11 I I I III I I I I 11 A TR]EATISE ON THE RICHARDS STEAM-ENGINE INDICATOR, WITH DIRECTIONS FOR ITS USE. BY CHARLES T. PORTER. REVISED, WITH NOTES AND LARGE ADDITIONS, AS DEVELOPED BY AMERICAN PRACTICE, WITH AN APPENDIX, CONTAINING USEFUL FORMULAS AND RULES FOR ENGINEERS, BY F. W. BACON, M. E., MEMBER OF THE AMERICAN SOCIETY OF CIVIL ENGINEEES. NEW YORK: D. VAN NOSTRAND, PUBLISHER, 23 MURRAY AND 27 WAREM. STREET. 1869. Entered according to Act of Congress, in the year 1869, by D. VAN NOSTRAND, in the Clerk's Office of the District Court oi the United States for the Southern District of New York. PREFACE, IN introducing the Richards Improved SteamEngine Indicator, we desire to call the attention of the numerous class who, as constructors, managers or owners, are interested in the steam-engine, to the advantages which it possesses. In the following pages all necessary information is furnished concerning the instrument and its application, and such instruction is given to those who are not already skilled in the use of the Indicator, as will enable them to employ it to the best advantage. The Indicator was invented by Watt. For some time it was kept by him a secret, but became known before his death, and to its use, now quite general, we are more indebted than to anything else, for the degree of excellence which the steam-engine has attained. The employment of more rapid velocities of piston, with higher pressures of steam, and higher grades of expansion, which has become so extensive and promises ultimately to be universal, has increased greatly the importance of the Indicator; since this is the only means as yet known, by which the engineer can render himself 4 PREFACE. familiar with the action of steam ufder these new conditions. Unfortunately, every form of this instrument has hitherto failed in its application to engines of this class. The long and tremulous spring used in them was put in a state of violent' oscillation by the momentum of the piston and attached parts, and the result was a serrated figure, from which but little information could be extracted; so that, after a time, attempts to employ the Indicator in this important and rapidly enlarging field were quite abandoned. Under these circumstances, the appearance at the Great Exhibition of 1862 of the improved form of this instrument, invented by Mr. Charles B. Richards, an engineer of Hartford, Connecticut, U. S., may not improperly be regarded as an event of some importance. The action of this Indicator was found to be quite perfect, under the severest tests to which it could there be subjected, and recently it has been still more thoroughly tried, on an express engine on the London and South-Western Railway, and its performance has more than realized the expectations formed of it. Two instruments, among the first manufactured by us, were employed, with which nearly two hundred diagrams were taken, on a trip to Southampton and back, at pressures varying from 80 lbs. to 130 lbs., at rates of motion varying from the slowest up to 260 revolutions per minute, giving a speed of 55 miles per hour, and at all points of cut-off; and PREFACE. 5 they -were found uniformly to work with the same steadiness at the highest velocity as at the lowest, and al the earliest point of cut-off as at the latest. Copies of a few of the diagrams are here given. We do not claim for these Indicators superiority on engines running at high velocities only, though certainly it is there most apparent where others will not answer at all; but we believe also, for reasons herein explained, that they will be found in practice to be the only correct Indicators for engines running at any speed, even the lowest. We have only to add, that no pains have been spared to attain, in the manufacture of these instruments, the highest degree of accuracy and excellence, and that if the directions here given are attended to, their indications may be implicitly relied on. ELLIOTT BROTHERS. PREFACE. THE demand for an elementary treatise won the Richards Steam-Engine Indicator, together with the solicitation of professional friends, has induced me to undertake the preparation of the work. The original and very excellent work of Mr. Porter, now out of print, being principally an illustration of English engines and English practice, leaves room for a work combining American engines and American practice. I have therefore used much of Mr. Porter's, and added new matter and new diagrams-the result of a large experience, extending over six years. The new diagrams introduced were, with one or two exceptions, taken by myself. The diagrams taken November 14th, 1867, from the locomotive No. 50, built by the "Taunton Locomotive Works, " are believed to be the first ever taken in this country from a locomotive when making a regular trip with an express train. It will be of interest to the American engineer to compare them with those from an English locomotive, as shown in the work. 8 AMERICAN EDITOR'S PREFACE. In order to make the work more useful to the practical engineer, an Appendix has been added, containing various formulas, which, during an experience of more than thirty years as a practical engineer, have been collected, but never before given to the public. The rules for calculating the horse-power of belting have been found to be correct by practice. They are copied by permission from a treatise on belting by Messrs. Hoyt Bros., Nos. 28 and 30 Spruce street, of this city. The prime object has been to give nothing that is not known by practical experience to be correct, also to give it in a way that will be understood by any one capable of filling the place of an engineer. F. W. BACON. NEW YORK CITY, August, 1869. RICHARDS' IMPROVED STEAM-ENGINE INDICATOR. THE NATURE AND USE OF THE INDICATOR. THE Steam-Engine Indicator is an instrument designed to show the pressure of steam in the cylinder, at each point of the piston's stroke. It does this in the following manner: A pencil, moving up and down with the varying pressure of the steam, draws a line on paper, which has a motion backward and forward, coincident with that of the piston. The paper is placed on a drum, which, while the piston is advancing, is caused to make about three-quarters of a revolution, by means of a cord connected with a suitable part of the engine, and while the piston is receding, is brought back to its first position by the reaction of a spring. The pencil is attached to a small piston, moving without friction in a cylinder, 1* 10 RICHARDS' STEAM-ENGINE INDICATOR. ~ and the motion of which is resisted by a spring of known elastic force. The pressure of the atmosphere is always on the upper side of this piston, and when the communication with the cylinder of the engine is closed, it is on the under side also; and if then the motionless pencil be applied to the moving paper, it will draw a line which is called the atmospheric line. When the communication is opened between the under side of this piston and one end of the cylinder of the engine, the piston will be forced upward by the pressure of the steam, or downward by that of the atmosphere, as the ope or the other preponderates; and if now the pencil be applied to the moving paper, it will describe, during one revolution of the engine, a figure, each point in the outline of which will show, by its distance above or below the atmospheric line, the pressure in that end of the cylinder, when the piston was at the corresponding point of its forward or return stroke. The spring which resists the motion of the Indicator piston is so proportioned in strength that a change of pressure of one pound on the square inch shall cause the pencil to move up or down a certain fractional part of an inch. The diagram thus described shows on inspection the following particulars, viz., what proportion of the boiler-pressure is obtained in the cylinder; how early in the stroke the highest pressure is 1RICHARDS' STEAM-ENGINE INDICATOR. 11 reached; how well it is maintained; at what point, and at what pressure, the steam is cut off; whether it is cut off sharply, or in what degree it is wiredrawn; at what point, and at what pressure it is released; in a non-condensing engine, whether it is freely discharged, or what proportion of it remains to exert a counter-pressure; in a condensing engine, the amount of the vacuum, and how quickly, or how gradually it is obtained; and in both classes of engines, whether, before the commencement of the stroke, there is any compression of the vapor remaining in the cylinder, and if so, at what point it commences, and to how high a pressure it rises. From the diagram, the mean pressure exerted during the stroke, to produce and to resist the motion of the piston, may be ascertained, and thus the engineer may come to know accurately the amount of power required to overt come the whole aggregate resistance on the engine, and also, by taking separate diagrams for each, the power required by each of the several resistances or classes of resistance separately.* He may en* This we find of great use when called to determine (as we often are) the power used by tenants. The landlord lets power to his tenants; it is fixed at a given price per horsepower. The question arises, how much the tenant does use. This is accurately determined. The practice is this: We take several diagrams, one from each end of the cylinder, when the engine is doing all the work, noting the number of revolutions being made when each pair is taken. Should there 12 RICHARDS' STEAM-ENGINE INDICATOR. deavor also to ascertain the causes of the various features presented in the diagram, and thus to learn the effect produced by this or that form or arrangement of parts, and to detect any imperfection in their construction or action. It must be borne in mind, that the Indicator shows only the pressure at each point of the stroke; to represent this faithfully is its sole office. It tells nothing about the causes which have determined the form of the figure which it describes. The engineer concludes what these are, as the result of a process of reasoning, and this is the point where errors are liable to be committed. be a difference of speed of the engine during the time of taking these diagrams it is noted on each pair, and arranged when worked up. These diagrams and the result we mark "all on;" then we stop tenant No. 1, throw off the belt that carries his work, take say three pairs of diagrams, and work them up. Now, as much As these are less than the average of those taken with "all on," so much we charge tenant No. 1. We then put his belt on and proceed with tenant No. 2, and charge him in the same manner. Thus we proceed with all. In making up'our accounts for each, and adding them, we find the aggregate will fall short of the gross of "all on." This is as it should be, from the well-known fact that the friction of the engine and intervening machinery decreases as the power required decreases, and vice versa. This amount of decrease or increase, as the case may be, we have found to vary from 5 per cent. to 8 per cent., depending on circumstances. Whatever it may be it should be charged to'the tenant. RICHARDS' STEAM-ENGINE INDICATOR. 13 Conclusions which seem obvious sometimes turn out to have been wrong, and the ability to form an accurate judgment, as to the causes of the peculiarities presented in a diagram, is one of the highest attainments of an engineer. The variety of diagrams given by different engines, and by the same engine under different circumstances, is endless; and there is perhaps nothing more instructive to the student of engineering, as there is nothing more interesting to the accomplished engineer, than their careful and comprehensive study, with a knowledge of the modifying circumstances under which each one was taken. Lines at first meaningless become full of meaning; that which scarcely arrested his attention, comes to possess an absorbing interest; he becomes acquainted with the innumerable variety of vicious forms, and learns the points and degrees, as well as the causes, of their departure from the single perfect form; he becomes familiar with the effects produced by different constructions and movements of parts, and competent to judge correctly as to the performance of engines, and to advise concerning changes, by which it may be improved; he ceases to be a mere imitator of material shapes, and learns to strive after the highest excellence, and, at the same time, to comprehend its conditions. No one at the present day can claim to be a mechanical engineer who has not become familiar with the use of the Indicator, and 14 RICHARDS' STEAM-ENGINE INDICATOR. skilful in turning to practical advantage the varied information which it furnishes. This brief summary of the uses of the Indicator would be incomplete without calling attention to the importance of applying it to boilers, as a means of testing the accuracy of the pressure-gauges, and to pumps, for the purpose of ascertaining the causes of any inefficiency in their action, and also to the condenser and the air pump of condensing engines. The diagram, No. 1, taken from one of the engines of a well-known steamship,* is introduced here to illustrate the action of the Indicator, as just described. The scale of the Indicator was twelve pounds to the inch. The line A B is the atmospheric line, and c D the line of perfect vacuum. The lines forming the outline of the diagram will be designated, for convenience of description, as follows:The line from a to b, the admission-line.'" b to c, the steam-line. (" c to d, the line or curve of expansion.;" d to e, the exhaust-line. " e to f, the line of counter-pressure. f to a, the compression-line. * The engines from which the diagrams here employed for illustration were taken, will not be mentioned, except in two or three exceptional cases; the object of this paper being, not to publish the comparative performance of different engines, but to give instruction to those who may require it, in the use of the Indicator. RICHARDS' STEAM-ENGINE INDICATOR. 15 The steam-line, does not in fact end at c, but at some unknown point beyond c. The diagram is divided bylines drawn perpendicular to the atmospheric line into ten equal parts, and also by lines drawn parallel with the atmospheric line at intervals of five pounds pressure. The object of these is to enable the engineer to observe more accurately the nature df the diagram, and to ascertain the mean pressure exerted during the stroke, the mode of doing which will be explained hereafter. The line c g is the theoretical expansion curve drawn from the point c. From an examination of this diagram, we conclude that the exhaust-port was covered at the point f, of the return stroke, and the vapor remaining in the cylinder was then compressed by the advance of the piston to a density, at the commencement of the forward stroke, of about five pounds above the atmosphere. The port was then opened for admission, and the pressure instantly rose to fourteen and a half pounds above the atmosphere. The port being opened wider and wider, this pressure was maintained behind the advancing piston to the point c, at which it began to fall, at first very slowly, from the gradual closing of the port by the cut-off valve. The point at which the port was covered cannot be identified. It was certainly, however, far beyond the point c, and strictly the steamline continues to the point of cut-off, however the pressure may fall before that point is reached. At 16 RICHARDS' STEAM-ENGINE INDICATOR. the point d, the pressure had fallen by expansion to two pounds above the atmosphere. Here the valve began to open communication with the condenser, and before the piston commenced its return stroke the pressure on this side of it fell to nearly ten. pounds below the atmosphere, and almost immediately after a vacuum of twelve pounds was formed; and when the return stroke was two-thirds accomplished, the counter-pressure suddenly fell half a pound lower, and this vacuum was maintained until the exhaust-port was closed at the point f. We shall refer to this diagram again, when on the subjects of calculating the power of the engine from the diagram, and of working steam expansively. OF TRUTH IN THE DIAGRAM., It is, of course, of the first importance that the diagram given by the Indicator shall be true. Causes of error appear at every point, and the degree of falsity arising from them increases greatly with an increase in the rate of revolution of the engine. It is not possible to be too critical in using the Indicator, especially at high speeds; the errors we are not conscious of are the ones sure to mislead us. The Conditions of a correct Diagram are-1st, that the movements of the paper shall coincide exactly with those of the piston; and, 2nd, that the RICHARDS' STEAM-ENGINE INDICATOR. 17 movements of the pencil shall simultaneously and precisely represent the changes of pressure in that end of the cylinder to which the Indicator is attached. 1st. Errors in the Motion of the Paper.-The common errors in communicating motion to the paper are of two kinds-those which arise out of the movements employed, and those which, when the movements are correct, are occasioned by a high velocity of the parts; but with proper care these may all be avoided. We shall mention them in detail presently, in connection with instructions for applying the Indicator. 2d. Errors in the Motion of the Pencil.-These are of a more serious nature. The spring may be accurate, but its unavoidable length and weakness, and its weight, joined to that of the piston and other attached parts, and the distance through which these must move, in order that the indications may be on a scale of sufficient magnitude, render it"impossible to obtain from engines which run at any considerable speed, with any form of Indicator hitherto in use, diagrams which can make any claim to accuracy. THE RICHARDS INDICATOR Is constructed on a plan by which it is found that these difficulties are quite avoided, and correct dia 18 RICHARDS' STEAM-ENGINE INDICATOR. grams are obtained under all circumstances. The principal distinguishing features of this instrument are a short and strong spring, a short motion of piston and light reciprocating parts, combined with a considerable area of cylinder, and an arrangement of levers and a parallel motion, for multiplying the motion of the piston in such a manner that the diagram is described in the usual way and of the ordinary size. The proportion between the motion of the piston and that of the pencil is a matter of discretion; that which has been adopted is 1 to 4, and the steadiness with which the indication is drawn by these instruments, even at the highest speeds of piston, leaves nothing to be desired. The diagrams numbered 2, 3, 4, 5, are fair samples of a large number taken from the locomotive "Eagle," on the London and South-Western Bailway, in April, 1863. In three of them, the pencil was held to the paper during a number of revolutions; in diagram No. 5 it passed over the paper only once and a half. They are introduced here to show the correct action of the instrument; we shall have occasion to consider them also as illustrations of working steam expansively. General Construction of the Indicator.-The parallel motion is made as compact as possible. For this purpose, a lever of the third order is employed to multiply the motion, and the extremities of RICHARDS" STEAM-ENGINE INDICATOR. 1 the line drawn by' the pencil are permitted to have a slight curvature, which considerably reduces the length of the rods, and does not affect the usefulness of the instrument, the curvature at the lower end being below any attainable vacuum, while the extremity of the scale above is very rarely employed. The Indicators are made of a uniform size; the area of. the cylinder is one-half of a square inch, its diameter being.7979 of an inch. The piston is not fitted quite steam-tight, but is permitted to leak a little; this renders its action more nearly frictionless, and does not at all affect the pressure on either side of it. The motion of the piston is. A of an inch, and the motion of the pencil, or extreme. height of the diagram, is 3- inches. The paper cylinder is 2 inches in diameter, and the length of the diagram may be 5i inches, if this extent of motion is given to the cord. The diagram is drawn by a pointed brass wire on metallic paper. This is a great improvement over the pencil; the point lasts a long time, cannot be broken off, and is readily sharpened, and the diagram is indelible.* The steam-passage has two or three times the area usu* We have used the metallic pencil with the prepared me. tallic paper. It works well, but the difficulty of procuring it, together with its high cost, renders it objectionable. We use heavy, unsized paper with a Faber No. 4 pencil; we succeed in getting good, distinct diagrams, with lines sufficiently fine to measure correctly. 20 RICHARDS' STEAM-ENGINE INDICATOR. ally given to it. The stem of the Indicator is conical, and fits in a corresponding seat in the stopcock, where it is held by a peculiar coupling, shown in section in the accompanying cut of the Indicator. This arrangement permits the Indicator to be turned round, so as to stand in any desired position, when, the coupling being turned forward, the difference in the pitch of the screws draws the cone firmly into its seat; and when the coupling is turned backward, the cone is by the same means started from its seat. The leading pulleys may be turned by some pressure, to give any desired direction to the cord, and will remain where they are set. By these means the Indicator can be readily attached in almost any situation. The Springs.-In order to adapt this Indicator for use on engines of every class, springs are made for it to 4 different scales, as follows: No. 16, which is graduated 16 lbs. to the inch. 35 lbs. No. 20, " " 20 " " 56" No, 30, " " 30 " ".. 75" No. 40, " " 40 " " 105 All the above will also indicate 15 lbs. below the atmospheric line. RICHARDS' STEAM-ENGINE INDICATOR. 21 PRACTICAL DIRECTIONS FOR APPLYING AND TAKING CARE OF THE INDICATOR. I. OF ATTACHING THE INDICATOR. When it is practicable, diagrams should be taken from each end of the cylinder. The assumption commonly made, that if the valves are set equal, the diagram from one end will be like that from the other, will be shown by this instrument to be erroneous. This is owing to the difference in the speed of the piston at the opposite ends of the cylinder, which is, at the outer end of a directacting engine, from one-sixth to one-third greater than at the crank end, the difference varying according to the degree of angular vibration of the connecting rod. In side-lever, or beam-engines, these proportions are reversed, and the speed of the piston is greater at the upper end of the cylinder. Often, also, there is a difference in the lengths of the thoroughfares, and in the lead, or the amount of opening, or the point of closing; and many times the valves are supposed to be correctly set when this Indicator will show that they are not. These, and many other causes, will make a difference in the diagrams obtained from the opposite sides of the piston. Pipes to be avoided.-The Indicator should be fixed close to the cylinder, especially on engines working at high speeds. If pipes must be used, 22 RICHARDS' STEAM-ENGINE INDICATOR. they should not be smaller than half an inch in diameter, and five-eighths in the bends, and as short and direct as possible. Any engineer can satisfy himself with this instrument that each inch of pipe occasions a perceptible fall of pressure between the engine and the Indicator, varying according to its size and number of bends and the speed of the piston. Diagrams have been known to show, from this cause alone, forty per cent. less pressure than was actually in the cylinder. Where to connect the Indicator.-On vertical cylinders, for the upper end, the Indicator-cock is usually screwed into the cover, where the oil-cup is set, this being removed for the purpose. For the lower end, it is necessary to drill into the side of the cylinder, at a convenient point in the space between the cylinder bottom and the piston, when on the centre, and screw in a short bent pipe, with a socket on the end to receive the Indicator-cock. The Indicator can be used in a horizontal position; but it will be found much more convenient to put in a bent pipe, and set it vertical. Sometimes it will be necessary to drill in the side of the cylinder at the upper end also, especially in double-cylinder engines having parallel motions, when the Indicator cannot generally be set on the covers. Care must be taken that the piston does not cover the hole when on thei centre. No putty is necessary to make these s1riai joints, and it should never be used, as RICHARDS* STEAM-ENGINE INDICATOR. 23 it is liable to clog the instrument. If the screw fits loosely, a few threads of cotton wound round the stem will prevent the escape of steam. Objections are sometimes made to drilling a cylinder or its heads, for the reason that the borings as the drill passes through will be left in the cylinder and likely to scratch it; this, with a little management, can be wholly prevented, by letting' a little steam on as the drill enters, which will blow it outwards. On horizontal engines, the best place for the Indicator is on the top or upper side, at each end; if it cannot be placed there, bent pipes may be screwed into the covers or into the side of the cylinder. In other respects follow the directions given for vertical engines. The Indicator should never be set to communicate with the thoroughfares. The current of steam past the end of the pipe or the hole reduces the pressure in the instrument, and the, diagram given is utterly worthless, as any engineer can readily ascertain by making the experiment. On oscillating cylinders care must be taken to set the instrument in such a position that the motion of the cylinder will not have the effect to throw the pencil to and from the paper. The stopcock being screwed firmly to its place, screw the Indicator down to its seat, turning it to the most convenient position,, and make it fast by turning the coupling; then move the guiding pulleys to their proper position to receive the cord, and the instrument is in readiness for use. 24 RICHARDS' STEAM-ENGINE INDICATOR. II. OF GIVING MOTION TO THE PAPER. The Drum the best Means.-The revolution of a drum is probably the most correct as well as convenient method of giving motion to the paper. It may be supposed that a flat slide, worked by positive means, would have a perfectly accurate motion; but, in fact, at high velocities, where alone any trouble is met with, the difficulties involved in its use are more troublesome than those presented by the cylinder. In most cases the connecting-rod must necessarily be somewhat long; it must not tremble, or the line on the paper will be tremulous, and the weight required for stiffness, joined to the weight of the slide, causes a momentum, which, if the rod is worked by a vibrating arm, will give to the paper, on each centre, a motion opposite to that of the piston of the engine; and precisely at these points it is of the greatest consequence that the two motions shall coincide. In the use of the cylinder at any speed, the question of obtaining a positive motion, if there is no elasticity in the cord or the parts to which it is connected, is simply one of proportion between the momentum of the revolving parts and the strength of the spring by which this is resisted. In this Indicator these parts are made as light as possible consistently with other requirements, and the spring is of such strength that they may be reciz procated. from 250 to 300 times per minute, without RICHARDS' STEAM-ENGINE INDICATOR. 25 any increase in the length of the diagram, and of course, therefore, without any error in the motion. There is no difference in the construction of these Indicators in this respect, it being intended that every instrument shall be applicable to any engine. From what Points to derive the, Motion.-This may be taken from any part of the engine which has a motion coincident with that of the piston. For a beam-engine a point on the beam, or beam-centre, or on the parallel-motion rods where these are employed, will give the proper motion; but care must be taken that the cord be so led off, that when the engine is on the half stroke it will be at right angles to whatever gives it motion (a requirement too often omitted); afterwards its direction of motion may be changed as required, always taking care, however, to use as few carrying pulleys as possible, and the shortest possible cord, which sh6uld be of linen, size No. 3; it should be well stretche'd by suspending a weight to it for several days. In some cases it is most convenient to take the motion from a point on the end of the revolving shaft; this is frequently the case on horizontal engines, working at high speeds, because then the motion does not need to be reduced. Exact accuracy cannot be got in this way, however, without employing a moving slide, and connecting it with the pin in the end of the shaft by a rod or cord of such length that its angular vibration. shall be the 2 26 RICHARDS' STEAM-ENGINE INDICATOR. same a~ that of the connecting-rod. This will be found generally a troublesome matter; and the engineer will probably prefer in most cases to disregard the error resulting from its omission —which is, that the motion of the paper will be more nearly equal at the two ends of the stroke, being slower than that of the piston at the one end, and faster at the other. The crank or pin from which the cord receives its motion must be on its centre relatively to the direction of the cord, whatever that direction may be, precisely when the crank of the engine is on its centre. If this requirement is not carefully attended to, the diagram will be worthless. Generally, on horizontal engines, the motion of the paper is taken from the cross-head. In an engine-room, a strip of board may be suspended from the ceiling, or carried off horizontally in such a manner'as to permit it to swing backward and forward edgeways by the side of the guides, and motion may be given to it by a pin, secured firmly to the cross-head, and projecting through a slot in the board, in which it should fit nicely to prevent lost time on the centres. To save drilling and defacing the cross-head to insert a pin, we use a clamp made fast to the cross-head or some of its appendages by a set screw; a projecting pin plays in a slot in the board, or if preferred, a short connecting rod may be used to make the connection. The board must hang plumb when the piston is in RICHARDS' STEAM-ENGINE INDICATOR. 27 the middle of its stroke, or if horizontal at right angles. The cord may be connected to' this strip of board at a point sufficiently near to its point of suspension-to give' the required reduction of motion for the paper, and must be led off in a horizontal direction, and then over one or more pulleys in any required direction to the Indicator. At high speeds, however, pulleys should be avoided. On portable engines, the motion may be attained in the manner just described, the lever swinging from a pin supported- in a standard about two feet in height, set on one of the guide-bars. On locomotives having outside connections, the motion must be taken from the cross-head. It is indispensably necessary to use only a short direct cord, free from elasticity, and connected to a point the motion of which is reduced from that of the cross-head by positive means. Care must be taken also so to proportion the parts employed for this purpose, that the point at which the 9ord! is connected shall have a positive motion without any fling, a matter not by any means free from difficulty at 250 revolutions per minute. A rock-shaft, turning in bushings, supported by two angle iron standards, precisely over the mid-position of that point of the cross-head from which the motion is derived, affords perhaps the best means of reducing the motion. A long-arm is worked by the cross-head and a short-arm gives motion to the cord. The short-arm must be keyed, in such a po 28 RICHARDS' STEAM-ENGINE INDICATOR. sition that when the piston is in the middle of its stroke it will stand at right angles with the direction of the cord, whatever that may be. The direction of the cord may form any necessary angle with the horizontal line, but must be at right angles with the rock-shaft. On locomotives having inside connections, and a single pair of driving-wheels, where it is practicable, it will be found to be the better way to take the motion from a pin set in the end of the shaft, and to communicate it by a connecting-rod to a point convenient for attaching the cord. The parts should be all substantially made; the momentum of the connecting-rod will be perfectly resisted by the pin. On oscillating engines, the motion may be taken from the brasses at the end of the piston-rod. If the stroke is long, it is sometimes difficult to reduce this motion to that required for the paper, and in such cases it is necessary to tale the motion from an eccentric on the main shaft, to a point as near as possible to the trunnion, and thence to communicate it to the Indicator. In all these connections, it is of the first consequence that there be no lost time, which will require to be made up on every centre, and will thus cause the paper to stand still while the piston is moving. Pulleys of different diameters on the same spindle have often been used as a means of reducing the motion from that of the cross-head, but we do RICHARDS' STEAM-ENGINE INDICATOR. 29 not recommend them; at high speeds it is very difficult to make them answer. The experience of the careful operator will teach him to guard against the various causes of error here mentioned, and others which will arise in the great diversity of situations in which the Indicator is used, and the effects of which are the more mischievous because often the diagram itself furnishes no means of detecting them. The mathematician will perceive that perfect accuracy of motion is attained by only a very few of the methods here suggested. Most of them are only approximately accurate, but they are the best which can be readily employed,'and the errors which they involve are too slight to be of practical moment. For the professional engineer, of course, directions are unnecessary. III. HOW TO TAKE A DIAGRAM. To fix the Paper.-Take the outer cylinder off from the instrument, secure the lower edge of the paper, near the corner, by one spring, then bend the paper round the cylinder, and insert the other corner between the springs. The paper should be long enough to let each end project at least half an inch between the springs. Take the two projecting ends with the thumb and finger, and draw the paper down, taking care that it lies quite smooth and tight, and that the corners come fairly together, and replace the cylinder. 30 RICHARDS' STEAM-ENGINE INDICATOR. To connect the Cord.-The Indicator having been attached, and the correct motion obtained for the drum, and the paper fixed, the next thing is to see that the cord is of the proper length to bring the diagram in its right place on the paper-that is, midway between the springs which hold the paper on the drum. In order to connect and disconnect readily, the short cord on the Indicator is furnished with a hook, and at the end of the cord coming from the engine, a running loop may be rove in a thin strip of metal, in the manner shown in the following cut, by which it can be readily adjusted to the proper length, and taken up from time to time, as it may become stretched by use. On highspeed engines, it is as well, instead of using this, to adjust the cord and take up the stretching, as it takes place, by tying knots in the cord. If the cord becomes wet and shrinks, the knots may need to be untied, but this rarely happens. The length of the cdiagram drawn at high speeds should not exceed four and a half inches, to allow changes in' the length of the cord to take place to some extent, without causing the drum to revolve to the limit of its motion in either direction. On the other hand, the diagram should never be drawn shorter than is necessary for this purpose. RICHARDS' STEAM-ENGINE INDICATOR. 31 To take the Diagram. —Everything being in readiness, turn the key of the stopcock to a vertical position, and let the piston of the Indicator play for. a few moments, while the instrument becomes warmed. Then turn the key horizontally to the position in which the communication is opened between the under side of the piston and the atmosphere, hook on the cord and draw the atmospheric line. Then turn the key back to its vertical position, and take the diagram. When the key stands vertical, the communication with the cylinder is wide open, and care should be observed that it does stand in that position whenever a diagram is taken, so that this communication shall not be in the least obstructed. To apply the pencil to the paper, take the end of the longer brass arm with the thumb and forefinger of the left hand, and touch the point as gently as possible, holding it during one revolution of the engine, or during several revolutions if desired. There is no spring to press the point to the paper, except for oscillating cylinders; the operator, after admitting the steam, waits as long as he pleases before taking the diagram, and touches the pencil to the paper as lightly as he chooses. Any one, by taking a little pains, will become enabled to perform this operation with much delicacy. As the hand of the operator cannot follow the motions of an oscillating'cylinder, it is necessary that the point be held to the paper by a light spring, and instru 32 RICHARDS'STEAM-ENGINE INDICATOR. ments to be used on engines of this class are furnished with one accordingly. Diagrams should not be taken from an engine until some time after starting, so that the water condensed in warming the cylinder, etc., shall have passed away. Water in the cylinder in excess always distorts the diagram, and sometimes into very singular forms. The drip-cocks should be shut when diagrams are being taken, unless the boiler is priming. If when a new instrument is first applied the line should show a little evidence of friction, let the piston continue in action for a short time, and this will disappear.* As soon as the diagram is taken, unhook the cord; the paper cylinder should- not be kept in motion unnecessarily, it only wears out the spring, especially at high velocities. Then remove the paper, and minute on the back of it at once as many of the following particulars as you have the means of ascertaining, viz:The date of taking the diagram, and scale of the Indicator. * Thus, by the motion of the pencil up and down, and the paper from right to left, and left to right, we transfer the pressure of the steam and vacuum (if there be any), and the movement of the piston to the paper, giving us a map or diagram of the action required to move the load at any and all points of the stroke, from which the power exerted may be computed and the condition of the internal action seen. RICHARDS' STEAM-ENGINE INDICATOR. 33 The engine from which the diagram is taken, which end, and which engine, if one of a pair. The length of the stroke, the diameter of the cylinder, and the number of double strokes per minute..The size of the ports, the kind of valve employed, the lap and lead of the valve, and the exhaust lead. The amount of the waste-room, in clearance and thoroughfares, adds to the length of the cylinder. The pressure of steam in the boiler, the diameter and length of the pipe, the size and position'of the throttle (if any), and the point of cut-off. On a locomotive, the diameter of the drivingwheels, and the size of the blast orifice, the weight of the train, and the gradient, or curve. On a condensing-engine, the vacuum by the gauge, the kind of condenses employed, the quantity of water used for one stroke of the engine, its temperature and that of the discharge, the size of the air-pump and length of its stroke, whether single or double acting, and, if driven independently of the engine, the number of its strokes per minute, and the height of the barometer. The description of boiler used, the temperature of the feed-water, the consumption of fuel and of water per hour, and whether the boilers, pipes, and engine are protected from loss of heat by radiation, and if so to what extent. In addition to these, there are often special circumstances which should be noted. 2* 84 RICHARDS' STEAM-ENGINE INDICATOR. IV. HOW TO KEEP THE INDICATOR. IN ORDER. Having the attachments made; before we admit steam to the instrument, we open the cocks and blow through the connections to clear them from any foreign matter, that it may not enter and injure the instruments. The Indicator will not continue to work well, unless it is kept in good order. When used, it generally becomes filled with water, which will rust and thus weaken the spring, and the steam often contains impurities and grit, a portion of which is lodged in it. After the Indicator has been used,' and before putting it up, unscrew the cover of the cylinder case, and draw off the upper ferule, with the pencil movement and the piston and spring attached, empty the water from the cylinder case, carefully clean and dry all the parts, and replace them, lubricating the cylinder with -a few drops of oil which is entirely free from gum.* The cylin*The oil is very important; it should be of the purest kind, free from gum and all foreign matter. The porpoise oil we have found to answer all the requirements; it has wonderful ability to resist the action of steam and water. We have found the cylinder well lubricated after having taken a hundred diagrams. It has equal merit in preventing corrosion; hence it should be used on the springs, piston-rod, and arms. It costs high, but a small bottle of it will, if properly used, last for years. It can be obtained of any first-class clockmaker or dealer in clock materials. RICHARDS' STEAM-ENGINE INDICATOR. 35 der is not to be removed from the case under any circumstances; the operation above directed gives complete access to it. Sometimes the surfaces of the piston and cylinder become scratched or roughened by impurities in the steam, which will be detected at once in the diagram by the unsteadiness of the line. If this shows the existence of any obstruction to the perfectly free action of the Indicator, take the inlstrument apart, as for cleaning; take out the two screws at the top of the piston-rod connecting it with the pencil movement, and unscrew the spring from the piston and the cover; then replace the piston in the cylinder, after cleaning and lubricating them; screw on the cover to guide the stem, and rub the piston up and down in the cylinder, dt the same time revolving the stem between the thumb and finger. The surfaces will quickly wear each other smooth; no grinding or polishing material should be used; the piston should be taken out once or twice during the operation, and the surfaces cleaned. The piston, if dry, ought to drop perfectly free from every position. Before replacing, lift the levers, and let them fall, to see if their action also is entirely free. Then replace everything, taking care to screw the heads of the spring firmly up to the piston and cover. Before putting the piston in the cylinder, revolve it between the thumb and finger, to ascertain if the pins connecting it with the pencil movement turn 36 RICHARDS' STEAM-ENGINE INDICATOR. quite smoothly in the groove at the end of the stem. The paper cylinder requires to be lubricated occasionally with a drop or two of pure oil, applied at the end of the arbor, also the leading pulleys and the joints of the pencil movement. V. HOW TO CHANGE THE SPRINGS. The directions already given for' taking the instrument apart, for the purpose of smoothing the surfaces of the cylinder and piston, are sufficient also for changing the spring. Merely introduce another, instead of replacing the one removed. The lengths of the springs for the different scales are so proportioned to each other, that the pencil will always come to the proper position for drawing the atmospheric line. Be careful that the heads are, screwed up firmly to the piston and cover. The spring, which gives reaction to the paper cylinder, is liable to break after considerable use, especially on engines running at high speeds'; for which reason this cylinder should never be left to run unnecessarily. When this happens, a new spring can be readily inserted, as follows. Set the Indicator on the engine; if there is no other convenient means for holding it firmly, remove the cover of the spring case and the broken spring; then take out the screw, and remove the brass ring from the arbor. Screw the new spring to the brass ring, replace this on the arbor, and set the RICHARDS' STEAM-ENGINE INDICATOR. -37 screw firmly up to the head. Then coil the spring into the case, and hook the end on the rim; see that it is coiled in the same direction with the cord. If the spring has not sufficient strength to keep the cord quite tight, another coil must be given to it, but it should not be coiled any tighter than is necessary for this purpose. HOW TO ASCERTAIN THE POWER EXERTED BY THE'ENGINE. The custom was introduced by Watt, and has since been generally followed in England, to designate the size of engines in measures of "horse power." Watt ascertained by experiment that the power of London draught horses, exerted with ordinary continuance, was to lift 33,000 lbs. one foot in one minute, and this is now employed, wherever English measurements are used, as the unit of measurement of the. actual power of steam engines. The Indicator furnishes one of the data for ascertaiing, the power exerted by the steam-engine, namely, the mean or average pressure of steam during the stroke, on each square- inch of the piston; or, more accurately, the excess of pressure on the acting side of the piston to produce motion, over that on the opposite side to resist it. This being multiplied: into the whole number of square inches, and the product by the mean or average speed of the piston, in feet per minute, gives the 38 RICHARDS' STEAM-ENGINE INDICATOR. total number of pounds of force acting through one foot in a minute, which are called foot pounds, and by dividing this by 33,000, which is the unit for a horse power, we obtain the gross power of the engine in actual horse powers. In order to ascertain the effective power, however, there must be deducted from this the friction of the engine, or the power required to drive the engine alone at the same speed, which, except in the case of vessels with the wheels submerged, the Indicator generally enables us to ascertain; and also the increase in this friction which arises when the resistance is being overcome, which the Indicator does not show. The amount of this latter is not generally known with any accuracy; but we know that the percentage of loss from this cause diminishes as the size of the engine is enlarged, because the increase in the motion of the surfaces in contact is much slower than the increase in the area of the piston, and also that it varies according to the nature of the lubricating material employed, and the degree of completeness attained in the separation of the surfaces by means of it. Five per cent. is usually allowed for this increase of friction; but it may, in fact, be considerably more or less than this. On small engines, the.frictionbrake can be applied, to show the amount of effective power exerted, and a comparison of this with the gross power, and with the friction of the engine alone, as shown by the Indicator, will exhibit the increase of friction occasioned by different amounts RICHARDS' STEAM-ENGINE INDICATOR. 39 of resistance, and show the value of different lubricants, and the utility of extended wearing surfaces. We will now describe the mode of ascertaining from the diagram the mean pressures on the opposite sides of the piston, in condensing and in noncondensing engines. For this purpose, divide the diagram into any desired number of equal parts, by lines drawn perpendicular to the atmospheric line. Sometimes these divisions are made very numerous; but the usual practice is to make ten, which number is probably sufficient, unless great accuracy is desired, when twenty divisions may be made. A convenient instrument for facilitating this operation, saving time, and insuring accuracy, is furnished with these Indicators. It consists of a parallel ruler, of eleven bars of thin steel, and a small square. The perpendiculars are first drawn by the square at each end of the diagram, when, the outer edge of bar No. 1 being brought to the beginning, and the inner edge of bar No. 11 to the termination of the stroke, the dividing lines are drawn with a sharp-pointed pencil. If twenty divisions are desired, the intermediate lines for this purpose will also be readily drawn by means of this instrument, points being first marked in the middle of the outer divisions. It is an excellent practice to divide the diagram also by lines drawn parallel with the, atmospheric line, into equal divisions, each representing a certain number of pounds pressure, generally five or ten, and num 40 RICHARDS* STEAM-ENGINE INDICATOR. bered on the margin according to the scale of the Indicator; by which means the engineer is able to observe much more accurately the general nature of the diagram. The same instrument may be employed for this purpose. On diagrams from condensing engines, the line of perfect vacuum should be drawn at the bottom, and the line of the boiler pressure, as shown by the gauge, at the top.* The line of perfect vacuum varies in its distance from the atmospheric line, or, more correctly, the latter varies in its distance from the former, according to the pressure of the atmosphere, as. shown by the barometer, from 13.72 lbs. on the square inch when the mercury stands at 28 inches, to 15.19 lbs. when it stands at 31 inches (vide Table II.); and it should be drawn according to the fact, if this can be ascertained. The engineer should always have a good aneroid in his pocket. The pressure of the atmosphere is usually reckoned at 15 lbs., which, as a general rule, is too high, being correct only when the barometer stands at 30.6 inches; but the error is unimportant, and it is very convenient to avoid the use of a fraction, and to say that 30 lbs., 45 lbs., 60 lbs., * When accuracy is required, the steam-gauge should be tested by the Indicator, which may be done by stopping the engine on the centre, opening the steam-valve, and letting the full pressure on the instrument; when the indications of the two instruments may be compared and noted. RICHARDS' STEAM-ENGINE INDICATOR. 41 and so on, represent 2, 3, 4, 5, 6 atmospheres of pressure. The principal object of knowing the exact pressure of the atmosphere is, to ascertain the duty performed by the condenser and air-pump. The temperature of the discharge being known, the pressure of vapor inseparable from that temperature is also known (vide Table No., III.), and this being deducted from the actual pressure of the atmosphere, the remainder is the total attainable vacuum at that temperature. The areas of the diagram above and below the atmospheric line are usually calculated separately, to ascertain how effectually the resistance of the atmosphere is removed from the non-acting side of the piston, by those parts of the engine whose function this is. In case of engines working very expansively, however, the expansion curve crosses the atmospheric line, and sometimes at an early point of the stroke, as in diagram No. 10. In such cases, the whole space between the atmospheric line and the line of counter-pressure should be credited to. the condenser and air-pump; not, of course, to be considered in estimating the power exerted, but for ascertaining the degree of economy in the consumption of steam, which depends greatly on the amount of vacuum maintained. The lines having been accurately drawn as above directed, ascertain, by careful measurement with the scale, the mean pressure in each division, be 42 RICHARDS' STEAM-ENGINE INDICATOR. tween the atmospheric line and the upper line of the diagram, until this crosses the former, if it does so; add these together, and point off one place of decimals, or divide their sum by the number of divisions, if there are more than 10, and the quotient will be the mean pressure above the atmosphere during the stroke. Then repeat the process for the area between the atmospheric line, or the expansion curve after it has crossed this line, and the lower outline of the diagram. Add the two mean pressures so ascertained together, then find in Table No. I. the number of square inches in the surface of the piston, if you know the diameter, and multiply the pressure on one square inch by the number of square inches, and the product by the mean velocity of the piston, in feet per minute, and divide by 33,000, and the quotient will be the gross amount of horse-power exerted; or the power represented by the two areas of the diagram, above and below the atmospheric line, may be calculated separately. The strictly accurate mode of measurement is, to measure the pressure of steam from the line of perfect vacuum, when the line of 151bs. pressure will come near, or possibly coincide with, the atmospheric line; but it is more convenient, and answers all the purposes of a diagram better, to measure each way from the latter. The space between the steam line and the line of boiler pressure shows how much the pressure is RICHARDS' STEAM-ENGINE INDICATOR. 43 reduced in the' cylinder by throttling, or by the insufficient area of the ports, proper allowance being made for the difference of pressure necessary to give the rapid motion to the steam, and that between the line of counter-pressure and the line of perfect vacuutn shows the amount of resistance to the motion of the piston. In illustration of the foregoing directions, let it be required to find the effective power exerted by the pair of engines, from the upper end of one of which diagram No. I was taken, the diameter of cylinder being 95/, the stroke of the piston 10', and the number of revolutions 15 per minute. We will assume that the other engine would have given'the same diagram, which is possibly correct, and also that the lower ends of the cylinders would have given the'same, which is probably quite incorrect, because in side-lever, or beam engines, the speed of the piston at the lower end is slower, and therefore probably the pressure obtained is greater, than in the upper end, the motion of the valves being the same. The mean pressure of steam above the atmosphere was....................................... 9.82 lbs. The average vacuum was...................... 11.46" Total excess of pressure above the resistance was. 21.28 " The better mode of calculation in all cases is, to obtain first the number of horse-powers for 1 lb. to mean pressure on the square inch, as follows: 44 RICHARDS' STEAM-ENGINE INDICATOR. Multiply the number of square inches in the surface of the piston..................... 7088.2 By the speed of the piston in feet per minute. 300. 33.(000)2126(460.0(64.44 198 146 132 144 132 126 Which is the number of horse-powers exerted, for each pound of pressure during the stroke on 1 square inch of the piston.............................. 64.44 To obtain the gross power we multiply this by the average pressure per squareinch on the piston.... 21.28 51552 12888 6444 12888 Gross horse-powers exerted in one engine.... 1371.2i32 To obtain the effective power we must abstract from the multiplier............. 21.28 lbs. The pressure required to run the engine alone, which in so large an engine would probably not exceed.......... 1.00 lb. And the increase in this pressure required to overcome the increased friction when the resistance is being overcome, say 5 per cent...=.................. =1.06 " 2.06 lbs. Effective pressure on each square inch.. 19.2 2" Which multiplied by.................... 64.44 7.688 7688 7688 11532 Gives amount of effective horse-power... 1238.5368 Which multiplied by................. Gives.............. 2,477.0 horsepower as the effective power of the engines. RICHARDS' STEAM-ENGINE INDICATOR. 45 It will be observed that, by the above mode of calculation, we obtain for any engine, the speed of piston continuing the same, a constant number, which, multiplied by the mean pressure on a square inch, gives at once the amount of horse-power exerted at any time. On diagramsfrom non-condensing engines, the line of boiler pressure should be drawn at the top, and it is well to draw the line of perfect vacuum also, that the engineer may be able to see at a glance the quantity of steam consumed, and to compare with it the amount of work done. It is not possible that the back pressure resisting the motion of the piston shall be less than the pressure of the atmosphere, but it may be a great deal more, and very commonly in non-condensing engines the line of resistance is as much as 2 or 3 lbs. above the atmospheric line, though it is quite possible to avoid this excess altogether, as is shown in diagrams Nos. 6 and 9. The mean pressure is ascertained in the manner already directed for obtaining the pressure in condensing engines above the atmospheric line, and the power is calculated in the same way. For example, let it be required to find the effective power exerted by the engine from which diagram No. 6 was taken, the diameter of the cylinder being 18'', the stroke of the piston 42'', and the number of revolutions 60 per minute 46 RICHARDS* STEAM-ENGINE. INDICATOR. The mean pressure of steam during the stroke, above the resistance of the atmosphere, was....................... 25 lbs. From this we must subtract the pressure required to run the engine alone, say.. 1.75 lbs. And the increase of pressure required to overcome the increased friction when the load is on, estimated at 5 pet cent.. 1.25 " 3 lbs. Leaving effective pressure............... 22" The area of the piston is........... 254.5 square inches, Which, multiplied by the velocity of the piston..................... 420 feet per minute, 50900 10180 And divided by 33.(000)106(890.0(3.24 99 78 66 129 132 Gives 3.24 horse-powers, for each pound of pressure on I square inch during the stroke.................... 3.24 horse-powers, Multiplied by.......... 22 lbs. pressure, 648 648 Gives................. 71.28 effective horse-powers, assuming the pressure on the opposite side of the piston to have been. the same. RICHARDS' STEAM-ENGINE INDICATOR. 47 In the same manner, on stationary engines, the power shown by the frictional diagrams can be calculated, and by diagrams taken when the shafting only is being driven, and when greater or lesser proportions of the whole resistance are being overcome, and on vessels at different depths of immersion. Generally, engines will give the same figures at each revolution, the pencil retracing the same line so long as the resistance continues the same; but sometimes this is not the case, as in the engine from which the diagram just calculated was taken, where are shown four distinct expansion curves. In such cases care must be taken to obtain the average diagram. Also, in comparing the pressures required to overcome different resistances, it is essential that the speed of the engine in each case be the same, a requirement often disregarded. In all calculations of power from the diagram, it is assumed, and correctly so, that the value of each unit of motion of the piston is the same, whether measured at the extremes or in the middle of the stroke. The motion of the crank should be uniform; and if this is the case, the divisions of the time occupied in a revolution can be accurately measured on the circle which it describes. The motion of the piston, on the contrary, changes at every point of the stroke. At the instant when the crank is on the centre it is at rest; then its speed, at fst infinitely slow, becomes gradually acceler 48 RICHARDS' STEAM-ENGINE INDICATOR. ated, until, at the point where the direction of motion of the piston and that of the crank-pin coincides, the velocities of the two are equal, and for some distance before reaching and after passing this point they differ but little; then its motion is gradually retarded, until on the opposite centre it is at rest again. TO MEASURE FROM THE DIAGRAM THE AMOUNT OF STEAM CONSUMED. For this purpose, draw the line of perfect vacuuim, if not precisely known, at 14.7 lbs. below the atmospheric line. Ascertain how much the clearance and the thoroughfare add to the length of the cylinder at one end, and add a proportionate quantity to the length of the diagram by a line drawn perpendicular to the atmospheric line, at the proper distance from the admission line. Then ascertain the,point in the stroke at which the steam is released, and the pressure in the cylinder at that point. Multiply this pressure, reckoned from the line of perfect vacuum (and which must be taken before the exhaust-port has been opened), by the sectional area of the cylinder in square inches, and the product by the length of the stroke in inches, up to the point at which the steam was released, and including the addition for the clearance and thoroughfare, and divide by 14.7, and the quotient will be the number of cubic inches of steam, at the RICHARDS' STEAM-ENGINE INDICATOR. 49 pressure of the atmosphere, discharged from the cylinder at a single stroke. If the valves do not leak, and there is nb water with the steam, the cubic contents of the cylinder multiplied by the pressure, at the point of cut-off, should equal the cubic contents multiplied by the pressure, at the point of release, and in a compound engine the cubic contents of each cylinder multiplied by the pressure, at the point of release, should give the same result. Multiply this by the number of strokes in an hour, and divide the product by 1728 to reduce the cubic inches to cubic feet, and the quotient again by 1700, to reduce the steam at atmospheric pressum to water, and the result will be the number of cubic feet of water used per hour; multiply this by 62.5 for pounds, and divide the product by 8.33 lbs. for wine gallons. The supply of water to the boilers will need to be greater than the quantity thus ascertained, and the excess required will measure the aggregate loss from all causes, including leakage, priming, blowing off, and radiation from the cylinder and pipes where the water of condensation does not flow back into the boiler. It is essential, of course, that the diagram measured shall represent the uniform power exerted, or the mean power, if it is subject to variations. The detection in this manner of losses of heat, from occult causes, is one of the most remarkable and important services which have been rendered by the Indicator. It has been proved in some cases 3 50 RICHARDS* STEAM-ENGINE INDICATOR. that nearly or quite twice the volume of steam must have entered the cylinder at every opening of the ports, either in the form of steam or of water already condensed, that existed in the form of steam at the point of cut-off. The field here presented is one of the most useful in which the Indicator can be employed. OBSERVATIONS ON THE SEVERAL LINES OF THE DIAGRAM. In order to point out clearly the principal points of excellence and defect in the action of engines, which are made known by the Indicator, it will be best to consider each line of the diagram separately, beginning at the commencement of the stroke. I. THE ADMISSION-LINE. At low pressures of steam this line may be very nearly vertical, especially when the opening of the ports is preceded by considerable compression of the steam in the cylinder, as in diagram No. 1. Diagram No. 13, also taken from a celebrated steamship, shows a more gradual opening, but not preceded by any compression. At high pressures it is important to avoid the shock of the full force of the steam on the centre, especially when there has been no compression..Diagrams Nos. 6 and 7, from non-condensing engines, show a moderate advance of the piston, and, the former especially, a RICHARDS' STEAM-ENGINE INDICATOR. 51 considerable movement of the crank, while the pressure was being attained in the cylinder, the latter with and the former without precedent compression. These are all excellent admission-lines. The direction of this line is determined by the amount of lead given to the valve, for which no general rule can be laid down. It depends upon the speed of the piston, the proportion between the area of the ports and that of the cylinder, the rapidity or slowness of the opening movement, and the density of the steam already in the cylinder at the instant of opening. The proper lead can be ascertained only by the application of the Indicator. Without its assistance the best judgement is liable to err in a case presenting novel conditions. By the best judgment is meant a judgment formed by careful comparison of the lead given with the admission-line drawn by the Indicator, in a wide diversity of cases. II. THE STEAB-LINE. Here we find engines divided into four classes, namely1. Those in which the valves have an invariable motion, without any or with only very trifling lap, causing the port to remain open, or, technically, the steam to follow the piston, quite or nearly to the end of the stroke. 52 RICHARDS' STEAM-ENGINE INDICATOR. 2. Those in which the valves have also an invariable motion, but with more or less lap, causing the steam to be cut off at a certain fixed point of the stroke. 3. Those in which the point of cut-off may be varied by hand, either by means of the link motion or of an independent cut-off gear; and, 4. Those in which the point of cut-off is adjusted by the action of the governor, according to the changes either in the pressure of steam or the resistance to be overcome. In the first two classes, when less than the full pressure is required in the cylinder, the governor or the engineer adjusts the pressure by changing the position of the regulating valve. In the third class the regulating valve may be employed for this purpose, but the more usual and better way is to run such engines with this valve entirely open, and to adjust the mean pressure in the cylinder by changing the point of cut-off. Engines df the fourth class have no regulating valve, but the full attainable pressure of steam is admitted to the cylinder. The action of the regulating valve varies the position of the steam line upward or downward, to that distance from the atmospheric line which gives the mean pressure required. The action of the cut-off gear, on the contrary, varies its length for the same purpose. In engines in which the steam follows to the end, or nearly to the end, of the RICHARDS STEAM-ENGINE INDICATOR. 53 stroke, and indeed in all cases where the pressure is reduced between the boiler and cylinder by the action of the regulating valve, it is a imatter of very little interest what the steam-line may be. Not only its distance from the atmospheric line, but also., its direction, is changed by every change in the position of the regulating valve, so that it is not at all a fit subject for consideration. In engines which have no regulating valve, or where it is not employed, as in marine engines except in rough weather, the steam-line should approach nearly to the line of boiler pressure, and should be parallel with this line up to the point of release or cut-off. Diagrams Nos. 1, 6, 8, 9, afford examples of correct steam-lines, except that in No. 1 it is not continued parallel nearly up to the point of cut-off. Diagram No. 10 shows a slight fall of the steam-line as the piston advanced, but the point of cut-off is well shown. Diagram No. 12 from a marine condensing engine, at 336 feet travel of piston per minute; and Nos. 2, 3, 4, and 5, from a locomotive, at 730, 820, and 950 feet travel of piston per minute, afford, on the contrary, examples of bad steam-lines. Diagrams Nos. 15 and 16 are good admission and steam lines. Locomotive diagrams Nos. 19, 20, and 21, are remarkably good steam and admission lines. In No. 22, steam-line falls off slightly. The boiler pressure is very nearly attained at the commencement of'the stroke, in the first case, by lead given to the valve, and in 4 RICHARDS' STEAM-ENGINE INDICATOR. others by lead superadded to excessive compression; but as the piston advances, the pressure falls with great rapidity, and the point at which the port was closed there is no means of discovering. In all these cases the passage of steam to the valvechamber was entirely unimpeded. The nature of the steam-line depends principally on the proportion between the area of the ports, supposing them to be, as they ought, the smallest passages through which the steam is taken, and the cubical capacity of cylinder to be filled in a given time. A given cubical capacity may be formed in the same time by the slow advance of the piston in a larger cylinder, or by its more rapid advance in a smaller one. The sectional area of cylinder and the speed of the piston must be equally considered in determining the area of the ports, as they are equal elements in determining the capacity of cylinder to be filled. While, therefore, very high velocity of piston does not render impossible the attaining of a correct steam-line, still the size of port required for this purpose becomes so considerable, and the amount of power absorbed in working the valves, under the pressure which is generally associated with high speed of piston, is already so serious, that with the present form of valve in use-on locomotives, for example-it is better probably to submit to the defect at high velocities, than to attempt to mend it by enlargement. Improvement in this feature can be looked for only from a radical change LRICHARDS' STEAM-ENGINE INDICATOR. 55 in the valves and movements. It should be observed, however, that the velocity of piston at which diagrams Nos. 7 and 8 were drawn was 600 feet per minute. Another cause often contributes largely to injure the steam-line, especially in condensing engines-namely, the condensation of the steam on entering the cylinder; and to this the enormous fall of pressure in diagram No. 12 must undoubtedly be in part attributed, the smallness of the ports not being sufficient to account for it. There is obviously a point beyond which expansion can not be advantageously carried, because it is possible to cut the steam off so early that even with the highest pressure the engine will not perform any duty at all, but only run itself. Of cburse the power absorbed in running the engine should be only a small percentage of the gross power exerted. But there is also another limitation. The loss of heat by radiation and conduction, external and internal, is far greater than was till lately generally supposed. It is possible to protect pretty thoroughly against external radiation; but against internal radiation, which is so much greater than the other, as the capacity for heat of the exhaust steam, at the density it may have, is greater than that of the atmosphere, it is not possible to protect at all, and the earlier the steam.is cut off, the greater is the proportionate time during which the exposed surfaces are being cooled, and the smaller the quantity of steam admitted from which they 56 RICHARDS' STEAM-ENGINE INDICATOR. must be warmed again.* The phenomenon of a higher terminal pressure, in cylinders working steam expansively, than the law of the gases could account for, was generally explained, until quite recently, by supposing that the valves leaked; but when it was found to be universal, and to be most remarkable where the steam was most charged with moisture, thoughtful men were not long in detecting the true cause. The temperature of this moisture, as it enters the cylinder, is the same as that of the steam, and being in great part relieved from pressure by the expansion, it will instantly assume the gaseous form, provided the heat, which must be rendered latent on its change of state, is furnished. This is abstracted from the surfaces with which the particles of moisture come in contact, and the excess of -terminal pressure above that which should exist measures the heat thus lost, and which must be regained at the commencement of the next stroke from the entering steam. If the steam enters the cylinder nearly dry, this process, when the cylinder becomes heated, soon reaches a very moderate point, as is illustrated in diagram No. 6, where the theoretical curve is closely approximated to. Diagrams No. 7 and 8, on the * The recent experiments of Professor Tyndall reveal the astounding fact, that the power of aqueous vapor, at the pressure of the atmosphere, to absorb heat, is 6,000 times greater than that of dry air. RICHARDS' STEAM-ENGINE INDICATOR. 57 contrary, being taken at the Great Exhibition of 1862, where the steam was charged with moisture in an excessive degree, show a great amount of re-evaporation to have taken place, as the pressure fell in the cylinder. The best means at present known for diminishing the loss from this cause is, to dry the steam by moderate superheating, perhaps sufficient to affect the thermometer but very slightly, since every atom of moisture must change its state to steam before the temperature can rise above that due to the pressure. The height of the terminal pressure, as shown by the Indicator, above that which the law of Mariotte and the law of contraction of gases by cooling call for, affords some indication of the loss from this cause. If the curve drawn could agree with the requirements of these laws, there would be demonstrably no loss at all; but this is not attainable. Indeed, the higher temperature of the cylinder would probably affect sensibly the fall of pressure, even if the steam was perfectly anhydrous. It is obvious, that the percentage of loss will be diminished, other circumstances being the same, in proportion as the speed of piston is increased, the -actual loss continuing the same, but the power exerted becoming greater. Whether the employment of two cylinders enables this loss to be avoided to a greater extent than it can be in a single cylinder, must at present be regarded as an open question, 3* 58 RICHARDS' STEAM-ENGINE INDICATOR. and is one the discussion of which is foreign to the purpose of this work. To expand steam properly, it is essential that it be cut off instantaneously-that is, that the port shall be closed so quickly, that the pressure shall not fall in the cylinder, from the advance of the piston during the operation of closing. This Indicator enables us to pronounce unerringly upon the value of every means which is employed to effect this object. Diagram No. 6 shows unquestionably the closest approximation to this requirement. It was taken from an engine in the city of New York, of the celebrated style known as the Corliss Engine, which is extensively used in the eastern part of the United States for stationary purposes. The speed of piston of this engine was 420 feet per minute. Diagrams 9 and 14 show the cut-off made by the Sickels valve-gear, also in extensive use in the United States, especially on boats and vessels. No. 9 was taken from a non-condensing stationary engine, making 30 revolutions per minute, and No. 14 from the engines of a steamship at 16 revolutions per minute. It is hardly necessary to add that these were not taken with the Richards Indicator. The theoretical expansion curves cannot be drawn on either of these diagrams, because the amount of waste room, which is considerable, from the nature of the valves employed, is not known. RICHARDS' STEAM-ENGINE INDICATOR. 59 The speed of piston in each was about 300 feet per minute. Diagrams Nos. 7 and 8 were taken from the Allen Engine at the Great Exhibition of 1862, at a speed of piston of 600 feet per minute. The pressure fell somewhat at this great speed, as the closing movement of the valve was being completed, giving a rounded corner. In Diagram No. 7 we find the expansion curve changed to a waving line. The pressure of steam was removed from the piston of the Indicator with such extreme suddenness that the reaction of the spring was necessarily violent; but the rounded, flowing nature of the oscillations show the action of the instrument to have been frictionless, and these gradually subside into the correct curve, which the mean of the oscillations gives throughout, as shown. Diagram No. 10, from the engines of a steamship, shows very superior action of the cut-off gear. The vice which is the opposite of this excellence is technically termed wiredrawing, and consists in a gradual fall of pressure in the cylinder, while the port is being closed. It is illustrated in various degrees in several of these diagrams, and is a source of serious loss. The object of cutting off is, to obtain. the greatest mean pressure with the lowest terminal pressure, and it is clear that the sharper the cut-off the more completely this object is attained. For example, in diagram No. 1, the steam expands to a pressure of 17 lbs. at the point 60 RICHARDS' STEAM-ENGINE INDICATOR. of release, and a mean pressure of 21.28 lbs. is exerted during the stroke; had it been cut off sharply at the point c, it would have expanded to a pressure of 9 lbs. at the point of release, describing the curve c g, and would have exerted a mean pressure of 15.87 lbs. But 21.28:15.87:17:12.67. The gain of steam from cutting off sharply would be then 12.67- 9=3.67 lbs., or 29 per cent. - But this is by no means the full amount of the gain, for so much less steam being to condense, 1 lb. better vacuum at least would have been formed, and the boilers would easily have maintained a pressure 5 lbs. higher, with much more moderated firing; so that the. full mean pressure of 21.28 lbs. would have been obtained by cutting off at the point c, and expanding to a terminal pressure of 10.5 lbs., a gain of 65 lbs., or 38 per cent., and improvements equal to this have by this single means been often realized in practice. The slide-valve in its best form wiredraws the steam considerably, unless a great travel is-given to it; the vicious practice of making the end V-shaped of course raises the loss from this cause to the very highest point. Diagram No. 14 shows the action of a single slide-valve with a serrated end, expressly contrived to wiredraw the steam as much more than it can be with the ordinary slide as possible. The mean pressure for different points of cut-off, may be found by RICHARDS' STEAM-ENGINE INDICATOR. 61 HYPERBOLICAL LOGARITHMS. RlLE.-Divide the length of the stroke by the length of the space into which the steam is admitted; find in Table No. IV. the logarithm of the number nearest to the quotient, to which add 1, the sum is the ratio of the gain; then find the terminal pressure, by dividing the initial pressure by the proportion of the stroke during which the steam is admitted, and multiply it by the logarithm + 1, found as above; the product will be the mean pressure through the stroke. EXAMPLE.-Suppose the length of the stroke to be 48 inches, the initial pressure to be 40 lbs. per square inch, and the steam to be cut off at 12 inches of the stroke, what will be the mean pressure? 48.12-=4., Hyp. log. of 4-=1.38629+1=2.38629. Then, 40 - 4 = 10 X 2.38629 = 23.8629 lbs., the mean pressure required. To find the initial pressure, add the atmospheric pressure, 15 lbs., to the pressure shown by the gauge, and from the mean pressure found as above subtract the counter-pressure, to ascertain the actual mean pressure exerted. Thus, in the above case, the gauge is supposed to show a pressure of 25 lbs. only, and if the calculation is being made for a condensing engine, the estimated loss from imperfect vacuum must be subtracted, and if for a non-condensing engine, the pressure of the atmosphere, and also any estimated counter-pressure above that, 62 RICHARDS' STEAM-ENGINE INDICATOB. must be subtracted from 23.8629, the mean pressure found by the calculation. The editor remarks that the above rule requires a little qualification, to be considered, correct. If the diagram shows the cut-off at ~ of the stroke, it does not follow that I is the grade of expansion, because the clearance has not been taken into account. EXAMPLE.-Suppose the length of the stroke to be 36"; initial pressure, to be 50 lbs. per square inch, and the steam to be cut off at 9" of the stroke, what will be the average pressure? 36.9=4. Hyp. Log. of 4=1.38629+1=2.38629. Then 50- 4=12.5 X 2.38-29.75, mean pressure required. This is correct without taking the clearance into account. Now, let us see what the result is, when we add the clearance in the following examples; which is an actual case occuring in my practice during the week in which this was written. Engine 36" strokeX14" diameter, cutting off at i (9"); initial pressure 50 lbs. to the square inch; revolutions per minute, 80; clearance equal to a of the cubical contents of the part of the cylinder occupied by the piston stroke; or what is the same thing, y of the stroke, which is equal to 1.64", added to 9", the point of cut-off, is 10.64"; which being divided by the length of the stroke, gives us as a quotient 3.39, with a mean pressure of 32.59 lbs., as calculated by the above rule, adding the clearance. RICHARDS' STEAM-ENGINE INDICATOR. 63 Computing it by the same rule, without taking account of the clearance, the average pressure is 29.75 lbs. The result stands thus, computing with the clearance added................ 73.00 H. P. Without the clearance.......... 66.64 " " Difference..................... 6.36 In using Table No. V., the clearance must be added to get the correct mean pressure. IV. THE EXHAUST LINE AND THE LINE OF COUNTERPRESSURE may properly be considered together. It is, of course, desirable that the pressure of the steam be got rid of as completely as possible before the piston commences its return stroke. This is accomplished in a non-condensing engine by having the exhaust port and passages sufficiently large, and opening the port a sufficient time before the termination of the stroke, according to the density of the steam to be released and the velocity of the piston. The passages and pipes communicating with the atmosphere should be at least 50 per cent. larger than the ports, and as free from angles as possible. These requirements apply to condensing engines even more strongly, and in addition the condenser and air-pump must be able to maintain a proper vacuum. Diagrams Nos. 6 and 9 show no back-pressure at 64 RICHARDS' STEAM-ENGINE INDICATOR. all above the atmnosphere; diagrams Nos. 7 and 8 show a trifling back-pressure, attributable to the number of angles in the pipe necessary for connecting with the exhaust main at the Exhibition. Diagram No. 10 exhibits remarkable exhaust andt counter-pressure lines, obtained by a surface condenser, while No. 14 shows a great loss of power from imperfect vacuum, which was very partial at the best, and that only gradually obtained. V. THE COMPRESSION-LINE. This line, when it exists, is formed by the closing of the exhaust port at some point before the termination of the stroke, when the advancing piston compresses the confined steam to a density proportioned to the decrease of volume. This is illustrated in various degrees in several of the diagrams here shown. This action occasions a loss of power, but not much waste of steam, because the confined steam reacts on the return stroke with a force equal to that expended to compress it. It is useful on engines running at high velocities, by taking up gradually all looseness of the joints, and preventing the entire force of the steam from striking suddenly on the piston. Indeed, so important is the compression in preventing shocks on the centres in engines of this class, that probably locomotives could not be safely run without it. At the same time, the nature of the valve and gear employed on RICHARDS' STEAM-ENGINE INDICATOR. 65 this class of engines is such, that when cutting off very early the compression becomes excessive, involving an increase in the counter-pressure as the piston approaches the centre, which is quite unnecessary for any useful purpose, as is illustrated especially in diagram No. 4. At any ordinary number of revolutions per minute made by stationary or marine engines, the compression is not required, but in a moderate degree is never, perhaps, objectional.* * We do not think our author gives sufficient prominence to the advantages of compression; all engines require it, to a greater or less degree, depending, of course, on the speed and action of the valves. Our practice is, when we can control the exhaust valves, to compress from one-half to the whole initial pressure. A great point gained by compression is, to take up and store away, to assist on the return stroke the momentum of the piston and its connections with the crank; also, to fill the ports, passage-ways and clearance with exhaust steam, that we may not have to call on the boiler for it. It is certainly easier on the machine to take up slack motion of the joints thus gradually, than to take high steam on before reaching the centre. It is true, we reduce the capacity of the cylinder, but lose no steam; on the contrary, save the momentum of the reciprocating parts, by compressing a portion of the exhaust steam. When the slide-valve is used, it serves to partially balance it during the compression, thereby relieving it from friction and wear; a very important consideration, particularly on large valves. We prefer also to give very little or no steam lead; let the centre be past or nearly so, and the piston on its way back, before the steam is admitted. Many a crank and its connections have been broken, brasses 66 RICHARDS' STEAM-ENGINE INDICATOR. Diagram No. 12, not taken by the Richards Indicator, shows the usual form of diagram made by the double opening slide-valves now in general use on marine engines, with an independent cut-off valve. It will be observed, that the steam line is well maintained until the cut-off valve commences to close, when the pressure falls in an increasing ratio, probably to about the pressure indicated by the dots at the exact distance of closing. In the preparation of this paper, and in the selection of diagrams for its illustration, its object has been carefully kept in view, and while it is hoped that nothing has been'omitted which is essential to guide one before unacquainted with the Indicator in learning how to employ it correctly and intelligently, care has been taken to introduce only those topics, and to consider these, only to that extent which seemed to be necessary for this purpose. THE THEORETIC CURVE AND ITS USES. When we wish to know the condition of the internal working of an engine from a diagram we have taken from it, we make a perfect diagram worn out; heating, straining, and thumping, with all their concomitant evils, are daily caused by excessive steam lead; while, by compressing, the piston meets the thin elastic vapor remaining in the cylinder without a shock. It is technically called " cushioning," a most appropriate term. RICHARDS' STEAM-ENGINE INDICATOR. 67 around it so we may compare the one with the other. To do this: First, we ascertain the clearance between the piston and cover, also the areas of the ports and passage-ways clear back to the valves, both steam and exhaust, if they be separate. This we reduce to cubicdinches; we then get the cubic inches of the cylinder, or that part of it occupied by the stroke. Suppose the cylinder to be 14" diameter, and 36" stroke, it will contain 4541.94 cubic inches. Now, then, suppose our clearance is 206.44 cubic inches; this being divided into the contents of the stroke part of the cylinder, 4541.94, gives us 22, or is Ho part of it. We then add to the steam end of our diagram H part of its length. We then draw the line of perfect vacuum, whether it is a condensing engine or not. Then we space the whole in ten or more equal divisions, and erect lines (ordinates) on these spaces at right angles to our vacuum line, as shown in diagram No. 0. We will suppose we have 100 lbs. from A to B, Diagram No. 0, measuring from the line A E, and we cut off at C, which is f- or ~; by the law of expansion we should find (having expanded the steam -) the terminal pressure to be - of the pressure at C, the steam having expanded, a of the whole diagram. To find the point where the true curve should bisect the ordinates, we have numbered them from one to ten. We find the steam is cut off at 2, the next ordinate is 3, this being 3 the length of 2; hence, 68 RICHARDS' STEAM-ENGINE INDICATOR. we use 2 for the numerator and 3 for the denominator, and so on to the end, using for the nunderator the number of the ordinate where the steam is cut off, and for a denominator the number of the ordinate whose length we seek for. It often happens in spacing our diagrams that we can't find a space that will come right in both divisions of the diagram. In that case we space the parts from B to C into equal spaces, say from i" to I" each and then space the remainder the same; if it should run over the termination of the diagram it is of no importance, as after the curve is established the measure will be taken at the terminal point. The practical application of the theoretic curve is this: If we find it below the curve given by the instrument, we seek for the cause; if the engine cuts off short, say at i or less of the stroke, we may expect to find it a little, say a pound or two, above, at the last I or - of the stroke; this is accounted for by re-evaporation of the water condensed in the first part of the stroke. But, if it should run as it often does 10 or 15 pounds above, we conclude at once that the steam valve leaks. If we find the curve made by the instrument falling below the theoretic line, we are certain that either the piston or exhaust valve leaks, or maybe both. Diagram No. 15 was taken from an engine 24" X 48", making. 50 revolutions per minute. The steam valves are of the class known as balanced RICHARDS' STEAM-ENGINE INDICATOR. 69 poppet; the exhaust valves plain slide; point of cut-off adjusted by the action of the governor. Boiler pressure 48 lbs., steam pipe 6" diameter by 150' in length, the exhaust pipe 7" diameter by 175' long, scale of the instrument 30 lbs. to the inch; work being done, driving two trains of rolls, one of 20", the other of 16" diameter, with the concomitant and other machinery. It will be observed that the pressure in the cylinder fell off some 10 lbs. from the initial in the boiler, which is easily accounted for by the great length of the steam pipe. The 2 lbs. back pressure may be accounted for by the excessive length of the exhaust pipe; these defects are no fault of the engine. The card is a very excellent one; we rarely see its equal-no superiors, unless from an engine whose cylinder is jacketed with high steam. It will be seen that the lines given by the instrument vary but little from theoretic curve. The engine was constructed by Messrs. Woodruff & Beach, under Mr. Wm. Wright's patent. Diagram No. 16 was taken from the top of the cylinder of the steamer Newport; it will be recognized by the engineer as very good. The steam pressure on the boiler was by the gauge 22 lbs., vacuum per gauge 26". It will be seen that the diagram shows 20.5 lbs. The terminal point is supposed to be as should be;, yet, not having the data to calculate. the area of the clearance, passage-ways, 70 RICHARDS' STEAM-ENGINE INDICATOR. etc., we cannot ascertain where the terminal point should be, exactly. If the exhaust had opened a little earlier, it would have improved the vacuum at its commencement. Diagram No. 17 is from an engine 24" diameter X48" stroke, 60 revolutions per minute, Babcock & Wilcox patent; cylinder jacketed with steam from the boiler. The clearance is g of the stroke, boiler pressure 72 lbs. to square inch, scale 40"-1='. This engine is in the flouring mills of Messrs. Chapin, Miles & Co., Milwaukie. The work being done when the diagrams were taken was driving 4 runs of 4' 6" stones, and 2 runs of 4'; 180 revolutions per minute, with all the required flouring machinery as used in such mills. We give this data, that any one who wishes can make the theoretical curve; it will be found almost perfect. The expansion line, it will be noticed, is somewhat waved, which is incident to the high speed, high pressure, anl early opening of the valves. The terminal point of the expansion line will be found about 3 lbs. above the true line, caused by evaporation of water that went over with the steam. Another and unusual point is the very near approach of the pressure in the cylinder to that in the boiler, being but 2- lbs. less. When we take into consideration the speed of the piston, 480' per RICHARDS' STEAM-ENGINE INDICATOR. 71 minute, the result is extraordinary and seldom attained. Diagram No. 18; these cards were taken from a Wilcox air engine, and beautifully illustrate the delicate action of the Richards Indicator. Fig. 1 is from the working cylinder; the receiving line shows the induction valve to be slightly behind time; the pressure gradually reduces the first of the stroke, as the reservoir containing the compressed air is small, but as soon as the pump begins to deliver into the reservoir, the pressure continues uniform till the induction valve closes near the end of the stroke; the exhaust is free, and there is a slight compression at the end of the return stroke. Fig. 2 is from the pump, which is ~ of the capacity of the working cylinder, and shows the gradual increase of pressure as the piston descends and compresses the air; the curves or waves at the point of greater pressure show the power required to open the eduction valve; the pressure then continues uniform till the induction to the working cylinder closes, when the pressure runs up; at the commencement of the return stroke of the pump piston, the pencil mark inclines back, showing the time required for the closing of the eduction valve, and the wave below the atmospheric shows the time and power for opening the induction valve. The working cylinder is 16"X 16" stroke, and makes 70 revolutions per minute, scale 12 lbs. to one inch. 72 RICHARDS' STEAM-ENGINE INDICATOR. The pump, Fig. 2, is i the capacity of the working cylinder, Fig. 1; hence, we measure the average pressure of the two diagrams, each separately. Suppose the working cylinder to show an average of 10 lbs. to the square inch, and the pump diagram to show 9 lbs. to the square inch. The pump being - of the capacity of the working cylinder, we divide the mean pressure, which we have assumed as 9 lbs., by 3, the quotient is 3, this added to 10 is 13; 3 subtracted from 9 leaves 6, which subtracted from 13 leaves 7 lbs. effective pressure per square inch on the piston. Our author concludes the work with a graphic account of "A Ride on the Buffer Beam" on the Great Eastern Railway, making the trip from London to Yarmouth (England) in company with Mr. Zerah Colburn, for the purpose of taking diagrams from the engines, in which they were eminently successful; which the compiler of this, owing to the prescribed limits of this work, reluctantly feels compelled to omit, and substitute an account of a similar, though shorter, trip-from Wilmington, Del., to Philadelphia, on the Philadelphia, Wilmington and Baltimore R. R. Through the kindness of Mr. G. W. Perry, master of machinery of that road, Locomotive No. 50, a first-class express engine built by " the Taunton Locomotive Works" -cylinders 16" diameter by 24" stroke, four driving wheels 5' 6" diameter, making 305.46 revolutions to the mile-was placed at the disposal of the writer, RICHARDS' STEAM-ENGINE INDICATOR. 73 and fitted for the occasion under his directions by Mr. S. A. Hodgman, the able and efficient master mechanic of the shops. The engine is outside connected. The diagrams were taken from the forward end of each cylinder.-Short'" pipes were screwed into the top parts of the cylinder covers, with elbows R" internal diameter pointing upwards, to which the Indicators were attached. An iron rail was secured to the signal flag-stands on the narrow platform in front; a packing-box some 9" high served as a seat for each operator, with his back to the wind, and the Indicator between his knees. The method employed for giving motion to the papers was very simple. A plank on each side of the boiler, running from the cab to the platform, about 3' above the cross-head, and directly over it, which was used for the purpose of going forward to oil, etc., was morticed through in the'proper place, and a bracket with a hole through it to secure the arm to,, was bolted to the plank beside the mortice. A stud with a nut on it was fastened to the bracket, pointing outwards horizontally. A light arm swung from this stud and received a vibratory motion from another stud screwed into the side of the cross-head, working in a well-fitted slot in the lower end of the arm. A button-headed pin was inserted in this arm at about 7" below the point of suspension, and to this was attached the cord leading directly to the Indicator, giving to the 3 74 RICHARDS' STEAM-ENGINE IND CATOR. paper a motion of 4k". Great care was taken to set the arm, so that when the engine was on the half-stroke and the cord attached to the instrument, it might be at right angles with the arm. The cord had a hook about 2" long, with a bend about 1i" diameter, with a corresponding one on the instrument cord, which made it easy to attach under any speed. The hook on the cord was secured by two other cords to keep it in position, allowing it to move back and forth, but not to fall when disengaged, where it could not be readily seized. It was arranged with the engineer that he should run at all times with the throttle-valve fully open, governing the speed entirely by changing the point of cut-off. Everything being ready, Mr. Hodgman, the master mechanic of the shops, and myself, prepared to mount the platform. It being the month of November, and not being very warm, an extra overcoat was put on; a pair of woollen gloves, fingers amputated at the second joint, leaving enough of the finger bare to manipulate the instruments, were found to work well. Our first essay was with the engine and tender alone, to see that all was right. We took several diagrams, both on the forward and backward motipns. We found the valves remarkably well set. Diagram No. 19 is one of a pair that were taken when running about 20 miles per hour; working the steam full stroke, both backwards and forwards, RICHARDS' STEAM-ENGINE INDICATOR. 75 shows how nearly the two actions correspond. Its mate from the right-hand cylinder is a perfect facsimile of the one we engrave. In taking these cards, the throttle was quite'open. Pressure of steam not noted. The scale of the instrument 40 to the inch. During these preliminary experiments, an unfortunate accident happened to one of the instruments by breaking a spring. Not having an extra 40 spring, we substituted a 30 spring in each instrument, and that we might get sufficient range, we put washers between the end of the spring and the piston, of sufficient thickness to carry the piston down to the vacuum line, thereby giving us a scope of 15 lbs. more, and sufficient to answer the requirements for 105 lbs. pressure in the cylinders. I mention this for the reason that should the young engineer meet with a similar mishap, he may be posted on the subject. The delay caused by this mishap prevented us from carrying out a programme we had made previously. At 4 P. M. the express train arrived from Baltimore, which it had been arranged for us to take to Philadelphia. We took diagrams at speeds varying from 30 to 60 or mot'e miles per hour, with great facility, at full stroke, and cutting off at various points. In consequence of our weak springs, our experiments were limited in pressure to 105 lbs., hence we could not maintain our speed when cutting off short. Diagram No. 20, scale 30 to the inch from the right hand cylinder, cutting off at about one fourth 76 RICHARDS' STEAM-ENGINE INDICATOR. stroke, was taken at 60 miles per hour, piston making 1,222 feet per minute, 305.46 revolutions. Notwithstanding this extraordinary speed of piston, the lines are all well defined, showing distinctly the points of cut-off and release. A remarkable point in the diagram is, that though the pencil passed over it certainly twice or more, the' lines are very near to each other, showing that even under this unprecedented speed of piston the instrument was uniform and reliable in its action. This is not a selected diagram; all others taken on the trip show the same characteristics. Diagram No. 21, same scale, from the left-hand. cylinder, cutting off one notch shorter, with a higher pressure of steam, taken next after the foregoing, exhibits the same general features, though taken under a higher speed. Diagram No. 22, same scale, was next taken, working full stroke, with, as will be seen, throttle full open; the speed increasing to such a degree that the engineer thought it prudent to put on ~ cut-off.'This, as do all the other diagrams taken from the engine, shows most marked points in the construction and setting of the valves; notwithstanding the great speed, the steam line is held uniform to the points of release. The exhaust line is all that can be desired.' The back pressure is merely nominal, the exhaust nozzles being 4k" each. In getting the diagrams, the writer was ably seconded by Mr. RICHARDS' STEAM-ENGINE INDICATOR. 77 Hodgman, who, though it was his first attempt at taking diagrams, was remarkably efficient and correct. We have spoken of the accuracy of the valvesetting. These valves were set wholly by marks on the wheels, slides, and valve-rods, with steam on, and of course valve-chest covered, which is the only method by which they can be correctly set, owing to the expansion of the parts by heat. We would here refer the engineer who wishes to be well informed on the important art of valvesetting, to a very excellent work on the slide valve and link motion by Mr. W. S. Auchincloss, recently published by D. Van Nostrand, 23 Murray-street, New York, which is the result of great research and practical experience; from which we copy: "HOW TO SET A SLIDE VALVE HAVING EQUALIZED EXHAUST. "1. Place the crank at the 1800 location, mark on the cross-head and one of its guides opposing'centre punch' points. " 2. Bring the crank to the zero and mark a second point on the guide. The two points thus found, measure the length of the stroke. Move the eccentric until the valve has the required lead for the forward stroke.'' 3. Advance the crank in the direction of the motion until the exhaust of the opposite stroke 78 RICHARDS' STEAM-ENGINE INDICATOR. closes; scribe a line across the guide which shall pass through the point on the cross-head. " 4. Move the crank until the other exhaust closes and scribe a second line on the guide. " 5. If now the exhaust should close at equal distances from the commencement of each stroke, the motion would be in adjustment; if not, alter the length of the eccentric rod until the closure becomes equalized, then return the crank to the zero position, and alter the angular advance of the eccentric until the required lead of the forward stroke is secured. "The position of the valve at the moment of closure may readily be fixed by means of a'valve gauge' fitting centre punch points on the valve stem and its stuffing box. "The above process will serve also to equalize the cut-off if the valve be proportioned for this object." The trip was not without its discomforts, however successful it might have been, being accomplished on a November afternoon, with rather a low thermometer; with nothing at our backs to break off the wind, with low seats and otherwise constrained positions, we at the conclusion of our. trip found ourselves somewhat cold and a little stiff. Had it been a summer day, this source of discomfort would not have been, and we should have enjoyed the excitement of our trip much. So far as it is known to the writer, the above is RICHARDS' STEAM-ENGINE INDICATOR. 79 the first successful application of the Indicator to a locomotive, when making a regular trip on the road, in this country. It is quite certain that there is no Indicator known but the Richards, that can be successfully used for the purpose. We will conclude with Mr. Porter's concluding paragraphs of his " Ride on a Buffer-Beam:" " These diagrams are taken under fewer difficulties than would be at first imagined, if the weather is pleasant, and the proper provision is made for the comfort and security of the operators. The principal difficulty is from the wind, which, at very high speed, approaches more nearly to a hurricane than anything that one is able to experience in this latitude in any other way, and the labor of resisting it becomes quite wearisome, if the operator is not somewhat protected from its force. No unpleasant sensation whatever is produced by the rapid motion, the passing of trains is scarcely observed, and if no accident happens, there is no danger more than in the carriages. Good weather is essential to the satisfactory accomplishment of the objects of such an excursion." TABLE No. I -Areas of Circles, advancing by lOths. oo AREAS..0.2.3.4.5 6.7.8.9. 0.0.0078.0314.07o6.1256 1963.827.3848 -5026.636I o I.7854.9503 I I309 1.3273 I.5393 1I7671 2 oo06 2.2698 2 5446 2 8352 1 2 3.14I6 3.4636 3.8013 4.1547 45239 4.9087 5 3093 57255 6.1575 6 6052 2 3 7 o686 7.5476 8.0424 8.5530 9 0792. 9.6211 10.1787 10 7521 11 3411 11.9459 3 4 I2.5664 13.2025 13.8544 14.5220 15.2053 15 9043 16.6190 17 3494 1I80956 I8.8574 4 5 I9 6350 20.4282 21.2372 22 06I8 22.9022 23.7583 24.6301 25.5176 26.4208 27.3397 5 6 28.2744 29.2247 30.1907 31.1725 32.1699 33-183I 34.2120 35-2566 36.3168 373928 6 7 38.4846 39.5920 40.7151 41.8539 43.0085 44 I787 45-3647 46.5663 47.7837 49 oi68 7 8 50 2656 51.5300 52.8102 54.1062 5541I78 56.7451 58 0881 59.4469 60.82I3 62.2115 8' 9 63.6174 65.0389 66.4762 67.9292 69 3979 70.8823 72.3824 73.8982 75.4298 76.9770 9 Io 78.5400 8O.II86 81.7130 83.3230 84.9488 86.5903 88.2475 89.9204 9.6090o 93.3133 Io II 95-0334 96.7691 98.5205 OO1.287 102.070 103 869 105.683 107.513 109 359 111.220 II 12 113 097 114.990 116 898 118.823 120.763 122 718 124 690 I26.677 128 679 130 698 12 13 132.732 134 782 I36.848 138.29 14126 43 I39 45267 4741 49571 I51747 3 1 4 I46 74 1473464 I38-929,4I.026 14 153 938 156.145 158.368 6o 606 162.860 I65 130 67.415 169.717 172.034 174 366 14 15 176.7I5 179~079 181.458 183.854 186.265. 188.692 191.134 I93.593 196.06t 198.556 15 - I6 201.062 203.583 206.120 208.672 211.241 213.825 216.424 219.040 221 671 224.318 16 17 226.980 229658 232.352 235.062 237 787 240.528 243.285 246.057 248.846 251.650 I7 I8 254.469 257.304 260.155 263.022 265.905 268.803 271.716 274 646 277.591 280.552 1 I9 283.529 286.521 289.529 292.553 295.593 298 648 317I9 304.805 30.7908 311.026 19 20 314 I60 317-309 320.474 323.655 326.852 330.064 333.292 336-536 339*795 343 070 20.0..27.3 4.5.6.7,.8.9 Areas of Circles, advancing by 10ths. ___^___ ___ _ A R EAS. 1. |.1 |.2.3.4.5.6.7. 8.9 2I 346-361 349.667 352.990 356.328 359.681 363 05I 366.436 369.837 373.253 376.685 21 t 22 380 133 383-597 387.076 390 571 3940o82 397.608 401.150 404.708 408.282 411.871 22 Q 23 415.476 419 097 422.733 426.385 430.053 433.737 437.436 441.15I 444.881 448.628 23 P 24 452.390 456.168 459.961 463 770 467 595 471436 475.292 479. 64 483 052 486.955 24 25 490.875 494.809 498.760 502.726 506.708 510.706 514.719 518748 522.793 526.854 25 m 26 530.930 535.022 539.129 543.253 547.392 55I 547 555-7I7 559.903 564.105 568-323 26 [ 27 572.556 576-805 581-070 585.350 589-646 593.958 598 286 602.629 606.988 611.363 27 I 28 6I5 753 620.159'624:58I 629 O19 633.472 637.941 642425 646.926 65I.442 655.973 28 29 660.521 665:084 669.663 674.258 678.868 683.494 688.I36 692.793 697.466 702.155 29' 30 706.860 711.580 7I6.3I6 72I.067 725.835 730.6I8 735.417 740.231 745.061 749.907 30 ~ 31 754-769 759.646 764.539 769 448 774.372 779 313 784 268 789.240 794.227 799.230 31 1 32 804.249 809 284 814.334 819.399 824.48I 829.578 834.691 839.820 844.964 850.124 32 M 33 855.300 860 492 865.699 870.922 876. I60 881.4I5 886.685 891.970 897.272 902.589 33 I 34 907.922 913.270 918.635 924.OI1 929.410 934.822 940.249 945.692 951.I50 956.625 34 / 35 962.1 5 967.620 973.I42 978679 984.231 989.800 995.384 100.98 I06.60 102.23 35 36 II07.87 1023 54 1029.2I 1034.9I I040.62 I046.34 1052.09 I057.84 I063.62 I059.40 36 / 37 107521 IOI08.3 I086.86 1092.71 I09858 I10446 III0.36 1116.28 122 21 1128.15 37. 38 1134.11 1140.09 1146.08 1152.09 1158. I1 I64.15 1170.21 II76.28 II82.37 II88.47 38 39 1194 59 1200 72 I206.87 11213.04 I219.22 I225.42 1231.63 1237.86 1244.IO 1250.36 39 40 1256.64 I262.93 1269.23 1275.56 I28I.89 I288.25 129462 30.00o 1307 40 I313.82 40.0 i.1.2.3..5.6.7.8 Q 9 _ 0 Areas of Circles, advaching by lOths. o_ AREAS.' ~i.0 | I.2.3.4.5.6.7.8.9 41 1320.25 1326.70 1333- 6 1339.64 1346.14 I352.65 1359 I8 1365 72 1372.28 1378.85 41 42 1385.44 I392.05 I398.67 I405.30 14II.96 14I8.62 I425.3I 1432.01 I438.72 I445.45 42 43 1452.20 1458.96 1465.74 1472.53 1479.34 1486.17 1493-01 I49987 I506.74 I513.62 43 44 1520.53 1527-45 1534-38 154133 1548.30 1555-28 I562.28 156929 I576.32 I583.37 44 t 45 1590.43 1597.5I 16.64.60 61.71 168.83 1625.97 I633-12 1640-30 I647.48 1654.68 45 1 46 1661.90 I669.13 1676.38 1683.65 1690.93 1698.23 I705-54 1712.87 1720.21 1727.57 46 w 47 1734-94 1742.33 I749-74 1757-I6 I764.60 1772.05 177952 78701 1794.51 1802.02 47 48 I809.56 1817.10 1824.67 1832.25 I839.84 I847.45 I855-o8 I862.72 1870.38 I878.05 48 # 49 1885.74 1893.45 1901.17 1908.90 1916.65 1924.42 1932.20 1940.00 1947.82 1955.65 49 50 1963-50 1971.36 I979.23 1987.13 I995.04 2002.96 2010.90 2018.86 2026.83 2034.82 50 51 2042.81 2050.84 2058.87 2066.92 2074.99 2083.07 2091.1712099.28 2107.4I 2115-56 51 52 2123.72 2131.89 2140.08 2148.29 2156.51 2164.75 2173.01 gI8I.28 2189.56 2197.87 52 ~,53 2206.18 2214.52 2222 87 2231.23 2239.61 2248.01 2256.42 2264.85 2273.29 2281.75 53 54 2290.22 2298.71 2307.22 2315.74 2324.28 2332.83 2341 40 2349.98 2358.58 2367.20 54 U 55 2375.83 2384-48 2393.I4 2401.82 2410.51 2419.22 2427.95 2436.69 2445.45 2454 22 55 56 2463.01 2471.81 2480.63 2489.47 2498.32 2507.19 2516.07 2524.97 2533-88 2542.81 56 H 57 2551.76 2560.72 2569.70 2578.69 2587-70 2596.72 2605.76 2614.12 2623.89 2632.98 57 58 2642.08 2651.20 2660.33 2669.48 2678.65 2687 83 2697.03 2706.24 2715.47 2724.71 58 59 2733-97 2743.25 2752.54 2761.85 2771.17 2780.51 2789.86 2799.23 2808.62 2818.02 59 60 2827.44 2836.87 2846.32 2855.78 2865.26 2874.76 2884.26 2893.79 2903.34 2912.89 60.0..2.3.4.5.6.7.8.9.~~~~~~~~~~~~~~~~~~~~~~~-. Areaq of Circles, advancing by 10ths. AREAS..0. i 3.3 4 5. 7 -.8.9 6i 2922.47 2932. 06 2941.66 2951.28 2960.92 2970.57 2980.24 93 29 99.63 3009.34 6i 62 3019.07 3028.82 3038-58 3048.36 3058.1 5 3067.96 3077.79 3087 63 3097 49 3I7.36 62 g 63 3117,25 3127- I5 313707 3147-01 3156.96 3166.92 3176.9I 3186.90 3196.92 3206.95 63 P 64 3216.99 322705 3237 I 3247.22 3257-33 3267-46 3277. 59 328775 399792 3308. 11 64 65 3318.31 3328.53 3338-76 3349-01 3359.28 3369-56 3379.85 3390.1 7 3400.49 3410.84 65 " 66 3421.20 3431-.57 3441 96 3452 37 3462.79 3473.23 3483.68 3494.-16 3504.64 3515-14 66 67 3525.66 3536.19 3546-74 3557-30 3567-88 3578.47 3589-o8 3599-71 36I0.35 3621.0I 67 N 68 3631.68 3642.37 3653.08 3663.80 3674-54 3685-29 3696.06 3706.84 37I7 64 3728.45 68 [ 69 3739.28 0750.13 3760.99 3771 87 3782.76 3793.67 304.60 3815.54 3826.50 3837.47 69 70 3848.46 3859-46 3870.48 388I.5 3892.56 3903.63 3914.7I13924- 8 3 936-92 3948.05 70 Y 71 3959.20 3970.36 398 153 3992.73 4003 93 4015. 6 4026.40 4037.65 4048.92 4060.21 7I 72 4071.51 4082.83 4094.16 4105.51 4116.87 4128.25 4139-65 4151.o6 4162.49 417393 72 M 73 4185-39 4196.87 4208.36 4219.86 4231 38 4242.92 4254.48 4266.04 4277 63 4289.23 73! 74 4300.85 4312.48 4324.12 4335 79 4347-47 4359. 6 4370.87 4382.60 4394-34 4406.10 74 I 75 4417.87 4429-66 4441 46 4453-28 4465.12 4476-97 4488.84 4500.72 4512.62 4524-54 75 p 76 4536.47 4548.41 4560.37 4572.35 4584-35 4596.35 46o8.38 4620.42 4632.47 4644.54 76 g 77 4656.63 4668.73 4680.85 4692.99 4705-14 47I7-30 4729-49 4741-68 4753-96 4766. 2 77 1 78 4778.37 4790.63 4802.90 4815.20 4827.50 4839.83 4852.16 4864.52 4876.89 4889.27 78 79 4901.68 4914.09 4926.53 4938.98 4951-44 4963.92 4976.42 4988.93 5001.45 5014-00.79 8o 5026.56 5039 I3 5051I72 5064.32 5076.95 5089-58 5102.24 5114-90 5127-59 5140.29 80 _.o _.i.2 5.6.7.8.9 _,s....,fa ]It Areas of Circles, advancing by lOths. oo g _._ _____ _________ AREAS. _..0.Z'.2.3.4 5 6.7.8.9 81 5153-00 5165.74 5178.48 5191.25 5204.02 5216.82 5229.63 5242.45 5255-29 5268.15 81 82 | 5281.02 5293.91 5306.82 5319.74 5332.67 5345.62 5358.59 5371-57 5384-57 5397-59 82 | 83 5410.62 5423 66 5436.72 5449-80 5462.89 5476.00 5489.12 5502.26 55I5.42 5528.59 83 84 5541.78 5554.98 5568.20 5581.43 5594.68 5607.95 5621.23 5634-53 5647.84 5661.17 84 85 5674-51 5687.87 570I.25 5714.64 5728.o4 5741.47 5754.90 5768.36 5781.83 5795-31 85. 86 5808.81 5822.33 5835.86 5849.4I 5862.97 5876.55 5890.I5 5903-76 5917-39 5931 o03 86 w 87 5944-69 5958.36 5972.05 5985.76 5999.48 6013.21 6026.97 6040-73 6054-52 6o68.32 87 M 88 6082.I3 6095.96 6I09.81 6123.67 6137.55 6151.44 6165.35 6179.28 6193.22 6207.18 88 X 89 6221.15 6235.14 6249.14 6263.16 6277.19 6291.20 6305.31 6319.39 6333-49 6347.61 89' 90 6361.74 6375-88 6390.04 6404.22 6418.41 6432.62 6446.84 6461.o8 6475.34 6489.61 90 91 6503.89 65I8.I9 6532.5I 6546.85 6561.20 6575-56 6589.94 6604.34 66i8.75 6633-18 91 1 92 6647.62 6662.08 6676.55 6691.05 6705.55 6720.07 6734.61 6749. I6 6763.73 6778. 32 92 93 6792.92 6807.54 6822.17 6836.82 6851.48 6866. 6 6880.85 6895.56 6910.29 6925.o3 93 M 94 7939.79 6954.56 6969.35 6984.16 6998.98 7013.81 7028.67 7043.53 7058.42 7073.32 94 95 7088.23 7I03.16 7118.11 7133-07 7148.05 7163.04 7178.05 7193-07 7208.11 7223.17 95 ~ 96 7238.24 7253-33 7268.43 7283.55 7298.69 7313.84 7329 00 7344. I8 7359.38 7374.59 96 97 7389.-82 7405.07 7420.33 7435.60 7450.90 7466.20 7481.53 7496.87 7512.22 7527.59 97 j 98 7?42.98 7558.38 7573-80 7589.23 7604.68 7620.14 7635.62 7651.19 7666.63 7682.16 98 99 7697.70 7713.26 7728.83 78 7744-42 7760.03 7775.65 779I.29 7806.94 7822.61 7838.29 99 Ioo 7854.00 7869-71 7885.44 7901.19 79I6.95 7932.73 7948.53 7964-34 7980.16 7996.00o oo.o..x.2..,s3.4.5.6,7.8.9 RICHARDS' STEAM-ENGINE INDICATOR. 85 Circumferences of Circles, advancing by 1Oths. CIRCUMFERENCES..o o.2.2.3.4;5 6.7.8.9 0.00.31.62.94 1.25'I.57 1.88 2.19 2.51 2.^82 I 3.14 3.45 3 76 4.08 4.39 4.7I 5.02' 5.34 5.65 5.96 2 6.28 6.59i 6.9I 7.22 7.53 7.85 8. 6 8.48-8.79 9.11 3 9.42 9.73 I0.05 I0.36 IO.68 I.9 II.301I.62 II.93112.25 4 12.56 I2.88 13. 191I3 50 I3.82 14. 3 14 45 14.7615I 07 I539 5 15.701 6.02I6.33 16.65 16.96 17.27 I7.59 17.901I8.22 I8.53 6 18.84 19. 16119.47 19.79120. 10 20.42 20.73 2.C4i21.36 21.67 7 21.99 22.30 22.61 22.93 23.24 23~ 56 23.87 24. 19 24. 50 24.81 8 25. 13125 44525. 76 26.0726.38 26. 70 27.0I 27. 33 27.6427.96 9 28.27 28.58128.90 29229.29.5329.84 30. I5130.47 30. 783. 10 I 131. 41 31.73 32 404 32.35 32.67 32.98 33 30 33.61 33. 92 34.24 11 34-55 34.87'35. I8 35. 5035 8I136. 12 36.44 36.75 37 o7 3. 38 I2 37. 69 038. 3832 38.64 38.95 39.27 39.5838940.2 40. 52 I3'40.84 4I 15'41. 4614I ~ 78 42. 09 42.41 42.72 43.03 43.35 43.66 1443.98144.2944.61 44.92 45.23 45.55 45.86 46,I8 46.49 46.80 I5'47.1 22 47.43 477548.06 48.38 48.69 49. 00 49.32149. 63 49 95 I6150.26 50.57 50. 89 51. 220 5. 515.83 52. I5 52.46 52 77 53 09 I715340 53 72 54.03 54.3454.60 54.97 55 29 55 60155.92 56.23 18,56.54156.86157.7 57.49 57.8058. 11584358435874159o0659.37 19 59.6960.0oo 60.3160 6360.946I.2666. 5761.8862.2062.51 20162.83 63. I4163.46163. 77 64.0864464.74064.765 03653465 65 21 65.9766.28 66.60 66.79 67.29 67 54 67.85 68. I7 68.4868. 80 22169. I69 42169.7470.05 70.37 70.6871 007I.3171.627I.94 23172.25 72.57 72.88 73. I973. 51 7382 I474.45 744574 76 75.08 24175 39[75-7I176.02 76.34 76. 65 76.96 77.28|77.59177.9I 78.22 25178~ 54 78 85 79. 8796 794 79180. II 80.42J80o 73 81.058I.36 26 8I. 68 8I.9982.30 82.62 82.93 83.25 83.56|83.88 84. I984.50 27184.82185 31i85.45 85 ~76 86.07 86.39 86. 70187.02 87.33 87.65 28187.96 88.27 8 8.59 90 89.22 89.53 89.84 90. I6 90o.47 90. 79 29 91. 10 91.I42 9I. 73 92.0 6. 92.369267 92.99 93.30 93.61 9.939 30194.24194.56 94.87 95 I9 95 50 95. 8I196. 13 96.44196.76 97.07 3I197.38 97~ 70o98.0 o98.3398.64 989699.27199.58199.90 ooo. 2 32 I00.5 1oo.8 ioi. 101. 4 101.7 102. I I02 4 102. 7 103 0 I03.3 331 I036 103.9 104. 4. 04 9 105. 2 105 5105 o581 Io6. I 6. 5 341 06.8107.1 107. 4 I077 718'. o0 I08.31 08.61o9. o 109.3 o9. 6 351109.9IIo0.2 110.5 10.8III1.2 II1. 5III.8III 1112.1 4 112.7 86 RICGHARDS' STEAM-ENGIIE INDICATOR. Circumferences of Circles, advancing by O1ths. 14 CIRCUMFERENCES. I~.o..I 2.3.4.S.6.7.8.9 36 113.0 113.4 113.7 114.0 114-3 II4.6 114.9 115.2 II5.6 115-9 37 116.216.5 116.8II7.1 I17.4 117.8lII8.I 118.4 118.7 1I9.0 38 119.3 I19.6 120.0 120.9 121.2 121.5 121.8 I22.2 391I22.5 122.8123. 1 234 123. 7124. 0124.4 I24 7 I25.0125 3. 40 125.6 125.9 126.2 I26.6 126.9 I27.2 I27.5 127.8 128. 1I 28.4 41 I28.81I29. I129.4 129.7 I30.0 130.3130.6 I3I0 131.3 13I.6 42 I3 9 132.2 I32.5 132. 133.2 I33.5 I33 81 34. 134.4 134-7 43'350,I3541I3 6.6 I37 13. 43 135013.4 135.7136.0 1 36.6 I366 36.9 137. 2 37 6 137-9 44 i38.2'I38.5 I38.81339. 139.4 I39.8 I40. 140.4 140.7141.0 45 141-3 141.6 142.0 I42.3 142.6142.9 143 2 143.5 143.8144.1 46 144 5' I44. 8 1445. I1454 14146.0 o 14.3 146.7 147.0 147.3 47 147.6147.9 148.2 148.5 148.9 149.2 1495'149-8 150.1 150.4 48 150 71 511 1552.3I4 1557 2.09 153.3 1553.6 49 153 91154.2 154.4 4.8 155 11555 I55 8156. I156.4 156.7 50 I57-0 I57.3 157.7 158.0 I58.3 158.6 I58.9 I59.2 159.5 159.9 I5 160.2 160.5 I60.8 i6I.I I6I.41I61.7 I62.I 162.4 162.7 163.0 52 163.3 163.6 163.9 I64.3 I64. 6I64.9 165.2 165.5 165.8 i66.I 53 166.5 166.8 167. I I67.4 167.7 0 68. 3 168. 687 169.0 169.3 54 I69.6 169.9 170.2 170.5 170.9I171.2 I7I.5 171.8 172.1 I72.4 55 172.7 173 - 1173.4 173.7 174 - 743 174.6 174.9 175-3 175 6 56 I75-.9176.2I76. 576..8 177-I7.5 77778 78.1 I78.4 178.7 57 179.0 179-3 179.61 80.0 I80.3 r8o.6 I80.9 181.2 181.5 I81.8 58 182.2 182.5 I82.81 83.I I83.4 183.7 1484.0 4 84.4 184 85.0 59185318 5.6185.986.286 6. 86.9 87.2 187.51 87.8 i88.I 60o 88. 4 88.8 I89.I 189.4 189.7 190.0 190.3 I9o.6' I91. 191I.3 6I 91.6191. 192.9 1 192.21 892. 193.2 193.8,194.I 194.4 62 194.7 195 01 95.4 I95.7 I9. 96. 3 19663 9 6. 99,197.2 197.6 63 197-99 82 I98.29 5198.8 I99. I199.4 I99.8 2c. I 200 4 200.7 64 201.0 20I.3 201.6 202.0 202.3 202.6 202.9 203.2203 5 203 8 65 2042204. 5 044.8205.1 205.4205. 7 2206.4206.7 207.0i 66 207. 3207.6 207.9 208.2 208.6 208.9 209.2 209. 5209.8 210. I 67 210.4 210.8 211.I 2II.421.7 212.0212.3 212.6 213 0 213.3 68 213.6 213.9'2I4.2 214.5 214.8 215.1 215.5215.8216.1216.4 6912I6.772I7.0 2I7. 3 2I7 28 28. 318.6 2.32 218.9 219.22129.5 70 219.9 220.2,220.5 220.8 22. 1221.4 221.7 222. I 222.4 222.7 RICfARDS' STEAM-ENGINE INDICATOR. 87 Circumferences of Circles, advancing by lOths. CIRCUMFERENCES.'.o0.1.2 3.4.5.6.7 8.9 71223.0 223.3 223.6 223.9 224.3 224.6 224.9 225.2 225 5 225 8 72 226.1 226. 5226.8227 I227.4227. 7228.0228.3i228.7229.0 73 229.3 229.6 229.9 230. 230 5 230.9'231.2 231- 51238 232. I 74 232 4232.7233 I233.4233.7234.0234.3234. 6234.9235.3 75 23523 5.6 923 236. 236..8 237. I237 5 237. 8238.I238.4 76 238.7 239.0239.3 239- 7240.0240.3 240. 6 20.9 241.2 24. 5 77 24I.9242.2 242. 5242.8 243. I 243 4 243 7 244. 244.4 244. 7 78 245.01245.3 245 6 245.9 246.3 246.61246.9 247.21247 5 247 8 79 248.I 248.5 248.8 249.1I249 4 249 7 250.0250.3 250.6 251.0 80o251.3j251.6251.9252.2252.5 252.8253.2 253.5 2538 254.I 8I 254.41254 7255-.0255.4255 7 256. 236.3 256.6 256.9257.2 82 257.6 257.9 258. 2258. 5258.8 259- I259.4 259.8 260.1260.4 83 260.7 261. 261.3261.6262.26 2.3 6 262.6 262.9 263.2263.5 84 263.8 264.2 264.5'264. 8265265. 42654 2657 266.2664 266.7 85 267 -0267.31267.61267.9 268.2 268.6 268.9 269.2 269. 5269.8 86 270. 1 270.4 270. 8 271. I1271.4 271. 7272.0 272.3 272.61273. 0 87 273.3 273.6273.9'274.21274.5 274.81275.2275.51275 8276. 88 276.4 276.7 277.0,277.4277.7 278.0278.3 278.6278.9 279.2 89 279.6279.9280.2280. 5280.828I.I 28I.428I.8. 282 282.4 90 282.7 8283.0 283.31283 -6284.0 284.3 2846 284.9 285.2 285. 5 91I285.8 286. 1286.51286.8287. I1287.4 287.7 288.0288.3 288. 7 92 289.0 289.3 289.6 289 29 29.2 2928 9 290..291.2 290. 529i9291.8 93 292.1 292 4 292.71293 I 293 4 293 71294. 0294 3 294 61294 9 94 295.3125~6,295.9296 2296.5 296. 8297. 1297.5 297 81298. 95 298.4 298. 7299 ~0299.3 299- 73 00 300300.6300930I.2 96 301.530.9302.2302.51302.8303.303.4 303. 7 304 304.4 971304 73055 0,305 35 6305.9 30536.3 306 636.9 307.21307.5 98 307.8 308. I 308.5 308 9.8 309.4 309. 7310.0 310. 313 I0. 7 9913II.031I.31311 63 I 9312.2312.5312.91133 2313 5313.8 100314. 1314 4314. 73I5 I3I5-43I5.713I6.013I6.3316. 63I6.9 88 B kRICHAiD3' STEAM-ENGINE INDICATOR. If the areas of larger cylinders are required, they will be found by the following RULE:-Multiply the square of the diameter by the decimal.7854, and the product will be the area in square inches; or, multiply half the circumference by half the diameter. TABLE No. II. Showing the weight of the atmosphere, in lbs. avoirdtpois, on 1 square inch, corresponding with diferent heights of the barometer, from 28 inches to 31 inches, varying by tenths of an inch. Barometer Atmosphere Barometer Atmosphere in Inches. in lbs. in Inches. in Ibs. in Inchlcs. in lbs. 28.0 13.72 29.I 14.26,30I 14.75 28.1 I3.77 29.2 I4.31 30.2 14.80 28.2 13.82 29.3 14.36 30.3 14 85 28.3 13-87 29.4 I4.41 30.4 14.90 28.4 13.92 29.5 I4.46 30.5 I4.95 28.5 I3.97 29.6 I4.51 306 15.00 28.6 14.02 29.7 I4.56 30.7 I5 05 28.7 I4.o7 29.8 14 6I 30.8 15.10 28.8 14 12 29.0 14 66 30.9 15-15 28.9 14.17 30.0 I4.70 31.0 I5.19 29.0 14.21 RICHARDS' STEAM-ENGINE INDICATOR. 89 TABLE No. III. Showing the ecastic force, temperature, and volume of steam,?t temperatures from 32~ to 387.3~ Fahrenheit, varying by 5~ of temperature up to the boiling point, then by k lbs. of pressure on the square inch up to 25 lbs., then by lbs. of pressure up to 85 lbs., and then by 5 lbs. of pressure up to 200 lbs. Elastic force in Elastic force in Tempe- TempeInches Pounds ratur Volume. Inc Volume nhe rr of per of per Merc'y. Sq. in. Merc'y. Sq. in..200.098 32. 187407 6.53 3.I00 145. 7040.22I.108 35. 170267 7.42 3.636 I50. 6243.263.129 40. 144529 8-40 4-116 155. 5559 -316.155 45. 121483 9.46 4.635 I60. 4976 375.184 50. 103350 io.68 5.23 165. 4443.443.2I7 55- 88388 12.13 5-94 I70. 3943.524.257 60. 75421 13.62 6.7 I75- 3538.616.302 65. 64762 15.15 7.42 180. 3208.721.353 70. 55862 17. 8.33 I85. 2879 851 -417 75- 47771 19- 9-31 I90. 2.595 I. 49 80. 41031 2I.22 10.4 I95. 2342. I7 -573 85- 35393 23.64 11.58 200. 2118 1.36.666 0o. 30425 26.13 12.8 205. 1932 1.58.774 95. 26686 28.84 I4.13 210. 1763 1.86.911 I00. 22873 29.41 14-4I 211. 1730 2.04 I. I03. 20958 30. 14.7 212. 1700 2.18 I 68 I 10. 0 I95 3 30.6 15. 212.8 1669 2.53 1.240 iI0o 16667 31.62 155 214-5 1618 2.92 1.431 II5- I4942 32.64 I6. 216.3 I573 3.33 i.632 120. 13215 33.66 16.5 218. 1530 3.79 1.857 I25- 1I723 34.68 I7. 219.6 1488 4.34 2.I29 130. 10328 35.7 17.5 221.2 I440 5.00 2.450 135- 9036 36 72 I8. 222.7 1411 5.74 2.813 140. 7938 37.74 18.5 224.2 1377 90 RICHARDS' STEAM-ENGINE INDICATOR. Elastic force in Elastic force in Tempe- TempeInches Pounds rature. Volume. Inches rounds rature. Volume. of per of per Ierc'y. Sq. in. Merc'y. Sq. in. 38.76 19. 225.6 1343 I02. 50. 283.2 554 39 78 19.5 227.1 1312 I04.04 51. 284.4 544 40.80 20. 228.5 1281 I06.08 52. 285.7 534 41.82 20.5 229.9 1253 108.I2 53. 286.9 525 42.84 21. 231.2 1225 110.16 54. 288.1 516 43.86 21.5 232.5 1199 112.2 55..289.3 508 44.88 22. 233.8 1174 II4.24 56. 290.5 500 45.90 22.5 235.- 1150 116.28 57. 291.7 492 46.92 23. 236.3 1127 118.32 58. 292.9 484 47- 94 23.5 237-5 1105 120.36 59.. 294.2 477 48.96 24. 238.7 1084 122.4 60. 295.6 470 49-98 24.5 239-9 Io64 124.44 6I. 296.9 463 51. 25. 24I. 1044 126.48 62. 298.1 456 53-04 26. 243.3 I007 128.52 63. 299.2 449 55.08 27. 245.5 973 I30.56 64. 300.3 443 57-I2 28. 247.6 941 132.6 65. 301.3 437 59.16 29. 249.6 911 134-64 66. 302.4 431 61.2 30. 251.6 883 I36.68 67. 303.4 425 63.24 31. 253.6 857 138.72 68. 304.4 419 65.28 32. 255.5 833 140.76 69. 305.4 414 67.32 33. 257.3 810 142.8 70. 306.4 408 69.36 34. 259.1 788 144-84 71. 307.4 403 71.4 35. 260.9 767 146.88 72. 308.4 398 73.44 36. 262.6 748 148.92 73. 309.3 393 75.48 37. 264.3 729 150.96 74- 310.3 388 77.52 38. 265.9 712 153.02 75. 311.2 383 79.56 39. 267.5 695 I55.o6 76. 312.2 379 81.6 40. 269.1 679 157.1 77. 313I. 374 83.64 41. 270.6 664 159.14 78. 314. 370 85.68 42. 272.I 649 I161.I8 79. 314.9 366 87.72 43. 273.6 635 163.22 80. 3I5.8 362 89.76 44. 275. 622 165.26 81. 316.7 358 91.8 45. 276.4 6i0 I67.3 82. 317.6 354 93.84 46. 277.8 598 169.34 83 318.4 350 95.88 47. 279.2 586 171.38 84. 319.3 346 97.92 48. 280.5 575 173.42 85. 320.1 342 99.96 49. 281.9 564 183.62 90. 324.3 325 J RICHARDS' STEAM-ENGINE INDICATOR. 91 Elastic force in Elastic force in Tempe- TempeInches Pounds rature. Volume. Inches Pounds rature. Volume. of per of per. Merc'y. Sq. In. Merc'y. Sq. in. 193.82 95- 328.2 310 306. 150. 363.4 205 203.99 I00. 332. 295 316 19 155. 366. 198 214.19 105. 335.8 282 326 39 I60. 368.7 193 224.39 IIO. 339.2 271 336 59 165. 371.1 I87 234.59 115. 342.7 259 346.79 I70. 373.6 183 244.79 I20. 345.8 25I 357- 175. 376. 178 254.99 I25'349 I 240 367.2 180. 378.4 174 265 19 130. 352.I 233 3771I 185- 380.6 I69 275-39 135- 355 224 387.6 190. 382.9 166 285.59 140. 357-9 218 397.8 I95.- 384.7 16I 295-79 145- 360.6 210 408. 200. 387.3 158 TABLE No. IV. No. Logarithm. No. Logarithm. No. Logarithm. 1.25.22314 5. 1.60943 9-5 2.,25129 15.40546 5.25 1.65822 IO. 2.30258 1-75.55961 5-5 1 70474 II. 2.39789 2. *.69314 5 75 I174919 12. 2.48490 2.25.81093 6 1.79175 13- 2.56494 2.5.91629 6 25 I 83258 I4. 2.63905 2.75. i.oii6o 6.5 1.87I80 15. 2.70805 3 I 09861 6.75 1-90954 I6. 2.77258 3.25 1.17865 7- 1.94591 17- 2.83321 3.5 1.25276 7.25 1I98100 18. 2.89037 3 75.1-32175 7-5 2.0I490 19. 2.94443 4. 1.38629 7-75 2.04769 20. 2 99573 4.25 1.44691 8. 2.07944 21. 304452 4.5 1.50507 8.5 2.14006 2 24 3.09104 4-75 I.55814 9. 2.19722 92 RICHARDS' STEAM-ENGINE INDICATOR. TABLE No. V. Table of Steam used Expansively. Average Presure of steam in lbs. per. square inch for the whole stroke. Initial Pressure, Pbs. per Portion of stroke at which steam is cut off. square inch. __ % S % 3' 8 5 4.8 4.6 4.2 3.7 2.9 1.9 Io 9.6 9.1 8.4 7-4 5.9 3.8 I5 14-4 I3-7 12.7 II.I 8.9 5.7 20 19.2 18.3 I6.9 14.8 11.9 7.6 25 24.I 22.9 21.1 I8.5 14.9 9.5 30 28.9 27.5 25-4 22.2 17.9 1.5 35 33.8 32.I 29.6 25.9 20.8 I3.4 40 37-5, 36.7 33.8 29.6 23.8 I5.4 45 43.4 41.3 38.I 33-3 26.8 I7.3 50 48.2 45.9 42.3 370 29.8 I9.2 60 57.8 55.1 50.7 44.5 35.7 23.1 70 67.4 64.3 59.2 52.4 41.7 26.9 80 77.1 73.5 67-7 59.3 47-7 30.8 90 86.7 82.6 76.1 66.7 536 34.6 1oo 96.3 91.8 84.6 74.1 59.6 38.4 IIo 106.0 IOI:o 93.I 81.5 65.6 42.5 120 115.2 110.2 101.5 89.4 71.5 46.I 130 125.4 119.I IIo.o 95.3 77.5 50O0 140 134.9 128.6 II8.5 103.8 83.3 53.8 I50 144.7 137.8 I26.4 III 2 89.4 57.7 160 153.6 I47.0 I35-4 118.2 95.4 61.5 180 I73-5 164.6 152.3 132.9 107.3 69.2 200 192.7 183-7 I69 3 148.3 I19.3 76.9 RICHARDS' STEAM-ENGINZ INDICATOR. 93 We insert the Table No. V, not for general use in determining the mean pressure, as we have seen in the example on page 62, that another element, the clearance, has to be taken into account to get a correct result. Now, it is seldom we can get at the drawings or patterns to get the measurement of the clearance, hence we must seek some other mode. We can easily find if the engine is tight or not, by taking off the cylinder cover, putting the engine on the half stroke, blocking the fly-wheel, and letting stealu on the opposite side of the piston. Suppose we find it tight in valves and piston, we then replace the cover and take some diagrams, and find the mean by measurement, as directed on page 62. We then refer to the table for the mean pressure, which will be found too low when compared with the result by measurement. Then, this excess given by measurement over the table is approximately the clearance. The editor is responsible for the above. He is aware that it is, at best, but an approximation, owing to the condition of the steam, whether wet or dry, influenced, also, by the point of cut-off, pressure of steam, etc. The engineer has to adopt this mode, or guess, or he may avail himself of both. Where time and circumstances permit, the clearance may be accurately found, if the piston is tight, as follows: Put the engine on the centre, remove the cover of the valve chest, uncover the steamport on the end where the piston is, and pour in 94 RICHARDS' STEAM-ENGINE INDICATOR. water until it is filled level with the valve seat; wait a few minutes, and if it maintains its level we know it is tight; then draw off the water, measure or weigh it, reduce it to cubic inches, and we have it exactly. Should the piston leak, we remove it out of our way; cut a segment from soft wood of sufficient length and width to cover the port at its entrance to the cylinder, fasten it in its place, and fill with water as above. To this must be added the clearance between piston, when on the centre and cover. Again, the clearance being known and added, we compute them by measurement. If the mean pressure falls short of that, we know that there is a leak in the exhaust valves or piston. If it overruns that, we know the cut-off valves leak. Hence the utility of the table is to make those points manifest.* * A very ingenious and useful chart for marking the points of the true curves has been published by the inventor, Mr. A. H. Raynal, of New York city. RICHARDS' STEAM-ENGINE INDICATOR. 95 DIAGRAM No. 0. f —'4~~~~~~~~~~~~~~~~~~~~C RICHARDS' STEAlM-ENGINE INDICATOR, 99 DIA2GRAMl No. 2. 200 revolutions per minute. 132 lbs. pressure of ~t?,sm cut off at second notch. IICHARDS STEAM-ENGINE INDICATOR. 101 DIAGRAM No, 3 200 revolutions per minute. 109 lbs. pressure of steam out off at second notch BJ.cHaf \cf * R)e,:, S lI: - \J,-S'afIN, IN ICATOR. 103 DIAGRAM No. 4. 2~60 re-volTtionis pCr m'l~ u inute. 10;) lbs. prerasei of stteal cll o'f;oti fi sL;t It(.~. il RICHARDS 8'rF Ii-NEATI-ENG'NE INtlDICATO. a1 0 DIAGRIAM No. 5. 224 revolutions per minute. 107 lbs. pressure of steam cut off at first notch, RICHNRDS' STEAM-ENGYINE INDICATOR. 107 I iiII'I"Ii I /I Qal C. V. %d~I l,ll l/l/l!Ill~~~~~~~~~~ll1 C~ /6 l//ll/,~~It ll/l//111 RICHARDS' STEAI-ENGINE INDICATOR. 109 DIAGRAM aNo, 7. A, termination of correct expansion curve. RTMIRAR DS' STEr-iAM.-ENGINVE IND OT-P), i I JL DIAGRAM No. 8. -.~~~~~~~~~~~~E' t) 0 <1 C;1 c F7 ,iOHARSB STEAAM-NGINE INDICATOR. 118 DXAGRAM No, 9. Io0'sN X- WU)0VXI t 91i 11o0.0voj0xa^ s4.10rf)X.4-lVro^ Wv 4a9vi(tyloiti - ---------- 44 ICHlJRABfI)S STEAM- NGO-INE IND1l(,iATOB,.1.19 DIAGIRA&M No, 21 ICHAtRDSI STEAM-ENOTHE INDICAToR. 121 ]DIAGRAM No. 13. OE RICHARDS STEAM-ENGINS INDICATOR. b12 DL&REAM No. 15. BOIHtARDS8' TEAM-ELNGINEl INDICATORL 127 DIAGRBM No. I6, RItC1HARDIS'1. STEM-ENo(TNl N fICA'TO. 1. DIAGRAoM No. 17. R-li'(HA1i:,s STEAFM-[-N(lSXNE IN])T(ATOR.:131 DIAGRAM No. 18. RICHARDS STEAM-ENGINE INDICATOR. 133 DIAGRAM No. 19. Back and forward. RICHARDS STEAI-ENGTINE INDICATOR. 1o3 DIAGRAM No. 20. - ~~~~~~~~~~1 _~* 0 Z -3 tit c4 v R I.' t-) C to tj -c-i > ----------- - nAGrAM No, 23. 0 O The above Diagrams from an engine 24/tXy60/t 30 revolitions per miuute. Boiler pressure 66 lbs, Scale, 30 Ibs. to inch. Clearance equal to 3^.7T of the stroke. Upright beam engine. Sickles' cut-of improved by Rockwell & Burr. APPENDIX. USEFUL INFORMATION. Cement for Steam Joints. Take a quantity of pure red lead, put it in an iron mortar or on a block or thick plate of iron. Put a quantity of pure white lead ground in oil; knead them together until you make a thick putty, then pound it; the more it is pounded the softer it will become. Roll in red lead and pound again; repeat the operation, adding red lead anid pounding until the mass becomes a good stiff putty. In applying it to the flange, it is well to put a thin grummet around the orifice of the pipe to prevent the cement being forced inward to the pipe when the bolts are screwed up. The more pounding the better. Another, to be used when the flanges are not faced: Make the above mass rather soft and add cast-iron borings, pounding in thoroughly until it is sufficiently soft to spread. Both the above are the most durable cements known to the engineer. They will resist fire and set in water. 144 RICHARDS' STEAM-ENGINE INDICATOR. Another (English), said to be very good: Take 10 lbs. ground litharge, 4 lbs. ground Paris white, lb. yellow ochre, I oz. of hemp cut into lengths of -',; mix all together with boiled linseed oil to the consistence of a stiff putty. Resists fire and will set in water. [Pounding would improve it.-ED.] A Good Dressing for Leather Belts. One part of beef kidney tallow and two parts of castor oil, well mixed and applied warm. It will be well to moisten the belt before applying it. No rats or other vermin will touch a belt after one application of the oil. It makes the belt soft, and has sufficient gum in it to give a good adhesive surface to hold well without being sticky. A belt with a given tension will drive 34 per cent. more with the grain or hair side to the pulley than the flesh or rough side. Directions for calculating the width of belts required for transmitting different numbers of horse-power. Multiply 36,000 by the number of horse-power, divide the amount by the number of feet the belt is to run per minute; divide this quotient by the number of feet or parts of a foot in length of belt contact with smaller drum or pulley; divide this last quotient by six, and the result is the required width of belt in inches. EXAMPLE, Required the width of belt, the ve RICHARDS' 8TEAM-EN GINE INDICATOR. 145 locity of which is 1,600 feet per minute, to transmit twenty horse-power, the diameter of smaller drum being four feet: 36,000X20=72,000 — 1,600'=450. Diameter of smaller drum being four feet, the circumference over twelve feet, we will suppose the other drum so near and so large as to leave but five feet of the smaller drum's circumference in contact with belt-the 450- 5=-90- -6=15 inches, the required width of belt. Directions for calculating the number of horse-power which a belt will transmit, its velocity, and the number of square inches in contact with the pulley being known. Divide the number of square inches of belt in contact with the pulley by two; multiply this quotient by the velocity of the belt in feet per minute, and this amount divide by 36,000, and the quotient is the number of horse-power. EXAMPLE. A twenty-inch belt is being moved with a velocity of 2,000 feet per minute, with six'feet of its length in contact with the circumference of a four feet drum-desired its horse-power. 20X72 = 1440 -2=720X2,000 1,400,000.36,000=40 horse-power. A belt will drive 30 per cent. more when running on an iron pulley that is turned and scraped, than on a rough turned pulley.-HoYT BRos. 116 RICHARDS' STEAM-ENGINE INDICATOR. The above data are from accurate tests by the dynamometer. How to make belts run on the centres of pulleys. It often happens that a belt will persist in rut ning on one side of the pulley. In this case one or more things cause it. First, one or both of them may be conical, and of course the belt would run on the higher side. Second, the shafts may not be parallel; in this case the belt would incline off, on the side towards where the ends of the shaft are nearest to each other. The remedy in this case is, to make them parallel to each other by carrying the ends of the shaft towards which the belt inclines, farther apart. In giving rules for calculating the horse-power of belts, we would not be understood as saying that a belt will not do more than the rule would give; on the contrary, we know that double and even more power may be transmitted by them by a sufficient: tension, which would create a ruinous amount of friction and a speedy destruction of the belt. We would be understood to say that the rules give data for a belt that will run with a moderate and safe tension. The attempt often made to calculate the work that a belt of given width and travel in feet per minute without any known tension is doing, or will do, is very like comparing the size of a pebblestone to a piece of chalk. The Indicator tests that with certainty. RIE HARDS' STEAM-ENGINE INDICATOR. 147 The practice of putting an idler against a belt to make it drive is a most pernicious one, destructive alike to the belt and power; its only merit is to disguise bad engineering. Measuring Steam used for heating. The engineer is often called to determine the amount of steam that is used to heat apartments, liquids, etc. This the Indicator does not reveal directly, no farther than it shows how much steam it requires for a horse-power; varied, of course, by the point of cut-off and its efficiency. Under these circumstances we have followed the rule of Watt, which is to allow one cubic foot of water per hour for each horse-power; hence we measure the water condensed in the heating pipes in a given time, and estimate accordingly. If it is inconvenient to reduce the water to cubic feet, it may be weighed, allowing 62.5 lbs. to the cubic foot, or it may be measured by the gallon, or 7.48 gallons per cubic foot. When the steam pipe enters the vessel and it discharges the steam directly into the liquid to be heated, the water then cannot be caught to be measured; in that case we measure the increment of its contents, and thereby find the quantity of steam condensed. 148 RICHARDS' STEAM-ENGINE INDICATOR. Condensation of pipes and coils. Steam pipes in the ordinary circulation, such as are used to warm buildings, when one or more run around the sides of the apartment, having and maintaiaing a temperature of 600, will condense.357 lbs. of water per hour for each square foot of surface of pipe. A coil maintaining the same temperature will condense.29 lbs. per hour per square foot of sur^ face. The radiating surface of steam pipe required to warm buildings and apartments. This varies in consequence of the character of the structures, the exposure, the quantity of glass, the use the space required to be heated is put to, climate, etc. In the city of New York the data of calculation, modified by the above-mentioned circumstances, is this: For dwellings-when the pipes in form of a coil are placed in the cellar and supplied with air from, outside-one square foot of pipe surface to 50 cubic feet of apartment to be warmed. When the coil is placed in the apartment, one square foot of surface of pipe to 65 cubic feet of space. In stores and warehouses, one square foot of pipe surface to 175 to 200 cubic feet. RICHARDS' STEAM-ENGINE INDICATOR. 149 In workshops, one square foot of pipe surface to 100 cubic feet of space. Heating with exhaust steam is of questionable economy. It is not economical, certainly, when used in small pipes, in consequence of the power required to force. the steam through them. We have seen exhaust steam used economically in workshops and factories where it is permissible to use large cast-iron pipes, which present so much less friction surface in proportion to the area, that the power used to force the steam into them shows but a small back pressure on the engine-1 or 1- lbs. per square inch-if the pipes are of sufficient size and properly arranged. We have found the following to work well in practice: We use for the smallest, flanged pipe, without regard to the size of the engine, 4" diameter. If it is required to be over 75 feet in length, we use 5"; if over 100 feet, we use 6". The pipes should be - thick, with flanges at least 4 inches larger than the outside diameter of the pipe. These flanges should be faced so as to have a fair bearing over the whole surface, and when faced, not less than 8" thick, fastened with five bolts, I" diameter. We place them, when practicable, around the walls of the room, near the floor, on the sides most exposed, giving them an inclination of not less than one inch in ten feet; for our joints, the cement No. 1 (rubber not permissible). 150 RICHARDS' STEAM-ENGINE INDICATOR. The main exhaust pipe we carry out of the.building, without reference to our heating pipes, except to have a nozzle to carry off steam to the highest end of the heating pipe. Should there be one or more rooms above or below, separate pipes from the main should be led off in the same way. The drain pipes should be at the lowest end of the pipe, and 1" to a" diameter. If it is desirable to let only water escape, a siphon may be fixed to the end of the tail pipe, with legs of sufficient length to overbalance the steam pressure, yet leaving the water by its superior gravity to escape. The supports should be firmly fixed to the wall, in perfect line with each other, that there be no bend or low place for the water to collect, which would inevitably destroy the pipe. We have used a system of pipes arranged as above, for eight years, without the least attention to them. Not a joint hasleaked. Value of Pea and Dust Coal, as compared with lump of good merchantable quality, with a blast induced by "Hancock's Steam Blower." 2,000 lbs. of pea and dust, the screenings from the coal-yards, have been found equal to 1,600 lbs. of lump. This is a result of several weeks' trial with the same engine and boiler doing the same work. Gauge glasses, when required to be cleaned, RICHARDS' STEAM-ENGINE INDICATOR. 151 should have a wooden swab-stick. A metallic one will cause the tube to fall to pieces inevitably, and sometimes immediately. Value of Cumberland coal as compared with anthracite. Two tons (4,000 lbs.) of anthracite furnished steam for an engine seven days. The same amount of Cumberland served the same engine, everything elsethe same, eight days. This experiment was continued with alternate changes for two months. Boiler, locomotive type, with natural draft. I N D E X. PAGB American Editor's Preface.......................... 7 Nature and Use of the Indicator..................... 9 Mode of proceeding to Find the Power a Tenant Uses.. 9 Analysis of Diagram No. 1................. 14 Truth of the Diagram............................ 16 Conditions of a Correct Diagram................. 16 Errors Liable............................. 17 General Construction of the Indicator............ 18 Metallic Pencil.................. 19 List of Springs.................................... 20 Practical Directions for Applying and Taking Care of the Indicator........2....1................... 21 Giving Motion to the Paper..................... 24 From what Points to Derive the Motion.......... 25 "' " " " 0on Locormotves.. 27 " "'. " " on Oscillating Engines................................. 28 How to Take a Diagram............................ 29 *To Connect the Cord............................... 30 To Take the Diagram............................... 31 Notes on Diagram................................... 33 How to Keep the Indicator in Order............... 34 Note on the Importance of Proper Oil...... 34 How to Change the Springs.......................... 36... Barrel Springs............... 36 " Ascertain the Power Exerted by the Engine... 37 On Diagrams from Condensing Engines............... 40 154 INDEX. PAGE Power Exerted by Engines as per Diagram No. 1, with Example............................ 43 On Diagrams from Non-condensing Engines-Example. 45 To Measure from the Diagram the Amount of Steam Consumed....................................... 48 Observations on the Several Lines of the Diagram.... 50. Classification of Engines, Steam Line................. 51 Full Stroke, Lap, Link, Independent, byAction of Governor on the Cut-off Valve, and according to the Work by Throttle................................. 51, 52 Prof. Tyndall's Experiments..................... 56 Importance of Cutting-off quickly...................59, 60 To find Mean Pressure by Hyperbolical Logarithms... 61 Remarks of the Editor-Examples..................62, 63 Exhaust Line and Line of Counter Pressure.......... 63 Compression Line........... 64 Theoretic Curve and its Uses; How it is Made; Clearance Defined...................................66, 67 Cards from a Caloric Engine......................... 71 Trip from Wilmington to Philadelphia on Locomotive No. 50, with Method of Operation................ 72 Valve Setting-How to set a Slide Valve.............. 77 Remarks on Table V.-How to find if the Engine is tight, and how to find the Clearance............ 93 TABLES. Table No. I.-Areas of Circles....................... 80 Circumferences of Circles............................ 85 Table No. II.-Showing Weight of the Atmosphere at different Heights of the Barometer............... 88 INDEX. 155 PAGE Table No. III.-Showing the Elastic Force of Steam at Different Temperatures........................... 89 Table No. IV.-Logarithms.......................... 91 Table No. V.-Steam Used Expansively. Average Pressure in lbs. per square inch for the Whole Stroke. 92 Diagrams.9.......................-,,,,......... 95-141 AP PEN DIX. cement for Steam Joints............................. 143 I Good Dressing for Leather Belts................... 144 Directions for Calculating the Width of Belts required for Different Numbers of Horse-Power.......... 144 Directions for Calculating the Number of Horse-Powers that a belt will transmit its velocity, and the number of square inches in contact with the pulley being known......................................... 145 How to Make Belts run on Centres of Pulleys'........ 146 "Idlers"........................................:. 147 Measuring Steam used for Heating................. 147 Condensation of Pipes and Coils..................... 148 Radiating Surface of Steam-pipe required to Heat Buildings and Apartments. 148 Comparative Value of Pea and Dust Coal with Lump.. 150 " " Cumberland and Anthracite..... 151 Cleaning Gauge of Glasses........................... 150 Lane's Improvement-Inside View. 1 AMERICAN STEAM GAUGE COMPANY, 44 Coxmgress Street, Boston, SOLE POPRIETORS AND MANUFACTURBBS OF BOURDON'S PATENT STEAM GAUGE (Formerly known as the "ASHCROFT GAUGE"), AND OF LANE'S IMPROVEMENT ON THE BOURDON. ALSO OF "E. G. ALLEN'S PATENT STEAM GAUGES, Formerly made and sold by the "National Steam Gauge Co." AND OF THE CELEBBATED WATER GAUGES, Formerly made by the "American Water and Alarm Gauge Company." HIGH PRESSURE, Low PRESSURE, BACK PRESSURE, LOCOMOTIVE, AND VACUUM GAUGES, OF EITHER OF THE ABOVE PATENTS. Water Gauges, Steam Whistles, Gauge Cocks, Oil Cups, etc THE AMERICAN STEAM GAUGE COMPANY are the Sole Proprietors and Manufacturers of the RICHARDS PARALLEL-MOTION INDICATOR. The particular attention of engineers is called to this Instrument, by the proper use of which the power of an engine may be ascertained, its valves accurately set, and any defects in the working of the engine discovered. ALSO, SEWELL'S PATENT SALINOMETER. Orders for PYROMETERS, a new and useful instrument for ascertaining the heat of Blast Furnaces, FILLED AT SHORT NOTICE. H. K. MOORE, Superintendent. 2 C -A - TI C STN. The original Bourdon Patent for Steam Gauges was purchased by E. H. Ashcroft, and was sold by him to the "American Steam Gauge Co.," March 22, 1854. One of the conditions of this sale was that this Company should place the name "Ashcroft" on every Gauge manufactured, and hence these Bourdon Gauges have acquired the name of the "Ashcroft Gauge." Since March 22, 1854, Mr. Ashcroft has had no right to make or vend these Gauges, nor has any person except this Company, as the following card will show: "No. 4 CHARLESTOWN STREET, BOSTON, April'24, 1854. "DEAR SIR,-Allow me to inform you that the'Ashcroft Steam Gauge' is now owned and manufactured by the'American Steam Gauge Co.,' to whom I have sold out all my interest in the Gauge, except an interest in the stock of the Company. The business is now done.by said Company, to whom all orders must hereafter be addressed. " The American Steam Gauge Company are prepared, with increased facilities, for manufacturing this Gauge; and all orders received by them will be promptly attended to. Your favors are respectfully solicited for the Company.. "E. H. ASHCROFT." Mr. Ashcroft has, however, Undertaken to manufacture a Steam Gauge similar in external appearance to the Bourdon or to the Allen Gauges manufactured by this Company, but which are entirely different in structure and principle. As they bear his name, many persons have purchased them under the belief that they were the well-known, well-established Gauges manufactured by this Company under the Bourdon Patent. Mr. Ashcroft has not the most remote interest or connection with this Company, or with the Patent; nor is he, or any other party, authorized to either alter or repair our Gauges. The public are cautioned against buying Gauges marked "Ashcroft's Improved Steam Gauge," or "E. H. Ashcroft," on the dials. They are not our make. Every Gauge made by this Company has their name, "American Steam 3 Gauge Co." and "Bourdon Patent," or "E. G. Allen's Pat. ent," on the dial or flange, without which none are genuine. The popularity of the Allen Gauge, it seems, has lately brought into market some instruments purporting to be "similar in principle" to that Gauge, but which are really nothing more or less than attempted evasions of that patent; but yet calculated to mislead those who are not familiar with the internal structure of Steam Gauges. Purchasers should beware how they buy such instruments, as all persons who infringe upon any of the patents owned by this Company will be held strictly accountable. SCALE OF PRICES. The AMERICAN STE.AM GAUGE COMPANY, by advice of many customers rof both patents,: have made such regulations in their prices as, it is hoped, will be found satisfactory. During their lorig experience as manufacturers of Steam Gauges, they have found it necessary to manufacture many different styles, to.ieet the numerous wants of the public; and in doing so, now find it necessary to number them. BOURDON, AND LANE'S IMPROVEMENT. No. 0, Brass Case, 9 inch Dial, Engraved............ $63 00 0, " 9 " Plain................ 55 00 1, " 81 " Engraved............ 60 00 1, " 8I " Plain............... 48 00 2, " 61 " Lane's Improvement, Locomotive, Steamboat, or Stationary....... 30 00 2, Brass Case, 61 inch Dial, Old Style, High or Low Pressure, or Vacuum................. 30 90 3, Iron Case, 61 inch Dial, Old Style, High or Low Pressure, or Vacuum................. 25 00 3, Iron Case, 61 inch Dial, High or Low Pressure, Lane's Improvement....................... 28 00 4, Brass Case, 6 inch Dial, Old Style, High or Low Pressure.................................. 25 00 4 4, Brass Case, 6 inch Dial, Lane's Improvement, Locomotive............................... $2'00 4, Iron Case, 6 inch Dial, Old Style............. 23 00 4. " 6 " Lane's Improvement.. 25 00 6, Brass Case, 5I " " " d Stationary................................ 20 00 6, Iron Case, 56 inch Dial, Old Style, Stationary. 15 00 6, " 5 "* Lane's Improvement, Stationary................................ 18 00 7, Brass Case, 3 inch Dial, for Back Pressure, etc. 12 00 ALLEN'S PATENTS. No. 00, Brass Case, 4j inch Dial, Stationary......... $15 00 00, Iron Case, 41 " ",... 1200 0, Brass Case, 51 " "........ 20 00 1, Iron Case, 5i "......... 15 00 2, " 6 ""'......... 20 00 1, Brass Case, 6 " "......... 25 00 2, " 6 S " Locomotive. 30 00 3, Iron Case, 61 " "....... 25 00 3, Brass Case, 81 " Engraved........... 58 00 3, " 8j " Plain.............. 48 00 4, " 10 " Engraed.......... 65 00 5, " 10 " Pressure and Vacuum 80 00 6, " 13 " Pressure and Two Vacuums............130 00 A Vacuum and Pressure Gauge, Revolution Counter, and Howard Clock, in one Case, 20 inch Ring, Brass Case........................................... 330 00 Two Vacuums and one Pressure Gauge, Revolution Counter, and Howard Clock, in one Case, 20 inch Ring, Brass Case............................... 350 00 A Howard Clock and Counter, in one Case, 10 inch Dial, Brass Case, and Silver-Plated Ring, or Bizzel, Gold-Plated Hands...........................160 00 A Howard Clock, 10 inch Engraved Dial, separate 5 Case, $115; 8} inch Engraved-Dial, same style, $110; 10 in. Counter, in separate Case, same style, $80; 8} in. Counter, same style........................ $70 00 Each of the above with Stand or Base, $10 extra. WATER GAUGES. No. 1, Water Gauge, 1 inch glass....... 30 00 2, " 2200 2, " i ".................... 22 00 2, " i " (Valve)............ 20 00,....................14 00 4, l "...................10 00 4, " i " (Valve)............ 10 00 STEAM WHISTLES. 12 inch Steam Whistle............................ 150 00 10 "..100 00 8 " "............................. 70 00'6 " "............ 35 00 5 "............................ 25 00 4 ".............................. 20 00 3.............................. 15 00 2................................. 1200 2." (with Valve).................. 8 00 2 ".. (without Valve)............... 5 00.............................. 3 00 WATER GAUGE GLASSES. American Glasses, all sizes and lengths; Scotch Glasses, regular sizes and lengths-wholesale and retail. PRICE LIST FOR INDICATORS AND APPENDAGES. Indicator, with one Spring, Scale, and Cock..........$90 00 Extra Spring and Scale............................ 6 00 Extra Cocks................... each, 2 50 Elbows........................................... 2 00 Carrying Pulleys................................... 50 Parallel Rule...................................... 7 00 6 F. w. BAGON, o. B.s APPLES THE INIDICATOR TO STEA.MV:-E N GINE S, FURNISHES Instruments, and gives Instruction in their Use. MANUFACTURERS, and others using Steam-Engines, can, by applying the INDICATOR, ascertain the condition of their Engines; the power required to do their work, or any portion thereof; the economy of fuel expended, when compared with power developed. The undersigned makes a specialty of this branch of engineering, and will wait on any party who desire his services. Special attention given to the erection of Steam-Engines and Machinery, Shafting and Belting. Will attend to laying out works, and make plans and esti. mates. Parties wishing to burn shavings, saw-dust, and other light fuels, can have their furnaces constructed so as to consume the smoke and gases therefrom, at a moderate cost. F. W. BACON, Consulting Engineer, 84 John St., N.. Y. 7 VALUABLE SCIENTIFIC BOOKS, PUBLISHED BY D. VAN NOSTRAND, 23 MURRAY STREET AND 27 WARREN STREET, NEW YORK. FRANCIS. Lowell Hydraulic Experiments, being a selection from Experiments on Hydraulic Motors, on the Flow of Water over Weirs, in Open Canals of Uniform Rectangular Section, and through submerged Orifices and diverging Tubes. Made at Lowell, Massachusetts. By James B. Francis, C. E. 2d edition, revised and enlarged, with many new experiments, and illustrated with twenty-three copperplate engravings. I vol. 4to, cloth.....................$5 oo ROEBLING (J. A.) Long and Short Span Railway Bridges. By John A. Roebling, C. E. Illustrated with large copperplate engravings of plans and views. Ix prjess........................................ CLARKE (T. C.) 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Revised and enlarged, with an Appendix on the Martin Process for making Steel, from the report of Abram S. Hewitt. Illustrated with numerous wood engravings. i2mo, cloth..................................... 2 50 CAMPIN on the Construction of Iron Roofs. By Francis Campin. 8vo, with plates, cloth........... 3 oo CLOUGH (A. B.) Contractors' Manual and Builders' Price-Book. By A. B. Clough, Architect. I vol. i8mo, cloth................................ 75 COLBURN (Zerah). Engineering - an Illustrated UV eekly Journal, conducted by Zerah Colburn, London. 32 pagesfolio. Is promptly received here by' weekly steamers. Price per annum............... 5 00 - The Gas Works of London. By Zerah Colburn, C. E. I vol. 12mo, boards........................ 60 CRAIG (B. F.) Weights and Measures. An account of the Decimal System, with "ables of Conversion for Commercial and Scientific Uses. By B. F. Craig, M.D. i vol. square 32mo, limp cloth.......... 50 NUGENT. 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With 76 Lithographic plates. 8vo, cloth. to oo - Supplementary Report to the above with 7 lithographed maps and views. 8vo, cloth.............. 5 oo AUCHINCLOSS. Link and Valve Motions Simplified. Illustrated with 37 wood-cuts, and 21 lithographic plates, together with a Travel Scale, and numerous useful Tables. By W. S. Auchincloss. 8vo, cloth.. 3 oo VAN BUREN. Investigations of Formulas, for the strength of the Iron parts of Steam Machinery. By J. D. Van Buren, Jr., C. E. Illustrated, 8vo, cloth. 2 oo JOYNSON. Designing and Construction of Machine Gearing. Illustrated, 8vo, cloth2 oo HOW TO BECOME A SUCCESSFUL ENGINEER. Being Hints to Youths intending to adopt the Profession. By Bernhard Stuart. z8mo, cloth. 75 FREE-HAND DRAWING, a Guide to Ornamental, Figure, and Landscape Drawing. By an Art Student. Profusely illustrated, i8mo, cloth........... 75 THE EARTH'S CRUST. A handy Outline of Geology. By David Page. 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