plates. 
 
 Lattice Jib. — A crane jib built up with wrought-iron lattice bars 
 (q.T.). 
 
 Lattice Web. — A girder web made by latticing, as opposed to a plated 
 web, or a web built up by a single system of triangulation, as in a 
 Warren girder. 
 
 Latticing. — The combination of two or more systems of triangulation 
 in an open webbed girder. The number of apical points being propor- 
 tionately increased, the weight is distributed over a greater number of 
 sections, and the stress in each diagonal reduced in proportion to the 
 increase in the number of triangulations. 
 
 Laws of Motion. — The laws of motion as formulated by Newton are three : 
 — Pirst law, every body continues in its state of rest or of uniform 
 motion in a straight Ime, except in so far as it may be compelled by 
 impressed forces to change that state ; second law, change of motion is 
 proportional to the impressed force, and tal e 1 place in the direction of 
 the straight line in which the force is impressed ; third law, to every 
 action there is always an equal and contrary reaction, or the mutual 
 actions of any two bodies are always equal and oppositely directed. 
 
 Laying-down Board. — A bottom board (q.v.). 
 
 Laying Out. — The setting out or marking out of work to full size. 
 Usually applied more especially to the development of boiler-makers' 
 and platers' work. 
 
 Lay Shaft. — A small secondary shaft, which is placed beside, or at the end 
 of a horizontal engine, for the purpose of actuating the valves. It is 
 driven from the crank shaft by means of bevel or spur-wheels. 
 
 Lead. — Symb. Pb. ; comb, weight, 206-4 ; Sp. gr., 11-3. A bluish grey 
 metal used in engineering work as an ingredient in brass and gun 
 metal, in solders for making the joints of cast-iron pipes, and in the 
 form of tubing for a variety of purposes. 
 
 Lead Glance. — Galena (q.v.). 
 
 Lead Hammer. — ^A hammer made of lead and occasionally used for the 
 same purpose as a copper hammer (q.v.). 
 
 Lead Lap. — See Lap. 
 
 Lead Letters. — See Pattern Letters. 
 
 Leading Axle. — The front axle of a locomotive. 
 
 Leading Edge. — That edge of the blade of a screw propeller which cuts 
 the water, as distinguished from the following edge (q.v.). 
 
 Leading Hand. — A workman who, by reason of his superior skUl, occu- 
 pies a leading position in his shop, to whom the best work is given, and 
 who is looked up to by the remaining hands. His wages average a few 
 shillings weekly over those of the other men. 
 
 Leading Screw, or Guide Screw, — The screw which runs longitudinally in 
 front of the bed of a self-acting lathe, and whose pitch is the first 
 factor in the cutting of screws ; occasionally called a main screw. 
 
 Leading Springs. — The springs which carry the axle boxes of the leading 
 wheels of locomotives and rolling stock, and which sustain and 
 minimise the shocks due to concussion. They usually consist of about 
 
2o6 DICTIONARY OF TERMS USED IN 
 
 sixteen steel plates of about 15 x f in. section, the larg'est being 
 thicker, oi say J in. 
 
 leading Wheels. — The front wheels of a locomotive. 
 
 Lead Joint. — Lead joints are used in pipe connections. Sometimes a 
 sheet oi lead is screwed up between flanges, but the employment of the 
 metal is more common in socket and spigot joints. The lead is poured 
 between the socket and spigot and hammered or stemmed down ; that 
 is, driven closely home with a drift and hammer. 
 
 Lead Line. — The left-hand vertical line in an indicator diagram which 
 represents the amount of opening to lead. 
 
 Lead of a Valve, — The amount by which a slide valve is opened at the 
 termination of the piston stroke for the admission of steam for cushion- 
 ing. It varies from ^ in. in slow running, to J in. in quick running 
 engines. 
 
 Lead Faints. — Ordinary paints, so called because their basis is white 
 lead. 
 
 Leaf Wood. — A term used to designate all timber not included in the pine 
 or coniferous family. 
 
 Leakage. — The loss of teed water from steam boilers. It is due chiefly to 
 the expansion and contraction of the plates caused by alternate and 
 sudden heating and cooling, which produces opening of the seams 
 and rivets. In some cases leakage is due to joints being originally 
 difficult to make, or to bad workmanship. 
 
 Leaning Threads. — The threads of screws where one side leans over more, 
 or makes a greater angle with the longitudinal axis than the side 
 opposite. Such screws are seldom used except in special cases where 
 the pressure is always in one direction. 
 
 Lean-to Eoof . — A roof which has only one slope. 
 
 Leather. — A material widely used for belts (q.v.) for driviag machinery. 
 It is used single or double, single belting ranging from 3-16 in. to 5-16 
 in. in thickness, and double fcom|-in. to fin. Its ultimate strength 
 (q.v.) is from 3,000 lbs. to 5,000 lbs. per square inch of section. The 
 leather is spliced, cemented, or united by sewing to make up the 
 necessary length, and is finally laced (see Lace) or screwed in the work- 
 shop to unite the free ends. 
 
 Leather Belting. — See Leather. 
 
 Leather Lace. — See Lace. 
 
 Leathers. — The packiugs, and certain portions of the valves of pumps. 
 See Cup Leather, Hat Leather, Flap Valve, U Leather, &c. 
 
 Leather Hollows. — Strips of leather largely used by pattern-makers to 
 form the hollows in wood patterns. The reason why they are preferred 
 to hoUows made of wood is that the time occupied in laying them 
 around curved portions of work is much less than that occupied in 
 cutting wooden hollows. They are cemented in with a special compo- 
 sition supplied with the hollows. 
 
 Leather Hose. — Hose pipe made of leather, and either cemented or sewn 
 down the joiut. It is the best and most durable. See Canvas Hose, 
 Eubber Hose. 
 
 Left-hand Engine. — An engiue which stands to the left of its fly wheel 
 when viewed from the end of the cylinder. 
 
 Left-hand Screw. — A screw which turns from left to right, or in the re- 
 verse direction to a common wood screw. 
 
 Left-hand Tools. — Side tools ground to an angle on the right hand sidei 
 and which, therefore, out from left to right. 
 
MECHANICAL ENGINEERING. 207 
 
 teft-hand Twist Drill. — A twist drill in wMcli tlie twist runs from left to 
 right up the shank. 
 
 Lengthening Bar. — An appendage to compasses used for drawing pur- 
 poses. It is a brass leg or shank which is made to fit into the socket 
 of the compass leg at the one end, and over the stem of the ink or pencil 
 point at the other ; its purpose being the adaptation of the compass to 
 the measurement of long distances, or the striking of arcs of large 
 radius. 
 
 Lengthening Bearers Castings or wooden cheeks made to attach to the 
 
 poppet end of a lathe bed to extend it for a temporary purpose, as the 
 turning of a long rod or shaft. The poppet being slid over the lengthen- 
 ing hearers the longitudinal capacity of the lathe is increased in propor- 
 tion to the length of the bearers. 
 
 Let In. — A shop term, which signifies the sinking in of one portion of 
 wood or metal into another. Thus, rapping plates are let in to patterns, 
 brass rings are let in to sluice cock faces, &c. 
 
 Letters. — See Pattern Letters. 
 
 Letting Down. — The lowering of the temperature of hardened works 
 down to the colour which indicates the temperature at which they are 
 to be quenched for tempering. 
 
 Level. — (1) Truly horizontal. In a horizontal plane. (2) A spirit-level 
 (q.v.). 
 
 Levelling. — The bringing of wrought-iron and steel plates superficially 
 true preparatory to working and cutting them out. They are levelled 
 by the striking of blows delivered from a hammer or wooden maUet. 
 See Levelling Block. 
 
 Levelling Block. — A large flat cast-iron plate stiflrened on its under side 
 with flanges or ribs upon which plates of sheet iron and steel are laid 
 while being levelled. It is used by boiler -makers and platers. 
 
 Lever. — A rigid bar turning upon an axis or fidcrum. The arms of a 
 lever are those portions of the bar standing away from and pivoting 
 round the fulcrum. The arms are straight or bent ; in the former 
 case it is said to be a straight, in the latter a bent lever. The principle 
 of the lever is that the product of the power multiplied into the length 
 of its arm is equal to the product of the weight multiplied into the 
 length of its arm. A lever of the first kind has the fulcrum between 
 the power and the weight. In a lever of the second kind the power 
 and the weight are on one side of the fulcrum, the weight occupying 
 the intermediate position. In a lever of the third kind the power and 
 weight are on one side of the fulcrum, but the power occupies the inter- 
 mediate position. 
 
 Lever Box, or Lever Bracket. — A hollow casting which carries the various 
 levers connected to the motions of a crane for slewing, lifting, 
 travelling, &c. 
 
 Lever Bracket. — A lever box (q.v.). 
 
 Lever Chuck. — A concentric chuck actuated by a lever instead of screws. 
 
 Lever Drill. — A form of drilling apparatus similar to a ratchet brace 
 (q.v.) but without the ratchet, the lever in this case passing through a 
 hole in the piece which carries the drill socket. 
 
 Lever Jack. — A form of jack comprising a simple lever for lifting, and a 
 standard for support. 
 
 Lever Press. — A form of press used for the compression of substances for 
 export and other purposes. It is acted upon by a long lever. 
 
 Lever Pumps. — The air and circulating pumps of marine engines which 
 
2o8 DICTIONARY OP TERMS USED IN 
 
 are commonly -worked by levers driven from the cross heads of the 
 piston rods. 
 
 lever Safety Valve. — A safety valve weighted through the intervention 
 of a lever, as distinguished from spring, and Cowbum valves. See 
 Safety Valve Lever. 
 
 Lewis. — A contrivance for lifting stone and concrete blocks by means of 
 dove-taUed irons attached to a shackle piece. These iit into an under- 
 cut dove-tail in the stone, and are tightened by means of a wedge. 
 
 Lewis Bolt. — A bolt having a jagged and tapered tail. Used for inser- 
 tion into masoiuy, where it is held with lead. 
 
 Life. — Expressive of the total period during which a structure remains 
 efficient. 
 
 Lift, or Hoist, or Ascending-room. — (1) An apparatus used in workshops 
 and warehouses for elevating heavy weights directly to the upper parts 
 of the building without the intervention of stairs. A lift consists of a 
 platform or a rectangular chamber carried up by means of hand power 
 or steam, or hydraulic pressure. (2) The upper part of a mould which 
 is lifted off or taken away from the pattern is called the lift. 
 
 Lifter, — (1) A moulder's tool, usually called a cleaner. It derives its name 
 of lifter from the use to which it is put in lifting loose fallen down sand 
 from the bottoms of flange and rib moulds. (2) Lifters, or gaggers, are 
 hooks of cast iron or wrought iron which are hung from the bars of a 
 moulding box into the mould, in order to afford support to the sand. 
 
 Lift Hammer. — An old-fashioned smith's hammer, which is lifted by a 
 spring pole overhead, and depressed by the placing of the workman's 
 foot on a treadle. The hammer, the overhead pole, and the treadle are 
 alike connected to a pivoted horizontal bar of wood. Sometimes called 
 an Oliver or bolt Oliver. 
 
 Lifting, — The raising up or springing of the top part of a mould, caused 
 by the Kquid pressure due to the head of the molten metal. The tendency 
 to Hft is counteracted either by screw bolts connecting the top and 
 bottom boxes, or by dead weights, or by both combined. The term 
 lifting is also applied to the drawing of a pattern out of the mould. 
 
 Lifting Blocks. — (1) Packing pieces put under the headstook, poppet, or 
 rest of a lathe to increase its capacity for a temporary purpose. They 
 may he either wood or metal packings. (2) Pulley blocks (q.v.). 
 
 Lifting Irons, or Lifting Straps. — ^Pieces of sheet or hoop u-on attached 
 by means of screws to the sides of deep wooden patterns, to enable the 
 moulder to withdraw them from the sand. 
 
 Lifting Jack See Jack. 
 
 Lifting Plates. — Plates of wrought or malleable oast iron furnished with 
 holes both for rapping and screwing, and let into or screwed on the 
 faces of patterns ; and by which they are lifted from the sand, a lifting 
 screw being inserted into the tapped hole in the plate. 
 
 Lifting Pump. — See Suction Pump. 
 
 Lifting Ram. — The smaller ram of the two in a hydraulic forging press, 
 and which lifts the crosshead and tup after each stroke. 
 
 Lifting Screw. — Used for lifting patterns from the sand. It is a round 
 metal rod, having an ordinary screw-thread cut at its lower end, and 
 bent into a loop at the end opposite. The screw is turned into a tapped 
 hole in a lifting plate, and the finger, or a crane hook, inserted into the 
 loop for the purpose of Uf ting or pulling it upwards. 
 
 Lifting Straps. — See Lifting Irons. 
 
 Lifting Tackle.— See Tackle. 
 
MECHANICAL ENGINEERING. 209 
 
 Lift Valve. — A oiroular disc valve fitting on an annular seating, and 
 guided in its lift by three or four feathers projecting' into the body of 
 the seating. Also called puppet, and mushi'oom valve. A lift valve 
 has a full waterway (q.v.) when the amount of its lift is equal to one- 
 fourth its diameter. 
 
 Light Cut. — In metal work a out is said to be light when the shavings 
 removed are thin and narrow. But a cut which would be a light one 
 when taken off a large piece of metal would be a heavy one if taken ofE 
 smaller work. 
 
 Light Firing, or Open Firing. — The making up of a thinsflre, caking it 
 on the dead plate, and frequent renewal of the charges. 
 
 Lighting Chamber. — See Firing Chamber. 
 
 Lighting Cook. — The jet by which the charge in the cylinder of a gas 
 engine is fired. 
 
 Light Oil. — A thin oil (q.v.). 
 
 Light Bunning. — A wheel and axle, a lathe crank, an engine shaft, 
 or journal of a shaft, are said to run light when there is the minimum 
 of friction due to good bearing surface, good fitting, and proper 
 lubrication. 
 
 Lignites. — ^Brown non-calring coals containing a large proportion of 
 water. 
 
 Lignum Vitse . ( Guaiaeum officinale.) — ^A wood of the natural order Zygophyl- 
 lacecB, found in Jamaica, Cuba, and St. Domingo. It is of a dull 
 brownish-green colour, hard, and cross-grained, the fibres interlacing at 
 various angles. The heart wood is chiefly used, and its uses in 
 engineering are for the linings of the shaft bearings of propeller 
 screws, and turbines which work in and are lubricated by water alone. 
 A cubic foot weighs from 40 to 80 lbs. Sp. gr. from '65 to 1'33. 
 
 Lime. — Symbol, CaO. Sp. gr. 3'18. The oxide of the metal calcium, 
 obtained by burning limestone in a Mln. It is an ingredient in con- 
 cretes, in limestones which are used as fluxes, and is present as car- 
 bonate and sulphate in the incrustations of steam boilers. 
 
 Lime Bag. — A linen or muslin bag containing lime powder, used for 
 dusting on the lower joint faces of foundry moulds and on the tops of 
 cores before lowering the top flask part on. The lime touches and leaves 
 an impression on the upper mould face if the joints are close, but non- 
 transfer of the lime indicates openness of the joint, which the moulder 
 sets himself to see the cause of, and to rectify. 
 
 Limestone. — Carbonate of hme. Symbol, Ca CO3. There are numerous 
 limestones, their value to the ironfounder consisting in the property 
 which they have of combining with the infusible sUiceous and earthy 
 matters in the ore and the pig, and thus producing readily fusible com- 
 pounds. Their value to the engineer consists in their property of 
 cementing together to form concrete blocks. 
 
 Limiting Angle of Resistance. — The limiting angle of resistance signifies 
 the angle of repose (q.v.V. 
 
 Limit of Elasticity. — See Elastic Limit. 
 
 Limit of Weight. — In the manufacture of bar iron, beams, and plates, 
 there are certain definite weights ordinarily manufactured. Beyond 
 these weights it is understood that special quotations are necessary. 
 But the limit of weight applies to particular houses only, depending 
 upon the nature of the plant which they possess. 
 
 Linear Advance. — The d&ect measurement which represents the amount 
 by which a slide valve is set forward for lap and lead beyond a line 90'' 
 
J 10 DICTIONARY OF TERMS USED IN 
 
 ahead of the crank. The linear advance is measured on the sheave 
 parallel with its centre. 
 
 Linear Velocity. — The velocity with which a body moves along a path, 
 either straight or curved, the body meanwhile not changing its position 
 relatively to its axis. The body simply undergoes a motion of transla- 
 tion. Linear velocity, when uniform in character, is usually measured 
 by the number of feet moved over in one second. 
 
 line. — (1) A mathematical abstraction which has neither breadth nor 
 thickness, but only length. (2) In mechanics, an aflOtx or prefix, as 
 centre line, chalk line, Ime of centres, in line, pitch line, &c., &c. 
 
 Line Colours. — Draughtsmen's colours used for drawing lines. Black is 
 the colour for actual definition lines. Ked is used for section lines, and 
 blue for dimension lines (q.v.). 
 
 Line Measurement. — Measurement taken by means of the divisions of a 
 rule, as opposed to end measurement (q.v.). This is not an accurate 
 mode of measurement. 
 
 Line of Action, — ^The line of action of a force is the direction in which it 
 acts upon a material point, which Hne must be straight. 
 
 Line of Centres. — When a crank and its connecting rod are in one plane, 
 or when a coupling or other rod is in one plane with the pins which it 
 connects, they are said to be in the line of centres. See Dead Centres. 
 
 Line of Chords. — See Chords, Line of. 
 
 Line of Lines. — See Lines, Line of. 
 
 Line of Pressures. — See Diagram of Work. 
 
 Line of Volumes. — See Diagram of Work. 
 
 Liner. — (1) The bush of a pump barrel or of a cylinder. (2) A thin strip 
 of metal, leather, or wood, placed between parts of machinery in order 
 to permit of the taking up (q.v.) of their wear, and generally to permit 
 of exact adjustment or of better bearing. Liners are put underneath 
 brass bearings to raise them up, and thus compensate for the lowering 
 down due to wear. (3) The wearing surfaces of friction clutches are 
 sometimes lined with copper. Liners are inserted between the feet or 
 flanges of eccentric rods in the operation of valve setting. Marine 
 engine propeller shafts, are provided with brass Uners where they run 
 through the stem bush. 
 
 Lines, Line of. — ^A scale of equal parts on the sectorial scales, marked L, 
 by means of which proportionate distances can be obtained by direct 
 measurement. By combined lateral and transverse measurement, both 
 equal and unequal proportionals can be obtained, hence scales of equal 
 parts, and reduced or enlarged drawings can be made therefrom. 
 
 Line Shafting. — The main shafting in a factory, to distinguish it 
 from the shorter intermediate countershafts (q.v.). Line shafting is 
 commonly run at from 90 to 100 revolutions per minute. 
 
 Linings. — Cements prepared from fire clay or from ganister ; used for 
 covering the interiors of foundry ladles, cupolas, blast furnaces, and 
 converters, to protect their outer iron casings from the action of the in- 
 tense heat. 
 
 Lining Out. — The marking of tie working lines on castings and forgings 
 with scribing blocks and compasses ; called also marking out, and setting 
 out. 
 
 Lining Tip. — The introduction of packing pieces under bearings to com- 
 pensate for their wear. 
 
 Link. — See Slot Link. 
 
 Link Arrangement. — An arrangement of a link and sliding block com- 
 
MECHANICAL ENGINEERING. 211 
 
 mon in shaping macMnes by meana of which the ram is furnished with 
 a quick return (q.T.) motion. 
 link Block. — The movable sliding or die block in a slot link, to which the 
 
 Talve rod is ooimected. 
 Linking Up. — Altering the position of the slot links in an engine fitted 
 with expansion gear, in order to produce an earlier cut-off. The link 
 is raised and lowered by means of a hand wheel and screw, and by its 
 means the amount of lap of the slide valve is altered. 
 Link Motion. — ^The arrangement of levers, and slot and drag links, by 
 which the position of a slide valve in relation to the cylinder ports is 
 regulated for backward or forward gear. Called also reversing gear. 
 Very many kinds of link motion are in use. 
 Link Reversing Motion. — The ordinary type of reversing motion for 
 engines, effected by one of the forms of slot links operating on the two 
 eccentrics, as distinguished from reversal provided for by the direct re- 
 versal of a single eccentric on its shaft. 
 Link Work. — A term sometimes applied to the motion work (q.v.) of 
 engines, sometimes to the coupling or connecting rods of wheels and 
 cranks. 
 Linseed Oil. — The oil expressed from the linseed or seed of flax. When 
 boUed, either alone or with litharge, or white lead, it acquires the pro- 
 perty of drying rapidly, and is therefore used in the composition of oil 
 paints. The clear boiled oil is brushed over castings, when they come 
 from the foundry, to prevent them from rusting previous to inspection. 
 This is done because the oil being transparent will conceal no defects, 
 while paint would cover them up. 
 Lip. — (1) The mouth of a foundry ladle, from which the metal is poured. 
 (2) The nicker or lancet-like edge on a centre bit or similar tool, 
 which cuts the circumscribing circle during the process of boring. 
 List Pot. — A vessel which contains a layer of molten tin about ^ in. deep 
 and in which the list or thickened rim of a tinned plate is placed to effect 
 its removal. When melted the list is detached by a blow on the plate. 
 Litre. — The Standard ^French measure of capacity. It contains 61-02705 
 cubic inches. It is the cube of a decimetre (q.v.), each of whose sides, 
 therefore, measures 3'93708 English inches, andit contains 1'7607 Eng- 
 lish pints, or -2201 gallons. 
 Live ^le, — ^A driving axle (q.v.). 
 Live Head. — A term sometimes appKed to the headstock (q.v.) of a lathe 
 
 in opposition to the poppet (q.v.) or deadhead. 
 Live Load. — When a structure is subjected to the alternate and often 
 repeated imposition and relief of weight, the term live load is used to 
 distinguish it from a dead load (q.v.). Also the greater the range of 
 variation of stress, and the greater the number of repetitions of the 
 load, the more severe will the straining actions become, and hence larger 
 factors of safety are required in the case of structures subject to Uve, 
 than in those subject only to dead loads. Called also variable load. 
 Live Bing. — A live ring consists of a number of conical rollers an'anged 
 in circle between an outer and inner ring of flat wrought iron, into 
 which the ends of the roUer spindles are fastened. In some cases the 
 roUera almost fill up the ring, and then they are not provided with 
 spindles. These rollers are employed for turntable centres chiefly. 
 Live Boiler. — A roller which does not revolve on a spindle, but is free to 
 move aroimd or along its path. Live rollers are used for turntable 
 centres, and the slewing motion of large cranes. 
 
212 DICTIONARY OF TERMS USED IN 
 
 Live Spindle. — A spindle wHoh oommumcates motion, as the mandrel of 
 a headstook or live head (q.v.). 
 
 Live Steam. — The entering steam in a, cylinder, as distinguished from 
 that which is exhausting. 
 
 Load. — The total amount of -weight home by a structure tending to 
 deform or break it, its own weight included. In the ease of a moving 
 body it includes the reaction due to friction and inertia. Loads are 
 classed as live loads (q.v.), dead loads (q.v.), impulsive loads (q.v.). 
 
 Loam. — Strictly speaking a stifE impure clay, but as the term is employed 
 in foundries it signiiies a mixture of clay, sand, and horsedung, ground 
 up with water in a loam miU (q.v.), and used in loam work. Though of 
 sufficient consistence when cold to be struck up to any desired outline 
 by means of the chamfered edge of a loam board, it dries hard when 
 exposed to the heat of the foundry stove. 
 
 Loam Board. — A board having an edge cut to the outline of the sectional 
 shape of the work which it is intended to strike up ; the edge being 
 chamfered also in thin knife-like fashion to prevent the loam from 
 being dragged out after the board. The term loam board is applied to 
 boards for striking both patterns and moulds. 
 
 Loam Brick. — A cake of loam made roughly to the size and shape of an 
 ordinary brick. These are used for building up those portions of loam 
 moulds where the unyielding nature of the common bricks would 
 cause the casting to break by preventing its due contraction when 
 cooling, and also in cases where it is probable or desirable that some 
 portion of the brick framework may have to be cut away during the 
 progress of the moulds. 
 
 Loam Cake. — A flat slab made of loam (q.v.) and dried. Used to form 
 the face of a flange or similar expansion, or some portion of a draw- 
 back, or as a^convenient piece from which a portion of a mould or of a 
 pattern can be cut with facility with saws and rasps and glasspaper. 
 
 Loam Hill. — A mfll essentially like a mortar mill (q.v.), but employed 
 for the mixing of loam (q.v.) for foundry use. 
 
 Loam Mould, — A movdd made in loam. 
 
 Loam Moulder. — An iron founder whose work lies chiefly in the making 
 of moulds in loam or dry sand, in opposition to moulders who work in 
 green sand. Loam moulders do not use complete patterns, but strike 
 up their work with the edges of loam boards while the loam is in 
 a plastic state. Loam moulds, unlike green sand moulds, have to 
 be dried before the metal is poured in. 
 
 Loam Moulding. — TTxe process of moulding in loam (q.v.) as dis- 
 tinguished from green sand moulding (q.v.) 
 
 Loam Pattern. — Large patterns of a circular or segmental outline which 
 can be produced by the aid of strickles or of loam boards are often 
 made in loam, and moulds are taken from them as from ordinary wood 
 patterns. 
 
 Loam Plate. — A flat plate of cast iron used to form the base or foun- 
 dation for striking up a loam mould (q.v.). It is usually provided 
 with projecting lugs around its circumference by means of which it is 
 lifted, and with gaggers or prods on its surface to hold the loam. 
 
 Loam Work. — Work moulded in loam. It is usually considered more 
 difficult than work in green sand (q.v.), and loam moulders command 
 the higher wages. It is specially adopted in cases where perfect 
 soundness of castings is required, and also where it is desired to save the 
 cost of a pattern. 
 
MECHANICAL ENGINEERING. 213 
 
 lock Nut. — A thin nut screwed down upon another. Its purpose is to 
 prevent the slacking back of the main nut under excessive vibration. 
 
 Lock Saw. — A pad saw (q.v.). 
 
 Lock-up Safety Valve. — A safety valve whose spring is enclosed in a 
 padlocked casing'. 
 
 Locomotive. — A steam engine complete with its boiler, its fittings, and 
 mountings, fixed in a carriage or framing, and provided with suitable 
 wheels, axles, buffers, drawbars, &c., to enable it to draw loaded 
 wagons upon the permanent way. 
 
 Locomotive Boiler. — See multitubular boiler. 
 
 Locomotive Crane. — A travelling crane propelled by steam, either driven 
 by a pair of cylinders independently of those which actuate the lifting 
 gear, or by means of clutch work connected with the engine shaft. 
 Properly speaking the former are locomotive cranes and the latter 
 travelling cranes merely. 
 
 Locomotive Hoist. — See Carriage Hoist. 
 
 Log. — (1) A balk of timber, either squared or rough. (2) The logarithm 
 (q.v.) of a number. 
 
 Logarithms, — A series of numbers which have a certain relation to the 
 natural numbers, and by which arithmetical calculations are facilitated. 
 Logarithms are the indices of numbers in geometrical progression. 
 
 Long Columns. — When the length of a column exceeds its diameter by 
 from 25 to 30 times it comes under the category of long columns, which 
 yield under pressure by bending alone, in the same manner that a beam 
 supported at both ends will yield. 
 
 Long D-Valve, or Long Valve. — A long slide valve used is some of the 
 older beam engines, so called because it extended over the ports at 
 each end of the cylinder, the ports being situated near the ends of the 
 cylinder to avoid the waste of steam consequent upon long passages. 
 
 Longitudinal Elevation, or Side Elevation. — A view showing the side of 
 a structure, as distinguished from its end view. 
 
 Longitudinal Seams. — The seams or joints running lengthways in a 
 boiler. They should always be made to break joint ; never be put " in 
 line." 
 
 Longitudinal Section. — A sectional drawing taken through a structure 
 in the direction of its length. 
 
 Long-toothed Gauge. — A gauge with a movable tooth or marker used 
 for gauging lines which are not in the same plane as the stem. The 
 head is made long to permit of variation in vertical movements corres- 
 ponding with those of the marker. 
 
 Long Valve. — See long ^-^i\:ve. 
 
 Loose Centres. — Heads very similar to lathe poppets, provided with screw 
 mandrels, and centre points. They are used as supports for some classes 
 of work, both when being lined out and when being shaped on a 
 planing machine. Hence called machine or planer centres. The 
 centre lines, and keyways of shafts when suspended between these 
 centres are marked with a scribing block ; lines and distances are 
 also marked ofi and squared up from a surface plate or marking- 
 ofl table. When clamped or bolted to a planing machine table the 
 work between the centres can be partially or completely rotated to bring 
 different sections under the action of the cutting tool, so that both 
 circular and irregular shaping can be done in a planing machine by the 
 use of loose centres. 
 
 Loose Coupling. — ^A shaft coupling which is made capable of instant dig- 
 
SI4 DICTIONARY OF TERMS USED IN 
 
 comieotion, either by claw engag'ements or ty friotional surfaces, as 
 distinguislied from permanent or fast couplings (q.v.). 
 
 Loose Eccentric. — A single and adjustable eccentric sheave used for 
 reversing engines which are not provided with the ordinary link 
 reversing gear. 
 
 Loose G-land. — A form of gland used in making the joints of hot water 
 piping. It is a loose ring furnished with two lugs and bolt holes, and 
 is slipped over the spigot end of a pipe. An india-rubber ring is then 
 placed in front, the spigot is slid into its socket, which has corre- 
 sponding lugs and bolt holes, and the two are bolted together. The 
 iron ring fitting loosely around the spigot allows of expansion, while 
 the india-rubber ring makes the joint watertight. 
 
 Loosening. — Rapping (q.v.). 
 
 Loosening Bar. — A round and pointed bar of iron used for rapping 
 patterns. 
 
 Loose Pieces. — Certain portions of pattern work, which standing out 
 beyond those faces which have to be lifted in a vertical direction, cannot 
 be drawn along with, and at the same time as the pattern, without 
 draggiag up the superincumbent sand, and are therefore attached 
 loosely or temporarily during ramming, being afterwards withdrawn 
 sideways into the space left by the main pattern. Sometimes pieces 
 are made loose in the top to Uft with the top box and be afterwards 
 withdrawn. Loose pieces are held during ramming with dowels, 
 skewers, or dovetails. 
 
 Loose Pulley. — The idle or carrier puUey of a pair, on which the belt runs 
 when the machine which the belt has to drive is not in use. When the 
 machine has to be driven the strap is shifted from the loose to the 
 fast pulley (q.v.). 
 
 Lorry, or Lurry. — A low truck used for running loads about on yard and 
 other tramways. 
 
 Loss. — In mechanical exchanges there is no actual loss (see Conservation of 
 Energy). But it is 'customary to use the term loss to designate the 
 difference between the calculated or theoretical and the actual work 
 obtained from a mechanical arrangement, the loss being due to the 
 imperfections of the arrangement. 
 
 Loss of Head. — The diminution in the weight and pressure of a liquid 
 column. Loss of head is due to the friction of long pipes and to the 
 presence of quick bends. 
 
 Loss of Heat. — This is due to transmission by conduction, or by radiation. 
 In engine boilers, cylinders, and steam pipes this is reduced by the prac- 
 tice of cleading (q.v.) or felting (q.v.). 
 
 Lost Motion. — The difference in the rate of motion of driver and driven 
 parts, due to bad or loose fitting, slips, &c. The term is frequently 
 used in reference to drill spindles, belting, &c. 
 
 Lost Pass. — The backward pass of a bar or rail over the top of a two 
 high mill (q.v.) which is not provided with reversing motion. 
 
 Low Breast Wheel See Breast Wheel. 
 
 Low Flashing Point. — An oil is said to have a low flashing point when it 
 will take fire at a low temperature. 
 
 Low Freezing Point. — A low freezing point is a valuable property in a 
 lubricating oil in England and in the colder climates, since bearings 
 are less liable to become gummed than when the oil freezes readily. 
 
 Low Moor. — The best quality of wrought-ironplate manufactured in the 
 United Kingdom is made at Low Moor, in Yorkshire. 
 
MECHANICAL ENGINEERING. 215 
 
 Low Press. — A wortahop abbre-nation, signifying the low-pressure cylin- 
 der in a oompound engine. 
 
 low-pressure Cylinder. — The larger cylinder in a compound engine into 
 which the expanded steam exhausts from the high-pressure cylinder. 
 
 Low-pressure Engine. — ^An engine which exhausts its steam into a 
 condenser. 
 
 Low-pressure Steam. — Steam which is either below or but a few pounds 
 in excess of the atmospheric pressure. 
 
 Low Bed Heat. — In forged work is a colour corresponding with a degree 
 of temperature midway between a black red heat (q.v.) and a bright 
 red heat (q.v.). It may be roughly taken at 1,290° P. 
 
 Low Water Alarm, — ^An apparatus which is used to announce when the 
 water in a steam boiler falls to a dangerously low level. In modem 
 practice the water gauge (q.v.), try cocks (q.v.), and fusible plugs 
 (q.v.) are the only indicators of water level used. In the old boilers, 
 arrangements of floats and weights were employed, by which, at low 
 water, a jet of steam was directed against the steam whistle, or some- 
 times a float and index board alone were used. 
 
 Low Water Safety Valve. — A low water alarm (q.v.), which is con- 
 structed to discharge the steam when the water falls below a safe level. 
 
 1_-Eest. — A lathe rest for hand turning made in the shape of the letter [_, 
 the head on which the tool rests being flat and short, and the leg which 
 fits in the socket being of the usual length. This rest is useful for 
 short work where the ordinary X-^'^st would be too long, and for 
 attaching to a slide rest for temporary hand turning. 
 
 Lubricant. — ^An unguent interposed between two bearing surfaces to 
 prevent them from coming into actual contact, and becoming abraded 
 by their mutual friction. The lubricants are commonly oils and tallows. 
 When bearings are submerged in water the latter furnishes the means 
 of lubrication. There are certain qualities which a good lubricant 
 should possess, the first of which is, that as compared with others, a 
 minimum quantity of heat only should be generated during a maximum 
 number of revolutions. In addition to this a lubricant should have a 
 low freezing point, so as to remain fluid all the year round ; a high 
 fiashing point (q.v.), in order to diminish the risk of spontaneous com- 
 bustion (q.v.) ; freedom from excessive tendency to gumming (q.v.), 
 and from acid, which is generated in some bad oils to the injirrious 
 corrosion of the bearing and other parts with which it comes in contact ; 
 suitable body or viscosity for heavy or hght machinery, as required ; 
 good power of capillarity, to insinuate its way between bearings ; free- 
 dom from rancidity ; and durability and uniformity of action. All 
 these qualities are capable of being put to actual test, and the highest- 
 priced oils often prove to be the cheapest in the end. 
 
 Lubrication. — The distribution of an unguent over bearing surfaces to 
 preserve them from the heating which results from the friction of sur- 
 faces in actual contact. The nature of the lubricant selected will 
 depend altogether upon its suitability for the particidar purpose for 
 which it is designed, the lubricants having most body being chosen for 
 heavy machinery, the light thin oils for light machinery. A thin oil 
 would be squeezed out of a heavy bearing at once, and a thick oil 
 would demand an increase of driving power to overcome its viscosity. 
 Lubrication is effected by various oil cans or oil feeders, self-acting or 
 otherwise, described under their various heads. 
 Lubricator. — ^A contrivance for supplying a regular amount of on or 
 
2i6 DICTIONARY OF TERMS USED IN 
 
 grease to a journal or bearing. It is sometimes of the needle form, 
 that is, a length of wire coming to the joumal acts as a carrier of oil from 
 an inverted glass receiyer, whose mouth is closed with a hit of tuhe. 
 The feeding takes place partly by capiHary attraction, partly by the vi- 
 bration of the shafting. If iiie bearings become heated the oil is ren- 
 dered more fluid and flows easier. See Axle Box, Impermeator, &o. 
 
 Lug. — An ear or projection upon a casting for the reception of bolt or 
 other attachments. 
 
 Luminosity. — Luminosity is due to the radiation of heat, the intensity of 
 the heat rendering visible the radiations of the different coloured rays ; 
 at a red heat the red rays are visible, but at a white heat all the rays 
 of every colour are blended and visible. The shades of luminosity vary 
 from a black red (about 1,000° F.) to a white heat (about 2,700° F.), 
 
 Lumps Special fire bricks, made expressly for the linings of blast 
 
 furnaces. 
 
 Lurry. — A lorry (q.v.). 
 
 Lustre Metallic lustre is due to the reflection of the Ught rays from a 
 
 smooth surface. A rough surface, being made up of a number of 
 minute surfaces, reflects and scatters the rays of light ; a smooth sur- 
 face reflects them almost wholly back. Hence the lustre depends upon 
 the density of a material, and upon the degree of smoothness or polish 
 imparted to it. 
 
 Lutes. — The materials used for rendering air-tight those vessels which 
 have to be exposed to the heat of a melting furnace, as crucibles, 
 annealing pots, &c. Stourbridge clay in powder, made into paste with 
 water, and loam, are used. 
 
 Luting. — Luting is the mode of connecting pipes, or tubes, or vessels 
 to prevent the entrance or escape of gases. In brass foundries 
 crucibles are often luted by placing an empty one over the one con- 
 taining the metal, or by placing a cover on it. 
 
 M. 
 
 M. — The Greek letter ii, the symbol of the coefficient of friction. 
 
 Machine. — A machine may be defined as an assemblage of parts, some 
 fixed, others movable, by which motion and force are transmitted. 
 
 Machine Centres. — See Loose Centres. 
 
 Machine-out Pattern. — The teeth of the change wheels of lathes are 
 either cut out by a wheel-cutting machine or are cast to shape from 
 patterns. In the latter case the patterns themselves are cut in a 
 machine, wood patterns not being sufficiently reliable. The wheels 
 made from machine -cut patterns are the better of the two, the hard 
 skin which results from contact with the sand rendering them more 
 durable than the others. 
 
 Machine Cutters. — Usually understood not of cutting tools, but of the 
 various milling wheels, reamers, &c. 
 
 Machine Drilling, — The drilling of work under a power-driven drilling 
 machine. All light work, all repetition work, and much of the heaviest 
 work is done under a machine. In exceptional cases hand drilling 
 (q.v.) is resorted to. 
 
 Machine Foundations. — Machines doing heavy work, drills, planing, 
 slotting, shaping, punching, shearing, and other machines of this class, 
 
MECBAmCAL ENGINEERING. 117 
 
 are liolted to massive foundations of stone or concrete, tail bolts teing 
 sunk into the foundation to -whioli tlie macMne bases are bolted. 
 
 Machine-moulded Wheels, — Cog wheels, both spur and bevel, moulded 
 by the aid of a machine, and in the making of -which sectional portions 
 only of a pattern are necessary. (See Wheel-moulding Machine.) The 
 essential pattern parts required are a tooth block containing two teeth 
 and a core box for spur wheels, and striking boards also, in addition to 
 these, for bevel wheels. The wheels have the advantage of great accu- 
 racy of pitch and cleanliness of surface. They take longer in moulding 
 than those made from a pattern, but their superiority to these enhances 
 their value, notwithstanding that the cost of a pattern is saved. 
 
 Machine Moulding. — This embraces the moulding of wheels and ordinary 
 work by the aid of special machines. In the wheel-moulding machines 
 the pattern teeth alone are carried round an exact and measured dis- 
 tance after the ramming up of each successive tooth, and the ramming 
 is done by hand. But in most moulding machines for common work 
 almost all the work is done automatically, even to the ramming of the 
 sand in some oases, so that all the moulder does is to actuate the levers 
 and finally clean and close the mould. 
 
 Machine Eiveting, — Riveting performed by a single application of steady 
 pressure at the same instant upon the tail and the head of a rivet. 
 
 Machinery. — Machinery comprises the various machines in a factory. 
 These are assessed at a definite sum, and a certain amount written off 
 their value each successive year for depreciation (q.v.). It is usual in 
 estimating the charges on work to enter a definite sum per day for the 
 use of each machine, to cover the cost of depreciation. This may range 
 from a few shillings to a pound or more. 
 
 Machine Shop. — The shop in which the operations of engineering requiring 
 the use of machines, as distinguished from fitting and erecting, are car- 
 ried on. The turning shop or turnery is usually included in the same 
 department. The smaller machines are ranged in rows, leaving room 
 for the workmen to pass around them freely. The larger ones are 
 placed as most convenient for the moving of heavy masses of work. 
 All are driven through the medium of countershafts, deriving their 
 motion from the row or rows of line shafting overhead, and are served 
 by overhead travellers, of light or heavy construction according to the 
 class of work done in the shops. 
 
 Machine Tap. — A tap for use specially in screwing machines, as distin- 
 guished from the hand taps, which are actuated by a tap wrench. 
 
 Machine Tools. — These embrace the various machines used in the depart- 
 ments of engineers' works, by turners, drillers, slotters, planers, boiler, 
 makers, &c., together with the various cutting, punching, and shearing 
 tools attached to, and forming a portion of the same. 
 
 Machine Vice, or Vice Chuck. — A small long parallel jawed vice, used on 
 the tables of planing, shaping, and drilling machines, for holding smaU 
 and irregularly shaped pieces of work which cannot be conveniently 
 bolted to the ordinary tables. 
 
 Machining. — Denotes generally the operations performed by machines on 
 metal work ; — tirming, planing, shaping, boring, &c., are comprehended 
 under the general term of machining. It is used both in specifications 
 and in the shops. 
 
 Machinist. — Machinists are a class of men distinct from fitters, erectors, 
 and turners, and signifies those who have charge of planing, drilling, 
 slotting, shaping, and similar machines. They are not apprenticed, but 
 
3i8 DICTIONARY OF TERMS USED IN 
 
 are simply recruited from the rants of imsldlled labourers and handy 
 
 men, and receive wages ranging midway between those of labourers and 
 
 mechanics. 
 Uagnesian Limestone. — A compound of carbonate of lime and magnesia 
 
 which is employed for the lining of converters in the basic process. 
 Magnesite. — An impure magnesia found in Buboea, and other places, 
 
 used for magnesite bricks. 
 Magnesite Bricks. — Kre bricks used as linings in converters and rotary 
 
 puddling furnaces. They are formed of impure magnesia calcined 
 
 and mixed with from 15 to 30 per cent, of raw and partially calcined 
 
 magnesia, and from 10 to 15 per cent, of water, the whole being dried 
 
 and burnt. 
 Magnetism. — The adherence of particles of metal to the points of drOla, 
 
 and metal turning and other tools, is due to the development of the 
 
 residual magnetism therein by friction. 
 Magnetite. — A magnetic iron ore abounding in the north of Europe and 
 
 America, largely quarried for commercial purposes. The Daunemora 
 
 iron from Sweden is a variety of this ore, and so also is the loadstone. 
 Magneting. — The separation by the action of magnets of particles of iron 
 
 from brass and copper turnings, previous to remelting. 
 Magneting Machine. — A machine used for magneting (q.v.) to save the 
 
 time occupied in the use of hand magnets. 
 Magnitude of Force. — The magnitude of a force is the aggregate of the 
 
 units of force which compose it, estimated in lbs. or tons, or other unit 
 
 terms. 
 Mahogany. [Swietenia mahogoni.) — Sp. gr. '56 to "85. A close-grained 
 
 red-coloured wood, belonging to the natural order Cedrelacea^. There 
 
 are two principal varieties of mahogany : — Spanish, which comes from 
 
 Cuba and St. Domingo ; and Honduras, or bay wood, which comes from 
 
 Honduras and around the Bay of Campeachy in Central America. The 
 
 latter is that chiefly used for common work, berog cheaper and more 
 
 readily worked than the Spanish. Mahogany is used for maldng the 
 
 better class of patterns. 
 Main Bearings. — The bearings for the crank shaft of an engine. 
 Main Centre. — In side-lever engines is the shaft upon which the side 
 
 levers vibrate. 
 Main Chuck. — A lathe chuck intermediate between the mandrel and the 
 
 actual driving chucks. 
 Main Cylinder. — The principal or working cylinder of an engine, as 
 
 distinguished from balance cylinders (q.v.), oil cylinders (q.v.), c&c. 
 Main Driving Belt. — The first motion belt, which comes direct from tho 
 
 motor of a workshop to the main driving pulley. 
 Main Driving Pulley. — The first or principal pulley on the line shafting 
 
 (q.v.) of a workshop or factory, or a pulley which has to do specially 
 
 heavy work in comparison with others. 
 Main Frames. — The frames of a locomotive which carry the boiler, axle 
 
 boxes, cylinders, c&c. 
 Main Link. — The link which is attached to the end of the beam in the 
 
 arrangement of levers known as parallel motion (q.v.). 
 Main Screw. — A guide screw (q.v.). 
 Main Valve. — Denotes the slide valve proper, when the expansive 
 
 working of the steam is provided for by a separate expansion or cut-off 
 
 valve (q.v.). 
 Major Axis.— See Transverse Axis. 
 
MECHANICAL ENGINEERING. 219 
 
 Make.— See Yield. 
 
 Making Joints. — The bringing together and seouring with proper 
 cements, or other steam or water tight agents, the joints of steam and 
 water pipes. 
 
 Making TTp. — Mending up (q.v.). 
 
 Making-up Piece. — A mending-up piece (q. v.) . 
 
 Malacca Tin. — Called also Banca tin, Straits tin. It is sold in pyramids 
 weighing about 1 lb. each. 
 
 Malachite. — Carbonate of copper. Green malachite is found in tie Ural 
 mountains and in Australia. Blue malachite is found at Burra Burra, 
 in Australia. The blue variety contains more carbonic acid than the 
 green. 
 
 Male. — "When a stud or a dowel fits into a recess it is said to be the male 
 portion of that particular piece of work. 
 
 Malleability. — The quality possessed by metals of becoming extended 
 under rolling, pressure, or hammering. 
 
 Malleable Cast Iron. — Cast iron which has been subjected to partial decar- 
 burisation. This is effected by keeping the castings in contact with 
 substances rich in oxygen at a high temperature for several hours, 
 or even days, according to circumstances. The substances employed 
 are oxides of iron, usually haematites, which part with their oxygen in 
 order to combine with the carbon in the castings, thus reducing them 
 to a condition approaching that of wrought iron. Except for small 
 work, malleable cast iron is not to be relied on, and has therefore but a 
 limited use. 
 
 Malleable Iron. — See "Wrought Iron. 
 
 Malleable Nails. — Pipe nails (qv.) made of malleable iron to prevent the 
 risk of blow-holes in the casting. 
 
 Mallet. — (1) A heavy wooden hammer used for the deHvery of blows on the 
 handles of chisels and gouges without incurring the risk of splitting 
 them down, as is the case when iron hammers are employed for that 
 purpose. (2) Hound-faced wooden mallets are used by moulders for 
 rapping patterns during their withdrawal from the sand, to facilitate 
 the detachment of the sand. Similar mallets are used by boiler- makers 
 for leveUing or bending their plates of wrought iron and steel. 
 
 Manager. — The individual who has a general supervision of an engineer- 
 ing works. There are two kinds of management, one general, the 
 other more limited. The general manager has charge of the entire 
 factory, including the of&ces, and undertakes or supervises the estimates, 
 tenders, expenses, &c., and is usually an educated engineer who has 
 been duly articled and gone through the shops and offices, and who 
 receives the salary of a professional man. The works manager has no 
 control over the offices, but only superintends the shops. He is usually a 
 practical man who has risen from the ranlcs. 
 
 Manchester Principle. — The system of diametral pitches (q.v.). 
 
 Mandrel, — Sometimes erroneously spelt mandril. (1) A cylindrical rod. 
 (2) A revolving spindle of wrought iron or steel used for chucking lathe 
 work upon. (3) The spindle of a circular saw is a mandrel. A lathe 
 mandrel is either the spindle of the headstock, or that of the poppet. A 
 smith's mandrel, or a "nut" mandrel, is a round rod upon which 
 nuts are finished to shape. 
 
 Mandril. — See mandrel. 
 
 Manganese. — An element which is invaluable to the steel manufacturer 
 owing to its entering more readily than iron into combination with 
 
220 DICTIONARY OF TERMS USED IN 
 
 oxygeu and sulphur. Iron containiiig from 5 to 20 per cent, of man- 
 ganese is called spiegeleisen ; if it contain more tlian 20 per cent, it is 
 called ferromanganese. 
 
 Manganese Bronze. — An alloy of copper and ferromanganese. The latter 
 is melted in a separate crucible and added to the copper, the manganese 
 cleansing the copper by reason of its affinity for oxygen. It is useful 
 when toughness is an essential, as in propeller blades. 
 
 Man Hole. — ^An oval opening in the shell of a boiler through -which the 
 attendant gains access to the interior for the purpose of examination 
 and cleaning. It is always stayed either with a ring of wrought iron 
 or with a casting. 
 
 Manilla Hopes. — Kopes used sometimes in preference to hemp for the 
 transmission of power. They are white or untarred, and are stronger 
 and more durable than those of tarred hemp, so that to do the same 
 amount of work a rope of manilla need not be so large as a hempen 
 one. The ropes are made in Manilla, in the Philippine Islands, from the 
 fibre of leaf -stalks of the Musa hoglodyarum, a species of plantain or 
 banana. 
 
 Mare's Grease. — A yellowish brown grease imported from Monte Video 
 and Buenos Ayres, being the fat of the mares slaughtered for their 
 hides, bones, and grease. Used for purposes of lubrication. 
 
 Margery's Fluid. — Sulphate of copper dUiited with water, and used for 
 the impregnation (q.v.) of timber. It is applied under pressure. 
 
 Margin of Safety. — 'The factor of safety (q.v.). 
 
 Marine Boiler. — Marine boilers are usually of the return tubular (q.v.) 
 type, but many variations in the arrangements are necessitated by 
 different conditions. 
 
 Marine Engine. — A generic term which denotes an engine used for pro- 
 pelling a vessel. Those commonly used in the present day are of the 
 inverted cylinder (q. v. ) type and of the compound surface condensing 
 class. See also Trunk Engine, Oscillating Engine, and Steeple Engine. 
 
 Marine Glue. — India-rubber, shellac, and mineral oil combined to form a 
 hard black cement. It is melted by the application of heat and is used 
 for making joints in packing cases water tight, by saturating strips of 
 canvas with it and sticking them along the faces of the joints. 
 
 Marine Pattern Connecting Rod. — That form of rod in which the bearing 
 end has two brasses, with or without an iron cap, and secured by bolts 
 to flat expansions of the wrought-iron end of the rod ; as distinguished 
 from box end, or strap end forms. 
 
 Marker Out, or Liner Out. — A workman whose special duties consist in 
 marking out the centres, working lines, &o., of metal work in readiness 
 for the machinists and fitters. 
 
 Marking Gauge. — A gauge used for marking the thickness of timber 
 which has to be planed to an equal dimension throughout. 
 
 Marking-off Table. — A planed cast-iron plate or table, strengthened and 
 stiflEened with flanges upon the under side, and employed as a basis for 
 marking oft the centres and working lines on rough castings and forg- 
 ings before they go to the machines to be planed, turned, and bored. 
 Being planed true on face and edges and blocked up and levelled, the 
 square and scribing block can be employed with accurate results. The 
 marking-out table is a necessary adjunct in all fitting shops of moderate 
 and large size, so that the sole responsibility of lining-out rests with the 
 two or three men who are employed thereon perpetually. 
 
 Marking Out. — See Lining Out. 
 
MECHANICAL ENGINEERING. 221 
 
 Marks. — See Brands. 
 
 Marlborough Wheel. — A cog -wheel whose teeth are elongated sufficiently 
 
 to gear with two other narrow wheels on different spindles. 
 Mass. — The quantity of matter in a body, not to he confounded with 
 weight, since the mass remains constant in any part of the earth's 
 surface, while the weight depends on the force of gravity, and therefore 
 on the latitude. 
 Mast. — The vertical timher in a derrick crane. 
 
 Master Jet, or Master Light. — The outer gas jet of the two in those gas 
 engines where the inner jet is extinguished by the force of the explo- 
 sion. Its function is to relight the inner one in readiness for the next 
 explosion. 
 Master Light. — A master jet (q.v.). 
 
 Master Tap. — A hob or hub (q.v.) used for cutting steel dies. 
 Master Wheel. — A dividing wheel used for cutting the teeth of gears. It 
 is properly of large diameter, in order to the minimising of errors due to 
 its own pitching out, such errors being reduced in the case of all wheels 
 smaller than itself. If the master wheel is of small diameter its errors 
 are magnified when cutting wheels of larger diameter. 
 Masting Shears. — Shear legs erected over the edge of a dock, and used for 
 lifting and lowering the masts of ships into their hulls. The gearing is 
 usually placed at some distance behind the shears and the power ia 
 transmitted thereto through chains. 
 Mast Winch. — A winch (q.v.) which is worked either by hand or steam, 
 
 and fastened to a ship's mast or to a pillar. 
 Match Flate. — A board or plate of wood or metal upon whose opposite 
 faces two different portions of a pattern are put for moulding. The 
 boxes containing the impressions, when brought together, constitute a 
 complete mould. See Plate Moulding. 
 Mate. — It is customary to term any two men who work together, mates, 
 but the tenn is more particularly applied to smiths and their hammer- 
 men, and to boiler-makers, platers, and angle-iron smiths and their 
 strikers, because they always keep together, and only change in the 
 case of illness or dismissal. 
 Matrix. — (1) Amould (q.v.) is amatrix, though the tennis seldom applied 
 thus. (2) The earthy matter which contains metallic ores is called the 
 matrix. 
 Matt, or Eegulns.— Copper matt is the resulting product after the oxide of 
 iron present in the ore has been caused to combine vrith sOica. It is 
 granulated by being poured while molten into a vessel with a perforated 
 bottom through which a stream of water is set running. Eegulus may 
 be coarse metal or fine metal, the former being produced in an early 
 (called the second) process, the latter in a subsequent (called the fifth) 
 process. 
 Maul. — A wooden hammer or mallet. Sometimes also applied to a smiths' 
 
 sledge-hammer. 
 Maximum Dimensions. — In the manufacture of iron bars and plates 
 there are certain dimensions given by most houses as the maximum. 
 For sizes exceeding these special quotations are necessary. 
 Maximum Pressure. — The utmost pressirre which is brought to bear upon 
 a body or structure. Commonly has reference to the pressure of 
 elastic fluids and liquids. Prom the maximum pressure and the rates 
 of expansion the mean pressure is deduced. 
 Maximum Strength, — This refers to the disposition of a definite quantity 
 
222 DICTIONARY OF TERMS USED IN 
 
 of material in suoli a manner that a structure of the strongest section 
 containing that quantity of material shall he designed. IDustrationa 
 are to be obtained in the sectional and longitudinal forms of timber 
 beams, iron flanged girders, and columns. 
 
 Maximum Weight. — The utmost weight or load which a body or struc- 
 ture has to sustain. It has reference to the pressure of dead and 
 Tariable loads. On the maximum load the factor of safety is based. 
 
 Mean. — The term is of wide application, signifying the average, as mean 
 head, mean height, mean quantity, mean pressure, &c. 
 
 Mean Effective Pressure. — The average pressure upon a piston, minus the 
 resistance due to back pressure. 
 
 Mean Pressure. — The average pressure upon the piston in a steam 
 cylinder taken through the entire stroke. 
 
 Mean Strength. — The average of the strengths of similar bars or beams, as 
 deduced from experiments. 
 
 Measurement. — Correct measurement is of the utmost importance in 
 engineering. For common work direct measurement with the rule is 
 sufficient, for better work, calipers, and gauges, both cylindrical and 
 the micrometrical are employed. Por sheet metals, wire gauges are 
 used. Measurements are given in inches, fractions and multiples of the 
 inch, and of the millimetre, and in the numbers of the wire gauges. 
 
 Measuring Machine. — The measuring machiue of Sir Joseph Whitworth 
 consists of two heads mounted on a bed, one fixed, the other movable. 
 Each headstock is provided with a mandrel and graduated wheel. 
 The mandrels are actuated by screws. Knowing the number of threads 
 in the screw and the number of graduations in the hand wheels and 
 the teeth in a worm wheel driving one of the screws, the exact amount 
 of forward movement can be deduced. 
 
 Measuring Eod. — See Standard Eod. 
 
 Measuring Tape. — A narrow tape or riband enclosed in a circular casing 
 from which one end is drawn out as required for measurement. Tapes 
 vary from 33 to 100 feet, andfrom 20 to 25 inches in length. They are 
 divided into feet and inches, and parts of inches, and into chains. 
 They are made of linen strengthened with wire, and of ribbon steel. 
 Tapes alter in length with the moisture in the atmosphere, but should 
 not be more than \ out in their total length. They are used for out-door 
 work chiefly, and for taking circumferences or arc measurements of large 
 pieces of work. 
 
 Mechanical Centres. — tJsually denote the centres of gravity, gyration, 
 oscfllation, and percussion. See appropriate headings. 
 
 MechanicarEngineering. — The art of construction of mechanism generally, 
 comprising both prime movers and machines. It embraces designing, 
 drawing, pattern-making, moulding, smiths' work, turning, boring, 
 diilling, shaping, planing, fitting, millwright's work, boiler and platers' 
 work, and erecting. 
 
 Mechanical Equivalent. — When one piece of mechanism is substituted 
 for another, the mechanical effect remaining the same, it is termed a 
 mechanical equivalent. 
 
 Mechanical Puddler. — A puddling (q.v.) fiunaee in which the operations 
 of hand puddling are performed automatically. 
 
 Mechanical Eabhle. — A rabble (q.v.) to which reciprocal motion is given 
 
 'by means of gearing and levers. 
 Mechanical Stoker. — A term applied to various pieces of automatic 
 apparatus for supplying uniform amounts of fuel to steam boilers. lu 
 
MECHANICAL ENGINEERING. 223 
 
 one form an endless chain takes the place of fire bars, and slowly travels 
 the fuel from the front of the furnace to the back, by which time it is 
 consumed. In another form the fuel is fed from hoppers placed over 
 the fire doors, the feeders being worked by gear direct from the engine. 
 
 Mechanics. — That branch of science which treats of the effect of force 
 upon matter. It is conveniently divided into the two sections of 
 statics (q.v.) and dynamics (q-v.), and embraces in its widest sense 
 the actions of solids, fluids, and liquids. 
 
 Mechanism. — Commonly understood of an assemblage of parts which, 
 without necessarily constituting a complete machine, embraces the 
 essential principles on which the machirie is constructed. Thus the 
 mechanism of a drilling machine would include the gear and spindles 
 apart from the framework, the mechanism of an eccentric would be 
 regarded independently of the details of its attachment, and that of an 
 engine distinct from the mode of its fixing. 
 
 Mediiim Drawing Paper. — Measures I'l x 17j. 
 
 Medium Hard. — A quality of emery wheel useful for shaping edges of 
 tools, saws, and trimming castings. 
 
 Medium Soft. — A quality of emery wheel useful for general surface work. 
 Por grinding narrow edges it wears away too rapidly. 
 
 Mellow. — Timber is mellow when it is thoroughly dry and slightly aged. 
 
 Melting. — The fusion of solids effected by the application of heat. The 
 melting of metals is carried on in cupolas, in reverberatory furnaces, 
 and in crucibles. The distinction between melting and smelting is, 
 that the former applies to the fusion of metals which have been pre- 
 viously reduced firom their ores, the latter signifies the reduction and 
 melting down from their ores. 
 
 Melting Down Refinery. — The usual form of refinery (q.v.) in which the 
 charge consists of selected pig and scrap, as opposed to a running in 
 refinery (q.v.). 
 
 Melting Furnace. — See Blast iFumace, Reverberatory !Fumaoe, Cupola, 
 &o. 
 
 Melting Holes. — The chambers which receive the crucibles containing 
 crucible cast steel (q.v.). 
 
 Melting House. — That department of a steel works devoted to the 
 melting of cast steel. 
 
 Melting Point. — See Fusing Point.. 
 
 Member. — ^Any separate piece or unit portion of a structure is termed a 
 member thereof. 
 
 Mendiug-np, or MaMng-up. — The repairing of the broken edges of a foun- 
 der's mould which have become damaged by the withdrawal of the 
 pattern. It is done by laying a strip of wood of the proper outline 
 against the broken edge, and ramming sand against it. 
 
 Mendiug-np Piece, or Making-np Piece. — The strip of wood, plain or 
 curved, as the case may be, which is used for mending-up (q.v.) . Some- 
 times a strip of lead is bent round a curved edge instead of a sweep 
 cut out in wood. 
 
 Mensuration. — The measurement of siufaces, or of solid contents. 
 
 Merchant Iron. — Finished bar iron of various sections. 
 
 Merchant Mill. — The entire plant of roUs and accessories used for the 
 making of tee, angle, and bar iron of various sections. 
 
 Merchant Kolls.— See Mm KoUs. 
 
 Merchant Train. — ^A train of roUs which reduces puddled bars to their 
 finished sections and sizes ready for the market. 
 
J24 DICTIONARY OF TERMS USED IN 
 
 Mercurial Gauge. — ^A form of pressure gauge muoli used on steam 
 boflers before the introduction of Bourdon's spring gauge. It con- 
 sisted of a suction tube partly filled witli mercury, open to the air in 
 the longer limb and in communication with the boiler in the shorter 
 lunb. The mercury in the longer limb sustained a float from which 
 a wire passed over a pulley and downwards to an index finger which 
 pointed to the dirisions upon a scale. The height of the float varying 
 with the pressure caused the position of the finger to indicate the 
 amount of pressure. In high-pressure boilers the construction was 
 modified to avoid the inconvenience of a long tube. A hole closed at 
 the top and opening into the mercury at the lower end was used, and 
 the amount of compression of the air in the tube according to Boyle 
 and Harriot's law (q.v.) furnished the means of deducing the pressures. 
 Mercury.— Symbol Hg. Comb, weight 199.8. Sp. gr. at 0° 13-596. The 
 only metal liquid at ordinary temperatures freezing at— 40°!'. The 
 pressure of steam is often estimated iu inches of mercury. Used in 
 barometers and thermometers and in mercurial gauges. 
 Mesh. — The size of the openings in the grating of an air-pump, or of a 
 
 Kingston valve, or of a moulder's sieve. 
 Meshed. — Used sometimes with the same signification as in gear (q.v.). 
 Metal. — Metals are elementary bodies. Those used in engineering are 
 iron, copper, tin, lead, zinc, manganese, each described under its 
 proper heading. 
 Metal Hollows. — Hollows made of metal and used by pattern-makers for 
 the same purpose as those made of leather (see Leather Hollows). To 
 enable the metal to bend with facility, the flat or back portions of the 
 hoUow are grooved out longitudinally. 
 Metallic Packing. — A kind of packing used for stufBng boxes (q.v.), 
 
 formed of woven wire. 
 Metal Patterns. — Foundry patterns are made of metal when too weak to 
 stand foundry usage if made in wood, or when curves have to be imparted 
 thereto which could not well be given to wood. Hence all ornamental 
 works are made in metal, and all works where a large number, say several 
 scores or hundreds, have to be cast from the same pattern.. Iron, brass, 
 tin, and lead, are the metals chiefly used ; iron and brass beiag employed 
 for permanent work, while lead and tin are used chiefly to be bent into 
 various outlines, from which the actual permanent patterns in the harder 
 metals are finally moulded. Patterns in iron are rusted and varnished, or 
 protected with a coating of beeswax. 
 Metallurgy. — The processes by which metals are separated from their ores, 
 
 and combined to form alloys. 
 Metal Saw. — See Hack Saw, Hot Iron Saw. 
 
 Metal Spinning. — The process by which light articles in the malleable 
 metals are made to assume circular and moulded shapes by means of 
 pressure applied to them while in rapid rotation in the lathe. 
 Meteoric Iron. — This is of interest as being the only state in which iron is 
 found in a nearly pure condition in nature. It is of extra mundane 
 origin but is of no commercial value. 
 
 Method of Moments Signifles the calculation of the bending strains in 
 
 a structure, by estimating the moments of the forces acting thereon, 
 as distinguished from the graphic methods (q.v.). 
 Methylated Spirit. — See Spirits. 
 
 Metre. — The French unit of length, containing 39-37079 English inches. 
 It is divided into a thousand equal parts termed millimetres. A square 
 
MECHANICAL ENGINEERING. 225 
 
 metre is equal to 1-196 square yards or 10'764 square feet. A cubic 
 metre is equal to 1-308 cubic yards or 35-3156 cubic feet. 
 
 Metre Sule. — A rule divided into fractions derived from the metre (q.v.). 
 These are sometimes made a metre long, but sometimes the millimetre 
 divisions are put on an ordinary two feet or one foot English rule. 
 Both wood and steel are used in their construction. 
 
 Metre Scale. — A scale (q.v.) used for dxawiiig purposes, in vrMch the metre 
 (q.v.) is the unit and millimetres (q.v.) the subdivisions. It may be 
 twelve inches, or it may be one metre long. Usually the subdivisions of 
 the inch and the metre are placed side by side for comparison. 
 
 Metric System. — The !French system of weights and measures, of which 
 the unit is the metre, origiaally supposed to be the 1-10, 000, 000th part 
 of a meridian of the earii. The metric system is purely decimal, hence 
 its value. 
 
 Mica. — ^Plates of mica are inserted in the sight holes of cupolas in order 
 that the furnace man may see the progress of the melting of the charge. 
 
 Micrometer Caliper. — A small caliper Tised in workshops for the best 
 classes of work, and constructed on the same principle as Whitworth's 
 measuring machine. It consists of a horseshoe-shaped piece, into 
 one end of which a traversing mandrel is screwed. The mandrel 
 is provided with a fine threaded screw having a definite number of 
 threads to the inch, and its head is graduated into an equal number of 
 divisions. By advancing the screw through a portion of a revolution 
 as indicated by the divisions on the head, the fractional portion of an 
 inch can be gauged with aoouraoy. 
 
 Middle Cut File. — A Lancashire File having a degree of coarseness 
 midway between a rough and bastard cut (q.v.). It is seldom used. 
 
 Middle Flat Gouge. — Any gouge whose amount of curvature is neither 
 very flat on the one hand nor quick on the other. 
 
 Middle Part. — The central portion of a three-parted moulding box. 
 Sometimes the central portion of the mould. 
 
 Mid Feather Wall. — The brick wall which divides the two flues in a 
 wheel draught (q.v.), so called because it is in the centre of the boiler, 
 and is very thin where the boiler rests upon it, or about three or four 
 inches in width. 
 
 Mid Gear. — The Knk motion of an engine is said to be in mid gear when 
 the arrangement is such that neither backward nor forward motion is 
 possible. Engines at rest should always be placed in mid gear. 
 
 Mil. — The thousandth part of an inch. A term used to denote the sizes of 
 ■wire gauges, the diameters being given as so many mils. The term is 
 behoved to have been first employed by Mr. Cocker of Liverpool, who 
 attempted to introduce a new wire gauge. 
 
 Mild Centred Steel, or Soft Centred Steel, — Steel whose central portions 
 are softer than the exterior. It is first brought into the form of rods, 
 &c., only partially earburised in the cementation process oarburisation 
 being arrested at a definite stage. Used sometimes for engineers' taps 
 where hardness without excessive brittleness is desirable. 
 
 Mild Steel, — Steel which contains a very low percentage of carbon, 
 approximating therefore to the condition of -wrought iron. It may 
 contain from -05 to -20 per cent, of carbon. It welds but does not 
 temper, and is suitable for boilers, ships' plates, rivets, and -wire. 
 
 Mill. — A term of general application. A building with its machinery ; a 
 boring machine ; a blacking mill, or a revol-ving blacking grinder ; a 
 rolling mill, or a forge mill for bar iron manufacture, &o. 
 
 4 
 
=26 DICTIONARY OF TERMS USED IN 
 
 Mill Bar. — Bax iron rougt from the puddler's roUs, as distinguished 
 from merchant bar (q.v.). 
 
 Milled Head. — The circular head of a pinching, or set, or adjustment 
 screw, -whose edge is cut into a succession of ridges to enable the fingers 
 to grasp it without sUppiug. 
 
 Mill Furnace. — A reheating furnace (<1-T.). 
 
 Mill Gearing. — Deriving its name from the old corn-mills, and compris- 
 ing the work of the millwright, embraces cog wheels, pulleys, shaft 
 bearings, and belting. 
 
 Millier. — The French metric ton, containing one million grammes (q.v.), 
 or a thousand kilogrammes, and equivalent to 2204-6212 English, 
 pounds, or 19-6841 hundredweights, or -9842 of an EngUsh ton. 
 
 Milligramme. — A French measure of weight, being the one-tiiousandth 
 part of a gramme (q.v.). It is equivalent to -0154 part of an English 
 grain. 
 
 Millimetre. — A French measure of length, being the thousandth part 
 (-001) of a metre (q.v.), and being the •03937 of an English inch. 
 
 Millimetre Drills. — Drills whose diameters are made to I^euch millimetre 
 dimensions instead of to English eighths of an inch. 
 
 Millimetre Pitches. — Screw pitches whose unit is the millimetre. These, 
 when required, are commonly out on lathes having English leading 
 screws, by a proper arrangement of change wheels. Thus, the metre 
 equals 39-375 or 39f inches. A pitch of one millimetre equals 
 therefore 1000 threads in 39| inches. In the same length of lead- 
 ing screw having four threads to the inch, we have 39| X 4 = 157^, 
 or 157-6 threads of ^ "pitch;" hence the ratio subsisting between 
 
 157-5 
 the two is .-j-j- , which reduced to its lowest denomination equals 
 
 rjjjjjT -r 2-5 = Tgg- For a lathe having a leading screw of f pitch 
 
 the ratio would he^Trrj, for one of J pitch ^^. To deduce the wheels 
 
 we multiply the numerator by the pitch of the thread, and then pro- 
 ceed as with ordinary change wheels. Thus, to cut a thread of 10 mm. 
 pitch, and having a leading screw of four to the inch, the equation would 
 
 i , 63 X 10 _ 630 ,, . . , ,.. , 63 X 10 ^ ^ ^ 
 
 stand — jQp — ;jpQ, breakmg up mto multiples ^q ^ ^^ ; but to 
 
 CO w Q A 
 
 obtain wheels in the set we substitute 00 v 60 ' ^""^ ^'^ ^ ^^ ^'^ ^ 
 drivers, and 20 X 60 the driven wheels. 
 
 Millimetre Rule. — See Metre Eule. 
 
 Milling. — The shaping of metals by means of slowly revolving tools or 
 milling cutters (q.v.). Surface contour can be more rapidly and accu- 
 rately effected by milling than by the ordinary operations of planing 
 and shaping -with the single-edged cutting tools, and the practice of 
 milling is constantly increasing in economical importance in the work- 
 shops. 
 
 Milling Cutters. — ^Discs or circular cutters made of steel and serrated 
 around their edges to an exact counterpart of the sectional shape which 
 they are intended to produce. Work of nearly any form and temper is 
 capable of being figured -with milling cutters. They can be used in the 
 lathe, but commonly they are fixed in a milling machine (q.v.). 
 
 Milling Machine. — A machine in which metal work is reduced to shape 
 
MECHANICAL ENGINEERING. 227 
 
 when attaolied to a table and passed under a rotating serrated 
 cutter. Both plain and irregular surfaces can be thus shaped, and 
 the -value of the machine consists in the uniformity of outline which 
 can be imparted to numerous similar parts. Nut faces, the flutes of 
 taps and reamers, and similar repetition works in iron, steel, and 
 braas, are done in milling machines. 
 
 Milling Tool.— See MiUing Wheel. 
 
 Hilling Wheel, or Milling Tool. — A small wheel running loosely on a pin 
 set in the cleft end of a bar of iron, and used for roughing or milling 
 heads of screws. The edge of the wheel is made into a counterpart of the 
 pattern which it is intended to produce, and the pattern is formed by 
 pressing the "wheel with sufficient force against the revolving work 
 to cause the wheel also to revolve, and so impress its pattern upon 
 the work. The wheel itself is cut by pressing it against a hob set 
 slowly revolving in the lathe. This of course precedes hardening. 
 
 Mill Pick, or Mill Bill. — A tool like a double wedge mounted in a short 
 handle and used to dress the faces of millstones. 
 
 Mill Sace. — The narrow space between the floats of an undershot water 
 wheel (q.v.) and the masonry within which the water is confined. 
 
 Mill EoUs, or Merchant EoUs, or Mill Train. — The merchant roUs of a 
 rolling mill. They are employed for the production of finished iron 
 from the puddled bar after it has been cropped, piled, and balled or 
 reheated. They are similar in the main to the puddle rolls, but differ 
 in some matters of detail. They consist of sets of roughing or biUeting, 
 and finishing rolls, and are either two high, or three high. 
 
 Mill Scale. — See Hammer Scale. 
 
 Mill TaU.— See Tail "Water. 
 
 MiU Train.— See MUl BoUs. 
 
 Millwright. — A workman of a class whose numbers are diminishing 
 owing to the increasing specialisation of engineers' work. The occu- 
 pation of the millwright originated in the development of com and 
 other mills driven by water power, at a period when modem engines 
 and machinery were unknown, and when the factory system had not 
 arisen. Owing to these conditions and the exigencies of circumstances, 
 the millwright was compelled to perform all the various tasks which 
 are now included under the head of engineering, and which are divided 
 into several distinct departments, embracing the working both in wood 
 and metal. 
 
 Mine. — Ore (q.v.). 
 
 Mine Tin. — Txn ore obtained by mining as distinguished from stream tin 
 (q.v.). It is found in veins in quartz, granite, and clay slate, 
 associated with arsenical and copper pyrites, specular iron ore, and 
 wolfram. 
 
 Mineral Oils. — These are used for lubrication and in the furnaces of steam 
 boDers. Mineral oils when used for lubrication do not generate 
 injurious acids like the animal oUs. They are manufactured from 
 bituminous shale, or are imported from America or from Russia, from 
 petroleum springs. They are subjected to filtration or to distUlation, 
 to free them from grit, tar, and volatile oil, and are used both pure 
 and as compound oils (q.v.). 
 
 Minium. — Ked Lead (q.v.). 
 
 Minor Axis. — See Conjugate Axis. 
 
 Minus Lap. — ^A term applied sometimes to the internal or exhaust lead on a 
 Bteam valve. It is flie lead to exhaust, diminishing the amount of 
 
228 DICTIONARY OF TERMS USED IN 
 
 cusHoning, and is used with very quick mrming engines where smooth- 
 ness of working is essential. See Inside Lead, 
 
 Uiter. — A frequent way of spelling mitre (q.v.), as miter wheel, miter 
 board, &o. 
 
 Mitis Castings. — See "Wrought-iron Castins^s. 
 
 Mitre. — Lines meeting at an angle of 45° with each other form a mitre. 
 
 Uitre Board. — A board used by wood workers for cutting mitred joints. 
 Blocks are screwed on a plain board at angles of 45° with its edge, 
 and form a guide for the plane, which is laid upon its side as in 
 shooting, or sometimes for the saw, though the latter is more commonly 
 used with the mitre box (q.v.). 
 
 Mitre Box, or Mitre Block. — A templet or guide for sawing mitre joints. 
 It has a bottom and two sides, and two saw kerfs opposed to each other 
 at an angle of 90°, cutting the sides therefore at angles of 45°. 
 
 Mitre Iron. — Bar iron of angular section. 
 
 Mitre Joint. — A butt joint whose ends are cut at an angle of 45°, the 
 abutting sides therefore forming an angle of 90°. 
 
 Mitre Valve. — The mitre of a safety valve signifies the annular seating, 
 turned to an angle of 45° in section, upon which the valve itself rests. 
 
 Mitre Wheel. — ^A bevel wheel whose pitch cone is placed at an exact 
 angle of 45° with its axis. Hence pairs of mitre wheels working 
 together are always of equal diameter, pitch, and number of teeth, and 
 connect shafts which stand at right angles with each other. 
 
 Mixed Gauge. — See Gauge. 
 
 Mixed Oils. — See Compound Oils. 
 
 Mixing Chamber. — A chamber at the end of the cylinder of a gas engine, 
 in which the gas and air become mingled previous to ignition. 
 
 Model. — A pattern is sometimes, though incorrectly, termed a model. A 
 model is really a counterpart or copy upon a small scale of a piece of 
 mechanism. The object of making a model is either to give a good 
 idea in due proportion of a large and expensive piece of work, or as a 
 work of art and beauty, or, as in a worMng model, to test the prac- 
 ticability or utility of an untried design. 
 
 Modulus. — A constant multiplier or coefficient employed in mechanical 
 calculation. It expresses the ratio of the effective value of a machine 
 as compared with its theoretical value, or the difference between the 
 work expended and that given out, the loss being due to friction chiefly. 
 
 Modulus of Elasticity. — A ratio of stress and strain. The weight in 
 pounds required to stretch a bar 1 in. square of a given material to 
 double its length is the modulus of direct elasticity for that bar. 
 
 Modulus of Eesistauce. — Equivalent to the modulus of rupture, or to a 
 lesser quantity, as the modulus of elastic resistance. 
 
 Modulus of Rupture. — A constant number which represents the weight 
 necessary to break a bar of any given material of definite length, 
 breadth, and depth, and used in calculating the strength of similar 
 bars differing therefrom in dimensions only. 
 
 Moment. — The measure of the importance of a physical agency or of a 
 force. Thus the moment of a lever is equivalent to the power turning 
 its arm around the fulcrum, in other words expresses its effect or 
 result. See Moment of Inertia ; Force, Moment of. 
 
 Moment of Inertia. — The sum of the products of each particle of a 
 moving body multiplied into the squares of the distances of the particles 
 from their neutral axis. It is represented by the letter I. If the mass 
 of every particle of a body he multiplied by the square of its distance 
 
MECHANICAL ENGINEERING. ZK) 
 
 from a straight line, the sum of the products so obtained is called the 
 moment of inertia of the system about that line, which is also called the 
 axis. The moment of inertia for any cross section is found by dividing 
 the total area into separate small layers or areas, and multiplying the 
 area of each element so obtained by the square of its distance from the 
 horizontal axis taken through the centre of gravity, and then adding 
 the products together. 
 
 Moment of Eesistance. — When a bar is subject to bending, the internal 
 stresses set up therein by the bending action constitute a mechanical 
 couple. The amount or moment of those stresses is equal and opposite 
 to the bending moment. This is termed the moment of resistance for 
 that particular section. 
 
 Moment of Rupture. — The moment of resistance at fracture. 
 
 Moments, Equality of. — See Equality of Moments. 
 
 Momentum. — The mass of a body multiplied by the velocity imparted 
 thereto, equals the momentum. The velocity may remain constant 
 and the mass vary, or the mass may remain constant and the velocity 
 vary. 
 
 Monkey, or Bam. — (1) The longitudinal weight which is made to fall on 
 the heads of piles when being driven into the soil. See PUe Driver. 
 (2) A jumper (q.v.). 
 
 Monkey Wheel. — See Grin Block. 
 
 Monkey Wrench. — A screw wrench (q.v.). 
 
 Monkbridge Iron. — Plates manufactured by the Monkbridge Company, 
 and held in high estimation for boiler work. 
 
 Mortar Mill, or Mortar Mixer. — A machine used for mixing mortar. It 
 consists essentially of a shallow cast-iron pan with two revolving 
 chilled wheels driven by bevel gearing from an engine. A false or 
 movable bottom of loose plates is provided in order that they may be 
 renewed when they are worn out. 
 
 Mortice. — A recess cut in a piece of timber which, with its corresponding 
 tenon, forms a joint used in timber work. 
 
 Mortice Chisel. — A stout wood-worker's chisel driven with the mallet, and 
 used for cutting mortices where percussion and leverage are rendered 
 necessary. 
 
 Mortice Gauge. — A gauge used for marking the thicknesses of mortices and 
 tenons. It consists of a stem and head similar in outline to those of an 
 ordinary gauge, but the stem is famished with two marking cutters, 
 one fixed, the other movable, which can be set to equal the thickness 
 of any mortice. Hence both edges of the mortice or tenon are marked 
 at one time, and the head being movable permits of the marking off of 
 a tenon from any distance inwards from the edge of the stuff. 
 
 Mortice Wheel. — A wheel in which wooden cogs are used instead of iron 
 teeth. The rim is pierced with as many mortices as there are cogs, and 
 the cogs are fitted into these mortices with corresponding shanks, the 
 long grain running radially towards the centre of the wheel. The cogs 
 are thicker and shorter than those of ordinary wheels, and the teeth 
 of the iron wheel into which they work are correspondingly thinner. 
 There is no flank clearance allowed as in ordinary gearing. 
 
 Morticing Machine. — A machine for cutting mortices in wood, either by 
 means of a chisel, or by a circular cutting bit. When the latter is used 
 the end is either left rounding or made square afterwards by a chisel. 
 The earlier morticing machines had a positive stroke, that is, a dead 
 thrust from the beginning, which strained the chisels. Now they are 
 
230 DICTIONARY OF TERMS USED IN 
 
 made -witli an adjustable stroke wtose force is increased gradually by 
 means of a system of leversi. 
 
 Motion. — See Laws of Motion. 
 
 Motion Bars. — The guide baisof an engine cross head. See Slide Bars. 
 
 Motion Block. — A cross head (q.T.). See SKde Blocks. 
 
 Motion Disc. — See "Wrist Plate. 
 
 Motion Work. — A term applied to the various rods, levers, and links 
 connected with an engine slide valve. 
 
 Motive Power. — The particular source of energy which is applied to 
 actuate a prime mover or a machine. Hence motive power may be 
 animal, steam, water, air, or gas. 
 
 Motor. — A prime mover (qv.). 
 
 Mottled Iron. — A quahty of cast iron intermediate between the grey and 
 the white varieties, both in point of texture, crystallisation, and the 
 state in which its carbon occurs, a portion being in the combined and a 
 portion also being in the imcombined or graphitic state. 
 
 Mould. — The hollow matrix or enclosed space into which metal is poured 
 to form a casting. A mould is, its cores excepted, a counterpart of its 
 pattern (q.v.). Moulds are made in green or in dry sand. 
 
 Moulder. — An ironfounder. His work consists in moulding the reverse 
 impressions of castings in sand, the impressions being obtained by 
 ranuning the sand around patterns of wood or other materials, which 
 are so constructed as to withdraw therefrom without doing injury to 
 the mould itself. Due regard must be paid to venting, to allow free 
 egress to the hberated gases, and the metal must be selected and mixed 
 as most suitable for the special class of work for which it is to be 
 employed. 
 
 Moulder's Baskets. — Hand baskets made in the form of trays ; used in 
 foundries for carrying about small quantities of coke, coal, and other 
 materials. They are made of cane or of wire. 
 
 Moulder's Bellows. — See Bellows. 
 
 Moulder's Lamp. — A cast-iron lamp whose vertical section is that of a 
 truncated cone, and burning paraffin or benzoline. Used by moulders 
 for throwing hght into the interior portions of moulds. Candles were 
 formerly used, but have been superseded by the lamps. 
 
 Moulder's Mallets. — See Rapping Mallets. 
 
 Moulder's Nails. — See Pipe Nails. 
 
 Moulding. — The making of moulds in sand, or loam, or plaster of Paris, 
 with or without the aid of patterns. When patterns are used they are 
 enclosed in sand rammed around them, from which they are subse- 
 quently withdrawn. When moulding is done without patterns the 
 necessary shape is imparted to the mould by means of loam boards or 
 strickles. Moulding is done either in green or in dry sand, or in loam. 
 The moulding of work was formerly more frequently called founding. 
 
 Moulding Board. — A bottom board (q.v.). 
 
 Moulding Box. — A flask (q.v.). 
 
 Moulding Cutter. — An adjustable steel cutter for woodworking, having 
 its edge ground and sharpened to the shape of the moulded edge which 
 it has to form. These cutters are usually fixed in pairs on opposite sides 
 of a disc, which is set to run with a spindle revolving over the wood 
 to bo operated on. The cutters travel at a rate of from 4,000 to 6,000 
 feet per minute. 
 
 Moulding Letters. — Pattern letters (q.v.). 
 
 Moulding Machine. — A machine en-ployed for moulding patterns in a 
 
MECHANICAL ENGINEERING. 231 
 
 partially automatic maimer, the aim teing to produce moulds of pre- 
 cisely tlie same shape, aud with flush joints, i.e. joints showing no lap. 
 The patterns are usually made of metal, laid upon a table horizontally, 
 and, according to the type of the machine tised, the moulding box is 
 rammed up over it by hand or by some kind of special mechanism. The 
 plate is then usually turned over, and the bos released aud dropped 
 downwards, being in this respect the reverse of ordinary moulding, 
 where the pattern is lifted away from the box. Usually, also, there is 
 no complete pattern, but divided patterns are put on separate plates, 
 or on opposite sides of the same plate, the moulds made separately and 
 only brought together for casting. 
 
 Honlding Sand. — Foundry sand (q.v.). But strictly speaMng moulding 
 sand designates the black sand which accumulates on the floor of the 
 foundry from repeated castings, and which is only used for box filling 
 ■ and for the rougher class of work. 
 
 Moulding Tub. — A wooden tub of oblong form and with sloping sides, 
 containing moulding sand, and provided with a shding cover. It is 
 used by brass and iron moulders who do hght work, the flask lying on 
 the cover and the tub supplying the necessary sand ; the moulder 
 therefore stands instead of kneeling at his work. 
 
 Mounted Tracing. — See Tracing. 
 
 Mounting. — The chucking of work in the lathe. 
 
 Mountings. — Commonly signifies the brass and ornamental work about 
 an engine, or boiler, or machine, but more especially applied to boiler 
 mountings (q.v.) . 
 
 Mouth. — Tie opening or orifice of a pipe, or furnace, or ladle, or similar 
 cylindrical or hollow vessels. 
 
 Mouthpiece. — (1) An attachment fitted to the mouth (q.v.) of a vessel, 
 pipe, or tank. A door often covers the mouthpiece. (2) A bridge of 
 wood let into the mouth of a plane to reduce the width caused by the 
 wearing back of the iron, and of the face of the wooden stock. 
 
 Movable Expansion. — Expansion which is capable of regulation by 
 means of a second elide valve, or other gear. 
 
 Movable Points. — (1) The movable centres of the rods in parallel motions 
 (q.v.). (2) The various legs, pens, pencil, and points which are sub- 
 stituted for each other in the compass (q.v.) used for drawing. 
 
 Movable Pulley. — A pulley whose axis is movable in space. 
 
 Moving Weight. — See Boiling Load. 
 
 M Teeth. — Saw teeth shaped like the letter |V| . Used in some cross-cut 
 saws (q.v.). 
 
 Mud Box. — A box placed in the suction pipe of a bilge pump (q.v.), to 
 arrest dirt or foreign matters which would otherwise lodge in the 
 valves. It is a cast-iron box fitted with a removable cover and con- 
 taining a perforated plate or diaphragm placed transversely therein. 
 
 Mud Bucket. — A dredger bucket or scoop constructed of cast or sheet 
 iron, or steel, and used for the purpose of bringing up the mud from 
 the bed of a stream or harbour. 
 
 Mud Hole, or Mud. — An oval opening in the lower part of a boiler, 
 through which the sediment deposited by the water is extracted. Most 
 boilers have several naud holes, two or three near, or in the bottom, aud 
 one or two opposite every cross tube. They are closed by doors while 
 the boiler is working. See lilud Hole Door. 
 
 Mud Hole Door, or Mud Lid. — A door or cover which closes the mud 
 hole (q.v.) of a Bteam boiler when the boiler is in use. It is oval in 
 
232 DICTIONARY OF TERMS USED IN 
 
 outline, and ia inserted within the hole and pulled up against its irnie* 
 face by means of a holt. The bolt is riveted into the door and passes 
 thence through a bridge spanning the mud hole ■without, and is 
 tightened against it with an ordinary nut. 
 
 Mud lid.— See Mud Hole Door. 
 
 Mud. — A mud hole (q.T.). 
 
 Muff Coupling. — See Bos Conpluig. 
 
 Muffle. — A small arched vessel of fire-clay, shaped like an oven and used 
 in the assaying of aUoys of metals, the muffle being used to protect the 
 metal from, the direct action of the flame. 
 
 Multiple Boiler. — A multitubular boiler (q.v.). 
 
 Multiple Boring Machine. — ^A boring machine provided with three or 
 more mandrels for simultaneous boring. 
 
 Multiple Drilling Machine. — A machine in which a number of drill 
 spindles are arranged parallel to each other, and driven simultaneously. 
 They are used in boiler and girder work where a large number of holes 
 of the same size and pitch are required. 
 
 Multiple Gear. — The combination of several pinions and several wheels 
 in train for the increase of mechanical effect. The product of all the 
 wheels divided by the product of all the pinions represents the 
 mechanical gain. 
 
 Multiple Threaded Screw. — A screw containing several heHces winding 
 around its body. Used to impart more rapid motion than could be 
 obtained by one only. The various threads are parallel with each 
 other, and of equal pitch. A worm wheel is an illustration of a mul- 
 tiple threaded screw, the number of teeth being equivalent to so many 
 thread sections. 
 
 Multiplier. — Wien the cubic measurement of a body in any given 
 material is known, its weight is readily deduced therefrom by multi- 
 plying the measurement by a constant number termed its multiplier. 
 Thus cubic inches of cast iron multiplied by -263, of wrought iron by 
 •28, of gun metal by -3, of steel by -28 give pounds avoirdupois. 
 
 Multitubular Boiler. — A boiler traversed with numerous tubes through 
 which the hot gases pass from the fire-box on their way to the chimney, 
 causing circulation and raising the temperature of the water in the 
 boiler during their progress. The tubes are of brass or iron fitting into 
 the tube plates of the fire and smoke boxes. Multitubular boilers are 
 chiefly confined to those of the locomotive and portable and horizontal 
 types, very few vertical boilers being provided with tubes of this 
 character. 
 
 Muntz Metal. — ^Au alloy of copper and zinc in the proportion of 60 of 
 copper to 40 of zinc. It is strong, and largely used in engineering 
 construction in the form of sheets and rods, and for the tubes of loco- 
 motives and of condensers. 
 
 Mushroom Valve. — See Lift Valve. 
 
 Myriagramme. — A Prench measure of weight containing ten thousand 
 grammes (q.v.) and equivalent to 22'0462 English pounds. 
 
 Myriametre. — Ten thousand Prenoh metres (q.v.) corresponding with 
 393,707-9 English inches. 
 
MECHANICAL ENGINEERING. 233 
 
 Nail. — A strip of pointed taetal provided -with a liead. Used for driving 
 into timber. See Clasp NaU. 
 
 Nailing. — See Sprigging. 
 
 Name Plate. — The casting -wHoh tears the name of the manufacturers 
 on a piece of work. The pattern is commonly made by casting the 
 letters separately in lead or tin and cementing or tacking them upon 
 their pattern plate of wood. 
 
 Napier's Compasses. — ^A drawing compass which is constructed with 
 folding legs to be carried in the pocket. The working points are 
 pivoted to the main legs, and are double ended and reversible on their 
 pivots. One pivot leg carries a point and pencil at opposite ends, the 
 other a point and a pen, so that two points, or a point and a pencil, or 
 a point and a pen can be used at pleasure. 
 
 Naphtha. — ^A comparatively thin and pure rock oil, closely allied to petro- 
 leum, which is sometimes used as a solvent for shellac in the making of 
 varnish for foundry patterns. Methylated spirit is mostly used in 
 preference. 
 
 Narrow Gauge. — Four feet eight and a-haU inches between rails, adopted 
 by Stephenson from the Northumbrian coal tramways. 
 
 Native Copper. — Copper which is mined in the metallic state. It occurs 
 in the district of Lake Superior, and is highly esteemed on account of 
 its purity, which renders it suitable for electrical purposes. 
 
 Natural Draught. — See Draught. 
 
 Nature. — By the nature of a material is understood the average excel- 
 lence of its qualities when unaffected by deteriorating influences. 
 
 Nave. — The boss of a wheel. 
 
 Neck. — (1) The narrowest portion of the passage in vena contracta (q.v.). 
 (2) An entire journal is often called a neck. 
 
 Neck Biug. — The bush for the rod which is fitted into an engine cylinder 
 or steam chest below the stuffing box, to insure durability of wear. 
 
 Needle Lubricator. — A pear-shaped or globular glass vessel containing 
 oil, and furnished with a neck which is placed lowermost. A wire 
 passes loosely through the plug which closes the mouth, and by its 
 vibration and capillary action conducts the oil down to the bearing. 
 
 Needle Wire. — A vent wire (q.v.) of the smallest size or about ^ in. 
 in diameter. 
 
 Negative Slip. — Is applied to the speed of a ship's screw when the velocity 
 of the vessel is greater than it should be according to the theoretical 
 calculation based on the hypothesis that the screw works in an unyield- 
 ing body. It is due probably to the vis viva of the current which 
 follows the vessel's wake. 
 
 Negative Stresses, — In English practice are those which represent tension. 
 
 Negative Terms. — Algebraical or arithmetical terms preceded by the 
 sign — . 
 
 Nest Gearing. — Gearing enclosed in a case or box, as in a capstan head, 
 and in some forms of hoisting tackle. 
 
 Nett Indicated Horse-Power. — See Actual Horse-Power. 
 
 Neutral Axis, or Neutral Line. — When a beam is subjected to flexure, 
 there is a longitudinal central line which is neither in compression nor 
 extension, and is therefore subject to no straining action. The part 
 
234 DICTIONARY OF TERMS USED IN 
 
 ■where this line cuts any particular section is termed the neutral axis of 
 the beam. Since also the tensile and compressive forces diminish aa 
 the neutral axis is approached, girders and girder-like structures are 
 frequently lightened out in their central portions. In a heam of 
 uniform section the neutral line corresponds with the central hue of the 
 cross section. In beams of other sections it "mil be the mean of the 
 bending sections. 
 
 Neutral Equilibrium, or Indifferent Equilibrium. — This results -when the 
 centre of gravity of a body which is in equilibrium is in the central 
 portion of the body, and cannot therefore arise into a higher or descend 
 into a lower position. A sphere is always iu neutral equilibrium. 
 
 Neutral Line. — See Neutral Axis. 
 
 Neutral Surface. — The plane of the neutral axis (q.v.). 
 
 Neutral Tint. — A purplish grey colour used to distiuguish cast iron iu 
 sectional drawings. 
 
 New Sand. — Mixtures of foundry sands used for facing moulds. See 
 Facing Sand, Old Sand, Sands. 
 
 Nickel. — Symbol, M. Comb, weight, 58'6. Sp. gr. 8'8. A silvery 
 white metallic element found iu the ore called kupfemickel. Used 
 largely for electro-plating the bright portions of the best machinery. 
 
 Nicker. — The vertical cutter or lip on the circumference of a centre bit, 
 or of a Jennings bit, which outs into the wood the radius of the hole 
 to be bored. 
 
 Nicking. — The cutting of a shallow vee'd groove around or across a bar of 
 metal in order to ensure its fracture by a blow at that particular spot. 
 
 Nicking Fuller. — A tool similar to an ordinary fuller, or fullering tool 
 (q.v.), except that instead of being straight across in the direction of 
 its width it is hollowed, fulfilling the same purpose for round bars 
 that the ordinary fuller does for flat bars. 
 
 Nippers. — See Cuttkig Nippers. 
 
 Nipping Lever. — A lever which is so constructed and adjusted, that on 
 moving its longer arm around the fulcrum, the shorter arm on the 
 opposite side of the fulcrum bites or nips the periphery of a smooth 
 turned wheel ;. and the greater the pressure brought to bear upon the 
 lever the greater the nipping power. Moving the lever in the contrary 
 direction releases the bite immediately. This principle is employed in 
 the construction of what is known as the silent feed (q.v.). 
 
 Nipple. — A short connecting piece in a union which receives the nut at 
 one end, and screws into a socket at the other. Or a screwed stud piece 
 used for insertion into gas piping. 
 
 Nobbing. — The same as shingling (q.v.). 
 
 Nom. H.P. — Nominal horse-power (q.v.). 
 
 Nominal Horse Power. — A vague term which represents no particular 
 power of engine, but only manufacturers' advertised sizes. Formarine 
 engines, twenty circular inches of piston are sometimes taken as 
 equivalent to a nominal horse -power, and for non-condensing land 
 engines ten circular inches. The term is gradually falling into disuse 
 excepting as a standard for purchase, indicated horse-power (q.v.) 
 being used in preference. 
 Non-condensing Engine. — An engine which exhausts its steam directly 
 
 into the atmosphere. See High-pressure Engine. 
 Non-conducting Composition. — See Boiler Coating. 
 
 Non-conductors. — In engineering, various substances are employed as non- 
 conductors of heat. Felting is put around boilers and steam pipes, 
 
MECHANICAL ENGINEERING. 235 
 
 ■wooden handles are used for gauge glasses, and steam and hot water 
 
 cocks, &o. 
 Kormal. — The line -vrhioh falls perpendicularly to the tangent of a curve 
 
 at that particular point. The normals to the curves of wheel teeth 
 
 should always, if the teeth are properly constructed, fall on the varying 
 
 points of contact. 
 Kormal Pitch. — The pitch of a screw wheel taken, normal or perpen- 
 dicular to the directions of the teeth, as distinguished from, the 
 
 circumferential pitch (q.v.). In screw gears, gearing together, the 
 
 normal pitches must be equal. 
 Nose. — The front of a spindle, or generally any projecting part, as a 
 
 mandrel nose. 
 Hose Bit. — A shell bit (q.v.) which is provided with a nose or lip at tha 
 
 cutting point fo.' the withdrawal of the core from the wood. 
 Nose Helve. — See Helve Hammer. 
 Nowel. — A term sometimes used to designate the inner core of a loam or 
 
 other mould, but chiefiy when the mould happens to be a large one. 
 Nozzle. — (1) A contracted channel of; exit for effluent fiuids, by which 
 
 their velocity of efflux is increased. (2) Also the discharging end of any 
 
 tube, as that of a tuyere, for example. 
 Number One Iron. — See Puddled Bar. 
 Number Tvo Iron. — See Best. 
 Numerical Co-efB.cient. — See Co-efficients. 
 Nut. — The loose head which tightens a bolt, usually rectangidar or 
 
 hexagonal in form, though sometimes circular. 
 Nut Brown Colour. — The colour at which most turning tools for metal, 
 
 particularly for wrought iron, are tempered. It corresponds with a 
 
 temperature of about 540° F. 
 Nut Lock. — The means adopted for securing a nut in place so that it shall 
 
 not slacken back and become loose in consequence of vibration. There 
 
 are many such devices, as pins, wedges, set screws, keys, &c. 
 Nut Machine. — A machine for cutting and punching nut blanks. Nut 
 
 making is a specialty. General engineers buy their nut blanks and 
 
 washers cheaper than they can make them. 
 Nut Mandrel. — See Mandrel. 
 Nut Tapper.— A Bolt Cutter (q.v.). 
 Nut Wrench. — A spanner (q.v.) or a screw wrench (q.v.). 
 
 o. 
 
 ID. — The Greek letter Omega is used in mechanics to signify the angular 
 velocity (q.v.) of a body. 
 
 Oak. (Quercus.) — Sp. gr. -93. A hard, durable, very strong wood employed 
 for a vast number of purposes by engineers. It is especially valuable 
 in works which are exposed to the weather. There are several varieties, 
 Quercus peduneulata, or the stalk-pointed oak, and Quercus sessilijiora, or 
 cluster-pointed oak, being the European varieties. The latter is the 
 more straight-grained of the two, the former the more flexible. Quercus 
 rohur is the English oak, and is superior to any other. The red and 
 white oaks and the live oak come from North America. The ultimate 
 tenacity of English oak is about 15,000 lbs. per square inch of section, 
 
236 DICTIONARY OF TERMS USED IN 
 
 and a cubic foot -weighs 58 lbs. Oak charcoal is used for the black, 
 ing* (q.v.) of foundry moulds. 
 
 Oak Bark. — See Tannic Acid. 
 
 Oblique Area. — The area of the face of a propeller blade. See Scre-w 
 Area. 
 
 Oblique Joint Steam Chest. — See Divided Steam Chest. 
 
 Oblique Section. — ^A section (q.v.) taken obliquely or at an angle across 
 the drawing of an object. The precise direction of an oblique section 
 "would be indicated by a dotted line and reference letters. 
 
 Obliquity of Connecting Rod. — This signifies the angle made by the con- 
 necting rod of a steam engine when the crank pin is at the extreme 
 upper and lower portions of its path respectively. The effect of the 
 obliquity is to cause the shde valve to open the ports unequally at each 
 end, the port being closed and opened a little earlier at one end than 
 at the other. Por this reason the connecting rod is always made as 
 long as circumstances will permit of, in order to diminish the amount of 
 obliquity. 
 
 Obtuse Angle. — One which is greater than a right angle. 
 
 Obtuse Angles. — See Angle Irons. 
 
 Occlusion of Gases. — Red-hot metals allow of the passage of gases through 
 their substance ; the gases are then said to be occluded. Occlusion 
 plays an important part in the carburisation of iron. The exact method 
 by which this is effected is doubtful, but probably the carbonic oxide is 
 dissociated and deposits carbon in the pores. 
 
 Odd Pitch. — The pitch of a screw is said to be odd when it is either not 
 of the same pitch, or not some ahquot part of the pitch of the leading 
 screw of the lathe in which it is being cut. Thus with a leading screw 
 of two threads to the inch, three, or nine, or eleven threads would be 
 odd pitches. 
 
 Odontograph. — A scale invented by the late Professor WiHis of Cam- 
 bridge, to simpHfy the marking out of wheel teeth. Tables of appro- 
 priate numbers are given upon the scale for wheels of various pitches, 
 by which suitable radii for the teeth of those wheels are obtained, the 
 centres of the radii being given by the setting of the slant edge of the 
 scale against the radial hnes running from the centre of the wheel 
 through the pitch lines. 
 
 Oil Boats. — The receptacles for the waste oil at the ends of the bed slides 
 of planing machines. 
 
 Oil Can. — A tin or brass can containing the oil used for purposes of lubri- 
 cation. The best form of oil can is that in which the internal opening 
 to the spout is closed by a cover when not in use, and opened only by 
 the pressing down of a lever and spring. 
 
 Oil Cataract. — An oil cylinder (q.v.). 
 
 Oil Collector. — A vessel provided to catch superfluous oil from bearings, 
 either to prevent the soiling of adjacent parts or for re-utilisation. It 
 usually consists of a tray of some kind or another. 
 
 Oil Cup. — A recess or hollow formed in a casting for the reception of oil 
 used in lubrication. 
 
 Oil Cylinder, or Oil Cataract. — A small cyhnder used for controlling the 
 amount of movement of the piston in a steam reversing cylinder (q.v.). 
 The pressure of the oil agaiost the piston in the oil cylinder is regulated 
 by a cock. 
 
 Oiler. — An oU can (q.v.), or more specially an oil can of small size for 
 bench use. 
 
MS.CHAN1CAL ENGINEERING. 237 
 
 Oil Feed. — Any appliance by whioli oil is fed to a 'bearing. It may mean 
 either an oil can, or a Inbricator, or a copper tube leading from a 
 reservoir, or a wisp of cotton wick. 
 
 Oil Fuel. — In the form of a jet is used in some boiler fires. 
 
 Oil Grooves. — Small semicircular or nearly semicircular grooves cut in 
 the internal faces of brasses and on the sliding surfaces of machinery, 
 for the due distribution of the oil for lubricating purposes. The oil 
 grooves are cut diagonally across the bearing surfaces. 
 
 Oil Hardening. — The hardening of steel, effected by quenching it in oil 
 instead of in water. The effect of oil hardening is the less rapid 
 cooling of the steel, with a resulting greater elasticity and tensile 
 strength, and an absence of extreme hardness. 
 
 Oil Hole. — A hole drilled down to a bearing to form a channel for the oil 
 used for lubrication. Oil holes are countersunk at the top, the better 
 to receive and retain the oil, and are usually covered with a pivoted 
 disc when not in use, to keep dirt and dust from working into the 
 bearing. The difference between an oil hole and an oil cup or a 
 lubricator is, that the former conveys a temporary supply of oil to the 
 bearing, the latter holds a store in reserve, so that while the former 
 requires constant renewal, the latter is only supplied at long intervals. 
 
 Oiling. — See Lubrication. 
 
 Oil Pump. — A small force pump used to provide a constant and positive 
 supply of oil under pressure to a bearing, as being more reliable, and 
 therefore preferable to a lubricator, which acts by gravitation or by 
 displacement only. 
 
 Oil Reservoir. — A vessel which contains a supply of oil for lubrication. 
 It may be the chamber in an axle box, or in a displacement, or other 
 lubricator, or it may be a tray only which supplies the oil feeders or 
 oil pipes for the connecting and other rods in marine engines. 
 
 Oil Slip. — A thin bit of oil stone, whose edges are rounded in the trans- 
 verse direction. Used for abrading or fretting the hollow faces of the 
 various forms of gouges. 
 
 Oil Stone, or Hone. — A fine-grained natural stone, used for imparting 
 the final edge to cutting tools by abrasion, oil being used to assist in 
 the process. The principal oil stones, in their descending order of 
 merit, are, Turkey, Charnley Forest, Arkansas, Grecian, and Washita. 
 Oil stones are set in wooden stocks, and provided with covers to pro- 
 tect them from dust. They are used by wood workers, and also by 
 iron turners and fitters, for giving a fine edge to finishing tools and 
 scrapers. 
 
 Oil Tray.— See Oil Collector. 
 
 Oils. — The term oils is applied commonly to those fats which are liquid at 
 ordinary temperatures, while the term fats is reserved for those which 
 are solid at the same, notwithstanding that their essential chemical 
 composition is the same, belonging to the class of organic compounds 
 termed glycerides. Only the fixed oils concern the engineer ; the essen- 
 tial, ethereal, or volatile oils belonging to the perfumer's art. It may 
 be observed that the distinction denoted by the two terms is, that the 
 essential oils can be distilled without undergoing change, while the 
 fitxed oils cannot be distilled without undergoing decomposition ; hence 
 the reason of the statement that oils cannot be boiled, since at their 
 boiling points they cease to remain oils any longer. All the oils are 
 lighter than water, and derived from the animal, vegetable, and mineral 
 kmgdoms. Their chief use to the engineer consists in their qualities aa 
 
23? DICTIONARY OF TERMS USED IN 
 
 lubricants (q.T.)- ^^^ ^1^° Oils, Purity of, and tlie various Oils noted 
 under theii' special headings. 
 
 Oils, Purity of. — The purity of the oils used in lubrication is a matter of 
 importance, and when oils ostensibly pure are purchased, the task of 
 detecting adulteration is not difficult, since in the presence of certain 
 test agents there are reactions whioh indicate the freedom from adulte- 
 ration or otherwise of the oils subjected to the tests. 
 
 Old Sand. — The black sand which forms the floor of a foundry, consisting 
 of various mixtures of sands which have been used for casting in over 
 and over again for years. It alone is used in ordinary moulding work, 
 but for facing, new sands are used for ramming around the pattern 
 itself, to a thickness of an inch or two. See Facing Sand. 
 
 Olive Oil. — A common lubricant for machinery, used either alone or 
 with other oUs, G-aDipoli being considered the best. Being a vegetable 
 oil, and therefore containing resin, it is apt to gum. The flashing 
 point of G-aUipoli oil is 490' JP. 
 
 Oliver. — (1) The small lift hammer used by smiths, but which has nearly 
 disappeared since the introduction of the steam hammer. It consists 
 of a horizontal shaft pivoted on end bearings and carrying a hammer at 
 the end of its shaft. A cord passes from a treadle underneath to a 
 lever standing out from the horizontal shaft, and thence to a spring pole 
 overhead. The depression of the treadle therefore brings down the 
 hammer, and its release allows the spring pole to lift it again in readi- 
 ness for a fresh blow. (2) A pair of swage blocks held in their relative 
 positions one over the other by means of a spring handle. Sometimes 
 termed hoUiper. 
 
 Open Belt. — A driving belt (q.v.) which passes directly in one plane from 
 puUey to pulley. With an open belt the driving and driven pulleys 
 both revolve in the same direction. 
 
 Open Divided Scale. — A scale used for drawing purposes in which only the 
 end primary divisions are divided into fractional parts, leaving the central 
 ones open and clear without subdivisions. In reading ofE subdivisions 
 therefore the measurement is commenced in the body of the scale, and 
 the fractional portion is read off at one of the ends. 
 
 Open-end Rolls. — Mill roUs, free or unsupported with housings at one end. 
 Used for rolling rings, tyres, &o., which must be sHd on and off from 
 the end. 
 
 Open Frame Connecting Eod. — See Bow Connecting Rod. 
 
 Open Hearth. — Has reference to steel-making furnaces built on the rever- 
 beratory type, those being termed open hearth furnaces, and theii 
 methods of manufacture open hearth processes. 
 
 Opening Out. — Enlarging the diameter of a hole by means of a reamer or 
 broach. 
 
 Open Joint. — A term applied to the mode of jointing the broad-plated 
 portions of foundry patterns. Since patterns are enclosed frequently 
 for several hours in damp moulding sand, the moisture acting on the 
 wood causes it to expand, with the result in the case of wide stuff of 
 increasing its width, and if its width is confined by other timber 
 attached thereto, of producing curving. Wide plates are for this reason 
 jointed in narrow separate pieces, the edges of the joints remaining 
 about ^ of an inch open, so that local extension takes place without 
 affecting the outside dimensions to any appreciable extent. Conversely, 
 the malnng of open joints prevents the plate from curving or contract- 
 ing by the after drying of the stuff. Timber jointed thus is held 
 
MECHANICAL ENGINEERING. 239 
 
 together by cross strips or battens, or by some other portions of the 
 pattern. Tight-iitting dowels are often inserted to assist the jointing. 
 
 Open Link. — A slot link (q.v.) in which the slot for the slide block is per- 
 fectly plain, the block bearing upon the inside faces of the slot. The 
 term is used to distinguish it from the box link (q.v.). 
 
 Open Mouth. — A punch or puaiching bear is open-mouthed, when both 
 sides and, front are free for the insertion of the work, as distinguished 
 from close mouth (q.v.). Used more especially for the punching of 
 plates. 
 
 Open Pattern. — A skeleton pattern (q.v.). 
 
 Open Pig. — Pig-iron having a largely crystalline structure, this being a 
 characteristic of the soft irons rich in carbon, or the Nos. 1, 2, and 3 
 foundry pigs. 
 
 Open Pit. — See Foundry Pit. 
 
 Open Eods — See Crossed Kods. 
 
 Open Safety Valve. — One which is not a lock-up valve. 
 
 Open Sand. — A foundry mould has in most cases a top covering of sand, 
 and is therefore enclosed on all sides. But in very rough castings this 
 top is often dispensed with, and the casting is then said to be made in 
 open sand. The surface is necessarily extremely rough and uneven. 
 
 Open-topped Furnace. — The older form of blast furnace in which the 
 waste gases were allowed to escape into the atmosphere. Open-topped 
 furnaces now chiefly linger in Scotland and South Staffordshire. 
 
 Opeu-wehbed Girder. — A Lattice Girder (q.v.) . 
 
 Opposite Angles. — ^A term given to rolled iron bars whose section is that 
 of a double angle iron, the parallel flanges being set off on opposite 
 faces of the central web. 
 
 Order Number. — In large factories it is necessary, in order to avoid 
 confusion in the charging of time, to give to each job or order its special 
 number, by which alone it is known and distinguished from all others. 
 But to avoid the inconvenience of very high numbers the custom is to 
 class them in sets under the letters of the alphabet, in other words to 
 give to A a thousand numbers, Al, A2, A3, &c., then to take B, Bl, 
 B2, &c., up to its thousand, and so on. These are called the order 
 numbers, and their employment both saves time and facilitates refer- 
 ence at a future period. 
 
 Ordinates. — Lines drawn at right angles from either axis of a conic 
 section to the circumscribing circle. 
 
 Ore. — Metals in their crude condition as found naturally associated with 
 earthy matter or gangue. Ore is sometimes called mine. 
 
 Orifices. — Commonly applied to the openings in the sides of vessels from 
 which liquids are permitted to issue. 
 
 Orthographic Projection. — See Projection. 
 
 Oscillating Cylinder. — A steam engine cylinder suspended upon hoUow 
 trunnions and oscillating thereon, so that the piston rod and cylinder 
 accommodate their motion to that of the crank at all parts of the revolu- 
 tion. The trunnions are made hollow, and furnished with ports for the 
 passage of the steam. 
 
 Oscillating Engine. — A marine engine furnished with oscillating cylinders 
 (q.v.). It is a direct-acting engine and occupies but little space, and is 
 especially adapted for paddle steamers, but for screw propulsion it has 
 been almost entirely superseded by the more modem compound engines 
 of the inverted cylinder type. 
 
 Oscillating Stresses, or Alternate Stresses. — Ai'e those by which 
 
«40 DICTIONARY OF TERMS USED IN 
 
 structures, or the memters of structures are placed alternately in tension 
 and compression, as for example in counterbraced structures, subject to 
 alternate moving loads. The conclusions deduced from the experiments 
 of Wohler in this direction show that when a bar is subject to these 
 oscillations in stresses, the total stress on the bar is equal to their sum, 
 that is, supposing a tensile stress of two tons, and a compressive stress of 
 two tons, alternately applied, thejequivalent is a total stress of four tons. 
 
 Oscillation, Centre of. — See Centre of Oscillation. 
 
 Out and Out. — See Over-aU. 
 
 Outdoor Foreman. — A man whose duty consists in taking general super- 
 vision of repair works and the erecting of work sent out from the shops. 
 He is expected to give estimates or to furnish the necessary data for the 
 giving of estimates by the firm, to follow the work through, and to be 
 generally responsible to his employers for the proper carrying through 
 of the same. 
 
 Out of Gear. — ^Wheels are said to be out of gear when their teeth are 
 disengaged from one another, either in consequence of being drawn 
 backwards until their points clear, or endways imtil their flanks are 
 no longer in contact. 
 
 Out of Truth. — A shop term signifying inaccuracy of work. A winding 
 piece of board or metal, or a wobbling or eccentric piece of lathe work, 
 is said to be out of truth. 
 
 Outside Caliper. — See Caliper. 
 
 Outside Crank. — An engiae crank which occupies a position on the 
 outside of the crank shaft bearing or bearings. 
 
 Outside Cylinders. — Locomotive cylinders placed outside the framing and 
 coimeeted to pins on the driving wheels. 
 
 Outside Fire Box. — That portion of a locomotive boiler which encloses 
 the actual or inside fire box (q.v.) and -which presents a large water 
 surface therefore to the action of the fire. 
 
 Outside Gouge. — A firmer gouge, so called because the bevel is ground 
 upon the outside or rounding face. 
 
 Outside Lap, or Steam Lap. — Lap (q.v.) given to a shde valve on the out- 
 side edges as distinguished from exhaust lap (q.v.). The amount of 
 outside lap is a measure of the ratio of expansion of the steam, an early 
 cut-ofB implying a high ratio of expansion. 
 
 Outside Screw Tools. — Chasers (q.v.) or comb tools, used for cutting or 
 chasing external screws in the lathe. 
 
 Out Stroke. — The forward stroke of a gas engine piston, that is, in a 
 direction away from the ignition chamber. It is produced by the 
 explosion of the gaseous charge. 
 
 Outward Flow Turbine. — See Turbine. 
 
 Oval. — An egg-shaped figure, the curves of whose ends are unequal. 
 
 Oven Coke, or Hard Coke. — The hard coke produced by the distillation 
 of coal in ovens. Of the latter there are several kinds in use, the 
 Appolt, Coppee, Carves, and Pemolet. It differs from the gas coke of 
 the gas works in being distilled at so high a temperature that the 
 gaseous hydrocarbons are partially decomposed and deposit their 
 carbon in the coke. Its value depends upon its hardness and density 
 and richness in carbon, and it is employed for the melting of metal in 
 the cupola, for which gas coke would be unsuitable. 
 
 Over-all. — A common term in the workshop signifying an outermost 
 dimension embracing the utmost extent of the dimension. Out and 
 out is an equivalent term. 
 
MECHANICAL ENGINEERING. 241 
 
 Overblow. — See Aftertlow. 
 
 Overflow Valve. — Any valve ty wliioli surplus Uquid is allowed to run 
 away. Overflow valves occur in injectors and tanks. 
 
 Overhanging Cylinders. — Engine cylinders wMcli are bolted to the ends 
 of their bed plates instead of upon their faces. The advantage claimed 
 is the lowering of the piston rod centre and the shortening of the 
 foundation for the bed. 
 
 Overhanging Pulley. — A pulley which is attached to the overhanging 
 portion of an overhanging shaft (q.v.). 
 
 Overhanging Shaft. — Ai end portion of a shaft which projects beyond 
 its bearing, being supported therefore in one direction only. 
 
 Overhauling. — The pulling down of the slack of a hoisting chain. To 
 effect this it is necessary to attach a pear weight (q.v.) or a balance 
 ball (q.v.) to the end of the chain next the hook. Where a snatch 
 block is used, its own weight is usually sufficient to effect the over- 
 hauling of the chain. 
 
 Overhead Crank. — The crank of a vertical engine, the cylinder being 
 lowermost, to distinguish it from an inverted cylinder engine. 
 
 Overhead Gear. — See Pit-Head Gear. 
 
 Overhead Traveller, or Overhead Travelling Crane. — Usually consists 
 of a crab mounted on a gantry and worked either by hand or steam. 
 When a crane is used the term gantry crane (q.v.) is more properly 
 applied to it. When a crab is worked by steam the engine may be 
 either mounted on the crab itself or both the crab and gantry may be 
 driven through rope gearing from a source of power situated below, 
 and at a distance therefrom. The advantage of overhead travellers is 
 that they leave a clear space for working underneath, and travel up 
 and down and across the shop without interfering with the operations 
 on the floor. The gantry truss is carried on girders or beams at each 
 side of the building. 
 
 Overhead Travelling Crane. — See Overhead Traveller. 
 
 Overheating. — (1) Causes iron and steel to become burnt. The over- 
 heating may be produced by a brief exposure to a white heat or by a 
 lengthy exposure to a lower temperature. (2) The overheating of boiler 
 plates is due to the accumulations of sludge, or of incrustation within, 
 or to insufficient supply of water. The effect of overheating is to soften 
 the plates, which then become bulged or fractured by the internal 
 pressure. 
 
 Over lap. — The overlap of plates is the amount by which one ri vetted 
 plate extends over the other. The overlap of riveted plates should be 
 such that the distance from the edge of the rivet holes to the edge of 
 the plate should not be less than the diameter of the rivets. 
 
 Overlap Joint. — A riveted joint of boiler or similar plate in which the 
 edges of the plates overlap to an amount sufficient for the reception of 
 the rivets. This is the reverse of a butt-riveted joint. 
 
 Overpoled. — See Poling. 
 
 Overpressure. — The pressure of steam in a boiler beyond that which it is 
 designed to sustain. It is of course a relative term, depending on the 
 capability of each boiler itself, so that while 140 or 150 pounds would 
 not be overpressure in a new boiler of the locomotive type, 40 or 45 
 pounds would be overpressure in a Cornish or Lancashire boiler of bad 
 design and improperly stayed. Overpressure follows from overloading 
 of the safety valve, or sticking of the valve, and from the giving way 
 of weak sections of the boiler, too weak to withstand the ordinary or 
 
 B 
 
?42 DICTIONARY OF TERMS USED IN 
 
 the sudden strains to wMcli they are subjected, as seams, rings, 
 seatings, stays, &c. 
 
 Over-ramming. — Hard Eaniinirig (q.v.). 
 
 Over-ruiming. — Kef ers to the case of the unequal velocity ratio of driving 
 and driven wheels. Thus, if the force of momentum generated by the 
 revolution of a driven -wheel exceeds that generated in the driving 
 wheel the former will overrun the latter instead of being controlled by 
 it. Over -running is due to extreme and rapid variations in the driving 
 force exerted. 
 
 Over -riding. — Riding (q.v.). 
 
 Overshot Wheel. — A water wheel which is turned by the gravity or 
 weight of the water emptying itself into buckets at the top of the 
 periphery. 
 
 Overtime. — All time worked over the specified nominal number of weekly 
 hours. Sometimes, in balancing up, each day's time is taken distinct 
 from that of any other day, but commonly the whole week's account is 
 taken, so that the advantage of overtime worked on any one day 
 is sacrificed by time lost on another. Overtime is always paid for at a 
 higher rate than the ordinary, usually at an advance of twenty-five 
 per cent., or as the men say, "time and a quarter." For working all 
 night, fifty per cent, more is commonly paid, while for very urgent 
 work, as Sunday labour, breakdowns, &c., from fifty to a hundred per 
 cent. 
 
 Ox Gall. — Is used by draughtsmen to impart fluidity to theii' colours. 
 
 Ox Hides. — The best leather belting and laces are made from ox hide 
 tanned with oak bark, the chief supply coming from America. 
 
 Oxidation. — The chemical combination of certain of the elementary 
 bodies with oxygen gas in the presence of water. Its efi'ects are of 
 vast interest to the engineer from the part which oxygen plays in the 
 processes of the blast furnace, the processes of manufacture of wrought 
 iron and steel, the preservation of iron work, the mixing of alloys, the 
 making of rust joints, &c. AU the metals used by engineers are directly 
 oxidisable. 
 
 Oxide. — The direct product of oxidation (q.v.). The metallic ores are 
 chiefly oxides. The presence of oxides prevents the making of welded 
 and soldered joints, hence the addition of substances to imite with, and 
 flux off the oxides. Oxides in metals in small quantities are a source of 
 weakness. 
 
 Oxygen. — Symbol, 0. Combining weight, 16. The vital element in 
 the atmosphere. Its presence is essential to combustion and it enters 
 into combination with the carbon in fuel to produce heat in furnaces. 
 In union with metals it forms oxides. 
 
 Oyster Shells. — Sometimes used as a fluxinirou melting in the cupola, in 
 place of limestones. 
 
 P. 
 
 ■n. — The GreeWetter Pi, which is used to denote the relation of circum- 
 ference to diameter = 3' 14 159. 
 
 Packing. — (1) The material, hempen, metallic, or otherwise which is 
 enclosed in a stuffing box (q.v.) for the purposo of rendering tho 
 
MECHANICAL ENGINEERING. 243 
 
 moTing rod, steam, or water tight. (2) The act or process of insertion 
 of packing material. (3) Blocking (q.v.). (4) Leathers (q.v.) are 
 termed packings. 
 
 Fackiiig Case. — AH except the largest and roughest metal and timber 
 work, is enclosed in packing cases before it leaves the yard for delivery. 
 The cases are made of spruce deal, of about 6 ins. X 1 in. soantKng, 
 nailed with battens, and banded with hoop iron. Por foreign transit 
 the joints of the cases are lined with canvas cemented with marine 
 glue. Where numerous irregular-shaped pieces are enclosed in a case, 
 Biey are prevented from sHfting by bars, stays, or blocks of wood 
 placed crosswise in the box. Packing-case making is a special occupa- 
 tion and a department of the carpentry. 
 
 Packing Piece. — ^A plate of wood or metal interposed between parts to 
 make up a dimension or to afford a base for the attachment of a bracket 
 or other work. See Patch Piece. 
 
 Packing Ring. — (1) A piston ring (q.v.). (2) A ring of metal introduced 
 into a groove on tiie back of an equilibrium slide valve. See Equilibrium 
 Ring. (3) MetaUio packing. 
 
 Pad. — The socket of an ordinary brace. 
 
 Pad Chuck. — A square hole chuck in which the ordinary brace bits are 
 used, the square hole or socket being of the same size as that in the 
 brace. 
 
 Paddle. — A flat tool employed by puddlera, for spreading the substances 
 used in coating or fettling the puddling furnace, over the bottom. 
 
 Paddle Shaft. — The shaft which carries the paddle wheels of a steamer and 
 which is driven directly by the engine cranks. 
 
 Paddle Wheel. — A wheel which propels a steamer by means of the resistance 
 offered by the water to float boards arranged round its periphery and 
 revolving with the wheel. A paddle wheel is hung on each end of the 
 paddle shaft, which shaft is cranked and moved directly by the 
 connecting or piston rods from the engine cylinders. Paddle wheels are 
 either of Qie radial (q.v.) or feathering float (q.v.) types. 
 
 Pad Saw, or Keyhole Saw. — A small narrow saw which slides within a 
 hollow handle or pad, and is secured in place by two set screws. Used 
 for sawing curves of small radius, and holes in the central portions 
 of work. 
 
 Faint. — All ironwork is painted to preserve it from rust. Before inspection 
 it is only brushed over with linseed oil. Afterwards with three coats of 
 ordinary lead or other paint. Chains are painted with hot coal tar, the 
 chains being usually heated in a stove or over a clear fire before the 
 application of the tar. For bright work pure white-lead paint, or 
 tallow, or patent composition is used. See also Bituminous Paint, 
 Iron Oxide Paint, Silicate Paint. 
 
 Painting. — The application of any coating or preservative preparation to 
 the surface of work is designated painting. Thus foundry loam moulds 
 are painted with black- wash, castings are painted with preservatives 
 against corrosion, and lubricants are painted over broad surfaces. 
 Wheel teeth are painted with anti-friction mixtures, the wafters of 
 Roots blowers are painted to ensure smoothness of motion, &c. 
 
 Pale Oils. — See Clear Oils. 
 
 Pallets. — (1) Square or circular vessels used by draughtsmen for rubbing 
 and mixing colours (see Square Tile, Wheel Slope, and Cabinet Nest). 
 (2) The plates of a chain pump (q.v.). 
 
 Pane, Pean, Peen, Pein, or Pene. — The smaller or narrower end of a 
 
444 DICTIONARY OF TERMS USED IN 
 
 hanuner head. It is termed a tall pane -when it is spherical in form, 
 cross pane when in the form of a narrow round- edged ridge placed at 
 right angles with the axis of the shaft, straight pane when a ridge of 
 the same character runs longitudinally. 
 
 Panel. — (1) The central thinner or recessed portion of a piece of work. 
 Generally, a plain recess. (2) A bay (q.v.). 
 
 Panel Gauge. — A marking gauge for wood, but longer than the ordinary 
 bench gauge, being as much as 18 ins. or 20 ins. long. So called 
 from its use in gauging the widths of panels. It is used for all stuff 
 over 8 ins. or 10 ins. in width. 
 
 Panel Machine. — A machine for planing up thin timber of small 
 dimensions. Also called panel planing machine. 
 
 Panel Saw. — A small hand saw 26 ins. or less in length, and containing 
 from seven to ten teeth per inch. It is used chiefly for cutting the 
 shoulders of halvings and tenons, and for light work generally. 
 
 Pan-head Kivet A rivet the form of whose head is that of the frustrum 
 
 of a cone, or of a pan inverted. 
 
 Fantagraph. — An instrument used for copying drawings either to an en- 
 larged or to a reduced scale. It consists of four rods jointed in pairs 
 with knuckle joints, and a fixed point, a tracer, and a drawing point. 
 The relative positions of the rods are arranged by means of thumb- 
 screws set in certain holes in the two pairs, and the fixed point is set in 
 a board or table ; the tracer is passed over the original drawing, and the 
 drawing point, or pricker, describes the copy. 
 
 Pap. — A short pin or stud forming a projection on a casting which has to 
 be turned, and which without it could not conveniently be chucked. It 
 is, therefore, a chucking or centring piece simply, and being such, is 
 cut off after its purpose is fulfilled. 
 
 Paper Joint. — A mode of temporary jointing employed by pattern-makers. 
 In works of a circular character, such as gear-wheels, which are built 
 up in segments on a face chuck, the first course of segments is glued, 
 not directly to the plate, but to an intermediate thickness of paper, the 
 paper being laid down underneath the meeting of the end joints. This 
 when set dry and hard is sufficient to retain the segments in place 
 during turning, but when the work is done the entire ring is readily 
 lifted from the plate without splitting of the wood, the paper dividing 
 and tearing through the centre of its substance. 
 
 Paper Scale. — A scale used by draughtsmen, made of a slip of thick paper. 
 These are sold singly, or in sets of a dozen each. Each slip has one 
 edge only marked out, and that with a single scale, and fully divided. 
 They are preferred by many to the ordinary wood scales for this reason, 
 and also because of their flexibility, by virtue of which they can be 
 carried round curved lines. The objection to their use is that they 
 become dirty, and if, on the other hand, they are varnished to preserve 
 them clean, they shrink. 
 
 Paper Weight. — Flat paper weights are used in drawing offices for hold- 
 ing drawings open. 
 
 Parabola. — A section of a cone taken parallel with its side. 
 
 Parabolic Girder. — A form of bow-string girder, the outline of whose 
 bow is that of a polygon inscribed in a parabola. Used on bridge 
 work. 
 
 Parabolic Governor. — A governor (q.v.) in which the points of suspension 
 are so adjusted relatively to the length of the arms that the path 
 described bv the balls is approximately that of a parabola. Governors 
 
MECHANICAL ENGINEERING. 245 
 
 of this clas3 are extremely sensitive, and are known as erossed-arm 
 governors. 
 
 Parallel Fence. — A fence (q.v.) wMoli stands rigidly at right angles with 
 the saw-table,'as opposed to a canting fence, which can be altered to an 
 angle. Most fences are made movable for both kinds of sawing. 
 
 Parallel File, or Dead Parallel File. — A file in which there is no taper 
 whatever lengthways. 
 
 Parallel Forces. — Forces which act in parallel lines. Their resultant is 
 equal to their algebraical sum, and the poiat at which their resultant 
 acts is called the centre of forces. 
 
 Parallel Iron. — ^A plane iron of parallel thickness throughout. The ad- 
 vantage of its use is that the mouth of the plane is not increased in 
 width by the wearing backwards of the iron, as in the ordinary taper 
 form. 
 
 Parallel Lines. — ^Parallel lines are lines which are in the same plane, but 
 which if produced to infinity would never meet. 
 
 Parallel Motion. — A series of levers employed for the purpose of adapting 
 the curved movement of the end of the beam in a beam engine to the 
 rectiHuear motion of the piston rod. There are several such arrange- 
 ments in. use. See Back link, Maia Link, Parallel Poiat, Parallel 
 Eod, Radius Rod. 
 
 Parallelogram, — A plane quadrangular or four-sided figure, whose oppo- 
 site sides are parallel and equal. 
 
 Parallelogram of Forces. — This is a principle of the utmost importance in 
 mechanics, and is constantly employed in calculating the strains on 
 different members of built-up and braced structures. It may be stated 
 thus : — If the magnitude and direction of any two forces acting upon a 
 point be represented by two lines, and if the parallelogr.am of which 
 these lines form two sides be completed by two other lines equal and 
 parallel with the first, then the diagonal of the parallelogram, which 
 passes through the point where these forces act, will represent the mag- 
 nitude and direction of the resultant. 
 
 Parallel Point. — That point or centre in the arrangement of levers for 
 parallel motion (q.v.) in which the motion first becomes rectilinear. 
 
 Parallel Print. — A print (q.v.) whose sides are parallel instead of being 
 tapered in the usual manner. Prints are parallel when they are circular 
 and mould sideways, since the curve of the circle itself then gives suffi- 
 cient taper for delivery. 
 
 Parallel Eod. — The rod which connects the main and back links (q.v.), 
 in the arrangement known as parallel motion. 
 
 Parallel Bnle. — (1) A double rule employed by draughtsmen. Diagonal 
 and parallel jointing strips of metal maintain the blades parallel with 
 each other in all positions. Parallel Unes are oftener marked without its 
 aid hy holding the stock of the T" square against an edge of a drawing 
 board and sliding a set-square along the edge of the blade, marking 
 lines therefrom at the distances required. (2) A common form of 
 parallel rule is that in which a roller is inserted in the body of the rule 
 running in bearings therein. The lower edge of the roller stands 
 just perceptibly beyond the face of the rule, so that it carries the rule 
 over the paper on the principle of the ordinary round ruler. 
 
 Parallel Shank. — See Shank. 
 
 Parallel Strips. — ^Winding strips (q.v.). 
 
 Parallel Vice. — A vice, the surfaces of whose jaws always retain a 
 parallel position in relation to each other, no matter what the width of 
 
246 DICTIONARY OF TERMS USED IN 
 
 opening may te, wHoli is not the case in the ordinary hinged or tail 
 vices. Parallel -vices are used chiefly in the fitting shops for the better 
 classes of work. 
 
 Paring Chisel. — A long paring tool similar to the ordinary chisel, hut 
 about twice the length of the firmer tool. Patternmakers use these to 
 the almost entire exclusion of the others, as being more convenient for 
 their special work. Paring chisels are seldom driven with the mallet, 
 but actuated by hand pressure alone. They are made in widths ranging 
 from J in. to 2 ins. 
 
 Paring Gouge. — A long paring tool difEering from the ordinary firmer 
 gouge in its increased length, and in being ground on the inner curve, 
 hence called an inside gouge. These tools are not driven with the 
 mallet, but with the hand only. They range from J in. to 2 ins. in 
 width, and are used by patternmakers chiefly, for cutting the various 
 curved outHnes of their work. 
 
 Paring Tools, — ^All tools which act by spHttiag, or which remove the 
 fibres in a direction approximately parallel with their cutting faces. 
 Chisels, gouges, planes, axes, and tools for metal turning and planing 
 generally, may be classed as paring tools. Patternmakers' long chisels 
 and gouges are specifically called also paring tools, to distinguish them 
 from the short or firmer tools (q..v.). 
 
 Part. — One of the sections with which a moulding box is built. See 
 Plask, Top, Bottom, and Middle Parts, Three-part box, Cope, 
 Drag, &c. 
 
 Parting. — (1) The sand joint between two contiguous mouldiag boxes 
 or flasks (q.v.). (2) The process of making the joint. (3) The act of 
 separating the different box parts. 
 
 Parting tine. — The joint line of a pattern. It may be marked upon 
 the pattern, but in most oases has no actual existence upon that, 
 only signifying the parting or joint made by the moulder on the 
 face of the sand itself. The parting line may be in a true plane, or 
 its outUne may be uneven, irregular, and undulatory in character, 
 depending altogether on the outline of the pattern. 
 
 Parting Ring. — A heavy ring of cast iron by which the parting of loam 
 moulds is effected. A joint being made as required on any portion of 
 a loam mould, parting sand is steewn over, and the ring laid upon it. 
 On the upper face of the ring the remaining courses of bricks are 
 buUt and the loam struck. The upper portion of the mould can there- 
 fore he lifted from the lower, by means of lugs on the ring, and after- 
 wards replaced in the same position when ready for casting. 
 
 Parting Sand, — Sand employed in iron foundries for scattering over the 
 parting surface in order to effect a complete separation between the 
 joints of a mould. It consists of burnt sand scraped off the surfaces of 
 castings, is loose, and non-adhesive in character ; or baked new sand, 
 or powdered briokdust, or similar dry material is used. By its use the 
 sand in the top and bottom flasks is prevented from mingling, and the 
 parting surface is unbroken. The layer of sand does not exceed -feth in. 
 in thickness, and it is dusted over by the hand, and blown .away from 
 the pattern edges with bellows. 
 
 Parting Surface. — The surface of a moulder's sand joint which corres- 
 ponds with the parting line (q.v.). 
 
 Parting Tool, — A tool for metal and wood turning, used for cutting or 
 parting off work in the lathe. It is narrow, deep, square across the 
 end, and the width tapers sHghtly backwards in order that it shall 
 
MECHANICAL ENGINEERING. 247 
 
 deal itself in the out, that is, shall not nih against the sides of the 
 metal -which it divides, and so set up unnecessary friction. 
 
 Passages. — The steam-ways of a cylinder, emhraoing both ports, and 
 exhaust. 
 
 Fasses. — The passing and re-passiag of malleable iron or steel bars, 
 through the rolls of rolhng-mills. See Lost Pass. 
 
 Pasty. — The pasty condition of iron is that "which is intermediate between 
 the solid and fluid state. AU irons do not pass through the pasty 
 condition. Grey irons pass directly from the sohd to the Kquid state, 
 while the white irons go through the intermediate stage. Hence the 
 former are used for tie finer class of castings, for which the latter 
 would be unsuitable. The value of wrought iron is due chieily to the 
 readiness with which it can be made to assume any desired outUne 
 while in a pasty condition. 
 
 Patch. — A plate of wrought iron, or steel, or sometimes of cast-iron, 
 riveted or bolted to broten parts for purposes of repair. Broken 
 castings are sometimes patched in this way in preference to replacing 
 them with new. Boiler plates are often patched, and so also is plated 
 work generally which has been injured by corrosion or accident. 
 
 Patch Piece, or Patch Plate. — A casting bolted to wrought iron work to 
 form the base for the attachment of another casting, the patch plate 
 being an intermediary to facihtate the process of fitting-up and attach- 
 ment. It may be considered as a packing piece. 
 
 Patch Plate. — See Patch Piece. 
 
 Patent Fuels. — These consist generally of small coal mixed with a 
 cementing farinaceous or resinous substance, pressed into bricks and 
 dried. They are used only where storage space is a consideration. 
 
 Path of Contact. — The path described by the faces and flanks of wheel 
 teeth mutually engaged. 
 
 Pattern. — A model or a counterpart of a piece of work. As commonly 
 understood, the model in wood or other material from which a founder 
 makes his mould. This, called the pattern, in most cases constructed 
 of wood, is rammed up in sand, and being withdrawn, leaves its exact 
 impression behind, iiito which impression the metal is then poured. 
 Cores, drawbacks, &c., have to be provided for in patterns. 
 
 Pattern Bench. — An ordinary carpenter's or joiner's bench, comprising 
 top, legs, vice, stop, and drawer. 
 
 Pattern Letters. — These are made in cast lead, tin, or brass, and fastened 
 upon plates of wood from which the actual name-plates (q.v.) are then 
 cast. 
 
 Fatternmaking. — That section of engineering devoted to the making of 
 the wood patterns or models for foundry use. Pattemmaldng not 
 only includes the actual construction of patterns, but the making of 
 full-sized working drawings on boards, both for the use of the pattern 
 shop and for foundry loam work, the marking out of cored and loam 
 work in the foundry, the setting of cores in moulds, the gearing of 
 mortice wheels, and much other work of a miscellaneous character, 
 principally in connection with the foundry. 
 
 Pattern Register. — A book in which a record is kept of aU patterns, and 
 their places in the stores, to which the date of their construction 
 and the job for which they were made, together with other useful 
 memoranda may be added. 
 
 Pattern Shop. — That department of an engineer's works in which the 
 foundry patterns «re constructed. It contains the usual wood benches 
 
248 DICTIONARY OP TERMS USED IN 
 
 common to carpenters' shops, sawing stools, and sucli machines as are 
 suited to the capacities and requirements of the shop, as circular, and 
 band saws, panel planing machine, or general jomer, together with two 
 or three lathes of different sizes. 
 
 Pattern Stores. — These stores contain the foundry patterns, which, having 
 been sent back from the foundry and not being required again for 
 immediate use, are stored away. In this the patterns are variously 
 arranged according to their character and value. Large patterns are 
 placed sometimes in open sheds, covered in at the top but exposed to 
 the air at the sides, but the majority are placed in a closed building. 
 The smaller ones are placed on shelves, the larger ones laid on the 
 floor or suspended from the beams or rafters overhead. Standard 
 patterns which are in frequent request are placed in such positions that 
 they can be taken out more rapidly than those which are seldom re- 
 quired. In large stores an attendant is regularly employed to devote 
 the whole of his time to their storage, and a register is also kept con- 
 tainiag sundry useful particulars of there date of construction, purpose, 
 place of storage, &c. 
 
 Pattern Work, — See Pattemmaking. 
 
 Paul, or Pawl. — (X) The finger or click which engages with a ratchet 
 wheel. (2) The catch which fixes a turntable. (3) The catch or dog 
 which 'prevents the endlong movement of a crane spindle when made 
 for single and double gear. See Spring Pawl. 
 
 Paul Feed, or Eatchet Feed. — The feed of a machine effected by means of 
 a paul and ratchet or small cog wheel. The feeds of planing and 
 shaping machines are effected by means of pauls actuatiag the feed 
 screws. 
 
 Pawl.— See Paul. 
 
 Fean. — See Pane. 
 
 Pear-tree. (Pyrus communis.) — Sometimes, though seldom, used in the 
 construction of patterns. It works sweetly, but is apt to warp unless 
 very well seasoned. Used for set-squares and Prench curves. Sp. gr. -73. 
 A cubic foot weighs 45 lbs. 
 
 Pear Weight. — A weight of the shape indicated by its name, which is 
 attached to the lifting chain of a crane just above the hook, for the pur- 
 pose of overhauling or pulling it down when there is no load being 
 lifted. The reason for its employment is that the weight of the chain 
 itself is not sufficient to overcome its own friction on the pulley and 
 the inertia of that portion of the chain which passes from the pulley to 
 the barrel. 
 
 Feasemeal. — This is used in the finer and more intricate class of mould- 
 ing as a fixing for the blackening, being intermediate between the black- 
 ing and the sand. In large ordinary and fiat moulds the blacking is 
 simply sleeked over without the intervention of peasemeal. 
 
 Pedestal. — A plummer block (q. v.) . See Horn Plates. 
 
 Peen. — See Pane. 
 
 Peg and Cup Dowells. — ^Patternmakers' metaUio dowels, consisting of 
 the plain male and female portions without a plate. (See Plate Dowels.) 
 The peg or pin is provided with a tapered shank or prolongation grooved 
 circularly, which shank is driven into one half the pattern, and the 
 cupped or hollow portion is also ribbed in the same manner and driven 
 into the opposite half. The dowels hold, therefore, in the wood by the 
 friction of their ribbed surfaces. They are made in brass. 
 
 Pegging Bammer. — A rammer with a small rounded head, used for press- 
 
MECHANICAL ENGINEERING. 249 
 
 ing sand around the narrower portions of patterns. The end of the 
 handle of a larger rammer is often employed as a peggiag rammer. 
 
 Pein. — The pane (q.T.) of a hammer. 
 
 Pendant Bracket. — A hang-do-mi (q.v.) bracket. 
 
 Pendulum. — The swinging ball and stem of the pendulum form of governor 
 is called the pendulum. 
 
 Pendulum Governor. — A governor (q.v.) consisting of a pair of balls 
 suspended from arms whose centre is at, or near, the centre line of a 
 vertical axis around which the balls rotate. It is called the pendulum 
 governor because the time of a revolution is affected by the length of 
 the axis of the cone just aa the time of oscillation of an ordinary pen- 
 dulum is affected by the length of its rod, that is, the time of a revolu- 
 tion varies directly aa the square root of the height of the cone. 
 
 Pendulum Hammer, or Monkey. — A heavy smith's hammer, suspended 
 by a rope from a beam and furnished with a long tail or handle, by 
 which it is swung to and fro for the purpose of directing blows upon 
 the ends of large bars and forgings during the process of upsetting (q.v.) . 
 
 Pene. — See Pane. 
 
 Pening. — Beating over, or smoothing over, a metallic surface with the 
 pane or pene of a hammer. 
 
 Penstock. — A pentrough (q.v.). Also applied to the sluice cocks or 
 hatches of large size which regulate the flow of water from the pen- 
 trough, or which close the entrance to dry docks. 
 
 Pentrough. — The reservoir above a water wheel which supplies the water 
 directly to the wheel, the quantity being regulated by a sluice. 
 
 Percussion, Centre of. — See Centre of Percussion. 
 
 Perfect Engine. — ^An ideal engine which can have no existence in fact, 
 but the theoretical performance of which it is convenient to assume aa a 
 standard for the measurement of the performances of actual engines. 
 A perfect engine would be one in which there was no loss of heat, or 
 one in which the indicator line would be an adiabatic curve (q.v.). 
 
 Perforated Pulley. — A wrought-iron or steel pulley, which is honey- 
 combed with numerous small holes perforated through the plate of 
 which it is composed, and through which the air escapes, giving the 
 belt closer adhesion. 
 
 Periphery. — The surface or plane of the circumference of a cylinder. 
 
 Permanent Coupling. — Any coupling by means of which the ends of 
 shafts are united to make a permanent Une, being the reverse there- 
 fore of a disengaging coupling or clutch. 
 
 Permanent Load. — A load which is constant and unvarying, and a dead 
 load, as the weight of a straoture itself, or a load imposed thereon, or 
 both taken in conjunction as distinguished from a live load (q.v.), or 
 from a rolling load (q.v.). 
 
 Permanent Set. — That amount of deflection from which a beam or 
 structure is unable to return to its original form, but which remains 
 constant. The term is used in contradistinction to that bending 
 underneath a load from which a structure recovers on the weight being 
 removed. 
 
 Permanent Way. — Includes the sleepers, chairs, rails, fish-plates, points, 
 crossings, &c., of a line of railway, as opposed to the temporary lines 
 of rails and tramroads laid down by contractors. 
 
 Permanent-way Crane. — A crane used as an accident crane, and so called 
 because made to run on the permanent way. 
 
 Perpendicular. — Synonymous with vertical ; that is a Une which stands 
 
250 DICTIONARY OF TERMS USED IN 
 
 at right angles -witl. the surface of still -water is strictly perpendicular. 
 Bnt a line is perpendicular to another line or to a plane, when the angles 
 ■which it makes there-with are equal, that is right angles, no matter 
 •what position the base hue or plane may occupy in relation to the 
 horizontal. 
 
 Perpetual Screw. — An endless screw (q.v.). 
 
 Persian Drill. — See Axchimediau DrOl. 
 
 Perspective. — Is used only occasionally iu engineering drawing, and 
 chiefly to assist in the comprehension of a drawing which presents 
 some difficulty. A knowledge of perspective is useful also in preparing 
 sketches of machines for engra-ving, though photography has generally 
 supplanted it. 
 
 Pet Cock. — An ordinary small plug-cock inserted in the ends of steam 
 cyliaders to allow of the escape of the water of condensation on the 
 starting of the engine. But for this precaution the presence of water 
 in cylinders having httle clearance, would, owing to its incompressi- 
 bUity, he a source of danger, leading to the possible blowing out of the 
 cylinder ends. 
 
 Petroleum Engine. — ^A gas engine in which petroleum oil is fed into the 
 combustion chamber and ignited ; its action, due to the expansion of 
 the vapour, is similar to that of coal gas. 
 
 Phoenix Column. — A built-up column made of four or more segments 
 united by outer flanges running longitudinally. 
 
 Phosphor Bronze. — An alloy composed of copper and tin, to which a little 
 phosphorus is added. It owes its value to its great toughness and 
 tensile strength, its tenacity varying from twenty-two to thirty-three 
 tons per square inch. It is now very largely employed in bearings 
 where durability is required, and in gearing subjected to great stress 
 and shock. 
 
 Phosphor Tin. — An alloy of tin and phosphorus which has been used with 
 moderate success for bearings. 
 
 Phosphorus. — Symbol, P. Combiuuig weight, 30-96. Enters largely 
 into the calculations of the engineer by reason of its influence upon 
 iron and brass. In wrought iron it produces cold shortness, its 
 influence being very decided when present to the extent of '75 per cent. 
 It renders steel cold short and valueless for cutting purposes. In steel 
 rails it should not exceed • 1 per cent. Its separation from the iron in 
 the Bessemer process for steel making is accomplished during the after- 
 blow (q.v.). In the basic process the phosphoric anhydride thus formed 
 enters into combination with the lime of the charge to form phosphate 
 of Hme. The effect of phosphorus on pig iron is to increase its fluidity 
 and hardness, hence phosphoric pig is used for the finer sort of 
 castings. If present in cast iron to the extent of I'S per cent, it is 
 injurious to its tensile strength. Added to gun-metal it produces a 
 tough alloy. See Phosphor Bronze. 
 
 Phototype. — ^A drawing made from another drawing by a species of 
 photography, the advantage of the process being the rapidity with 
 which any number of copies all precisely alike can be multiplied and 
 the time occupied in re-drawing and tracing mostly saved. There are 
 three kinds of phototypes, the blue line, having blue lines on a white 
 ground ; the white line, with white lines on a blue ground ; the black 
 line, where the lines are black on a white ground. For making blue- 
 line phototypes a printing frame, a bath containing a saturated solu- 
 tion of yellow prussiate of potash, a bath of hydrochloric acid composed 
 
MECHANICAL ENGINEERING. 2;i 
 
 of about one part of acid to nine parts of water, and two baths of clean 
 water are required. The tracing or drawing to be printed is laid face 
 downwards on the inside face of the glass in the frame, a sheet of 
 prepared copying paper is then laid face downwards on the top of the 
 tracing or drawing, a piece of felt is laid on that, and all are com- 
 fined together with boards, which are maintained in position by 
 means of springs and bars of wood (see Printing Erame). The frame is 
 then swung over so that the outer face of the glass is exposed to the 
 light. In strong sunlight a tracing will probably reqtiire from haU-a- 
 minute to two minutes, and a drawing about three minutes, but pro- 
 portionally longer in dull weather. The best way to tell when the 
 phototype is taken is to have some strips cut from the drawing or tracing 
 paper on which the drawing or tracing is made, mark some black lines 
 upon them, gum them in the frame, and lay some strips of prepared 
 paper over these, and then at the end of every minute or two pull one 
 of these test strips out and put it into the yellow prussiate bath. When 
 the phototype is finished the blue lines will come out on a clear yellow 
 ground colour on the test paper. When the print is complete the 
 prepared paper is taken out of the frame, laid face downwards, and an 
 edge of about half-an-inch in width turned up all round. It is then 
 placed face downwards in the yeUow prussiate bath. When the Unes 
 come out strong like those on the test paper it is transferred to one of 
 the water baths and washed well by drawing it rapidly through the 
 water, then taken to the acid bath and covered with acidulated water. 
 A blue deposit will at once settle on the print, and on brushing this off 
 with a soft flat brush the ground colour will be found white. It is 
 then given a final washing with a soft brush in the last water bath, and 
 hung up to dry. White line phototypes are put into the frame in the 
 same way, but they take much longer than the blue, or from half-an- 
 hour to two hours, according to the strength of the light. But instead 
 of passing the print through the yellow and blue baths, it is only 
 washed in water until the lines come out on the blue ground colour. 
 Black-line phototypes are printed in the same way as the white lines. 
 The black lines are seldom used, the white and blue coming out best. 
 
 Physic. — Small amounts of various substances added to bar iron used for 
 the manufacture of steel in order to assist in the elimination therefrom 
 of sulphur, phosphorus, and other deleterious ingredients. Generally 
 speaking, also any substance added to a metal or alloy, to improve it. 
 Burnt steel is sometimes physicked. 
 
 Picker, or Picker-out. — A fine-pointed steel wire used for withdrawing 
 small patterns from the sand. Lifting screws (q.v.) are used for the 
 heavier work. 
 
 Picker-out. — See Picker. 
 
 Picking-out. — The lifting of light patterns from the mould with a 
 picker (q.v.J. 
 
 Pickling. — (1) A process by which the outer hard skin is removed from 
 castings before they are operated upon by files or cutting tools. Iron 
 castings are pickled in sulphuric acid and water, brass castings in nitric 
 acid and water. The practice is not much resorted to except in the case 
 of small work. (2) The immersion of sheet iron plates used in the manu- 
 facture of tin plate in dilute sulphuric acid contained in a leaden 
 trough, by which all oxide is dissolved off. 
 
 Piecework. — Work done by contract as distinguished from day work. 
 The practice of piecework is adopted extensively in most departments 
 
2S2 DICTIONARY OF TERMS USED m 
 
 of engineeriag except in pattemmaking, and there also to a limited 
 extent. The price for work is usually fixed by the foreman of the 
 department. The custom ia for a chargeman to take a job for a deiinita 
 sum, to find employment for the men whom the foreman places 
 ■with him, and to divide the balance, if any, among them, reserving a 
 larger share for himself than for them, by reason of his increased 
 responsibility. The balance is not paid until the work is finished, but 
 each man takes his ordinary wages, together with overtime if worked, 
 as long as the job is going on. If there is a deficiency, the custom 
 varies in different shops ; in some the deficiency is made good from the 
 first subsequent job which shows a balance, in others each job is con- 
 sidered independently of every other, and though the workman may 
 have a deficit on one, if he makes a balance on the next he reaps the full 
 advantage of it. But a man rarely suffers actual loss, that is, receives 
 less than his usual wages. 
 
 Piecework Note, or Contract Note. — A paper given to a workman who 
 receives a job to be done at a definite price. It contains the description 
 of the job, with its order number, price, date of giving out, name of 
 man, and of his mate or mates ; and a counterfoil of it is kept by the 
 foreman or manager. 
 
 Piercer. — A vent wire (q.v.). 
 
 Pig. — (1) A bar of cast-iron of D -shaped section, and weighing about a 
 hundredweight. So called because when run from the smelting furnace 
 it passes through a large intermediate reservoir called the sow, from 
 which the smaller moulds or pigs diverge. See Pig Iron. (2) Lead is 
 cast into pigs when it leaves the improving furnace (q.v.) of about the 
 same weight and shape as pig-iron, but somewhat flatter. (3) Bars of 
 blister copper (q.v.) are termed pigs. 
 
 Pig and Ore Process. — See Siemens Process. 
 
 Pig and Scrap Process. — See Siemens-Martin Process. 
 
 Pig Bed The sand bed containing the moulds into which pig-iron is 
 
 run from the blast furnace. 
 
 Pig Boiling, or Wet Puddling. — That form of puddling in which the iron 
 is purified while in a molten condition, in a reverberatory, or a revolving 
 furnace. A layer of slag upon the surface protects the metal from the 
 action of the air, and the decarburization is effected by the oxide of 
 iron in the fettling (q.v.) and in the scale present. See App. 
 
 Pig Iron. — The cast-iron of commerce. It is classed according to quality, 
 number one, two, three, &o. ; the greyest, softest iron being at the 
 beginning, and the hard white irons at the end of the list ; one, two and 
 three are foundry pigs specially, being most suitable for castings, while 
 the numbers above these are chiefly employed for conversion into 
 vrrought iron. See Foundry Pig, and Porge Pigs. 
 
 Pig-iron Breaker. — A machine used for breaking up pig iron into short 
 lengths for remelting in the cupola. Blake's machine will break a ton 
 a minute. In the absence of a machine, pig is broken either with a 
 sledge hammer, or by throwing the bars down upon the angular 
 edge of a mass of iron embedded in or laid upon the ground. 
 
 Pig Mould, or Casting Pit. — The receptacle for the refined iron which is 
 tapped out from the refinery (q.v.). It consists of cast-iron blocks 
 rebated and luted together with fire-clay, and in communication 
 with the refinery through a plate. It rests upon a cistern of brick- 
 work, or cast-iron, through which a current of cold water circulates 
 in order to cool the mould. A rib is often left in the bottom of the 
 
MECHANICAL ENGINEERING. 253 
 
 mould to produce a line of Tveakness in the plate to facilitate its break- 
 ing up. 
 
 Pig Stack. — Tte pile of pig iron in stock in an engineering -works. 
 
 Pile. — (1) The fagot of puddled bar prepared for the reheating furnace. 
 See Fagoting. (2) Squared timber driven into the beds of streams, 
 or into uncertain and marshy ground, to form the foundations of bridges 
 or buildings. The point of the pile is enclosed in iron, and the head 
 encased with an iron ring to prevent splitting of the wood. See also 
 Screw Pile. 
 
 Pile Cap. — A beam which connects the heads of piles. 
 
 Pile Driver. — A vertical framework, provided with guides for carrying 
 a descending weight, or monkey, which, being first of all elevated to 
 the top of the framing, is allowed to fall by the force of gravity on the 
 head of the pUe. Pile drivers are worked either by hand or by steam, 
 from a crab winch. 
 
 Pile Hoop. — An iron band, or bond, shrunk on the head of a pile to 
 prevent splitting of the timber while being driven in. 
 
 Pile Screw. — A screw used for the bottoms of cast-iron foundation piles. 
 The screw, usually of one revolution only, and cast on a centre-tapered 
 core or cylinder, is run into the soil by worm gearing from above, and 
 becomes the attachment for the upper columns or piles. 
 
 Pile Shoe. — An iron point with straps, fastened to the driven end of a pile 
 to enable it to penetrate the ground. 
 
 Piling, — The placing of iron bars in pile. See PUe, Fagoting. 
 
 Pillar. — A column (q. v.) . 
 
 Pillar Bolt. — Bolts shaped like gland bolls (q.v.) are sometimes termed 
 pillar bolts. 
 
 Pillar Drill. — A form of drilling machine, which is supported by a central 
 pillar terminating in a suitable base. 
 
 Pillar File. — A flat, thin, and narrow safe-edged file. 
 
 Pillar Iron. — Rolled malleable iron bars used for building up phoenix 
 columns. The section of the iron is that of the quadrant of a circle 
 with external flanges for bolting to the quadrants on each side, four 
 such quadrants therefore forming a circle. The dimensions are given 
 in internal diameters, and range from 6 ins. to 11 J ins. 
 
 Pillar Pump. — A lift or force pump attached to a base plate upon which 
 a pillar stands, the latter forming the support for a crank, fly-wheel, 
 and handle by which the necessary movements are imparted to the rod 
 of the bucket or piston. 
 
 Pillow.— See Pillow Block. 
 
 Pillow Block, or Pillow. — A pedestal or plummer block (q.v.), being the 
 older name for the actual plummer block which receives the pillow 
 bearing or "brass." 
 
 Pimple Metal. — See Fine Metal. 
 
 Pin. — (1) A small axis or spindle, as that which carries a pulley, or on 
 which a lever oscUlates. (2) A split piece of iron rod or wire which 
 keeps a nut or collar in place, hence called a split pin. 
 
 Pin Boss. — The small boss of an engine crank which carries the crank 
 pin (q.v.). 
 
 Pincers. — Used for drawing nails from timber. Made of iron, and steel- 
 faced in the jaws. Pincers should be large and nearly flat acrogs the 
 face, for affording greater leverage. 
 
 Pincer Tongs. — A pair of smith's tongs open or globular, similar to car- 
 penters' pincers, but Vee'd also in the jaws to grip thin rods or bolts, the 
 
254 DICTIONARY OF TERMS USED IN 
 
 head of the rod or bolt heing enclosed by the globular body of th» 
 jaws. 
 
 Pinch Bar. — A shop term used to designate a crow-bar. The word indi- 
 cates the method of moving trollies about the yard tramrails, by 
 inserting the end of the bar between the wheel and the rail, and so 
 pinching the carriage along. 
 
 Pin Drill. — A drill which is prolonged below the cutting edges into a 
 short solid central cylinder of relatively small diameter which fits into 
 a hole previously drilled to correspond, and becomes a concentric guide 
 to the cutting edges for the larger hole. Used in flat countersinking. 
 
 Pine Wood, or Fir. — Is applied to timber obtained from the trees of the 
 natural order Coniferce, which order includes such trees as the yew, 
 cedar, larch, &c. Pine wood is largely used in engineering construc- 
 tion. The term deals (q.v.) refers to the sizes of the timber as imported. 
 The Baltic red or Eiga deals are yielded by the Scotch iir ( Pinus sylvestris) , 
 the white deal by the spruce fir [Abies excelsa) of Norway. The North 
 American white deals are obtained from the Weymouth or white pine 
 [Pinus strohus). The yellow pine is the wood of the Pinus variabilis or 
 Pinus mitis, or Pinus liitea. The pitch pine is yielded by the Pinus rigida. 
 The uses to which the pines are put by engineers are for foundry 
 patterns, for which the yellow and wUte are employed, and for the frame- 
 work of heavy structures in wood, the red and pitch pines being mostly 
 employed for these. The sp. gr. of red deal ranges from '48 to '70, and 
 the weight of a cubic foot from 29 to 43 lbs., that of spruce being about 
 the same. The North American yellow pine, sp. gr. '46, and weight 
 28; the pitch pine, sp.gr. -73, and weight 45 lbs. Very wide variations, 
 however, occtu.' in woods of the same species but of different qualities 
 and under different conditions of seasoning, so that these must be taken 
 as rough average approximations only. 
 
 Pinion. — A small toothed wheel, either bevel or spur. It denotes no 
 particular size, but in a pair the smaller of the two is the pinion. 
 
 Pinning. — The securing of the cogs of mortice wheels in their place. 
 This is effected by driving naQs or short lengths of wire into the ends 
 of the shanks just within the rim, or sometimes through the rim itself. 
 Wedging is often substituted for pinning. 
 
 Pinny. — (1) When wrought iron or gun metal contains numerous en- 
 closed specks of metal harder than that in the general mass they are 
 said to be pinny. (2) A term applied to signify the condition of a 
 file whose teeth have become choked up with minute particles of soft 
 abraded metal. It is cleaned out with card wire. 
 
 Pin Kammer. — A pegging rammer (q.v.). 
 
 Pipe. — (1) A cyHndrical tube open at both ends and used for the con- 
 veyance of water, steam, or other liquids or gases. There are numerous 
 kinds of pipes — cast iron, copper, rain water, steam, weldless — 
 described under their headings. (2) A hoUow spindle or quill is 
 often termed a pipe. 
 
 Pipe Bend. — See Bend. 
 
 Pipe Bending. — When bending copper and wrought iron and lead pipes 
 it is necessary to guard against buckling or wrinkling in the internal 
 curve. This is prevented by pouring into the section which is to be 
 bent a quantity of melted rosin or fusible alloy which preserves its 
 circular shape during the bending process, and is melted out again 
 afterwards. When wrought-iron pipes are being bent hot, sand is 
 often used instead of an aUoy, which would melt with the heat. 
 
MECHANICAL ENGINEERING. zjj 
 
 Pipe-clay. — Is used for making models of ornamental castings, the model- 
 ling of which demands considerable time. Clay is mixed mth water 
 or with glycerine, the latter causing it to retain its plasticity longer 
 than the former. Moulds are taken direct from the clay model, or a 
 metal pattern is moulded from the model and the actual mould is taken 
 from that. 
 
 Pipe Connections. — The various parts used in making the joints of pipes, 
 as bends, tees, unions, elbows, crosses, nipples, thimbles, &c., described 
 under their headings. 
 
 Pipe Covering. — See Covering of Pipes. 
 
 Pipe-cutter. — A tool used for cutting ofi wrought-iron piping. It consists 
 of a hook or stirrup within which the pipe is grasped, and a hardened 
 sharp-edged steel revolving disc, whose centre is adjustable and which 
 beiag rotated around the pipe by means of a lever handle cuts it off. 
 
 Pipe Flange. — ^When a series of pipes have to be rigidly connected in 
 line, flanges are used in preference to sockets. These are united with 
 bolts and the si^es of flanges and number and sizes of bolts usually 
 bear some approximately definite relation to the diameter of the pipe. 
 Planges are either rough or faced ; in the former case they are jointed 
 with lead or millboard, in the latter with red-lead alone, dependent on 
 the purposes for which the pipes are to be used. 
 
 Pipe Joint. — Pipes are joiated in various ways, with flanges, sockets, 
 and spigots, caulked or turned, the various hose couplings unions, &c. 
 
 Pipe Moulding. — Where cast-iron pipes are made in quantity it is the 
 practice to mould them by special appliances, the pipe pattern being 
 of iron, and usually moulded vertically. The cores are made on an 
 expanding and collapsible bar (see Core Bar), so that the use of hay- 
 bands is dispensed with. Pipes are either cast on a sloping bed, or 
 else upright. 
 
 Pipe Nails. — Broad flat-headed nails of wrought or malleable iron used 
 as chaplets (q.v.) in light cored work. Being employed largely for 
 pipes they are thus denominated. 
 
 Pipe Ovens. — See Pipe Stoves. 
 
 Pipe Prover. — See Hydraulic Pipe Prover. 
 
 Pipe EoU. — A roll hollowed or curved longitudinally, free to turn on a 
 bearing bracket, and used for the support of long lengths of steam and 
 hot-water pipes, its function being to pemut of the free endlong 
 expansion and contraction of the series of pipes due to heat. 
 
 Pipe Sleekers. — Moulders' tools curved lq cross sections and used for 
 smoothing pipe moulds and hoUow circular work generally. 
 
 Pipe Stand. — A bracket hollowed on its top face, its use being to afford 
 support to pipes, and to keep them from the ground and prevent them 
 from rusting. 
 
 Pipe Stoves, or Pipe Ovens. — Stoves for hot blast, in which the air, 
 while on its way to the blast furnace, is heated by being passed 
 through a series of cast-iron pipes arranged horizontally or vertically 
 in a closed chamber. The air is heated sometimes by a fire, usually by 
 the hot gases from the furnace. About one square foot of heating 
 suri^ace is allowed per cubic foot of blast passing through, though 
 rather more when the waste gases are used. Pipe stoves are being 
 supplanted by the regenerative stoves, the iron pipes in the former 
 frequently suffering fracture, oxidation and other evils. 
 
 Pipe Tap. — A Gas Tap. See Gas Stocks and Dies. 
 
 Pipe-testing Machine. — See Hydraulic Pipe Prover. 
 
i56 DICTIONARY OF TERMS USED IN 
 
 Pipe-ttreader.— A macMne for outtiiig the threads, or screws in metal 
 tubing. 
 
 Pipe Tongs. — A pair of tongs hollowed out and finely serrated in the jaws. 
 Used for the clasping and screwing up of wrought-iron piping, the 
 serrations maintaining a secure hold without risk of bruising the pipes. 
 Those of small sizes are called gas plyers. 
 
 Pipe Wrench. — A tool which fulfils the same purpose as pipe tongs, but 
 which is provided with a single handle only, and embraces the work by 
 means of a hinged lever which tightens with increase of pressure. 
 
 Piston. — A solid or hollow disc-like plunger moving lineally in a closely- 
 fitting bored receptacle termed its cylinder. Engines and pumps are 
 furnished with pistons against which steam, air, gas, or water pressure 
 is brought to bear. Pistons are rendered close fitting by cup leathers 
 (q.v.), junk rings (q.v.), Ramsbottom rings (q.v.), and split rings 
 (q.v.). The revolving portions of a rotary engine or a blower are also 
 termed pis-tDns. 
 
 Piston Air Pump. — A marine engine air pump fitted with suction and 
 delivery valves at both ends, and having a solid bucket. 
 
 Piston Cover. — In small engine pistons it is common to form them of a 
 single split-ring enclosed between top and bottom discs. These discs 
 are termed piston covers. 
 
 Piston Packing. — The packing by means of which pistons are rendered 
 air, gas, steam or water tight. See Piston, Piston Ring. 
 
 Piston Bing. — A metallic ring either of cast iron, wrought iron or gun 
 metal, the first being preferable, as possessing more elasticity than the 
 others, and used as the peripheral portion of an engine piston. The ring 
 is thin and turned slightly larger in diameter than the bore of the 
 cyKnder, usually also thicker on one side than on the other, then 
 slotted across diagonally and forced into the cyUnder between the 
 piston covers. Its elasticity then thrusts it outwards and maintains a 
 steam-tight joint with the bore. 
 
 Piston Kod. — The rod attached to the piston of an engine or pump, by 
 which its motion is transmitted to the connecting rod or crank. The 
 rod travels through a packed stuffing box and gland, by which leakage 
 of the contents of the cylinder is prevented. 
 
 Piston-rod Gland. — The gland which closes tlie stuffing box of the piston- 
 rod of an engine or pump cylinder. It is placed on the cover of the 
 cylinder or barrel and renders the piston rod steam or water tight. 
 
 Piston-rod Packing. — See Packing. 
 
 Piston Speed. — The speed of an engine piston measured in feet per 
 minute. The speed ranges ordinarily from 260 feet in condensing and 
 heavy engines to about 800 in locomotive engines. The piston speed is 
 one of the factors in the estimation of the engine or horse-power. 
 
 Piston Spring. — (1) A spring ring, or piston ring. (2) A spring placed 
 within the ring to press it outwards. 
 
 Piston Valve. — A slide valve whose transverse section is circular, moving 
 closely in a circular seating, opening and closing steam ports arranged 
 diagonally around the seating. The advantage of these valves is that 
 they are balanced. 
 
 Pit.— See Foundry Pit. 
 
 Pitch. — (1) The distances between the centres of wheel teeth, or of bolts, 
 rivets, or boiler stays, or similar parts arranged equidistantly. Thus 
 wheel teeth or rivets, &c., whose centres are 2 in. apart are of 2 in. 
 pitch. (2) The inclination or rake of the teeth of saws, varying from 
 
MECMANICAL ENGINEERING. 25? 
 
 those which are upright or have no pitch, as in cross out saws, to those 
 
 ■which are set forward very much, as in some mill saws for soft woods. 
 
 (3) The angle at which a plane iron is set in its stock, the angle being 
 
 measured from the hack of the bedding on which the plane iron rests, to 
 
 the sole of the plane. It varies sometimes for hard and soft woods, but 
 
 most planes are used for both alike, and are made to an angle of 45°. 
 
 Some of the planes for hard wood range to 55°. (4) The height or 
 
 angle of a roof truss. 
 Pitch Chain. — A chain composed of built-up flat links, between whose 
 
 sides the projections of a sprocket wheel engage. The centres of the 
 
 link pins are pitched out with exact uniformity and correspond with 
 
 the centres of the sprockets, hence the term. 
 Fitch Circle. — The circumference of the pitch line (q.v.). 
 Fitch Cone. — The imaginary cone formed by the development of the pitch 
 
 plane of a bevel wheel. 
 Fitch Diameter. — The diameter of the pitch line of a wheel, that being 
 
 the term in which the size of the wheel is given, the diameter at root 
 
 and point being deduced therefrom, and from the pitch. 
 Pitching Out. — The marking or dividing out of the equidistant centres of 
 
 wheel teeth, or rivets, or other similarly pitched work, with dividers or 
 
 compasses. 
 Pitch Line. — The line on which the centres or the pitches of wheel teeth 
 
 occur. Its position relatively to the length of ihe tooth is -j^ths from 
 
 the point and -njths from the bottom, the difference in which allows the 
 
 necessaiy bottom clearance. 
 Fitch Plane. — The plane of a pitch line from one end of the wheel teeth 
 
 to the other. In a ^evel wheel it is the frustrum of a cone. 
 Fit Head Gear. — The frames, rope pulleys, bearings, and bracing, erected 
 
 over a pit's mouth for raising and lowering the cage. 
 Pitman.— A term sometimes applied to a connecting rod. 
 Pitman Boz. — The box end of a connecting rod or pitman (q.v.). 
 Fit Saw. — A saw about sixfeet in length, having ^-in. to f -in. tooth spaces, 
 
 and furnished with two cross handles, one above for the top sawyer and 
 
 one below for the bottom sawyer. Used for cutting planks and boards 
 
 in a saw pit. 
 Pitting. — The corrosion of boiler and wrought-iron plates in patches, due 
 
 to the action of acids, or to their inferior quahty, or to electro-chemical 
 
 action, or to all combined. 
 Pit Wheel. — A mortice wheel revolving on a horizontal axis, and which is 
 
 usually the first motion wheel in a mill, so called because it revolves in 
 
 a pit specially prepared for its reception. 
 Plan. — The appearance which a structure would have (disregarding 
 
 perspective) to an observer looking at it from above. " Sectional plan " 
 
 supposes the structure cut through in a horizontal plane and the 
 
 observer placed as before. 
 Plan Angle. — The angle formed by the two edges of a double-edgea 
 
 metal turning tool viewed from above. 
 Plane. — ^A cutting tool which owes its value to the guidance which the 
 
 wooden or iron stock imparts to the cutting iron. The stock is usually 
 
 of beech wood, and the iron is held in place with a wedge or screw. 
 
 Iron planes are made for various special purposes, and in most of these 
 
 the iron is tightened with a screw. There are perhaps a hundred 
 
 varieties of planes in use. 
 Plane Iron. — The cutting iron of a wood-working plane, sometimes single, 
 
258 DICTIONARY OP TERMS USED IN 
 
 sometimes double, the loTver one then for cutting, tlie upper for imparting 
 rigidity. The plane irons of adze blocks for machine work are always 
 single and 12 in. or 15 in. wide. Though denominated irons they are of 
 course always faced with best steel. 
 
 Planer, — The workman who gives his attendance to a planing machine 
 (q.v.) for metal. He sets and fixes the work, regulates the feed, often 
 grinds his own tools, and keeps the machine in order. His wages are 
 those of a machinist (q.v.). 
 
 Planer Bar. — A rigid bar of iron or steel carried horizontally in, and 
 standing out from the front of the tool box of a planing machine. Its 
 use is in planing the interior of hollow works, the cutting tool being 
 clamped in the end of the bar farthest from the tool box, the bar entering 
 into narrow spaces where the tool box could not find admittance. 
 
 Planer Centres. — See Loose Centres. 
 
 Plane Surface. — A surface whose points are all on the same level. To 
 obtain such surfaces the chisel and file, the plane, and planing and 
 shaping machines, and scrapers are used, and to test their accuracy, 
 winding strips, straight edges, and surface plates are employed. It is 
 possible to obtain such accuracy that when two heavy metallic plates 
 are placed in contact, the upper will sustain the lower, even in vacuo. 
 
 Planing. — The removal of material from plane surfaces hy means of 
 cutting tools, effected in the case of wood by hand tools, and in the case 
 of wood in large quantities and of metal, in planing machines (q.v.). 
 
 Planing Machine. — (1 ) For wood. A machine in which the cutting tools are 
 either arranged to project from the face of a disc, or around a rect- 
 angular adze block. In the former case they are augur-like inform and 
 rotate in a plane parallel with the face of the wood ; in the latter they 
 rotate in a plane at right angles with that face. The forms and 
 dimensions of planing machines vary much, and there are some machines 
 in which the cutters do not revolve at aU hut are.set in an iron block, 
 and the wood is literally planed as if by hand, with this difference, that 
 while in hand planing the tool is traversed over the wood, in the type 
 of machine here referred to the timber is passed over a fixed iron. 
 Kumerous modifications of planing machines are made. Panel-planing 
 and thicknessing machines are used for surfacing and planing small 
 pieces of stufi: to uniform thickness, and are used in pattern making. 
 (2) The machine for iron planing consists of bed, travelling table, 
 standards, cross slide, tool box, and gearing ; by which metal to be 
 operated on is carried underneath a fixed cutter, the cutter moving only 
 after the termination of a cut by a distance equal to the amount of feed 
 (q.v.), usually automatic, which is imparted to it. The wheel-spoke 
 planing machine is constructed for the purpose of planing the edges 
 of the spokes of railway wheels. 
 
 Planishing. — The smoothing and polishing of metallic surfaces hy ham- 
 mering or by rolling, instead of by abrasion or cutting. Shafting is very 
 commonly planished instead of being turned. 
 
 Planishing Hammer. — A machine -driven hammer used for planishiag 
 plates of sheet metal, and capable of deliveiing as many as three 
 hundred blows a minute. 
 
 Plank. — A piece of timber more than nine inches in width . Planking is used 
 as a general term to signify timber over about two inches in thickness, 
 and of any width over nine inches, to distinguish it from board (q.v.). 
 
 Plank Way. — When work is cut from board or plank in such a way that 
 the out edges stand approximately at right angles with the face of the 
 
MECHANICAL ENGINEERING. 259 
 
 timber it is said to be cut plank way of tbe grain, as opposed to end 
 grain. 
 
 Planometer. — Tho older name for a snrface plate (q.v.)' 
 
 Plan Section, or Sectional Plan. — A section (q.v.) taken in a, horizontal 
 plane in tke drawing of an object. 
 
 Plant. — ^Plant comprises the machines, tools, forges, furnaces, benches, 
 cranes, &o. of a faotoiy. Eailway plant is the rolling-stock and per- 
 manent way. 
 
 Plaster of Paris. — ^Plaster of Paris is used for maldng the reverse im- 
 pressions of some founders' moulds, for making the whole or portions 
 of some intricate and ornamental patterns and core-boxes, and as 
 bomontague (q.v.) for pattern work. 
 
 Plate. — ^A broad, thin sheet of metal. Plates being rolled, the fibre is 
 developed in the longitudinal direction, in which direction therefore 
 they are best able to resist tensile stress. There are limiting sizes and 
 weights for plates in iron and steel. The thicknesses of plates in these 
 materials are given iu inches and fractions of an inch ; that of brass 
 plates and of iron plates or sheets (q.v.) for tinning is given in B.'W.Gr. 
 Rolled plates of malleable iron, above No. 4 B.'W.&., or '238 of an inch 
 in thiclmess, are called plates to distinguish them from sheets (q.v.). 
 See also Pish Plate, Horn Plates, Plate Moulding, &c. 
 
 Plate-bending ISachine, — A machiue used for bending boiler and other 
 plates to various curves. It consists of three rolls having their bearings in 
 housings, the top roU being capable of adjustment for distance from the 
 others, by which adjustment provision is made for the different curves to 
 be imparted to the plates ; diminishing the centres increasing the curva- 
 ture of the plates, increasing the centres diminishing the curvature. 
 
 Plate Box. — A foundry flask used for plate moulding. 
 
 Plate Dowels. — Patternmakers' metallio dowels, in which the male and 
 female portions axe carried on thin rectangular plates which are sunk 
 flush into the jointed surfaces of the patterns, and there screwed fast. 
 They are the best dowels because they are less liable to be shifted by 
 rough usage than the peg and cup, or the wooden dowels. When 
 small they are sometimes made in brass, but the majority are made 
 in malleable cast-iron. 
 
 Plate-edge Planing Machine. — A special metal-planing machine used for 
 truing the edges of the wrought-iron and steel plates employed in 
 boiler and girder work. It differs from ordinary machines in this, 
 that the tool travels while the table remains fixed, and that the box 
 which traverses the tool over the work moves along th'e side of the 
 machine. The tool box is traversed by a double-threaded screw of 
 coarse pitch, and quick return is given by pulleys of unequal size 
 driven by open and crossed belts. 
 
 Plate-flattening Machine. — A form of straightening machine (q.v.) for 
 plates, which contains a larger number of rolls than the ordinary form, 
 seven rolls being employed, four above and three beneath, by passing 
 between which, the plates are rendered perfectly flat and true. 
 
 Plate Furnace, — A reverberatory furnace, used in boilermakers' and 
 platers' sheds for the purpose of heating plates preparatory to flanging, 
 bending, and welding. 
 
 Plate Gauge. — ^A thin, flat metal gauge, used for measuring spaces for 
 which the ordinary cylindrical gauges would be too weak, owing to 
 the smaUness of the dimensions measured. The thicknesses of plate 
 gauges range from about ith to j^th of an inch. 
 
i60 DICTIONARY OF TERMS USED Itf 
 
 Plate Girders. — Girders of wrought iron built up of a central plate or 
 web, riveted to top and bottom flanges by means of angle-irons riveted 
 alike to the plate and to tbe flanges. 
 
 Plate Link Chain. — A chain formed of flat links united with pins passing 
 through holes near the ends of the links. Suspension chains, and chains 
 for heaving up slips, are made of flat links. The lengths of the links 
 vary with the purpose for which they are to be employed. 
 
 Plate Metal. — See Refined Iron. 
 
 Plate Mill, or Plate KoUs. — A rolling miU similar in design to mill rolls 
 (q.v.), the place of the grooved cylinders in the latter being taken by 
 plain cylinders. They consist of roughing, and finishing rolls, the 
 former being grain rolls (q.v.), the latter chilled rolls. 
 
 Plate Moulding. — A process by which the labour of ramming up patterns 
 in sand is lessened. The opposite halves of the pattern are laid upon 
 metal plates in such a position that when two moulding boxes are 
 rammed, each on the separate plates and then brought together, the 
 opposite portions of the moulds correspond exactly, frequently the 
 plates are manipulated by a moulding machine (q.v.). 
 
 Platen, — (1) The table of a planing machine for metal which traverses 
 the work under the tool. So named after the platen of a printing 
 machine. (2) The table of a moulding machine (q. v.) . 
 
 Plater. — A boilermaker who devotes himself exclusively to that branch 
 of work which consists of marking out, cutting, and punching the iron 
 or steel plates which are used in the construction of boilers, girders, 
 bridges, and similar structures. 
 
 Plate Eolls.— See Plate MiU. 
 
 Plate-shearing Machine.— A shearing machine furnished with specially 
 long knives or shears for the purpose of cutting off the ragged edges 
 of plates after they leave the roUs. The knives may average four or 
 five feet in length. 
 
 Platform. — The planking attached to the sides of a crab (q.v.) or a 
 gantry (q.v.), upon which the man stands to work the handles of the 
 levers. The platform of a steam crab is usually termed a foot plate 
 and is made in metal. 
 
 Platform Crane. — A whip crane (q.v.) which is independent of any 
 support at the top of the post, hence termed independent whip crane. 
 It is held firmly on a very broad cast-iron base. The rope and chain 
 barrels are carried on a post of cast, or of wrought iron, stepped into the 
 base. 
 
 Platform Scale. — A small weighbridge (q.v.). 
 
 Plating. — The special work of the plater (q.v.). 
 
 Play, or Slackness. — Freedom of movement of bearing or working parts, 
 but confined within certain definite hmits. The purpose of giving this 
 freedom is to prevent jamming of parts, by heating or by oscillation or 
 other causes. See End Play. 
 
 Pliers, or Plyers. — ^A pincer-fike tool, having broad and flat roughened 
 jaws, and employed by fitters, smiths, and metal workers generally 
 for the grasping of wire or slight iron rods. Wire pliers are used for 
 bending wire intx) loops and other shapes, nipping pliers are used for 
 cutting, smiths' pliers are employed for grasping work indiscriminately. 
 
 Plomber Block. — A plummer block( q.v.) 
 
 Plomer Block. — A plummer block (q.v.). 
 
 Plommer Block. — A plummer block (q.v.). 
 
 Plotting. — The laying down of the lines of diagrams which are made 
 
MECHANICAL ENGINEERING. i6i 
 
 ■with a view to the calculations of strains, &c., by the graphic methof" 
 alone. 
 
 Flough. — A woodworker's plane used for grooving out the recesses for 
 tongueing and for panels. It is guided to its work by a fence, and the 
 depth of the cut is also controlled by a fence, adjustable with a screw. 
 
 Plug. — (1) The plug of a cock is the inner movable portion, which on 
 being turned allows free passage to the liquid. (2) An arbor or chuck 
 used as an intermediary attachment for small lathe drill chucks. It fits 
 into a tapered hole in the back of the actual chuck at the one end and 
 into the tapered mandrel nose at the other. (3) A sand plug or clay 
 plug is a term apphed to the baU of sand or clay with which the riser 
 (q.v.) of a mould is covered while the metal is being poured at the 
 ingate. Its purpose is to check the too rapid rushing of the air out of 
 the mould before the advancing metal, which would be liable to result 
 in a washing away of some portions of the sand. The plug is either 
 floated up by the rise of the metal, or more properly the moulder 
 removes it when he sees that the mould is nearly full. 
 
 Plug Centre Bit. — A centre bit having a cylindrical centre instead of a 
 point. Used for the enlargement of small holes already bored in wood. 
 
 Plug Cock. — A cock in which the fluid passes through a central plug, 
 which by being made to revolve in its circular plane presents either its 
 blank surface, or a passage through its body, to the flow of liquid. So 
 named in contradistinction to valve cocks. The taper of plugs should 
 not be less than one in sis, or more than one in four. 
 
 Plug Gauge. — See Cylindrical Gauge. 
 
 Plug Rod. — A plug tree (q.v.). 
 
 Plug Tap. — A parallel screw tap used for taking the finishing cuts on 
 internal screws. 
 
 Plug Tree. — A long rod suspended from the beams of old-fashioned 
 single-acting piunping engines, and provided with tappets for moving 
 the handles of the equilibrium and steam exhaust valves. 
 
 Plumb. — In a vertical position. The position assumed by a weighted 
 cord at rest. 
 
 Plumbago, or Graphite. — A nearly pure form of carbon used for foundry 
 blacking, and mixed with clay for crucibles. It is smooth and soapy 
 to the touch, and is highly refractory. 
 
 Plumbago Blacking. — See Plumbago. Blacking. 
 
 Plumbago Crucibles. — Crucibles in which plumbago is the chief ingredient 
 present. They contain only so much clay as is necessary to afford the 
 requisite amount of plasticity, and are employed in preference to those 
 made entirely of clay, where great heat or excessive alternations of tem- 
 perature exist. 
 
 Plumb Bob. — A pear-shaped or globular weight suspended from the end 
 of a plumb-line (q.v.). ITor engineer's work its lower end terminates 
 in a point for the purpose of indicating the exact centre of the plumb- 
 line. 
 
 Plumber Block. — A plummer block (q.v.). 
 
 Plumb Line. — A line or string sustaining a plumb bob, and used either 
 alone or in conjunction with a straight-edge to ascertain the exact 
 vertical position of portions of structures. It is employed chiefly in the 
 erecting department. 
 
 Flummer Block. — Variously spelt plomber, plomer, plonijner, plumber. 
 The ordinary form of pedestal for carrying the journal of a shaft. It 
 consists of 3, b^se or body, eonietimes termed a pillow, and ^ cap enclos- 
 
262 DICTIONARY OF TERMS USED IN 
 
 ing a pair of brasses. The foot of the block is prolonged to receivo 
 hold-do-wn bolts, and the bolting down of the cap secures the brasses in. 
 place. Lubrication is provided for at the top, through a hole drilled 
 in the cap and top brass. 
 
 Plunger. — The piston or ram of a force pump. Being soKd it draws the 
 water by producing a vacuum, and delivers it by its forcing or displacing 
 action. 
 
 Plunger Air Pump. — An air pump fitted with a solid plunger or piston. 
 
 Plunger Bucket. — A force-pump piston having no valves. 
 
 Plunger Pump. — See Force Pump. 
 
 Ply. — To bend. A fold, a twist, a single thickness of a material, as a 
 ply of wire gauze, three ply, four ply cotton belting', meaning three 
 and four thicknesses respectively. 
 
 Plyers. — See Pliers. 
 
 Pneumatic Lift. — See Compressed Air Lift. 
 
 Pneumatic Moulding Machine. — A moulding machine in which the pres- 
 sure on the sand is imparted by means of an air bag (q.v.), instead of by 
 a rigid platen. 
 
 Pneumatic Process. — The Bessemer process (q.v.). 
 
 Pneumatics. — Pneumatics treat of the properties of elastic fluids, as air, 
 steam, gas. 
 
 Pocket Print. — A long or drop print used for coring holes in the sides of 
 castings where a round print would not be available, by reason of the 
 superimposed sand preventing it from lifting. The pocket print being 
 therefore prolonged to the surface of the mould, the upper part of the 
 print impression is filled up or " stopped over " with sand after the 
 core has been dropped in. 
 
 Pockets. — (1) Curved plates inserted into, and standing out from the 
 sides of the flue of a Galloway boiler in positions intermediate with 
 those occupied by the Galloway tubes. Their use is to throw the flame 
 among the tubes, and so increase the economy and effieiency of the 
 boiler. (2) Recessed portions of a casting provided for the reception of 
 timber or girder ends. 
 
 Podger. — See Tommy. 
 
 Point, or Switch. — A movable rail by which the direction of an engine 
 or wagon is changed from one set of rails to another. 
 
 Point Bail. — A movable rail or switch. Also called a point simply. 
 
 Point. — This word has several significations, which are treated under their 
 several headings, as Boiling Point, Fusiag Point, &c. 
 
 Point Tool. — A diamond point (q.v.) . 
 
 Poker riling. — See Draw Piling. 
 
 Pole Lathe. — The primitive form of lathe. So called because each down- 
 ward movement of the treadle was made to impart a similar movement 
 to the end of an elastic pole iixed horizontally overhead. A cord slung 
 from the pole was turned round the work and rotated it towards the 
 tool. On the release of the treadle the work was rotated in the oppo- 
 site direction. Hence half the time was lost in the return movement, 
 and the tool had to be drawn away after each cut. The pole lathe is 
 stUl in use in some Eastern countries. 
 
 Poling. — The stirring of molten copper with a pole of green wood, usually 
 birch, in order to bring it to tough pitch (q.v.). The effect of poling is 
 to remove the oxygen which is present as a suboxide of copper, and 
 which renders the metal brittle or " dry." The oxygen combines with 
 the g9,ses liberated from the burning wood, If the poling is not carried 
 
MECHANICAL ENGINEERING. 263 
 
 on to a auffioient extent the metal is brittle, and is said to be imder- 
 poled, if it is carried too far the effect is einular, but it is then said to 
 be overpoled. 
 
 Polishing Headstook. — A polishing lathe (q.v.). 
 
 Polishing Lathe, or Polishing Head. — A mandrel and pulley driven at a 
 high speed and carrying small emery or buff wheels for polishing light 
 ■work. It is mounted on a small head or standard, which is bolted to a 
 bench or other smtable support. 
 
 Polishing Stick. — ^A couple of strips of wood used -with emery for 
 poKshmg work while revolving in the lathe. The ends farthest 
 from the workman are united with hinges, those nearest him serve aa 
 handles, by which the strips are made to embrace the work tightly. 
 The opposed faces of the sticks are hollowed out where they embrace 
 the work, emery cloth or powder intervening. This is therefore an 
 external lap. See Lap. 
 
 Polishing Wheel. — A buff wheel or buff (q.v.) used for finishing bright 
 work. See Pohshing Lathe. 
 
 PoU. — The larger or broad end of a hammer as distinguished from the 
 pane (q.v.). 
 
 Polygon. — A plane figure bounded by many right lines. A regular poly- 
 gon has its sides and angles equal. In an irregular polygon the reverse 
 condition obtains. The number of sides in a polygon is indicated by 
 the prefixes penta, hexa, &c. 
 
 Polygon of Forces. — An expansion of the triangle of forces (q.v.), and 
 which may be thus stated : — If any number of forces be represented in 
 magnitude and direction by the sides of a polygon taken in order they 
 will be in equilibrium. 
 
 Polygons, Line of. — One of the sectorial scales by means of which any 
 regular polygon can be described according to the number, four-, five, 
 six, seven, eight &o., on the line marked pol. To set out a polygon, 
 open the leg.i of the sector until the divisions marked six correspond in 
 distance aparb with the radius of the ciroumsoribing circle. Then the 
 distance apart of four will represent the sides of a square, five of a 
 pentagon, six of a hexagon, and so on. Conversely, having the 
 length of the sides of a polygon given, open the legs until the distance 
 apart of the figures representing the side of the particular polygon 
 required corresponds with the length of the side. Then the distance 
 between the fignrres six wiU be the radius of the circle to contain the 
 required number of sides. 
 
 Popit. — A Poppet (q.v.). 
 
 Poplar. (FojmIus.) — A tree of the natural order Saliccweai. The wood 
 is soft, white, and light. Poplar wood is used chiefly for brake blocks 
 (q.v.). Sp. gi'. "39. A cubic foot weighs twenty-four pounds. 
 
 Poppet, Poppit, or Popit. — The movable headstock of a lathe, upon the 
 point of whose mandrel, work placed between centres is made to 
 revolve. 
 
 Poppet Cylinder. — The mandrel of the poppet of a lathe. It is made 
 cylindrical in order to allow the traversing screw to move freely 
 through its interior. 
 
 Poppet Head. — A poppet (q.v.) 
 
 Poppit. — A poppet (q.v.). 
 
 Ports. — The passages or steamways through which the steam gams 
 admission to the interior of an engine cylinder, and through which it 
 also returns to the exhaust passage. 
 
264 DICTIONARY OF TERMS USED IN 
 
 Portability. — This is carried into extensive practice in engine work 
 and macMnery. See Portable Engine, Portable Forge, &o. 
 
 Portable Crane. — A crane constructed to travel about upon tram rails. 
 It may be worked either by hand or by steam. 
 
 Portable Engine. — Portable engines are used chiefly for agricultural 
 purposes, but they are useful for outdoor and contractors' work, and 
 for work of a temporary character. They are built on the locomotive 
 type with multitvibular boilers for high pressures. 
 
 Portable Forge. — A small forge supported on a light framing of wrought 
 iron between which the bellows are situated. It is removable at 
 pleasure, and is therefore used for outdoor and repair work. 
 
 Portable Vice. — An engineer's vice supported on a central pillar, base, 
 and wheels. 
 
 Portable Winch. — A winch (q.v.) placed upon wheels for convenience of 
 removal about contractors' yards, on ship board, or in other places 
 where the work required to be done cannot be localised^ 
 
 Porter. — The bar of iron which the smith holds in his hand when mani- 
 pulating a forging. In fagoted work the porter is a single bar, 
 longer than the rest and standing out from the mass. In ordinary 
 single bars the porter is the end which the smith happens to hold in his 
 hand. 
 
 Port Holes. — ^Ports (q.v.). 
 
 Portland Cement. — Used sometimes for making the socketed joints of 
 hot-water pipes, an india-rubber ring being first inserted. 
 
 Porty. — A print (q.v.) of large diameter is often termed by pipemakers a 
 porty. 
 
 Positive. — A positive motion or a positive stroke signifies that which is 
 precise and exact, in opposition to that which is not so precise or exact, 
 but only approximately so. Thus the stroke of an ordinary planing 
 machine being accomplished by the airl of shifting bands is not precise ; 
 but that of shaping machines, being effect d by a rigid though adjust- 
 able connecting rod, is poe'tive. Hence a pos'tive stroke is one that is 
 direct, a non-positive is one in which a oerta'n amount of elasticity, or 
 sUp, or lost motion comes ii to play. 
 
 Positive Stroke. — See Positive. 
 
 Positive Stresses. — In English practice are those which represent com- 
 pression. 
 
 Positive Terms. — Algebraical or arithmetical terms preceded by the -}- 
 sign ; terms preceded by no sign are also understood to be positive. 
 
 Post. — An upright timber, as a king post, a pillar, or column, a crane 
 post, &o. 
 
 Pot. — A crucible. 
 
 Potash, Yellow Prussiate of. — The ferrooyanide of potash, symbol K4 
 FeCe Ne, largely employed by smiths for the purpose of case-hardening 
 (q.v.), and in the process of making draughtsman's phototypes (q.v.). 
 
 Potatoes. — Used to prevent incrustation of boilers. 
 
 Potential Energy. — See Energy. 
 
 Pot Lid Valve. — A hoUow cup-shaped Kft valve. 
 
 Pot Metal. — Used for some cheap brass goods, variously composed of 
 copper sixteen, lead six to eight parts, the latter amount giving an 
 inferior quahty, and being called wet pot metal, because the lead 
 partially oozes out in cooling. Tin, zinc, and antimony in small quantities 
 are sometimes added with the view of improving the alloy. 
 
 Pot Sleeper. — A combined railway sleeper and chair, the chair being 
 
MECHANICAL ENGINEERING. 265 
 
 njually cast on the top of abroad dome-shaped base, which is the actual 
 sleeper. The gauge is maintained bj cross-tie rods, and the rai's 
 attached in the usual -way with keys. They are used in hot countries 
 chiefly, where timber sleepers would be liable to decay, and to suffer 
 from the destructive agencies of insects. 
 
 Pot Valve. — A safety valve, shaped like an inverted pot. It is a lift 
 valve, and the conical pivot of the lever drops loosely into a recess in 
 the crown of the pot. The advantage claimed is that such valves being 
 in a condition of unstable eqiiilibrium are less liable to stick than the 
 ordinary form. The lift of the valve is controlled and maiutained by 
 guides cast on the top of the seating. 
 
 Found. — The English pound is a tenth part of a gallon of distilled water 
 at 62^ F., and 30 in. barometric pressure. 
 
 Found Degree. — A thermal unit which denotes the quantity of heat 
 necessary to raise a pound of water through one degree of tempera- 
 ture. It is a pound degree Centigrade, or a pound degree Fahrenheit, 
 according to the thermometric scale used. Unless stated to the contrary 
 the latter is always understood. The latter is equivalent to the com- 
 mon unit of heat, being 772 ft. pounds; the former is a bastard unit 
 only derived from the other. 
 
 Fouring. — The emptying of the molten metal into a foundry mould. 
 
 Pouring Gate. — An ingate (q.v.). 
 
 Power. — (1) A term of general application signifying the actuating of 
 motors by agencies other than those supplied by animal power. Steam, 
 water, air, gas, &c., are power agencies. (2) The expression of the 
 number of times by which a number is multiplied into itself. 
 
 Power Feed. — The feed (q.v.) of a lathe, planing, scre-ndng, or other 
 machine, which is effected automatically by the agency of the motive 
 power which drives the machine itself. 
 
 Power Gear. — Gear, usually understood of the toothed form, which is 
 worked by power (q.v.). 
 
 Power Lift. — A lift (qv.) worked from any convenient source of power, as 
 a gas or steam engine. 
 
 Power MaoMne. — A machine actuated by a motor (q.v.), as distinguished 
 from a hand- worked machine. 
 
 Power of Animals. — The power of animals, as deduced by experiment, is 
 of use in calculations connected with those machines which are worked 
 by animals, as horse and mule gear, pumps, &c. 
 
 Power of Men. — The power of men varies greatly with the manner in 
 which it is exerted. Por practical calculations certain values are 
 accepted. 
 
 Preadmission. — The admission of steam to an engine cylinder just previous 
 to the termination of the stroke in the opposite direction. The amount 
 of preadmission is governed by the lead (q. v. ) it should be sufficient in 
 quantity to allow the steam to acquire its full pressure immediately on 
 the return stroke of the piston. 
 
 Prerelease. — The opening of a steam cylinder to exhaust just before the 
 termination of the piston stroke, to prevent injurious and wasteful 
 back pressiu;e (q.v.). 
 
 Press Drill. — An old-fashioned form of drilling machine, in which the 
 drill is pressed down to the work by a weighted lever. 
 
 Presser. — That portion of a moulding machine which imparts the neces- 
 sary pressure to the moulding sand. 
 
 Prese Tit. — A fitting of contiguous parts slightly tighter than a sliding fit 
 
i66 DICTIONARY OF TERMS USED IN 
 
 (q.T.), to alloTv of the sliding parts being pressed together with a 
 hydraulio press. 
 
 Pressing. — See Stamping. 
 
 Pressure. — A compressing force •which does not produce motion but 
 imparts stress. Steam pressures are measured in lbs. per square inch, 
 or inches of mercury. Water pressures are measured in lbs. per square 
 inch or in the equivalent "head " (q.v.), and sometimes in atmospheres. 
 
 Pressure Blower. — This is used to denote a blower (q.v.) of rotary type, 
 as opposed to a fan, the former producing a definite and constant 
 amount of positive pressure, while the latter acts by displacement only. 
 
 Pressure Forging. — The practice of stamping forged works by gentle 
 hydraulic pressure, instead of by the impact of a steam hammer. See 
 Hydraulic Forging Press. 
 
 Pressure Gauge. — The dial gauge attached to a boiler or other vessel by 
 which the pressure of the steam or hquid within is indicated. A curved 
 spring within the body of the gauge actuates the pointer. Steam 
 gauges register up to about 200 lbs. per inch, but water gauges are 
 made for very much higher pressures, ranging to several tons per 
 square inch. 
 
 Pressure, lines of. — The vertical or approximately vertical lines enclosed 
 by an indicator diagram, or a diagram of work. 
 
 Pressure Bam. — The larger of the two in a hydraulic forging press, and 
 which imparts the necessary downward force. 
 
 Pricker. — A vent wire (q.v.). 
 
 Prime. — A number which is only divisible by itself, or by unity. See 
 Hunting Cog and prime numbers in Appendix. 
 
 Prime Mover. — Any piece of mechanism which absorbs and gives out 
 again the material forces of nature, whether the expansive energy of 
 steam or gas, or the pressure of water, air, or wind, &o. 
 
 Priming. — (1) In steam boilers, is the carrying of mechanically suspended 
 particles of water along with the steam into the steam chambers and 
 pipes. It is due to various causes, as irregular withdrawal of the 
 steam, the presence of oil and grease in the water, want of proper 
 circulation, &c. Sometimes called foaming. (2) The priming of a 
 force piunp is the expulsion of the air from the water space, in order 
 that the water shall enter into the partial vacuum thus produced. 
 Usually it is effected by the opening of a pet cook placed in the highest 
 portion into which air can enter, which is opened to permit of escape of 
 air, but closed by the finger to prevent its return. This is repeated 
 until the water fiUs up and begins to be ejected from the cock. (3) The 
 fetching of a lift pump by pouring liquid into the bucket in order to 
 produce sufficient vacuum to enable it to draw. 
 
 Priming Valve. — The valve which affords the means of escape for the 
 water of condensation in engine cylinders. A pet cock (q.v.). 
 
 Principals. — See Rafters. 
 
 Print. — A projection put upon a foundry pattern to indicate the position 
 of a cored hole, and to foi-m an impression to receive the end of the core. 
 Prints are commonly weU tapered to withdraw easily, and those portions 
 of the cores which are placed in the print impressions are filed to 
 correspond. Prints are of various shapes, depending on the shape of 
 their cores. At the sides of patterns, pocket prints (q.v.) and parallel 
 prints (q.v.) are used. 
 
 Printing Frame, or Copying Frame. — A frame in which phototypes are 
 copied. It consists of a stout oblong frame of wood, about four inches 
 
MECHANICAL ENGINEERING. 267 
 
 aeep and from two to four feet in length, according to tlie sizes of paper 
 used. A thick sheet of plate glass is laid on fillets in the bottom of the 
 frame, through which the light penetrates to the sensitised paper. A 
 back board or boards cover the paper and a thickness of felt, and these 
 ajre kept in place by means of springs attached to cross ribs hinged to 
 one side of the frame and folded over and clamped down on the other. 
 The whole frame is mounted on rollers to run on rails carrying it 
 through a window outside into the light. 
 
 Prising. — Barring round or turning round a wheel or wheels with a 
 crowbar. 
 
 Frism. — A solid whose ends are plane figures equal and parallel, and 
 whose sides are plane parallelograms. 
 
 Problem. — A construction which is capable of being efEeoted by the 
 employment of principles of construction already admitted or proved. 
 
 Prod. — The pyramidal or conical points cast on loam and core plates for 
 the retention of the loam are termed prods. 
 
 Producer. — See Gas Producer. 
 
 Producer Gas, or Gaseous Fuel. — A mixture of combustible gases con- 
 sisting chiefly of CO and hydrogen, and CO2, which is prepared by the 
 combustion of fuel apart from the furnaces to be heated. The gases, 
 after passing from the gas producer furnace, are heated in regenerators 
 and mingle and bum on their furnace hearth with atmospheric air 
 similarly heated. Producer gas is prepared from inferior fuel, but 
 chiefly from bituminous coal, and by its employment a saving of fuel 
 is effected, a uniform and more regulable heat obtained, a diminished 
 loss from oxidation of the iron and steel reheated, furnace linings saved, 
 and a great economy generally obtained over the older methods. 
 
 Product. — The sum produced by the multiplying together of two or more 
 factors. 
 
 Products of Combustion. — Chiefly carbonic acid and carbonic oxide and 
 water. The former are utflised in many ways ; in blast furnaces, 
 gas engines, regenerative furnaces, &c., described under their several 
 heads. 
 
 Profiling. — The grinding and sharpening of a cutter for working wood or 
 metal, so that the outline of the cutting edge is that of the section 
 which it is desired to impart to the material. 
 
 Progression. — The succession of one number after another by virtue of 
 some definite law. Arithmetical progression is a series of numbers 
 that increase or diminish by a common difference, as seven, ten, 
 thirteen, sixteen, cfec. In geometrical progression each term of the 
 series is equal to that which precedes it midtiplied by some factor which 
 is constant for all the terms. Thus two, six, eighteen, iifty-four are in 
 geometrical series. 
 
 Projection. — Signifies in a general sense the representation on a plane sur- 
 face of objects as they appear to the eye of an observer, the various 
 kinds of projection being differentlynamed according to the position occu- 
 pied by the observer ; perspective, stenographic, isometric, gnomonic, 
 and orthographic are projections, but in the working drawings of the 
 engineer the latter alone is used. In this the eye is supposed to be at 
 an infinite distance, and the visual rays are all parallel. Hence such 
 drawings are suitable for direct measurement, and according as the 
 objects are viewed the terms plan, elevation, section are employed. 
 
 Prong Chuck. — A fork-Hke chuck, whose prongs revolve wood set 
 between lathe centres, 
 
268 DICTIONARY OF TERMS USED IN 
 
 Prong Key. — A kind of spanner used for tightening up circular nuts by 
 power applied to their faces. Two projections or prongs on the front 
 face of the spanner fit two corresponding holes in the nut faces, the 
 leverage being applied to a handle attached to the spanner. 
 
 Proof Bar. — The loose bar which is thrust through a hole in the trough 
 which contains steel undergoing the process of cementation, and which 
 is removed from time to time to enable the attendant to judge of the 
 progress of the operation. 
 
 Proof Load, or Test Load. — A load imposed on a structure greater in 
 amount than the working load, in order to test its capability or margin 
 of safety. The deflection of a structure, when under its test load, 
 is carefully noted and its capability deduced therefrom. See Proof 
 Strain. 
 
 Proof Strain. — Any strain to which a portion of material, or a structure, 
 or a section of structure, is subjected, in order to test its suitability for 
 the specific purpose for which it is designed to be used. A proof strain 
 would in all cases be short of that which would have a crippling effect, 
 assuming of course that the material were good, but also above that 
 which it would be expected to sustain in the ordinary conditions to 
 which it would be subject. 
 
 Propeller, or Propeller Screw. — The helical segments used for the pro- 
 pulsion of steam vessels. Propellers are two, three, or four bladed, 
 according as they form segments of two, three, or four different screws. 
 
 Propeller Blade. — A single segment of a propeller (q.v.). 
 
 Propeller Screw. — See Propeller. 
 
 Proportion. — See Ratio. 
 
 Proportional Compasses. — A compass (q.v.) for drawing purposes which 
 is provided with two slotted and double-ended legs united by a sliding 
 pivot and screw, by the regulation of whose position th? distance apart 
 of the extreme points may be adjusted within a very wide range. By 
 its employment distances and drawings may be enlarged or reduced 
 proportionally, polygons of circles and square and cube roots of 
 numbers can be obtained rapidly without calculation. 
 
 Proportioning. — The proper proportioning of machine parts is the 
 business of the engineer. But although a correct knowledge of the 
 strength of materials and the nature and amount of strain and stress 
 set up in structures is essential, there are few or no machines designed 
 on strictly mathematical data. The art of proportioning consists in 
 combining theory with experience, and these with an intuitive sense of 
 fitness and beauty, in one harmonious result. So largely does experience 
 enter into the labour of the engineer that there are few who are able, in 
 spite of excellent theoretical knowledge, to enter successfully into the 
 task of designing and proportioning works of a totally difEerent class 
 from those to which they have been accustomed. 
 
 Protracting. — The laying down of angles with or without the assistance 
 of a protractor. 
 
 Protractor. — A drawing instrument used for laying down or for measuring 
 angles. It is made in several forms, rectangular, semicircular, and 
 circular, having the angles of, and divisions into degrees marked. These 
 beiag of small size are most useful in the drawing ofBees, or for the 
 smaller work in the shops. For large work a large wooden or card- 
 board instrument, or a line of chords (see Chords, Line of) is to be used 
 in preference, as being less Uable to produce errors in striking out. 
 
 Proud. — A word sometunes used by iron turners to designate a cuttingf 
 
MUCHAt^lCAL ENGINEERING. 269 
 
 tool 1: aving a large amount of top rake (q. v. ) . Thus a tool for the turning 
 of -wrought iron -would be too proud to turn steel or gun-metal. 
 
 Proving MaoMne. — A testing machine (q.v.). 
 
 Prussian Blue The colour used to distinguish -wrought iron on sectional 
 
 dra-wings. 
 
 Prussiate Bath. — See Phototype, YeUo-w Bath. 
 
 Puddle Ball. — A mass of puddled iron as it lea-yes the puddHng furnace 
 (q.T.). 
 
 Puddled Bar, or Number One Iron. — The bar of malleable iron as it 
 leaves the last of the grooves in the finishing series of puddling rolls 
 (q.v.). It is not of merchantable value (see Merchant Iron), but is 
 piled, reheated, re-welded,and rolled to make marketable quaHties of iron. 
 
 Puddled Steel. — A steely iron (q.v.) produced in the puddling furnace by 
 so regulating the process that a portion of the carbon is allo-wed to 
 remain in combination. 
 
 Puddlers' Candles. — The term given to jets of carbonic oxide gas -which 
 issue from the surface of the molten metal in the pig boiling (q.v.) 
 process. They o-we their origin to the union of the oxygen in the tap 
 cinder with the carbon in the pig. 
 
 Puddlers' limine. — A mixture of a variety of red haematite and -water, 
 employed for the purpose of fettling puddling furnaces. It is smoothed 
 over the surface of the bull-dog (q.v.) lining. 
 
 Puddling. — The series of processes by -which the carbon and other foreign 
 substances present in pig iron are extracted therefrom previous to the 
 rolling of bars and plates for the use of the smith or plater. See Dry 
 Puddling, "Wet Puddling. 
 
 Puddling Furnace. — A reverberatory furnace (q.v.) in -which cast iron is 
 subjected to the action of the atmosphere to effect the removal of t] e 
 carbon and bring it into the condition of -wrought iron. Some puddlii g 
 furnaces are made double, two sets of men being employed, one set cu 
 each side at opposite -working doors. An iacrease in output and economy 
 of fuel are thus obtained. 
 
 Puddling Eolls, or Forge Train.— The first sets of roUs through -which a 
 shingled bloom is passed. The first or roughing rolls are grooved in 
 Gothic or \/-shaped channels and in diamond shape, the grooves 
 diminishing in depth from left to right along the rolls. Those to the 
 left are distingtdshed from the others as roughing rolls because there 
 the bloom is first embraced. The surfaces of the grooves are roughened 
 -with chisel niokings to take firm hold of the blooms. To the right 
 hand are the finishing rolls in -which the grooves are rectangular in 
 section to impart that section to the puddled bar. These grooves also 
 diminish in depth from left to right. 
 
 Pug Hill. — A mill used for the mixing of the materials of -which concrete 
 is composed. 
 
 Pulley, or Bigger. — The -wheel -which carries driving belts. It is made 
 cither in cast or -wrought iron and turned rounding upon the face. 
 
 Pulley Block. — A sheave pulley or series of pulleys having a hollo-w rim 
 section, and enclosed bet-ween metal side cheeks in -which the pulley 
 pins have their bearings, constitute a pulley block. A hook fastened 
 to the upper end furnishes the means of attachment to any convenient 
 point of support. Pulley blocks are single, double, or treble according 
 as they have one, t-wo, or three sheaves. 
 
 Pulley Lathe. — A special kind of machine used for boring and facing 
 pulleys. It consists of an inner ring furnished -with bolts for setting the 
 
2?d DICTIONARY OF TERMS VSBD IN 
 
 pulleys of different diameters central, and having its periphery turned 
 truly to revolve in a bored outer ring made fast to foundations. A 
 circle of teeth forms an integral portion of the periphery of the inner 
 ring, which teeth are driven by a pinion, on whose shaft are the 
 driving pulleys by which the ring is driven round. The pulleys are 
 bored and faced, but are transferred to an ordinary lathe to be turned. 
 
 Pulling Up. — The tearing up of the sand of a foundry mould by the 
 withdrawal of a badly made or non- tapered pattern. Pulling up from 
 the bottom means that the whole of the sand reaching upwards from 
 the lowermost edge of the pattern is pulled up, to distinguish it from 
 mere breaking of the sand along the edges. 
 
 Pump. — A machine for lifting or forcing liquid either by means of a 
 bucket, or of a piston working in a closed cylinder. See Force Pump, 
 Suction Pump. 
 
 Pump Barrel. — The closed cyHnder in which the bucket or the piston of 
 a pump moves. Barrels are variously made of cast iron lined with gTm- 
 metal, or gun-metal entirely, or glass, according to the liquids which 
 have to pass through them, or the price paid. 
 
 Pump Bit. — A bit for boring the cylinders of wooden pumps. 
 
 Pump Bob. — A bell crank, or rooking lever which converts rotary into 
 reciprocal motion. 
 
 Pump Bucket. — The piston of a lift pump. It differs from an ordinary 
 piston in being provided with an open central space or waterway (q.v.), 
 which is covered with a flap valve (q.v.), which valve opens when the 
 bucket is falling and closes when it is lilting. 
 
 Pump Case, or Pump Top. — The top of a Uft pump, or that part above the 
 working barrel (q.v.), which contains the handle, spout, and cover. 
 
 Pump Cup Leather. — See Cup Leather. 
 
 Pump Gear. — The various parts and connections of a pump. 
 
 Pump Head. — A sheet iron hood placed at the top of a chain pump to 
 prevent any of the discharge water being thrown off by centrifugal 
 force. 
 
 Pumping. — The term pumping is sometimes applied in the foundry to the 
 act of feeding (q. v.) , in allusion to the up and down movement of the 
 feeding rod in a vertical direction. 
 
 Pumping Crank. — A crank or disc to which a pump rod is attached. 
 
 Pumping Engine. — An engine employed for pumping purposes. For Kght 
 work, ordinary engines of horizontal or vertical types are employed, for 
 heavy pumping, beam engines are commonly used. 
 
 Pump Leather. — See Cup Leather. 
 
 Pump Eods.— The piston rods of pumps are made of various materials, but 
 chiefly copper and gun-metal, or Muntz metal, to prevent corrosion. 
 Air-pump rods are commonly made of iron for strength, and sheathed 
 with Muntz metal. The rods of deep well pumps are made of iron, and 
 cottared together in length, or are in some cases made of wood. See 
 Pump Spear. 
 
 Pump Spear. — A name given to the long wooden rods of deep well and 
 mining pumps. 
 
 Pump Top. — See Pump Case. 
 
 Punch. — A shearing instrument made of steel and employed for the 
 removal of a definite portion of metal, whose shape is the counterpart 
 of the shape of the punch. Punches are used in many classes of work, 
 and are actuated both by hand and by power. See also Brad Punch 
 and Centre Punch. 
 
MMCMANICAL ENGINEERItJG. 2?t 
 
 Pancned Holea. — Rivet holes are oommonly punched in plates for boiler, 
 bridge, and girder, and plated work generally. , Only in the best work 
 are they di'Uled. The holes are either marked direct with compasses, or 
 from a templet, and punched singly, the plates being moved by hand, 
 or in some cases automatically. The proper spacing-out of punched 
 holes is of the utmost importance, as preventing the injurious employ- 
 ment of the drift (q.v.). 
 
 Punched Plates. — Plates of wrought iron and mild steel are suitable for 
 punching ; hard steel is unsuitable. Plates which will not stand 
 piinching are too brittle for boiler and girder work. Punching involves, 
 under the most favourable circumstances, a loss of strength, due not 
 only to the diminution of sectional area, but to the detrusive action 
 straining the plates beyond their limit of elasticity. Hence punched 
 plates are sometimes annealed, or more frequently rymered out, it being 
 considered that the stresses due to punching are only present in the 
 immediate vicinity of the holes. The tensile strength of soft wrought- 
 iron plates is diminished from 5 to 10 per cent, by punching, while 
 that of steel plates is diminished from 20 to 28 per cent. 
 
 Punching. — The making of holes through plates under a punching ma- 
 chine. It is done in the boiler department usually by a plater (q.v.). 
 
 Punching Bear. — A portable punching machine. The punch is actuated 
 by a screw, or in some cases by hydjauKc pressure. 
 
 Punching Machine. — A machine in which the punch is actuated by 
 power. Commonly the processes of punching and shearing are com- 
 bined in one double-ended machine. 
 
 Punching Strength. — The strength necessary to punch plates of iron and 
 steel. It has been found by experience that the resistance of a wrought- 
 iron plate to punching is nearly the same as its resistance to tensile 
 strain. The resistance is measured by the area of the metal separated, 
 and the resistance increases directly as the thickness and strength of 
 plate and diameter of hole. Holes are punched in plate thinner than 
 the diameter of the punch, but seldom in plates whose thickness exceeds 
 that diameter. 
 
 Punch Pliers. — Pliers in which the cutting edge takes the form of an 
 aimular ring. They are used for punching the holes in leather belting. 
 
 Pupil, — Youths of from fourteen to sixteen years of age are articled as 
 pupUs to firms of engineers for periods ranging from two to five years, 
 during which time they pass through the various departments in turn, 
 and obtain some practical experience in each, at the same time that 
 they pursue theoretical studies at home. The premium payment 
 averages about £.tO a year. 
 
 Puppet, — A poppet (q.v.). 
 
 Puppet Valve. — A lift valve (q.v.). 
 
 Purchase. — A term used in workshops, and equivalent in its meaning to 
 leverage, more or less purchase meaning more or less leverage. 
 
 Pure Oil. — A simple oil which is not admixed with any other oil, as is 
 the case with compound oils (q.v.). 
 
 Pure Kuhher. — Applied to vidcanised india-rubber which is homogeneous 
 throughout, to distinguish it from insertion rubber (q.v.). 
 
 Purlins. — The members which unite the trusses of roofs in longitudinal 
 directions. 
 
 Purple. — The colour used to denote steel in engineers' drawings. 
 
 Pushing Poppet. — A poppet whose mandrel is moved in the forward 
 direction only by the thrust of the screw, but is slid back by hand. 
 
i?2 DICTtOlSrAkV OF TERMS USED IN 
 
 Pncvy. — Used in pattern-making for filling up the holes formed hy tha 
 heads of nails and the countersunk recesses for screw-heads. Called 
 Stopping', or Bomontague. 
 
 Pyramid Oil Can. — The small conical-shaped oil can for bench use. 
 
 Pyrometer. — See Pyrometer Gauge. 
 
 Pyrometer Gauge. — A dial gauge used for recording the heat of steam, 
 as well as its pressure; it is therefore a combination gauge (q.v.). 
 Another type of dial pyrometer gauge, depending for its value on the 
 expansion of metal rods or tubes, is used for testing the heat of blast 
 and other furnaces and ovens. 
 
 Q 
 
 Quadrant. — (1) The segment of worm wheel teeth on the upper portion of 
 the tool box of a shaping machine, which is made to curve through an 
 arc of a circle for hollow circular shaping. (2) A quarter circle bounded 
 by two radii at right angles to each other and by a corresponding por- 
 tion of the circumference. 
 
 Quadrant Compasses. — "Wing Compasses (q.v.). 
 
 Quadrant Plate, or Wheel Plate. — The plate which carries the stud 
 wheels in the change wheel series for screw cutting in the lathe. It is 
 hinged on the end of the leading screw, and is provided with two parallel 
 slits for carrying the stud or studs for the intermediate wheals. Being 
 thus hinged, the studs with their wheels can be brought into almost any 
 desired position in relation to the wheels on the mandrel and on the 
 guide screw. 
 
 Quadruple Expansion Engine. — A compound engine in which steam is 
 expanded four times ; first in a high-pressure cylinder, and afterwards 
 in three low-pressure cylinders in succession. A goodly number of en- 
 gines have now been constructed on this principle, but necessarily it 
 means high initial pressures, or from 150 lbs. to 180 lbs. 
 
 Quarter Bend. — A pipe bend which makes an arc of 90°, and is used there- 
 fore for connecting pipes at right angles with each olhar. 
 
 Quartering. — (1) The adjustment of cranks or crank pin holes at right 
 angles with each other. (2) Deals cut into strips of four to the deal. 
 Also called scantling (q.v.). 
 
 Quartering Belt. — Half crossed belting (q.v.). 
 
 Quartering Machine. — A boring machine for accurately boring out the 
 crank pin holes in locomotive wheels, after the wheels have been fixed on 
 their axles. 
 
 Quarter Kip Saw. — A handsaw (q.v.). 
 
 Queen Post. — A roof member which fulfils a similar fimction to that of 
 the king post (q.v.), its position only being different. Queen po.sts 
 occupy positions placed between the king posts and the ends of the roof 
 truss. 
 
 Quenched. — Wlien steel is heated for hardening or tempering, and then 
 dipped into water or oil, it is said to be quenched. 
 
 Quenching. — The act of dipping steel rapidly into water, oil, or other 
 hardening mixture, to impart the necessary hardness or temper thereto. 
 
 Quick. — Having a curve of lesser radius relatively to another curve. 
 
 Quick Feed.— See Slow Feed. 
 
 Quick Gear, — When a crane is lifting direct instead of through intenae- 
 
MECHANICAL ENGINEERING. 273 
 
 diate gearing it is said to be in quiolc gearing. A back geared lathe is 
 in quick gear -when the back gear is not in. Speed pulleys are in quick 
 gear when they are driving from the larger to the smaller instead of 
 under reverse conditions. 
 
 Quick Gouge. — A gouge which has the greatest amount of curvature made, 
 though proportionate to the width of the gouge. See Flat Gouge, 
 Middle Flat Gouge. 
 
 Quick Eetum. — (1) The mechanism by which the cutting tool of a machine, 
 or the work which is traversed under the tool is ran at a quicker speed 
 during the non-cutting than during the cutting stroke. Quick return 
 is applied to planing, shaping, and slotting machines, and many others, 
 and is usually effected by trains of gearing, or by link motion, that is a 
 connecting rod sliding in a pivoted link, moving across a revolving disc, 
 or by an arrangement of levers. (2) A lathe in which the slide rest is 
 traversed back with a rack and pinion is said to be provided with quick 
 return. See Quick Traverse. 
 
 Quick Sweep. — ^A sweep whose amount of curvature is great relatively to 
 some other curve or curves with which it is compared. 
 
 Quick Traverse. — The hand traverse given to the slide rest of a laihe by 
 means of a rack and pinion. After the rest has travelled down the bed, 
 through the medium of the leading screw, the clasp nuts are disengaged, 
 and the quick traverse or quick return is put into gear for carrying the 
 saddle back. 
 
 Quiescent Load. — A dead load (q.v.). 
 
 Quill. — The term generally applied to a hoUow shaft or spindle. 
 
 Quintal. — A French measure of weight containing one hundred kilo- 
 grammes (q.v.) or one hundred thousand grammes (q.v.), equivalent to 
 2204621 English pounds, or 1-9684 hundredweights 
 
 E 
 
 Eabbet. — A rebate (q.v.). 
 
 Babble. — A tool used by puddlers for rabbhng (q.v.) the pasty metal. It 
 is a long bar of iron turned up at the end at right angles. 
 
 Babbling. — The working or stirring about of the iron in a puddling fur- 
 nace, removing slag from its surface, and drawing the metal into masses 
 or balls ready for the hammer. 
 
 Bace. — (1) A circular ring upon which travel the rollers supporting a 
 revolving superstructure. The roller race of a revolving crane furnishes 
 an Olustotion. (2) The channel by which water is conducted to a water 
 wheel. 
 
 Baciug. — Engines are said to race when their rates of speed are very 
 unequal, due to variations in the resistance which they have to over- 
 come, or to the absence of governors, or the imsuitability of the gover- 
 nors provided. Racing is a source of danger because of the uncertain 
 strain put thereby upon moving parts. 
 
 Back. — A straight length of toothed gearing, being a successive series of 
 teeth pitched in a straight line instead of around a curve, as in the 
 case of wheels. The teeth of racks are formed on the same principles 
 as those of wheels. The term is often applied to a wheel segment or 
 circular rack. 
 
 Back and Pinion. — An arrangement of gear for converting rotary into 
 
274 DICTIONARY OF TERMS USED IN 
 
 linear and reciprocal motion, -wMcli is largely employed in mectauism, 
 a pinion wteel Tvliose centre is fixed actuating a movable rack (q.v.). 
 
 Back Compass. — A pair of shop qnadi'ant compasses, in wHcli the lower 
 edge of the quadrant is out into minute teeth, forming a circular rack. 
 
 Back Feed. — Peed motion imparted by a rack and pinion. The feed of 
 some drilling machines is thus imparted, and also the longitudinal 
 traverse of self-acting lathes, both screw - cutting and non- screw- 
 cutting. The travelling tables of some frame saws are actuated by 
 rack feeds. 
 
 Backing. — (1) The running of the block carriage of a crane or traveller 
 inwards or outwards to suit the requirements of the work in hand. 
 The racking is performed by suitable gearing, and an endless chain 
 passing over sheave wheels. (2) The running of a shde rest along with 
 the rack and pinion motion. 
 
 Backing Gear. — The gear which actuates the block carriage (q.v.) of a 
 crane (see Racking). The nature of the gear will depend upon the class 
 of crane, and whether hand or steam. 
 
 Back Bail. — A toothed rack laid between the ordinary permanent way 
 rails on the steep gradients in mountainous districts, into which toothed 
 gear in rack rail locomotive engines engages, in order to move upwards 
 by tractive force. 
 
 Bad. — The radius of a circle. 
 
 Badial. — Moving in a right ine and along the shortest distance from 
 centre to circumference. 
 
 Badial Arm. — (1) The movable cantilever which supports the drilling 
 saddle in a radial drilling machine (q.v.). (2) The arm which is centred 
 on and pivots round the end of the leading screw of a screw-cutting 
 lathe, and which carries the train of gearing connecting the screw with 
 the wheel on the mandrel of the headstock. 
 
 Badial Azle. — See Bogie. 
 
 Badial Axle Box. — See Bogie. 
 
 Badial Drilling Machine. — A heavy drilling machine, which is so con- 
 structed that the position of the drill can be accommodated to the work 
 without moving the latter. The whole drilling apparatus — spindle, 
 feed, &o. — is carried on a saddle, which slides on a radial arm hinged 
 to a post, mitre wheels actuating the spindle, and communication 
 being maintained with the spindle in any part of the arm through a 
 telescopic shaft. Kadial drUls are made both attached to a strong 
 base or table and also for fastening to a wall. 
 
 Badial Paddle Wheel. — ^A paddle wheel in which the float boards are 
 fastened directly to the arms by means of hook bolts, their faces 
 radiating from the centre of the wheel. Hence the floats are always 
 vertical, and consequently only develop their greatest power when in 
 their lowest position. They enter and leave the water at an angle with 
 the level of the water, with a consequent waste of energy. AVTieels 
 having feathering floats (q.v.) are not subject to this disadvantage. 
 
 Eadiation. — The emission of heat rays from hot bodies. A body which 
 emits red rays only, is red hot, one which emits rays of all colours is 
 white hot. These radiations are visible, but there are others to which 
 our eyes are not sensitive, and bodies are supposed to give off radiations 
 at all temperatures. 
 
 Badins. — A radius of a circle is the straight line which extends from the 
 centre to the oiroumf erenoe along the shortest possible distance. 
 
 Eadius Finder. — ^A centre square (q.v.). 
 
MECHANICAL ENGINEERING. 275 
 
 Eadius Sod, or Bridle Rod. — (1) A rod in the arrangement Imo-mi as 
 parallel motion (q.v.), which, is fixed on a pivot at one end and jointed 
 to the back link at the other, and which vibrates with the motion of the 
 beam. (2) Sometimes applied to the rod which passes from the die 
 block of a slot link to the slide, or out-ofi valve. 
 
 Bafters. — The diagonal roof ribs which extend from the king post to the 
 tie beam in a roof truss. These are often called priacipals, or priacipal 
 rafters, to distinguish them from conunon rafters (q.v.). 
 
 Eail Bender. — See Rail Straightener. 
 
 Rail Clamp. — See Bail Drill. 
 
 Eail Clips. — Clips of wrought iron attached to the front and back of a 
 balance crane, and used for fixing the crane during the lifting of hea%'y 
 loads. They are made to embrace the railway metals by bolts passing 
 through both halves. Without rail cKps, a crane would be liable to 
 overturn with a full load. 
 
 Eail Drill, or Eail Clamp. — A portable combination tool used for drilling 
 holes in rails without removing them from their places. It consists of 
 a short stout clamp arching over the rail and provided with a set or 
 tightening screw on the one side, placed in opposition to a ratchet 
 drill upon the other. 
 
 Eail Fagot, or Eail Pile. — The fagot or pile from which the blooms for 
 iron rails are rolled. It is composed in different ways, according to the 
 specification, quahty, and price. It is usually about 8J in. wide and 
 9 in. high. The heads, if for a double-headed rail, are formed of 
 slabs of hard hammered iron, and the middle space is filled in with puddle 
 bars, which may be either of the entire width or made to break joint. 
 Steel rails are now made in preference to iron, and these are rolled from 
 a homogeneous ingot. 
 
 Eail Gauge. — An iron bar having a projection or set-ofi near each end at 
 right angles with the bar, the distance of whose outer faces apart is 
 that of the gauge of the rails, which are laid down by direct measure- 
 ment therefrom. 
 
 Eail Guards. — The curved rods or bars which extend from the front of a, 
 locomotive downwards nearly to the rails, to throw ofi! any obstructions 
 from the Hue. 
 
 Rail Ingot. — The ingot from which Bessemer steel rails are rolled, and 
 which takes the place of the rail fagot for iron rails. These ingots are 
 cast in moulds of cast iron , tapered to permit of ready stripping of the 
 mould from the ingot, and are about 11^ in. square. 
 
 Eail Mill. — A mill in which rails are rolled, the rolls being grooved out 
 into the required sections. 
 
 Ran Pile. — See Eail Fagot. 
 
 Rail Punch. — A form of punching-bear, usually worked by hydraulic 
 pressure, used for punching the holes in the webs of rails, to take the 
 fish bolts. 
 
 Rails. — The bars which form thfe tracks for the wheels of rolling stock on 
 tramways and permanent way. They are made in various sections, 
 both single and double headed, and in iron and in Bessemer steel. They 
 rest either directly on the sleepers, or in chairs spiked down to the 
 sleepers. See details under special heads. 
 
 Rail Saw. — A saw used in rail rolling mills for cutting off the crop ends 
 of rails after they leave the rolls. 
 
 Rail Straightener, or Rail Bender. — A powerful screw press used for 
 Btraightening or bending rails and bars. Some of these machines are 
 
276 DICTIONARY OF TERMS USED IN 
 
 worked by a hand lever, or a wheel, actuating the screw, some ty 
 hydraulic pressure. The rail is sustained on two points at some dis- 
 tance apart, and the pressure is applied between these points. See also 
 Squeezing Maohing. 
 
 Hail Teste. — The principal test used for rails is the falling weight test 
 (q.v.), and the usual test is a monkey of a ton weight allowed to fall 
 from a height ranging from 15 to 20 ft. upon a rail resting on sup- 
 ports 3 ft. 6 in. apart. Thus with a double-headed steel rail weigh- 
 ing 70 lbs. to the yard, two blows from a monkey of a ton weight 
 falling from a height of 18 ft. should not produce a deflection greater 
 than 3 in. in amount. Under the dead weight test (q.v.), which 
 is also applied to rails, a dead weight of 28 tons should not pro- 
 duce a deflection of more than \ of an inch on a rail similarly sup- 
 ported. 
 
 Railway Axle. — Axles are made of wrought iron or mild steel. The 
 largest part of the axle is just behind the wheel boss. The diameter is 
 gradually reduced to the centre midway between the wheels, and again 
 at the ioumals, whose lengths are about twice their diameters. The 
 diameter of the journal is usually about 3J in. Sharp comers at the 
 junctions of the shouldered portions are avoided by turning a small 
 radius. 
 
 Hallway Brake, — Brakes are of various kinds — air, friction, steam, &o. — 
 not«d under their proper headings. 
 
 Railway Chair. — See Chair. 
 
 Railway Gauge.— See EaU Gauge. 
 
 Railway Wheel. — Railway wheels have their bodies either of wrought 
 iron or wood. The different parts of a wheel are the boss or the central 
 portion, and the body, intermediate between the boss, and the tire. The 
 boss is usually made of cast iron oast around the free ends of the bent 
 bars which form the arms, or of wrought iron welded and pressed into 
 form. Tires are fastened on with rivets, bolts, or retaining rings. In 
 wooden wheels the body is solid, built up in pieces whose shape is the 
 sector of a circle, the grain running radially, the timber being bonded 
 together with retaining rings (q.v.) and the boss. Wood has the advan- 
 tage of elasticity ; it afl:ords continuous support to the tire, and does 
 not beat the air or raise dust like wheels with spokes. Wheels are 
 attached to their axles without keys, being pulled on with hydrauUo 
 pressure, or by shrinking on. 
 
 Raised Work. — Work which has been hammered into outline. See 
 Raising. 
 
 Raising. — (1) The production of curved outlines in sheet metal by the 
 application of blows from a hanamer. (2) When a tap or die is in bad 
 order, that is, not backed off properly, or not having a keen-cutting 
 front, the screw thread is partly compressed or squeezed out of shape, 
 and is then said to be raised instead of being cut. 
 
 Raising Hammer. — A round-faced hammer used for raising (q.v.) metal 
 work. 
 
 Rake. — (1) A term usually applied to signify the angles of metal turning 
 tools, as side rake, front rake, &c. (2) The amount of forward angle, 
 or pitch of saw teeth. (3) A broad flat expansion turned down at 
 right angles with the end of a long bar, and used for thrusting about 
 the fuel to front or back on a furnace hearth. 
 
 Raking Bar. — A long rod of wrought iron used for raking out the cupola 
 fire after casting. 
 
MECHANICAL MNGINMERING, 277 
 
 Baking Out. — The remoyal of the residuary coke, slag, and metal from 
 the bottom of a cupola furnace after the running down of the charge. 
 This is done after every blowing, and is necessary, otherwise the semi- 
 fused mass would form a hard agglomeration when cold, the forcible 
 removal of which would damage the furnace. 
 
 Bam, — (1) A term sometimes applied to the monkey (q.v.) of a pile driver. 
 (2) The arm of a shaping or slotting machine which can-ies the tool 
 backwards and forwards, is termed a ram. (3) A lydraulio ram 
 (q.v.). (4) The plunger of a hydraulic lift (q.v.). (5) A hydraiiho 
 piston (q.v.). (6) The plunger of a hydraulic press (q.v.). 
 
 Earn Leather. — A cup leather (q.v.). 
 
 Sammer. — A tool used by moulders for the purpose of ramming the sand 
 around patterns. It consists of a head of cast iron attached to a handle 
 of wrought iron, or sometimes of wood. In a hand rammer, or a bench 
 rammer, the working end is made rounding, in the flat rammer it is 
 disc shaped. Frequently the rammer is reversed in use, and the pointed 
 end of the handle employed for ramming the sand into narrow spaces. 
 
 Bamming Blocks. — Reversed moulds (q.v.) used in some kinds of mould- 
 ing work. 
 
 Bamps, or Guide Plates. — (1) Appliances for placing rolling stock upon 
 the rails. They clip the rails, and are provided with flat hehcal exten- 
 sions against which the wagon wheels slide up to the rail. They are 
 made in sets of four, two right and two left. (2) Planks laid on 
 suitable supports and forming an inchned plane, up and down which 
 barrows of material are wheeled are sometimes termed ramps. 
 
 Eamsbottom Ring. — See Spring King. 
 
 Barn's Horn. — A symmetrically shaped double crane hook. Used chiefly 
 for light weights, being inferior in strength to the single hook. 
 
 Eape-seed Oil. — See Seed Oil. 
 
 Bapping. — Rapping is the process of looseniug a pattern in the foundry 
 sand previous to its withdrawal, and is effected by inserting the pointed 
 end of an iron bar in a hole bored in the pattern, or into a rapping 
 plate, and striking it heavUy sideways with a hammer. During the 
 actual process of withdrawal, rappiug mallets (q.v.) are employed. The 
 process of rapping, though necessary, is often damaging to the pattern, 
 and if carelessly performed affects the size of the mould, enlarging it to 
 an extent which is very appreciable in small castings. 
 
 Bapping Bar. — A loosening bar (q.v.). 
 
 Bapping Hole. — A hole made ni a foundry pattern for the insertion of the 
 loosening bar used in rapping. When a single moulding, or when two 
 or three mouldings only from a pattern are required, the rapping hole is 
 usually bored in the wood of the pattern, but when a large number are 
 wanted, rapping plates (q.v.) are used to prevent damage to the pattern. 
 In large patterns several rapping holes are provided. 
 
 Bapping Mallets, or Moulders' Mallets.— Small roimd-faced wooden 
 maUets used for loosening the sand from foundiy patterns during the 
 process of their withdrawal from the moulds. The faces and edges of 
 the patterns are Ughtly tapped with the mallets as the pattern is 
 gradually lifted. They are made of wood, as inflicting less injury to 
 the pattern than iron hammers. 
 Bapping Plates. — Plates of malleable iron let into and screwed on the 
 faces of foundry patterns, and provided with holes for the insertion of 
 the rapping bar. The holes for rapping and lifting are usually inserted 
 in the same plate, and they are then termed rapping and lifting plates. 
 
278 DICTIONARY OF TERMS USED IN 
 
 Easp. — Easps are used by core makers and loam moulders for the purpose 
 of reducing loam, -work to accuracy, in regard to both shape and 
 dimensions. 
 
 Basp Cut. — The abrasive surface formed on a file by the punching up of 
 isolated projections, as distinguished from the ridges formed by the 
 action of chisels. 
 
 Eastrick Boiler.— A vertical cylindrioal boiler of large diameter, and 
 having horizontal tubes. It is an antiquated form. 
 
 Eatchet. — A ratchet wheel (q.v.). 
 
 Eatchet Bar. — A straight bar serrated with teeth like those of a ratchet 
 wheel, to receive the thrust of a paul. "The function of the ratchet bar 
 is to permit of movement in the one direction whUe preventing it in the 
 direction opposite. It is attached to foot or other levers. 
 
 Eatchet Brace. — A tool used hy metal workers for the drilling of holes by 
 hand. It consists essentially of a lever which moves the drfll round 
 and feeds it forward at the same time by means of a ratchet and click 
 actuating a square -threaded feed screw. 
 
 Eatchet Drill. — A drill used in conjunction with a ratchet brace (q.v.). 
 It is furnished with a square tapered shank. 
 
 Eatchet Feed. — A paul feed (q.v.). 
 
 Eatchet Jack. — A screw jack (q.v.) rotated by means of a ratchet and 
 click. 
 
 Eatchet Paul. — A paul or click which engages with the teeth of a ratchet 
 or a spur wheel, as distinguished from the pauls used in the sliding 
 shafts of cranes, and on turntables. See Spring Paul. 
 
 Eatchet Teeth. — The teeth of ratchet wheels are difi:erently formed 
 according to the f auction which they have to fulfil. When the ratchet 
 paul has to woi k in opposite directions at pleasure, as when moving a 
 feed screw to right or left alternately, the teeth are hke those of 
 ordinary spur wheels. But when the motion is always in one direction, 
 as happens in the case of cranes, the teeth slope in the one direction 
 only. Their outline then is roughly, though not quite, that of a right- 
 angled triangle, the base resting on the periphery of the wheel, and 
 the side being nearly, though not quite, radial with the centre, being 
 slightly undercut, and the hypothenuse being the sloping face over 
 which the paul slides. This is not, however, straight, but slightly 
 curved outwards. 
 
 Eatchet Wheel. — A wheel provided with teeth into which a paul (q.v.) 
 fits. The paul either moves and turns the ratchet wheel with an inter- 
 mittent motion which renders it capable of feeding a machine cutter, or 
 the wheel moves, its motion being independent of that of the paul. 
 Owing to the shape of the teeth it turns always freely in the one 
 direction, but when it is attempted to reverse the motion of the wheel 
 the paul prevents it from receding. In the first case the shape of the 
 teeth is usually symmetrical, being common wheel teeth ; in the latter 
 they approximate roughly to that of a right-angled triangle, or to that of 
 saw teeth for ripping. The first form is used in most machine feeds, 
 the second in the hoisting gear of cranes for preventing the load from 
 running down. 
 
 Eate, — See Screw Rate. 
 
 Eatio, or Proportion. — A particular relation subsisting between numbers or 
 quantities, as shown by the division of one by the other. Thus 
 12 : 3 : : 8 : 2 expressing the ratios which exist between those numbers, 
 12 containing 3 four times, and 8 containing 2 four times. In propor- 
 
MECHANICAL ENGINEERING. 279 
 
 tional mrmbers the product of the first and last terms is equal to thai 
 of the second and third terms. Hence the rule to find a fourth pro- 
 portional : multiply the second and third terms together and divide bj 
 the first. 
 
 Eatio of Expansion. — The proportion subsisting between the final and 
 the initial volumes of steam in a cylinder. 
 
 Eat Tail Eile. — ^A file circular in section and tapering or bellied in the 
 direction of its length. 
 
 Battle Barrel. — A rumble (q.v.). 
 
 Battling Box. — A rumble (q.v.). 
 
 Eaw Hide Belting, — Beltiag which has not been subjected to the process 
 of tanning, excepting on tiie surface. 
 
 Eaw Iron. — Iron which has not been refined. See Eefining. 
 
 Eaw Mine. — A term applied to iron stone (q.v.). 
 
 Beaction. — ^When a body is at rest it presses downwards with a definito 
 weight. The support beneath it reacts with a pressure which is equal 
 and opposite. Hence the fundamental law, action and reaction are 
 equal and opposite. 
 
 Beaction Wheel. — An enclosed wheel into which water enters under head 
 or pressure, and escapes from, tangentially, the force being derived 
 from the reaction of the weight thrown off at the periphery. See 
 Turbine. 
 
 Eeamer, Eymer, Bimer, or Ehymer. — ^A fluted tool used for finishing and 
 truing cored or drilled holes. Eeam.er3 are solid when used in a socket 
 or with a wrench, shell or hollow when bored out to fit on a mandrel. 
 See Broach, Fluted Eeamer, Kose Reamer, &o. 
 
 Eebate, or Babbet. — ^A shoulder or recess on the edge of a piece of wood or 
 metal for the reception of the edge of another similar piece. 
 
 Bebate Joint. — A joiat which is made by the overlapping of the edges of 
 material, half the thickness of the material being cut away to a little 
 distance inwards from the matching edges. 
 
 Eebate Plane, — A plane used for the working of rebates. The cutting 
 iron is as wide as the wood stock, and hence planes right up to the 
 edge. Skew-mouth planes have the cutting iron at an angle with the 
 side of the stock, and work sweeter than the square-mouthed ones. 
 Eebating is also performed by machines furnished with revolving 
 cutters, or by a thick circular saw. 
 
 Eebating. — The grooving or shouldering back of timber from the edge to 
 produce a lap joint, 
 
 Eeboring. — When engine cylinders have become grooved and of varying 
 diameters through long use and wear, it is customary to bore them again 
 and insert a larger piston. The process is termed reboring. Small 
 cylinders are removed from their beds or foundations for the purpose, 
 but large cylinders are rebored while in place. 
 
 Eecarburisation, — The adding of a definite amount of carbon to iron 
 which has been first completely deoarburised. Steel of various grades 
 is thus made in the Bessemer converter (q.v.) and in the cementation 
 (q.v.) process. 
 
 Eeceiver, — (1) When large quantities of iron of fifteen or twenty tons 
 weight and upwards have to be poured, exceeding the capacity of the 
 foundry ladles, the metal is allowed to accumulate in a receiver, which is 
 a sheet-iron vessel lined with fire bricks and clay, and from which the 
 iron is conducted into the mould. Such vessels may be fixed or 
 portable, (2) Generally any vessel used for the storage of liquids or 
 
28o DICTIONARY OF TERMS USED IN 
 
 gases, as for instance air in an air compressor. See also Intermediate 
 Receiver. 
 
 Bechuckiug, — In all but the very plainest turned work it is necessary that 
 it should be set a second or a third time in the lathe chuck or chucks, 
 in order to turn some portions which could not be reached by the tool 
 in the first chucking. This is termed rechucMng or second chucking. 
 
 Reciprocal, — One quantity is the reciprocal of another when it is the re- 
 sult of unity divided by the other. Thus 2 and -j ^ '2 and '5 are recipro- 
 cals. Hence the product of a quantity by its reciprocal is always unity 
 as2X •5 = 1-0. 
 
 Beciprocatiug, — Used in opposition to rotary. The vast majority of 
 engiues and pumps are reciprocating, that is the piston and rods move 
 forward and backward alternately in right lines. 
 
 Eeoiprocating Engines. — See Reciprocating. 
 
 Reciprocating Pump. — See Reciprocating. 
 
 Reciprocating Weight. — Usually understood to signify the moving 
 weights of an engine piston, piston rod, and half that of the connect- 
 ing rod. The power which they absorb is equal to their weight multi- 
 plied by the height from which the weight must have fallen to pro- 
 duce their velocity. 
 
 Rectangle. — A parallelogram (q.v.) whose sides are at right angles to one 
 another. 
 
 Red Brass. — An alloy variously composed, as : Copper, 24 lbs. ; zinc, 
 5 lbs. ; bismuth, 1 oz. Copper, 24 lbs. ; zinc, 5 lbs. ; lead, 8 oz . 
 Copper, 32 lbs. ; zinc, lOlbs. ; lead, lib. Copper, 160 lbs. ; zinc, 
 60 lbs. ; lead, 10 lbs; antimony, 44 oz. 
 
 Red Brick Dust. — Used for parting sand (q.v.). 
 
 Red Copper Ore. — ^A very pure oxide of copper found in Cornwall, Cuba, 
 and other parts. 
 
 Red Deal, or Red Pine. [Finus st/lvesiris.) — The produce of the Scottish 
 fir, grown in Norway and Sweden and Russia. The deals take their 
 names from the ports whence they are shipped, as Riga, Memel, 
 Dantzic. Riga deals are superior to the last-named. 
 
 Reddle. — A shop term for red lead, mixed with oil and used when filing 
 and scraping surfaces to fit. 
 
 Red Haematite. — An ore of Iron quarried largely in Cumberland, 
 Glamorganshire, and Ireland. It is a non-hydrated peroxide of a red 
 colour, hence its name, and furnishes excellent quality of iron. 
 
 Red Heat. — There are several grades of red heat, distinguished by the 
 prefixes, black, bright, or low red, noticed under their headings ; 
 the distinguishing of these shades of colour being of importance in the 
 hardening, tempering, and welding of iron. 
 
 Red Lead, or Minium. — Symbol 2Pb O -j- Pb O2. The red oxide of 
 lead. It is used when mixed with boiled oil only, or with boiled oil 
 and with white lead, in making steam joints. Also mixed in a thin 
 semi-fluid paste, for checking the accuracy of contact of surfaces which 
 are being fitted the one to the other, the colour being tran.sferred from 
 the surface which is finished to the highest portions of the surface 
 which is undergoing the process of fitting. 
 
 Red Shortness, or Hot Shortness. — That condition of wrought iron or 
 steel in which they are incapable of being roUed or worked at a red 
 heat. The presence of sulphur produces red shortness. 
 
 Reducing Agent. — The agent through whose influence a chemical com- 
 pound is resolved into its simple elements. The reduction of metals 
 
MSCHAmcAL BnaiNnEkltfG. 28 r 
 
 from tteir ores is due to the agency of heat acting in combination with 
 some solid substance or substances. Thus carbon, or more properly 
 carbonic oxide, CO, is the reducing agent in the smelting of iron ores. 
 
 Beducing Furnace. — Any furnace in -which metals are separated from 
 their ores and reduced to the metallic state. Hence blast, and some 
 reverberatory furnaces are reducing furnaces. 
 
 Seducing Pipe. — A pipe having different dimensions, or sometimes also 
 different shapes at its opposite ends. It is used to connect pipes of un- 
 equal sizes or of different shapes together. 
 
 Seducing Valve. — A valve constructed for the regulation of steam 
 pressure between a boiler and its connections. A weighted lever 
 regulates the opening of the valve. 
 
 Seduction, — The extraction of metals from their ores by depriving them 
 of their oxygen in a reducing furnace (q.v.). 
 
 Seduction of Area. — Malleable iron and steel, when subjected to tensile 
 stress, elongates up to the breaking strain, with a consequent reduction 
 of area. The amount of elongation and reduction of area which it 
 undergoes is a recognised test of its quality. The amount of reduction 
 of area should not be less than 25 per cent, in a good specimen, and 
 the amount of elongation 15 per cent. 
 
 Seduplication, — Reduplication refers to the gain in power obtained by 
 the combination of pulleys in pulley blocks (q.v.). In a system of 
 pulleys a force equal to the pull of the string comes into play at every 
 departure of the string from a pulley. 
 
 Bed Zinc Ore. — ^An ore of zinc of small commercial value. It occurs as 
 an oxide, the red colour being due to contamination with the oxides of 
 iron and manganese. It is found in New Jersey and the United States. 
 
 Seeking. — The coating over of the faces of ingot moulds for the casting 
 of crucible steel, vrith a layer of carbon, to prevent the adhesion of the 
 ingot to the mould. 
 
 Seel Hose. — See Hose Keel. 
 
 Ee-evaporation. — Re-evaporation is a term used to express the influence 
 of an unjacketed engine cylinder of long stroke, and worked to a high 
 grade of expansion, upon the steam. The cylinder being subject to 
 the extremes of temperature of the entering and exhausting steam, 
 the latter is subject to initial condensation (q.v.) on its first entrance. 
 The heat thus lost is however reimparted to it as it acquires by expan- 
 sion a temperature below that of the cylinder, while towards the end of 
 its work it acquires from the cylinder, hotter than itself, a vaporous 
 condition, or is re-evaporated. By the use of the steam jacket these 
 variations are prevented or minimised. 
 
 Befined Iron. — Fine metal or plate metal. It is white iron, which has 
 passed through the refinery and been deprived of much of its carbon and 
 siHeon preparatory to dry puddling. It is rendered brittle by quick 
 cooling with water, and is broken up into small fragments before being 
 passed to the puddling furnace. 
 
 Sefined Tin. — See Boiling. 
 
 Eeflnery. — The structure in which the process of refining is effected. It 
 consists of an outer vertical framework surmounted by a low stack, and 
 containing hearth, twyers, dam plate, tap hole, and casting pit. The 
 hearth is about 4 ft. square by 15 to 18 in. in depth, bounded at back 
 and sides by cast-iron water blocks. The twyers are inclined down 
 towards the hearth at an angle of from 30° to 35°, and are five or six in 
 number, to distribute the oxidising influence of the air equably over 
 
2P2 DICTIONARY OF TERMS USED IN 
 
 the area. The hearth is lined with sandstone, and coke is the fuel 
 used, laid in alternate layers with the pig and scrap, which may amount 
 to two tons per charge iu the larger refineries, and the time of its puri- 
 fication three or four hours. The molten metal and slag are then 
 tipped out into the casting pit, or pig mould (q-v.), and broken up when 
 cooled. It is then ready for puddling. Refining is also carried on to a 
 limited extent in the manufacture of coke and oharooal plates for tinned 
 goods, but its commercial importance is being dmunished by the sub- 
 stitution of steel sheets in their place. 
 
 Eeflning. — The process of partial decarburisation and purification of grey 
 pig iron from silica, with its accompanying conversion into white 
 iron. The refining process is adopted as a preliminary to dry puddling, 
 the reason for its adoption being that white iron, when passing from 
 the solid to the molten state, passes through a pasty condition which is 
 favourable to its oxidation in the puddling furnace, a condition which 
 is not the case with the grey iron, which becomes liquid without under- 
 going any transitional state. Refining is not practised in the open 
 hearth or wet puddling processes. About twenty-four hxmdredweights 
 of grey iron are required to produce a ton of refined iron. 
 
 Eeflux Valve, or Check Valve. — A flap valve used for the purpose of 
 taking off the pressure of a head of water acting in a backward direc- 
 tion against a set of pumps. 
 
 Eefractory. — A substance is said to be refractory in the degree in which 
 it is able to resist the action of heat. Lime, eilioa, clay are refractory 
 substances, and hence are used in various combinations with other sub- 
 stances for linings of furnaces, crucibles, &o. Substances refractory in 
 themselves cease to be so when combined in certain proportions with 
 bases, and due regard must also be had to the nature of the metal 
 or alloy which is to be brought into contact with the lining or crucible. 
 
 Refrigerating Fluids. — See Hardening Mixtures. 
 
 Eefrigerator. — (1) A cyhndrical vessel containing a number of copper tubes 
 and used for heating the feed water for a marine boiler above the tem- 
 perature which it derives from the hot well. The waste brine from 
 the boiler is employed to heat the feed water. (2) A machine for lower- 
 ing the temperature of air for cooling purposes, the air being made to 
 expand. 
 
 Eegenerative Furnace.— A furnace in which waste gases, gaseous fuel, 
 and products of combustion are utilised by being taken through layers 
 of brickwork or other regenerators, there rendering up their heat, 
 which heat is taken up again by a similar current mingled with air 
 turned at a certain interval in the reverse direction, which taking up 
 the heat in the regenerators passes into the combustion chamber of the 
 furnace. See also Gras Producer, Pipe Stoves. 
 
 Eegenerative Stoves. — See Pipe Stoves. 
 
 Eegenerator. — The chequer work of a regenerative furnace. It is of 
 glazed firebrick. See App. 
 
 Eegulator. — Any contrivance by which motion is equalised. Hence 
 governors, ily wheels, throttle valves, are regulators. More particularly 
 the term is understood of the regulator valve (q.v.) of a locomotive, and 
 the damper of a steam boiler. 
 
 Eegulator Valve. — The valve which regulates the admission of steam to 
 the cylinders of a locomotive. It is either of the double beat, or 
 conical, or sHding types. 
 
 Begulus, or Matt, — Refers to different stages in the reduction and 
 
MECHANICAL ENGINEERING. 283 
 
 purification of certain metals ; tut in a general sense signifies a metal 
 whicli is yet in an impure condition, that is one which has not reached 
 the final stage of its reduction. The term is applied to a limited 
 number only, as copper, antimony. 
 
 Eegulns of Copper See Matt. 
 
 Eeheating. — The heating a second time of puddled bar for the making of 
 fagoted iron. It is performed in a reverberatory furnace. 
 
 Reheating Furnace. — The reverberatory furnace used for heating the 
 fagots or piles of puddled bar preparatory to passing them under the 
 finishing roUs. 
 
 Eeins. — The handles of smiths' tongs. 
 
 Belative Strength. — It is convenient to know not only the absolute 
 strengths of the materials of construction, but also their relative 
 strengths Tvhen subject to uniform conditions of strain and stress. 
 
 Eelative Volume. — Specific volume (q.v.). 
 
 Eelease. — Release signifies the opening of the steam port of an engine to 
 allow of the escape of 'the exhaust steam from the cylinder. 
 
 Belief Valve. — See Cylinder Escape Valve. 
 
 Eelieving. — Backing ofE (q. v.) . 
 
 Eelighting. — The ignition of the inner lighting tap of a gas engine by 
 means of the outer or master jet (q.v.). 
 
 Eemelting. — The tensile stiength of cast iron is supposed to be increased 
 by repeated remelting. This is not borne out in foundry practice. 
 Repeated remelting tends to make the iron whiter, with a corresponding 
 loss of tensile strength. Iron when remelted takes up impurities from 
 the fuel. Eemelting is only useful when suitable brands of pig are 
 mixed with selected scrap, but the improved quality is not due to the 
 remelting but to judicious mixing. 
 
 Eepairs. — The proper execution of repairs to broken-down or otherwise 
 damaged motors or machines calls for the highest skill of the working 
 engineer. More particularly is this the case at sea, and in large fac- 
 tories where a temporary stoppage only, means an enormous loss in the 
 aggregate. The best workmen are or should be entrusted with the 
 execution of repairs. See also Auxiliary, Break Down. 
 
 Berailing, — Placing rolling stock upon the rails. This is done with screw 
 jacks and timber blocking, or with ramps (q.v.). 
 
 Eesidual Gases. — ^Applied to the products of combustion left in the 
 cyhnder of a gas engine after the explosion of the charge. Carbonic 
 acid is the principal residue. 
 
 Eesilience. — The amount of work involved in the resistance of a body to 
 an impulsive load (q.v.). The total resilience of any material is the 
 amount of work done in breaking it, and is equal to the product of its 
 resistance into the distance through which the resistance acts. The 
 elastic resilience of any material is the work done in straining it up to 
 its elastic limit, and is equal to the product of the deformation by the 
 mean load producing it. 
 
 Bcsin, or Eosin. — Common resin is the product of several species of pine, 
 from which it exudes in a semi-fluid state, and is collected in vessels. 
 It is used as a flux for soldering tinned work, and mixed with tallow 
 and other ingredients as a dressing for belts. See Belt Dressing. 
 
 Besistance. — Eesistauceis the result of friction, and is a state or condition 
 of things tending to arrest and destroy the state of motion. The study 
 of the laws which govern the resistance of bodies under different condi- 
 tions is based on direct experiments, from which coefficients of friction 
 
284 DICTIONARY OP THRMS USED IN 
 
 are deduced. A certiin amount of work is necessarily absorbed in 
 overcoming resistance, and this amount has to be estimated and pro- 
 vided for in calculations relating to all machines and motors. What- 
 ever diminishes resistance becomes a clear mechanical gain. Hence the 
 importance of giving to bearings their proper proportions of surface 
 area, of suitable lubrication of bearing parts, the proper grinding of the 
 edges of cutting tools, &c. 
 
 Resolution of Forces. — The process of substituting or discovering the 
 components (q.v.) of a force from a knowledge of its resultant (q.v.). 
 This is done either by calculations or by a graphic delineation. 
 
 Eest. — The support which takes the re.sistanee of the tool in turning ope- 
 rations in the lathe. There are many Idnds of rests, from the simple 
 rests for hand-turning to the various slide rests. See Floor Eest, Hand 
 Eest, Slide Rest, Tee Eest. 
 
 Besnltant. — The sum of two or more separate forces which act upon a 
 body in difEerent directions (not equal and opposite) , causing it to move, 
 or producing a tendency to move in a definite direction. In other words, 
 it may be defined as a single force which replaces two or more other 
 forces, and which is equal to their sum. 
 
 Betaining Kings. — Eings of wrought iron employed for uniting the tyres 
 to those railway wheels which have wooden bodies, They are annular 
 rings, each having an internal flange on its periphery, which fits 
 into corresponding grooves, one on each side of the ring. The rings 
 being bolted together through the wooden body, clasp the tyres securely 
 in the grooves. 
 
 Betaining Valve. — In pumps where the water has to be lifted from a great 
 depth it is customary to insert in addition to the ordinary valves an 
 additional one in the series of pipes in order to prevent much of the 
 water from running back between the strokes. Hence the name retain- 
 ing valve applied to it. 
 
 Beturn Block. — A snatch block (q.v.). 
 
 Beturn Flues. — The flues of Comish, Lancashire, and "Wagon boilers, 
 being brought from the back of the furnace to the front, thence being 
 carried back again to the chimney, are so termed. 
 
 Beturn Tubular Boiler. — A boiler of marine type in which the smoke 
 tubes pass from the back of the boiler forwards to the smoke box or 
 uptake. The products of combustion travel therefore first to the back 
 through the fire box and then to the front through the tubes. 
 
 Beturn Valve. —A valve which allows of the return of fluid. An over- 
 flow valve. 
 
 Beverberatory Arch. — The arched roof of a reverberatory furnace. 
 
 Eeverberatory Furnace. — A furnace employed in various metallurgical 
 operations, in which the ore or metal is exposed to the action of flame, 
 but is not in contact with the fuel. The fuel is burnt in a separate 
 chamber, divided from the hearth by a bridge, over which the flame 
 passes. The principle of the furnace is the deflection or concentration 
 of the heated gases down on the metal. Eeverberatory furnaces are 
 used for puddhng, and for heating iron plates, angle irons, joists, 
 preparatory to bending; for melting iron, and for melting brass in 
 quantity for special purposes when great purity is essential. The 
 reverberatory furnace is an air furnace, no artificial blast being 
 employed. 
 
 Beverse Cones.. — Cones whose bases are turned away from each other. 
 Applied to the coned bearings of lathe headstocks. See Cone Bearing. 
 
MECHANICAL ENGINEERING. 285 
 
 Eeversed Moulds, or Ramnung Slocks, — Plaster or metal moulds used 
 ia some classes of repetitiou moulding -work. The actual casting moulds 
 are made from these blocks direct, instead of from a pattern, and the 
 advantage of their employment is that a very large number of moulds 
 can be made precisely alike without the labour of forming the parting 
 surfaces and runners and risers at every moulding. 
 
 Eeverse Jaw Chuck. — A dog chuck -whose jaws can be readily reversed, 
 end for end, for convenience of clamping work on the exterior or 
 interior diameters. It is usually effected by running the jaw right off 
 the screw and turning it round. 
 
 Eeverse Jaws. — The jaws of a lathe chuck which are placed within the 
 work which they clamp, for turning exterior surfaces. 
 
 Eeverse Keys. — Keys (q.v.) made and used not with the object of holding 
 machine parts together, but for the purpose of driving them asunder. 
 They are employed in preference to the hammer, to avoid the possibility 
 of bruising the work. They consist of two steel plates, one having a 
 projecting slip on one edge, the other a recess of the same length. 
 Inserted through a cottar way with the projection facing towards the 
 larger or outer end of the strap piece, and a wedge being driven 
 between, the projection thrusts the butt piece of the strap end outwards. 
 They are useful with tapered piston rod ends. 
 
 Reversible Jaws. — The jaws of a reverse jaw chuck (q.v.). 
 
 Reversing. — (l) The making of a founder's mould from a clay or plaster or 
 other model, for which the face alone is available. See Reversed 
 Moulds. (2) The changing of the motion of an engine or machine, or 
 machine part, into a direction directly opposite. 
 
 Eeversing Countershaft. — A countershaft (q.v.) whose direction of rotation 
 can be reversed for the purpose of driving its machine in either direc- 
 tion. A fast pulley, keyed on the shaft, is flanked by two loose pulleys, 
 one carrying an open and the other a crossed belt. By shifting one or 
 the other of the belts to the fast pulley the direction of its motion, 
 together vrith that of the shaft, is immediately reversed. 
 
 Eeversing Cylinder. — See Steam Eeversing Cylinder. 
 
 Reversing Engine. — An engine whose motion can be changed into 
 opposite directions. The reversal is usually effected by means of slot 
 links, lifting links, weigh shaft, and suitable levers, actuating an 
 eccentric, having double sheaves for forward and backward gear, from 
 whence either port is opened to steam. A single eccentric is sometimes 
 used instead, and reversed. See also Eeversing Boiling Mill 
 Engine. 
 
 Eeversing Gear. — The gear which accomplishes the reversal of an engine 
 or other motor, or machine. In an engine it includes the links, weigh 
 shaft, levers. In belting, the forks, cords, levers, as the case may be. In 
 mechanism generally, levers, pulleys, and rods of various kinds. 
 
 Eeversing Handle. — The handle of a reversing lever (q.v.). 
 
 Eeversing Lever. — The lever by which the reversing gear of an engine, 
 or other motor or machine is actuated. 
 
 Eeversing Link. — The slot link (q.v.) of an engine, which, through the 
 medium of the eccentrics, alters the valve for forward or backward 
 motion. 
 
 Eeversing Mill. — A rolling Tnill in which the rolls are reversed after 
 each pass of the rail, bar, or plate. Reversing mills are those with 
 two high roUs (q.v.), and where no provision is made for reversal the 
 bars or rails have to be brought back over the top of the rolls and a pass 
 
286 DICTIONARY OF TERMS USED IN 
 
 is thereby lost. Three high rolls (q.T.) ohTiate the necessity of reversal 
 ■without the loss of a pass. 
 
 Reversing Motion. — Reversing motions are of various lands. The re- 
 versing motion of a lathe is designed to enable the slide rest to traverse 
 either up or down the bed. It is effected in back-geared self-acting 
 lathes by an idle wheel being made to engage in turn with wheels 
 which drive the back shaft in different directions, carrying the saddle 
 up or down accordingly ; in screw-cutting lathes, by introducing an 
 extra wheel into the sorew-ontting train by which, tiie motion being 
 reversed, left-handed screws can be cut. A reversing motion which is 
 employed with bevel gearing is effected through the medium either of 
 a friction or of a claw clutch. The clutch slides upon a feather simk 
 into a shaft upon which two bevel wheels turn freely and gear into a 
 crown wheel common to them both. The clutch can be slid in either 
 direction to engage with either bevel wheel, when clutch and wheel are 
 practically fast on the shaft and revolve with it. It is easy to see that 
 the changing of the clutch from one bevel wheel to the other effects a 
 reversal in the direction of rotation of the crown wheel. See also 
 Reversing Engine, Keversing Mill, &c. 
 
 Reversing Plate. — ^A plate or disc of metal employed for reversing the 
 direction of travel of a single-cylinder engine, in the absence of a slot 
 link (q.v.). It is essentially a plate keyed upon the crank shaft, and 
 furnished either with a slot or with holes by which the eccentric proper 
 is moved up or down for forward or backward motion as required, or 
 for greater or less expansive working of the valve. 
 
 Keversing Boiling Mill Engine. — A type of engine specially constructed 
 for the reversal of the rolls of rolling mills. It may be either simple 
 or compound. It is a geared engine, the engine running faster than the 
 rolls in the proportion of about three to one, according to circumstances. 
 These engines are commonly in pairs connected with cranks at right 
 angles, and the reversal is effected through the medium of a slot link, 
 lifted or depressed for forward or backward gear by means of a small 
 steam cylinder, or by hand only. These engines are made massive, are 
 well fitted, and notwithstanding the rapidity of reversal, run quietly. , 
 
 Keversing Rolls. — The rolls of a rolling mill whose motion is reversible to 
 allow of passes (q.v.) both forward and backward. 
 
 Reversing Shaft. — A weigh shaft (q.v.). 
 
 Reversing Stud. — The stud or spindle which carries the idle wheel for 
 reversing the motion of back-geared self-acting lathes. See Reversing 
 Motion. 
 
 Reversing Valve. — The valve which directs the air and gas into one or 
 the other of the regenerative chambers of a furnace, as they become 
 alternately cooled and heated. 
 
 Revolution. — It is usual to give the speeds of engines, pumps, and other 
 motors and machines, in the number of revolutions they make per 
 minute. This is alternative with piston speed, or stroke, since one is 
 readily calculable from the other. 
 
 Revolvers. — Rotary pistons (q.v.). 
 
 Revolving Furnace, or Rotary Furnace. — A type of furnace designed to 
 effect tie conversion of cast into malleable iron by a process of mecha- 
 nical puddling, in which the furnace rotates, bringing all portions of 
 the molten iron successively into contact with the fettling. The prin- 
 cipal furnaces are the Danks, Spencer, Siemens, Crampton, and Pemot. 
 They have but a limited use in England. In the first-named the 
 
MECHANICAL ENGINEERING. 287 
 
 heartlt, or actual furnace, revolves in a vertical plane ; in the Pemot, 
 and some others, the plane is either horizontal or slightly inclined to 
 the horizontal. The interior is lined with fettling, 'which is kept in 
 place with ribs running longitudinally through the hearth. Rotary 
 furnaces are used for the production of maUeahle iron direct irom the 
 ore, as well as from the pig. The Siemens rotary furnace is of this 
 character. It is formed of a casing of wrought-iron plates riveted to- 
 gether, lined with fire brick and bauxite, or magnesite bricks, and a 
 fettling compound of hammer scale and iron ores melted together. 
 This furnace is about 10 ft. 6 in. long by 10 ft. 6 in. diameter, having its 
 axis horizontal. The body of the rotator revolves on friction wheels, a 
 water jacket keeps the neck cool, the heat is supplied by gas producers 
 and air regenerators. Bends or knees attached to the water pipes 
 project into the body of the rotator and keep the charge continually 
 turning over, and break it up into five or six small homogeneous balls 
 instead of allowing it to agglomerate into one mass. 
 
 Revolving Tool Box. — A tool box employed in some planing machines 
 for metal, which is made to turn through an angle of 180° for the pur- 
 pose of cutting in both directions. It is revolved by cords moved 
 automatically. Termed a Jim Crow box, or a Jack-in-the-box. 
 
 Ehomboid. — A parallelogram whose sides are unequal, and whose angles 
 are not right angles. 
 
 Ehombus. — A paraUelogram (q.v.) whose sides are equal in length, but 
 whose angles are not right angles. 
 
 Rhymer. — A reamer (q.v.). 
 
 Eib. — ^A flange or fillet carried around the edges of or across a casting 
 or piece of plated work, in order to strengthen and support an other- 
 wise weak web. 
 
 Ribbon Brake. — ^A strap brake (q.v.). 
 
 Ribbon Saw. — A band saw (q.v.). 
 
 Riddle. — A coarse foundry sieve about half an inch in the mesh, used for 
 sifting the coarse and old sand of the foundry floor. 
 
 Riddlings. — The residual lumpy material left in the riddle after the rid- 
 dling or sifting of foundry sand. The smaller the proportion of riddlings 
 the better the quality of sand. 
 
 Ridge. — A central horizontal foundry runner, lying longitudinally in 
 relation to the casting or castings, and from which a number of 
 offshoots or sprays (q.v.) proceed to convey the metal each to its 
 own section of the mould, or to its separate casting, as the case 
 may be. 
 
 Ridge Capping. — The covering which runs along the ridge of a roof. 
 
 Ridge Roof. — A roof whose rafters meet in an apex. Its end view is 
 therefore that of a gable. 
 
 Riding. — When, owing to loose fitting shafts, or to bad centring of cog 
 wheels, they slip out of gear and the points of the teeth of one come 
 into contact witii the teeth points of its fellow, they are said to ride or 
 override. 
 
 Riffler, or Bow File. — A file curved in the longitudinal direction. Used 
 chiefly for some kinds of brass work. 
 
 Rigger. — A pulley used for the pui'pose of transmitting motion through 
 the medium of a belt or cord. 
 
 Right Angle. — ^When a straight line standing on another straight line 
 makes equal angles on each side of it, those angles are right angles ; a 
 right angle is therefore 90°. 
 
288 DICTIONARY OF TERMS USED IN 
 
 Eight-hand Engine. — A horizontal engine wMoh stands to the right of its 
 fly wheel when viewed from the back end of the cylinder. 
 
 Eight-hand Tools. — Side tools ground to an angle on the left-hand side, 
 and which therefore cut from right to left. 
 
 Eight-hand Screw. — A screw which turns from left to right. A common 
 wood screw is right-handed. 
 
 Eight Iiine. — A straight line, that is, one which occupies the shortest 
 possible length in passing from one point to another, which is not the 
 case with a curved line. 
 
 Eigid. — Strictly speaking, there are no rigid bodies existent, since absolute 
 rigidity implies that such a body exposed to strain would suffer no 
 stress. But conventionally speaking, the rigid bodies are the metals 
 and harder materials. 
 
 Eigid Metals. — Metals which resist the force of impact, or of tension, or 
 compression,, with the least change of form. Cast iron and steel are the 
 purely rigid metals from an engineer's point of view. 
 
 Eigid Wheel Base. — See Wheel Base. 
 
 Eim. — The outer portion of a circular object, as a wheel, a sheave, or a 
 pulley. 
 
 Eimer. — See Reamer. 
 
 Einging Engine. — A form of pile-driver worked by the combined labour 
 of several men. The monkey slides in timber guides, and is attached 
 to a rope passing over a pulley at the top. The rope to which the 
 monkey is attached divides into several smaller ropes, each of which is 
 held by one man, who lifts and lets go at a given signal. Each indi- 
 vidual hauls about 40 lbs. of the weight of the monkey, which is lifted 
 about three or four feet. 
 
 Eings. — Are used for many purposes, as for pistons and piston packings, 
 the means of union between the shells and fire boxes of boilers, the 
 jointing of boiler seams, caulking rings, retaining rings, rings of angle 
 iron used in built-up structures, &c. Kings are cast or welded, seldom 
 riveted. 
 
 Eing Seams. — The circumferential seams or joints of a boiler. 
 
 Eing Valve. — A lift valve (q.v.) ia which the usual solid disc is replaced 
 by a ring, in order to allow of the escape of fluid on both the outer and 
 inner edges, and which therefore diminishes by one-half the amount of 
 lift necessary. The valve is guided by a central block fitting within 
 the ring. Valves having two rings are also in use, by which the 
 amount of lift is stiU further lessened. 
 
 Eipping The sawing of timber longitudinally or with the grain, as dis- 
 tinguished from cross cutting (q.v.). 
 
 Eip Saw.— A hand saw from 28 in. to 30 in. long, and containing three 
 
 to three and a half teeth per inch. It is used for cutting or ripping 
 
 down with the grain only. It would not be called a hand saw (<l.v.), 
 
 but a rip saw only. 
 
 Else. — The rise of an arch is the vertical distance between the springings 
 
 (q.v.) and the centre or highest point of the intrados (q.v.). 
 Eiser, or Air Gate, or Eising Gate. — A vertical opening through which 
 the upper portion of a foundry mould communicates with the outer air. 
 When the metal rises into it the founder knows the mould is full, dirt 
 and scoriae are carried up into it, and the first outrush of air is allowed 
 to escape freely therefrom. 
 Eising and Tailing Spindle. — The spindle of a circular saw, which is 
 made to rise and fall relatively to the table, in order to cut grooves of 
 
MECHANICAL ENGINEERING. agq 
 
 different depths ia the edges of boards. A -wonn and wheel are the 
 means used to operate the saw spindle. 
 
 Eising and Falling Table.— A machiae table used with drUling, panel- 
 thicknessing, ani other machines, which is made to rise and fall to suit 
 the requirements of different Mnds of work. 
 
 Eising Gate. — The riser (q.v.) of a mould as distinguished from the run- 
 ning gate. 
 
 Eising Main. — The &st portion of a series of pipes for the deliyery of 
 water supply, that is, next the pump or pumps. 
 
 Eising Eod. — ^A rod which actuates, through the medium of catches, sec- 
 tors, and weights, the steam and exhaust valves in a Cornish engine. 
 
 Eising Spindle Saw. — See Eising and Tailing Spindle. 
 
 Eivet. — A double-headed bolt-like but solid fastening, employed for 
 securing plates together in a permanent manner, the tail of the rivet 
 being hammered over in place. Rivets are chiefly employed in cases 
 where they will be subject to shearing, and not to tensile strains. They 
 are of soft iron of superior quality to that used for plates, and are made 
 by pressing into dies while red hot. Rivets hold partly by the contrac- 
 tion of the metal in cooling, nipping the plates, but also by the frictional 
 resistance of the plates to slipping. Rivets are usually closed up while 
 red hot, but if the length between the heads is more than four inches 
 the head is apt to become broken off by the contraction. Over six 
 inches rivets are seldom used, or if used are riveted up cold. 
 
 Eivet Boy. — A lad whose duty is to make rivets red hot in a furnace or on 
 a forge, and hand them to the workmen with tongs. 
 
 Eiveted Plates. — No definite rules can be laid down for the strength of 
 riveted plates, since each example must be tested on its own merits — 
 the mode of pxmching or drilling, the fairness or otherwise of the holes, 
 the quality of the material, both in the plate and the rivet, the nature 
 of the strains to which the plates are subject, and the forms of joints, 
 whether lap, or butt, single or double stripped. 
 
 Eiveted Stays. — Boiler stays are mostly riveted over at their ends, being 
 first screwed into the plates, and suflicient length being left for 
 riveting over. Sometimes a rivet is passed through a pipe or distance 
 piece of wrought iron whose length is equal to the distance between 
 plates. 
 
 Eivet Forge. — ^A portable forge (q.v.) used by boiler-makers and platers 
 for heating their rivets alongside of the work for which they are 
 required. 
 
 Eivet Head. — The head of a rivet is the portion which is first formed, not 
 that which is turned over by the act of riveting, or the tail. Rivet 
 heads are segmental, ellipsoidal, pan, snap, or countersunk, noted 
 under their several headings. 
 
 Eivet Holes. — The holes pierced in metal plates to receive the rivets (q.v.). 
 They are either punched, or drilled, or punched and rymered out. 
 Punching weakens a rigid plate ; rymering relieves the punched holes 
 of some of the local tension set up therein, and leaves the plate un- 
 injured. 
 Eiveting. — ^The turning over or clenching of the heads of rivets. Large 
 rivets are treated while red hot, small ones when cold. Two men 
 and a boy are required for hand riveting, one to hold up, the othei 
 (often two) to hammer over the head, and, the boy to fetch the rivets 
 from the fire. The rivets are hammered sharply while red hot, the 
 hammer beating over the tail on all sides in succession. The finish 
 
 W 
 
--go DICTIONARY OF TERMS USED IN 
 
 is imparted to tlie head by the snap, whose shape is an exact revei'so of 
 that of the rivet. See Machine Riveting. 
 
 Riveting Hammers. — Hammers of various kinds employed in ri^'eting.. 
 They are mostly narrower than ordinary engineers' hammers and 
 the panes are never broad. 
 
 Riveting Machine. — A machine used for closing up or forming the tails 
 of rivets by pressure only. The essential mechanism consists of a die 
 fixed near the end of a, stout cast-iron pillar, and which receives the 
 thrust of a movable cup or snap-head die, actuated by mechanism 
 similar to that of a punching maohiae, the rivet, of course, intervening. 
 Hydiauhc riveters are actuated by the pressure of water, and have come 
 into extensive use of late years. 
 
 Eiveting Set. — A steel punch hollowed upon its face either to a cup or 
 snap-head shape, and used for closing up and forming the tails of 
 rivets. In hand work they are used toE oUow after the hammer and 
 impart a finish ; in machine rivetiug they close at one operation. 
 
 Eivet Joint, — Riveted joints have the advantages of being quickly and 
 readily made, and of being very reliable if properly proportioned, and 
 hence are applied to a vast number of structures — boUera, girders, 
 bridge work, tanks, &c. The forms of rivet joints are single and double 
 lap, and butt, described under their headings. 
 
 Bivet Steel. — MUd steel is now used largely for the rivets of boilers. 
 Good rivet steel should stand bending cold to a curve whose inner 
 diameter is equal to that of the rivet. The heads of steel rivets should, 
 be hammered down quickly. Overheating of these is more injurious' 
 than in the case of iron. 
 
 Kivet Tongs. — Tongs with long narrow jaws used for grasping red-hot 
 rivets and slipping them into their holes. 
 
 Roach Belly. — See Chambered Core. 
 
 Soad Locomotive. — See Traction Engine. 
 
 Eoad Pen. — See Drawing Pen. 
 
 Bead Sand. — The scrapings of roads in flinty districts, which, being of a 
 sOicious and refractory character, is used for mixing with sands of a 
 more close nature, for foundry use. 
 
 Boasting. —The preparatory treatment of ores of metals, consisting in the 
 heating them at a moderately high temperature in order to volatihse and 
 drive off the deleterious gases, carbonic acid, sulphur dioxide, &o. 
 
 Booking Disc. — See Wrist Plate. 
 
 Booking Frame. — The frame which carries the gear wheels at the end of 
 a self-acting lathe, for reversing the direction of the back shaft. 
 
 Booking Grate Bars. — Fire bars (q.v.) to which a rocking motion is im- 
 parted in order to prevent choking of the interspaces. 
 
 Booking Handle, or Booking lever. — The double-ended handle for the 
 application of manual power to the working of double-barrelled pumps. 
 One piston is thus at the lowest part of its stroke while the other is at 
 its highest. Called also bob lever. 
 
 Booking Lever. — The lever which drives the air and the circulating 
 pumps in marine engines. 
 
 Booking Shaft, or Bock Shaft. — A shaft which carries the double-ended 
 lever which actuates the slide valve in the indirect acting slide valve 
 (q.v.) type. Also any shaft or spindle which has a to-and-fro motion 
 only, as a weigh shaft (q.v.). 
 
 Book Sand. — The debris of abraded rook, used for foundry cores. See 
 Foundrv Sand. 
 
MECHANICAL ENGINEERING. agi 
 
 Bod. — A tar of iron or other metal. The sections and sizes of rods are 
 variable — flat, round, oval, half-round, &o. — according to the numerous 
 purposes for which they are required. 
 
 Eod Chisel. — The smith's chisel, -svhioh is held by -n-ithy handles, to dis- 
 tinguish it from the anvil cutter (q.v.) . 
 
 Bodding. — When, in the course of moulding a pattern, a mass of sand 
 overhangs a flange space, the sand is supported by bent rods of iron 
 proceediug from a drawback or other plate, and bent over the flange 
 space to form a rigid nucleus for the binding together of the sand. 
 But for this redding, as it is called, the sand would probably be washed 
 down by the rush of metal. 
 
 Eod Gauge. — See Gauge Eod. 
 
 Eolled Bars. — Bars of malleable iron or steel, the shape of whose cross 
 section has been developed by passing through the rolls of rolling mills. 
 AH imaginable sections can be rolled thus, provided that the section 
 la uniform and that all flanged portions stand at right angles with 
 the main axis. 
 
 Eolled Beams. — Joists (q.v.). 
 
 Eolled Iron. — See Rolled Bars. 
 
 Eoller Feed. — In machines for wood working the timber is fed up to the 
 cutters by fluted rollers ; hence the term roller feed . 
 
 Boiler Path. — A smooth surface, plane, circular, or otherwise, upon which 
 smooth rollers, turned or chiUed, travel to carry a superstructure of 
 some kind. Rotating furnaces, revolving cranes, &c., run on roller 
 paths. 
 
 Boiling. — The straightening, or the bending of plates of sheet or bar 
 metal, performed between the rolls of rolling mills. 
 
 Boiling Circles. — See Rolling Curves. 
 
 Boiling Collar. — The half slirouding of gear wheels, which, terminating 
 in each wheel on the pitch line, gives rolling contact on that line, and 
 consequent ease and regularity of motion, in addition to strength. 
 
 Boiling Contact. — The communication of motion by means of friction 
 wheels and toothed wheels. 
 
 Boiling Curves, or Boiling Circles. — A term given to templet curves used 
 in striking out the shapes of the teeth of gear wheels. The funda- 
 mental circles (q.v.) are represented by arcs of circles, inner and outer 
 respectively, laid upon the pitch lines struck on the drawing board, and 
 the generating circles by complete discs, which are rolled upon the 
 fundamental arcs, needle points being inserted in the generating circles, 
 by which the cycloidal curves of the teeth are scribed upon the drawing 
 board or paper. See Wheel Teeth. 
 
 Boiling rriction. — Friction which takes place in the contact of an axle 
 with frictionrollers (q.v.), used to distinguishitfrom sliding friction (q.v.) 
 
 Boiling Load, or Moving Weight. — A load which is neither concentrated, 
 nor distributed simply, but "which, either concentrated or distributed in 
 its mass, is nevertheless in a state of motion over a structure, as in the 
 passage of a railway train over a bridge. 
 
 Boiling Hill. — The mill in which puddled bar is converted by rolling into 
 merchant iron. See Puddling Rolls, Forge Train, Merchant Train, 
 Roughing Rolls, Three High Rolls, &c. All the various sections of 
 malleable iron bars are imparted during the processes of rolling. 
 
 Boiling Mill Engine. — The term cannot be said to refer to any special 
 type, but rather to the work which it is designed to perform. AH the 
 main types of engines are employed in rolling mills, condensing and 
 
292 DICTIONARY OP TERMS USED IN 
 
 non-oondensing, horizontal and vertical, reversing and non-reversing 
 They are massive and well made, suitable for the heavy work which 
 they have to do. 
 
 HoUing Oil. — Oil used for lubricating the surfaces of metal passed be- 
 tween cold rollers. 
 
 Boiling Over. — The turning over of a foundry box after one-half has been 
 rammed up. Strictly speaking, that process of moulding by which both 
 sides of a pattern are directly rammed up, in contradistinction to tlie 
 bedding in method, where the top side only is rammed and the bottom 
 is bedded in the floor and packed around with sand. 
 
 Rolling Parallel Eule.— See Parallel Rule. 
 
 Bolls. — Cylinders of cast iron, ranging from a few inches to three or four 
 feet in diameter, used in the processes of the manufacture of the various 
 sections of malleable iron and steel. The cylinders are plain, or grooved, 
 according to the sections which they are designed to produce. Por spe- 
 cific terms see Puddling Rolls, MiU Rolls, Porge Train, Two High Rolls, 
 Three High RoUs, Grain RoUs. 
 
 Boll Squeezers. — Rolls used as squeezers for consolidating puddled balls 
 into blooms. The squeezer contains three roUs, two of them side by side 
 and on the same level, and an upper one capable of adjustment upwards 
 or downwards. The length of the bloom is fixed by eoDars on the 
 lower rolls, and its diameter by the adjustment of the top one. 
 
 Eoman Balance. — See Steelyard. 
 
 Eoofing Stays. — See Roof Stays. 
 
 Boof Stays, or Boofiug Stays. — The stays which stiffen the roof of the 
 fije box of a locomotive or portable engine. See Girder Stays. 
 
 Boof Truss.— See Truss. 
 
 Bope Crane. — A travelling crane driven by an endless rope of cotton cord 
 or of hemp. The source of power may be attached to or be distinct 
 from the crane. The cord travels at a very high speed, so that a 
 minimum of power is required to lift a heavy load. The tension of the 
 cord is maintained, and its slack taken up by tightening pulleys having 
 their bearings in sliding frames, which are counterbalanced by sus- 
 pended balance weights. 
 
 Bope Oearing. — Power is conveniently transmitted to a long distance by 
 means of ropes running at a high speed. They are principally applicable 
 to machinery to which the power has to be conveyed to a considerable 
 distance, as the ropes should hang loosely on their pulleys in order to 
 increase the extent of the arc of contact. The driving power is due 
 principally to the weight of the ropes, and they should fit slack to 
 prevent undue wearing of the strands in the grooves of the pulleys. Tho 
 pulleys should be large — that of the smallest should not be less than 
 30 times the diameter of its rope. It is more convenient to use several 
 small ropes than two or three large ones. The pulley grooves should be 
 turned as smooth as possible to diminish imdue wearing of the strands 
 of the ropes. 
 
 Bopes. — Ropes are used for the transmission of power over long distances, 
 as being more suitable than belt and toothed gearing. Ropes are made 
 of Rus.sian hemp and tarred, or of Manilla fibre, or of cotton, or steel, 
 or iron wire. The twist of the strands of which a rope is composed 
 diminishes its strength, but is necessary to bind it together continuously. 
 Tarred hempen ropes are the weakest, steel wire ropes the strongest. 
 The sizes of ropes are given in their girth or circumference, and 
 their weight in pounds per fathom. 
 
MECHANICAL ENGINEERING. 2qj 
 
 Eope Wheel. — A sheave pulley whose groove receives the bight of a rope 
 for hauling purposes. The rim is veed in section, but often -waved in 
 the circumferential direction. See "Wave Wheel. Hope wheels are 
 used for overhead travelling cranes, hoists, &c. 
 
 Eose Bit. — A soUd cylindrical paraUel boring tool, used for making drilled 
 holes straight and paraUel and of equal diameter. This it effects by 
 cutting only in front, or rather where the front merges into the 
 parallel sides, the front edge being rounded shghtly and serrated into 
 a succession of small cutters so that the end is imagined to bear some 
 rude resemblance to the whorl of a rose blossom. The rigid solid 
 cyhndrical body prevents the tool from being drawn to one side by the 
 irregularities of the original rough drilled hole. The difference between 
 a rose drill and a broach, or reamer, with which it is sometimes con- 
 founded, is that the latter cuts at the sides, the former at the front 
 rounded portion only. 
 
 Eose End. — A strainer (q.v.). 
 
 Eose Jet. — The perforated strainer or nozzle at the end of a water hose 
 employed for irrigation or other purposes. 
 
 Eose Eeamer. — A broach, both fluted and having a rose end. 
 
 Eosette Copper. — A variety of copper obtained by throwing water upon the 
 surface of the molten metal, the result being that it solidifies in thin 
 films. 
 
 Eosin. — See Resin. 
 
 Eotary Blower. — A blower (q.v.) whose essential characteristic is the 
 rotation of fans or pistons in a cylindrical case. The fans are usually 
 either radial or curved. The pistons are double or treble ended, and so 
 formed and pivoted that during rotation, escape of air is prevented by 
 their accurate and close fitting within the cylinder, and next each other't 
 
 Eotary Cutter. — A cutter (q.v.) which is rapidly rotated on a spindle in 
 order to impart a definite outline and a clean surface to a wood or 
 metal blank. The teeth of gear wheels are thus formed. Milling 
 cutters are rotary cutters; also the surfaces of timber boards and of 
 moulded edges are produced with cutters set in a revolving adze 
 block. The rate of revolution is variable, though very high in most 
 cases. Cutters set in slowly revolving boring bars are not properly 
 included under this head. 
 
 Eotary Engines, — Applied to steam engines whose pistons have a rotary 
 movement. 
 
 Eotary Furnace. — See Revolving Furnace. 
 
 Eotary Pistons. — The pistons of rotary engines, pumps, and blowers. 
 They are circular, or segments of circles, with or without sliding pieces 
 or abutments moving in grooves in their bodies. The pistons of 
 blowers are also called wafters. 
 
 Eotary Puddler. — See Revolving Furnace. 
 
 Eotary Pumps. — Steam pumps in which the necessary action is produced 
 by the revolution of segmental pistons around their axes. This is also a 
 general term appUoable to all pumps whose pistons have a rotary or 
 circular motion. See Centrifugal Pump. 
 
 Eotary Squeezer. — A form of squeezer used in the consohdation of 
 puddled ball. It consists essentially of two cylinders, an external and 
 internal, whose surfaces in opposition are roughened, and their axes set 
 eccentrically one with the other. The ball introduced at the widest 
 portion of the space between the cylinders is carried round by the 
 rotation of the inner drum and squeezed between the narrower spaces. 
 
294 DICTIONARY OF TERMS USED IN 
 
 Eotary Vice. — A swivel vice (q.v.). 
 
 Botating Valve. — A cylindrical valve which turns upon its longitudinal 
 axis, thus opening or shuttiag ports or passages against which its 
 circular face abuts, its body being pierced with a hole to allow of the 
 passage of fluid in certain positions. See Plug Valve. It is thus dis- 
 tingnished from disc valves, lift, and slide valves. 
 
 Botating, or Eotational Weights. — Usually applied to the weights which 
 tend to equalise the varying angular velocities of engine crankshafts, 
 fly wheels, machinery, paddle wheels, propellers, the balance weights 
 of locomotives, &c. 
 
 Kotator. — A revolving furnace (q-v.), 
 
 Eough Coat. — The first coat of loam applied to a loam pattern, mould, or 
 core. 
 
 Bough Cut. — (1) The term used to designate the coarsest kindof ffle made. 
 The degree of coarseness depends upon the length of the file. In ono 
 of 12 in. in length there would be 40 rows of cuts to the hnear inch. 
 (2) A first thickness of shaving removed from a piece of metal work 
 in a lathe, shaping, or similar machine. The rough cut is taken to 
 penetrate under the skin. 
 
 Bough Dimensions. — It is necessary to give certain allowances of extra 
 thickness of metal in aU work which has to be machined, whether castings 
 or forgings, so that they are larger by this amount than the finished 
 dimensions (q.v.). These are called the rough dimensions, and in the 
 pieces of work, whether rough castings or rough forgings, so long as 
 sufficient thickness is allowed for machining, very close accuracy is not 
 looked for, nor is necessary. 
 
 Boughing. — See Roughing Down. 
 
 Eoughing Down or Boughing. — The removal of the largest bulk of 
 material, including the outer skin or scale, from a piece of work, pre- 
 paratory to the more accurate and final bringing to shape with finish- 
 ing outs. 
 
 Boughing Out. — Sometimes used in the sense of roughing down (q.v.), 
 but more properly signifies the first preparation of a forging, or a piece of 
 wood work from the crude material. A forging would be roughed out 
 when produced by swaging, jumping up, and welding from the original 
 bar, while not yet finished with the fullering and flatting tools, dies, 
 or final swagings. A pattern would be roughed out when the stuff 
 was brought nearly, but not accurately to dimensions. A piece of 
 bright metal work would be roughed out when it leaves the slotting 
 or shaping machine, or when chipped rudely to shape. 
 
 Eoughing EoUs. — The first roUs used for rolUng puddled bar, in which 
 the bloom is squeezed and consolidated and brought roughly to shape. 
 See Puddling EoUs, MiU Rolls, Plaf« MiU. 
 
 Eoughing Tool. — The ordinary tool used by iron turners and machinists 
 for removing the outer skin, and generally for turning cast iron, wrought 
 iron, and steel. It is either of the sohd cranked form or is a short 
 length of rod held in a cutter bar. Its angles vary with the material 
 upon which it is used. 
 
 Bound Backed Angles. — See Angle Iron. 
 
 Bound Bar Iron. — See Bar, Rod. 
 
 Bound Body Valve. — A pump valve whoso body is of cylindrical shape. 
 
 Bound File. — A file circiilar in section. Round files are either tapered 
 or parallel, the tapered files of small size being termed rat tail files 
 (q.v.). Round files are used generally for enlarging holes and shaping 
 
MECHANICAL ENGINEERING. 295 
 
 hollo-w curves. Bound parallel files are also used for guUeting the 
 teeth of large circular and pit saws. 
 
 Round Head Screws, — Button-headed scre-ws (q.v.). 
 
 Bounding Tool. — A swage tool hollowed to a semi-cylindrical section and 
 used bj smiths for rounding and finishing iron rods. 
 
 EoundNose Tool, or EoundTool. — (1) A chisel whose cutting edge, round- 
 ing in plan, is used both in wood and metal turning for finishing curred 
 and hollow parts. (2) A stout tool similar in shape to the fore- 
 going, but narrower, used by fitters for cutting oil grooves in brasses 
 and on broad bearing surfaces. 
 
 Bound Plane. — A plane, the edge of whose cutting iron is an arc of a 
 circle, and which therefore planes hollow. Used by carpenters and 
 pattern makers. The sizes of the planes are indicated by numbers, the 
 lowest and smallest sweep being No. 1, and the highest and largest 
 being No. IS. 
 
 Round Tool. — See Round Nose Tool. 
 
 Eouter. — The lip on a centre bit or Jennings bit, which removes the 
 wood within the circle cut by the nicker (q.v.). 
 
 Eoyal Drawing Paper. — Measures 24 x 19J. 
 
 Eubber, or Glass Paper Eubber. — (1) Aflat rectangular piece of cork glued 
 to a similarly shaped wood backing, and used in applying glass paper to 
 woodwork. The cork is more elastic than wood alone and does not 
 work so harshly. Rubbers are cut also into various outlines, curved or 
 otherwise for special work. (2) India-rubber (q.v.). 
 
 Eubber File. — A coarse heavy file used only in the roughest work, and 
 seldom by engineers. 
 
 Eubber Hose. — Hose pipe built up of vulcanised india-rubber. This is 
 superior to canvas hose (q.v.). 
 
 Eubbing Board. — A flat board measuring about 6 in. X 3 in., held in the 
 hand and used for sleeking over the flat faces of foundry moulds pre- 
 vious to the final smoothing with the trowel and the blackening. 
 
 Tluhbish Pulley.— See G-in Block. 
 
 Eule. — A standard of measurement. See Arch Joint, Contraction Riile, 
 Standard Rule, Square Joint. Engineers' rules are either two feet, two 
 fold, that is, having one joint only ; or one foot steel rules (q-v.). 
 
 Eule Measurement. — Used for all ordinary dimensions, but is not 
 admissable for work requiring great exactness ; trammeling off (q.v.) 
 and the use of calipers, with ordinary, and micrometer gauges, &c., 
 being employed instead. 
 
 Bumble, or Battle Barrel, or Tumbler. — A hoUow revolving cylinder, 
 used for the purpose of cleaning off castings from the sand which 
 clings to them from the moulds. The eastings are enclosed loosely in 
 the revolving cylinder and become cleaned by their mutual attrition. 
 
 Bumbling. — The cleaning of castings in a rumble (q.v.). 
 
 Bunuer. — The channel or passage through which the molten metal passes 
 from the gate into a mould. 
 
 Bunner Head. — The mass of metal which fills the ingate (q.v.) of a 
 foundry mould. Runner heads and feeder heads (q.v.) are knocked 
 off while red hot, and are in request in the foundry for cooling very 
 hot metal just tapped into the ladles. They are dropped in the molten 
 metal, and in becoming remelted, lower the temperature of that in the 
 ladle. 
 
 Eunner Pin, or Bunner Stick., — A tapered pin, cylindrical or rectangular 
 in section, used by iron moulders as a patterq from which the runner 
 
296 DICTIONARY OF TERMS USED IN 
 
 (q.T.) is formed for a mould. The sand is rammed around it in the 
 usual way, and on the -withdrawal of the pin a passage remains for the 
 inflow of the metal. 
 
 Runner Stick. — See Kunner Pin. 
 
 Running Away. — (1) Eaoing (q.v.). (2) The escape of metal from a mould 
 in the act of pouriag, due to bad jointing of the sand. When it occurs 
 in quantity, a waster casting results. 
 
 Running Centre Chuck. — A driver chuck (q.v.) so called because it re- 
 Tolves with the lathe, as opposed to the similar points in a dead centre 
 lathe (q.T.). 
 
 Running Down. — The melting of iron in a cupola. When a charge of 
 iron is aU melted, or completely liquid at the tap hole, it is said to be 
 nm down. A deftnite charge takes a defiuite time to run down, the 
 time being variable with the character of the cupola, and the nature of 
 the fuel and the blast, but constant for the same cupola. 
 
 Running Gate. — The ingate (q.v.) of a mould as distinguished from a 
 riser (q.v.) or rising gate. 
 
 Running In. — An engine is said to run in when the' valve is so set that 
 the top of the fly-wheel rim runs towards the cylinder. 
 
 Running In Refinery A refinery (q.v.) which is built close to the blast 
 
 furnace and into which the molten iron is run direct from the latter. 
 See Melting Down Eefinery . 
 
 Running Out. — (1) An engine is said to run out when the valve is so set 
 that the top of the fly-wheel rim runs away from the cylinder. (2) The 
 slipping or working of a drill to one side of the centre in which it was 
 started, due to carelessness in centring, or to improper setting of the 
 work, or to a badly formed drill, or to the influence of inequalities on 
 the surface of the work itself. It is remedied by recentring with the 
 centre punch if the hole is not entered deeply, and by chipping out if 
 it is too deep for punching. If very deep the evil is incapable of remedy 
 except by filing, or broaching, or boring, or drifting, according to 
 circumstances. (3) "When a piece of work is not chucked truly in a 
 lathe, but is eccentric, it is also said to be running out. 
 
 Running Out Fire. — See Eefinery. 
 
 Running Pulley. — (1) The movable pulley in a snatch block (q.v.) and in 
 lifting tackle generally. (2) A gin pulley. 
 
 Run Out. — The escape of metal from a mould during the act of pouring, 
 due to open joints somewhere, caused by bad fitting of the moidd itself, 
 or of cores, or through straining of the flask parts. 
 
 Rust, or Red Rust. — The hydrated peroxide of iron (2Pej O3 3H2 0) 
 formed by union of iron with the oxygen of the air, producing slow com- 
 bustion. It is prevented in the workshop by brushing newly fettled 
 castings over with a coat of boiled oil, and by painting finished work 
 with three or four coats of oil paint. 
 
 Rusting. — The coating of bright iron patterns with rust in order that they 
 may take the shellac varnish without risk of its peeling off. Busting is 
 accomplished rapidly by rubbing the iron over with a solution of sal-am- 
 moniac in water, or of weak hydrochloric acid, and allowing it to dry. 
 
 Rust Joint. — A joint used by engineers where iron and iron have to be 
 caulked to withstand water pressure. It is made by filling the joint 
 with iron borings and sal-ammoniac, to which sulphur is sometimes added, 
 and which hardens in a day or two. 
 
 Rymer. — A reamer (q.v.). 
 
 Rymering. — The practice of enlarging by means of a rymer or reamer 
 
MECHANICAL ENGINEERING. 297 
 
 (q.T.) toles Tvliioli have been already punched or drilled. The advan- 
 tages of rymering are : that in holes roughly drilled the ridges or 
 arrisses left by the drill can be removed and the hole left truer ; that 
 holes in plates which have been punched or drilled and "which are not 
 exactly fair can be made to correspond by clampiug the plates together 
 and passing the rymer through both at once ; also, that in punched 
 holes the local tension set up in the immediate vicinity of the holes is 
 removed entirely by rymering them about t'g m- larger in diameter. 
 
 s 
 
 Saddle. — ^The base of a slide rest -which lies on the lathe bed, and -whose 
 edges embrace the edges of the Vees. Similarly, the shding plate -ivhich 
 carries the drill spindle and gear -wheels of a radial drill. The Beatings 
 or supports -which carry horizontal cylindrical boilers, both land and 
 marine, are called saddles. These are made both in -wrought and in cast 
 iron. 
 
 Saddle Back Bail, or Barlow Rail. — A rail -whose sides curve rapidly out- 
 -wards and do-wn-wards, in order to pro-ride a broad base for the laying 
 of the raU directly on the ballast -without the necessity for the inter- 
 vention of sleepers. Its shape is inherently -weak. 
 
 Saddle Flange. — A curved flange hollowed out to fit a boiler, a pipe, or 
 other cylindrical vessel. 
 
 Saddle Key. — A key (q.v.) whose inner face is hoUo-ned to fit its shaft, 
 instead of the shaft being either flattened or recessed for its reception 
 as is the case -with ordinary keys. 
 
 Saddle Tank.— See Saddle Tank Engine. 
 
 Saddle Tank Engine. — A locomotive engine in which the water tank 
 envelops the top and sides of the boiler, thus presenting the appearance 
 of a saddle. 
 
 Safe Edge File. — A file having one or more edges left uncut, in order that 
 the smooth edge may serve as a guide only to the actual cutting faces 
 of the file. 
 
 Safety, Factor of. — See Factor of Safety. 
 
 Safety Hoist. — Any hoist constructed -with differential pulleys. Also an 
 ordinary rope hoist in which an automatic catch or safety stop (q.v.) 
 secures the rope against running do-wn. 
 
 Safety Ladle. — The tipping of a heavy ladle for the purpose of pouring 
 its contents into a mould was formerly effected by the power of men 
 applied to levers fixed on the axis of its trunnions. To obviate the risks 
 attendant upon this clumsy method, Nasmyth applied the screw and 
 worm wheel movement thereto. One man by turning a handle aflixed 
 ■to a worm or screw shaft can then move several tons of metal with ease. 
 This is called the safety ladle, and is now universally employed in 
 foundries. G-eared ladles of the largest size are often pro-rided -with a 
 pair of mitre wheels in addition to the worm gear, by which more power 
 is gained. 
 
 Safety Plug.— A fusible plug (q.v.). 
 
 Safety Kail. — A guard rail (q.v.). 
 
 Safety Stop. — An arrangement applied to lifts and elevators for the pur- 
 pose of checking their descent in case of the accidental breaking of the 
 rope or chain. It usually consists of levers or springs which on thp 
 
298 DICTIONARY OF TERMS USED IN 
 
 release of the lift throw a paul into gear with a ratchet, one being placed 
 upon each side of the shaft. 
 
 Safety Valve. — The escape or relief valve by which excessive and unsafe 
 pressure in steam boilers is prevented. It consists essentially of a lift 
 valve of some one shape or another, and contains mechanism for impart- 
 ing to the valve a definite pressure. The mechanism is either a lever 
 with an adjustable weight, or a spring whose strength is known, and 
 whose tension may be adjusted by a movable nut ,' or a dead weight, or 
 Cowbum valve (q.v.). 
 
 Safety Valve Lever. — A loaded lever, the valve to be opened by steam 
 pressure lying between the fulcrum and the load or weight ; its prin- 
 ciple being that the weight of the total steam pressure on the valve 
 multiplied by its distance from the fulcrum is equal to the weight on the 
 lever multiplied into its distance from the fulcrum. This takes no account 
 of the weight of the lever itself, or of the valve, which must also be 
 considered. 
 
 Safety Valve Seating, — (1) In Cornish andLancashire and marine boilers, 
 the safety valve is not attached directly to the boiler shell, but to an 
 intermediate casting called its seating. It is more convenient, and safer 
 in practice to fit a seating to the curve of the boiler, and provide it with a 
 flange for the attachment of a valve shell, than to fit the latter directly. 
 (2) The annular opening on and within which the valve fits and 
 through which the steam escapes, is called the seat or seating. This is 
 usually a gun-metal casting distinct from, and driven into the safety 
 valve shell. 
 
 Safety Valve Shell. — The cast-iron casing which carries the gun-metal 
 seating of a safety valve. 
 
 Safe Working Load. — That which is obtained by diriding the load which 
 would produce fracture or crippling, by a factor of safety (q.v.). 
 
 Sag. — The vertical and lateral sway of a rope or belt due to stretching 
 and slackening. 
 
 Saggers. — Cast-iron boxes used for packing the castings and sifted red 
 haematite, in readiness for the annealing oven, in the process of manu- 
 facture of malleable cast iron (q.v.). 
 
 Salamander. — See Scaffold. 
 
 Sal-ammoniac. — Symbol NHi CI. The chloride of ammonia obtained as 
 a bye product in gas manufacture. Its uses are various. It is used as a 
 flux for tinned surfaces which are to be brazed, and as an ingredient in 
 rust cement, and for the rusting of iron patterns. It is also sometimes 
 used to prevent or to remove incrustation in steam boilers. This it 
 effects by the formation of chloride of lime which is soluble in water. 
 It requires caution in its use, as the carbonate of ammonia formed will, 
 if it becomes concentrated, attack the metal work. 
 
 Salinometer. — An instrument used for testing the degree of saltness present 
 in the water used in marine boilers. The instrument used, is either the 
 thermometer by which the boiling point of the water is ascertained and 
 the amount of saturation deduced therefrom, or a hydrometer especially 
 marked for degrees of saltness, by which the specific gravity of the water 
 is measured. 
 
 Salting, — The accumulation of a deposit of salt on the plates of a marine 
 boiler. A certain amount of salting is not injurious to the plates, but 
 the density of the water should not exceed -fg, or from 8 to 10 ounces of 
 salt to the gallon. See Two Salt Waters, 
 
 Salt Water. — See Sea Water. 
 
MECHANICAL ENGINEERING. 299 
 
 Sampling. — The process of judgiag of tlie quality of pig iron or steel bj 
 the appearance of a newly fractured surface. A small button of metal 
 is removed from the furnace and either flattened out or broken mtb a 
 sledge, and by the appearance of the fracture, or by a ready chemical 
 test, or both combined, the properties of the metal are inferred, and any 
 necessary "alteration made in the proportions of the ingredients, or in the 
 conditions of working. 
 
 Sand, — Sand is formed by the decomposition of sandstone (q.v.) rocks, and 
 is of very various composition and degrees of hardness. Its basis 
 is silioa, but this is so iutermised with other substances as to produce 
 compoimds varying greatly in characteristics and uses. Some are 
 highly infusible, others very slightly refractory. The uses of sand 
 in engineering work are multifarious and are described under their 
 specific headings. See Old, Dry, Green, Strong, Eoad, Core Sand, 
 Loam, Ganister, &o. Sand is also sprinkled by smiths over thosa 
 joints which have to be welded together in order to protect them from 
 oxidation by the atmosphere. The sand forms a glassy scale at the 
 welding temperature. Sand and water are used for the scouring of 
 the sheet-iron plates used in the tin manufacture. 
 
 Saad Bank. — In foundries where small pipes are cast in quantities the 
 moulding boxes are placed, and the metal run on a bank of sand sloping 
 at an angle of about 45° with the horizontal. The pipes are sounder 
 when made by this method than horizontally, since the suUage rises to 
 the upper portion as is the case when castiag upright. 
 
 Sand Bed. — (1) The bed of sand in front of a blast furnace into which the 
 sow and pigs are run. (2) Any bed of foundry sand, level or sloping, 
 on which a moulding box or pattern is laid. 
 
 Sand Bin. — A trough or compartment in, or adjacent to foundries, used 
 as a convenient receptacle for sand required for the use of the moulder, 
 the different sands being kept in separate bins. 
 
 Sand Blast Sharpening. — The sharpening of files by the direction of a 
 current of sand and water across the teeth and along the file at an 
 angle. The mixed current is discharged by the introduction of a steam 
 jet. The sand is as fine as flour emery. Files sharpened thus are con- 
 sidered superior to those cut in the ordinary manner. 
 
 Sand Box. — (1) A box containing a selected quantity of foundry sand for 
 moulders' use. Sand boxes are kept at hand in all classes of work both 
 hand and machine. In moulding machines the boxes are either above, 
 or underneath in the base of the machine. (2) A box used on locomotives 
 as a receptacle for sand, which being allowed to fall on the rails in 
 slippery weather increases the adhesion of the wheels. 
 
 Sand Burned. — Castings become burned, or sand burnt, when the metal is 
 poured into the mould at too high a temperature, in which case the 
 surface of the metal combines with the silioa in the sand and becomes 
 extremely hard and rough or chilled. The use of plumbago or of 
 blacking is to interpose a protective infusible medium between the 
 actual sand and the intensely hot metal. 
 
 Sand Joint. — The parting or joint between the different portions of the 
 sand of a foundry mould. 
 
 Sand Mixer. — Amachine used in mixing sand for foundry use. 
 
 Sand Mixing. — The mixing of sands for foundry use is an art for which 
 no directions can be laid down, being altogether within the range of 
 practical experience. The proportions of the different sands necessary 
 to produce any given result varies also with the locality from which the 
 
300 DICTIONARY OF TERMS USED /.V 
 
 sands are obtained. For special notes see Strong Sand, Core Sand, 
 Dry Sand, Loam, and other specific headings. 
 
 Sand Paper. — See Glass Paper. 
 
 Sand Papering Machines. — See G-lass Papering Machines. 
 
 Sand Pit.— See Poundiy Pit. 
 
 Sand Plug.— See Plug. 
 
 Sand Pump. — A pump used for drawing the wet sand out of caissons, pits, 
 and mines, and in prospecting for gold and diamonds. It is of the 
 centrifugal type. 
 
 Sand Eat. — A slang term commonly applied by iron moulders to members 
 of their craft. Sand puncher is also a favorite cognomen. 
 
 Sand Sifter. — A machine made for sifting foundry sand, and worked by 
 hand or power. For sifting sand in small quantities sieves or riddles 
 are employed. There are different forms of machines, small sifters rest- 
 ing on supports, larger ones being suspended from suitable beams. The 
 principle in each is as follows. An open sieve of rectangular form has 
 a to-and-fro oscillatory movement imparted to it by means of three teeth, 
 which as they are revolved by means of a winch handle within a slotted 
 block impart to it alternately a back and forth motion, this being com- 
 municated through a rigid rod to the frame of the sieve. The move- 
 ment is much more rapid than can be imparted by hand sieves, hence 
 the advantage of using the mechanism. 
 
 Sand Sifting. — AH foundry sand is subjected to a process of sitting or 
 riddling before being mixed and used, the object of sifting being the 
 removal of lumps and gravelly stones and foreign matters. 
 
 Sandstone . — Sandstones are of various composition and degrees of hard- 
 ness. They consist essentially of silicious sand cemented together with 
 carbonate of lime, oxide of iron, or clay, hence called calcareous, ferru- 
 ginous, or argillaceous sandstones. They furnish the various foundry 
 sands (q. v. ) , the linings of furnaces, are mixed with fire clays, and some fire 
 bricks, and yield the ganister for converters, and steel moulds. They occur 
 as rocks and as loose friable deposits, and are termed, according to their 
 physical appearance and locality, rock sand, sea sand, pit sand, free 
 sand, &c. 
 
 Sand Valve. — The valve by which the escape of sand from the sand box of 
 a locomotive is regulated. It is under the control of the driver, being 
 actuated by a foot lever. 
 
 Sap. — The circulating fluid in timber which conveys the elements of 
 nutrition to the tree. 
 
 Sappy. — Timber is said to be sappy when it is foxey (q.v.) or when it has 
 not been properly seasoned, so that the sap remains in large quantities. 
 
 Sap 'Wood. — The wood which lies immediately underneath the bark of a 
 tree. It is of little value, and rapidly undergoes deterioration when in 
 the plank. 
 
 Saturated Steam. — Steam is said to be saturated when it remains in con- 
 tact with the water from which it has been generated. It then holds 
 a quantity of moisture in suspension, and is not in the condition of a 
 true gas. Also called dry steam (q.v.) and vaporous steam. 
 
 Saturation. — A vapour is said to be saturated when it is at the greatest 
 density and pressure corresponding with its temperature, and when 
 therefore an increase of pressure or decrease of temperature would 
 cause some of the vapour to be condensed. It is on the point of con- 
 densation, and is therefore in a different condition from that of a true gas. 
 
 Saw. — A tool having a serrated blade, and furnished with a handle or 
 
MBCnAmCAL ENGINEERING. 301 
 
 frame. The saw plate is of steel, the temper of tlie steel varying with 
 the natiire of the work which the toolhas to do, beinghard in most cases, 
 hut soft for band saws. The saws used in the departments of engineer- 
 ing are the hand saw, the back, frame, and pad saws, the pit, deal 
 frame, and circular saws for wood, and the hack saw for metal, noted 
 under their special headings. 
 
 Saw Bench, or Saw Table. — The bench of a machine saw, upon which the 
 timber is supported while being cut. Sometimes the word bench is used 
 more especially when speaking of circular saws, and table in reference 
 to band and jigger and fret saws. 
 
 Saw Dust. — This is used for cleaning the oil from bolts, and also, mixed 
 with loam, for the same purpose as horsedung (q.v.). 
 
 Saw Fence.— See Fence. 
 
 Saw Files. — Piles made specially for the use of the saw sharpener, though 
 employed also for other work. They are known uride.r various names 
 and made in various classes, mostly as second cut (q.v.) and smooth (q.v.) 
 and both single cut (q. v. ) and double cut (q.v. ) . They are either taper tiles 
 (q.v.) or blunt files (q.v.), and of great range as regards length. For 
 saws having triangular teeth simply, the ordinary triangular single cut 
 taper files are used, but for circular and pit, and large frame saws, the 
 parallel, blunt, double-cut, flat-faced, round-edged files, and the parallel 
 blunt, round double-cut files are employed. 
 
 Saw Filing Machine. — A machine used for filing band saws, in which the 
 file is carried to and fro by an arm provided with a rectilinear motion, 
 at the same time that the saw is traversed along a distance equal to a 
 single tooth for each traverse of the file. 
 
 Saw Frame. — (1) A swing frame (q.v.). (2) The frame of a bow saw (q.v.). 
 
 Saw Gullet. — The curved bottom or root or interspace between contiguous 
 saw teeth. The teeth of the larger saws alone aregulleted, the object being 
 to secure freedom or clearance for the sawdust without choking the 
 saw or causing it to work hard, GruUeting, called also saw gumming 
 (q.v. ),is only performed once to every two or three times of sharpening. 
 
 Saw Gumming. — The grinding out of the gullets or roots of circular saw 
 teeth by means of emery wheels, the sections of whose edges are the 
 counterparts of the tooth spaces. 
 
 Sawing. — The division of material by means of sawteeth. The saving of 
 a given quantity of material and the minimum expenditure of power 
 depends partly on the shape of the saw teeth, partly on the degree of 
 thickness of the blade. The thinner the blade consistently with the 
 work the saw has to perform, the easier the task and the less the waste 
 of material. Sawing demands under any circumstances a great ex- 
 penditure of power, hence saws are where practicable thinned down 
 towards the back, which together with set, enables the plate to clear itself 
 in the cut. Circular saws and band saws are in addition lubricated 
 with tow soaked in tallow and oil. 
 
 Sawing Stool. — A low trestle upon which timber is laid, which hag to be 
 sawn by hand. 
 
 Saw Pit . — The pit used in country districts upon which timber is laid when 
 being out into planks and boards, the bottom sawyer working in the pit. 
 
 Saw Set. — A tool or appUanoe used for setting the teeth of saws. It is 
 either a plyor set, or a setting hammer and round-faced block, or it is a 
 special contrivance of an automatic character, of which latter there are 
 many kinds. 
 
 6aw Setting. — The bending over of the teeth of a saw to right and left 
 
JOS tilCTIONARV OB TERMS USED IN 
 
 alternately, in order to make the kerf formed by the teeth somewhat wider 
 than the saw blade, so that the latter shall move with the minimum ot 
 friction therein. The setting of saw teeth is not usually done at each 
 time of sharpening, but at about every second or third sharpening. 
 
 ^aw Sharpening. — The bringing of the teeth of saws to a keen edge when 
 dulled by use. It is efieoted by files, mostly worked by hand. The 
 sharpening is done from each side of the blade, every alternate tooth 
 being filed from one side, and afterwards all the intermediate teeth from 
 the side opposite, the teeth being filed in the same direction in which 
 they lean, both to prevent screeching of the saw, and to give a buiT on 
 the cutting edge. For sharpening small saws a single triangular file 
 is used, for larger saws a flat file having rounding edges for gulleting, 
 or a flat file for the points and a round file for gulleting. 
 
 Saw Spindle. — The spindle which carries a circular saw. It consists of a 
 turned spindle furnished with bearing necks, fast and loose pulleys, 
 and a couple of washers, one fixed, the other movable, and tightened 
 with a nut, the saw being clamped between the two washers, and pre- 
 vented from turning by a feather fitting into a slot cut in the hole in the 
 centre of the saw. 
 
 Saw Table. — See Saw Bench. 
 
 Saw Teeth. — The angles of saw teeth vary with the work they have to do. 
 The angles of the faces are from 80° to 86° for hard, 65° to 70° for soft 
 wood, and the relief angle is 65° to 70° for hard, 45° to 50° for softwood.; 
 The spacing and the set should be greater for soft than for hard wood. 
 For cross cutting, the teeth are set farther back than, for ripping. 
 
 Scab. — An excrescence upon a casting caused by the washing out of a 
 corresponding portion of the sand in the mould, due principally to im- 
 proper ramming. The presence of the scab is not in itself very objec- 
 tionable since that can be chipped off, but in most cases where scab is 
 present the sand which has been washed away is located somewhere ia the 
 body of the casting, with the result of rendering it hoUow and unsound. 
 
 Scaffold, or Salamander. — A mechanical obstruction in a blastfurnace due 
 to one or two or several causes in combination, as bad fuel, slag, bad 
 charging, or a badly shaped furnace, and which by its presence interferes 
 with the proper working of the furnace. 
 
 Scale, — (1) Atermsignifyingtherelative proportionsof parts, andapplied in 
 mechanics to any instrument by which proportional parts are obtained. 
 Specially an instrument for making or measuring drawings which are 
 not drawn to fuU size, but to some proportional fraction of actual di- 
 mensions. Thus if an inch upon a drawing represents a foot on the actual 
 piece of work, that is said to be drawn to a scale of an inch to a foot. That 
 inch will be divided into twelve equal parts, and each twelfth part repre- 
 sents an inch of actual dimension. A fuUy divided scale is one each 
 inch of whose whole length, usually of twelve inches, is subdivided thus 
 into twelfths, so that a minute measurement can be taken at any part 
 of its length. Aji open divided scale is one in which the end or terminal 
 dimension only representing the foot, is divided into twelve parts, the 
 parts intermediate being only partly divided. An open divided scale 
 will thus contain more separate and distinct scales than a fully divided 
 one, as for instance | in. at one end and 1 J in. or 3 in. at the other. 
 Main divisions from which the scale takes its name, as ^ in., 1 in., 2 in., 
 are termed the primary divisions of the scale. (2) The carbonate of 
 hme which accumulates on the interior of boiler plates, and which is 
 deposited by hard water. 
 
MECHANICAL ENGINEERING. 303 
 
 Scaled Drawing.- — A dramng made smaller than tlie ■work -whioli it repre- 
 sents, but to a definite proportion wHcli is specified on the drawing 
 itself. See Scale. Many -working drawings are made to full size 
 (q.v.). 
 
 Scale Pan. — See Scum Trough. 
 
 Scaling. — (1) The process of removing the scale (q.v.) from the interior 
 of boiler plates. (2) The taking of dimensions from a drawing by 
 means of a scale (q.v.), in the absence of figured dimensions, or full- 
 sized delineations. 
 
 Scaling Hammer. — A keen-edged hammer used for the removal of the 
 scale (q.v.) from steam boilers, which it effects by a process of chipping. 
 
 Scandinavian Cotton Belting. — A cotton belting solid woven instead of 
 being made in plies. It can be obtained in widths ranging from one to 
 twenty-four inches, and in light, medium, and heavy weft. 
 
 Scantling. — All quartering under five inches square. Also the transverse 
 dimensions of a piece of timber is termed its scantling, as for example 
 a piece having a scantling of 5 in. X 4: in. 
 
 Scarf, — See Scarf Joiut. 
 
 Scarf Joint, or Scarf. — An oblique form of joint used by smiths and by 
 carpenters, for the fastening together of rods of metal and strips of wood. 
 The scarf joint in wood is often assisted and tightened by wedges 
 inserted in the middle portion. 
 
 Scintillation. — Hard white iron scintUlates or throws off sparks when 
 in the ladle, so that the founder knows thereby the nature of the metal 
 while yet iu its molten condition. See Breaking, Jumper. 
 
 Scoop "Wlieels. — ^Wheels employed for lifting water and drawing it away 
 from marshy lands. They are in shape somewhat similar to water 
 wheels, but the place of the buckets is occupied by scoops, and the 
 necessary power is supplied by windmills or by steam engines. These 
 wheels are largely employed in the fen countries. 
 
 Scoria. — (1) Slag (q.v.). (2) SuUage (q.v.). 
 
 Scorification. — The melting of a small quantity of lead along with copper 
 which is intended to be rolled into sheets, so called because of the 
 scoria which collects on the surface. 
 
 Scotch Pig. — For ordinary foundry purposes Scotch pig is that chiefly 
 used, both for light and ornamental castings, and mixed with other 
 brands, for the stronger and tougher castings. No. 1 Scotch, mixed 
 with scrap or with inferior brands, produces useful mixtures. It is 
 smelted from the clay ironstone or black band ores, and exported from 
 the Clyde chiefly. 
 
 Scotch Tuyere. — A form of blast furnace tuyere in which the water is 
 made to circulate around a coil of pipe encircling the tuyere. 
 
 Scouring. — Plates of sheet iron used iu the tinplate manufacture are 
 scoured with sand and water to cleanse them, after preliminary immer- 
 sion in dilute sulphuric acid. 
 
 Scouring Drum. — A rumble (q.v.). 
 
 Scrap. — Broken and worn castings, wasters, &c., clippings and ends of 
 wrought iron and steel bars, and plates. The cast-iron scrap is 
 remelted with an addition of new pig, and the wrought iron scrap 
 is piled or fagoted, and balled up or rewelded into blooms for future 
 use. 
 
 Scraper. — The scraper for wood is a strip of old saw blade, used for 
 smoothing over the face of planed timber whose grain is cross and 
 crooked. It is held a few degrees over the perpendicular and pushed 
 
304 DICTIONARY OF TERMS USED IN 
 
 or dragged over the wood. It is sharpened by forcible burrmg up of 
 the edge with a smooth piece of steel, such as a sorew-driver or gouge. 
 The scraper for metal is a file ground square across and sharpened at the 
 end, and pushed with a straight or semi-rotatory movement over the metal 
 at a few degrees only from the horizontal. It is sharpened upon an 
 oilstone. 
 
 Scrap Heap. — A receptacle for odds and ends of waste material, which is 
 utilised in various ways. Scrap cast iron consists to a slight extent of 
 foundry wasters, but chiefly of old iron bought for the pui'pose of re- 
 melting, while the scrap heaps of wrought iron or steel consist of the 
 accumulation of shop refuse, and odds and ends cut to waste. 
 
 Scraping. — The bringing of surfaces to a very approximate plane condi- 
 tion by means of scrapers. AH good wearing and sliding surfaces are 
 scraped to a fit, to obliterate the coarse marks or grooves left by cutting 
 tools and files, and to increase the number of minute points of contact. 
 By scraping, the work of fitting is locahsed on certain spots for the time 
 being, until at length so perfect a contact becomes possible that one 
 plate will sustain another of equal weight on its under face. There is 
 no mechanical operation by which such perfect results are possible of 
 attainment as by scraping. To indicate the points of contact it is cus- 
 tomary to rub a thin film of red lead and oil on the opposite surface 
 to that which is being scraped, which red lead indicates by its trans- 
 ference to certain highest points the localised points of contact, to which 
 points therefore the work of the scraper is directed. 
 
 Scraping Tools. — Tools which remove the particles from the materials on 
 which they operate by abrasion, mainly or altogether, as scrapers, 
 broaches, reamers, saws. 
 
 Scrap Iron. — See Scrap. 
 
 Scrap Steel. — Scrap steel is utilised in the open hearth processes, being 
 mixed with pig iron and ore in the Siemens-Martin process (q.v.), and 
 in the Siemens process (q.v.) also. 
 
 Scratch Brush. — See "Wire Brush. 
 
 Screen. — A large rectangular sieve set up at an angle with the ground, 
 and used for screening (q.v.) sand for foundry use. 
 
 Screening, — The passing of foundry sand through a screen (q.v.) in order 
 to separate the lumpy from the finer portions, the former being pounded 
 up afterwards and screened over again. 
 
 Screw. — A screw may be defined as a helix wound around a cylinder. 
 The helix may be single, as in a common screw, or double or multiple, 
 as in many forms of feed and endless screws. Tractional portions only 
 of helices may be present, as in screw propellers. The helix, if further 
 analysed, is found to be an inchned plane. The mechanical advantage 
 of a screw (disregarding friction) is in the ratio of the circumference of 
 the arm at which the power is applied to the pitch of the thread. 
 Screws are square or angular in section, right or left-handed according 
 to the direction in which the helix turns ; and they have different names 
 designating their function or shape. They are cut by taps and dies, or 
 in the lathe, and are used for almost all kinds of engineering work. 
 The various terms used in connection with screws and screw threads will 
 be found defined under their special headings. 
 
 Screw Area, — In a propeller is the area of the circle described by the tips 
 of the blades. 
 
 Screw Barrel. — A chain barrel having a continuous spiral groove cut 
 around its periphery to receive the links edgeways, the flat of the alter* 
 
MECHANICAL ENGINEERING. 305 
 
 nate links resting on tlie periphery of the barrel. Designed to maintain 
 an even lap of the chain, and thus prevent overriding. 
 
 Screw Blade. — A sector of a screw thread, forming one of the arms or 
 blades of a propeller screw. 
 
 Screw Blade Area. — The area of the oblique surfaces of the blades of 
 a screw propeller. 
 
 Screw Bolt. — More commonly termed a bolt (q.v.), signifying therefore a 
 fastening made by means of a nut engaging with a screw thread, as 
 distinguished from the riveted form of fastening. 
 
 Screw Chasing. — The cutting, or smoothing and polishing of screw 
 threads in the lathe by means of chasing tools. See Chaser. 
 
 Screw Chuck. — See Taper Screw Chuck. 
 
 Screw Clamp. — The ordinary clamp used by wood workers. Small screw 
 clamps are sometimes called thumb screws to distinguish them from the 
 larger timber or bar clamps. 
 
 Screw Coupling. — The ordinary coupling used for raOway rolling stock. 
 Links are attached to the opposite draw hooks, and these are united by 
 a double screw, right and left hand respectively, by turning which in 
 one direction or another the coupling is lengthened or shortened. 
 
 Screw Cutter's Gauge. — A centre gauge (q.v.). 
 
 Screw Cutting. — The formation of screw threads on cylinders. It is per- 
 formed by taps (q.v.) and dies (q.v.) by chasers (q.v.) and in o, screw 
 cutting lathe (q.v.) sometimes with a traversing mandrel (q.v.). A good 
 screw should have a full thread, be cut clean, and have sharp edges. 
 
 Screw Cutting Lathe. — An iron turner's lathe, in which provision is 
 made for cutting screw threads without the aid of a die, by the use of a 
 screw tool only. The tool is held in the slide rest and traversed in a 
 longitudinal direction to an exact and measured distance for each revolu- 
 tion of the lathe, the traverse being effected by means of a guide screw 
 (q.v.) and change wheels (q.v.). A screw cutting lathe is a self-acting 
 lathe (q.v.) though the latter term is commonly used to designate a lathe 
 which is non-screw.cutting. 
 
 Screw Dies. — See Die, 
 
 Screw Down Valve. — A screw valve. A valve which is raised or 
 depressed by means of a screw. Globe valves, sluice valves, and others 
 similar in type are familiar examples. 
 
 Screw Driver. — Screw drivers are either flat, or rectangular, or circular in 
 section. The latter form is useful to pattern makers because of the 
 facUity which it affords for driving screws down deep into round bored 
 holes. Breadth of handle gives increase of leverage, hence handles are 
 properly made broad, and oval in section. Length also gives more 
 power. For turning large screws into metal work, screw drivers with 
 cross handles in the form of a letter X are used. 
 
 Screw Driver Bit. — A screw driver, the end of whose shank is square 
 tapered to fit within the socket of a brace, similarly to brace bits. Being 
 revolved with the brace its action is quicker than that of an ordinary 
 hand-worked screw driver. 
 
 Screwed Stays. — The bar stays, or tube stays, of boilers are also termed 
 screwed stays. Ordinary riveted stays (q.v.) are usually screwed first 
 of all, but the term is not so commonly applied to them as to those just 
 named. 
 
 Screw Engine. — An engine specially designed to drive the screw of a 
 steamer. It is generally of the inverted cylinder (q.v.) type and com- 
 pound (q.v.). Engines having two cylinders only, one highand one low 
 
3o5 DICTIONARY OF TERMS USED IN 
 
 pressure, were, "until recently, mostly used, and are still for small vessels. 
 But for large ocean-going steamers these are being replaced by triple 
 expansion engines of three cylinders, one high and two low pressure, 
 and to a limited extent by quadruple expansion engines (c[.v.). 
 
 Screw Feed. — The feed (q.v.) of a machine which is effected tlirough the 
 medium of a screw and nut. Screw feeds are applied to many 
 drUUng machines, to screw cutting lathes, and other machines. 
 
 Screw Gearing. — Gearing in which the teeth are not parallel with the 
 axes of the shafts. The axes may be placed at any angle, and the teeth 
 may correspond with a single, or with a many threaded screw. Worm 
 gearing and angle wheels come under this heading. 
 
 Screw Head. — The upper portion of a wood, or metal, or other screw, 
 being the part by which it is driven into its place. 
 
 Screwing. — The cutting of screw threads by means of taps and dies. Most 
 commonly used by workmen to denote the cutting of bolt screws in the 
 screwing machine, or the cutting of gas threads on piping rather than 
 of work done in the lathe, which is more often denominated screw cutting. 
 
 Screwing Flange. — A cast-iron flange, screwed internally for attachment 
 to the similarly screwed ends of wrought-iron piping, the piping being 
 then united by bolts passing through opposing flanges. Screwed flanges 
 are used in preference to common tubular unions, because of the readi- 
 ness with which they can be disconnected, and also for connecting, pipes 
 to other flanges, as on cast-ironwork, engine cylinders, &c., into which 
 it would be inconvenient or impossible to screw the wrought-iron tubing 
 directly. Better steam tight joints can also be made with flanges than 
 with screwed ends alone. 
 
 Screwing Machine. — ^A machine used for screwing bolts in quantity, the 
 dies revolving. 
 
 Screwing Tackle. — A term commonly appUed to the appliances used for 
 cutting screws apart from the aid of a lathe. Stocks, dies, taps, and tap 
 wrenches are included under this heading. 
 
 Screw Jack. — A lifting jack which is actuated by a square threaded screw 
 worked either by a lever bar inserted in a hole at the upper end or head 
 of the screw, or by a lever permanently attached to the head and pro- 
 vided with a ratchet and click similarly to a ratchet brace (q.v.), or by 
 a worm and worm wheel, the worm wheel embracing the screw and 
 becoming its nut. The nut not being free to move endways, the screw 
 must of necessity traverse. The mechanical gain is obtained by 
 multiplying the power exerted at the end of the lever into the product 
 of its length with the pitch of the screw. In the larger jacks the means 
 of longitudinal traverse is also provided by a horizontal screw working 
 in a base. See Bottle Jack, Traversing Screw Jack, Hydraulic Jack. 
 
 Screw Key.— A spanner (q.v.) for turning screw heads. Usually applied 
 to spanners which belong to machines and workshop appliances. 
 
 Screw Mandrel. — See Traversing Mandrel. 
 
 Screw Nail. — A common wood screw (q.v.) as distinguished from an 
 ordinary nail driven in by percussion, the term being akin to the term 
 screw bolt (q.v.). 
 
 Screw Nut. — See Nut. 
 
 Screw Pile. — A foimdation pile which is not driven into the ground, but 
 turned in by means of a tapered screw, of one or of several revolutions 
 at its lower end. It is used in ground too hard or too uncertain for the 
 reception of driven piles. 
 
 Screw Plate. — A steel die plate used for the cutting of small screws of 
 
MECHANICAL ENGINEERING. 307 
 
 about \ in. and under, in diameter. A number of distinct holes are 
 sere-wed in a single plate, and the plates are also made in various sizes. 
 The finest of the holes in the smallest plates used for model work would 
 cut a thread on a very small needle. Screw plates are diminished in 
 thickness as the holes decrease in size. Taps are supplied correspond- 
 ing in size with the holes in plates. 
 
 Screw Press. — See Fly Press. 
 
 Screw Propeller. — See Propeller. 
 
 Screw Bate. — The rate of a screw signifies the number of threads per inch 
 which it contains. 
 
 Screw Shaft. — The shaft which drives a ship's screw, and to which it is 
 directly attached. Screw shafts are usually made in lengths and 
 united with solid couplings. The thrust of the screw and shaft is 
 taken by thrust collars and thrust blocks (q.v.). 
 
 Screw Slotting. — The slotting of the grooves in the heads of cheese- 
 headed and button-headed screws. It is effected with a rotary cutter 
 or saw. 
 
 Screw Stock. — See Die Stock. 
 
 Screw Surface. — The surface formed by the development of a helix, or of a 
 screw blade. The latter is termed the screw blade area (q.v.). 
 
 Screw Tap. — See Tap. 
 
 Screw Threads. — Formerly each manufacturer had his special screw rates 
 designed without reference to uniformity with any other. A sense of 
 the advantage of a uniform series of threads has, however, resulted in the 
 universal adoption of certain standard rates. In England the Whit- 
 worth threads are the standard, the Sellers' threads in America, and 
 the decimal threads in France. 
 
 Screw Threaded Gauge. — An assemblage of laminal or thin steel plates, 
 whose edges are notched to fit screws of many different pitches, and by 
 which the pitch of any thread within the range of the gauges can be 
 ascertained. 
 
 Screw Tool. — A tool whose edge is ground to the sectional shape of the 
 interspace between two contiguous threads, Vee shaped, or square, as 
 the case may be, and used for cutting screws in the screw cutting lathe. 
 For cutting screws in the lathe by a hand feed only, a chaser (q.v.) or 
 chasing tool is employed. 
 
 Screw Valve. — See Screw Down Valve. 
 
 Screw Worm Chuck. — See Taper Screw Chuck. 
 
 Screw Wrench. — A spanner, the width of whose jaws is rendered adjust- 
 able by a screw to an extent within the limits of the traverse of the 
 screw. The strain put upon a spanner is so great that this traverse is 
 necessarily very short, and hence a screw wrench wUl enclose a few bolt 
 sizes only. It is convenient for use in outdoor work, saving the weight 
 of a number of separate spanners. 
 
 Scribe. — A steel tool used for marking lines on work in wood or metal. 
 The timber scribe is pointed at one end and knife-shaped at the other, 
 the former for scratching, the latter for cutting. The fitter's scribe is 
 pointed at both ends, but while one end is straight the other is usually 
 curved for marking underneath work. 
 
 Scribing. — Before proceeding to cut a piece of wood or metal to outline 
 or shape, whether by hand or machine, the outline is marked out on the 
 rough material as an exact guide in the subsequent operations. The 
 process is variously termed scribing, lining, or setting out, the former 
 -word taking its name from the scribe, which is in constant request. 
 
3oS DICTIONARY OF TERMS USED IN 
 
 Scribing Block. — A block of metal carrying a scribe pivoted on, and 
 pinched by a screw, for adjustment to different heights. It is used 
 for lining off centre lines on work when laid on the surface plate. 
 Hence called a surfacing gauge. 
 
 Scrieve. — To scribe. See Scribing. 
 
 Scroll Chuck. — ^A universal chuck (q.v.) 
 
 Scroll Irons. — Small brackets attached to the underside of railway 
 wagons, to which the ends of the bearing springs are attached. 
 
 Sculls. — The lining or skin of metal and scale which forms around the 
 interior of the ladles used in casting steel and iron. These are knocked 
 out previous to the reliniug of the ladles with ganister or fire clay. 
 
 Scum Cock. — A cock placed in the side of a marine boiler for the purpose 
 of getting rid of the dirt and scum which are carried to the surface of 
 the water. A pipe leads from the cock through the boiler shell and 
 terminates in a copper dish or trough immersed just below the water 
 line, and into which the scum collects. 
 
 Scum Trough, or Scale Pan, or Sediment Collector. — A shallow trough 
 provided in large marine and stationary boilers, for the collection of 
 the fine sediment which is ballooned to the surface by the ebullition of 
 the bubbles of steam. See Ballooning, and Scum Cock. 
 
 Sea Cock. — An injection cook (q-v.) whioh is placed upon the side of a 
 steamer, leading from the sea to the condenser. It is supplementary to 
 the usual injection cock. 
 
 Seam. — A lap joint made between the wrought-iron, or steel plates of 
 which riveted and welded structures such as steam boilers are built up. 
 
 Seamless Tubes. — Solid drawn tubes (q.v.). 
 
 Seam Set. — A coppersmith's tool, which is used for closing up seams in 
 sheet metal work. 
 
 Searing. — The practice of smoothing the surface of the rougher class of 
 foundry patterns with a flat-faced red hot iron, as a substitute for 
 paint or varnish. The grain is thereby smoothed and prevented from 
 rising up when in contact with the damp sand. 
 
 Sea Sand. — The sea sands of many localities are the debris of sandstone 
 rocks, and are suitable for core making, being free or porous, and so 
 offering facility for the necessary venting. They are rendered adhesive 
 by the addition of clay water. 
 
 Seasoning. — The removal of the sap from fallen timber. This is effected 
 by allowing the moisture to dry out by free exposure to the atmosphere. 
 'Kmber takes from one to three years to season in the ordinary way, 
 but much less when artificial seasoning (q.v.) is resorted to. 
 
 Seat. — A seating (q.v.). 
 
 Seating. — (1) A casting which becomes the base or foundation for por- 
 tions of work. Usually applied to the castings which are attached to 
 boilers to carry the safety, stop, and other valves. Also called a seat. 
 
 Sea Water. — Sea water is of necessity used in marine boilers, and though 
 a slight degree of saltness is not injurious, but rather beneficial, too 
 much salt is detrimental, producing a rapid deposition of scale. Since 
 the water in the boiler increases in saltness by reason of the constant 
 evaporation going on, frequent testing by means of a salinometer is 
 essential, and judicious blowing off of the brine at intervals 
 
 Sec. — The secant of an angle. 
 
 Secants, Line of. — See Sines, Line of. 
 
 Second Cut File. — A file having a degree of coarseness midway between 
 that of a bastard and a smooth out (q.v.) 
 
MECffAMCAL ENGINEERING. 309 
 
 Second Tap. — A tap intermediate in size between a taper and a plug tap. 
 
 Section. — The division of a substance or the cutting of a mass in any 
 direction. The term is used chieily to indicate those particular views 
 in a drawing by which the internal or central parts of a piece of work 
 are delineated. It may therefore be defined as a drawing showing a 
 view of an object on the assumption that the object is cut across at that 
 particular spot. The direction in which the section is taken is indi- 
 cated by the words "longitudinal," "transverse," "oblique," "ver- 
 tical" or "plan,"or by lines dotted on the drawing, as "section on 
 line A B, line CD," &c. 
 
 Sestional Area. — This has reference to the sum total of the area of the 
 quantity of metal in a casting or forging irrespective of its diameter or 
 linear dimensions. The term is chiefly employed in reference to columns 
 whose strength to resist torsion varies widely with their sectional areas, 
 for example, a hollow column "whose sectional area is the same as that 
 in a solid column, will if its inner and outer diameters are as 8 to 1 , be 2 J 
 times stronger than the solid one, notwithstanding that there is the 
 same amount of metal in each. 
 
 Sectional Boiler. — A steam boiler which consists of an aggregation of 
 small independent heating tubes. The advantages of these boilers con- 
 sist in the high pressures to be obtained in them, their immunity from, 
 or at least localisation of explosions, the strength of small tubes, and 
 rapid transmission of heat through them, and lie ease with which local 
 repairs can be effected. On the other hand there is a tendency to the 
 accumulation of deposit in the tubes, and difficulty of clearing them 
 out, and a tendency also to overheating. Also called water tube boiler, 
 unit boiler. 
 
 Sectional Plan. — See Plan Section. 
 
 Section Angle. — The angle between the top and front faces of a double- 
 edged turning tool. 
 
 Section Colours. — The colours used by engineers to indicate sections of 
 various materials. Cast-iron section is grey, wrought-iron section is 
 blue, steel section is purple, gun-metal and brass sections generally are 
 gamboge. Wood is brown (umber). When colours are not used, con- 
 ventional varieties of shading are employed. 
 
 Sector. — (1) A universal scale by which numerous computations can be 
 obtained by measurement simply. It consists of two legs divided out 
 into lines, termed lines of chords, sines, polygons, &c., whose uses are 
 described under their special names. The Hues of division are termed 
 sectorial lines. Sectors are usually six inches long when folded and 
 twelve inches when opened out. (2) The sector of a circle is the part 
 bounded by two radii and the arc which they enclose. 
 
 Sectorial lines. — See Sector. 
 
 Sediment. — The muddy deposit which collects in steam boilers, consist- 
 ing chiefly of carbonate, and sulphate of lime. See Incrustation, &o. 
 
 Sediment Collector. — See Scum Trough. 
 
 Seed Oil.— See Vegetable Oils. 
 
 Segment. — A segment of a circle is the portion bounded by an arc (q.v.) 
 and its chord (q.v.). 
 
 Segmental Back, or Segmental Wheel. — An arc of a toothed wheel, mov- 
 ing about its proper centre, and used for imparting reversible motion to 
 a spindle through the mediiun of a wheel gearing into the rack. 
 
 Segmental Rivet. — A rivet, the vertical section of whose head is that of 
 a segment of a sphere, being hemispherical nearly. 
 
310 DICTIONARY OF TERMS USED IN 
 
 Segmental Wheel. — See Segmental Rack. 
 
 Seizing. — The jamming fast of bearing parts, caused by the expansion due 
 to heat and the absence of sufficient lubrication. When bearings seize, 
 they should be cooled by pouring hot water thereon, to be followed 
 afterwards by applications of colder water. 
 
 Self-acting. — A machine or some section of a machine whose moTements 
 are not executed by a direct intervention on the part of the attendant, 
 but which are derived immediately from the motions of the machine itself. 
 The chief motions in ordinary machines are rendered self-acting through 
 the intervention of screws, cams, gearing, levers, &o. 
 
 Self-acting Balance Crane. — A balance crane in which the balance weight 
 is rendered automatic, with a view of preventing accidents due to the 
 overturning of the crane, through the balance weight being run out to 
 its full distance when not liftingaload. The ends of the tie rods terminate 
 in looped chains near the side frame, and each of these chains is attached, 
 one end to a lug in a derrick barrel, the other to the short end of a bell 
 crank lever. The lower or longer limbs of the bell crank levers are 
 attached to balance weights, and these again by means of links to the 
 actual balance weight itself, which is a round ball roUing on the tail 
 girders of the crane. The action of the mechanism is such that when 
 a load is suspended from the crane the long arm of each belt crank 
 lever with its balance weight is lifted and the actual balance run out, 
 the distance to which it is run being proportional to the load. When 
 the load is dropped the levers drop, and the balance ball runs inwards. 
 
 Self-acting Lathe. — A lathe furnished with a slide rest whose motions are 
 rendered either partially or entirely self-acting. Strictly spealdng a self- 
 acting lathe will have two motions, one by rack and pinion, or by screw, 
 or by each at pleasure, for traversing or longitudinal cutting : the other 
 by back shaft and screw gearing, and geared spindle in the slide rest, for 
 surfacing or cross traverse. But it is also customary to term a lathe 
 self-acting even though the longitudinal traverse only is so rendered by 
 means of a leading screw, whOe the surfacing movement is effected by 
 hand. Almost all engineers' lathes are self-acting in both motions. 
 
 Self-acting Lubricator. — A lubricator which is self -feeding, the oil pass- 
 ing over from a reservoir ioto the actual oil hole, being drawn up in 
 many forms through a twist of tow or gasket by capillary attraction. 
 The difference between the steam and the exhaust pressure in steam 
 cylinders is also made to actuate the movements of valves in some forms 
 of lubricators, while in others the difference in the specific gravities of 
 oil and condensed steam is utilised to cause the oil to pass through an 
 overflow pipe into a steam cylinder. The term embraces any lubricator 
 which is only filled at intervals, and in which the feeding goes on until 
 the supply is exhausted. See Displacement Lubricator, Impermeator, 
 Steam Lubricator, Syphon Lubricator. 
 
 Self-centring. — A term which signifies the automatic setting or marking 
 of cylindrical work truly. It is effected in the lathe or similar machine 
 by means of a chuck whose jaws arc worked simultaneously to or from 
 the centre. See Centring Chuck. The bell centre punch (q.v.) is also 
 an example of self-centring, so also is the use of a square centre 
 (q.v.). 
 
 Self-contained Machines. — Machines whose parts are not attached to dis- 
 tinct fixings, but are all so combined that one foundation or attachment 
 is sufficient. Thus a radial drill is self-contained when the table and 
 pillar are bolted together, instead of, as is often the case, the radial arm 
 
MECHANICAL ENGINEERING. 311 
 
 being attacHed to a -wall or pillar, while the table is bolted to the stone 
 foundation. Independent machines (q.v.) may be considered as self- 
 contained. 
 
 Self-delivery. — The delivery of the hollow portions of patterns in the 
 sand, dne to their own taper only, as distinguished from coring out. In 
 self-delivery the core is therefore of the same material as the re- 
 mainder of the mould. 
 
 Self-fluxing Ores. — Some red haematites contain sufficient calcareous 
 matter as to require no additional flux, hence the term self-fluxing. 
 They occur in Sweden chiefly. 
 
 Sellers' Screw Threads. — The American standard engineers' screw threads 
 in which the sides slope at an angle of 60°. The tops and bottoms of 
 the threads are cut off square to a depth equal to one-eighth of the 
 pitch. 
 
 Semaphore. — ^A signal attached to a tall pillar ; as used on railways the 
 signals consist of arms and lamps worlced by levers and chains. 
 
 Semi-Beam. — A cantilever (q.v.). 
 
 Semi-Bituminous Coal See Bituminous Coal. 
 
 Semi-Chord. — Half the length of the chord of an arc. 
 
 Semi-Circle. — A half circle, bounded by the lines of circumference and of 
 diameter. 
 
 Semi-Fixed Portable Engine. — A boiler and engine of the common port- 
 able type, which, instead ef being mounted upon wheels, is made a 
 fixture, the fire box resting directly upon the ground and a cast-iron 
 standard being placed underneath the smoke box. 
 
 Semi-fiirder. — A semi-beam or cantilever (q.v.). 
 
 Semi-Portable Engine. — An engine which is in the main of the portable 
 type (see Portable Engine), but which differs from it in this respect, 
 that instead of being mounted upon wheels it is attached to an iron 
 base or frame, and this to a solid foundation of stone or timber. It is 
 used generally for the same kinds of work as are portable and light 
 horizontal engines, as sawing, pumping, winding, driving machines, 
 and for work located in one place, and in work of a temporary cha- 
 racter. 
 
 Semi-Steel. — A steely iron. See Puddled Steel. 
 
 Sensible Heat. — Heat which is measured by the thermometer, as opposed 
 to latent heat (q.v.). 
 
 Service Pipe. — The small piping which conveys liquid from a main pipe 
 to its ultimate destination. 
 
 Serving. — The covering of a rope with spun yam to protect it from 
 chafmg against the pulley or drum over which it works. 
 
 Serving Board. — The board employed in serving or winding the spun 
 yam around a rope. Its shape is somewhat like that of the letter "X. 
 The yam is wound around the rope in a transverse direction, and is 
 tightened as it is wound by being reeved round the neck of the board, 
 while the handle affords the necessary leverage for pulling the yam taut. 
 
 Serving Mallet. — A cyHndrioal block of iron used in serving (qv.) a rope. 
 
 Set, or Sett. — (1) A narrow square nosed or round nosed chisel-like tool 
 used by fitters and boiler makers for chipping grooves in metal. (2) 
 Broad chisel -like tools used for cutting off hot or cold bars on the anvil, 
 the hot set being ground thinner than the cold set. They are attached 
 both to handles as ordinaiy hammers or to hazel rods. (3) A hook 
 wrench (q.v.). (4) The deflection which a bar or structure undergoes 
 when subjected to strain or stress is its set. See Permanent Set. 
 
312 DICTIONARY OF TERMS USED IN 
 
 Set after Fracture. — See Ultimate Set. 
 
 Set Hammer. — A form of smith's hammer whose face is rectangular in 
 plan and its edges square, and which is laid upon the work and struck 
 with a heavier hammer or sledge in order to form a set-off (q.v.). Also 
 called a set, simply. 
 
 Set Off. — A term used in a general way to signify the production of an 
 abrupt shoulder in a piece of work, or the standing out of one portion 
 of a structure at an abrupt angle from another portion. 
 
 Set Screw. — A plain screw ha-ving a square or other shaped head, made 
 use of for tightening purposes. It holds by friction alone, and is not 
 suitable for machine parts subject to excessive vibrations. 
 
 Set Square. — A square whose shape is that of a right-angled triangle, 
 the angles of the hypothenuae being usually either 45°, or 30°, and 
 60°. Used for laying down lines, and for checking work where the 
 ordinary try square being of different thicknesses in blade and stock 
 would not be suitable. 
 
 Sett.— See Set. 
 
 Setting. — (1) The fixing of engine slide valves in their proper positions 
 relatively to the ports, valve rods, eccentrics, and cranks, is called 
 setting of valves (q.v.). (2) The production of a set off (q.v.)iu a piece 
 of work. (3) The placing of portions of mechanism in their exact 
 positions for the fitting of keys, the drilling of holes, and the mark- 
 ing of centres. See also Saw Setting. 
 
 Setting Block. — A round-edged block of iron upon which a saw is laid 
 longitudinally during the operation of setting. The amount of set for 
 different saws is regulated by the amount of angle given to the saws 
 relatively to the curve of the block. 
 
 Setting Down. — The flatting or hammering down of portions of smith's 
 work with a set hammer or flatter. 
 
 Setting Down Screws. — The top screws in the standards or housings of 
 ben(£ng rolls, by which the position of the top roU is adjusted. 
 
 Setting Hammer. — A light cross pane hammer (see Pane) used for saw 
 setting, purposely made narrow to permit of the striking of a saw tooth 
 without risk of hitting its next neighbour. The teeth are struck while 
 the saw is laid on a setting block (q.v.). 
 
 Setting of Boilers. — The placing of steam boilers permanently in place. 
 Cornish and Lancashire boilers are set on brickwork, the flues being 
 built in the brickwork itself. Marine boilers are set on saddles. 
 Locomotive boilers are not set, but slung. 
 
 Setting of Valves. — The setting of engine slide valves is an operation of 
 great nicety, and is performed in various ways, dependent upon the 
 nature of the link motion. The aim in every case is to obtain a precise 
 and constant amount of lead for the valve, so that the greatest angular 
 advance of the eccentric shall coincide at each revolution with the lead. 
 Also it is the aim, though not always practicable, to get the lead equal 
 at both ends of the stroke, except in the case of vertical engines of large 
 size, where the bottom lead is slightly increased over that of the top to 
 allow of wearing down. Usually in setting valves the practice is to 
 first place the crank on dead centres, then turn the eccentric into the 
 position of greatest angular advance corresponding with the position of 
 the crank, set the valve to the position open to lead, also corresponding 
 with the position of the eccentric and crank, and then having already 
 made the rod joints, to trammel off the precise length of the connect- 
 ing rod. Then turning the crank, eccentric, and valve into the exactly 
 
MECHANICAL ENGINEERING. 313 
 
 opposite positions, to repeat the operation, and shut or weld up the 
 eocentric rods to their ends. Lastly, hefore finishing ofE the rods to 
 repeat the previous operations and make any necessary adjustments. 
 But when the rods are already welded up before setting, it is necessary 
 to omit the cutting of the key-way for the eccentric on the crank shaft 
 until the setting is finished, and the length of the connecting rods may 
 have to be adjusted by planing ofE some portion of the ends of the 
 rods, or conversely by lining them up. 
 
 Setting Out. — See Lining Out. 
 
 Setting Over. — The placing of the mandrel centre of a lathe poppet out 
 of line with the axial centre of the headstoek in order to provide for the 
 turning of taper work between centres. Li many lathes the upper 
 portion of the poppet is made movable on a lower base or foundation 
 plate for this purpose . 
 
 Set 'Work. — ^Work which is repeated many times over or perpetually in 
 the workshop. Work which is a speciahty, and which therefore is 
 done more cheaply and better by firms which engage in it mostly or 
 entirely, than by those who do work of a general character. It is 
 carried out by minute subdivision of labour, and piece work, and 
 though cheap, tends to produce an inferior and one-sided class of work- 
 men. 
 
 Shackle. — A loop to which the end of a chain is attached. The open ends 
 of the loop are generally formed into eyes through which a sustaining 
 bolt or pin is passed. 
 
 Shackle Bolt. — ^A bolt having a shackle formed at the end opposite to the 
 nut. 
 
 Shading. — The colouring or lining of drawings to give to parts the appear- 
 ance due to relief, or to circular, sectional, and other forms. Working 
 drawings are shaded but slightly, elaborate and complete shading being 
 reserved for finished and for general drawings. Conventional modes 
 of shading are adopted for various metals. 
 
 Shaft. — A spindle which revolves in bearings and carries pulleys or gear 
 wheels for the transmission of power. The principal strain to which 
 shafts are subject is that of torsion (q. v.), and the force of torsion is pro- 
 portional to the cubes of their diameters. 
 
 Shaft Boss. — The larger boss of an engine crank which carries the crank 
 shaft (q.v.). 
 
 Shaft Coupling. — See Coupling. 
 
 Shafting. — A line or succession of shafts united with couplings and used 
 for the carrying of pulleys for driving machinery. 
 
 Shafting Oil. — Oil used especially for the lubrication of shafting. 
 
 Shaft Straightener. — A machine used for straightening shafts. It acta 
 by the umform and adjustable pressiire of three rollers divided out 
 equally in a circle, and between which the shaft is passed on to two 
 larger rollers. 
 
 Shaft Tunnel. — See Tunnel. 
 
 Shake. — A line of fracture in timber, the splitting being caused by the 
 shrinking up of the iibres due to the desiccation or drying up of 
 the moisture. 
 
 Shank. — A hand foundry ladle is sustained by a shank, or rod bent round 
 as a hoop to envelop the body of the ladle, and prolonged at one end and 
 there bent downwards to fall over a cross bar, and forged at the 
 opposite end into a cross handle. Three or four men carry such a ladle, 
 one at each end of the cross bar and one at the cross handle, or one at 
 
J 14 DICTIONARY OF TERMS USED IN 
 
 eaoli end of the latter. By the leverage of the cross handle or omtoh 
 the metal is tipped into the mould. Shank ladles hold from 1^ to 3 
 or 6 cwt. of metal. (2) The stem or body of a cutting tool, as the 
 shank of a drill, or the upper portion which enters into the chuck 
 or the socket through -which it receives its motion. It is tapered or 
 parallel, round or square in section, according' to the shape of the socket 
 or chuck. 
 
 Shank Ladle. — A foundry ladle (see Ladle) suspended in the central loop 
 of a horizontal handle or shank (q.v.). 
 
 Shaping. — The shaping of metal in a shaping machine, though analogous 
 to that of planing, differs therefrom both in the extent of the surface 
 operated upon, and in the outlines imparted thereto. The shaping 
 machine only operates on small areas, seldom over 12 in. in length, 
 commonly much less ; also convex and concave cut surfaces can be 
 shaped as readily as plain ones, the former by threading the "work on an 
 arbor under the tool, and imparting a slow rotatory movement to the 
 arbor, the latter by using a tool holder having a -worm and quadrant 
 movement, by which the tool is caused to rotate slowly through an arc of 
 a circle. 
 
 Shaping Machine. — A machine used for shaping metallic masses which 
 are not sufficiently bulky to go into the planing machine. The tool is 
 carried on a rigid arm which moves in a horizontal direction, the length 
 of whose stroke is capable of regulation by means of a connecting rod 
 movable in a slot in the arm. Quick return (q.v.) motion is given in 
 the larger but not in the smaller machines. An angle plate is attached 
 to the front of the machine and is movable vertically or transversely. 
 Most machines have a worm and wheel segment arrangement on the 
 tool box for circular shaping. 
 
 Sharpening. — The imparting of a fine edge to a cutting tool by abrasion 
 or fretting on an oil stone. 
 
 Shear. — (l)To cutwith shears (q.v.). (2) A bar is said to be in shearwhen 
 it is subject to shearing stress (q.v.). 
 
 Shearing. — The act of cutting with shears. 
 
 Shearing Machine. — A machine in which shears or shearing knives are 
 worked by power. Commonly the processes of punching and shearing 
 are combined in one machine, the punching below, the shearing above, 
 or in the larger machines at opposite ends. Shearing machines are 
 employed in iron and steel manufactories and in boiler sliops chiefly, 
 for cutting off the rough edges of plates, or for cutting to precise 
 dimensions. Bars and angle irons are also cut, the lengtti and shape 
 of the knives varying with the nature of the work. The knives are 
 placed at an angle with each other, the out taking place from one end 
 towards the other like that of scissors. 
 
 Shearing Strength. — The strength necessary to shear iron is about equal 
 to its tensile strength. 
 
 Shearing Stress. — The stress to which a body is subject when force is 
 applied to it in a direction parallel with its section. Its mean intensity 
 is equal to the shearing force divided by the area of the section. 
 
 Shearing Tools. — Tools which remove material by detruding action (q.v.), 
 or violent separation. They include shears and punches. 
 
 Shear Legs, variously termed Sheer Poles, Shears, or Sheers. — A rude 
 but strong form of crane, having three legs or pillars set leaning at an 
 angle towards each other for supporting the lifting tackle. Tlae gear 
 wheels may be attached to one of the legs, or be fixed independently, 
 
MECHANICAL ENGINE ERIMG. 315 
 
 and hand or steam power may be employed. Timter or iron are used 
 in the construction of the legs. 
 
 Shears, or Sheers. — (1) Enives used for severing sheet metal, tars, angles, 
 &c., by shearing, or cutting parallel with the section. They act 
 by the opposition and pressure of the cutting edges, the faces being 
 ground generally to an angle of from 80° to 90°. Shears are worked 
 by hand power for the thinner sheets, but for the thicker plates shearing 
 machines are used. (2) The term is often used to designate the bearers 
 of a lathe bed. (3) Shear legs (q.v.). 
 
 Shear Steel. — Forged steel composed of bars of blistered steel laid side by 
 side to form a bundle or fagot, and drawn down and welded under a 
 hammer. 
 
 Sheave. — (1) A term applied to the eccentric body or to that part which is 
 keyed directly on the shaft, to distinguish it from the eccentric straps 
 (q.v.). (2) A sheave wheel. 
 
 Sheave Wheel, or Sheave, simply. — A wheel whose groove is made to re- 
 ceive a chain or rope. The section of the rim of the sheave may be a 
 plain semi-circle, or veed, or a single groove, or a double groove, 
 according to the work which the wheel has to do. 
 
 Sheer Poles. — See Shear Legs. 
 
 Sheers. — See Shears. 
 
 Sheet Brass. — Brass rolled into sheets and used for a variety of purposes, 
 chiefly for ornament, covering steam domes, gauges, handrailing, 
 &c. It is either hard or soft, similarly to wire. 
 
 Sheet Copper. — Used by engineers for the making of steam pipes chiefly. 
 
 Sheet Iron. — Strictly speaking, the thinnest iron which is roUed, as dis- 
 tinguished from plates. See Plate, Sheets. 
 
 Sheet Lead. — Used for making the joints of steam and water pipes. 
 Used also for lining up small patterns. 
 
 Sheet Tin. — Iron sheet, coated with tin. It is used by engineers in the 
 making of the lightest kinds of templets. 
 
 Sheet Hetal Gauge. — A gauge used for measuring the thicknesses of sheet 
 metals. It may be a micrometer caliper (q.v.) or a wire gauge (q.v.), 
 the former measuring in terms of the inch, the second by manufacturers' 
 numbers. 
 
 Sheet Mills, — EoUing nulls of light construction, used for the rolling of 
 sheets (q.v). 
 
 Sheet Eubber. — Vulcanised india-rubber, insertion or plain, is made into 
 sheets of large size for the convenience of being cut into washers, 
 collars, &c., of any required dimensions. It, may be had in sheets of 
 from 4 to 30 yards long, by 48 in. in width, and from the ^oth of an 
 inch upwards in thickness. Its usual thickness is from -J to -f^ for 
 ordinary work. 
 
 Sheets. — ^All plates of malleable iron below No. 4 B.W.G. or -238 in., are 
 termed sheets, as distinguished from plates (q.v.). 
 
 Sheffield Files. — Sheffield is the great seat of the file industry, the 
 majority of engineers' files being made there. For shapes and charac- 
 teristics, see specific names. 
 
 Shell. — The shell of a boiler is the outer casing of all, enclosing fire box, 
 water space, cross tubes, &:c. The shell of a cock is the outer envelope 
 or casing through which the liqidd passes on the turning of the plug 
 
 (q-v.) 
 
 Shellac. — Shellac is produced by the agency of members of the family Coo- 
 cidse, of the order ilhynchota or beaked insects. The true lac insect 
 
3i6 DICTIONARY OP TERMS USED IN 
 
 {Cocms lacca) is a native of Siam, Assam, Bengal, Burmah, and Malatar. 
 The lac is produced by the agency of the females chiefly, ■who, onco 
 settled upon a twig of a tree — the trees frequented being species of 
 Butea, Ficus, and Croton — never leave it, but suck up the resinous 
 juices, feeding on and enveloping themselves in them until they die, 
 leaving their eggs enveloped in the secretion thus obtained, coloured 
 ■with dye matter secreted from their o^wn bodies. G-enerations of in- 
 sects hatched from successive colonies of eggs live on the same branch 
 until it becomes coated to the extent of half inch or more, ■when the 
 t^wigs are collected by the natives and subjected to various processes of 
 boiling, kneading, and squeezing, by ■which the resin is obtained in 
 varying degrees of purity kno^wn as stiok-lac, seed-lac, and sheU-lac, 
 the latter being the most free from colour, and most soluble in spirit, 
 and that which is exclusively used in the mixing of varnish for foundry 
 patterns. 
 
 Shellac Varnish. — This is made by simply dissolving shellac (q. v.) in naph- 
 tha, in methylated spirit, or in spirits of ■wine, the former being the ■worst, 
 the latter the best solution, but the second being that most generally 
 employed. The proportions should consist of about two pounds to the 
 gallon, and ought to be mixed ■without the aid of artificial heat. 
 
 Shell Bit. — A bit used for boring ■wood, ■whose section is a convex and 
 concave curve, roughly though not exactly of a half circular form. See 
 Nose Bit, Gouge Bit. 
 
 Shell Plates. — The plates of which boiler shells are composed. 
 
 Shell Reamer. — See Reamer. 
 
 Shield. — (1) A covering employed to protect the bearings and spindles of 
 emery- grinding machines from the action of the gritty dust. (2J A 
 guard placed over or in front of hand and circular saws and portions 
 of machinery to protect the workmen from accidents. (3) The curved 
 device or outline formed by the union of the body of a two-way cock 
 ■with its branches, is often termed the shield. 
 
 Shifting Link, — A slot link (q.v.) whose concavity lies towards the crank 
 shaft, and which is lifted or lowered relatively to the link block or pin. 
 Originally kno^wu as Stephenson's link motion. 
 
 SMngler. — The workman whose task consists in shingling (q.v.) puddled 
 ball. 
 
 Shingling. — The process of hammering or rolling puddled ball in order to 
 convert it into bar or sheet iron. 
 
 Shingling Hammer. — The hammer, either tilt or steam, by which the 
 puddled ball is converted into a bloom. 
 
 Shingling Mill. — The forge where the puddled hall is converted into 
 malleable iron. 
 
 Shingling Tongs. — The tongs used in moving the puddled ball about 
 under the tUt or steam hammer. 
 
 Shipping. — The putting on of a belt over its puUey. See Belt Shipper. 
 
 Shipping Measurement. — The mode of measurement adopted in the case 
 of machinery which is received as cargo on board ship. The measure- 
 ment is taken over the extreme limits of any piece of machinery. 
 Hence projecting portions should, where practicable, be removed for 
 shipment, and stowed into as small an area as possible. ' 
 
 Ship Plates. — Plates of malleable iron, or mild steel of inferior material, 
 or material imperfectly refined. Their tensile strength is lower than 
 that of other qualities of iron or steel, and the metal of which they are 
 composed is not sufficiently homogeneous or reliable to render them 
 
MECHANICAL ENGINEERING. 317 
 
 suitable for any but the commonest work. The hulls of iron ships are 
 largely built of these, hence the name. 
 
 Ship's Hoist. — An engine and boiler attached to a carriage or truck 
 running on wheels, used for the general and miscellaneous work where 
 power is required on board ship. 
 
 Ship's Pump. — A suction pump, varying in form, employed on ship 
 board for general use, pumping bilge water, &c. 
 
 Shock. — The jerk or reflux action produced in pumps and long pipes, being 
 due to the reversal of the water pressure. Shock is lessened by the use 
 of an air vessel (q.v.). 
 
 Shoe. — A cap or socket which receives the end of a piece of timber, and 
 which sustains the end pull of a truss rod (q.v.) or takes the thrust of 
 the legs of shears, or of roof principals, or carries a pivot or bearing as 
 in the pillars of wooden cranes, or acts in a general way as a protection 
 to timber ends, as in pile shoes. Shoes are commonly made of cast iron, 
 but often wrought iron is used in their construction. The base plates 
 which support the housings of rolling mills are also called shoes. 
 
 S Hooks. — Iron hooks whose shape is roughly that of a letter S. They 
 are suspended from the bars of moulding boxes in most cases, to aid 
 in bindiiig together and supporting the body of sand which is enclosed 
 by the sides of the boxes. The adhesion of the sand is assisted by 
 dipping the hooks into clay water. 
 
 Shooting. — The planing of the edges and ends of timber straight, with or 
 without the aid of a shooting board (q.v.). 
 
 Shooting Board. — A board used for planing or shooting the edges of 
 timber square and straight. It consists of two pieces of wood screwed 
 one on top of the other, the upper one being narrower than the lower 
 by so much as will allow a sufficient breadth of bearing for the side 
 of the trying plane on the margin of the lower one. The stuff to 
 be planed is laid upon the upper board, and the side of the plane being 
 laid upon the uncovered margin of the lower one, with the cutting iron 
 towards the edge of the stuff, a shaving is removed as the workman 
 pushes the plane forwards. The advantage of the use of a board over 
 that of the vice is that in the former the edges planed, assuming that 
 both board and plane are true, are not only straight, but square also 
 with the faces of the stufE. 
 
 Shop Tools. — Numerous tools and appliances which are not provided by 
 the workmen in departments, but by the firm, for the common use of all. 
 The term does not embrace machinery so much as minor articles, as 
 standard rules, straight edges, surface plates, trestles, dies and die 
 blocks, water cans, sieves, shovels, and scores of kindred articles used by 
 all, but owned only by the firm. 
 
 Shop Traveller. — An overhead travelling crane employed in the workshop 
 under cover, and used for hfting about heavy masses to the machines, 
 various machined and finished parts for the erectors, ladles of metal or 
 castings in the foundry, plates, girders, bars in the boiler shop, forgings 
 in the smithy, &c. Most shops are fiu-nished with travellers in pre- 
 ference to cranes. See Overhead Traveller. 
 
 Short Columns. — ^A term appKed to columns whose length exceeds their 
 diameter by from three to five times that amount, and which yield 
 to rupture by simple crushing only. 
 
 Short Heat. — The making hot of a short length only of a bar of iron in a 
 smith's fire in order that the heated portion alone shall be operated 
 upon, without incurring the risk of distorting the adjacent portions. 
 
3(8 DICTIONARY OF TERMS USED IN 
 
 The heat is localised by covering all but the portion to be heated with 
 damp slack or small coal, or ia some iostanoes by enclosing in a matrix 
 of damp clay. 
 
 Short Link Chain. — See Close Link Chain. 
 
 Shoulder. — That portion of a shaft, or of a stepped, or of a flanged 
 structure where an immediate increase of diameter occurs. 
 
 Shovel. — Broad light shovels are used in foundries for filling the moulding 
 boxes with sand. 
 
 Shrinkage. — See Contraction. 
 
 Shrinking Head. — See Feeder. 
 
 Shrinkage Hole. — A depression or slightly hollowed space left in the face 
 or in the body of a casting, due to imperfect feeding. See Feeder. 
 Shrinkage holes are prevented by making feeders large enough to hold 
 a supply of hot metal whose mass is sufficient to prevent solidification 
 taking place in the feed metal before the casting itself is set. 
 
 Shrinking On. — The clasping of wheel tires around their centres, being 
 first expanded by heat, and then allowed to tighten on the centres by 
 virtue of their own shrinkage in cooling down. The amount allowed 
 for shrinkage on a wheel of about 2 ft. in diameter is barely J of an inch. 
 
 Shroud. — (1) Aflangecastagainstthe ends of wheel teeth in order to increase 
 their strength or to promote smoothness of motion. If cast up to the 
 pitch line the wheels roll together on their pitch circles, and the term half 
 shrouding is applied to it. If cast to the poiots of the teeth the pur- 
 pose is to afford the maximum of strength, and this is termed fiiU or 
 whole shrouding. "Whole shrouding is believed to increase the strength 
 of wheel teeth by from 40 to 60 per cent. (2) The circular flanges 
 around the edges of a water wheel, between which the buckets extend. 
 
 Shrouded Wheel. — A gear wheel provided with shrouds. A water wheel 
 is also a shrouded wheel. See Shroud. 
 
 Shrouding. — The casting of shrouds on the ends of wheel teeth or of the 
 buckets of water wheels. See Shroud. 
 
 Shroud Laid Eope, — An ordinary rope formed of three strands twisted 
 together. These are stronger than cable laid ropes (q..v.) and strongest 
 of all when untarred or white. 
 
 Shutting. — The shop term for the welding together of joints in wrought 
 iron or steel. 
 
 Shutting Link. — ^The union of the free ends of chains, either to each 
 other or toother portions of work, as rings, hooks, &c., is effected by 
 means of a shutting link, that is a Unk sinular to the ordinary link but 
 about J in. larger in the diameter of the iron from which it is made, and 
 frequently also a little longer ; this increase in size is made to compen- 
 sate for possible weakness due to any imperfection in the weld. 
 
 Side Chisel. — The chisel specially employed for wood turning. The 
 cutting edge is ground obliquely in relation to the edges of the shank, and 
 it is used purely as a cutting tool, seldom as a scraper, the cutting edge 
 being placed approximately at a tangent to the work The acute angled 
 comer of the chisel is also used for parting or cutting off. The side 
 chisel turns a remarkably clean and approximately plain surface, but is 
 not suited for quick curves or for mouldings or ornamental work, or 
 for work of large diameter. 
 
 Side Discharge Valve. — See Discharge Valve. 
 
 Side Discharge Wheel. — SeelTurbine. 
 
 Side Elevation, er Side View. — A view on a drawing which shows thq 
 side of a structure. 
 
MECHANICAL ENGINEERING. 319 
 
 Side Frames. — The main frames, standards, or supports of cranes, engines, 
 pmnps, &o., whicli carry tlie bearings for the shafts. They are made 
 both in cast and in -wrought iron. Small side frames are often called 
 cheeks. 
 
 Side Hooks. — The coupling hooks of railway wagons, placed at the side of 
 the draw hook. 
 
 Side Lever Engine. — A marine engine in which motion is communicated 
 from the side rods of the piston cross head to the connecting rods, by 
 two levers centred nearly on a level with the base of the cylinder. 
 Side lever engines are nearly obsolete, though in the early days of 
 steam navigation they were much in request, and they have the advan- 
 tage of maintaining the moving parts nearly in equilibrium, so that 
 there is little difficulty in starting them. The connecting rod being 
 long, the oblique thrust on the crank is reduced to a miniimun. But 
 they lack compactness of form and are heavy. 
 
 Side Sake. — The rake (q.v.) of a cutting tool which cuts sideways, to 
 right or left as the ease may be. Such rake may be side top rake, or 
 side bottom rake. See Top Kake, and Bottom Rake. 
 
 Side Bods. — (1) The rods connecting the cross head with the side levers 
 of a side lever engine (q.v.). (2) Hods fulfilling the same purpose in 
 one of the old forms of table engine. 
 
 Side Tank. — See Tank Engine. 
 
 Side Tool. — A tool used by wood turners for finishing the inner and outer 
 portions of work. Called a side tool because its cutting edge is ground 
 to an angle with the axis of the tool in order to reach the sides of the 
 work, or those which stand approximately at right angles with 
 the tool rest. 
 
 Side Top Bake.— See Top Eake. 
 
 Side View. — See Side Elevation. 
 
 Side "Winch. — A light hoisting winch furnished with a flange for attach- 
 ment to any convenient support, as the side of a wall or beam. 
 
 Siemens-Martin Process. — The process of manufacture of mild steel by 
 the fusing together of pig iron and scrap steel in a reverberatory fur- 
 nace, in which the pig is decarburised, the necessary amount of carbon 
 being added afterwards by spiegeleisen or by f erro-manganese. The cast 
 iron is rendered fluid, before the scrap steel rendered white hot in 
 another part of the furnace, is allowed to mingle with it. It is one of 
 the open hearth processes, and is also termed the pig and scrap process. 
 
 Siemens Process. — The method of manufacture of steel by the fusing 
 together of pig iron and iron ore and scrap steel, the spiegeleisen or 
 ferro-manganese, or a mixture of both, being added afterwards. Hse- 
 matite pig iron and steel scrap, in the proportion of about thirty of the 
 former to seventy of the latter, are first melted, and haematite ore 
 added after fusion. Spiegel, or ferro-manganese, or both, are added 
 as the metal is being tapped into the ladle, to afitord the necessary 
 recarbnrisation. It is not necessary that scrap steel should be added 
 except as a convenient mode of using up odd ends. It is one of the 
 open hearth processes, and is also called the pig and ore process. 
 
 Sieve. — Sieves of different meshes are used in foundry work for the pur- 
 pose of sifting the sands required for moulding. They are termed J, 
 i\, &c., according to the sizes of mesh. Asieve proper ranges from \ in. 
 downwards, or from 8 to 18 mesh. Brass moulders' sieves range from 
 8 to 36 mesh. See Kiddle. 
 
 Sight Feed Luhricator. — A lubricator (q.v.) in which the flowing or non- 
 
320 DICTIONARY OF TERMS USED IN 
 
 flo-mng of the oil is always apparent at sigtt, being enclosed in, or 
 having to pass through a glass vessel, 
 
 Sight Holes. — Holes in the sides of a reverheratory, or blast furnace, or of 
 a cupola, or of a hot blast stove, through which the attendants note 
 the progress of melting operations. 
 
 Signs. — The arithmetical and algebraical symbols used in mathematical 
 calculations, and expressive of the operations denoted thereby. 
 
 Silent Feed. — A piece of mechanism by which the logs are fed forward to 
 the saw in deal and timber frames. It ia used in preference to the 
 rachet and click by reason of its freedom from noise. It consists of an 
 adaptation of a nipping lever (q.v.) carried at the end of a radial arm, 
 whose length can be varied to suit different amounts of feed. In 
 Worssam's silent feed, which is that chiefly used, the nipping lever 
 is disguised by being modified into a cam-like piece forming an arc 
 of a circle, whose centre is set eccentrically to its periphery. 
 
 Silica. — The oxide of sOicon, symbol Si Oj. A refractory substance 
 which, in combination with ether elements, is extremely useful to the 
 metallurgist. In combination with alumina and water it forms the 
 fire clays of crucibles. The fire bricks of Bessemer converters contain 
 about 90 per cent, of silica, while ganister is composed largely of it. 
 Natural siliceous stones are used for the hearths of blast furnaces. 
 See Silicon. 
 
 Silica Bricks. — iFire bricks whose main constituent is silica (q.v.). The 
 rock which furnishes their constituent silica is ground, crushed, and 
 mixed with lime and water, then moulded and burnt. Silica bricks 
 expand in burning to the extent of \ inch in 9 inches. They are 
 used for the roofs of furnaces, being set in silica cement. They are 
 unsuitable for those hearths and other furnace linings where they would 
 come in contact with metallic oxides. Por these situations aluminous 
 bricks (q.v.) are employed. 
 
 Silicate Cloth. — An incombustible silicious cloth used as a non-conducting 
 coating for steam boilers. 
 
 Silicate Cotton. — See Slag Wool. 
 
 Silicate Paint.— A protective coating for iron work whose bases are 
 silicious. It resists the action of acids and of salt water better than the 
 ordinary paint. 
 
 Silicious Iron. — Iron which contains silicon in combination in quantity. 
 Sihcon makes iron hard and brittle, and therefore by diminishing its 
 toughness impairs the property which renders it most valuable for the 
 chief purposes for which it is required. But the effect of the sihcon 
 depends largely on the proportion of carbon present, a diminution in 
 the percentage of the latter depriving the sUicious iron of much of its 
 brittleness. The inliueuce of silicon is analogous to that of carbon. 
 It is believed to exist both in the combined and uncombined condition. 
 Hot blast pig contains more sihcon than cold blast. It is produced by 
 the working of poor ores and light burdens. See Blazed Pig. 
 Silicious iron possesses both cold shortness (q.v.) and red shortness (q.v.). 
 
 Silicious Sand. — Sand composed mainly of silica, used instead of lime for 
 setting silica bricks (q.v.), and also for mixing with fire clay for the 
 manufacture of fire-bricks, and for the bottoms of hearths of furnaces. 
 
 Silicious Steel. — This is harder than the ordinary mOd steel, but has red 
 shortness (q.v.), and is therefore unsuitable for plates and bars, though 
 useful for some kinds of castings. 
 
 Silicon. — Symbol Si. Comb, weight 28. Is, next to oxygen, the most 
 
MECHANICAL ENGlNEERiNG. 3«i 
 
 atundant element in nature, ocoruring in combination with oxygen as 
 silica (q.T.) in rooks and sands, and in comlDination with metals as 
 metallic silicates. Pure silicon is extremely hard. Its presence in iron 
 or steel is one of the chief factors affecting their qualities of hardness 
 and brittleness, both during the operation of smelting or refining, and 
 as a permanent constituent. It is present to the extent of 4 per cent, 
 in some soft grey pig irons, but usually below 2 per cent. 
 
 Silky Fibre. — When the bending of wrought iron or steel develops a 
 smooth homogeneous and shining fibre, it is said to be silky. 
 
 Silver Grain. — The medullary rays in timber which radiate from the 
 heart to the bark. The position of the silver grain is of importance as 
 affecting the shrinkage, which fakes place chiefly in a direction trans- 
 versely to the course of its rays. 
 
 Similar Beams. — Beams, which though differing in dimensions, are so 
 proportioned that their relative ratios of strength are the same. 
 
 Simple machines. — The mechanical powers in their elementary forms, as 
 a single lever, or a single wheel and axle, &c. 
 
 Simple Train. — A train of change wheels for screw cutting in which there 
 is only one intermediary or stud wheel used. All coarse pitches, or, say, 
 any of less than eight to the inch, can be cut with a single train. See 
 Compound Train. 
 
 Simply Divided Scale. — A generic term used merely to distinguish 
 ordinary equally divided drawing scales from diagonal scales (q.v.) 
 and vernier scales. 
 
 Sin. — The sine of an angle. 
 
 Sines, Line of. — Sectorial lines (see Sector) by which the lengths of sines 
 and tangents, and secants to a given radius, can be obtained by simple 
 measurement. To obtain siues, open the sector until the transverse 
 distance of 90 and 90 on the sines is equal to the given radius, then the 
 transverse distance measured on the numbers Tvhich correspond with the 
 degrees and minutes will give the sines. The same operation per- 
 formed on the lines of tangents opened to 45 and 45 will also give tan- 
 gents. To obtain the secant, let the radius be taken at and at the 
 beginning of the line of secants, and then take the transverse distance 
 as required. Conversely, to obtain the radius from the length, make 
 the length given a transverse distance in degrees and minutes on its 
 proper scale. Then in the case of a sine the transverse distance of 90 
 and 90 on the sines will be the radius. If a tangent under 45°, 45 
 and 45 on the tangents ; if a tangent over 45°, 45 and 45 on the upper 
 tangents; if a secant, and on the secants. 
 
 Single-acting, — Signiiies generally a prime mover, or machine in which 
 the motive power is appHed in one direction only ; the motion in the 
 opposite direction being effected by momentum or other extraneous 
 form of power. 
 
 Single-acting Engine. — An engine in which the steam acts only against 
 the under side of the piston, the weight of the atmosphere pressing it 
 down again, against the vacuum produced by the condensation of the 
 spent steam. Such engines are now out of date, though long used for 
 pumping in the mines. They were also called atmospheric engines. 
 Engines of single-acting type are used for steam, hammers and also 
 for some forms of three-cylinder engines. 
 
 Single-acting Fiston. — ^A piston which is in contact with the fluid upon 
 which it acts on one side only, usually termed a plunger (q,v.). 
 
 Bingle-acting Pump. — A pump which delivers liquid at each alternate 
 
322 DICTIONARV OP TERMS USED IN 
 
 stroke only, one stroke teing spent in dra-wing or lifting the Kqtdd into 
 
 the pump, the other in dehvering it. 
 Single Belting. — A belt formed of a single thickness only of leather. 
 
 This thickness varies from i to i of an inch. Single belting is 
 
 employed for light and moderatdy light work. For the heaviest 
 
 driving, double belting (q.v.) is used. 
 Single Butt Strip. — A single covering strip uniting a butt-riveted 
 
 joint. Joints made thus are much weaker than those having double 
 
 butt strips (q.v.). 
 Single Cut File. — A float cut (q.v.) file. 
 Single Cutting Drill. — A drill which is ground to cut in one direction 
 
 only, usually right-handed. The majority of drills and drill-like tools, 
 
 and bits for boring wood are single cutting. 
 Single Cylinder Engine. — ^An engine having one steam cylinder only. 
 
 Its action without the assistance of a fly wheel to carry it over dead 
 
 centres (q.v.) would be jerky and uncertain. 
 Single Disc Valve. — A disc-shaped plug valve which is in contact with 
 
 a seating on one face only. It is not so tight as the double disc valve 
 
 (q.v.). 
 Single-ended Boiler. — A marine boiler fired from one end only. 
 Single-ended Machine. — A term applied to those punching and shearing 
 
 machines where one punch or one shear only can be in operation at 
 
 one time. 
 Single Fished Joint. — A fished joint having a single fish plate or covering 
 
 strip only, as distinguished from a double fished joint (q.v.). 
 Single Flue Boiler. — See Cornish Boiler. 
 
 Single Gear. — Gear comprising one pinion and one wheel only in com- 
 bination, for the gaining of power. See Double Gear. 
 Single Geared. — ^When the mandrel of a lathe or the spindle of a machine 
 
 is driven directly by a pviUey keyed upon it, and has therefore no back 
 
 gear, it is said t<) be single geared. 
 Single Grease Cup. — A grease cup having one cock only, leading direct 
 
 into the cylinder or steam chest. 
 Single Purchase. — Gear for lifting or other purposes in which one pinion 
 
 and one wheel only, that is a single gear, are engaged. The 
 
 velocity ratios are then inversely as the radii. 
 Single Rail Crane — A light workshop crane which runs on a single rail 
 
 embedded in the floor. It is maintained in a vertical position by 
 
 means of wheels running on channel iron hung from or attached to 
 
 the roof. 
 Single Beading Scale. — A scale (q.v.) used for drawing purposes in 
 
 which one primanr division only is subdivided. 
 Single Kiveting. — vVhen there is one line only of rivets in lap joints, or 
 
 two in butt joints, this is called single riveting, to distinguish it from 
 
 two lines in the former case, and four in the latter, or double riveting. 
 Singles. — Sheet iron plates used for tinning, whose thickness ranges 
 
 between No. 4 (-238 in.) and No. 20 (-35 in.) B.W.G. 
 Single Shear. — A term applied to the strains upon rivets ; a rivet which 
 
 unites a lap or a butt joint with a single fish plate only, can be shorn 
 
 across in but one section, and is therefore weaker than a rivet in 
 
 double shear (q.v.). 
 Single Stroke. — One stroke of a piston, taken either backwards or for- 
 wards. Used in opposition to double stroke (q.v.) and employed in 
 
 calculations relating to engine power. 
 
MECHANICAL ENGINEERING. 323 
 
 Single-threaded Screw. — ^A screw consisting of one helix only windiag 
 around the body. Ordinary wood screws are always single threaded, 
 as are also attachment screws, and set screws. 
 
 Single Train. — ^A simple train (q.T.) or single gear (c[.T.). 
 
 Single-webhed Girder. — ^A built-up flanged girder whose flanges are 
 connected by a single vertical web only. The term would apply both 
 to a plated and to a lattice girder having a single web. 
 
 Sinking Engines. — Stationary or semi-portable engiues, used for sinking 
 or excavating the shafts of mines. 
 
 Sinldng Fnmp. — A pump used for clearing the water from foundations, 
 docks, mines, &c. The actual pump consists of two suction barrels 
 whose pistons are worked alternately with a bob lever, either by hand or 
 power, the barrels being sunk to the necessary depth, or about twenty 
 feet from the surface of the water to be pumped, by means of telescope 
 pipes. Similar pipes connect the barrels with the suction below. 
 Another form consists of a steam pump self-contained, slung with 
 chains and so sunk into deep wells and mines for pumping to any 
 required depth. 
 
 Siphon Oil Cup. — See Syphon Lubricator. 
 
 Sixteenth Bend. — ^A pipe bend which makes an arc of 22J°, and which 
 therefore connects pipes whose amount of divergence is comparatively 
 slight. 
 
 Skeleton Girder. — An open-webbed girder, or lattice girder (q.v.) 
 
 Skeleton Pattern. — An open frame pattern, that is, one which is not pre- 
 cisely like its casting, but whose outhnes or bounding edges alone are 
 given. In a skeleton pattern the central portions are either strickled 
 or scraped out, or are cored or made up in some other way by the 
 moulder. The reason of their employment is the saving of cost in the 
 pattern making. These are only adopted in framed and plain work. 
 
 Skelp. — A strip of wrought iron which is bent preparatory to its being 
 welded into a pipe. 
 
 Sketch. — See Hand Sketch. 
 
 Sketch Book. — ^A book of semi-transparent prepared tissue paper, used in 
 drawing of&ces, in which is preserved a copy or print of each hand 
 sketch (q.v.) sent out into the shops. The sketches being made in copy- 
 ing ink are printed on the prepared paper similarly to letters, by first 
 damping the paper, placing the sketch between the leaves, preserving 
 the adjacent leaves from contact with oiled sheets, and squeezing the 
 book in the screw press for a moment or two ; in this way a permanent 
 record is kept of all hand sketches however small, and the book is to the 
 sketches, what the tracings are to the shop drawings. 
 
 Sketch Paper. — Foolscap paper having faint lines crossing at right angles, 
 produoiag squares of 1 inch, each divided into eight equal parts. Used 
 for proportional drawing or sketching. 
 
 Skew. — Oblique, not at a right angle. Work is said to be askew when it 
 is out of square, or when it is atwist. 
 
 Skew Back Saw. — A hand saw whose back is curved inwards in order to 
 lighten its weight without diminishing its stiffness. 
 
 Skew Bevels, — Bevel wheels (q.v.) whose axes are not in the same plane 
 and which consequently would not meet if prolonged. See App. 
 
 Skewers, or Wires. — ^Pieces of iron wire from 3 to 6 inches in length, 
 pointed at one end, and turned round into a loop at the other, and em- 
 ployed for the temporary holding of loose pieces (q.v.) in the foundry 
 sand. The turned round eye is for the insertion of the workman's 
 
324 DICTIONARY OP TERMS USMD IN 
 
 finger, in order to efEect the -withdra-wal of the wire from the pattern 
 after it is partially rammed up. Wire nails or wrougM brads are some- 
 times used, but are not so convenient as skewers with eyes. The diameter 
 of the wire from which skewers are made varies from ^ in. to -^ in., J in. 
 being the most generally suitable. 
 
 Skew Eehate Plane. — A rebate plane in which the cutting iron is set 
 obliquely to the sides of the stock, instead of at right angles. It cuts 
 with less chatter, and sweeter than the square-mouthed plane. 
 
 Skid. — See Skidding. 
 
 Skidding. — The slipping of a wheel along its raU. Awheel skids through 
 lack of adhesive power, or through the brake power being insufficient 
 to overcome the momentum of the moving mass. 
 
 Skimmer. — (1) A length of rectangular iron bar which is held across the 
 mouth of a foundry ladle while the metal is being poured, to bay back 
 soorise and foreign matters which float on the top, and which if not 
 skimmed would run into the mould. (2) The call name of the boy whose 
 duty is to hold the skimmer across the ladlo. 
 
 Skimming. — The baying back of the soorise or dross, which floats upon 
 the surface of molten metal, iron, or brass, and which is thereby pre- 
 vented from running into the mould to the detriment of the casting. 
 
 Skimming Chamber, or Skimming Gate. — A chamber whose function is 
 the separation of the dross or sullage from the metal in a foundry mould. 
 It owes its utility to the principle of centrifugal force, and usually con- 
 sists of a globular, or sometimes of a discoid cavity placed in the 
 course of the running metal between the poviring gate and the mould. 
 The metal is run into it on one side and necessarily assumes a whirling 
 motion which throws the scum to the centre and the heavier iron to- 
 wards the circumference, where it passes through a gate or sprue (q.v.) 
 into the mould. All work which has to be planed or turned bright all 
 over is run with a skimming chamber, or, as it is sometimes termed, run 
 with a ball, or run with a disc. 
 
 Skimming Gate. — See Skimming Chamber. 
 
 Skin. — A term used to denote the thin film of hard metal which exists on 
 the surface of a casting or forging, owing to the chilling or hardening 
 of those surfaces against the sand, or in contact with the air, or with 
 cold iron chills. It is so hard that when turning, or planing, the first 
 out taken must be sufficiently deep to pierce below the skin, while if it 
 has to be filed the skin must be first removed by grinding, or by chip- 
 ping, or by using a file nearly worn out, to save iie new one. 
 
 SMn Deep. — See Skin. 
 
 Skin Drying. — The drying of the surface of a green sand mould previous 
 to closing it for the pouring in of the metal. Skin drying effects the 
 removal of a portion of the moisture and diminishes the risk of a blown 
 or a scabbed casting. It is effected with a devil (q.v.) or with an open 
 tray containing burning charcoal or coke. 
 
 Skip. — ^A circular or rectangular shaped open vessel used for tipping 
 rubbish, concrete, ballast, coal, &c., where desired. Skips are either 
 turn-over skips or tipping buckets, that is, they swivel on trunnions, 
 and throw the contents out at the top, or are drop bottom skips, in 
 which the bottom opens downwards on the unfastening of a catch. 
 
 Skulls. — See Sculls. 
 
 Slab. — (1) A flat rectangular block of wrought iron or steel, used for 
 piling or building up heavy forgings, or for roUing plates. Slabs of 
 malleable iron are prepared from the puddling furnaces, or are piled 
 
MECHANICAL ENGINEERING. 325 
 
 from scrap, slabs of mild steel are drawn down under the steam ham- 
 mer from, the ingot. (2) The outer boards cut from logs of adzed 
 timber are called slabs, and are useful for the outsides of core boxes, 
 turn-over boards, and similar rough work. 
 
 Slabbing. — The drawiag down of steel ingots into slabs under the steam 
 hammer. 
 
 Slack. — (1) Small coal used in engine fires. See Small Coal. (2) The 
 dust and burnt out rubbish from a smith's fire. 
 
 Slack Chain. — The loop of chaia which hangs below the pulley blocks in 
 lifting tackle, and which diminishes in amount when a load is being 
 lowered. 
 
 Slack Fit. — A fit is said to be slack when the parts in contact have more 
 freedom of play than is sufficient or desirable for their free and easy 
 movement. The term is relative, because what would be a slack fit in 
 some portions of a machine would be too tight a fit in another. See 
 End Play, Sliding Fit. A slack fit in many cases would more properly 
 mean a bad fit, as in the case of the fitting of shafting into wheel bosses, 
 which must necessarily be tighter than the fitting of the same shafting 
 into its bearings. 
 
 Slacking. — See Slacking Back. 
 
 Slacking Back, — A nut is said to slacken back when it works loose 
 ' from its thread owing to the influence of constant vibration. The nuts 
 of engine and machine parts are thus apt to slacken back, necessitating 
 the introduction of lock nuts (q.v.). 
 
 Slacking Sown, — The damping down of engine fires to prevent or 
 diminish the generation of steam for a season. 
 
 Slacking Off. — ^A shop term denoting the tempering (q.v.) of steel tools, 
 as taps, chisels, and turning tools. 
 
 Slackness. — Play (q.v.). 
 
 Slack Side. — That side of a driving belt which is lowermost. Called also 
 the FoUowing Half. 
 
 Slag. — Slag is a bye product of blast furnaces, cupolas, and melting 
 furnaces generally. As relating to the iron manufacture, it consists of 
 earthy and infusible matters present in the ore, and which are fluxed ofE 
 by being brought into contact with elements for which they have a 
 natural affinity. The slags formed in the iron furnaces are essentially 
 silicates, that is, the basis of their composition is silica, but alumina 
 lime, magnesia, and many other elements enter into the composition of 
 furnace slags. 
 
 Slagging. — ^The tapping out of the dag from a cupola. It requires to be 
 done several times in the course of a prolonged blow, to relieve the iron 
 of its impurities, and to prevent the loss of heat which the presence of 
 slag in quantity occasions. The better the quality of iron the less 
 slagging out is required. "With inferior and burnt iron the slag hole is 
 allowed to run nearly all the time the melting is going on. By judi- 
 cious slagging, one quarter to one half more metal can be melted in a 
 given time in a cupola than could be done if it were neglected. 
 
 Slag Hole. — The hole in a blast furnace or cupola through which the 
 slag is discharged. In a blast furnace it is situated in the lower part 
 of the crucible. In a cupola it is situated in the breast plate 
 (q.T.). 
 
 Slag Wool. — ^Tlsed as a coating for steam boilers and steam pipes. It is 
 prepared by directing a jet of steam against the molten slag as it issues 
 from the furnace. Sometimes termed spcate cotton, 
 
326 DICTIONARY OF TERMS USED IN 
 
 Slake Trough, — The vessel which contains the -water attached to a snaith's 
 forge for cooling or quenching hot metals. 
 
 Slaking. — Sleeking (q.T.). 
 
 Sleaker. — A sleeker (q-T.). 
 
 Sledge. — See Sledge Hanuner. 
 
 Sledge Hammer, or Sledge, simply, — The hammer swimg hy the smith's 
 stnker. It is a broad, flat-paned, double-ended hammer, weighing 
 from 5 to 14 lbs,, and is lifted up hand (q.v.) for the lightest blows, or 
 about sledge (q.v.) for the heaTiest. 
 
 Sleekers, or Smoothers, — Moulders' tools, made ia various forms and 
 used for smoothing and ftnishing the surfaces of sand moulds. See 
 Bead, Egg, and Square-comer Sleekers. Variously spelt Slakers, 
 Sleakers, and Slickers. 
 
 Sleeking, or Slaking, or Slicking. — Smoothing over the surface of a 
 foundry mould with tools specially adapted for the purpose. Broad 
 fiat surfaces are sleeked with the trowel, but where that fails to enter 
 proper sleekers (q.v.) are used. All except the roughest moulds are 
 sleeked both before and after blackening. 
 
 Sleepers. — (1) Balks of timber of rectangular section, used as the founda- 
 tions of the rails forming permanent way. Sleepers are either longitudinal, 
 or cross sleepers, aceordmg as they run continuously with the rails, or 
 transversely. Cross sleepers are laid underneath the longitudinal 
 ones. The chairs are attached to the sleepers. Dantzic or Memel fir 
 is the material commonly employed, which is usually creosoted or 
 otherwise preserved from the weather. Iron sleepers are sometimes 
 used in foreign countries. Timber sleepers are valuable by reason of 
 theic elasticity. Cast-iron sleepers are pot sleepers, elliptical in plan 
 and dome-shaped in elevation, and the chair and sleeper are a single 
 casting. Wrought iron has also been used for sleepers, both in the 
 pot form and also having the chair and sleeper independent of one 
 another, and held together with bolts. Iron sleepers are advantageous 
 in hot countries infested by white ants and other destructive insects. 
 (2) The timber imbedded in or laid on the ground to form the founda- 
 tions for derrick cranes, and to which the guys are fastened. 
 
 Sleeve. — ^A hollow cylinder or quill (q.v.). 
 
 Sleeve Bearing. — An unjointed bearing which is xmusually long in pro- 
 portion to its diameter. 
 
 Sleeve Screw. — An external screw whose cylinder is hollow throughout. 
 Examples occur in the feed screws of some drilling machines. 
 
 Sleeve Wheel. — A wheel on which is cast a long hollow boss, the boss 
 being made hoUow to fit over and sKde along a shaft. Examples occur 
 in the bevel wheels which slide along the revolving gantry shafts of 
 overhead travelling cranes, and through which motion is conveyed to 
 the crab in whatever part of the gantry it may happen to be situated. 
 
 Slewing. — The act of turning round, or revolving on a centre. Applied 
 to the circular movements of cranes and other revolving machines. 
 This is performed in hand cranes with a pair of bevel wheels actuated 
 by a winch handle, giving motion to a smaE pinion gearing into a curb 
 ring, or ring of cogs. In steam cranes the motive power is transmitted 
 to the curb ring through movable friction crutches, generally placed on 
 the engine shaft. 
 
 Slewing Bracket. — A bracket, or bearing, which carries the spindle of 
 the cog wheel used for slewing cranes. 
 
 Slewing Gear. — The gear by which the slewing motion of a travelling 
 
MECHANICAL ENGINEERING. 327 
 
 crane is actuated, consisting usually of friction cones actuating a 
 vertical shaft "whicli revolves a pinion in a curb ring on the truck. 
 
 Slice, or Slice Bar. — ^A firing tool, being a flat thin expansion only, at 
 the end of a long bar, and used for breaking up and separating the 
 clinkers on a furnace hearth. See Cliukering. 
 
 Slice Bar. — A shoe (q.v.). 
 
 Slicker. — A sleeker. 
 
 Slicking See Sleeking. 
 
 Slide. — A term which signifies in a general way any piece of mechanism 
 which moves in a rectilinear direction over a flat or curved face, for 
 the purpose of opening and shutting ofE communication with certain 
 chambers or passages, or which becomes a guide or steady to some 
 other piece of mechanism. 
 
 Slide Bars, or Guide Bars. — The bars by which the free end of a piston is 
 constrained to move in a straight line through the medium of slide 
 blocks (q.v.). The blocks move between the slide bars and are attached 
 to the cross head (q.v.) of the piston. Slide bars have flat, or cylindrical 
 faces. Sometimes termed motion bars. 
 
 Slide Blocks. — The blocks attached to the cross head (q.v.) of an engine or 
 pump, which, moving between and along the slide bars (q.v.), main- 
 tain the piston rod truly rectilinear. Also termed guide blocks, slipper 
 blocks, slippers, motion blocks. 
 
 Slide Case.— The old-fashioned steam chest affixed to an engine cylinder, 
 within which worked the long [) valve, now obsolete. The openings of 
 the ports being near the ends of the cylinder, and the valve being single 
 only, a case or chest, nearly equal in length to that of the cylinder 
 itself, was employed to cover them over, hence the term. 
 
 Slide Lathe. — A slide rest lathe (q.v.). 
 
 Slide Principle. — The slide principle is embodied in that construction in 
 which adjacent plates are so fitted one to the other with guiding strips 
 that they can move in one direction only, over each other. It has its 
 application in almost all kinds of modem machine tools. 
 
 Slide Best. — A lathe rest designed for automatic or self-acting turning 
 and screw cutting. It consists essentially of a saddle, fitted either to 
 the vee'd edges of the lathe bed, or between the bearers, and of two 
 slides moving on vee'd edges, one for sliding, the other for surfacing. 
 A circular swivelling motion is also usually provided for angular 
 turning. The sHdes are moved by hand screws, and the saddle is either 
 worked by hand or power with rack and pinion movement, or through 
 the intervention of the leading screw (q.v.). 
 
 Slide Eest Lathe, or Slide Lathe. — ^A lathe for metal turning furnished 
 with a slide rest. In the larger lathes the slide rest is an integral 
 portion of the lathe, without which no turning is done ; in the smaller 
 lathes it forms an attachment only for automatic turning, being 
 removed for the accomplishment of hand turning also. 
 
 Slide Rod. — A slide valve spindle (q.v.). 
 
 Slide Bule. — A rule provided with logarithmic numbers arranged on a 
 shding scale, whose graduations are so arranged relatively to other 
 similar graduations upon the body of the rule, that when a certain 
 number upon the scale is made to correspond with a certain number 
 upon the rule, a definite product or fraction is obtained without the 
 labour of calculation. 
 
 Slides. — The edges and faces of machine parts which carry and form the 
 guides of reotjlineally moving parts. See Adjustment Strips. 
 
328 DICTIONARY OF TERMS USED IN 
 
 Slide Valve. — Any Talve whose motion is that of eliding, aa opposed to 
 rotating' or lift -valves. The term is usually imderstood to refer 
 specially to the Talves of steam and gas engines of the ordinary type 
 (not Corliss or lift valves). These are usually of the D shape, but 
 may be single, double, or treble ported. They are also main slide, or 
 cut off expansion valves. They may be provided with lap or not, aU 
 of which terms are explained under their own headings. See also 
 EquiBbrium Valve, Travel, Setting of Valves. 
 
 Slide Valve Diagram. — See Valve Diagram. 
 
 Slide Valve Spindle, or Slide Eod. — The rod of a slide valve through 
 which motion is communicated from the eccentric to the valve, with or 
 without the intervention of a slot link. It is attached to the valve 
 either with a brass T -headed nut, or is hooped to embrace it, or is set 
 with nuts at each end of the valve. 
 
 Sliding. — Shding denotes the longitudinal traverse of a slide rest, that is 
 its motion lengthways on the bed. See Surfacing. 
 
 Sliding Blocks. — (1) The blocks which slide across the slotted cross head 
 of a steam pump. (2) Any blocks whose motion is that of a sliding 
 character are slide blocks. 
 
 Sliding Contact. — The communication of motion by means of cams, 
 screws, worms, and worm wheels. 
 
 Sliding Fit. — When sirrfaces cylindrical or plain move one over the other 
 freely, yet without perceptible slackness, the fit is so designated. The 
 difference of l-10,000th part of an inch in diameter will mate the 
 difference between a sliding and a slack fit. 
 
 Sliding Friction. — The friction which is set up between two surfaces in 
 contact. Its amount is independent of the area, so that the larger the 
 area the less the amount per unit of surface. 
 
 Sliding Pipe. — A suction or delivery pipe for a pump, made adjustable 
 for length with a joint similar to an expansion joint (q.v.). 
 
 Sliding Pulley. — A guide pulley for a rope or chain which is not con- 
 fined endways on its shaft, but which, while revolving, can at the 
 same time slide from side to side along the shaft to accommodate its 
 position to that of the rope or chain as the latter is wound or unwound 
 towards one end or the other of its barrel. Instances occur on the jibs 
 of cranes. 
 
 Slimes. — The deposits of tin ore left in the washing reservoirs after the 
 process of stamping (q.v.) and subsidence is complete. The slimes are 
 subjected to a further process of washing previous to calcination. 
 
 Sling. — A rope, or chain, or cKp passed around a load for the purpose of 
 lifting and moving it about. 
 
 Sling Chain. — ^An ordinary piece or a bight of chain used for encircling 
 heavy work for the purpose of lifting about, the crane hook being 
 inserted into a lap of the chain. 
 
 Slinging. — The securing of heavy masses of material in the ropes or 
 chains of cranes or of pulley blocks while being hoisted about. The 
 methods of slinging vary with the shape of the body which is being 
 lifted. 
 
 Slinging Eings. — Rings attached to the top of a portable engine boiler 
 by means of straps riveted to the boiler shell, and used for lifting the 
 boiler by. 
 
 Sling Bods. — The rods or stays by which a locomotive boiler is attached 
 to the framing. 
 
 Sling Stays. — Slings used for attaching girder stays C<l-v.) to the crown 
 
MECHANICAL ENGINEERING. .■^ag 
 
 of the outer fire tox shell in locomotive and portable boilers. The 
 sling stays are attached to angle or X irons. 
 
 Slip. — The sliding of riveted joints one over the other to such an extent 
 as to be visible. See also Gouge SUp, Slip of a Screw. 
 
 Slip Jaws. — Temporary facings dovetailed on the gripping portions of 
 the jaws of lathe chucks. 
 
 Slip Knot. — A knot -which allows the rope to glide through it and to 
 become taut. It is used in slinging (q.v.). 
 
 Slip of a Screw. — The difference between the theoretical performance of 
 a ship's screw supposing it moved in an unyielding medium, and the 
 actuELl performance, the yielding nature of the water being taken into 
 account. The slip of a propeller is always given as so much per cent, 
 on the distance as calculated from the working of the engine. 
 
 Slipper. — A slide block (q.v.). 
 
 Slipper Block. — A slide block (q.v.). 
 
 Slipper Brake. — A form of brake which consists of iron blocks so attached 
 to a truck by an arrangement of screws and levers that they can be 
 thrust forcibly down on the rails when it is desired to arrest the motion 
 of a wagon or train. It is thus the reverse of the method conunonly 
 employed, of braking the wheels themselves. 
 
 Slipper Guides. — Slide bars (q.v.). 
 
 Slippery Iron. — A mixture of cast iron specially prepared for engine 
 cylinders, cylinder liners, slide blocks, and moving surfaces generally. 
 It is tough and moderately hard, and its shpperiness of surface is 
 obtained by using a manganiferous brand of iron, the manganese being 
 present to the amount of 2 or 3 per cent. 
 
 Slipping Load. — A term sometimes used to denote the load necessary to 
 produce sHp in riveted plates. See SUp. It is stated in terms of tons 
 per rivet subject to strain. 
 
 Slipping of Belts. — See Belt Tension, Belt Dressing. 
 
 Slit Bar. — A bar having an open slot or central clear space within which 
 a stud is slid or tightened at pleasure. Linear and rotative motions are 
 thereby rendered interchangeable, and the length of stroke of recipro- 
 cating rods is rendered capable of adjustment. Slit bars are used in 
 machines of almost all descriptions, and in prime movers. 
 
 Slit Bar notion. — The mechanism of a rod or link, the amount of whose 
 throw is capable of adjustment within the limits of a slit or slits in the 
 rod along which the set bolt for varied adjustment slides. 
 
 Slitting File. — A file whose section is that of a double V having two 
 thin knife-like edges. 
 
 Slope Tile. — See Square TEe. 
 
 Slot. — ^An oblong hole, which may be either rounding or square at the 
 ends. Slot holes are cut in levers to allow of adjustment for length 
 and in machine slides to take up the wear, the adjustment being made 
 by a small nut or set screw, or in a cottar way (q.v.) by means of a 
 wedge or cottar (q.v.). 
 
 Slot Drilling. — The cutting of slots either for cottars or set screw adjust- 
 ment, or of shallow grooves for the reception of sunk feathers, by 
 means of a machine somewhat similar to a drill, the cutting tool being 
 carried by a revolving spindle, though provided with no downward feed, 
 but having a sliding table, which, while carrying the work, is fed along 
 under the slot drill, thus cutting an oblong recess or hole of any re- 
 quired length and of uniform depth throughout, 
 §lot Hole,— See Slot, 
 
330 DICTIONARY OF TERMS USED IN 
 
 Slot Link, — The movable Unk, the shifting of whose position relatively to 
 the valve rod of an engine cylinder determines the amount of cut-off, 
 and the forward or backward motion of the engine ; called also the 
 reversing link. These results it effects by bringing one or other of the 
 eccentric rods in turn into a line with the valve spindle. 
 
 Slotted Cross Head, — A cross head (q-v.) slotted for the reception of the 
 sliding block attached to the end of the connecting rod of a steam pump, 
 and which combines rectilinear with rotational movement. 
 
 Slotting. — The vertical cutting of narrow grooves and keyways, and 
 generally the vertical shaping of curved outlines by means of a slotting 
 machine (q.v.). 
 
 Slotting Machine. — A machine used for shaping metals, the arm which 
 carries the cutters moving in a vertical direction. The travel of the arm 
 is capable of adjustment by means of a connecting rod movable in a slot 
 in the arm ; and provision is also made for imparting feed (q.v.) motion 
 to the table, and aLso motion in a circular direction. The arm also is 
 usually supplied with provision for quick return (q.v.) motion by means 
 of a link attached to a disc, on the same principle as that employed 
 in shaping machines. Slotting machines occur in modified forms. 
 What are known as curvilinear machines are constructed for slotting 
 out the interior portions of the rims of railway wheels. 
 
 Slotting Tools. — Comprise round-edged, keyway, parting, and hook tools. 
 
 Slow Cutting Motion. — The motion of the tool box of a shaping or slotting 
 machine during the forward or downward stroke, as opposed to the quick 
 return (q.v.) stroke. 
 
 Slow Feed. — When provision is made for two sets of feed motions, as in 
 many drilling machines, one is termed the slow and the other the fast 
 or quick feed, the variation being necessary, since different work demands 
 different rates of feed according to the coarseness or fineness of the 
 iinish required, or the nature of the metal itself. 
 
 Slow Gear, — The double or treble purchase gear of cranes and hoisting 
 machinery, and the back gear of lathes and drilling and other machines, 
 are termed slow gear, because with increase of power there must be 
 corresponding and inverse diminution of velocity. 
 
 Sludge, — The muddy deposit which accumulates in a steam boiler. 
 
 Sludge Cock. — The cock at the bottom of a steam boiler which is employed 
 for the purpose of cleaning the boiler from sludge by periodical washing 
 through with a strong current of water. 
 
 Sludge Hole A mud hole (q.v.). 
 
 Sluice. — (1) A water way and gate, or a disc plug valve for the regulation 
 of the flow of water. (2) The opening through which the water is ad- 
 mitted to a water wheel or turbine. 
 
 Slurry. — A term used in foundries to signify dirty water, or black wash, 
 and in a general way any fluid used in moulding. 
 
 Small Coal. — Coal which has been screened at the pit's mouth. It is used 
 to a limited extent in engine and smiths' fires and furnaces, but is 
 more largely employed in the manufacture of patent fuels (q.v.). 
 
 Smelting. — The process of the reduction of metals from their ores, effected 
 ohieily by the aid of heat, and fluxing and reducing agents. 
 
 Smelting Furnace. — A blast furnace (q.v.) or some form of reverberatory 
 furnace (q.v.). 
 
 Smith. — An engineer's smith is a specialist, since his work relates entirely 
 to forging of machine parts. Usually it is of a somewhat heavier 
 nature than that of an ordinary smith, requiring the aid of the steam 
 
MECHANICAL ENGINEERING. 331 
 
 hammer ; and in the Bghter -work, owing to the repetition demanded, die 
 blocks (see Die) in which the forgings are either partly or entirely 
 stamped, axe largely used. 
 
 Smith's Brace. — A hand brace used by smiths for drilling holes of 
 moderate diameter. Its outline is very similar to that of the ordinary 
 carpenter's brace, and it is turned in the same way, but the requisite 
 pressure is imparted at the top by means of a feeding screw against 
 whose end the top of the brace, which is formed iato a hardened point, 
 is centred. The resistance is taken by a horizontal arm ha"ving a boss 
 tapped to receive the feeding screw, the arm being capable of sliding 
 up and down, and of being tightened at any height on a vertical pillar, 
 whose foot is bolted to a bench or clasped in a vice. These braces are 
 not used much in engineers' smithies, the ratchet brace and drilling 
 machines being more convenient. 
 
 Smiths' Hammers. — Smiths' hammers embrace the sledge hammer, the 
 ordinary hand hammer having either a straight or a ball pane at the 
 small end, the set hammer, and the various flatters and fullers, which 
 though not strictly speaking hammers, are nevertheless tools of a 
 similar type. Notes on each will be found under their respective head- 
 ings. See also Oliver, Tilt Hammer, &c. 
 
 Smith's Saw. — A hack saw (q..v.). 
 
 Smith's Shop. — The shed or building in which the operations of smith's 
 work are carried on. The forges are arranged around the walls, space 
 being left between each for the racks which carry the swages, fullers, 
 chisels, and other similar tools. The anvils stand in front of these open 
 spaces. A light wall crane is attached to the wall between each forge, 
 or one to two forges. The central open space of the shop is occupied 
 with steam hammers, forging machines, &c. A shed adjoining the 
 shop is used as a store for bar iron. 
 
 Smiths' Tools. — Include anvils, anvil stands, forges and firing tools, 
 hammers, tongs, flatters, fullers, swages in their various forms, sets, 
 pliers, punches, bolt and heading tools, and drills, chisels, saws, and 
 machines, both special and common to the fitting and erecting shops, 
 each described in place. 
 
 Smith's Work. — The heating, handling, light hammering, and manipu- 
 lation of wrought iron and steel, the direction of the heavier blows of 
 the striker, the holding of the top swages, and other tools, the pre- 
 paring of joints for welding, the hardening and tempering of steel, &o. 
 
 Smithy Fan, — A centrifugal fan used for blowing the fires in a smith's 
 shop, branch pipes leading to each forge through tuyeres, and the 
 amount of blast being capable of regulation by a valve. 
 
 Smoke. — Consists of a mass of minute particles of solid unbumt carbon 
 liberated from hydro-carbons by the action of heat, and suspended in 
 an enveloping _2nedium of vapour of water, and unbumt gases given 
 off by the fuel. See Smoke Prevention. Black smoke is that which 
 contains the largest quantity of solid carbon. The so-called smoke 
 which is of a yellowish or yellowish brown colour is not smoke (i.e. 
 free carbon), but carburetted hydrogen, chiefly defiant and marsh 
 gases mixed with tarry and sulphurous matters. 
 Smoke Box. — The front part of the locomotive, or portable engine boOer, 
 into which the tubes discharge the products of combustion on their way 
 to the chimney. 
 Smoke Box Plate. — The dished plate which covers over the outer end of 
 the smoke box of a locomotive or portable engine boiler and which is 
 
332 DICTIONARY OF TERMS USED IN 
 
 removed when the tuhes require examination or cleaning. It is usually 
 of wrought iron, but is sometimes cast. 
 
 Smoke Consuming.— The application of the principle of perfect com- 
 bustion, to the smoke from furnaces, whereby the solid carbon and in- 
 flammable gases are fully oxidised. See Smoke Prevention. 
 
 Smoke Flues. — The flues of Cornish and Lancashire boiler.i, and ex- 
 ternally fired boUers which are built in brick work, as distinguished 
 from the fire fiues (q.v.) of internally fired boilers. 
 
 Smokeless Coals. — Anthracite, and anthracitic coals (q.v.). 
 
 Smoke Prevention, — Without describing the various schemes that have 
 been proposed to prevent the nuisance of smoke formation, it is as well 
 to note the essential conditions which must obtain in order to its re- 
 moval. The black smoke and yellow smoke (see Smoke) which are 
 given off from engine fires is given off in these forms, either beoausa 
 there is not a sufficient quantity of oxygen present to form a chemical 
 union therewith, or because, if present, the temperature is not sufficiently 
 high to produce ignition. AH such gases and solid carbon allowed to 
 pass off unbumt represents a vast amount of heat wasted. Hence the 
 adoption of measures to prevent the formation of amoke not only abates 
 a nuisance but is an economical gain. In ordinary furnaces the remedy 
 is obvious. The fuel should be well coked on the dead plate so that 
 the liberated gases shall be well consumed in the combustion chamber 
 on their way to the chimney. 
 
 Smooth Cut File. — An ordinary smooth or fine file. A smooth cut file of 
 12 in. in length wiU oontaiu 72 lines of teeth to the liaeariach. 
 
 Smoother. — A sleeker (q.v.). 
 
 Smoothing Plane. — A small plane used by wood workers for giving a 
 smooth finish to surfaces in cases where accuracy is not very essential. 
 It measures about 8 in. in length, and its cutting iron will range 
 from 1| in. to %\ in. in width. 
 
 Snail. — A volute-shaped cam. 
 
 Snap. — The steel die used by riveters for finishing the heads of rivets. 
 
 Snap Head. — See Snap Head Eivet. 
 
 Snap Head Eivet, or Cup Head Eivet. — A rivet whose head is semi- 
 circular or cup-shaped in section. 
 
 Snatch Block. — The suspended block in lifting tackle, containing the 
 pulleys which rest in the lower bight of the chain. 
 
 Snifting Valve. — A relief valve, used generally for the purpose of afford- 
 ing an exit for an imprisoned fluid or gas, when the pressure thereon 
 attains a definite amount. In a condensing engine it is the valve 
 through which the steam and air which mingle in the blowing through 
 (q.v.) process pass out of the oyhnder. 
 
 Snug. — A lug (q.v.). 
 
 SoaMng. — See Soaking Pit. 
 
 Soaking Pit. — A cavity or pit in the ground or baserof a steel works, 
 lined with fire brick, and in which steel ingots are laid to soak, as it 
 is termed, before beiag passed to the cogging and rolling miUs ; the 
 soaking being a term apphed to the uniform distribution of the tem- 
 perature of the ingot. The ingot is too fluid iu its central portion for 
 rolling immediately that it leaves the mould, and if allowed to cool, 
 the outer skin becomes set while the inner portion is yet in a semi- 
 fluid condition. By cooling the ingot in a pit of fire brick, the tem- 
 perature becomes uniformly distributed without much loss of heat by 
 radiation. Hence reheating is unnecessary when soaking is resorted 
 
MMCHANICAL EMGlNEBRl^O. 33J 
 
 to, that IB, so long aa the ingots are not allowed to accumulate on 
 tand. 
 
 Soap. — Soap is thrown into the melting pot containing gun-metal orbrasa 
 to act as a flux. See also Soapsuds, Soft Soap. 
 
 Soapstone Gasket. — A form of packing used for hydraulic joints, made 
 of hemp, tallow, French chalJr, and other ingredients. Called soap- 
 stone because of its greasy nature. 
 
 Soapsuds. — Soap and water used in the lubrication of cutting tools, and 
 supplied from a soap-water can (q.v.). 
 
 Soapsuds Can. — A soap-water can (q.v.). 
 
 Soap Water Can. — A cyUndrioal tin can, open at the top and furnished 
 with a stop cook near the bottom. It is used to effect the lubrication 
 of work which is being turned or otherwise machined, the stop cook 
 being opened only just so much as wiU allow of the slow drip of the 
 fluid contained in the can, upon the work. The usual lubricant is soap 
 and water, or oil. Hence called drip oil can. 
 
 Socket. — That enlarged recessed portion of a pipe which receives the 
 spigoted end of the pipe to which it is united. Called also the faucet. 
 When the spigot pipe is inserted into the socket, the joint is secured 
 by stemming or caulking with lead, or with rope gasket, or in the best 
 pipes the joints are turned and bored. 
 
 Socket Bend. — A bend pipe furnished with a socket at one end and a 
 spigot at the other. 
 
 Socket Chisel. — The strongest kind of chisel made, used hke the mortice 
 chisel for cutting the joints of heavy timber framing, being actuated by 
 the mallet alone. It derives its name from the upper end terminating 
 in a hollow tapered socket, into which a round wooden handle is driven. 
 These chisels range from f in. to IJ in. in width. 
 
 Socket Pipe. — A cast-iron pipe which is provided with a socket (q.v.) at 
 one end and a spigot (q.v.) at the other. The sockets of wrought-iron 
 pipes are unions (q.v.), and are screwed over the ends on the outside 
 diameter. 
 
 Socket Washer. — See India-rubber "Washer. 
 
 Soda. — Common soda is used for the purpose of preventing and of 
 removing incrustation of carbonate and sulphate of lime from steam 
 boilers. This is efEeoted by an exchange of acids, the carbonate in the 
 soda entering into combination with the lime, forming sulphate of 
 Ume, which is soluble, and carbonate of soda, which is deposited. The 
 soda is either introduced in lumps or is dissolved with the feed water. 
 Soda ash is sometimes substituted, sometimes also caustic soda. In the 
 former case a larger quantity, in the latter a smaller amount is required. 
 Soda is useful, neutralising the grease in greasy feed water, forming 
 with it a soluble soap. 
 
 Soda Ash.— See Soda. 
 
 Soffit. — The intrados (q.v.) of an arch. 
 
 Soft Blast. — A blast of low velocity, or a blast insuflioient in amount, 
 its pressure being inadequate to melt the metal without an excessive 
 expenditure of fuel. 
 
 Soft Brass. — Brass which has been annealed after drawing and rolling. 
 Used for purposes requiring ductility. 
 
 Soft Centred Steel. — See Mild Centred Steel. 
 
 Softener. — A double colour brush (q.v.) used by draughtsmen for shad- 
 ing. 
 
 Soft Grit. — A griadstone of soft and porous texture, 
 
334 DICTIONARY OF TERMS USED IN 
 
 Soft Iron. — Iron wHoh can te shaped Tvith ordinary cutting tools or 
 abraded readily with files. The quality is due to the amount of carton 
 present and the manner of its combination, and also to the mode of 
 crystallisation. Iron which contains practically no carbon, as mal- 
 leable iron, is -very soft, so also is iron which contains the maximum of 
 carbon, as foundry pigs, which may contain as much as 4 or 5 per cent. 
 Carbon when present in the graphitioal condition makes a soft iron, 
 but a very much smaller proportion when in the combined state yields 
 white iron, which is extremely hard. Iron allowed to cool slowly in 
 sand is soft, while the same iron cooled rapidly against a metallio 
 chill is hard. Soft iron is used for all ordinary castings which have to 
 be machined ; tough, slippery, and hard iron being reserved for special 
 classes of work. Where it is necessary to machine castings of hard 
 iron, grinding- or cutting by means of an extremely slow feed is 
 resorted to. 
 
 Soft Hetal. — This is a relative term expressive of the density of the particu- 
 lar metal in relation to the purpose for which it is required. Metals aro 
 soft when they are more ductile, more elastic, and more easily cut than 
 the same metals when hard. Hard brittle metals are rendered softer 
 by annealing (q.v.), by judicious cooling, and by chemical changes 
 affecting the relative proportions of foreign metallio or non-metallio 
 substances, which are always present in small and variable quantites. 
 
 Soft Bain Tiling. — See Hard Hamming. 
 
 Soft Soap. — Soft soap is used for the lubrication of the wooden patterns of 
 pipes and columns while turning in the lathe, and supported by a 
 steady, the soap being rubbed into the bearing of the steady to prevent 
 heating and burning of the wood. Used also in the mixing of soap 
 suds (q.v.). 
 
 Soft Solder. — Solder used for uniting the joints of works in lead, tin, and 
 soft brass, and similar metals and alloys. Its composition is various, 
 and so also are the fi.uxes employed with it. 
 
 Soft Water. — Water free from carbonate and sulphate of lime. The 
 softer the water for hot water apparatus and for steam boilers the 
 better, since it will then produce less calcareous deposit in the pipes 
 and on the plates. 
 
 Soft Woods.' — The soft woods employed by engineers are pine — both 
 yellow, red, and white — spruce, red deal, kauri pine, &c. 
 
 Solder. — A metallio cementing material interposed between surfaces 
 which are to be united in close and firm contact. See Hard Solders, 
 and Soft Solder. 
 
 Soldering. — The uniting of two portions of metal by means of another 
 metal or of an alloy. Soft soldering is effected with the aid of various 
 alloys of lead and tin. Hard soldering applies to the alloys of copper 
 and tin, and is called brazing (q.v.). A clean surface is essential to 
 efBoient soldering. A copper bit (q.v.) is used in soft soldering ; in 
 hard soldering the parts are held together with binding wire (q.v.), 
 and the metal allowed to run in. See Autogenous Soldering, Brazing 
 Metal, Sweating On. 
 
 Sole Plate. — (1) A thin base plate, differing from a bed plate in its more 
 slender form being either unstayed or but slightly stiffened with flanges 
 or ribs. It usually owes much of its rigidity to the timber or metal 
 foundation upon which it is fastened. A sole plate is often a mere base 
 for plummer blocks. Not unfrequently, however, the term is applied 
 indiscriminately to ordinary bed plates. (2) The periphery of a water 
 
MECHANICAL ENGWEERlNG. 33S 
 
 wheel from whioh the buckets start. (3) The bed of a reverberatory 
 furnace (c[.t.). 
 
 Soles. — The longitudinal or side timbers in the under frame of a railway 
 truck. 
 
 Solid. — ^A body or substance which is able to sustain a longitudinal 
 pressure without receiving lateral support is termed a solid. 
 
 Solid Elows. — Dead, non-elastic blows, imparted by a hammer to a sheet 
 of metal, or similar solid body, which rests upon a fii-m and sohd sup- 
 port. The effect of a solid blow is to indent or thin the metal, and 
 spread it out over a large area. Solid blows are imparted to wedges, 
 nails, keys, cogs, &c., by holding the hammer very firmly when 
 striking. 
 
 Solid Box. — A solid or unjointed bearing. A dead eye (q.v.). 
 
 Solid Column. — See Hollow Column. 
 
 Solid Coupling. — A coupling forged in a sohd piece with its shaft. The 
 ordinary couplings of propeller shafts are an example of the sohd form. 
 
 Solid Drawn Tubes, or Seamless Tubes. — Drawn tubes, in opposition to 
 brazed, or welded, or riveted tubes. The copper piping for feed, 
 bUge, blow-off, and similar purposes in connection with marine 
 engines, the brass tubes for surface condensers, and the tubes of multi- 
 tubular boilers, are all solid drawn. Iron hydraulic tubes also are 
 solid drawn. 
 
 Solid Emery Wheel. — A wheel bmlt wholly of emery, to distinguish it 
 from a wheel in which the powder is laid on a centre of wood. 
 
 Solid Half Bounds. — See Half Eoimd Iron. 
 
 Solidity. — The eohd contents of a body. The solidity of aU bodies can be 
 obtained by calculation, and it is often necessary to be able to do so in 
 order to obtain their mass and weight. 
 
 Solid Piston, — An engine piston which is a solid disc, instead of being 
 built up in separate portions. The circumference of the disc is recessed 
 for the reception of spring rings (q.v.). 
 
 Solid Beamer, — See Keamer. 
 
 Solid Soiled. — ;Ordinary rolled wrought-iron joists, beams, or girders, as 
 distinguished from beams and girders which are built up with trellis 
 work of various types. 
 
 Solid Tool. — An ordinary tool for metal turning in which the cutting 
 point is in one with its shank, as distinguished from the smaller. tool 
 points used with a tool holder (q.v.). 
 
 Soot. — Solid uuburnt carbon which accumulates in the flues of engine 
 furnaces, and the amount of whose accumulation should be reduced 
 as much as possible by consuming the smoke in the furnace, soot repre- 
 senting fuel wasted. 
 
 Soot Door. — A square iron door inserted in an iron frame, built into the 
 front ends of the brickwork flues of Cornish and other boilers of the 
 horizontal type, through which the periodical accumulations of soot 
 are removed. 
 
 Sow. — See Pig. 
 
 Spacing. — The dividing or setting out of holes, rivets, bolts, &c., into 
 their relative positions in a piece of work, the compasses or dividers or 
 special templets being used for the purpose. 
 
 Spall. — To break off a chip. Usually apphed to the accidental breaking 
 off or out of a strip of wood when planing the end grain of timber. 
 SpaUing only occurs when the planing is clumsily or carelessly done. 
 It is readily prevented by first chamfering the edge towards which the 
 
336 DICTIONARV OP TERMS USED W 
 
 plane is cutting, or by planing alternately from each edge. Broke* 
 edges are said to be spalled or spalt. 
 
 Span. — (1) The horizontal distance between the springings (q.v.) of an 
 arch. (2) The distance measured between the supports which sustain a 
 beam, or girder or girder-hke structure. The strength of beams of 
 similar section and similarly fixed will vary inversely with the span. 
 
 Spandrel. — The space enclosed between the outer curve of an arch, a 
 horizontal line from its apex and a vertical line from its springing. 
 
 Spanish Mahogany. — See Mahogany. 
 
 Spanner, — A lever used for the tightening up of nuts. Spanners are 
 usually double ended, that is, each end is formed to take a nut of a 
 different size than the end opposite. The size of a spanner is reckoned 
 by the diameter of bolt for which it is suited and not by the width of 
 the jaws. Thus a ^-in. spanner takes a j-in. nut, but will be an 
 inch vdde in the jaw. The angle which the spanner jaws make with 
 the handle is not arbitrary, but is selected with the view to turning a 
 nut in the least possible space. If the handle is straight with the 
 jaws, a hexagon nut cannot be turned in less than 60°, or a square one 
 in less than 90°. But if the angle of the jaws be made 15°, a hexagon 
 nut can be tximed in 30°. The length of a spanner may be from 15 to 
 18 times the diameter of the bolt. See also Screw Wrench. 
 
 Spare. — See Spare Gear. 
 
 Spare Gear, or Spare, or Spare Parts. — Signifies the supply of duplicate 
 portions of machinery together with the order to wMch they belong. 
 It is customary to include spare parts with work which is despatched 
 to the colonies and with sea-going engines ; the parts consisting of 
 those which wear out most rapidly, and therefore require frequent 
 replacement, or those vital parts upon which the efficiency of the 
 machine or engine mainly depends, and which in the case of a break- 
 down it would be difficult or impossible to replace immediately. 
 
 Spare Parts. — See Spare Gear. 
 
 Spark Arrester. — (I) A globular cage of galvanised iron wire, or a curved 
 plate of sheet iron, put above the chimney of a portable engine or crane 
 to arrest and throw back the sparks. (2) A grating placed across the 
 smoke box and beneath the blast nozzle in some locomotives to arrest 
 the upward flight of sparks. 
 
 Spathic Ore. — Is a carbonate of iron found chiefly in Styria and Carinthia. 
 It owes its chief value to the presence of manganese, which renders it 
 especially suitable for the making of some quafities of steel. 
 
 Spear. — See Pump Spear. 
 
 Specification. — A docimient in which all particulars, both general and in 
 detail, are stated respecting the construction of a machine or engineering 
 work. Specifications are issued for all important works, and are bind- 
 ing on the contracting parties. 
 
 Specific Gravity. — The density or weight of a substance estimated rela- 
 tively to that of water, if a solid or liquid, or relatively to that of air at 
 the same temperature and pressure, if a gas. It is denoted by the 
 initials sp. gr. 
 
 Specific Heat. — The ratio of the quantity of heat required to raise the 
 temperature of a given weight of a substance through 1° F. to the 
 quantity of heat required to raise the temperature of an equal weight 
 of water at 39° P. or 4° C. through 1°. In other words, the capacity of 
 a body for heat, relatively to that of water. 
 
 Specific levity.— Signifies the relative tendency of those gaseous elements 
 
MECHANICAL ENGINEERING. 337 
 
 and compoimda whicli are lighter than air to rise. It is therefore the 
 opposite to specific gra-rity. 
 
 SpeoLfic Volume, or Relative Volume. — The volume of a gas or vapour 
 compared with that of the liquid from -wluoh it is generated. 
 
 Specimen. Bar. — A length of bar of any material specially prepared for 
 testing in a testing machine. Bars are either provided with shouldered 
 ends to be held in bridles or clips, or are screwed into their bridles. 
 
 Specimen Bridle. — See Specimen Holder. 
 
 Specimen Holder. — A bit of mechanism employed for holding specimens 
 to be tested in the testing machine (q.v.). They are made for the most 
 part to clip the specimen, which has collars at the ends to fit thereon. 
 Hence termed specimen bridles. 
 
 Specimen Plate. — A piece of plate of any material specially prepared for 
 testing in a testing machine. Plate specimens are embraced at tha 
 ends, the breadth at the ends being increased to maintain the sectional 
 area, and so compensate for the loss of strength due to the holes made 
 for attachment. The central portion of the plate is parallel. Mr. 
 Kirkaldy's plates are 10 in. long by 2 in. wide. The Admiralty length 
 is 8 in., and the area of original section as nearly as possible one square 
 inch. The Hrench standard is 200 mm. (7-87 in.). 
 
 Specular Ore. — A non-hydrated peroxide of iron which furnishes metal 
 of excellent quality. It is one of the haematites, and derives its name 
 from the lustre of its crystals; hence also the term "iron glance" 
 applied to it. 
 
 Speed Cones. — See Speed Pulleys. 
 
 Speeding, — The calculation of the diameters of puUeys and gear wheels in 
 order to obtain definite velocity ratios (q.v.) between the shafts and 
 spindles connected with each other through their medium. 
 
 Speed of Ignition, — This has reference to the rapiditjr with which chemical 
 combination take§ place between the air and gas m a gas engine. The 
 speed of ignition is slow or rapid, according as the percentage of ad- 
 mixed air is large or small. The speed of ignition must always exceed 
 the piston speed in order to obtain the best results due to chemical 
 combination. 
 
 Speed Pulleys, or Speed Cones, — ^Pairs of pulleys, each stepped down to 
 different diameters, but both being alike or nearly alike in dimensions. 
 'They are arranged the reverse way to each other on their shafts, the 
 smallest diameter of the one coming in Hue with the largest diameter of 
 the other. By shiftiag the belt to the corresponding pairs variations in 
 speed corresponding with the variations in their respective diameters 
 are obtainable. When speed pulleys are so placed that tfieir centres are 
 situated a long distance apart, the steps are equal, that is, the sums of 
 the diameters of each pair of steps throughout are the same, but when 
 the centres approximate, the sums are not precisely aKke, the difference 
 being due to the greater obliquity of the belt, and then the diameters 
 may either be obtained by an elaborate calculation or by a more simple 
 graphic delineation. 
 
 Speeds. — Speeds signifies the steps of a cone or driving pulley or drum, 
 or the diameters around which the belt or cord laps, as three speed, 
 four speed, &o. 
 
 Speed of Cutting Tools, — See Cutting Tools, Speed of. 
 
 Spelter. — Zinc (q.v.) cast into the ingots of commerce. Also an alloy of 
 equal parts of zinc and copper. 
 
 Sperm Oil.— See Whale Oil. 
 
 z 
 
338 DICTIONARY OF TERMS USED IN 
 
 Sp. 6r. — Specific gravity (q.v.). 
 
 Sphere. — A solid having every part of its surface equally distant from its 
 centre. The sphere has these properties — that of all solids of a given 
 volume it is that which has the least surface, and of all solids of a giveq 
 surface it is that which has the greatest volume. 
 
 Spider Wheel,— A wheel or pulley having Ught arms of wrought iron or 
 steel. 
 
 Spiegel. — An abbreviation for spiegeleisen (q.v.). 
 
 Spiegeleisen. — ^A variety of iron which is invaluable to the steel manu- 
 facturers, and which owes its value to the presence of definite amounts 
 of carbon and manganese. By adding spiegeleisen in definite pro- 
 portions, any desired exact quantity of these elements can be imparted to 
 decarburised iron melted in association therewith, causing the immediate 
 production of a definite grade of steel. See Ferro-Manganese. 
 
 Spikes. — (1) Iron fastenings used for holding railway chairs down to the 
 sleepers. They are either cyliudrical bars with circular heads, or rect- 
 angular bars with a single projecting head on one side. The latter are 
 also termed dogs, or dog spiies. (2) Nails larger than tenpenny nails, 
 or over three inches in length. 
 
 Spills. — The cracks and seams which occur in inferior iron bars, and in 
 which adhesion is imperfect, owing to the presence of scales. Wlien a 
 bar of wrought iron or steel shows these cracks or seams in its fibre it is 
 said by smiths to be spiLLy. 
 
 SpiUy. — See Spills. 
 
 Spindle. — A slight metal rod used for carrying wheels and pulleys in light 
 machinery. It is a shaft of small diameter. 
 
 Spindles. — See Breaking Pieces. 
 
 Spindle Valve. — A lift valve guided by a central axial spindle or stem. 
 
 Spindle Wheel. — The toothed wheel on the leading screw or spindle of a 
 screw-cutting lathe, therefore being a "driven" wheel in the series of 
 change wheels. 
 
 Spinning. — The moulding of circular articles in thin sheet metal by pressure 
 applied during rotation in a lathe. Also termed burnishing. 
 
 S Pipe. — ^A pipe whose outline is roughly that of the letter Sj used for 
 connecting parallel lengths of straight piping. 
 
 Spiral Gear. — Includes helical, stepped, and worm gearing. Described 
 under those headings. 
 
 Spiral Spring. — A helical coil of an elastic material, as steel, brass, or iron, 
 which has the faculty of extension and compression in the direction of 
 its length. Used in spring balances, locomotive axle springs, and as 
 elastic cushions. A spiral springis understood to have all its coils of the 
 same diameter and pitch. In a heKcal spring the diameters of the coOs 
 increase with each revolution. A bufEer spring is a good example of a 
 helical spring. In a doujjle helical spring the diameters of the coils in- 
 crease from the centre towards the ends. 
 
 Spiral Winged Valve. — A lift valve, the wings of which instead of being 
 at right angles to the seat, are arranged as sections of a spiral of very 
 long pitch. The advantage is that the valve is turned round on its seat- 
 ing to a slight degree at each hft, thus rendering the wear uniform. 
 
 Spirit. — Methylated spirit, and spirit of wine are used for making shellac 
 varnish (q.v.) 
 
 Spirit Level. — An instrument used for trying the horizontal and vertical 
 accuracy of work. It consists of a glass bulb nearly but not quite full 
 of spirit, and enclosed in a wooden casing. The bubble formed by the 
 
MECHANICAL ENGINEERING. 339 
 
 vacancy in the bulb indicates by its central position tie accuracy of the 
 surface under test. For testing vertical surfaces the bubble is placed 
 transversely near one end of the stock, which is then pierced with a hole 
 to permit of it being seen. 
 
 Spirits of Salts. — Hydrochloric acid (q.v.). 
 
 Splasher. — The guard plate or guard strap (q.v.) which covers the top of 
 a locomotive wheel. 
 
 Splicing. — ^The splicing of hempen and wire rope is generally performed 
 by some one of the engineer's labourers who has been an old sailor. The 
 hempen ropes require to be well stretched previous to splicing, else the 
 operation has to be repeated several times subsequently at short intervals, 
 especially in the long ropes used for travelling and gantry cranes. 
 
 Spline. — A feather (q.v.) on a shaft. 
 
 Split Cottar Pin. — A split pin (q.v.). 
 
 Split Draught. — In an internally fired boOer (q.v.) the gases pass through 
 the furnace tubes (q.v.) to the back of the boUer, whence they dip under- 
 neath into an external flue of brickwork, and so pass to the front end. 
 Thence they divide or split to right and left into 'two distinct brick 
 flues placed upon each side of the boiler, which conduct (them to the 
 chimney. This is called split draught to distinguish it from wheel 
 draught (q.v.). Dampers (q.v.) are placed in these side flues at the 
 farther ends. 
 
 Split Joint. — See Tongue Joint. 
 
 Split Pin, or Split Cottar Pin. — A split pin is formed of wire whose 
 section is hemispherical, bent round until the flat faces meet. It is 
 then inserted into the circular hole prepared for its reception and the free 
 ends drawn apart to prevent the pin from falling out. It forms a secure 
 and neat fastening for the pin of a knuckle joint, and is largely used. 
 
 Split Pulley. — ^A pulley made in halves and bolted together, and used in 
 cases where it would be impossible or inconvenient to slide it on from 
 the end of its shaft. The two halves are unscrewed, clipped over the 
 shaft, and bolted up in place. 
 
 Split Bing. — An ordinary piston ring, or ring which is divided either 
 diagonally or with a lapped joint to afford the elasticity necessary to 
 render it steam tight. 
 
 Splitting. — The method of dividing castings of wheels and pulleys in the 
 act of casting. It is done either in order to have two symmetrical 
 halves which can be fitted to the central portion of a shaft when other 
 wheels, pulleys, or bearings occupy the ends, or to relieve the strain on 
 a casting due to unequal massing of metal around the boss. It is 
 effected by introducing splitting plates (q.v.) into the mould, which 
 usually not only divide the mould in two, but also carry the cores to 
 form the bolt holes. When the boss of a pulley or wheel is split 
 simply to relieve it of tension, filling-up pieces of metal are afterwards 
 introduced into the open spaces, and the whole banded together by the 
 shrinking on of rings of wrought iron over the ends of the bosses. 
 
 Splitting Plates. — Thin plates of wrought iron or of cast iron placed in 
 a foundry mould to effect the division or splitting of a wheel or pulley 
 in the act of casting. To prevent adhesion of the molten metal to 
 their faces, they are painted over with tar, or with loam and black wash. 
 
 Split Wheel. — Cog wheels are sometimes split for the same reason as 
 pulleys. They are usually moulded as one, but split by interposing a 
 thin plate of wrought or cast iron between the arms, by means of 
 which the casting is divided into two. The spUttiug takes place either 
 
340 DICTIONARY OF TERMS USED IN 
 
 tlirough the arms ; or through lugs oast on the tosses, and on the iuBido 
 of the rim. Sometimes the halves are moulded and oast separately, and 
 fitted together by planing. 
 
 Spoke Machine. — A maohine or lathe used for turning spokes on the copy- 
 ing principle. The lathe has two sets of centres, the wood to be turned 
 revolving between one set, and an iron templet or copy of the spoke re- 
 volving at the same speed between the other set. The cutters and a 
 roller are set in the same slide rest : and while the latter follows the 
 templet, being kept pressed agaiust it, the former follows, and removes 
 the wood, so that the latter is bound to become an exact counterpart 
 of the templet or copy. 
 
 Spokes. — The arms of the running wheels of locomotives and rolling stock. 
 
 Spoke Shave. — A tool used by pattern makers for the working of sweeps 
 in cases where great accuracy is not essential. 
 
 Sponge. — The ball or impure mass of iron newly reduced from the ore, in 
 readiness for shingling, rolling, or casting. 
 
 Sponge Cloth. — A coarse cotton towel woven expressly for the use of 
 machinists and engineers, to cleanse bright and working parts from 
 superfluous oil and dirt. Hence termed a wiper. These have largely 
 taken the place of waste (q..v.). 
 
 Spontaneous Combustion. — Some qualities of oils if left in saturation with 
 cotton fibre, cotton waste, &c., for a few hours become heated and 
 spontaneously ignite, hence a source of danger to factories which the 
 oil manufacturers strive to diminish by careful selection and prepara- 
 tions of their oUs. It is therefore a recommendation to an oil where, 
 other qualities being equal, it has a high flashing point (q.v.). 
 
 Spontaneous Ignition. — See Spontaneous Combustion. 
 
 Spoon Bit. — A bit of gouge-like section (see Shell Bit) used for boring 
 wood. Its cutting end is roughly cone or parabola-shaped, so that it 
 does not draw its core so effectually as a nose bit (q.v.). 
 
 Spoon Gouge. — See Bent Gouge. 
 
 Spoon Tools. — Moulders' tools rudely spoon-shaped, and used for smooth- 
 ing or sleeking moulds. 
 
 Spray. — A series of small or thin runners (q.v.) diverging from a common 
 centre or ingate (q.v.), each to convey its quota of metal to a separate 
 mould, the moulds all being in one box. Sprays are commonly em- 
 ployed in plate moulding when several patterns are moulded in conti- 
 guity to each other, and are used also for any light castings when it is 
 desired to obtain sufficient area of entry for the metal without the risk 
 of breaking the casting, which would result from the knocking off of a 
 single large runner. See Eidge. 
 
 Spray Tuyere. — A form of blast furnace tuyere, in which the interior of 
 the tubes of which it is composed is kept cool by a nujnber of jets or 
 sprays of cold water, directed from holes in supply pipes introduced 
 into the body of the tuyere, the waste water falling down the sides and 
 passing out through a waste pipe. 
 
 Sprig. — A cut brad. See Brad. 
 
 Sprigging. — ^Wlen narrow and inherently weak and otherwise unsup- 
 ported sections of sand occur in foundry moulds, it is necessary to sus- 
 tain them ; and the custom is to thrust long cut brads or sprigs into 
 the sand, reaching from the weak sections into the body of the mould. 
 This is termed sprigging or nailing. 
 
 Spring. — (1) A contrivance in which the elasticity due to the nature of 
 a substance or to its form is employed for the purpose of deadening 
 
MECHANICAL ENGINEERING. 341 
 
 shocks caused by the sudden contact of bodies, or for the exact adjust- 
 ment of strains or pressures. Examples of the former are found in 
 buffer springs (q.v.) and in the springs of railway axles, examples of the 
 latter in the spring balance (q.v.) and in the dial gauge (q-v-)- '^^^ 
 railway, or wagon spring, consists of a bundle of strips of curved 
 steel riveted together, the rivets having play allowed endways in slots 
 in the springs. The springs being curved upwards sustain the pres- 
 sure of loads suddenly applied to the truck or carriage to which they 
 are attached. (2) The term spring is also appUed to a wrought-iron 
 bend pipe, the amount of whose curve is exceedingly small. 
 
 Spring Balance. — The ordinary spring balance is used chiefly for safety 
 valves and weighing machines. The proportion for springs is that the 
 diameter of the internal portion of the coil should be four times that of 
 the thickness of the steel. 
 
 Spring Balance Valve. — A form of safety valve in which the lever is 
 attached to the end of a spring balance, instead of receiving a weight. 
 The graduations of the balance indicate the pressures. 
 
 Spring Bows, also called Bows, or Bow Compasses. — Small drawing com- 
 passes used for the most delicate and minute work, for which the ordi- 
 nary form would be unsuitable. The legs, which are short, are united 
 at their upper portions by a spring, which would maintain them wide 
 asunder but for a milled headed screw by means of which their dis- 
 tances apart are adjusted as required. A set of bows comprises three 
 instruments, points, pen, and pencil. 
 
 Spring Box. — A hollow box, containing a helical spring enclosing and 
 confining the spring sideways. The reaction of the latter against the 
 end of the box thrusts it against whatever is placed in line with and 
 in contact with it. Levers, pauls, &c., are thus actuated by springs 
 enclosed in spring boxes. 
 
 Spring Chaplet. — See Springer. 
 
 Spring Chuck. — A lathe chuck made of hard wood, generally box wood, 
 and used for holding light and delicate work which would be injured 
 or distorted by the application of much pressure. It is in shape like a 
 cup chuck, and the spring is imparted to it by running a number of 
 radial saw kerfs from the front downwards, slroilar to the shts in the 
 caps of telescopes, and by clamping the sections thus formed with a 
 ring sliding on the slightly tapered exterior diameter, so that the exact 
 amount of pressure of the chuck upon the contained object can be 
 regulated, and work can also be removed without using the hammer. 
 
 Spring Dividers. — Workmen's shop dividers, whose legs are united by a 
 strong arched spring which tends always to thrust them asunder, which 
 tendency is counteracted by a wing nut and screw pulling them to- 
 gether. The nut and screw furnishes the means of very minute adjust- 
 ment of the legs. For pitching out wheels and centres generally, and 
 for striking the smaller curves they are employed in preference to the 
 wing compasses. 
 
 Springer, or Spring Chaplet. — ^A simple chaplet made by bending a short 
 strip of hoop iron round to form three sides of a rectangle. It is used 
 chiefly for assisting to steady the sides of cores at a definite distance 
 from the sides of their moulds or from each other. 
 
 Spring Grinder. A grinder (q.v.) for emery which is made in two 
 portions attached to opposite ends of a metal rod bent round so as to 
 form a spring loop. Spring grinders are used for lapping out cylindrical 
 holes, as weB as the outsides of turned work. 
 
i42 DICTIONARY OF TERMS USED IN 
 
 Springings. — That part of an arch where the intradoa (q.T.) meets the 
 abutmenta (q.v.). 
 
 Spring Paul. — A paul which instead of pressing downwards by the action 
 of gravity simply, in which case it must be placed over its wheel, is 
 kept in contact with the wheel by means of a spring. The spring may 
 be either external or internal, in the former case consisting of a strip of 
 sheet metal fixed at one end and exerting pressure at the other, or a 
 coiled spring enclosed within the body of Qie paul which by its reaction 
 against one of three faces of a triangular pin enclosed in the paul 
 centre maintains the paul in either one of those three positions ; though 
 the resistance of the spring is not so great but that the paul can be 
 turned round by manual force. 
 
 Spring Piston. — An engine piston fitted with some form of spring ring, 
 as distinguished from a solid piston (q.v.). 
 
 Spring Pulley. — A wrought-iron pulley which is divided through the 
 boss, and also at a point in the rim in line with the joint in the boss, 
 in order to permit of its being opened or sprung apart sufficiently wide 
 to pass over a central portion of a shaft. It is built up of wrought 
 iron or steel. See also "Wrought-iron Pulley. 
 
 Spring Ring, — ^A metallic ring by which the piston and the cylinder 
 bore of an engine are rendered mutually close fittiog. It sometimes fits 
 between the top and bottom plates of the piston. Then it is turned in 
 the first place somewhat larger in diameter than that of the bore of the 
 cylinder, and slit or cut in a diagonal direction and sprung inwards by 
 main force, and so reduced to the size of the bore. When put in place 
 its elasticity maintains it closely fitting against the cylinder bore. 
 Spring rings are usually a little thicker on one side than on the 
 side opposite, in order to increase their elasticity. Eamsbottom 
 rings, usually of steel, are thinner than ordinary spring rings, and 
 either form a spiral of two or three coils, or two or three separate 
 cut rings are pressed into grooves turned in the periphery of a solid 
 piston. Spring rings are also forced outwards by set screws, wedge 
 blocks, &c. Spring rings are usually made in cast iron, but wrought 
 iron, steel, and gun-metal, are also employed. 
 
 Spring Safety Valve. — A spring balance valve (q.v.). 
 
 Spring Swage Tools. — Top and bottom swages (see Swage) which are 
 connected by two parallel handles uniting to form a spring at the end 
 farthest away from the swage blocks, roughly after the fashion of a pair 
 of sugar tongs. They are used for hand forging chiefly. 
 
 Spring Tool. — A turning tool used for taking a fuiishiog cut along a piece 
 of work already roughed down nearly to size. It is curved or arched 
 upwards and downwards just behind the cutting edge, and so possesses 
 a slight amount of elasticity or spring, which, though not conducive to 
 accuracy, produces a smooth and polished surface. 
 
 Sprocket. — See Sprocket Wleel. 
 
 Sprocket Wheel, or Pitch Chain Wheel. — A chain wheel which is provided 
 with projections upon its periphery, which are so pitched out that they 
 enter into the recesses of flat link or pitch chains, and either carry the 
 chain along as they revolve or are themselves carried round by tho 
 moving chain. This is a method for the conveyance of motive power 
 which has come largely into use of late years where power has to be 
 transmitted to a moderate distance. The chain is composed of flat linka 
 whose sides are formed of plates of wrought iron or steel, riveted to- 
 gether, the centres of the links coinciding in distance apart with the 
 
MECHANICAL ENGINEERING. 343 
 
 centres of the projections upon tlie sprocket wheels, but the projections 
 
 themselves fall into clear interspaces midway between the centres of 
 
 the pias which unite the links. 
 Spruce {Abies excelsa). — Akindof deal imported from Norway and Sweden. 
 
 See Pine Wood. It is used for packiig cases and the rougher class of 
 
 work generally. 
 Sprue, — A channel or channels running from an ingate to a foundry 
 
 mould. Also the smaU runners which are knocked off'after casting. 
 Spun Yarn. — A loosely spun soft and flexible hempen rope. It is used in 
 
 slinging bodies of light weight, for which its flexibOity and the ease 
 
 with which it is manipulated render it very useful. It is also used for 
 
 making steam joints, and for serving (q.v.). 
 Spur Gearing. — G-earing composed of combinations of spur wheels (ct.v.). 
 Spur Wheel. — ^A toothed wheel whose teeth are on the outer diameter, and 
 
 at right angles with the wheel face. 
 Square. — (1) A rectangle (q.v.) haviag four equal sides whose angles are 
 
 right angles. (2) A tool used for checking the accuracy of ends and 
 
 edges of timber or metal. See Set Square, Ity Square. (3) The square 
 
 of a number is the product of the number multiplied by itseU. 
 Sciuare-bar Iron. — Malleable iron of rectangular form, rolled to various 
 
 sections in roUs, and used in smiths' and platers' work generally. 
 Square-body Valve. — ^A pump-valve whose casing is of rectangular 
 
 shape. 
 Square Centre. — A lathe centre placed in the poppet mandrel, having its 
 
 end pyramidal instead of conical in form. It is u^ed for cutting in the 
 
 centres of work revolving in the lathe, the work being pressed against 
 
 the sharp edges of the centre. 
 Square-corner Smoothers. — Moulders' tools having two faces at right 
 
 angles with each other taken in cross section, and a thumb bit for the 
 
 finger and thumb in the internal angle. Used for sleeking the angular 
 
 portions of moulds. Both faces may be straight, longitudinally, or one 
 
 may be curved in outline, the other being straight. 
 Squared. — Work is said to be squared when the faces referred to are 
 
 brought to the exact angle of 90° with each other. 
 Square-edged Angles. — See Angle Iron. 
 Square File. — A file square in cross section, commonly tapered in length, 
 
 sometimes cut on all four sides, sometimes haviag one safe edge. 
 
 Used for cottarways and keyways, and for rectangular holes generally. 
 Square-hole Chuck. — A lathe chuck roughly similar to a cup chuck, but 
 
 having a square tapered hole instead, in its front end. It is made in 
 
 wood or in metal, and used for chucking rough pieces of wood or metal. 
 Square Inch. — See Inch. 
 Square Joint, — The joint plates of a rule which pass straight across the 
 
 wood instead of being arched out. See Arch Joint. 
 Square-nose Tool. — An iron turner's finishing tool. So called because its 
 
 cutting edge stands at right angles with the edges of the shank, and is 
 
 a straight line ; difBering in this from the round-nose tool, which it 
 
 resembles in other respects. 
 Square Packing. — G-asket (q.v.) made into a square sectional form. Used 
 
 for water joints. 
 Square Boot. — The square root of a number is the number which, if mul- 
 
 tiphed by itself, would have the square (q.v.) for its product. 
 Square-threaded Screw, — A screw the section of whose threads is rect- 
 angular in form. Its pitch is about twice that of a triangular thread, 
 
344 DICTIONARy OP TERMS USEJD IN 
 
 and its depth \% of the pitoh. Square-threaded screws are used where 
 accurate movement and good -wearing surface are required, as in lathes 
 and ia engineers' machines generally. Often the points and roots are 
 rounded and hollowed to a sUght amount. Sometimes also the flanis, 
 instead of being exactly square, slope at a slight angle. 
 
 Square Tile. — A draughtsman's rectangular palette, having three or four 
 slopes or divisions for holding colour. 
 
 Square Trowel. — ^A moulder's trowel whose outline is rectangular. 
 
 Square Way. — The water passage through the body of an ordinary cock 
 is called a square or " common " way, to distinguish it from fuU- water 
 way (q.v.). 
 
 Squaring TTp. — The process of bringing the faces of work into a squared 
 (q.v.) position with reference to one another, with planes, files, or 
 machine cutters ; or the setting of faces already squared, perpendicular 
 in relation to some other section of the work to which they belong, or 
 to the face of a surface plate or marHng-off table or bench, in readinesa 
 for the scribing off of Imes and distances. 
 
 Squeezer. — (1) A machine used for the purpose of reducing a ball of 
 puddled iron to a solid hom.ogeneous mass, by the expulsion of the slag 
 and cinder preparatory to rolling it into bars. The steam hammer (q.v.) 
 is often used in preference to the squeezer. Squeezers are reciprocal, or 
 rotational. See Alligator Squeezer, Eotary Squeezer. (2) Straightening 
 Machines (q.v.) are also called squeezers, or squeezing machines. 
 
 Squeezing Machine. — Any machine by which bars or rails are bent or 
 straightened. There are several forms, but the essential principle of 
 their construction is that of a ram or pressor actuated by a screw driven 
 by a large hand wheel, or by a cam movement driven by power and 
 pressing against the bar, whose pressure is taken by two points of 
 support behind it. Squeezing machines form a portion of the equip- 
 ment of all boiler shops and of most smithies. 
 
 Stable Equilibrium. — This results when the centre of gravity of a body 
 which is in actual equilibrium lies in its lowest position. 
 
 Stack. — ^A chimney, though usually applied to a structure built of 
 masonry. The chimney of an engine boiler is made long in stationary 
 engines for the production of draught, its shortness in locomotives and 
 portables being compensated for by the utilisation of the action of the 
 blast. 
 
 Stacking Crane. — ^A fixed or portable crane used for stacking pOes of 
 goods or material at wharves or in quarries, and at sheds and sidings 
 of railway stations. 
 
 Stake. — (1) A long tapering spike or bar of rectangular section, of wood 
 or iron, used in foundry work. "When a pattern is bedded in (See 
 Bedding In) and covered with a top part (q.v.) only, the latter is 
 guided into its proper position by several stakes driven into the sand 
 of the foundry floor in immediate proximity to the lugs which project 
 from the sides of the box. Being set for ramming, and reset after 
 lifting, cleaning and coring, by means of the same stakes, the joints 
 in the mould will correspond. (2) Small anvils having faces variously 
 shaped and used by coppersmiths for bending and raising (q.v.) work 
 are also called stakes. 
 
 Staking On. — A term sometimes applied to the rough method of fitting or 
 hanging (q.v.) of wheels on shafts by the aid of keys alone without 
 boring or other fitting. The eye of the wheel is in such cases larger 
 than the shaft itself, and several keyways are cut in the eye, fiia 
 
MECHANICAL ENGINEERING. 345 
 
 nuin'ber of keys employed supplying the means of adjustment. It is 
 common in millwriglits' "work. 
 
 Stamp. — A die for the moulding of sheet metal into desired form by means 
 of screw or hydraulic pressure. Boiler crowns and repetition flanged 
 work is done with stamps or dies. So also is much smith's work. 
 
 Stamping, or Pressing. — (1) The production of forged work by means of 
 dies pressed together either under the hammer or under the hydraulio 
 forging press. (2) The term is also applied to one of the processes in 
 the preparation of tin ores. Tin ores are stamped in a stamp chest, and 
 being reduced to powder are carried away by a stream of water into 
 reservoirs where the heavier ore settles down by its greater sp. gr., the 
 sand, &o., being carried on by the stream. The deposits of ore are 
 termed slimes (q..v.). 
 
 Stamps. — Letters and figures cut in relief on the ends of short lengths of 
 steel rod, and used for stamping initials and words upon patterns and 
 machine parts, in the former case with a view to ready recognition, in 
 the latter to indicate the contiguous parts in order to facilitate final 
 re-erection. 
 
 Stanchion. — K. Hght column of oast or wrought iron used for the support 
 of a floor, or to carry hand railing and other similar light purposes. 
 
 Standard. — (I) A vertical support used for machinery, being usually a 
 stout cast-iron structure fitted with bearings, feet, and strengthening 
 ribs or fillets. Lathes, engines, pumps are built on or bolted to stan- 
 dards or upright frames. (2) Anything of fixed and exact dimensions 
 which is used as a test or basis of final reference and appeal in a work- 
 shop. Standard rules, gauges, taps, &c., are thus preserved in work- 
 shops. (3) A wholesale unit of measurement for timber. A standard 
 of pine timber is equal to 720 ft. of H in. X 3 in. cross section. Also 
 the standard sizes of deals, as St. Petersburg, Quebec, &c. 
 
 Standard Eod, or Measuring Eod. — A rod of well-seasoned yellow pine 
 used as a basis and reference for accurate measurement in a workshop. 
 Such rods are usually made from 5 to 10 ft. long, the section of the 
 wood being about 2 in. X 2 in. Each 12-in. division is marked on a 
 brass inlaid plate. The end foot is whoUy marked on brass, accurately 
 divided out into fractional parts as required. A standard rod is either 
 precisely the length, if required for butt measurement (q.v.), in which 
 case its ends are protected with steel or brass. Or the length of the 
 rod is in excess, and the requisite length is marked on brass plates let 
 in, from which measurement is taken with trammels. Standard rods 
 are made with metre divisions also. 
 
 Standard Enle. — ^A rule containing the divisions into ordinary inches and 
 parts. Used to distinguish it from the contraction rule (q.v.). 
 
 Standing Vice See TaUVice. 
 
 Stand Pipe. — (1) A safety valve seating (q.v.). (2) The pipe which is 
 screwed on the top of a hydrant. 
 
 Staple, or Dog. — A tool used for clamping timber joints temporarily to- 
 gether while being glued or otherwise fastened. Its form is that of 
 three sides of a rectangle, the free ends being pointed. It is made of 
 wrought iron or steel rod. 
 
 Staple Vice. — The ordinary form of upright or tail vice, which is stapled 
 to a bench and whose leg is stepped into a block on the floor. 
 
 Starting Cylinder. — The cylinder of a starting engine (q.v.). 
 
 Starting Engine. — The small engine used for starting large marine 
 engines. 
 
346 DICTIONARY OF TERMS USED IN 
 
 Starting Gear, — Any arrangement used for starting engines or macWnea. 
 It consists variously of starting valves and levers or wlieels, barring 
 engines, linTr motions, striking gears, fast and loose pulleys, &c., noted 
 under tlieir headings. 
 
 Starting Lever.' — The lever attached to a starting valve (q.v.) when the 
 latter is of the sliding type. 
 
 Starting of Machines. — The strains put upon machines by abrupt starting 
 are frequently so great as to become a source of injury to them. 
 Sudden starting is quite analogous to the sudden stopping of a mass in 
 rapid motion, and produces jars, jerks, shpping of belts, and surging 
 of parts. A machine therefore, especially when of a heavy character, 
 should be allowed time to gain momentum by having its starting gear 
 put slowly and easily into motion. 
 
 Starting Valve. — The valve employed for admitting steam from the boiler 
 or pipes connected therewith, into the cylinder or cylinders of a steam 
 engine. The valve may be of the shding disc type moved by a lever, 
 or a litt or puppet globe valve lifted by a screw, or a plug valve turned 
 with a wheel. 
 
 Starts. — ^Those portions of the buckets (q.v.) of a water wheel which 
 come next the sole boards and start therefrom. 
 
 Star Wheel. — ^A small wheel furnished with large projecting radial teeth, 
 and attached to the end of a feed screw. A paiil engages with the star 
 wheel once during each revolution, and so feeds the screw round to a 
 definite amount at each passing of the paul. 
 
 Star-wheel Motion. — A feed motion employed for surfacing in lathes 
 and boring machines, through the agency of a star wheel (q.v.) and 
 suitable adjuncts. The cutting tool is carried in a slide moving in a 
 plate and actuated by the feed screw attached to the star wheel. The 
 star wheel is moved one tooth at each revolution of the boring bar by 
 which it is carried, through the medium of a pin attached to any con- 
 venient position on the bed, or rest, or head of the machine. When 
 the star wheel is turned through the arc represented by the passing of 
 a tooth, the screw being also carried with it, the slide in which the 
 latter moves, and the cutting tool also which is fixed in the slide, must 
 move to the precise amount which is regulated by the pitch of the 
 wheel teeth, and by that of the screw thread. 
 
 Statical Fatigue. — The fatigue of materials (q.v.), which results either 
 from a purely dead load (q.v.) or from a variable load (q.v.). 
 
 Statical Load. — A dead load (q.v.). 
 
 Statical Moments The moments of forces which produce stresses with- 
 out causing actual motion. 
 
 Statics. — The study of those forces which act upon structures without 
 producing sensible motion, but which induce strains (q.v.) and stresses 
 (q.v.) instead. 
 
 Stationary Engine.— An engine fixed on foundations. The reverse of a 
 portable engine (q.v.). 
 
 Stationary Hand-wheel Feed. — A term applied to the feed of those drill- 
 ing machines in which the feed screw is elevated and depressed by the 
 revolution of a hand wheel, which is turned in a fixed horizontal plane. 
 The interior of the hand wheel boss is cut to take the screw thread, 
 and so forms its nut. The wheel is prevented from rising and falliag 
 by a turned collar embracing its boss. 
 
 Stationary Link. — A slot Unk (q.v.) which is not lifted or lowered for the 
 purpose of reversing, but in which the pin or die block alone is moved. 
 
MECHANICAL ENGINEERING. 5-47 
 
 The Hnk in this case is curved in a direction away from the crank 
 shaft. 
 
 Staunch. — Riveted joints are rendered staunch or -water-tight by canlking 
 with a drift (q.v.). Plates bolted together are rendered staunch by 
 caulking with iron borings and sal-ammoniac. 
 
 Stave. — The projecting end or porter by which a crank shaft is held 
 during the process of its building up and forgiag. It is cut off when 
 the forging is complete. 
 
 Stay, — (1) A bar which stays or steadies a structure. (2) A boiler stay 
 (q.v.). (3) Also applied to the bars of moulding boxes. See Bar. 
 
 Stay Bars. — Bars which stiffen the roofs of the inside fire boxes of loco- 
 motives. They rest edgeways at intervals across the roof, touching 
 however, only through the intervention of washers at the two sections 
 through which the bolts pass, in order to permit of the circulation of 
 the water underneath them. See Girder Stays. 
 
 Stay Bolt. — Any bolt which stays or stiffens an otherwise intrinsically 
 weak plate. The end flat plates of the fire boxes of locomotives are 
 furnished with stay bolts connecting the two outer and inner shells. See 
 also Boiler Stays. The plates of built-up cast-iron water tanks are 
 held against the outward pressure of the water by stay bolts reaching 
 from side to side. Side frames of pumps, crab winches, &c., are also 
 connected with stay bolts. 
 
 Stayed Link Chain. — See Studded Chain. 
 
 Staying, — The affording of support to structures inherently weak, by 
 means of stays of various kinds, as most suitable to the forms of the 
 structures, and the pressures or strains to which they are subjected. 
 Plates are stayed with ribs, chains are stayed with studs, boilers with 
 various stays, tanks with tie rods, gantries and roofs with trusses ; the 
 arched, dished, and other forms given to many structures are with a 
 view to proper staying. 
 
 Stay Tap. — A specially long tap, being from 15 to 20 in. in length, though 
 sometimes reaching to 2 or 3 ft. Used for screwing the holeS which 
 receive the stay rods in the ends of locomotive and marine boilers. Its 
 lower end is not screwed, but turned smooth, in order to maintain the 
 tap truly concentric with the holes in both inner and outer shells. 
 
 Stay Tubes. — The smoke tubes of boilers, which are also made to stay 
 the boiler ends by being screwed for the reception of back nuts within 
 and without the end plates. 
 
 Steady. — ^A piece of mechanism used by wood and iron turners for the 
 purpose of preventing the wobbling of long cylindrical pieces of work 
 which are being revolved in the lathe. A portion of the cylindrical 
 piece is turned first of aU and enclosed in adjustable bearings in the 
 steady, after which the remaining portion is turned with ease. The 
 steady is fixed to the lathe bed by wedges or screws, or else travelled 
 with the rest. Wood turners use a steady of wood, those of iron turners 
 are constructed of iron. Long hght shafts are also steadied by a cylin- 
 drical body or ring encircling them, set with screws and running in the 
 bearings of a vertical steady, the latter being often simply a bit of 
 square iron bar bent to the outline of an inverted vee over the turned 
 portion of the cylinder, and clamped to an angle plate bolted down to 
 the lathe bed. That form of steady which is bolted to the saddle of a 
 slide rest is also called a following rest, or following steady, or back 
 steady rest (q.v.), because it follows after or travels along with the 
 work over the newly turned portions. 
 
348 DICTIONARY OF TERMS USED IN 
 
 Steadying Boiler, — A small roller employed in planing maoliines for wood, 
 its function teing to press the plank or board firmly down upon the table. 
 Its position is immediately in front of the revolving cutter block. 
 
 Steady Load. — See Dead Load. 
 
 Steady Pins. — (1) The guide or set pins in the lugs of a moulding box 
 by which the box parts are made to coincide. Dowels are sometimes 
 termed steady pins. (2) A stud, pin, or short sunk feather, employed 
 for the purpose of preventing a wheel or pulley from turning round 
 upon its spindle, is also called a steady pin. The pin is made to fit a. 
 corresponding recess in the wheel or pulley. 
 
 Steam. — "Water in the vaporous, or in the gaseous condition. Vapour of 
 water is given off at all temperatures, provided the vapour already 
 existing in the atmosphere is not of the same density. The difference 
 between vaporous and gaseous steam is, that in the former the particles 
 of water are in a state of mechanical suspension, and therefore visible, 
 while the latter is in the condition of a true gas, or invisible, and its 
 pressure and volume are strictly in inverse relation to each other. (See 
 Boyle and Marriott, Law of.) Saturated steam is also invisible, though 
 not absolutely in the true gaseous condition. It is usual to designate 
 that as steam only, which is evaporated from the surface of water, at 
 and above the boiling point (q.v.). Steam owes its value as a motive 
 agency to its elastic force (q.v.) and as a drying or heating agent 
 to its latent heat (q.v.). The pressure and density of steam alike 
 rise with the temperature, and conversely the temperature rises with 
 the pressure and density. But there is only one pressure and density 
 for any given temperature ; hence steam, generated in contact with 
 water ia a closed vessel, is at its maximtun density and pressure 
 corresponding with that temperature, and is then at its point of 
 saturation. See Saturated Steam. If, however, the steam so gene- 
 rated be made to receive increments of heat in a separate vessel away 
 from contact with water, it becomes superheated (see Superheated 
 Steam), and approaches then to the condition of a perfect gas. A cubic 
 inch of water vaporised at the boiling point corresponding with the 
 ordinary atmospheric pressure is expanded 1,642 times. Steam of any 
 pressure is capable of expansion on a reduction of pressure by virtue of 
 its elastic force, and hence its value in the economy of engines worked 
 expansively. See Compound Engine, Absolute Pressure, High, and 
 Low Pressure Steam. 
 
 Steam Boiler. — See Boiler. 
 
 Steam Brake A railway brake in which the pressure of steam is made 
 
 to actuate the brake mechanism. Such a brake is suitable for engines 
 and tenders, biit not for trains, owing to the condensation of the steam. 
 
 Steam Capstan. — A capstan (q.v.) worked by steam power, actuating a 
 small iudepeudent pair of engines, instead of by hand. 
 
 Steam Case. — An old term for steam jacket (q.v.). 
 
 Steam Chamber. — ^Any reservoir or store for steam, as the steam room 
 (q.v.) a superheating chamber, or steam dome (q.v.). 
 
 Steam Chest. — (1) The rectangular case or box attached to the side of an 
 engine cylinder, and enclosing the slide valve (q.v.) together with a 
 portion of the valve rod. Strips cast upon its edges afford guidance to 
 the edges of the valve, and in large engines a facing or ring cast within 
 its back face maintains the valve in eqmlibriuni. See Equilibrium 
 Valve. Steam chests are almost invariably oast separately from their 
 cylinders and bolted thereto, for convenience of fitting up. In the 
 
MECHANICAL ENGINEERING. 349 
 
 larger chests the back is also made distinct as a separate cover, and 
 bolted to a flange on the actual chest, for convenience of examination of 
 the valve. (2) Also applied to the steam domes of locomotive and 
 marine engines, the object of which is to dry and superheat the steam 
 away from immediate contact with the water. 
 
 Steam Coal, — Coal used in the furnaces of steam boilers. The anthracitio 
 coals (q.v.) are the best steam coals ; being free burning, non-caMng, 
 almost smokeless, and producing comparatively little ash, they are 
 much used for sea-going vessels. But the eemi-bituminous coals (See 
 Bituminous Coal) are those chiefly used as steam coals. They are rich 
 in hydrocarbons, bum freely, and emit much smoke, but there is much 
 variation in their composition and qualities. 
 
 Steam Cock, — (1) The upper of the two try cocks (q.v.) of a steam boiler, 
 which when open should always pass steam, never water, since that 
 would show too contracted steam room. (2) Generally, any cock by 
 which admission of steam is regulated. 
 
 Steam Coil. — A coil of pipes through which steam is circulated for heating 
 purposes. 
 
 Steam Comer. — The left-hand comer of an indicator diagram, or the 
 comer which unites the exhaust with the lead Une. It is not properly 
 a comer, but becomes a small radius. 
 
 Steam Crane. — A crane to which the motive power is supplied by a steam 
 engine, or a pair of engines forming a portion of the crane, to distinguish 
 it from a crane worked by hand power only. Steam is apphed to both 
 fixed and portable cranes. The engines are usually of the vertical type, 
 and attached to the side frames. See also Horizontal Crane. 
 
 Steam Cylinder. — ThecyUnder (q.v.) of a steam engine (q.v.). 
 
 Steam Dome. — The dome-shaped structure upon a locomotive boiler whence 
 the supply steam is taken for the cylinders. The steam is partially 
 superheated and is therefore hotter and drier there than it is elsewhere, 
 hence the tendency to priming (q.v.) in the boiler is diminished. 
 
 Steam Donkey Pump. — A small pump used for supplying steam boilers 
 with feed water. The piston rod of the steam cylinder and the ram of 
 the pump are in line, and the connecting rod is usually of the bow or 
 triangular form. See Bow Connecting Eod. A fly wheel carries over 
 the dead centres (q.v.). The pump and cylinder are attached to a base 
 plate which is bolted to the steam boiler or other convenient support. 
 There are numerous modifications of this form of pump. 
 
 Steam Edges. — The outer edges of a slide valve by which the entering 
 steam is cut off. 
 
 Steam Engine. — A prime mover which is actuated by the elastic force of 
 steam urging a piston in a closed cylindrical vessel. See details under 
 their headings. 
 
 Steam Engine Indicator. — See Indicator. 
 
 Steam Gauge. — See Pressure Gauge. 
 
 Steam Hammer. — A hammer moving vertically in guides and lifted by the 
 force of steam, actuating the piston of an engine cylinder placed over- 
 head on an A framing. The tup or moving mass and the hammer 
 attached to the same, are in some hammers allowed to descend by the 
 force due to gravity alone, in others the steam is introduced above the 
 piston also to accelerate their descent. The valves for the admission 
 and out off of steam are under the control of a lever held by the atten- 
 dant. The vibration of the blows is received by a massive anvil block 
 (q.v.) embedded in the foundations. The weight of a steam hammer is 
 
3S0 DICTIONARY OF TERMS USED IN 
 
 expressed by the weiglit of the piston rod and hammer-Iiead ortnp. la 
 a five-ton hammer, for example, five tons would be the total weight of 
 these parts. 
 
 Steam Hammer Framing. — A term applied to the framing of ordinary 
 inverted cylinder marine engines, on account of its resemblance to that 
 of the steam hammer. 
 
 Steam Hammer Type. — A term applied to inverted cylinder marine en- 
 gines. See Steam Hammer Framing. 
 
 Steaming. — The firing and getting up or generating of steam in an 
 engine boiler, in preparation for testing or working. 
 
 Steam Jacket. — An open casing or envelope formed around a steam 
 cylinder for the purpose of maintaining the temperature of the cylinder 
 as high as that of the entering steam. It is formed by fitting an iron 
 bush or lining ring within the bore of the main casting, which contains 
 the casing, iie piston moving within the bush. The liner, as it is 
 commonly called, fits only for a short distance in from the ends, 
 the steam space being formed by the intermediate recessed portion. 
 When the variations in the temperature of the entering and exhaust 
 steam are not excessive, the steam jacket is productive of economical 
 working as preventing initial, or subsequent condensation and re- 
 evaporation. 
 
 Steam Jet. — (1) A jet or blast of steam introduced either into the ash- 
 pit or into the body of the fuel in a gas producer, to effect an economy 
 of fuel and an increase in the volume of the gas produced. This it 
 effects by becoming decomposed in contact vsdth the heated fuel, the 
 liberated oxygen then combining with the carbon to form CO, and the 
 hydrogen mingling with the producer gas. (2) Also the jet of steam 
 sent into the chimney of a locomotive or portable engine boiler through 
 the blast pipe (q.v.) for the purpose of increasing the draught. 
 
 Steam Joints. — The joints made between the various flanges of steam 
 pipes and steam connections, as cylinder covers, steam chests, stuffing 
 boxes, &c. Tarn, copper wire, india-rubber, lead, millboard, and 
 other substances are used in the making of steam joints. 
 
 Steam Lap. — The extension of the faces of a shde valve beyond the precise 
 length which is necessary to cut off live steam exactly at the termina- 
 tion of the stroke of the piston. See Lap. Used in contradistinction 
 to Exhaust Lap (q.v.). 
 
 Steam Lift. — A lift (q.v.) actuated by a small steam engine. 
 
 Steam Line. — The upper straight or approximately straight portion of 
 an indicator diagram, which records the mode of entrance of the 
 steam into an engine cylinder. 
 
 Steam Lubrication. — Engine pistons and the bores of cylinders require 
 lubrication to prevent abrasion of the working surfaces. Saturated 
 steam (q. v. ) is in some degree its own lubricant, owing to the presence 
 of moisture held in suspension, but superheated steam (q.v.)' owing to 
 the absence of water, abrades and scores the surfaces of cylinders, 
 pistons, valves, and valve faces very rapidly. But all steam requires 
 some lubrication, hence it is the custom to feed a constant supply of 
 cylinder oil in with the steam, through the steam chest or cylinder ; this 
 being diffused among the steam, and coming in contact with the wear- 
 ing surfaces, prevents the injury due to friction. 
 
 Steam Lubricator. — A displacement lubricator (q.v.). A certain amount 
 of steam being allowed to flow into the closed lubricator, containing 
 oil, is condensed and floats the oil to the surface, whence it passes down 
 
MECHANICAL ENGINEERING. 351 
 
 through an overflow pipe to the parts requiring luhrication. See 
 Impermeator. 
 
 Steam Nozzle. — The discharging opening of a steam blast pipe, narrowed 
 to increase the force of the jet. Applied to the blast pipes of steam 
 engines, and to the pipes by which steam is discharged into chimneys 
 and furnaces, to increase the rate of combustion. 
 
 8team Passages. — The steam and exhaust ports of an engine cylinder 
 through which the steam obtains ingress and egress. They should 
 bear a constant proportion to the size of the cylinder and the rate of 
 travel of the piston, together with ample allowance for loss by friction 
 due to bendings in the pipes, their size being such that there should 
 not be any material difference in the pressure of steam in the cylinder 
 and in the passages. An excess of size should always be given them. 
 
 Steam Pipes. — The pipes which form the connections between a steam 
 boiler and an engine, or, generally, any pipes through which steam 
 circulates for heating or other purposes. Steam pipes are made of cast 
 iron, wrought iron, or copper. Cast-iron pipes are used for some large 
 stationary engines and for heating apparatus, but their use necessi- 
 tates the introduction of expansion joints. See Expansion Joint. Pipes 
 of wrought iron are used for small engines, and when no very great 
 length is required there is no necessity for the introduction of expan- 
 sion Joints. Copper pipes are used for marine and locomotive engines 
 and for the best engines in other classes, and being usually subject to 
 several bendings, expansion takes place without damage to the pipes or 
 to their joints. 
 
 Steam Ports. — The passages through which the steam gains ingress to an 
 engine cylinder. They enter the side of the cylinder close to the end. 
 In small engines they take a curved course to the valve face at the 
 centre of the cylinder ; in large engines and in engines of the Corliss 
 type they pass out direct. 
 
 Steam Pressure. — The pressure of steam is equivalent to its elastic force, 
 and in the superheated state is in an inverse ratio to its volume. The 
 temperature increases more rapidly than the pressure, hence the 
 economy of using steam at high pressures. See Boiler Pressure, Ex- 
 pansive Working. 
 
 Steam Pump. — ^An ordinary force pump driven by a steam engine. Steam 
 pumps are usually direct acting (q.v.), but are made in a very great 
 variety of forms. 
 
 Steam Eeversing Cylinder. — A smaU steam cylinder whose function is 
 the reversal of the slot IitiIt on a large marine engine, for ahead or 
 astern movements. See Oil Cylinder. 
 
 Steam Boom. — TTie area included between the level of high water and the 
 crown of a boiler, and which is occupied by the steam. 
 
 Steam Thermometer. — A thermometer graduated for high pressures and 
 attached to a steam pipe. 
 
 Steam Tight. — Elanges, moving rods, pistons, and other jointed portions 
 are rendered steam tight by various modes of packing. See Paeking, 
 Steam Joints, &c. 
 
 Steam Trap. — A piece of mechanism automatic in its action, by means of 
 which the water of condensation which accumulates in steam pipes is 
 periodicaUy discharged. There are several forms, but the commonest 
 is that in which the water on rising to a certain height lifts a float, and 
 through its movement opens an escape or relief valve, the float falling 
 again immediately that the trap is emptied. 
 
JS2 DICTIONARY OF TERMS USED IN 
 
 Steam Valve. — A slide valve, or any valve by means of wHch steam 
 supply is regulated, whether of the sliding or lifting types. A start- 
 ing valve fq.v.) or a stop valve (q.v.). 
 
 Steam Whistle. — Essentially a keen edge, annular or otherwise, against 
 which a jet of steam is projected at pleasure. Various names are given 
 to the different whistles according to their shape and tone, as round 
 barrel, long barrel, plug, hummer, fog, octave, treble, &o. 
 
 Steam Winch. — A wiach (q.v.) driven by steam power, the engines being 
 af&xed to the outsides of the side frames which carry the gearing. The 
 cylinders are usually placed at an angle in order to give as great a 
 length of connecting rod as possible. 
 
 Steel. — A term of wide apphcation, embracing cast, shear, Bessemer, and 
 Siemens's steels, in their various qualities. It is essentially a compound 
 of iron with carbon, upon whose proportions mainly depend the hard- 
 ness or softness of the steel. The mildest steel differs little from 
 wrought iron in respect to the amount of carbon present, while the 
 hardest contains somewhat more. The properties which render steel 
 so valuable are its great tensile strength, cast steel having a tenacity of 
 iifty tons per square inch, and its capacity for receiving any degree of 
 temper required. Details are furnished under special headings. 
 
 Steel Castings. — These have largely taken the place of cast iron in late 
 years, for purposes where strength and durability are required. Steel 
 castings are made both from crucible oast steel (q.v.) and from steel 
 made by the open hearth (q.v) processes, the latter being the more recent 
 of adoption, and also the cheaper. The castings are made from patterns 
 as in ordinary moulding, but the sands are more sUicious and more re- 
 fractory, consisting of mixtures of ganister, and the moulds are always 
 dried. Steel castings require annealing, and are seldom so clean and 
 smooth as those made in cast iron owing to the high temperature at 
 which the metal is poured. They are also more subject to blow holes, 
 but are nevertheless to be preferred owing to their greater strength. 
 
 Steel Facing. — Refers to the practice of covering, or facing the working 
 parts of many percussive and cutting tools, whose bodies are made of 
 iron, with steel, the metals being made to adhere when at a welding 
 heat. Smiths' anvils, tongs, &o., hammers in general, plane irons, the 
 chisels, axes, and a multitude of similar tools are steel faced. 
 
 Steeling. — The facing of wrought-iron work vrith a thin layer of steel, in 
 order to impart durability, or cutting power thereto. See Steel Facing. 
 
 Steel Pulleys. — See "Wrought-iron Pulleys. 
 
 Steel Press. — A hydraulic press, used for compressing fluid steel into 
 ingots. 
 
 Steel Ropes. — See "Wire Kopes. 
 
 Steel Bnle. — Engineers' rules are made of steel, usually being a foot long, 
 and containing numerous subdivisions of the inch, ranging from eighths 
 to sixty-fourths frequently ; also English inches are upon one side and 
 milliinetres on the other. Sometimes various drawing scales are also 
 included. Special rules are made triangular, and square in cross 
 section. 
 
 Steel Square. — An ordinary try square (q.v.) used by a fitter or machinist. 
 These are usually of small size, the smallest being carried in the waist- 
 coat pocket, some being no longer than 1^ in. in the length of blade. 
 The blades are narrow so that they may pass through cottarways and 
 key ways, and similar contracted spaces. Often they contain sub* 
 divisions of the inch on the blade or stock. 
 
MnCBANtCAL ENGINEERING. 353 
 
 Steel Tyre.— See Tyre. 
 
 Steel Wire. — This is used in the manufacture of wire ropes. Its tenacity 
 exceeds that of steel prepared in any other form and is developed in 
 the act of drawing, since subsequent annealing weakens it. Thus 
 steel wire unannealed was found to have a tensile strength of 54-07 
 tons per inch, while when annealed it gave 33'32 tons only. Some 
 steel wires have a tensile resistance of 90 tons per iach. See "Wire 
 Ropes. 
 
 Steel Yard, or Soman Balance. — A lever ia which the action of two 
 unequal parallel forces ranged in positions inversely to their weights on 
 opposite sides of a third force (the point of support) is taken advantage 
 of as a means of weighing objects. 
 
 Steely Iron. — Cast iron which contains a low percentage of carbon. 
 
 Steeple Engine. — A form of marine engine now become antiquated, so 
 called because the connecting rod passed up above the deck and was 
 guided in massive A standards rising to a considerable height. 
 
 Steeples. — Sometimes applied to moulder's nails. 
 
 Steering. — The same as slewing (q.v.). 
 
 Steering Bracket. — A slewing bracket (q. v.) . 
 
 Steering Gear. — Slewing gear (q.v.), or the gear whether hand or steam, 
 employed for steering a ship. 
 
 Stemming. — See Lead Joiat. 
 
 Stencilling. — The marking letters and figures on drawings, and on 
 portions of wood and metal work for identification, by means of stencil 
 plates (q.v.). Small-sized metal and pattern work is often marked with 
 stamps (q.v.) in preference to stencilling, as being more permanent. 
 
 Stencil Plates. — Metallic plates of copper or zinc pierced with the shapes 
 of letters or figures, narrow bridges of metal only being left to main- 
 tain the continuity of the plates. The ink or paint is used thick and 
 rubbed on with a stumpy brush, the plate being held closely down to 
 prevent the running in of the colour beyond the edges. 
 
 Step. — (1) See Footstep. (2) The distance from either one of the belt 
 faces on a speed pulley to the belt face of its contiguous step measured 
 radially. Hence twice the amount of step will give the exact difference 
 in the diameters of the contiguous speeds. Also termed the fall, or the 
 amount of fall. 
 
 Step Bearing. — See Footstep. 
 
 Step Gauge. — A male gauge turned to several standard diameters. 
 
 Stepped Gearing, or Hooke's Gearing. — Gearing in which the teeth are 
 arranged as though cut into successive slices in their breadth, and these 
 slices placed at a definite and constant distance behind one another in 
 their plane of rotation. The arrangement is made to obtain continuous 
 bearing contact between wheels gearing with one another, and conse- 
 quent steady motion. The principle has been developed more fuHy in 
 helical gear (q.v.). 
 
 Stepped PuUeys, — See Speed Pulleys, Step. 
 
 Stepped Back. — ^A rack in which the teeth are stepped. See Stepped 
 Gearing. Used chiefly for the tables of planing machines. 
 
 Stepping In. — When the lower end of a shaft or spindle is turned or 
 formed into a step or shouldered shank to fit into a hole in a base 
 plate or other support, it is said to be stepped in, and the process of 
 fitting is termed stepping in. 
 
 Stepping Eonnd. — Thia is often used to signify the dividing round of the 
 rim of a toothed wheel pattern into equal parts, according to the number 
 
 A A 
 
354 DICTIONARY OF TERMS USED IN 
 
 of teeth, required. It is done witli spring dividers by a process of trial 
 and error. 
 
 Stern Tube. — ^The tube whicli carries the bearings of a propeller shaft. 
 
 Sterro Metal. — An alloy of copper, zinc, and tin with wrought iron. 
 
 Sticking of Valves. — The sticking of safety valves is a fruitful cause of 
 boiler explosions, and is due to several causes. Too tight a fit in the 
 first place, bendiug of the spindle, corrosion, bad design, are the chief 
 causes of sticking. 
 
 StifFeners. — See Web Stifieners. 
 
 Stirrup. — A strap or loop which supports a rod or spindle, or any similar 
 object, in a vertical direction. The spindles of some lever drilling 
 machines are lifted by means of stirrups which embrace the tops of the 
 spindles. 
 
 Stock. — The mass of hard melted caked coal which surrounds the hollow 
 incandescent portion of a smith's fire, and within which his heat is 
 localised at pleasure, and from which the fire is fed. 
 
 Stock Rail. — The fixed rail at a point in a permanent way, to distinguish 
 it from the point rail (q.v.) or movable rail. 
 
 Stocks and Dies. — The common term for the ordinary dies for screwing, 
 which are held in the stock or box provided with lever handles. 
 
 Stokehold. — The compartment in which the stoking of marine boilers 
 is carried on. Stokeholds are open, when they receive only natural 
 draught from above, closed, when they receive all their draught from 
 fans. See Closed Stokehold. The term stokehole is more specially 
 applied to land boilers. 
 
 Stoke Hole. — The area or enclosure in front of the door of a boiler furnace 
 where the stoking is performed. 
 
 Stoker. — In the case of small land stationary boilers means one whose duties 
 are to attend generally to a steam boiler, feed the furnace fires, maintain 
 the water supply, keep the plates properly clean and free from scale 
 and deposits of mud, and to see that the cocks and valves are always 
 in working order. In large laud boilers and in marine and locomotive 
 boilers the stoker's duties are of a more restricted character, being those 
 comprised under the head of stoking, the engineer attending to the 
 cocks and valves. 
 
 Stoking. — The supplying of fuel to a boiler furnace, including its proper 
 distribution over the grate area, the regulation of the draught, perio- 
 dical clinkering (q.v.), and the removal of ash. 
 
 Stop. — (1) A plain cup-shaped casting used to fill up fie socket end of a 
 cast-iron water pipe when it is required to be closed. It is thrust into 
 the socket and there caulked. (2) A term often used to denote a 
 ohaplet (q.v.) of rectangular section. (3) A bar of wood fitting and 
 sliding closely in a hole near the front end of a bench to receive the 
 thrust of wood which is being planed over. (4) A block of metal used 
 under many modifications, its purpose being to cause the action of a 
 machine to cease or to be reversed at a definite invariable position, 
 the stop striking or being struck by some projecting portion of the 
 mechanism. 
 
 Stop Cock. — (1) Acock used in steam boilers, whose function is the shutting 
 ofl and turning on of the steam into the pipe which communicates with 
 the engine. It is usually of a globular shape. (2) Any small plug 
 cock (q.v.) used for making or closing communication in the small tubes 
 of brass fittings. 
 
 Stop Drill, — A driU provided with a collar in order to prevent it from 
 
Mechanical engineering. jss 
 
 penetrating beyond a required distance into the material upon whioli it 
 is being operated. 
 
 Stop Motion. — A lever arrangement in punobing and shearing machines 
 by -which the puncb or shear can be instantly thrown out of action 
 without stopping the machine itself. The actic n of the lever is com- 
 monly to interpose or throw out a block along the line of thrust between 
 the slide and the punch. Also termed disengaging motion. 
 
 Stopper Hole. — The bole in the side of a puddling furnace just beneath 
 the working door through which the rabble (q.T.) is introduced for the 
 purpose of stirring about the pasty metal. 
 
 Stoppering. — The closing of the mouth of a steel ingot mould when filled 
 with molten metal. It is effected by strewing sand on the metal and 
 covering it with an iron plate, which is then held down with a cross bar 
 and wedges. Stoppering is necessary to prevent oxidation and the 
 formation of spongy metal, and to preserve the chemical composition of 
 the metal intact. 
 
 Stopping. — Material used for the filling up of hole's in castings or in 
 patterns ; putty, plaster of Paris, chalk, sheUao varnish, are used as 
 stopping for patterns. See Beaumontague. 
 
 Stopping Off.— The device by which the shape of a foundry mould is 
 altered without altering the pattern itself ; a loose piece of the desired 
 outline being prepared and placed in the mould, and the sand rammed 
 around it into the new shape reqiiired. Thus pipes are stopped off 
 shorter than their patterns, frames are made shaDower than their 
 patterns, and, in short, in an almost infinite number of ways, local parts 
 are altered and modified. The process of filling up pocket prints is also 
 called stopping off, or stopping over. 
 
 Stopping Over. — See Stopping Off. 
 
 Stop Valve. — Strictly speaking, a valve with a sliding face, as a sluice 
 valve, but used indifferently to designate any cook or valve which is 
 employed to regulate the passage of fluids. See Stop Cock. 
 
 Stop Valve Seating. — The globular stop valve of a Cornish or Lancashire 
 boiler is fitted to a seating similar to a safety valve seating (q.v.), and 
 employed for the same reason. 
 
 Stores. — Stores are either general or special in character. In the general 
 stores are contained all the miscellaneous lighter articles used through- 
 out the factory, as screws, nails, packing, tallow, oil, wire, small rivets, 
 soap, &c., &c., all kept under the charge of a storekeeper, who gives 
 them out as needed. The special stores comprise the larger and heavier 
 goods. Thus there is a shed or store for bar iron, another for plates, 
 another for angles and tees, another for stock castings, another for pat- 
 terns, &c., &c., each being under the charge of a man who in large 
 works may have his time wholly occupied in attending thereto, or in 
 small works may divide his time among other duties. 
 
 Stourbridge Clay. — A fire clay found near Stourbridge, used for crucibles 
 and fire bricks. The clay is mixed with ground coke to diminish its 
 tendency to contraction when heated. 
 
 Stoves. — See Drying Stove, Pipe Stoves. 
 
 Straight Edge. — A parallel straight strip of wood or metal used for 
 cheeking the linear aoouracy of work. Straight edges are very difficult 
 to make in the first instance, and are therefore constructed either in 
 pairs or in threes, and checked one against the other in turn. Pairs 
 of equal straight edges are termed winding strips (q v.). 
 Straightening Machines. — (1) Machines used for the purpose of straight- 
 
3S6 DICTIONARY OP TERMS USED IN 
 
 ening rails and bars when they leave the roUs of the forge train. The 
 machines are lite punching machines, a flat block or squeezer taMng 
 the place of the punch. See Rail Straightener. (2) A machine in 
 •which channel, angle, and bar iron are straightened or bent, in boiler 
 and smiths' shops, by squeezing ; hence also called squeezers or squeez- 
 ing machines. The bar, angle, or channel to be bent or straightened 
 is laid agaiust two blocks which form two points of resistance, on the 
 same principle as bending roUs. The force necessary to bend or 
 straighten, as the case may be, is furnished by a head situated midway 
 between these blocks, and on the opposite side of the iron to be bent ; 
 the head is moved forward or backward by a cam, or eccentric, either 
 driven by power, or by a screw if by hand, and being pressed against 
 the iron, bends or straightens it according to the relative positions of 
 the blocks and the amount of pressure brought to bear upon the iron. 
 Since it will bend as well as straighten it is also called a bending 
 machine. 
 
 Straight Link. — A slot link (q.v.) in which the amount of movement 
 necessary for reversal is divided between the link and the block. 
 
 Straight Pane. — See Pane. 
 
 Straight Shank Drill. — A drill, twist or otherwise, having a parallel shank 
 for use with self -centring chucks. 
 
 Straight Shank Keamer. — See Chucking Reamer. 
 
 Straight Taper. — A taper whose bounding line is a plane, not a curve. 
 
 Straight Way Valve.— A valve whose waterway or passage does not bend 
 at a right or at any other angle, but passes through in one plane, or 
 straight forward. 
 
 Strain. — The change of form produced in a structure by the action of the 
 load. When the load is duly proportioned to the structure an elastic 
 strain (q.v.) is the result, when the load is excessive the strain accumu- 
 lates into permanent set (q.v.). 
 
 Strainer, or Wind Bore. — A bulb-like expansion at the termination of 
 the suction pipes of a pump, perforated with numerous small holes, 
 which while permitting of the passage of water prevent the ingress of 
 foreign solid bodies. The collective area of the perforations should be 
 in excess of that of the bore of the pipe, being about equal to \\ times 
 the bore. 
 
 Straining — See Strain. Specifically the tension put upon a foundry 
 mould by the pressure of the liquid metal. It produces lifting (q.v.) in 
 some cases, in others rupture of the mould or distortion of the casting. 
 It is most liable to occur in deep moulds and moulds having large 
 superficies. 
 
 StrainiDg Beam. — A strut placed between the queen posts of a roof truss 
 to counteract the upward thrust of the principals. 
 
 Straining Line. — A fine brass wire used by engineers for lining out 
 shafting and similar work. It is wound on a reel when not in use, and 
 serves the purpose of the chalk line of the wood worker. 
 
 Straits Tin. — Tin ore from Malacca and Bauca. It is the purest ore 
 known, and is valued accordingly. 
 
 Strand. — An aggregation of separate rope yams twisted together in readi- 
 ness for the laying of the actual rope. See Hempen Ropes. 
 
 Strap. — (1) A belt (q.v.). (2) An eccentric strap (q.v.). 
 
 Strap Bar. — A sKding bar which carries the belt fork or forks in the 
 reversing motion of machines for fast or loose pulleys. It slides in 
 guides, in hanging brackets, or other convenient supports, and cord^ 
 
MECHANICAL ENGINEERING. 357 
 
 or levers move it endways to a distance sufficient to move the telt from 
 one pulley to another. 
 
 Strap Brake. — A brake consisting of a strap of hoop iron enveloping the 
 periphery of a smoothly turned wheel, and operating by friction alone, 
 the necessary friction being produced by the tightening of a lever. The 
 hoop may or may not be lined with blocks of wood. 
 
 Strap End. — When the end of a connecting rod (q.v.) has a loose strap or 
 loop enclosing the brasses (See Brass) and held in place with a gib (q.v.) 
 and cottar (q.v.), the complete fitting is Oiilled a strap end. 
 
 Strap Fork.— A belt fork (q.v.). 
 
 Strap Pulley.— See Pulley. 
 
 Straw. — Straw is mised with loam for the same purpose as horse dung 
 (q.v.). 
 
 Stream Tin. — Alluvial tin ore, which, as its name impHes, has been 
 washed down by toiTents into valleys. It is therefore less contaminated 
 with earthy matters than the mine tin (q.v.). 
 
 Strength. — That property by which a material or structure is enabled to 
 resist strains and pressures. See details under specific heads. 
 
 Strength of Materials. — As it concerns us, is a measure of the value of 
 the materials used by the engineer. These embrace iron in its various 
 characters, copper and its alloys, timber, hemp, &o. The strains to 
 which these materials are subjected are compressive, tensile, and shear- 
 ing. See details. 
 
 Stress.— When materials and structures are subjected to straining forces, 
 those forces are resisted by internal molecular actions called stresses. 
 When the straining forces overpower the resisting stresses, the limit of 
 the elastic strength (q.v.) of the material is passed and permanent set 
 (q.v.) ensues. Stresses are tensile, compressive, transverse, shearing, 
 or torsional, and these can be reduced to the tensile and compressive 
 types simply. 
 
 Stress Diagram. — A diagram drawn to scale in which the strains upon the 
 ties, struts, beams, &c., of a structure are represented in a graphic 
 manner both in respect of direction and intensity. The diagram consists 
 therefore of lines only, and, being drawn to scale, the exact amount 
 of the stresses on each member can be taken by direct measurement. 
 
 Stretcher. — See Stretcher Bar. 
 
 Stretcher Bar, or Stretcher. — A long bar or bolt shouldered near each 
 end, and used for the purpose of maintaining j\ frames and side frames 
 at a fixed distance apart and perfectly rigid. 
 
 Stretching. — (1) The stretching of drawing paper on the drawing board in 
 readiness for use. It is accomplished by damping evenly with a sponge 
 all its central portions, gluing the edges for about \ in. inwards and 
 laying on the board. The glue wiU hold the paper and strain it taut 
 as the paper shrinks with drying. (2) Driving bands and cords become 
 permanently elongated due to the constant tension which they undergo 
 over their pulleys. Ropes and leather bands stretch most. To com- 
 pensate for the stretching of cords, tightening pulleys (q.v.) are em- 
 ployed. Leather bands are purposely stretched previous to use to 
 anticipate the inevitable, and to avoid the necessity for relaoing almost 
 immediately after first using. See Belt Stretcher. 
 
 Strickle. — (1) A templet by which a founder strikes or works to shape a 
 loam core. The strickle is usually guided in a longitudinal direction 
 by a guide iron (q.v.). (2) Any piece of wood cut to a special shape 
 and used to impart a special contour to a bed of foundry sand, and thus 
 
358 DICTIONARY OF TERMS USED IN 
 
 save expense in pattern making. The methods of its application are 
 very numerous, being adapted to each special piece of work in turn. 
 
 Strickling. — The art of forming symmetrical or almost entirely sym- 
 metrical outlines in sand or loam by the aid of strickles, a practice 
 by which the cost of much pattern making is saved. The strickling 
 is effected by means of a strickle or striking board and a guide of 
 some form or another, either a vertical bar, an iron guide rod, or a core 
 plate or board, as may happen to be most convenient. 
 
 Striker. — (1) The central core or die block upon which a swage tool is 
 moulded to shape by forging. (2) A hammerman (q.v.). 
 
 Striking Gear. — The lever and forks with their essential fittings by which 
 a belt is shifted from the fast and loose puUeya belonging to a coun- 
 tershaft or a machine. 
 
 Striking Knife. — A timber scribe (q.v.). 
 
 Striking Out. — The drawing out of detailed views of work. Chiefly used 
 in reference to the fidl-sized working drawings of the workshop. 
 
 Striking Screws. — The initiation or commencing of screw threads with 
 chasing tools. See Chaser. 
 
 Striking Up. — Generally used in the same sense as strickling, but the latter 
 is frequently employed in the more restricted sense of producing cores 
 and patterns with strickles working against a guide iron where the 
 longitudinal axis of the core is not in a right line, and the former of 
 making cores or other works by the process of striking up straight though 
 circular work on a core bar against a core board. 
 
 Strip, or Draught. — The taper of patterns for withdrawal from the sand. 
 
 Stripping. —{1) The interposing of thin strips of wood between the boards 
 in a pile of stacked timber, in order to allow a free passage for the air 
 between, for the purpose of effectual drying of the boards. (2) The 
 damaging or tearing off of the teeth of wheels owing to too sudden 
 starting or stopping. Wheels not sufficiently deep in gear are liable 
 to stripping. It is more specially understood of the wooden cogs of 
 mortice wheels. (3) The removal of the sand from a casting which is 
 newly turned out of its mould. 
 
 Stripping Plate. — Stripping plates are plates whose ends are sloped to fit 
 the several grooves of mill rolls, bevelled off chisel-shaped to lift or 
 clear the bars from the grooves, and so prevent collaring (q.v.). 
 
 Stroke. — The distance traversed by the rod and piston of an engine or 
 pump, or similar reciprocating part, or the length of travel of the ram 
 of a shaping machine, or the arm of a slotting machine. 
 
 Strong Iron. — Applied usually to mixtures of iron of various brands, 
 logether with scrap iron, effected according to the judgment of the 
 : oaader, and by which a definite grade of strength or toughness is 
 ODtained. Strong iron will not be soft on the one hand, nor too hard 
 or brittle to be turned and planed on the other. When hammered with 
 a sledge it will become largely indented before fracture. When broken, 
 its crystals will be of moderate size, grey, and somewhat silvery, having 
 a. large proportion of bright black crystals of uncombined carbon or 
 grapHte intermixed therewith. Its tensile strength will be high, say 
 from ten to twelve tons per square inch. 
 
 Strong Sand. — Tenacious foundry sand, containing a large proportion of 
 loam and horse dung. 
 
 Structural Load. — The load due to a structure itself, as distinguished 
 from the imposed load (q.v.) . 
 
 Structures, — ^An assemblage of distinct members combined together to 
 
MECHANICAL ENGINEERING. 359 
 
 produce a specific piece of mechamsm. In estimating; tHe strength of 
 structures tlie strains on each individual member and sectional portions 
 are taken separately, and also the strains due to the action of certain 
 portions on each other due to their mass and leverage, &c. 
 
 Strut Girder. — A lattice girder -whose top and bottom flanges are united 
 by vertical struts and braced by diagonal braces, or by counter bracing. 
 
 Stmts. — (1) Vertical or diagonal rods which connect a beam -with a truss 
 lod, and through which the strains due to deilectiou of the beam are 
 translated into those of tension in the rod. In roof trusses, those mem- 
 bers which extend diagonally from the beam or from the foot of the king 
 or queen posts either to the rafters or to the shoulders of queen posts. 
 (2) Generally any member of a structure which is in a state of com- 
 pression or thrust, as, for example, the bars of a lattice girder which 
 incline downwards to the nearest point of support. The jib of a crane 
 is also a strut. 
 
 Stub End. — A strap end (q.v.). 
 
 Stud. — (1) A projecting pin used as an attachment or centre of motion 
 for a lever, rod, or wheel. (2) A bolt or screw having one nut only. 
 Both ends of a stud are threaded, but while one end is tapped into a 
 screwed hole, the other is left to receive the tightening nut. (3) A 
 circular projection turned on a loose boss or similar loose portion of a 
 pattern, and fitting into a corresponding recess of its fellow-piece. A 
 stud is therefore a single dowel. (4) A form of chaplet having basal 
 plates and disc-shaped heads. 
 
 Stud Block. — ^A rectangular block used for the purpose of screwing a stud 
 (q.v.) into its hole. The block is screwed internally throughout its 
 length ; the lower screwed portion fits easily over the standard size of 
 screw for which it is designed, and the upper part receives a set screw 
 whose point bears on the end of the stud which is being screwed in, a 
 spanner fitting around the outside of the block imparting to it the 
 necessary circular motion. Since the block fits the screw loosely only, 
 a turn of the hand alone is sufficient to run it back off the stud after 
 the screwing in is completed. Stud blocks are kept for all the ordinary 
 sizes of screws in workshops, and the trouble of using look nuts for the 
 screwing in of studs is avoided by their employment. 
 
 Studded Chain, or Stayed Link Chain. — Chain whose IJTika are stayed in 
 the centre by a short stud or connecting piece welded in one with them. 
 
 Stud Print. — ^A round print set in position with a circular stud fitting 
 into a corresponding centre-bit hole, instead of being attached with 
 brads or screws. Stud prints of various diameters, but whose studs are 
 uniform in size, are therefore readily interchangeable on patterns. 
 
 Stud Wheel. — The wheel which revolves loosely on the stud or inter- 
 mediate pin of a screw-cutting lathe, or the idle wheel of the train. 
 
 Stuff. — A workshop term which denotes timber in general, as dry stuff, 
 wet stuff, cross-grained stuff, &c. 
 
 StufS.ug Box. — A recessed chamber through which the rods of pumps and 
 steam pistons pass, being surrounded therein either with hempen, 
 metallic, asbestos, or other packing, to prevent the leakage of the fluid 
 or the steam. The packing is retained in place by the screwing down 
 of a gland (q.v.) thereon. 
 
 Sucker. — The bucket of a lifting or sucking pump. 
 
 Sucking Pump. — See Suction Pump. 
 
 Suction. — The drawing of air or liquid into a vacuum, the entry being 
 due to the difference in pressure 
 
36o DICTIONARY OF TERMS USED IN 
 
 Suction Box. — The lower or entering chamber of a suction pump, or of a 
 series of two or three throw pumps, into which the liquid is drawn on 
 the upward stroke of the piston. 
 
 Suction Pipes.— The series of pipes through which liquids aie drawn up 
 hy pumping machinery. 
 
 Suction Pump. — A lift pump which depends on atmoi?pheric pressure 
 for its action. The atmosphere will sustain a column of water 32 ft. 
 in height, and this therefore is the limit to the depth from which a 
 suction pump will draw water. When the water is drawn into the 
 barrel by suction, the descent of the piston allows it to pass through the 
 bucket valve into the upper part of the pump, whence it is lifted out 
 and delivered on the upward stroke of the bucket (see Pump Bucket). 
 Actually a pump will not lift from a greater depth than 28 ft. owing to 
 defects in fittings causing leakage, and 25 ft. is about the limit in 
 practice. But less lift than this must be given if the pumping is to 
 be continuous. 
 
 Suction Strainer. — See Strainer. 
 
 Suction Valve. — The lowermost valve in a lift pump, that is below the 
 bucket through which the liquor is lifted by the suction of the vacuum 
 above, or in other words by the pressure of the atmosphere beneath 
 acting against the vacuum above. 
 
 Sudden Grip Vice. — See Instantaneous Grip Vice. 
 
 Sudden Load. — An impulsive load (q.v.). 
 
 Suet.— Used for the lubrication of engine cylinders and bearings ; it is 
 also rubbed over bright parts to preserve them from rust. 
 
 Suet Lubricator. — AtaUowoup (q.v.). 
 
 Sugar Loaf. — See Thimble. 
 
 Sullage. — The scoriae, cinder, scurf, dirt, &c., which floats on the surface 
 of, and is skinmned off the metal, while it is being poured into a foundry 
 mould. 
 
 Sullage Piece. — Sometime applied to a runner (q.v.) or to the head metal 
 (q.v.) of a casting. 
 
 Sulphate of Copper. — See Margery's Fluid. 
 
 Sulphate of Lime. — Oa SO4. A compound which ranks next to the carbon- 
 ate as a destructive agent in the incrustation of steam boilers. It loses 
 its solubility beyond 95° P., being altogether insoluble at 290°. See Soda. 
 
 Sulphur.— Symbol, S. ; comb, weight, 31'98. An element which plays a 
 most important part in the preparation of iron, Its presence, whether 
 in wrought iron or steel or cast iron, is in most cases an evU, affecting 
 the quahties of the metal. A very small proportion of sulphur will 
 make cast iron harder and whiter. In excess it produces red shortness. 
 A mere trace of sulphur in wrought iron or steel will produce red short- 
 ness. Pig iron which contains near -03 per cent, of sulphur is not 
 suitable for conversion into Bessemer or Siemens steel. The value of 
 coke as a smelting agent, or for remelting iron in the cupola, is also 
 diminished by the presence of sulphur. 
 
 Sump. — The lower part of a sinking pump (q.v.). 
 
 Sun and Planet Wheels. — A substitute invented by Watt for the engine 
 crank. It consists of a cog wheel fixed at the end of the connecting 
 rod, whose centre occupies the place of the ordinary crank pin. The 
 centre of this wheel is maintained equidistant from the centre of another, 
 or "sun," wheel keyed on the fly-wheel shaft. As the planet wheel is 
 carried round the sun wheel, the latter is compelled to revolve, and with 
 it also the ehaf t which carries the fly wheel. 
 
MECHANICAL ENGINEERING. 361 
 
 Sun Copy. — A term often used to designate a phototype (q.v.). 
 
 Sunk Key. — See Feather. 
 
 Super Elevation. — The amount by which the outer rail of permanent way 
 is elevated above the inner one when carried round a curve. 
 
 Superheated Steam. — Steam in the gaseous state, produced by imparting 
 additional heat to saturated steam (q.v.), or else by expansion. It is 
 brought to this condition by being passed through a superheater 
 in which the suspended moistrire is driven off by removing it from con- 
 tact with the water, and by the application of heat combined, so as to 
 render its condition very nearly that of a true gas. If superheated 
 beyond a few degrees the steam corrodes away the metaUic surfaces 
 with which it comes in contact in a rapidly destructive manner. 
 
 Superheating. — See Superheated Steam. 
 
 Superheating Surface. — The amount of surface in a steam boiler to which 
 steam is subject to drying or superheating (q.v.). 
 
 Super Eoyal Drawing Paper. — Measures 27 in. by 19J in. 
 
 Super Salted Water. — Sea water which contains more than -}i, or 8 oz. of 
 salt to the gallon, and from which therefore the brine should be blown 
 off to prevent injurious incrustation. See Two Salt "Waters. 
 
 Supplement of an Angle. — Its difference from 180°. 
 
 Supply Steam. — Entering steam, or that which is about to do work in an 
 engine cyhnder, as distinguished from exhaust steam (q.v.). 
 
 Suppression. — The cut off (q.v. ) of steam in a cylinder. 
 
 Surface Blow-off. — The blowing off of the scum which collects on the top 
 of the water in a boiler. 
 
 Surface Chuck. — A face plate (q.v.). 
 
 Surface Condensation. — Condensation of steam effected in a surface con- 
 denser (q.v.) as distinguished from that effected by a jet condenser 
 (q.v.). 
 
 Surface Condenser. — ^The modem form of condenser, in which the steam is 
 brought into contact with the outside of a nimiber of small brass tubes 
 enclosed in a cast-iron casing, through which tubes a circulation of cold 
 water is maintained by means of a circulating pump (q.v.). The steam 
 is thereby condensed effectively, and the warmed water of condensation 
 is sent to feed the boiler. 
 
 Surface Gauge. — A scribing block (q.v.). 
 
 Surface Plate. — A plate of metal which has been brought to the highest 
 possible degree of superficial accuracy, and which is used for the pur- 
 pose of testing the truth of work in course of preparation. Sir Joseph 
 Whitworth originated the modem method of the manufacture of surface 
 plates by the finishing operation of scraping (q.v.), previous to which 
 they had been ground by means of emery powder. Surface plates are 
 made in numerous sizes for workshop use. They are rendered rigid 
 with ribs underneath. A good pair of surface plates should be sepa- 
 rated with difficulty after being rubbed together. Professor Tyndall 
 attributes this property of adherence to molecular attraction, due to the 
 extreme proximity of the particles. That such is the cause, and not, as 
 was previously supposed, the pressure of the atmosphere, there can be 
 little doubt, since the plates will adhere if placed under an air pump 
 vacuum. 
 Surfacing. — Surfacing signifies the transverse traverse of a slide rest, or 
 its motion across the bed for face work. Hand surfacing is effected by 
 the screw and handle which actuates the shde for cross travel, but in 
 the larger lathes which are provided with a back shaft the surfacing is 
 
362 DICTIONARY OF TERMS USED IN 
 
 automatic, beiag eflEeoted by gearing or by friction cones driven from 
 tlie back shaft. 
 
 Surfacing Lathe. — ^AU orduiary engineers' lathes are surf aoing lathes, but 
 it is customary to give a lathe that appellation in specifications, to dis- 
 tinguish it from special lathes in which boring only, or some such single 
 set of operations are performed. 
 
 Surging Drum. — See Warping Cone. 
 
 Suspension Links. — Two parallel flat rods or plates, by which the slot links 
 (q.T.) of an engine are lifted or lowered for reversal, one end of the 
 pair being loosely attached to the tafl. of the slot link, the other end 
 being attached to a short lever keyed on the weigh shaft. Also called 
 vibrating links from the manner in which they vibrate with the slot 
 link when the engine is working. When placed in a horizontal direc- 
 tion they are frequently termed drag links. 
 
 Swab. — See Water Brush. 
 
 Swab Pot. — See Water Pot. 
 
 Swage. — A die used for imparting any desired shape to a piece of forging. 
 It consists of a lower piece fitting into the anvil, and an upper piece 
 held by the smith, between which the metal to be operated upon is 
 wrought to shape. Called also top and bottom tools. See also Spring 
 Swage Tools. 
 
 Swage Block. — A rectangular block of cast iron used by smiths. It is 
 pierced through its central portions with numerous holes, both round 
 and square in section, for the reception of work which requires shoulder- 
 ing, while its edges are grooved, in various sectional forms to receive 
 pieces of forging too large for the orduiary bottom swages. 
 
 Swage Tools. — See Swage. 
 
 Swaging. — The drawing down of a piece of wrought metal to a definite 
 form, with or without the aid of swages. The reverse of upsetting (q.v.) . 
 
 Swarf. — (1) The particles of metal abraded by the cutting of screw 
 threads. (2) See also Wheel Swarf. 
 
 Swash Plate. — A circular plate attached to a shaft, the face of the plate 
 being at an angle with the axis of rotation of the plate. The plate 
 therefore imparts a reciprocal movement to a rod which is in contact 
 with its surface. 
 
 Sway. — The lateral vibration of a rope or belt due to want of accuracy in 
 the pulleys, or to their being not in plane. 
 
 Sweating On, or Sweating. — The soldering of metaUio surfaces vdthout 
 the aid of a copper bit. The surfaces are cleaned, heated, and covered 
 with a film of solder ; they are then brought into juxtaposition and 
 warmed until the solder flows and unites. Sweating on is often em- 
 ployed for the temporary holding together of work which has to be 
 turned or shaped, and which could not be so conveniently held by other 
 methods. After having been turned or shaped, the separation of the 
 parts is readily effected by the aid of heat. 
 
 Swedish Iron.— Swedish bar iron is chiefly in request for the manufacture 
 of crucible cast steel (q.v.) . It is produced from iron smelted from 
 magnetic ores nearly free from sulphur and phosphorus, the smelting 
 being effected by charcoal. The Dannemora brands are the Hoop \_, the 
 Double Bullet, W aii^ Crown, Hoop p and Little S> ^"^ Gridiron 
 brands. Swedish pig is cast in iron moulds, in rectangular slabs 
 16 in. long X 9 in. wide X 2^ in. thick. 
 
 Sweep. — Any portion of work whose outline is curved is said to be 
 sweeped. Sweeps, that is short sections of circles, are commonly used 
 
MECHANICAL ENGINEERING. 363 
 
 in the foundry for sweeping up entire rings, tlio segment being rammed 
 up and shifted round several times in succession until the ring is 
 complete. 
 
 Sweeping Tip. — StriMng up (c[.v.) in loam or green sand. 
 
 Sweep Saw. — See Bow Saw, Compass Saw, Pad Saw. 
 
 Swell Piece. — Any flat piece of material which has its outer face curved. 
 A term common in the shops. 
 
 Swing. — The swing of a lathe signifies the size of the piece of work which 
 can be turned in it. Its dimensions are usually given in the gap, over 
 the bed, over the rest or carriage, and between centres. 
 
 Swing Frame. — (1) The frame which carries the row of saws in a recipro- 
 cating or frame saw. It is made of cast or wrought iron, and works in 
 vertical guides. (2) Swing frames are besides of wide application, 
 being used in nearly all those cases in which the bearings of a piece of 
 mechanism are required to be free to move relatively to other portions. 
 
 Swing Sledge. — See About Sledge. 
 
 Swing Table. — The table of a drilling machine which is made to swing 
 or swivel around the central piUar, or frame work, as the case may be, 
 in order to bring any desired portion of the work underneath the drill. 
 
 Swipe. — A term used in some districts to signify the starting lever of an 
 engine, chiefly of the portable type. 
 
 Switch. — See Point. 
 
 Swivel. — A provision made by means of a shank and collar for circular 
 movement. Crane hooks are thus made to swivel, the shank of the 
 hook turning in a collar formed in the eye. Moulding boxes swivel 
 upon shanks, or pins, cast in their ends. Swivel motions are employed 
 in many parts of machines. 
 
 Swivel Hook. — See Swivel. 
 
 Swivel Jaw. — See Taper Vice. 
 
 Swivel Union. — A union (q.v.) which is provided with an indepen- 
 dent movement by which it may be swivelled when the parts are 
 screwed up. 
 
 Swivel Vice. — A bench vice which is made to swivel in a horizontal plane. 
 
 Symbols. — Letters representative of numbers, or quantities, used in mathe- 
 matical calculations. 
 
 Symmetrical Beams. — Beams whose centre of gravity corresponds with 
 the centre of their mass. 
 
 Syphon Lubricator. — A type of lubricator in which the oil is fed slowly 
 to the bearing by cotton wick or cotton tape inserted at one end into the 
 oil, while the other bends over and down to the bearing. The principle 
 is of very wide application. 
 
 Syphon Oil Cup. — See Syphon Lubricator. 
 
 Systems. — Alludes to the various types of bracing and counter bracing 
 adopted in different girder frames. 
 
 T. 
 
 e. — The Greek letter Theta is usually applied in engineering formulse to 
 
 denote the measurement of an angle, whatever angle may happen to be 
 
 under consideration in the formulae. 
 Table. — ^Applied to the horizontal portions of machines upon which the 
 
 work to be operated on is placed, as in planing, shaping, slotting, and 
 
 other machines. 
 
364 DICTIONARY OF TERMS USED IN 
 
 Table Engine. — A type of vertical engine, once very common, in which 
 the cylinder stood on a table or plate of metal, and the crank and fly- 
 wheel shaft worked in the top of A standards. 
 
 Table Feed. — When a shaping maolmie has a fixed instead of a traversing 
 head (q..v.), the traverse is imparted to the table ; hence called a table 
 feed, to distinguish it from tLe feed given to the traversing head in 
 that type of machine. 
 
 Table Moulding Machine. — A wheel moulding machine (q.v.) in which 
 the flask is rammed on a revolving table, as distinguished from those 
 machines which are set in the floor. The table machines are used for 
 small work and work of an average size, the floor machines for the largest 
 wheels. 
 
 Table Saw. — A compass saw (q.v.). 
 
 Table Vice. — A small vice for light work, attached to a table or bench by 
 means of a screw underneath, which tightens up a triangular pointed 
 clamp against the under side of the table. 
 
 Tackle or Lifting Tackle. — A term applied to the combinations of pulleys 
 used for hoisting purposes in the erection of heavy work, and embracing 
 blocks, chains, and similar attachments. 
 
 Tail. — (1) The hinder part of a portable crane upon which the balance 
 box rests. (2) The vertical support of a tail vice (q.v.). 
 
 Tail Piece. — A short double-flanged casting, bolted to the bottom of the 
 suction box of a pump for the connecting up of the actual suction pipes. 
 
 Tail Eace. — The channel which conducts away the tail water (q.v.) from 
 a water wheel. 
 
 Tail Screw. — ^A screw situated at the hinder end of that which it actuates. 
 Hence the back centre screw of a headstoek, and the screw which actuates 
 a poppet cyhnder are termed tail screws. See Tail Stop Screw. 
 
 Tail Stock. — Another name for the poppet (q.v.) or movable head of a 
 lathe. It is used in contradistinction to head stock. 
 
 Tail Stop Screw. — The back screw of the headstoek of a back-geared 
 lathe. It has a flat or slightly rounding end, which receives the thrust 
 of the tail end of the mandrel. 
 
 Tail Vice. — The ordinary form of vice for general and rough work, which 
 is partly attached to the bench or to a tripod stand, but whose tail or 
 vertical support rests in a block of wood or other attachment, either on 
 the floor or on the tripod base. It is sometimes called the standing 
 vice. 
 
 Tail Water. — The water which flows away from a water wheel or turbine 
 after having done its work, or the waste water. Called also tail race. 
 
 Taking XTp. — (1) A shop term which signifles the making of adjustment 
 for wear. It is nearly, though not quite, equivalent in meaning to 
 tightening, but is rather appHed to smooth bearing and moving parts 
 than to parts tightly bolted or wedged together. The term is legiti- 
 mately applied to the closing up of strap ends of connecting rods, the 
 cone bearings of lathes, divided brass bearings, compensating collars, 
 &c. It is accomplished by means of set screws, gibs and cottars, lock 
 nuts, Sea. See "Wear. (2) Also applied to the shortening and relacing 
 or resplicing of belts and ropes which have become stretched by use. It 
 is then termed taking up slack. 
 
 Taking Up Slack.— See Taking Up. 
 
 Taking Up Wear. — See Taking Up. 
 
 Tallow, — ^Used for the lubrication of engine cylinders, as a flux for solder- 
 ing lead, for coating bright work to prevent corrosion, and as an ^uti- 
 
MECHANICAL ENGINEERING. 365 
 
 ItlCinistatioil agent in. steam toilers, whioli it effects ty uniting with the 
 salts of lime to form an insoluble soap. Its employment for the latter 
 purpose is, unless performed very judiciously, a practice to be strongly 
 condemned. It is sometimes forced into a boiler by means of a syringe, 
 in order to prevent priming (q.v.), which it does by forming a scum on 
 the surface of the water. Tallow should not be used for the lubrication 
 of engine cylinders unless of the very best quality, since with high- 
 pressure steam it becomes partially converted into oleic or stearic acids, 
 which corrode the iron away in the piston, cylinders, and steam joints, 
 and around the bolts. 
 
 Tallow Cup. — A hoUow oup-shaped vessel screwed in the upper part of 
 an engine cvlinder to hold the tallow or oil used for lubrication. It is 
 provided with either one or two cocks. 
 
 Tallow Injector. — A syringe used for injecting melted tallow into marine 
 and other boilers for the prevention of incrustation. 
 
 Tamping, — (1) A moulder's term which signifies the ramming up of the 
 sand round a pattern. (2) Stopping the tap hole (q.v.) of a cupola with 
 clay. The term is derived from the beating down a charge into a hole 
 in blasting and mining operations. 
 
 Tan. — The Tangent of an angle or of a circle. 
 
 Tandem Engines. — Horizontal engines of the compound type in which 
 the cylinders are placed in the same longitudinal axis, so that the 
 piston rods are in one length. 
 
 Tang. — The shank of a cutting tool, or that portion which is driven into 
 the handle. This portion is not hardened. 
 
 Tang Chisel. — A chisel having a tang, as distinguished from a socket 
 cMsel (q.v.). 
 
 Tangent Screw, or Tangent Wheel. — A worm or endless screw of fine 
 pitch, consisting either of multiple or single threads, and so called be- 
 cause its axis stands at a tangent with the circumference of the wheel 
 which it drives. 
 
 Tangents, Lines of. — See Sines, Line of. 
 
 Tangent Wheel A worm or tangent screw (q.v.). 
 
 Tanite. — A manufacturer's term given to a certain class of emery wheels. 
 
 Tank. — A receptacle for liquids, made in wrought and cast iron and of 
 various sizes, the larger sizes being made of separate plates riveted or 
 bolted together. Cast-iron tanks are caulked with iron borings and 
 sal-ammoniac, sometimes from within, sometimes from without. See 
 Tank Plates. The sides of large tanks are stayed against liquid pressure 
 by means of stay bolts or tie rods. 
 
 Tank Base. — ^A water tank bed plate (q.v.). 
 
 Tank Engine. — A locomotive engine which is provided with a tank for 
 the conveyance of its own water, thus dispensing with the necessity 
 for a tender. Tank engines are of side tank, or saddle tank type, 
 according as the tanks flank or arch over the boiler. 
 
 Tank Plates. — The plates of which cast-iron tanks are constructed. They 
 are rectangular in form, with flanges cast aroimd the edges and stand- 
 ing at right angles with the plate for bolt attachments. Since the 
 difference in liquid pressure on the sides of deep tanks near the surface 
 and near the bottom is very considerable, a corresponding difference is 
 conamonly made in the thicknesses of the upper and lower plates ol 
 deep tanks, or tanks consisting of two or more tiers. See Tani. 
 
 Tannic Acid, — Substances containing tannic acid are in request, being 
 found useful for the prevention of boiler incrustation, the tannic acid 
 
366 DICTIONARY OF TERMS USED AV 
 
 comlDining with the lime to form tannate of lime. This is an insoluhlo 
 scum whioh is blown ofE. Oak bark is the substance commonly em- 
 ployed, being suspended within the boiler. 
 
 Tap. — (1) A male templet screw used for cutting threads in holes. Taps 
 are tapered for entering, and stump or parallel for finishing. Taps for 
 ordinary work are cut to common Whitworth threads ; gas taps have a 
 finer thread. Taps are actuated by a tap wrench, or by screwing 
 machines. They are grooved, and relieved. Using a tap is termed 
 tapping or screwing. See details under these and other headings. 
 (2) A term employed in reference to the opening of a hole in a melting 
 furnace through which the liquid metal flows. See Tap Hole. 
 
 lap Cinder. — The slag or refuse of puddling and reheating furnaces, 
 consisting of a ferrous silicate, or a silicate of the protoxide of iron, 
 2 Fe Si O2, which, after a roasting process, becomes converted into 
 Fea O3 and Si, the peroxide or ferric oxide, and silica, both highly infu- 
 sible substances. This, under the name of bull dog (q.v.), is used for 
 the bottom lining of puddUng furnaces. It is covered with puddlers' 
 mine (c|..v.). 
 
 Tape. — See Measuring Tape, Cotton Tapes. 
 
 Taper. — (1) In a foundry pattern, is the bevelling or thinning downwards 
 of the faces which are to draw or lift from the sand, in order to facili- 
 tate their withdrawal. In deep patterns this taper will be from \ in. 
 to \ in., that is the bottom edge will be \ in. or \ in. thinner than the 
 top. Also termed draught, and strip. (2) The slope of the cylindrical 
 plug, and seating of a cock. It varies from one in four to one in six. 
 
 Taper Belt Joint. — A joint made in cotton belting by cutting off the plies 
 at different lengths to thin the joint down, and so prevent jumping of 
 the belt when running. 
 
 Taper File. — The commonest form of file, in which the dimensions of the 
 cross section diminish towards the point. 
 
 Taper Plug.— See Plug. 
 
 Taper Reamer. — A reamer whose body is tapered longitudinally for clean- 
 ing out tapered holes. 
 
 Taper Screw Chuck, or Screw Worm Chuck. — ^Aform of lathe chuck used 
 for turning wood, in which the trouble of attaching it to the work with 
 ordinary wood screws is saved by h aving a taper screw affixed to the 
 centre of a small face plate and standing out therefrom, to which the 
 piece of wood to be turned is screwed. These chucks are restricted 
 in use to small work, and that also which is chiefly cut plank way of 
 the grain, since the screw strips out end grain if much pressure is appUed 
 when turning. 
 
 Taper Shank Drill. — ^A drill, twist or otherwise, whose shank is tapered in 
 its length, and circular in section, for use with the ordinary drill spindles. 
 
 Taper Shank Reamer. — A reamer (q.v.) whose shank is tapered similarly 
 and for the same reason as a taper shank drill (q.v.). 
 
 Taper Tap. — A tap (q.v.) tapered in the direction of its length, in order to 
 afford facility of entrance and ease of cutting when commencing the 
 cutting of a screw thread in a drilled hole. The tap, by reason of its 
 taper, cannot cut at its lower end, but only near the upper end or shoulder. 
 Hence its function is to initiate a shallow thread only at the top of the 
 hole, and so prepare the way for the plug or finishing tap, which is 
 parallel throughout. 
 
 Taper Turning. — See Conical Turning. 
 
 Taper Vice. — A vice provided with an attachment for holding tapered 
 
MECHANICAL ENGINEERING. 36? 
 
 work. It usually consists of a loose jaw piece rounded on the tact, 
 and movable in a corresponding hoUow seating on the fixed jaw, by 
 which means it is capable of a slewing movement to adapt it to dif- 
 ferent angles. 
 
 Tapes.— See Cotton Tapes. 
 
 Tap Grooving. — The cutting of the grooves or flutes in taps (q.v.) by 
 means of which their cutting edges are imparted. The process is usually 
 accomplished in a milling machine (c[.v.) . 
 
 Tap Holder. — The contrivance by which the taps are held ia a screwing 
 machine. 
 
 Tap Hole. — (1) The hole in a blast furnace or cupola through which the 
 molten metal is allowed to flow into the mould or ladles. See Bott 
 Stick, Tapping. (2) The hole in the bottom of a casting ladle (q.v.) 
 for the discharge of the metal. 
 
 Tappet. — (1) The adjustable pin or stud bolted on the edge of a metal 
 planing machine, and which through a series of levers and rods reverses 
 the motion of the table. (2) The cam teeth, or wipers, on the wheel of 
 a tilt-hammer are also called tappets. (3) The valves of Cornish engines 
 are actuated by tappets. 
 
 Tappet Motion. — The feed motion derived from the action of a tappet 
 (q.v. ) as distinguished from that of a paul, a screw, or other agency. 
 
 Tapping. — Signifies the opening of the tap hole in a cupola or melting 
 furnace, through which the molten metal finds egress into the ladle or 
 into the mould, as the case may be. It is closed with fire clay during 
 the intervals of tapping. See Bott Stick. (2) The art of screwing a 
 hole with a tap. 
 
 Tapping Bar. — The pointed bar or bott stick (q.v.) employed for tapping 
 out the molten metal from a cupola. 
 
 Tapping Hole. — (1) A hole driUed to the same diameter as the bottom of 
 a screw thread, or twice the depth of the thread smaller than its nominal 
 size, thus leaving metal for the tap to remove. (2) A tap hole (q.v.). 
 
 Tap Plate. — A screw plate (q.v.). 
 
 Tap Wrench. — A double and equal armed lever used for the screwing of 
 taps. A square hole pierced through the centre of the bar fits over the 
 neck of the tap and gives suflicient grip to turn it by. 
 
 Tar. — Is used in foundries for imparting a hard preservative skin to the 
 surfaces of loam patterns and sometimes of cores. See also Anhydrous 
 Tar. Archangel and Stockholm tar are used for hemp ropes. 
 
 Tarred Bopes. — Ropes made of hemp, usually Russian, and steeped in 
 tar, as distinguished from Manilla or white ropes. 
 
 Tar Varnish. — Bituminous paint (q.v.). 
 
 Teak. — (1) There are two woods thus designated, the one the African 
 oak, the other the Moulmein or Indian, the true teak. The latter is the 
 one which is chiefly in request for engineering works. It is the wood 
 of Tectmia grandis, found in the south-eastern parts of Asia and the East 
 Indian Islands, Ceylon, Malabar, and Java. It is of a greasy nature, 
 and therefore does not corrode iron in contact with it. It contains 
 silicious matter which dulls the edge of cutting tools. It is of a light 
 brown colour, shrinks little, is durable, straight and rather open grained, 
 stands heat well, and is not attacked by insects. A cubic foot weighs 
 46 lbs. Sp. gr. -74. (2) African oak or African teak is beUeved to be 
 the product of Oldfieldia Africana, of the order Euphorbiaceae. It is 
 harder, closer grained, and heavier than the Indian teak. It is about 
 as heavy as water, its sp. gr. being -993. 
 
368 DICTIONARY OF TERMS USED IN 
 
 Tedge. — An ingate (q.v.)- 
 
 Tee.— See Tee Pipe. 
 
 Tee-headed Bolt. — A tolt whose head is formed of a transverse piece, so 
 that with its hody it makes the outline of a letter X- The piece which 
 forms the upper bar fits into a recessed or undercut X ^l^^j whose over- 
 hanging edges furnish the necessary resistance to the force requisite for 
 tightening up. This form of bolt is used where adjustability is neces- 
 sary, the bolt sHding into any position within the range of the tee slots. 
 
 Tee Irons, — Rolled wrought-iron bars whose section is that of a letter X- 
 They are universally employed in miscellaneous engineering built-up 
 constructions, as bridge, girder, and roof work. 
 
 Tee Joint. — A welded joint employed for uniting pieces of bar iron stand- 
 ing at right angles with each other. The end of the bar which forms the 
 vertical part of the tee is spread out, and set down or fidlered cross- 
 ways, and laid upon a similar set-down and fuUered portion gf the face 
 of the transverse bar. 
 
 Teem, or Teeming. — A term applied to the pouring of metal, or to the 
 appearance which it presents on being run from the furnace, or ladle, or 
 crucible. Thus it is said to teem " dead " or " fiery," according to its 
 sluggish or active appearance. The term is chiefly used by steel makers, 
 who "teem," not pour, their ingots. 
 
 Teeming. — See Teem. 
 
 Teeming Hole, — One of the holes or pits in the floor of a steel melting 
 house, in which the moulds for the reception of crucible cast steel or 
 for ingot moulds are placed. 
 
 Tee Pipe, — A branch pipe, the branch of which comes out of the main 
 pipe at right angles, similar to a letter X- Tee pipes are usually made 
 with socket and spigot. Coimections through flanged tees are also 
 made. 
 
 Tee Eest, — The 'ordinary rest for hand-turning, so caUed from its re- 
 semblance to the letter X- 
 
 Tee Slots. — Slots or grooves cast in the tables of planing, shaping, slotting, 
 and drilling machines for carrying the heads of tee-headed bolts (q.v.). 
 Tee slots should preferably be planed on their inner edges. 
 
 Tee Square. — ^A trying square formed in the shape of the letter X> t^e 
 vertical portion being the blade, the transverse bar the stock. XJsed 
 chiefly in the drawing office. 
 
 Teeth, — The. projections on the peripheries of cog wheels and ratchet 
 wheels. See Wheel Teeth. 
 
 Telescopic Boiler. — A boiler in which the rings forming the barrel are 
 tapered in diameter, so that the transverse joints or scams fit with- 
 out and within m. succession. The shells of most Cornish and Lan- 
 cashire boilers are thus made. 
 
 Telescopic Pipe, — A pipe within whose upper end the last of a series of 
 deep-well pipes slides. It is used in deep-weU pumps to permit of 
 moderate adjustment of the length of the series. It is sometimes termed 
 a telescopic suction shde. 
 
 Telescopic Shaft. — See Telescopic Slide. 
 
 Telescopic Slide, or Telescopic Shaft. — Is formed by the movement of 
 hollow tubes one within the other. Such shafts are of wide applica- 
 tion, being employed to carry a portion of a machine whose longitudinal 
 position is always varying, as the horizontal spindles of radial drilling 
 machines, and in blast pipes for portable forge furnaces, and in deep- 
 well pumps. 
 
MECHANICAL ENGINEERING. 369 
 
 Tell Tale. — An indicator by -wHcli the attendant of a winding engine is 
 informed when to stop its motion, and so arrest the upward or down- 
 ward movements of the cage. Tell tales are employed also on Tarioua 
 automatic machines to indicate the precise time when a certain set of 
 operations are terminated. 
 
 lelodyiiamic Transmission. — The transmission of power to long distances 
 by means of relays of wire rope (q-T.). 
 
 Temper. — (1) The temper of a piece of steel is its elastic condition con- 
 sidered in reference to the purpose for which it is to be utUised. See 
 Tempering. (2) A mixture of 16 parts of copper to 32 of tin, used to 
 assist in the mixing of alloys of various kinds in which the proportion 
 of copper is so small that if added alone its higher fusing point wotdd 
 not allow proper combination to take place. The copper and tin alloy 
 are added as a temper. See Babbitting. 
 
 Temperature. — The temperature of a body is measured by the amount of 
 its sensible heat, or that which can be measured by a thermometer, and 
 is independent of its latent heat (q.v.). It is therefore that which can 
 be communicated from one body to another, and be directly recognisable 
 and measurable. 
 
 Tempering. — (1) The imparting of a definite degree of hardness, or elas- 
 ticity to steel, by the raising or letting down (q.v.) of the metal to a 
 certain temperature, and then rapidly cooling or quenching in water or 
 oil, from that temperature. The temperature is indicated by the colour 
 which the steel assumes in passing from a high to a lower degree, and 
 is different for almost every class of cutting instruments. The steel is 
 quenched in water, oil, soap, or other substances, the medium varying 
 with the nature of the objects tempered and the degrees of heat. Some- 
 times the temperature is estimated not by colour, but by the flashing 
 point (q.v.) of a fat. (2) Tempering also has reference to the slow dry- 
 ing of articles moulded in clay, as bricks and crucibles. When the 
 paste has been moulded into form, the article is subjected to a pro- 
 longed desiccation at a gradually increasing temperature ranging from 
 about 60° P. to 150° or 180°. The tempering may continue from two 
 to eight months, and the longer the process is continued the longer the 
 crucibles or bricks will last. 
 
 Template, or Templet. — Any temporary pattern, guide, or model by which 
 work is either marked out or by which its accuracy is checked. Usually 
 thin Ught plates of wood or metal cut to special outlines. Used in all 
 the departments of engineering. 
 
 Template Maker. — See templating. 
 
 Templating. — The laying out (q.v.) of diagrams on thin sheets of metal, 
 or thin strips of wood, from which the plates employed in boiler and 
 sheet metal work are to be cut. Templating is usually the special work 
 of a boiler maker or plater devoted wholly to it, hence called a template 
 maker, whose intelligence and careful skill ensure him a rate of wages 
 correspondingly higher than those of ordinary platers or boiler makers. 
 
 Templet. — A template (q.v.). 
 
 Temporary Centre. — A centre piece, or a centre mark, used only for a tem- 
 porary purpose, either for marking out work or for machming it. A 
 temporary centre may be a slip of wood bridging over a hole, upon 
 which sHp the centre point is marked ; or it may be a mandrel filling 
 up the hole, and having a centre point countersunk in its ends. 
 
 Temporary Mandrel. — A mandrel (q.v.) used as a temporary centre, either 
 for supporting work which is being lined out, or for carrying work 
 
370 DICTIONARY OF TERMS USED IN 
 
 already 'borecl, in the lathe wlule it is being turned on the outside 
 diameter. 
 
 Tenacity. — That property by which a material ia enabled to resist forces 
 tending to tear it asunder. Tenacity depends mainly upon density, but 
 is affected by conditions of cooling, drawing out, or development of 
 fibre, temperature, and other causes. The tenacity or tensile strength 
 of materials is usually given in the number of hundredweights or tons 
 necessary to break a bar of the material of one square inch sectional 
 area. 
 
 Tender. — It is the custom to prepare tenders of all large works to be con- 
 tracted for, in the drawing office, in fulfilment of the terms of specifica- 
 tions. Before tenders can be prepared, general drawings and partial 
 details at least of the machine or structure in question have to be made, 
 in order to obtain therefrom approximate weights of all the castings, 
 forgiogs, and plated work, and also to estimate the value of the labour 
 involved. Tracings of the drawings, or sun copies are also sent with 
 the tender or estimate. Sometimes tenders are paid for, but usually 
 there is no compensation in the event of non-acceptance, and lost 
 tenders am.ount to a very high percentage of drawing office expenses. 
 
 Tenon. — A tongue projecting from the end of a piece of timber, and 
 which, with the mortice into which it fits, is one of the commoner joints 
 in wood work. 
 
 Tenoning Machine. — A machine employed for cutting tenons in wood, 
 consisting generally of four saws, two running vertically together, and 
 capable of adjustment sideways for the different thicknesses required, 
 and two running horizontally to cut the shoulders. Or, in more recent 
 machines, consisting of two adze blocks (q.v.), with flat plane iron cut- 
 ters revolving horizontally, and capable of vertical adjustment. The 
 work is then bolted to a sliding table having a horizontal movement in 
 front of the cutter blocks. Sometimes a third cutter is used to take out 
 a central portion, and so form a double tenon. 
 
 Tenon Saw. — A saw which derives its name from the tenon form of joint. 
 It is a thin saw ranging from 8 in. to 16 in. in length, and is supported 
 by a back of wrought iron or brass ; hence called also a back saw. It 
 contains about ten teeth to the inch. 
 
 Tensile Strain. — A strain or pull in a longitudinal direction, and therefore 
 the reverse of a crushing strain. 
 
 Tensile Strength. — The strength necessary to enable a bar or structure to 
 resist a tensile strain ; equivalent to tenacity. 
 
 Tensile Stress. — The stress to which a bar or structure is subject when in 
 tension. 
 
 Tension. — (1) Abody is in tension when it is subject to forces tending to tear 
 or break it asunder in a direction parallel with its axis. (2) The degree 
 of strain put upon a band saw in order to keep it taut for work. It is 
 regulated by means of a weighted lever and rack and quadrant, or by 
 means of a hand wheel, screw, and spring. 
 
 Tension Bar. — A bar which is being subjected to tensile stress. 
 
 Tension Bolts. — Tie bolts (q.v.). 
 
 Tension Rod. — A rod subject to tensile stress. Tie rods (q.v.) are ex- 
 amples of tension rods. 
 
 Terminal Pressure. — Final pressure (q.v.). 
 
 Terms. — The parts of an algebraical or arithmetical expression connected 
 by the signs plus and minus. 
 
 Tesselated Plates. — Often applied to the thin wrought-iron chequered 
 
MECHANICAL ENGINEERING. 371 
 
 plates used as foot plates, the word taTing reference to the form of the 
 chequering, which is produced hy the diagonal crossing of shallow 
 ridges or elevations on the surface of the plate. 
 Test. — (1) Engiaes and machines are usually tested at the works in 
 which they are manufactured, hef ore delivery to their purchasers. The 
 tests are in every case those of a recognised and standard character, 
 and are witnessed in most instances by an appointed and experienced 
 inspector, not the actual purchaser. (2) The tests to which the raw 
 materials of engineers' structures are subjected are extremely numerous, 
 and in some cases very severe. 
 Test Bars. — Bars employed as tests of the quality of metal in any par- 
 ticular set of castings. When large quantities of iron castings are 
 ordered it is customary to have bars run from the same metal as that 
 which is put into the castings. These bars are usually of a 2 in. X 1 in. 
 cross section and about 3 ft. 4 in. long. They are rested upon supports 
 3 ft. apart, and loaded until they break, the amount of their deflection 
 before breaking being also noted. A bad bar will break at 25 owt. , a 
 good one at 35 or 37 cwt., 30 cwt. being a bar of fair average quality. 
 These will deflect \ in. or more before fracture if the metal is tough. 
 Test Cocks. — Try cocks (q.v.). 
 
 Testing Machine. — A machine used for testing the elasticity and strength 
 of materials. In its simplest form it consists of a simple lever very un- 
 equally divided, the proportions between the lengths of the arms being 
 inversely as the weight suspended and the strain on the specimen. The 
 best testing machines are made of a combination of two or more levers, 
 together with sundry other attachments for the adjustment of the levers 
 themselves, and specimen holders, and appliances also for the measure- 
 ment of torsional strains. 
 Test Load. — ^A proof load (q.v.). 
 Test Fump. — A hydraulic force pump (q.v.) is the kind of pump used 
 
 for testing purposes. 
 Test Specimens. — Pieces of material specially prepared for testing, either 
 with or without the aid of a machine. See Specimen Bar, Specimen 
 Plate, Test Bars, Test Strips, Forge Test, &c. 
 Test Strips. — In specifications for boiler and other works in wrought-iron 
 and steel plates, it is usual to stipulate that a strip shall be cut off each 
 plate to be subjected to suitable tests by the engineer or inspector ; 
 these are known by the name of test strips. 
 Theorem. — A truth capable of demonstration from truths previously 
 
 admitted or proved. 
 Theoretical Quantities. — Quantities which have scarcely any existence in 
 practice, though valuable as standards of reference when making calcu- 
 lations as to the useful effects given out by motive agencies. Thus the 
 modidus of a machine represents its actual value and is a fraction only 
 of its theoretical value. 
 Thermal Lines. — See Adiahatio Curve, and Isothermal Lines. 
 Thermal Unit. — A certain quantity of heat, or its equivalent of work ; 
 used as a standard by which to compare other quantities.. See Unit of 
 Heat. 
 Thermal Value The economic value of a combustible element or sub- 
 stance, estimated according to the number of heat units liberated by its 
 perfect combustion- The thermal value is the same for any substance 
 under similar conditions, whatever be the rate of its combustion. (See 
 Combustion, Products of Combustion.) The thermal values of sub- 
 
372 DICTIONARY OF TERMS USED IN 
 
 stances are higher when the products of comhustion are water instead 
 of steam, "because a certain portion of the heat is absorbed in the con- 
 version of water into steam. See Latent Heat. 
 Thermo-dynamic Engines. — TJsually applied to gas engines, hot-air 
 engines, and engines which derive their motive power from increase 
 and diminution in temperature of the motive force. Steam engines, 
 though thermo-dynamic, are not popularly classed with these. 
 Thermo-dynamics. — The study which treats of heat as a form of energy 
 
 or mode of work. 
 Thermo-kinematics. — Sometimes applied to the study of the theory of 
 
 the motion of heat. 
 Thermometer. — An instrument used for measuring temperatures. An air 
 thermometer is graduated from absolute zero (q-v.) point upwards. 
 Since its readings must be taken in conjunction with those of the baro- 
 meter, its use is confined to scientific researches chiefly. Fahrenheit 
 scale reckons from 32° to 212° ; Centigrade, from 0° to 100° ; Keaumer, 
 0° to 80°. To convert degrees Centigrade into degrees Fahrenheit mul- 
 tiply the given temperature by 9 and divide by 5 (a degree C. being to 
 a degree F. in the ratio of 9 to 5), then add 32. Conversely, to reduce 
 Fahr. to Cent, subtract 32 ; multiply by 6 and divide by 9. 
 Thermostatics. — Sometimes applied to the theory of the equilibrium of 
 
 heat. 
 Thick Eire. — A furnace fire is thick when the fuel is spread to a consider- 
 able depth over the grate bars. It is more economical than a thin fii'e, 
 because the heat of combustion is not so rapidly dissipated, and the 
 fuel is more thoroughly coked. 
 Thickness. — Thickness in a loam pattern signifies that coat of loam which 
 represents the pattern thickness superimposed over the core. This is 
 stripped ofi after moulding, leaving the core intact, which last is then 
 placed in the mould ready for casting. 
 Thioknessing Machine. — A machine used for the purpose of planing stuff 
 to a gauged or parallel thickness, two adze blocks being used, one of 
 which is movable for adjustment to thickness. 
 Thickness Pieces. — Rectangular sti^s of wood gauged to definite thick- 
 nesses, and used by moulders for trying the spaces or metal thick- 
 nesses in their moulds, the strips being laid between cores and the 
 adjacent moiild portions. 
 Thick Oil, or Heavy Oil. — A lubricating oil having much body or viscosity, 
 as castor oil, and used for the heaviest class of machinery, being less 
 liable than the thin oils to become squeezed out from between the bear- 
 ing surfaces. 
 Thimble. — (1) A short cylindrical casting used for connecting the spigoted 
 ends of pipes which lay end to end, or which have been cut off, or have 
 become cracked and broken and have to be reunited without sockets 
 and spigots. A thimble is of the same bore as the socket of its pipe, 
 and is caulked similarly to a socket. (2) A tapered iron mandrel, cir- 
 cular in section, used in smithies for the bringing of rings and holes 
 which have been already roughly shaped under the hammer into a truly 
 circular form, the hole being slid over the tapered portion, and set down 
 on the faces and struck on the outside until it assumes the circular 
 form. Termed also a sugar loaf from the almost precise resemblance 
 of the smaller thimbles in outline and size to a sugar loaf. Also termed 
 a cone simply. 
 Thin Fire. — A boUer fire is said to be thin when the fuel is spread in a 
 
MECHANICAL ENGINEERING. 373 
 
 t.Viin stratum over the fire tars. There is a loss of teat in using a thin 
 fire, though in horizontal internally fired toilers its employment cannot 
 be aToided owing to the contraction in the area of the flue and ash pits. 
 
 IMnning Out. — In boiler Tvork Trhere the circumferential and longitu- 
 dinal joints of the plates overlap (q.v.), it is necessary that the middle 
 plate should be bevelled or drawn down to a feather edge just at the 
 joint, to permit of close and flush fitting. This is called thinning out, 
 or thinning down. 
 
 Thin Oil, or Light Oil. — A lubricating oil having little body or viscosity, 
 as sperm oil, and used for the lightest class of machinery. 
 
 Thoroughfare Hole. — ^A hole carried right through a piece of work, as 
 distinguished from a hole which is recessed only. 
 
 Thread. — The actual helix, or feather, or blade of a screw, as distinct 
 from the solid body or bar on which it is out and by which it is carried 
 and supported. 
 
 Thread Gauge. — A screw -threaded gauge (q.v.). 
 
 Three-cylinder Engine. — (1) There are several types of three-cylinder 
 engines now made. They may be divided into two main classes — those 
 in which the cylinders are placed at an angle of 120° to each other, and 
 those in which they are ranged side by side. In the former or Brother- 
 hood type, the three pistons are of the trunk form, though shallower 
 than ordinary trunk pistons, and three piston rods pivoted loosely in the 
 bodies of the pistons are connected together by bonding, around a single 
 eccentric shaped crank, made solid with the crank shaft. The supply 
 of steam takes place at the end, that is to one side of the three cylin- 
 ders, and is regulated by a valve common to all, which opens and closes 
 the ports in succession. (2) In the other type, in which the cyHuders 
 are placed side by side, their pistons actuate a three-throw crank. In 
 "WHlan's engine the steam is introduced only above the pistons, and the 
 pistons act as valves also for opening and cuttkig off the supply of 
 steam to the other cylinders. The pistons of three-cylinder engines 
 being in equilibrium there is no balancing of reciprocating parts 
 required, and they can be run at a much higher speed and steadier 
 than engines of the ordinary reciprocating type. Hence they are em- 
 ployed for driving dynamos, centrifugal pumps, cicculating pumps, 
 and high-speed machinery generally. 
 
 Three-high MUl. — See Three-high Rolls. 
 
 Three-high EoUs, or Three-high Mill In a rolling Tnill this signifies the 
 
 arrangement of three roUs one over the other, so that the bars or plates 
 may be passed forward tetween the lower pair and backward through 
 the upper ones, without reversing the direction of rotation of the roUs. 
 
 Three-part Box. — ^A moulding box or flask consisting of three parts, and 
 used for moulding those patterns in which the middle section must be 
 distinct from the top and bottom, as, for example, in the case of a 
 grooved pulley. 
 
 Three-ported Cylinder. — The ordinary steam cylinder for the common 
 slide valve, as distinguished from those cylinders having two or more 
 openings leading into each steam passage from the valve face, in cases 
 where double-ported valves and treble-ported valves are employed. 
 
 Three-square File. — A term commonly applied to a file triangnlar in sec- 
 tion, or a three-cornered file. Used chiefly for saw-sharpening. 
 
 Three-throw Crank. — ^A shaft having three cranks forged upon it at 
 angles of 120°, for driving three valves, or buckets, or pistons, and 
 used chiefly for pumps. The cranks being so arranged, are in equili- 
 
374 DICTIONARY OF TERMS USED IN 
 
 trium in any position, and can be nm smootHy at a liigli rate of speed, 
 and also started in any position. 
 
 Three-throw Pump, or Treble-barrel Pump. — A pump having three 
 ■working barrels arranged in line, and having their piston rods con- 
 nected to three overhead cranks set at angles of 120° on a common 
 crank shaft. Equality of motion and a continuous supply are the ad- 
 vantages of their use. 
 
 Three-way Cock. — A cock having three delivery branches, either sockets, 
 or flanges, for diverting the liquid from the inlet branch into two 
 different directions at pleasure. 
 
 Throat. — (1) The enlarged neck of a branch or offset pipe, enlarged and 
 curved for the purpose of diminishing friction and allowing greater 
 freedom of flow for the liquid. (2) The top or opening of an open- 
 topped blast furnace, into which the fuel and ore are charged. (3) The 
 inner edge of the flange of a railway wheel, or that portion which cor- 
 responds with the gauge of the rails. 
 
 Throat Core Box. — A core box used in connection with cast-iron pipe 
 work. It forms the curved portion by which the core of a branch or 
 Tee passes into that of the main pipe. See Throat. 
 
 Throttle Valve. — A flat, thin, disc valve, which lies diagonally within 
 and across a round pipe and closes it partly or entirely. Used in 
 dampers, flues, and engine steam pipes leading from the boiler, to 
 regulate the passage of smoke and of steam. 
 
 Throttling. — The wire drawing (q.v.) of steam in a narrow passage. 
 
 Through Tubes. — The flue tubes of Lancashire and Cornish boilers, so 
 called because they pass from end to end, being attached to the end 
 
 Throw. — The total amount of eccentricity of a crank or eccentric, being 
 equal to twice the radius. 
 
 Throw Disc. — The disc of a slotting machine which actuates the ram (q.v.) 
 through the medium of a short connecting rod. 
 
 Throw-out Gear. — An arrangement of levers and rods by which the mo- 
 tion of a single eccentric is reversed in marine engines. 
 
 Thrust. — The compressive force exercised by a body transmitting pressure. 
 
 Thrust Bearing, or Thrust Block. — (1) The bearing which receives the 
 endlong thrust or pressure of the horizontal shaft of a ship's screw. It 
 is similar in outline to a plummer block, but its bearing portion is 
 grooved circumferentiaUy to receive the thrust collars (q.v.). A horse- 
 shoe thrust block is one in which the bearing grooves are not continuous 
 around, but arched over the shaft only, so that the portions of the 
 shaft collars which are lowermost run in a reservoir of oil, and carry it 
 up to the actual coUar bearings above. (2) The bearing or shouldered 
 portion of a drill spindle (q.v.) where the feed screw and the revolving 
 spindle are in contact. See Thrust Collars. 
 
 Thrust Block. — A thrust bearing (q.v.). 
 
 Thrust Collars. — (1) Collars turned on the body of the shaft of a ship's 
 screw which transmit the endlong thrust to the thrust' bearing (q.v.), 
 the collars fitting into the circumferential grooves of the thrust bear- 
 ing. (2) The compensating collars (q.v.) of drUliag machine spindles, 
 so named because they sustain the thrust due to the reaction of the 
 work against the drill. 
 Thrust Screw. — A screw with or without the power of endlong adjust- 
 ment, which takes the thrust of a revolving spindle. Examples of 
 thrust screws occur at the top of the drill spindles of some drilling ma- 
 
MECHANICAL ENGINEERING. 375 
 
 oUnes, and in the back centres of tlie headstooks of lathes. The bearing 
 end of a thrust screiv may be either flat, or conical in form, and is 
 always hardened. 
 
 Thvimb Plane. — A small plane about four or fire inches long, and having 
 an iron of about an iuch in width, used for small work in general, 
 where a larger plane would be inconvenient. 
 
 Thumb Screw. — A light screw having its head expanded for grasping by 
 the finger and thumb. A wing nut (ij.v.). 
 
 Ticks. — Crows' feet (q.v.). 
 
 Tie. — A bar or member introduced into a structure to resist tensile stress. 
 Ties axe used in trussed beams, in Warren and lattice girders, being the 
 bars which incline downwards towards the centre ; and to receive the 
 pull of the load on crane jibs, and in numerous other positions besides. 
 See Wind Tie, Tie Beam, Tie Kod. 
 
 Tie Beam. — A beam which ties together or prevents the spreading out of 
 the lower ends of the rafters of roof trusses. 
 
 Tie Bolts. — Screw bolts, usually long, which tie or stay large flat and 
 inherently weak surfaces. They are used in bruit up water tanks, as 
 longitudinal stays in Cornish and Lancashire and marine boilers, and 
 for similar purposes in many other structures. 
 
 Tie Eod. — (1) A long screwed bolt or stay, which passes from end to end 
 of a Cornish or Lancashire boiler, and ties or stays the flattened plates. 
 (2) Kods which support or tie the jib or lifting strut of a crane. These 
 rods are subject to very severe stress. Tie rods are also termed tension 
 bolts or tension rods. 
 
 Tightening Gear. — The arrangement by which the cotton or hemp ropes 
 used for driving machinery are kept taut on their puUeys. The usual 
 means of tightening is the employment of weights depending from an 
 idle and adjustable pulley over which the lope passes. See Tightening 
 PuUey. 
 
 Tightening Pulley. — In rope gearing, hygroscopic changes in the atmo- 
 sphere, and the stretching due to straining action causes the lengths of 
 the ropes to vary. To take up the slack, a guide pulley or pulleys are 
 hinged on a sliding bearing plate, moving in guides so that within 
 certain limits the extensions of the ropes are compensated. The pulleys 
 are therefore termed tightening pulleys. In light running cords, driving 
 lathes and other machines from overhead, similar pulleys are em- 
 ployed. 
 
 Tile. — The iron plate or Kd which covers the mouth of a brass melting 
 furnace. So named because a common tile was originally used. 
 
 Tilt Hammer, or Trip Hammer. — An old-fashioned form of smith's ham- 
 mer, used for heavy forging before the introduction of the steam ham- 
 mer. The hammer shaft swings on a pivot : and a revolving cam or 
 wheel furnished with projecting teeth, by pressing down the end of the 
 hammer shaft lifts the hammer, which falls by its own weight directly 
 the cam has passed, to be again Hfted for the next blow by the next 
 cam tooth. Tilt hammers, though to a great extent superseded by tbe 
 steam hammers, are stUl employed both in smithies and in iron, steel, 
 and tin plate works, for forging and for slabbing and blooming down 
 the smaller puddled balls and ingots. 
 
 Tilt Steel. — Blister steel which has been beaten out under a tilt hammer 
 (q.v.). The name is still retained notwithstanding that the work is 
 now done by the steam hammer. 
 
 Tunber, — The various timbers employed by engineers, together with 
 
3/5 DICTIONARY OF TERMS USED IN 
 
 their qualities, defects, preservation, seasoning, &o., are noted nnde» 
 appropriate headings. See "Wood. 
 
 Timber Clamp. — A bar clamp (q.v.). 
 
 Timber Measurement. — ^Timber is measured in various ways. By the 
 superficial foot, reckoned as one inch thick, as in boards ; by the cubic 
 foot, as in logs or beams ; by the standard (q.v.) as board in quantity ; 
 by the load, as in wholesale dealing ; by the hundred, as in deals and 
 battens. 
 
 Timber Back. — A store for timber. There are two kinds of racks, one in 
 which the wood is laid in a horizontal, the other in a vertical position. 
 In the first case the boards are stripped (see Stripping) and laid in bays 
 or compartments ; in the second they stand on end slightly inclined 
 edgeways, leaning against a beam from which round rods of iron pro- 
 ject and act as divisions between each batch of boards. The first mode 
 is used when the boards are actually drying, the second when they 
 have been dried and are considered ready for use. But though boards 
 are never dried while standing on end, they are when dried, often kept 
 in the horizontal position untU required. 
 
 Timber Scribe. — See Scribe. 
 
 Timber Washers. — "Washers (q.v.) of cast or wrought iron used in framed 
 timber works to receive the pressure of the bolt heads and nuts, and so 
 prevent bruising of the timber. "When the bolts pass through the 
 timber in an obhque direction bevelled washers are used. 
 
 Time Sheets, — Printed slips of paper with headings for dates, on which 
 workmen write out each day's time; thatis, the number of hours which 
 they have worked and the jobs upon which they have been engaged. 
 These are collected and sent into the ofBce and checked against the time 
 as given in by the gatekeeper. 
 
 Tin. — Symbol, Sn. ; comb, weight, 11 7'8 ; sp. gr., 7'3. A silvery white 
 metal of immense value in engineering work, chiefly as an alloy in the 
 manufacture of gun-metal, brass, phosphor bronze, Muntz metal, &c., 
 and in the mixing of solders. 
 
 Tine. — An iron or steel claw or fork used in dredging operations. The 
 terms half tine, whole tine, refer to the length of the claws. Any fork- 
 like projection used for piercing or digging would properly be called 
 a tine. 
 
 Tinned Chaplets. — Moulders' ohaplets coated with tin for the same reason 
 as tinned nails (q.v.). 
 
 Tinned Nails. — Moulders' chaplet nails coated with tin to prevent rusting 
 and the consequent formation of blow holes. 
 
 Tinning. — (1) The process of covering sheet iron plates with tin in the 
 tinplate manufacture. It is effected by a succession of processes sub- 
 sequently to the preparatory rolling and piclding. About 340 plates 
 are immersed at a time in a bath of melted tin covered with a thick 
 layer of tallow, and heated to nearly the flashing point of the latter. 
 They are removed in about an hour and a half, immersed in another 
 bath of tin, hfted out, brushed and plunged into melted tallow, and 
 allowed to drain. They are then dipped into a hot pot to remove 
 the rim of metal along the bottom edge, cleaned in bran, sorted and 
 packed. (2) The coating of a soldering iron with tin previous to use. 
 
 Tin Ore. — See Tinstone. 
 
 Tin Plate. — Thin sheet iron coated with tin. 
 
 Tinstone, or Tin Ore. — The ore of tin occurring in the condition of an 
 oxide. It is found in Cornwall, Malacca, Banoa, Australia, Bohemia, 
 
MECHANICAL ENGINEERING. 377 
 
 and Saxony. That from Malacca and Banoa is known as Straits' tin, 
 or Banca tin. See Stream Tin, Mine Tin. 
 
 Tipping Bucket— See Skip. 
 
 Tire.— See Tyre. 
 
 Titan Crane. — A massive type of block-setting crane similar to a Hercules 
 (q.v.) in lifting capacity and general form, bnt diiiering therefrom, in 
 that it is not provided -with motions for slewing. It consists of a 
 travelling carriage bnUt np and properly braced, spanning the pier or 
 breakwater, and travelling on raUs. A traveller and lifting crabs are 
 mounted on this, so that there are three sets of motions available, one 
 of the Titan framework longitudinally, another of its traveller, also 
 longitudinally, carrying the crab, and a third of the crab transversely. 
 Hence a considerable range in the setting of the blocks is practicable. 
 Titans are driven by steam power, the engines being at the hinder 
 end. 
 
 Titanic Steel See Titanium. 
 
 Titanium. — Symbol, Ti. ; comb, weight, 48. One of the rare metaUic 
 elements which is sometimes found associated with grey pig iron and 
 with the slags of blast furnaces, and is also purposely alloyed with tool 
 steel, or steel required for cutting purposes, hence called Titanic 
 steel. 
 
 Toe. — The lower or bearing end of a vertical spindle which rests in or 
 works in a footstep (q.v.). 
 
 Toe Step.— See Footstep. 
 
 Toggle Joint. — A form of lever knuckle joint by means of which great 
 power is obtained. It consists essentially of two lever arms forming an 
 angle with each other and hinged at the centre, the opposite end of one 
 lever being hinged on a fixed pivot, the opposite end of the other being 
 free to move. Any attempt to straighten the levers, that is to bring 
 them into, or nearly into Ime, causes enormous pressure to be exerted 
 at the ends. This form of joint is used in various presses. 
 
 Tommy. — A pointed round iron bar or lever used for insertion in the holes 
 drilled in the circular back nuts of lathes and other machines, for the 
 purpose of tightening them up. Also a metal rod kept for insertion in 
 the eyes of the tightening screws of hand-restsockets, for tightening 
 the X ""sst. Sometimes called a podger. 
 
 Tommy Hole. — A small hole drilled in a circular nut or similar machine 
 part, and into which the point of a tommy is inserted for tightening up. 
 
 Ton. — The highest unit of weight employed in Enghsh practice. It con- 
 tains 20 cwt., or 2,240 lbs. The Cornish mining ton is 21 cwt. 
 
 Tongs. — A smith's tool made in diversified forms and used for holding 
 the work which is being operated upon. See Flat Bit Tongs, Pincer 
 Tongs, Crook Bit Tongs, Hammer Tongs, Hoop Tongs. 
 
 Tongue, or Tongue Piece. — This is a short piece of metal or wood project- 
 ing from one portion of a structure and entering into another, in order to 
 ensure steadiness and to prevent overlapping of joints. Or a tongue 
 may simply be of the nature of a guide piece or a check. Hence tongue 
 and tenon are not quite synonymous, a tenon being short and narrow, 
 and used only as a method of jointing ; while a tongue may be long 
 and wide, and used for other purposes besides the making of joints, as 
 for instance a projecting strip screwed on a foundry loam board to give 
 the length of a struck-up core, or to form a groove around the core, 
 would be termed a tongue. 
 Tongueing. — The jointing of the edges of boards by a groove and oorre- 
 
378 DICTIONARY OF TERMS USED IN 
 
 sponding slip, the tongue on tlie edge of one toard fitting into the 
 groove on the edge of its fellow. Tongueing is performed either by 
 cutters set in a revolTing blooli:, or by means of a joiner's plough. 
 
 Tongue Joint, or Split Joint. — (1) A smith's joint made by inserting the 
 tapered end or tongue of a rod into a V-shaped corresponding cleft in 
 the end of another rod for the purpose of making a weld. (2) Also the 
 joint formed by the tongueing of boards. 
 
 Tonne. — A French measure of weight equivalent to that of a cubic metre 
 of distilled water at 4° C, and equal to 1,000 kUos. See MUlier. 
 
 Tool. — Any implement by which mechanical operations are performed, 
 whether by hand or machine. See Hand Tools, Machine Tools, and 
 detaOs under specific names. 
 
 Tool Angles. — See Angles of Cutting Tools, Angle of Eelief, &o. 
 
 Tool Blanks. — Blanks (q.v.) for milling and other cutters. 
 
 Tool Board. — A board supported behind the bed of a lathe as a receptacle 
 for the tools used in turning. 
 
 Tool Box. — (1) A piece of mechanism attached to the cross elides of 
 planing machines, the sHde rests of lathes, the arms of shaping and 
 slotting machines, &c., to carry the cutting tools. Movement is im- 
 parted to the tool in one or more directions by automatic arrangements 
 varying in the different kinds of machines. Tool boxes are usually 
 made in several parts, sliding the one over the other for longitudinal or 
 cross traverse, and often for circular movements besides. The tool itself 
 is clamped with a screw or screws. (2) Any wooden box which is used 
 to contain workmen's tools. Pattern-makers' tools are kept in a chest 
 suitably fitted with trays and drawers ; moulders' tools in an open rect- 
 angular box without any trays or partitions, and furnished only with a 
 cross handle bridging over the top. Titters and turners keep their tools 
 in drawers or in plain boxes. Por outdoor work the erectors' tools, as 
 spanners, ratchet braces, &c. , are put in strong iron-clamped packing 
 boxes with padlocked covers. 
 
 Tool Carriage. — The sliding carriage which traverses the cutting tool in 
 any self-acting machine. The slide rest of a lathe, and the tool box 
 (q.v.) of a planing machine are illustrations. 
 
 Tool Handles. — The adoption of suitable forms for the handles of tools, 
 cutting and otherwise, is not a matter of indifference, but one which is 
 regarded as almost of exceptionable importance by workmen, since few 
 care to use either the tools or the handles used by another man. In 
 most cases the handles are made of wood. Thus files, chisels, gouges, 
 and hand-turning tools have handles of wood bonded with ferrules 
 where the tang is inserted, and the shape of the handles varies in the 
 case of nearly every separate tool, depending upon the way in which it 
 is held. The handles of moulders' trowels are similar in shape to those 
 of small file handles ; the handles of smiths' swages and fullering tools 
 are of withes twisted around the body of the tool ; hammer handles are 
 nearly parallel, and oval in section, but of various lengths. Many tools, 
 as all moulders' tools, except the trowel, have no handles, nor have cold 
 chisels, drifts, .slide-rest tools, any handles. 
 Tool Holder, or Cutter Bar. — A bar of iron or steel used for holding the 
 actnial cutting tools in metal turning or shaping. There are numerous 
 tool holders in use, but they consist essentially of an arrangement by 
 which the tool is clamped in the holder to the angle most suitable for 
 cutting the metal in hand. Some types of cutter holders have the 
 front portion, in which the tool is clamped, perfectly rigid with the 
 
MECHANICAL ENGINEERING. 379 
 
 ahank ; hence in these a pair of right and left-hand holders are neces- 
 sary in each size. In other types the clamping arrangement is made to 
 swivel from one hand to the other, so that one cutter bar in each size 
 is sufficient. These sometimes lack the rigidity of the solid bars, 
 allowing the tool to give under heavy cutting. The advantage of the 
 use of tool holders is that time and material are saved ; time, in draw- 
 ing down and re-tempering, , which are rendered unnecessary by the use 
 of tool points, and material, because a single cutter bar will take a 
 number of small tool points, each of which would otherwise have 
 required its own separate shank. 
 
 Tooling. — The cutting of metals with ordinary cutting tools, as opposed to 
 the shaping of svirfaces by grinding. 
 
 Tool Post. — A circular post attached to the top of a slide rest for the 
 clamping down of the cutting tools. It is pierced with a rectangular 
 hole, through which the tool is slid and clamped with a set screw pass- 
 ing down from above. Tool posts are used only on small lathes, the 
 laSies of larger size being provided with screwed studs and nuts and 
 cross-bars, or with a triangular or rectangular shaped form of clamp. 
 
 Tool Rest. — See Rest, and Slide Rest. 
 
 Tool Smith. — In all large engineering firms there is at least one smith 
 whose sole business consists in forging, hardening, and tempering the 
 steel tools used by the fitters, turners, and machinists. The experience 
 which this tool smith gains relative to the tempers required for different 
 kinds of steel and different kinds of work, renders it simply a matter of 
 economy to entrust to him alone the preparation of the workmen's 
 tools. 
 
 Tool Stay. — A lathe stay used for the purpose of preventing drills, and 
 double-edged cutters which are driven by the poppet centre against 
 their work, from being rotated thereon. It is a slotted bar held in the 
 socket of the 1" rest, the slot of which embraces the flattened shank of 
 the boring tool. 
 
 Tooth.— See Wheel Teeth. 
 
 Tooth Block. — The block from which the teeth of gear wheels are moulded 
 in a wheel moulding machine. It consists of a rectangular block, which 
 is both long and wide enough to be embraced by the carrier of the 
 machine, or about 9 in. x 4in., and of theexactdepthof thewheel. It 
 carries two teeth precisely Hke those required for the wheel, except that 
 their outer flanks are chamfered away to well clear the sand of the 
 tooth mould last rammed up. The inter-tooth space alone forms the 
 tooth mould, and the block is moved roimd to a distance of one tooth 
 after each inter-space is rammed. 
 
 Toothed Gearing. — Wheel gearing (q.v.). 
 
 Toothed Segment. — Large gear wheels are seldom cast in a single ring by 
 reason, first, of the enhanced difficulty attendant upon the making of 
 large eastings, and, second, their inconvenience as regards transit, fix- 
 ing, and subsequent repair. These are therefore commonly cast in 
 segments of six, eight, or ten to the circle, and either bolted to their 
 arms or to something which forms a suitable base, as the shrouding of 
 a water wheel. 
 
 Toothed Wheel. — See Wheel Gearing. 
 
 Top and Bottom Tools. — See Swage. 
 
 Top Card. — An indicator card taken from the top of a vertical, or oscil- 
 lating cylinder. In the top card the lead line (q.v.) is on the left-hand 
 side. 
 
38o DICTIONARY OP TERMS USED IN 
 
 Top Face. — That face of a casting or mould wMcli is uppermost in pour' 
 ing. It is unsound as compared -with the bottom face. 
 
 Top Iron. — The curved upper iron -which is screwed to the cutting iron of 
 a -wood -working plane. The function of the top iron is to impart 
 rigidity to the cutting iron. This it seems to do simply by exerting' 
 pressure upon the cutting edge, and not by breaking the continuity of 
 the shaving, as many suppose. 
 
 Top Part. — The upper portion of the boxes, or the top box alone, in a 
 foundry mould ; or sometimes the upper part of the mould itself. 
 
 Top Fuller. — A fullering tool (q.v.) -which is held in a hazel rod (q.v.) and 
 struck by the sledge. See iFullering. 
 
 Topping, — (1) The reduction of the tops of sa-w teeth to a uniform level 
 previous to sharpening. The topping is necessary to ensure the simul- 
 taneous cutting action of all the teeth, and is performed by passing a 
 file over them once or twice in a longitudinal direction previous to 
 sharpening. In circular saws it is done by holding a piece of stone to 
 the tops of the teeth -while the saws are revolving. (2) The breaking 
 off of the unsound and hoUo-w top portions of steel ingots -which have 
 sunk or become hoUo-w in the centre. 
 
 Top Print. — ^A print (q.v.) -which is placed on the top face of a pattern. 
 It is rendered necessary -when the core is too long and slender to be 
 supported truly by a bottom print alone, or -when, though it might be 
 supported, the shape of the mould is such that it cannot be centred by 
 measurement in the top pre-vious to closing of the mould. The top print 
 then guides and steadies it in correct position. 
 
 Top Bake. — In cutting tools, signifies the angle -which that part of the 
 cutting face that lies immediately behind the tool point makes -with the 
 horizontal. The top rake -will vary from zero in tools cutting the 
 hardest metals, as chilled rolls, do-wn to 15° in -wood-cutting tools. Top 
 rake is either front top rake, -when it is sloped backwards direotly from 
 the point, or side top rake, or side rake, -when it simply slopes from the 
 side or transversely to the front. In the latter case the tool is spe- 
 cially adapted for side cutting, -which it -will not effect so sweetly -when 
 front rake alone is given. 
 
 Top Steam. — The steam -which enters above the piston in a double-acting 
 steam hammer (q.v.). 
 
 Torsion. — A body is subject to torsion -when two equal and opposite forces 
 forming a couple (q.v.) act upon it in directions at right angles -with 
 its axis. It may be defined as the strain to -which a bar or shaft is 
 subject tending to twist it. 
 
 Torsional Stifiness. — That amount of rigidity of a shaft by -which it is 
 enabled to resist, not simply such strains as -would produce actual twist- 
 ing off, but also such excessive vibration as -would prevent it from 
 doing its -work -with due steadiness. 
 
 Torsional Strength. — The strength necessary to enable a bar or structure 
 to resist a torsional strain. The strength of a shaft to resist torsion 
 varies as the cube of its diameter. 
 
 Torsional Stress. —The stress to -which a bar or structure is subject when 
 in torsion. 
 
 Tossing. — A process of tin refinery which is sometimes substituted for 
 boiliug(q.v.). The molten metal is lifted in ladlesful to a considerable 
 height and poured back into the bath, the effect being to oxidise out 
 the impurities by bringing them into contact with the au" during their 
 descent. 
 
MECHANICAL ENGINEERING. 381 
 
 Total Heat. — The total heat of steam, or the total heat of vaporisation, ia 
 the Slim of both the sensible and latent heats, including also that ■which 
 is engaged in overcoming the resistance of the atmosphere. 
 
 Total Pressure. — The total pressure of steam is that reckoned from the 
 point of no pressure, or absolute pressure (q.v.). 
 
 Total Wheel Base.— See Wheel Base. 
 
 Touch Hole. — The aperture through which the charge of a gas engine ia 
 ignited. 
 
 Tough Brass. — Brass which is suitable for engine bearings and wearing 
 parts. It is rather a vague term which might mean either a superior 
 quality of brass, or gun-metal simply. 
 
 Tough Cake Copper.— See Tough Pitch. 
 
 Tough Iron. — Slippery iron (q.v.) and strong iron (q.v.) are tough irons. 
 
 Toughness. — Toughness denotes the inherent power which a material has of 
 resisting fracture by bending. In tests (see Porge Test) it is measured 
 by the capacity for bending through a definite angle one or more times 
 without sustaining fracture. Toughness and strength are not quite 
 identical, since a material may be strong, i.e. rigid, without possessing 
 toughness, that is, it may be able to sustain great tensile force up to a 
 certain point and then give way suddenly without previous warning. 
 Thus chilled iron, and silicious iron are strong in this sense, but lack the 
 quality of toughness. Hence for structures subject to tension, tough- 
 ness is to be preferred to rigidity, while for those in compression the 
 latter is the principal quality required. 
 
 Tough Pitch. — Blister copper after the process of refining by roasting, 
 melting, and poling (q.v.) is said to be at " tough pitch." The pro- 
 cess is called toughening, and the ingots cast in this condition are 
 called " tough cake "copper. Atestingotiscast, and when hammered 
 red hot should show no cracks at the edges. 
 
 Tow. — See Hemp. 
 
 Tracing. — The making of copies of drawings by tracing over the lines on 
 the drawing or copy, upon a semi-transparent tracing paper (q.v.), or 
 tracing cloth (q.v.) laid thereon. It effects a great saving of time when 
 a number of copies are wanted, and being quite an automatic task is 
 done by lads. A mounted tracing is a tracing pasted on thin calico to 
 preserve it from becoming torn. 
 
 Tracing Cloth. — A specially prepared cloth glazed on one side and rough 
 upon the other, used instead of tracing paper (q.v.) in making tracings 
 for shop use, for which ordinary tracing paper would not be suffi- 
 ciently strong. 
 
 Tracing Machines. — ^Wood-working copying machines used for working 
 the tracery of panels, &c. The cutter is afiixed to the end of a 
 movable radial arm, and a collar affixed to the collar of the spindle 
 follows the outline of a templet of the form to be cut ; sharp angles and 
 corners are of necessity finished by hand. See also Copying Machines. 
 
 Tracing Paper. — Tliin semi-transparent paper used for copying drawings 
 placed underneath. It is made by soaking tissue paper in a solution 
 of resins, or a varnish. Spirits of turpentine and Canada balsam are 
 the agents chiefly employed. 
 
 Tracks. — A term sometimes employed to designate the top faces of the 
 bearers of a lathe bed, as flat tracks, V tracks. 
 
 Traction. — Locomotion by virtue of the frictional adhesion of wheels. 
 
 Traction Engine, or Koad Locomotive. — An engine of the locomotive 
 type provided with large ribbed wheels for traction on common roads. 
 
382 DICTIONARY OF TERMS USED IN 
 
 Tractive Force. — The amount of force necessary to enable a locomotive 
 or animal to overcome tlie resistance due to gravity, incline, vceiglit, 
 and also to travel at a definite speed. The tractive force necessary^ to 
 move a train on a level line must be sufficient to overcome the friction 
 of the -wheels on the rails, the resistance of the friction of the axles, and 
 the resistance due to the air. 
 
 Trade Marks. — See Brands. 
 
 Trailing Axle. — The hinder axle of a locomotive. 
 
 Trailing Lengths. — Those portions of the coupling rods of a fully coupled 
 locomotive which extend backward to the trailing wheels (q.v.). 
 
 Trailing Springs. — The springs which carry the axle boxes of the trailing 
 wheels of locomotives and railway stock, and which sustain and mini- 
 mise the shocks due to concussion. They arc made similarly to leading 
 springs (q.v.). 
 
 Trailing Wheels. — The hinder wheels of a locomotive. 
 
 Train. — Parts of machines similar or identical in form arranged in series. 
 Thus the rolls of puddling mills are termed the forge train. A number 
 of wheels mutually dependent are termed a train of gearing, &c. 
 
 Train of Gearing. — An arrangement of wheels and pinions by which 
 power is gained in the one direction or speed gained in the direction 
 opposite. See Simple Train, Compound Train. In a train of gearing 
 the power or speed of each wheel is inversely as its radius, diameter, 
 circumference, or number of teeth, and the product of the series is ia 
 geometrical ratio. 
 
 Train of Wheels See Traia of Gearing. 
 
 Train Oil.— See Whale OH. 
 
 Trammel Heads. — See Trammels. 
 
 Trammelling Off. — The taking or measuring off of important lengths and 
 centres by means of trammels. This is the only correct method recog- 
 nised in the shops, rule measurement being inadmissible. Small dis- 
 tances and centres are similarly transferred with compasses or dividers. 
 
 Trammels. — Beam compasses, in which the heads slide along a straight 
 bar ; they are tightened by set screws, and are used to strike radii too 
 large for the capacity of ordinary compasses. The heads are made 
 indifBerently of brass or of boxwood, the former being the better of 
 the two. The steel points are inserted into the bodies, and frequently 
 a socket for lead pencil is provided at the side of one of the heads. 
 
 Tram Wheel. — A flanged wheel constructed to run on rails. 
 
 Transfer of Heat. — Refers specially to the transmission of heat from a 
 boiler furnace to the water within. (See Heating Surface.) Rapidity 
 of circulation (q.v.) is necessary to prevent destructive overheating of 
 the plates, which would soon happen if the heat transferred from the 
 furnace were not carried away rapidly by the water. Incrustation (q.v.) 
 and sooty accumulations iaterfere with the transmission of heat. Thin 
 plates conduct more rapidly than thick ones, the rate of transmission 
 being directly proportional to the thickness of the plates. Furnace 
 area is more efficient than tube area, because of the greater concentra- 
 tion of heat there. The rate of transmission signifies the number of 
 heat units transferred per hour, but the amount of heating surface will 
 vary ia different types of boilers. 
 
 Transmission of Heat. — See Transfer of Heat. 
 
 Transmission of Power. — When power is transmitted through shafts, 
 wheels, belts, &c., the amoxmt of horse-power that is transmitted varies 
 as the speed. But at high speeds this general rule becomes modified. 
 
MECHANICAL ENGINEERING. 383 
 
 Transoms. — The transverse distance or stretcher pieces placed between 
 the longitudinal sleepers of permanent way. 
 
 Transverse Axis. — The right line which passes through the vertices of a 
 curve, or through the longest diameter in the case of an oval or ellipse, 
 or through the vertical height of a parabola. 
 
 Transverse Section. — A section (q.v.) taken across at a right angle to the 
 longitudinal direction of a drawing. 
 
 Transverse Strain. — That kind of strain to which a har or structure is 
 subject when it rests upon supports, the load being placed between 
 the supports. 
 
 Trapezium. — A quadrangular figure which has no sides parallel. 
 
 Trapezoid. — A quadrangular figure which has two sides only parallel. 
 
 Travel. — The amount of extreme Huear movement of a piston or valve, or 
 of their rods. 
 
 Traveller, Overhead. — See Overhead Traveller. 
 
 Travelling Crane. — This has reference chiefly to steam cranes which are 
 furnished with gearing to enable them to travel along Hues of rails, the 
 term portable being applied rather to cranes travelled by hand. 
 
 Travelling Gear. — The gear by which the motions of a travelling crane 
 are actuated, usually embracing friction clutches on the engine or inter- 
 mediate shaft, whose motion is communicated by a vertical shaft to 
 bevel wheels, one on the vertical shaft and the other on one of the wheel 
 axles of the truck, with or without the aid of a pitch chain. 
 
 Traverser. — A low flat carriage containing a capstan, usually driven by a 
 stationary engine fixed on the carriage, and used for the purpose of 
 hauling railway trucks about on sidings. 
 
 Traversing. — The motion for longitudinal cutting in a self-acting lathe. 
 It is accomplished either by means of the leading screw and clasp nut 
 or by means of a rack and pinion. Usually in lathes furnished with 
 both sets of gear the turning is accomplished by means of the screw, and 
 the racking back by means of the pinion. The movement effected by the 
 rack and pinion is called the hand traverse, to distinguish it from the 
 traverse effected by the leading screw. The term traversing is also 
 appKed to numerous motions of machines, as the longitudinal motion of 
 a shaping machine head, the transverse movement of a tool box effected 
 by a traversing screw, &o. 
 
 Traversing Drill. — See Slot Drilling. 
 
 Traversing Head. — The head of a shaping machine comprising tool box 
 and ram, which is made to slide along its bed, to distinguish it from 
 those heads which have a motion in one direction only. See Table 
 Feed. 
 
 Traversing Mandrel. — A headstock sliding mandrel used for cutting 
 ornamental screw threads. It is furnished with interchangeable guide 
 screws at the tail end, which screws work in an eccentrically fixed 
 brass plate cut out round its circumference to corresponding pitches. 
 Hither one set of threads in guide screw and plate being placed in gear, 
 and the plate fixed, when the lathe is started the mandrel slides for- 
 ward in its bearings to the extent permitted by the brass plate, and 
 traverses any work attached to it against a cutter set in the rest. This 
 therefore is the reverse of the ordinary screwing process in the screw- 
 cutting lathe, inasmuch as in this case the mandrel travels, the tool 
 remaining fixed. It is useful chiefly for short screws and for orna- 
 mental threads, and is scarcely employed by engineers. 
 
 Traversing Screw. — Any screw employed in machine construction for tha 
 
384 DICTIONARY OF TERMS USED IN 
 
 purpose of drawing along a movaUe Hook or carriage, a tool box or a 
 saddle for instance. The screw does not traverse — that is, it has no 
 endlong motion — hut as it revolves it caixies along a nut attached to 
 the movable sUde. 
 
 Traversing Screw Jack. — A- jack (q.v.) which is made to travel longitu- 
 dinally upon its base by means of a horizontal traversing screw turning 
 in bearings on the base. 
 
 Tread. — (1) The upper portion of a rail upon which the wheels run. 
 (2) That portion of the wheel which runs on the rail. (3) The bearing 
 faces of a lathe bed. 
 
 Treadle, or Foot Board. — A strip of wood actuated by the foot and con- 
 nected to the crank of a lathe, grindstone, drill, or other small machine 
 by a crooked rod or chain, through which the vertical motion of the 
 foot is converted into a rotative movement on the crank shaft. 
 
 Treble Barrel Pump. — A three-throw pump (q.v.). 
 
 Treble Clack Box. — A treble valve box (q.v.). 
 
 Treble Gear. — The combination of three pinions and three wheels in train 
 for the increasing of mechanical effect. 
 
 Treble Geared. — A lathe is treble geared when it is provided with two 
 back gear spindles (see Back Gear) , as distinguished from one which is 
 double geared (q.v.). Treble -geared drilling machines are those having 
 three pairs of gears on two vertical spindles, so that the drill can be 
 fed at three different speeds, the wheels on the second and third spindles 
 being adapted for throwing into and out of gear. Treble-geared lathes 
 are rather exceptional, being reserved for the heaviest work, and treble- 
 geared drUling machines are chiefly hand machines where it is desired 
 to drill holes of an inch in diameter and upwards. 
 
 Treble Ported Slide Valve. — An exhaust relief valve (q.v.) in which the 
 steam gains access to the cylinder through two narrow ports in the 
 body of the valve in addition to the end supply, and exhausts through 
 two ports in the cylinder on each side of the exhaust. Its function is 
 similar to that of the double-ported sUde valve (q. v.) , being only an 
 extension of the principle. 
 
 Treble Purchase. — A combination of gear in which three pinions and 
 three wheels are engaged, the velocity ratio being equal to the pro- 
 duct of the radii of the wheels divided by that of the radii of the 
 pinions. 
 
 Treble Riveting. — Three rows of rivets pitched parallel in a longitudinal 
 direction, but whose middle row is placed intermediately with the others 
 in the transverse direction. 
 
 Trebles, or Lattens. — Sheet iron plates prepared for tinning, whose thick- 
 ness ranges between No. 26 B. "W. Gr. (-020 in.) and No. 27 B. W. G. 
 (-016 in.). 
 
 Treble Valve Box. — A pump valve casing, provided with suction and 
 delivery valves and an intermediate check or retaining valve. The feed 
 is then rendered continuous ; used on portable or stationary engines for 
 piunping to the boiler. 
 
 Tree Feller. — A reciprocating saw driven directly from a steam cylinder 
 of long stroke, used for felling trees or sawing trunks and logs. The 
 saw cuts on the backward or return stroke only, to avoid the risk of 
 becoming bent. Several tree fellers may be worked at once from a 
 portable boiler. 
 
 Trenails. — Wooden spikes u.sed for holding railway chairs down on their 
 deepers. The timber from which they are made is compressed, and 
 
MBCHANtCAL ENGINEERING. 385 
 
 moisture excluded, so that the trenails swell in their holes and prevent 
 the chairs from becoming' slack. They are used in combination with 
 spites, usually two spikes and two trenails to a chair. 
 
 Tresses. — Trestles (q.v.). 
 
 Trestles, or Tresses. — ^Light narrow stools or supports with spreading 
 legs, standing about 2 ft. 7 in. high, and used for laying drawing boards, 
 patterns, foundry loam boards, core bars, and Ught work generally 
 upon. They are made in wood and in iron, iron trestles being chiefly 
 for foundry use. The trestles ia common use are flat on their upper 
 faces ; those for core bars are notched to receive the journals of the bars. 
 
 Trial and Error. — A method of obtaining correct results in the production 
 of pieces of mechanism and of tools, commonly resorted to in workshops. 
 It simply means that when the best results are obtained possible with 
 one set of tools, or with one method of construction, that another set of 
 tools, or another method of construction is resorted to in order to detect 
 the errors left uncorrected by the previous method. Thus the pro- 
 duction of surface plates or of straight-edges is essentially one of trial 
 and error. The centring of work in the lathe with chalk is done by a 
 method of trial and error, and numerous other instances will occur to 
 the mind. 
 
 Triangle. — A rectilineal or plane figure which is bounded by three lines 
 or sides. Having all its sides equal, it is equilateral. Having two 
 sides forming a right angle, — a right-angled triangle. With one obtuse 
 angle, — an obtuse-angled triangle. With three acute angles, — an acute- 
 angled triangle. A triangle is the only figure whose shape cannot be 
 altered while the length of its sides remains constant. Hence crane 
 frames and roof trusses are triangles. 
 
 Triangle of Forces. — It is a fundamental principle in mechanics that if 
 three forces (equal or unequal) be represented in magnitude and direction 
 by the three sides of a triangle taken in order, they will produce 
 equilibrium. Hence if three forces, equal or unequal, acting upon a 
 point, are in equilibrium, then the magnitudes of those forces may be 
 represented in a graphic method by the lines of a triangle, the lengths 
 of whose three sides are proportionate thereto, and drawn in the direc- 
 tion in which the forces act. The post, jib, and tie of a crane furnish 
 a common example of the triangle of forces. 
 
 Triangular Compasses. — A compass (q.v.) used for drawing, provided 
 with three movable points by means of which three centre points or 
 dimensions can be taken off, and transferred at once from one drawing 
 to another. 
 
 Triangular Bale. — A rule having three faces, and used with the same 
 object as the triangular scale (q.v.). 
 
 Triangular Scale. — A drawing scale having three faces, each being dif- 
 ferently divided. The dimensions on each side can therefore be set off 
 directly on the paper without resorting to the use of compasses, or 
 without having separate scales at hand. 
 
 Triangnlation. — The designing of the bays in a Warren, or lattice girder. 
 In a Warren girder the triangles are equilateral, in the lattice girder 
 the bases are shorter than the sides, the stresses in the diagonals are 
 proportionally reduced, and the weight is distributed more evenly over 
 the flange ; there being a greater number of apices. Triangnlation is 
 single in the Warren girder, multiple in the various forms of lattice 
 girders. 
 
 Triblet. — (1) A smith's tool, being a round rod slightly tapered, which is 
 
 00 
 
386 DICTIONARY OF TERMS USED IN 
 
 Tised as a mandrel around wliich rings and nuts are finished upon the 
 anvil. (2) The steel core upon ■which tuhes are drawn to produce a 
 smooth interior surface of uniform diameter. See Tuhe Drawing. 
 
 Trimming. — See FettUng. 
 
 Trip Gear. — Valve gear in which the valves are opened and closed by 
 means of cams, levers, or catches. Trip gears include those of Corliss, 
 Cornish, and other engines. 
 
 Trip Hammer. — See TiLt Hammer. 
 
 Triple Expansion Engine. — A compound engine in which the steam is 
 expanded in three separate cylinders, one high pressure and two low 
 pressure cylinders. The triple expansion is rapidly superseding the 
 ordinary two-cylinder compound engines for ocean service. 
 
 Trip Lever. — A lever usually of the bell crank form whose function is 
 the rapid opening and closing of valves. The lever being lifted at the 
 end of one arm for a certain distance moves the valve at the end of the 
 opposite arm, but slipping off at a definite stage allows the valve to go 
 free. 
 
 Tripod Jack. — A screw jack (q..v.) which is supported on a tripod of three 
 iron legs. 
 
 Tripod Vice.— See Tail Vice. 
 
 Trolly. — A low strong truck running on a tramway. Used in engineers' 
 yards for running castings, forgings, and heavy work generally, from 
 one department to another. 
 
 Trolly 'Wiieel. — A single or double-flanged wheel which is attached to the 
 axles of a trolly (q.T.). 
 
 Troughs. — (1) The fire-clay vessels in which the bar iron which has to be 
 converted into steel by the cementation process is placed. Also called 
 pots. (2) Any open vessels containing water, hardening mixtures, 
 sand, or other materials for smiths' use. 
 
 Trowel. — A small tool used by moulders for smoothing over the surfaces 
 of sand, making sand joints, and generally for shaping and finishing 
 surfaces. See Heart, Square, Dog-tail Trowel. 
 
 Truck. — A low carriage, a trolly, a bogie, the carriage of a portable crane ; 
 or in general any low carriage running on wheels. 
 
 True Pitch.— Uniform pitch (q.v.). 
 
 True Screw. — A screw whose pitch is uniform throughout. 
 
 Trumpet Mouth. — See Bell Mouthed. 
 
 Trunk Air Pump. — A marine air pump in which the piston rod is made 
 hollow to enclose the connecting rod, which is jointed loosely within to 
 its lo"wer end. Trunk air pumps are used in cases where space is so 
 confined that the crosshead and links cannot be employed. 
 
 Trunk Engine. — A marine engine the purpose of whose design is the pro- 
 duction of so compact an arrangement that the engine shall be secure 
 from the enemy's shot below the water line. The distinguishing 
 feature consists in the piston rod being hollow or trunk-like in form. 
 It passes through both ends of the oyhnder, being encircled by the 
 piston at its centre, while the connecting rod is|[attached to its interior, 
 the length of the piston rod being saved thereby. Trunk engines are 
 wasteful of steam owing to the large conducting surface of the trunlc 
 being exposed to the air, and are not constructed now. 
 
 Trunk Plunger. — A pump plunger in which the connecting rod, instead 
 of being attached to an eye at the upper end, passes loosely through the 
 central portion, which is hollowed out for its reception, to be attached 
 to the lower end. The principle is that of the trunk engine ((J.t.), 
 
MMCHAmcAL ENGlNEEklNG. 387 
 
 Itltmk Valve. — A term appKed to that form of D slide valve which is 
 made suiiioieutly long to govern the entrance of the steam to ports 
 placed near the ends of the cylinder. It is an antiquated form. 
 
 Tiunuiou. — The centre npon -which an oscillating cylinder moves. Usually 
 cast as part of the cylinder and containing the steam ports. 
 
 Truss. — A diagonal brace employed to receive the thrust of a loaded beam, 
 girder, or shaft. The vertical thrusts on the beam are received and 
 transmitted through the diagonals, which are thus put into a condition 
 of tensile stress. 
 
 Trussed Beam. — A long beam whose power of resistance to bending 
 strains is increased by transmitting those strains through a truss rod 
 (q.v.). 
 
 Trussed Shaft. — A long light shaft rendered rigid by truss rods arranged 
 around it. Trussing is applied to shafts whose length is such as to 
 require some intermediate support, which support it is not convenient 
 to give otherwise than by trussing. 
 
 Trussing. — The affording of support to otherwise weak structures by 
 means of truss rods (q. v.) . 
 
 Truss Eod. — The rod which passes from end to end of a trussed beam and 
 through which the strain due to downward pressure is transmitted. 
 The stratus in a truss rod are those due entirely to tension. Hence it is 
 a tie rod. A truss rod forms an angle with the beam whose strains it 
 receives, its distance from the beam increasing as it approaches the 
 central portions where it receives the thrust of the strut or struts, and it 
 forms with the beam and strut a triangle of forces (q.v.) . 
 
 Truth. — A term of very common use iu workshops to denote accuracy. 
 Inaccurate work, or an inaccurate tool is said to be out of truth ; the 
 getting of a straight-edge or grindstone or square into correct outline 
 is termed truing up. A shaft or a spindle is true when it is straight 
 or in line, and of equal or correct diameter. A piece of stuff is true 
 when of equal thickness, or when not winding ; a cylindrical piece of 
 work is true when it fits to gauge or calipers. AU the tools used for 
 measurement are employed to check the truth of work. 
 
 Try Cocks. — The cocks screwed into a boiler shell at the extreme highest 
 and lowest water marks, which are used to cheek the water gauge itself 
 in the event of the latter becoming choked up or ceasing to act ; the 
 upper one being the steam, the lower the water cock. 
 
 Trying Cocks. — Try cocks (q.v.). 
 
 Trying Plane. — ^A plane used for producing the utmost accuracy attain- 
 able in the surfacing of wood by hand. Its length is commonly 22 in., 
 and the width of its iron 2|- in. The iron is sharpened straight trans- 
 versely, and this combined with the length of the plane enables very 
 true surfaces to be produced by its use. It is used after the jack plane. 
 
 Trying Up. — The planing of the surfaces of wood true, that is, straight 
 and out of wiading and at right angles with each other; hence 
 the terms trying plane (q.v.), trying up machines (q.v.), try square 
 (q.v.). 
 
 Trying Tip MachiJies. — "Wood-working machines for planing timber, 
 
 ' usually appHed to those machines used for the heavier railway timbers 
 for wagons, trucks, &c., in which the cutters are fixed on the face of 
 a circular disc. 
 
 Try Square. — The ordinary square, consisting of thick stock and thin 
 blade, used for checking the accuracy of the edges of work. The term 
 is used to distinguish it from the set square (q.v.). 
 
388 DICTIONARV OP TERMS USED IN 
 
 Tnte. — A pipe of wrought iron or trass. It is either welded, or solic 
 drawn. Cast-iron tube is termed pipe, or piping. 
 
 Tube Cleaner. — A stifi brust or metallic scraper screwed to the end of a 
 rod and used for cleaning the soot out of the tubes of locomotiTe, por- 
 table, and marine boilers. 
 
 Tube Cutter. — An instrument by which wrought-iron tube is embraced 
 in a curved or hollowed portion provided at the end, and cut by a 
 smooth-edged, hardened steel roller actuated by the handle or lever of 
 the cutter. Tube cutters of circular form are also made for cutting off 
 boUer tubes from the inside. 
 
 Tube Drawing. — (1) The periodical taking out of the tubes of multitu- 
 bular boilers for the purpose of thorough examination. This should 
 be done at intervals of from five to ten years. (2) The manufacture of 
 tubes in various materials by drawing them through a draw plate, with 
 or without the aid of a triblet (q.v.) . The tubes thus made are either 
 drawn through at a welding heat and so united, or they are welded 
 or brazed first, and then drawn to impart the necessary finish to their 
 exterior and interior surfaces, or they are solid drawn, that is, cast and 
 drawn, or drawn from a semi-fluid mass only. 
 
 Tube Dzpander. — A tool used chiefly by boUermakers for expanding or 
 increasing the diameter of wrought-iron or brass tubes for steam boilers 
 in their tube plates (q.v.). There are several forms in use, but in prin- 
 ciple they consist of a central mandrel, tapered in form, by the screwing 
 in of which an outer tube or rollers are both turned round and increased 
 in diameter when placed within the boiler tube and rotated. 
 
 Tube Ferrules. — The ferrules of condenser tubes. See Perrule. 
 
 Tube Plates. — The plates into which the tubes of multitubular boilers, or 
 of surface condensers are inserted and fastened. 
 
 Tube Plug, or Tube Stopper. — A plug of wood driven into the end of a 
 leaky boiler tube to render it temporarily water tight, or until it is con- 
 venient to replace it with a new tube. 
 
 Tube Scraper. — See Tube CJeaner. 
 
 Tube Stopper. — See Tube Plug. 
 
 Tube Surface. — The total area of the exterior surface of the tubes in a 
 surface condenser. The extent of this area is variable in different 
 engines, being dependent on the efficiency of the cold water circulation, 
 but it may be taken to average one square foot for every three to five 
 pounds of steam condensed per hour. 
 
 Tube Vice. — A clamping apparatus fitted with a vertical screw, and used 
 for holding wrought iron tube whilst being cut off or screwed. Also 
 termed a pipe vice. 
 
 Tube Wrench. — A pipe wrench (q.v.). 
 
 Tubing. — (1) Tubes. (See Tube.) (2) The insertion of tubes in a boiler is 
 called tubing the boiler. See Tube Expander. 
 
 Tubular Boiler. — A steam boiler provided with small water tubes or 
 pipes to increase the amount of heating surface without unduly adding 
 to the biitk of the boiler. It denotes no one type of boiler in particular, 
 but any form which is provided with tubes, and hence embraces marine, ■ 
 locomotive, portable, vertical, horizontal, and sectional boilers. 
 
 Tubular Compasses. — A pair of drawing compasses whose legs are hollow 
 tubes, within which other tubes move telescopicaUy for the purpose of 
 increasing their capacity. These sliding bars also carry reversible 
 points rotating around pivots, point and pencil on one side, point and 
 ink on the other. 
 
MECHANICAL ENGINEERING. 389 
 
 Tubular Girder. — A box girder (q.T.) of large size. 
 
 Tubulous Boiler. — A tubular boiler (q.v.). 
 
 Tucking In, or Tucking Under. — The thrusting of the moulding sand 
 around and underneatii the lower portions of patterns which are bedded 
 in. (See Bedding In.) Tucking under is not necessary when patterns 
 are turned or rolled over in their moulding boxes. 
 
 Tucking Under. — Tucldng in (q.v.). 
 
 Tue Iron. — See Tuyere. 
 
 Tumbler. — A rumble (q.v.). 
 
 Tumbler Bearing. — A bearing used specially for gantry (q.v.). driving 
 shafts. "When the crab travels along the gantry it carries with it a 
 sleeve bevel-wheel, having a square central hole fitting on and sliding 
 along the square shaft, and driving it, and with it the traveller wheels 
 at the ends. The long square driving shaft, though supported at the 
 ends and by the bevel- wheel on the crab, requires also intermediate 
 support, and this is supplied by three or four tumbler bearings, placed 
 equidistantly, and pivoting on the girder sides. Their peculiarity is 
 that they are movable, being depressed by the crab as it travels along, 
 and returning to their positions again immediately that it has passed 
 over. The commonest and typical form is that of two arms oast at 
 right angles, and having their bearings at their free ends, the point of 
 junction of the two being bossed up to swing on its pivot. Other 
 forms more intricate in design are in use also. 
 
 Tumbling Bay.— A means of testing or ascertaining the performance of 
 a condeusing-engine. The water from the hot well is delivered into a 
 trough and made to circulate over and under plates of metal. The 
 water escapes from the trough through a notch of definite width cut in 
 a thin plate of brass. This is called the tumbling-bay. The tempera- 
 ture of the water which tumbles over is taken by a thermometer, and 
 the quantity passing per minute is ascertained by the difierence in 
 height of the notch and of the water in the trough itself. Kiiowing 
 the quantity therefore which passes per minute and comparing the 
 temperature of the injection water with that of the water which falls 
 over the tumbling-bay, the amount of heat lost per indicated horse 
 power can be ascertained. 
 
 Tungsten. — Symbol, AV. Comb, weight, 184. A rather rare metal which 
 is of interest to the steel manufacturer from the beneficial eifect which 
 it produces in combination, making, when the amount of tungsten 
 present does not exceed from one to three per cent, a very pure silvery 
 white steel of uniform crystallization, both hard and ductile. When 
 present in greater amount, it produces a hard tool steel which does not 
 require further hardening for cutting purposes. Tungsten is derived 
 from the mineral Wolfram where it is combined with ferrous oxide. 
 
 Tunnel, or Shaft Tunnel. — The enclosed space in the stem of a steamer 
 through which the propeller shaft passes. 
 
 Tunnel Bearings. — The propeller shaft bearings within the tunnel (q.v.) 
 as distinguished from the thrust and main bearings. 
 
 Tunnel Head. — A chimney surmounting the charging holes of open 
 topped blast furnaces to carry the flame clear of the charging holes. 
 
 Tup. — The mass of iron which constitutes the hammer head of a steam 
 hammer, being attached directly to the piston-rod on one side, and 
 receiving the hammer block itself on the other. 
 
 Turbine. — A water motor consisting essentially of two horizontal rings of 
 buckets, one ring being enclosed within the other, and its buckets or 
 
390 DICTIONARY OF TERMS USED IN 
 
 clmtes teooimiig the guides to a column of water, whicli having 
 descended "by gravity under a dejmite head, is caused to impinge on 
 the buckets of the outer ring, and turn it by reaction. This is the 
 principle of the outward flow or Foumeyron turbine. In the inward 
 flow or central discharge turbine the method is reversed, the water 
 entering from without and escaping inwards. In the Jonval or down- 
 ward flow tui'bine the discharge is from above downwards. In the 
 Vortex turbine the water is admitted from without and actuating the 
 vanes passes out at the centre above and below ; and the turbine may 
 either be iixed horizontally or vertically. In tie Girard turbine the 
 water does not act by reaction at aU, but impinges on the curved sides 
 of the buckets only. This also can be used in a vertical or horizontal 
 position. Special turbines are also constructed in which improvementa 
 or modifications or combinations of these are introduced, so that from 
 the original simple outward flow of M. IToumeyrou a vast variety of 
 useful motors have been developed. Turbines are high pressure when 
 running under a great head of water up to 300 or 400 feet, the rings 
 being then of small diameter ; they are low pressure when under a 
 small head, and are then of large diameter. Heads as low as 9 in. 
 wfll drive a turbine. Turbines working under a constant head have 
 . their chutes or vanes fixed ; when designed for a variable head, the 
 blades are made movable. With the exception of the Girard type, 
 turbines will work inunersed in water without loss of energy due to the 
 friction of tail water. Their mechanical efficiency ranks very high. 
 
 Turn Carriage. — The bogie arrangement for swivelling the axles of the 
 front wheels of a portable pump to which the drag handle is attached. 
 
 Turned Bolts. — These are used on all good machine and engine work, 
 their holes being driUed or bored to make a good fit. The employment 
 of turned bolts is necessary to prevent the displacement of parts due to 
 vibration. 
 
 Turner. — Turners are a distinct class of men in engineers' factories, seldom 
 leaving the lathe for the vice. The skill of a turner consists chiefly in 
 rapid chucking and in ready manipulation of tools, both in their grind- 
 ing and setting. 
 
 Turnery. — See Machine Shop. 
 
 Turning. — The art of bringing work to circular form in a lathe. Turning 
 is done by hand and machine tools, and in wood and metals ; it is both 
 plain and ornamental, and while some of its productions are of the sim- 
 plest character, others are of the most complex and highly ornate kind. 
 Pattern turning is usually of a simple character, and seldom automatic, 
 being only so when parallel pipes or pillars are done in a sHde rest 
 lathe. Engineers' turning in the machine shop is nearly all done 
 in automatic lathes provided with self-acting sUde rests. It varies 
 from the smallest spindles, screws, pins, &o., to that of the largest 
 crank shafts, cylinders, and wheels. 
 
 Turning Chisel. — An obliquely-grormd doubly-bevelled chisel used for 
 turning smoothly, or finishing the surfaces of woodwork in the lathe. It 
 is not held flat, but at an angle with the axis of the stufil. Much pattern 
 work being of large diameter and necessitating the employment of the 
 scraping or ordinary firmer chisel, that is also frequently though incor- 
 rectly termed a turning chisel. 
 
 Turning Gouge. — A long stiff gouge used for turning or roughing down 
 the surfaces of wood in the lathe. Gouges range from \ to If- in width. 
 
 Turning Lathe. — See Lathe. 
 
MECHANICAL ENGINEERING. 391 
 
 Tnrnlng Over, — The method of moulding' ty TThioh both sides of a pattern 
 are rammed up in succession. Used in opposition to bedding in (c[.T.). 
 See Soiling Ovei'. 
 
 Tnming Point. — That point of a structure around which the statical 
 moments are supposed to act. 
 
 Tumings. — Turnings, borings, and other metallic shavings cut ofB by the 
 processes of turning, boring, drilling, planing, shaping, slotting, &o., 
 are, when of cast iron, utilised in the maldng of iron cement ; when of 
 wrought iron and steel are fagoted or remelted ; when of brass and gun 
 metal are remelted. 
 
 Turning Saw.— See Bow Saw. 
 
 Turning Shop. — See Machine Shop. 
 
 Turning Tools. — For pattern makers' wood turning, consist of gouges, 
 chisels, round nose, diamond points, side tools. For metal turning 
 they comprise roughing tools, spring tools, right and left-hand tools 
 and gravers, the angles of each being modified for use with steel, 
 cast iron, gun metal, and copper. See details under these speci&o 
 headings. 
 
 Turn Over Board. — ^A board used for ramming a pattern upon ; when, 
 first, the pattern is so flimsy that it would otherwise become rammed out 
 of truth, or when, secondly, the quantity of castings required is so large 
 that the use of a board will save the time the moulder would otherwise 
 occupy in making sand joints. Also called bottom board and joint board. 
 
 Turn Over Skip.— See Skip. 
 
 Turn Screw. — A screw driver (q.v.). 
 
 Turntable. — A platform or table used for changing the direction of 
 motion of rolling stock. The table revolves on a circular line of rails, 
 and the top of the table is furnished with rails of the same gauge and 
 height as the permanent way. Turntables, when large, are usually 
 built up with fish-hellied girders and distance pieces ; when small, of 
 cast iron or of a ring of H iron (q.v. ) , across which the plates which carry 
 the rails are laid. Turntables commonly revolve on a live ring (q.v.). 
 
 Turret Kest. — See Capstan Tool Eest. 
 
 Tuyere. — The pipe through which a current of air or blast is conveyed to 
 a furnace. The tuyeres for blast furnaces, cupolas, and smiths' fires 
 are formed on different types, according to the special work which they 
 have to do. In nearly every case they are cooled by a current of water 
 circulating around the nozzle. Also spelt twyere. A smith's tuyere is 
 often called a tue iron. 
 
 Twin Screws. — A pair of propeller screws, right and left handed respec- 
 tively, placed on separate parallel shafts, and designed to neutralise the 
 tendency which each alone would have to produce vibration or rolling. 
 
 Twist. — See Angle of Flexure, Torsion. 
 
 Twist Drill, — A drill grooved longitudinally and spirally for the clearing 
 of the waste material, the swarf or waste passing spirally up the shaft 
 or twisted grooves. A drill of this form need not be periodically with- 
 drawn from the hole for the purpose of affording clearance to the 
 borings, as is the case with the ordinary form, and being circular in 
 section is not so liable to run out of truth in the hole as is a drUl of 
 the common type. 
 
 Twist Drill Grinder. — Since so much of the efficiency and sweet working 
 of twist drills depends on the angle of their cutting lips being main- 
 tained intact, grinding machines have been devised, and are used in 
 most large factories, by which this constant angle is maintained, the 
 
392 DICTIONARY OF TERMS USED IN 
 
 drill being held in a. socket or clip against a rapidly revolving emery 
 ■wheel. 
 
 Twisting Moment. — The measure of the amount of torsion set up in a 
 bar. It is equal to the product of the twisting force into the distance 
 from the centre of the bar at which it acts. 
 
 Twisted Belt. — ^Driving belts are sometimes twisted to secure their better 
 adhesion, and so save the trouble of tightening up. But, as commonly 
 understood, twisting refers to the turmng of a belt through a definite 
 angle, to drive pulleys whose axes are not on the same plane, or to 
 drive machines in opposite directions. See Crossed Belt, Half -crossed 
 Belting. 
 
 Twist Wheels. — See Screw Gearing. 
 
 Two High Mill,— See Two High Kolls. 
 
 Two High Bolls, or Two High Mill. — Two rolls only, one above the other, 
 for rolling bar iron, or plates. In such rolls the bar must, when passed 
 through, be either drawn back over the top, so losing a pass, or the mill 
 must be reversed. See Three High Rolls. 
 
 Two-jawed Chuck. — A lathe chuck having two jaws only opposed to each 
 other. They are either independent, or universal in movement ; in the 
 first case being actuated by distinct screws, in the second by a single 
 screw spindle, whose halves are furnished with right and left-handed 
 threads respectively. 
 
 Two Salt Waters. — Sea water contains -^g of its weight of salt. When it 
 is prevented from exceeding 3-j of its weight in the boilers of a marine 
 engine, no incrustation of moment accumulates. Hence the boilers 
 must be blown out sufficiently often to prevent the density from 
 exceeding two salt waters. 
 
 Two-throw Crank. — An axle or shaft having two cranks forged upon it, 
 the cranks being usually situated at right angles with each other. 
 Used for double cylinder engines and double-barrel pumps. 
 
 Two-way Cock. — Most cocks are two-way cooks, that is, having one 
 passage for the entrance of the fluid, the other for its exit, the valve 
 dividing the passage and regulating the flow. In these therefore the 
 fluid can only pass in one straight channel. See Three-way Cook, 
 Four-way Cock. 
 
 Two-wheeled Barrow. — Barrows having two wheels extending one on each 
 side of the front of the barrow, instead of the ordinary central one, are 
 much used in foundries for wheeling the castings and moulding boxes 
 about, because the risk of their overturning is minimised thereby. Used 
 also in machine and erecting shops and yards for a similar purpose. 
 
 Twyere. — See Tuyere. 
 
 Tymp. — See Tymp Stone, Tymp Plate. 
 
 Tymp Plate, or Tymp simply. — A plate of cast iron over the hearth of a 
 blast furnace which encloses the tymp stone. 
 
 Tymp Stone, or Tymp simply. — The stone which forms the front or 
 top of the hearth in a blast furnace. 
 
 Typical Engine. — Signifies an ideal engine such as could not exist in 
 fact, but which might be imagined to exist if the theoretical values 
 of the principles involved in its construction could be obtained in 
 practice. Also a generic term denoting any engine which might be 
 relegated to a certain type, as a single-acting engine, a portable engine, 
 a compound engine, &c. 
 
 Tyre. — A steel ring which forms the periphery of a truck wheel, or running 
 wheel. It is shrunk, bolted, riveted, or otherwise fastened around a 
 
MECHANICAL ENGINEERING. 393 
 
 ■wheel centre (q.v.), or a Ibuilt up centre of arms and toss, or is lield by 
 some form of continuous retaining ring (q.T.). Tyres are roUed from 
 blooms of Bessemer steel whose section is that of the frustrum of a cone, 
 the centre being punched out and the shape being imparted by roUing 
 on open end rolls. 
 
 Tyre Bolt. — ^A bolt whose head is tapered similarly to that of a tyre rivet, 
 but at a rather more acute angle, and used for the same purpose. The 
 nut is fastened within the rim. 
 
 Tyre King. — See Eetaiaing Rings. 
 
 Tyre Rivet. — ^A form of rivet specially used for fasteniag tyres to wheel 
 bodies. The end which enters through the tyre is conical, the part 
 passing through the body parallel, and the riveted end is formed within 
 the rim. It is therefore a counter-sunk rivet in which the taper of the 
 counter-sunk part is small. 
 
 u. 
 
 U leather, or TJ Packing. — A pump leather packing whose section is that 
 of the letter (J inverted. 
 
 Ultimate Set. — The difference between the length of a specimen plate, or 
 bar, before testing, and at the m.oment of fracture ; and given in per- 
 centage of the length. This amount in conjunction with the reduction 
 of area (q.v.) is a measure of the duotOity of the plate or bar. Siace 
 it is measiured after fracture by laying the broken ends together, it is 
 also termed the set after fracture. 
 
 Ultimate Strength. — Synonymous with the load which produces actual 
 fracture in a structure. The ultimate strength is usually taken as the 
 basis of calculations by engineers, as afiording more definite data than 
 the elastic strength. 
 
 Undercut. — A pattern is said to be undercut when those portions of the 
 pattern which are lowermost in the mould slope beyond the per- 
 pendicular, so that they cannot be drawn out without tearing up the 
 sand along with them. It is the reverse of taper (q.v.). When parts 
 must unavoidably be undercut, the only course is to core these portions, 
 or to hft away the sand around them with a drawback (q.v.). 
 
 Under Frame. — That portion of a truck or wagon which coutaias the 
 bearing springs for the axles, the buffer and drawbar springs, the axles 
 and axle boxes, with their wheels. The under frame itseU consists of 
 soles, or side timbers, headstocks, or end timbers, cross bars, or trans- 
 verse timbers, and diagonals, all formed of timber united with wrought- 
 iron knees and bolts. 
 
 Under Poled. — See PoUng. 
 
 Under -shot Wheel. — A water wheel which receives the water near the 
 bottom of the periphery, and whose motion results from the impulse 
 due to the head of the water. The water is confined between masonry, 
 so that none of its impulse is wasted. 
 
 Unequal Lap. — This is caused by the obliquity of connecting rod (q.v.) . 
 
 Unequal-sided Angles. — See Angle Irons. 
 
 Ungeared. — A lathe or drUling machine is said to be ungeared when it is 
 unprovided with back gear (q.v.). 
 
 Uniformity of Section. — Signifies the proportioning of the several parts of 
 a machine or structure so that no part shall be weaker than another. 
 
394 DICTIONARY OF TERMS USED IN 
 
 in proportion to tlie strain wMoli it tas to bear. If tte sections are 
 not proportioned umformly, an excess of stress will be put upon tbe 
 weaker parts whicli wOl render them still weaker. The increase in 
 diameter of a cottared end, and the increase in diameter of the screwed 
 end of a rod, are illustrations of the maintenance of uniformity of 
 section. 
 
 Uniform Load. — A load which is not a variable load (q.v.), and which 
 therefore does not induce so great stress as the latter. 
 
 TTniform Pitch. — A screw is said to be of uniform pitch when there is an 
 equal distance between the helioes, or blades, as distinguished from 
 increasing pitch. 
 
 Uniform Motion. — Motion, the rate of which is uniformly proportional to 
 the time occupied therein. 
 
 Uniform Strength. — A beam or structure is said to he of uniform strength 
 when the moment of resistance at any point is equal to the bend- 
 ing moment (q.v.) at the same point. In other words, when each part 
 is in an equal condition of strain relatively to its strength. 
 
 Union. — ^A connection joint for water piping made in three pieces, two 
 being nozzles for attaching to the pipes, and the third, a nut screwed 
 internally, having also an internal shoulder which clips a corresponding 
 shoulder upon the nozzle, whose tail end passes through the nut. A 
 ring of india-rubber, or other impervious material is laid between the 
 shoulders before the nut is screwed down. 
 
 Union. Wrench. — A tommy-shaped wrench used for tightening up the 
 joints of union screws. It partially embraces the cu-cular nut, and a 
 hole drilled in the wrench slips over one of the horns cast on the side of 
 the nut. 
 
 Unit Boiler. — A sectional boiler (q.v.). 
 
 Unit of Heat, or Thermal Unit. — Is a quantity of heat which will pro- 
 duce a certain effect, and which is used as a standard by which to com- 
 pare other quantities of heat. The English imit is the Joule, or 772 
 foot pounds, that beiag the amount of work necessary to raiso the tem- 
 perature of one pound avoirdupois of water at or near its temperature 
 of greatest density 39 • 1° P. through one degree ]?. The Urenoh thermal 
 unit is equal to one kilogramme of water raised one degree C. in tempe- 
 rature, and is equal to 3-97 English units. 
 
 Unit of fflass. — ^Any definite weight employed in mechanical calculations, 
 as a pound or a ton. 
 
 Unit of Work. — A foot pound (q.v.). The Erench unit of work is one 
 kilogrammetre, or one kilogramme raised one metre high. It is equal 
 to 7-2331 footpounds. 
 
 Units. — Mechanical units are either those relations of things which have 
 their basis in natural law, or are conventional standards commonly 
 agreed upon as being convenient for calculations. Thus the unit of 
 heat has its foundation in a natural and interchangeable fact, but a 
 horse-power, or a foot pound, are simply conventional rules accepted 
 by the mutual consent and use and custom of engineers. The great 
 primary mechanical units used by engineers are the Joule, or unit of 
 heat (q.v.) ; the foot pound or ton ; the inch pound, or inch ton, and 
 the H.P. But besides these there are many scores of secondary units, 
 as the power of men, the electrical standards, and so forth. 
 
 Unit Strength, — The ultimate unit stress (q.v.) of a material, or that 
 which causes fracture. 
 
 Unit Stress. — The stress upon a unit of sectional area, as a square inob 
 
MECHANICAL ENGINEERING. 395 
 
 or square foot, ■with a given amount of force. Or the ultimate stresa 
 per square inch or square foot of section which -would cause fracture. 
 It is represented by the letter/. In a structure whose sections are 
 subject to various degrees of stress the relative stresses of the several 
 sections are sometimes conveniently referred for comparison to a single 
 primary stress, and this is also termed a unit stress. Thus the unit 
 stress in a "Warren girder is that of the bays next the end, whence in a 
 girder loaded uniformly or at the centre, and having the longer flange 
 lowermost, the stresses increase by simple proportion through succes- 
 sive bays towards the centre. 
 
 Universal Send, — Two bends provided with a swivel joint, so that they 
 can be turned round to any desired angle in relation to each other. 
 
 Universal Chuck, or Concentric Chuck. — A jaw chuck whose jaws are 
 endowed with simultaneous movement for instantaneous centring of 
 the work. The jaws of universal chucks are actuated by gear-wheels 
 working in a common rack, or by a scroll, or by a combination of both, 
 the rack and pinions in this case moving the soroU. They are also 
 moved by means of a key or lever or by hand. All universal chucks 
 must of necessity consist of two main portions, a front and a back plate, 
 or an inner and outer shell enclosing the gearing between them. See 
 Combination Chuck. 
 
 Universal Coupling. — See Universal Joint. 
 
 Universal Joint. — In Hook's gimbal joint the ends of the shafts to be 
 connected are prolonged into forks which svrivel on the ends of a cross, 
 each arm of which also swivels in an arm of the forks. Used for carry- 
 ing shafting round angles of biiildings. Other forms of universal joint 
 are used for pipes and rods, being modifications of the ordinary ball-and- 
 socket or globular joint, the ball being retained in place by means of a 
 flange slipped over it and screwed to an opposing flange. 
 
 Universal Scale. — ^A scale (q.v.) used for drawing purposes upon which 
 aU proportional divisions in ordinary use are engraved in parallel rows. 
 The objection to universal scales is that measurements, except when 
 along the edges, must be taken oft by dividers instead of being set off 
 from the edge directly on the paper. 
 
 Universal Square. — A centre square (q.v.). 
 
 Unstable Equilibrium. — Unstable equilibrium results when the centre of 
 gravity of a body which is in equilibrium is situated at its highest point. 
 
 Unsymmetrical Beams. — Beams whose cross section is irregular considered 
 with reference to the quality of their straining moments. In other 
 words, beams whose centre of moments does not coincide with the 
 centre of gravity. 
 
 Untarred Eopes. — Manilla ropes (q.v.). 
 
 U Packing. — See U Leather. 
 
 Up End, or Up Ending. — A term in frequent use by erectors to signify the 
 standing up of a heavy piece of work upon its end. 
 
 Up Hand. — Up hand signifies the method of using a smith's sledge hammer 
 for light work. The sledge is held in the left hand and lifted and 
 thrown down by the right ; the latter slides freely up and down the 
 shaft. 
 
 Uphand Sledge. — Uphand sledge denotes the lifting of the sledge over the 
 work, in opposition to about sledge (q.v.). See Uphand. 
 
 Upright Chuck. — ^A wooden chuck furnished with a pair of slotted jaws, 
 or with a single jaw only, by which work is held which would not ooa- 
 veniently be held in the hollow or ordinary form, 
 
396 DICTIONARY OF TERMS USED IN 
 
 XTpset, Angle of. — See Angle of Upset. 
 
 Upsetting. — Jumping up (q.v.). 
 
 Uptake. — (1) The internal flue of a vertical boiler leading from the furnace 
 to the outer flue or chimney. (2) The flue of a marine return flue 
 boiler. (See Dry Uptake, and "Wet Uptake.) (3) The short vertical 
 chimney of a gas producer -which forms a communication between the 
 fire-brick chamber and the gas mains. 
 
 Uses. — Rough pieces of metal to be used in the welding (q.v.) of heavy 
 masses of forging. Or any rough heavy mass of metal from -which 
 pieces of mechanism are to be shaped. Uses are prepared at the forge 
 mills and delivered to the orders of customers -who do not possess 
 machinery sufficiently hea-py to forge large masses of material. 
 
 V. 
 
 Vacuo, or in Vacuo. — A term used in calculations on the behaviour of 
 
 faUing bodies and liquids, by which their velocity is referred to that 
 
 of a body falling in a vacuum, or in vacuo; in other words, not subject 
 
 to the retarding influence of the atmosphere. 
 Vacuum. — A vacuum is strictly spealdng a space absolutely devoid of air. 
 
 In engineering it only signifies a space partially empty. Twenty-six 
 
 inches, or thirteen pounds, is a very good vacuum in a condenser. See 
 
 Vacuum Gauge. 
 Vacuum Brake. — A form of continuous brake in which the steam pressure 
 
 actuating through a steam jet or an air pump is made to produce a 
 
 partial vacu-um against which the pressure of the atmosphere then 
 
 operates. 
 Vacuum Engine. — An engine in which the power is generated by the 
 
 explosion of a gas producing a vacuum, the air then rushing in to fill 
 
 the vacuum. 
 Vacuum Gauge. — A gauge used to register the amount of vacuum in 
 
 the condenser of a steam engine or in any vessel in -which a partial 
 
 vacuum is produced by the exhaustion of air. Vacuum gauges are 
 
 dial gauges (q.v.) and are graduated from zero to thirty pounds. 
 Valve. — A movable cover or lid, by means of which the ingress and 
 
 egress of fluids and gases is regulated. There are various kinds of 
 
 valves. See under their heads, ball, bucket, disc, flap, lift, sUde, spiral 
 
 -winged, equilibrium valves, and others. 
 Valve-box. — The box or casing, rectangular or otherwise, in which the 
 
 valves of pumps are placed. Also the steam chest which contains the 
 
 slide valve of an engine. 
 Valve-Bridle.— See Bridle. 
 Valve Casing. — A valve-box, or valve chamber. 
 Valve Chamber. — A chamber which contains a valve, and within which 
 
 it works. UsuaUy understood to denote a steam chest rather than a 
 
 clack or valve box. 
 Valve Chest. — A valve casing or steam chest (q.v.). 
 Valve Circle. — The circle on a valve diagram (q.v.) whose diameter ia 
 
 equal to the half travel of the valve. There are two such circles on 
 
 the diagram. 
 Valve Cock. — A cock of the ordinary outline, gland, lib, faucet, or 
 
 otherwise, which opens -with a lift valve, and hand wheel and screw, 
 
 or by means of a sliding valve ; instead of by the turning of a plug-, 
 
MECHANICAL ENGINEERING. 397 
 
 as in a plug cock (q.v.). A globe valve is therefore properly termed 
 a valve cock. 
 
 Valve Diagram. — A cliagram Iby -wMcli the position of the slide valve for 
 any position of the piston, and conversely the position of the piston for 
 any position of the valve, may be determined graphically. As a con- 
 sequence the relative positions of valve and piston at the instants of 
 opening, cut off, cushioning, release, may also be determined. There 
 are numerous modes of constructing valve diagrams. Dr. Zeuner's 
 being considered the simplest. 
 
 Valve Face. — The face against vrhich a slide valve works or slides, and 
 therefore properly distinguished from a valve seat (q.v.). 
 
 Valve Gears. — The mechanical arrangements for actuating slide valves, 
 both for single and reversing action, embracing slot links, rods, pro- 
 vision for expansion, automatic or otherwise. 
 
 Valve Plates.— See Cut ofE Valve (q.v.). 
 
 Valve King. — An equilibrium ring (q.v.). 
 
 Valve Bod Gland. — The gland which closes the stuffing-box of the rod 
 of a slide valve. It is screwed to the steam chest and maintains the rod 
 steam tight. 
 
 Valve Seat, or Valve Seating. — The bearing surface, annular or otherwise, 
 against which a valve fits when closing or shutting off ; properly 
 applied to the seatings of lift valves and plug valves. 
 
 Valve Sector. — (1) A slot link (q.v.), also termed a quadrant. (2) A spe- 
 cific name for the vertical sliding link of an oscillating cylinder engine 
 which conmiunicates the motion of the eccentric to the valve rod weigh 
 shaft. 
 
 Valve Spring. — A spring of either the plated or spiral form, used for 
 forcing the packing or equilibrium rings of slide valves against their 
 working faces. 
 
 Valve Stem. — A valve spindle or rod. 
 
 Valve Yoke. — The bridle (q.v.) of a valve rod. 
 
 Vanes. — The buckets or guides of turbines, or the flat expansions of 
 blowing fans. 
 
 Variable Expansion. — The expansion of steam in an engine whose amount 
 of expansion is not constant, but capable of alterations under the 
 varying conditions of the work or strain thrown upon it. It may either 
 be automatic expansion (q.v.), or expansion effected through the 
 medium of some type of hand gear, by which either the amount of lap 
 of the main slide valve is altered, or by means of a back cut-oS 
 valve (q.v.). 
 
 Variable Expansion Gear. — See Automatic Expansion Gear, Variable 
 Expansion. 
 
 Variable Load. — See Live Load, Oscillating Stresses. 
 
 Variable notion. — When a body moves over equal spaces in unequal times 
 its motion is said to be variable. 
 
 Varnish. — Shellac varnish (q.v.) is used to protect patterns from the action 
 of the damp foundry sand, in which they are often embedded for several 
 hours at a time, and likewise to furnish a glossy skin, which facilitates 
 withdrawal from the mould. Two or three coats are laid on, the 
 varnish being glass-papered down after each application. In spite of 
 varnish, patterns of considerable width are found to swell in the sand. 
 Hence the necessity for open joints (q.v.), but small patterns remain 
 practically unaffected. See also Lacquer. 
 
 Varying Lap. — To produce variable expansion (q.v.) it is necessary that 
 
398 DICTIONARY OF TEkMS USMD IN 
 
 the amoimt of lap (q.T.) of the slide valve should he rendered oapahle of 
 variation, since that governs the point of out off. 
 
 Varying Lead. — The lead of a valve designed for the same purpose as 
 varying travel (q..v.). It is not employed in practice. 
 
 Varying Load. — A variahle load or live load (q.v.). 
 
 Varying Travel. — The difference in the lengths of travel of a slide valve, 
 in order to furnish the different amounts of lap necessary to effect 
 variable expansion (q.v.). Expansion gears of various kinds are 
 employed with this object, the usual method being to set the sliding 
 block from -which the valve rod receives its motion at a point nearer to 
 or farther from the centre of the slot link. 
 
 Vee'd Edges. — The edges of automatic metal working machines which are 
 embraced by the sliding vee'd portions of the movable parts. The edge 
 of a lathe bed embraced by the sliding rest, or the edge of the cross 
 travel of a planing machine are familiar oases in point. The angles of 
 these edges are commonly 60°. 
 
 Vees. — See Vee'd Edges, Vee Strips. 
 
 Vee Strips. — Loose strips having angles corresponding vrith those of the 
 vee'd edges (q. v.) , along which they sKde, and by means of which the 
 amount of slack due to wear is taken up. Hence called adjustment 
 strips (q.v.). 
 
 Vee Threaded Screw. — The ordinary Whitworth screw of angular thread. 
 See Screw Threads, Whitworth Thread. 
 
 Vee Welding — A mode of welding the plates of boiler flues in which there 
 is neither butt nor lap properly so called, but in which a strip of square 
 rod is inserted angle ways between the nearly abutting edges of the 
 plate, so that it unites the edges upon two sides of the rod. 
 
 Vegetable Oils. — Oils expressed from the seeds of vegetables, and used in 
 lubrication, or for paints. They are either non-drying or drying oils 
 (q.v.), and embrace almond, beech, castor, cotton seed, nut, poppy, 
 hemp seed, oKve, pahn, rapeseed, and other oils. The oil is expressed 
 from the seeds by pressure, or by pressure and heat combined. Eape 
 seed oil is expressed from the seeds of the rape {Brassica napus). It is 
 not a good lubricant used alone, being liable to gumming and acidity. 
 Castor oil and oUve oils are good, and are noted under their headings. 
 See also Linseed Oil. 
 
 Veins. — Lregular wavy markings on the surfaces of castings, which occur 
 when too much blacking has been used in the mould. The metal 
 swells the blacking up into fine ridges, hence the marks. They do not 
 injure the casting, but look unsightly, suggesting to inexperienced 
 eyes incipient lines of fracture. 
 
 Vein Stuff. — Gangue (q.v.). 
 
 Velocity. — The rate at which a moving body changes its position under 
 the action of force impressed upon it from without. Velocity is com- 
 monly estimated in feet per second. It may be either uniform or 
 variable, that is, in the former case when the body passes over equal 
 distances in equal times, in the latter when the space moved over in 
 consecutive seconds varies. Velocity is either linear (q.v.) or angular 
 (q.v.). See also Virtual Velocity. 
 
 Velocity Eatio. — Signifies the proportional velocities of bodies which are 
 mutually connected, as levers, gearing, &c. 
 
 Vena Contracta, or Contracted Vein. — The contraction in area which a jet 
 of water, or other ef&uent liquid undergoes in issuing from an aperture 
 in a thin plate. The reduction of area is in the ratio of -6 to I'O, the 
 
MECHANICAL ENGINEERING. 399 
 
 latter being tlie area of the aperture ; the distance at wliioli the contrac- 
 tion takes place from the opening being about half its diameter. 
 
 Vena Contracta mouthpiece. — A mouthpiece adapted to the vena contracta, 
 being made doubly conical in section, in order to prevent the loss of area 
 due to vena contracta, (q.v.). 
 
 Vent. — ^The calorimeter (q.v.) of a boiler multiplied by the length of the 
 flue in feet is termed its vent. 
 
 Ventilating Bucket. — In overshot water wheels the water as it descends 
 into the buckets would he partially driven out again by the reaction 
 due to the compressed air within the buckets, but for the precaution of 
 leaving a sHght opening between the bucket and sole plate, through 
 which the air escapes ; hence the term. 
 
 Ventilating Fan. — ^Aii ordinary fan (q.v.), used for purposes of ventila- 
 tion. 
 
 Ventilator. — The term ventilator is applied to the revolving grids, usually 
 attached to the doors of Cornish and Lancashire boilers, through 
 which the ingress of air to the fuel is partially regulated. 
 
 Venting. — The venting of a mould is the piercing or honeycombing 
 of the sand of which it is composed, by a long rod of J ia. or J iu. wire, 
 thrust in all directions to allow of the free egress of the gases generated 
 by the decomposition of its moisture, consequent on the heat imparted 
 thereto by the inflowing of the molten metal. 
 
 Vent Pipes. — Lengths of common piping leading up at an angle from the 
 coke bed (q.v.) of a foundry mould, to bring off the escaping gases and 
 carry them outside the edges of the moulding box, where they are 
 ignited and burnt. 
 
 Vent Bope, or Vent String. — Common rope or string rammed up in certain 
 cores and in certain sections of moulds in situations where it would be 
 difficult, or impossible to ram up the usual vent wires, by reason of the 
 sinuous character of the vents. After the ramming is complete the rope 
 or string is withdrawn, leaving the vent or vents curved as required. 
 
 Vent Wire. — ^A rod of iron wire used for piercing a foundry mould with 
 small holes for the escape of the gas generated in casting. Vent wires 
 and rods will range from J in. to |^ in. diameter. 
 
 Vermilion. — ^A bright rich red colour, being a sulphide of mercury, Hg S. 
 Useful for mixing with sheUao varnish to impart a hard and glossy skin 
 to the best foundry patterns. 
 
 Versin. — The versed sine of an angle. 
 
 Vertical. — ^Plumb, or perpendicular to the centre of the earth. A vertical 
 must be perpendicular, but a perpendicular (q.v.) is not necessarily 
 vertical. 
 
 Vertical Boiler. — A steam boiler whose horizontal section is circular. 
 Boilers of this type are used only for small engines, and are more waste- 
 ful than those of horizontal type, the products of combustion passing 
 at once into the chimney. Economy in vertical boilers is obtained by 
 the employment of Field's tubes (q.v.), but in general such boilers con- 
 sist of shell and fire boi only, connected by the uptake (q-v.) leading to 
 the chimney, and having in the larger forms one or two cross tubes 
 (q.v.) in the fire box. 
 
 Vertical Crane. — A steam crane of the ordinary type with tall side frames, 
 as distinguished from a horizontal crane (q.v.). 
 
 Vertical Engine. — ^An engine whose axis is vertical, and which there- 
 fore forms a very numerous type. The advantages of vertical engines 
 eonsist in the small foundation space which they occupy, and equality 
 
403 DICTIONARY OF TERMS USED IM 
 
 of wear on the cylinder, piston, and rods. Very few Tertioal engines 
 are constructed with the cylinder lowermost, and those only of the 
 smallest sizes. Most vertical engines haye the cylinders above, em- 
 bracing the various steam hammer types, launch and screw engines, or 
 inverted cylinder engines. 
 
 Verticals. — The upright members of a lattice girder. 
 
 Vertical Section. — A section (q.v.) taken in a vertical direction through a 
 drawing of an object. 
 
 Vertical Shaping Machine. — A slotting machine (q.v.). 
 
 Vibrating Links. — See Suspension Links. 
 
 Vibration. — Vibration in engineering works is a fruitful soiirce of deterio- 
 ration of material, and if long continued produces fatigue of materials. 
 The vibration produced by heavy caulking, hammering, &c., on rivet 
 heads and seams is also liable to lead to fracture or starting of joints 
 and consequent leakage. To prevent vibration in machines doing 
 heavy sawing, planing, drilling, shaping, slotting, &c., the machine 
 bases are bolted down to large stone or concrete foundations. Steam 
 hammers are not only thus bolted down, but their anvils also are em- 
 bedded on massive anvil blocks. The framings of heavy machines are 
 made hollow the better to withstand vibration stresses ; ties, struts, and 
 distance pieces, &c. , are also introduced into structures for the purpose 
 of minimising the stresses due to vibration . 
 
 Vice. — A common workshop tool employed for holding or gripping work 
 which requires to be held firm, but which is not .sufficiently heavy in 
 itself to remain immovable under the operation of the tools. It con- 
 sists of a pair of steel-faced jaws, one of which is moved by a screw or 
 by a lever, the other jaw being rigid. In the former case the friction 
 of the screw prevents the release of the jaws. In the latter the teeth 
 of a ratchet fulfil the same function. Vices are made in great variety 
 of forms and sizes, the best being those with parallel movement in the 
 jaws. Machine vices are employed for bolting to the tables of planing, 
 shaping, and drilling machines. 
 
 Vice Bench. — A small iron portable bench usually mounted on a tripod 
 and made to carry the ordinary tail vice. 
 
 Vice Cheeks. — ^Vice jaws (q.v.). 
 
 Vice Chuck. — A machine vice (q.v.). 
 
 Vice Clamps. — See Vice Claws. 
 
 Vice Claws, or Vice Clamps. — Angle strips of lead, brass, or copper, used 
 for insertion into vice jaws to prevent the bruising of delicate pieces of 
 work by the serrations of the hard steel faces. They are usually made 
 to cover the serrated jaws and to bend over the upper faces as well. 
 For special purposes vice claws are made in one piece, the two cheeks 
 being united at some distance below the jaws either by a spring joint 
 or by hinges. 
 
 Vice Jaws. — Vice jaws are steel-faced, the faces being screwed to the 
 wrought-iron backing, beingfirst screwedand serrated while untempered, 
 and subsequently removed for hardening, and then replaced. In the 
 smaller vices the steel jaws are instead welded to the iron. Most jaws 
 are thus fixed, but not invariably. See Taper Vice. 
 
 Virtual Velocity. — The law of virtual velocities is simply the expression of 
 a fundamental principle of mechanics, that, namely, that whatever is 
 gained in power is lo.st in time, with its converse axiom ; or that the 
 power multiplied by the space through which it moves is equal to the 
 weight multiplied by the space through which it moves. It is simply 
 
MECHANICAL ENGINEERING. 401 
 
 saying in other -words that hy no mechanical combination can we create 
 force, but only change its mode of application. See Conservation of 
 Energy. 
 
 Viscosity.— See Body, Thick Oil. 
 
 Visible Drop Lubricator. — ^A sight feed lubricator (q.v.). 
 
 Vis Inertia. — The property of iaactivity inherent in matter, by -virtue of 
 -which it resists external ioiiuences tending to make it change its state 
 of rest or of motion. Its equivalent is therefore the force required to 
 put bodies -which are in a state of rest into motion, or to accelerate the 
 speed of bodies already in motion. 
 
 Vis Viva. — See Energy. 
 
 Voltaic Action See Galvanic Action. 
 
 Volume. — A term of general application, signifying the cubical contents 
 of an engine cylinder, a definite amount of steam, or of gas at a definite 
 pressure, or a mass of liquid. The product of the sectional area of a 
 piston and the length of its path is termed its volume. This also is 
 equivalent to the quantity of -water lifted by a pump. In the case of a 
 steam engine the volume multiphed by the mean pressure is equivalent 
 to the gross amount of -work performed. 
 
 Volume, Lines of. — The horizontal or approximately horizontal lines in 
 an indicator diagram of -work. 
 
 Volute Spring. — A flat ribbon like spring coiled in the form of a helix, 
 and extensible in the direction of the breadth of the ribbon. Used as a 
 bufiler spring, and also for driving springs (q.v.). 
 
 Vortex Turbine. — See Turbine. 
 
 Voussoira. — The -wedge-shaped stones of -which an arch is composed. 
 
 Vulcanite. — A compound of india-rubber and sulphur. Used for draughts- 
 men's set squares. 
 
 Vulcanized Eubber.— See India-rubber. 
 
 w. 
 
 Wabblers. — The oouphng-boxes used for connecting the breaking pieces 
 (q.v.) -with the necks of the rolls in puddling rolls. 
 
 Wabble Saw. — A drunken saw (q.v.). 
 
 Wabbling Disc. — ^A swash plate (q.v.). 
 
 Wafters. — The revol-sdng discs or fans in a Koot's blower. See Rotary 
 blower. 
 
 Wagon Boiler. — An old-fashioned, externally fired form of boiler, now 
 rapidly going out of use. It has a semi-circular, or overarching top, 
 shghtly hollowed sides, and flat or arched bottom, the flues taking 
 the form of a wheel draught (q.v.) . Its shape renders it difScult of stay- 
 ing, and though adapted to the low pressures of forty or fifty years 
 ago, it is wholly unsuitable for the high pressures now commonly em- 
 ployed. 
 
 Wall Bearing.— A Wall Box (q.v.). 
 
 Wall Box, or Wall Bearing. — A east-iron open frame, commonly rectan- 
 gular in form, used in cases where shafting is carried through a wall, 
 the bearing or plummer block for the shafting being bolted within the 
 wall box. The box is btult into the masonry of the wall. 
 
 Wall Bracket. — A bracket of approximately triangular outHne bolted to a 
 wall to carry a plummer block for shafting. 
 
 D D 
 
402 DICTIONARY OF TERMS USED IN 
 
 Wall Drill. — A drilling machine tolted to the -wall of a -workshop. It 
 may be either fixed or radial, according to convenience, and the parti- 
 cular class of work -which it is designed to perform. The advantage 
 of -wall drills is -that they leave a clear floor space underneath for the 
 manipulation of hea-vy -work. The -wall is sometimes arched out 
 Tmdemeath the drill to afford still more room for the hauling and turn- 
 ing about of bulky -work. 
 
 Wall Engine. — A type of small vertical steam engine, -whose bed plate is 
 bolted to a -wall. Such engines are convenient for dri-ring sectional 
 lines of shafting, as one set of shafting can then be stopped -without 
 afllecting that in another shop, or in another part of the same shop. 
 They are also used for dri-ving traveUing cranes, foundry fans, &o. 
 The cylinders are lo-wermost and the crank shaft above. 
 
 Wallo-w Wheel. — A bevel -wheel fixed upon a vertical shaft, and having 
 the teeth facing downwards, or the reverse of a cro-wn -wheel. It ia 
 employed in mill -work. 
 
 Wall Plate. — (1) Aflat cast-iron plate or angle bracket, bolted to a wall 
 as a base for the attachment of wall brackets, bearings, &c., for the 
 carrying of shafting, or other portions of machinery. Its function ia 
 therefore that of a base or foundation plate. (2) The plate upon which 
 the ends of roof trusses abut, in order to distribute the strain due to 
 their weight over a sufficiently large area. 
 
 Wall Pump. — Sometimes applied to a donkey pump when bolted to a 
 wall. 
 
 Wall Washer. — A large flat washer against which the ties of buildings 
 are screwed. Or a similar broad washer which receives the pressure of 
 a bolt head or bolt heads used for fastening brackets or plates to that 
 face of the wall which is on the side opposite to that which takes the 
 wall washers. 
 
 Walrus Hide. — ^Walrus hide is used as a covering for bnffs (q.v.). 
 
 Waney Boards. — The outer boards of logs whose edges are chamfered 
 off, and irregular. 
 
 Waney Log. — A squared log or balk of timber whose angles have been 
 adzed ofll. Waney log is therefore more wasteful in the sa-wing up 
 than squared logs, but is cheaper in first cost. 
 
 Warehouse Crane. — A light slightly-made crane, used only for lifting 
 weights ranging usuafly between 10 cwt. and 40 cwt. in warehouses, 
 and commonly worked by hand. See also Whip Crane, Platform 
 Crane. 
 
 Warp. — To pull a load along by the -winding of a rope or chain upon a 
 drum. See also Warping Cone. 
 
 Warping. — (1) The alteration in form, of timber planks, and boards, due 
 to the unequal swelling or shrinking of the fibres by reason of the 
 action of dryness or of moisture therein. (2) The act of warping a 
 rope or chain by means of a warping cone (q.v.). 
 
 Warping Cone. — A conical or capstan -shaped drum, used to receive the 
 coil of the rope or chain when loads are being warped along (see 
 Warp). Sometimes called a surging drum. Also frequently termed 
 a capstan, because its outline is that of a capstan ; sometimes, also, 
 warping ends, when attached to the ends of horizontal shafts, as in 
 steam -winches. 
 
 Warping Ends. — See Warping Cone. 
 
 Warren Girder. — A lattice girder (q.v.) in which the struts (q.v.) and 
 ties (q.v.) form triangles or triangular bays, the struts leaning inwards 
 
MECHANICAL ENGINEERING. 403 
 
 or towards the centre of the girder, and the ties leaning outwards. 
 Warren girders are largely employed for bridges. A warren girder 
 consists of a single system of triangles, while lattice girders contain 
 two or more systems of triangulation. 
 
 Wash Brush. — ^A draughtsman's colour hrush (q.T.) used for cleaning 
 palettes and colour utensils. 
 
 Washer. — A thin ring of metal encircling the screwed end of a holt, and 
 receiving the thrust of the nut. These are of most value when used 
 against rough surfaces, as affording a comparatively true face for the 
 distributiou of the pressure. Wall washers and other cast-iron and 
 "wrought-iron washers of large sizes are often made rectangular in outline. 
 
 Washing Out. — The cleansing of a steam boiler, effected by driving out 
 the muddy deposit or sludge before a jet of water sent through a hose 
 pipe. See also Mushing Charge. 
 
 Wash-out Plug. — A plug screwed either into the bottom plates of boilers 
 or on the outside of a nozzle attached thereto, for the purpose of 
 closing the opening used for washing out (q.v.). 
 
 Waste, or Cottan Waste. — ^The refuse of cotton nulls, which being soft 
 and of close fibre, is used by engineers and machinists to cleanse their 
 working parts of accumulated o2 and dirt, and to wipe off superfluous 
 oil and grease from the surfaces of work in process of shaping and 
 fitting. Sponge cloths (ci..v.) are rapidly superseding cotton waste. 
 
 Waste Blocks. — ^Plaster moulds from which reversed moulds (q.v.l are 
 made, the waste blocks being rammed directly on the pattern. After 
 the reversed moulds are obtained the waste blocks are no longer of 
 service. 
 
 Waste Heat. — See Close-topped rumace, Hot Blast, Kegenerative ]?ui- 
 nace, &c. 
 
 Waste Pipe. — The pipe used to convey waste steam away from a bon- 
 neted safety-valve. Also a blow- ofi pipe. Similarly any pipe used for 
 conveying away waste steam or water. 
 
 Waster. — (1) Waster castings are those which, owing to some defect or 
 defects, are discarded as useless, and are broken up for the scrap heap. 
 Wasters are due to several causes, as blow-holes, scabs, cold shuts 
 (see Cold Short), insufficient metal, a very rough exterior, flaws arising 
 from bad proportioning or improper cooliDg, and sometimes from mis- 
 takes in coring and stopping off. (2) Steel and iron plates which 
 show blow-holes and other defects on rolling are also termed wasters. 
 
 Waster Casting. — See Waster. 
 
 Waste-water Cock. — See Pet Cock. 
 
 Waste-water Pipe. — ^A drain pipe (q.v.) or waste pipe (q.v.). 
 
 Water. — Symbol, H2 0. Is a compound of the two gases, hydrogen and 
 oxygen, in the above proportions, andean be analysed into those elements. 
 It may be built up by exploding a mixture of the gases. Its value 
 as a motive agent is due to the pressure derived from head (q.v.), and 
 to its capacity of vaporization (see Steam). It is the best solvent 
 known, so that it is impossible to obtain water in a condition of purity 
 in a natural state ; hence the incrustation (q.v.) of steam-boilers. This 
 is especially the case with sea water (q.v.) which requires for this 
 reason to be maintained at a certain standard of saltness by frequent 
 blowing-off. See Two Salt Waters. The weight of distilled water is 
 used as a standard by which to measure the specific gravity (q.v.) of 
 bodies. Of the temperatures of water there are four being constantly 
 employed as standards for reference : 32°F. or 0°C., the freezing-point; 
 
404 DICTIONARY OF TERMS USED IN 
 
 39-1° F. or 4° C, the point of maximmn density; 62° F. or 16-66° C, the 
 standard of temperature as used for determining the specific gravity of 
 todies ; 212° F. or 100° C, the boiling point at the pressure of the 
 atmosphere. 
 
 Water Bath. — ^A bath of clear water used in the development of photo- 
 types (q.v.), its function being to check the action of the prussiate 
 solution, which, but for tliis precaution, would cause the lines to break 
 and diffuse over the paper. There are usually two baths used, one 
 before, and the other after the acid bath, to remove all traces of the 
 chemicals. The water bath is lined with tin. 
 
 Water Bosh. — (l)The tank which supplies the tuyere(q. v.)of a smith's shop 
 with water. (2) A tank ia a foundry which supplies the water neces- 
 sary for core making and the watering of green sand moulds. 
 
 Water Bridge. — A form of bridge used for steam boilers which is made 
 continuous with the boiler itself. It is of iron, and is hollow, thereby 
 assisting the circulation of the water which traverses through the 
 interior. 
 
 Water Brushes. — Soft brushes of bristles employed in foundries for the 
 purpose of wetting or moistening the surface sand of moulds to make 
 it cohere consistently. The water is spurted over in a fine spray, or 
 lightly wiped around the edges, according to circumstances. 
 
 Water Can. — Ordinary gardeners' water cans are used by moulders for 
 damping and remixing the sand on the foundry floor after the cast- 
 ings made over-night have been turned out. 
 
 Water Chamber. — A chamber, usually annular in form, encircling the 
 cylinders of gas engines and air compressors to prevent the heating 
 due to the products of combustion in the first place, and to the com- 
 pression of the air in the second. 
 
 Water Cock. — Thelowerof the two try cocks (q.v.) of a steam boiler. So 
 called because water should always issue fcom it when opened, never 
 steam, since that would imply that the water had fallen to a dangerous 
 level. 
 
 Water Column. — ^A column up which the supply water for a water crane 
 (q.v.) passes. It is of cast-iron and encloses within its body the actual 
 supply pipes. 
 
 Water Core. — In some large cylindrical works of considerable thickness, 
 the central portions remain hot so long after the outer portions have 
 cooled, that injurious internal stresses are set up between the outer 
 and inner layers of metal, due to the unequal coohng. This is pre- 
 vented, and the cooMng and contraction rendered approximately uni- 
 form by the carrying of a current of cold water through the interior, 
 by which the central portions are cooled at about the same rate as 
 the exterior. This is called a water core. 
 
 Water Crane. — A contrivance for supplying water to the tanks of loco- 
 motives at the stations along their lines, though not properly spealdng a 
 crane at all, the term being probably derived from the appearance of the 
 swinging supply arm. In. one form the turning round of the swing 
 arm to which the hose is attached opens a valve, and the water pressure 
 in the reservoir forces up the liquid through the supporting column 
 • along the arm into the tender. In another form the lifting of a sluice is 
 necessary to deliver the water supply, the water still flowing under 
 constant head. In a third type a tank is carried on the water column 
 and is maintained constantly full, being fitted with inlet valve and 
 overflow pipe, and the raising of a lift valve by means of a chain is all 
 
MECliANlCAL ENGINEERING. 405 
 
 that is necessary to allo-w of the descent of -water from tie tank by 
 gravity. 
 
 Water Cylinder. — Sometimes applied to the pump barrel of a steam pump 
 to distinguish it from the steam or engine cylinder. 
 
 Water Engine. — See Water Pressure Engines. 
 
 Water Float.— See Float. 
 
 Water Gauge. — ^A gauge afSxed to a steam boiler for. the purpose of 
 registering the height of the water contained -within. It consists usually 
 of a stout glass tube fixed in brass seatings, -whose lowest end is at the 
 lowest level at which -the water should be allowed to sink, and furnished 
 ■with steam and water cocks. Sometimes, however, it consists of a float 
 and -wire, -with a chain and register pointer attached. See Moat 
 Gauge. 
 
 Water Hardening. — The hardening of steel, effected in water, as opposed 
 to oil hardening (c[.v.). In water hardening the steel becomes more 
 brittle and acquires a harder texture than when oil is used. Some- 
 times the water is medicated "with salt or other substances, but pure 
 well or spring water appears to be in most favour. 
 
 Watering. — Alludes to the practice of damping foundry sand to make it 
 cohere properly. After castings have been turned out of the sand in 
 the morning, a certain amount of water is sprinkled over it from the 
 rose of a water can, or from buckets, the sand meanwhile being turned 
 over with shovels. The amount of water sho-uld be only sufficient "to 
 render the sand perceptibly damp, -without being muddy or sticky. 
 Watering is also resorted to just previously to the -withdrawal of a 
 pattern, the edges of the sand around the margin of the pattern being 
 damped with a swab or water brush (q.v.) to cause sufficient coherence 
 of the sand to prevent pulling up. Broken edges of sand are also 
 watered in the act of mending up and for the same reason. 
 
 Water Jacketing. — The casing of the cylinder of a gas engine -with a 
 water jacket. See Water Chamber. 
 
 Water Meter. — ^A meter used for recording the amount of feed water 
 which passes into a steam boiler in any given time. There are many 
 forms of water meters in use. 
 
 Water Packing. — The pistons of some air pumps are made for water 
 packing ; that is, the piston, which is solid and deep, is furnished with 
 circularly turned grooves around its circumference, which retain a film 
 of water of sufficient thickness to render the piston watertight. 
 
 Water Pot. — A small oast-iron pot used in foundries for holding water, 
 for dipping the water brush or swab into. Called also a swab pot. 
 
 Water-pressure Engines. — These include generally hydra-uUc rams, tur- 
 bines, and other motors driven by water pressure, but refer specifically 
 to certain types of engines having cylinders and pistons, either recipro- 
 cating or rotary, whose construction is the same iu principle, though 
 differing in detail, as that of steam engines, the pressure due to a head 
 of water being employed instead of steam. 
 
 Waterproof Cement. — Iron Cement (q.v.). 
 
 Waterproof Glue. — See Glue Cement. 
 
 Water Earn. — See Hydraulic Earn. 
 
 Water Tank. — See Tank, Tank Plates, Iron Cement. 
 
 Water-tank Bed Plate. — A form of engine bed plate which is cored out 
 to serve as a tank for the feed water of the boiler. 
 
 Water-tube Boiler. — A sectional boiler (q.v.). 
 
 Water Tubes. — See Galloway Tubes. 
 
406 DICTIONARY OP TERMS USED IN 
 
 "Water Tuyere. — See Tuyere. 
 
 Water Wlieel. — A -wheel whose axis is horizontal, and -whose rim is 
 furnished -with buckets or floats, against -which *-he -water acts either 
 by impulse, or gra-rity, or reaction. See Breast, Overshot, and "tinder- 
 shot Wheels, and Turbine. 
 
 Water Way. — The full space open for the passage of fluid in the buckets 
 of pumps, the plugs of cocks, and the area of lift of valvea. 
 
 Wave Wheel. — A -wheel for the reception of a rope, the bite of -which is 
 ensured by a -wavy contour being given to the rim, the groove -waving 
 from side to side around the circumference. 
 
 Wax. — ^This is used as a material for modelling patterns of ornamental 
 -work. 
 
 Way Shaft. — A -weigh shaft (q.v.). 
 
 Wear. — ^A term applied to -the slo-w abrasion of surfaces in frictional 
 contact, as the shdes of machine parts, the pistons and valves of 
 engines, the journals of shafts, lever pins, &c. Provision is made in 
 many instances by means of adjustable pieces for the taking up of -the 
 wear, as it is called. See TaHng-up. 
 
 Wear and Tear.— See Depreciation. 
 
 Weathering. — (1) Those iron ores which contain pyrites in considerable 
 quantity, and which are not of a calcareous quality, are often weathered 
 by exposure to the atmosphere previous to calcination, the sulphur pre- 
 sent being slowly oxidised, and rendered soluble, and washed away by 
 rain. (2) Foundry clay is weathered by being cut up and exposed to 
 the frost, which f acOitates the subsequent work of grinding and mixing. 
 
 Web. — The plated or central portion of a structure as distinguished from 
 its flanges and bosses. Thus a crank web is the plate which carries the 
 shaft and pin bosses ; a girder web is the main vertical plate which 
 becomes the connection between the top and bottom flanges. See Lat- 
 tice "Web. 
 
 Web Stiffenera. — Webs of "J" iron riveted to the sides of deep-plated 
 girders, and continued -to the inner faces of the top and bottom flanges 
 to preserve them from -wrinWing stresses. 
 
 Wedge. — A triangular prism resolvable into two incliued planes set back 
 to back, in which the mechanical gain is greater the more acute the 
 angle of the sides. The power of a wedge may be obtained in a 
 graphic manner. The theoretical rule is that the pressure apphed at 
 the back of the wedge is to the resistance, as half -the -width of the back 
 of the wedge is to the length of the side. But the elements necessary 
 to -the calculation are so variable that it is best not to rely much on the 
 theoretical statement. 
 
 Wedge Gearing. — ^Wheels whose peripheries are grooved circumferen- 
 tially ; the sides of the grooves being sloped or angular in section : the 
 projectiag rings in the one wheel enter into the grooves on the other 
 and drive by friction only. These are therefore a type of friction 
 gearing (q.v.), 
 
 Weighbridge. — This is essentially a table carried by a system of levers 
 comprised in a small compass, the lengths of whose arms are so pro- 
 portioned that a weight of a few ounces or pounds hung upon a steel- 
 yard at one end -will co-unterbalance a weight of several hundredweights 
 or tons on the weighbridge table at the other end of the system. 
 
 Weighing Machines. — ^Light instruments made on the principle of the 
 weighbridge (q.v.) for taking weights of a ton and under. 
 
 Weigh Shaft, or Way Shaft. — ^The shaft or spindle which forms the centre 
 
MECHANICAL ENGINEERING. 407 
 
 of motion of the lever employed for throwing the slot Knts (q.v.) for tlie 
 reversing motion of an engine into the proper positions for forward or 
 backward gear. Sometimes called a reversing shaft. 
 
 Weight. — The tendency of a body to move downward towards the surface 
 of the earth, xmder the action of gravity. See Mass. The unit of 
 weight employed by the engineer is the pound, owt. , or ton, depen- 
 dent upon the precise work whose amount it is desired to estimate. 
 The question of weight is of fundamental commercial importance. 
 Castings in various metals are sold by weight at so much per lb., cwt., 
 or ton. Rolled iron of various sections is sold by weight, and is quoted 
 at so much weight per foot. Ropes and chains are quoted at a certain 
 weight per fathom. Sheet metals are distinguished as of certain 
 weights per foot ; the weight of tubing is also thus quoted. In many 
 oases, especially in plates, a slight percentage of margin is allowed 
 either way. 
 
 Weight Case. — The casing which surrounds the accumulator (q.v.) of a 
 hydraulic crane, and which is loaded with stones or iron to the pressure 
 necessary for the effective working of the crane. 
 
 Weight, Distributed. — The weight of a locomotive is so distributed that 
 the load upon leading, driving, and trailing wheels shall be as nearly 
 as possible alike. See also Distributed Load. 
 
 Weighted Pendulum Governor. — A governor (q.v.) whose balls are 
 attached by Knks to the central axis above, and to a collar below, the 
 latter being attached to a heavy weight free to slide on the central 
 spindle. For any given rise in the height of the balls that of the weight 
 is doubled. 
 
 Weighting Down. — The holding down of the top part of a moulding box 
 diiring casting by means of hundredweights, or half ton weights. Pins 
 and cottars or screw bolts afford better security than weights. 
 
 Weights. — Weights are used for many purposes in engineers' workshops. 
 Por scales, weighbridges, foundry boxes, and as tests in the proving of 
 structures. They vary from small weighbridge weights to those of 
 half a ton or a ton each. 
 
 Weir. — The dam or barrier by which the waters of a stream are bayed 
 back in order to afford sufficient head of water for driving a water 
 wheel or turbine. 
 
 Weld. — A welded joint (q.v.) as a good weld, a bad weld. 
 
 Welded Joint. — A joint made between opposing faces in wrought iron 
 and steel work by welding (q.v.). Welded joints are butt, lap, scarf, 
 and vee, noted under those headings. They are employed both by 
 smiths and boiler-makers. 
 
 Welded Tube. — ^Wrought-iron tube which is made by being brought to 
 a circular form or skelp, raised to a welding heat, and drawn through a 
 pair of jaws, by which the seam is closed up. 
 
 Welding. — The common mode of union of wrought iron and steel, by 
 which close and permanent contact is made between the joint faces, so 
 that the union is homogeneous throughout. The joints to be so united 
 are cleaned from scale and sprinkled with a flux, usually sand or borax, 
 to dissolve off or to prevent the formation of oxide, brought to a welding 
 heat and hammered together. The process is commonly called shutting, 
 or shutting up, in the shops. 
 
 Welding Heat. — The degree of heat when in smith's work the iron or 
 steel gives out vivid sparks, and small globules melt off. It corresponds 
 roughly with a temperature of from 2,500° F. to 2,700^ F. for wrought 
 
to8 DICTIONARY OF TERMS USED IN 
 
 iron, but less for steel, vHch requires especial care as regards the 
 temperatore, cast steel being difB.oiilt of welding, and scarcely bearing 
 more tban a cherry red. Shear steel will weld easily, and endure a 
 white heat safely, so that in welding the judgment and experience of the 
 smith is of first importance. 
 
 Weldless Tube.— See Solid Drawn Tubes. 
 
 Well Crane. — A fixed post crane, one-half of whose post is above ground 
 and the other sunk ia a pit, or well, dug to receive it, and encased with 
 masonry, or with iron plates. The lower end of the post rests on a 
 step at the bottom of the well, and the fulcrum of the post is at the 
 ground line. 
 
 Well Plate. — ^A oast-iron plate put over the mouth of a well to carry the 
 pumps, (fee. See Well Stage. 
 
 Well Fump. — An ordinary lift pump of two or three throw type, affixed 
 to staging at the required depth, and worked from the well staging by 
 hand or cattle gear, or by power, the cranks being connected to the 
 pump piston by a sufficient length of jointed rods to estabHsh communi- 
 cation between the crank and piston. Also called deep well pump. 
 
 Well Stage. — Aframingof timber erectedover the mouth of a well to carry 
 the pumps and pipe connections. 
 
 Welt. — The covering strip used in butt riveting (q.v.). 
 
 Westinghouse Brake. — An air brake used on railway rolling stock. Air 
 is compressed by a steam pump placed underneath the engine, and is 
 retained in a reservoir ready for use. A cylinder and piston under each 
 carriage communicates with the reservoir by means of hose pipes and 
 coupKngs. The communication between the piston rods and brakes is 
 made through the intervention of levers. 
 
 Wet Blacking. — Black wash (q.v.). 
 
 Wet Bottom. — A puddling f aruace is said to have a wet bottom when the 
 slag is allowed to accumulate instead of being drawn off at frequent 
 intervals. 
 
 Wet Brush. — See Water Brushes. 
 
 Wet Puddling. — Pig boiling (q.v.). 
 
 Wet Steam. — Steam, the amount of whose moisture has been increased 
 by mechanically admixed spray thrown off by the priming (q.v.) of the 
 water in the boiler. 
 
 Wet TTptake. — When the uptake of a marine boiler is placed within the 
 shell, and is therefore surrounded by water and steam, it is termed a 
 wet uptake, to distinguish it from a dry uptake (q.v.). 
 
 Wet Wood. — Timber which has not been seasoned properly, and which 
 therefore retains the sap in the vessels. Timber which has been 
 seasoned may become wet by long exposure to the weather. This 
 moisture soon dries, however, under cover, and is not so detrimental 
 as the sap wet. 
 
 Whale Oil. — Sometimes, though improperly, termed a fish oil. There 
 are two kinds of whale oil known, as train oil, the produce of the 
 blubber of the Eight whale, and some other species, and sperm 
 oil, which is taken from a reservoir in the head of the sperm 
 whale or Caeholot. The sperm oil is the best machinery lubricant 
 known, and 5,000 or 6,000 gallons of the oil is taken from a single 
 animal. 
 
 Wharf Crane. — A crane specially adapted for use- on wharves. It is a 
 fixed well crane of the triangular form, consisting of pillar or post, jib, 
 and ties, and usually worked by hand. 
 
MECHANICAL ENGINEERING. 409 
 
 Wheel. — A general term wliioli denotes no wieel in particular, apart 
 from its qualifying prefix, as sheave wheel, chain wheel, pulley wheel, 
 toothed wheel, cog or mortice wheel, &o. 
 
 Wheel and Axle, or Windlass. — This owes its value to the principle of 
 the lever, and has its application ia trains of gearing, capstans, i&c. 
 
 Wheel Barrow. — ^Wheel barrows are used in foundry work for carrying 
 sand, loam, light castings, and moulding boxes, and for yard work 
 generaEy. Made in iron and wood, and with single and double wheels. 
 
 Wheel Base. — The distance apart of the centres of the leading and trailing 
 wheels of a locomotive, or of the front and hinder wheels of a railway 
 wagon. A rigid wheel base denotes the distance between centres of 
 those wheels which have rigid {i.e. not bogie) bearings. Total wheel 
 base would include the bogie wheels also. 
 
 Wheel Bossing. — The weldmg on of the boss pieces of railway wheels 
 under the steam hammer. 
 
 Wheel Centre. — The central portion of a solid plated truck or wagon 
 wheel, which corresponds with the body of a wheel with arms. For 
 trucks and trollies it is customary to use wheels having plated centres 
 for the attachment of steel tyres in preference to using chilled cast-iron 
 wheels. The centres are turned and shouldered, or stepped on the cir- 
 cumference, and the tyres are bored to correspond. Heating of the 
 tyres in a reverberatory furnace expands them sufficiently to clear the 
 shallow shoulder, and in cooHng they shrink over and embrace the 
 shoulder and so remain fast. Sometimes tyre bolts are employed in 
 addition to prevent the possibility of the working loose of the tyres. 
 
 Wheel Cutting. — The cutting of the teeth of gear wheels by means of 
 revolving loilling or gear cutters, the wheel blank being held steady 
 while each interspace is being cut, and moved around an arc of a circle 
 exactly equivalent to the pitch of the tooth for the next cut. The 
 means of dividing out adopted are either a division plate (q.v.) or a 
 tangent wheel and screw with change wheels. The practice of wheel 
 cutting has rather to do with the making of models and the smaller 
 portions of machines, as paul wheels and such like, than with general 
 engineering-, for which cast teeth are preferable. 
 
 Wheel Draught. — In an externally fired wagon boiler (q.v.) the gases 
 pass rmder the boiler from front to back, then upwards into a flue on 
 the right-hand side leading towards the front of the boiler, thence round 
 into a flue on the left-hand side, and so to the back of the boiler into 
 the chimney. This, from its circuitous motion, is called a wheel 
 draught to distinguish it from a split draught (q.v.). 
 
 Wheel Float.— See Moat, Boiler Float. 
 
 Wheel Gearing, or Toothed Gearing. — This means that type of gearing 
 which acts by means of teeth or cogs, or modifications of the same 
 attached to the peripheries of rings, as distinguished from gearing of 
 other kinds. Hence it embraces spur and bevel wheels, mortice wheels, 
 helical and worm, and internal gears, each noted under its special 
 heading. 
 
 Wheel Lathe. — A lathe of special design, having a bed short in propor- 
 tion to its size, and used for the turning of locomotive and other 
 wheels. A duplex-wheel lathe has two heads, so that a pair of wheels 
 can be turned at one time upon their axles. 
 
 Wheel Moulding Machines. — Machines extensively used for the mould- 
 ing of toothed wheels without the making of a complete pattern. The 
 Diachines, diflEering much iu details, are in principle dividing engines, 
 
+10 DICTIONARY OF TERMS USED IN 
 
 a worm and endless screiv and oliange wlieela supplying the means of 
 regnlating the equal division into any required number of teeth. Two 
 teeth only are required for mouldmg from, and the space between 
 those teeth alone imparts the outline to the sand. When a single 
 tooth space is rammed, the tooth block is lifted and moved round by 
 the machine to a distance corresponding with the pitch. The arm 
 which carries the tooth block usually revolves around a central pillar, 
 and is adjustable for radius and also for depth. Sometimes the mould- 
 ing table revolves, and the arm can only move radially and vertically. 
 The arms of the wheels are made by means of cores. There are also 
 machines which are not furnished with the tangent wheel ; but a 
 perforated drum or circular division plate instead answers the same 
 purpose. 
 
 Wheel Plate. — A quadrant plate (q.v.). 
 
 Wheel Segment. — See Toothed Segment. 
 
 Wheel Slope. — A draughtsman's palette (q.v.), circular in plan, and 
 having several radial slopes falling inwards. 
 
 Wheel Stamping. — The stamping out of the spokes of railway wheels 
 under the steam hammer previous to welding up. 
 
 Wheel Swarf. — The silicious and steely mud which collects in the 
 troughs of the grindstones of the Sheffield cutlers. It is used to form 
 a layer within tiie mouths of the crucibles or pots used in the production 
 of crucible cast steel, where it fuses and forms an air-tight glaze to 
 protect the bars of blister steel within. 
 
 Wheel Teeth. — The teeth of gear wheels are formed on definite principles 
 of design, the forms of their curves being either cycloidal, or involute. 
 The cycloidal curve is that employed for nearly all wheels, the involute 
 (q.v.) being reserved for special work. The cycloidal curves are 
 obtained by means of the odontograph (q.v.) scale, or are formed for 
 each separate pair or set of wheels by means of rolling curves (q.v.). 
 The strength of wheel teeth is estimated by considering each tooth 
 as a cantUever (q.v.), or by determining the horse power to be trans- 
 mitted. 
 
 Wheel Tooth-cleaning Machine. — A revolving emery wheel, turned to 
 the section of the interspaces of cog-wheel teeth, and used for grinding 
 out the cast teeth to a smooth surface, the wheel being laid 
 horizontally. 
 
 Wheel Valve. — A lift globe valve of the ordinary type, in which the 
 screw which lifts and depresses the valve is worked by means of a 
 hand wheel above. 
 
 Whelps. — The longitudinal strips arranged equidistantly around the 
 barrel of a capstan (q.v.) or warping cone (q.v.) on which the rope 
 coils, and by which its bite is increased. 
 
 Whiffle Trees. — Whipple trees (q.v.). 
 
 Whin. — A variety of horse gear or bullock gear (q.v.) in which the rope 
 is wound round a barrel fastened directly to lie vertical shaft which 
 carries the cross-bar. 
 
 Whip Crane. — A sHght crane used generally for warehouse purposes. It 
 has no gearing, but is worked by a rope ; hence its name. iTie rope is 
 afSxed to a large dram or pulley at the top of the crane, thence it 
 passes down to a small barrel on the winch shaft. The winding up of 
 the rope gives motion to a small barrel on the same axis as the large 
 pulley, and the difference in the diameters of the barrels and pulley 
 affordB sufficient leverage for lifting loads as high as 30 or 40 owt. 
 
MECHANICAL ENGINEERING. 411 
 
 Independent "wHip cranes are those in whicli the top of the crane has 
 no point of fixture for slewing, the whole structure being simply sup- 
 ported on a base sufficiently broad to afford the requisite stability. 
 
 Whip Gin.— See Gin Block. 
 
 Whipping Drum. — A term applied to the winding barrel of a deck 
 winch (q.v.) or a whip crane (q.T.). 
 
 Whipple Trees, or Whifle Trees. — The loosely swiTeUing bars attached 
 to the ends of the poles in horse and cattle gear, to which the cattle are 
 yoked. They are either single, double, or treble. 
 
 Whips. — The long arms which carry the cross-pieces and sails of a 
 windmill. 
 
 Whistle.— See Steam Whistle. 
 
 White Brass. — See Antifriction Metal. 
 
 White Heat. — A degree of colour in smith's work, at which the scales on 
 the surface are scarcely ■visible, and which corresponds roughly with a 
 temperature of 2,370° F. It is the temperature at which most large 
 forged work is taken from the fire. 
 
 White Iron. — A highly crystalline form of cast-iron. It is extremely 
 hard and brittle, and contains nearly all its carbon in the combined state. 
 Hence called a carbide of iron. White iron also results when the sur- 
 face of molten grey or mottled iron is chilled against a metaUio mould. 
 See also Forge Pigs. 
 
 White Lead. — Carbonate of lead (q.v.). Used when mixed with boiled oil 
 and red lead for making steam joints. 
 
 White Line Phototype. — See Phototype. 
 
 White Metal. — See Babbitt's Metal. These and similar mixtures are 
 termed white metals. 
 
 Whitening. — The facing used for brass founders' moiilds. 
 
 Whitening Bag. — A linen bag which contains the whitening used in brass 
 founders' moulds, and from which it is dusted out. 
 
 White Pine [Pimis strohis) . — A class of pine timber imported from North 
 America. See Pine Wood. 
 
 White Eope. — See Manilla Hopes. 
 
 White Spruce. — See Pine Wood. 
 
 White's Tackle. — A system of pulley blocks, so named after the inventor, 
 in which the diameters of the pudeys are regulated according to the 
 rate at which they travel, in order to ensure uniformity of speed and of 
 wear. 
 
 Whitwell Stove. — ^A regenerative stove used for heating the blast for 
 smelting puj^oses. It is in principle like the Cowper stove, but lire- 
 brick partitions are employed therein instead of chequer work. 
 
 Whitworth Thread. — The standard engineer's screw thread of angular 
 section. The depth of the thread, that is to the apices of the angles, is 
 •96 of the pitch, and the slope of the angles is 55°. The working depth of 
 the thread is reduced by rounding off the points and roots to an extent 
 of about Jth each, making the working depth '64 of the pitch. 
 
 Wholes and Halves. — A drawing compass, the lengths of whose legs are 
 in the proportion of one to two, measured from a joint pin around which 
 the legs play. They are used for enlarging or reducing dimensions on 
 drawings in those proportions. 
 
 Whole Shrouding. — See Shroud. 
 
 Wide Gauge. — See Broad G-auge. 
 
 Willow (Salix). — ^A tree of the natural order Salicaeece, being the order to 
 which the poplar belongs. It is a very soft, smooth-grained, white or 
 
4tz DICTIONARY OF TERMS USED IN 
 
 yellowish grey 'wood, easily worked, and is used by engineers for brake 
 blocks. Sp.gr. -585. A cubic foot weighs 36 J lbs. 
 
 Winch. — A fixed crane (q.v.) having no jib and no proTision for slewing. 
 It may have single, double, or treble gear, and be driven by hand or 
 steam. See Deck Winch, Steam Winch. 
 
 Winch Handle. — The handle of a crane, crab, or other hoisting 
 machine turned by hand power. It is a lever whose length is 
 the measurement taken from the centre of the handle to the centre of 
 the spindle. This length is usually 1 ft. 4 in. 
 
 Winch Shaft. — The first shaft in a train of gearing, to which the winch 
 handle is attached. 
 
 Wind Bore. — The strainer of a suction pipe. (See Strainer.) 
 
 Wind Chest.— See Air Belt. 
 
 Wind Engine. — A windmill (q.v.). 
 
 Wind Gall. — A defect in a balk of timber caused by an old wound, sub- 
 sequently covered over by a growth of wood. It becomes a centre of 
 
 Winding.- — The variations of a surface from a true plane, considered 
 chiefly in relation, not so much to local inequalities of surface, as to 
 the total superficies. Thus, if on one corner of the plate the surface were 
 sloping "iV below the general surface, the plate would be -jV winding. 
 
 Winding Drum. — The barrel or cylinder which coils the wire rope for 
 raising and lowering cages and trucks on inclines. 
 
 Winding Engine. — The engine which drives a winding drum (q.v.). It 
 does not refer to any particular type of engine, but simply to the purpose 
 for which it is employed. 
 
 Winding Gear. — A particular type of hoisting machine used for hauling 
 wagons up inclines. It consists of winding drum, or clip pulley, and 
 suitable toothed gearing, single or double purchase, with arrangements 
 for the application of sufScient brake power, the whole being driven by 
 a stationary, a locomotive, or portable, or semi-fixed portable engine. 
 
 Winding Sticks. — Winding strips (q.v.). 
 
 Winding Strips, or Winding Sticks. — Straight-edges of metal or of wood, 
 made perfectly parallel, and equal in width, by means of which the 
 inaccuracy of a supposed level surface is detected. The strips are set 
 by their edges on those portions of the plate whose condition it is 
 desired to test, and the amount of their divergence from parallelism is 
 observed by the eye cast across their top edges. 
 
 Windlass. — See Wheel and Axle. 
 
 Windlass Jack. — A lifting jack provided with a double-ended lever and 
 handles for working bevel gear wheels, by which the nut is turned 
 around the lifting screw. 
 
 Wind Mill, or Wind Engine. — These are used to some extent for driving 
 pumps. A windmill consists of its main support, which carries the sail 
 frame or whip shaft. This shaft is incKned at an angle of about 8°, 
 with the horizon on level ground, and 15° in mountainous districts, ib 
 being found that the direction of the wind is always slightly downwaros. 
 The whips or sail frames carry transverse or cross pieces, on which the 
 actual sails are spread, the cross pieces being so hinged that their 
 obliquity in relation to the direction of the wind is capable of vari- 
 ation. 
 
 Wind Ties. — ^Diagonal side ties of wrought iron rod, on bridges and large 
 block setting cranes, and other structures, for steadying the structures 
 to which they are attached against wind pressure. 
 
MECHANICAL ENGINEERING. 413 
 
 Wing Compasses. — ^A pair of compasses used in the ■workshops, in which 
 an arc- shaped wing attached to one leg passes through a slot ia the 
 other leg, to which it is set or clamped in any position by a set screw. 
 
 Wing Nut. — A form of nut which is tightened or relaxed by two thia flat 
 wings or expansions coming out from opposite sides. 
 
 Wing Bail. — In permanent way, is a short rail laid down at a crossing 
 near the point rail to guide the wheel flange. It fulfils the same 
 purpose as a cheek rail (q.v.) on a curve. 
 
 Wing Tanks. — The tanks of a side tank locomotive engine. 
 
 Wing Valve. — A valve whose lift is guided by three or four wings, or 
 feathers, or ribs, as they are variously termed, cast upon its under side 
 and fitting into its cylindrical seat ; called also Hf t, and puppet valve. 
 Such a valve may be placed in a vertical position, as in a common safety 
 valve, or its axis may be horizontal or otherwise, if pressed against its 
 seating by springs. 
 
 Wiper. — (1) See Sponge Cloth. (2) The cam teeth on the wheel of a 
 helve or tilt hammer are called wipers or wipes. 
 
 Wiper Shaft. — The shaft or axle of a wiper wheel (q.v.). 
 
 Wiper Wheel. — ^The wheel or disc to which the wipers (q.v.) or cams of 
 helve hanuners and stamping machines are attached. 
 
 Wipes. — The teeth or projections on the cam plate of a helve hammer. 
 
 Wire. — Iron, brass, and copper wire is used for many purposes in the 
 factory, and in all departments, as for dowels and skewers, for binding 
 and fastening light cores, for making steam joints, for pins and small 
 screws, for brazing joints, for straining lines, and many others. 
 
 Wire Brush. — A brush used for the fettling ofi of castings. It is in 
 shape like an ordinary hand brush, but the place of bristles is occupied 
 by thin elastic fibres of steel, by which the sand and dirt are readily 
 scraped off the surfaces of the castings. 
 
 Wire Card. — See Card Wire. Used by moulders for rubbing or dressing 
 down cores. 
 
 Wire Drawing. — (1) The process of manufacture of wire by pulling it 
 through draw plates. (2) The throttKng of steam in the passages of an 
 engine cylinder, by which some amount of expansive working is effected. 
 This throttling takes place when the passages are so contracted that 
 the rate of travel of the entering steam falls behind that acquired by 
 the piston towards the termination of its stroke. 
 
 Wire Edge. — The turned over strip of metal which results when a tool is 
 subjected to abrasive action upon a grindstone, or hone. This is removed 
 by rubbing both faces of the tool alternately, thus thrusting the wire 
 edge from one side to the other, until it is readily detached. 
 
 Wire Gauge. — A notched plate having a series of gauged slots, numbered 
 according to the sizes of wire and sheet metal manufactured. The 
 Birmingham wire gauge is that in general use. 
 
 Wire Gauze. — ^Fine iron wire woven intx) gauze, having a fine mesh. It 
 is employed in making steam joints, the gauze being cut to the size and 
 shape of the flanges, and smeared with red or white lead previous to 
 the bolting together of the flanges. 
 
 Wire Nails. — Nails circidar in section, parallel, and having thin circular 
 heads. Used in general pattern work. 
 
 Wire Pliers. — Pliers (q.v.) in which a pair of smooth jaws, circular in 
 section and tapered lengthways, are substituted for the ordinary flat 
 and roughened jaws, their purpose being the bending of wire into 
 small curves and loops. 
 
414 DICTIONARY OF TERMS USED IN 
 
 Wire Eope. — Rope formed by twisting several wires aroimd a central 
 hemp core, to form a strand, seTeral such strands being- tben twisted 
 around a central hemp core to form the rope. The diameter of a single 
 wire varies from -^ to -^^ of an inch, and the twisting of the wires to 
 form the sti'and is in the reverse direction to that of the strands which 
 make up the rope. "Wire ropes are formed of both iron and stccl. 
 Their strength is very great, so that a small wire rope will do the work 
 of a much larger hempen one. 
 
 Withe Handles. — The flexible elastic handles of smith's tools. See Hazel 
 Rods. 
 
 Wood. — ^Wood is employed as a fuel, and in the preparation of charcoal. 
 It is not economical as a fuel in the green state, owing to the quantity 
 of moisture which it contains. Wood is composed essentially of carbon 
 and oxygen ; hydrogen, nitrogen, and ash being present in small quan- 
 tity. Woods are hard or soft, terms which are relative merely. The 
 value of wood to the engineer consists in its adaptability in the form 
 of timber boards, planks, and logs for purposes of construction. 
 
 Wood Ferrules. — Kings of wood used for making the ends of marine 
 engine condenser tubes water-tight. They fit closely around the tube 
 ends, and are driven tightly between them and the holes in the tube 
 plates. 
 
 Wood, Preservation of. — Various methods have been employed for the 
 preservation of timber from decay, the chief of which are creosoting, 
 kyanizing, and the employment of Burnett's and Margery's fluids, 
 described under their several heads. 
 
 Wood Screw. — A right-handed screw having a conical-shaped head pro- 
 vided with a slot or nick, by which the screw is turned in through the 
 medium of a screw-driver. Formerly called a sorew-naU. 
 
 Wood Spirit, — Methylated Spirit. See SheUao Varnish. 
 
 Wood Turning, — Wood turning is an essential section of pattern work, 
 and is not performed by professional turners, but by the pattern-maker 
 himself, who alone can know the conditions necessary to be observed in 
 order to proper delivery from the sand. The work is seldom orna- 
 mental, and much of it is done by scraping tools chiefly. 
 
 Woolf Engine. — An early type of compound engine in which the cranks 
 were set opposite to each other, instead of at right angles, as is now the 
 common practice, so that when one piston was at the termination of its 
 stroke the other was at its commencement. 
 
 Woollen Pad.— See Worsted Pad. 
 
 Work. — This is the result of resistance overcome by the action of force 
 acting upon a body. See Energy. 
 
 Work, Diagram of. — See Diagram of Work. 
 
 Working. — The working of the frames of locomotives signifies the loosen- 
 ing of their joints, due to the strains communicated to them by the 
 engines. 
 
 Working Anvil Block. — A block of steel or cast iron fitting on the top of 
 the anvil block (q.v.) of a steam hammer. It is fitted to the latter 
 with a dovetailed joint, to be readily removable, in the same mannei 
 as the hammer block (q.v.) is attached to the tup (q.v.). 
 
 Working Barrel. — A pump barrel proper, containing the piston and 
 bored portion, and in some cases also the clack valves. Used to dis- 
 tinguish it from the pump case (q.v.). 
 
 Working Beam. — The beam of a Cornish or beam engine, having tha 
 piston rod at one end and the pump rod at the other. 
 
MECHANICAL ENGINEERING. 415 
 
 Working Bed. — The lining' of a puddling furnace, consisting of broken 
 slags, tap cinder, heartii bottoms, and fettling. 
 
 WorMng Cylinder. — The explodiag cylinder in those gas engines which 
 are provided with a separate compressing cyUuder (q.v.). 
 
 ■Working Depth. — In toothed gearing this is less than the total length of 
 tooth from point to root by the amount of bottom clearance. 
 
 Working Door. — The opening through the side of a reverberatory furnace 
 through which the charge is introduced to, and withdrawn from the 
 hearth. The door sUdes in vertical grooves, is protected with fire brick, 
 and is balanced by a chain and counterweight. 
 
 Working Drawing. — ^A plain, fully detailed drawing of an engine, 
 machme, or structure, or more generally a portion only of the same, 
 and either dimensioned, or drawn to full size, or to a uniform scale, and 
 sent out into the workshops to be used in construction. 
 
 Working Gear. — This is applied specifically to the motion work of a loco- 
 motive or engine, namely, the piston and connecting rods, eccentrics, 
 and rods, links, slide valves and rods, as opposed to the fixed gear, or 
 that which has no reciprocal movement. 
 
 Working Load. — The ordinary load to which a structure is subjected, not 
 necessarily the maximum load, but the average or mean load, as dis- 
 tinguished from the proof load (q. v.) . 
 
 Working Nuts. — Nuts which are perpetually being tightened and relaxed 
 by means of spanners or screw keys, as distinguished from the nuts 
 which remain permanently fast. "Working nuts are, or should be, 
 always case-hardened (see Case Hardening) in order to prevent the 
 wearing of their angles rounding. 
 
 Working Stress. — The safe stress which calculation and experience com- 
 bined allow that structures should be subject to. It is less than the 
 elastic strength (q.v.) by the divisor selected as the factor of safety 
 (q.v.), which factor of safety is selected in accordance with the nature 
 of the load imposed. 
 
 Work, Unit of.— See Unit of Work. 
 
 Worm. — A form of helical gear consisting of a continuous screw thread 
 wrapped around a cylinder. It is used to impart a slow and equal 
 motion to a worm wheel (q.v.). 
 
 Worm Gearing. — Gearing composed of worms and worm wheels. It is 
 employed where great power is sought, but much of its ef&ciency is lost 
 in friction, so that it is often necessary to run the worm in oil. 
 
 Worm Wheel. — Gears with a worm, and each tooth consists of a small 
 segment of a hehx. The worm commonly drives the wheel. In order 
 that the wheel should drive the worm, the obliquity would have to be 
 very great. 
 
 Worsted Pad, or Woollen Pad. — A pad of wool placed in the lower por- 
 tions of ao-ne types of axle boxes, from which oil is led up by capillary 
 attraction through tapes of cotton wool to the bearing. It rests on a 
 horsehair cushion saturated with oU. 
 
 Wrench. — A spanner (q.v.) one of whose jaws is rendered adjustable by 
 the agency of a screw, for nuts of narrow sizes. See Screw Wrench. 
 The term is often appKed to any form of spanner. 
 
 Wrinkling. — The failure of thin unstayed or improperly stayed wrought- 
 iron plates, by wrinkling up, or the becoming corrugated under pressure. 
 
 Wrinkling Strain. — The strain necessary to produce wrinkling- (q.v.). 
 
 Wrist. — Sometimes applied to a crank pin, or to any projecting pin which 
 receives a connecting rod. 
 
4i6 DICTIONARY OF TERMS USED IN 
 
 Wrist Plate, or Motion Disc, or Eocking Disc. — The plate attached to the 
 side of the cyhnder of a CorUss engine (q.v.), through -which motion is 
 transmitted by connecting rods to the Talve spiadle. It is "worked by 
 levers. 
 
 Wrought Iron. — Iron which has had the major portion of its carbon, as 
 weU as the foreign elements which -would afieot its workability, re- 
 moved in the various processes of puddling, shingling, and rolling. Its 
 value lies chiefly in its great tensile strength, averaging about twenty- 
 three tons per square inch, in its capacity for welding, and its ready 
 malleability. See App. 
 
 Wrought-Iron Castings, or Mitis Castings, — Made by a recent process 
 of melting and pouring -wrought iron into moulds, by which the expense 
 of forging is saved. The wrought iron is melted in crucibles in a 
 petroleum furnace, and poured into a mould containing a patented 
 mixture composed essentially of fire clay, burnt and ground, and mixed 
 ■with molasses. The metal is dead melted or superheated by the addition 
 of about 0-1 per cent, of aluminium, by which its melting point islowered, 
 and the entrance of deleterious gases due to the superheating of the 
 metal alone, is prevented. It is thus rendered sufficiently fluid to take 
 •the finest impressions of the mould, while its quality as -wrought iron 
 remains unimpaired. These castings do not require to be annealed, 
 and while cold can be bent and twisted like good malleable iron. 
 
 Wrought-Iron Plates. — Plates which have been rolled from iron pre- 
 pared by puddling. See Boiler Plate, Ship Plates, Limit of Weight, &o. 
 
 Wrought-Iron Pulleys. — These are rapidly superseding the old cast-iron 
 pulleys, from their superior lightness and reliabOity. The rims are 
 framed of -wrought iron or steel, and the arms are of the same material, 
 each being made distinct from -the other, and fastened together. They 
 are put together in halves, and are, therefore, split pulleys (q.v.). 
 There are numerous designs of thgse pulleys in the market. They do 
 not break, put less strain upon the shafts, are more easily fixed, and, 
 though costing more in the first place, are cheaper in the end than 
 those of cast iron. 
 
 Yacht Engine A light engine specially designed to drive the screw of 
 
 a yacht. Yacht engines are mostly of the inverted cylinder (q.v.) and 
 compound engine (q.v.) types. 
 
 Yank. — To puB, -wrench, or hammer -with undue violence. A slang 
 term. 
 
 Yard Travellers. — Ordinary overhead travellers, used for lifting heavy 
 work about an engineer's yard, both for erecting and loading. They 
 are worked by hand or steam -with ordinary gear, or with hempen 
 ropes. 
 
 Yam. — Pibres of prepared hemp twisted together into small cords in 
 readiness for laying into strands. 
 
 Yellow. — See G-amboge. 
 
 Yellow Bath, or Prussiate Bath. — A bath containing a saturated solu- 
 tion of the yellow prussiate of potash K2 Fe Ce Ne, and which is used 
 for developing the lines of phototypes (q.v.) which are removed to the 
 
MECHANICAL ENGINEERING. 417 
 
 bath from the printing frame (q.v.). This bath is lined with gutta- 
 percha. 
 
 Yellow Brass. — A cheap kind of brass formed of an aUoy of copper 70 
 paits, zinc 30 parts, and used for the commoner class of turned and 
 other work, and also for name-plates and similar castings when 
 durability and strength is not essential, or when flexibility is desired. 
 
 Yellow Metal. — See TeUow Brass. 
 
 Yellow Pine [Fimis variabilis or Pinus mitis) . — The wood of an American 
 pine of the natural order Coniferm. A light faintly yeUow-eoloured 
 wood, open grained, not much given to warping, and pleasant and soft 
 to work. It is employed chiefly in the making of patterns (q.v.). Sp. 
 gr. 448. A cubic foot weighs 28 Ihs. 
 
 Yield. — The quantity of iron or steel produced by a blast furnace, a, 
 puddling, or similar furnace, in a given time. 
 
 Y Lever. — The longest lever of a weighbridge, to which the rod of the 
 actual steelyard la attached. 
 
 z. 
 
 Zero. — (1) In mathematics, signifies 0, or nothing. (2) In thermometry, 
 commonly denotes the temperature obtained by a mixture of salt and 
 snow; or the zero of Fahrenheit's scale, being 32°, corresponding with 
 0° on the Centigrade scale. This is the zero point used in practice ; 
 but sometimes it is convenient to reckon from absolute zero (q.v.) . 
 
 Zigzag Riveting. — Bows of rivets placed parallel longitudinally, but 
 alternately, or in zigzag form in the transverse direction. 
 
 Zinc. — Symbol, Zn. Comb, weight, 64'9. An easily oxidizable metal, 
 used as an aUoy for brass (q.v.). The oxidization of zinc, when in 
 the brass-melting furnace, is prevented by throwing borax, powdered 
 glass, or powdered charcoal over the surface. It is valuable also 
 because of its being an element electro positive to iron. In this 
 capacity it is employed to prevent the corrosion of steam boilers ; for ii: 
 strips of zinc are suspended therein they are wasted away ; whilst the 
 iron plates remain unaffected. 
 
 Zinc Oxide, or Zinc White. — Used as the basis of a white paint. 
 
 Zones. — Zones signifies the various horizontal sections or areas of a blast- 
 furnace, corresponding with certain chemical reactions which take place 
 between the hot gases and the metal ; accompanying the formation of 
 CO2, and the reducing agent CO. 
 
APPENDIX. 
 
 A. 
 
 Alnminitim (see Diet.) is now produced at a eomparatively low coat, toth 
 in the pure state and alloyed witli other metala. In lie first case the 
 Castnar process is employed ; in the second the Cowles. In the Castnar 
 process tiu:ee stages are requisite : (1) the manufacture of sodium, (2) 
 the manufacture of a double chloride of sodium and aluminium, (3) the 
 reduction of aluminium. In the Cowles process, the ores of aluminium 
 are reduced by the electric current, conveyed from a dynamo through 
 copper bars to electrodes within the furnaces. The electrode consists 
 of a bundle of carbons, to which a cylindrical head of metal is cast (iron 
 for ferro-aluminium, copper for aluminium bronze). The aluminium 
 on being reduced, ascends with its alloying metal in the form of vapour, 
 and on reaching the cooler parts of the furnace, becomes condensed and 
 runs to the bottom. The price of aluminium is about half-a-crown a 
 pound, in quantities of not less than two owt. 
 
 Aluminium Bronze. — An alloy of copper with aluminium, in various and 
 widely differing proportions. A tensile strength as high as 67'9 tons 
 per in. has been obtained with this material ; and with a tensUe strength 
 of 33'4 tons, an elongation of 66 per cent, in 2 in. Professor Unwin 
 gives, as the result of a test on a specimen bar J in. in diameter, a 
 tenacity of 36'78 tons per square in., an elongation in 10 in. of 33'26 per 
 cent., a contraction of 39'87 per cent., and an elastic limit of 17'74 tons 
 per square in. 
 
 American Cloth. — Sometimes used with red lead and oil, to form the 
 steam joints of flanges, in a similar manner to gauze wire, or asbestos 
 sheet. 
 
 Angle Wheels, or Twist Wheels. — A form of screw gearing (q.v. in Diet.) 
 in which the teeth form portions of many threaded helices, and by 
 means of which motion is transmitted between shafts which cross each 
 other, but are not parallel. In these wheels, the friction between the 
 teeth is wholly that of sliding, hence their wear, and the mechanical 
 loss occasioned are excessive. Skew bevels (q.v. in Diet.) are some- 
 times used in preference to angle wheels, because they develop less 
 friction. 
 
 Angus Smith's Process. — A process employed for protecting water-pipes 
 from corrosion. The pipes are heated to 310° Fahr., and immersed in a 
 bath of pitch, to which a little oil is usually added, the temperature of 
 the bath being not less than 210° Fahr. 
 
 Animal Charcoal, — Denotes the material used for case-hardening of the 
 most efficient character, as distinguished from the very superficial 
 hardening effected by potash. (See Case-hardening in Diet.) The 
 
APPENDIX. 419 
 
 animal charcoal comprises the leather clippings, horns, hoof parings, 
 bones, &o., used in the case-hardening box (q.v. in Diet). 
 
 Arboring, — Signifies the shouldering back of a flat bearing face, to reoeiye 
 the washers and nuts of attachment bolts. It is done by means of a 
 broad facing cutter wedged transversely in a, boring bar, or arbor. 
 Where hollows or angles intersect flange faces, and where the surface 
 of a casting is from any cause uneven, arboring is usually and properly 
 resorted to. 
 
 Axle Box Slide. — ^A stout casting composed of two plane portions standing 
 at right angles, and stiffened with internal brackets. Used for the 
 same purpose as a horn block (q.v. ia Diet.). The horn block is a 
 single casting ; the shdes are riveted, — one on each side of the axle box. 
 
 B. 
 
 Barrel Wheel. — The large wheel which is keyed upon the same shaft as 
 the lifting barrel of a crane, and by which the barrel is directly revolved. 
 It is the last one in the train of gearing. 
 
 Barring. — (1) The turning round of an engine flywheel with an iron bar, 
 to get the engiue over dead centres (q.v. in Diet.) in readiness to start. 
 Points of leverage or fulcra are afforded by fixed pins, suitably placed 
 adjacent, and a few holes are drilled in the flywheel to take the point 
 of the bar. (2) Also the initial turning of a large engine by a smaller 
 engine. (3) Poking away lumps of fuel from the immediate vicinity 
 of the tuyere holes of a cupola, an iron bar being thrust through the 
 sight hole for the purpose, in order to make a free passage for the 
 blast. 
 
 Basic. — Being of a highly metallio character. Thus, slags are said to be 
 basic, when they contaiu a large proportion of metalHc oxides. 
 
 Basic Process (see Diet.). — The dolomite is either ground and burnt, and 
 mixed with anhydrous tar (q.v.) to cement it together, or it is made 
 into bricks and laid with tar. Lime is added to the charge of metal, in 
 the proportion of from 1 to 3 cwts. per ton of steel produced, and 
 this in the presence of the basic lining combines with the phosphoric 
 anhydride P2 O5, formed by the oxidation of the phosphorus, yielding 
 calcic phosphate, which passes out with the slags. In the basic process 
 inferior pigs, or those containing from one to three per cent, of phos- 
 phorus, can be used, while in the acid process (q.v.) the purest hematite 
 ores have to be employed. 
 
 Batter. — The slope or angle given to a wall or chimney. 
 
 Bessemer Process (see Diet.). — The process is divisible into well-marked 
 stages : — the first, during which the graphitic carbon passes into the 
 combined form, lasting about four minutes ; thcsecond or boiling stage, 
 during which the carbon is being oxidized by the blast, the carbonic 
 oxide formed burning in long yellow flames ; the third or "fining" 
 stage, followed by the "drop," which marks the complete decarbon- 
 ization of the charge. It is at this stage that the converter is turned 
 down and the Spiegel, or ferro, introduced, which produces a long jet of 
 flame, indicative of the recarbonization which is taking place ; fifteen 
 or twenty minutes elapse between the commencement and termination 
 of the process. The oxidation of the carbon, silicon, &c., by the atmo- 
 sphere produces sufficient heat not only to keep the metal fluid, but to 
 increase its temperature. 
 
420 APPENDIX. 
 
 Binder Pulley. — A pulley, the sole function of wMoli is to bind or 
 tighten a belt or cord on its driving and driven pulleys, when, owing to 
 extension or shrinkage of the belt or cord, the tension becomes vari- 
 able in amount. The binder pulley is properly made adjustable. 
 
 Blue Heat. — A range of temperature between about 470° and 600° Fahr. 
 corresponding with a blue black colour, during which steel becomes 
 injuriously affected by work done upon it. Bending a strip once only 
 while at a blue heat alters the material for the worst, notwithstanding 
 that it may be bent cold with relatively little injury. 
 
 Bob. — A lap (q.v. in Diet.). 
 
 Bobbing. — A term sometimes applied to the lapping (see Lap in Diet.) 
 of metals, the lead or copper lap being termed a bob. 
 
 Body Flange. — When a pattern flange is fitted temporarily over the body 
 or outside of a pipe, for convenience of sliding it along into any position 
 for stopping off odd lengths, it is called a body flange, to distiuguish it 
 from the flanges which are fitted in grooves permanently, at the ends of 
 pipe patterns. 
 
 Boring. — In strictness, the term boring has reference to the cutting out 
 of holes of large size, the term drilling relating to those of small 
 diameter. StiU, the term is somewhat vague and loosely applied, since 
 we speak of boring bits, boring lathes, which operate on small as well 
 as large holes. A more comprehensive definition would be, that boring 
 relates to the formation of holes vrith tools having a single cutting edge 
 only, while drilling signifies the formation of holes with tools having 
 two cutting edges. 
 
 Boss Tools — Moulders' sleekers (see Sleekers in Diet.) used for smoothing 
 the sides and bottom faces of boss moulds. The body of the tool is of a 
 hollow semicircular cross section, and has a flat horizontal set-off piece 
 at the bottom. It is attached to a long vertical handle, or stalk, above. 
 
 Bottom Clearance. — The distance between the points of the teeth of one 
 wheel and the roots of another wheel which are in mutual engagement, 
 the clearance being given to prevent injurious grinding and friction 
 between points and roots. 
 
 Breaking-down Point. — See Yield Point. 
 
 Brick-work Flues. — (1.) The external flues in a Lancashire or Cornish 
 boiler, forming spht draught, or wheel draught, as distinguished from 
 the internal flues in the boiler itself . (2.) Chequering (q.v. in Diet.). 
 
 Broad Cutting. — The taking finishing cute, of considerable width, with 
 square-nosed tools, off the surfaces of turned or planed work. 
 
 Buckstaves. — The cast-iron plates which form the outer casings of rever- 
 beratory fumaoes, and which are supported by the bolts passing from 
 one side to the other. 
 
 Building Up (see Diet.). — The advantage of building up is that all the 
 shrinkages of the timber are looaHsed in the short segments, and that 
 the breaking of the joints and overlapping of the grain in different 
 directions increases the strength vastly, both matters of vital import- 
 ance in pattern work. The piling of iron and steel bars causes increase 
 of strength by a crossing and intertwining of the various grains and 
 quaUties. 
 
 Bull Metal. — An aUoy which is used for hydrauHo and marine work, and 
 for gun fittings, both in the form of bar and of castings. The tough- 
 ness and ductility of the alloy increase with high temperatures, so that 
 at 400' Fahr. the strength of roUed bull metal is equal to that of mild 
 steel. 
 
APPENDIX. 421 
 
 c. 
 
 Calciner. — Specifically, a reTerberatory furnace (q.v. in Diet.) having a, 
 hearth of large area nearly as broad as long, and used in the roasting 
 of the ores of copper. 
 
 Caliper Gauge. — A horseshoe gauge (q.v. in Diet.). 
 
 Cape Chisel. — A term sometimes applied to a cross-cut chisel (q.T. in 
 Diet.). 
 
 Carbon Steel. — Denotes common steel, or that which is produced by the 
 union of a definite quantity of carbon with iron. This term is neces- 
 sary, since alloys possessing steel-Uke qualities are now made by a 
 union of iron with manganese, silicon, or tungsten. 
 
 Carping. — A term used in North Britain to denote the alteration in form 
 which timber undergoes by shrinkage. Synonymous with Warping. 
 
 Cast Iron (see Diet.). — The tensUe strength of cast iron seldom averages 
 more than seven or eight tons per square inch, but its compressive 
 strength varies from thirty-five to forty tons. In rough calculations 
 the weight of a cubic inch of iron is usually taken at •263 lbs., and 
 of a cubic foot at 450 lbs. ; but this is necessarily approximate, since 
 grey, white, and mottled irons have different sp. gravities. Grey iron 
 melts at from 1600° C. to 1700° C, and white iron at from 1400° C. to 
 1500° C. 
 
 Cast Steel (see Diet.). — The object of casting being to obtain greater 
 homogeneity than is possible in the process of cementation(q.v.), various 
 ingredients are often added to the bUater steel in order to obtain certain 
 grades of temper, or bar iron is fused with carbon, spiegeleisen, or black 
 oxide of manganese. The steel is melted in crucibles in a melting- 
 house (q.v.), and either poured, or ** teemed " into sand, or into ingot 
 moulds direct ; or, if the quantities melted are larger, the contents of 
 several crucibles are either poured into a large ladle, and thence into a 
 large ingot-mould, or are emptied into a numer or trough, which 
 empties their contents into a large ingot-mould. 
 
 Cementation Furnace. — The furnace used for the conversion of bar iron 
 into blister steel. It is an oblong, arched chamber of fiLre-briok, sup- 
 plied with small chimneys leading into a. tall stack. The chamber 
 contains a fireplace, running longitudinally between two oblong troughs 
 or pots, in which the bars are converted into steel. These may measure 
 12 ft. Oin. long, by 3 ft. Oin. wide, by 3 ft. in. deep. The pots rest 
 upon and are fianked by a series of bearers and divisions of masonry, 
 which form channels for the diffusion of the heat and fiame from the 
 fireplace. There is a tap hole in one end of each pot to receive the 
 proof or trial bars. The furnaces are buUt in ranges of five or six. 
 
 Centre-bit (see Diet.). — The hole bored is equal to twice the radius of 
 the nicker. Centre-bits are not so suitable for the best work as the 
 Jeimings and Gilpin's bits with double nickers, and double cutters ; 
 because in these the cutting forces are equally balanced around the 
 centre, which is not the case in the common centre-bits. The double 
 cutting bits win bore therefore in any direction of the grain, while 
 the others will only bore well "plank way," that is, parallel with the 
 direction of the fibres. Expanding centre-bits are those in which the 
 nicker and cutter are adjustable in the shank. 
 
 Change Point. — In a workable machine the relative motions of all its parte 
 must be completely constrained. If, however, in any portion a want of 
 
422 APPENDIX. 
 
 constrainnient occurs — that is, if through lack of proper coercion it i8 
 possible for that portion to remain still, or to take some other motion 
 than that intended, that position is termed a change point. Constrain- 
 ment is usually brought upon changed points by duplication of the 
 mechanism, so that one portion is in complete constrainment whilst the 
 other is passing its change point. An example occurs in pairs of 
 coupling-rods or links with their cranks, placed at 90° of angle with 
 each other. 
 
 Change Valve. — ^A valve used on a hydraulic crane, for directing the 
 water pressure into two or three lifting cylinders at pleasure, either 
 singly or in combination, in order to obtain different degrees of power 
 adapted to the load to be lifted. It is operated by a slide valve passing 
 over ports. 
 
 Choking of Vents. — See Vents, Choking of. 
 
 Cinders, or Ashes. — Are used to assist in the venting of moulds and of 
 cores. Where large central spaces exist in cores or in moulds, whether 
 they are made in green sand, dry sand, or loam, these are filled with 
 cinders, roughly, of sizes ranging from f in. to J in. in diameter. The 
 air from the numerous vents collects in these, and is carried away quietly, 
 instead of rushing out with difficulty. The vents from large cores 
 are also often collected and brought out through vent pipes (q.v. in 
 Diet.) into a body of ashes placed outside the core, against the termina- 
 tion of its vents, and the vent to the outside of the mould is placed in 
 communication therewith. Cinders of larger size, say from 1 in. to 
 2 in. in diameter, are used in the formation of coke beds. (See Coke 
 Bed in Diet.) 
 
 Circumferential Pitch (see Diet.). — It is this pitch which is usually and 
 conveniently made the basis of calculation in screw wheels, and heUcal 
 gears, because more easy of measurement than the norma] pitch (q.v.) 
 notwithstanding that the latter is the true pitch on which the tooth 
 sections should be properly based, and which must always coincide 
 in wheels gearing together ; whereas in screw wheels, having different 
 angles of thread, the circumferential pitches will differ also. 
 
 Clagg. — Denotes the sticking of sand to a pattern, which is damaging 
 to the rox)uld. 
 
 Cod. — This term is often used in the foundry, to denote a green sand core, 
 a mass of sand upon a drawback, or any loose portion of green sand, — 
 as a " cod of sand." This term is also sometimes used to denote a small 
 tongue, or filling-np piece, such as a glut. 
 
 Cold Blow. — A cold blow is said to result when the percentage of foreign 
 elements, such as sUioon and phosphorus, undergoing oxidation in a 
 Bessemer converter, is not sufficient to maintain the high temperature 
 required for the successful conduct of the process. (See Bessemer 
 Skulls in Diet.). 
 
 Cold Soldering. — This really is a process of amalgamation of metaUio 
 surfaces by the aid of mercury. A hard amalgam is made of five, or six 
 parts of pure silver, three or four parts of tin, and three to five per 
 cent, of bismuth. This alloy is melted and oast into ingots, the ingots 
 reduced to fine filings, and these filings mixed, when required, with 
 enough mercury to form a stiff paste, which hardens in about an hour. 
 
 Coming-down. — Boiler crowns are said to "come down" when the 
 plates are bulged downwards into the firebox through overheating, due 
 to the accumulation of deposit thereon. 
 
 Compensating lever. — An equal-armed lever, which is used to obtain a 
 
APPENDIX. 423 
 
 mean between tmequal pressures. In the locomotive, the lever is a 
 rigid bar, pivoted at its centre, and the ends of its equal arms aro 
 attached to the springs at front and back, thus equalising the loads on 
 their vrheels, and so rendering the engine less liable to injurious jerks 
 and jars when running over rough ways. The reason is obvious, since 
 for a lever with equal arms to be in equilibrium, the initial forces 
 acting thereon must immediately become equalised. 
 
 Copper Smoke. — The gases which escape from the hearth of the reverbe- 
 ratory furnace in which the calcination of copper ores is performed. 
 They consist of sulphurous acid, with a little of the vapour of sulphuric 
 acid, aa?senions acid, and hydrofluoric acid gas. 
 
 Core Vents. — The methods of venting cores do not differ materially from 
 those employed for moulds (see Venting, in Diet.). Cores are vented 
 with the wire, and with ashes, with stemgs or ropes, and with rods, 
 and the sand employed is also, when dried, of a porous character. Core 
 vents require to be well secured where they fit into their prints, or into 
 one another, or where they abut against the mould. Wet loam is often 
 daubed around to secure these, and dried with a " devil," or open fire. 
 
 Counterbore (see Diet.). — Signifies also to bore a large hole concentric 
 with another and smaller hole, the hole thus bored forming a recessed or 
 shouldered portion to the other, to receive the head of a cheese-headed 
 screw, or of a shouldered pin. A pin drill is commonly used in 
 counterboring. Sometimes the pin drill itself is termed a counterbore. 
 The term is also sometimes used to signify the simple enlargement of 
 holes already drilled with a smaller drill, not in the sense of reaming, 
 but of enlarging with a pin drill. The enlarged portion of the bore of 
 a cylinder into which the covers are checked is called the counterbore. 
 
 Counter, or Engine Counter. — An automatic recorder for registering the 
 number of revolutions made by an engine. The motion of the engine is 
 transmitted to the counter, either from a reciprocating part of the engine 
 by a pawl and ratchet wheel, or from a revolving part by means of an 
 endless screw. An index-hand registers the number of revolutions. 
 
 Countersunk Eivet. — A rivet, the head of which is shaped to fit into a 
 countersunk hole, so that it lies flush with the face of the plate or bar 
 in which it fits. It is employed in cas-^s where a flush face is necessary, 
 in order to permit of the attachment of other pieces of work. 
 
 Crank Hoop. — A hoop of wrought-iron or of steel shrunk around the 
 webs of locomotive cranks, with a view to prevent accident in case of 
 sudden fracture of the web. 
 
 Cup Drum. — A term sometimes used to denote that form of sheave- wheel 
 (q.v., in Diet.) the rim of which is recessed out for the individual links 
 of a chain. 
 
 Curving of Castings. — When castings are badly proportioned, that is, 
 when there are light, and heavy flanges or ribs in close proximity, the 
 cooling does not take place regularly, and then one portion becomes 
 "drawn" by the other, becoming curved in consequence. Usually, 
 the section having heaviest metal goes concave lengthwise, but this is a 
 general rule only, since in some cases the opposite condition obtains. A 
 knowledge of the amount and manner of curving can only be gathered 
 by experience, and then but imperfectly. 
 
 Cylinder Ratio. — The ratio between the capacities of the cylinders in 
 compound engines. Speaking generally, the ratio equals the initial 
 pressure in the cylinder, multiplied by the number of tenths of the 
 stroke during which it is required to admit the steam in the high- 
 
42^ APPENDIX. 
 
 pressure cyKnder, di-vided by tlie constant 105. But a very considerable 
 variation is permissible. 
 
 D. 
 
 Dead-Hole. — A hole trkicli is not a thorougMare bole ; that is, one that is 
 bored only for a certain distance into a piece of metal. This term is 
 nsed chiefly in connection -with the use of taps, the plug and bottoming 
 taps being made expressly for tapping dead-holes, which could not be 
 reached with taper taps. 
 
 Delta Metal. — An alloy of copper and zinc, with a small quantity of iron. 
 It is prepared in various grades, both oast and forged. I^om tests 
 made by Mr. Kjrkaldy the following results were obtained : — A specimen 
 cast in sand, having an area equal to one square inch, stood an ultimate 
 stress of 20-9 tons, and an elastic stress of 7'9 tons, and also an ultimate 
 percentage elongation of 19'1 in 10 in. AroUedbar of the same section 
 gave an ultimate strength of 33'9 tons, an elastic strength of 21'8 tons, 
 anda percentage elongation of 21'6 in 10 in. A similar bar, annealed, 
 gave 29'8 tons ultimate stress, 9'6 tons elastic stress, and an elongation 
 of 34-7 per cent, in 10 in. Delta metal is readily cast and forged. It 
 is adapted for screw propellers because it has good resisting power to 
 corrosion. It is also suitable for amaU-gear wheels, being stamped hot 
 in suitable dies, and for pump-work, and ornamental fittings. 
 
 Diametrical Pitch (see Diet.) . — It denotes the number of teeth in one inch 
 of pitch diameter, and bears the sam.e relation to the diameter of the 
 pitch circle that the circular pitch (q.v.) does to the circumference of the 
 pitch circle. Hence, dividing the circular pitch by 3'1416 gives dia- 
 metrical pitch, and vice versa. Or, since dividing by 3'1416 is the same 
 
 as multiplying by ■3183, because = '3183 ; multiply the circular 
 
 pitch by ■3183 to obtain diametrical pitch. 
 
 Die Forging. — ^The forging of smiths' work in dies is largely practised in 
 the case of repetitive work. The dies are of cast iron, or of ■(vrought 
 iron, or of steel. Speaking generally, steel is used for small forgings, 
 cast iron for large ones. Dies are single, or double. If the top portion 
 of the forging is plain, a single bottom die suffices ; if otherwise, a por- 
 tion of the forging is formed in a top die. The accurate closing of the 
 two portions is controlled by long pins, or dowells, passing from one 
 into the other. The forging takes place under the Oliver, or the drop 
 hammer, or the steam hammer, or the forging press. Care has to be 
 taken in cutting off the exact quantity of metal required for the forging, 
 in order that on the one hand the forging shall finish clean and shai'p 
 everywhere, and that on the other there shall be as little superfluous 
 fin as possible. 
 
 Differential Principle. — T%e mechanical principle which has for its basis 
 the difference between two members connected rigidly together, by the 
 application of which in various machines, a very large mechanical gain 
 is obtained with a small expenditure of power. It denotes in general 
 the compounding of two or more distinct motions in such a way that 
 uniform variations of speed shall be Imparted to certain pieces of 
 mechanism relatively to one another. In the Chinese windlass, in the 
 wheel and axle, the differential sore'w, and diflferential pulley block, the 
 principle is embodied. 
 
APPENDIX. 425 
 
 Distrilmtion Valve. — A main slide valye, or main valve (q.v. in Diet.), as 
 distinguislied from an expansion valve (q.v.). 
 
 Drop Hammer. — A heavy hammer used for forging. It slides between 
 vertical guides, and is suspended by a broad leather belt that passes 
 over and is attached to a pulley of large diameter overhead, and to 
 ■whose opposite end, cone or other gear is attached, by which the weight 
 is lifted. Very little power is required to lift the hammer, because 
 most of the load is lifted by the leverage of the puUey and the breadth 
 of the belt, these being so proportioned as to produce this effect. The 
 throwing out of the cone allows the hammer to fall. 
 
 Dry Puddling. — "White or refined iron (q.v.) only, is suited for dry puddling. 
 In dry puddling the principal oxidizing agent is the atmosphere, which 
 plays over the surface of the pasty metal on the furnace bed, but the 
 action is assisted by hammer scale (q.v.) added to the charge, and the 
 oxide of iron forming the bed. The pasty metal is rabbled over the bed 
 to assist the oxidizmg action, the carbon being removed as carbonic 
 oxide, while the silicon, sulphur, phosphorus, manganese mostly enter 
 the tap cinder in the form of oxides. As the metal becomes purfeed its 
 fusibility decreases ; it is then said to " come to nature," and is balled 
 up in readiness for squeezing. 
 
 E. 
 
 Electrically Deposited Copper. — See Seamless Copper Tubes. 
 
 Electric Crane. — A crane driven by a dynamo independent of the mecha- 
 nism of the crane, the electric current being conveyed along copper rods, 
 rubbers or strikers sKding along the rods and communicating with an 
 electro motor on the crane. The mechanism of the crane is generally 
 that of a steam crane, driven by friction clutches, but in consequence of 
 the high speed of the motor it is necessary to introduce extra gear to 
 reduce the speeds for all motions. Overhead travelling cranes are also 
 driven by the electric current. 
 
 Electric Welding. — A process invented in 1886 by Professor E. Thomson, 
 the electrician of the Thomson-Houston Electric Company, of Boston, 
 United States of America. The process is based on the principle that 
 the electrical resistance is greater at a break than at any other portion 
 of a conductor. Its application consists in applying the ends of two 
 pieces of metal to be welded together, and passing a strong alternating 
 current through the jointure. The heating due to the resistance at thS 
 point fuses the surfaces. The industry has developed latterly with 
 great rapidity. AH kinds of metals and alloys can be thus united, and 
 also dissimilar metals and alloys, and nearly all sections and sizes, from 
 wire, up to sections of several square inches. Machines are in use for 
 the purpose. At the moment of welding, pressure is used, varying with 
 the material. For copper a pressure of about 600 lbs. per square inch, 
 for iron 1,200 lbs., for steel 1,800 is employed. 
 
 Elliptical Gears. — Gear wheels, the pitch peripheries of which are 
 elliptical in outline. In elliptical gears, the centres of whose shafts 
 are placed in the intersections of the conjugate and transverse diameters, 
 there are four rates of revolution, two maximum and equal, two 
 Tni'Tn'mnTn and equal, coinciding with the major and minor (fiameters. 
 These are, therefore, variable gears (q. v.) . Elliptical gears, the shafts 
 of which are in focal centres, are used occasionally for producing a quick 
 
4*6 APPENDIX. 
 
 return (q.v. in Diet.) motion. Then the shaft of the driven wheel has 
 to be movable in space. 
 
 £picyclic Train (see Diet.). — The peculiarity of this gear is that the axis 
 of one wheel being fixed, the axes of the others rotate round it, and these 
 consequently have a motion compounded of their own rotation round the 
 fixed wheel, and of the rotation of their axes in space. Thus, suppose 
 two equal wheels : the one having the movable axis will turn round once 
 in a complete revolution round the fixed wheel, and once more by reason 
 of the revolution of its axis round that of the fixed wheel. Hence it 
 will malce two revolutions in the course of one rotation around its fixed 
 or dead wheel. Any number of wheels may be combined in an epicyclio 
 train, but their relative motions will be calculated on the basis of the 
 two classes of rotation. 
 
 Ezhanst Injector. — A form of injector by means of which exhaust steam 
 at the atmospheric pressure is made to force water into a boiler against 
 steam of high pressure. The arrangement of the mechanism is designed 
 to cause the exhaust steam to come into contact with the cold water in 
 the combining cone, and produce condensation, and a partial vacuum, 
 into which more steam and water rushes, improving the vacuum, until 
 sufficient velocity and force are generated to overcome the back pressure 
 due to the steam in the boUer. 
 
 External Flues. — Boiler flues which are placed without the boiler shell, 
 as ia waggon and haystack boUere, and the brickwork flues in Cornish 
 and Lancashire boilers. (See Split Draught, "Wheel Draught, in Diet.) 
 
 F. 
 
 f. is the symbol commonly used by engineers to signify stress. 
 
 Factor of Safety (see Diet.). — If the calculation is one determining the 
 load on a structiire, the load corresponding with the ultimate strength 
 will be divided by the factor of safety in order to give the safe working 
 load. The factor of safety may also be determined in reference to the 
 elastic strength of the structure instead of by its ultimate strength. 
 This, divided by the factor of safety, will give the safe working load. 
 Factors of safety will range from about three in iron structxires, 
 subject to dead loads only, to ten in structures in the same material 
 subject to Uve loads, and will reach twenty or more in the case of 
 masonry. 
 
 Feather Edge. — A keen edge, or, as the workmen say, an edge going off, 
 or tapering off, to nothing. 
 
 Feed Gear. — The mechanism, usually automatic, by which the extent of 
 the operations of cutting tools used in machines is governed. Com- 
 binations of gearing, feed screws, ratchet wheels, &c., are variously 
 employed ; with the result of imparting a precise and definite amount 
 of forward or downward movement, either to the tool or to the work, 
 immediately after each cutting stroke. 
 
 Flame Fine. — The combustion flue of a horizontal boiler, so named to 
 distinguish it from the smoke or return flues which are built in brick- 
 work. 
 
 Flank Clearance.. — The amount of clearance or space between the flanks 
 or sides of wheel teeth, which are in mutual gear. 
 
 Fining. — The process of refining pig iron in the process for the manu- 
 facture of coke plates. (See Coke plate in Diet.) 
 
APPENDIX. 427 
 
 Finning. — The joint edges of a dried sand mould are more tender and 
 fragile than those of a green 8and mould ; and it, at the iinal closiag 
 of the iiasks, thej come into such contact that sensible pressure occurs 
 between the opposite faces of the mould, the edges 17111 become fractured, 
 and the loose sand f aUing into the mould "wiU perhaps produce a waster 
 casting. To prevent this crushing, the edges are pressed down with 
 the trowel, while the mould is yet green, so that actual contact of the 
 faces does not occur. This process is termed firming, because a thin 
 sheet of metal or "fin" forms in consequence around the joint edges 
 of the casting. This is easily chipped off, and entirely prevents risk of 
 crushing of the mould. 
 
 Floor Plates, or Foot Plates. — The plates of oast or of wrought iron 
 which cover the area immediately^in front of an engine furnace. Cast- 
 iron foot plates are chequered over, those of wrought iron are tesselated 
 in order to afford a firm foothold for the stoker. 
 
 Fly Bope. — A term often used to denote a rope of cotton or hemp used for 
 telodynamio transmission of power. The term has reference to the 
 high speed at which such ropes are driven. 
 
 Fork Scriber. — A scribe (q.v. iu Diet.), the outline of which is something 
 like that of a straight spanner, but the ends of the horns are tapered 
 and pointed, and are used as rigid compasses for describing a number 
 of circles all of the same size. 
 
 Foundation King. — The ring which forms the base of a locomotive fire- 
 box, and to which the plates of the inner and outer boxes are riveted. 
 It is of square cross section, and of rectangular outUne in plan 
 view. 
 
 G. 
 
 Gap Gauge. — A form of plate gauge used by smiths. It is made by 
 cutting a series of notches of different definite sizes in the edge of a 
 piece of plate. These notches are sKpped over those portions of a flat 
 or round bar which are being forged to a required size. Thus, the 
 delay and inconvenience attending the measurement of red-hot metal 
 by means of the rule, or ordinary calipers, are avoided. 
 
 Gas Furnace. — A regenerative furnace (q.v.) or specifically a reheating 
 furnace (q.v.) in which gaseous instead of solid fuel is used. The gas 
 may be made iu a portion of the furnace itself, as in the Boetius, 
 Bicheroux, and Ponsard furnaces, or in a separate producer, as in the 
 Siemens. These are essentially reverberatory furnaces, either with or 
 without regenerators. The Siemens and the Ponsard furnaces are 
 constructed with regenerators, the Bicheroux and the Boetius without. 
 
 Goliath Bails. — Heavy rails, of 100 lbs. to the yard ; several thousands 
 of tons of which have been laid on the Belgian railways. 
 
 Green Sand Moulding. — All common work, which constitutes by far the 
 largest proportion done, is made in green sand. The sand mixtures 
 used are weak and friable in comparison with dry sand mixtures, and 
 green sand moulds are therefore not adapted to stand the enormous 
 liquid pressure of heavy casts. Sometimes a compromise is made by 
 drying the surface only (see Skin drying). Also, the sand being still 
 damp at the time of pouring, more, and careful venting are necessary, 
 than in moulds made of diy sand, and loam ; and there is a slightly 
 greater risk of waster castings. Thin, narrow, weak comers, and 
 
428 APPENDIX. 
 
 sections of sand, are also more liable to become washed away in green, 
 than in dry sands. Drying increases the cost of the work. 
 
 Grounds. — A term used in North Britain to denote the wood blocking or 
 framiag upon which a piece of mechanism is bolted — a hand winch, 
 for example. 
 
 Guide Screw Stock. — A form of die stock (q.v. in Diet.), originally intro- 
 duced by Sir Joseph Whitworth, in which the want of proper guidance, 
 or the squeezing inseparable more or less from the use of ordinary dies, 
 is much diminished. In this stock the dies are divided into three 
 portions, one becoming the guide, the other two, the actual cutters. 
 The cutters are placed in radial slots, and are very narrow, so that 
 they operate to the best advantage, in opposition to the rigid guide 
 piece. 
 
 H. 
 
 Hand Bamming. — Ramming (q.v.) performed by hand rammers, as dis- 
 tinguished from that effected by means of a presaer (q.v.). All ordinary 
 ramming is necessarily done by hand, the only exceptions being in the 
 case of some few specially constructed moulding machines, furnished 
 with a pressing plate or air bag. 
 
 Hand-Working Tap. — A tap (q.v. in Diet.) which is actuated with a 
 screw wrench by hand, as distinguished from a machine tap (q.v. in 
 Diet.). 
 
 High-Speed Fielding Engine, — The Melding engine is designed on the 
 principle of Hooke's universal joint. There are four cylinders, two on 
 each bow of the joint, the pistons being on each side of the disc. The 
 cylinders and pistons are set in pairs, at right angles with each other. 
 The cylinders and pistons are curved lengthwise, and move in an arc of 
 a circle struck from the point of the two arms. At each revolution, the 
 cylinders, which are single acting, are filled with steam once, and 
 exhausted. The steam enters through ports formed in the faces of 
 bosses to which the cylinders are attached. The faces of these bosses 
 run in rubbing contact with valve faces formed in one with the shaft 
 bearings. These faces have four ports, two in the end face, and two in 
 the side, for steam and exhaust, respectively. The engines are com- 
 pounded, the steam passing from small high pressure, round to large 
 low pressure cylinders. There are no dead points, and they run with- 
 out special lubrication, at 1000 revolutions per minute. 
 
 High-Speed Governor. — The cross-armed centre-weighted governor. It 
 is suited for driving at from 200 to 300 revolutions per minute, and 
 must be driven at high speeds, otherwise the centrifugal force of the 
 balls would not suffice to overcome the gravity of the centre weight. 
 It is very sensitive to sudden changes in the load of the engine, and its 
 power is greater than that of the ordinary governors ; hence its bulk is 
 correspondingly diminished. 
 
 Hobbing. — Cutting the threads of worm wheels, dies, or chasers with a 
 hob or master tap in a lathe. 
 
 Hydraulic Joint. — A form of joint used to connect piping which is subject 
 to water pressure. The flanges are checked into one another by a male 
 and female fitting, terminating in bevelled edges or shoulders, and a 
 ring of indiarubber, screwed up and pressed between the bevelled faces, 
 renders the joint water-tight. 
 
APPENDIX. 429 
 
 I. 
 
 Ingot Iron. — Mild steel, low in carbon, whioli has been prepared by the 
 open hearth, or the Bessemer processes ; a teiin employed to distinguish 
 it from weld iron or "wrought iron. 
 
 Ingot Saw. — A hot iron saw specially constructed for sawing hot ingots. 
 These saws are made several feet in diameter, for cutting ingots of 
 several inches square. 
 
 Intensifler. — A device frequently employed in place of the hydraulic 
 accumulator, for converting a low water pressure into a higher. The 
 water at low pressure operates a piston in a large cylinder, which in 
 turn operates a ram of smaller diameter in a smaller cylinder. The 
 areas of the two cyliaders are proportional to the difEerenoe in the low 
 and high pressures required. 
 
 Interchangeable Gears. — This denotes gears whose teeth are so designed 
 that wheels of any number of teeth, if of the same pitch, will gear to- 
 gether correctly. This can only be secured by designing the teeth on a 
 common basis. The Odontograph scale of Professor Willis effects this 
 result by taking a generating circle of the same diameter as the radius 
 of the smallest wheel of a set (of 11 or 12 teeth in cast gears) and con- 
 structing all the teeth on that basis. Different makers have different 
 rules, but it is necessary that all should be referred to a constant size of 
 describing circle. In any case in iaterchangeable gears, the roots of 
 the small pinions will be weak and those of the larger wheels exces- 
 sively strong. Pinions having a diameter smaller than the one which 
 is taken as the base, will have flanks much undercut, and convex in 
 profile. In change wheels the base may be taken as 15 or 16 teeth. 
 
 Intermediate Gear. — Gear which is interposed between power applied and 
 the work done, for the purpose of obtaining mechanical advantage. 
 
 Intermediate Wheel. — The cog wheel in tiie intermediate shaft of a 
 crane, to distinguish it from the barrel wheel (q.v.). 
 
 J. 
 
 Jockey Weight. — A weight which is slid along a lever, in a weighing or 
 
 testing machine, for purposes of precise adjustment. 
 Jump Weld. — A butt welded joint, formed by bringing the ends of a bar 
 
 together, and jumping them up on the anvil, or with the hammer. 
 
 X. 
 
 Key Gauges. — Plate gauges, both male and female, used for cheeking the 
 width of keys and key seatings, the one being notched to embrace the 
 sides of keys of a given size, the feUow one fitting closely within this 
 notch, and used to cheek the corresponding width of the key way. 
 
 Kinematic Chain. — A kinematic chain, or a closed kinematic chain, is com- 
 posed of a series of kinematic links, so paired together that the move- 
 ment of each link is absolutely constrained in relation to all the others 
 in the chain. When a single link of a kinematic chain is fixed, a 
 mechanism is produced. When the Unks of a kinematic chain contain 
 only two elements, it is termed simple ; when some links contain more 
 than two elements it is termed a compound chain. 
 
 Kinematic Elements. — Signifies certain profiles, or forms, or methods of 
 constraint imparted to bodies in mutual engagement or connection, by 
 means of which their relative motions are absolutely constrained in 
 
430 APPENDIX. 
 
 all possible positions of the bodies. These elements must of necessity 
 always occur in pairs and they are the fundamental elements in all 
 mechanisms. The most important are the turning pairs, and the sliding 
 pairs. The type of the first is the rcTolTing pin with collars, that of 
 the second the sliding block or guide block. The methods of constrain- 
 ment may either take place by surface contact, as in all journal bearings 
 and machine sKdes, and in this case the term lower pairs, or lower 
 pairing is applied to the elements ; or they may take place by line con- 
 tact only, as in the case of cams and screw gears, in which case the 
 term higher pairs, or higher pairing is employed. A third pair of 
 elements is the twisting pair, of which the common screw and nut is a 
 familiar example. 
 
 Kinematic Links. — Bodies which are essential and elementary parts of all 
 mechanisms, as rods, levers, &c., which are connected together by two 
 or more kinematic elements (q.v.) by which their relative movements 
 are rigidly constrained. 
 
 Knife Tool. — An iron turner's finishing tool, which is used for side cutting, 
 and made in right and left hand forms. 
 
 lead Tempering. — A method of tempering sometimes adopted for armour 
 plate. The advantage is uniformity of texture. For heating many 
 classes of cutlery preparatory to hardening, a bath of melted lead, or of 
 an alloy of lead with tin is used. The advantage is that the tempera- 
 tare of such a bath is uniform, and therefore more reliable than the test 
 of colour. By varying the proportions of lead and tin, the tempera- 
 ture of the bath can be varied within a range of more than 200° Fahr. 
 
 lever Crank Chains. — Kinematic links which are connected by pairs of 
 mechanical elements in such a way that one pair being fixed, all the 
 others have movement or motion of rotation. Illustrations occur in the 
 eccentric and crank. 
 
 Lifting Cylinder. — The cylinder of a hydraulic crane, which is used for 
 lifting the load, as distinguished from the turning cylinder (q.v.). 
 There are in the largest cranes, three such cylinders, by means of which, 
 when worked separately, or in unison, different degrees of power can 
 be exerted. 
 
 Lip Drill. — A connnon drill, the cutting faces of which are sUghtly 
 hollowed out backwards, immediately above the cutting edges, in order 
 to give a sKght amount of front rake to the tool. A lip drill cuts 
 faster than an ordinary flat drill, but loses its edge quicker, necessitating 
 frequent re-grinding. 
 
 Liquid. — A fluid which does not expand, but remains in the bottom of a 
 containing vessel when pressure is removed. Liquids are practically 
 incompressible, differing in this respect from gases. But liquids expand 
 by heat, though to a much smaller extent than gases. 
 
 list. — A rim of tin formed along the bottom edges of tin plate during the 
 process of turning, due to the accumulation of the superfluous tin which 
 has drained down. 
 
 M. 
 
 Machine Tapper. — A very useful applianoe by means of which holes are 
 tapped more quickly and accurately than by hand. It is fitted to the 
 
APPENDIX. 431 
 
 socket of a driHiiig macliine, and thus revolved. By means of an 
 internal spring the driving pressure on the tap is released before it he- 
 comes so excessive as to cause risk of fracture of the tap — the socket 
 slipping round merely, without operating. The tap has to he run hack 
 by reversing gear attached to the drilling machine. There is no risk 
 ■with this, as there is with hand-worked taps, of the work being out of 
 perpendicular. And larger, heavier jobs can be done upon the drilling 
 machine, which could not be done in the screwing machine. There are 
 two of these machine tappers in the market — Beams', and Payton's. 
 
 Machine-working Taps. — Taps (see Tap in Diet.) made for use ia a screw- 
 ing machine, and employed chiefly for tapping nuts. They are longer 
 in the shank than hand-working taps (q.v.), so that several nuts may be 
 threaded at one time. They are also taper taps, and thoroughfare taps. 
 
 Macnaughting. — The term commonly apphed in the North of England to 
 the compounding of steam-engines, after Hacnaught, who in 1845 
 patented an engine in which a high pressure cylinder was incorporated 
 with an ordinary condensing beam engine. 
 
 Manganese Steel. — A compound of manganese with iron, for a know- 
 ledge of which we are mainly indebted to the late Mr. Robert Hadfield. 
 Though manganese is present in all steel, the above term is given speeifi- 
 cally to compounds containing more than 7 per cent, or ranging from 
 7 to over 22 per cent. The properties of manganese steel are, extreme 
 hardness, toughness, and duotUity. The effect of water hardening 
 upon it is the reverse of that upon carbon steel, increasing the ductUity 
 as well as the tensile strength. 
 
 Man Power. — Roughly, the tenth of a horse power, or 3,300-foot pounds 
 per minute. 
 
 Motion Plate. — A plate of oast steel, or of rolled steel, or iron plate, which 
 is bolted transversely between the longitudinal frame-plates of a loco- 
 motive, to carry those ends of the motion-bars farthest from the cylinder. 
 The connecting-rods and the valve-rods pass through openings in this 
 plate on their way to the crank axle. 
 
 Movable Centre.- — A centre of motion which is not fixed in space, but 
 which revolves around a fixed centre (<l.v. in Diet.). (See also Epi- 
 oycUc Train.) 
 
 Mutilated Gears, or Segmental Gears. — A term commonly applied to a 
 class of gears not often employed, but which are yet extremely useful 
 in [some kinds of automatic mechanism. In these gears the teeth, 
 instead of being continuous, occupy a portion only of the pitch peri- 
 pheries. Their action is therefore either absolutely intermittent, ceasing 
 altogether for an indefinite period, or partially intermittent, ceasing to 
 operate on one portion of the driven mechanism, but operating instead 
 upon another. 
 
 0. 
 
 Odd Side Monlding. — A term sometimes applied to plate moulding 
 (q. V. in Diet,). 
 
 Oil Bath.' — A bath, or reservoir, of oil, in which revolving parts subject 
 to excessive friction are partially immersed, to provide them with con- 
 stant lubrication. "Worm gearing, when run at a high speed, is often 
 immersed in an oil bath. 
 
 Open Link Chain. — Chain whose links are not stayed or supported 
 across their centres with a stay or stud. Nearly all the chain used 
 
432 APPENDIX. 
 
 by engineers is of the open-link type, and of the close or short-linked 
 class. Chain is made of BB quality of Shropshire iron, having a 
 strength of 26 or 27 tons per square in., tut the ultimate strength 
 of a chain is often 25 per cent, less than this — the reduction of strength 
 being due to imperfect welds, and burning. The safe ■working load 
 of a one-inch chaiu is about six tons. The comparatiye strength 
 of other chains is to the one-inch chain as the square of the dia- 
 meter of the iron from wliich they are made. Another approximate 
 rule for the safe working load of chains is : — square the nxmiber of 
 eighths of an inch in the iron and strike off the last figure as a decimal ; ' 
 the result is the greatest safe worlring load in tons ; if there is a single 
 figure only it represents the decimal fraction of a ton. Chains are 
 tested to about half their estimated breaking strength, and the proof 
 strain is about double the safe working load. Chains should be fre- 
 quently lubricated with oU, applied with a brush. After they have 
 been iu use for several months they become crystalline and brittle ; 
 hence the reason for occasional annealing, which is performed by heating 
 them over a wood fire, or in a core stove, and then allowing them to 
 cool down gradually. 
 Ore Furnace. — SpeoiS.cally the reverberatory furnace (q.v.) used for the 
 meltiug of coarse metal (see Matt, in Diet.). Its hearth is much smaller 
 than that of the calciner (q.v.), or about one-third the size, while its 
 grate is larger. The reason is, that iu the ore furnace the charge has 
 to be raised to the melting poiat, while in the calciner it has to be 
 roasted only. 
 
 Pasting.— Securing together the halves or sections of cores, previously 
 rammed iu separate portions, with clay water or with flour. 
 
 PoU'oleum. — A rock oil, found extensively in the vicinity of the Caspian, 
 and in the United States of America. It occurs chiefly in the Silurian 
 and the lower Tertiary formations. It is employed in various forms for 
 lubrication, and for illumination, and as fuel. The preparations of petro- 
 leum for lubricating have the advantage over oils of animal and vegetable 
 origin, that they do not absorb oxygen from the air, which causes sponta- 
 neous combustion. As heavy oils of this kind do not thicken, and retain 
 their properties when heated, they are valuable for heavy bearings, and 
 engine cylinders. Petroleum is becoming utilised for prime movers (see 
 Petroleum Engine) and also for fuel. The first application of it to 
 this purpose was in Mr. Holden's iujeotor for the engiues on the Great 
 Eastern Railway. Mr. TJrquhart has used it during nine years past iu 
 Russian locomotives. A very considerable saving has been efllected by 
 its use. 
 
 Petroleum Engine. — An engine iu which the vapour of petroleum oil is 
 utilised as the motive power. There are three types of this engine — one, 
 in which a jet of oil is mixed, and sprayed with a current of air, and 
 the two being received with a further supply of air in a vaporizing 
 chamber, heated by a jacket through which the exhaust gases pass, 
 are compressed, ignited by an electric spark, and expanded, doing work 
 in the cylinder, and exhausted. Priestman's engine is of this class. In 
 the second type the oil is injected into a volume of air heated and com- 
 pressed in a vessel which opens into the cylinder. The Akroyd engine 
 is of this class. In the third class the oil passes through a heated 
 
APPENDIX. 433 
 
 chamber, acting as a gas generator, on its way to the cylinder. The 
 Homsby engine belongs to this class. Petroleum engines, though not 
 yet extensively employed, are certain to win favour because they have 
 proved to be economical in working. Thus, Professor TJnwin, as the 
 result of tests on a five horse-power Priestman's engine, drew the 
 estimate that the consumption of oil was equal to that of from 1'02 to 
 1'23 lbs. of coal per brake horse-power per hour, while the lowest 
 recorded consumption of steam in a triple expansion engine corresponded 
 with 1-61 lbs. of coal per brake horse-power per hour. There is a large 
 field for the employment of oil-engines, because, in addition to their 
 economy, they have this advantage, that the oil supply being indepen- 
 dent of the engine, no fixed pipe connections are necessary as in the case 
 of gas and of steam engines. Oil-engines have been used for pumping, for 
 driving dynamos, for working rock-driUs, for working air-compressors, 
 for fog-signaUing at lighthouses, and for driving launches and barges. 
 As the engines do not reverse, a reversing friction clutch is used for 
 driving laxmches astern. 
 
 Pig-Boiling (see Diet.). — There is less waste of iron in pig-boiling than 
 in dry-puddling ; iron of less purity can be used, and grey iron can be 
 employed without the expense of preliminary refining into white. The 
 oxidising agents in the pig-boiling process are mainly substances rich 
 in oxide of iron, as tap cinder, hammer scale, old broken-up furnace 
 bottoms, together with a fettling of puddlers* mine, and bull dog, or of 
 blue billy. The evolution of carbonic oxide at the surface of the molten 
 slag gives rise to the appearance of boiling — hence the term. At the 
 same time the oxidation of the sulphur, phosphorus, silioon, and man- 
 ganese goes on, the action of the molten slags being assisted by that of 
 the atmosphere, while the semi-pasty metal is being rabbled. When 
 the ebullition ceases the rabbling is still continued for a little while, 
 previous to the balling up. Pig-boiling has largely superseded the 
 older method of dry-puddling. The expenditure of fuel in the puddling 
 process is great. Pig-boiling is more economical on the whole than 
 the method of refining, and dry-puddling, though in the single opera- 
 tion of dry-puddling there is less loss than in the pig -boiling. The loss 
 of metal is greater in grey than in white iron. The loss varies from 
 7 to 10 per cent., in Staffordshire, to 15 or 18 per cent, in Blackband 
 ores. The charges of metal weigh a few cwts. only ; from 3 to 5, and 
 from 20 to 25 cwts. of fuel per ton of iron are used, the practice and 
 proportions varying in different localities, and for different quahties of 
 metal. 
 
 Piping. — The drawing down or hollowing out in a conical depression of 
 an ingot of cast-steel, due to the shrinkage of the metal. In cast-iron 
 it would be termed a "draw " (see Feeding, in Diet.). 
 
 Plastic. — Materials are said to be plastic when they have no tendency to 
 return to their original shape after the action of external forces operating 
 upon them is withdrawn. Clay, putty, &o. are plastic substances. 
 The term is employed specifically, to distinguish such substances from 
 those which are termed elastic. 
 
 Plast'O Metal. — Eichards's plastic metal is a white alloy, having a low co- 
 enicient of friction, and anti-corrosive properties which render it adapted 
 for high-speed bearings, and for use imder water. It can be employed 
 for fan bearings, locomotive axle-boxes, glands, and for coating pro- 
 peller-blades. It contracts very little in cooling, and fuses at a low 
 temperature. It is used as follows : — Melt the ingots in an iron pot, or 
 
434 APPENDIX. 
 
 ladle, over a slow fire ; then run the metal into thin strips like tinmen's 
 solder. The bearing, or other article, having been thoroughly cleansed 
 from oil and grease, should be heated hot enough (about 450° Fahr.) to 
 melt the plastic metal ; then, after having first sprinkled a little ground 
 Bal-ammoniao upon the part to be refaced, take a strip of the plastic 
 metal ajid rub it on until a thin coating is formed ; the metal may then 
 be pasted on, layer upon layer, with a plumber's soldering-iron, until 
 the required thickness is obtained, or it may be run on out of a ladle, 
 having first made a core of dry sand, or iron plate, to the required 
 radius of the bearing. When " pasting-up" upon plastic metal, first 
 apply a httle spirits of salts to the surface of the old plastic metal. 
 
 Plumb' Eule. — A rule or straijjhtedge used to test the perpendicular 
 accuracy of a supposed vertical surface. It carries a plumb hne against 
 the centre of its longitudiual axis, and has a recess, cut near its lower 
 end, for the plumb bob. 
 
 Point Chuck. — The dead centre, or point centre, attached to the head- 
 stock of a lathe, for turning work which is pivoted between centres. It 
 is either fitted with a coned end into the hollow of the mandrel nose, or 
 it is screwed over the nose, like the face, and cup chucks. In the latter 
 case it is also usually slotted through for the driver (q.v. in Diet.). 
 The latter method is adopted on small lathes, the former on those of 
 best construction. Also called driver chuck, and running centre chuck. 
 
 Pop. — A term used in North Britain to denote a small boss which receives 
 a set screw. 
 
 Portable Drill. — A type of small hand drilling machine, used chiefly for 
 drilling holes in boOer shells, and fire boxes in situ. The machine is 
 held in the hands, and operated with an endless cord, from a pulley 
 overhead, the cord passing over guide pulleys, the distances of which 
 are adjustable. 
 
 Potash Hardening. — A shop term, which distinguishes mere surface har- 
 dening, effected by the contact of potash at a red heat with wrought 
 iron, from that effected in a case-hardening pot, in prolonged contact 
 with animal charcoal. The former is a mere film that can be penetrated 
 with a file ; the latter is of sensible depth, or from -^2" iH' to -j^ in. deep. 
 
 Pot Steel. — Cast steel (q.v. in Diet.), to distingnish it from steel made by 
 Bessemer and Siemens processes. 
 
 Pottering Down. — ^Poking or stoMng the fuel around the crucibles used 
 for steel melting. 
 
 Pouring Basin. — The depression, or hollow receptacle above the ingate 
 of a mould, which receives the metal from the ladle. The basin is 
 deep, of sufficient area, and aH sharp comers of sand are scrupulously 
 avoided. 
 
 Power Transmitter. — Shaw's transmitter is a successful device by means 
 of which power is transmitted from a motor to shafting, or to pulleys. 
 It depends for its action upon the friction of a coil spring enclosed in a 
 cylindrical box sliding closely upon a cyhuder or boss which is keyed to 
 the shaft. There is some rather intricate gear for controlling the coU 
 spring, which cannot be described in detail without a diagram, and 
 which varies in different classes of transmitters ; but by its means the 
 gripping power of the coil is limited and adjustable, so that machinery 
 can be started without sudden shock ; and in the case of excessive and 
 unusual resistance being offered, a relative movement of the coil and 
 case takes place, by which the coil is released from its grip automatically. 
 The coU and its parts work in a bath of oil, and the wear is practically 
 
APPENDIX. 435 
 
 nil. The transmitter is largely used on gas engines. The exterior 
 appearance is simply that of a eylindrioal box, -with starting handle. 
 Prime Number. — Tlie ordinary change wheels used for scre-w cutting 
 have composite numbers of teeth. These, in various combinations, will 
 out screws having an almost infiidte range of composite pitches. But 
 to cut threads having prime numbers to the inch, change wheels having 
 prime numbers of teeth are requisite. Prime numbers can be out with 
 a division plate, or with a traversing mandrel. Any number that can- 
 not be divided without remainder by any other number is said to be 
 prime ; that is a prime number is one which has no divisor or factor 
 but itself, and unity. The prime numbers up to 97, which alone would 
 concern screw cutters, are 1, 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 
 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97. 
 
 E. 
 
 Eain-'Water Pipe. — A special branch of pipe founding, done chiefly in 
 Scotland, which is an interesting illustration of how the minimum 
 thickness of iron can be run over a large surface, by using metal of 
 softest quality, thoroughly hot, and employing several long narrow 
 runners. The thickness of the metal in these pipes ranges from \ in. 
 to ^ in. 
 
 Bamming. — The consolidation of the sand around a pattern by means of 
 a rammer. Sand may be rammed too hard, or too soft ; in the first 
 place causing scabs, in the second the formation of lumps on the 
 castings. Sand requires to be rammed harder in some sections of a 
 mould than in others, and dry sand may be rammed harder than green. 
 The harder the ramming the more complete should be the venting. 
 
 Begeuerator (see Diet.) . — Its function is the utilization of the heat of the 
 waste gases from the furnace hearth. These gases being led through the 
 brickwork, give up a large portion of their heat thereto, which is 
 afterwards taken up by a cool return current on its way to the hearth. 
 There are separate regenerators for the air, and the combustible gases. 
 (See Air Regenerator, Gas Regenerator, in Diet.) The regenerator of a 
 not-air engine is not like that used in a regenerator (q.v. in Diet.) 
 furnace. !Following Stirling's patent in 1827, it consists of thin sheets 
 of metal, or layers of wire gauze, through which the exhaust hot air 
 passes ; which heat is taken up again by lie cold air for the succeeding 
 sttoke. 
 
 Register. — To register is to fi.t one section to another, to cause parts to 
 coincide accurately. The term is appKed to the good fitting of pins and 
 holes, rebates, rings, &c. 
 
 Be-startiug Injector. — Is designed for use in locomotive and marine 
 engines, which, being subject to shock, sometimes render the ordinary 
 injector unreliable. In the injector patented by Messrs. Schaffer and 
 Budenberg, the steam nozzle is closed by a double seated valve of 
 conical form. Hence, when it is opened, an annular jet of steam issues 
 from the nozzle, and condensing a portion of the cold feed water, 
 creates a partial vacuum, which causes the steam to flow with higher 
 velocity, and carry the water into the boiler. 
 
 Bibbed Tubes. — The ribbed tubes, the invention of M. Serve, have been 
 introduced with a view to increase the heating surface of the fire tubes 
 of steam boilers, with a corresponding economical consumption of fuel, 
 »nd an increase in steam pressure. The tubes are simply rolled with 
 
436 APPENDIX. 
 
 several mtemal deep radial ribs running longitudinally. They are 
 made in iron, steel, copper, and brass. They have been, approved by the 
 Committee of Lloyd's Register, and by the Board of Trade authorities. 
 Messrs. John Brown & Co., of Sheffield, are the manufacturers. 
 Experiments have proved that 15 per cent, better results are obtained 
 by the adoption of the Serve ribbed tubes when natural draught is 
 employed, and of 20 per cent, when forced draught is used. The 
 Purves flue tubes are ribbed and corrugated transversely, and are also 
 manufactured by John Brown. 
 
 Bivet Tail. — That portion of a rivet which is turned over in the process 
 of riveting, or the opposite end to the rivet head, which is formed by 
 machinery. 
 
 Eubbing. — When it is desired to design a wheel or wheels to gear with 
 one already existing, it is customary to rub a sheet of clean white 
 paper on the ends of the teeth of the old wheel, in order to obtain their 
 correct curves, whence those of the new wheel are adapted thereto. 
 This is oaUed " taking a rubbing." 
 
 s. 
 
 SoroU Gear. — A form of the variable gears (q.v.) in which the pitch sur- 
 face is in the form of a scroll, the effect being to impart a gradually 
 increasing rate of motion to a shaft. 
 
 Seamless Copper Tubes. — The numerous accidents which have occurred in 
 consequence of the bursting of steam pipes of brazed copper have resulted 
 in the introduction of a suooessful economical process of making seam- 
 less tubes by electroKtio deposition, the invention of Mr. Elmore. The 
 tubes are made in a bath of copper sulphate from bars of common Chili 
 copper, which are simply placed in the bath and allowed to dissolve. 
 The copper is then deposited from its solution upon a slowly revolving 
 iron mandrel. The deposited crystals are broken down almost as soon 
 as formed by an agate burnisher kept moving backwards and forwards 
 along the revolving mandrel. A layer of copper, one-seven thou- 
 sandth part of an inch in thickness, is formed between each reciprocation 
 of the burnisher. The tubes are deposited at the rate of J in. in thick- 
 ness per week of 144 hours. So closely are the particles squeezed 
 together that the specific gravity is increased, xmtil a plate \ in. thick 
 weighs 6 lbs. to the square foot, instead of 5 '79 lbs. The metal has a 
 tensile strength of 25 tons per square inch, with an extension of 20 per 
 cent, in breaking. The copper is perfectly pure, and the pipes are 
 homogeneous and of equal thickness and strength, and without the uncer- 
 tain brazed joint. The pipes are made in all sizes, from 6 in. to 18 in. 
 diameter, and from a little more than -^ in. to |- in. in thickness. 
 
 Sector Gears. — A term appHed to a special form of toothed gearing, by 
 which motion of an intermittent character is transmitted from one shaft 
 to another. The pitch peripheries of the wheels, instead of being con- 
 tinuous, are broken up into arcs of circles of different curvations, each 
 pair of arcs therefore transmitting different velocity ratios. The gears 
 are, therefore, variable (see Variable G-ears), though the term mter- 
 mittent would more properly be applied to them, because there is no 
 merging of different speeds into each other, but a sudden and instant 
 change of speeds. 
 
 Separator. — A device to prevent priming in steam pipea. There are 
 
APPENDIX. 437 
 
 varioua types made use of, the aim being to throw down the partiolea 
 of water which are meohauicaUy mixed with the saturated steam, leading 
 the latter comparatively dry on its passage to the cylinder. 
 
 Shingled Bloom. — A term applied to the ball of crude malleable iron 
 which has been subjected to the process of shingUng, preparatory to 
 rolling into a slab or puddled bar. 
 
 Single Curve Teeth. — Involute teeth (q. v. in Diet.) , so called because their 
 flanks and faces above and below that which corresponds with the pitch 
 line in double curve gear, are formed with a. single continuous curve 
 only. (See Double Curve Teeth.) 
 
 Single Ported Slide Valve. — The common valve, the travel of which is the 
 same as the throw of the eccentric. The term is merely used to dis- 
 tinguish it from the double and treble ported valves (described in Diet.) . 
 
 Skew Bevels (see Diet.). — The pitch surfaces of these are, in principle, 
 frusta of hyperboloids of rerolution, though in practice, frusta of cones 
 are substituted for these. They are employed in the first case where 
 shafts cross each other without actually intersecting, in the second 
 where they neither cross nor intersect, but where one runs near the 
 other, and at right or at other angles therewith. In either case screw 
 wheels could be used, or in the second case a worm and wheel ; but the 
 advantage of the skew bevels is that the mutual action of these gears is 
 chiefly rolling, whereas that of screw wheels is entirely sliding. 
 
 Slag Pit. — A. depression made beneath the tap hole of a Siemens steel 
 melting furnace to receive the slag after the metal has been tapped out. 
 Also, the similar pit beneath a Bessemer converter. 
 
 Slider Crank Chains. — ^Kinematic links, which are connected by pairs of 
 mechanical elements in such a way that two of the links cannot turn, 
 but must slide simply. It may be supposed to be derived from a levir 
 erank chain (q.v.), two of the links of which are made of equal length 
 and infinitely long. An illustration occurs in the rectilinear motion of 
 an engine slide block, moving in guide bars, converted into the angular 
 and rotary motion of the connecting rod. 
 
 Slot Drill. — The instrument used in slot drilling (q.v. in Diet.). It is a 
 flat-ended double-cutting drill, having two radial cutting edges opposed 
 to each other, and no centre point. Being traversed as it operates, it is 
 termed a traversing drill. 
 
 Smoke Tubes, or Fire Tubes. — The tubes of multitubular boilers, through 
 which the flame and hot gases pass from the fire grate to the chimney. 
 
 Spherical Engine. — The Tower engine is too complicated for description 
 without illustration. It consists of a pair of quarter spheres, hinged to 
 a disc along diameters at right angles with each other, and enclosed in 
 a hollow sphere of the same diameter as the disc, with the curvature of 
 which also that of the quarter spheres corresponds. The hollow sphere 
 is steam tight, and forms the cylinder. The two spaces between the 
 sections and disc will in the course of a revolution open and close in 
 pairs, and this is the effect therefore of the action of steam admitted into 
 the hollow sphere. In principle the spherical engine is a Hooke's 
 universal joint, the sections corresponding with the bows and the disc 
 with the cross piece connecting the bows. It is serviceable for driving 
 dynamos. 
 
 Split Key. — A key (q.v.) which is split at one end similarly to a spHt pin, 
 to lessen the tendency to work out of its bed. 
 
 Spring Bas9. — The distance from centre to centre of the spring cradlea or 
 hangers upon which the ends of an arched spring are pivoted. 
 
438 APPENDIX. 
 
 Springf Buckle. — The forging wHoh embraces a sheaf or lumdle of arched 
 springs, at the centre. 
 
 Spring Compass. — The amount of curvature of an arched spring. 
 
 Spring Cradle, or Spring Hanger. — The forging -which sustains the ends 
 of arched springs, either with pins or with hooks. 
 
 Standards. — The standards of the British yard measure, and pound weight 
 are deposited tmdemeath the window on the second landing of the 
 staircase leading to the committee rooms of the House of Commons. 
 The standard yard consists of a sohd bar of brass thirty- eight inches 
 long, and one inch square, and the lines representing the length of 
 thirty-sir inches are cut upon gold plugs inserted and sunk in the bar. 
 This is kept in a mahogany box sealed up in an oak case. The standard 
 pound, of seven thousand grains, is a mass of platinum, in the form of 
 a cylinder, nearly 1-35 in. high, and 1'15 in. in diameter. The first 
 standard yard was made by Bird in 1760, but was not actually legalised 
 until June 17th, 1824 ; when an Act was passed to the effect that ' ' the 
 straight line or distance between the centres of the two points in the 
 gold studs in the straight brass rod, now in the custody of the Clerk of 
 file House of Commons . . . the brass being at the temperature of 
 62 degrees of Fahrenheit's thermometer, shall be, and is, hereby 
 denominated the 'imperial standard yard.'" Section 3 of the Act 
 contained directions for making a new standard yard in the event of the 
 original becoming lost, or destroyed, or defaced, by reference to the 
 length of a pendulum beating seconds. The bar was actually destroyed 
 by fire ten years afterwards, and then on attempting to restore the lost 
 standard by reference to the pendulum in the manner defined by the 
 Act, so many errors in the conditions necessary became apparent, that 
 this method was abandoned and the lost bar was ultimately restored by 
 comparison with five yard bars still in existence. The work was com- 
 menced by Sir IVanois Bayley, who died before it was completed, and 
 was then finished by the Rev. E. Sheepshanks, whose standards are 
 those stUl existing. There were four Parliamentary copies constructed, 
 and forty copies for distribution among foreign governments. They 
 are made of "Bailey's metal," consisting of 16 parts copper, 1\ parts 
 tin, and 1 part zinc. 
 
 Star Gears. — See Variable Gears. 
 
 Stamps. — Pieces of refined iron of about 28 lbs. in weight each, obtained 
 by nicking and breaking up the blooms shingled under the steam 
 hammer in the refining process, for the manufacture of coke plates. 
 
 Standard Corrective Gauge, or Corrective Gauge simply. — A cylindrical 
 step gauge made of steel, which is turned in a succession of short 
 parallel lengths or steps, to six or eight different standard diameters, 
 and furnished with a handle lilre an ordinary parallel cylindrical male 
 gauge. Sizes advance either by sixteenths or eighths of an inch, the 
 smaller gauges beginning at -^ or J in., and the larger ones range as 
 high as 3 in. or 4 in. in diameter. These gauges are not made for 
 the testing of work ia progress, but for the periodical testing of the 
 shop gauges, by which work is bored and turned. 
 
 Steam Blower. — A pipe and cock on a locomotive, employed to create a 
 draught before the engine starts. The pipe leads into the chimney, and 
 ■when steam is turned into it, the action is similar to that of the blast 
 pipe in intensifying combustion when the engine is running, except that 
 the blast is continuous instead of intermittent, as in the case of the 
 Uastpipe. 
 
APPENDIX. 439 
 
 Steam Loop. — Btimliain's steam loop ia a device for economising fuel, by 
 the return of condensed water to a steam boiler without the use of 
 pump or injector, and in which it is not necessary that the water should 
 be made to flow by gravity. A hent pipe is carried from the condenser or 
 separator, as the case may be, and consists of two vertical portions and 
 a horizontal portion. The vertical portion from the condenser or sepa- 
 rator is called the "riser," the level length the " horizontal," and the 
 vertical portion to the boUer the "drop leg." These constitute the 
 "loop." The arrangement is such that a current of steam from the 
 boiler causes condensation in the loop, and the water from the condenser 
 or the separator flows in to occupy the partial vacuum thus formed, 
 and gradually a constant flow of feed water is thus obtained. 
 
 Steam Packing. — Packing which is used in the stuffing boxes of engine 
 cylinders, steam chests, &c., to render them steam-tight without inter- 
 fering with the free movement of the rods. The term is used in oppo- 
 sition to water packing (q. v. in Diet.) . The materials used are flax, or 
 hemp, well saturated with grease, asbestos, or divided metallic rings. 
 The packing is placed in the stuffing box (q.v. in Diet.) and tightened 
 around the rod by the screwing down of a gland (q.v. in Diet.). 
 
 Steel Pipes. — Water pipes made of thin sheet steel. These are coming 
 into increasing favour both at home and abroad. They have been made 
 as large as eight feet in diameter. They have the very great advantage 
 over cast-iron pipes, of lightness, a matter of the first consideration in 
 new countries, where they have to be carried over many miles of uneven 
 country by ox wagons. The sheets are made so thin as a tenth of an 
 inch. 
 
 Swabbing. — Moistening the edges of a foundry mould with the water 
 brush (q.v. in Diet.) in order to effect the due consolidation of the sand. 
 Swabbing must be only moderate in amount. Excessive swabbing 
 tends to produce scabs and blowholes. 
 
 T. 
 
 Test Bars (see Diet.). — The highest result yet obtained was that of Mr. 
 Thomas Turner, of 42-1 cwts. The standard test bar is 1 ft. in. by 
 1 in. by 1 in., which should breai at about a ton. It is convenient to 
 know that pounds weight on the standard bar divided by 84, gives 
 cwts. on the 3 ft. in. by 2 in. by 1 in. bar, and that cwts. on the 3 ft. 
 bar, multiplied by 84, give pouncU on the standard bar. 
 
 Test Pressure. — The pressure put upon a steam boiler before delivery to 
 purchaser. (See Boiler Testing in Diet.). 
 
 Thoroughfare Taps. — Taps whose square heads are sufficiently small to 
 allow them to pass through the hole which has been tapped with them 
 and so save the time which would otherwise be lost in running them 
 back. Whitworth taps, and most modem taps are of this type. 
 
 Throat Plate. — The plate ia the outer firebox of a locomotive boiler, to 
 which the lower portion of the barrel is riveted. It is flanged forwards 
 at the top to receive the barrel, and backwards at the sides to receive 
 the arched sheet of the outer firebox. 
 
 Tool Points. — The cutters which are clasped in a tool holder (q.v. in 
 Diet.) to distinguish them from solid tools (see Solid Tool in Diet.). 
 
 Total Heat of Steam, or Total Heat of Evaporation. — Comprises the latent 
 heat, in addition to the sensible heat. It increases uniformly with 
 temperature under constant pressure. At higher temperatures than 
 
44P APPENDIX. 
 
 212° Fair, tlie sensible heat increases, and the latent heat decreases, hut 
 the total heat of steam slowly increases. 
 
 Trial Bar, or Proof Bar. — A bar of blister steel, -withdrawii from time to 
 time through the tap hole of the trough or pot, in order that by inspec- 
 tion of its general appearance and fracture, a correct opinion may be 
 formed of the progress of the cementation process. 
 
 Trip Engines. — Engines of the Corliss type, and of some pumping-engine 
 types, the valves of which are opened by means of short levers instead 
 of by eccentrics, as in ordinary engines. 
 
 Turning Cylinders, or Slewing Cylinders.^ — The shorter cylinders of a 
 hydraulic crane, whose rams cause the crane to slew or turn on its 
 centre, as distinguished from the lifting cylinders (q.v.). 
 
 Tuyere Box. — The air chamber underneath a Bessemer converter (q.v. in 
 Diet.) from which the air necessary for the decarburization of the metal 
 passes to the tuyere openings. Sometimes an air belt (q.v. in Diet.) is 
 termed a tuyere box. 
 
 Two Throw Pump. — A double-barrelled suction pump, operated by two 
 cranks. It is therefore not in equilibrium, as is the case with a three 
 throw pump. 
 
 u. 
 
 Undertype Engine. — That form of semi-portable engine, in which the 
 engine is frKcd on the foundation, beneath the boiler itself. 
 
 Unit of Section. — Any convenient unit, or constant dimension, employed 
 in estimating the area of a section. It is usually the square iuch, 
 sometimes the circular inch ; or in the decimal system, the square 
 centimetre. 
 
 Valve Eod, or Valve Spindle.— The rod to which a slide valve is attached, 
 through which it is actuated from the eccentric or eccentrics. The rod 
 passes through a stuffing box in the steam chest. 
 
 Variable Gears. — Toothed wheels of various outlines, which transmit 
 varying velocity ratios during the course of a single revolution. The 
 outlines of their pitch peripheries may be rectangular, triangular, 
 elKptical, rudely star shaped, &o. ; each depending upon the number of 
 alterations in speed required in a single revolution. In square gears, 
 the pitch peripheries are rectangular, with rounded comers ; and there 
 are eight changes in speed, four maximum and equal, four minimum 
 and equal. The star gears are modifications of the square gears, the 
 diagonals being longer, and the sides correspondingly deepened, so that 
 the changes in speed are correspondingly greater. In triangular gears 
 the pitch peripheries are of the outlines of equilateral triangles, with 
 rounding corners. There are then six variations in speed, three maxi- 
 mum and equal, three minimum and equal. These also may be developed 
 into triangular star gears. (See also Elliptical G-ears, SoroU Gears, 
 Sector Gears.) 
 
 Vents. — The channels, area spaces, &c., by which the air and gas are 
 carried away from a mould. They may be cylindrical channels, pierced 
 with vent wires, or with rods, if straight ; or with ropes, if curved ; or 
 they may be bodies of ashes, between the interspaces of which the air 
 collects as in a reservoir, to be led away quietly by the TeBt channels. 
 
APPENDIX. 44 J 
 
 In any case care must be taken that metal does not get into the venta 
 and choke them. 
 Vents, Choking of. — This means that melted metal gains access to the air 
 channels in a mould, and by closing them up, prevents the escape of 
 air. This is prevented in many ways. In a surface of large area the 
 metal is prevented from entering, by interposing a thin stratiim of sand, 
 say of f -in. or J-in. in thickness between the face of the mould and 
 the vent openings ; and the air is forced through this stratum by the 
 pressure in the mould. Where cores abut against each other, metal is 
 prevented from getting between by a luting of loam, or clay water, or 
 dry sand. This is called securing the vents. 
 
 w. 
 
 Walking-Crane. — A single rail crane (q.v. in Diet.). 
 
 Washing Down. — ^A term used in North Britain to denote the thinning, 
 or tapering down of anything, to a feather edge. 
 
 Waste Gases.. — The gaseous products of combustion, chiefly carbonic 
 oxide, carbon dioxide, and marsh gas, mixed with inert nitrogen. 
 Metallurgists now aim at utilizing the combustible gases as much as 
 possible. Hence the use of close topped blast furnaces, and of regenera- 
 tive furnaces, by which the greater portion of the heat is utihzed, 
 instead of being dissipated into the atmosphere. 
 
 Weak Sand. — The term is used in opposition to strong sand (q.v. in Diet.), 
 because it contains no horse dung or core sand. 
 
 Weld Iron. — Wrought iron, to distinguish it from ingot iron (q.v.). 
 
 Wing Bar. — A fire bar which is the outermost of the series in a Cornish 
 or Lancashire boiler. In small boilers the curvature of the fire fine is 
 so great that the bars of ordinary depth cannot be brought sufficiently 
 close to the sides to fill up the space. Hence in these cases shallower 
 bars, one on each flank, are employed to fill up the space. These are 
 the wing bars. 
 
 Witness, or Witness Line. — When in machining work some faint traces 
 of the lines marked thereon, or some of the original rough surface of 
 the casting or forging is left intact and visible, this is said, in shop par- 
 lance, to be left as "witness," signifying that the workman has not 
 carelessly reduced below given dimensions, the testimony of the witness 
 being indisputable. Also, in Uned-out work it is usual to strike a line 
 concentric with and outside or inside the working line, according to the 
 character of the work, and to centre pop it. This line, remaining after 
 the machining is done, testifies to the concentric accuracy or otherwise 
 of the machined work. 
 
 Woodite. — A preparation of caoutchouc, named after its inventress, Mrs. 
 A. M. Wood. It is elastic and flexible, but, unlike the natural rubber, 
 it does not become sticky, and it resists the action of oils and heat. It 
 is made in various degrees of elasticity and of hardness, and is recom- 
 mended as a substitute for rubber, leather, and asbestos. It is spongy 
 and buoyant, closes up behind a shot, is unaffected by steam, aoida, 
 ammoniacal liquor, bilge water. It is, therefore, of service for washers, 
 rings of pump valves, packing, and other purposes. 
 
 Working Pressure. — The pressure at which a boiler is safely worked, as 
 distinguished from the test pressure (q.v.). 
 
 Wrought-iron Pipe. — Common welded gas tubing is used for engineers' 
 steam and water connections, for moderate pressures only. For pros- 
 
442 APPENDIX, 
 
 sores up to 60 or 70 lbs. per inch, and in diameters up to 1\ in. or 3 in. 
 
 it is a cheap and safe material. For higher pressures and large dia- 
 meters solid drawn tube, or copper tube is employed. Wrought-iron 
 pipe can be easily bent at a red heat, its connections easily made with 
 tees, elbows, crosses, and screwed unions and sockets ; and faulty tubes 
 seldom occur. 
 
 Yard Oil lights.— Taking the WeUs as one of the best known, the prin- 
 ciple is the vaporization of oO, and its combustion, and the production of 
 a long jet of flame under pressure. In the Wells light the reservoir is 
 pumped three-quarters full of oil. Then air is pumped in until a pres- 
 sure gauge shows 20 lbs. to the inch. This pressure drives the oil up 
 steadily to the burner above, which is first heated, and the oil circulat- 
 ing through an arrangement of heated tubes, finally issues, still under 
 pressure, from the horizontal nozzle of the burner, and being vapor- 
 ized, bums with a fine white light, making a rushing noise. The 
 lamp is first heated with paraffin or oil, and burning waste is placed in 
 a dish beneath the jet. When the pressure of the air diminishes to 
 about 7 lbs., the lamp must be again charged up to 20 lbs. Special oil, 
 made from coal tar, is sold for burning in these lamps. But petroleum 
 or kerosene will also answer. 
 
 Yield Point, or Breaking Down Point. — That point in the stressing of 
 a material in which the deformation increases very suddenly. It occurs 
 immediately beyond the elastic limit, and is marked by a well-defined 
 and sudden curve in the stress-strain diagram. 
 
 z. 
 
 Z is the symbol conmionly used by engineers to signify the modulus of a 
 section. 
 
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 0/ modern engineering work. 
 
 *#* Opinions of the Press, 
 
 " A thoroughly good practical handbook, which no engineer can go through without learning 
 something that wifl be of service to him." — Marine Engineer. 
 
 " An excellent book of reference for engineers, and a valuable text -book for Students of 
 ■engineering." — Scotsman. 
 
 " This valuable manual embodies the results and experience of the leading authorities on 
 mechanical engineering." — Building- News. 
 
 " The author has collected together a surprising quantity Oi rules and practical data, and has 
 rfwjwn much judgTnent in the selections he has made. . . . There is no doubt that this book is 
 one of the most useful of its kind published, and will be a very popular compendium." — Engineer. 
 
 " A mass of information, set do^vn in simple language, and in such a form that it can be easily 
 referred to at any time. The matter is uniformly good and well chosen, and is greatly elucidated 
 by the illustrations. The book will find its way on to most engineers' shelves, where it will rank as 
 cme of the most useful books of reference." — Practical Engineer. 
 
 " Should b^ found on the office shelf of all practical engineers."— £'«^^ij-A Mechanic, 
 
2 CnOSBY LOCKWOOD <&* SON'S CATALOGUE, 
 
 JELandhooTc for Works' Managers* 
 
 THE WORKS' MANAGER'S HANDBOOK OF MODERN 
 
 RULES, TABLES, AND DATA. For Engineers, Millwrights, and Boiler 
 
 Makers; Tool Makers, Machinists, and Metal Workers; Iron and Brass 
 
 Founders, &c. By W, S. Huttqn, C.E., Author of " The Practical Engineer's 
 
 Handbook." Fourth Edition, carefully Revised, and partly Re-written. In- 
 
 One handsome Volume, medium 8vo, 15s. strongly bound. [Just published. 
 
 IS" The Author having compiled Rules and Data for his own use in a great 
 
 variety of modern engineering work, and having found his notes extremely useful, 
 
 decided to publish them — revised to date — believing that a practical work, suited tc 
 
 Me DAILY REQUIREMENTS OF MODERN ENGINEERS, would be favourably received. 
 
 In the Third Edition, the following among other additions have been made, viz.: 
 Rules for the Proportions of Riveted Joints in Soft Steel Plates, the Results of Experi- 
 ments by Professor Kennedy /or the Institution of Mechanical Engineers — Rules 
 for the Proportions of Turbines— Rules for the Strength of Hollow Shafts of Whii^ 
 worth's Compressed Steely &c, 
 
 %* Opinions of the Press. 
 
 "The author treats every subject from the point of view of one who has collected workshoy? 
 notes for application in workshop practice, rather than from the theoretical or literary aspect. The 
 volume contains a great deal of that kind of infonnatton which is gained only by practical experi- 
 ence, and is seldom written in books." — Engineer. 
 
 "The volume is an exceedingly useful one, brimful with engineers' notes, memoranda, and 
 rules, and well worthy of being: on every mechanical engineer's bookshelf." — Mechanical IVorid. 
 
 " The information is precisely that likely to be required in practice. . . ■ The work forms a 
 desirable addition to the hbrary not only of the works manager, but of anyone connected withi 
 general engineering." — Mining- journal. 
 
 "A formidable mass of facts and figures, readily accessible through an elaborate index 
 .... Such a volume will be found absolutely necessary as a book of reference in all sorts 
 of 'works' connected with the metal trades." — Ryland's Iron Trades Circular, 
 
 " Brimful of useful information, stated in a concise form, Mr. Hutton's books have met a press- 
 ing want among engineers. The book must prove extremely useful to every practical raaa. 
 possessing a copy."—Praeiical£fi£iueer, 
 
 Practical Treatise on Modern Sfeam-Boilers. 
 
 STEAM-BOILER CONSTRUCTION, A Practical Handbook 
 for Engineers, Boiler-Makers, and Steam Users. Containing a large Col- 
 lection of Rules and Data relating to the Design, Construction, and Working 
 of Modern Stationary, Locomotive, and Marine Steam-Boilers. ByWALTERi 
 S. HuTTON, C.E., Author of "The Works' Manager's Handbook," &c.- 
 With upwards of 300 Illustrations. Medium 8vo, i8s. cloth. [Just published. 
 "Evcy detail, bcth in boiler design and manaErement, is clearly ]aid before the reader. The? 
 
 volume shows that boiler construction has been reduced to the condition of one of the most exact 
 
 sciences ; and such a book is of the utmost value to the JT71 de siicle Engineer and Works'" 
 
 Ma^ag■er " — Marine Engineer. 
 
 " There has long been room for a modern handbook on steam boilers ; there is not that rooms 
 
 now, because Mr, Hutton has filled it. It is a thoroughly practical book for those who are occui- 
 
 pied in the construction, design, se'ection, or use of boilers." — £ngi?icer, 
 
 *^The Modernised Templeton,'' 
 
 THE PR A CTICA L MECHA NIC 'S WORKSHOP COM- 
 PANION. Comprising a ^eat variety of the most useful Rules and Formulae 
 in Mechanical Science, with numerous Tables of Practical Data and Calcu- 
 lated Results for Facilitating Mechanical Operations. By William Temple- 
 TON, Author of "The Engineer's Practical Assistant, &c. &c. Sixteenth 
 Edition, Revised, Modernised, and considerably Enlarged by Walter S. 
 Hutton, C.E,, Author of "The Works' Manager's Handbook," "The 
 Practical Engineer's Handbook," &c. Fcap. 8vo, nearly 500 pp., with Eight 
 Plates and upwards of 250 Illustrative Diagrams, 6s,, strongly bound for 
 workshop or pocket wear and tear. {_Just published, 
 
 *^(.* Opinions of the Press. 
 
 "In Its modernised form Hutton's ' Templeton ' should have a wide Sale, for It contains rouch 
 valuable information which the mechanic will often find of use, and not a few tables and notes which 
 he might look for in vain in other works. This modernised edition wi be appreciated by all who 
 have learned to value the original editions of ' Templeton.' ' —Eno-lish Mechanic. 
 
 ' ■ li has met with great success in the engineermg workshop, as we can testify ; and there ate 
 a great many men who, in a great measure, owe their rise in life to this little book." — Building NtTus. 
 
 " This familiar text-book — well known to all mechanics and engineers— is of essential service to 
 the every-day requirements of engineers, millwrights, and the various trades connected with 
 engineermg and building. The new modernised edition is worth its weight in eo\^."— Building 
 ^fws. {Second Notice,) * 
 
 "This well-known and largely used book contains information, broi ght up to date, of the 
 sort so useful to the foreman and draug'itsman. So much fresh information has been introduced 
 as to constitute it practically a lew book. It will be largely used in the office and workshop. '— 
 Mechanical U'orld. 
 
MECHANICAL ENGINEERING, etc. 
 
 Stone-worhing Machinery. 
 
 STONE-WORKING MACHINERY, and the Rapid and Economi- 
 cal Conversion of Stone. With Hints on the Arrangement and Management 
 of Stone Works. By M. Powis Bale, M.I.M.E. With Illusts. Crown 8vo, gs. 
 " Should be in the hands of every mason or student of stone-work." — Colliery Guardian. 
 "A capital handbook tor all who manipulate stone for building^ or ornamental purposes." — 
 Machinery MarJiet. 
 
 Fiitnp Construction and Management, 
 
 PUMPS AND PUMPING : A Handbook for Pump Users. Being 
 Notes on Selection, Construction and Management, By M. Powis Bale, 
 M.I.M.E., Author of " Woodworking Machinery,'' &c. Crown 8vo, 2s. 6d. 
 ' ' The matter is set forth as concisely as possible. In fact, condensation rather than diffuseness 
 
 has been the author's aim throughout; yet he does not seem to have omitted anything likely to be 
 
 of use." — yourtial of Gas Lighting. 
 
 Milling Machinery, etc, 
 
 MILLING MACHINES AND PROCESSES: A Practical 
 Treatise on Shaping Metals by Rotary Cutters, including Information on 
 Making and Grinding the Cutters. By Paul N. Hasluck, Author of " Lathe- 
 work." With upwards of 300 Engravings. Large crown 8vo, 12s. 6d. cloth. 
 
 Turning. ^"'* published. 
 
 LATHE-WORK : A Practical Treatise on the Tools, Appliances, 
 and Processes employed in the Art of Turning. By Paul N. Hasluck, 
 Fourth Edition, Revised and Enlarged. Or. 8vo, 5s. cloth. 
 "Written by a man who knows, not only how work ought to be done, but who also knows how 
 
 to do it, and how to convey his knowledge to others. To all turners this book would be vcLluable."' 
 
 —£?igineertng. 
 
 "We can safely recommend the work to young engineers. To the amateur it will simply be 
 
 invaluable. To the student it will convey a great deal of useful information."— £«£-sHecr. 
 
 Screw-Cutting. 
 
 SCREW THREADS: And Methods of Producing Them. With 
 Numerous Tables, and complete directions for using Screw-Cutting Lathes. 
 By Paul N. Hasluck, Author of " Lathe- Work," &c. With Fifty Illustra- 
 tions. Third Edition, Enlarged. Waistcoat-pocket size, is. 6d. cloth, 
 
 " Full of useful information, hints and practical criticism. Taps, dies and screwing-tools gene- 
 rallyare illustrated and their action desciiaed."— Mechanical World. 
 
 " It is a complete compendium of all the details of the screw- cutting lathe; in fact a mieltuni- 
 in-par^o on all the subjects it treats upon." — Carpenter aiidBuilder. 
 
 SmitWs Tables for Mechanics^ etc, 
 
 TABLES, MEMORANDA, AND CALCULATED RESULTS, 
 FOR MECHANICS, ENGINEERS, ARCHITECTS, BUILDERS, etc. 
 Selected and Arranged by Francis Smith. Fifth Edition, thoroughly Revised 
 and Enlarged, with a New Section of Electrical Tables, Formula, and 
 Memoranda. Waistcoat-pocket size, is. 6d. limp leather. [Just published^ 
 " It would, perhaps, be as difficult to make a small pocket-book selection of notes and formulae: 
 t J suit ALL engineers as it would be to make a universal medicine; but Mr. Smith's waistcoat- 
 pocket collection may be looked upon as a successful attempt." — Engineer. 
 
 "The best example we have ever seen of 250 pages of useful matter packed into the dimen- 
 sions of a card-case." — Building News. "A ventable pocket treasury of knowledge."— /rc». 
 
 Engineer's and Machinist's Assistant, 
 
 THE ENGINEER'S, MILLWRIGHT'S, and MACHINIST'S 
 PRACTICAL ASSISTANT. A collection of Useful Tables, Rules and Data, 
 By William Thmpleton, 7th Edition, with Additions. i8mo, 2s. 6d. cloth, 
 
 " Occupies a foremost place among books of this kind. A more suitable present to an appren- 
 tice to any of the mechanical trades could not possibly be made." — Building News. 
 
 "A deservedly popular .work, it should be in the 'drawer' of every mechanic."— £»^/i^A 
 Mechanic. 
 
 Iron and Steel, 
 
 " IRON AND STEEL " : A Work for the Forge, Foundry, Factory, 
 and Office. Containing ready, useful, and trustworthy Information for Iron- 
 masters; Managers of Bar, Rail, Plate, and Sheet Rolling Mills; Iron and 
 Metal Founders; Iron Shi and Bridge Builders ; Mecnanical, Mining, and 
 Consulting Engineers; Cj.Jractors, Builders, &c. By Charles Hoare. 
 Eighth Edition, Revised and considerably Enlarged. 32ir.o, 65. leather, 
 
 " One of the best of the pocket 'boosts."— English Mechanic. 
 
 " We cordicdly recommend this book to those engaged in considering the details of all kinds of 
 Iron and sted viqtVis,"— Naval Science, 
 
4 CROSBY LOCKWOOD &- SON'S CATALOGUE. 
 
 Engineering Construction, 
 
 PATTERN-MAKING : A Practical Treatise, embracing iheUB-ln 
 Types of Eneineering Coustruction, and including Gearing, both Hand and 
 Machine made, Engine Work, Sheaves and Pulleys, Pipes and Columns, 
 Screws, Machine Parts, Pumps and Cocks, the Moulding of Patterns in 
 Loam and Greensand, &c., together with the methods of Estimating the 
 weight of Castings; to which is added an Appendix of Tables for Workshop 
 Reference. By a Foreman Pattern Maker. With upwards of Three 
 Hundred and Seventy Illustrations. Crown 8vo, 7s. 6rf. cloth, 
 
 " A well-written technical ^uide, evidently -written bv a man who understands and has prac- 
 tised what he has written abo'iit. . . . We c rdially recommend it to engineering students, your.g 
 j jumeyinen, and others desirous of being initiated into the mysteries of pattern-making."— if MiVrfc**. 
 
 " We can confidently recommend this comprehensive treaiiae.' — Building News. 
 
 " Likely to prove a welcome §:uide to many workmen, especially to draughtsmen who have 
 lacked a training in the shops, pupils pursuing their.practical studies in our factories, and to em- 
 ployers and managers in engineering works. — Hardivare Trade yonmal, 
 
 " More than 3^0 illustrations help to explain the text, which is, however, always clear and ex- 
 plicit, thus rendermg the work an excellent vade 9?iecum for the apprentice who desires to become 
 master of his trade." — English Mechanic. 
 
 I>ictionary of Mecha^iical Engineering Terms, 
 
 LOCKWOOD'S DICTIONARY OF TERMS USED IN THE 
 PR A CTICE OF MECHA NIC A L ENGINEERING, embracing those current 
 in the Drawing Office, Pattern Shop, Foundry, Fitting, Turning, Smith's and 
 Boiler Shops, &c. &c. Comprising upwards of 6,000 Definitions. Edited by 
 A Foreman Pattern-Maker, Author of " Pattern Making." Crown 8vo, 
 7s. 6d. cloth. 
 "Just the sort of -handy dictionary required by the various trades engaged in mechanical en- 
 
 glneermg. The practical engineering pupil will find the book of great value in his studies, and 
 
 every foreman engineer and mechanic should have a copy." — Building Ne'ws, 
 
 "After a careful examination of the book, and trying all manner of words, we think that the 
 
 engineer will here find all he is Ukely to require. It will be largely used." — Practical Engineer. 
 "One of the most useful books which can be presented to a mechanic or student." — English 
 
 Mechanic. 
 
 " Not merely a dictionary, but, to a certain extent, also a most valuable guide. It strikes us as 
 
 a happy idea to combine with a definition of the phrase useful information on the subject of which 
 
 it treats," — Machinery Market. 
 
 " Kc word having connection with any branch of constructive engineering seems to be 
 
 omitted. No more comprehensive work has been, so far, issued. —>fCno7uledge. 
 
 "We strongly commend this useful and reliable adviser to our friends in the workshop, and to 
 
 students everywhere." — Colliery Gitardian. 
 
 Stecf/tyt HoiTer^ 
 
 A TREATISE* ON STEAM BOILERS: Their Strength, Con- 
 struction, and Economical Working. By Robert Wilson, C.E. Fifth Edition, 
 lamo, 6s. cloth. 
 
 "The best treatise that has ever been published on steam boilers." — Engineer. 
 "The author shows himself perfect master of his subject, and we heartily recommend all era- 
 ploying steam power to possess themselves of the work." — Ryland's Iron Trade Circular, 
 
 Boiler Chi^nneys, 
 
 BOILER AND FACTORY CHIMNEYS; Their Draught-Power 
 and Stability. With a Chapter on Lightning Conductors. By Robert 
 Wilson, A. T. C.E. , Author of "A Treatise on Steam Boilers," &c. Second 
 Edition. Crown 8vo, 3s. 6d. cloth. 
 
 " Full of use''ul infonn!ition, definite in statement, and thoroughly practical in treatment. — 
 The Local G<ryer7i)nent Chronicle. 
 
 " A valuable contribution to the iterature of scientific building." — The Builder. 
 
 Boiler MaJcing, 
 
 THE BOILER-MAKER'S READY RECKONER S- ASS 1ST- 
 A NT. With Examples of Practical Geometry and Templating, for the Use 
 of Platers, Smiths and Riveters. By John Courtney, Edited by D. K. Clark, 
 M.I. C.E. Third Edition, 480 pp., with i4oIllusts. Fcap. 8vo, 7s. half-bound. 
 " No workman or apprentice should he without this book."— /ro« Trade Circular. 
 " Boiler-makers will readily recognise the value of this volume. . . , The tables are clearly 
 printed, and so arranged that they can be referred to with the greatest facility, so that it cannot be 
 doubted that they will be generally appreciated and much used." — Mining youmal, 
 
 HEATING BY HOT WATER; with Information and Sug- 
 gestions on the best Methods of Heating Public, Private and Horticultural 
 Buildings. By Walter Jones. With Illustrations, crown 8vo, 2s. cloth. 
 
 " We confidently recommend all interested in heating by hot water to secure a copy of this 
 valuable little treatise." — The Plumber and Decorator^ 
 
MECHANICAL ENGINEERING, &tc. 
 
 Steam Engine, 
 
 TEXT-BOOK ON THE STEAM ENGINE. With a Sup- 
 plement on Gas Engines, and Part II. on Heat Engines. By T. M. 
 GooDEVE, M.A., Barnster-at-Law, Professor ot Mechanics at tbe Normal 
 School of Science and the Royal School of Mines; Author of "The Princi- 
 ples of Mechanics," "The Elementsoi Mechanism," &c. Eleventh Edition, 
 Enlarged. With numerous Illustrations. Crown 8vo, 6s. cloth. 
 
 "Professor Goodeve has given us a treatise on the steam engine which will bear comparison 
 with anything written by Huxley or Maxwell, and we can award it no higher praise." — En^tttef'. 
 
 "Mr. Goodeve's text-book is a work of which every young engineer should possess himself.'" 
 — Mining Journal . 
 
 Gas Engines, 
 
 ON GAS-ENGINES. Being a Reprint, with some Additions, of 
 the Supplement to the Text-book on the Steam Engine^ by T. M. Goodeve, 
 M.A. Crown 8vo, zs. 6d. cloth. 
 " Like aU Mr. Goodeve's writings, the present is no exception In point of general excellence. 
 It is a valuable little volume." — Mecha7iical IForld. 
 
 Steam, 
 
 THE SAFE USE OF STEAM. Containing Rules for Un- 
 professional Steam-users. By an Engineer. Sixth Edition. Sewed, 6d. 
 
 " If steam-users would but learn this little book by heart boiler explosions would become 
 sensations by their rarity." — English Mechanic. 
 
 Hef'erence JBookfor Mechanical Engineers, 
 
 THE MECHANICAL ENGINEER'S REFERENCE BOOK, 
 for Machine and Boiler Construction. In Two Paris. Part I. General 
 Engineering Data. Part II. Boiler Construction. With 51 Plates and 
 nnmerous Illustrations. By Nelson Foley^ M.I.N.A, Folio, £s 55* half- 
 bound. [Jifst published. 
 
 Coal and Speed Tables, 
 
 A POCKET BOOK OF COAL AND SPEED TABLES, for 
 Engineers and Steam-users. By Nelson Foley, Author of "Boiler Con- 
 struction." Pocket-size, a^- 6i. cloth; 4s. leather. 
 
 "These tables are designed to meet the requirements of every-day use ; and maybe com- 
 mended to engineers and users of steam."— Iron, 
 
 ■ " This pocket-book well merits the attention of the practical engineer. Mr. Foley has com- 
 piled a very useful set of tables, the information contained in which is frequently required by 
 engineers, coal consumers and users of steam." — Iron and Coal Trades Review, 
 
 Fire Engineering, 
 
 FIRES, FIRE-ENGINES, AND FIRE-BRIGADES. With 
 a History of Fire-Engines, their Construction, Use, and Management; Re- 
 marks on Fire-Proof Buildings, and the Preservation of Life from Fire ; 
 TToreign Fire Systems, &c. By C. F. T. Young, C.E, With numerous 
 Illustrations, 544 pp., demy 8vo, £"1 4s. cloth. 
 
 " To such of our readers as are interested in the subject of fires and Sre apparatus, we can most 
 heartily commend this book." — Engitteering. 
 
 "It displays much evidence of careful research; and Mr. Youne has put his facts neatly 
 together. It is evident enough that his acquaintance with the practical details of the construction ot 
 steam fire engines Is accurate and i\iQ."~Engin€er. 
 
 Estitnating for Engineering Work, iSc. 
 
 ENGINEERING ESTIMATES, COSTS AND ACCOUNTS: 
 A Guide to Commercial Engineering. With numerous Examples of Esti- 
 mates and Costs of Millwright Work, Miscellaneous Productions, Steam 
 Engines and Sleam Boilers; and a Section on the Preparation of Costs 
 Accounts. By A General Manager. Demy 8vo, 12s. cloth. 
 
 " This is an excellent and very useful book, covering subject-matter in constant requisition ir> 
 every factory and workshop. . .. The book is invaluable, not only to the young engineer, but 
 also to the estimate department of every woYks."— Builder. ... , ^ 
 
 "We accord the work unqualified praise. The mformation is given m a plam, straightforward 
 manner, and bears throughout evidence of the intimate practical acquaintance of the author with 
 every phrase of commercial engineering."— jWficAamVa/ World, 
 
 Elementary Mechanics. 
 
 CONDENSED MECHANICS. A Selection of Formula, Rules, 
 Tables, and Data for the Use of Engineering Students, Science Classes, &c. 
 In Accordance with the Requirements of the Science and Art Department 
 Bv W. G. Crawford Hughes, A.M. I. C.E. Crown 8vo, 2s. 6rf. cloth. 
 
 ■^ IJust published'. 
 
6 CROSBY LOCKWOOD &> SON'S CATALOGUE, 
 
 THE POPULAR WORKS OF MICHAEL REYNOLDS 
 (" The Engine Driver's Friend "). 
 
 Locomotive-Engine Driving, 
 
 LOCOMOTIVE-ENGJNB DRIVING : A Practical Manual for 
 Engineers in charge of Locomotive Engines. By Michael Reynolds, Member 
 of the Society of Engineers, formeriy Locomotive Inspector L. B. and S. C. R. 
 Eighth Edition. Including a Key to the Locomotive Engine. With Illus- 
 trations and Portrait of Author. Crown 8vo, 4s. 6d. cloth. 
 " Mr, Reynolds has supplied a want, and has supplied it well. We can confidently recommend 
 
 the book, not only to the practical driver, but to everyone who takes an interest in the perfonnance 
 
 of locomotive engines." — The Engitteer. 
 
 " Mr. Reynolds has opened ^ neiv chapter in the literature of the day. This admirable practical 
 
 treatise, of the practical utility of which we have to speak in terras of warm commendation."— 
 
 Athen£Butn. 
 
 " Evidently the work of one who knows his subject thoroughly.' — iCatYwaj/ Service Gazette. 
 " Were the cautions and rules given in the book to become part of the every-day working of 
 
 our engine-drivers, we might have fewer distressing accidents to dep\oie,"'-Scotsman. 
 
 Stationary Engine Driving, 
 
 STATIONARY ENGINE DRIVING : A Practical Manual for 
 Enpneers in charge of Stationary Engines. By Michael Reynolds. Fourth 
 Edition, Enlarged. With Plates and Woodcuts, Crown 8vo, 45. 6d. cloth. 
 " The author is thoroughly acquainted with his subjects, and his advice on the various points 
 
 treated is clear and practical, . . . He has produced a manual which is an exceedingly useful 
 
 one for the class for whom it is specially intended." — Engineering-' 
 
 " Our author leaves no stone unturned. He is determined that his readers shall not only know 
 
 something about the stationary engine, but all about it." — Engineer, 
 
 "An engineman who has mastered the contents of Mr.Reynolds's booJcwill require but little actual 
 
 experience with boilers and engines before he can be trusted to look after them." — EnglishMeckanic, 
 
 The Engineer^ Fireman^ and Engine-Boy, 
 
 • THE MODEL LOCOMOTIVE ENGINEER, FIREMAN, and 
 ENGINE-BOY. Comprising a Historical Notice of the Pioneer Locomotive 
 Engines and their Inventors. By Michael Reynolds. With numerous Illus- 
 ^ations and a fine Portrait of George Stephenson. Crown 8vo, 45. 6d. cloth. 
 
 "From the technical knowledge of the author it will appeal to the railway man of to-day more 
 forcibly than anything written by Dr. Smiles. . . . The volume contains information of a tech- 
 nical kind, and facts that every driver should be familiar with." — English Mechanic, 
 
 "We should be glad to see this book in the possession of everyone m the kingdom who has 
 ever laid, or is to lay, hands on a locomotive engine." — Iron, 
 
 Continuous ^Railway Draltes, 
 
 CONTINUOUS RAILWAY BRAKES: A Practical Treatise on 
 the several Systems in Use in the United Kingdom ; their Construction and 
 Performance. With copious Illustrations and numerous Tables. By Michael 
 Reynolds, Large crown 8vo, gs. cloth. 
 
 " A popular explanation of the different brakes. It will be of ^eat assistance in forming public 
 opinion, and will be studied with benefit by those who take an mterest in the brake," — English 
 Mechanic, 
 
 "Written with sufficient technical detail to enable the principle and relative connection ot the 
 various parts of each particular brake to be readily graspea." — Mechasiical World, 
 
 Engine-Driving lAfe, 
 
 ENGINE-DRIVING LIFE : Stirring Adventures and Incidents 
 in the Lives of Locomotive-Engine Drivers. By Michael Reynolds. Second 
 Edition, with Additional Chapters. Crown 8vo. 2s. cloth. 
 
 " From first to last perfectly fascinatmg. Wilkie Colllns's most thrilling conceptions are thrown 
 
 nto the shade by true incidents, endless in their variety, related in every page." — North BriHshMail. 
 
 " Anyone who wishes to get a real insight into railway lif^ cannot do better than read ' Encfine- 
 
 Driving Life' for himself ; and if he once take it up he will find that the author's enthusiasm ana reed 
 
 ove ot the engine-driving profession will carry him on till he has read every ps.g&."^Saturdcij/ Review, 
 
 Pocket Co^npanion for Enginemen, 
 
 THE ENGINEMAN' S POCKET COMPANION AND PRAC^ 
 TICAL EDUCATOR FOR ENGINEMEN, BOILER ATTENDANTS, 
 AND MECHANICS. By Michael Reynolds. With Forty-five Illustra- 
 tions and numerous Diagrams. Second Edition, Revised. Royal i8mo, 3s. 6^., 
 strongly bound for pocket wear. 
 
 "This admirable work is well suited to accomplish its object, being the honest workmanship of 
 a competent engineer." — Glasgow Herald. 
 
 " A most meritorious work, giving in a succinct and practical form all the Information an engine* 
 minder desirous of mastering the scientific principles 01 his daily caUing would require." — Miller. 
 
 " A boon to those who are striving to become efficient mechanics." — Daily Chronicle. 
 
CIVIL E NGINEERING, SURVEYING, etc, 7 
 
 French-English Glossary for Bngineersf etc. 
 
 A POCKET GLOSSARY of TECHNICAL TERMS: ENGLISH- 
 FRENCH, FRENCH-ENGLISH ; with Tables SHitable for the Architectural, 
 Engineering, Manufacturing and Nautical Professions. By John James 
 Fletcher, Engineer and Surveyor, 200 pp. Waistcoat-pocket size, is. 6d., 
 limp leather. 
 
 *' It ousfht certainly to be in the waistcoat-pocket of every professional man." — Iron. 
 " It is a Tery great advantage for readers and correspondents in France and England to have 
 eo lar^e a number of the words relating to engineering and manufacturers collected in a liliputian 
 •rolume. The little book will be useful both to students and travellers.' —Architect. 
 
 *' The glossary of terms is very complete, and many of the tables are new and well arranged. 
 We cordially commend the book. —Mechanical PForla. 
 
 Portable Engines, 
 
 THE PORTABLE ENGINE; ITS CONSTRUCTION AND 
 
 MANAGEMENT. A Practical Manual for Owners and Users of Steam 
 Engines generally. By William Dyson Wansbrough. With 90 Illustra- 
 tions. Crown 8vo, 3s. 6d. cloth. 
 
 " This is a work of value to those who use steam machinery. . . . Should be read by every- 
 one who has a steam engine, on a farm or elsewhere." — MarA Lane Express. 
 
 " We cordially commend this work to buyers and owners of steam engines, and to those who 
 have to do with their construction or use," — Timber Trades journal. 
 
 " Such a general knowledge of the steam engine as Mr. vVansbrough furnishes to the reader 
 'Should be acquired by all inteUigent owners and others who use the steam engine." — Building- News. 
 
 " An excellent text-book of this useful form of engine, which describes with all necessary 
 minuteness the details of the various devices. . . ' The Hmts to Purchasers contain a good deal of 
 commonsense and practical midom."— English Mechanic. 
 
 CIVIL ENGINEERING, SURVEYING, etc. 
 
 MR, NUMBER'S IMPORTANT ENGINEERING BOOKS, 
 The Water Supply of Cities and Towns, 
 
 A COMPREHENSIVE TREATISE on the WATER-SUPPLY 
 OF CITIES AND TOWNS. By William Humber, A-M.Inst.C.E., and 
 M. Inst, M.E., Author of "Cast and Wrought Iron Bridge Construction," 
 &c. &c. Illustrated with 50 Double Plates, i Single Plate, Coloured 
 Frontispiece, and upwards of 250 Woodcuts, and containing 400 pages of 
 Text. Imp. 4to, £6 6s. elegantly and substantially half-bound in morocco. 
 List of Cotitents. 
 
 Conduits.-XIII. DlsttibuHon of Water.-XIV. 
 
 Meters, Service Pipes, and House Fittings, — 
 
 XV. The Law and Economy of Water Works. 
 
 XVI. Constant and Intermittent Supply. — 
 
 XVII. Description of Plates. — Appendices, 
 giving Tables of Rates of Supply, Velocities, 
 &c. &c., together with Specifications of several 
 Works illustrated, among which will be found : 
 Aberdeen, Bideford, Canterbury, Dundee. 
 Halifax, L.ambeth, Rotherham, Dublin, and 
 
 . „ - . others. 
 
 The most systematic and valuable work upon water supply hitherto produced In English, or 
 fa any other language. ■ , . Mr, Humber s work is characterised almost throughout by an 
 exhaustiveness much more distinctive of French and German than of English technical treatises." 
 — Engineer. 
 
 " We can congratulate Mr. Humber on having been able to give so large an amount of Infor- 
 oiation on a subject so important as the water supply of cities and towns. The plates, fiftj; in 
 Qumber, are mostly drawings of executed works, and alone would have commanded the attention 
 of every engineer whose practice may lie in this branch of the profession." — Builder. 
 
 Cast and Wrought Iron Bridge Construction, 
 
 A COMPLETE AND PRACTICAL TREATISE ON CAST 
 AND WROUGHT IRON BRIDGE CONSTRUCTION, including Iron 
 Foundations. In Three Parts — Theoretical, Practical, and Descriptive. By 
 William Humber, A.M.Inst.C.E., and M.Inst.M.E. Third Edition, Re- 
 vised and much improved, with 115 Double Plates (20 of which now first 
 appear in this edition), and numerous Additions to the Text. In Two Vols,, 
 imp. 4to, £6 i6s. 6d. half-bound in morocco. 
 
 " A very valuable contribution to the standard literature of clvD engineering. In addition to 
 elevations, plans and sections, large scale details are given which very much enhance the instruc- 
 tive worth of those iUustrations."— Civil En^i?ieer and Architect's jfournal. 
 
 "Mr, number's stately volumes, lately issued — in which the most important bridges erected 
 during the last five years, under the direction of the late Mr. Brunei, Sir W. Cubitt, Mr. Hawk- 
 chaw, Mr. Page. Mr. Fowler, Mr, Hemans, and others among our most eminent ei^:ineers, are 
 diawn and specified in great detail."— £«^»««r. 
 
 I. Historical Sketch of some of the means 
 tliat have been adopted for the Supply of Water 
 Co Cities cmd Towns. — II. Water and the Fo- 
 reign Matter usually associated with it.— III. 
 Ramfall and Evaporation, — IV. Springs and 
 the water-bearing formations of various dis- 
 tricts. — V. Measurement and Estimation of the 
 flow of Water— VI. On the Selection of the 
 Source of Supply.— VH. WeUs.- VIII. Reser- 
 voirs. — IX, The Purification of Water. — X. 
 Fumps. — XI. Pumping Machinery. — XII. 
 
CROSBY LOCKWOOD &- SON'S CATALOGUE. 
 
 MR. NUMBER'S GREAT WORK ON MODERN ENGINEERING. 
 
 Complete in Four Volumes, imperial 4to, price ^12 12s., half-morocco. Each 
 Volume sold separately as follows : — 
 
 A RECORD OF THE PROGRESS OF MODERN ENGINEER- 
 ING. First Series. Comprising Civil, Mechanical, Marine, Hydraulic, 
 Railway, Bridge, and other Engineering Works, &c. By William Humbbr, 
 A-M.Inst.C.E., &c. Imp. 4to, with 36 Double Plates, drawn to a large scale. 
 Photographic Portrait of John Hawkshaw, C.E., F.R.S., &c., and copious 
 descriptive Letterpress, Specifications, &c., £2 3s. half-morocco. 
 
 List of the Plates and Diagrams, 
 
 Thames, West London Extension R^way (S 
 plates) ; Armour Plates : Suspension Bridge, 
 Thames (4 plates); The Allen Engine; Sus- 
 pension Bri(kfe, Avon (3 plates) ; Underground 
 Railway (3 plates). 
 
 Victoria Station and Roof, L. B. & S. C. R. 
 (8 plates) ; Southport Pier (a plates) ; Victoria 
 Station and Roof, L. C, & D. and G. W. R. (6 
 plates); Roof of Cremome Music Hall ; Bridge 
 over G. N. Railway ; Roof of Station, Dutch 
 Rhenish Rail (z plates) ; Bridge over the 
 
 " Handsomely lithographed and printed. It will find favour with many who desire to preserw* 
 In a permanent form copies of the plans and specifications prepared for the guidance of the con- 
 tractors for many important engineering works." — Sngineer. 
 
 HUMBERTS RECORD OF MODERN ENGINEERING, Second 
 
 Series. Imp. 4to, with 36 Double Plates, Photographic Portrait of Robert 
 Stephenson, C.E., M.P., F.R.S., &c., and copious descriptive Letterpress, 
 Specifications, &c., ^3 3s. half-morocco. 
 
 List 0/ the Plates and Diagrams. 
 
 Birkenhead Docks, Low Water Basin (15 
 
 Slates); Charing Cross Station Roof, C. C. 
 Railway (3 plates) ; Digswell Viaduct, Great 
 Northern Railway ; Robbery Wood Viaduct, 
 Great Northern Railway; Iron Permanent 
 Way; Clydach Viaduct, Merthyr, Tredegar, 
 
 and Abergivenny Railway; Ebbw Viaduct, 
 Merthyr, Tredegar, and Abergavenny Rail- 
 way; College Wood Viaduct, Cornwall Rail- 
 way; Dubhn Winter Palace Roof (3 plates) s 
 Bridge over the Thames, L. C. &; D. Railway 
 (6 plates); Albert Harbour, Greenock (4 plafes). 
 
 " Mr. Humber has done the profession good and true service, by the fine collection of examples 
 he has here brought before the profession and the public." — Practical Mechanic's youmal, 
 
 HUMBERTS RECORD OF MODERN ENGINEERING. Third 
 Series. Imp. 4to, with 40 Double Plates, Photographic Portrait of J. R. 
 M'Clean, late Pres. Inst. C.E., and copious descriptive Letterpress, Speci- 
 fications, &c., 5^3 3*. half-morocco. 
 
 List of the Plates and Diagrams, 
 
 Main Drainage, metropolis.— iVor^A 
 
 Side. — Map showing Interception of Sewers ; 
 Middle Level Sewer (2 plates) ; Outfall Sewer, 
 Bridge over River Lea (3 plates); Outfall Sewer, 
 Bridge over Marsh Lane, North Woolwich 
 Railway, and Bow and Barking Railway Junc- 
 tion; Outfall Sewer, Bridge over Bow and 
 Barking Railway (3 plates); Outfall Sewer, 
 Bridge over East London Waterworks' Feeder 
 (2 plates) ; Outfall Sewer, Reser^'oir (2 plates) ; 
 Outfall Sewer, Tumbling Bay and Outlet ; Out- 
 fall Sewer, Penstocks. South 5irff.— Outfall 
 Sewer, Bermondsey Branch (2 plates); Outfall 
 
 "The drawings have a constantly increasing value, and whoever desires to possess clear repre- 
 sentations of the two great works carried out by our Metropolitan Board will obtain Mr. Humber's 
 volume. " — Engin eer, 
 
 HUMBERTS RECORD OF MODERN ENGINEERING. Fourth 
 
 Series. Imp. 4to, with 36 Double Plates, Photographic Portrait of Joho 
 Fowler, late Pres. Inst. C.E., and copious descriptive Letterpress, Speci- 
 fications, &c., £1 35. half-morocco. 
 
 List of the Plates and Diagrams. 
 
 Sewer, Reservoir and Outlet (4 plates) ; Outfall 
 Sewer, Filth Hoist; Sections of Sewers (North 
 and South Sides). 
 
 THAMES Embankment.— Section of River 
 Wall ; Steamboat Pier, Westminster (2 plates) j 
 Landing Stairs between Charing Cross and 
 Waterloo Bridges ; York Gate (2 plates) ; Over- 
 flow and Outlet at Savoy Street Sewer (3 plates^ 
 Steamboat Pier, Waterloo Bridge (3 plates)) ; 
 Junction of Sewers, Plans and Sections ; 
 Gullies, Plans and Sections ; Rolling Stock ; 
 Granite and Iron Forts. 
 
 Abbey Mills Pumping Station, Main Drain- 
 age, Metropolis (4 plates) ; Barrow Docks (< 
 pUtes) ; Manquis Viaduct, Santiago and Val- 
 paraiso Railway (2 plates); Adam's Locomo- 
 tive, St. Helen's Canal Railway (2 plates) ; 
 Cannon Street Station Roof, Cnarmg Cross 
 Railway (3 plates) ; Road Bridge over tbie River 
 Moka (2 pUtes) ; Telegraphic Apparatus for 
 
 "We gladly welcome another year's issue of this valuable publication from the able pen 09 
 Mr. Humber. The accuracy and general excellence of this work are well known, while its useful- 
 ness in giving the measurements and details of some of the latest examples of engineering, as 
 carried out by the most eminent men in the profession, cannot be too highly prized." — Artixan, 
 
 Mesopotamia ; Viaduct over the River Wye, 
 Midland Railway (3 plates) ; St. Germans Via- 
 duct, Cornwall Railway ^ plates) ; Wrought- 
 Iron Cylinder for Diving Bell; Millwall Docks 
 (6 plates); Milroy's Patent Excavator: Metro- 
 politan District Railway (6 plates); Harbours, 
 Ports, and Breakwaters (3 plates). 
 
CIVIL ENGINEERI NG, SURVEYING, etc. 9 
 
 MR. NUMBER'S ENGINEERING BOOKS—coniinued. 
 StrainSf Calculation of. 
 
 A HANDY BOOK FOR THE CALCULATION OF STRAINS 
 
 IN GIRDERS AND SIMILAR STR UCTURES,AND THEIR STRENGTH. 
 Consisting of Formulae and Corresponding Diagrams, with numerous details 
 for Practical Application, &c. By William Humber. A-M.Inst.C.E., &c, 
 ^ Fifth Edition. Crown 8vo, nearly 100 Woodcuts and 3 Plates, 7s. 6d. cloth 
 " The formulae are neatly expressed, and the diagrams gcod." — Athentzutn, 
 " We heartily commend this really handy book to our engineer and architect readers."— ^«fi*- 
 lish Mechanic 
 
 Sarlow^s Strength of Materials, enlarged by Humber 
 
 A TREATISE ON THE STRENGTH OF MATERIALS : 
 with Rules for Application in Architecture, the Construction of Suspension 
 Bridges, Railways, &c. By Fstter Barlow, F.R.S. A New Edition, revised 
 by his Sons, P. W. Barlow, F.R.S., and W. H. Barlow, F.R.S. ; to which 
 are added, Experiments by Hodgkinson, Fairbairn, and Kirkaldy ; and 
 Formulae for Calculating Girders, &c. Arranged and Edited by W. Humber» 
 A-M.Inst.C.E. Demy 8vo, 400 pp., with 19 large Plates and numerous Wood- 
 cuts, iSs. cloth. 
 " Valuable alike to the student, tyro, and the experienced practitioner. It will always rank ia 
 
 future, as it has hitherto done, as the standard treatise on that particular subject." — Ens^ineer. 
 " There is no ^cater authority than Baxlov." —Building News. 
 _ "As a scientific worlc of the first class, it deserves a foremost place on the bookshelves of evefy 
 
 civil engineer and practical mechanic."— i'M^/tjA Mechanic. 
 
 Trigonometrical Surveying, 
 
 AN OUTLINE OF THE METHOD OF CONDUCTING A 
 
 TRIGONOMETRICAL SURVEY, for the Formation of Geographical and 
 Topographical Maps and Plans, Military Reconnaissance, Levelling, &c., witb 
 Useful Problems, Formulae, and Tables. By Lieut.-General Frome, R.E, 
 Fourth Edition, Revised and partly Re-written by Major General Sir Charles 
 Warren, G.C.M.G., R.E. With 19 Plates and 115 Woodcuts, royal 8vo, 16s. 
 cloth. 
 
 " The simple fact that a fourth edition has been called for is the best testimony to its merits. 
 No words of praise from us can strengthen the position so well and so steadily maintained by this 
 work. Sir Charles Warren has revised the entire work, and made such additions as were necessary 
 to bring every portion of the contents up to the present date." — Broad Arrow. 
 
 Field Fortification, 
 
 A TREATISE ON FIELD FORTIFICATION, THE ATTACK 
 OF FORTRESSES, MILITARY MINING, AND RECONNOITRING, By 
 Colonel I. S. Macaulay, late Professor of Fortification in the R.M.A., Wool- 
 wich. Sixth Edition, crown 8vo, cloth, with separate Atlas of 13 Plates, 125. 
 
 Oblique bridges, 
 
 A PR A CTICA LAND THEORETIC A L ESS A Y ON OBLIQ UE 
 BRIDGES. With 13 large Plates. By the late George Watson Buck, 
 M.I.C.E. Third Edition, revised by his Son, J. H. Watson Buck, M.I.C.E. ; 
 and with the addition of Description to Diagrams for Facilitating the Con- 
 struction of Oblique Bridges, by W. H. Barlow, M.I.C.E. Royal 8vo, 12s. 
 cloth. 
 
 " The standard text-book for all engineers regarding skew arches is Mr. Buck's treatise, and iJ 
 would be impossible to consult a better. ' — Enginter. 
 
 "Mr. Buck's treatise is recognised as a standard text-book, and his treatment has divested the 
 subject of many of the intricacies supposed to belong to it. As a guide to the engineer and archi* 
 tect, on a confessedly difficult subject, Mr. Buck's work is unsurpassed." — Building News, 
 
 Water Storage, Conveyance and Utilisation, 
 
 WA TER ENGINEERING : A Practical Treatise on the Measure- 
 ment, Storage, Conveyance and Utilisation of Water for the Supply of Towns, 
 for Mill Power, and for other Purposes. By Charles Slagg, Water and 
 Drainage Engineer, A.M.Inst.C.E., Author of " Sanitary Work in the Smaller 
 Towns, and in Villages," &c. With numerous Illusts. Cr. 8vo, ys, 6d. cloth. 
 
 "As a small practical treatise on the water supply of towns, and on some applications of 
 water-power, the work is in many respects excellent." — E^tgitieering. 
 
 " The author has collated the results deduced from the experiments of the most eminent 
 authorities, and has presented them in a compact and practical form, accompanied by very cleair 
 and detailed explanations. . . . The apphcation, of water as a motive power is treated very 
 carefully and exhaustively." — Builder. 
 
 "For anyone who desires to begin the study of hydraulics with a consideration of the practical 
 applications of the science there is no better guide." — Architect, 
 
10 CROSBY LOCKWOOD &* SON'S CATALOGUE. 
 
 Statics^ Graphic and Analytic* 
 
 GRAPHIC AND ANALYTIC STATICS Jn their Practical Applu 
 cation to the Treatment of Stresses in Roofs, Selid Girders, Lattice^ Bowstring 
 and Suspension Bridges, Braced Iron Arches and Piers, and other Frameworks, 
 By R. Hudson Graham, C.E. Containing Diagrams and Plates to Scale. 
 With numerous Examples, many taken from existing Structures. Specially 
 arranged for Class-work in Colleges and Universities. Second Edition, Re- 
 vised and Enlarged. 8vo, i6s. clotb. 
 
 ' ' Mr. Grahcua's book will find a place wherever grftpMc and analytic statics are used or studied. " 
 —£n£^ne£r. 
 
 ' ' The work is excellent from a practical point of view, and has evidently been prepared with 
 much care. The directions for working are ample, and are illustrated by an abundance of well- 
 selected examples. It is an excellent text-book for the practical draughtsman." — Atheneeum. 
 
 Student's Text-JSooJc on Surveying, 
 
 PRACTICAL SURVEYING : A Text-Book for Students pre- 
 paring for Examination or for Survey-work in the Colonies. By George 
 W. UsiLL, A.M.I.C.E., Author of "The Statistics of the Water Supply of 
 Great Britain," With Four Lithographic Plates and upwards of 330 Illustra- 
 tions. Second Edition, Revised. Crown 8vo, ys. 6rf. cloth. 
 
 " The best forms of instruments are described as to their construction, uses aild modes of 
 employment, and there are innumerable hints on work and equipment such as the author, in his 
 experience as surveyor, draughtsman and teacher, has found necessary, and which the student 
 in his inexperience will find most serviceable," — Engineer. 
 
 " The latest treatise in the English language on surveying, and we have no hesitation in say- 
 ing that the student will find it a better guide than any of- its predecessors .... 
 Deserves to be recognised as the first book which should be put in the hands of a pupil of Civil 
 Engineering, and every gentleman of education who sets out for the polonies would find it well to 
 tiavea copy." — Architect. 
 
 "A very useful, practical handbook on field practice. Clear, accurate and not too con- 
 densed." — yourjiat o/" Education. 
 
 Survey Practice. 
 
 AID TO SURVEY PRACTICE, for Reference in Surveying, LeveU 
 
 ling, and Setting-ojit ; and in Route Surveys of Travellers by Land and Sea, 
 With Tables, Illustrations, and Records. By Lowis D'A. Jackson, 
 
 A.M.I.C.E., Authcr of " Hydraulic Manual," "Modern Metrology," &c. 
 Second Edition, Enlarged. Large crown 8vO|i2s. 6d. cloth. 
 
 "Mr. Jackson has produced a valuable vade-mecuTtt for the surveyor. We can recommend 
 this book as containing an admirable supplement to the teaching of the accomplished surveyor."— 
 Athenizum. 
 
 " As a text-book we should advise all surveyors to place It In their libraries, and study well the 
 matured instructions afforded in its pages." — Colliery Guardian. 
 
 •* The author brings to his work a fortunate union of theory and practical experience which, 
 aided by a clear and lucid style of writing, renders the book a very useful one." — Builder, 
 
 Surveying, Land and Marine. 
 
 LAND AND MARINE SURVEYING, in Reference to the Pre- 
 
 paration of Plans f jr Roads and Railways ; Canals, Rivers, Towns' Water 
 Supplies; Docks and Harbours. With Description and Use of Surveying 
 Instruments. By W. D. Haskoll, C.E., Author of " Bridge and Viaduct Con- 
 struction," &c. Second Edition, Revised, with Additions, Large cr. 8vo, 9s. cl, 
 " This book must prove of great value to the student. We have no hesitation in recommend- 
 ing it, feeling assured that it wiU more than repay a careful stndy."~Mn:hanicai IVorld. 
 
 "A most useful and well arranged book for the aid of a student. We can strongly recommend 
 tt as a carefuUy-whtten and valuable text-book. It enjoys a well-deserved repute among surveyors." 
 —Buildxr. 
 
 " This volume cannot fail to prove of the utmost practical utility. It may be safely recommended 
 to all students who aspire to become clean and expert surveyors." — Mining Journal. 
 
 Tunnelling. 
 
 PRACTICAL TUNNELLING, Explaining in detail the Setting- 
 out of the works, Shaft-sinkingand Heading-driving, Ranging the Lines and 
 Levelling underground, Sub-Excavating, Timbering, and the Construction 
 of the Brickwork oi Tunnels, with the amount of Labour required for, and the 
 Cost of, the various portions of the work. By Frederick W. Simms, F.G.S., 
 M.Inst.C.E. Third Edition, Revised and Extended by D. Kinnear Clark, 
 M.Inst. C.E. Imperial 8vo, with 2i Folding Plates and numerous Wood 
 Engravings, 30s. cloth. 
 " The estimation in which Mr. SImms's book on tunnelling has been held for over thirty years 
 cannot be moretruly expressed than in the words of the late Prof. Rajikine: — ' The best source of in- 
 formation on the subject of tunnels is Mr.F.W.Simms'swork on Practical Tunnelling.'" — Architect. 
 " It has been regarded from the firstas a text book of the subject. . .' . Mr. CuLfke has added 
 immensely to the value oi the book." — Engineer, 
 
CIVIL ENGINEERING, SURVEYING, etc. ii 
 
 Levelling, 
 
 A TREATISE ON THE PRINCIPLES AND PRACTICE OF 
 
 LEVELLING. Showing its Application to purposes of Railway and Civil 
 Engineering, in the Construction of Roads; with Mr.TELroRD's Rules for the 
 same. By Frederick W. Simms, F.G.S., M.Inst.C.E. Seventh Edition, with 
 the addition of Law's Practical Examples for Setting-out Railway Curves, and 
 Trautwine's Field Practice of Laying-out Circular Curves. With 7 Plates 
 and numerous Woodcuts, 8vo, 8s, 6d. cloth. *^* Trautwine on Curves 
 may be had separate, 5s. 
 
 " The text-book on levelling in most of our eng^Ineeringf schools and colleges." — Engineer. 
 
 " The publishers have rendered a. substantial service to the profession, especially to the younger 
 members, by bringing out the present edition of Mr. Simms's useful work." — Engineerififf. 
 
 Heatf Expansion by, 
 
 EXPANSION OF STRUCTURES BY HEAT. By John 
 Keily, C.E., late of the Indian Public Works and Victorian Railway Depart- 
 ments, Crown Svo, 3s. 6rf. cloth. 
 
 Summary of Contents. 
 Section I. Formulas and Data, Section VL Mechanical Force of 
 
 Section II. Metal Bars. Heat. 
 
 Section III. Simple Frames. Section VII, Work of Expansion 
 
 Section IV, Complex Frames and and Contraction. 
 
 Plates. Section VIII. Suspension Bridges. 
 
 Section V. Thermal Conductivity. Section IX. Masonry Structures. 
 
 " The aim the author has set before him, viz., to show the effects of heat upon metallic and 
 other structures, is a laudable one, for this is a branch of physics upon which the engineer or archi- 
 tect can find but little reliable and comprehensive data in books." — Builder. 
 
 '* Whoever is concerned to know the effect of changes of temperature on such structures as 
 suspension bridges and the like, could not do better than consult Mr, Keily's valuable and handy 
 exposition of the geometrical principles involved in these changes." — Scoisman. 
 
 Practical Mathcfnatics, 
 
 MATHEMATICS FOR PRACTICAL MEN: Being a Common- 
 place Book of Pure and Mixed Mathematics. Designed chiefly for the use 
 of Civil Engineers, Architects and Surveyors. By Olinthus Gregory, 
 LL.D., F.R.A.S., Enlarged by Henry Law, C.E. 4th Edition, carefully 
 Revised by J, R. Young, formerly Professor of Mathematics, Belfast College. 
 With 13 Plates, Svo, £1 is. cloth. 
 " The engineer or architect will here find ready to his hand rules for solving nearly every mathe- 
 matical difficulty that may arise in his practice The rules are in all cases explained by means of 
 examples, in which every step of the process is clearly worked out." — Builder. 
 
 " One of the most serviceable books for prdctical mechanics. . . It is an instructive book for 
 the student, and a text-book for mm who, having once mastered the subjects it treats of, needs 
 occasionally to refresh his memory upon them." — Building News. 
 
 ^Xu^vaulic Tables 
 
 HYDRAULIC TABLES, CO-EFFICIENTS, and FORMULA 
 
 for finding tke Discharge of Water from Orifices, Notches, Weirs, Pipes, and 
 Rivers. With New Formulae, Tables, and General Information on Rainfall, 
 Catchment-Basins, Drainage, Sewerage, Water Supply for Towns and Mill 
 Power. By John Neville, Civil Engineer, M.R.I. A. Third Ed., carefully 
 Revised, with considerabJe Additions. Numerous Illusts. Cr. 8vo, 145. cloth. 
 
 " Alike valuable to students and engineers in practice ; its study will prevent the annoyance of 
 avoidable failures, and assist them to select the readiest means of successfully carrying out any 
 given work connected with hydraulic engineering." — Mining Jouriial. 
 
 " It is, of all English boons on the subject, the one nearest to completeness. . ■ . From the 
 good acrangement of the matter, the clear expl.anations, and abundance of formulas, the carefully 
 calculated tables, and, above all, the thorough, acquaintance with both theory and construction, 
 which is displayed from first to last, the book w be found to be an acquisition."— j4?-cAtfcrf. 
 
 Hydraulics, 
 
 HYDRAULIC MANUAL, Consisting of Working Tables and 
 Explanatory Text. Intended as a Guide in Hydraulic Calculations and Field 
 Operations. By Lowis D'A. Jackson, Author of "Aid to Survey Practice," 
 "Modern Metrology,'' &c. Fourth Edition, Enlarged. Large cr. Svo, i6s. cl. 
 " The author has had a wide experience in hydraulic engineering and has been a careful ob- 
 server of the facts which have come undet his notice, and from the great mass of material at his 
 command he has constructed a manual which may be accepted as a trustworthy guide to this 
 branch of the engineer's profession. We can heartily recommend this volume to all who desire to 
 be acquainted with the latest development of this importcint subject."— Engijieertng. 
 " The standard-work in this department of mechnnics.' — Sco/sman. 
 
 " The most useful feature .of this .work is its freedom from what Is superannuated, and Its 
 thorough adoption of recent exoeriments ; the text is, in fact, in great part a short account of the 
 great modem experiments."— A'aftiw. 
 
12 CROSBY LOCKWOOD &* SON'S CATALOGUE. 
 
 Drainage. 
 
 ON THE DRAINAGE OF LANDS, TOWNS AND BUILD- 
 INGS. By G. D. Dempsey, C.E., Author of "The Practical Railway En- 
 gineer," &c. Revised, with large Additions on Recent Practice in 
 Drainage Engineering, by D. Kinnear Clark, M.Inst.C.E. Author of 
 "Tramways," "A Manual of Rules, Tables, and Data for Enginsers,*' &c. 
 Second Edition, izmo, 5s. cloth. 
 
 " The new matter added to Mr. Dempsey's excellent work is characterised by the comprehen- 
 sive grasp and accuracy of detail for which the name of Mr. D. K. Clark is a sumcient voucher." — 
 Athenaufn. 
 
 " As a work on recent practice in drainage engineering", the book is to be commended to all 
 who are making that branch of engineering science their special study." — Iron. 
 
 " A comprehensive manual on drainage engineering, and a useful introduction to the student," 
 Building News. 
 
 Tramways and their Working, 
 
 TRAMWAYS : THEIR CONSTRUCTION AND WORKING. 
 Embracing a Comprehensive History of the System ; with an exhaustive 
 Analysis of the various Modes of Traction, including Horse-Power, Steam, 
 Heated Water, and Comjpressed Air ; a Description of the Varieties of Rolling 
 Stock ; and ample Details of Cost and Working Expenses : the Progress 
 recently made in Tramway Construction, &c. &c. By D. Kinnear Clark, 
 M.Inst.C.E. With over 200 Wood Engravings, and 13 Folding Plates. Two 
 Vols., large crown 8vo, 30s. cloth. 
 
 " All interested in tramways must refer to it, as all railway engineers have turned to the author's 
 work ' Railway Machinery.'" — Engineer. 
 
 " An exhaustive and practical work on tramways, in which the history of this kind of locomo 
 tlon, and a description and cost of the various modes of laying tramways, are to be found."— 
 Building' News. 
 
 " The best form of rails, the best mode of construction, and the best mechanical appliances 
 are so fairly indicated in the work under review, that any engineer about to construct a tramway 
 will be enabled at once to obtain the practical information which will be of most service to tacQ."— 
 Athenceutn, 
 
 Oblique Arches. 
 
 A PRACTICAL TREATISE ON THE CONSTRUCTION OP 
 OBLIQUE ARCHES. By John Hart. Third Edition, with Plates. Im- 
 perial 8vo, 8s. cloth. 
 
 CurveSf Tables for Setting-ouU 
 
 TABLES OF TANGENTIAL ANGLES AND MULTIPLES 
 for Setting-out Curves from 5 to 200 Radius. By Alexander Beazeley, 
 M.Inst.C.E. Third Edition. Printed on 48 Cards, and sold in a cloth boa, 
 waistcoat-pocket size, 35. &d. 
 " Each table is printed on a small card, which, being placed on the theodolite, leaves the hands 
 
 free to manipulate tne instrument — no small advantage as regards the rapidity of work," — Engineer. 
 " Very handy ; a man may know that all his day's work must fa on two of these cards, which 
 
 he puts into his own card-Ccise, and leaves the rest behind." — Athenceum. 
 
 Earthwork, 
 
 EARTHWORK TABLES. Showing the Contents in Cubic 
 Yards of Embankments, Cuttings, &c.,of Heights or Depths up to an average 
 of 80 feet. By Joseph Broadbent, C.E., and Francis Campin, C.E. Crown 
 
 8vo, 55. cloth. 
 
 " The way in which accuracy is attained, by a simple division ol each cross section into three 
 elements, two in which are constant and one variable, is ingenious." — AtheneeuTti, 
 
 Tunnel Shafts, 
 
 THE CONSTRUCTION OF LARGE TUNNEL SHAFTS : A 
 Practical and Theoretical Essay. By J. H. Watson Buck, M.InstC.E,, 
 Resident Engineer, London and North-western Railway, Illustrated with 
 Folding Plates, royal 8vo, 12s. cloth. 
 
 "Many of the methods given are of extreme practical value to the mason; and the observations 
 on the form of arch, the rules for ordering the stone, and the construction of the templates will be 
 found of considerable use. We commend the book to the engineering profession." — Building News, 
 
 ' ' Will be regarded by civil engineers as of the utmost value, and calculated to save much tiiL e- 
 and obviate many mistakes." — Colliery Guardian, 
 
 Girders, Strength of, 
 
 GRAPHIC TABLE FOR FACILITATING THE COMPUTA- 
 TION OF THE WEIGHTS OF WROUGHT IRON AND STEEL 
 GIRDERS, etc, for Parliamentary and other EstimateF. By J. H. Watsow 
 Buck, M.Inst.C.E. On a Sheet, as.erf. 
 
CIVIL ENGINEERING, SURVEYING, etc, 13 
 
 River Engineering, 
 
 RIVER BARS: The Causes of their Formation, and their Treat- 
 ment by " Induced Tidal Scour; " with a Description of the Successful Re- 
 duction by this Method of the Bar at Dublin. By I. J. Mann, Assist. Eng. 
 to the Dublin Port and Docks Board. Royal 8vo, ys. 6d. cloth. 
 
 " We recommend all interested in harbour works — and, indeed, those concerned in the im- 
 provements of rivers generally — to read Mr. Mann's interesting work on the treatment of river 
 ba rs. ' ' — £tigin eer. 
 
 T'v itsses 
 
 TRUSSES OF WOOD AND IRON. Practical Applications of 
 Science in Determining tke Stresses, Breaking Weights, Safe Loads, Scantlings, 
 and Details of Construction, with Complete Working Drawings. By William 
 Griffiths, Surveyor, Assistant Master, Tranmere School of Science and 
 Art, Oblong 8vo, 4s. 6d. cloth. 
 
 " This handy little book enters so minutely into every detail connected with the construction of 
 toof trusses, that no student need be ignorant of these matters." — J^raciical Engiiteer, 
 
 Hallway Working, 
 
 SAFE RAILWAY WORKING. A Treatise on Railway Acci- 
 dents: Their Cause and Prevention ; with a Description of Modern Appliances 
 and Systems. By Clement E. Stretton, C.E., Vice-President and Con- 
 sulting Engineer, Amalgamated Society of Railway Servants. With Illus- 
 trations and Coloured Places. Second Edition, Enlarged. Crown 8vo, 3s. 6d. 
 cloth. [J^ust published. 
 
 " A book for the engineer, the directors, the managers ; and, in short, all who wish for informa- 
 tion on railway matters will find a perfect encyclopaedia in ' Safe Railway Working. '" — Railway 
 Review. 
 
 " We commend the remarks on railway signalling to all railway managers, especially where a 
 uniform code and practice is advocated."— Herepath's Railiuay 'journal. 
 
 " The author may be congratulated on having collectedj in a very convenient form, much 
 valuable information on the prmcipai questions affecting the safe workirg of railways." — Rati- 
 ■way Engineer. 
 
 Field'SooJc for Engineers^ 
 
 THE ENGINEER'S, MINING SURVEYOR'S, AND CON- 
 TRACTOR'S FIELD-BOOK. Consisting of a Series of Tables, with Rules, 
 Explanations of Systems, and use of Theodolite for Traverse Surveying and 
 Plotting the Work with minute accuracy by means of Straight Edge and Set 
 Square only ; Levelling with the Theodolite, Casting-out and Reducing 
 Levels to Datum, and Plotting Sections in the ordinary manner; setting-out 
 Curves with the Theodolite by Tangential Angles and Multiples, with Right 
 and Left-hand Readings of the Instrument: Setting-out Curves without 
 Theodolite, on the System of Tangential Angles by sets of Tangents and Ofif- 
 sets ; and Earthwork Tables to 80 feet deep, calculated for every 6 inches in 
 depth. By W.Davis Haskoll, C.E. With numerous Woodcuts. Fourth 
 Edition, Enlarged. Crown 8vo, 12s. cloth. 
 
 "The book is very handy; the separate tables of sines and tangents to every minute will make 
 it useful for many other purposes, the genuine traverse tables existing all the same." — Athentzunt. 
 
 " Every person engaged m engineering field operations will estimate the importance of such a 
 work and the amount of v*iluable time which will be saved by reference to a set of reliable tables 
 prepared with the accuracy and fulness of those given in this volume." — Railway News. 
 
 Earthworlc^ Meamire^nent of, 
 
 A MANUAL ON EARTHWORK, By Alex. J. S. Graham, 
 C.E. With numerous Diagrams. Second Edition, i8mo, 2s. 6d. cloth 
 "A great amount of practical information, very admirably arranged, and available for rough 
 
 estimates, as well as for the more exact calculations required in the engineer's and contractor's 
 
 offices." — Ariixan. 
 
 Strains in Ironwork, 
 
 THE STRAINS ON STRUCTURES OF IRONWORK; with 
 Practical Remarks on Iron Construction. By F. W. Sheilds, M.Inst,C.E, 
 Second Edition, with 5 Plates. Royal 8vo, 55. cloth. 
 The student cannot find a better little book on this subject."— .£';;^'««^. 
 
 Cast Iron and other Metals, Strength of, 
 
 A PRACTICAL ESSAY ON THE STRENGTH OF CAST 
 IRON AND OTHER METALS. By Thomas Tredgold, C.E. Fifth 
 Edition, including Hodgkinson's Experimental Researches. 8vo, 12s. cloth. 
 
14 CROSBY LOCKWOOD &■ SON'S CATALOGUE. 
 
 ARCHITECTURE, BUILDING, etc. 
 
 THE SCIENCE OF BUILDING : An Elementary Treatise on 
 the Principles of Construction. By E. Wyndham Tarn, M.A., Architect. 
 Third Edition, Enlarged, with 59 Engravings. Fcap. 8vo, 4s. cloth. 
 " A very valuable book, which we strongly recommend to all students." — Builder. 
 " No architecbiretl student should be without this handbook.' ~~ A rchHect. 
 
 Villa Architecture, 
 
 A HANDY BOOK OF VILLA ARCHITECTURE: Being a 
 Series of Designs for Villa Residences in various Styles. With Outline 
 Specifications and Estimates. By C. Wickes, Author of "The Spires and 
 Towers of England," &c. 61 Plates, 410, £1 us, 6d. half-morocco, gilt edges. 
 " The whole of the designs bear evidence of their being the work of an artistic architect, and 
 they will prove very valuable and sugfiestive."—£uii(img-J^ws, 
 
 Text-BooTc for Architects, 
 
 THE ARCHITECT'S GUIDE: Being a Text-Booh of Useful 
 Information for Architects, Engineers^ Surveyors, Contractors, Clerks of 
 Works, &c, &c. By Frederick Rogers, Architect, Author of " Specifica- 
 tions for PracticalArchitecture,"&c. Second Edition, Revised and Enlarged. 
 With numerous Illustrations. Crown 8vo, 65. cloth. 
 
 "As a text-book of useful information for architects, engineers, surveyors, &c., it would be 
 hard to find a handier or more complete Uttle volume," — Standard. 
 
 "A young architect could hardly have a better guide-book." — Timber Trades journal, 
 
 Taylor and Cresy's Ro^ne, 
 
 THE ARCHITECTURAL ANTIQUITIES OF ROME, By 
 
 the late G. L.Taylor, Esq., F.R.I. B. A., and Edward Cresy, Esq. New 
 Edition, thoroughly Revised by the Rev. Alexander Taylor, M.A. (son of 
 the late G. L, Taylor, Esq.), Fellow of Queen's College, Oxford, and Chap- 
 lain of Gray's Inn. Large folio, with 13c Plates, half-bound, £5 3s, 
 "Taylor and Cresy's work has from Its first publication been ranked among those professional 
 books which cannot be bettered. ... It would be difficult to find examples of drawings, even 
 among those of the most painstaking students of Gothic, more thoroughly worked out than are the 
 one hundred and thirty pmtes in this volume." — Architect. 
 
 Ijifhcar I^ers'^ect tve 
 
 ARCHITECTURAL PERSPECTIVE : The whole Course and 
 Operations of the Draughtsman in Drawing a Large House in Linear Per- 
 spective. Illustrated by 39 Folding Plates, By F. O. Ferguson, Demy 
 8vo, 3s. 6d. boards. IJiisf published. 
 
 Architectural Drawing, 
 
 PRACTICAL RULES ON DRA WING, for ike Operative Builder 
 and Young Student in Architecture. By George Pyne. With 14 Plates, 4to, 
 75. 6d. boards. 
 
 Sir JVm, Chambers on Civil Architecture, 
 
 THE DECORATIVE PART OF CIVIL ARCHITECTURE. 
 By Sir William Chambers, F.R.S. With Portrait, Illustrations, Notes, and 
 an Examination of Grecian Architecture, by Joseph Gwilt, F.S.A. Revised 
 and Edited by W, H, Leeds, with a Memoir of the Author, 66 Plates, 4to, 
 215. cloth. 
 
 House Building and Repairing, 
 
 THE HOUSE-OWNER'S ESTIMATOR ; or. What will it Cost 
 to Buili, Alter, or Repair? A Price Book adapted to the Use of Unpro- 
 fessionil People, as well as for the Architectural Surveyor and Builder. By 
 James D. Simon, A.R.LB.A. Edited and Revised by Francis T, W. Miller, 
 A. R.I. B, A. With numerous Illustrations. Fourth Edition, Revised. Crown 
 8vo, 3s. 6d. cloth, 
 "In two years it will repay its cost a hundred times over." — Field, 
 
 Cottages and Villas. 
 
 COUNTRY AND SUBURBAN COTTAGES AND VILLAS: 
 How to Plan and Build Them, Containing 33 Plates, with Introduction, 
 General Explanations, and Description of each Plate. By James W. Bogue, 
 Architect, Author of " Domestic Architecture," &c, 4to, los. Qd. cloth. 
 
ARCHITECTURE, BUILDING, etc. 15 
 
 The Neiv Builder's Price Book, 1892. 
 
 LOCKWOOD'S BUILDER'S PRICE BOOK FOR 1892. A 
 Comprehensive Handbook of the Latest Prices and Data for Builders^ 
 Architects, Engineers and Contractors. Re-constmcted, Re-written and 
 Further Enlarged. By Francis T. W. Miller, 700 closely-printed pages, 
 crown 8vo, 4s. cloth. [just published. 
 
 " This book is a very useful one, and should find a place in every English office connected with 
 the building- and engfineerin? pTQ[es^ons."—Inciiisiries. 
 
 "This Price Book has been set up in new type. . . . Advantage has been taken of the 
 transformation to add much additional information, and the volume, is now an excellent book of 
 reference. "~A rchitect. 
 
 " In its new and revised form this Price Book is what a work of this kind should be— compre- 
 hensive, reliable, well arranged, legible and well bound.' —British Archittct. 
 " A \york of established reputation."— -4^A<;«<?;;»;. 
 
 "This very useful handbook is well written, exceedingly clear in its explanations and great 
 care has evidently been taken to ensure accuracy."— jWtir«i«j^ Advertiser. 
 
 Designing, Pleasuring, and Valuing, 
 
 THE STUDENTS GUIDE to the PRACTICE of MEASUR- 
 ING AND VALUING ARTIFICERS' WORKS. Containing Directions for 
 taking Dimensions, Abstracting the same, and bringing the Quantities into 
 Bill, with Tables of Constants for Valuation of Labour, and for the Calcula- 
 tion of Areas and Solidities, Originally edited by Edward Dobson, Architect. 
 With Additions on Mensuration and Construction, and a New Chapter on 
 Dilapidations, Repairs, and Contracts, by E. Wyndham Tarn, M,A. Sixth 
 Edition, including a Complete Form of a Bill of Quantities. With 8 Plates and 
 63 Woodcuts. Crown 8vo, 7s. 6d. cloth. 
 
 " Well fulfils the promise of its title-page, and we can thoroughly recommend it to the class 
 for whose use it has been compiled. Mr. Tarn's additions and revisions have much increased the 
 usefulness of the work, and have especially augmented its value to students."— En2-i?ieerin£. 
 
 "This edition will be found the most complete treatise on the principles of measuring and 
 valuing artificers' work that has yet been puh]ished."—£i(UdiK£-NeTi;s. 
 
 I'ocTcet Estimator and Technical Guide, 
 
 THE POCKET TECHNICAL GUIDE, MEASURER AND 
 ESTIMATOR FOR BUILDERS AND SURVEYORS, Containing Tech- 
 nical Directions for Measuring Work in all the Building Trades, Complete 
 Specifications for Houses, Roads, and Drains, and an easy Method of Estimat- 
 ing the parts of a Building collectively. By A. C. Beaton, Author of 
 "Quantities and Measurements," &c. Sixth Edition, Revised. With 53 
 Woodcuts, waistcoat-pocket size, is. 6d. gilt edges. [Just published. 
 
 "No builder, architect, surveyor, or valuer should be without his ' Beaton." — Buildi7tg- News. 
 
 " Contains an extraordinary amount of information in daily requisition in measuring and 
 estimating. Its presence in the pocket will save valuable time and tion\M,"— Building World. 
 
 Donaldson on Specifications, 
 
 THE HANDBOOK OF SPECIFICATIONS; or. Practical 
 Guide to the Architect, Engineer, Surveyor, and Builder, in drawing up 
 Specifications and Contracts for Works and Constructions. Illustrated by 
 Precedents of Buildings actually executed by eminent Architects and En- 
 gineers. By Proiessor T. L. Donaldson, P.R.LB. A., &c. New Edition, Id 
 One large Vol., Svo, with upwards of 1,000 pages of Text, and 33 Plates, 
 £xiis.6d. cloth. 
 
 " In this work forty-four specifications of executed works are given, Including the specifica- 
 tions for parts of the new Houses of Parliament, by Sir Charles Barry, and for the new Royal 
 Exchange by Mr. Tite, M.F. The latter, in particular, is a very complete and remarkaSle 
 document. It embodies, to a great extent, as Mr. Donaldson mentions, 'the bill of quantities 
 with the description of the works.' ... It is valuable cLS a record, and more valuable still as a 
 book of precedents. , . . Suffice it to say thaC Donaldson's 'Handbook of Specifications 
 must be bought by all architects,"— ifMi^e&r. 
 
 Bartholomew and Rogers' Specifications, 
 
 SPECIFICATIONS FOR PRACTICAL ARCHITECTURE. 
 
 A Guide to the Architect, Engineer, Surveyor, and Builder. With an Essay 
 
 on the Structure and Science of Modern Buildings, Upon the Basis of the 
 
 Work by Alfred Bartholomew, thoroughly Revised, Corrected, and greatly 
 
 added to by Frederick Rogers, Architect. Second Edition, Revised, with 
 
 Additions, With numerous lUastrations, medium 8vo, 155. cloth. 
 
 "The collection of specifications prepared by Mr. Rogers on the basis of Bartholomew's work 
 
 is too weU known to need any recommendation from us. It is one of the books with which every 
 
 young architect must be equipped ; for time lias shown that the specificatio5is cannot be set aside 
 
 through any defect in them."— .<4rf/w'ftrt. 
 
i6 ROSBY LOCKWOOD &- SON'S CATALOGUE, 
 
 Siuildlng ; Civil and JEcclesiasticaL 
 
 A BOOK OM BUILDING, Civil and Ecclesiastical, including 
 Church Restoration ; with the Theory of Domes and the Great Pyramid, &c. 
 By Sir Edmund Beckett, Bart., LL.D., F.R.A.S., Author of " Clocks and 
 Watches, and Bells," &c. Second Edition, Enlarged. Fcap. 8vo, 5s. cloth. 
 
 "A book which is always amusing and nearly always instruccive. The style throughout is in 
 t-he highest degree condensed and epigframmatic."— /"iwitfj. 
 
 Ventilation of Buildinfjs. 
 
 VENTILATION. A Text Book io the Practice of the Art oj 
 Ventilating Buildings. With a Chapter upon Air Testing. By W. P, Buchan, 
 R.P., Sanitary and Ventilating Engineer, Author of " Plumbing," &c. With 
 170 IllustratioDS. i2mo, 4s. cloth boards. IJust published. 
 
 The Art of Pliinihing. 
 
 PLUMBING. A Text Book to the Practice of the Art or Craft of 
 the Plumber, with Supplementary Chapters on House Drainage, embodying the 
 latest Improvements. By William Paton Buchan, R.P,, Sanitary Engineer 
 and Practical Plumber. Sixth Edition, Enlarged to 370 pages, and 380 
 Illustrations. i2mo, 4s. cloth boards. 
 
 " A text book which may be safely put in the hands of every young plumber, and which will 
 also be found useful by architects and medical professors." — Builder. 
 
 " A valuable text Dook, and the only treatise which can be regarded as a really reliable manual 
 
 of the plumber's art." — Builtiin^ News. 
 
 Geometry for the Architect, Engineer, etc, 
 
 PRACTICAL GEOMETRY, for the Architect, Engineer and 
 Mechanic. Giving Rules for the Delineation and Application of various 
 Geometrical Lines, Figures and Curves. By E. W. Tarn, M.A., Architect, 
 Author of "The Science of Building," &c. Second Edition. With 172 Illus- 
 trations, demy 8vo, gs. cloth. 
 
 " No book with the same objects in view has ever been published in which the clearness of the 
 rules laid down and the illustrative diagrams have been.so satisfactory." — Scotsman. 
 
 The Science of Geometry, 
 
 THE GEOMETRY OF COMPASSES; or, Problems Resolved 
 by the mere Description of Circles^ and the use of Coloured Diagrams and 
 Symbols. By Oliver Byrne. Coloured Plates. Crown 8vo, 3s. 6d, cloth. 
 " The treatise is a good one, and remarkable — hke all Mr. Byrne's contributions to the science 
 af geometry — for the lucid character of its teaching." — Btiilding NeTus. 
 
 DECORATIVE ARTS, etc. 
 
 Woods and Marbles (Imitation of). 
 
 SCHOOL OF PAINTING FOR THE IMITATION OF WOODS 
 
 AND MARBLES, as Taught and Practised by A. R. Van der Burg and P. 
 
 Van der Burg, Directors of the Rotterdam Painting Institution. Royal folio, 
 
 iSi by 12^ in.. Illustrated with 24 full-size Coloured Plates; also 12 plain 
 
 Plates, comprising 154 Figures. Second and Cheaper Edition. Price £1 ii5.6d. 
 
 List of Plates, 
 
 I. Various Tools required for Wood Painting 
 
 — 2, 3. Walnut : Preliminary Stages of Graining 
 
 tnd Finished Specimen — 4. Tools used for 
 
 Finished Specimen — 19. Mahogany: Specimens 
 of various Grains and Methods of Manipulation 
 —20, 21. Mahogany: Earlier Stages and Finished 
 Specimen — 22,23,24. Sienna Marble : Varieties 
 of Grain, Preliminary Stages and Finished 
 Specimen — 25, 26, 27. Juniper Wood : Methods 
 of producing Grain, &c, ; Preliminary Stages 
 and Finished Specimen — 28, 29, 30. Vert do 
 Mer Marble: Varieties of Grain and Methods 
 of Workihg Unfinished and Finished Speci- 
 mens — 31. 32. 3?. Oak : Varieties of Grain, Tools 
 Employed, and Methods of Manipulation, Pre- 
 
 Marble Painting and Method of Manipulation— 
 f,6. St. Rem! Marble; Earlier Operations and 
 Finished Specimen — 7. Methods of Sketching 
 different Grains, Knots. Ac— 8, 9. Ash: Pre- 
 liminarv Stages and Finished Specimen — 10. 
 Methods of Sketching Marble txrains — 11, 12. 
 Breche Marble : Preliminary Stages of Worlting 
 and Finished Specimen — 13. Maple : Methods 
 of Producing the different Grains — 14, ic. Bird's- 
 eye Maple: Preliminary Stages and Finished 
 Specimen — 16. Methods of Sketching the dif- 
 ferent Species of White Marble — 17, 18. White 
 Marble : Preliminary Stages of Process and 
 
 *^* Opinions of the Press, 
 
 " Those who desire to attain skill in the art of painting woods and marbles will find advantage 
 In consulting this book. . . . Some of the Worlung Men's Clubs should give their young men 
 the opportunity to study it." — Btiilder. 
 
 " A comprehensive guide to the art. The explanations of the processes, the manipulation and 
 management of the colours, and the beautifully executed plates will not be the least valuable to the 
 Kudent who aims at making his work a faithful transcript of nature." — Building News. 
 
 liminary Stages and Finished Specimen — 34, 35, 
 36. Waulsort Marble: Varieties of Grain, iTn- 
 finished and Finished Specimens. 
 
DECORATIVE ARTS, etc, 17 
 
 Souse Decoration^ 
 
 ELEMENTARY DECORATION. A Guide to the Simpler 
 Forms of Everyday Art, as applied to the Interior and Exterior Decoration of 
 Dwelling Houses, &c. By James W. Facey, Jun. With 68 Cuts. lamo, w. 
 cloth limp. 
 
 PRACTICAL HOUSE DECORATION : A Guide to the Art of 
 Ornamental Painting, the Arrangement of Colours in Apartments, and the 
 principles of Decorative Design. With some Remarks upon the Nature and 
 Properties of Pigments. By James William Facey, Author of " Elementary 
 Decorationj" &c. With numerous Illustrations, izmo, 25. 6d. cloth limp. 
 N.B. — The above Two Works together in One Vol., strongly half-bound, 55, 
 
 Colour* 
 
 A GRAMMAR OF COLOURING. Apph'ed to Decorative 
 Painting and the Arts. By George Field. New Edition, Revised, Enlarged, 
 and adapted to the use of the Ornamental Painter and Designer. By Ellis 
 A. Davidson. With New Coloured Diagrams and Engravings, i2mo, 35. 6rf. 
 cloth boards. 
 "The book is a most useful resume of the properties of pig;ments."— rOTVt&n 
 
 Mouse Fainting^ Graining, etc, 
 
 HOUSE PAINTING, GRAINING, MARBLING, AND SIGN 
 WRITING, A Practical Manual of. By Ellis A. Davidson. Sixth Edition. 
 With Coloured Plates and Wood Engravings. larao, 6s. cloth boards. 
 
 " A mass of infonnation, of use to the amateur and of value to the practical man." — Eji^iish 
 Mechanic, 
 
 ' ' Simply invaluable to the youngster entering upon this particular caUing', and highly service 
 able to the man who is practising it. — F'urtiiinre Gazette, 
 
 Decorators, Receipts for. 
 
 THE DECORATOR'S ASSISTANT: A Modern Guide to De- 
 corative Artists and Amateurs, Painters, Writers, Gilders, &c. Containing 
 upwards of 600 Receipts, Rules and Instructions ; with a variety of Informa- 
 tion for General Work connected with every Class of Interior and Exterior 
 Decorations, &c. Fourth Edition, Revised. 152 pp., crown 8vo, 15. in wrapper. 
 
 " Full of receipts of value to decorators, painters, gilders, &c. The book contains the gist of 
 larger treatises on colour and technical processes. It would be difficult to meet with a work so full 
 of varied information on the painter's a.rt."— Bui/ding- News. 
 
 " We reconunend the work to all who, whether for pleasure or profit, require a guide to decora- 
 tion," — Plumber and Decorator. 
 
 Moyr Smith on Interior Decoration. 
 
 ORNAMENTAL INTERIORS. ANCIENT AND MODERN. 
 By J. MoYR Smith, Super-royal 8vo, with 32 full-page Plates and numerous 
 smaller Illustrations, handsomely bound in cloth, gilt top, price 185. 
 
 " The book is well illustrated and handsomely got up, and contains some true criticism and » 
 good many good examples of decorative treatment,' — The Builder. 
 
 " This is the most elaborate and beautiful work on the artistic decoration of interiors that we 
 have seen* . . . The scrolls, panels and other designs ftom the author's own pen are very 
 beautiful and chaste ; but he takes care that the designs of other men shall figure even more thar. 
 his ovm,"—Lvverpool Albion. 
 
 " To all who take an interest In elaborate domestic ornament this handsome volume will be 
 welcome." — Graphic. 
 
 British and Foreign 31arhles. 
 
 MARBLE DECORATION and the Terminology of British and 
 Foreign Marbles. A Handbook for Students. By George H. Blagrove, 
 Author of " Shoring and its Application/' &c, With 28 Illustrations. Crown 
 8vo, 3s. 6d. cloth. 
 
 " This most useful and much wanted handbook should be in the hands of every architect and 
 builder." — Building World. 
 
 " It is an excellent manual for students, and interesting to artistic readers generally."— Ja^wra'ay 
 
 ' ' A carefully and usefully written treatise ; the work is essentially practical."— Jctj/jwa^, 
 
 Marble Working, etc, 
 
 MARBLE AND MARBLE WORKERS: A Handbook for 
 Architects, Artists, Masons and Students. By Arthur Lee, Author of " A 
 Visit to Carrara," "The Working of Marble," &c. Small crown 8vo, 2s. cloth. 
 " A really valuable addition to the technical literature of architects and masons."— Building 
 
1 8 CROSBY LOCK WOOD S- SON'S CATALOGUE. 
 
 DELAMOTTE'S WORKS ON ILLUMINATION AND ALPHABETS. 
 
 A PRIMER OF THE ART OF ILLUMINATION, for the Use of 
 Beginners : with a Rudimentary Treatise on the Art, Practical Directions for 
 its exercise, and Examples taken from Illuminated MSS., printed in Gold and 
 Colours. By F. Dklamotte. New and Cheaper Edition. Small 4to, 6s. orna- 
 mental boards. 
 "The examples of ancient MSS. recommended to the student, which, with much eood sense, 
 
 the author chooses from collections accessible to all, are selected with judgment and Knowledge, 
 
 as well as taste." — Atkemzum, 
 
 ORNAMENTAL ALPHABETS, Ancient and Mediaval, from the 
 ■ Eighth Century, with Numerals; including Gothic, Church-Text, large and 
 small, German, Italian, Arabesque, Initials for Illumination, Monograms, 
 Crosses, &c. &c., for the use of Architectural and Engineering Draughtsmen, 
 Missal Painters, Masons, Decorative Painters, Lithographers, Engravers, 
 Carvers, &c. &c. Collected and Engraved by F. Delamotte, and printed in 
 Colours. New and Cheaper Edition. Royal 8vo, oblong, 2s. 6d. ornamental 
 boards, 
 
 ' ' For those who Insert enamelled sentences round gilded chalices, who blazon shop legends over 
 shop-doors, who letter church walls with pithy sentences from the Decalogue, this book will be use- 
 ful.' — Athennsu^n, 
 
 EXAMPLES OF MODERN ALPHABETS, Plain and Ornamental; 
 including German, Old English, Saxon, Italic, Perspective, Greek, Hebrew, 
 Court Hand, En^ossing, Tuscan, Riband, Gothic, Rustic, and Arabesque ; 
 with several Origmal Designs, and an Analysis of the Roman and Old English 
 Alphabets, large and small, and Numerals, for the use of Draughtsmen, Sur- 
 veyors, Masons, Decorative Painters, Lithographers, Engravers, Carvers, &c. 
 Collected and Engraved by F. Delamotte, and printed in Colours. New 
 and Cheaper Edition. Royal 8vo, oblong, 2S. 6d. ornamental boards. 
 "There is comprised in it ev^ry possible shape into which the letters of the alphabet and 
 
 numerals can be formed, and the talent which has been expended in the conception of the various 
 
 plain and ornamental letters is wonderful," — Standard, 
 
 MEDIEVAL ALPHABETS AND INITIALS FOR ILLUMI^ 
 NATORS. By F. G. Delamotte. Containing 21 Plates and Illuminated 
 Title, printed in Gold and Colours. With an Introduction by T. Willis 
 Brooks. Fourth and Cheaper Edition. Small 4to, 4s. ornamental boards. 
 " A volume In which the letters of the alphabet come forth glorified in gilding and all the colours 
 
 of the prism interwoven and intertwined ana intermingled." — Sun. 
 
 THE EMBROIDERER'S BOOK OF DESIGN, Containing 
 Initials, Emblems, Cyphers, Monograms, Ornamental Borders, Ecclesiastical 
 Devices, Mediseval and Modern Alphabets, and National Emblems. Col- 
 lected by F. Delamotte, and printed in Colours. Oblong royal 8vo, is. 6rf. 
 ornamental wrapper. 
 " The book will be of great assistance to ladles and young children who are endowed with the 
 
 art of plying the needle in this most ornamental and useful pretty y/oxW—^asi Anglian Times. 
 
 Wood Carving, 
 
 INSTRUCTIONS IN WOOD-CARVING, for Amateurs; with 
 Hints on Design. By A Lady. With Ten Plates. New and Cheaper Edition. 
 Crown 8vo, 25, in emblematic wrapper. 
 
 " The handicraft of the wood-carver, so well as a book can Impart It, may be leamt from ' A 
 Lady's' publication." — Athenauvn. 
 
 " The directions given are plain and easily understood." — English Mechanic, 
 
 Glass Painting, 
 
 GLASS STAINING AND THE ART OF PAINTING ON 
 GLA SS, From the German of Dr. Gessert and Emanued Otto Fromberg. 
 With an Appendix on The Art of Enamelling. i2mo, 2s. 6cl. cloth limp. 
 
 Letter Painting, 
 
 THE ART OF LETTER PAINTING MADE EASY. By 
 James Greig Badenoch. With iz full-page Engravings of Examples, is. 6d. 
 cloth limp. 
 
 " The system is a simple one, but quite original, and well worth the careful attention of letter 
 painters. It can be easily mastered and tememheied."— Building Nnt/s, 
 
CARPENTRY, TIMBER, etc. ig 
 
 CARPE NTRY, TIMBER , etc, 
 
 Tredgold's Carpentry, Revised i& Enlarged by Tarn. 
 
 THE ELEMENTARY PRINCIPLES OF CARPENTRY, 
 
 A Treatise on the Pressure and Equilibrium of Timber Framing, tbe Resist- 
 ance^ of Timber, and the Construction of Floors, Arches, Bridges, Roofs, 
 Uniting Iron and Stone with Timber, &c. To which is added an Essay 
 on the Nature and Properties oi Timber, &c., with Descriptions of the kinds 
 ef Wood used in Building ; also numerous Tables of the Scantlings of Tim- 
 ber for different purposes, the Specific Gravities of Materials, &c. By Thomas 
 Tredgold, C.E, With an Appendix of Specimens of Various Roots of Iron 
 •and Stone, Illustrated. Seventh Edition, thoroughly revised and considerably 
 enlarged by E. Wyndham Tarn, M.A., Author ol "The Science of Build- 
 ing," &c. With 6i Plates, Portrait of the Author, and several Woodcuts, In 
 one large vol., 4to, price £i gs. cloth. 
 
 "Ouffht to be in ever>' architect's and every builder's Uhr iTy."— Builder, 
 " A work whose monumental excellence must commend it wherever skilful carpentry Is con- 
 cerned. The author's principles are rather confirmed than impaired by time. The additional 
 plates are of great intrinsic value." — Buildifig News. 
 
 Woodworking Machinery. 
 
 WOODWORKING MACHINERY : Its Rise, Progress, and 
 ■Construction. With Hints on theManagement of Saw Mills and the Economi- 
 cal Conversion of Timber. lUustratediWith Examples oi Recent Designs by 
 leading English, French, and American Engineers. By M. Powis Bale, 
 A.M.Inst.C.E., M.I.M.E. Large crown 8vo, 12s. 6cl. cloth. 
 
 " Mr. Bale is evidently an expert on the subject and he has collected so much Information that 
 tiis book is all-sufficient for builders and others engaged in the conversion of timber." — A^hilect. 
 
 "The most comprehensive compendium of wood-working machinery we have seen. The 
 Author is a thorough master of his subject." — Building Nrws. 
 
 " The appearance of this book at the present time will, we should think, give a consid rable 
 impetus to the onward march of the machinist engaged in the designing and manufacti re of 
 wood-working machines, it should be in the office of every wood-working factory." — Ei glish 
 Mechanic. 
 
 Saw Mills. 
 
 SA W MILLS : Their Arrangement and Management, and the 
 Economical Conversion of Timber. (A Companion Volume to " Woodwork- 
 ing Machinery.*') By M. Powis Bale, With numerous Illustrations. ClOW 
 8vo, IDS. 6d. cloth. 
 
 " The administration of a large sawing establishment is discussed, and the subject examincv. 
 6rom a financial standpoint. We could not desire a more complete or practical treatise."— ffMi/</g»-. 
 
 " We highly recommend Mr. Bale's work to the attention and perusal of all those who are en- 
 gaged in the art of wood conversion, or who are about building or remodelling saw-mills on im- 
 proved principles."— ^i*t^rfx«^ News. 
 
 Carp entering. 
 
 THE CARPENTER'S NEW GUIDE ; or, Book of Lines for Car- 
 penters ; comprising all the Elementary Principles essential for acquiring a 
 knowledge of Carpentry. Founded on the late Peter Nicholson's Standard 
 Work. A New Edition, Revised by Arthur Ashpitel, F.S.A. Together 
 with Practical Rules on Drawing, by George Pvne, With 74 Platesi 
 4to, £1 IS. cloth, 
 
 Slandrailing and Sfairbuilding, 
 
 A PRACTICAL TREATISE ON HANDRAILING : Showing 
 New and Simple Methods for Finding the Pitch of the Plank, Drawing the 
 Moulds, Bevelling, Jointing-up, and Squaring the Wreath. By George 
 CoLLiNGS. Second Edition, Revised and Enlarged, to which is added A 
 Treatise on Stairbuilding. With Plates and Diagrams, igmo, 2s. 6d, 
 cloth limp. 
 
 " Will be found of practical utility in the execution of this difficult branch of joinery." — Builder. 
 
 "Almost every difficult phase of this somewhat intricate branch of joinery is elucidated by the 
 tid of plates and explanatory lettetptess."—Furftiiure Gazette. 
 
 Circular WorJc, 
 
 CIRCULAR WORK IN CARPENTRY AND JOINERY: A 
 Practical Treatise on Circular Work of Single and Double Curvature. By 
 George Collings, Author of " A Practical Treatise on Handrailing." Illus- 
 trated with numerous Diagrams. Second Edition, i2mo, 2s. 6d. dfoth limp. 
 " An excellent example of what a book of this kind should be. Cheap in price, clear in defini- 
 tion and practical in the examples selected,"— Uuilder, 
 
20 CROSBY LOCKWOOD <S* SON'S CATALOGUE, 
 
 Timber Merchant's Companion, 
 
 THE TIMBER MERCHANTS AND BUILDER'S COM- 
 PANION. Containing New and Copious Tables of the Reduced Weight and 
 Measurement of Deals and Battens, of all sizes, from One to a Thousand 
 Pieces, and the relative Price that each size bears per Lineal Foot to any 
 given Price per Pet^sburg Standard Hundred ; the Price per Cube Foot of 
 Square Timber to any given Price per Load of 50 Feet ; the proportionate 
 Value of Deals and Battens by the Standard, to Square Timber by the Load 
 of 50 Feet ; the readiest mode of ascertaining the Price of Scantling per 
 Lineal Foot of any size, to any given Figure per Cube Foot, &c. &c. By 
 William Dowsing. Fourth Edition, Revised and Corrected. Cr, 8vo, 3s, cl . 
 "We are glad to see a fourth edition of these admirable tables, which for correctness and 
 
 simplicity of arrangement leave nothing to be desired." — Timf-er Trades journal. 
 
 "An exceedingly well-arranged, clear, and concise manual of tables for the use of all who buy 
 
 or sell timber." — Jottrnal of forestry. 
 
 Practical Timber 3Ierchant, 
 
 THE PRACTICAL TIMBER MERCHANT, Being a Guide 
 for the use of Building Contractors, Surveyors, Builders, &c., comprising 
 useful Tables for all purposes connected with the Timber Trade, Marks of 
 Wood, Essay on the Strength of Timber, Remarks on the Growth of Timber, 
 &c. By W. Richardson. Fcap. 8vo, 3s. 6d. cloth. 
 "This handy manual contains much valuable information for the use of timber merchant?, 
 
 builders, foresters, and all others connected wiUi the growth, sale, and manufacture of timber." — 
 
 yountalof Forestry. 
 
 Timber Freight BooTc. 
 
 THE TIMBER MERCHANTS. SAW MILLER'S, AND 
 IMPORTER'S FREIGHT BOOK AND ASSISTANT. Comprising Rules, 
 Tables, and Memoranda relating to the Timber Trade. By William 
 Richardson, Timber Broker; together with a Chapter on *' Speeds of Saw 
 Mill Machinery," by M. Powis Bale, M.I. M.E., &c. i2mo, 3s. 6d. cl. boards. 
 
 "A very useful manual of rules, tables, and memoranda relating to the timber trade. We re- 
 commend it as a compendium of calculation to all timber measurers and merchants, and as supply- 
 ing a real want in the trade." — Buildhtg- News. 
 
 FacJcing-Case Mahers, Tables for, 
 
 PACKING-CASE TABLES ; showing the number of Super- 
 ficial Feet in Boxes or Packing-Cases, from six inches square and upwards. 
 By W. Richardson, Timber Broker. Third Edition. Oblong 4to, 3s. 6d. cl, 
 
 "Invaluable labour-saving tables." — frontnons'er, 
 "Will save much labour and calculation." — Grocer. 
 
 Superficial Measurement, 
 
 THE TRADESMAN'S GUIDE TO SUPERFICIAL MEA- 
 SUREMENT. Tables calculated from i to 200 inches in length, by i to ro8 
 inches in breadth. For the use of Architects, Surveyors, Engineers, Timber 
 Merchants, Builders, &c By James Hawkings. Third Edition. Fcap., 
 35. 6d. cloth. 
 " A useful collection of tables to facilitate rapid calculation of surfaces. The exact area of any 
 sarface of which the limits have been ascertained can be instantly determined. The book will be 
 found of the greatest utility to all engaged in building ooerations." — Scotsman. 
 
 " These tables will be foimd oFgreatassistancetoall who require to make calculations in super- 
 ficial measurement," — Enghsk Mechanic, 
 
 Forestry, 
 
 THE ELEMENTS OF FORESTRY. Designed to afford In- 
 formation concerning the Planting and Care of Forest Trees for Ornament or 
 Profit, with Suggestions upon the Creation and Care of Woodlands. By F. B, 
 Hough, Large crown 8vo, los. cloth. 
 
 Timber Importer's Guide, 
 
 THE TIMBER IMPORTER 'S, TIMBER MERCHANT'S AND 
 BUILDER'S STANDARD GUIDE. By Richard E. Grandy. Compris- 
 ing an Analysis of Deal Standards, Home and Foreign, with Comparative 
 Values and Tabular Arrangements for fixing Nett Landed Cost on Baltic 
 and North American Deals, including all intermediate Expenses, Freight, 
 Insurance, &c. &c. Together with copious Information for the Retailer and 
 Builder. Third Edition, Revised, lamo, cs. cloth limp. 
 
 " Everything it pretends to be : built up graduallj', it leads one from a forest to a treenail, and 
 throws in, as a makeweight, 3 host of material concerning bricks, columns, cisterns, Sic"—Eng^lish 
 
MARINE ENGI NEERING, NAVIGA TION, etc, 21 
 
 MARINE ENGINEERING, NAVIGATION, etc. 
 
 Chain Cables* 
 
 CHAIN CABLES AND CHAINS. Comprising Sizes and 
 Curves of Links, Studs, &c., Iron for Cables and Chains, Chain Cable and 
 Chain Making, Forming and Welding Links, Strength of Cables and Chains, 
 Certificates for Cables, Marking Cables, Prices of Chain Cables and Chains, 
 Historical Notes, Acts of Parliament, Statutory Tests, Charges for Testing, 
 List of Manufacturers of Cables, &c. &c. By Thomas W. Traill, F.E.R.N., 
 M. Inst. C.E., Engineer Surveyor in Chief, Board of Trade, Inspector of 
 Chain Cable and Anchor Proving Establishments, and General Superin- 
 tendent, Lloyd's Committee on Proving Establishments. With numerous 
 Tables, Illustrations and Lithographic Drawings, Folio, £z zs. cloth, 
 bevelled boards. 
 
 * ' It contaios a vast amount of valuable Informatloii, N'othlngr seems to be wanting to make it 
 a complete and standard work of reference on the subject." — Nauiicat Magazine. 
 
 ISIarine Engineering, 
 
 MARINE ENGINES AND STEAM VESSELS (A Treatise 
 on). By Robert Muhray, C.E. Eighth Edition, thoroughly Revised, with 
 considerable Additions by the Author and by George Carlisle, C.E., 
 Senior Surveyor to the Board of Trade at Liverpool, izmo, 5s, cloth boards. 
 " Well adapted to give the young steamship engineer or marme engine and boiler maker a 
 general hitroduction into his practical work." — Alechanical World, 
 
 " We feel sure that this thoroughly revised edition will continue to be as popular in the future 
 as it has been in the past, as, for its size, it contains more useful information than any similar 
 treatise. " — Industries. 
 
 The information given is both sound and sensible, and well qualified to direct young sea- 
 going hands on the straight road to the extra chiefs cert fi cite. Most useful to survejors, 
 inspectors, draughtsmen, and all young engineers who take an interest in their profession." — 
 
 Glasgow Herald. 
 " An indispensable manual for the student of marine engineering." — Liverpool Mercury. 
 
 Focket-IBooTcfor Naval Architects and Shipbuilders^ 
 
 THE NAVAL ARCHITECT'S AND SHIPBUILDER'S 
 POCKET-BOOK of Formula, Rules,and Tables,and MARINE ENGINEER'S 
 AND SURVEYOR'S Handy Book 0/ Reference. By Clement Mackrow, 
 Member of the Institution of Naval Architects, Naval Draughtsman. Fourth 
 Edition, Revised. With numerous Diagrams, &c. Fcap., 12s. 6d. strongly 
 bound in leather. 
 *' Will be found to contain the most useful tables and formulas required by shipbuilders, carefull> 
 
 collected from the best authorities, and put together in a popular and simple form."— £ngzneer. 
 " The professional shipbuilder has now, in a convenient and accessible form, reliable data foi 
 
 solving many of the numerous problems that present themselves in the course of his work." — Iron. 
 "There is scarcely a subject on which a naval architect or shipbuilder can require to refresh 
 
 his memory which will not be found within the covers of Mr. Mackrow's book." — English Mechanic. 
 
 BocTcet-BooTc for Marine Engineers, 
 
 A POCKET-BOOK OF USEFUL TABLES AND FOR^ 
 MULM FOR MARINE ENGINEERS. By Frank Proctor, A.I.N.A. 
 Third Edition. Royal 32mo, leather, gilt edges, with strap, 4s. 
 
 "We recommend it to our readers as going far to supply a long-felt want." — Naval Science. 
 "A most useful companion to all marine engineers." — untied Service Gazette. 
 
 Introduction to 3Iarine Engineering. 
 
 ELEMENTARY ENGINEERING : A Manual for Young Marine 
 Engineers and Apprentices. In the Form of Questions and Answers on 
 Metals, Alloys, Strength of Materials, Construction and Management of 
 Marine Engines and Boilers, Geometry, &c. &c. With an Appendix of Useful 
 Tables. By John Sherren Brewer, Government Marine Surveyor, Hong- 
 kong. Small crown 8vo, 2s. cloth. 
 
 " Contains much valuable information for the class for whom it is intended, especially in the 
 chipters on the management of boilers and eng'-nes."—Naiilical Magazine. 
 
 '■ A useful introduction to the more elaborate text hooks."—Scotsman. 
 
 *' To a student who has the requisite desire and resolve to attain a thorough knowledge, Mr. 
 Brewer offers decidedly useful iielp."— A ihenteum. 
 
 Navigation. 
 
 PRACTICAL NAVIGATION. Consisting of The Sailor's 
 Sea-Book, by James Greenwood and W. H. Rosser ; together with the 
 requisite Mathematical and Nautical Tablesfor the Working of the Problems, 
 by Henry Law, C.E,, and Professor J. R. Young. Illustrated, izmo, 75, 
 strongly half-bound. 
 
CROSBY LOCKWOOD &- SON'S CATALOGUE, 
 
 MINING AND METALLURGY. 
 
 Metalliferous Mining in the United Kingdom, 
 
 BRITISH MINING : A Treatise on the History. Discovery, Practical 
 Development, and Future Erospects of Metalliferotts Mines in the United King' 
 dom. By Robert Hont, F.R.S., Keeper of Mining Records; Editor oi 
 " Ure's Dictionary of Arts, Manufactures, and Mines, &c. Upwards of 950 
 pp., with 230 Illustrations. Second Edition, Revised, Super-royal 8vo, 
 £'i 25. cloth. 
 
 " One of the most valuable works of reference of modern times. Mr. Hunt, as keeper of mining 
 records of the United Kingdom, has had opportunities for such a task not enjoyed by anyone else» 
 and has evidently made the most of them. . . . The language and style adopted are good, and" 
 the treatment of'^the varioKs subjects laborious, conscientious, and scientific." — En^neering: 
 
 "The book is, in fact, a treasure-house of statistical information on mining subjects, and we; 
 know of no other work embodying so great a mass of matter of ihis kind. Were this the only 
 merit of Mr. Hunt's volume, it would be sufficient to render it indispensable in this library oi 
 everyone interested in the development of the mining and metallurgical mdustries of this country.' 
 — Athenau}n. 
 
 _ " A mass of information not elsewhere available, and of the greatest value to those who may 
 be interested in our great mineral industries." — Euf^nctr. 
 
 "A sound, business-like collection of interesting facts. . . . The amount of Informatioai 
 Mr. Hunt h2is brought together is enonnous. . . . The volume appears likely to convey more 
 fcistruction upon the subject than any work hitherto published." — Aiming yournal. 
 
 Colliery Management, 
 
 THE COLLIERY MANAGER'S HANDBOOK: A Compre- 
 hensive Treatise on the Laying-out and Working of Collieries, Designed as 
 a Bock of Reference for Colliery Managers, and for the Use of Coal-Mining 
 Students preparing for First-class Certificates. By Caleb Pamely, Mining 
 Engineer and Surveyor; Member of the North of England Institute off 
 Mining and Mechanical Engineers ; and Member of the South Wales Insti- 
 tute or Mining Engineers, With nearly 500 Plans, Diagrams, and other 
 Illustrations. Medium 8vo, about 600 pages. Price j^i 55, strongly bound. 
 
 [Just piiblishe(3^ 
 
 Coal and Iron, 
 
 THE COAL AND IRON INDUSTRIES OF THE UNITED 
 
 KINGDOM, Comprising a Description of the Coal Fields, and of the 
 Principal Seams of Coal, with Returns of their Produce and its Distribu- 
 tion, and Analyses of Special Varieties. Also an Account of the occurrence 
 of Iron Ores in Veins or Seams ; Analyses ot each Variety ; and a History of 
 the Rise and Progress of Pig Iron Manufacture. By Richard Meade, Assistant 
 Keeper ot Mining Records. With Maps. 8vo, £1 8s. cloth. 
 
 "The book is one which must find a place on the shelves of all Interested In coal and IroD 
 production, and in the iron, steel, and other metallurgical industries," — Engitieer. 
 
 " Of this book we may unreservedly say that it is the best of its class which we have ever met. 
 . . A book of reference which no one engaged in the iron or coal trades should omit from his 
 library." — /ran and Coal Trades Review. 
 
 JProspecting for Gold and other Metals, 
 
 THE PROSPECTOR'S HANDBOOK: A Guide for the Pro- 
 spector and Traveller in Search of Metal-Bearing or other Valuable Minerals. 
 By J. W. Anderson, M.A. (CambJ, F.R.G.S., Author of "Fiji and New 
 Caledonia." Fifth Edition, thoroughly Revised and Enlarged. Smali 
 crown 8vo, 35. 6d. cloth. 
 
 " Will supply a much felt want, especially amon^ Colonists, in whose way are so often thrown 
 many mineralogical specimens the value of which it is difficult to determine,' — En^'nerr. 
 
 "How to find commercial minerals, and how to identify them when they are ioUnd, are the 
 leading points to which attention Ls directed. The author has managed to pack as muchpracticaJ 
 detail mto his pages as would supply material for a book three times its size." — Mining 'Journals 
 
 Mining Notes and Forrnulce, 
 
 NOTES AND FORMULAE FOR MINING STUDENTS. By 
 John Herman Merivale, M.A., Certificated Colliery Manager. Professor of 
 Mining in the Durham College of Science, Newcastle-upon-Tyne. Third 
 Edition, Revised and Enlarged. Small crown 8vo, 2s. 6rf. cloth. 
 " Invaluable to anyone who is working up for an examination on mining subjects." — Caal and 
 Iron Trades Rcmtw. 
 
 " The author has done his work in an exceedingly creditable manner, and has produced a book 
 that will be of service to students, and those who are practically engaged in mining operations.'' — 
 Engineer, 
 
 " A vast amount of technical matter of the utmost value to mining engineers, and of consider* 
 able interest to students," — Schoolmaster. 
 
MINING AND M ET A LL URG Y. 23 
 
 Explosives* 
 
 A HANDBOOK ON MODERN EXPLOSIVES. Being a 
 Practical Treatise on the Manufacture and Application of Dynamite, Gun- 
 Cotton, Nitro-Glycerine and other Explosive Compounds. Including the 
 Manufacture of Collodion-Cotton. By M. Eissler, Mining Engineer and 
 Metallurgical Chemist, Author of " The Metallurgy of Gold," &c. With 
 about 100 Illustrations. Crown 8vo, ids. 6d. cloth, 
 "Useful not only to the miner, but also to officers of both services to whom blasting and the 
 
 use of explosives generally may at any time become a necessary auxiliary. " — Nature. 
 
 " A veritable mine of information on the subject of explosives employed for Military, mining 
 
 a:.d blasting purposes." — Army and Na-oy Gazette. 
 
 " The book is clearly ivritten. Taken as a whole, we consider it an excellent little bonk a-^d 
 
 one that should be found of great service to miners and others who are engaged in work requiring 
 
 the use of explosives."— v4/Ai«t7«»/. 
 
 Goldf Metallurgy of, 
 
 THE METALLURGY OF GOLD : A Practical Treatise on the 
 Metallurgical Treatment of Gold-bearing Ores. Including the Processe s of 
 Concentration and Chlorination, and the Assaying, Melting and Refining of 
 Gold. By M. Eissler, Mining Engineer and Metallurgical Chemist, formerly 
 Assistant Assayer of the U. S. Mint, San Francisco. Third Edition, Revised 
 and greatly Enlarged. With 187 Illustrations, Crown 8ve, 125, 6d. cloth. 
 
 " This book thoroughly deserves its title of a ' Practical Treatise.' The whole process of gold 
 millmg, from the breaking of the quartz to the assay of the bullion, is described in clear and 
 orderly narrative and with much, but not too much, fulness of detail." — Saturday Revtevi. 
 
 " The work is a storehouse of information and valuable data, and we strongly recommend it to 
 aU professional men engaged in the gold-mining industry," — Mining journal 
 
 Silver, Metallurgy of, 
 
 THE METALLURGY OF SILVER : A Practical Treatise on 
 the Amalgamation, Roasting and Lixiviation of Silver Ores, Including the 
 Assaying, Melting and Refining of Silver Bullion. By M. Eissler, Author 
 of "The Metallurgy of Gold '' Second Edition, Enlarged, With 150 Illus- 
 trations. Crown 8vo, los. 6d. cloth. {Just published. 
 
 "A practical treatise, and a technical work which we are convinced will supply a long-felt want 
 amongst practical men,, and at the same time be of value to students and others indirectly connected 
 with tne industries." — Mitiiiig- J^oicntal. 
 
 "From first to last the book is thoroughly sound and reliable." — Colliery Guardian. 
 
 "For chemists, practical miners, assayers and investors alike, we do not know of any work 
 on the subject so handy and yet so comprehensive."— C/aj^czv Herald. 
 
 Silver-Lead, Metallurgy of. 
 
 THE METALLURGY OF ARGENTIFEROUS LEAD: A 
 Practical Treatise on the Smelting of Silver-Lead Ores and the Refining of 
 Lead Bullion. Includiug Reports on various Smelting Establishments and 
 Descriptions of Modern Furnaces and Plants in Europe and America. By 
 M. Eissler, M.E., Author of "The Metallurgy of Gold," &c. Crown 8vo. 
 400 pp., with numerous Illustrations, 12s. 6d. cloth. U^ist published. 
 
 Metalliferous Minerals and Mining, 
 
 TREATISE ON METALLIFEROUS MINERALS AND 
 MINING. By D, C. Davies, F.G.S., Mining Engineer, &c., Author of "A 
 Treatise on Slate and Slate Quarrying." Illustrated with numerous Wood 
 Engravings. Fourth Edition, carefully Revised. Crown 8vo, 12s. 6d. cloth. 
 
 " Neither the practical miner nor the general reader interested in mines canhave a better book 
 for his companion and his guide." — Muting- jFournal. IMi'tifig World, 
 
 •' We arc doing our readers a service in calling their attention to this valuable work. "— . 
 
 "Asa history of the present state of mining throughout tne world this book has a rezJ valu e, 
 and it supplies an actual v/axA."—Athenteufn. 
 
 JSarthy Minerals and Mining, 
 
 A TREATISE ON EARTHY &- OTHER MINERALS AND 
 MINING. ByD. C. Davies, F.G.S. Uniform with, and forming a Com- 
 panion Volume to, the same Author's *' Metalliferous Minerals and Mining." 
 With 76 Wood Engravings. Second Edition. Crown 8vo, 12s. 6d. cloth. 
 " We do not remember to have met with any English- work on mining matters that contains 
 
 the same amount of information packed in equally convenient {otm."—Aradetny. 
 
 " We should be inclined to rank it as among the very best of the handy technical and trades 
 
 manual which have recently appeared."— ^/-iftVA Quarterly Review, 
 
24 CROSBY LOCK WOOD &* SON'S CATALOGUE, 
 
 Mineral Surveying and Valuing, 
 
 THE MINERAL SURVEYOR AND VALUER'S COMPLETE 
 
 GUIDE, comprising a Treatise on Improved Mining Surveying and the Valtior 
 Hon of Mining Properties^ with New Traverse Tables. By Wm. Lintern, 
 Mining and Civil Engineer. Third Edition, with an Appendix on " Magnetic 
 and Angular Surveying," with Records of the Peculiarities of Needle Dis- 
 tuobances. With Four Plates of Diagrams, Plans, &c. i2mo, 4s. cloth. 
 " Mr. Lintern's book forms a valuable and thoroughly trustworthy guide."— />w( and Coal 
 Trades Revie-w. 
 
 " This new edition must be of the highest value to colliery surveyors, proprietors and mana- 
 gers." — Coiliery Guardian. 
 
 Asbestos and its Uses, 
 
 ASBESTOS : Its Properties, Occurrence and Uses. With some 
 Account of the Mines of Italy and Canada. By Robert H. Jones. With 
 Eight Coliotype Plates and other Illustrations. Crown 8vo, 12s. 6d. cloth. 
 
 " An interesting- and invaluable work." — Colliery Guardian. 
 
 " We counsel our readers to get this exceedingly interesting work for themselves ; they will 
 fiud in it much that is suggestive, and a great deal that is of immediate and practical usefulness."— 
 Guilder. 
 
 " A valuable addition to the architect's and engineer's \\brd.ry. "'—Bitildittff News. 
 
 Underground dumping Machinery, 
 
 MINE DRAINAGE. Being a Complete and Practical Treatise 
 on Direct-Acting Underground Steam Pumping Machinery, with a Descrip- 
 tion of a large number of the best known Engines, their General Utility and 
 the Special Sphere of their Action, the Mode of their Application, and 
 their merits compared with other forms of Pumping Machinery. By Stephen 
 MiCHELL. 8vo, 15s. cloth. 
 "Will be highly esteemed by colliery owners and lessees, mining engineers, and students 
 
 generally who require to be acquainted with the best means of securing the drainage of mines. It 
 
 is a most valuable work, and stands almost alone in the literature of steam pumping machinery."— 
 
 Colliery Guardian. 
 _ " Much valuable information is given, so that the book Ls thoroughly worthy of an extensive 
 
 circulation cimongst practical men and purchasers of machinery." — Mining Joiir>ial. 
 
 Mining Tools, 
 
 A MANUAL OF MINING TOOLS. For the Use of Mine 
 Managers, Agents, Students, &c. By William Morgans, Lecturer on Prac- 
 tical Mining at the Bristol School of Mines. i2mo, 2s. bd. cloth limp. 
 ATLAS OF ENGRAVINGS to Illustrate the above, contain- 
 ing 235 Illustrations of Mining Tools, drawn to scale. 4to, 4s. 6d. cloth. 
 "StudenLs in the science of mining, and overmen, captains, managers, and viewers may gain 
 practical knowledge and useful hints by the study of Mr. Morgans' manual."— C(j^/«o' Guardian. 
 
 "A valuable work, which will tend materially to improve our mining literature."— ^i«w(f 
 ^ourttal. 
 
 €oal Mining^ 
 
 ■ COAL AND COAL MINING: A Rudimentary Treatise on. By 
 the late Sir Warington W. Smyth, M.A., F.R.S., &c.. Chief Inspector of the 
 Mines of the Crown. Seventh Edition, Revised and Enlarged. With 
 numerous Illustrations. i2mo, 4s. cloth boajds. 
 '* As an outline is given of every known coal-field in this and other countries, as well as of the 
 
 principal methods of working, the nook will doubtless interest a very large number of readers. "— 
 
 Mining journal. 
 
 Subterraneous ■ Surveying, 
 
 SUBTERRANEOUS SURVEYING, Elementary and Practical 
 Treatise on, with and without the Magnetic Needle. ByTHOMAS Fenwick, 
 Surveyor of Mines, and Thomas Baker, C.E. lUust. i2mo, 3s, cloth boards. 
 
 Granite Quarf*ying, 
 
 GRANITES AND OUR GRANITE INDUSTRIES. By 
 George F. Harris, F.G.S., Membre de la Soci6t6 Beige de Gdologie, Lec- 
 turer on Economic Geology at the Birkbeck Institution, &c. With Illustra- 
 tions. Crown 8vo, 2S. 6d. cloth. 
 "A dearly and well-written manual for persons engaged or interested In the granite industry.' 
 
 •'^ An interesting work, which will be deservedly esteemed."— Colliery Guardiatt. 
 An exceedinefly interesting and valuable monograph on a subject which has hitherto received 
 unaccountably httle attention m the shape of systemaiic Uttrary treatment."— 5f<7«ij^ Leader 
 
ELECTRICITY, ELECTRICAL ENGINEERING, etc. 25 
 
 ELECTRICITY ELECTRICAL ENGINEERING, etc. 
 
 Electrical Engineering, 
 
 THE ELECTRICAL ENGINEER'S POCKET-BOOK OF 
 
 MODERl^ RULES, FORMULA, TABLES AND DATA. By H. R. 
 Kempe, M.Inst.E.E., A.M.lDst C.E., Technical Officer Postal Telegraphs, 
 
 Author of "A Handbook of Electrical Testing," &c. With numerous Illus- 
 trations, royal 32mo, oblong, 5s. leather. IJust published. 
 
 " There is very little in the shape of formulse or data which the electrician is likely to want 
 in a hurry which cannot be found in its pag^es," — Practical Sn^neer, 
 
 "A very useful book of reference for daily use in practical electrical engineering and its 
 various applications to the industries of the present day." — Iron. 
 
 " It is the best book of its kicd." — Electrical Eiigimer. 
 
 "The Electrical Engineer's Pocket-Book is a good one." — Electrician. 
 
 "Strongly recommended to those engaged in tne various electrical industries."— £^i^i'''"^'ai/ 
 Hevirw, 
 
 Electric Lighting, 
 
 ELECTRIC LIGHT FITTING : A Handbook for Working 
 Electrical Engineers, embodying Practical Notes on Installation Manage- 
 ment. By John W. Urquhart, Electrician, Author of " Electric Light,'' Sec. 
 With numerous Illustrations, crown 8vo, 5s. cloth. [Jws( published. 
 
 "This volume deals with what may be termed the mechanics of electric lighting, and is 
 addressed to men who are already engaged in the work or are training for it. The work traverses 
 a. ere=it deal of ground, and may be read as a sequel to the same author's useful work on ' Electric 
 Light,' " — Electrician. 
 
 " This is an attempt to state in the simplest language the precautions which should be adopted 
 in instal ing- the electric light, and to g'lve information,K)r the guidance of those who have to run 
 the plant when installed. The book is well worth the perusal of the workmen for whom it is 
 wiitten." — Electrical Review. 
 
 ' Eminently practical and useful. . . . Ought to be in the hands of everyone in charge of 
 an electric light plant." — Electrical F.yigineer. 
 
 " A really capital book, which we have no hesitation in recommending to the notice of working 
 electricians and electrical engineers." — Meckamcal IVorld. 
 
 Electric Light, 
 
 ELECTRIC LIGHT : Its Production and Use. Embodying Plain 
 Directions for the Treatment of Dynamo- Electric Machines, Batteries, 
 Accumulators, and Electric Lamps, By ]. W. Urquhart, C.E., Author of 
 "Electric Light Fitting," &c. Fourth Edition, Revised, with Large Additions 
 and 145 Illustrations. Crown 8vo, 75. 6d. cloth. [Just published. 
 
 *' The book is by far the best that we have yet met with on the subject." — Athenezitm. 
 
 "It is the only work at present available which gives, in language intelligible for the most part 
 Co the ordinary reader, a general but concise history of the means which have been adopted up to 
 the present time in producing the electric light." — Metropolitan. 
 
 "The book contains a general account of the means adopted in producing the electric light, 
 not only as obtained from voltaic or galvanic batteries, but treats at length of the dynamo-electric 
 machine in several of its forms." — Colliery Gjiardian. 
 
 ^Construction of Dynamos, 
 
 DYNAMO CONSTRUCTION : A Practical Handbook for the Use 
 of Engineer Constructors and Electricians in Charge. With Examples of 
 leading English, American and Continental Dynamos and Motors. By J. W. 
 Urquhart, Author of " Electric Light," &c. Crown 8vo,-75. 6d. cloth. 
 
 {Just published. 
 
 'The author has produced a bonk for which a demand has long existed. The subject is 
 treated in a thoroughly practical manner." — Mechanical World. 
 
 Dynamic Electricity) and Magnetism, 
 
 THE ELEMENTS OF DYNAMIC ELECTRICITY AND 
 MAGNETISM. By Philip Atkinson, A.M., Ph.D., Crown 8vo. 400 pp. 
 With 120 Illustrations. los. 6d. cloth. \_Just published. 
 
 Text Booh of Electricity, 
 
 THE STUDENTS TEXT-BOOK OF ELECTRICITY. By 
 Henry M. Noad, Ph.D., F.R.S., F.C.S. New Edition, carefully Revised, 
 With an Introduction and Additional Chapters, by W. H. Preece, M.I.C.E., 
 Vice-President of the Society of Telegraph Engineers, &c. With 470 Illustra- 
 tions. Crown 8vo, 12s. 6d. cloth. 
 
 'We can recommend Dr. Noad's book for clear style, great range of subject, a good index 
 <1 a plethora of woodcuts. Such collections as the present are indispensable. ' — Atkentxum.. 
 "An admirable text book for every student — begmner or advanced — of electricity." — 
 ftn^neering. 
 
26 CROSBY LOCKWOOD &* SON*S CATALOGUE. 
 
 Electric Idghting* 
 
 THE ELEMENTARY PRINCIPLES OF ELECTRIC LIGHT ^ 
 
 ING. By Alan A. Campbell Swinton, Associate I.E.E. Second Edition, 
 Enlarged and Revised. With i6 Illustrations. Crown 8vo, is. 6rf. cloth. 
 "Anyone who desires a short and thoroughly clear exposition of the elementary principles of 
 electric-lig-hting cannot do better than read this little •9iQt)s.."^Bradfor{i Obset~ver, 
 
 Electricity, 
 
 A MANUAL OF ELECTRICITY: Including Galvanism, Mag •■ 
 netism, Dia-Magnetism, Electro-Dynamics, Magno-Electricity, and the Electric 
 Telegraph. By Henrt M. Noad, Ph.D., F.R.S., F.C.S. Fourth Edition, 
 With 500 Woodcuts. 8vG, £"1 4s. cloth, 
 
 "It is worthy of a place in the library of every public institution."— jWwjijj^ ^oui^tcU, 
 
 Dijfiamo Construction, 
 
 HO W TO MAKE A DYNAMO : A Practical Treatise for Amateurs, 
 Containing numerous Illustrations and Detailed Instructions for Construct- 
 ing a Small Dynamo, to Produce the Electric Light. By Alfred Crofts. 
 Third Edition, Revised and Enlarged. Crown 8vo,2S. cloth. 
 "The instructions given in this unpretentious little book are sufficiently clear and explicit to 
 
 enable any amateur mechanic possessed of average skill and the usual tools to be found in au 
 
 amateur's workshop, to build a practical dynamo machine." — ElectHcian. 
 
 NATURAL SCIENCE, etc. 
 
 Pneumatics and Acoustics, 
 
 PNEUMATICS : including Acoustics and the Phenomena of Wind 
 Currents, for the Use of Beginners.' By Charles Tomlinson, F.R.S. 
 F.C.S. , &c. Fourth Edition, Enlarged, izmo, is. 6d. cloth. 
 
 " Beginners in the study of this Important application of science could not have a better manual, " 
 — Scotsman. " A valuable and suitable text-book for students of Acoustics and the Fheno- 
 
 mtiiia of Wind Currents." — Schoolfftaster, 
 
 Conchology, 
 
 A MANUAL OF THE MOLLUSC A : Being a Treatise on Recent 
 and Fossil Shells. By S. P. Woodward, A.L.S., F.G.S., late Assistant 
 Palaeontologist in the British Museum. With an Appendix on Recent and 
 Fossil Conchological Discoveries, by Ralph Tate, A.L.S., F.G.S. Illustrated 
 by A. N. Waterhouse and Toseph Wilson Lowry. With 23 Plates and 
 upwards of 300 Woodcuts. Reprint of Fourth Ed., 1880, Cr. 8vo, y$. 6d. cl. 
 " A most valuable storehouse of conchological and geological information."'— ^irzc^tcc Gossip. 
 
 Geology, 
 
 RUDIMENTARY TREATISE ON GEOLOGY, PHYSICAL 
 
 AND HISTORICAL. Consisting of "Physical Geology," which sets forth 
 the leading Principles of the Science; and "Historical Geology," which 
 treats of the Mineral and Organic Conditions of the Earth at each successive 
 epoch, especial reference being made to the British Series of Rocks. By 
 Ralph Tate, A.L.S., F.G.S., &c. With 250 Illustrations. lamo, 5s. cloth. 
 " The fulness of the matter has elevated the book into a manucil. Its Information Is exhaustive 
 and well 3.Tnnseii."^^chool Soard Chronicle, 
 
 Geology and Genesis, 
 
 THE TWIN RECORDS OF CREATION: or, Geology and 
 Genesis : their Perfect Harmony and Wonderful Coicord, By George W, 
 Victor le Vaux. Numerous Illustrations. Fcap. 8vo, 5s. cloth. 
 " A valuable contribution to the evidences of Revelation, and disposes very conclusively of the 
 arguments of those who would set God's Works against God's Word." — The Rock, 
 
 The Constellations, 
 
 STAR GROUPS: A Student's Guide to the Constellations. By 
 J. Ellard Gore, F.R.A.S., M.R.I. A., &c., Author of "The Scenery of the 
 Heavens." With 30 Maps. Small 4to, 5s. cloth, silvered, [Jitst published. 
 
 Astronomy. 
 
 ASTRONOMY. By the late Rev. Robert Main, M. A., F.R.S. . 
 formerly Radcliffe Observer at Oxford. Third Edition, Revised and Cor- 
 rected to the present time, by W, T. Lynn, B.A., F.R.A.S. i2mo, 2s. cloth. 
 "A sound and sunple treatise, very carefully edited, and a capital book tor beginners."— 
 KnoTvledg:'.. [Cional Times. 
 
 I' Accurately brought down to the requirements of the present time by Mr. Lynn." — £tiuca- 
 
NATURAL SC IENCE, etc, 27 
 
 DH. LARDNER'S COURSE OF NATURAL PHILOSOPHY. 
 
 THE HANDBOOK OF MECHANICS. Enlarged and almost re- 
 
 written by Benjamin Loewy, F.R.A.S. With 378 Illustrations. Post 8vo, 
 
 6s. cloth. 
 
 "The perspicuity of the orl^nal has beea retained, and chapters which had become obsolete 
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 physics to the industricd arts, and to the practical business of h(e."— A/^iKiKir journal. 
 
 "Mr. Loewy has carefully revised the book, and brought it up to modem requirements." — 
 Nature. 
 
 "Natural philosophy has had few exponents more able or better skilled in the art of popu- 
 larising the subject than Dr. Lardner ; and Mr. Loewy is doing good service in fitting this treatise, 
 and the others of the series, for use at the present t]sa.e."—Scets}Tian. 
 
 THE HANDBOOK OF HYDROSTATICS AND PNEUMATICS. 
 New Edition, Revised and Enlarged, by Benjamin Loewy, F.R.A.S. With 
 
 236 Illustrations. Post 8vo, 5s. cloth. 
 
 "For those 'who desire to attain an accurate knowledge of physical science without the pro- 
 found methods of mathematical investigation,' this work is not merely intended, but well adapted." 
 —Chemical News. 
 
 " The volume before us has been carefully edited, augmented to nearly twice the bulk of the 
 former edition, and all the most recent matter has been added. . . . It is a valuable text-book." 
 — Nature, 
 
 "Candidates for pass examinations will find it, we think, specially suited to their requirements." 
 English Mechanic. 
 
 THE HANDBOOK OF HEAT. Edited and almost entirely re- 
 written by Benjamin Loewy, F,R.A.S., &c. 117 Illustrations. PostSvo, 6s. 
 cloth. 
 
 " The style Is always clear and precise, and conveys instruction without leaving any cloudiness 
 or lurking doubts behind." — Engineering: 
 
 " A most exhaustive book on the subject on which It treats, and is so arranged that It can be 
 
 understood by all who desire to attain an accurate knowledge of physical science Mr, 
 
 Loewy has included all the latest discoveries in the varied laws and effects of heat." — Standard, 
 
 "A complete and bandy text-lsook for the use of students and general readers." — English 
 Mechanic. 
 
 THE HANDBOOK OF OPTICS. ByDioNYSius Lardner.D.C.L., 
 
 formerly Professor of Natural Philosophy and Astronomy in University 
 College, London. New Edition. Edited by T. Olver Harding, B.A. Lond., 
 of University College, London. With 298 Illustrations. Small 8vo, 448 
 pages, 5s. cloth. 
 
 "Written by one of the ablest English scientific writers, beautifully and elaborately illustrated." 
 Mechanitts Magazine, 
 
 THE HANDBOOK OF ELECTRICITY, MAGNETISM, AND 
 .4COt7Sr/CS. By Dr. Lardner. Ninth Thousand. Edit, by George Carey 
 Foster, B.A., F.C.S. With 400 Illustrations. Small 8vo, 5s. cloth, 
 " The book could not have been entrusted to anyone better calculated to preserve the terse and 
 
 lucid style of Lardner, while correcting his errors and bringing up his work to the present state o4 
 
 scientific knowledge." — Popular Science Revieiu. 
 
 THE HANDBOOK OF ASTRONOMY. Forminga Companion 
 to the " Handbook of Natural Philosophy.'' By Dionysius Lardner, D.C.L.» 
 formerly Professor of Natural Philosophy and Astronomy in University 
 College, London. Fourth Edition. Revised and Edited by Edwin Dunkin, 
 F.R.A.S., Royal Observatory, Greenwich. With 38 Plates and upwards of 
 100 Woodcuts. In One Vol., small 8vo, 550 pages, gs. 6d. cloth. 
 
 "Probably no other book contains the same amount of information in so compendious and well- 
 arranged a form — certainly none at the price at which this is offered to the public." — Athenau-m. 
 
 '•We can do no other than pronounce this work a most valuable manual of astronomy, and we 
 strongly recommend it to all who wish to acquire a general — but at the same time correct — acquaint- 
 ance with this sublime science." — Quarterly Journal of Science, 
 
 "One of the most deservedly popular books on the subject . . , We would recommend not 
 only the student of the elementary principles of the science, but he who aims at mastering the 
 higher and mathematical branches of astronomy, not to be without this work beside \am.."— Practi- 
 cal Magazine. 
 
 J)r* Lardner^s Electric Telegraph. 
 
 THE ELECTRIC TELEGRAPH. By Dr. Lardner. Re- 
 vised and Re-writfen by E. B. Bright, F.R.A.S. 140 Illustrations, Small 
 8vo, 2S. 6d. cloth. 
 * One of the most readable books extant on the Electric Telegraph."— £;;^/zj^ Mechanic. 
 
28 CROSBY LOCKWOOD 6- SON'S CATALOGUE. 
 
 DR. LARDNER'S MUSEUM OF SCIENCE AND ART. 
 
 THE MUSEUM OF SCIENCE AND ART. Edited by 
 DiONYSius Lardner, D.C.L-t formerly Professor of Natural Philosophy and 
 Astronomy in University College, London. With upwards of 1,200 Engrav- 
 ings on Wood. In 6 Double Volumes, £1 is., in a new and elegant cloth bind- 
 ing ; or handsomely bound in half-morocco, 31s, Sd. 
 
 *** Opinions of the Press. 
 
 " This series, besides affording popular but sound instruction on scientific subjects, with which 
 the humblest man in the country ought to be acquainted, also undertakes that teaching of ' Com- 
 mon Things ' which every well-wisher of his kind is anxious to promote. Many thousand copies of 
 this serviceable publication have been printed, in the belief and hope that the desire for Instruction 
 and improvement widely prevails ; and we have no fear that such enlightened faith will meet with 
 disappointment."— Tirnes, 
 
 " A cheap and interesting publication, alike Informing and attractive. The papers combine 
 subjects of importance and great scientific knowledge, considerable inductive powers, and a 
 popular style of treatment."— ii/erffl/(7r. 
 
 "The 'Museum of Science and Art' is the most valuable contribution tKat has ever been 
 caade to the Scientific Instruction oi every class of society." — Sir DAVID BREWSTER, in the 
 North British Revieiu. 
 
 " Whether we consider the liberality and beauty of the illustrations, the charm of the writing, 
 or the durable interest of the matter, we must express our belief that there is hardly to be found 
 among the new books one that would be welcomed by people of so many ages and classes as a 
 valuable present."— £ara»«w«r. 
 
 *^^.* Separate books formed from the above^ suitable fof Workmen's Libraries, 
 Science Classes, etc. 
 
 Common Things Explained, Containing Air, Earth, Fire, Water, Time, 
 Man, the Eye, Locomotion, Colour, Clocks and Watches, &c. 233 Illus- 
 trations, cloth gilt, 5s. 
 
 The Microscope. Containing Optical Images, Magnifying Glasses, Origin 
 and Description of the Microscope, Microscopic Objects, the Solar Micro- 
 scope, Microscopic Drawing and Engraving, &c. 147 Illustrations, cloth 
 gilt, 2S, 
 
 Popular Qeology, Containing Earthquakes and Volcanoes, the Crust of 
 the Earth, &c, 201 Illustrations, cloth gilt, 2s. 6d. 
 
 Popular Fhysics, ContaininK Magnitude and Minuteness, the Atmo- 
 sphere, Meteoric Stones, Popular Fallacies, Weather Prognostics, the 
 Thermometer, the Barometer, Sound, &c. 85 Illustrations, cloth gilt, 25. 6d. 
 
 Steam and its Uses. Including the Steam Engine, the Locomotive, and 
 Steam Navigation. 89 Illustrations, cloth gilt, 22. 
 
 Fopidar Astronomy. Containing How to observe the Heavens — The 
 
 Earth, Sun, Moon, Planets, Light, Comets, Eclipses, Astronomical Influ- 
 ences, &c. 182 Illustrations, 4s. 6cJ. 
 
 The See and WJiite Ants : Their Manners and Habits. With Illustra- 
 tions of Animal Instinct and Intelligence, 133 Illustrations, cloth gilt, zs. 
 
 The Electric Telegraph Popularised. To render intelligible to all who 
 can Read, irrespective of any previous Scientific Acquirements, the various 
 forms of Telegraphy in Actual Operation. 100 Illustrations, cloth gilt, 
 IS. 64, 
 
 I>r, Lardner's School JEEanclhoohs, 
 
 NATURAL PHILOSOPHY FOR SCHOOLS. By Dr. Lardner. 
 328 Illustrations. Sixth Edition. One Vol., 3s. 6d. cloth. 
 
 " A very convenient class-book for junior students in private schools. It is Intended to convey, 
 in clear and precise terms, general notions of all the principal divisions of Physical Science."— 
 , British Quarterly Review. 
 
 ANIMAL PHYSIOLOGY FOR SCHOOLS. By Dr. Lardnef. 
 
 With 190 Illustrations. Second Edition, One Vol., 3s. 6d. cloth. 
 
 " Clearly written, well arranged, and exce'iently illustrated." — Gardefter's Chronicle, 
 
COUNTING-HOUSE WORK,TABLES, CALCULATORS, etc, 29 
 
 COUNTING-H OUSE WORK, TABLES, etc. 
 
 Introduction to business, 
 
 LESSONS IN COMMERCE, By Professor R. Gambaro, of 
 the Royal High Commercial School at Genoa. Edited and Revised by James 
 Gault, Professor of Commerce and Commercial Law in King's College, 
 London. Crown 8vo, price about 3s. 6rf. [Z/t the press. 
 
 Accounts for Manufacturers, 
 
 FACTORY ACCOUNTS: Their Principles and Practice. A 
 
 Handbook for Accountants and Manufacturers, with Appendices on the No- 
 menclature of Machine Details ; the Income Tax Acts ; the Rating of Fac- 
 tories ; Fire and Boiler Insurance ; the Factory and Workshop Acts, &c., 
 including also a Glossary of Terms and a large number of Specimen Rulings. 
 By Emile Garcke and J. M. Fells. Third Edition. Demy 8vo, 250 pages, 
 price 6s. strongly bound. 
 " A very interesting: description of the requirements of Factory Accounts. . . . the principle 
 
 of assimilating the Factory Accounts to the general commercial books is one which we thoroughly 
 
 agree 'vnth."— Accountants' ^oitrnal. 
 
 "There are few owners of Factories who would not derive great benefit from the peruSEi] 
 
 of thii; most admirable work." — Local Government Chronicle, 
 
 Foreign Commercial Correspondence. 
 
 THE FOREIGN COMMERCIAL CORRESPONDENT : Being 
 Aids to Commercial Correspondence in Five Languages— English, French, 
 German, Italian and Spanish. By Conrad E, Baker, Second Edition, 
 Revised. Crown 8vo, 3s. 6d. cloth. 
 ' ' Whoever wishes to correspond in all the languages mentioned by Mr. Baker cannot do better 
 
 than study this work, the materials of which are excellent and conveniently arranged." — Athentzutn. 
 "A careful examinaiiin has convinced us that it is unusually complete, well arranged and 
 
 reliable. The book is a thoroughly good one." — Schoolmaster. 
 
 Intuitive Calculations. 
 
 THE COMPENDIOUS CALCULATOR : or, Easy and Con- 
 cise Methods of Performing the various Arithmetical Operations required in 
 Commercial and Business Transactions, together with Useful Tables, By 
 D. O'GoRMAN. Corrected by Professor J. R, Young. Twenty-seventh Ed., 
 Revised by C. Norris. Fcap. 8vo, 25. 6d. cloth ; or, 3s. 6t/. half-bound. 
 " It would be difficult to exaggerate the usefulness of a book like this to everyone engaged in 
 
 commerce or manufacturing \n^astry."—ICnoTijledg^e. 
 
 " Supplies special and rapid methods for all kinds of calculations. Of great utility to persons 
 
 engaged in any kind of commercial transactions." — Scotstnan. 
 
 Modern Metrical Units and Systems. 
 
 MODERN METROLOGY : A Manual of the Metrical Units 
 and Systems of the Present Century. With an Appendix containing a proposed 
 English System. By Lowis D'A, Jackson, A.M.Inst.C.E., Author of *' Aid 
 to Survey Practice," &c. Large crown 8vo, 12s. 6d. cloth. 
 
 "The author has brought together much valuable and interesting information, . . , "We 
 cannot but recommend the work." — Nature. 
 
 ' ' For exhaustive tables of equivalent weights and measures of all sorts, and for clear demonstra- 
 tions of the effects of the various systems that have been proposed or adopted, Mr. Jackson's 
 treatise is without a rival." — Academy. 
 
 The Metric System and the British Standards, 
 
 A SERIES OF METRIC TABLES Jn which the British Stand- 
 ard Measures and Weights are compared with those of the Metric System at present 
 in Use on the Continent. By C. H. Dowling, C.E. 8vo, ios. 6d. strongly bound. 
 
 "Their accuracy has been certified by Professor Airy, the Astronomer-Royal." — Builder. 
 
 "Mr. Dowling's Tables are well put together as a ready-reckoner for the conversion of one 
 system into the oiAiex. "—AthenauTn, 
 
 Iron and Metal Trades^ Calculator. 
 
 THE IRON AND METAL TRADES' COMPANION. For 
 expeditiously ascertaining the Value ot any Goods bought or sold by Weight, 
 from IS. per cwt. to 112s. per cwt., and from one farthing per pound to one 
 shilling per pound. Each Table extends from one pound to 100 tons. To 
 which are appended Rules on Decimals, Square and Cube Root, Mensuration 
 oi Superficies and Solids, &c. ; also Tables of Weights of Materials, and other 
 Useful Memoranda. ByTnos. Downie. Strongly bound in leather, 396 pp., gs. 
 '• A most useful set of tables. . . . Nothing like them before e:sis,ted"~Butlding^ News. 
 "Although specially adapted to the iron and metal trades, the tables will be found useful in 
 every other business in which merchandise is bought and sold by weight,"— ifatVa'ty/ News. 
 
. 30 CROSBY LOCKWOOD S* SON'S CATALOGUE, 
 
 Calculator for Numbers and Weights Combined. 
 
 THE NUMBER, WEIGHT AND FRACTIONAL CALCU- 
 LATOR. Containing upwards of 250,000 Separate Calculations, showing at 
 a glance the value at 422 difierent rates, ranging from x^th of a Penny to 
 20s. each, or per cwt., and 3^20 per ton, of any number of articles consecu- 
 tively, from I to 470.— Any number of cwts., qrs., and lbs., from i cwt. to 470 
 cwts. — Any number of tons, cwts., qrs., and lbs., from i to 1,000 tons. By 
 William Chadwick, Public Accountant. Third Edition, Revised and Im- 
 proved. 8vo, price i8s., strongly bound for Office wear and tear. 
 *:^* This work is specially adapted for the Apportionment of Mileage Charges 
 
 for Railway Traffic, 
 
 tS" This comprehensive and entirely unique and original Calculator is adapted 
 
 for the use of Accountants and Auditors, Railway Companies, Canal Companies^ 
 
 Shippers, Shipping Agents, General Carriers, etc. 
 
 Ironfounders, Brassfounders, Metal Merchants, Iron Manufacturers Jronmon^ers, 
 
 Engineers, Machinists, Boiler Makers, Millwrights, Roofing, Bridge and Gtrdcr 
 
 Makers, Colliery Proprietors, etc. 
 
 Timber Merchants, Btiilders, Contractors, Architects, Surveyors, Auctioneers 
 
 Valuers, Brokers, Mill Owners and Manufacturers, Mill Furnishers, Merchants and 
 
 General Wholesale Tradesmen. 
 
 *^* Opinions of the Press. 
 
 "The book contains the answers to questions, and not simply a set of loeetilous puzzle 
 methods of arriving at results. It is as easy of reference for any answer or any number of answers 
 as a dictionary, and the references are even more quickly made. For making^ up accounts or esti- 
 mates, the book must prove invaluable to all who have any coiislderable quantity o£ calculations 
 ifivolving price and measure in any combination to do," — Enguteer, 
 
 "The most perfect work of the kind yet prepared." — Glasgow Herald. 
 
 Comprehensive Weight Calculator^ 
 
 THE WEIGHT CALCULATOR, Being a Series of Tables 
 upon a New and Comprehensive Plan, exhibiting at One Reference the exact 
 Value of any Weight from 1 lb, to 15 tons, at 300 Progressive Rates, from id. 
 to i68s. per cwt,, and containing 186,000 Direct Answers, which, with their 
 Combinations, consisting of a smgle addition (mostly to be performed at 
 sight), will afEord an aggregate of 10,266,000 Answers ; the whole being calcu- 
 lated and designed to ensure correctness and promote despatch. By Henry 
 Harben, Accountant. Fourth Edition, carefully Corrected. Royal 8vo, 
 strongly half-bound, £1 5s. 
 
 " A practical and useful work of reference for men of business generally ; it is the best of the 
 kind we have seen.' —Ironmonger. 
 
 " Of priceless value to business men. It is a necessary book in cilL mercantile o£Eices." — She/- 
 field Inaetendent. 
 
 Comprehensive Discount Guide* 
 
 THE DISCOUNT GUIDE. Comprising several Series of 
 
 Tables for the use of Merchants, Manufacturers, Ironmongers, and others, 
 by which may be ascertained the exact Profit arising from any mode of using 
 Discounts, either in the Purchase or Sale of Goods, and the method of either 
 Altering a Rate of Discount or Advancing a Price, so as to produce, by one 
 operation, a sum that will realise any required profit after allowing one or 
 more Discounts : to which are added Tables of Profit or Advance from ij to 
 go per cent., Tables of Discount from i\ to 98} per cent., and Tables of Com- 
 mission, &c., from ^ to 10 per cent. By Henry Harben, Accountant, Author 
 of " The Weight Calculator." New Edition, carefully Revised and Corrected. 
 Demy 8vo, 544 pp. half-bound, £1 5s, 
 
 "A book such as this can only be appreciated by business men, to whom the saving of time 
 means saving of money. We have the nigh authority of Professor J. R. Voung that the tables 
 throughout the work are constructed upon strictly accurate principles. The work is a mode 
 of typographical clearness, and must prove of great value to merchants, manufacturers, and 
 general traders."— ^ri^tjA Trade journal. 
 
 Iron Shipbuilders^ and Merchants^ Weight Tables. 
 
 IRON-PLATE WEIGHT TABLES: For Iron. Shipbuilders, 
 Engineers and Iron Merchants. Containing the Calculated Weights of up- 
 wards of 150,000 difterent sizes of Iron Plates, from i foot by 6 in. by i in. to 
 10 feet by 5 feet by 1 in. Worked out on the basis of 40 lbs. to the square 
 foot of Iron of i inch in thickness. Caretully compiled and thoroughly Re- 
 vised by H. Burlinson and W. H. Simpson. Oblong 4to, 255. half-bound. 
 ' ' This v?ork will be found of great utility. The authors have had much practical experience 
 
 of what is wanting in making estimates; and the use of the book wiH save much time ill making 
 
 elaborate calculations."— £'«^/<rA Mechanic. 
 
INDUSTRIAL AND USEFUL ARTS, 31 
 
 INDUSTRIAL AND USEFUL ARTS. 
 
 Soap-making, 
 
 THE ART OF SOAP-MAKING : A Practical Handbook of the 
 Manufacture of Hard and Soft Soaps, Toilet Soaps, etc. Including many New 
 Processes, and a Chapter on the Recovery of Glycerine from Waste Leys. 
 By Alexander Watt, Author oi *' Electro-Metallurgy Practically Treated," 
 &c. With numerous Illustrations. Fourth Edition, Revised and Enlarged. 
 Crown 8vo, 7s. 6rf. cloth. 
 "The work will prove very useful, not merely to the technological student, but to the practical 
 
 soap-boiler who wishes to understand the theory of his art." — Chemical News. 
 
 "Mr. Watt's book is a thoroughly practical treatibe on an art which has almost no literature In 
 
 our language. We congratulate tne author on the success of his endeavour to fill a void in English 
 
 technical literature."— A 'a.'Mr,?. 
 
 Paper 3Iaking, 
 
 THE ART OF PAPER MAKING : A Practical Handbook of the 
 
 Manufacture of Paper from Rags, Esparto, Straw and other Fibrous Materials^ 
 Including the Manufacture of Pulp irom Wood Fibre, with a Description of 
 the Machinery and Appliances used. To which are added Details of 
 Processes for Recovering Soda from Waste Liquors. By Alexander Watt. 
 With Illustrations. Crown 8vo, ys. 6d. cloth. 
 
 "This book is succinct, lucid, thoroughly practical, and iocludes everything of interest to the 
 modem paper maker. It is the latest, most practical and most complete work on the paper-making 
 an before the British pubUc."— Pa^cr Record. 
 
 '' It may be regarded as the standard work on the subject. The book is full of valuable in- 
 formation. The ' Art of Paper-making,' is in every respect a model of a text-ibook, either for a 
 teclmical class or for the private student." — Paper and Pri7itin^ Trades Jonr^ial, 
 
 "Admirably adapted for general as well as ordinary technical reference, and as a handbook 
 for students in technical education may be warmly commended." — The Paper Maker's Monthly 
 yourjial. 
 
 Ijeather Manufacture, 
 
 THE ART OF LEATHER MANUFACTURE, Being a 
 Practical Handbook, in which the Operations of Tanning, Currying, and 
 Leather Dressing are fully Described, the Principles of Tanning Explained 
 and many Recent Processes introduced. By Alexander Watt, Author of 
 " Soap-Making," &c. With numerous Illustrations. Second Edition. Crown 
 8vo, gs. cloth. 
 "A sound, comprehensive treatise on tanning and Its accessories, This book is an eminently 
 
 valuable production, which redounds to the credit oi both author and publishers." — Chemical 
 
 Review. 
 
 ' ' This volume is technical without being tedious, comprehensive and complete without being 
 
 grosy, and it bears on every page the impress of a master hand. We have never come across a 
 etter trade treatise, nor one that so thoroughly supplied an absolute want." — Shoe astd Leather 
 Trades' Chro7ticU. 
 
 Boot and Shoe Mahing, 
 
 THE ART OF BOOT AND SHOE-MAKING, A Practical 
 
 Handbook, including Measurement, Last-Fitting, Cutting-Out, Closing and 
 
 Making, with a Description of the most approved Machinery employed. 
 
 By John B. Lend, late Editor of St. Crispin, and The Boot and Shoe-Maker. 
 
 With numerous Illustrations. Third Edition. i2mo, 2s, cloth limp. 
 
 " This excellent treatise is by far the best work ever written on the subject. A new work, 
 
 embracing all modern improvements, was much wanted. This want is now satisfied. The chapter 
 
 on clicking, which shows now waste maybe prevented, will save fifty times the price of the book." 
 
 ^-Scotiisk LeatJur Trader. 
 
 MECHANICAL DENTISTRY: A Practical Treatise on the 
 Construction of the various kinds of Artificial Dentures. Comprising also Use- 
 ful Formulae, Tables and Receipts for Gold Plate, Clasps, Solders, Sec. &c. 
 By Charles Hunter. Third Edition, Revised, With upwards of 100 
 Wood Engravings. Crown 8vo, 3s, 6d. cloth, 
 
 " The work is very praLCtical."— Monthly Review of Dental Stirgtry. 
 
 " We can strongly recommend Mr. Hunter's treatise to all students preparing for the profession 
 of dentistry, as well as to every mechanical dentist." — Dublin Jour^ial of Medical Science. 
 
 Wood Engraving, 
 
 WOOD ENGRA VING : A Practical and Easy Introduction to the 
 Study of the Art. By William Norman Brown. Second Edition. With 
 numerous Illustrations, izmo, is. 6d. cloth limp. 
 . "The book is clear and, complete, and will be useful to anyone wanting to understand the first 
 elements of the beautiful art of wood engrav'ms,"— Graphic. 
 
32 CROSBY LOCKWOOD &- SON'S CATALOGUE. 
 
 HANDY BOOKS FOR HANDICRAFTS. By PAUL N. HASLUCK. 
 Metal Turning* 
 
 THE METAL TURNER'S HANDYBOOK. A Practical Manual 
 for Workers at the Foot-Lathe: Embracing Information on the Tools, 
 Appliances and Processes employed in Metal Turning. By Paul N. Has- 
 LucK, Author of " Lathe-Work." With upwards of One Hundred Illustra- 
 tions. Second Edition, Revised. Crown 8vo, 2S. cloth. 
 
 " Clearly and concisely written, excellent in every way." — Mechafiical World, 
 
 Wood Turning^ 
 
 THE WOOD TURNER'S HANDYBOOK. A Practical Manual 
 for Workers at the Lathe: Embracing Information on the Tools, Appliances 
 and Processes Employed in Wood Turning. By Paul N. Hasluck, With 
 upwards of One Hundred lUastrations. Crown 8vo, zs- cloth. 
 "We recommend the book to young turners and amateurs. A multitude of workmen have 
 hitherto sought in vain for a manual of this special industry." — Mechanical World. 
 
 WOOD AND METAL TURNING. By P. N. Hasluck. 
 (Being the Two preceding Vols, bound together.) 300 pp , with upwards of 
 zoo Illustrations, crown 8vo, 3s. 6d. cloth. 
 
 Watch Hepairing. 
 
 THE WATCH JOBBER'S HANDYBOOK. A Practical Manual 
 on Cleaning, Repairing and Adjusting, Embracing Information on the Tools, 
 Materials, Appliances and Processes Employed in Watchwork. By Paul Ni 
 Hasluck, With upwards of One Hundred Illustrations. Cr. 8vo, 2S. cloth, 
 " All young persons connected with the trade should acquire and study this excellent, and at 
 the same time, inexpensive work." — CUrken-well Cfironicle, 
 
 Clock Hepairing. 
 
 THE CLOCK JOBBER'S HANDYBOOK : A Practical Manual 
 on Cleaning, Repairing and A djusting. Embracing Information on the Tools> 
 Materials, Appliances and Processes Employed in Clockwork. By Paul N. 
 Hasluck, Withupwards of roo Illustrations. Cr. 8vo, as. cloth. 
 
 " Of inestimable service to those commencing the tV3ifie."—Covenlry Standard, 
 
 WATCH AND CLOCK JOBBING. By P. N. Hasluck. 
 (Being the Two preceding Vols, bound together.) 320 pp., with upwards of 
 200 Illustrations, crown 8vo, 3s. 6d, cloth. 
 
 Pattern MaMng. 
 
 THE PATTERN MAKER'S HANDYBOOK. A Practical 
 Manual, embracing Information on the Tools, Materials and Appliances em- 
 ployed in Constructing Patterns for Founders. By Paul N. Hasluck. 
 With One Hundred Illustrations. Crown 8vo, zs. cloth. 
 
 "This handy volume contains sound information of considerable value to students and 
 artificers." — Hardware Trades your?ial. 
 
 Mechanical Manipulation, 
 
 THE ME CHA NIC'S WORKSHOP HA ND YBOOK. A Practical 
 Manual on Mechanical Manipulation. Embracing Information on various 
 Handicraft Processes, with Useful Notes and Miscellaneous Memoranda, 
 By Paul N. Hasluck. Crown 8vo, 2s. cloth. 
 
 " It is a book which should be found in every workshop, as it is one which will be continually 
 referred to for a very great amount of standard information," — Saturday ReviCTv. 
 
 Model Engineering, 
 
 THE MODEL ENGINEER'S HANDYBOOK: A Practical 
 Manual on Model Steam Engines. Embracing Information on the Tools, 
 Materials and Processes Employed in their Construction. By Paul N. 
 Hasluck. With upwards of 100 Illustrations. Crown 8vo, 2S. cloth. 
 " Ey carefully going through the work, amateurs may pick up an excellent notion of the con- 
 struction of full-sized steam envies." — Telegraphic Journal, 
 
 Cahinet Making, 
 
 THE CABINET WORKER'S HANDYBOOK : A Practical 
 Manual, embracing Information on the Tools, Materials, Appliances and 
 Processes employed in Cabinet Work. By Paul N, Hasluck, Author of 
 " Lathe Work," &c. With upwards of 100 illustrations. Crown 8vo, 2s, 
 
 cloth, {Glasgow Herald. 
 
 " Thoroughly practical throughout The amateur worker in wood will find it most useful."— 
 
INDUSTRIAL AND USEFUL ARTS. 33 
 
 Electrolysis of Gold, Silver, Copper, etc. 
 
 ELECTRO-DEPOSITION : A Practical Treatise on the Electrolysis 
 of Gold, Silver, Copper, Nickel, and other Metals and Alloys. With descrip- 
 tions of Voltaic Batteries, Magneto and Dynamo-Electric Machines, Ther- 
 mopiles, and of the Materials and Processes used in every Department of 
 the Art, and several Chapters on Electro-Metallurgy, By Alexander 
 Watt. Third Edition, Revised and Corrected. Crown 8vo, 95. cloth. 
 "Eminently a book for the practical worker In electro-deposition. It contains practical 
 
 descriptions of methods, processes and materials as actually pursued and used in the workshop." 
 
 — Engineer. 
 
 Electro- 3Ietalliirgy, 
 
 ELECTRO-METALLURGY : Practically Treated. By Alexander 
 Watt, Author of " Electro-Deposition,'' &c. Ninth Edition, Enlarged and 
 Revised, with Additional Illustrations, and including the most recent 
 Processes, i2mo, 4s. cloth boards. 
 
 "From this book both amateur and artisan may learn everything necessary for the successful 
 prosecution of electroplating." — Iron. 
 
 Electroplating, 
 
 ELECTROPLATING: A Practical Handbook on the Deposi- 
 tion of Copper, Silver, Nickel, Gold, Aluminium, Brass, Platinum, &c. &c. 
 With Descriptions of the Chemicals, Materials, Batteries and Dynamo 
 Machines used in the Art. By J. W, Urquhart, C.E. Second Edition, with 
 Additions. Numerous lUusirations. Crown 8vo, 5s. cloth. 
 " An excellent practical manual." — Engineering, 
 " An excellent work, giving the newest information." — HorologicaL yournal. 
 
 Electrotyping» 
 
 ELECTROTYPING : The Reproduction and Multiplication of Print- 
 ing Surfaces and Works of Art by the Electro-deposition of Metals, By J. W. 
 Urquhaht, C.E. Crown 8vo, 5s. cloth, 
 " The book is thoroughly practical. The reader Is, therefore, conducted through the leading 
 
 laws of electricity, then through the metals used by electrotypers, the apparatus, and the depositing 
 
 processes, up to the final preparation of the work."— j4r/ j^ourjial. 
 
 Horology, 
 
 A TREATISE ON MODERN HOROLOGY, in Theory and Prac- 
 tice. Translated from the French of Claudius Saunier, by Tulien Trip- 
 FLIN, F.R.A.S., and Edward Rigg, M.A., Assayer in the Royal Mint. With 
 78 Woodcuts and 22 Coloured Plates. Second Edition. Royal 8vo, £2 25. 
 cloth ; £2 los. half-calf. 
 
 " There is no horological work in the English language at all to be compared to this produc- 
 tion of M. Saunier's for clearness and completeness. It is alike good as a guide for the student and 
 as a reference for the experienced horologist and skilled workman." — Horological Journal. 
 
 " The latest, the most complete, and the most reUable of those literary productions to which 
 continental watchmakers are indebted for the mechanical superiority over their Enelish brethren 
 —in fact, the Book of Books, is M. Saunier's 'Treatise.'" — IVatchsnaker, Jeweller a7i.d Silversntith, 
 
 t^ ft f fTi 'Wi.ii.Tcin/G 
 
 THE WATCHMAKER'S HANDBOOK. A Workshop Com- 
 panion for those engaged in Watchmaking and the Allied Mechanical Arts. 
 From the French of Claudius Saunier. Enlarged by Julien Tripplin, 
 F.R.A.S., and Edward Rigg, M.A., Assayer in the Royal Mint. Woodcuts 
 and Copper Plates. Third Edition, Revised. Crown 8vo, gs. cloth, 
 
 " Each part is truly a treatise in itself. The arrangement is good and the language is clear and 
 concise. It is an admirable guide for the young ■w3Xchm3ker."~Engineering. 
 
 " It is impossible to speak too highly of its excellence. It fulfils every requirement in a hand- 
 book intended for the use of a woricman,"— H^izfcA atid Clockmaker. 
 
 " This book contains an immense number of practical details bearing on the daily occupation 
 of a watchmaker."— -^a/^c-Awa-fe?- and Metalworker (Chicago). 
 
 Goldsmiths^ Worlc. 
 
 THE GOLDSMITH'S HANDBOOK. By George E. Gee, 
 Jeweller, &c. Third Edition, considerably Enlarged. lamo, 35. 6d, cl. bds. 
 "A good, soind educator, and will be accepted as an authority." — Horological Journal. 
 
 Silversmiths' Work, 
 
 THE SILVERSMITH'S HANDBOOK. By George E. Gee. 
 Jeweller, &c. Second Edition, Revised, with numerous Illustrations, lamo, 
 3s. 6d. cloth boards. 
 "Workers in the trade will speedily discover its merits when they sit down to study it." — 
 English Mechanic, 
 
 *** The above two works together, strongly half-bound, price 75, 
 
34 CROSBY LOCKWOOD &• SON'S CATALOGUE. 
 
 JBread and Biscuit Baking, 
 
 THE BREAD AND BISCUIT BAKER'S AND SUGAR- 
 BOILER'S ASSISTANT. Including a large variety of Modern Recipes. 
 With Remarks on the Art of Bread-making. By Robert Wells, Practical 
 Baker. Second Edition, with Additional Recipes, Crown 8vo, 2s. cloth, 
 " A large number of wrinkSes for the ordinary cook, as well as the hB.ker."—Saiurday Eevierw. 
 
 Confectionery, 
 
 THE PASTRYCOOK AND CONFECTIONER'S GUIDE. 
 For Hotels, Restaurants and the Trade in general) adapted also for Family 
 Use. By Robert Wells, Author of " The Bread and Biscuit Baker's and 
 Sugar Boiler's Assistant." Crown 8vo, 2S. cloth, 
 " We cannot speak too highly of this really excellent work. In these days of keen competition 
 our readers cannot do better than purchase this book." — Bayers' TiJftes. 
 
 Ornamental Confectionery, 
 
 ORNAMENTAL CONFECTIONERY : A Guide for Bakers, 
 Confectioners and Pastrycooks ; including a variety of Modern Recipes, and 
 Remarks on Decorative and Coloured Work. With 129 Original Designs. 
 By Robert Wells, Crown 8vo, 55. cloth. 
 
 "A valuable work, and should be in the hands of every baker and confectioner. The illus- 
 rative designs are alone worth treble the amount charged for the whole work,"— Bayers' Times. 
 
 Flour Confectionery, 
 
 THE MODERN FLOUR CONFECTIONER. Wholesale and 
 Retail. Containing a large Collection of Recipes for Cheap Cakes, Biscuits, 
 &c. With Remarks on the Ingredients used in their Manufacture, &c. By 
 R. Wells, Author of " Ornamental Confectionery," " The Bread and Biscuit 
 Baker," " The Pastrycook's Guide,'' &c. Crown 8vo, 2s. cloth. 
 
 Laundry Work, 
 
 LA UNDRY MANAGEMENT. A Handbook for Use in Private 
 and Puhlic Laundries, Including Descriptive Accounts of Modern Machinery 
 and Appliances for Laundry Work. By the Editor of "The Laundry 
 Journal." With numerous Illustrations, Crown 8vo, as. 6d. cloth. 
 
 CHEMICAIi MANUFACTUKES & COMMERCE, 
 
 New Manual of Engineering Chemistry, 
 
 ENGINEERING CHEMISTRY: A Practical Treatise for the 
 Use of Analytical Chemists, Engineers, Iron Masters, Iron Founders, 
 Students, and others. Comprising Methods of Analysis and Valuatioxi of the 
 Principal Materials used in Engineering Work^ with numerous Analyses, 
 Exami)]es, and Suggestions. By H. Joshua Phillips, F.I.C, F.C.S., 
 Analytical and Consulting Chemist to the Great Eastern Railway, Crown 8vo, 
 320 pp., with Illustrations, ids. 6rf. cloth. [Just published. 
 
 " In this work the author has rendered no small service to a numerous body of practical men. 
 . . . The analytical methods may be pronounced most satisfactory, being as accurate as the 
 despatch required of engineering chemists permits."— C/tewiica/ News. 
 
 Analysis and Valuation of Fuels, 
 
 FUELS: SOLID, LIQUID AND G^S£0?7S, Their Analysis 
 and Valuation. For the Use of Chemists and Engineers. By H. J. Phillips, 
 F.C.S., Analytical and Consulting Chemist to the Great Eastern Railway. 
 Crown 8vo, 3s. 6d. cloth. 
 
 " Ought to have its place in the laboratory of every metallurgical establishment, and wherever 
 fuel is used on a large scile." — Chonicat Neios. 
 
 " Cannot fail to be of wide interest, especially at the present time." — Railway News. 
 
 Alkali Trade, Manufacture of Sulphuric Acid, etc, 
 
 A MANUAL OF THE ALKALI TRADE, including the 
 
 Manufacture of Sulphuric Acid, Sulphate of Soda, and Bleaching Powder. 
 
 By John Lomas. 390 pages. With 232 Illustrations and Working Drawings. 
 
 Second Edition. Royal 8vo, £1 10s. cloth. 
 
 "This book is written by a manufacturer for manufacturers. The working details of the most 
 approved forms of apparatus are eiven, and these are accompanied by no less than 232 wood en- 
 gravings, all of which may be used for the purposes of construction."— WM<r««M>«. 
 
AGRICULTURE, FARMING, GARDENING, etc. 35 
 
 The Bloivpipe. 
 
 THE BLOWPIPE IN CHEMISTRY, MINERALOGY, AND 
 GEOLOGY. Containing all known Methods of Anhydrous Analysis, Work- 
 ing Examples, and Instructions for Making Apparatus. By Lieut.-Col. W. A. 
 Ross, R.A. With 120 Illustrations. New Edition. Crown 8vo, 55. cloth. 
 "The student who goes through the course of experimentation here laid down will gain n 
 better insight into inorgfanic chemistry and mineralogy than if he had 'got up' any of the best 
 text-books ol the day, and passed any number of examinations in their contents."— C/wwi'ira/ Neivs. 
 
 Commercial Chem^ical Analysis, 
 
 THE COMMERCIAL HANDBOOK OF CHEMICAL ANA- 
 LYSIS; or, Practical Instructions tor the determination oi the Intrinsic or 
 Commercial Value of Substances used in Manufactures, Trades, and the Arts. 
 By A, Normandy. New Edition by H. M. Noad, F.R.S. Cr. 8vo, 12s. 6d. cl. 
 "Essential to the analysts appointed lender the new Act. The most recent results aregiven, 
 and the work is well edited and carefully written."— 'iVorfwrfl. 
 
 Brewing, 
 
 A HANDBOOK FOR YOUNG BREWERS. By Herbert 
 Edwards Wright, B.A. New Edition, much Enlarged, [In the press. 
 
 Dye~War€s and Colours, 
 
 THE MANUAL OF COLOURS AND DYE-WARES : Their 
 Properties, Applications, Valuation, Impurities, and Sophistications. For the 
 use of Dyers, Printers, Drysalters, Brokers, &c. By J. W. Slater. Second 
 Edition, Revised and greatly Enlarged. Crown 8vo, ys. 6d. cloth. 
 
 " A complete encyclopedia of the maiifiaHnctoria. The information given respecting each 
 article is full and precise, and the methods of determining the value of articles such as these, so 
 liable to sophistication, are given with clearness, and are practical as well as valuable." — Chetnut 
 a?id Drug-gist. 
 
 "There is no other work which covers precisely the same ground. To students preparing 
 for examinations in dyeing euid printing it will prove exceedingly useful."— CAiWiiro/ News. 
 
 Pigments, 
 
 THE ARTIST'S MANUAL OF PIGMENTS. Showing 
 their Composition, Conditions of Permanency, Non-Permanency, and Adul- 
 terations; Effects in Combination with Each Other and with Vehicles ; and 
 the most Reliable Tests of Purity. By H, C. StandactE, Second Edition. 
 Crown 8vo, 2s. 6d. cloth. 
 
 " This work is indeed ntuliUTn-in-parT/o, and we can, with good conscience, recommend it to 
 all who come in contact with pigments, whether as makers, dealers or ns^is."— Chemical Review. 
 
 Gauging, Tables and Rules for Kevenue Officers, 
 
 JBreicers, etc* 
 
 A POCKET BOOK OF MENSURATION AND GAUGING : 
 Containing Tables, Rules and Memoranda for Revenue Officers, Brewers, 
 Spirit Merchants, &c. By J. B. Mant (Inland Revenue). Second Edition 
 Revised. Oblong i8mo, 4s. leather, with elastic band. 
 
 " This handy and useful book is adapted to the requirements of the Inland Revenue Depart- 
 ment, and will be a favourite book of reteience."— Civilian. 
 
 " Should be in the hands of every practical biev/ei."— Brewers' journal. 
 
 AGRICULTURE, FARMING, G ARDENING, etc. 
 
 Youatt and Burn's Complete Grazier. 
 
 THE COMPLETE GRAZIER, and FARMER'S and CATTLE- 
 BREEDER'S ASSISTANT. Including the Breeding, Rearing, and Feeding 
 of Stock ; Management of the Dairy, Culture and Management of Grass 
 Land and of Grain and Root Crops, &c. By W. Youatt and R. Scott 
 Burn. An entirely New Edition, partly Re-written and greatly Enlarged, by 
 W. Fream, B.Sc.Lond,, LL.D. In medium 8vo, about I, ooo pp. lln the press. 
 
 Aaricultural Facts and Figures. 
 
 NOTE-BOOK OF AGRICULTURAL FACTS AND FIGURES 
 FOR FARMERS AND FARM STUDENTS. By Primrose McConnell, 
 late Professor of Agriculture, Glasgow Veterinary College. Third Edition. 
 Royal 32mo, 4s. leather. 
 " The most complete and comprehensive Note-book for Fanners and Farm Students that we 
 
 have seen. It literally teems with mforraation, and wo can cordia llyrecommend it to all connected 
 
 with agrcuilture."— A'ffr/A British Agriculturist. 
 
36 CROSBY LOCK WOOD cS- SON'S CATALOGUE. _^ 
 
 Flour Manufacture, Milling, etc. 
 
 FLOUR MANUFACTURE: A Treatise on Milling Science 
 and Practice. By Friedrich Kick, Imperial Regierungsrath, Professor of 
 Mfechanical Technology in the Imperial German Polytechnic Institute, 
 Prague. Translated from the Second Enlarged and Revised Edition with 
 Supplement. By H. H, P. Powlks, A.M.l.C.E. Nearly 400 pp. Illustrated 
 with 28 Folding Plates, and -167 Woodcuts. Royal 8vo, 25s, cloth. 
 " This valuable work is, and will rqjnain, the standard authority on the science of milling. . . 
 The miller v/ho has read and digested this work will have laid the foundation, so to speak, of a suc- 
 cessful career ; he will have acquired a number of general principles which he can proceed to 
 apply. In this handsome volume we at last have the accepted text-bookofmodernmillmgingood, 
 sound English, which has little, if any, trace of the German idiom." — The Miller. 
 
 " The appearance of this celebrated work in English is very opportune, and British millers 
 will, we are sure, not be slow in availing themselves of its ^ages."— Millers' Gassette. 
 
 Small Farming. 
 
 SYSTEMATIC SMALL FARMING; or. The Lessons of my 
 Farm. Being an Introduction to Modern Farm Practice for Small Farmers 
 in the Culture of Crops ; The Feeding of Cattle; The Management of the 
 Dairy, Poultry and Pigs, &c. &c. By Robert Scott Burn, Author of " Out- 
 lines of Landed Estates' Management." Numerous lUusts., cr. 8vo, 6s. cloth. 
 "This is the completest book of its class we have seen, and one which every amateur farmer 
 will read with pleasure and accept as a guide." — Field. 
 
 "The volume contains a vast amount of useful information. No branch of farming is left 
 untouched, from the labour to be done to the results achieved. It may be safely recommended to 
 all who think they will be in paradise when they buy or rent a three-acre iaxui,."—Glasgo'U) Herald. 
 
 Modern Farm,ing* 
 
 OUTLINES OF MODERN FARMING. By R. Scott Burn. 
 Soils, Manures, and Crops— Farming and Farming Economy— Cattle, Sheep, 
 and Horses — Management of Dairy, Pigs and Poultry — Utilisation of 
 Town-Sewage, Irrigation, &c. Sixth Edition. In One Vol., 1,250 pp., half- 
 bound, profusely Illustrated, 12s. 
 
 " The aim of the author has been to make his work at once comprehensive and trustworthy, 
 and in this aim he has succeeded to a degree which entitles him to much credit." — MorjUns 
 Advertiser. "No farmer should be without this hooV.."— Banbury Guardian. 
 
 Agricultural Engineering, 
 
 FARM ENGINEERING, THE COMPLETE TEXT-BOOK OF. 
 Comprising Draining and Embanking; Irrigation and Water Supply ; Farm 
 Roads, Fences, and Gates; Farm Buildings, their Arrangement and Con- 
 struction, with Plans and Estimates; Barn Implements and Machines ; Field 
 Implements and Machines; Agricultural Surveying, Levelling, &c. By Prof. 
 John Scott, Editor of the " Farmers' Gazette," late Professor of Agriculture 
 and Rural Economy at the Royal Agricultural College, Cirencester, &c, &c. 
 In One Vol., 1,150 pages, half-bound, with over 600 Illustrations, 125. 
 "Written with great care, as well as with knowledge and ability. The author has done his 
 
 work well ; we have found him a very trustworthy guide wherever we have tested his statements. 
 
 The volume will be of great value to agricultural students." — Mark Lane Express. 
 
 " For a young agriculturist we know oftno handy volume likely to be more usefully studied. 
 
 — Bell's Weekly Messenger. 
 
 English Agriculture, 
 
 THE FIELDS OF GREAT BRITAIN : A Text-Book of 
 Agriculture, adapted to the Syllabus of the Science and Art Department. 
 For Elementary and Advanced Students. By Hugh Clements (Board of 
 Trade). Second Ed., Revised, with Additions. iSmo, 2s. 6£i. cl. 
 "Amost comprehensive volume, giving a mass of information," — AgriatUural Econotnist, 
 " It is a long time since we have seen a book which has pleased us more, or which contains 
 such a vast and useful fund of knowledge." — Educational Times, 
 
 Tables for Fariners, etc, 
 
 TABLES, MEMORANDA, AND CALCULATED RESULTS 
 for Farmers, Graziers, Agricultural Students, Surveyors, Land Agents Auc- 
 tioneers, etc. With a New System of Farm Book-keeping. Selected and 
 Arranged by Sidney Francis. Second Edition, Revised. 272 pp., waist- 
 coat-pocket size, IS. 6d. limp leather. 
 
 " Weighing less than i oz., and occupying no more space than a match box, it contains a mass 
 of facts and calculations which has never before, in such handy form, been obtainable. Every 
 operation on the farm is dealt with. The work may be taken as thoroughly accurate, the whole ot 
 the tables having been revised by Dr. Fream. We cordially recommend it."— Bell's Weekly 
 Messenger. 
 
 " A marvelloub little book. . . . The agriculturist who possesses himself of it will not be 
 disappointed with his investment." — The Farm. 
 
AGRICULTURE. FARMING, GARDENING, etc, 37 
 
 Farm and Estate Book-keeping, 
 
 BOOK-KEEPING FOR FARMERS S- ESTATE OWNERS. 
 A Practical Treatise, presenting, in Three Plans, a System adapted for all 
 Classes of Farms. By Johnson M. Woodman, Chartered Accountant. Second 
 ^Edition, Revised. Cr. 8vo, 3s. 6d. cl. bds. ; or 2S. 6d. cl. limp. 
 
 /The volume is a capital study of a most important s\ih}ect."—^£-riciUiural Gazette. 
 Will be found of great assistance by those who intend to commence a system of book-keep- 
 ing, the author's examples being clear and exphcit, and his explanations, while full and accurate, 
 being to a large extent free from teclinicalities."— Z-iVe Stock Journal. 
 
 Farm Account Book. 
 
 WOODMAN'S YEARLY FARM ACCOUNT BOOK. Giving 
 a Weekly Labour Account and Diary, and showing the Income and Expen- 
 diture under each Department of Crops, Live Stock, Dairy, &c. &c. With 
 Valuation, Profit and Loss Account, and Balance Sheet at the end of the 
 Year, and an Appendix of Forms. Ruled and Headed for Entering a Com- 
 plete Record of the Farming Operations. By Johnson M. Woodman, 
 Chartered Accountant. Folio, ys. 6d. half bound. laeieure. 
 
 "Contains every requisite form for keeping farm accounts readily ^md accurately."— ^^y/- 
 
 Early Fruits, Flowers and Vegetables, 
 
 THE FORCING GARDEN ; or, How to Grow Early Fruits. 
 Flowers, and Vegetables. With Plans and Estimates for Building Glass- 
 houses, Pits and Frames. By Samuel Wood. Crown 8vo, 3s. 6d. cloth. 
 "A good book, and fairly fills a place that was in some degree vacant. The book is written with 
 
 great care, and contains a great deaf of valuable teaching." — Gardeners' Ma^aziJie. 
 
 " Mr. Wood's book is an originzil and exhaustive answer to the question ' How to Grow Early 
 
 Fruits, Flowers and Vegetables ? ' "—Land and Water. 
 
 Good Gardening, 
 
 A PLAIN GUIDE TO GOOD GARDENING ; or, How to Grow 
 Vegetables, Fruits, and Flowers, With Practical Notes on Soils, Manures, 
 Seeds, Planting, Laying-out of Gardens and Grounds, &c. By S. Wood. 
 Fourth Edition, with numerous Illustrations. Crown 8vo, 3s. 6d. cloth. 
 " A very good book, and one to be highly recommended as a practical guide. The practical 
 
 directions are excellent." — Athen<sttm. 
 
 "Maybe recommended to young gardeners, cottagers, and specially to amateurs, for the 
 
 plain, simple, and trustworthy information it gives on common matters too often neglected." — 
 
 Gardeners' Chronicle. 
 
 Gainful Gardening, 
 
 MULTUM-IN-PAKVO GARDENING; cr, How to make One 
 Acre of Land produce £'620 a-year by the Cultivation of Fruits and Vegetables ; 
 also, How to Grow Flowers in Three Glass Houses, so as to realise £r76 per 
 annum clear Profit. By S. Wood. Fifth Edition. Crown 8vo, is. sewed. 
 
 *' We are bound to recommend it as not only suited to the case of the amateur and gentleman's 
 gardener, but to the market grower." — Gardeners' Magazine. 
 
 Gardening for Ladies. 
 
 THE LADIES' MULTUM-IN-PARVO FLOWER GARDEN, 
 and Amateurs' Complete Guide. By S, Wood. With Illusts. Cr. 8vo, 3s. 6A. cl. 
 
 " This volume contains a good deal of sound, common sense instruction." — Florist. 
 
 " Full of shrewd hints and useful instructions, based on a lifetime of experience." — Scotsman, 
 
 Receipts for Gardeners. 
 
 GARDEN RECEIPTS. By C. W. QuiN. i2mo, is, 6cl. cloth. 
 
 "A useful and handy book, containing a good dejtl of valuable information." — Atheneeum. 
 
 Market Gardening. 
 
 MARKET AND KITCHEN GARDENING. By Contributors 
 to " The Garden," Compiled by C. W. Shaw, late Editor of *' Gardening 
 Illustrated." i2mo, 3s. 6d. cloth boards. 
 "The most valuable compendium of kitchen and market-garden work published."— iJ'arwjer. 
 
 Cottage Gardening. 
 
 COTTAGE GARDENING; or. Flowers, Fruits, and Vegetables for 
 Small Gardens. By E. Hobday, izmo, is. 6i. cloth limp. 
 
 Potato Culture. 
 
 POTATOES : How to Grow and Show Them. A Practical Guide 
 to the Cultivation and General Treatment of the Potato. By James Pink. . 
 Second Edition. Crown 8vo, 2S, cloth. 
 
38 CROSBY LOCKWOOD &' SON 'S CATALOGUE. 
 
 LAND AND ESTATE MANAGEMENT, LAW, etc. 
 
 Hudson's Land Valuer's Pocket-Book, 
 
 THE LAND VALUER'S BEST ASSISTANT: Being Tables 
 on a very much Improved Plan, for Calculating the Value of Estates. With 
 Tables for reducing Scotch, Irish, and Provincial Customary Acres to Statute 
 Measure, &c. By R. Hudson, C.E. New Edition. Royal 32mo, leather, 
 elastic band, 4s. 
 
 "This new edition includes tables for ascertaining the value of leases for any term of years ; 
 and for showing how to lay out plots of eround of certain acres in forms, square, round, &c,, with 
 valuable rules for ascertaining the probable worth of standing timber to any amount j and is of 
 incalculable value to the country gentleman and professional man."— Farrfurs y<mr7ial. 
 
 EwarPs Land Improver's JPocketSook* 
 
 THE LAND IMPROVER'S POCKET-BOOK OF FORMULA, 
 TABLES and MEMORANDA required in any Computation relating to the 
 Permanent Improvement of Landed Property. By John Ewart, Land Surveyor 
 and Agricultural Engineer. Second Edition, Revised. Royal samo, oblong, 
 leather, gilt edges, with elastic band, 45, 
 "A compendious and handy little volame "Spectator. 
 
 Complete Agricultural Surveyor's Pocket-Book, 
 
 THE LAND VALUER'S AND LAND IMPROVER'S COM- 
 PLETE POCKET-BOOK. Consisting of the above Two Works bound to- 
 gether. Leather, gilt edges, with strap, 7s. 6d. 
 
 " Hudson's book is the best ready-reckoner on matters relating to the valuation of land and 
 crops, and its combination with Mr.Ewart's work greatly enhances the value and usefulness of the 
 latter-mentioned. ... It is most useful as a manual for reference,"— A^'ew/A of England Farmer, 
 
 Auctioneer's Assistant, 
 
 THE APPRAISER, A UCTIONEER, BROKER, HOUSE AND 
 ESTATE AGENT AND VALUER'S POCKET ASSISTANT, tor the Valua- 
 tion for Purchase, Sale, or Renewal of Leases, Annuities and Reversions, and 
 of property generally ; with Prices for Inventories, &c. By John Wheeler, 
 Valuer, &c. Fifth Edition, re-written and greatly extended by C. Norris, 
 Surveyor, Valuer, &c. Royal 32mo, 55. cloth. 
 
 " A neat and concise book of reference, containing an admirable and clearly-arranged list of 
 
 prices for Inventories, and a very practical guide to determine the value of {uininite,&c."— Standard. 
 
 " Contains a large queuitity of varied and useful information as to the valuation for purchase, 
 
 sale, or renewal of leases, annuities and reversions, and of property generally, with prices for 
 
 inventories, and a guide to determine the value of interior fittings and other eSects."— Builder. 
 
 Auctioneering » 
 
 AUCTIONEERS: THEIR DUTIES AND LIABILITIES, 
 
 A Manual of Instruction and Counsel for the Young Auctioneer. By Robert 
 Squibbs, Auctioneer. Second Edition, Revised and partly Re- written. Demy 
 8vo, 125. 6d. cloth, 
 
 "The position and duties of auctioneers treated compendiously and clearly." — Builder. 
 
 "Every auctioneer ought to possess a copy of this excellent work." — Ironmonger. 
 
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LAND AND ESTATE MANAGEMENT. LAW, etc, 39 
 
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