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 ELECTRICITY 
 
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3Hi JO 
 
 AmHBn 
 
DOMESTIC 
 
 y. 
 
 
 ^ — * • to 
 
 
 ELECTRI CITY 
 
 FOR AMATEURS. 
 
 TRANSLATED 
 
 FROM THE FRENCH OF E. HOSPITALIER, 
 
 EDITOR OF “ L’fiLECTRICIEN,” 
 
 WITH ADDITIONS, 
 
 BY 
 
 C. J. WHARTON, 
 
 ASSOCIATE OF THE SOCIETY OF TELEGRAPH ENGINEERS AND ELECTRICIANS. 
 
 E. & F. N. SPON, 125, STRAND, LONDON. 
 
 NEW YORK : 35, MURRAY STREET. 
 
 1885. 
 
^6y\r3l !<r06 
 
 CZI. 3 
 H7‘f fw 
 
 PREFACE. 
 
 Every one is agreed as to the immense advantages to be 
 obtained from a general distribution of electricity, and it is to 
 be hoped that ere long it may be realised in every city and 
 town, if only on the comparatively small scale at present at 
 work in a few cities of the United States, and on Holborn 
 Viaduct, London. 
 
 It will, however, be many years before this distribution 
 can become universal, and although we may look forward to 
 the future with confidence, it is as well to think of the present 
 also, and at the same time to render the public familiar with 
 the numerous advantages to be expected when a general 
 distribution of electricity becomes an accomplished fact, 
 although we can at present only deal with it on a very small 
 scale. 
 
 It is for this purpose that the present work has been 
 written, and it must be understood that it is not to the pro- 
 fessional electrician that it is addressed, but as its name will 
 imply, it is intended as a book of amusement combined with 
 instruction for the amateur who wishes to know something of 
 the working and uses of that subtle something, “ electricity,” 
 which, it is prophesied, is destined to revolutionise the world. 
 
 London, May 1885. 
 
 754514 
 
CONTENTS 
 
 
 
 
 
 VAGK 
 
 Introduction 
 
 CHAPTER I. ' 
 
 
 
 
 Production of the Electric Current 
 CHAPTER II. 
 
 
 
 9 
 
 Electric Bells 
 
 CHAPTER III. 
 
 
 
 26 
 
 Automatic Alarms 
 
 CHAPTER IV. 
 
 
 
 40 
 
 Domestic Telephones 
 
 CHAPTER V. 
 
 
 " 
 
 49 
 
 Electric Clocks .. 
 
 CHAPTER VI. 
 
 
 
 67 
 
 Electric Lighters 
 
 CHAPTER VIL 
 
 
 
 76 
 
 Domestic Electric Lighting .. 
 
 88 
 
Vlll 
 
 Contents. 
 
 CHAPTER VIII. 
 
 PAGE 
 
 Domestic Application of the Electric Light .. .. 124 
 
 Electric Motors .. 
 
 CHAPTER IX. 
 
 •• 138 
 
 
 CHAPTER X. 
 
 Electrical Locomotion .. .. 15 1 
 
 CHAPTER XL 
 
 Electrotyping, Plating, and Gilding .. .. 163 
 
 CHAPTER XII. 
 
 Electric Recreations 174 
 
 CHAPTER XIII. 
 
 Various Applications— Workshop of the Electrician 
 
 215 
 
DOMESTIC ELECTRICITY 
 
 FOR AMATEURS. 
 
 INTRODUCTION. 
 
 Like all other physical forces, electricity only reveals itself to 
 us by its effects ; we know how to use these effects, to apply 
 them to our requirements, and to measure their magnitude, 
 but the cause which creates them is unknown to us. We will 
 not here endeavour to gloss over our ignorance by erroneous 
 and often deceptive theories, but let us be content with results : 
 for these results are sufficiently interesting and curious to 
 enable us to forget the obscurity which hides their origin. 
 
 Beyond all hypothesis, electricity is to us a vague term, 
 under which a series of phenomena and physical actions are 
 understood which are called electrical phenomena. Electricity 
 is no more a fluid than the other physical forces into which it 
 may be transformed, or which give rise to it, such as : heat, 
 light, mechanical and chemical energy. It is, to employ the 
 striking expression used by Professor Tyndall, a peculiar 
 mode of motion capable of reproducing, under certain given 
 conditions, every other mode of motion. 
 
 We will first of all make these mutual transformations 
 evident by means of an electric generator, well adapted for 
 this demonstration, but, without for the moment troubling 
 ourselves with its exact constitution, we will consider it solely 
 as an apparatus capable of producing electrical phenomena 
 by the turning of a handle (Fig. i). 
 
 This little machine enables us to make most of the ele- 
 mentary experiments we shall require to demonstrate the case 
 
 B 
 
2 Domestic Electricity for Amateurs, 
 
 with which the different phases and applications of electricity 
 and its different transformations are effected. 
 
 The first, the most striking, is made with the machine 
 alone, without accessories. It shows clearly the transformation 
 of mechanical into electrical energy. As long as the circuit is 
 open, putting the machine in motion requires but trifling 
 exertion, just sufficient to overcome the friction of the parts. 
 
 Fig. I. 
 
 When the circuit is closed by joining the two terminals by a 
 conductor a considerable resistance is experienced, and the 
 operator is compelled to slacken the speed. 
 
 The magnetic actions of the current are shown by means 
 of a small compass, Fig. 2, No. 7, which, placed above or below 
 the wire, tends to set itself at right angles with the current. 
 The principle of the electric telegraph is made evident by a 
 vertical electro-magnet. No. 3, magnetised by the current from 
 the machine, and a commutator key introduced in the 
 circuit, which may be worked as desired to produce Morse 
 signals. 
 
 For the calorific effects of the current, a small Swan 
 
Fig. 
 
 Domestic Electricity for Amateurs. 
 
 3 
 
 incandescent lamp, No. I2, is used, mounted on a suitable 
 support, or small clips. No. 4, which enable fine platinum or 
 
 iron wire to be heated to redness, and volatilise or to render 
 incandescent small carbon pencils, No. 9. 
 
 B 2 
 
4 
 
 Domestic Electricity for Amateurs. 
 
 By simply varying the speed of the machine, the degree of 
 incandescence of the lamp or the wires may be varied. Under 
 - calorific effects must also be included the small fuzes, No. 6, 
 which the current explodes when the circuit is completed. 
 
 The storage of electrical energy in chemical form is 
 effected by the aid of a small Plante accumulator. No. lo, in 
 which the plates are each formed of a sheet of lead rolled on 
 itself to increase the surface. This accumulator charged by 
 the machine can then set the magnet at work, make wire 
 glow, &c. A voltameter of platinum plates. No. 5, and baths 
 for nickel or silver plating and electro-deposition complete 
 the materials required to demonstrate the chemical actions 
 of the current. 
 
 Handles of copper silvered over. No. 2, may be used to 
 give shocks and to show the physiological effects of the 
 current, which can be modified at will by varying the speed 
 of the machine. The shocks are produced here by the extra 
 currents, and in order to obtain them it is necessary to 
 arrange the commutator between the terminals and to com- 
 plete and open the circuit in rapid succession, or to touch 
 the handles together and then separate them. 
 
 These small accessories can be varied indefinitely ; let us 
 add : a bell, a small motor, an induction coil, a few Geissler’s 
 tubes, a solenoid, a galvanometer, &c. 
 
 In all the experiments with the small generating machine 
 we are always obliged to join the two terminals of the machine 
 by something, and that something we name a conductor. 
 This conductor is the seat of all the various phenomena caused 
 by the passage of what we call the electric current ; but as 
 before stated, it is not the purpose of this work to investigate 
 the cause and nature of that current ; suffice it for us to 
 examine its effects when we have produced it in any of the 
 known ways. 
 
 In order to obtain a tangible idea of this electric current, 
 it is convenient to assimilate it to an actual flow in the 
 conductor, and to compare this supposed flow to the flow of 
 water in a pipe. This is, we repeat, merely a conventional 
 notion, but is universally adopted to assist the ideas. 
 
Domestic Electricity for Amateurs. 5 
 
 This being admitted, as also that water only flows when 
 there is a difference of level or pressure, and that the flow is 
 from the highest to the lowest level or pressure, so we will 
 suppose the electric current to flow from the highest to the 
 lowest pressure or potential as it is usually termed. 
 
 This hypothetical and imaginary current then starts from 
 a point where the electric level or potential is highest — or the 
 positive pole — to the point where the potential or electric level 
 is lowest — or the negative pole. 
 
 In all the ordinary batteries the negative pole is always 
 the zinc plate, the positive pole is the other, whether copper, 
 carbon, or platinum. When the two poles are united by a 
 conductor, the electric current goes from the + pole (copper, 
 carbon, or platinum) to the — pole through the conductor. 
 
 Continuing our comparison between the electric current 
 and the flow of water in a pipe, we can define and materialise 
 in some way the three most important factors in this 
 circulation. 
 
 In a flow of water we have to consider the pressure or 
 difference of level by reason of which the fall is produced ; 
 the delivery of the pipe, expressed by the number of gallons 
 of water which pass in a given time, and finally the friction 
 of the pipe which opposes the flow and tends to diminish the 
 delivery. 
 
 In the same way, in an electric current, the difference 
 of potential between two given points of a circuit is equal 
 to the difference of the level in the water. The electromotive 
 force is the cause which produces this potential difference. 
 
 The current represents the output of the pipe, and the 
 resistance of the conductor is the obstacle which it opposes 
 to the passage of the current ; this is a factor analogous to the 
 friction in the water-pipe. 
 
 It will easily be understood that the current will be the 
 greater the higher the pressure and the less the resistance 
 opposed by the conductor to the passage of the current. 
 
 These relations between the three electrical measurements, 
 electromotive force^ resistancey and current^ are expressed by 
 the aid of a very simple law propounded by Ohm in 1827. 
 
6 
 
 Domestic Electricity for A mateurs. 
 
 This law, known as Ohm’s law, is expressed by the following 
 very simple formula : 
 
 It expresses that the current (C) in an electric circuit is 
 proportional to the electromotive force (E), and inversely 
 proportional to the resistance of the circuit (R). 
 
 Electrical Units. 
 
 In order to turn this simple relation between the three 
 principal electric measurements to account, a common measure 
 is necessary for the purpose of comparison. 
 
 The electrical measurements at present universally re- 
 cognised and adopted are those fixed by the International 
 Congress of Electricians held at Paris in i88i, and by the 
 International Commission of 1884. The entire system of 
 electrical units is called the C.G.S. system, which recalls its 
 origin as it is based on the three fundamental units, viz. 
 the centimetre, as unit of length, the gramme as unit of mass, 
 and the second as unit of time. 
 
 We shall not now demonstrate the relation of all the 
 electrical units one to another and to the fundamental units, 
 but it will suffice for us that the Congress and the Commission 
 fixed the practical units of measurement as well as their names. 
 
 Unit of Electromotive Force . — The practical unit of electro- 
 motive force, usually written E.M.F., is the volt. An idea of 
 the volt is easily obtained by comparing it with known bat- 
 teries. The electromotive force of a Daniell cell is about 
 I volt ; of a newly charged Leclanche i -48 volt ; of a Bunsen 
 from I *8 to 1*9 volts ; of a Plante accumulator from 1*9 to 2 
 volts. 
 
 Unit of Resistance . — The practical unit of resistance is the 
 ohm. This is the resistance at 0° C. of a column of mercury 
 of one square millimetre in section and 106 centimetres in 
 length. A copper wire 48 metres long and one millimetre 
 diameter has i ohm resistance. About 100 metres of iron 
 wire 4 millimetres in diameter go to one ohm. 
 
Domestic Electricity for A mateurs. 
 
 7 
 
 Unit of Current. — The practical unit of current is the 
 ampere. This is the current which traverses a circuit of 
 I ohm resistance, with a difference of potential of i volt 
 between its two ends, thus : 
 
 , volt 
 
 I ampere = i — . 
 
 ohm 
 
 Ordinary bells require about a quarter of an ampere ; 
 incandescent lamps require from o • 8 to 2 amperes ; arc 
 lamps require according to their power from 5 to 120 amperes ; 
 the large Edison machines for lighting produce up to 1000 
 amperes ; and some machines for plating purposes give up to 
 3000 amperes. 
 
 On the other hand telephone currents are calculated by 
 milli-amperes. 
 
 Electric Quantity and Unit of Quantity. — If through a pipe 
 water flows during a certain time, the quantity of water 
 which has passed is proportional to the delivery of the pipe 
 and to the time. 
 
 In the same way, when a current C traverses a conductor 
 during a time t^ the quantity Q which traverses the con- 
 ductor is proportional to the product Ct. Thus the idea of 
 electric quantity and the definition of the unit of quantity are 
 arrived at. 
 
 The practical unit of quantity is the coulomb. This is 
 the quantity of electricity which traverses a conductor during 
 a second when the current is one ampere. 
 
 The law of Faraday shows the relationship between Q, C, 
 and /, and is written : 
 
 Q = a. 
 
 It gives for the practical unit of quantity : 
 
 I coulomb = I ampere x i second. 
 
 Practical engineers have adopted another unit of quantity 
 directly derived from the coulomb, the ampere-hour. The 
 ampere-hour is the quantity of electricity which traverses a 
 conductor in one hour, or 3600 seconds, when the current is 
 
8 Domestic Electricity for A mateurs. 
 
 I ampere, that is to say when one coulomb per second flows 
 through the conductor. 
 
 From this definition it results that : 
 
 I ampere-hour = 3600 coulombs. 
 
 These general ideas are sufficient for the amateur 
 electrician to solve the simple calculations which he will 
 require, and they will become clearer as we advance. 
 
Domestic Electricity for Amateurs. 
 
 9 
 
 CHAPTER I. 
 
 PRODUCTION OF THE ELECTRIC CURRENT. 
 
 Before passing in review the different applications to which 
 electricity, or more correctly electrical energy, easily lends 
 itself, we must learn to produce this electrical energy. 
 
 The agencies which enable us to produce it reduce them- 
 selves to three : 
 
 Chemical action as utilised in primary batteries ; 
 
 Thermo-electric action as utilised in thermopiles ; 
 
 Mechanical action as utilised in the machines incorrectly 
 called static and in magneto and dynamo-electric machines. 
 
 Thermopiles have not yet arrived at a sufficient degree of 
 perfection to enter into practice, and are in fact of no use to the 
 amateur electrician ; static or frictional machines are only 
 useful for scientific or amusing experiments ; we shall later on 
 have a few words to say respecting these latter. Magneto 
 and dynamo-electric machines require a motive power rarely 
 at the amateur’s command. 
 
 We have therefore only primary batteries left, which are 
 up to the present the only practical generators generally 
 available for the amateur electrician. 
 
 Taking into account the uses to which they are applied, 
 primary batteries may be divided into two perfectly distinct 
 classes : one intended for applications which require but 
 small electrical powers, the others requiring greater power 
 and constancy. We distinguish them, to fix the idea in the 
 mind, as batteries for . intermittent use, and batteries for 
 continuous use. 
 
lo Domestic Electricity for Amateurs. 
 
 I. Batteries for Intermittent Use. 
 
 Batteries for intermittent use are more especially applicable 
 to bells, alarms, domestic telephones, gas-lighters, and for 
 certain amusing experiments which we will describe in due 
 course. 
 
 The essential qualities for these various applications are 
 the following : cheapness ; erection, maintenance, and super- 
 vision easy; long durability; absence of all local action on open 
 circuit ; not to be obliged to renew the active elements too 
 ' often ; and, finally, sufficient power to satisfy the demands of 
 the various apparatus required to be operated. 
 
 The best battery of this description is no doubt the 
 Leclanche in one or other of its forms. 
 
 Fig. 3. 
 
 Porous-pot Leclanchl . — This element is composed of a block 
 of carbon surrounded by a mixture of powdered carbon and 
 
Domestic Electricity for Amateurs, 1 1 
 
 black oxide of manganese inclosed in a cylindrical porous pot. 
 The negative pole is a rod of amalgamated zinc standing in an 
 exterior glass jar partly filled with a solution of sal-ammoniac 
 (Fig. 3). 
 
 Agglomerate Leclanchl , — The mixture of carbon and oxide 
 of manganese is here replaced by blocks of the mixture com- 
 pressed into the solid form in heated steel moulds (Fig. 4 ). 
 
 Fig. 4. 
 
 The Leclanche cell, whether of the porous pot or agglo- 
 merate form, is perhaps the most useful cell known for inter- 
 mittent work, although it polarises easily and quickly if used 
 continuously on a circuit of low resistance, and is useless for 
 lighting, plating, or other work where a continuous and large 
 current is required. 
 
 To insure proper working and duration, it should be 
 remembered that it is advisable : 
 
 I. To place the elements in a dry place and medium 
 temperature. 
 
1 2 Domestic Electricity for Amateurs, 
 
 2. To coat the inside of the neck of the glass jar, if it has 
 not already been paraffined, with a coat of oil or tallow for 
 about an inch down, to avoid the creeping of the salts. 
 
 3. To take care that the contacts are in good order, and 
 the conducting wires well insulated. 
 
 4. If, in consequence of evaporation, the level of the water 
 has fallen too much, to fill up to about two-thirds the height 
 of the jar. 
 
 5. When the liquid, which was originally clear, becomes 
 milky, this is a sign that it wants sal ammoniac, and it is 
 necessary to renew it. 
 
 6. To scrape off the crystals which sometimes settle on 
 the zincs ; this is the result of an excess of sal-ammoniac. 
 
 Duration of Leclanche Batteries. — It is impossible 
 to estimate by time only the duration of Leclanche elements, 
 or, in fact, of any battery whatsoever. A battery, newly 
 charged, represents a certain supply of combustible, zinc, and 
 a certain supply of an oxidiser, which, in this case, is repre- 
 sented partly by the sal-ammoniac and partly by the oxygen 
 contained in the black oxide of manganese. 
 
 As soon as one of these bodies — zinc, sal-ammoniac, or 
 manganese — is exhausted, the battery ceases to act, and it is 
 necessary to renew the stock ; that is to say, to recharge the 
 battery, by replacing the zinc, the solution, or the agglomerate. 
 For example, let us suppose that the stock of sal-ammoniac 
 is sufficient to furnish an amount of electricity equal to 
 25,000 coulombs, and that the battery is used solely for 
 domestic bells requiring 0*25 ampere. The bells expend a 
 quarter of a coulomb per second ; the battery can therefore 
 act for a duration of 
 
 25,000 X 4 = 100,000 seconds. 
 
 If we make on an average 25 calls per day of 4 seconds 
 each, we expend exactly i coulomb per call, and 2 5 coulombs 
 per day; the battery acts therefore for 1000 days, that is to 
 say, nearly three years. If we make 100 calls per day, the 
 charge will be exhausted at the end of eight months; but 
 in any case, when the total duration of action amounts to 
 
Domestic Electricity for Amateurs. 
 
 13 
 
 100,000 seconds, or, more correctly, when the battery has 
 supplied 25,000 coulombs of electricity, it will cease to act. 
 
 If the wires are badly insulated, so that leakage ensues, 
 the battery may be slowly exhausted in a continuous way 
 without the corresponding useful work being effected, and this 
 is a frequent cause of failure of the battery. When the wires 
 are badly insulated, the only sure remedy is to put the whole 
 of the wires up afresh, taking every precaution and care. 
 
 Dry Batteries. — To avoid the inconvenience of the 
 liquids, many people have thought to make dry batteries by 
 filling the cells up with asbestos, sand, or other spongy sub- 
 stance to soak up the liquid, but we cannot recommend these 
 batteries for general use, for several reasons. The presence of 
 inert substances in the cells increases their internal resistance 
 while decreasing the bulk of the active liquid ; and also this 
 inert matter hinders the circulation of the solutions and the 
 renewal of the parts in direct contact with the electrodes, 
 which makes polarisation set in more quickly. 
 
 Bichromate of Potash Batteries.— In order to obtain 
 intermittent efforts of short duration and great power, the 
 bichromate of potash battery, either 
 single or double fluid, is the most 
 convenient and most powerful. 
 
 When a fairly powerful current 
 is required only for a few minutes, 
 the bottle form is very convenient, 
 see Fig. 5. 
 
 They are made in all sizes from 
 half a pint to a gallon, or more. 
 
 In principle it is composed of an 
 amalgamated zinc plate placed be- 
 tween two carbons. 
 
 This zinc plate is suspended by 
 a rod of brass, which moves up 
 and down, fitting tightly in a spring 
 socket, and can be lowered into the liquid or withdrawn at 
 will. 
 
 The exciting liquid is composed of bichromate of potash, 
 
14 
 
 Domestic Electricity for Amateurs. 
 
 dissolved in sulphuric acid and water (for preparation of the 
 solution, see page 93). 
 
 Batteries for Continuous Use. — When batteries are 
 required for continuous work, as for instance for plating, 
 domestic electric lighting, charging accumulators, &c., it is 
 necessary that they possess special qualities very difficult to 
 unite in the same apparatus. 
 
 One of the oldest batteries is the Daniell cell, so well 
 known that it appears unnecessary to describe it. 
 
 Callaud’s Battery. — This form of Daniell, which is 
 much used, is one in which the solution of sulphate of copper 
 is separated from the sulphate of zinc solution, by reason of 
 the difference of density between the two solutions. The 
 form we give (Fig. 6) is very simple, and in consequence 
 
 Fig. 6. 
 
 cheap. The glass vessel is about 5 inches in height and 3 in 
 diameter. The zinc is supported by three projections or lips 
 made with a pair of pliers. The copper pole is a flat spiral 
 of copper wire, the end of which rises vertically through the 
 middle of the vessel ; this vertical part is protected by a small 
 glass tube. The elements are joined up by means of a small 
 spiral at the end of the wire soldered to the zinc, into which 
 the copper of the nest cell is inserted. 
 
 The worst of Daniell cells is that they run down when on 
 open circuit. 
 
15 
 
 Domestic Electricity £or Amateurs, 
 
 Modified Callaud Battery. — This is easier to maintain 
 and has less local action. It is in use in the telegraphic 
 service of the Eastern Railway Company of France, and may 
 be useful to amateur electricians for plating purposes, and for 
 the slow charge of small accumulators. 
 
 This battery differs from the foregoing by replacing the 
 positive electrode, that is to say the copper plate, by a lead 
 pipe open at both ends and plunged into the liquid of the 
 battery as shown in the figure. The lead, which is not 
 attacked, lasts indefinitely ; it is kept 
 in its vertical position by the lower 
 end being slit up, and the tongues, so 
 formed, spread out ; these tongues 
 also serve to prevent the lead tube 
 from touching the zinc. 
 
 To charge the element, the lead 
 tube is filled with crystals of sulphate 
 of copper, and water is poured into 
 the glass vessel until it is within about 
 half an inch of the top of the zinc. 
 
 At the end of an hour the sulphate of 
 copper crystals have sufficiently dis- 
 solved to enable the battery to act. 
 
 Experience has shown that whatever supply of sulphate 
 is put into the lead tube the sulphate solution never reaches 
 the zinc, even when the circuit is open. 
 
 This arrangement has the great advantage that it may be 
 given into anybody’s charge, since the only thing necessary 
 is merely to replenish the central tube with sulphate of copper 
 crystals when the blue tint of the lower liquid disappears, and 
 to proportion the expenditure to the work actually done. 
 
 Lalande & Chaperon’s Oxide of Copper Batteries. 
 — These batteries to a certain extent combine the duration of 
 the Leclanche with the power of the bichromate of potash. 
 
 They vary in shape and size according to the purposes for 
 which they are intended. In principle they always consist of 
 a plate or cylinder of amalgamated zinc as active metal, a 
 solution of 30 or 40 per cent, of caustic potash as exciting 
 
 Fig. 7. 
 
i6 Domestic Electricity for Amateurs. 
 
 liquid, and oxide of copper in direct contact with a plate of 
 iron or copper as depolariser. 
 
 Owing to the choice of materials, the battery will work 
 on a continuously closed circuit for several days, without 
 excessive polarisation, and almost up to complete exhaustion 
 of the products : the transformation of the potash into oxide 
 of zinc, and the progressive reduction of the copper oxide, act 
 without the constants varying sensibly. The initial E.M.F. 
 some hours after setting up the elements is somewhat less 
 than I volt ; when in continuous use, it is about 0*85 volts, 
 at which it is maintained. 
 
 The internal resistance varies with the dimensions of the 
 elements : its duration depends on the current taken out and 
 the quantity of the active materials, zinc, caustic potash, and 
 
 oxide of copper, contained in the 
 ^ element at the time of setting up. 
 
 Fig. 8 represents the spiral 
 elements intended for applications 
 which require a small current, as 
 for instance, for telegraph or tele- 
 phone purposes. It is about 7 
 inches high and 4 inches diameter, 
 and can supply 200,000 coulombs, 
 or 5 5 ampere-hours, with a delivery 
 which, for this type of element, 
 should not exceed half an ampere. 
 
 The heavy current cell. Fig. 9, 
 is in the form of a rectangular 
 trough of sheet iron, which serves 
 at the same time as containing- 
 vessel and pole. The bottom of 
 the trough is covered with oxide of copper, and the amalga- 
 mated zinc plate is placed horizontally over the oxide, 
 resting on four cement supports fixed in the corners. A 
 layer of heavy petroleum over the solution insures the closing 
 up of the element, and keeps the potash from the action of 
 the air. 
 
 The small model is 10 inches long, 5J inches wide, and 
 
Domestic Electricity for Amateurs » 17 
 
 4 inches in depth. It can give 6 amperes, and furnishes about 
 800,000 coulombs, which corresponds to a deposit of 250 
 grammes of copper. The large model is 16 inches long, 
 8 inches wide, and 4 inches in depth. Its delivery is 15 to 
 18 amperes, and it can supply 1,800,000 coulombs of electricity. 
 
 Fig. 9. 
 
 which is equal to 500 ampere-hours. This cell is supposed 
 to supply at will i ampere during 500 hours, 10 amperes 
 during 50 hours, or 15 amperes during 33 hours. 
 
 They are suitable for all applications where a Bunsen 
 battery is employed, if every quart Bunsen be replaced by 
 two of these in tension in order to have the same electro- 
 motive force. 
 
 They can be used for electric lighting by arc or in- 
 cande.scence, for big induction coils, plating, charging accu- 
 mulators, &c. They have the advantage over the Bunsen 
 elements, inasmuch as they give off no injurious or dis- 
 agreeable fumes. They act without attention until exhausted, 
 and above all, have the essential quality of practically 
 consuming nothing when the circuit is open. 
 
 Its disadvantage, however, is that it necessitates the use 
 of the destructive caustic potash, and it is necessary to 
 carefully keep this battery in a place where the accidental 
 upsetting of a cell will have no serious consequences. 
 
 Cast-iron Hermetically Closed Cells.— These have 
 the advantage of being easily transported and possessing a 
 great solidity, one of the most important qualities for elements 
 holding a caustic liquid. 
 
 In the 4-inch or small current cell, Fig. 10, the exterior 
 
 C 
 
1 8 Domestic Electricity for Amateurs. 
 
 cast-iron case has the appearance of a conical shell. It 
 constitutes the positive pole of the element ; a shoulder A 
 in the casting forms the terminal. The exterior of the pot 
 
 is coated with paraffin, so as to 
 prevent rusting and leakage. The 
 zinc D consists of a cylinder | inch 
 in diameter soldered to a brass 
 rod K fixed in the indiarubber 
 stopper G, and carrying the ter- 
 minal F. The stopper has also 
 passing through it a metallic tube 
 ending in a valve H formed of a 
 bit of soft indiarubber tube. 
 
 These elements are generally 
 delivered filled with the potash 
 solution, so that in order to set 
 them up, it is sufficient to pour in 
 the proper quantity of copper ox- 
 ide, which distributes itself on the 
 bottom B, and to close the element 
 up by means of the indiarubber 
 stopper with the zinc fixed. 
 
 This arrangement is especially convenient for house work, 
 telephones, bells, &c. This model can give as much as 
 2 amperes. A smaller size of 2 inches in diameter is sufficient 
 for house bells for several years. 
 
 Fig. 1 1 represents another type of the hermetically closed 
 element, intended for larger currents, about 9 inches in diameter, 
 giving up to 8 amperes, which enables it to be used in place 
 of Bunsen or bichromate cells. The arrangement of this 
 element is much the same as the preceding one. The copper 
 oxide B is at the bottom of the pot ; the zinc D, made by a long 
 plate rolled in spiral shape to present a great surface, is sus- 
 pended from an ebony lid G fixed in the mouth of the jar by 
 means of an iron ring and three screws ; a soft rubber washer 
 insures the closing of the joints. 
 
 These elements hold the same charge as the large trough- 
 cells, and can be substituted for them in all applications. 
 
 Fig. 10. 
 
Domestic Electricity for Amateurs. 19 
 
 They can do considerable work ; for example, a trough battery 
 could light for 200 hours a 5 -candle Edison lamp. By em- 
 ploying six elements nearly two months of nickel-plating work 
 of seven hours per day has been done, which necessitates the 
 
 Fig. II. 
 
 use of three Bunsen elements : these require recharging every 
 two days. These cast-iron cells have the remarkable property 
 of giving a much heavier current without polarisation than 
 corresponding non-metallic elements of which the conducting 
 surface in contact with the copper oxide is as great. As 
 hydrogen is not set free on the iron, the inventors claim that 
 its surface must nevertheless occlude the hydrogen which 
 travels along to the copper oxide, and thus contributes to the 
 depolarising action. 
 
 The Conventional Sign for a Battery. — A con- 
 venient plan universally adopted represents a battery by the 
 conventional signs shown in Fig. 12. The thick stroke stands 
 for the positive pole, the thin stroke the negative pole, and 
 the number of pairs for the number of elements. Fig. 12, for 
 example, shows a battery of five cells, of which the positive 
 pole is to the left and the negative pole to the right. 
 
 c 2 
 
20 Domestic Electricity for Amateurs. 
 
 Connecting-up Batteries. — Amateurs generally ex- 
 perience much difficulty in not knowing how to couple up 
 a battery, of which they have a given number of elements, so 
 
 Fig. 12. 
 
 as to obtain through a given resistance the greatest current 
 possible with this given number of cells. There exist methods 
 whereby this coupling up is determined with certainty in each 
 particular case, which we will endeavour to explain, avoiding 
 complicated formulae, and by giving some practical examples, 
 facilitate their use even to those little accustomed to algebraical 
 calculations. 
 
 The determination of the best method of coupling up is 
 governed by three measurements which must be expressed in 
 the electrical units, volts and ohms, before they can be used 
 in formulae. These measurements are : — 
 
 1. The electromotive force of one element E expressed in 
 volts. 
 
 2. The internal resistance of this element r, expressed in 
 ohms. 
 
 These two quantities, which are called the constants of the 
 battery, are generally supplied by the makers ; they vary 
 with the nature and dimensions of each element. 
 
 3. The external resistance R, expressed in ohms. 
 
 This resistance comprises not only the resistance of the 
 conductors, but also that of the instruments to be worked. 
 
 In the most simple case, where a single cell is placed in 
 the circuit, the current C expressed in amperes is : — 
 
Domestic Electricity for A mateurs, 2 1 
 
 When several elements are available, they may be coupled 
 up in various ways, for example : — 
 
 1. All the cells may be coupled in quantity (otherwise 
 called in parallel or in multiple arc), that is to say, all the 
 zincs joined up to each other in such a way as to- make a 
 battery of which the electromotive force is that of a single 
 cell, but of which the internal resistance is as much smaller as 
 the number of elements is greater. 
 
 2. All the cells may be coupled up in tension or series, that 
 is to say, the zinc of the first cell coupled to the carbon of the 
 second, the zinc of the second to the carbon of the third, and 
 so on. In this way both the electromotive force and the 
 internal resistance are multiplied at the same time by the 
 number of elements. 
 
 Between these two extremes a middle course is often 
 advisable, which we will explain by example. 
 
 Let us suppose we have 20 cells available. These 20 
 elements enable us to obtain the following 6 combinations : 
 1st. 20 cells in quantity, and i in tension. 2nd. 10 cells in 
 quantity, and 2 in tension. 3rd. 5 cells in quantity, and 4 in 
 tension. 4th. 4 cells in quantity, and 5 in tension. 5th. 2 cells 
 in quantity, and 10 in tension. 6th. i cell in quantity, and 
 20 in tension. 
 
 According to the resistance of the external circuit, one or 
 the other of these arrangements will be found most advan- 
 tageous. The variations of the current when the external 
 resistance is varied may be represented by a curve. Fig. 1-3 
 represents these curves, in which the abscissae are the external 
 resistances in ohms, and the ordinates the corresponding 
 currents in amperes. To simplify the calculations of these 
 curves, we have assumed a battery of which the E.M.F. is 
 exactly i volt, and the internal resistance i ohm. In practice 
 this corresponds nearly to a large Daniell. By consulting 
 the curves, it is seen, for example, that with an external 
 resistance of 5 ohms, that is to say, five times that of the 
 element, the maximum current is obtained by arranging 
 10 cells in tension and 2 in quantity, it is therefore i ampere. 
 By arranging the 20 elements in quantity, C = 0*22 only is 
 
22 Domestic Electricity for Amateurs. 
 
 obtained, not much more than that given by a single cell. A 
 careful study of these curves will give a very good idea of the 
 importance of properly connecting up a battery when the 
 constants, the number of cells, and the external resistance are 
 given, and it will appear generally that quantity arrangement is 
 best for low external resistance and tension for high external 
 resistance. By comparing the dotted curve which corresponds 
 
 to a single cell with curve No. VI., it will be seen that on a 
 circuit of no resistance 20 elements in tension do not give 
 more current than one. The comparison between the dotted 
 curve and curve I., on the other hand, shows that for great 
 resistances a single element gives as much current as 20 in 
 quantity. The crossing points of these curves indicate the 
 resistance with which it is immaterial whether one or other 
 corresponding arrangement be adopted. 
 
 The following are the formulae by which it is possible to 
 determine the arrangement which gives the maximum external 
 work and the value of the corresponding current : 
 
 Let t be the number of elements arranged in tension ; 
 q the number of elements arranged in quantity ; 
 n the total number of elements : 
 
 then n ■= tq. 
 
 The current in an external circuit of a resistance R, if E 
 
Domestic Electricity for Amateurs. 23 
 
 is the E.M.F. of one element, and r its internal resistance, 
 will be 
 
 C = 
 
 -^ + R 
 
 {d) 
 
 By varying t and q in such a way that the product t q remains 
 constant, there is a maximum for the external work when 
 
 (^) 
 
 The external work is a maximum when the number of 
 elements in tension (f) is to the number of elements in 
 quantity (f) as the external resistance (R) is to the resistance 
 of each element (r). 
 
 Numerical Example . — What is the best arrangement for a 
 battery of eight Daniells (E = 1*07 volts, r = 6 ohms) to 
 work a bell whose resistance is 10 ohms on a line whose 
 resistance is 4 ohms ? 
 
 According to the given problem, R = 10 + 4 = 14 ohms. 
 The formula {U) gives : — 
 
 In practice it is necessary to take for t and q, the numbers 
 approaching nearest to this ratio. In this particular case, it is 
 by taking ^ = 4, ^ = 2 that the equation is best satisfied. 
 
 Under these conditions, the current calculated by the 
 formula {d) will be : — 
 
 ^ 4 X ^ 4 X 1-07 
 
 } X 6 4 - 14 12+14 
 
 C = o - 16 ampere. 
 
 By coupling up the 8 cells in tension f = S, q = i the 
 formula (a) gives : 
 
 8 X I '07 , , 
 
 C = ;r — ~ = O’ 14 ampeie, nearly. 
 
 8 X 6 + 14 
 
 By coupling up the 8 cells in quantity / = i, q = 8, the 
 formula {a) gives: — 
 
 r^n 1*07 
 
 C = g = 0*07 ampere. 
 
 ¥ +14 
 
24 Domestic Electricity for Amateurs. 
 
 It will be seen that the latter method gives a current 
 less than half the maximum. 
 
 When the constants of the batteries, the number of ele- 
 ments at disposal, and the resistance of the external circuit 
 are known, formulae (a) and {U) enable us to determine the 
 ratio between t and q, which gives C a maximum, and to cal - 
 culate exactly the value of this current corresponding to each 
 particular coupling up of the cells. 
 
 In conclusion we give some practical figures respecting the 
 batteries mostly employed for domestic purposes which may 
 serve as a guide when electric bells, lighters, &c., are required 
 to be installed. 
 
 The porous pot Leclanch6 has an E.M.F. of i *4 volt and 
 an internal resistance of about 5 ohms. The new agglomerate 
 Leclanchds have the same E.M.F., but the internal resistance 
 is only 1 • 2 ohm. After long use the E.M.F. falls to i volt 
 and the internal resistance attains 2 * 5 ohms. 
 
 Daniell elements have an E.M.F. of 1*07 volt. Their 
 resistance varies much with their dimensions. The large 
 circular cells 8-inches high have 3 ohms resistance ; those used 
 for telegraph purposes vary between 5 and 20 ohms. 
 
 The Bunsen battery has an E.M.F. of r* 8 volt ; the circular 
 cell 8-inches high has a resistance of 0*25 ohm. 
 
 Niaudet’s battery has for constants E = i, r = 5. 
 
 The bichromate of potash battery has an E.M.F. of 2 
 volts when fresh charged ; the quart bottle battery has a 
 resistance of about i ohm. 
 
 These figures are only approximate, especially those 
 relating to internal resistance, which varies greatly with the 
 degree of saturation of the liquids, the surface of the plates, 
 their distance, &c., but in any case they serve as a guide, and 
 may prevent grave errors. 
 
 The currents required vary greatly according to the nature 
 of the appliances. 
 
 Keeping ourselves to domestic appliances and telegraphs, 
 we give some figures, the results of experience. 
 
 The bichromate gas-lighters act with currents which vary 
 between one ampere and one-tenth of an ampere, according 
 to the size of the incandescent spirals. 
 
Domestic Electricity for Amateurs, 
 
 25 
 
 Domestic bells act very well with two Leclanch^ cells in 
 tension ; the resistance of the wires does not exceed 2 ohms, 
 that of the bells varies between 5 and 10 ohms. 
 
 Under average conditions the current is therefore : — 
 
 C = 
 
 2 X 1-4 
 2 X I ‘2 + 10 
 
 = 0*23 ampere. 
 
 Polarisation, bad contacts, &c., reduce this to 0'20 ampere 
 or 200 milliamperes. 
 
 Telegraphic currents under ordinary circumstances are 
 not more than lO milliamperes, which is twenty times less. 
 The attraction on the armature is, however, the same in both 
 cases. This difference is thus explained : in domestic bells 
 the proportionately large wire takes a small number of turns 
 round the electro-magnet, whilst in telegraphic apparatus 
 the number of turns is much greater. The attractive power 
 depending on these two factors, what is gained in current is 
 lost in the less number of turns, and besides, the electro- 
 magnets of domestic bells are used on comparatively short 
 circuits, while the electro-magnets of telegraphs are included 
 in a long circuit of great resistance. 
 
 It is therefore necessary before connecting a battery for a 
 given instrument, to know exactly its resistance and the current 
 necessary to enable it to act properly. 
 
 The formula {a) will give the number of cells of a battery 
 of which the. constants E and r are known, necessary to 
 produce a current C in the circuit of the apparatus, for by 
 combining it with formula {U) a double equation will be 
 formed of two unknown quantities easily solved. In fact, the 
 ■ formulae {a) and {b) give t and q ; the value of n will then be 
 the product, provided we take t and q as the whole number 
 nearest to the exact value, it being impossible to divide into 
 fractions the cells of a battery. In case the number of 
 elements n is determined beforehand, the formula {h) will give 
 the arrangement which gives the maximum current, and the 
 formula {a) will give the value of this current. It will then 
 be seen if it is more or less than that required by the apparatus 
 in order to work properly. 
 
26 
 
 Domestic Electricity for Amateurs. 
 
 CHAPTER II. 
 
 ELECTRIC BELLS. 
 
 The most simple and practical application to which the 
 amateur electrician can direct his first knowledge and obtain 
 tangible results is without doubt the installation of electric 
 bells in a room or house. We will therefore commence with 
 them, describing all the necessary details. Reduced to its 
 most simple character the system always includes at least four 
 essentials : the electric generator, which here will always 
 consist of a battery ; properly insulated conductors ; the 
 contact-maker to close the circuit between the battery and the 
 bells ; and, finally, the latter themselves. We will review the 
 arrangements employed in ordinary practice. 
 
 The Battery. — The Leclanche battery is the most con- 
 venient for electric bells. Porous pot elements are sufficient 
 if they are used exclusively for bells; if gas-lighters, fire- 
 alarms, alarum clocks, &c., are wanted to be installed at the 
 same time the agglomerated form is perhaps better. Four 
 cells in tension are sufficient for most cases. 
 
 The small Lalande and Chaperon batteries are also good 
 for electric bells ; three to four elements in tension are 
 sufficient. 
 
 Laying the Conductors. — The conductors placed in 
 interior of houses are usually of copper, covered with an in- 
 sulating compound such as indiarubber, &c. 
 
 For short lines, and in dry places, wire simply covered with 
 silk or cotton may also be used. 
 
 The size of the wires necessarily varies with the length of 
 the circuit, the nature of the apparatus to be worked, and the 
 
Domestic Electricity for Amateurs, 27 
 
 number of elements to be used. We give some figures which 
 may be taken as the average in practice. 
 
 Let us take for example a very usual form of installation, 
 consisting of a battery of three or four cells in the basement 
 or elsewhere, to work the front door and various rooms and 
 floors. Under these circumstances three sizes of wire are 
 used : — 
 
 1. Between the battery in the basement and the staircase, 
 
 wire of should be used. This is about equal to 
 
 No. 18 B.W.G. 
 
 2. In the staircase, wire of or i mm., equal to No. 19 or 
 20 B.W.G. 
 
 3. For the interior communication of the apartments, wire 
 of will be quite sufficient. Nos. 21 or 22 B.W.G. 
 
 In practice it need never be feared to use wire too large, 
 except for the price. In the case of which we speak, in large 
 towns, half of this wire may be saved by fixing the negative 
 end of the battery to water or gas pipes, in which case all the 
 negative branches from the various bell-pushes, &c., must be 
 taken to the nearest gas or water pipe ; these pipes then act 
 as return wires and simplify the installation. 
 
 Wires covered with silk and cotton of all shades may be 
 obtained to match the wall-papers and other furniture. They 
 should be fixed to the walls, avoiding contact as much as 
 possible, especially at sharp corners, which tend to cut the 
 
 Fig. 14. 
 
 insulation ; they may be con- 
 cealed in the mouldings, 
 cornices, or corners, or where 
 appearance has to be specially 
 studied, ornamental hollow 
 casing may be laid over 
 them. 
 
 To keep the wires in posi- 
 tion, bone insulators (Fig. 14, 
 
 No. i), may be used nailed 
 into the wall, round which a turn is taken with the wire ; for 
 re-entering angles enamelled hooks (Fig. 14, No. 2) of a con- 
 venient size are used. Staples (Fig. 14, No. 3) are also used ; 
 
28 Domestic Electricity for Amateurs. 
 
 they are easily fixed, and the price very moderate, but care 
 must be used in driving them in not to cut the insulation. 
 
 When the wires go through the walls it is important to 
 keep them from dampness ; they should then be covered by 
 an indiarubber tube of suitable diameter, drawn out for half- 
 an-inch or so on each side of the wall to keep the wires from 
 contact with the sharp edges of the hole. 
 
 Thre junction of the wires is effected by stripping the two 
 ends to be joined for about two inches, cleaning them with 
 sandpaper and twisting the two ends five or six times over 
 each other. 
 
 The joint must then be covered by a thin sheet of softened 
 rubber by rolling it between the fingers and then with a layer 
 of cotton similar to that of the rest of the wire. When double 
 wire is used it is advisable not to make the two joints at the 
 same place, but about two inches apart. 
 
 It is often convenient to use two wires covered with rubber, 
 inclosed in the same cotton or silk covering. 
 
 Joining the wires with the springs of the contact-maker 
 and the terminals of the bells presents no difficulty. 
 
 Contact-makers. — Under this general head may be in- 
 cluded every device which, by a simple mechanical motion, 
 allows an electric communication to be established. The most 
 simple arrangement for this purpose is the ordinary bell-push 
 (see Fig. 1 5). It is so well known that we need not describe it ; 
 
 Fig. 15. 
 
 it varies in form, size and nature, according to requirement. It 
 is made of wood, ebony, porcelain, bronze, copper, ivory, 
 celluloid, &c. The most simple form may be bought for 
 sixpence. It is simply fixed to a wall, panel, &c., by means 
 
Domestic Electricity for Amateurs. 
 
 29 
 
 of two wood-screws, taking care to plug the wall previously 
 if necessary. For outside doors pulls or presses are some- 
 times used, in which the contact arrangement differs, but the 
 method of working will be understood from Fig. 16. 
 
 Fig. 16. 
 
 These outdoor contact-makers are more solid and less 
 liable to damage than the ordinary pushes ; they are also not 
 so likely to get out of order by oxidation as the contact is a 
 sliding or rubbing one which keeps the surfaces clean. 
 
 By a most ingenious and simple device recently patented 
 by Mr. Kenneth D. Mackenzie, the person making the call by 
 pressing the call button may have audible evidence that the 
 bell at the other end of the circuit has really rung. This 
 apparatus may be added to any existing presses, or a special 
 press may be used inclosing the ordinary contact-maker and 
 the sounding apparatus in a neat box, slightly larger than the 
 ordinary button. The sounder consists of a small bobbin 
 included in the line circuit. This bobbin has a soft iron core, 
 and stands in a little round box of tinned iron, the base of 
 the core being screwed to the bottom of the box. The lid is 
 then put on, and is so arranged that though close to the top 
 of the iron core, it is not in contact with it. When the make 
 and break current passes, the core and box are alternately 
 magnetised and demagnetised, producing a vibrating tinkle 
 easily heard. This then gives instant indication to the person 
 ringing that the bell at the other end has actually sounded. 
 
 In offices, public institutions, hotels, &c., where it is 
 necessary to call various different persons, multiple contacts 
 are used, of which Fig. 17 shows some specimens. The hand 
 in the form of a paper weight is a multiple contact, and calls 
 
30 
 
 Domestic Electricity for Amateurs, 
 
 are made by pressing one or other of the bracelet stones. A 
 flexible wire to the various conductors established the necessary 
 communication. It is sometimes more convenient to have a 
 
 Fig. 17. 
 
 movable push ; it is then placed at the end of a flexible 
 cord. Fig. 18 represents some of the means employed. 
 
 Fig. 18. 
 
 123 4 
 
 No. 4 shows a contact-maker, resembling in use and appear- 
 ance an ordinary crank bell-pull, the actual electrical contact 
 being made by means of a lever and spring concealed in a 
 
Domestic Electricity for Amateurs. 
 
 31 
 
 box near the ceiling. The internal arrangements are very 
 various, and Fig. 19 shows some : A and C require a side 
 pull ; B, a centre pull. 
 
 Fig. 19. 
 
 A B c 
 
 Fig. 20. 
 
 A very ingenious arrangement by Charpentier is one in 
 which the contact acts, not only as an ordinary call, but in 
 case of fire rings the bell continuously. 
 
 To this end a very light and com- 
 bustible cord is fixed to the ring C, Fig. 
 
 20, holding a weight heavy enough to 
 lower the metallic ring D below the two 
 points A and B. Contact is made by 
 lifting the weight suspended from C, 
 when the spiral spring forces the ring D 
 back, and thus makes contact between 
 the two bent springs as shown in the 
 figure. The advantage of this arrange- 
 ment is that when the cord which holds 
 the weight burns, the weight falls, the 
 ring D then ascends and establishes a 
 continuous contact, and the bells give 
 the alarm. 
 
 In conclusion we may mention two 
 pedal arrangements for offices or dining 
 rooms, the action of which will be under- 
 stood from Fig. 21, and the door or 
 window contacts shown in Fig. 22 ; 
 these latter act automatically on a bell 
 when a door is opened or shut. 
 
 The rabbet contact (Fig. 22) breaks the contact when the 
 door is closed, and acts the whole time the door is open, 
 which is sometimes inconvenient, but can be remedied by 
 
32 Domestic Electricity for Amateurs, 
 
 introducing a switch into the circuit between the contact and 
 the bells or the battery. The other contact shown in the 
 figure only acts momentarily every time the door is opened or 
 shut. This arrangement is a contact by friction giving great 
 security. 
 
 Fig. 21. 
 
 These are the principal contacts employed in practice ; 
 their arrangement can be varied indefinitely according to the 
 purpose in view, but what we have said will suffice for most 
 cases with which the amateur is likely to meet. 
 
 Fig. 22. 
 
 Bells. — Trembling bells are generally used, of which Fig. 
 23 shows a very simple and cheap model. It is composed of 
 a square-shaped casting, which constitutes the body of the 
 system as it carries the bell, the electro-magnet, the counter- 
 spring, the armature, and the hammer. The interrupter, with 
 its regulating screw, is mounted on a piece of wood, on which 
 is fixed the box which protects the system from dust. The 
 bell is then secured to the wall by means of two hooks and 
 clasps. In the more elaborate, but more expensive arrange- 
 ments, the support of the regulating contact screw is placed 
 on the same metallic support as the magnet and the bell ; the 
 contact screw being fixed by a lock-nut. This arrangement 
 may be used with bells of all sizes* of from 2 to 12 inches 
 diameter. 
 
Domestic Electricity for Amateurs. 33 
 
 In order to distinguish the bells from each other, and to 
 suit the buyers’ tastes, they are made in the form of clock-bells, 
 gongs, or domes of bronze, lignum vitae, which has a peculiar 
 dull sound, or even of glass. 
 
 Fig. 23. 
 
 If indicators are not employed the bell is sometimes 
 furnished with an index which falls when the bell has acted, 
 thus indicating the call by a permanent signal when the person 
 to whom the call has been made is absent for a time. 
 
 The bell shown in Fig. 24 has been designed to act in all 
 positions, whether flat on a table, against a wall, or on a jolting 
 vehicle. The entire mechanism is arranged in a round case, 
 of which the hemispheric lid is the gong, thus making a very 
 portable apparatus, and neat in appearance. 
 
 The electro-magnet is placed at the bottom of the case 
 and acts on an armature fixed to a spring bent round into a 
 
 D 
 
34 
 
 Domestic Electricity for Amateurs, 
 
 semicircle. A small strip cut out of the spring acts as inter- 
 rupter, and a brass ball at the other end forms the hammer. 
 
 Fig. 24. 
 
 Fixing the Bells. — Fig. 25 is a diagram of the most 
 simple installation that can be imagined : a battery P, a con- 
 tact-button I,' and a bell S. 
 
 Fig. 25. 
 
 Fig. 26 shows the arrangement of a single battery supply- 
 ing several bells, acting separately by different buttons. 
 
 Fig. 27 represents a battery P, acting on a bell S, put 
 into motion by three different buttons, i, 2, 3. Where gas is 
 laid on in the apartment, the wire represented by the dotted 
 
Domestic Electricity for Amateurs. 
 
 35 
 
 line in the figure can easily be omitted ; it will do if the left 
 terminal of the bell S and the negative pole of the battery is 
 joined to the gas-pipe. By means of three wires and the one 
 
 Fig. 26. 
 
 battery it is possible to fix two buttons and two bells, so that 
 by pressing button i (Fig. 28) the bell Si alone rings, and 
 
 Fig. 27. 
 
 button 2 only rings the bell S2. The diagram will explain 
 the connections. 
 
 D 2 
 
36 Domestic Electricity for Amateurs. 
 
 In certain cases, where only one bell is at disposal, and 
 where it is necessary to make three distinct calls at A, B, 
 and C (Fig. 29), it is easy to use this single bell without an 
 
 Fig. 28. 
 
 
 indicator, in order to easily distinguish which is the button, 
 A, B, or C, which has called. 
 
 For this purpose it is sufficient to use an ordinary bell 
 (Fig. 30), and to add to it a third terminal 2 joined electrically 
 
37 
 
 Domestic Electricity for Amateurs. 
 
 to the support of the armature. The wires are arranged as 
 shown by Fig. 29, taking care to introduce a resistance R of 
 a convenient length between the terminal 3 of the bell and 
 the button C. Three different 
 and well-defined calls can thus 
 be made : — 
 
 1. By pressing on A, the 
 sound will be a trembling one of 
 ordinary power. 
 
 2. By pressing on B, the 
 armature will be attracted once, 
 and strikes once, and thus we 
 have a single-stroke arrange- 
 ment. 
 
 3. By pressing on C, a sound 
 is heard, weakened by the resist- 
 ance R, which it will be impos- 
 sible to confound with that of A. 
 
 It would be convenient to 
 make B the front-door bell, the 
 ordinary trembling one in the 
 drawing-room or bedroom, and 
 the weakened ring in the dining- 
 room, because, in the last case, when used, the person for 
 whom the call is intended would naturally always be near 
 the bell, and does not consequently require a loud call. 
 
 The expense of putting up an indicator-board for these 
 few calls is thus saved. 
 
 The three-terminal bell (Fig. 31), somewhat modified in its 
 arrangement, constitutes a continuous bell. Every time the 
 button is pressed, whatever be the duration of the contact, 
 the bell rings continuously until it is stopped by a switch, 
 which in many cases acts as a security and a check. 
 
 In order to understand the connections, it will be sufficient 
 to examine Fig. 31. Ordinarily, the switch T interposed 
 between the terminal i of the bell and the positive pole of 
 the battery closes the circuit there, but there being no con- 
 tact between the armature and the spring joined up to the 
 
38 
 
 Domestic Electricity for A mateurs. 
 
 terminal 3, the bell does not act. By pressing the contact B, 
 the current from the battery passes by 2 and i, the armature 
 is attracted and remains fast against the electro-magnet ; 
 when the pressure on the button is stopped, the armature 
 
 Fig. 31. 
 
 rebounds, owing to the elasticity of the spring to which it is 
 fixed, with such force that it goes beyond its original position, 
 the two points touch, when a current passes into the electro- 
 magnet by 3 and i, the armature is attracted, the contact 
 breaks, the armature recoils, re-establishes contact, is attracted 
 again, and so on until the circuit at T is for an instant inter- 
 rupted and the armature enabled to return to its original 
 position. 
 
 This plan is very useful in a country house where the 
 entrance-gate is some distance off, as servants will often let 
 a visitor ring without replying. With a continuous ringing, 
 however, when the precaution has been taken to place the 
 switch near the gate, it is necessary to go there to stop the 
 noise. 
 
 This arrangement may also be adapted to a letter-box; 
 every time the postman delivers letters he lifts the small 
 
Domestic Electricity for Amateurs, 
 
 39 
 
 oblong lid which closes the box ; this contact can be utilised 
 to make the bell ring continuously — until the servant comes 
 to collect the letters. 
 
 As the servants might purposely forget to re-establish the 
 contact at T, it is easy to compel them to do this by arranging 
 the contact in such a way that they will be obliged to break 
 it by opening the gate or the lid of the letter-box, and to 
 restore it by closing the door or the box. 
 
 It will be seen that the arrangements of electric bells may 
 be varied indefinitely, and do not give rise to any serious 
 difficulties if a little care and attention be taken in laying the 
 wires. 
 
 The above general directions apply equally well to indi- 
 cator-boards, which may be just as easily set up as simple 
 bells. 
 
40 
 
 Domestic Electricity for Amatetirs. 
 
 CHAPTER III. 
 
 AUTOMATIC ALARMS. 
 
 Together with bells and indicator arrangements we may 
 class the automatic alarms, which, as their name suggests, are 
 intended to indicate automatically and to warn those whom it 
 concerns of some phenomenon or accident. 
 
 Their number and arrangement may be varied indefinitely, 
 but we will here only describe a few examples, for electricity 
 presents a fruitful field to the hundreds of inventors who daily 
 devise some fresh arrangement. 
 
 Thermometrical Indicators. — If we have a platinum 
 rod sliding in the tube of a thermometer, the lower end of 
 which rod may be fixed at any desired degree, it will be 
 understood that if the temperature reaches this degree the 
 mercury comes into contact with the rod, and that this 
 metallic contact may be utilised to close a circuit to an alarm- 
 bell, gas-tap, or any other suitable apparatus. 
 
 Fire-alarms. — Many of the so-called fire-alarms are 
 made on the same principle as the thermometrical indicators, 
 some, however, have this advantage, that they act at the same 
 time as ordinary calls for domestic use, requiring no special 
 installation. 
 
 In order to transform ordinary bell-pushes into fire-alarms, 
 a small piece of fusible alloy is fixed to the lower spring so 
 as to keep it pressed down and out of contact with the upper 
 spring. Under these conditions it acts as an ordinary push, 
 but as soon as the bit of fusible alloy melts, at a tempera- 
 ture of about 37° C., the lower spring rises and thus makes 
 continuous contact with the upper spring, and the bell will 
 
Domestic Electricity for Amateurs. 41 
 
 ring continuously, giving warning that there is a temperature 
 of 37° C. in the neighbourhood of the push. 
 
 In Fig. 32, A is the upper spring. B the lower, which left 
 to itself would at once make contact with A. The plug of 
 fusible alloy is at C, and is held down on the spring by a 
 screw through B. In Fig. 33 the arrangement is nearly the 
 same. The lower spring is at B, the bit of fusible metal at C, 
 and the upper S-shaped spring A bends to the pull of the bell- 
 rope by means of a finger working in the hollow of the spring. 
 
 Fig. 32. Fig. 33. 
 
 When the cord is pulled, the finger presses on the convex part 
 of the spring, brings it down to the lower spring, and the con- 
 tact being produced, the bell rings. On the other hand, in 
 case of fire, the fusible metal disappears, the spring B makes 
 permanent contact with A, and gives warning of the increasing 
 temperature. 
 
 Forgeot’s Fire-alarms. — These are also based on the . 
 rise of temperature caused by fire at a given point. The 
 cylindrical rod of porcelain, ivory, or any other insulating 
 material, shown in Figs. 34 and 35, about f in. long by i in. 
 in diameter, has metallic hooks on top and bottom, A and B, 
 to which the wires from the battery are attached. If the two 
 hooks A and B are put into metallic communication, the circuit 
 is closed and the bell rings. 
 
 To effect this automatically in case of fire, a metallic 
 spring A is wound round the insulating rod, held at one end 
 by the hook B, and at the other by a small pin of fusible 
 
42 Domestic Electricity for Amateurs, 
 
 metal, inserted in a hole drilled through the rod, ^ inch from 
 the hook A. When the spring is held in this position the cir- 
 cuit is open, but as soon as the melting-point of the metal 
 (55°) is reached, the pin melts, the spring extends and touches 
 A, closing the circuit and ringing the bell. 
 
 Fig. 34. 
 
 1 i 
 
 The arrangement of apparatus to act as fire-alarms will now 
 be easily understood. When a series of these very small instru- 
 ments is fixed in any room, all joined to the battery and bell by 
 common wires, which, being covered with silk, maybe laid up 
 
 Fig. 35. 
 
 together to save space ; it is very certain that as soon as any 
 increase of temperature caused by the beginning of a fire is 
 felt on any part of the wire the bell immediately gives warn- 
 ing of the danger. 
 
 The melting-point of the pin is 55° C., but this may be 
 varied by modifying the composition of the fusible metal. A 
 high temperature may destroy the elasticity of the spring, but 
 electric contact would be established long before then. 
 
 An important point is to assure the actual contact between 
 the extreme ends of the spring and the receiving hooks of the 
 wire. These hooks and the spring itself are therefore gilt or 
 nickel plated, and thus prevented from oxidising. But the 
 contact may also be disturbed by dust or cobwebs, which will 
 
Domestic Electricity for Amateurs. 43 
 
 not fail to make their appearance between the extremity of 
 the spring fastened by the pin and the adjoining hook, unless 
 frequently and constantly cleaned. In order to avoid this 
 inconvenience each apparatus may be covered with very fine 
 goldbeater’s skin, secured in such a way 
 as not to interfere with the motion of the Fig. 36. 
 
 spring, as shown in Fig. 36. 
 
 This apparatus, by merely changing 
 the substance of which the pin is made 
 (by using soluble instead of fusible 
 material), gives a warning of leaks in cellars, holds of vessels, 
 &c. 
 
 All the foregoing apparatus are rather temperature alarms 
 than fire-alarms. If the regulation is not very exact, there is 
 the risk that in winter they will not act, or act too late, and 
 in summer give false alarms. An anonymous contributor 
 sent to ‘ L’Electricien,’ in January 1882, the description of an 
 alarm, the principle of which we let him explain : — 
 
 “ The most striking fact about a fire is the rapidity with 
 which it spreads ; every alarm should therefore be based upon 
 the rapidity of this increase of temperature during a fire, and 
 not on the increase of the temperature per se. 
 
 “Acting on this principle, I constructed the following 
 small apparatus : — 
 
 “This very simple and cheap apparatus is composed of 
 two distinct thermoscopic couples. They are two U-shaped 
 metallic strips, each consisting of a copper strip and a zinc 
 strip soldered together. Zinc and platinum are the most 
 sensitive plates, but platinum is dearer than copper, and it is 
 difficult to find a solder of which the coefficient of expansion 
 is the mean between 8 Zn and S Pt. 
 
 C Zinc 0*000029 
 
 Coefficient of expansion Brass ... o* 0000 18 
 
 I Platinum... 0*000008 
 
 “ One set of strips is thick, and the other exceedingly thin ; 
 in the apparatus used by me for my experiments, one of the 
 combined strips had a thickness of a fifth of a millimetre, and 
 
44 
 
 Domestic Electricity for Amateurs. 
 
 the other a millimetre and a half ; it is also deeper. They 
 are, however, the same in length, the two zincs being on the 
 inside. 
 
 “As soon as the temperature rises, the plates get heated and 
 expand ; by expanding unequally the two arms of the U tend 
 
 Fig. 37. 
 
 to separate ; but as one is fixed, the whole effort is extended 
 to the second arm, which opens out from the fixed point. But 
 the plate B, the bulk of which is smaller, absorbs the heat 
 more readily, so that if the increase is sudden and considerable, 
 as it always is at the beginning of a fire, it expands rapidly 
 and makes contact with A, which, being of greater mass, takes 
 longer to heat and expand. If, on the other hand, the air 
 becomes heated from ordinary causes, the rise in temperature 
 always being more gradual, the plate A has time to expand, 
 and the two contact points C C do not touch. These contacts 
 are made of bent silver or platinum strips, so that the contact 
 may take place in all positions of the plates. The advantages 
 of this instrument are its simplicity, sensitiveness, low price, 
 and automatic action for preventing false alarms.” 
 
 Another indicator recently proposed is based on the same 
 principle, but the two plates of unequal calorific capacity are 
 replaced by two glass vials filled with air, of which the one is 
 uncovered and the other covered with a material which is a 
 bad conductor of heat, as, for instance, white cloth or felt. 
 These two vials are joined by a horizontal glass tube con- 
 
Domestic Electricity for Amateurs, 45 
 
 taining mercury. If the rise in temperature is gradual, the 
 air expands in both vials equally, and the mercury remains 
 stationary ; if the rise of temperature be sudden, the air in 
 the uncovered vial becomes heated sooner and drives out the 
 mercury, which may then be used to close a bell circuit. 
 
 Breguet’s Desk and Safe Alarms. — The idea of 
 utilising the electric current to automatically give warning of 
 the improper opening of a room-door or safe is certainly 
 not new. 
 
 But if the systems are numerous very few are of much use, 
 and it is to be supposed that thieves, whether born to thieve 
 or having taken it up as a profession, know most of these con- 
 trivances and care very little for them. A wire properly cut 
 reduces the obnoxious bell to silence. 
 
 But by the Breguet alarm this last resource is denied to 
 the safe-pickers, the cut wire at once betrays their presence 
 by giving the alarm on the bell, and if the wire is not cut the 
 first movement of the door produces exactly the same effect. 
 Thanks to this new combination, the safe becomes an object 
 of forced respect, an idol which cannot be touched without 
 warning its guardian. 
 
 - ^ This is arrived at by making use of a continuous current, 
 and by utilising the opening of this circuit. An ordinary bell, 
 a continuous-current battery, an ordinary Leclanche battery, 
 and internal contacts which break as soon as the safe is 
 opened, are all that is required. The continuous-currrent 
 battery may be placed in the safe or any other suitable place, 
 and forms the electric source of a circuit completed by the 
 coils of the electro-magnet of the ordinary bell, the wires 
 which lead to the safe, and the contact or contacts the breaking 
 of which is to give the alarm. 
 
 The bell is also in circuit with the Leclanche battery in the 
 ordinary way, but with no break in the circuit. The con- 
 tinuous current which circulates in the magnet of the bell, 
 maintains the armature and the hammer close against this 
 magnet, and in consequence keeps the circuit of the Le- 
 clanche battery open while the spring of the trembler and its 
 screw are not in contact. But if from any cause whatever the 
 
46 
 
 Domestic Electricity for A mateurs. 
 
 other circuit becomes broken, the armature flies back, makes 
 contact with the trembler, and the bell rings loudly until the 
 continuous circuit is re-established. 
 
 There is nothing to prevent a multiplication of the bells by 
 placing them at several points. It is only necessary to break 
 the continuous circuit at any point to make all the bells on 
 this circuit ring at once. 
 
 This use of the continuous circuit also enables warning to 
 be given at any moment if the system is not in proper working 
 order, for if by negligence the continuous battery is allowed 
 to run down the tingling of the bell at once gives the alarm. 
 
 This continuous battery acts for a long time without having 
 anything done to it, as the current required is insignificant, it 
 being in fact only necessary to keep an armature in contact 
 with its magnet, and a very small current will do this. 
 
 Thanks to this system, honest folk are protected against 
 thieves, and we do not believe that the latter have a sufficiently 
 profound knowledge of electricity to get round this combination. 
 
 In New York, however, safes with electric bells are out of 
 date. We read in the / Chronometrical Review,’ that a 
 German has invented a safe which not only rings a bell as 
 soon as touched, but throws out a powerful beam of electric 
 light, by means of which a photographic apparatus instanta- 
 neously takes the features of the thieves. (See the American 
 papers !) 
 
 Fig. 38 shows a device for making contact when shaken, 
 which was designed by Morse for railway purposes. This 
 
 Fig. 38. 
 
 small apparatus may be fixed against the door to be protected, 
 as the slightest shake disturbs the mercury in C, which thus 
 makes contact with B, closing the circuit of a battery and bell. 
 
Domestic Electricity for Amateurs, 47 
 
 The screw D is to regulate the level of the mercury and 
 render the apparatus more or less sensitive. 
 
 Abdank- Abakanowicz’ s Magneto-electric Call.— 
 In many cases it is an advantage to dispense with batteries 
 for ringing the bells, and to replace them by a magneto- 
 electric system, in which the work necessary to give the 
 signal is performed by the muscular energy of the operator. 
 For example, in a telephone system where only magneto 
 transmitters are used, the installation is much simplified by 
 the use of magneto apparatus to work the call-bell. 
 
 In long distance telephoning it requires a number of cells 
 to work the calls, which number increases in proportion to the 
 distance, while a magneto call of a uniform price acts at any 
 distance ; it is therefore economical to use it above certain 
 distances, even with a microphone transmitter, because the 
 number of elements necessary for the latter is almost con- 
 stant. 
 
 Fig. 39 represents the transmitter and the receiving- 
 bell. The transmitter is formed of a U-shaped magnet 
 between the poles of which works a coil with an iron core, 
 and fixed at the end of a spring the other end of which is 
 strongly fixed. The coil is moved from its position of equili- 
 brium between the poles of the U-shaped magnet by pushing 
 a button fixed to the lower part of the coil and then letting 
 go. Under the action of the spring the coil oscillates rapidly, 
 like a pendulum, between the poles of the magnet, and 
 the wire of which it is composed is traversed by a series of 
 alternately undulatory currents ; these currents last some 
 seconds, until the coil returns to its original position. 
 
 These undulatory currents thus produced arrive at 
 the receiver, made of a second coil rolled on a sheet of thin 
 iron plate in the form of a double T, and moving in a magnetic 
 field constituted by two permanent magnets. This double 
 T carrying the coil is fixed on a spring which enables its 
 vibrations to be regulated, and renders them synchronous 
 with those of the transmitter, which increases the sensitive- 
 ness of the apparatus. The other end is furnished with a 
 small brass ball which strikes the two clock-bells alternately 
 
48 
 
 Domestic Electricity for A mateurs. 
 
 when the coil is traversed by the undulatory currents coming 
 from the transmitter. 
 
 The call thus constituted is very simple to manage, it acts 
 in all positions and requires no keeping up. All that is 
 
 Fig. 39. 
 
 necessary is to fix the transmitter securely on a table or 
 against a wall, and to couple it up to the receiver. To 
 work it, the handle is pushed from its position until it nearly 
 touches the stop on the other side, and is then let go. The 
 undulatory currents produced by this system have the 
 great advantage of not causing any induction noises on the 
 neighbouring lines, owing to their nature and their periods 
 of vibration, which exceed of a second, the lowest limit of 
 perceptible sounds. This is a valuable quality which recom- 
 mends its use for telephone purposes. 
 
Domestic Electricity for Amateurs, 
 
 49 
 
 CHAPTER IV. 
 
 DOMESTIC TELEPHONES. 
 
 Although a recent invention, the telephone has made greater 
 strides than perhaps any other discovery, and there is no 
 knowing what future may not be in store for it. A regular 
 network of telephone wires already covers every large city, 
 and recent discoveries, which appear to promise that tele- 
 phones and telegraphs may be simultaneously worked by one 
 and the same wire, will make its use even more universal. 
 
 We propose to study the telephone in a somewhat more 
 modest sphere by considering it as a useful and valuable 
 adjunct to the other domestic electric apparatus which we 
 have already examined. 
 
 We will, as usual, proceed from the simple to the compli- 
 cated, and we first of all suppose that communication between 
 two points in a house, office or factory, is to be made. 
 
 The first question is the choice of a system. We would 
 advise the use of magneto telephones of the Graham Bell type 
 if the distance is not very great, say, for instance, lOO yards 
 or so. Simplicity, economy, and easy installation are com- 
 bined here. Battery telephones certainly give better results, 
 but they are dearer and require greater care and supervision. 
 
 The sounds produced by magneto telephones are small, it 
 is therefore necessary to call attention by means of a bell. 
 
 One of the most simple installations of a bell and a tele- 
 phone possible, is to use an ordinary bell-push with one 
 insulated wire and an earth return, the same circuit being 
 used for the Bell telephone. In such cases the magneto call 
 is very useful. 
 
 In most cases it is necessary that each station shall be 
 
 E 
 
50 Domestic Electricity for Amateurs. 
 
 able to call the other ; a complete telephonic communication 
 between two stations includes, therefore, at each station a tele- 
 phone transmitter, which can act as receiver, or better, a pair 
 of telephones, a call-button, a call-bell, and a battery. All 
 these may be arranged in different ways, each presenting its 
 special advantages and disadvantages ; the choice to be made 
 between the different arrangements depends upon the special 
 requirements of the proposed installations. 
 
 If the telephone is to be available to anybody, which is 
 generally the case, it is absolutely necessary to do without 
 every commutator or switch which may be forgotten to be 
 replaced, and to do this a sufficient number of wires must be 
 used, four at the most, or three, taking the gas- and water- 
 pipes as return wires ; the call-button and telephone are 
 sufficient to establish complete communication without the 
 possibility of error. See Fig. 40. 
 
 Fig. 40. 
 
 On examining the diagram it is easy to follow the inter- 
 communications of the various apparatus with each other — 
 presses, bells, telephones, battery, and wires. 
 
 To avoid error it is advisable to attach first of all the four 
 wires to four numbered terminals on a board fixed at each 
 station, and then to join up the two sets of terminals. The 
 
Domestic Electricity for A mateurs, 5 i 
 
 terminal and wire No. 4 may be replaced by water- or gas- 
 pipes. The diagram of Fig. 40 shows all the apparatus close 
 together, to enable the connections to be easily traced out. 
 In practice, however, they are placed wherever possible, by 
 adapting the buttons, bells, and telephones to suit the circum- 
 stances. 
 
 To make a nice appearance all the apparatus should be 
 fixed symmetrically on an oak or mahogany board. 
 
 In other countries pairs of complete telephone stations 
 may be bought all ready, with telephone, bell, battery, &c., 
 and it is only necessary to screw the board up to the wall, lay 
 the wires, and couple up to the marked terminals ; but in 
 England, owing to the monopoly of the United Telephone 
 Company, no one may make or use a telephone without a 
 licence from them. 
 
 Telephone conductors placed inside a house may be of the 
 same nature and size as ordinary bell-wires, but it is convenient 
 to distinguish them by choosing different colours. Or the 
 wires, two, three, or four in number, may be run in lead or 
 compo pipes, fastened by hooks and staples, exactly the same 
 as gas-pipes. 
 
 When the telephone stations to be joined are some dis- 
 tance apart, without an intermediate building, recourse must 
 be had to an aerial line on telegraph posts, 18 or 20 feet high, 
 of pine, fir or larch, impregnated with sulphate of copper or 
 creosote to make them last. 
 
 The wires should be galvanised iron or steel, from two to 
 six millimetres diameter, according to the distance, or of 
 silicium-bronze, eight-tenths to one millimetre in diameter. 
 The silicium bronze wires allow of longer spans owing to their 
 smaller weight ; the longest span of iron wire is from 80 to 
 100 yards, while 250 yards may be spanned with silicium 
 bronze wires. Bare conductors must be fixed to the posts, or 
 the buildings to which they are attached, by means of porcelain 
 insulators, of which Fig. 41 shows some shapes, but many other 
 patterns are used in this country. 
 
 Magneto telephones may be suitable for short distances 
 and quiet localities, where the conversation is not troubled by 
 
 E 2 
 
52 
 
 Domestic Electricity for A mateurs. 
 
 outside noises, but in manufactories, workshops, &c., microphone 
 transmitters with batteries must be used. 
 
 For telephone purposes the Leclanche is the battery most 
 used. It must not be forgotten, however, that they polarise 
 
 Fig. 41. 
 
 when kept continuously on closed circuits, therefore it is neces- 
 sary to break the connection as soon as the conversation is 
 finished. The Lalande and Chaperon battery, as well as 
 accumulators, have been used with good results. 
 
 The transmitters vary indefinitely in form and arrangement. 
 
 We cannot here describe all the known variations capable 
 of giving good results, many of which cost a good deal more 
 than they are worth. Any one may make a very serviceable 
 microphone with a few carbon pencils, like those used for arc 
 lamps. Such is the microphone of Professor Hughes, who 
 
Domestic Electricity for Amateurs. 53 
 
 invented this instrument, and gave it to the world without any 
 patent. See Fig. 42. 
 
 It consists of a small pointed carbon pencil A, held tightly 
 in a vertical position, between two blocks of carbon C C, fixed 
 
 Fig. 42. 
 
 against a thin sounding-board on a solid base D. These 
 blocks C C are joined to the battery and to the line wire 
 which leads to the telephone. This instrument, even in a 
 rough model, is of an amazing and marvellous delicacy. It 
 has wonderful sensitiveness, almost too much, as it has 
 to be diminished to destroy the crashing sounds produced by 
 too intense noises. 
 
 This is done by several means ; sometimes the board which 
 supports the carbon blocks is inclined until it is perfectly 
 horizontal or slightly inclined like a desk ; sometimes a small 
 piece of paper folded into the shape of a V is placed between 
 the board and the carbon pencil, the elasticity of the paper is 
 
54 Domestic Electricity for Amatetirs. 
 
 sufficient to diminish the too great mobility of the carbon, and 
 to eliminate almost entirely the crashing sounds. 
 
 Fig. 43 shows a very simple arrangement of the micro- 
 phone, which will give good results, and is of so easy a con- 
 
 Fig. 43. 
 
 A 
 
 struction that only a few minutes are required to make one if 
 the materials are to hand. The sounding-board A is made 
 simply out of a visiting-card cut square, and of medium thick- 
 ness. On this card three small light plates B B B' of carbon, as 
 used for electric lighting, are fastened by means of sealing- 
 wax. These three plates occupy the three angles of an equi- 
 lateral triangle ; they are put into communication by means of 
 copper wires b b b. 
 
 For this purpose a small hole is made in each, when the 
 end of a copper wire is fixed to it, and the three small copper 
 wires are joined together. 
 
 The rest of the apparatus consists of a board M, holding 
 the three carbon rods C C C' corresponding exactly to the 
 three plates B B B'. Two columns C C communicate by the 
 copper wires d d with a terminal D. The third column C is 
 connected to a second terminal D'. The upper ends of the 
 
Domestic Electricity for Amateurs, 
 
 55 
 
 carbon sticks should be bevelled, as pointed ends do not give 
 such good results, and the other ends of the carbons must be 
 fixed to the base board with wax. 
 
 This little instrument may be made very sensitive to the 
 voice and all other sounds, provided a suitable weight, neither 
 too heavy nor too light, be placed on the card A. A person 
 speaking in his usual voice at the end of the room in which 
 the microphone is, may be heard distinctly, and the voice and 
 tone of the speaker easily recognised. Piano sounds are par- 
 ticularly well heard. It is necessary to place the apparatus on 
 a table two or three yards away in order that the mechanical 
 vibrations may not affect it. 
 
 A Leclanche battery of two or three cells is required with 
 this microphone. 
 
 In the Locht-Labye transmitter, to which the inventor has 
 given the somewhat pretentious name of Pantelephone, the 
 contact of variable resistance is formed between a fixed piece 
 of platinum and a small carbon lozenge attached to a plate of 
 cork suspended by two springs on the upper part ; the cork 
 plate offering little inertia, and having a great surface, follows 
 the voice well. 
 
 A very simple transmitter, easy of construction, is that of 
 d’Argy, and it may be made of materials ready to hand. 
 
 Take a board of walnut, deal, ebony, or a Japanese hand- 
 screen, fix it vertically to a base by means of two corks. In 
 the middle of this board, two pieces of carbon are fixed, 
 between which a pinch of coke is placed, held by means of a 
 piece of indiarubber tube or the nipple of a feeding-bottle. 
 The vibrations of the board react on the variable contact 
 resistance formed by the powdered coke. 
 
 Practically, good results are obtained by multiplying the 
 contacts and by arranging them either in tension or quantity. 
 In the Ader transmitter there are ten carbons, which give 
 twenty contacts, four in tension, and five parallels. Crossley’s 
 transmitter holds four carbons, eight contacts, four in tension 
 and two in quantity ; the Gower Bell, six carbons, twelve 
 contacts, three in quantity, four in tension, &c. In all these 
 instruments it is necessary, in order to obtain good results, to 
 
56 
 
 Domestic Electricity for A mateurs. 
 
 proportion the number of elements to the number of contacts 
 and to their arrangement : if the contacts are in series the cells 
 should be in series ; if they are in quantity, the cells should 
 be arranged in quantity. The rule to be followed is, that the 
 internal resistance of the battery should be as near as possible 
 equal to the mean resistance of the transmitter. 
 
 Ader’s Transmitter. — This transmitter, mostly used in 
 France, Fig. 44, is made of ten small carbons A A, arranged 
 
 Fig. 44. 
 
 two in series and five parallel, supported at their ends by three 
 cross-pieces of carbon BCD fixed on a light pine-board, 
 which receives the vibrations and at the same time serves as 
 a cover for the apparatus. For ordinary use it is fixed 
 directly to a board ; for theatrical purposes it is fixed to a 
 leaden base, supported by four indiarubber feet, which shield 
 it from the shaking of the stage. 
 
 Dunand’s Microphone. — This microphone transmitter 
 in which the contacts are protected from air and dust, seems 
 to possess some advantages. It is made of two metallic plates 
 
Domestic Electricity for Amateurs. 57 
 
 A A, Fig. 45, fixed on a wooden ring, making an air-tight case 
 protecting the microphonic system against air and dust, which • 
 in ordinary microphones sometimes interferes with the con- 
 tacts. Each of these plates has a small carbon lozenge B B 
 fixed in the centre. Between these 
 two carbon lozenges is a small egg- 
 shaped piece of carbon, of a some- 
 what greater length than the distance 
 between the inside faces of the car- 
 bon lozenges. This is held in the 
 middle by a brass wire F, stretched 
 diametrically, one end of which is 
 fixed and the other end joined to a 
 button E. By twisting the wire more 
 or less the egg-shaped carbon is 
 pressed with varying force against 
 the two lozenges, and the microphone 
 becomes proportionately sensitive. An 
 index fixed to the button E makes it 
 easy to regulate the twist of the wire 
 in order to proportion the sensitive- 
 ness of the instrument to the nature 
 transmitted. The variations of resistance are produced by 
 speaking before one of the plates ; two persons, one speaking 
 into A and the other into A', may even transmit a duet, which 
 the receiving apparatus reproduces clearly and distinctly. 
 
 A transmitter may act upon a telephone receiver in two 
 distinct ways : — 
 
 1. Directly, without the intermediary of an induction coil. 
 
 2. Indirectly, by means of an induction coil. 
 
 The first system can only be used with very short distances, 
 as for example from one room to the next, and using a tele- 
 phone wound with comparatively thick wire. It will, in fact, 
 be understood that, as the distance increases, the total resis- 
 tance of the circuit, constituted by the battery, the transmitter, 
 the receiver, and the wire, increases also, while the variations of 
 the resistance of the transmitter always retain their absolute 
 value. The effect of these variations will therefore be less 
 
 Fig. 45. 
 
 of the sounds to be 
 
5 8 Domestic Electricity for A mateurs. 
 
 as the distance increases, and finally becomes insufficient to 
 make the sounds perceptible. 
 
 This, however, is not the case if induction currents are 
 made use of. 
 
 The transmitter works on a circuit of fixed resistance, con- 
 sisting of its own resistance, the resistance of the battery, and 
 that of the primary circuit of the induction coil, while the 
 receiver and the line wire are in circuit with the secondary 
 coil. The length of the line wire, in this case, only indirectly 
 affects the instruments, and by proportioning the wire on the 
 induction coil and telephone to the length of the line wire, 
 the requisite regulation and sensitiveness may be obtained, 
 always remembering that the longer the line, the finer and 
 longer must be the wire of the coils. Most of the telephone 
 stations erected at present are furnished with induction coils, 
 and act easily up to ten or twelve miles and over. 
 
 Telephone Stations. — For domestic or private telephones 
 the two stations are generally joined to each other per- 
 manently, as for example between an office and a workshop, 
 a manufactory and the house of the manager, a country house 
 and the lodge-keeper, &c., &c. 
 
 As battery telephones are intended above all to satisfy the 
 requirements of a somewhat long line, it is impossible to use 
 a great number of wires, two at the most are used, and often 
 only one, the earth acting as return. 
 
 Under these circumstances a commutator is necessary, in 
 order that when no message is being sent, and the instrument 
 is not in use, the line wire is connected to the bell, that when a 
 call is made the battery at the station making the call is con- 
 nected to the line, and that when the call has been answered 
 and conversation is being carried on the telephones are in 
 :onnection through the line and battery. 
 
 In the early days of telephones all these various connec- 
 tions were made and broken by switches worked by hand, but 
 at present automatic commutators are almost invariably used. 
 
 All existing stations are so arranged that the telephone 
 when not in use is hung on a hook, which is in reality a lever 
 switch controlled by a spring. When a conversation is ended 
 
Domestic Electricity for A mateurs. 
 
 59 
 
 the speaker returns the telephone to the hook, and its weight 
 pulls it down half an inch or so, thus breaking contact with 
 the telephone and putting the bell in circuit. 
 
 Each station includes ; — 
 
 1. A battery of some Leclanche cells, which serve both for 
 the call-bell and the transmitter. 
 
 2. A call-bell. 
 
 3. A call-button. 
 
 4. A transmitter for speaking into. 
 
 5 An induction coil, generally placed out of sight in the 
 case of the apparatus. 
 
 6. One or two magnetic telephone receivers. 
 
 Dunand’s Telephone — Fig. 46. Everything is system- 
 atically arranged on a board from which go four wires, two to 
 battery and two to line ; the Dunand microphone is fixed on 
 
 Fig. 46. 
 
 the bell-case itself, the button is below, and the receivers are 
 two Bell telephones, the right-hand one producing the auto- 
 matic commutation. 
 
6o Domestic Electricity for Amateurs. 
 
 Crossley’s Telephone — Fig. 47. Here the call-button 
 is in front of the case which holds the entire system, the bell 
 N on the left, the hook commutator C on the right, and the 
 
 Fig. 47. 
 
 mouthpiece on the upper part. At A, Fig. 47, will be seen the 
 carbon lozenges arranged in two parallels each with four 
 contacts in series. 
 
 Ader’s Portable Telephone. — In this pattern, shown 
 in Fig. 48, the foot carries the call-button, the transmitter in 
 the form of a desk, and the two Ader receivers. Flexible 
 wires connect the instrument with the battery, the bell fixed 
 
Domestic Electricity for Amatenrs. 6i 
 
 elsewhere in the room, and the line wire, thus enabling the 
 transmitting and receiving apparatus to be moved about to a 
 certain extent. 
 
 Fig. 48. 
 
 Bert and D’ Arson vaFs Telephone. — In this arrange- 
 ment the carbon pencils of the transmitter are surrounded by 
 a small sheet of tin ; a magnet acting on these sheets pro- 
 duces thus a magnetic regulator, enabling the transmitter to 
 be used in any position. With this magnetic regulator a 
 transmitter may be held in the hand while the other parts of 
 the apparatus are in a small case, hung on a wall. 
 
 Simplified Telephones. — Under this name the General 
 Telephone Company (French) constructs small telephones 
 intended specially for private use, and of a price within an 
 amateur’s reach. Fig. 49 represents one of these telephones. 
 The greater part of the vibrating board, forming the top of 
 the desk, is shown broken away, in order that the internal 
 arrangement may be seen. The transmitter is a m.icrophone 
 on Ader’s system of ten carbons : the induction coil and the 
 automatic commutator are arranged underneath, in the body 
 of the desk ; the call-button is in front, where the lock of an 
 ordinary desk would be. All the connections are therefore 
 
62 
 
 Domestic Electricity for Amateurs. 
 
 inside, and the erection of the telephone is very simple ; it 
 requires eight connections to be made, and these are clearly 
 indicated : two go to the line wire L, two to the local bell S, 
 
 Fig. 49, 
 
 two to the local battery of the telephone, and two to the 
 call-bell under the desk. 
 
 The handling and the action of the simplified telephone are 
 identical with those of an ordinary telephone. When the right- 
 hand receiver is hooked up, the telephone is out of action, 
 ready for a call ; when it is taken in the hand, the switch lever 
 rises and closes the circuit on the telephone. 
 
 Figs. 50 and 5 1 show in section and elevation a telephone, 
 the novelty of which consists in the magnet, made of a steel 
 ring, having two screw threads and two internal soft iron pole- 
 pieces, on which two flat coils are fixed, coupled in series 
 
Domestic Electricity for Amateurs. 63 
 
 and joined to the line wire by means of a flexible cord. The 
 round magnet has its two poles diametrically opposite, and the 
 magnetic distribution is the same as in Duchemin’s circular 
 compass. On the lower thread a lid is screwed with a ring, 
 
 Fig. 50. 
 
 Fig 51. 
 
 by which the telephone is hooked up when not in use ; the 
 upper thread takes the cover, mouthpiece, and the vibrating 
 diaphragm. The distance of the plate from the poles is; 
 regulated by inserting brass washers of suitable thickness, 
 
64 
 
 Domestic Electricity for Amateurs. 
 
 The telephone so constructed forms a compact whole, rigid, 
 and not easily put out of order. 
 
 Erection of Telephone Stations. — Fig. 52 shows the 
 coupling up and connections necessary for two complete 
 
 Fra 52. 
 
 telephone stations, batteries, transmitters, receivers, and bells. 
 The number of elements necessary to work the bells varies 
 with the distance, while that of the elements required for 
 the microphone system varies very little with this distance, 
 generally three Leclanche cells in series. 
 
 Milde’s Telephone Station — Without contradiction, 
 simplicity, elegance, and cheapness, for small telephone 
 stations, are combined in the apparatus shown in Fig. 53. 
 The whole apparatus is movable, and comprises the trans- 
 mitter — a D’Argy microphone, a round Bell receiver, call-bell, 
 button, and automatic commutator. The battery — one 
 Leclanche cell for each station — is fixed, and may be hung 
 against a wall, or hidden in a corner of the room. In the 
 most recent pattern it is hidden in an elegant bracket, used to 
 stand the apparatus on. In the ordinary position, or when at 
 rest, the apparatus stands on a table or bracket. A button B 
 fixed underneath. Fig. 53, is thus lifted, and puts the bell in 
 circuit. Pressing the button A, the right-hand station calls 
 
Domestic Electricity for Amateurs, 65 
 
 up the left-hand station, which in its turn calls up the right- 
 hand station. The two interlocutors have then to take the 
 apparatus by the handle, and by putting it to the ear auto- 
 matically put the telephones in circuit. 
 
 Fig. 53. 
 
 The instrument is so made that when the receiver is put 
 to the ear, the rectangular board of the transmitter comes 
 near the mouth, on the side, and a little obliquely. When the 
 conversation is finished, and the apparatus replaced on the 
 table, communication with the bell is again established. 
 
 The whole thing is compact and light ; the two stations 
 and their batteries, with 60 yards of wire, are enclosed in a 
 neat box, and make a charming present to give to young 
 amateur students of electricity. 
 
 Telephone Elbow-rests. — In many of the combina- 
 tions of private or central telephone stations, the caller 
 has to hold the receiver to his ear, waiting for the reply. The 
 annoyance of waiting, and the fatigue of the position, make 
 the time often seem longer than it really is. 
 
 F 
 
66 
 
 Domestic Electricity for A matetirs. 
 
 Lhoste’s Elbow-rest, the use of which will be readily 
 understood by looking at Fig. 54, reduces the fatigue, and 
 
 Fig. 54. 
 
 patience may be more easily exercised. By means of a metal 
 arc and a catch, the height can be easily regulated to that of 
 the speaker. 
 
Domestic Electricity for Amatetirs. 
 
 67 
 
 CHAPTER V. 
 
 ELECTRIC CLOCKS. 
 
 The uses to which electricity may be put, for the indication 
 and measurement of time, are of various kinds. 
 
 Sometimes it may be used to transmit at regular intervals 
 a signal or mechanical action to regulate and set the time of a 
 clock or a series of clocks, each working independently in the 
 ordinary way. 
 
 Sometimes it is itself the motor, which from a distributing 
 centre works a number of dials situated at a distance. 
 
 Finally, it is sometimes the motor of the clock itself, where 
 it replaces the spring or weights required to be wound up 
 daily, weekly, or fortnightly. 
 
 In order to get rid of this necessity a system has been 
 sought for capable of acting indefinitely while the battery 
 lasts, and the patented variations and adaptations are almost 
 without number. 
 
 Electric Butterfly Clock. — A battery capable of supply- 
 ing a given quantity of energy, dependent upon the volume of 
 liquid, its composition, the thickness of the zinc, &c., would 
 very soon be exhausted if it had to furnish a current to give 
 an impetus to each tick of the pendulum. But experience 
 shows that this impetus is only required now and then. 
 
 In the clock shown in Fig. 55, Lemoine only gives this 
 impetus at the moment when it is necessary in consequence 
 of the decrease of the amplitude of the oscillation of the pen- 
 dulum ; a considerable saving of the battery is thus effected, 
 which therefore lasts longer, while waste of electric energy is 
 avoided. 
 
 This clock has an ordinary train of wheels worked by the 
 
 F 2 
 
68 Domestic Electricity for Amaterirs. 
 
 pendulum, which in this instance is the motor, having on its 
 upper part a clutch or pawl acting on a ratchet on the axis of 
 the first motion. Let us suppose the pendulum to be moved 
 by hand. Owing to the resistance of the air and the work 
 
 Fig. 55. 
 
 done by turning the clockwork, its amplitude of oscillation 
 decreases gradually and will soon be stopped if the motion be 
 not kept up. The pendulum, the lower part of which is a 
 cylindrical iron disc, has a small rod. Fig. 56, which moves 
 very freely round a horizontal axis, and to which is fixed a 
 
Domestic Electricity for Amateurs , 69 
 
 thin piece of mica or paper cut in the shape of a butterfly, 
 which gives the system its name. 
 
 During the motion of the pendulum, the resistance of the 
 air makes the properly regulated rod take a more or less in- 
 clined position. When the speed and ♦therefore the amplitude 
 
 Fig. 56. 
 
 of the motion of the pendulum is sufficient, the extremity of 
 the rod glides without depressing it over a very flexible con- 
 tact spring on the base of the clock. When the amplitude 
 decreases, the rod becomes more vertical, it then meets the 
 contact, depresses it, and sends a current into the magnet 
 placed on the left of Fig. 55. This latter attracts the pendu- 
 lum and gives it an impetus, thereby recovering the amplitude 
 of oscillation. 
 
 The pendulum then makes 6, 8, 10 or 12 oscillations with- 
 out making contact again, and consequently without expendi- 
 ture. By this ingenious arrangement the clock is kept going 
 automatically at the required speed, by means of a fresh 
 impetus given to the pendulum every time the speed of the 
 oscillation has arrived at its lowest point. 
 
70 
 
 Domestic Electricity for Amateurs, 
 
 It is very curious and amusing to watch the working of 
 this arrangement. With it a separate battery may be used, or 
 the battery may be placed in the stand. 
 
 Schweizer’s Electric Winding-up Arrangement. — 
 With the view of reducing the frequency of a closed circuit on 
 the battery, and to use to the utmost the disposable work 
 every time it is closed, an electric winding-up arrangement 
 has been devised by Schweizer. The battery circuit is closed 
 every time it is necessary to maintain at an equal tension a 
 spiral spring which transmits the motion to the clockwork. 
 The motive force is therefore entirely independent of the 
 current and the electricity has only to wind up a spring at 
 regular intervals. It consists, Fig. 57, of a wheel A, mounted 
 
 Fig. 57. 
 
 on the axis of the dial and moving the hour and minute hands 
 B. A second wheel C, placed above the first, transmits the 
 motion of the wheel A to the escapement. A spring D, fixed 
 on one side of the shaft of the minute wheel, the other end 
 being pressed against a pin in the ratchet wheel E, on the 
 shafts of the minute wheel, conveys the motion. 
 
 Pressure on the end of the spring, in the direction of the 
 
Domestic Electricity for Amateurs, 71 
 
 motion of the hand, puts the wheels in motion. This motion 
 is transmitted by the pin on the ratchet wheel, driven in its 
 turn by a weight P, Fig. 58, on the extremity of the lever L, 
 by means of a pivoted pawl C. The fall of the weight P is 
 very limited, and it is necessary to relift it whenever it gets 
 near the end. The electricity does this automatically by 
 means of a beam B, Fig. 58, on which is pivoted the lever L. 
 On one end of this beam is a soft iron armature over an 
 electro-magnet, and on the other a regulating screw. The 
 
 Fig. 58. 
 
 magnet is worked by a battery of two Leclanche cells. When 
 the current passes, the weight P is lifted up without affecting 
 the ratchet wheel, which is then held by the pawl C. This 
 movement does not therefore affect the action of the apparatus, 
 however suddenly the magnet pulls home its armature. When 
 the current stops, the weight begins to fall again, turns the 
 ratchet several teeth by means of the lever C, and gives to the 
 spring its required tension. 
 
 The circuit is closed only for a very short time, which 
 insures a long duration of the battery, and the motion of the 
 beam being independent of that of the lever, it returns to its 
 original position without hindering its motion. 
 
72 
 
 Domestic Electricity for Amateurs, 
 
 The lever and weight are very quickly lifted by the 
 current, which once effected, it can do no more useful work, 
 and therefore to save the battery the circuit should only be 
 closed an instant every time the lifting of the weight is 
 necessary, that is to say that the contact should in some way 
 be momentary. 
 
 This is effected by means of the disc D, joined to the 
 lever L, Fig. 58, by a connecting rod which moves it on its 
 axis in one way or the other according to the motion of the 
 lever L which governs it 
 
 Fig. 59 represents the two positions of interruption and 
 contact of the disc commutator governed by the rod. 
 
 The sketch on the left shows the circuit broken. As 
 soon as the weight falls, the disc turns slowly as shown by 
 the arrow until the moment when the screw T on this disc 
 presses the spring R, the contact spring drops, touches the 
 flat side of the disc, and closes the circuit. By the action of 
 the magnet the lever rises, the disc returns in the reverse 
 way, and the pir 3 pushes back the spring R and then 
 takes up its original position again, thereby breaking the 
 circuit. 
 
 Leclanche has modified the dry contact by substituting 
 a mercury contact. 
 
 The disc D, governed by the connecting rod of the lever 
 
 Fig. 59. 
 
 1 nterruption 
 
 Contact 
 
Domestic Electricity for Amateurs, 73 
 
 L, as in Schweizer’s commutator, has a collar to take a 
 small glass tube in which are several swellings. 
 
 The two ends of the tube form a reservoir, the slender 
 parts A, B, C, Fig. 60, are traversed by platinum wires 
 soldered in. The tube filled with hydrogen is also closed 
 up with a blow-pipe after a small quantity of mercury is 
 introduced. The wire A on the one side, and B and C on 
 the other, close the circuit. The two wires at B and C, 
 joined together, are a precaution in case during the displace- 
 ment of the mercury one of them should fail. 
 
 Fi&. 60. 
 
 After what we have said about the dry contact, the 
 mercury commutator will be easily understood and it will be 
 seen that in no case can the circuit be closed continuously. 
 
 Employment of bells for striking the hours.— 
 If it be desired to transmit the time, and to repeat it on 
 clock-bells or house-bells, the following very simple arrange- 
 ment has been devised by Lange, watchmaker of Beziers. 
 
 We use a simple clock, no matter of what construction 
 as long as it strikes. We take the negative wire of a bell- 
 battery, and fix it to a metallic part of the works. The 
 positive, properly insulated from the other parts of the clock, 
 is placed a little above the rod of the hammer. When the 
 clock itself strikes, the hammer rises, the rod touches the 
 positive wire, and the contact is made. 
 
 At the same instant, all the bells in the circuit strike the 
 same hour as the clock. 
 
 This experiment has been successfully tried, using a 
 single agglomerated Leclanche cell. By enlarging this 
 application the time may be given to all the rooms of a house. 
 
 It is easy to apply the system to church or public 
 clocks. 
 
74 Domestic Electricity for Amateurs. 
 
 Another adaptation is to cause a clock to strike at will, 
 by simply pressing a button. This button forms the circuit 
 of a Leclanche battery on a magnet which unlocks the 
 striking gear. 
 
 If it is desired to know the time at night, one has only to 
 press a button fixed at the head of the bed. 
 
 AlarxM Clocks. 
 
 Nothing is simpler than to transform an ordinary clock 
 into an electric alarm, and the following is an example : — 
 
 One of the wires is joined to any metallic part of the 
 clock, while the other is joined to a small support made of 
 a vertical rod over which a spiral copper wire can be slipped 
 bent towards the middle to a right angle, in such a way as 
 to form a horizontal arm on which another rod can turn, 
 having a hook at the end ; this simple arrangement being 
 completed, any necessary position can be given to it, so as 
 to place it against the dial of the clock where desired, so 
 that the large hand passes freely above the hook, while it 
 bars the way of the small hand in such a way that when the 
 latter comes to the spot where the hook is placed, it meets 
 it, thus making contact and ringing the bell ; if this little 
 apparatus be lightly made it can in no way disturb the 
 regularity of the clock, especially if one takes care to get 
 up to remove it. 
 
 It is not, however, necessary to attach one of the wires to 
 the works of the clock if we use the hour hand to bring 
 together two ends of wire so arranged as to close the circuit. 
 The support must then carry the two wires insulated and 
 stripped only at the two ends which the hand will cause to 
 touch. 
 
 Another way is to join one of the wires to the works 
 and place the other, ending in a piece of platinum wire of 
 yV rnm. diameter, flat on the dial over which the glass of the 
 clock is shut. The wire at this point is insulated by means 
 of a bit of paper, which will not prevent the closing of the 
 glass. 
 
Domestic Electricity for Amateurs. 75 
 
 The arrangement of these alarm clocks may be varied 
 indefinitely according to the ingenuity and skill of the 
 amateur electrician. 
 
 We cannot conclude these remarks without reference to 
 the three-contact clock of Dr. Ranque. Suppose we wish to 
 
 Fig. 61. 
 
 get up at 7 A. M. At 6.45 the first contact is made and sets 
 light to a spirit-lamp placed under a kettle of water ; at 6. 59 
 the alarum goes off, and a few seconds afterwards a third 
 contact lights a lamp. The amateur thus finds himself aroused, 
 the room lighted, and a kettle of warm water ready for his 
 toilet. 
 
76 
 
 Domestic Electricity for Amateurs. 
 
 CHAPTER VI. 
 
 ELECTRIC LIGHTERS. 
 
 Among the valuable services which may be rendered by elec- 
 tricity for domestic purposes, are gas, lamp, and fire lighters. 
 
 Electric lighters may vary much in shape and arrangement 
 according to the use for which they are intended, the places 
 where they are to be put, the combustible which they are to 
 set alight, &c. 
 
 We will, however, here only describe the simplest and most 
 practical of the numerous devices contrived. 
 
 To set fire to a given combustible substance an incandes- 
 cent material must be brought into contact with it, at a tempera- 
 ture varying with the nature of this substance, moderately 
 feeble for gas, greater for petroleum, and white heat for a stove 
 or a candle. For this purpose platinum wire is generally used, 
 rendered instantaneously incandescent by the passage of an 
 electric current. The temperature of this wire depends 
 entirely upon the current which traverses it. If this current 
 be sufficiently strong, platinum, chosen on account of its 
 inoxidability and its high point of fusion, will rapidly melt ; if 
 the current be too weak, the temperature of the wire will be 
 too low and the substance to be lighted may not take fire- 
 Experience will enable one to avoid these two extremes and 
 to so arrange the battery power that the wire will hardly ever 
 melt, and that a light is always produced. A very fine wire 
 will glow with a very weak current, but it will then be very 
 fragile and subject to breakage from the slightest accident. It 
 is therefore advisable to use wires tolerably strong (varying 
 generally from A' to of a millimetre in diameter), but the 
 current must then be a little stronger. The necessary current 
 
Domestic Electricity for Amateurs. 
 
 11 
 
 is easily obtained by using cells of large surface having a low 
 internal resistance, and as for a given E.M.F. the current 
 diminislies as the internal resistance increases, it is advisable 
 to reduce this internal resistance as much as possible. 
 
 The platinum wires are generally coiled into a spiral, the 
 object of this arrangement being to concentrate the heat in 
 one spot so as to increase the temperature at that point as 
 much as possible. A weaker current may therefore be used 
 than if the same wire be simply stretched out straight. In 
 fact a wire traversed by a uniform current hardly glows when 
 extended, while it gets up to white heat when coiled into a 
 spiral, because in the second case the heat lost by radiation is 
 much reduced. 
 
 Fig. 62. 
 
 Loiseau’s Lighter. — Fig. 62 represents a spirit or 
 petroleum lamp for the use of smokers. By pressing the 
 lamp against the wall the wick is brought close to the spiral 
 
78 Domestic Electricity for Amatettrs, 
 
 and the lamp presses a button which closes the circuit from 
 the battery. On releasing the lamp it is pushed a little 
 forward by the spring of the button and by this simple 
 arrangement the spiral is never in contact with the flame and 
 therefore lasts a long time. A very fine flattened wire is used 
 and the current from a single cell is sufficient to light the 
 lamp. The apparatus is so arranged that any one can easily 
 replace the spiral in an instant in case it is accidently spoiled. 
 
 With all lighters for spirit or petroleum lamps it is 
 important that the spiral never touches the wick : it should 
 be brought a little over it and to one side in the mixture of 
 air and inflammable vapour. 
 
 Fig. 63. 
 
 The Liuciphore. — This is also an apparatus intended 
 for smokers. It is composed essentially of a bichromate of 
 potash battery in a bottle and hermetically sealed. The two 
 
Domestic Electricity for Amateurs. 79 
 
 poles of the battery are joined to a very small platinum spiral 
 fixed above the lighter. When the battery is in its ordinary 
 position the liquid does not touch the zinc and carbon. By 
 taking it up as shown in the figure the liquid covers the 
 electrodes and the spiral glows, but the same motion also 
 brings a small spirit or petroleum lamp towards the incan- 
 descent spiral, which lights at once. 
 
 From 500 to 600 lights may be had without exhausting 
 the liquid ; the apparatus is again charged by renewing this 
 liquid with the chromic salt prepared by dissolving 4 oz. of 
 bichromate of potash in a quart of boiling water and adding 
 6 oz. of sulphuric acid to the solution when cool. 
 
 Unfortunately it is difficult to make a hermetically tight 
 joint, and owing to the damage 
 
 caused by the leakage of the Fig. 64. 
 
 acid solution this form of 
 lighter is not much used. 
 
 Desruelles’s Lighter. 
 
 — To avoid the defects of the 
 Luciphore the small lighter 
 shown in Fig. 64 has been de- 
 vised. This application may 
 be used with all batteries, and 
 consists in the introduction 
 into the batteries, in place of 
 liquids, of a sort of asbestos 
 sponge, soaked in acid or any 
 suitable solution. This gives 
 a species of dry battery which 
 may be moved, displaced, or 
 upset without any liquid spill- 
 ing, which is of advantage 
 for movable appliances, such as 
 portable lighters, batteries for 
 bells on board .ship, railways, 
 
 &c. 
 
 The lighter is composed of a small raised case of wood, in 
 which the battery is inclosed : in this case a small spirit-lamp 
 
8o Domestic Electricity for Amateurs. 
 
 is placed ; a platinum spiral near the wick produces the 
 light. 
 
 The battery is a bichromate of potash element in which 
 the liquid is replaced by an asbestos paste soaked in a bichro- 
 mate solution identical with that of the bottle batteries. 
 
 The zinc is suspended from a small lever which when 
 pressed brings it in contact with the paste ; the circuit is then 
 closed, the zinc is attacked and the current produced flows 
 through the spiral which glows and sets the spirit alight. 
 When the spiral no longer becomes red the paste must be 
 renewed, which is a very simple operation. When the lever is 
 not pressed the zinc is of course held up and out of action. 
 On the same principle may be constructed gas lighters, the 
 battery being in the handle, which may be of any required 
 length. 
 
 The fault of this apparatus is that the space occupied by 
 the inert substance leaves little room for the liquid, that is to 
 say, the exciting agent. The paste must therefore be frequently 
 renewed, which is practically a great inconvenience. 
 
 Gas Lighters. — Several arrangements for lighting gas by 
 electricity have also been brought out, and we will describe 
 
Domestic Electricity for A mateurs. 8 1 
 
 some of them. A very simple one is that shown in Fig. 65, 
 for smokers, candles, sealing a letter, &c. It consists of a 
 small gas-burner B on a round case about 3 inches in diameter, 
 and joined to a gas-pipe by an indiarubber tube A. By 
 moving the handle M the tap is opened, and an electric con- 
 tact established of sufficient duration to make the spiral G G' 
 glow and light the gas. It is handy in this case, to save wire, 
 to use the lead gas-pipe as return wire, especially if the battery 
 is far from the lighter. 
 
 In this arrangement the tap has a spring which tends to 
 turn it to a vertical position, and with a tooth which, inter- 
 locking in a pivoted piece D, keeps it in its horizontal position 
 as soon as it is turned. To extinguish the gas the lever D is 
 lowered, which enables the tap to return to its vertical position, 
 that is to say, the gas is turned off. 
 
 Another arrangement is that shown in Fig. 66. It is a 
 gas-tap for an ordinary burner, batswing, Argand or Man- 
 chester, having a spiral fitted to the side. One end of the 
 spiral is joined to the positive of the battery, the other to a 
 small horizontal brass rod, which will be seen on the bottom 
 of the figure. By opening the tap a slight escape of gas takes 
 place near the platinum spiral, and at the same time a pro- 
 jection firmly fixed on the tap presses a small vertical metallic 
 piece, bringing it into contact with the brass rod ; the circuit 
 is closed for an instant, the spiral glows and lights the gas, the 
 flame rises and finally lights the burner. It is needless to add 
 that by continuing the motion the contact breaks, in order not 
 to tax the battery uselessly and to reclose the escape. 
 
 The Fiat-lux. — This consists of a fine platinum wire sup- 
 ported by a swinging arrangement in connection with the two 
 poles of a battery of two or three Leclanches. By pulling down 
 the button on the left of the apparatus, shown in Fig. 67, either 
 direct or by means of a small cord fixed to this button, it at 
 the same time turns the gas on and brings the platinum spiral 
 to it, which by closing the circuit becomes incandescent, When 
 the gas is alight the apparatus is let go, the tap remains open, 
 the spiral moves away from the burner, the circuit is again open, 
 and the gas burns until it is extinguished by turning it off. 
 
 G 
 
82 Domestic Electricity for Amateurs, 
 
 This arrangement is particularly suitable in all cases where 
 there is a sudden need for a light, as a single action is suffi- 
 cient to open the tap and to light the gas. 
 
 Portable Gas -lighters. — These are mostly based on 
 the calorific properties of the spark produced by an induction 
 coil, and the internal arrangements allow the use of a powerful 
 battery, taking up very little space. The apparatus consists 
 of a rod of a length to suit the height of the burner, to the 
 lower part of which is fixed an ebonite tube an inch and a half 
 in diameter and 8 inches in length. This tube divides into 
 two parts, which are shown separately in Fig. 69, and incloses 
 the battery and the coil. The battery is a chloride of silver 
 cell, and is hermetically closed, and has a disc B and a brass 
 rim C on the upper end which form the two poles ; when the 
 two parts are screwed together these make contact with the 
 two springs B and C. 
 
 The battery is supposed to supply 25,000 lights before 
 exhaustion. H is an ebonite tube inclosing and protecting 
 the induction coil K, the secondary wire of which com- 
 
Domestic Electricity for Amateurs, 
 
 83 
 
 municates with the brass tube L and a central insulated 
 conductor M, the point of which is near to the end of the 
 
 FiG. 68. Fig. 69. 
 
 brass tube. The currents induced in this wire 
 give a series of sparks between the tube L and 
 the rod M, which light the gas when the end of 
 the apparatus is brought near to the burner. 
 
 When the end of the tube L is brought near 
 to the burner to be lighted, it is sufficient to 
 press the button E from left to right, in order to 
 develop a limited number of sparks sufficient to 
 light the gas. The effect of the motion of the 
 button F is not, as might be supposed, to close 
 the primary circuit of the coil ; in fact, in its 
 ordinary position, the trembler is some dis- 
 tance from its contact, and closing the circuit 
 produces no effect ; the motion of F causes a 
 mechanical displacement of the spring of the 
 trembler, which vibrates for some seconds, and produces a 
 definite number of contacts, giving rise to an equal number 
 
 G 2 
 
84 
 
 Domestic Electricity for Amateurs. 
 
 of sparks. Owing to this arrangement, the expenditure of 
 electric energy required for each lighting is limited, and on 
 the other hand, the trembler is worked mechanically, when 
 it would be unable to act if it were necessary for the current 
 to do the work. The required vibration being obtained from 
 the hand of the operator, the battery is saved this work, and 
 lasts longer. 
 
 For gas stoves a movable lighter, as shown in Fig. 70, 
 may be used. 
 
 Fig. 70. 
 
 The latest and perhaps the most remarkable form of gas 
 lighter is one which, though it resembles in external appear- 
 ance that shown in Fig. 68, is entirely different in principle. 
 It is in reality a small static machine of the Wimhurst in- 
 fluence type, the plates being spun at great speed by pressing 
 the button sharply. As no battery is used there is nothing to 
 be consumed, and the whole thing being merely a mechanical 
 contrivance, as long as the parts are not broken, it is an inex- 
 haustible source of sparks sufficient to light the gas. 
 
 All these lighters act well, and render real services ; they 
 may be considered a natural and indispensable adjunct to 
 domestic electric bells. 
 
 Combined Lighters and Extinguishers — To light 
 a lamp at a distance when it is out, or to extinguish it when it 
 is lighted, by simply pressing a button, sounds a difficult 
 problem, but by means of a double system of electro- 
 magnets, commutators, &c., somewhat complicated, this may 
 be effected. 
 
 In the arrangement shown in Fig. 71, the spirit or petro- 
 leum lamp is placed on a stand inclosing a horizontal electro- 
 magnet. The armature of this electro-magnet has two long 
 
Domestic Electricity for Amateurs, 85 
 
 copper rods, to which a small platinum spiral is fixed ; these 
 rods at the same time work a small bellows, to which is fixed 
 a tube, the end of which opens near the wick of the lamp. 
 
 Fig 71. 
 
 By sending a current through the apparatus (four bell 
 Leclanches or two large surface cells are sufficient) one of 
 the following two effects is produced : — 
 
 I. If the lamp is out, the current at the same time goes 
 through the electro-magnet and the spiral ; the first attracts 
 the armature and brings the spiral to the*wick, setting it 
 alight, but the bellows being acted upon before the spiral 
 approaches the wick, it blows at a lamp which is not burning, 
 which makes no difference, and when the current stops, 
 the spiral resumes its original position, leaving the lamp 
 lighted. 
 
86 Domestic Electricity for Amateurs, 
 
 2. When the lamp is burning the current passes as before, 
 but the bellows take effect this time, and the lamp is blown 
 out ; if the contact is not prolonged sufficiently to give the 
 spiral time to relight the lamp, the armature resumes its 
 original position, leaving the lamp extinguished. 
 
 The form of the apparatus permits of its being adapted to 
 a hanging lamp in a bedroom, ante-room, or other place 
 where the light is only required at irregular and unequal 
 intervals. 
 
 Fig. 72. 
 
 Fig. 72 shoWs a novel arrangement. An electro-magnet 
 inclosed in the stand brings the platinum spiral to the wick. 
 The extinguisher, balanced by a counterpoise, swings on a 
 horizontal axis. The support of this extinguisher has two 
 small pins acted upon alternately by two notches on an oval- 
 shaped piece, fixed on one side of the movable rods. 
 
Domestic Electricity for Amateurs. 
 
 87 
 
 In the position shown in the figure, on first closing the 
 circuit, the upper notch pulls the extinguisher, but the course 
 of the rods carrying the spiral is limited so that the spiral does 
 not hit the extinguisher, which would spoil it. The next 
 time the current passes, the lower notch lifts the extinguisher 
 up again, while the spiral is brought near to the wick, and 
 lights it. 
 
 It is convenient to work these combined lighters and 
 extinguishers not by a contact button, but by a pull, which is 
 easier to find in the dark. 
 
88 
 
 Domestic Electricity for A mateurs. 
 
 CHAPTER VII. 
 
 Domestic Electric Lighting. 
 
 Of all the domestic uses to which electricity may be put, with- 
 out contradiction, lighting is most tempting to amateurs, and 
 the desire increases every day, as the lamps get more perfected 
 and the numerous and incontestable advantages of this mode 
 of illumination are appreciated. The most serious obstacle to 
 the universal adoption of the electric light (apart from the 
 question of price which for a small installation is and must be 
 very high) is the inherent difficulty of producing the electrical 
 energy. When the distribution of electricity to every house 
 is an accomplished fact, the use of the electric light will 
 become general even if for an equal light a higher price has to 
 be paid than for gas. This extra expense will be largely 
 recovered by the less amount of disagreeable heat, decrease of 
 danger from fire, a steadier light, a more breathable atmosphere, 
 no more blackened ceilings, &c. 
 
 In spite of the inherent difficulties of the production of 
 electrical energy in sufficient quantity for lighting, many 
 private persons have got over these difficulties and have 
 installed for their own use regular model manufactories of 
 electricity sufficient to satisfy their daily or intermittent 
 wants. We will rapidly explain the principal things neces- 
 sary for an installation, such as motors, machines, batteries, 
 accumulators, lamps, and accessories. 
 
 Prime Movers. 
 
 All motors are not equally suitable for private lighting. 
 Steam engines require too much attention and can only be 
 used advantageously for installations of large size, and are 
 
Domestic Electricity for Amateurs. 89 
 
 therefore beyond the limits of the present work. Hot air 
 engines are also not suitable. This only leaves water motors, 
 applicable only in few cases, and gas engines. 
 
 If a sufficient fall of water be obtainable, high speed 
 turbines are the very best motors possible for driving 
 dynamos. Simply turning a tap starts and stops them, but 
 unfortunately it does not often happen that water power is 
 available and therefore we will not go further into this here.* 
 
 Gas Engines. — The gas engine possesses many of the 
 qualities necessary for domestic electric lighting, and in this 
 country, America, and the Continent very numerous installa- 
 tions are now running. Preference is almost universally given 
 to the Otto gas engine shown in Fig. 73. 
 
 A gas engine consists of a cylinder in which a piston 
 works ; a suitable mixture of air and illuminating gas is intro- 
 duced into the cylinder and this mixture is set alight, either 
 by electricity as in the old Lenoir engine, or by a gas jet as in 
 the Otto, Clarke, and Bishopp. 
 
 The high temperature produced by the combustion of the 
 mixture expands the gas and the piston is pushed with a 
 force depending upon the composition of the mixture, its 
 volume, and upon its more or less complete and efficient 
 combustion. When the expanded mixture has produced its 
 effect it is allowed to escape into the exhaust, a fresh mixture 
 is introduced into the cylinder, which is in its turn exploded, 
 and so on. 
 
 This is the principle : it is simple, but what difficulties in 
 application } These difficulties have been more or less 
 surmounted, especially in the Otto and Clarke engines. 
 
 The Machine. 
 
 The most convenient apparatus for experiments of short 
 duration is the hand or treadle Gramme, Fig. 74. If it is 
 desired to use it to charge a few accumulators with, and a 
 small hydraulic or gas motor is at hand, a pulley and belt are 
 
 * I can speak from experience of the great advantages of using water power 
 by means of turbines to drive dynamos, and thus obtain light from a natural 
 source, costing nothing. I have installed hundreds of lamps off turbines. — C. J. W. 
 
Fig. 73. 
 
 90 
 
 Domestic Electricity for Amateurs, 
 
 easily fitted. For charging accumulators particularly, the 
 magneto-electric machine has this advantage, that a reversal 
 
 of the current is impossible. In case of accidental stoppage it 
 will be sufficient to insert in the charging circuit an automatic 
 
Domestic Electricity for A mateurs. 
 
 91 
 
 contact-breaker which breaks the circuit before the accumu- 
 lators can discharge themselves through the machine. 
 
 For more important installations dynamos must be used, 
 that is to say, machines where the magnetic field in which the 
 armature revolves is an electro magnet and not a permanent 
 magnet. 
 
 Fig. 74. 
 
 For full description of dynamos, their construction, theory 
 and practice, see works devoted to the subject. We will here 
 only mention that shunt dynamos are more especially suitable 
 for charging accumulators, while compound-wound dynamo 
 machines are more especially suitable for direct lighting. 
 If, for example, our installation consists of 60 lamps, by 
 means of a compound machine it is possible to have a single 
 lamp alight or the whole sixty, and to light or extinguish 
 any number at pleasure, without interfering with the action of 
 the others. 
 
92 Domestic Electricity for Amateurs, 
 
 Heavy Current Batteries. — With reference to primary- 
 batteries for continuous work, we would refer the reader to 
 what we have already said (see p. 17) about some forms of 
 battery, but we will now refer more especially to some new 
 types which are intended and have been used exclusively for 
 electric lighting, but the question of cost and attention required 
 must not be too closely criticised by those who, though willing 
 to pay for the luxury of the electric light, only require a 
 small number of lamps, and can therefore not satisfactorily 
 or economically use dynamos and engines. 
 
 Bichromate of potash Battery. Trouve’s Tjrpe. 
 — When designing the battery represented by Fig. 75, Trouve 
 started with the idea of producing a source of electricity 
 
 Fig. 75. 
 
 capable of giving light for some hours (four to eight according 
 to the number of lamps in use) by means of incandescent lamps 
 suitable for this purpose, and requiring not more than 12 to 
 14 volts E.M.R, which enables a very fair amount of light to 
 be obtained from two batteries, the total weight of which does 
 not exceed 140 lbs. 
 
Domestic Electricity for Amateurs. 
 
 93 
 
 Each battery consists of an oak trough holding six ebonite 
 jars, which contain the liquid of each element. The zincs 
 and carbons, coupled up by movable connections, are mounted 
 on a windlass, enabling them to be immersed or withdrawn from 
 the liquid at pleasure, and to regulate the current by dipping 
 the electrodes more or less into the liquids, that is to say, by 
 varying the internal resistance of the battery and its active 
 surface. A wooden stop prevents the electrodes from coming 
 completely out of the jars ; on removing this stop and again 
 turning the windlass they rise completely out of the jars, so 
 that these may be removed for emptying and refilling. 
 
 The front of the trough is therefore furnished with a hinge 
 enabling it to be opened and the jars taken out without dis- 
 turbing the electrodes. These consist of a zinc plate and two 
 carbons, coppered on the top. The zinc has an indentation 
 which serves to fix it to the metal rod covered with india- 
 rubber, which supports the electrodes. This arrangement 
 allows the zincs to be very quickly taken out to amalgamate 
 or replace them. 
 
 The total weight of a battery of six cells is about 34 
 kilos., divided as follows : — 
 
 Six zincs 
 
 Twelve carbons .. 
 
 Six ebonite jars .. 
 
 Contacts 
 
 Oak case 
 
 Iron mountings . . 
 
 Liquids 
 
 Kilos. 
 7 '68 
 5*46 
 
 I ’62 
 
 O' 60 
 3*00 
 2-30 
 12' 80 
 
 Total weight 
 
 33 ‘46 
 
 The composition of the liquid for a battery is as follows : — 
 
 Kilos. 
 
 Water .. .. 8'o 
 
 Pulverised bichromate of potash . . i ' 2 
 
 Sulphuric acid 3*6 
 
 Total 12 '8 
 
 and is prepared as follows : — 
 
 The powdered bichromate of potash is thrown into the 
 water, and after being stirred up the sulphuric acid is added 
 
94 Domestic Electricity for Amatetirs. 
 
 very slowly, stirring all the time ; the mixture heats by 
 degrees, and the bichromate, once dissolved, remains clear and 
 does not crystallise in cooling. The preparation takes eight 
 to ten minutes. Care must be taken not to use a wooden 
 stirrer, which would be quickly’ carbonised, thereby exhausting 
 uselessly part of the solution. 
 
 Time must be given for the solution to cool before putting 
 it into the battery. 
 
 Two Trouve batteries in tension freshly charged with the 
 above solution have given the following results : — 
 
 1. A constant current of 8 amperes, during four hours and 
 a quarter, taking care to lower the zincs from time to time to 
 increase the active surface as the liquid became exhausted. 
 
 2. A decreasing phase of an hour and twenty-five minutes, 
 during which the current fell very regularly from 8 to 5 
 amperes, when the experiment was stopped. 
 
 The zincs, weighed before and after the experiment, 
 showed a total consumption of 1 1,463 grammes, or an average 
 of 122 grammes per cell. The theoretical consumption should 
 have been 53 grammes per cell, according to the electro- 
 chemical equivalents and the total quantity of electricity 
 furnished by the batteries. 
 
 The twelve elements therefore supplied a constant dis- 
 posable electric work of 1 3 ’ 5 kilogrammetres per second for 
 four hours and a quarter, and work of about 9 kilogrammetres 
 per second for about an hour and a half; a total of 253,350 
 kilogrammetres, or nearly one horsepower-hour. 
 
 We do not give the candlepower-hours as these have no 
 real value, no notice being usually taken of the efficiency at 
 which the lamps are burned, and if to-morrow a substance 
 should be discovered more refractory than carbon, and pos- 
 sessing its electrical qualities, it will then be possible to 
 double, quadruple, or increase tenfold the light without 
 increasing the expenditure of electrical energy. The number 
 of candle-hours furnished by the battery would be doubled, 
 quadrupled, or increased tenfold without the batteries con- 
 suming an atom less or producing a foot-pound more. 
 
 In fact, it is shown that the work that two newly charged 
 
Domestic Electricity for A mateurs. 
 
 95 
 
 Trouve batteries in tension can produce is 13*5 kilogrammetres 
 per second for four hours and a quarter, and a decreasing 
 delivery for about one hour and a half, during which the 
 current fell from 8 to 5 amperes, the total available energy 
 furnished being about one horsepower-hour. This electrical 
 energy costs : — 
 
 Grammes. 
 
 Zinc . . I • 360 
 
 Bichromate of potash 2^400 
 
 Sulphuric acid 7 • 200 
 
 in addition to amalgamation, labour, depreciation, and other 
 small expenses common to all systems. 
 
 Fig. 76. 
 
 Radiguet’s Battery. — This battery and its arrange- 
 ments and mode of construction will be easily understood 
 from the drawing Fig. 76, 
 
96 
 
 Domestic Electricity for Amateurs. 
 
 Reynier’s Battery. — This is a modification of the 
 Daniell cell, and its appearance is shown in Fig. 77. The 
 containing vessel is of copper and acts as positive electrode. 
 The zinc, in rectangular form, is covered with a porous pot 
 of parchment paper ; the zinc nearly entirely fills up this 
 
 Fig. 77. 
 
 porous cover, and a thin piece ot cloth sewn over all protects 
 the paper. 
 
 The sulphate of zinc is at first formed by local action at 
 the expense of the electrode and of a small quantity of 
 sulphate of copper which gets to it through the cover. The 
 cell, therefore, gets itself into its normal working condition, 
 and the excess of sulphate of zinc which is ultimately formed 
 by the closing of the circuit, diffuses itself towards the 
 external compartment. 
 
 The action of osmose is sufficient to keep up the supply, 
 and the harder the battery is worked the more the action of 
 osmose brings up the supply of sulphate of zinc. 
 
 To renew the sulphate of copper in the outer cell the india- 
 rubber tube with which each cell is provided is lowered, in 
 
Fig. 78 
 
 Domestic Electricity for A mateurs. 
 
 97 
 
 order to allow part of the exhausted liquid to run out ; 
 ordinary water is then added through these tubes, and sul- 
 
 phate of copper is put into a wicker basket hung on the 
 upper part of the containing vessel. 
 
 H 
 
98 
 
 Domestic Electricity for Amateurs, 
 
 In order to reduce the internal resistance, a mixture of 
 neutral or acid salts, soluble and cheap, may be added to the 
 cells, such as chlorides and sulphates of potassium and sodium, 
 sulphate of ammonia, nitrate and bisulphate of soda, &c. 
 
 Once a month the battery must be taken to pieces to 
 change the zincs and to clear away with a wooden knife the 
 lumps of copper which are deposited, the value of which is a 
 set-off against general expenditure. 
 
 For cells i6 inches by 8 inches by 2 inches, the constants 
 are 
 
 E = I • 07 volt. 
 
 R = o * 14 ohm. 
 
 The expenditure . per twenty-four hours of work is about : — 
 Sulphate of copper . . . . 400 grammes. 
 
 Zinc . . . . 100 „ 
 
 with a deposit of copper of nearly 90 grammes. 
 
 Mr. Reynier at his own house uses a battery of sixty-eight . 
 small cells. Fig. 78 represents it in its actual position under 
 the windows of the drawing room in a small court which 
 separates the house from the street. This battery is used for 
 the formation of accumulators, for work in the laboratory, and 
 for lighting the house as required. 
 
 Accumulators. 
 
 This is the name given' to any apparatus capable of storing 
 energy or work, in any shape, which may afterwards be given 
 out again at will. An electric accumulator then is an apparatus 
 which absorbs energy in the form of electricity (the charging 
 current), stores it as chemical energy, and subsequently gives 
 it up again in the form of electrical energy (discharging 
 current), available at will for lighting, motive power, &c. 
 
 An electric accumulator is nothing more than a reversible 
 battery, that is to say, a battery capable of being indefinitely 
 regenerated by sending a current through it in the opposite 
 direction to that which it itself produces, thereby recombining 
 in their original state its component substances, and thus a 
 fresh quantity of energy may be produced, limited in each 
 
Domestic Electricity for A mateurs. 99 
 
 case by the nature and quantity of active materials, as well as 
 the duration and power of the charging current. 
 
 Theoretically, every battery, the chemical action of which 
 does not set free gases which escape and are lost, is reversible 
 and capable of being an accumulator. 
 
 Practically, lead alone answers the purpose of alternate 
 charges and discharges, as was demonstrated by Plante in 
 i860. 
 
 Accumulators may also act as transformers, that is to say, 
 heavier currents than those of the original source may be 
 obtained from them for a proportionately shorter time, or 
 inversely, we may have smaller currents, lasting longer than 
 the original source. 
 
 For example, with 800 small Plante cells charged in 
 quantity by two Bunsens and subsequently coupled in tension, 
 a Geissler tube may be illuminated 
 direct, and all the so-called static elec- 
 trical effects may be reproduced. 
 
 On the other hand, small accumu- 
 lators have been constructed by a process 
 analogous to that of dry piles and 
 charged in series by a Holtz machine ; 
 by recoupling them subsequently in 
 quantity, effects of the same nature as 
 those furnished by so-called dynamic 
 electricity may be obtained. 
 
 Construction of an Accumu- 
 lator. — The most simple way to con- 
 struct an accumulator is to roll two long 
 and broad lead plates into a spiral, sepa- 
 rated by a piece of thick cloth. Fig. 79, 
 and then to plunge them into a jar full 
 of water, acidulated with sulphuric acid 
 in the proportion of 2 in 20 or 25 
 by bulk. This is the accumulator constructed by Plante in 
 i860. 
 
 The cloth has the disadvantage of rotting away in time 
 and also of increasing the internal resistance of the accumulator. ‘ 
 
IQO Domestic Electricity for Amateurs, 
 
 It is better to separate the plates by narrow strips of india- 
 rubber which do not rot in the acidulated water and only cover 
 a small portion of the surface of the electrodes. 
 
 To construct these cells, take two narrow strips of india- 
 rubber, Fig. 8o, about half an inch broad and a quarter of an inch 
 
 Fig. 8o. 
 
 thick, to prevent the plates touching. The prolonged contact 
 strips should be placed at opposite ends of the plates to avoid 
 short-circuiting them, and to equalise the distribution of the 
 primary currents on the surfaces of the electrodes. 
 
 The lead plates, thus separated by two or three pairs of 
 indiarubber bands, are wound on a wooden or metal cylinder. 
 
 It is well to place two small indiarubber bands lengthways 
 of the roller so as to thoroughly separate the edges of the two 
 lead plates. 
 
 The rolling up effected, the internal roller must be carefully 
 withdrawn, and to give stability to the whole system, the 
 spirals may be kept in their place by means of small gutta- 
 percha cross-bars fixed on when softened by heat. The couple 
 thus constructed is then put into a cylindrical glass jar filled 
 with water acidulated with i in lo of sulphuric acid. 
 
 Fig. 8 1 shows a cell constructed as described. 
 
 The containing glass jar is covered with a disc of hard 
 rubber, to which are fixed the terminal pieces. The ends of 
 the two lead plates are, by means of the binding screws G 
 
Domestic Electricity for Amateurs, loi 
 
 and H, both in contact with a small primary battery of two 
 Bunsen cells and with the copper strips M M'. The strip M 
 is fixed below another copper strip R, its prolonged end 
 making a spring which may be pressed down by the thumb- 
 screw B, and the strip M is then in communication with A. 
 
 Fig. 8i. 
 
 The strip M', on the other hand, is always in contact with the 
 clip A', and between these two clips are placed the metallic 
 wires to be reddened or melted by the current. To these two 
 clips may be attached the wires coming from any other 
 apparatus through which it is desiied to pass the current. 
 
 Chemical Action produced in Lead Secondary 
 Cells. — When a secondary cell of large surface is new, and 
 
102 
 
 Domestic Electricity for Amateurs. 
 
 the current from two Bunsen cells is passed through it, oxygen 
 appears almost immediately on the one plate, and it is not 
 long before this is covered with a very fine coat of peroxide 
 of lead. On the other hand, the hydrogen, after having 
 reduced the slight coat of oxide with which the lead may be 
 covered owing to exposure to the air, will soon make its 
 appearance on the other plate, and if after some seconds the 
 secondary current produced by the apparatus be tried, it will 
 be found from the crispness of the spark that it is already very 
 energetic. 
 
 During the discharge the oxygen on the plate, which 
 during the passage of the charging current was negative, has 
 slightly peroxidised this plate, at the same time that the per- 
 oxide formed on the other plate during the passage of the 
 primary current was reduced by hydrogen. After the first 
 experiment, therefore, the two plates are covered with a slight 
 coat of oxide and of reduced metal, which facilitate the action 
 of the charging current when again turned on. 
 
 The lead plate which during the first passage of the 
 charging current was negative is, as will be seen, covered with 
 a coat of oxide after the discharge has taken place. . It results 
 therefrom that if the charging current is again passed, the first 
 portion of hydrogen will be applied in the reduction of this 
 coat of oxide, instead of the thin coat due solely to exposure 
 to the air as happened previously. In consequence, the 
 appearance of hydrogen on the surface of this plate will be 
 more retarded than the first time. 
 
 The first portion of the oxygen set free on the surface this 
 time meets a coat of reduced peroxide or subdivided metallic 
 lead, on which the gas has more hold than on the original 
 lead plate ; the gas is more easily absorbed, and a delay is 
 also noticed in the appearance of oxygen on the plate, a delay 
 which corresponds to the time necessary to oxidise again the 
 coat of reduced lead on the surface. 
 
 When the current is again discharged, the preceding 
 phenomena are reproduced, and after these operations have 
 been renewed a very great number of times, it will be seen 
 that the surfaces of the plates are in a more favourable state 
 
Domestic Electricity for Amateurs. 103 
 
 for oxidation or reduction ; the coats of oxide alternately 
 formed and reduced become denser, and the secondary effects 
 resulting therefrom last longer and are more energetic. 
 
 It will, in fact, be noticed that the more primary current 
 a secondary cell can usefully receive, the longer is the duration 
 of the secondary current. All the work of the battery is thus 
 accumulated in the shape of oxidation of lead on the one 
 hand, and on the other in the reduction of oxidised lead 
 produced by the previous discharging current. When, in a 
 well-formed cell, the gases commence to appear and escape, it 
 is a sign that the battery can effect no more useful work in 
 storing energy. 
 
 A well-charged secondary cell will furnish a discharge 
 which depends on the size of the plates, the thickness of the 
 products, and finally on the external resistance of the circuit. 
 
 The discharge is very constant as long as the battery holds 
 stored electricity in the form of chemical energy. 
 
 In the same way as a very large vessel holding a great 
 quantity of liquid of very slight depth, may furnish for a long 
 time through a small orifice a nearly constant flow, ceasing 
 suddenly as soon as the liquid gets to the level of the orifice, 
 so a secondary battery of great surface only diminishes in 
 strength a short while before entirely stopping its supply. 
 
 The initial E.M.F. of a well-formed secondary cell reaches 
 nearly 2 \ volts, which explains why at least three Daniells 
 or two Bunsens are necessary to charge it completely. 
 
 The low internal resistance of the cells, which varies 
 between and i of an ohm, explains the strength of the 
 current furnished. Plante cells can also be charged by 
 laboratory Gramme machines ; but in that case the speed 
 must not fall below a certain rate, or else the battery will 
 discharge itself uselessly through the machine. To avoid 
 this an automatic maker and breaker of the circuit may be 
 used, which cuts out the secondary battery as soon as the 
 E.M.F. falls too low to charge it, and replaces it in the 
 circuit as soon as the E.M.F. is sufficient. 
 
 Secondary batteries keep the accumulated charge for a 
 long time. Thus a well-formed and well- charged secondary 
 
104 Domestic Electricity for Amateurs . 
 
 battery can still make a platinum wire J millimetre in diameter 
 glow more than a month after charging. 
 
 According to Plante the secondary battery gives a return 
 of 88 to 89 per cent, of the energy put into it, but this is never 
 reached in practice. 
 
 The formation of a secondary battery is a long and costly 
 operation, and many plans have been devised to reduce this. 
 Among them Plante discovered that the formation of the 
 elements is accelerated by increasing the temperature of the 
 electrolyte either before or during the action of the charge. 
 But practically this presents many difficulties. 
 
 A better plan is to soak the plates from 24 to 48 hours in 
 a strong nitric acid solution. They are then thoroughly washed, 
 fitted in the cells, filled with the proper electrolyte of weak sul- 
 phuric acid and water, and submitted to the charging current. 
 
 Notwithstanding a dissolution of a portion of the lead, the 
 thickness of the plates is not materially diminished, but the 
 acid produces a sort of metallic porosity, so that the chemical 
 action of the current is not limited merely to the surface of the 
 lead ; it acts also internally, creates new molecular intervals and 
 facilitates in consequence the action of the charging current. 
 
 Secondary cells so treated will, in a week, after three or 
 four reversals of the charging current, give results which 
 without the previous nitric acid process, they would only give 
 after several months of formation. It will therefore be of 
 interest to amateurs who desire to construct and form their 
 own accumulators, to know this process. 
 
 Faure’s Accumulator. — Faure’s secondary battery is 
 directly derived from the Plante battery ; his electrodes are of 
 lead, and are plunged in water acidulated with sulphuric acid ; 
 but its formation is more thorough and quicker. In the Plante 
 battery the formation is limited by the thickness of the lead 
 plates. Faure quickly gives his batteries an almost unlimited 
 power of accumulation, by covering the electrodes with 
 spongy lead, formed and retained in the following way : — 
 
 The two plates are each covered with minium or other 
 insoluble oxide of lead ; they are then covered with felt, 
 placed close together on a vessel holding acidulated water. 
 
Domestic Electricity for Amateurs. 105 
 
 If they are of great length they are rolled spirally, as in the 
 Plante cell. To form them a current is passed through them, 
 which brings the minium to the state of peroxide on the 
 positive electrode, and on the negative to reduced lead. As 
 soon as the whole mass has been electrolysed, the couple is 
 formed and charged. When it is discharged the reduced lead 
 oxidises, and the peroxided lead is reduced until the battery 
 is exhausted. It is then ready to receive a new charge of 
 electricity. We only describe it here as a matter of history, 
 as this type is now abandoned in favour of the Faure-Sellon- 
 Volckmar accumulator. The perfections to which the Faure 
 accumulator has been brought, and which have given rise, 
 after many transformations, to the apparatus known to-day as 
 the F. S. V. accumulator, consist in : — 
 
 1. Doing away with the felt, which does not last long in 
 the acidulated water. 
 
 2. In the ‘use of perforated lead plates in the shape of a 
 grating, holding the oxides of lead, which the current on the 
 one hand oxidises, and on the other reduces. 
 
 The reduced lead and the peroxidised lead are therefore 
 in the form of small blocks, round in the original model, 
 square in the actual practical type, surrounded on four sides 
 by a network of lead conductors, which place them in more 
 intimate connection with their respective electrodes than on 
 the original Faure type, in which the oxides were merely 
 applied to the surface of the lead plates. 
 
 There are three types current. 
 
 1. The laboratory type, weighing from 18 to 24 lbs. in glass 
 jars for amateurs, which may be used for lighting, electro- 
 deposition, &c., on a small scale. 
 
 2. The tramway type, weighing about 65 lbs., intended 
 especially for movable installations, such as tramways, 
 tricycles, and electric navigation. 
 
 3. The lighting type, weighing about 120 lbs., the use of 
 which is restricted to fixed installations.* 
 
 * These sizes and denominations only apply to French manufacture. The 
 F. S. V. accumulators made in England by the Electrical Power Storage Com- 
 pany vary somewhat in size and denomination from those referred to here. 
 
io6 
 
 Domestic Electricity for Amateurs. 
 
 Fig. 82 shows the tramway type in elevation and section. 
 It consists of a rectangular case of tarred wood, holding 
 17 lead plates, each in the form of a grating terminating in a 
 lead strip which serves as terminal. 
 
 Fig. 82. 
 
 Nine plates are joined on one side of the box in quantity 
 to form the negative pole, and the other eight on the oppo- 
 site side to form the positive pole. The joints are made 
 by pinching the projecting strips between two lead plates in 
 communication with the terminals N and P. The plates are 
 kept apart by indiarubber rings. The brackets C are for the 
 purpose of leaving a space at the bottom of the boxes where 
 any particles of reduced or oxidised lead detached from the 
 
Domestic Electricity for Amateurs, 107 
 
 electrodes may fall and accumulate without making a short 
 circuit between the plates. * 
 
 The mean weights of a tramway accumulator are divided 
 as follows : — 
 
 Kilos. 
 
 Tarred wood case, lid, handles, and terminals .. .. 6*0 
 
 Acidulated water of i in lo 6*5 
 
 Lead plates and oxides i6‘8 
 
 The gaps of the positive and negative plates are respec- 
 tively filled up with litharge and red lead or minium, which is 
 previously made into a paste and spread on the plates and 
 then by pressure all the holes are equally filled up. 
 
 The plates thus prepared are fixed in the cases and 
 submitted to a formation which consists in passing a current 
 through them proportionately powerful to the surface of 
 the plates, the duration of which is about lOO hours. The 
 number of lOO hours is not absolute, as after this formation 
 the accumulators still gain in capacity with each new charge 
 as they are used in consequence of the gradual attack of the 
 lead supports. 
 
 The accumulators for lighting purposes differ only from 
 the tramway type in weight and size ; they are proportionately 
 heavier in order to obtain greater solidity and lasting power. 
 
 Storage Capacity. — All experiments with accumulators 
 go to show that the total recoverable energy from a given 
 weight of accumulators, diminishes as the work demanded in 
 a given time is increased, that is to say, the greater the current 
 taken out, the less will be the total output. 
 
 From recent experiments with F. S. V. accumulators, 15 
 ampere-hours per kilogramme of plates have been obtained 
 with a mean useful potential of 1*9 volt at the terminals, 
 that is, 10 ampere-hours per kilogramme of the total weight, 
 taking the weight of both cover and liquid at 50 per cent of 
 that of the lead plates. 
 
 A horsepower-hour of electrical energy is thus obtained 
 from a weight of 40 kilogrammes or about one electrical horse- 
 power per 88 lbs. 
 
 The capability of accumulators in which lightness is not so 
 
io8 Domestic Electricity for Amateurs, 
 
 much an object, is of course less, and the weight of material 
 necessary to produce one electrical horsepower-hour may 
 reach 170 lbs. 
 
 EfBLciency and Duration of Accumulators. — It is 
 
 of interest to know, when accumulators are used, how the 
 losses sustained in the different transformations are appor- 
 tioned from the moment the energy is furnished by the prime 
 mover (steam, water, or gas), up to the moment it is again 
 given out in the form of mechanical work. The following 
 figures apply under ordinary conditions : — 
 
 Mechanical work absorbed by the charging machines .. .. loo 
 
 Electrical energy furnished by these machines, and available 
 
 for the charge 0*7 x loo 70 
 
 Only about o • 9 of the quantity of electricity furnished by the 
 charging machines is obtainable from the accumulator, and 
 the pressure or mean E.M.F. of discharge is only o* 7 of the 
 mean charging E.M.F. ; the available electrical energy is 
 therefore only o'9XO'7 = o*63 of the energy of the 
 charge supplied to the accumulators. 
 
 It results therefrom that the available electrical energy is equal 
 
 to O’ 63 X 70 of the initial motive power = 44’ i 
 
 Finally, when this electrical energy is transformed back into 
 mechanical work, only O’ 7 or O’ 7 x 44' i 30 ’8 
 
 is obtained, that is to say, about 31 per cent, of the initial 
 mechanical work supplied by the prime mover. 100 horse- 
 power-hours must therefore be expended in the motor which 
 drives the charging machines in order that the accumulators 
 may supply 31 available horsepower-hours for locomotion or 
 any other application. 
 
 According, therefore, as the available electrical energy is 
 utilised direct or transformed into mechanical work 44 or 3 1 
 per cent, of the available initial work is obtainable for industrial 
 purposes. 
 
 No reliable figures respecting the duration of accumulators 
 are so far available. The lighting apparatus installed per- 
 manently, charged and discharged systematically, will last 
 very much longer than batteries for vehicles subject to rapid 
 charging, irregular use, and much knocking about. Plante’s 
 accumulators of simple lead plates seem to offer greater 
 guarantees in this respect than the F.S.V. accumulators. 
 
Domestic Electricity for Amateurs, 109 
 
 Applications. — In spite of the loss which must be 
 suffered by means of the intermediary of accumulators they 
 offer great and numerous advantages. Foremost among their 
 advantages, accumulators are most useful for purposes of 
 instruction whether on the lecture table or in the laboratory, 
 not only for the studies to which they give rise, but also for 
 the many electrical operations to which they so easily lend 
 themselves. 
 
 Fig. 83 represents 20 Plante cells arranged for this pur- 
 pose. At the upper part is a commutator which in one posi- 
 tion couples the 20 cells in quantity and in another puts them 
 
 all in series. In the first case all the external electrodes are 
 joined to one metallic plate and all the internal electrodes to 
 another, in such a way that the entire apparatus is like a 
 single cell of great surface ; the charge is then effected ; 2 
 Bunsens are sufficient, and in a longer or shorter time accord- 
 ing to their dimensions and the extent of the lead surfaces they 
 are fully charged. In the second case the external electrode 
 of each element is put in communication with the internal 
 electrode of the succeeding cell and the apparatus is made a 
 veritable battery of 20 cells, and under these conditions the 
 battery may be discharged, the current available being equal 
 to 30 Bunsens of very large surface. 
 
 In fixed installations where the accumulator has to act the 
 part of a fly-wheel, regulator, or receiver, it may also render 
 
no Domestic Electricity for A mateurs, 
 
 efficient service, for example in lighting applications it gives 
 more constancy and steadiness to the light and renders 
 accidental total or partial extinction impossible, which in a 
 theatre, for example, would be a veritable disaster. 
 
 Accumulators also enable more light to be obtained for a 
 time than by using direct the disposable power, this result 
 being obtained by expending in 4 or 5 hours all the work 
 produced by the engine in 20 hours. 
 
 Accumulators may also be used as movable reservoirs of 
 electrical energy in applications where expense is a secondary 
 matter. 
 
 For example, assemblies, balls, and soirees may be lighted 
 by means of incandescent lamps fed by accumulators brought 
 to the house from the factory in carts. The cost of an installa- 
 tion of this nature is not so much more than that paid for 
 other modes of temporary lighting that it cannot be difficult 
 to make it pay in the same way as similar hirings of marquees, 
 chairs, flowers, &c. 
 
 We may also refer to pleasure boats, electric tricycles, and 
 small luminous jewels for which accumulators are or soon will 
 be perfectly applicable and to which w^e will further allude 
 presently. 
 
 Electric Lamps. 
 
 The amateur electrician can only make use of the arc 
 light in exceptional cases ; the only electric lamps suitable for 
 him are the carbon incandescent lamps. All these lamps, 
 which vary considerably in shape and size, have a filament of 
 carbon inclosed in a glass globe, exhausted as much as 
 possible of air to prevent the combustion of the carbon. 
 Almost any candle power and resistance may be obtained, and 
 their price is at present 5^. each. 
 
 We cannot here undertake to describe their manufacture, 
 which is a complicated and difficult operation. Besides, it is 
 very easy to procure them at present, and we advise those who 
 require them simply to buy them instead of trying to make 
 them. 
 
 The characteristic point of incandescent lamps is the 
 
Domestic Electricity for Amateurs. 1 1 1 
 
 nature of the filament. Edison uses carbonised bamboo, 
 Maxim cardboard, Swan cotton, &c. 
 
 When buying an incandescent lamp the following three 
 points are important to know : — The normal luminous power ; 
 the amount of current in amperes which furnishes this lumin- 
 ous power ; the necessary potential difference at the terminals 
 of the lamp in volts. 
 
 The least known and least correct figure is the luminous 
 power of the lamp. Manufacturers of lamps and batteries 
 have the bad habit of over-estimating the light produced. 
 The possibility of forcing the lamps by increasing the current, 
 added to the different standards in use, explains to a certain 
 extent these errors. It is certain, however, that the pro- 
 gress made within three years in the manufacture of incan- 
 descent lamps, has doubled the light which a lamp for a given 
 consumption of electric energy under normal conditions can 
 supply. Normal conditions we call those when the lamp 
 gives -a sufficiently white light, lasting a long time without 
 the filament breaking through gradual disintegration. 
 
 When the filament is broken the lamp is useless. The 
 duration or life of lamps depends, everything else being equal, 
 on their being used at a normal state of incandescence. The 
 one is shortened by increasing the other, and conversely. 
 Practically a mean must be adopted, the value of which it is 
 difficult to indicate exactly. It may, however, be conceded 
 that a lamp, the filament of which can be clearly distinguished 
 when incandescent, may, from the point of view of luminosity, 
 be traversed advantageously by a stronger current. A lamp, 
 on the other hand, the filament of which cannot be distin- 
 guished is too much forced. Practically a lamp should not be 
 run higher than where the shape of the filament begins to 
 disappear. 
 
 In lamps of small dimensions, this critical point is often 
 exceeded and thus they last but a short time. Lamps of 
 medium size last with proper management from 500 to 2000 
 hours. Lamps have been known to last 4000 hours ; others, on 
 the contrary, are rendered useless within a few hours or even 
 minutes. 
 
1 1 2 Domestic Electricity for A mateurs. 
 
 It will be seen within what wide limits the life of a lamp 
 varies and the reason thereof will be well understood. 
 
 As we have now sufficiently defined what must be under- 
 stood by normal power and proper management of a lamp, 
 let us examine how the constants C and E of an incandescent 
 lamp vary under these conditions. 
 
 The consumption of a lamp is calculated in watts or in 
 volt-amperes. A lamp of which 
 
 C = I * 2 ampere 
 E = 50 volts 
 
 is a lamp of i *2 x 50 = 60 watts. 
 
 The value of C depends upon the size of the filament ; it 
 varies between 0*4 and 2*5 amperes in ordinary lamps. The 
 value of E depends at one and the same time on C and on 
 the length of the filament. For electric jewels small lamps are 
 constructed which only require 2 volts and act with a single 
 accumulator ; while Edison lamps, A type (16 candles), require 
 100 volts, and Swan lamps, 20 candle-power, from 41 to 120 
 volts as desired. A useful lamp for the amateur electrician is 
 a Swan lamp of five candles, supplying a light sufficient for 
 work in an office, if the light be reflected down by means of a 
 shade. The E.M.F. required may be 10, 15, or 20 volts and 
 the current i, 0'66and0'5 respectively, thus consuming 10 
 watts. 
 
 A type of Swan lamp much employed in small installa- 
 tions is that equal to an ordinary gas-jet and may be had of 
 10, 15, 20, 25, 30, and 50 volts with current in proportion, the 
 energy required in every case being 20 watts. The horse- 
 power being equal to 746 watts, it will be seen that with one 
 horse-power of available electrical energy it will be possible 
 to supply 37 such lamps. With good dynamos this means 
 from 25 to 30 lamps per actual horse-power supplied to the 
 driving shaft. An Otto gas engine of three and a half horse- 
 power is quite sufficient therefore for an installation of 100 
 such lamps. 
 
Domestic Electricity for Amateurs, 
 
 113 
 
 Accessories. 
 
 The most important detail in fitting up a lamp is the 
 holder, and to find a good lamp-holder is not an easy task. 
 It should be solid, well insulated, and convenient to handle 
 both for cleaning and for replacing a lamp. 
 
 Fig. 84 shows a very simple and rough form ; it consists 
 of a brass wire A, coiled to make a ring, in which the neck of 
 the lamp fits ; in the upright part of this wire is a curl which 
 gives it the necessary elasticity ; the platinum loops of the 
 lamp are fixed to the hooks B B. The whole is fitted to a 
 wooden socket C, which may be screwed into an ordinary 
 chandelier or in place of a gas burner. 
 
 Fig. 84. 
 
 Fig. 85. 
 
 Sometimes a small switch is added to light or extinguish 
 the lamp at pleasure. 
 
 Fig. 85 shows another and more usual holder fitted to a 
 movable standard with a shade. If a more ornamental 
 support is desired, Trouve s chandeliers may be used, Fig. 86 
 
 I 
 
Domestic Elecbncity for A mateurs. 
 
 114 
 
 Fig. 86. 
 
Domestic Electricity for A mateurs. 1 1 5 
 
 or 87, and as will be seen these combine both the electric light 
 and ordinary candles in one fitting. 
 
 Of course these designs may be multiplied indefinitely, 
 and any of the regular makers supply many varieties both 
 
 Fig. 87. 
 
 plain and ornamental, and either specially designed for the 
 electric light or both gas and electric light combined, or as in 
 this instance, candles and electric light combined. 
 
 In movable fittings it is often convenient to be able to 
 remove the lighting arrangement, or at least the conductors 
 during the day. This necessitates a system by which the 
 separation can be very quickly effected. Fig. 88 shows a very 
 
1 1 6 Domestic Electricity for Amateurs, 
 
 crude form, but these are being much improved from day to 
 day. 
 
 The great Swan lustre which lighted the buffet at the 
 Electrical Exhibition of Paris, in i88i, is historical, and we 
 reproduce it in Fig. 89, but since that time many more 
 elaborate and artistic fittings have been made, but even this 
 shows with what facility the electric light lends itself to 
 decorative effect. 
 
 Fig. 88. 
 
 In an electric light installation the accessories are very 
 numerous and it is impossible to enumerate and describe them 
 all. Lamp-holders, shades of all colours and designs, multiple- 
 way switches, contact-breakers, fusible safety cut-outs, &c., 
 in endless variety are made by all the suppliers of electric 
 light necessaries, and we would refer our readers to the well- 
 known manufacturers for the latest designs and improve- 
 ments. 
 
 Test Bell for primary and secondary batteries.— 
 
 When accumulators are used it is often necessary to know the 
 terminals which correspond to the positive and negative poles, 
 
Fig. 89. 
 
 Domestic Electricity for A mateurs. 1 1 7 
 
 especially during formation, when they are being constantly 
 changed. 
 
 The small apparatus shown in Fig. 90, is useful for this 
 purpose. It consists of a small portable bell, in the shape of 
 
 
1 1 8 Domestic Electricity for Amateurs. 
 
 a flattened cylinder serving at the same time as a case for the 
 mechanism. A handle fixed to the case enables it to be easily 
 held, and to bring the two movable wing terminals in contact 
 with the two poles of the battery to be tested. The electro- 
 magnet hidden in the case attracts an armature with a small 
 
 Fig. 90. 
 
 hammer at the end which strikes the bell as will be understood 
 from the drawing. The more or less powerful tingling of the 
 bell indicates with some practice the state of the battery, and 
 the apparatus is a sort of acoustic galvanometer. 
 
 This little apparatus may be put in the pocket and enables 
 a great number of elements to be tested in a very little time. 
 A hole in which appears the sign -j- or — , according to the 
 direction of the current, indicates the name of the pole in 
 contact with the terminal nearest the hole. This result is 
 obtained by means of a small magnetised steel plate, which 
 under the influence of the current passing through the electro- 
 magnet tends to one pole or the other according to which 
 way the current passes. 
 
 Switch-board for charging, discharging, and 
 recoupling accumulators.— According to the nature of 
 the charging machine and the apparatus through which the 
 current is discharged, it is often necessary to arrange 
 accumulators in series, multiple arc, or combinations of the 
 two. At other times it may be convenient during formation, 
 for example, to discharge well-formed accumulators through 
 
Domestic Electricity for Amateurs, 1 19 
 
 other accumulators in process of formation. All these 
 arrangements may be effected by means of a mercury 
 commutator of simple construction. 
 
 This may be made of a wooden or ebonite board about an 
 inch and a half thick, in which holes are drilled about an inch 
 apart. These holes should be about f of an inch in diameter, 
 and about an inch deep. They are nearly filled with 
 mercury. 
 
 The first and last rows of holes are joined to terminals by 
 small copper strips, which are sunk into the corresponding 
 holes of these rows. Each series of accumulators is attached 
 by wires to a pair of terminals forming groups i, 2, 3, 4, &c. 
 
 The coupling up is effected by means of movable U"Shaped 
 pieces of copper wire of No. 10 or 12 B.W.G., which make 
 contact between the different mercury cells. 
 
 These y -shaped wires should be insulated along the part 
 which does not dip in the mercury, so that they may lie over 
 and cross each other without making contact between each 
 other. 
 
 Automatic Contact-breaker. — If owing to any cause 
 the source of the charge does not develop an E.M.F. sufficient 
 to overcome the back E.M.F. of the accumulators, they will 
 discharge themselves through the machine, expending in pure 
 loss the electrical energy originally stored. 
 
 The object of the automatic contact-breaker is to prevent 
 this by opening the circuit as soon as the charging current is 
 no longer sufficient. 
 
 This apparatus consists of an upright electro-magnet, the 
 coils of which are in the charging circuit. This electro-magnet 
 keeps a small armature attracted, and the circuit is closed by 
 a lever plunged into the mercury cells. 
 
 When the current becomes too weak the armature is 
 released, the armature flies back and breaks the circuit before 
 the current has time to reverse. The circuit must then be re- 
 established by replacing the armature by hand. 
 
 A more complete arrangement, combining an automatic 
 make and break, itself closes the circuit when the E.M.F. has 
 again become sufficient to effect the charge. 
 
I 20 
 
 Domestic Electricity for A mateurs. 
 
 A third mercury cell serves to close the circuit of the 
 accumulator on a bell which gives notice the moment the 
 charging current is broken. 
 
 MareschaPs Apparatus to work Bichromate 
 Batteries from a distance. — Bichromate of potash 
 batteries, especially the single fluid batteries, used for domestic 
 
 Fig. 91 . 
 
 electric lighting, have the grave defect of consuming nearly as 
 much zinc on open as on closed circuit, and exhaust themselves 
 uselessly and rapidly if it is neglected to withdraw the zincs 
 from the battery when not in use. But this purely mechanical 
 
Domestic Electricity for A mateurs, 1 2 1 
 
 operation necessitates that the battery be placed near to the 
 spot where it is used, or that a complicated and unornamental 
 arrangement of mechanical transmission be put up. 
 
 In order to obviate this defect inherent to all bichromate 
 batteries, the arrangement shown in Fig. 91 has been designed. 
 
 A frame carrying all the zincs of the battery is suspended 
 from the extremity of a horizontal beam, balanced by means 
 of weights on the other end. 
 
 The system thus balanced, the lifting of the zincs or their 
 immersion requires only slight mechanical work, which is 
 obtained from an ordinary clockwork by means of a combina- 
 tion easily understood by reference to Fig. 92, which shows 
 the principle. 
 
 Fig. 92. 
 
 The axis M moves the crank M D, to which is fixed a 
 connecting rod A, the other end of which is fixed to the 
 horizontal beam supporting the zinc and the counterpoise. If 
 the axis M of the jack be continuously rotated it communicates 
 to the connecting rod a reciprocating motion, which is trans- 
 mitted to the beam, and alternately immerses the zincs and 
 lifts them out of the liquid. 
 
 By stopping the crank M D in suitable positions, the zincs 
 may be maintained at pleasure immersed in the liquid or 
 raised out of it. The clockwork acts on a horizontal fly-wheel 
 V, against which is pressed an iron shoe F, placed opposite an 
 
1 2 2 Domestic Electricity for A 7nateurs. 
 
 electro-magnet E. In the ordinary position, this shoe by 
 reason of a spring puts a break on the fly-wheel, but when a 
 current is sent through E, the shoe F is attracted and frees 
 the fly-wheel, the clockwork revolving until the current ceases 
 to pass through the electro-magnet 
 
 The question is therefore reduced to sending a current into 
 the electro-magnet and to stop this current at the proper time. 
 This is easily done by means of an auxiliary Leclanche battery 
 (the battery for the bells of the house may be used), by closing 
 the circuit of this battery on the electro-magnet E by means 
 of a button B, when it is desired to light or extinguish a lamp. 
 In the position of rest, for example, the crank M D is vertical, 
 as shown by the small diagram on the right of Fig. 94. The 
 circuit is opened between M and N by means of the pin C, 
 which keeps the spring R apart from the spring R'. As soon 
 as the circuit is closed, if only for an instant, the crank quits 
 the vertical position, the pin C leaves the bend S, and R, by 
 reason of its elasticity, touches R' and continues the contact 
 until the handle M D having completed half a turn the pin C' 
 pushes the plate R and opens the circuit again, the break acts, 
 the crank stops after having revolved through 180 degrees, 
 immersing the zincs to the utmost. To extinguish the lamp 
 the button B is again pressed. The axis M makes another 
 half turn, and when it stops the zincs are entirely lifted out ot 
 the liquid. 
 
 The depth of the immersion is regulated by fixing the pin 
 D of the crank in the holes Ti or T2 of the connecting rod, 
 which enables the stroke to be varied, and in consequence the 
 degree of immersion. 
 
 The installation necessitates three wires, two of which join 
 the lamp to the battery, and the third is to work the apparatus 
 by closing the circuit at B. 
 
 It is often necessary to vary regularly and gradually the 
 resistance of an electric circuit in order to increase or diminish 
 at pleasure a current which passes through it, particularly in 
 electric lighting by batteries, as in switching on, the first spurt 
 of a bichromate battery before it polarises may be more than 
 the lamps will stand. To obviate this and provide a small 
 
Domestic Electricity for Amateurs. 
 
 123 
 
 and easily used resistance-coil, Trouve designed the apparatus 
 shown in Fig. 93. 
 
 It consists of a spiral of German silver wire, inclosed in a 
 nickeled brass tube, the spirals being kept from each other 
 and insulated from the brass tube by a pasteboard case. 
 Inside slides an elastic contact, made by a metallic rod split 
 into four parts, slightly opened out from each other. 
 
 Fig. 93. 
 
 The current comes from the right, passes through the 
 spiral, the contact, and the rod divided in degrees. In the 
 position shown by Fig. 93 the rod is at the bottom, and as 
 the current only goes through one or two turns of the spiral, 
 the resistance introduced is at a minimum ; but when the rod 
 is pulled out, the current, before it reaches the contact, must 
 pass through more turns of the spiral, and consequently pass 
 through more resistance. The divisions marked on the gradu- 
 ated rod correspond to the number of turns of the spirals 
 included in the circuit. 
 
 This apparatus is applied by Trouve to his polyscopes ; it 
 enables the current supplied by a Plante accumulator to be 
 regulated and to maintain the small platinum wire at the 
 desired degree of incandescence in each particular case. 
 
124 
 
 Domestic Electricity for Amateurs. 
 
 CHAPTER VIII. 
 
 DOMESTIC APPLICATION OF THE ELECTRIC LIGHT. 
 
 This subject may be divided into two classes, characterised 
 by the presence or absence of a mechanical motor for driving 
 an electrical generating machine : the first applies to large 
 installations for those who are prepared to sink a certain 
 amount of money ; the second, small installations comprising a 
 limited number of lamps, and accessible to more modest 
 means. 
 
 Large Installations. 
 
 The arrangements vary with each installation according 
 to the nature of the motor used, the room at disposal, the 
 light demanded, the richness and decoration of the rooms to 
 be lighted, &c. 
 
 Fig. 94 shows a complete installation, in a basement, of an 
 Otto gas engine of 4 horse-power driving two Gramme 
 machines for the supply of incandescent lamps distributed 
 over a private mansion. 
 
 Lighting; Direct. — As an example of this system we 
 may mention the house of M. Forges, manager of the Edison 
 Company in Paris, who uses a two-cylinder Otto gas engine 
 of 8 horse-power. The machine, Edison K, feeds 60 A lamps 
 requiring each 0*75 amperes and 100 volts at the terminals. 
 The installation consists, however, of more than 100 lamps, 
 because on the one hand all the lamps are never alight at the 
 same moment, and on the other hand a certain number of B 
 lamps are substituted for A lamps, these requiring only 50 
 volts, and also some lamps of a still smaller type requiring 
 
Fig. 94. 
 
 Domestic Elect 7 'icity for Amateurs, 125 
 
 only 15 volts. The 50 volt lamps B are of course two in 
 series, and the 1 5 volts seven in series. 
 
 The inconvenience of this installation is evident a priori : 
 the gas-engine must go, no matter what number of lamps are 
 
126 Domestic Electricity for Amateurs. 
 
 alight ; but this system works very well in practice, and there 
 are at the present moment hundreds of such domestic installa- 
 tions in this country, many of which have been working for 
 several years and give undoubted satisfaction. 
 
 Indirect Lighting by means of Accumulators may 
 in many cases be more advisable, and the following is a 
 sample. 
 
 The total installation comprises 150 Swan lamps of 40 
 volts and 0‘7 amperes fed by 22 Faure-Sellon-Volckmar 
 accumulators of the 2 horse-power type all in series. 
 
 These accumulators can safely give a current of 40 to 45 
 amperes which enables 60 lamps to be supplied at once — a 
 sufficient number under ordinary circumstances. 
 
 These accumulators are charged daily, during the day, by 
 a shunt machine, the power of which is regulated by means of 
 resistances in the exciting circuit. 
 
 This machine is driven by an Otto gas engine of 5 horse- 
 power. With a little experience the servant in charge of the 
 lighting estimates accurately enough the consumption of the 
 previous day in ampere-hours and he recharges the accumu- 
 lators with about an equal quantity, giving them 10 or 15 per 
 cent, more, to allow for losses and possible errors. 
 
 Thus, for example, let us suppose that over night 60 lamps 
 have been alight for 4 hours. The total consumption in 
 ampere-hours will be: 60 x 0*7 x 4 =168 ampere-hours. 
 
 The accumulators are recharged for about 5 hours with a 
 current of 40 amperes so as to supply them with 40 x 5 
 = 200 ampere-hours. 
 
 Owing to the use of accumulators, the lamps in all parts 
 of the house may be lighted at any time, day or night, by 
 simply turning a switch. 
 
 On days when it is desired to light the whole house and so 
 to use nearly all the lamps, the accumulators should be 
 charged thoroughly during the day and then by running the 
 machine parallel with the accumulator nearly the whole of the 
 lamps may be lighted at one time. If the machine gives 60 
 amperes and the accumulators 40, this makes 100 amperes in 
 all, and quite sufficient for the whole work. The conductors,. 
 
Domestic Electricity for Amateurs. 
 
 127 
 
 thoroughly insulated with indiarubber, should be designed 
 for currents in excess even of this figure, and then even with 
 the maximum current no heating of the leads can take place. 
 
 Small Installations. 
 
 Direct Lighting. — Easy as it is, and often economical, to 
 install industrial lighting by means of dynamos driven by water, 
 steam, or gas engines, it is difficult and costly to put up a small 
 domestic lighting plant consisting of one or a small number 
 of incandescent lamps to supply each day four to five hours of 
 light. Every one knows that the difficulty consists in the pro- 
 duction of the electrical energy, which for small installations 
 should always be obtained through the medium of chemical 
 energy, that is to say, by primary batteries. Unfortunately, 
 comparatively cheap and constant batteries give too weak a 
 current, and it requires a great number of cells to obtain satis- 
 factory results ; constant batteries of suitable output are dear, 
 and have for the most part the defect of expending nearly • 
 as much active substances, zinc and liquids, on open as on 
 closed circuit, which necessitates the withdrawal of the zincs 
 from the liquid when the lamps are not lighted. We have 
 previously described (p. 14, 92, et seq.) several useful bat- 
 teries for domestic electric lighting. Their advantages and 
 inconveniences must now be explained. 
 
 Lalande and Chaperon’s oxide of copper batteries have the 
 great advantage over some others in as much as they may 
 remain set up for several months, without being touched, and 
 thn.t during this time they may supply at regular or irregular 
 intervals, an amount of electrical energy and consequently a 
 corresponding duration of light proportionate to the size of the 
 elements used: Thus during the winter 1883-4 a battery of 
 
 12 trough elements of small size supplied light for about 120 
 hours to a small incandescent lamp of 6 volts. When these 
 batteries are used for direct lighting it is necessary, however, 
 to include in the circuit a variable resistance, which may be 
 gradually switched out as the E.M.F. falls and the internal 
 resistance rises ; besides this, as the batteries become ex- 
 
128 Domestic Electricity for Amateurs. 
 
 hausted the E.M.F. and resistance get worse and worse, so that 
 eventually more cells have to be switched in. This of course 
 all means a great loss of energy and the zinc consumed is not 
 in proportion to the useful work obtained from it. Single 
 fluid bichromate of potash batteries may be used for a few 
 hours’ lighting. With two windlass batteries of 6 elements 
 each coupled up in tension, 4 or 5 lamps of 14 to 16 volts may 
 be lighted for 4 or 5 hours. We will not go into the photo- 
 metrical power of the lamps. When it is desired to supply 
 only a single lamp at once the duration of the light may be 
 proportionately increased, but it is necessary not to plunge the 
 zincs too deeply into the liquid so as not to destroy the lamp, 
 as well as in order to diminish the local action which consumes 
 the zinc uselessly. 
 
 With double fluid bichromate of potash batteries the local 
 action is reduced but the internal resistance of the element is 
 increased by the presence of the porous pot and the output is 
 diminished. With equal dimensions the double fluid batteries 
 can supply less lamps at once than single fluid batteries. 
 
 We reproduce here Radiguet’s 8-cell battery, Fig. 95, 
 intended to supply one or two lamps of 12 volts. The 
 F.M.F. is about 2 volts per cell, which is 16 volts for the 
 8 cells in series, and 12 to 13 volts are available at the 
 terminals of the lamp. The disadvantage of this battery 
 is that the acidulated water in the porous pot must be changed 
 every two or three days and the solution of bichromate of 
 potash when it gets a greenish tint, a sign that it is exhausted. 
 
 The Daniell cell and its modifications, Callaud, Minotto, 
 &c., are not suitable for direct domestic lighting. The reason 
 is this. It is difficult even when making cells of great size to 
 obtain batteries which at their best have an output of more 
 than one watt (2 amperes and *5 volt). To supply only two 
 lamps of I *5 amperes and 12 volts, i*5X 12 X 2 = 36 watts 
 are required in the external circuit, which is at least 36 
 Daniells of large size, cumbersome, costly to buy and to 
 maintain, as they consume on open circuit. Zinc carbon 
 batteries, with acidulated or salt water, have too low an 
 F.M.F. and current. Leclanche batteries, which consume 
 
Domestic Electricity for Amateurs, 
 
 129 
 
 but little on open circuit, in addition to a small delivery, have 
 the still greater defect of polarising very rapidly on closed 
 current. 
 
 Indirect Lighting.— But although all these batteries 
 are unsatisfactory for lighting the lamps direct, some may be 
 used advantageously in conjunction with accumulators. 
 
 Accumulators thus used for domestic lighting act as 
 reservoirs and transformers. As reservoirs they enable a 
 small, but continuous current to be utilised for the production 
 of more powerful effects, intermittent and of less duration. 
 As transformers, by suitably coupling the elements, they 
 enable a greater tension to be obtained than that of the 
 primary current, together with a greater delivery at a pro- 
 portionate sacrifice of duration. With respect to lighting, this 
 sacrifice is unimportant, as if we assume on an average 4 hours’ 
 light per day, this leaves 20 hours per day for charging. It is 
 sufficient therefore if in 20 hours the electric source can supply 
 what we expend afterwards in four, to obtain the light. 
 
 K 
 
130 Domestic Elect7^icity for Amateurs. 
 
 The arrangements may be varied indefinitely, but we will 
 content ourselves with describing a few. Fig. 96 shows a 
 small stand with an electric lamp designed by M. Aboilard 
 for stationary or movable lighting. The lamp appears as an 
 ordinary oil-lamp, but the wick is replaced by a small lamp of 
 6 volts. 
 
 The base holds a cylindrical ebonite case of four com- 
 partments in which four small accumulators are coupled in 
 tension. The key seen on the left acts on a switch in order to 
 light or extinguish the lamp at will. The four small 
 
 Fig. 96. 
 
 accumulators give light only for a short time owing to their 
 small size, but they are only required when the lamp is 
 displaced. When the lamp is placed on the stand it is in 
 contact with four other accumulators of larger size arranged in a 
 
Domestic Electricity for A mateurs. 1 3 1 
 
 second ebonite case forming the column in the middle of the 
 table. These accumulators assist the first and together give six 
 hours’ light. 
 
 The lower compartments of the stand hold the charging 
 battery composed of 16 sulphate of copper elements in series 
 and small enough to go into a space 16 inches square and 
 9 inches high. These elements are maintained by adding water 
 _and sulphate of copper crystals and letting the water, charged 
 by the action of the elements with sulphate of zinc, run out 
 from time to time. 
 
 Fig. 97. 
 
 A movable lamp for lighting carriages, which is shown in 
 Fig. 97, has also been used. Owing to a white-metal lining 
 making a reflector, the incandescent lamp fed by three accumu- 
 lators in series gives a powerful light. 
 
 The case holding it is only 9 inches high, and it can easily 
 
 K 2 
 
132 Domestic Electricity for Amateurs, 
 
 be placed under the coachman’s seat When the carriage is 
 put up the accumulators are charged by means of sulphate of 
 copper batteries. Three to four elements must be reckoned 
 for each accumulator. 
 
 Fig. 98 represents some elegant and ingenious arrange- 
 ments, also worked by accumulators of various sizes. No. i 
 is a watch-stand very useful at night It is about 3J inches 
 
 Fig. 98. 
 
 high, 2 \ broad, and long. It holds two small accumulators 
 in series which light a tiny incandescent lamp a quarter of an 
 inch in diameter, placed below the watch in a shell reflector. 
 Awaking at night and wanting to know the time, all that is 
 necessary is to touch the switch on the watch-stand, when 
 the lamp glows and throws the light on the dial of the watch. 
 It not only shows the time, but also lights up the whole room. 
 
Domestic Electricity for Amateurs. 
 
 133 
 
 No. 2 is a travelling bag carried across the shoulders, holding 
 two accumulators, and weighing two pounds. It lights a 
 small three-candle lamp which may be fixed in the button- 
 hole of the coat. No. 3 is another travelling bag accumulator 
 of greater size, for more extended journeys. Under the head- 
 ing of Recreations, we will mention electric jewels. 
 
 These small lamps may be used for going down into the 
 cellars, seeing the time at night, consulting the thermometer, 
 &c. A small Plante accumu- 
 lator may also be used to 
 make a platinum wire glow 
 and set light to a candle or 
 stove as shown in Fig. 99. 
 
 Three small Callaud cells 
 3 inches high will maintain 
 the accumulator. 
 
 In all these applications 
 we have always supposed 
 that the charging battery 
 has a number of elements 
 in tension sufficient to charge the accumulators without 
 changing their coupling. 
 
 If this is not the case the accumulators must be coupled 
 up in quantity to charge them, and in tension to discharge 
 them. 
 
 A Plante commutator moved by hand, as described on 
 page 109, may be used, or the Plante- Hospitalier automatic 
 coupler, represented by Fig. 100. 
 
 The apparatus is intended without any special manoeuvre 
 — beyond switching in or out the lamp or lamps fed by 
 the accumulators — to automatically effect the coupling in 
 quantity to the charging battery and the coupling in tension 
 to the lamps, and to change the accumulators again directly 
 the lamps are put out. It consists of a wooden board carry- 
 ing a certain number of mercury cups joined to terminals by 
 copper strips ; into the cups are plunged jockeys suspended 
 from a horizontal axis turning on pivots. 
 
 The apparatus represented in Fig. 100 is arranged for three 
 
134 
 
 Domestic Electricity for Amatetirs. 
 
 accumulators, the terminals being ten in number, viz. two 
 for the charging circuit ; two for the external circuit, includ- 
 ing the lamp and contact-breaker ; three terminals for the 
 
 Fig. ioo. 
 
 positive poles of the three accumulators A, B, C ; three 
 terminals for the negative poles of the three accumulators 
 A, B, C. 
 
 In the ordinary position, the lamps being out, the plates are 
 in the position as shown in Fig. lOO, that is to say, in the 
 charging position ; all the positive poles of the accumulators 
 communicate with the positive pole of the charging battery, 
 and all the negative poles of the accumulators with the 
 negative pole of the battery. When the circuit to the lamp is 
 closed the current passes through an electro-magnet having 
 two windings, the one fine and long, the other short and 
 thick. The magnet becoming active attracts an armature 
 which swings the axis carrying the jockeys, plunges them 
 into other cups, and changes the coupling, insulates the 
 charging battery from the circuit, and couples the accumu- 
 lators in tension. 
 
 If the magnet had only one wire, the coupling would be 
 effected as before, but the lamp would not light, the resistance 
 
Domestic Electricity for Amateurs, 135 
 
 of the magnet wire weakening the current ; but the moment 
 the motion of the magnet is nearly ended the thick wire is 
 shunted into circuit, its resistance being almost nothing ; but the 
 magnetism due to the current in the thick coil being powerful 
 enough to maintain the armature in its position, keeps the 
 accumulators coupled in series on the lamps. When the 
 lamp is switched out, no current circulating on the magnet, 
 the jockeys fall back and recouple the accumulators in 
 quantity on the charging battery. The couplings are there- 
 fore effected automatically without troubling about a com- 
 mutator as is necessary with an apparatus worked by hand. 
 
 The foregoing relates principally to the uses that have been 
 made of primary batteries and accumulators in France, where 
 the general tendency seems to be in favour of the Trouve 
 form of single fluid bichromate battery for lighting direct, 
 and the use of constant batteries of low efficiency in con- 
 junction with secondary batteries or accumulators for the 
 indirect mode. In England, however, much greater advances 
 have been made, and the general tendency seems rather to 
 be in favour of modifications of the Bunsen, zinc-carbon, 
 nitric acid battery. Such batteries as the Goad, Emmens, 
 Holmes, Noad, and Ross are well known here, and some of 
 them much used. The Goad battery is a double fluid cell 
 with a bichromate and nitric acid solution, but it does not 
 appear to be any great improvement on other and older 
 forms, and has not been much employed. 
 
 The Emmens battery is a really practical thing, and has 
 done good work. The large cell is made of earthenware, 
 with a wooden frame round the top, in which are the terminals, 
 the contacts being made with mercury cups. The outer solu- 
 tion, in which are two zincs, is dilute sulphuric acid, the inner 
 solution, which is kept a secret by the inventor, and called 
 by him “chromozone,” is a very efficient depolariser; the 
 porous pot is about 12 by 10 by 2 inches, and is of very 
 porous material, and there are two carbons in each pot. 
 The single-pot cell, with external measurements of 13 by 
 12 by 5 inches, has an E.M.F. of over two volts, and an 
 internal resistance of O' 02 ohms; it can furnish continuously 
 
136 Domestic Electricity for Amateurs, 
 
 in useful work a current of 10 amperes for twenty-four hours, 
 extended over a week if necessary. This battery has been 
 much used for electric lighting, both for public and domestic 
 purposes, and the working cost with Swan lamps of high 
 efficiency comes out about equal to gas at Ss. per 1000 cubic 
 feet. 
 
 The Holmes battery is made in cells of about the same 
 capacity, and generally in wooden boxes of eight cells. The 
 outer solution is acidulated water, one in fifteen, and the 
 inner solution is nitrate of soda and sulphuric acid. There 
 are two zincs in each cell, and two carbons in each porous 
 pot. The constants are E = 1*85, R = 0*025. One 8-cell 
 battery will run sixteen lamps of 10 volts and i ampere, 
 or eight lamps of 10 volts and 2 amperes for twelve or 
 thirteen hours, either continuously or extended over three 
 or four days. The porous pots and the outside cells are 
 all connected to a common tube, and by an ingenious 
 siphon arrangement each battery of eight cells can be 
 charged in two operations in about ten ^minutes. The con- 
 nections never want touching, except to take out the zincs to 
 amalgamate them, or replace them. With ordinary work 
 they will last from six weeks to two months ; that is to say, 
 when an average current of 20 amperes for four hours per 
 day is taken out of them. The working cost with Swan 
 lamps at a high efficiency is about equal to gas at ys. per 1000 
 cubic feet, and a very great number of installations are now 
 running worked by these batteries, with great satisfaction to 
 the consumer. The efficiency of the battery is very good, 
 about 60 per cent, of the theoretical value of the zinc being 
 obtained in the lamps. 
 
 The Noad battery is a carbon and iron battery with nitric 
 acid, but no practical work has yet been done with it. 
 
 The Ross battery, like the Holmes, has a very ingenious 
 arrangement for charging all the cells, both inner and outer, at 
 one operation, but although this battery has been much 
 exhibited, we have heard of very little practical work from it. 
 
 There are amateurs willing to go to the expense of a small 
 electric lighting installation, seeing the special advantages of 
 
Domestic Electricity for Amateurs. 137 
 
 the light, but who are, with reason, afraid of the daily trouble 
 and attention required by most batteries. Give them an 
 installation capable of working properly without undue 
 personal trouble, and numbers of people will adopt the light. 
 In such cases economy is a secondary consideration ; but 
 simplicity, easy manipulation, and absolute certainty are 
 paramount. 
 
 Domestic electric lighting by means of primary batteries 
 is not, and cannot be, economical, but the cost is not suffi- 
 ciently high to render it prohibitive. 
 
 It suffices to show that it is possible and practicable to 
 tempt the amateur, but we cannot at present expect to see it 
 become general, and our only object is to point out the best 
 known means of obtaining a practical result on a comparatively 
 small scale, and as a luxury. 
 
138 
 
 Domestic Electricity for Amateurs. 
 
 CHAPTER IX. 
 
 ELECTRIC MOTORS. 
 
 The facility with which electrical energy may be transformed 
 into mechanical work, the neatness, elegance, lightness, ease 
 of starting and stopping of electric motors, has seduced many 
 inventors.. But, unfortunately, as with lighting, the difficulties 
 met with do not arise from the motor itself, but from the 
 electrical source required to work it. 
 
 There are, nevertheless, cases where, for small intermittent 
 purposes, it is convenient to use electric motors fed by batteries 
 direct, or, as previously explained, through the intermediary 
 of accumulators. 
 
 These small motors may be very useful in special cases, 
 which we will presently rapidly glance at, but we will com- 
 mence by briefly explaining the phenomena on which they 
 are based. 
 
 Magnetic Actions of the Electric Current. — Elec- 
 trical and magnetic phenomena are closely allied to each 
 other, as was first demonstrated by Oersted in 1820, when he 
 showed the action of an electric current on a magnetised 
 needle. A little later Ampere pointed out a rule, named 
 after him, to determine in each case the relative action of a 
 current and of a magnet. This rule itself is nothing more 
 than a consequence of indications furnished by the magnetic 
 figures. 
 
 If a thin card or glass plate be placed over a magnet and 
 iron filings are dusted on this plate, it will be seen that the 
 filings take certain positions, and trace certain lines which 
 Faraday called the magnetic “ lines of force,” the whole being 
 termed a magnetic figure. 
 
Domestic Electricity for Amateurs, 139 
 
 * The shape of the figure varies with that of the magnet, its 
 relative position to the plate, &c. The whole space under 
 the influence of this magnet constitutes the magnetic field, 
 characterised by the presence of lines of force, the study of 
 which is most important, when considering the laws of electro- 
 magnetic actions, and of induction. It is convenient, in order 
 to study these figures, to fix them, so as to be able to keep 
 them. 
 
 Fig. 1 01 shows how these figures may be fixed. The 
 plate is covered with gum, allowed to dry before being 
 
 Fig. ioi. 
 
 placed over the magnet ; the surface is sprinkled with soft 
 iron filings by means of a small sieve, and when the curves 
 are well developed, which will be assisted by gently tapping 
 the plate, a spray of water is gently thrown on its surface, or 
 better still, a jet of steam may be allowed to play on the 
 surface. The gum softens, holds the filings without the 
 particles changing position, and when the gum is dry again, 
 the magnet is withdrawn, the magnetic figure remaining 
 fixed. 
 
140 Domestic Electricity for Amateurs. 
 
 Thus a natural representation of the magnetic field pro- 
 duced by the magnet on the glass plate or sheet of paper is 
 obtained. The number of these lines or their density is at 
 every point proportional to the intensity of the field, the 
 curves traced indicate the direction. To complete the defini- 
 tion of the field the direction of these lines of force must be 
 determined. This direction is by definition and convention 
 taken to be the direction in which the north-seeking pole of a 
 magnetised needle displaces itself when free to move in the 
 field. From this definition it follows that the lines of force 
 start out from the north pole of a magnet and re-enter at the 
 south pole, since the north pole of the magnet repels the north 
 pole of the needle, and the south pole of the magnet attracts 
 the north pole of the needle. 
 
 Faraday discovered two physical properties of the lines of 
 force, which the magnetic figures clearly prove : (i) The lines 
 of force tend to shorten themselves ; (2) two parallel lines of 
 force in the same direction repel each other. 
 
 These two actions explain the curved shape which the 
 lines of force take between the two poles of a magnet ; they 
 are in equilibrium when their tendency to shorten is compen- 
 sated by their mutual repulsion. 
 
 When a magnetised needle is placed in a magnetic field, 
 by virtue of the tendency of the lines of force to shorten, the 
 needle places itself in the direction of the lines of force of the 
 field, which enter through the south pole of the needle and go 
 out through the north pole. This explains the direction 
 taken by a magnetised needle placed in a magnetic field. 
 
 It is by virtue of the same action that an electric current 
 acts on a magnetised needle. In fact, the space which sur- 
 rounds a conductor traversed by an electric current is equally 
 full of lines of force similar to those produced by a permanent 
 magnet. 
 
 In the case of a straight conductor, these lines of force are 
 parallel circles, the centres of which are in the conductor 
 itself and the plane of the circles is at right angles to the 
 conductor. The direction of these lines of force is given by 
 the following rule : — If a conductor be looked at from the end 
 
Domestic Electricity for Amateurs, 14 1 
 
 where the current enters, the direction of the lines of force will 
 be that of the hands of a watch. These lines of force possess 
 the same properties as magnetic lines of| force ; they differ, 
 however, in an essential point ; while magnetic lines of force 
 are always in existence in the field of the magnet without 
 other expenditure of energy than that necessary to originally 
 provoke the magnetism, lines of force due to electric currents 
 begin and end with the currents ; they can only exist when 
 a certain quantity of electrical energy is expended in the 
 conductor which they surround. 
 
 Principle of Electro-motors. — It will now be easy, 
 if the foregoing has been well understood, to explain the 
 principle of action of an electro-motor. 
 
 An electro-motor always comprises three essentials : a 
 permanent or electro-magnet producing the field ; a coil, 
 which traversed by a current also produces a field ; a commu- 
 tator or collector to distribute the current in the coil. 
 
 Every time a current passes through the coil, its lines of 
 force react on the field. If the bobbin be movable and the 
 field fixed, the former will be displaced to satisfy the mutual 
 attractions and repulsions of the lines of force and tend to take 
 up a position of equilibrium. If at the moment it arrives at 
 this position we reverse the current in the coil by means of 
 the commutator, we reverse the reciprocal action of the field 
 and the bobbin, the attractions change into repulsions, and 
 inversely, the coil tends to take a new position of equilibrium 
 different from the first. When it arrives at this second position 
 we again reverse the current, the directive force again changes, 
 and so on continuously. A series of motions of the coil 
 towards two positions of equilibrium is thus produced, which 
 it cannot retain owing to the successive reversals of the 
 current. Give the coil a suitable shape and arrange it in such 
 a way that the movements to its positions of equilibrium give 
 it a rotation of 180° round the axis which supports it, and we 
 have a rotary motor. The reversals may in this case be very 
 rapid, up to even 200 or 300 times a second. Practically, 
 small motors make at least 1800 revolutions per minute, or 
 30 revolutions and 60 reversals per second. 
 
142 
 
 Domestic Electricity for Amateurs. 
 
 In the large size motors the bobbins are divided into 
 sections and the commutator effects the change of direction 
 of the current in the bobbin no longer on the entire wire, but 
 section by section ; this is a continuous commutation, the 
 variation taking place only in or even -^^5 of the coil at 
 
 once, so that the current remains practically continuous, the 
 dead point is suppressed, the .action is more regular, and the 
 efficiency higher. 
 
 Small Motors. — The best continuous-current generators 
 are therefore, in principle, the best electro-motors. 
 
 But if small forces are to be produced, not exceeding 
 25 to 30 foot-pounds per second, for example, the problem 
 becomes very different. 
 
 The Gramme and Siemens rings become difficult of con- 
 struction and costly when their dimensions are small. It is 
 somewhat like the difference between a large clock and a 
 small watch. It is therefore necessary to make some sacrifice 
 in the efficiency of the apparatus to produce a simple and 
 cheap motor in order that its use may become general. 
 
 All constructors who have studied this question have 
 returned to the primitive Siemens armature, and we find it 
 more or less modified in most of the small motors at present 
 in use. 
 
 The Siemens coil consists of a soft iron cylinder hollowed 
 out by two longitudinal grooves, which gives its section the 
 form of an H. In this groove an insulated wire is wrapped, 
 the ends of which are joined to the two plates of the commu- 
 tator. The coil thus constructed is placed in a field formed by 
 a permanent or electro-magnet. Under the action of the cur- 
 rents, alternately reversed, which traverse it, it revolves rapidly. 
 
 In Deprez’s motor. Fig. 102, the field is formed by a 
 horseshoe magnet, and the coil is placed longitudinally 
 between the arms of the magnet, which renders the motor 
 lighter and more compact. The current is brought to the 
 commutator by two brushes of thin brass wire, as in the 
 Gramme machine. The current passing through the coil is 
 changed in direction every half turn. The brushes are fixed 
 to a support turning round the axis of the coil. 
 
Domestic Electricity for Amateurs. 143 
 
 The lead of the brushes and the speed of the motor may 
 thus be varied according to the work it has to do. With a 
 magnet weighing about 4 lbs. and an armature weighing 
 about I lb., the weight of the complete motor does not reach 
 9 lbs. At a speed of 3000 revolutions per minute, it de- 
 velops 184 lbs. per second, with eight flat Bunsen elements. 
 
 Fig. 102. 
 
 When the speed becomes too great, a small spring, in fixed 
 communication at one end with one of the ends of the coil, 
 and pressing by its other end on one of the commutator plates, 
 flies back, by the effect of the centrifugal force. The circuit 
 is broken and remains open until the speed becomes normal. 
 Practically the breaking and making of the circuit takes place 
 quickly enough to prevent the speed varying from the normal 
 t>y 
 
 Trouve’s motor also consists of a Siemens armatuf^ with 
 poles slightly excentric, turning between the arms of an 
 electro-magnet in series with the armature. 
 
 Fig. 103 represents Trouve’s motor applied to an ordinary 
 sewing machine. The motor is fixed vertically. The shaft 
 carries a pulley with a rubber tyre which presses against 
 the fly-wheel of the machine and thus communicates the 
 motion. The difference between the diameters being great 
 
144 
 
 Domestic Electricity for Amateurs. 
 
 the motor may run at a great speed, which warrants its small 
 dimensions. The pressure of the pulley on the fly-wheel is 
 regulated by means of a spring. It is easy to disconnect the 
 sewing machine from the motor by moving a lever which 
 
 Fig. 103. 
 
 moves the motor pulley away from the fly-wheel. The band 
 is then replaced and the machine can be worked by the 
 treadle, which is very convenient if accumulators are used, 
 which, by negligence or any other cause, may be exhausted. 
 Stopping and starting the machine is very simple. By 
 pressing the pedal two actions are produced : the first sends 
 the current into the apparatus, the second causes a graduated 
 strain on a chain composed of a number of silver links intro- 
 duced in the circuit. More or less strain exercised on the 
 chain reduces or increases the resistance. This application of 
 microphonic contacts is due to Reynier, and provides a simple 
 arrangement to regulate instantaneously and at will the 
 speed of the machine. 
 
 The Griscom motor. Fig. 104, for small work, is about 
 4 inches long and weighs under 3 lbs. Nevertheless, at a 
 speed of 5000 revolutions per minute, it can give out 20 to 25 
 foot-pounds per second. The Siemens H armature is used, 
 and revolves in a magnetic field formed by a ring-shaped 
 
Domestic Electricity for Amateurs, 145 
 
 magnet with consequent poles. The armature is entirely- 
 inclosed by the field-magnet which protects it. The armature 
 and field-magnet are of malleable castings, the coercive force of 
 which is as low as that of soft iron. Thus all the parts may 
 be cast, making their manufacture very cheap. 
 
 Fig, 104. 
 
 The apparatus is easily applied to any existing sewing 
 machine ; a small slotted support and a wing-nut on the 
 lower part of the motor are all that are required. 
 
 With this motor a bichromate of potash battery of six 
 elements is generally supplied. 
 
 The speed of the motor is regulated by plunging more or 
 less of the electrodes into the liquid by means of a pedal 
 placed on the side of the case containing the cells ; a single 
 charge of the battery is said to be sufficient to do 500 to 1000 
 yards of sewing, either in a fortnight or in six months at 
 irregular intervals. This is a veritable domestic application, 
 
 L 
 
146 Domestic Electricity for Amateurs, 
 
 if the inevitable recharging of the battery be attended to when 
 it has supplied the work it is capable of producing. 
 
 When power exceeding 25 to 30 foot-pouixis per second 
 is required, continuous-current machines are more regular, 
 lighter, and cheaper motors than those of total reversion of 
 the current, founded on the principle of the Siemens H 
 armature. 
 
 To obtain a solid, light, and compact motor. Gramme has 
 modified his dynamo machine to the cylindrical motor re- 
 presented in Fig. 105. Its essential parts of course are as 
 
 Fig. 105. 
 
 usual the field-magnets, the ring armature, and the commu- 
 tator, but the whole is neatly arranged and well-protected by 
 a covering of sheet brass ; Fig. 105 shows a part of this brass 
 covering cut away, enabling the internal arrangements to be 
 seen. They may be made in all sizes from 10 foot-pounds per 
 second to 2 or 3 horse-power. 
 
 Ayrton and Perry’s Motor. — Owing to theoretical 
 considerations which we cannot go into here, Professors 
 Ayrton and Perry have shown that dynamos should not have 
 the sarnie proportions existing between their different parts, 
 when intended to act as generators as when intended for 
 motors. 
 
 A generating dynamo should have massive inductors or 
 
Domestic Electricity for Amateurs. 147 
 
 field-magnets, so as to form an intense magnetic field, while 
 in a dynamo machine acting as motor it is preferable to have 
 a very large armature and a small field-magnet. It is there- 
 fore necessary to reverse the usual order of things, and make 
 a motor as shown in Figs. 106 and 107, which may be defined 
 
 Fig. ic6 
 
 as a reversed Pacinotti-Gramme machine with movable 
 field-magnet and fixed armature. The field-magnet, re- 
 presented separately at F, Fig. 107, is nothing else than a 
 Siemens H armature, revolving inside a Pacinotti ring, 
 represented by A ; the different sections of this ring are 
 
 L 2 
 
148 Domestic Electricity for Amateurs, 
 
 joined to a fixed collector, flat or circular ; the field-magnet 
 in revolving moves with it two brushes which press on the 
 collector and make the commutation. In motors intended to 
 be controlled by hand, boat motors, domestic motors, &c., the 
 speed is regulated and the direction of rotation is changed by 
 altering the lead of the brushes by means of a lever. 
 
 The smallest type of Ayrton and Perry motor weighs 
 about 34 lbs., and is constructed to supply an average work 
 of horse-power, that is to say, about 160 foot-pounds per. 
 second. These motors, according to the E.M.F. and current 
 at disposal, are made of three types, requiring 25, 50, or 100 
 volts at the terminals to act normally. 
 
 25 Volt Type . — At 1800 revolutions per minute, it pro- 
 duces 0*3 horse-power, with 22*4 volts at the terminals, and a 
 current of 25 amperes. The efficiency, that is to say, the 
 proportion between the mechanical work available on the 
 motor shaft measured by brake, to the electrical energy 
 between the terminals, is 39 per cent. 
 
 50 Volt Type . — At 2000 revolutions per minute, it pro- 
 duces 0*33 horse-power, with 48 volts at the terminals, and a 
 current of 14 * 2 amperes. The efficiency is 36 per cent. 
 
 100 Volt Type . — At 2100 revolutions per minute, it 
 produces 0*35 horse-power, with 98 volts at the terminals, 
 and a current of 6*i amperes. The efficiency is 38 per 
 cent. 
 
 From" these figures it will be seen that the efficiency of 
 small motors is very low ; in fact, it is necessary that the 
 work produced reach one horse-power for the motor to trans- 
 form into work 50 per cent, of the electrical energy absorbed. 
 To give an efficiency of 60 to 70 per cent, it is necessary that 
 the motor produce at least three or four horse-power. 
 
 The figures which we have given enable the number of 
 primary or secondary cells necessary to work one of these 
 motors at its normal speed to be readily ascertained. 
 
 It is necessary to know what difference of potential is 
 available at the terminals of the element at disposal when it 
 is made to deliver the number of amperes required , by the 
 motor. This difference of potential available at the terminals 
 
Domestic Electricity for Amateurs, 
 
 149 
 
 must not be confounded with the E.M.F. of the cell ; it is 
 always less, and may even be only half the E.M.F. 
 
 Let us assume, for example, that we have an accumulator 
 capable of delivering 15 amperes, with a difference of 
 potential available at the terminals of i * 5 volts. 
 
 This accumulator may work the 50 volt type, requiring 
 only 14*2 amperes. The number of cells in series required 
 will be 
 
 50 
 
 P5 = 33 - 3 . 
 
 Therefore, 34 cells in series must be used. If, on the 
 contrary, we use accumulators of larger dimensions, capable 
 of supplying 25 amperes, with the same useful difference of 
 potential, 1*5 volts, the 25-volt type of motor may be used. 
 The number of accumulators to be coupled in series will be 
 found to be reduced to 
 
 If, on the other hand, batteries incapable of delivering 
 more than 6* i amperes are only available, the lOO-volt motor 
 must be chosen, and the number of elements in series must 
 not be less than 
 
 9^ 
 
 1-5 
 
 = 65*3 elements. 
 
 The number of elements varies inversely as the current, 
 but it will be seen that the product of the current into the 
 number of elements is constant, as is also the work itself, 
 which is in conformity with the principle of the conservation 
 of energy. 
 
 Reversibility of Dynamo-Electric Machines.— 
 
 Every mechanical generator of electrical energy may be used 
 as a motor, and vice versa, by virtue of the principle of reversi- 
 bility. Thus, a most instructive and interesting experiment 
 may be made by means of a hand Gramme machine and a 
 Plante accumulator (Fig. 108). The machine when driven by 
 hand, expends mechanical energy, and produces electrical 
 energy which is stored in the accumulator in the form of 
 
1 50 Domestic Electricity for Amateurs. 
 
 chemical energy by reducing one of the lead plates and 
 peroxidising the other. 
 
 If the charging current is then stopped, and the plates 
 left closed on the circuit of the machine, the substances pre- 
 viously separated combine, producing electrical energy, which 
 passing through the machine, produces mechanical energy by 
 putting it in motion. This is one of the most beautiful 
 
 Fig. 108. 
 
 demonstrations of the unity of physical forces and their 
 mutual transformations. The practical consequence is that 
 one and the same machine may act alternately as generator 
 and motor, according as it is supplied with power or electricity 
 — a most important consequence from the practical point of 
 
 view, 
 
Domestic Electricity for Amateurs, 
 
 CHAPTER X. 
 
 ELECTRICAL LOCOMOTION. 
 
 Although electrical locomotion has so far not been abso- 
 lutely perfected, many attempts, some crowned with success 
 and capable of practical application in special cases, prove 
 that the actual realisation is not far distant. Each improve- 
 ment in batteries or accumulators, every perfection given to 
 small motors by decreasing their weight for a given power, 
 and increasing their efficiency, are steps in advance. It is, 
 therefore, not without interest to review the results obtained 
 up to date, if only to show what has been accomplished and 
 what has still to be attained. 
 
 We shall not refer here to aerial locomotion, although 
 this subject has within the last month or two made wonderful 
 advances ; a balloon fitted with a propeller driven by batteries 
 and an electro-motor, having actually ascended under perfect 
 command and having made a trip of several miles, was 
 brought back to the starting point. This subject is, however, 
 hardly within the scope of the present work, and we shall 
 confine ourselves to land and water locomotion. 
 
 Land Locomotion. 
 
 The dream of amateur electricians is to possess a vehicle 
 driven by electricity. What is more charming than to have 
 one at disposal, started and stopped instantaneously by simply 
 turning a switch without further trouble ? 
 
 Unfortunately the cup is still far from the lip, and this 
 dream of all, has up to the present not been practically 
 realised. The principal difficulty always is, as with lighting, 
 
152 Domestic Electricity for Amateurs. 
 
 and as with small fixed motors, the difficulty of producing 
 easily and conveniently the necessary electrical energy. But 
 here the difficulty is increased by the fact of the mode of 
 employment itself ; the vehicle must carry the source with it ; 
 it must, therefore, at the same time be powerful and light in 
 order not to expend all the work which it produces in 
 drawing its own weight and leave nothing available for useful 
 work, that is to say to move the weight of the travellers. 
 The struggle between batteries and accumulators is eager, and 
 it is still difficult to give an opinion. Both have their advan- 
 tages and inconveniences. 
 
 Accumulators are in existence, which can supply a horse- 
 power-hour of electrical energy per 80 lbs. of weight, but 
 Messrs. Renard and Krebs have, it appears, recently combined 
 an exceedingly light battery which is kept secret, capable of 
 giving this horsepower-hour from a weight of less than 40 lbs. 
 Accumulators may be recharged by a machine, which is an 
 advantage and a saving when the motive power is available 
 and a disadvantage in the contrary case. On the other hand, 
 batteries are very costly and require so much attention every 
 time they are to be used. 
 
 Perhaps, after all, batteries might be made serviceable for 
 the purpose if we could feed them en route as locomotives 
 are fed with water. What renders batteries so heavy is the 
 enormous quantity of solution which must be carried to insure 
 prolonged action. Water in this case is ballast, and a very 
 inconvenient ballast. Instead of carrying the whole of the 
 solution all the way, if we could so arrange that we only 
 carry a part and then obtain fresh en route as required, in the 
 same way as a locomotive engine is watered, it would be a 
 great advance. We should then require on the vehicle only 
 the supply of zinc and active material necessary for the whole 
 journey. Two kinds of batteries may be arranged for use in 
 this way. One is a zinc carbon battery with a solution of 
 chromic salt, which may be dissolved as required, letting the 
 exhausted liquor run off from time to time. 
 
 The second battery is a kind of zinc and peroxide of lead 
 accumulator, in which the space required for the liquid is 
 
Domestic Electricity for Amateurs. 153 
 
 very limited ; the latter may be supplied as required and the 
 solution which, after use, is composed almost exclusively of 
 sulphate of zinc, may be thrown away. During prolonged 
 stoppages the battery may be left dry, and thus local action 
 on the zincs is avoided. 
 
 This combination, complicated as it may appear, has its 
 advantages: the E.M.F. will be very high, 2*35 volts, and 
 constant as long as the peroxide of lead plates are not ex- 
 hausted, and then they may be replaced. The equivalent of 
 
 Fig. 109. 
 
 zinc being less than that of lead, the negative plates may be 
 lighter in the proportion of one to three for the same quantity 
 of electricity. Finally, the renewal of the liquid enables the 
 
154 
 
 Domestic Electricity for Amateurs. 
 
 positive plate to be more completely exhausted, and to obtain 
 for a given weight a greater quantity of electricity and to 
 increase in fact the storage capacity. 
 
 As regards what has been already done in the direction of 
 electric locomotion by land, we shall not refer to the electric 
 rail and tramways in existence, as this hardly comes within 
 the province of amateurs, but for them the electric tricycle 
 represented in Fig. 109 will have more interest. This was 
 used in London in 1882 by Professor Ayrton. The energy 
 is furnished by ten Faure-Sellon-Volckmar accumulators of a 
 special type, placed under the seat. These accumulators 
 work an Ayrton and Perry electro-motor weighing 40 lbs., 
 and giving an effective work of 180 foot-pounds per second. 
 This motor drives one of the large wheels of the tricycle by 
 means of a pinion and cogged wheel on the axle of this wheel. 
 The rider has to his hand a commutator enabling him at will 
 to vary the number of accumulators in circuit according to 
 the nature of the ground and the speed required, also the 
 break and the steering gear. An am-meter and a volt-meter 
 indicate at any moment the electrical energy being expended. 
 Finally two Swan lamps act as side lights and illuminate the 
 measuring instruments. The result probably was not very 
 successful as, so far as we know, no other apparatus of this 
 type has been constructed since. But from this it must not 
 be concluded that the idea of small electric vehicles is 
 abandoned. Their study is being followed up by many 
 people, and there is no doubt that when this application 
 becomes more perfect and practical, very numerous purchasers 
 will be forthcoming. 
 
 Electric NaviCxAtion. 
 
 The idea of applying electricity to the propulsion of boats 
 is far from new. The invention of the electro-magnet demon- 
 strated the possibility of producing mechanical work by means 
 of an electric current. It was not difficult for electricians 
 fifty years ago to use the power of an electro-magnet to work 
 small electro-magnetic engines. The first attempts of Jacobi, 
 
Domestic Electricity for A mateurs. 155 
 
 Davidson, Henry, Ritchie, and Page, produced a number of 
 electro-motors which only required a cheap source of electricity 
 to find many useful applications. No great effort of in- 
 vention was necessary to understand that if a sufficiently 
 powerful battery could be placed in a boat, it would be 
 possible to work a motor which would effect the propulsion of 
 this vessel. This idea, one of the first amongst the numerous 
 applications of the electro-magnet, was first realised by 
 Professor Jacobi of St. Petersburg, who in 1838 constructed 
 an electric boat. Fig. 1 10 represents the primitive electro- 
 motor devised by Jacobi to propel his boat. Two series of 
 
 Fig. no. 
 
 horseshoe electro-magnets were fixed to solid wooden frames ; 
 between the poles of these electro-magnets revolved a sort of 
 wooden star carrying a number of straight electro-magnets. 
 
 By means of a revolving commutator, consisting of a series 
 of toothed wheels, the current was changed in direction at 
 regular intervals, the movable electro-magnets being first 
 attracted, then repelled, thus producing a continuous rotary 
 motion. 
 
 This magnetic engine was at first worked by a Daniell 
 battery of 320 cells of zinc and copper plates, each having a 
 surface of 36 square inches, excited by a solution of sulphuric 
 acid and sulphate of copper. This battery only gave a 
 maximum speed of mile per hour. 
 
 In the following year, 1839, the Daniell cells were replaced 
 
15 ^ Domestic Electricity for Amateurs. 
 
 by 64 Grove elements, the platinum plates of which had 36 
 square inches of surface. The boat, 28 feet long, broad, 
 and drawing 3 feet of water, was run on the Neva carrying 
 fourteen persons at a rate of 2J miles per hour. 
 
 Trouve’s Boat. — Trouve had the ingenious idea, in 
 order to render electric pleasure boating convenient and 
 
 practical without essentially altering the hull of the boat, to 
 place the motor on the top of the rudder and to communicate 
 the motion to the screw by means of an endless chain. Fig. 
 III. The battery consisted of two bichromate of potash 
 
Domestic Electricity for Amateurs. 157 
 
 windlass batteries of six elements each, which we have 
 previously described. These batteries take up a limited 
 space, and may be easily put on board a boat. The current 
 is conveyed to the motor by the two yoke lines, which are of 
 flexible wire, and contain also a switch to open and close the 
 circuit at will. The boat may therefore easily be steered at 
 will, and the speed regulated. The screw moving with the 
 rudder, of which it is part, gives the boat a list when the 
 rudder is hard over, and then the boat may be turned almost 
 in her own length. 
 
 The first boat thus fitted was tried on the Seine, near the 
 Pont Royal, on the 26th May, 1881. Fig. 112 represents this 
 experiment, in which a speed of about 2 miles per hour 
 against stream, and 5 miles with stream was reached. 
 
 Electric Boat with Accumulators. — The great 
 quantity of electrical energy which it is possible to store in 
 accumulators, and the power of expending this energy quickly 
 or slowly at will, gave the idea of using these remarkable 
 properties in pleasure boats. The first electric boat with 
 accumulators was constructed by Mr. A. Reckenzaun, en- 
 gineer of the Electrical Power Storage Company, of London, 
 and tried on the Thames on the 28th September, 1882. 
 Fig. 1 13 shows the boat under weigh ; Figs. 114 and 115 are 
 sections showing the principal arrangements. 
 
 The launch Electricity is built entirely of iron, its length 
 is nearly the same as the wooden boat of Jacobi. It holds 
 twelve persons ; the screw makes 350 revolutions per minute, 
 and the motor working it, 950. The accumulators, 45 in 
 number, weigh rather over 2 tons, and will give 4 horse-power 
 for 6 hours. 
 
 They are of the Faure-Sellon-Volckmar type, of a specially 
 compact manufacture for launch work ; each element contains 
 40 plates and weighs nearly 40 pounds. They are 10 inches 
 in depth and 8 inches high. There is room in the boat for 54 
 elements of this type, but only 45 were carried on the trial 
 trip. These accumulators will supply more than 30 amperes 
 for 9 hours, which corresponds for the 45 accumulators to a 
 total electrical energy — external and internal — of 36 horse- 
 
Fig. II2, 
 
 158 Domestic Electricity for Amateurs. 
 
 power-hours, of which it is possible to obtain usefully 20 to 24 
 or about 4 horse-power for 6 hours. 
 
 These accumulators work two dynamos of the Siemens 
 type furnished with reversing gear and regulators, so as to 
 
Fig. 1 13. 
 
 Domestic Electricity for Amateurs. 159 
 
 run the screw at will in either direction, and at any speed. 
 Either or both of these motors may be switched into circuit 
 
 at a time. On the first trip a speed of 8 miles per hour was 
 attained against the tide, in presence of a long line of 
 
i6o Domestic Electricity for Amateurs. 
 
 spectators massed on London Bridge, who watched this boat, 
 which, without steam or visible power, and even without a 
 visible helmsman, made its way against wind and tide. The 
 total E.M.F. of the accumulators was 96 volts, and during the 
 journey the current was maintained very 
 steady at 24 amperes in each machine. 
 Calculation shows that this corresponds 
 with an expenditure of electrical energy 
 of 3 • I horse-power. 
 
 The two Siemens machines work by 
 belts on to a counter-shaft above, fitted 
 with friction gear, enabling them to be 
 connected or disconnected at will. 
 
 A third belt works the screw-shaft. 
 Each of the dynamos is provided with 
 two pairs of brushes arranged opposite the collector, one pair 
 for going ahead, the other for going astern. 
 
 The accumulators arranged underneath the seats make a 
 perfect ballast, and leave the deck entirely free. It results, 
 therefrom, that a 36-foot electric launch is, as regards the 
 number of passengers that may be carried, and their con- 
 venience, equal to a steam launch 50 to 60 feet long ; all the 
 parts are accessible, and the launch is entirely free from 
 smoke, steam, cinders, and noise. 
 
 Considered from the point of view of comfort, the electric 
 launch is thus evidently perfection ; the cost and mainten- 
 ance is more than that of a steam launch, but it must not be 
 forgotten that expense is often in these cases a secondary 
 consideration. 
 
 For the application to become general on a river, it will 
 be necessary to erect charging stations where electricity may 
 be taken in, in the same way as at present coal is taken in. 
 
 In short, when the accumulators have been charged, they 
 keep their charge a long time, while the loss does not exceed 
 I per cent, per day ; they represent, therefore, an amount of 
 electricity always ready at a moment’s notice, while it is 
 impossible to start a steam launch under two or three hours’ 
 notice. Perhaps a system may even be invented whereby the 
 
Domestic Electricity for Amciteurs. 
 
 i6t 
 
 recharging of the accumulators may be effected free of cost 
 during long stoppages, either by using the wind or even by 
 using the stream of the river by means of floating wheels. 
 
 While we are speaking of new ideas, let us mention 
 another. Could not the great speed of electro-motors be 
 
 M 
 
i 62 
 
 Domestic Electricity for Amateurs, 
 
 used to supplant the screw by a hydraulic propeller worked 
 by a rotary pump ? The attempts made in this direction 
 have, if our information is correct, given encouraging results. 
 Would it not do to resume these trials with electro-motors, 
 the speed of which is particularly favourable to this applica- 
 tion ? The suppression of the screw would have considerable 
 advantages, especially where the draught of water is small 
 and where the impurities of the water, weeds, floating matter, 
 &c., expose the screw to continual danger. 
 
 As a matter of fact, electric navigation, like land loco- 
 motion, is still of small account when bichromate batteries 
 are used, or a great luxury with accumulators, but certainly a 
 great future may be predicted for it, when it is considered 
 that the experiments are of so recent a date, and taking into 
 account the surprises and progress that the future may have 
 in store. Awaiting the arrival of the electric launch as an 
 every-day thing, let us record their entry into the nautical 
 sporting world. 
 
 A race between two electric launches, the Electricityy 
 which we have described, and the Australia^ of a more recent 
 construction, and fitted with more perfect apparatus, has lately 
 taken place on the Thames. 
 
 As might be expected, the new boat won. When shall 
 we have “ electro-cycle ” races ? 
 
Domestic Electricity for Amateurs, 
 
 163 
 
 CHAPTER XL 
 
 ELECTROTYPING, PLATING, AND GILDING. 
 
 The discovery of the art of metallic deposition by means of 
 a current is well known, and we will content ourselves with 
 rapidly glancing at the more simple processes whereby the 
 amateur may obtain interesting results, either in the repro- 
 duction of medals and metallisation of small objects, or by 
 fine and adherent deposits of gold, silver, and nickel. 
 
 Electrotyping is the art of effecting a non-adherent 
 metallic deposit, thick enough that the metal deposited may 
 itself form a fresh object, and be capable of a separate 
 existence apart from the original mould, preserving its con- 
 figuration and dimensions. 
 
 The phenomenon of electro-chemical deposition is based 
 on an electrolytic action of the current, the principle of which 
 is the following : let us suppose, for the sake of example, that 
 we have a vat filled with a saturated solution of sulphate of 
 copper, in which two copper plates are plunged ; join these 
 two copper plates to the two poles of a Daniell cell ; the 
 passage of the current will effect the decomposition or elec- 
 trolyse the solution or electrolyte. The metal, which here is 
 copper, will be deposited on the plate fixed to the negative 
 pole of the battery or cathode, while the sulphuric acid, freed 
 by the decomposition, attacks the plate fixed to the positive 
 plate of the battery or anode, and dissolves it. If the action 
 is very regular, and the anode very pure, the weight of 
 copper deposited on the cathode will be equal to the weight of 
 copper dissolved from the anode, and will itself be proportional 
 to the quantity of electricity which has passed through the 
 
 M 2 
 
164 Domestic Electricity for Amateurs. 
 
 circuit. To obtain a good and regular deposit, called by 
 Smee “reguline,” certain relations between the composition 
 of the bath, the current, and the surfaces to be covered must 
 exist, and this we will presently more fully explain. 
 
 If we replace the copper plate by a suitable mould 
 rendered conducting, the electro-chemical deposition will 
 take place on this mould, and when the piece is separated 
 from the mould, it will be found to reproduce in hollows all 
 its reliefs, and vice versa. 
 
 We will now describe the moulds, the baths, and their 
 general management. 
 
 Moulds. — The substance originally used was plaster 
 of Paris, but as it is porous, it must be made impermeable. 
 At present moulds are made in stearine, wax, marine glue, 
 gelatine, indiarubber, and fusible alloys. When the moulds 
 are hollow, a metallic skeleton of platinum is arranged inter- 
 nally, joined to the anode, which serves to distribute the 
 current, and to equalise the deposition ; these wires are 
 covered with rubber, to prevent all contact, except where 
 required. Plante substituted lead wires for the platinum 
 wires used before then, which is an important saving. 
 
 When covering several pieces at once it is prudent to join 
 each of them to the negative pole by an iron or lead wire of a 
 size suitable to the piece ; this wire melts if an internal short 
 circuit takes place and then withdraws the piece automatically 
 from the circuit. 
 
 The moulds are given a metallic coating by means of pure 
 plumbago which must be applied to the mould with a plate 
 brush or soft polishing brush, wax requiring very soft brushes. 
 Metallising may also be effected by the wet process with a 
 solution of nitrate of silver painted upon the object in two or 
 three coats and reduced by a solution of phosphorus in bisul- 
 phide of carbon. This wet process is suitable for delicate 
 and intricate objects, laces, flowers, leaves, moss, lichens, 
 insects, &c. 
 
 Baths. — Whatever the work in hand may be, the bath is 
 always the same and is prepared as follows : — 
 
 A certain quantity of water is put into a jar to which 
 
Domestic Electricity for Amateurs. 165 
 
 8 to 10 parts in 100 of sulphuric acid are added in small 
 quantities, stirring continually ; afterwards as much sulphate 
 of copper is dissolved in the acidulated water as it will take 
 at the ordinary temperature, stirring continually ; it is always 
 used cold and must be maintained saturated by the addition 
 of crystals or suitable anodes. It should be put into jars of 
 clay, porcelain, glass, or hard brown earthenware or india- 
 rubber ; for large baths wooden vats may be used lined inside 
 with a thin coating of indiarubber, marine glue, or varnished 
 sheets of lead. Never line with iron, zinc, or tin. 
 
 Kate of Deposit — This may be varied within consider- 
 able limits without greatly affecting its quality. 
 
 In printing work, for instance, about i gramme of cop- 
 per per hour per square decimetre is deposited and the 
 operation lasts 24 hours, but the same deposit may be 
 obtained in 12 and even in 8 hours. A current of 2*6 am- 
 peres per square decimetre of surface to be covered gives a 
 magnificent deposit of 7 grammes per hour per square deci- 
 metre. An ampere-hour, that is to say, a current of one 
 ampere for one hour, passes 3600 coulombs of electricity, 
 and deposits i • 19 gramme of copper. These few figures 
 enable the current, the rate of deposit, and the duration of 
 the operation to be regulated, according to the surfaces to be 
 covered and the thickness desired. 
 
 General Management of the Baths and Currents. 
 — When the solution is too weak and the current too stronsf, 
 the deposit will be black ; when the solution is too concen- 
 trated and the current too weak, the deposit is crystalline. A 
 fine deposit of flexible metal called by Smee “ reguline ” will 
 be obtained under mean conditions. The stratification of the 
 liquid and the circulation which is produced in the interior of 
 the bath by the decomposition of the anode and the deposi- 
 tion on the cathode, produce long vertical lines. It is 
 necessary therefore to move the pieces about in the solution 
 as much as possible so as to keep the bath homogeneous. 
 Large baths have an advantage in this respect. A great 
 distance between the anodes and the cathodes produces a 
 more regular deposit ; this is especially necessary for small 
 
1 66 Do7nestic Electricity for Amateurs. 
 
 objects, but loss is thereby entailed in the quickness of the 
 deposit or a more powerful current is necessary. The same 
 bath maybe used for several objects, each joined to a separate 
 electric source, by using a single anode joined to all the 
 positive poles of the different sources. The surface of the 
 anode in general must be equal to the surface of the cathode ; 
 too small an anode impoverishes the solution, too great an 
 anode enriches it ; experiment in each case indicates whether 
 it is to one’s interest to produce one effect or the other. 
 
 Simple Apparatus for Amateurs. — A simple appa- 
 ratus, and moderate in price, may be made without difficulty 
 for covering with copper small plane surfaces or for the re- 
 production of medals or bas-reliefs of small size, by placing 
 the sulphate of copper solution in an earthenware or porcelain 
 jar, in the centre of which is a porous pot holding an amalga- 
 mated zinc and a solution of sulphuric acid and water of 2 or 
 3 in lOO. At the top of the zinc a brass rod is fixed, sup- 
 porting a circle of the same metal, the diameter of which is 
 between that of the containing vessel and that of the porous 
 pot ; from the brass circle the pieces are suspended in such a 
 manner that the parts to be covered are turned towards the 
 porous pot. 
 
 Two small horsehair bags filled with crystals of sulphate 
 of copper are suspended in the solution of sulphate of copper 
 to maintain its saturation. 
 
 Simple amateur baths are also constructed of indiarubber, 
 in the shape of a flat rectangular case, less fragile and easier 
 to move. 
 
 The size varies with the objects to be covered. 
 
 Thin Adhesive Deposits, or Electro-plating. 
 
 Thin adhesive deposits are at present obtained from all 
 the metals and on all the metals. We shall only refer to 
 those most important to the amateur, that is to say, the 
 deposition of gold, silver, or nickel, when the object is to 
 protect from atmospheric or other influences, or to beautify 
 certain articles. 
 
Domestic Electricity for Amateurs, 
 
 167 
 
 Good and lasting deposits are only obtained after a series 
 of most important operations of thorough cleansing, the object 
 of which is to prepare the metallic surface to receive the 
 deposit, and to insure as perfect an adhesion between the 
 two metals as possible. Too much stress cannot be laid 
 upon the necessity of this cleansing ; most failures may be 
 attributed to bad cleansing, in the same way as nearly all 
 failures in photography are due to defective cleaning of the 
 glass plate. 
 
 Cleaning^. — Whether the deposit is to be of gold, silver, 
 or nickel, the following are the operations to be performed to 
 obtain an adherent deposit, whether dull or bright. 
 
 1. Removal of Grease . — Warm the pieces before a slow fire 
 of charcoal, coke, or, better still, in a dull red stove. Delicate 
 or soldered articles should be boiled in a solution of caustic 
 potash dissolved in ten times its weight of water. 
 
 2. Scouring . — The scouring bath is composed of 100 parts 
 of plain water to 5 to 20 parts of sulphuric acid ; the articles 
 may generally be put in hot Leave them in the bath until 
 the surface turns to an ochre-red tint. The articles cleaned 
 of grease by potash should be washed and rinsed in water 
 before being scoured. 
 
 From this moment the articles must not be touched with 
 the hand ; copper or glass tongs must be used, and for very 
 small articles earthenware or porcelain strainers. 
 
 3. Spent Nitric Acid Bath . — This is nitric acid weakened 
 by previous use. The articles are left in until the red coat 
 disappears, so that after rinsing they show only a uniform 
 metallic tint Rinse thoroughly. 
 
 4. Strong Nitric Acid Bath . — The articles, well shaken 
 and drained, are put into a mixture of 
 
 The articles must only remain a few seconds in the bath 
 Avoid over-heating or using too cold a bath. Rinse thoroughly 
 with cold water. 
 
 Nitric acid of 36° Baume . 
 Chloride of sodium .. 
 Calcined soot (lampblack) 
 
 100 volumes. 
 I volume. 
 
 I „ 
 
1 68 , Domestic Electricity for A mateurs. 
 
 5. Strong Nitric Acid Bath^ to give a bright or dull 
 appearance , — For articles required to have, when finished, a 
 bright appearance, plunge for a second or two, moving them 
 rapidly about, in a cold bath of 
 
 Nitric acid 100 volumes. 
 
 Sulphuric acid .. • loo ,, 
 
 Common salt, about . . . . I volume. 
 
 Rinse quickly in water. 
 
 If a dull or “ mat ” appearance is desired, the bath is 
 composed of 
 
 Nitric acid 200 volumes. 
 
 Sulphuric acid 100 ,, 
 
 Sea salt i volume. 
 
 Sulphate of zinc i to 5 volumes. 
 
 The duration of immersion varies from 5 to 20 minutes, 
 according to the dulness desired. Wash with plenty of 
 water. The articles look earthy and disagreeable, which dis= 
 appears by plunging them for a moment into the brightening 
 bath and rinsing quickly. 
 
 6. Nitrate of Mercury Bath . — Plunge the cleaned articles 
 for a second or two into a bath of 
 
 Plain water 10 kilos. 
 
 Nitrate of mercury 10 grammes. 
 
 Sulphuric acid 20 ,, 
 
 Stir up before using. The bath should be richer in mercury 
 if the articles are heavy, less rich if light A badly cleaned 
 article comes out tinted in various shades, and without 
 metallic brightness. It is better to throw a spent bath away 
 than to strengthen it. After passing through the mercury, 
 the article must be rinsed and put at once into the plating 
 bath. 
 
 Gilding. — Small articles are gilded hot, large pieces cold. 
 
 Cold Cyanide of Gold and Potassmm Bath : — 
 
 Distilled water lo litres. 
 
 Pure cyanide of potassium 200 grammes. 
 
 Pure gold 100 ,, 
 
 The gold, transformed into chloride, is dissolved in 2 litres 
 of water, the cyanide in 8 litres ; mix the two solutions, and 
 
Domestic Electricity for Amateurs. 
 
 169 
 
 boil for half an hour. The richness of the bath is maintained 
 according to requirement by adding equal parts of cyanide of 
 potassium and chloride of gold, a few grammes at a time. If 
 the bath is too rich in gold, the deposit is blackish or deep 
 red ; if there is too much cyanide, the deposit is slow and 
 grey. The anode must be entirely submerged in the bath, 
 suspended by platinum wires, and withdrawn directly the 
 bath is not in action. 
 
 Hot Gold Bath. — Zinc, tin, lead, antimony, and the alloys 
 of those metals are better previously covered with copper. 
 The following are the formulae for the .other metals per 
 10 litres of distilled water : — 
 
 Silver, Copper, Bronze, Castings, 
 
 Alloys rich in Copper. Iron and Steel, 
 grammes. grammes. 
 
 Crystallised phosphate of soda . . . . 600 . . . . 500 
 
 Bisulphide of soda loo .. .. 125 
 
 Pure cyanide of potassium .. .. 10 .. .. 5 
 
 Pure gold transformed into chloride 10 .. .. 10 
 
 Dissolve the phosphate of soda hot in 8 litres of water, let 
 the chloride of gold cool in i litre of water, mix little by little 
 the second solution with the first, dissolve the cyanide and 
 bisulphide in i litre of water, and mix this last solution with 
 the other two. 
 
 The temperature of the bath may vary between 50° and 
 80° C. A few minutes are sufficient to produce a good 
 deposit; an anode of platinum is used ; the anode not sunk 
 deep into the bath gives a pale gold deposit ; deeply im- 
 mersed, it gives a red colour. The bath may be kept up by 
 successive additions of chloride of gold and cyanide of potas- 
 sium, but after long usage a red or green deposit is obtained, 
 according as it has been used most to gild copper or silver. 
 It is preferable to renew the bath instead of enriching it 
 
 Rapidity of Deposition. — In a bath holding i gr. of gold 
 per litre, about 30 centigrammes per hour per square deci- 
 metre may be deposited, but this average figure may vary 
 greatly. 
 
 Silvering. — For amateurs a bath of 10 gr. of silver per 
 litre is sufficient ; dissolve 1 50 gr. of nitrate of silver, equi- 
 
1 70 Domestic Electricity for Amateurs, 
 
 valent to 100 gr. of pure silver, in 10 litres of water, and add 
 250 gr. of pure cyanide of potassium. Stir up until com- 
 pletely dissolved, and filter. Silvering is generally done 
 cold, except for small articles. Iron, steel, zinc, lead, and 
 tin, previously coppered, silver better hot. The cleaned 
 articles are first put into the nitrate of mercury bath and 
 moved continually. When there is too much current the 
 pieces become grey and blacken, then gas is liberated. Use 
 anodes of platinum or of silver in cold baths. Old baths are 
 preferable to new baths. The baths are artificially aged by 
 adding i to 2 in 1000 of liquid ammonia. The silver baths 
 are kept up by adding equal parts of the silver salt and 
 cyanide of potassium. If the anode blackens, the bath is 
 poor in cyanide, and the deposit is too slow ; if it whitens, 
 there is too much cyanide, the deposit is rapid, but does not 
 adhere. The deposit is normal and regular when the anode 
 becomes grey when the current passes, and white again when 
 it ceases. 
 
 Nickeling. — Nickel is a white metal, little oxidisable, and 
 may be applied in coats of varying thickness to the other 
 metals, especially to iron, and to its derivatives, and to 
 copper. 
 
 The first attempts to nickel metals were due to Smee, and 
 afterwards to Becquerel. But Smee and Becquerel’s experi- 
 ments gave insufficient results, while Dr. Isaac Adams of 
 Boston was the first to make known a really practicable and 
 commercial process of depositing nickel. This was published 
 in 1869, and since then a great number of nickel-plating 
 works have been put up in the United States. The first 
 European nickel-plating factory was established in Paris by 
 Adams and Gaiffe, but a great deal of nickel-plating is now 
 done in London. 
 
 Nickel is much used to cover copper and its alloys, brass, 
 bronze, gun-metal and bell-metal ; also iron and its deriva- 
 tive, steel. Its application to the other metals is of little 
 importance, and necessitates operations and preparations as 
 long as they are tedious. 
 
 A vat and a battery are necessary to nickel-plate ; the 
 
Domestic Electricity for Amateurs, 1 7 1 
 
 vat to receive the bath and the articles to be covered ; the 
 battery to decompose the bath. 
 
 The Vat. — For amateurs the vat should be of glass, or, in 
 default, porcelain or earthenware may be used, or a case 
 lined inside with an impermeable gum. 
 
 The Bath. — The best nickel bath is prepared by dissolving 
 to saturation in hot distilled water, nickel sulphate and 
 ammonium free from oxides of alkalies and alkaline earthy 
 metals. The proportion of salt to dissolve is i part by 
 weight to 10 of water. Filter after cooling, when the bath is 
 ready for use. 
 
 The Battery. — A convenient battery for amateurs, but not 
 for industrial purposes, is the bichromate of potash bottle 
 battery. 
 
 Double fluid bichromate batteries, or the Lalande and 
 Chaperon, Holmes, or Emmens batteries are also suitable. 
 
 Preparation of the Bath. — When the bath is ready and 
 the battery set up, the wires from the latter are joined by 
 means of binding screws to two metallic bars resting on the 
 edge of the vat. The bar joined to the positive pole of the 
 battery supports, suspended from a copper hook, nickel- 
 plated, a plate of nickel constituting the soluble anode 
 which restores to the bath the metal deposited on the 
 cathode by the electrolytic action. From the other bar 
 (zinc or negative pole) the articles to be nickeled are sus- 
 pended. 
 
 Preparation of the Articles. — But before putting the 
 articles into the bath, they must undergo a series of neces- 
 sary operations if a good result is to be obtained. Nickel 
 being a hard metal, and difficult to burnish, it is advisable 
 that the articles should be well polished before being put into 
 the bath, if a nice polish of the deposited metal is to be 
 obtained. 
 
 Removal of Grease. — This is effected by scrubbing the 
 articles to be plated with brushes soaked in a hot solution of 
 whiting boiled in water and carbonate of soda. When the 
 pieces are 'perfectly freed from grease, they may be easily 
 and equally wetted with plain water. 
 
1 72 Domestic Electricity for Amateurs, 
 
 Scouring . — This is effected either by chemical or mecha- 
 nical means. 
 
 Copper and its alloys are cleaned well in a few seconds by 
 dipping in a bath composed of 10 parts of water by weight, 
 and I part of nitric acid. Or for rough articles a more 
 energetic bath may be used, consisting of 2 parts of water, 
 I part nitric acid, and i part sulphuric acid. Iron, steel, 
 and polished castings are cleaned in a bath of 100 parts of 
 water to i part of sulphuric acid. The articles should 
 remain in the cleaning bath till the whole surface is of a 
 uniform grey tint. They are then rubbed with powdered 
 pumice stone till the solid metal appears. Iron, steel, and 
 rough castings require a longer series of operations. These 
 metals are left for three or four hours in the cleaning bath, 
 then scrubbed with sand well ground and sifted. 
 
 Both these operations are continued until the complete 
 disappearance of any trace of oxide or rust on the surface of 
 the articles. 
 
 The pieces prepared and ready to be put into the nickel 
 bath, are plunged for a moment in a liquid of the same com- 
 position as that used for cleaning them, when they are quickly 
 washed in plain water and afterwards in distilled or filtered rain 
 water. When they come out of this last bath they are imme- 
 diately put on the hooks and immersed in the plating bath. 
 
 Management of the Ctcrrent , — It is prudent to watch the 
 progress of the operation and to regulate the current of the 
 battery. If the current is too strong the nickel is deposited 
 in the form of a grey or even black powder. When the bottle 
 battery is used it is easy to modify the current, by sinking 
 the zinc more or less into the exciting liquid. 
 
 An hour or so is sufficient to render the coat of nickel 
 deposited sufficiently thick, and in a condition to stand proper 
 polishing ; but the articles may with advantage be left for 
 five or six hours in the bath, if it is desired that they should 
 be very thickly coated. 
 
 Rate of Deposit . — In a bath holding 10 gr. of nickel per 
 litre, about i ‘ 8 gr. of nickel must be deposited per hour per 
 square decimetre to obtain a good result. 
 
Domestic Electricity for Amateurs. 173 
 
 When the articles are taken out of the bath they are 
 washed in plain water and dried in hot sawdust. 
 
 Polishing . — Polishing finishes the process and gives the 
 brilliant appearance of silver so much sought after. This is 
 the more easily and perfectly obtained when the articles have 
 been polished before being put into the bath. 
 
 To polish the articles they are taken in the right hand 
 and rubbed rapidly backwards and forwards on a strip of 
 cloth soaked in polishing powder boiled in water, the cloth 
 being firmly fixed at one end and held at the other in the left 
 hand. The hollow parts are polished by means of cloth pads 
 of various sizes fixed on sticks. These pads must be dipped 
 into the polishing paste when using them. 
 
 The articles when well brightened are washed in water to 
 get rid of the paste and the wool threads, and finally dried in 
 sawdust. 
 
174 
 
 Domestic Electricity for Amateurs, 
 
 CHAPTER XII. 
 
 ELECTRIC RECREATIONS. 
 
 Electricity, by its invisibility, instantaneous action, and the 
 peculiar characteristics of its manifestations, lends itself to a 
 mass of experiments and singular phenomena, some of which 
 we will now describe with the idea that amongst the numerous 
 ways of self-instruction, those which instruct whilst they amuse 
 must take a high rank. 
 
 With this view we will review successively telephonic 
 curiosities, melographs, jewels, illusions, and toys. 
 
 Telephonic Curiosities. 
 
 Under this title we give some telephone experiments 
 remarkable for the nature of the receiver employed. We 
 know that the telephone transmitter, whether magneto or 
 microphone, is an apparatus designed to set up undulatory 
 currents synchronous with the vibrations which gave rise to 
 them, and that these electrical waves react on a receiver 
 which again transforms it into sound-vibrations more or less 
 weakened, but sensibly of the same nature. 
 
 The Bell magneto telephone is generally used as receiver, 
 but as a matter of fact, none of the parts of which it consists 
 are essential for a transmission, which if not perfect is at least 
 workable. 
 
 Telephones without Vibrating Diaphragm — The 
 
 first simplification to which a Bell telephone may be sub- 
 mitted consists in the suppression of the vibrating diaphragm, 
 when speech is no longer distinctly audible if the transmitter 
 is a magneto telephone, but if a carbon transmitter and 
 
Domestic Electricity for A mateurs. 
 
 175 
 
 induced currents are used conversation may be carried on. 
 The sound is, however, very weak, but Count du Moncel who 
 made a great number of experiments on this subject, proved 
 that the effects are the more pronounced the more strongly 
 the core is magnetised and its bulk lessened. By using a 
 well magnetised watch-spring and a small coil of fine wire on 
 its extremity, Du Moncel succeeded in hearing speech even 
 when a Bell magneto telephone was used as transmitter. 
 
 Telephone without Diaphragm and without 
 Magnet. Ader’s Experiment. — The presence of a mag- 
 netised core in the telephone receiver is not absolutely neces- 
 sary ; the electrophone of Ader has very small electro-magnets 
 of soft iron. Making experiments with this apparatus Ader 
 was led to construct a receiver consisting of a simple iron rod 
 
 1 millimetre in diameter wrapped with a coil of fine wire, 
 and he was enabled to transmit speech under these conditions 
 with great distinctness. The small iron core was stuck on a 
 block of wood, and he found that 
 by applying to the other free end 
 a heavy mass, the intensity of the 
 sound was more than doubled. 
 
 He then constructed the simple 
 telephone receiver shown in Fig. 
 
 1 16, in which B is a door handle, 
 
 C C a soft iron rod i millimetre 
 in diameter, fixed on a deal board 
 
 2 inches square and a small coil 
 A wound on a goose-quill. The 
 transmitter was a carbon trans- 
 mitter of any description. With 
 this little instrument a very 
 amusing spiritualism experiment may be made by fixing the 
 iron rod C C underneath a table, hiding the conductors care- 
 fully and letting a confederate speak into the transmitter 
 placed in another room some distance away. If the experi- 
 ment be made in silence at a late hour of the night, the whole 
 table speaks, and it may be heard anywhere round the table 
 if the ear be brought close to it. This experiment produces 
 
176 Domestic Electricity for Amateurs. 
 
 the most singular effects on credulous and impressionable 
 persons. 
 
 Ader, continuing his experiments, constructed another 
 Fig. 1 17. telephone still more simple ; 
 
 it is made of a piece of 
 wood A B, Fig. 117, and of 
 a bobbin C fixed to it, on 
 which a fine wire is wound 
 very loosely. Such an ap- 
 paratus will speak when 
 actuated by a carbon trans- 
 mitter and three Leclanche 
 cells. If the spirals are 
 too tight or covered with 
 shellac, the telephone does 
 not speak, but by intro- 
 ducing a nail D into the bobbin, speech will at once be heard 
 distinctly. Withdraw the nail and the telephone ceases to act. 
 Telephone without Diaphragm, Magnet, or Coil.— 
 
 The following telephone 
 receiver is still simpler. 
 It consists of a soft iron 
 rod A, Fig. 118, fixed in a 
 wooden board B, with a 
 heavy metallic mass at the 
 other end of A. By holding 
 the board B to the ear 
 speech may be reproduced 
 by using a carbon trans- 
 mitter. De la Rive in 1846 
 reproduced sounds under 
 similar conditions with in- 
 terrupted currents, but Ader first reproduced articulate speech 
 by this means. 
 
 Dunand’s Speaking Condenser — A condenser is a 
 number of sheets of tin-foil each separated by paraffined paper 
 or mica. Such an arrangement makes an excellent telephone 
 receiver. Dunand by the following means makes it speak, 
 
Domestic Electricity for Amateurs, 
 
 177 
 
 On the primary circuit are included a microphone M, Fig. 1 19, 
 a battery P, and a small bobbin B ; the secondary wire of the 
 coil B is in circuit with the line, and a battery of several 
 elements P', the two free ends being joined to the terminals 
 of a small condenser C, which forms the receiver. By speak- 
 ing into the microphone the primary current becomes undu- 
 
 lating and induces currents in the fine wire of the coil, which 
 vary the charge of the condenser. These undulating charges 
 and discharges of the condenser make it speak, but the cause 
 of the phenomenon cannot yet be perfectly explained. 
 
 The battery P is indispensable ; the induced currents, by 
 increasing or diminishing the current of the battery, vary the 
 charge of the condenser, but the direction always remains the 
 same. This is up to the present a sine qua non of the 
 speaking condenser, and however the connections may be 
 altered, if this point be satisfied the condenser will have this 
 faculty of articulation in a greater or less degree. The battery 
 P consists of four ordinary Leclanche cells, two in tension 
 and two in quantity. 
 
 The coil B has a primary wire of about \ ohm resistance 
 and a secondary of 250 to 300 ohms. 
 
 The number of cells in the battery P' to charge the con- 
 denser varies with the number of condensers used. 
 
 Telephonic transmission without receiving appa- 
 ratus — We saw how Dunand made the condenser speak, but 
 it is possible to greatly simplify this, as was demonstrated by 
 M. Giltay at the Paris Observatory on the occasion of the 
 Easter meeting of the French Physical Society. 
 
 An inspection of Fig. 120 will explain the connections. 
 The primary circuit includes a battery P of two or three large 
 Leclanche cells, or of one or two small accumulators, an Ader 
 transmitter, and the primary wire of a small induction coil B. 
 
 Fig. 1 19. 
 
 N 
 
178 Domestic Electricity for Amateurs. 
 
 The second circuit consists of the secondary wire of the 
 coil B, a battery P' of ten to twelve Leclanche cells, and 
 the line wire terminating at R in two ordinary medical coil 
 handles. 
 
 If some one speaks or sings into the transmitter M, and 
 two persons A and B each take one of the handles R in the 
 bare hand, it is sufficient for A to apply his other hand, 
 gloved, to B’s ear, or vice versa, or even simultaneously for A 
 or B, or A and B together, to hear a voice coming out of the 
 glove. 
 
 Fig. 120. 
 
 This experiment is similar to Dunand’s speaking con- 
 denser. A’s hand and B’s ear constitute the two plates of a 
 condenser, the glove acting the part of the dielectric. 
 
 Repeating Giltay’s experiment at the laboratory of the 
 School of Physics and Chemical Industry of Paris and vary- 
 ing its arrangements, the glove was replaced by a sheet of 
 ordinary paper ; then two persons A and B holding the 
 handles R and applying the ear of one to that of the other, 
 interposing the sheet of paper, heard tunes and words coming 
 out of the paper. Finally the paper, that is to say the 
 dielectric, was entirely done away with and sounds heard 
 direct by including the hearer or hearers in the circuit, 
 Fig. 1 2 1. One of the most curious phases of the experiment 
 is to make a chain of three persons. A, B, and C, when the 
 third person C hears the hands of A and B speak. A and B 
 each holds one of the circuit wires and applies his disengaged 
 hand to the ear of C. It is even possible, but the experiment 
 requires absolute silence, to make a sort of telephonic chain 
 enabling five or six persons to hear at once ; A putting his hand 
 to B’s ear, B his hand to C’s ear, and so on to the last, who 
 
Domestic Electricity for Amateurs. 179 
 
 closes the circuit by holding one of the handles, the other 
 being held by A. 
 
 It is difficult to explain clearly how these telephonic 
 
 N 2 
 
i8o Domestic Electricity for Amateurs, 
 
 transmissions are effected without a receiver. All that can 
 be concluded is that the ear is an instrument of incomparable 
 delicacy, and of an exquisite sensitiveness, seeing that -it can 
 perceive such excessively feeble vibrations as there must be 
 on this telephonic chain. 
 
 Melographs. 
 
 The name of melograph is applied without distinction, 
 and wrongly, in our opinion, to apparatus which register 
 music and to those which reproduce it mechanically. We 
 will describe two systems in which electricity plays an im- 
 portant part. 
 
 Roncalli’s Melograph, or Automatic Recorder of 
 Musical Compositions. — The first question is. Are re- 
 corders of musical improvisoes useful, and can they render 
 real service to musicians by ' inscribing automatically and 
 instantaneously in a suitable notation, easy to read and 
 ultimately to transcribe, all melodies passing through the 
 brain of the artist at the moment of inspiration ? 
 
 The opinions on this subject are very divergent. It 
 appears, however, that a good recorder of musical impro- 
 visoes, useless according to some, indispensable according to 
 others, may nevertheless be of some use, and we will there- 
 fore describe a system exhibited at the Vienna Exhibition in 
 1873 by Roncalli, which offers, if not a perfect solution, at 
 least a first important step in that direction. 
 
 The first electrical music-recorder was invented and con- 
 structed in 1856 by Count du Moncel. After some experi- 
 ments the apparatus was, perhaps prematurely, abandoned, 
 as its performance did not come up to what was required. 
 But we must not forget that twenty-eight years have since 
 passed, and that batteries were not so simple and not so gene- 
 rally known as they are to-day. An apparatus compelled to 
 have recourse to electric batteries was at that time almost pro- 
 scribed, especially by those little accustomed to their handling. 
 
 At the present moment the question may be reopened 
 and the solution attempted with greater chance of practical 
 
Domestic Electricity for Amateurs. i8i 
 
 success. Roncalli’s apparatus, as was that of du Moncel, is 
 based upon the chemical reactions produced by the electric 
 current. 
 
 It is known that a steel point gliding over a sheet of paper 
 saturated with a solution of yellow cyanide of potassium and 
 nitrate of ammonia leaves no mark, but when an electric 
 current passes through the paper and the metallic point, the 
 latter is attacked ; a salt of protoxide of iron is formed, 
 which in presence of the cyanide causes a black precipitate 
 leaving a mark. 
 
 The colours of the marks vary with the nature of the 
 point : thus, for example, copper or its alloys leave a red 
 mark ; cobalt, a brown ; bismuth, an invisible mark turning 
 canary yellow in water ; nickel and chrome leave green 
 marks ; silver, an invisible mark which turns brown when 
 exposed to the light. 
 
 Roncalli’s melograph is founded on these properties. It 
 consists of a comb with fixed and very close metallic teeth, 
 traversed by the current of the battery. Each tooth is joined 
 by a wire to a key of the piano or the harmonium. 
 
 The teeth corresponding to the natural tones are of steel, 
 those which correspond to the half-tones of brass. 
 
 A roll of prepared paper drawn by a clockwork movement 
 passes at a uniform speed underneath the metallic points, and 
 shows the mark of the teeth the keys of which are lowered ; 
 the length of the marks on the paper roll is proportionate to 
 the duration of the corresponding sounds, that is to say, the 
 value of the note. Fig. 122 represents the whole system 
 arranged on a harmonium, and Fig. 123 shows the details of 
 the instrument itself, seen* on the right of Fig. 122. The case 
 on the left is a clockwork arrangement for unrolling the paper, 
 the speed of which is regulated by fans ; the pyramidal- 
 shaped case in the middle is a metronome, the use of which 
 we will presently explain. 
 
 The recorder. Fig. 123, consists of a metallic cylinder A, 
 joined to the zinc pole of a battery sufficiently powerful to 
 decompose the nitrate of ammonia (Roncalli uses three or 
 four chloride of sodium elements). At B is a comb, movable 
 
i 82 
 
 Domestic Electricity for Amatezcrs. 
 
 round the axis C ; this comb has forty-one teeth, each of which 
 communi(iates by an insulated wire E with a terminal D, 
 from whence a second insulated wire G joins it to one of the 
 keys of the piano. The handle M enables the comb B at 
 will to be brought up to or away from the cylinder A. 
 
 Fig. 122. 
 
 The paper is worked by the two cylinders F and L, 
 between which it passes. The cylinder F is driven by clock- 
 work (Fig. 123) by means of pulleys and a cord. There are 
 nine rows of teeth on its surface, which press by means of a 
 spring into an equal number of grooves cut on the circum- 
 
Fig. 123. 
 
 Domestic Electricity for Amateurs. 
 
 183 
 
 ference of the cylinder L. The barrel M carries the prepared 
 paper, which passes between the cylinder A and the comb B, 
 
 and between the two cylinders F and L, which unroll it at a 
 uniform speed. A brass strip is stretched under the keys all 
 along the finger-board of the piano or harmonium, and this 
 
184 Domestic Electricity for Amateurs. 
 
 strip is connected to the positive pole of the battery. Small 
 springs fixed under each key make contact between this strip 
 and the metallic pieces, to which come the conductors G, 
 joined to the corresponding terminals D of the receiver. 
 
 It will now be readily understood how the apparatus 
 works. By pressing one or several notes, the current passes 
 into the corresponding teeth of the comb and imprints on the 
 paper roll a series of marks, the position of which indicates 
 the height, the duration, and the length ; the line is black for 
 a natural tone, red for a sharp or flat. For a harmonium of 
 five octaves a comb of sixty-one points is necessary, and as 
 the points are about 2 millimetres apart, a breadth of at least 
 1 12 millimetres (about 4J inches) is required. To reduce the 
 width of this roll Roncalli repeats the two end octaves, so 
 that the first is written over the second and the fifth over the 
 fourth. Thirty-nine points and a roll of paper 3^ inches wide 
 are then sufficient. 
 
 It now remains to mark the time. For this purpose 
 Roncalli introduces into the comb two other teeth, made of 
 an alloy of bismuth and copper, which leave orange-coloured 
 marks. In the original arrangement the musician sent the 
 current to these points by pedals, thus making two orange 
 marks whenever the time was changed, but this was a great 
 nuisance to the player. At present Roncalli uses a metro- 
 nome, the action of which is automatic and perfect, provided 
 the musician himself keeps the time indicated by the 
 metronome. 
 
 Practically this is at least just as inconvenient as in the 
 first case, or perhaps more so, as in one piece different times 
 follow each other rapidly, and the musician may not be able 
 under the influence of his inspiration to stop himself to 
 change the motion of the metronome and to adapt it to the 
 changed rhythm of the melody. 
 
 In fact the registration of the time, or more correctly of 
 the separation of the times, does not appear to us to have 
 been solved by any of the known apparatus. 
 
 The use of chemical papers necessitates certain precautions 
 to which an artist cannot easily conform ; the oxidation and 
 
Domestic Electricity for Amateurs. 185 
 
 the unequal wear and tear of the points also require a certain 
 maintenance which render the apparatus very delicate to 
 manage in spite of its simplicity. 
 
 Carpentier’s Repeating Melograph. — We cannot 
 do better, in order to describe this curious and original instru- 
 ment, than let M. Carpentier speak himself: — 
 
 “ The desire to add to one’s talents one which one does 
 • not possess is, perhaps, an active incitement to the spirit of 
 invention. As far as I am concerned, I may say that my 
 pronounced liking of music added to my complete ignorance 
 of playing any instrument has always induced me to look 
 to mechanical contrivances for the means of satisfying my 
 natural liking. Musical boxes and organs have always 
 delighted me, and if it were not for the monotony resulting 
 from the repetition of the same airs, I would willingly turn a 
 handle for hours in order to enjoy, without requiring assistance 
 from any one, the pleasure which the sensation of listening to 
 the measure and rhythm of the melody gives me. 
 
 ^‘Mechanical pianos, with their limitless series of perfo- 
 rated wood or cardboard sheets, would be a grand help to 
 dilettanti like me. But they are cumbersome, very dear, 
 and at the price at which the pieces of music are sold the 
 getting together of a musical library would be ruinous. 
 
 “ All these considerations have repassed a thousand times 
 through my mind, leading me some years since to invent a 
 small apparatus which I have called the melophone, and 
 which is made as follows : — 
 
 “ A small closed rectangular case ; inside, under the lid and 
 close together^ thirty very small harmonium reeds, requiring 
 ' little room and fixed in the ordinary manner ; above each 
 reed a passage cut in the common sounding-board and end- 
 ing in a small orifice on the top of the box. On one side of 
 the box is a tube enabling air to be pumped in by means of 
 any kind of bellows. 
 
 “ The thirty small holes are arranged in a perfectly straight 
 line, and a musician, with thirty fingers and some practice, 
 might make something of it. But I have only ten fingers and 
 no practice at all, so that I must have recourse to some other 
 
Fig. 1 24. 
 
 186 Domestic Electricity for Amateurs, 
 
 device to get from my melophone what I expect from it. By 
 means of revolving cylinders worked by a crank handle 
 
 I pass over the perforated surface of the case, in a direction 
 at right angles to the line of holes, a broad band of paper, 
 
Domestic Electricity for A mateurs . 187 
 
 which I take care to keep well pressed flat on the top of the 
 holes. The reader will already have guessed that the paper 
 was pierced with long and short holes of a special arrange- 
 ment, so that in the movement these holes are brought 
 exactly over the various openings, giving vent to the air 
 through the reeds, and that the melophone plays auto- 
 matically the piece previously inscribed. 
 
 “ The means being simple, the instrument was not perfect, 
 but it was something, and for me, much. I have since seen 
 similar instruments made in America. I do not know, 
 however, to whom the priority of invention belongs. 
 
 “ However, in possession of my melophone, I had to con- 
 sider the making of my rolls. The translation of ordinary 
 music into such language occupied my leisure in the winter 
 evenings. I soon saw that this would be a long and tedious 
 operation, and set to work to simplify it by getting musicians 
 of my acquaintance to prepare my rolls for me, without their 
 knowing what' they were doing. I combined a melograph to 
 write down the pieces played on a piano, but using characters 
 which my melophone could read, that is to say, by perforating 
 the paper. I would add that my melophone itself was trans- 
 formed, I made it able to take broader bands and even to 
 work the instrument itself, piano or harmonium, on which was 
 played the piece inscribed by the melograph. 
 
 “ My apparatus were exhibited at the International 
 Electric Exhibition. Before describing them let me give the 
 reader a glimpse of the results obtained. 
 
 “ I. A composer sits down at my piano and plays some 
 improvise or fleeting inspiration unpublished. He rises. I turn 
 three buttons and the instrument at once repeats automatically 
 the piece it has once heard or rather played by the fingers of 
 the artist. 
 
 “ 2. Together with the merit of an author, that of the per- 
 former has also to be considered, and the same piece, played 
 by two persons, produces very different effects. My instru- 
 ment is very docile, it preserves and reproduces the style of 
 each. It goes even further, it plays false notes. 
 
 “ 3. Several persons come to me to play a concerto ; I get 
 
1 88 Domestic Electricity for Amateurs, 
 
 them a violin, violoncello, flute, hautboy, piston (all provided 
 with my system). The piece is finished. Listen : my instru- 
 ment, past-master in the art of transcribing, plays at once on 
 a piano or an organ the concerto, perfectly transcribed, and 
 you hear all its parts. 
 
 “ 4. Finally, the last very useful application : I arrange 
 my roll in a printing machine, and the piece, instead of being 
 played, comes out written in ordinary characters. This 
 musical printer is at present only projected, but it is realis- 
 able. 
 
 “ Let me now describe the apparatus. First of all, the 
 harmonium and the melograph must be distinguished. Fifty 
 wires, hidden under the floor, place the two instruments in 
 communication. 
 
 “ Inscription . — The fifty harmonium keys are so arranged 
 that when pressed down an electric current is sent into the 
 corresponding wires. Each current, received in the melo- 
 graph, works a series of perforating tools, thus recording 
 the motion of the key sending it, on a roll of paper passed 
 through the apparatus at a uniform rate. 
 
 “ Repetition . — On again unwinding the roll, previously put 
 back to the original position, fifty small silver wires try to 
 make contact through the paper with a metallic cross-piece, 
 against which they press the paper. As soon as a hole 
 enables a point to touch the cross-piece, a current circulates 
 in one of the line wires, and acting on the lowering mechanism 
 of the corresponding key, determines the emission of the 
 sound, maintained until the substitution under the wire of a 
 blank. 
 
 This general explanation shows the connection between 
 the different parts of the apparatus, and I may now separately 
 describe the principal parts, as shown in Figs. 125 and 126. 
 
 ‘‘ Underneath each key a spring a, Fig 125, tends to place 
 itself on a silver band b running along the cross-piece c, 
 which covers the back part of the finger-board. A pilot 
 working freely in a small cylinder, holds the spring up, by 
 pressing against the key, when this is at rest. When the key 
 is lowered, the pilot follows its motion, and the spring .being 
 
Domestic Electricity for Amatetirs. 189 
 
 freed, makes contact. Two regulating screws enable the 
 course and the tension of the spring to be varied. The 
 current thus started by a key, is sent along the line wire 
 passing through a commutator e. 
 
 Fig. 125. 
 
 “ The currents caused by the harmonium and received in the 
 melograph, produce there the motion of the parts by means 
 of electro-magnets, Fig. 126, of a special form. The space in 
 the apparatus available for the necessary organs being very 
 limited, the electro-magnets form a battery in four rows in 
 
 Fig, 126. 
 
 echelon. The motion of the armatures b is transmitted by 
 the rods c to the bent levers and at the end of the 
 horizontal arm of each lever is an essential part of the 
 apparatus — the goffer e. The name explains its use : it is 
 pressed on the paper, and leaves there the record of the 
 pressure of the player on the keys of the harmonium. • 
 
1 90 Domestic Electricity for Amateurs. 
 
 ‘‘ The goffer forces the paper to penetrate into one of the 
 mortices cut in the plate /, under which the band passes, and 
 thus brings it up to a two-edged cutter revolving at great 
 speed, thus cutting out all the indentations made by the 
 goffer. 
 
 “ This is the action of the recording apparatus, and, of 
 course, a complete regulating system had to be adopted. 
 
 To play from the bands, the melograph causes currents, 
 and the harmonium receives them. The switch e enables 
 the line wires to be put in connection either with the sending 
 springs, or with the receiving organs. 
 
 “ For each note of the harmonium, the principal part of the 
 receiving mechanism is an electro-magnet f similar to those 
 of the melograph. Below the finger-board, from all the keys 
 are suspended by flexible chains small wooden shoes : these 
 work freely in the grooves cut in a cylinder h revolving with 
 a continuous and rapid motion. When a current passes 
 through any electro-magnet it presses by means of small 
 rollers i on the back of the shoe, binding it by friction against 
 the revolving cylinder. This pulls down the corresponding 
 key, and the note is sounded.” 
 
 Electric Jewels. 
 
 Animated Electric Jewels. — Trouve by means of 
 electricity has obtained some novel and often .startling effects. 
 
 These jewels are small figures animated by a lilliputian 
 battery, and we will describe some. 
 
 The death’s-head on the right of the bird. Fig. 127, is of 
 gold enamelled, and has diamond eyes and a movable jaw. 
 This makes a breast-pin. 
 
 The rabbit, also of gold, to the left of the bird, sits on its 
 tail and holds in its forepaws two small drum-sticks with 
 which it beats a microscopic gold clock-bell. This is also a 
 breast-pin. 
 
 An invisible wire joins the object to the small hermetically- 
 sealed battery of the size of a cigar, which is hidden in the 
 waistcoat pocket, Fig. 128. If one of these jewels is carried 
 
Fig. 127. 
 
 Domestic Electricity for Amateurs, 19 1 
 
 under the chin, and anybody looks at it, a finger is slipped 
 into the waistcoat-pocket, setting the battery to work, when 
 
 the death’s-head rolls its sparkling eyes and grinds its teeth, 
 or the small rabbit works like a kettle-drumer at the opera. 
 
192 
 
 Domestic Electricity for Amateurs, 
 
 Fig. 128. 
 
 The diamond bird is carried by a lady in her hair, and she 
 can at will make the wings of the bird flap by means of a 
 concealed wire. 
 
 Trouve’s Pocket Battery.— These jewels 
 are worked by a very small battery, which is 
 easily carried in the waistcoat pocket, or in a 
 lady’s hair. The battery is a zinc carbon cell 
 inclosed in a vulcanised rubber case hermeti- 
 cally closed. The zinc and carbon only extend 
 
 to the upper half of the case, the other holds the 
 exciting liquid. As long as the case is upright 
 the electrodes are not touched by the liquid, and 
 no electricity is produced, nor is there any ex- 
 penditure ; but as soon as the case is turned 
 upside down, or placed horizontally, the chemical 
 reaction takes place, and continues as long as 
 the case is in this position ; but when the battery is replaced 
 all action ceases. 
 
 Liuminous Jewels. — The production of small incandescent 
 lamps requiring only a few volts and less than an ampere, has 
 been utilised for novel and curious effects. Since 1882 the 
 actresses at the Savoy Theatre have been adorned with small 
 incandescent lamps fed by small accumulators easily hidden 
 in their dress. 
 
 Since then these applications have been enormously multi- 
 plied, and few theatres in London and the provinces are now 
 without them, especially for the Christmas pantomimes. 
 
 Trouve’s Luminous Electric Jewels. — Fig. 13 1 
 shows how a luminous jewel is constructed. The incan- 
 
Fig. 130, 
 
 Domestic Electricity for Amateurs, 
 
 193 
 
 descent lamp is fixed in the centre of the apparatus, the 
 glasses are cut into facets making lenses and increasing the 
 light. The two wires are hidden between the supporting pins, 
 
 o 
 
194 Domestic Electricity for Amateurs. 
 
 and the whole thing is easily taken to pieces to enable the 
 incandescent lamp to be renewed when broken. 
 
 Trouve’s Pocket Battery — The battery used by 
 Trouve consists of three zinc-carbon cells (two carbons to 
 each zinc) or more, according to the effect to be obtained, 
 the electrodes being in a solution of bichromate of potash 
 inclosed in an ebonite trough in compartments. The lid 
 
 Fig. 131. Fig. 132. 
 
 carrying the zincs and carbons is also of ebonite ; it is pro- 
 vided with a soft rubber washer, closing hermetically under 
 the pressure of two indiarubber rings, one of which is shown 
 at E. In spite of these precautions leakage of the acid 
 liquid may take place. In order to avoid this inconvenience 
 Trouve incloses the battery in two hard rubber cases F and G 
 which fit over each other like two parts of a cigar-case. The 
 wires are connected to the two terminals H H, and a small 
 switch enables the circuit to be closed or opened. This 
 small battery, shown in Fig. 132 in actual size, weighs about 
 I lb. and will work for about twenty minutes with a lamp of 
 
Domestic Electricity for Amateurs, 
 
 195 
 
 2 or 3 volts (small breast-pin). Larger batteries weighing 
 under 2 lbs. may also be carried in a good sized pocket, and 
 under favourable conditions they will light a lamp of 4 to 
 5 volts for nearly an hour. In other types the elements are 
 arranged flat and can be hidden in a side pocket, as their size 
 is not greater than that of an ordinary pocket-book. 
 
 Scrivanow’s Batteries and Jewels — This battery is 
 shown in Fig. 133. It is contained in a guttapercha box, the 
 electrodes being a plate of silver covered with chloride of 
 
 Fig. 133. 
 
 silver, wrapped in parchment paper and surrounded by a 
 U-shaped zinc insulated by a piece of guttapercha. The 
 section of the battery, shown to the right of the figure, shows 
 the arrangement : Zn is the zinc plate, and Ag Cl the 
 chloride of silver. The exciting liquid is an alkaline solu- 
 
 o 2 
 
196 Domestic Electricity for Amateurs. 
 
 tion of very dilute potash. The guttapercha case with the 
 electrodes is closed hermetically by a guttapercha lid, in 
 which a hole is made to introduce and renew the liquid, the 
 hole being closed by a stopper. 
 
 The dancers are equipped as follows : — The silver-plated 
 belt passed round the waist holds two batteries. Fig. 1 34 ; the 
 
 Fig. 134. 
 
 diadem is placed on the head and some attendants fix the 
 conducting wires from the two cells in series to the incan- 
 descent lamp. This done, a muslin sash is gathered round 
 the waist hiding nearly the whole apparatus. The incan- 
 descent lamp of the diadem is fitted in front of a metallic 
 star covered with pieces of glass imitating emeralds, and 
 forming a reflector. On the belt a small switch is fixed, 
 enabling the fairy at will to light or put out the lamp of her 
 diadem. 
 
Domestic Electricity for Amateurs. 
 
 197 
 
 Aboilard’s Electric Jewels.— -Fig. 135 represents in 
 actual size these electric jewels, and shows how delicately 
 they are constructed. On the right and left are two breast- 
 pins for men : one is in the form of a small lantern, and the 
 other represents an open flower forming a reflector. In the 
 middle two pretty trinkets for ladies are seen, a bird and a 
 diadem ; below these is a small round switch, very convenient, 
 and may be worked in the pocket. 
 
 Fig. 135. 
 
 Conjuring. 
 
 Speaking Tables and Electric Insects. — The mar- 
 vellous facility with which electricity lends itself to the pro- 
 duction from a distance of mechanical calorific or luminous 
 effects has often been made use of in some curious and amusing 
 
198 Domestic Electricity for Amateurs, 
 
 effects, which simple minds willingly call supernatural, as 
 they cannot explain them satisfactorily. 
 
 Fig. 136 is a table having the appearance of an ordinary 
 stand, which enables one to reproduce at will spirit-rapping 
 or sepulchral voices. 
 
 Fig. 136. 
 
 The foot of the table holds a Leclanche cell of squat form, 
 carefully hidden in the part which joins the three feet to the 
 upright. The table itself is in two parts ; the lower part is 
 hollowed out and the upper is a thin lid not more than | to 
 inch thick. 
 
 In the middle of the table below the top a horseshoe 
 magnet is arranged vertically. 
 
 One end of the wire of this magnet communicates with 
 one of the poles of the battery, and the other with a flat 
 metallic ring fastened to the upper part of the table making 
 
Domestic Electricity for Amateurs, 199 
 
 the lid ; below this metallic ring, and at a little distance, is a 
 toothed ring F joined to the other pole of the battery. 
 Pressing lightly on the table causes the lid to bend, the flat 
 ring touches the toothed one and closes the circuit of the 
 battery on the magnet which attracts its armature and produces 
 a dull knock ; lifting the hand, the lid resumes its original 
 position, breaks the circuit again and produces another knock. 
 
 Passing the hand lightly over the table the lid is succes- 
 sively bent over a part of the circumference, makes and breaks 
 take place on a number of the teeth and the distinct raps 
 give place to a rumbling sound, clear or dull as required by 
 the medium interrogating the spirits. As the table itself 
 contains the whole mechanism it may be moved about without 
 the trick being suspected. 
 
 The table may also be worked from a distance by using con- 
 ductors passing through the feet under the carpet of the room, 
 communicating with a battery the circuit of which is closed 
 by a confederate in an adjoining room at opportune intervals. 
 
 Finally, a small telephone receiver may be substituted for 
 the electro-magnet, and a micro-telephonic system for the 
 ordinary battery, by which the spirit-rappings may be trans- 
 formed into speaking voices. With a little practice it will be 
 easy for the confederate to give messages from the spirits in 
 a sepulchral voice, thereby adding to the illusion. 
 
 Fig. 137 shows an amusing device for the decoration of a 
 room ; it represents insects resting on a plant which is no 
 sooner moved than their wings begin to move as if they were 
 going to fly away. These insects are animated by a Leclanche 
 battery hidden in the flower-pot. The insect itself is nothing 
 more than a mechanism similar to that of an ordinary bell. 
 The body of the insect forms the core of a straight electro- 
 magnet c carrying a light return wire on its upper part, 
 before which a small iron disc b is placed, making the head 
 of the animal. The head is fixed to a spring like the arma- 
 ture of an ordinary bell, and works the wings, giving them a 
 flapping motion when it is attracted and repelled alternately 
 by the electro-magnet ; the interruptions of the current are 
 caused by means of a small tremble arrangement, the action 
 
200 Domestic Electricity for Amateurs. 
 
 of which will be easily understood by reference to the drawing 
 on the left of Fig. 137. The current reaches the electro- 
 magnet by a fine copper wire hidden in the foliage, and is 
 joined to the positive pole of the battery, the negative pole of 
 which is in relation with the bottom of the pot. 
 
 Fig. 137. 
 
 The wire to the trembler of each insect runs to the bottom 
 of the pot, but without touching it ; a drop of mercury is on 
 the bottom of the pot and rolling about freely. If, therefore, 
 the pot be moved, the mercury rolling over the bottom by 
 successively closing the circuit of the different insects sets 
 them in motion until the pot is replaced and the mercury is 
 again stationary. 
 
 Amusing: Physical Experiment with an Induc- 
 tion Balance. — It is easy to be a very good conjurer if one 
 is a good electrician, by pressing into the service of the art 
 
Domestic Electricity for Amateurs. 201 
 
 the numerous resources of the science. The following is an 
 example which makes use of one of the most remarkable 
 discoveries of modern times, viz. the induction balance of 
 Professor Hughes. This apparatus lends itself to a very- 
 curious and amusing trick which will doubtless be of interest 
 to our readers. 
 
 The experiment consists in guessing the value and nature 
 of a piece of money, placed at a distance in a wooden box 
 closed by a lid, without touching the case or even going 
 near it. 
 
 The apparatus is in two parts, one of which is behind the 
 scenes, and is shown on the left of the figure, the other is an 
 ornamental wooden box, .shown on the right of the figure, 
 into which the piece of money whose value is to be guessed is 
 placed. Four wires twisted together join the two parts. It 
 is hardly necessary to say that if it is desired to perform the 
 trick in a thorough and complete style, the conductors should 
 be hidden and the terminals dispensed with by using contacts 
 in the bottom of the stand. The case may also be suspended 
 from the ceiling of a room as in the well-known trick of the 
 magic drummer. 
 
 The apparatus. Fig. 138, consists essentially of four coils, 
 A A' B B' ; the two coils B B' are connected in series by the 
 conductors i, 2 ; the circuit is completed by a battery P and 
 any contact-breaking apparatus I, for example a clockwork 
 sending interrupted currents from the battery P into the two 
 coils B B' ; the two coils A A' are also in series with one 
 another by the conductors 3, 4, and a telephone T is intro- 
 duced into the circuit. The battery therefore sends interrupted 
 currents into the coils BB', which develop induced currents 
 in the coils A A', but the winding of the coils is such that the 
 action of A on B balances the action of B' on A' if the coils 
 are quite equal and placed at equal distances apart. As in 
 practice it is impossible to realise these conditions, the coil 
 A is placed on a movable support and the distance is regu- 
 lated by means of the screw V. When the induced currents 
 are perfectly balanced the telephone T in the circuit of A A^ 
 remains silent. 
 
202 
 
 Domestic Electricity for Amateurs* 
 
 When under these conditions a piece of money is put into 
 the box C, the balance is disturbed, so that in the telephone 
 will be heard the click of the interruptions caused by the 
 clockwork in the battery circuit. 
 
 Fig. 138. 
 
 In order to obtain silence an identical piece of money 
 must be placed between the coils A and B. In practice a 
 collection of the different coins of the realm may be stuck 
 on one, two, or three flat wooden rulers, which are slipped 
 between the coils quickly, stopping at each coin for an 
 instant until the telephone is silenced, when the piece placed 
 at that moment between the coils is the same as that in the 
 box. If no coin in the collection silences the telephone, it is 
 owing to the piece of money in the box being a foreign coin, 
 or it is bad money. 
 
 This is in detail the curious trick which may be performed 
 by the induction balance, an apparatus which by its nature 
 touches on the highest theories of molecular physics. 
 
 Electric Toys. 
 
 Electricity lends itself to a number of curious, instructive, 
 and amusing experiments, and an entire volume would not be 
 sufficient to enumerate them all. We will content ourselves 
 with describing a few of the simplest and easiest. 
 
 A Simple Electric Machine.— We will first of all 
 
Domestic Electricity for Amateurs, 203 
 
 construct at little expense an electric machine capable of 
 giving sparks three-quarters of an inch long. 
 
 A sheet of strong paper and of large size is used for this. 
 Rub it well with the dry hand or some woollen fabric until it 
 adheres to the table. A bunch of keys is then placed in the 
 middle of the sheet, which is lifted by two corners. If at this 
 moment any one brings the finger near the bunch of keys a 
 brilliant spark is emitted, the finer and larger the dryer the 
 weather and the more often the paper has been rubbed and 
 heated. 
 
 Ordinary paper, foolscap for example, well heated and 
 dried, acquires electric properties when rubbed sharply; it 
 will be felt to crackle in the hand under the influence of a 
 multitude of small discharges slightly luminous in the dark. 
 Electrified paper will adhere to walls. Wideman found that 
 the electric properties of paper may be considerably increased 
 by submitting it to previous treatment ; if ordinary unglazed 
 paper be plunged into a mixture of equal parts of nitric and 
 sulphuric acid, then well washed with plenty of water and 
 dried, it becomes extremely electric. If it is placed on a 
 wooden table, or better still, on a wax cloth, and rubbed with 
 the hand, it soon attracts all light bodies — feathers, small 
 pieces of paper, pith-balls, &c. In the dark, when the paper 
 is taken from the wax cloth the entire surface shines like 
 phosphorus ; on approaching the finger an electric spark 
 will be seen to shoot out. A Leyden jar may be charged 
 with this paper, which becomes a regular electrophorus, and 
 in fact all the ordinaiy experiments with electric sparks and 
 discharges may be made. This paper when rubbed gives out 
 the characteristic odour of ozone. It keeps its curious pro- 
 perties for a long time, and when weakened it Is sufficient to 
 slightly heat it to restore all its energy. It will be seen that 
 for a few pence an electric machine may be obtained sufficient 
 to demonstrate all the electric phenomena. 
 
 An Economical Electrophorus. — Take a lacquered 
 iron tea-tray, 12 to 16 inches long; cut a sheet of stout 
 packing-paper to such a size that it will easily lie on the flat 
 part of the tray. Two strips of paper are fixed by means of 
 
204 
 
 Domestic Electricity for Amateurs, 
 
 sealing-wax to each end of the sheet to lift it by when placed 
 on the tray. The tea-tray is then placed on two tumblers, to 
 support and insulate it. 
 
 The sheet of paper must then be well heated over a very 
 bright fire or stove till it becomes well dried and as hot as 
 possible. This done, it is placed quickly, to prevent its 
 
 Fig. 139. 
 
 cooling, on a wooden table, and rubbed sharply with a hard 
 and very dry clothes-brush. It is then placed on the tray ; 
 the tray is touched with the finger and the paper lifted up. 
 If at this moment any one brings his finger near the tray a 
 visible spark will pass. Fig. 139. The paper may then be 
 replaced on the tray, and touching the edge a second time 
 and relifting the paper, a second spark will be drawn out, 
 and so on seven or eight times. 
 
Domestic Electricity for A 7 nateurs, 205 
 
 To make an extemporary Leyden jar, take a glass 
 tumbler filled with shot, plant in the middle of the shot a 
 teaspoon, and if everything be thoroughly dry we have an 
 excellent Leyden jar. To charge it we work our electro- 
 phorus as just explained. While one operator touches the 
 
 Fig. 140. . 
 
 edge of the tray and -lifts the paper, another person, holding 
 the glass tumbler by the bottom, brings it to the tray, so that 
 the spark takes place between it and the spoon. The Leyden 
 jar is thus charged by means of successive sparks ; a small 
 discharge may then be obtained as shown in Fig. 140. 
 
 Pfeiffer’s Electrophorus. — A number of instructive 
 and amusing experiments may be effected with this. It 
 consists in principle. Fig. 141, of a thin sheet of ebonite, 
 I millimetre thick, 6 inches broad, and 8 inches long. 
 
2 o 6 Domestic Electricity for Amateurs, 
 
 The wooden disc covered with brass of the classic electro- 
 phorus is replaced by a small brass sheet of the size of a 
 playing card, fixed on to one of the sides of the ebonite. 
 
 This ebonite electrophorus produces electricity with re- 
 markable facility. It is placed flat on a wooden table, rubbed 
 successively on both sides with the open hand ; if it is lifted 
 in the left hand and the right hand brought near to the brass 
 foil, a spark half an inch long will be obtained. 
 
 Fig. 141. 
 
 The ebonite electrophorus is completed by a number of 
 small accessories consisting of small pith figures enabling the 
 phenomena of electric attraction and repulsion to be demon- 
 strated in a most amusing way. 
 
 Electrify the ebonite plate, place on the sheet of brass foil 
 any of the small figures, and lift the plate to insulate it from 
 its support. Here is a small mannikin lifting its arms to 
 heaven, or this one the silken hair of which stands on end, and 
 the third, lighter than the others, leaps away like a clown and 
 escapes from the electric influence, together with the two 
 small pith-balls which were placed alongside it. We have 
 
Domestic Electricity for Amateurs, 207 
 
 grouped the three mannikins in a single drawing, but they are 
 generally worked singly. 
 
 Magnetic Toy. — Magnetism also lends itself to a number 
 of amusing experiments owing to its action at a distance and 
 through most bodies. Every one has been amused as a child 
 
 Fig. 142. 
 
 by making a needle stand on end by means of a magnet 
 placed over it sufficiently distant from the needle to keep it 
 vertical, but not close enough to lift it altogether, or by making 
 a pen run about a table without apparent reason by manoeu- 
 vring a magnet underneath the table. This experiment, 
 revived in a more elaborate style, is represented in Fig. 142. 
 
 The scene represents a circus with painted decorations 
 and track formed of a piece of yellow coloured cardboard. 
 
 In the middle of the track small figures are placed on 
 
2o8 Domestic Electricity for Amateurs, 
 
 wooden bases. As shown in the drawing these may consist 
 of three musicians and one master of the ring. Toward the 
 circumference of the circus other small figures are placed, 
 representing a horse mounted by a lady rider, a car drawn 
 by a sorrel horse, a horse at liberty, &c. By turning the 
 handle on the base of the toy, the band strikes up and at the 
 same time, the horse starts by itself and runs round the 
 circular track. The horse is taken away and replaced by the 
 harnessed horse. Turn the handle, and as the music sounds, 
 the car becomes animated like the horse and spins round the 
 master of the ring and the musicians, who do not move. 
 
 The explanation is very simple : the handle moves a mag- 
 net hidden in the case which serves as support to the small 
 circus ; this handle, while working the mechanism of the 
 music, at the same time turns the magnet round an axis in 
 the centre of the circus. The small figures which move round 
 the ring are mounted on small soft iron bases, and are very 
 light, and the surface of the cardboard being highly polished, 
 the magnet is powerful enough to overcome the friction and 
 so drag these light objects with it. 
 
 An Economical Compass. — The ‘ Magasin Pittoresque ’ 
 describes a simple and economical compass. It says : 
 “ Take a small cork. Fig. 143, and pass an ordinary knitting 
 
 Fig. 143. 
 
 
 oi 
 
 needle through it which has been magnetised by gently rub- 
 bing it in one direction on one of the small horseshoe 
 magnets given to children. When the needle E is passed 
 through the cork, a sewing needle or a pin is stuck in one of 
 
Fig 144. 
 
 Domestic Electricity for Amatcttrs. 
 
 2C9 
 
 its ends, and the point lodged in one of the holes on the top 
 of a thimble. To balance it a match C is run in on each side 
 
 of the cork as shown in the drawing, and wax melted on to 
 the end of each match until the whole is properly balanced. 
 
 P 
 
2 1 o Domestic Electricity for A mateurs. 
 
 As it is very important with so sensitive an instrument to 
 avoid agitation by air, the thimble is placed on the bottom of 
 an ordinary earthenware basin B D T and closed with a pane 
 of glass V. To graduate the compass, a circle is described 
 with a pair of compasses on stout paper, and the points and 
 degrees marked off. This is then fixed under the needle, the 
 north end of the card coinciding with the north-seeking pole 
 of the needle. 
 
 If a fine sewing needle be magnetised and smeared with 
 tallow it will float on water, thus making a very simple 
 compass. 
 
 Liuminous Fish. — Fig, 144 shows the effect of an ex- 
 periment of M. Trouv^ in which a fish is caused to swallow 
 a tiny incandescent lamp which is then lighted, showing every 
 bone in its body. These lamps are now much used by 
 surgeons and dentists for lighting up the cavities of the body. 
 They are especially useful to dentists, who are able to have a 
 powerful light thrown through the teeth rendering them trans- 
 parent, when the slightest decay becomes visible. 
 
 The Induction Coil — This is used to modify the 
 qualities of the electric current and generally to increase the 
 
 Fig. 145. 
 
 tension or E.M.F. at the expense of the current ; or as it is 
 sometimes wrongly stated, it transforms dynamic electricity 
 
Domestic Electricity for Amateurs, 2 1 1 
 
 into static electricity. We most strongly protest against this 
 definition which tends to the idea of two different electricities, 
 while really they are only modifications of one and the same 
 phenomenon. 
 
 However, with the Ruhmkorff coil, a number of very 
 amusing, interesting, and instructive experiments may be 
 made. Fig. 145 shows a very convenient form of this instru- 
 ment, in which all the connections are visible, enabling the 
 course of the current to be traced out ; the secondary coil is 
 movable and enables the power of the induced current to be 
 varied at will and the condenser may be used or not, as 
 required, which enables its action on the nature and power of 
 the spark to be studied. 
 
 Caricatures on Electricity. — We cannot better close 
 the chapter devoted to electric recreations than by a reference 
 to the many caricatures relating to electricity which have 
 appeared. 
 
 The kind of electric furore which attacked London in 1881 
 and 1882, in consequence of the brilliant results obtained from 
 the first attempts at public and industrial electric lighting, 
 gave an opportunity to the caricaturists to exercise their wit 
 on this subject. 
 
 From the numerous caricatures which appeared at that 
 time we will reproduce two. 
 
 The first appeared in Punch on the 25th June, 1881, at 
 the time when the Faure accumulator appeared in England. 
 King Coal and King Steam anxiously watch the new 
 arrival, and ask, Fig. 146, “ What will he grow to ? ” King 
 Coal is particularly put out and gives the baby a look boding 
 it no good. It is now well known that this anxiety was alto- 
 gether needless, as, to store electrical energy, it is generally 
 necessary to consume coal. 
 
 The second caricature. Fig. 147, appeared in The City 
 of the 4th November, 1882, and represents “The dream of a 
 gas director.” The artist endeavoured to picture the night- 
 mares which haunt the brain of a gas company’s director, 
 thinking over the new inventions of electric lighting, which at 
 that time were rapidly introduced in England by numerous 
 
 P 2 
 
2 I 2 Domestic Electricity for Amateurs. 
 
 companies, some of which, from the first, were only ephe- 
 meral. 
 
 Our Director, before going to sleep, reads The City, and 
 instead of finding the desired rest, electric lighting and the 
 
 Fig, 146. 
 
 various phases of its development and rapid progress pass 
 before his eyes as a vision in the shape of promotors and 
 inventors, while the gasometer disappears in the darkness of 
 the night. 
 
 Perpetual Motion by means of Electricity As 
 
 might have been expected, electricity has been pressed into 
 
FrCx. 147. 
 
 All inventor (save the mark) proposed as the sole and only 
 true solution of domestic electric lighting, a common clock- 
 
 Domestic Electricity for Amateiirs. 213 
 
 the service of inventors of a certain class who seriously pro- 
 pose projects involving perpetual motion. 
 
2 1 4 Domestic Electricity for A mateurs. 
 
 work arrangement which was to work a dynamo producing a 
 powerful current, of which it would be sufficient to shunt off a 
 portion to rewind the clockwork. Nothing simpler ! 
 
 Another actually proposed a no less infallible system of 
 working tramways by using the excess of power produced 
 during rotation (?) of the wheels to charge accumulators to be 
 used at starting ! 
 
 Quite recently, too, an engineer, editor of an industrial 
 publication, seriously proposed a carbonic acid motor, in 
 which the cooling produced by the expansion of the gas was 
 to be counterbalanced by platinum spirals, heated by an 
 electric current furnished by a small dynamo run by the 
 motor itself (sic) ? 
 
 It seems almost a dream to read in 1884 of such absurdi- 
 ties. 
 
Domestic Electricity for Amateurs. 
 
 2I5 
 
 CHAPTER XIII. 
 
 VARIOUS APPLICATIONS — WORKSHOP OF THE 
 ELECTRICIAN, 
 
 A WHOLE book would be required to review entirely all the 
 various applications of which electricity is susceptible, and 
 which could not be classified under any of the foregoing 
 headings. We can here only refer to a very few taken 
 haphazard. 
 
 Physiological Actions of the Current— Medical 
 Applications. — Electro-therapeutics are becoming every 
 day more important in medicine, and in spite of the opinions 
 so divergent which still divide practitioners, it may be hoped 
 that before long, thanks to the introduction of precise methods 
 and measuring apparatus into medical practice, the doses of 
 electricity will cease to be quack, and become scientific and 
 rational. However, the results already obtained are suffi- 
 ciently important to justify their introduction into daily 
 practice. 
 
 Electricity is employed in medical practice under two 
 forms: (i) continuous current; ( 2 ) alternating or induced 
 current. 
 
 Continuous currents are always produced by means of 
 small batteries easy to move about and to renew ; sulphate of 
 copper or Leclanch^ batteries are very suitable for this ap- 
 plication. They are coupled in tension by means of a com- 
 mutator in the case holding them ; a varying number may at 
 will be taken according to the effects to be obtained, the 
 nature of the disease, the parts to be affected, &c. 
 
 Alternating currents are obtained by means of a small 
 
2 i 6 Domestic Electricity for Amateurs, 
 
 Clarke machine, or an induction coil. With the first the 
 power is modified by changing the speed, or by masking the 
 magnet more or less. With the induction coil either the 
 number of elements in the primary circuit may be varied, or 
 the number of induced currents produced in a given time 
 may be altered by regulating the speed of the trembler ; or, 
 finally, the quantity of electricity developed at each dis- 
 charge may be varied by altering the distance between the 
 primary and secondary coils. 
 
 It will be understood, so great a number of variable 
 factors being given, that the logical and rational application 
 of electricity to therapeutics becomes a complex, delicate, 
 and difficult question, and the intervention of a practitioner is 
 required to apply it judiciously. 
 
 Together with the direct use of the current, electricity is 
 used in an indirect manner in a number of cases, such, for 
 instance, as to localise the position of a bullet, the lighting of 
 dark cavities, cauterisation, &c. ; but the study of these 
 applications cannot be gone into here. 
 
 The Trainingr of Horses by Electricity.— Various 
 means have been proposed to stop and master runaway or 
 restive horses ; there is nothing more ingenious and efficacious 
 than that devised by Defoy, and of which M. Bella, manager 
 of the French Omnibus Company, has had occasion to ap- 
 preciate the advantages. This question cannot fail to be of 
 interest to those fond of horses. The apparatus is simply a 
 Clarke machine inclosed in a case, which may be placed 
 convenient to the hand of the rider or driver. The reins 
 contain conducting wires connected to the bit and to the 
 magneto-electric apparatus. By turning the handle a current 
 is sent through the mouth of the horse, giving it such a 
 surprise that it stops and remains quiet. By coupling the 
 action of the electricity with gentleness and petting the most 
 dangerous horse will be rapidly mastered. 
 
 M. Bella reports that M. Defoy tried his apparatus in 
 his presence at the yard of the General Omnibus Company 
 (French), where the worst tempered and most dangerous 
 horses were assembled. A gelding, very difficult to shoe. 
 
Domestic Electricity for Amatctcrs, 2 1 7 
 
 was brought to the forge, where it showed excessive temper, 
 but when supplied with the electric persuader, it, at the end 
 of a few minutes, allowed its neck and back to be patted, 
 then its limbs, and finally, the hind feet were lifted, always 
 the most difficult to approach and to lift up. The shoe was 
 hammered without the horse again becoming rebellious, says 
 M. Bella, and its shoes were changed without being shackled, 
 and without recommencing its dangerous defences. 
 
 The Director of the Paris Cab Company also certified to 
 the efficiency of this process : “ The experiment,” says M. 
 Camille in a report before us, “ was tried on several horses 
 which up till then it was impossible to shoe, all, without 
 exception, being tamed by the apparatus. One horse about 
 to be shod, rolled about on the ground, kicking and struggling 
 against everything, and nothing could subdue it. I had 
 recourse to M. Defoy’s apparatus ; at the first trial the feet 
 of the restive horse were, to my astonishment, lifted without 
 great difficulty ; at the second trial it was as easy to shoe it 
 as if it had never offered any opposition ; the animal was 
 conquered.” 
 
 M. Defoy drove a dangerous horse before us, which he 
 stopped instantaneously after being set galloping, by turning 
 the handle of a Clarke apparatus fixed under the seat of the 
 vehicle. Fig. 148. It is important to state that the result is 
 not due to a violent shock ; the electric current is not strong 
 enough to galvanise or stupefy the animal ; it rather pro- 
 duces astonishment and the disagreeable but not painful 
 sensation of electric pricking. We ourselves have very easily 
 borne the current of the magneto-electric apparatus used by 
 M. Defoy. There is nothing in the process on a par with 
 the barbarous methods sometimes used to tame horses by 
 force or violence, which tire them out, excite them, and make 
 them wild and vindictive. 
 
 We will add that M. Defoy completes the electric bit 
 with an electric stick not less ingenious than the first appa- 
 ratus. This is a whip containing two insulated conductors, 
 ending in two points at right angles to the end of the stick, 
 and are, as in the case of the bit, connected to a magneto- 
 
Fig. 148. 
 
 Domestic Electricity for Amateurs, 
 
 218 
 
 electric apparatus. A horse in the habit of rearing may, at 
 the moment it attempts to do so, be stopped by giving it the 
 
 spur and at the same time applying the electric stick to the 
 top of the neck. Under the influence of the electric current 
 
Domestic Electricity for Amateurs. 219 
 
 it at once starts forward with head down. The same effect 
 may be produced on a shying horse, by applying the current 
 to its jaw on the side towards which it attempts to shy, when 
 it will at once be stopped. By means of an electric stick 
 M. Defoy makes a horse obey him in a few seconds in a 
 truly marvellous manner. 
 
 Edison’s Electric Pen. — The electric pen is an appa- 
 ratus by which marks are made on ordinary paper — not a 
 continuous coloured mark as with ordinary pens and pencils, 
 but a broken mark, formed by a great number of small holes 
 pierced through the paper. These holes are made by a very 
 fine steel point, which alternately goes in and out of a tube 
 held in the hand, and which much resembles a metal pencil. 
 This point is worked backwards and forwards very rapidly ; 
 it makes 180 strokes a second when doing no work. Each time 
 it passes out of the case barely enough to be visible, but quite 
 enough to pierce the paper. The writing is not so quick as 
 with ordinary pens, but nearly as quick as that of a writer 
 who takes time to shape his letters well. 
 
 The alternating motion is given to the pen by a small 
 electro-motor, very ingenious and simple, which is placed 
 above the penholder, as shown by Fig. 149. The point is at 
 the lower end of a rod which traverses the penholder, and 
 which at its upper part ends in a fork pressing an excentric 
 mounted on the axis of the motor. This excentric has three 
 cams, and therefore sixty revolutions of the axis per second 
 produce the 180 strokes just mentioned. This axis carries a 
 soft iron plate acting as movable armature to a fixed electric 
 magnet, before v/hich it revolves rapidly, by means of a very 
 simple commutator, which breaks the current twice per 
 revolution. A fly-wheel, relatively heavy, surrounds this 
 armature, which is a diameter to it, and it serves to give 
 great regularity and steadiness to the motion of the 
 axis. 
 
 The electric current which gives life to this small appa- 
 ratus is furnished by a bichromate of potash battery of two 
 elements suitably arranged. The lids of the two cells are of 
 ebonite plates, joined to a metallic central piece which slides 
 
2 20 Domestic Electricity for Amateitrs, 
 
 on a vertical rod ; the lids carry the two electrodes, carbon 
 and zinc. When the pen is used, the electrodes are plunged 
 into the liquids. When the writing is finished the central 
 piece is lifted up and hooked to the upper part of the sliding 
 
 Fig. 149. 
 
 rod, and then the electrodes are kept from contact with the 
 liquids, and consequently no zinc is uselessly consumed. 
 
 Thanks to this precaution, the battery will work for four 
 days without any maintenance whatever, that is to say, 
 without renewing the liquid, and the zinc may work for 
 several weeks. 
 
 By means of the electric pen, writing is obtained, formed 
 by a number of small holes close together. This writing is 
 very difficult to read by reflection, that is to say in the usual 
 way for ordinary writing ; it is more readable by transparency, 
 but either way would be useless in practice. But this per- 
 forated paper must be treated as a negative, by means of 
 which a great number of positive proofs may be obtained. 
 To obtain these copies the press represented in Fig. 150 is 
 used. The negative is placed on the lid shown on the left; it 
 is kept in position all round by springs easy to manipulate. 
 
Domestic Electricity for Amateurs. 221 
 
 On the body of the press a sheet of white paper is placed, 
 and the lid is put over it ; the negative is applied to the white 
 paper. By means of the roller shown on the right, ink is 
 spread over the negative, which penetrates through all the 
 
 Fig. 150. 
 
 holes to the sheet of white paper below. When the lid is 
 relifted the proof is obtained. This copy has a peculiar 
 appearance ; the writing has neither thick down nor light up 
 strokes. To be readable it should have been clearly written. 
 However, with some use and some very simple artifices all 
 kinds of designs are obtained ; music may be copied with 
 the whites and blacks perfectly reproduced. The same nega- 
 tive may be used to produce a great number of proofs ; it 
 is said up to a thousand and more may be obtained. 
 
 Persons used to the work will print six copies per minute. 
 Of course like all other manual labour, this operation is not 
 learned without a little study and some trouble, but there is 
 nothing difficult about it. 
 
 Bellet and Hallez d’Arros’ Voltaic Pencil. — This 
 apparatus was to obtain the same results and to satisfy the 
 
222 Domestic Electricity for Amateurs. 
 
 same wants as Edison’s electric pen, but it differs essentially 
 from it by the means employed. 
 
 It is known that the spark of the electric machine or the 
 induction coil flashing between two metallic points or between 
 a metal point and a conducting body, is susceptible of piercing 
 cardboard and more so, paper. Let us suppose, between such 
 a point and a conductor, we have a series of electric sparks 
 flashing almost continuously, while between these bodies a 
 sheet of paper is moved. This will be pierced by holes : the 
 closer together the more sparks there are, and the slower the 
 paper passes. 
 
 The principle is simple, but the practical realisation was 
 not effected without difflculties, the principal one being the 
 following : — 
 
 At the moment when the draughtsman brought the point 
 near to the paper, a spark several millimetres long flies out, 
 the consequence of the tension between the two opposite 
 charges. This spark gave to the person holding the point a 
 shock, which repeated every moment made it impossible to 
 trace a straight or a curved line. 
 
 The spark besides was rarely insulated, several sparks were 
 created at the same time, piercing the paper in several places 
 round the point wanted. Therefore no clean and precise mark 
 could be obtained. Finally, in order not to have the holes too 
 far apart, without being obliged to slacken the speed of the 
 pencil, it was necessary that the sparks were far more numer- 
 ous than those produced by ordinary induction coils. 
 
 Bellet and d’Arros have succeeded in overcoming these 
 difflculties. The induced current passes through the point 
 and at the same time part goes through a shunt in a measure 
 and within limits which may be regulated at will, the sparks 
 between the point and the metallic plate being thus re- 
 duced so that they just suffice to pierce, cut, or destroy the 
 paper where they are produced without giving appreciable 
 shocks. 
 
 The paper used, which must be very fine, is previously 
 soaked in a solution of sea salt and then dried. This simple 
 operation prevents multiple sparking and enables absolutely 
 
Fig. 151. 
 
 Domestic Electricity for Amateurs, 
 
 223 
 
 clean marks to be obtained. The contact-breaker, trembler, 
 and the bobbin were also modified in form. Fig. 151 shows 
 
 the principal arrangement of the voltaic pencil ; it is similar in 
 appearance to an ordinary pencil, the wood of which serves as 
 
2 24 Domestic Electricity for Amatetirs, 
 
 insulator, and the lead as conductor. A flexible wire covered 
 with silk joins the pencil to the secondary wdre of the coil. 
 
 The desk supports the metallic plate on which the sheet 
 of paper is placed and holds the printing arrangement similar 
 to that of Edison’s pen. 
 
 Electric Stamper. — This apparatus is intended to re- 
 place the ordinary damp stamps used to obliterate stamps, 
 cheques, invoices, &c. At the lower part of the apparatus is 
 a thin platinum wire shaped so as to make a design or an 
 initial. This is the part applied to the surface of the stamp 
 to be cancelled. The platinum wire is in communication with 
 a battery. The circuit is closed by pressing a spring with 
 
 Fig. 152. 
 
 the finger, as shown in Fig. 152. The platinum glows and 
 the paper to which it is applied is carbonised by the heat and 
 bears the trace of an imprint absolutely ineffaceable. This 
 ingenious system may not alone be used by the post office, 
 but also by merchants who have to cancel a great number of 
 stamps. 
 
Domestic Electricity for Amateurs, 225 
 
 Photophonic Experiments. — Selenium possesses the 
 singular and curious property of changing its resistance with 
 the intensity of the light which falls on its surface ; Graham 
 Bell’s photophone is based on this action. 
 
 A selenium cell easy of construction and sufficient to 
 demonstrate the principles of Bell’s discovery may be made 
 for experimental purposes in the form shown in Fig. 153, 
 which gives one of these cells in actual size. 
 
 To construct it, take two brass strips a and about one- 
 tenth of a millimetre thick, and one centimetre wide. They 
 are separated by two strips of parchment paper which insulate 
 
 Fig. 153. 
 
 them, and the four strips are rolled into a spiral, as shown in 
 the figure, where one of the brass strips is represented by a 
 full line, the second by a dotted line, and the paper by the 
 blank space separating them. The block so formed is 
 placed between two brass plates c and d in contact respec- 
 tively with the ends d and b' of the metallic strips ; the whole 
 is strongly pressed between two hard pieces of wood by two 
 tie-pieces M and N. Two terminals A and B, in metallic 
 communication with the plates c and join the element to 
 the circuit in which it is to be included. One side is then 
 filed smooth and carefully polished with emery paper. After 
 having thus polished the block, and having tested with a 
 
 Q 
 
2 26 Domestic Electricity for Amatetirs. 
 
 sensitive galvanometer the absence of metallic communication, 
 the polished surface is covered with selenium in the following 
 manner : — 
 
 The apparatus is heated in a sand-bath, or by placing it 
 over a thick copper plate heated by the flame of a Bunsen 
 burner up to a temperature at which a selenium pencil pressed 
 on the top will melt ; the pencil is then worked along the 
 surface, so as to cover it with as slight a coat as possible. 
 By not allowing the temperature to get above this point, the 
 selenium takes the slaty tint characteristic of the state in 
 which it is most sensitive to light ; when cool it is ready to 
 act. To preserve the surface, it may be protected by a thin 
 mica plate, or covered with a coat of shellac varnish laid on 
 hot. When the apparatus becomes deteriorated, it is suffi- 
 cient to file up the surface, polish it, and put fresh selenium 
 on to recondition it. The resistances of these cells vary 
 greatly with the sizes, nature of the selenium, mode of pre- 
 paration, &c. To obtain good results, about ten Leclanche 
 cells in tension and a very high resistance telephone are re- 
 quired, that is to say, one, the fine wire of which makes a 
 great number of turns round the magnetised cone. 
 
 Private Electric Laboratories.— According to taste, 
 means, and the sum to be spent upon it, electricity takes 
 a more or less important position in the house of an amateur. 
 With some electricity is everything, with others nothing. A 
 middle course between these two extremes should be kept so 
 as not to become either an electromaniac or an electrophobe. 
 Some eminent scientists have expended endless time and 
 money in perfecting their laboratories, foremost, perhaps, 
 among them being that of Mr. Warren de la Rue, which 
 represents a fortune in itself. M. G. Plante’s laboratory, of 
 which Fig. 1 54 reproduces a part, is also worthy of remark. 
 Here 800 small secondary cells are to be seen, being those 
 used by him in his experiments on high tension currents. 
 
 The Amateur’s Workshop. — The most necessary tools 
 for the amateur are those for working in wood and metal, and 
 he should accustom himself to the handling of these with 
 some amount of skill, to enable him to construct for himself. 
 
Fig. 154. 
 
 Domestic Electricity for A mateurs. 227 
 
 in a more or less rough fashion, the elementary parts of 
 apparatus. At most manufactories he will be able to obtain 
 
228 
 
 Domestic Electricity for A^nateurs, 
 
 parts ready made, only requiring finishing up and putting 
 together, but whatever tools he may possess, it will, for 
 
 Fig. 155. 
 
Domestic Electricity for Amateurs, 229 
 
 example, be waste of time for any one to make their own 
 terminals, and cover their own wire. It may, on the other 
 hand, however, be advantageous to wind for himself any 
 electro-magnets he may require, so as to be sure of the length 
 of wire wrapped on and its resistance. Small means must be 
 content with a box of tools more or less complete, but con- 
 taining the essentials for working in wood and metal ; what- 
 ever may be wanting must be made up for by patience and 
 careful contriving. Those who are more fortunate may be 
 able to set up a small workshop containing a carpenter’s 
 bench, a vice, and a small foot lathe with the necessary tools. 
 
 We do not, however, propose in this book to go into the 
 full details of workshop construction, and we would refer 
 our readers to any of the known manuals on the special 
 subject, but for their guidance we give in Fig. 155 some 
 sketches of ordinary terminals, connections, &c., which will 
 be required, no matter what kind of work they may under- 
 take, and the uses of the various parts will be easily understood 
 from an inspection of the figures. 
 
 London: printed fy wili iam clowes and sons, limited, 
 
 STAMKORD STREET AND CHARING CROSS. 
 

 t 
 
 
 
 
 
1885. 
 
 BOOKS RELATING 
 
 TO 
 
 APPLIED SCIENCE 
 
 PUBLISHED BY 
 
 E. & F. N. SPON, 
 
 LONDON: 12S, STRAND. 
 
 NEW YORK : 35, MURRAY STREET. 
 
 A Pocket-Book for Chemists, Chemical Manufacturers, 
 
 Metallurgists, Dyers, Distillers, Brewers, Sugar Refiners, Photographers, 
 Students, etc., etc. By Thomas Bayley, Assoc. R.C. Sc. Ireland, Ana- 
 lytical and Consulting Chemist and Assayer. Third edition, with 
 additions, 437 pp., royal 32mo, roan, gilt edges, 5 j. 
 
 Synopsis of Contents : 
 
 Atomic Weights and Factors — Useful Data — Chemical Calculations — Rules for Indirect 
 Analysis — Weights and Measures — Thermometers and Barometers — Chemical Physics — 
 Boiling Points, etc. — Solubility of Substances — Methods of Obtaining Specific Gravity — Con- 
 version of Hydrometers — Strength of Solutions by Specific Gravity — Analysis — Gas Analysis — 
 Water Analysis — Qualitative Analysis and Reactions — Volumetric Analysis — Manipulation — 
 Mineralogy — Assaying — Alcohol — Beer — Sugar — Miscellaneous Technological matter 
 relating to Potash, Soda, Sulphuric Acid, Chlorine, Tar Products, Petroleum, Milk, Tallow, 
 Photography, Prices, Wages, Appendix, etc., etc. 
 
 The Mechanician : A Treatise on the Construction 
 
 and Manipulation of Tools, for the use and instruction of Young Engineers 
 and Scientific Amateurs, comprising the Arts of Blacksmithing and Forg- 
 ing ; the Construction and Manufacture of Hand Tools, and the various 
 Methods of Using and Grinding them ; the Construction of Machine Tools, 
 and how to work them ; Machine Fitting and Erection ; description of 
 Hand and Machine Processes ; Turning and Screw Cutting ; principles of 
 Constructing and details of Making and Erecting Steam Engines, and the 
 various details of setting out work, etc., etc. By Cameron Knight, 
 Engineer. Containing 1147 illustrations, and 397 pages of letter-press. 
 Third edition, 4to, cloth, i8j. 
 
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2 
 
 CATALOGUE OF SCIENTIFIC BOOKS 
 
 On Designing Belt Gearing, By E. J. Cowling 
 
 Welch, Mem. Inst. Mech. Engineers, Author of ‘Designing Valve 
 Gearing.’ Fcap. 8vo, sewed, (id. 
 
 A Handbook of Formulce, Tables, and Memoranda, 
 
 for Architectural Surveyors and others engaged in Building. By J. T. 
 Hurst, C.E. Thirteenth edition, royal 32mo, roan, 5r. 
 
 “ It is no disparagement to the many excellent publications we refer to, to say that in our 
 opinion this little pocket-book of Hurst’s is the very best of them all, without any exception. 
 It would be useless to attempt a recapitulation of the contents, for it appears to contain almost 
 everything that anyone connected with building could require, and, best of all, made up in a 
 compact form for carrying in the pocket, measuring only s in. by 3 in., and about f in. thick, 
 in a limp cover. We congratulate the author on the success of his laborious and practically 
 compiled little book, which has received unqualified and deserved praise from every profes- 
 sional person to whom we have shown it .” — The Dublin Builder. 
 
 Tabulated Weights of Angle, Tee, Bulb, Round, 
 
 Square, and Flat Iron and Steel, and other information for the use of 
 Naval Architects and Shipbuilders. By C. H. Jordan, M.I.N.A. Fourth 
 edition, 32mo, cloth, 2J. (id. 
 
 Quantity Surveying. By J. Leaning. With 42 illus- 
 trations, crown 8vo, cloth, gj. 
 
 Contents : 
 
 A complete Explanation of the London 
 Practice. 
 
 General Instructions. 
 
 Order of Taking Off. 
 
 Modes of Measurement of the various Trades. 
 Use and Waste. 
 
 Ventilation and Warming. 
 
 Credits, with various Examples of Treatment. 
 Abbreviations. 
 
 Squaring the Dimensions 
 Abstracting, with Examples in illustration of 
 each Trade. 
 
 Billing. 
 
 Examples of Preambles to each Trade. 
 
 Form for a Bill of Quantities. 
 
 Do. Bill of Credits. 
 
 Do. Bill for Alternative Estimate. _ 
 
 Restorations and Repairs, and Form of Bill. 
 Variations before Acceptance of Tender. 
 Errors in a Builder’s Estimate. 
 
 Schedule of Prices. 
 
 F orm of Schedule of Prices. 
 
 Analysis of Schedule of Prices. 
 
 Adjustment of Accounts. 
 
 Form of a Bill of Variations. 
 
 Remarks on Specifications. 
 
 Prices and Valuation of Work, with 
 Examples and Remarks upon each Trade. 
 
 The Law as it affects Quantity Surveyors, 
 with Law Reports. 
 
 Taking Off after the Old Method. 
 
 Northern Practice. 
 
 The General Statement of the Methods 
 recommended by the Manchester Society 
 of Architects for taking Quantities. 
 
 Examples of Collections. 
 
 Examples of “ Taking Off” In each Trade. 
 
 Remarks on the Past and Present Methods 
 of Estimating. 
 
 A Practical Treatise on Heat, as applied to the 
 
 Useful Arts; for the Use of Engineers, Architects, &c. By Thomas 
 Box. With 14 plates. Third edition, crown 8vo, cloth, I 2 s. (id. 
 
 A Descriptive Treatise on Mathematical Drawing 
 
 Instruments: their construction, uses, qualities, selection, preservation, 
 and suggestions for improvements, with hints upon Drawing and Colour- 
 ing. By W. F. Stanley, M.R.I. Fifth edition, with numerous illustrations, 
 crown 8vo, cloth, 5 j. 
 
PUBLISHED BY E. & F. N. SPON. 
 
 3 
 
 Spans A rchitects and Builders Pocket-Book of Prices 
 
 and Memoranda. Edited by W. Young, Architect, Royal 32mo, roan, 
 4s. 6 d. ; or cloth, red edges, 3<r. (id. Published annually. Eleventh edition. 
 Now ready. 
 
 Long-Span Railway Bridges, comprising Investiga- 
 tions of the Comparative Theoretical and Practical Advantages of the 
 various adopted or proposed Type Systems of Construction, with numerous 
 Formulae and Tables giving the weight of Iron or Steel required in 
 Bridges from 300 feet to the limiting Spans ; to which are added similar 
 Investigations and Tables relating to Short-span Railway Bridges. Second 
 and revised edition. By B. Baker, Assoc. Inst. C.E. Plates, crown 8vo, 
 cloth, 5 j. 
 
 Elementary Theory and Calculation of Iron Bridges 
 
 and Roofs. By August Ritter, Ph.D., Professor at the Polytechnic 
 School at Aix-la-Chapelle. Translated from the third German edition, 
 by H. R. Sankey, Capt. R.E. With 500 illustrations, 8vo, cloth, 15^. 
 
 The Builders Clerk : a Guide to the Management 
 
 of a Builder’s Business. By Thomas Bales. Fcap. 8vo, cloth, i.y. (d. 
 
 The Elementary Principles of Carpentry. By 
 
 Thomas Tredgold. Revised from the original edition, and partly 
 re-written, by John Thomas Hurst. Contained in 517 pages of letter- 
 press, and illustrated with 48 plates and 150 wood engravings. Third 
 edition, crown 8vo, cloth, i8i-. 
 
 Section I. On the Equality and Distribution of Forces — Section II. Resistance of 
 Timber — Section III, Construction of Floors — Section IV. Construction of Roofs — Sec- 
 tion V. Construction of Domes and Cupolas— • Section VI. Construction of Partitioirs — 
 Section VII. Scaffolds, Staging, and Gantries — Section VIII. Construction of Centres for 
 Bridges — Section IX. Coffer-dams, Shoring, and Strutting — Section X. Wooden Bridges 
 and Viaducts — Section XI. Joints, Straps, and other Fastenings — Section XII. Timber. 
 
 Our Factories, Workshops, and Warehouses: their 
 
 Sanitary and Fire-Resisting Arrangements. By B. H, Thwaite, Assoc. 
 Mem. Inst. C.E. With 183 wood engravings, crown 8vo, cloth, qj. 
 
 Gold : Its Occurrence and Extraction, embracing the 
 
 Geographical and Geological Distribution and the hlineralogical Charac- 
 ters of Gold-bearing rocks ; the peculiar features and modes of working 
 Shallow Placers, Rivers, and Deep Leads ; Hydraulicing ; the Reduction 
 and Separation of Auriferous Quartz ; the treatment of complex Auriferous 
 ores containing other metals ; a Bibliography of the subject and a Glossary 
 of Technical and Foreign Terms. By Alfred G. Lock, F.R.G.S. With 
 numerous illustrations and maps, 1250 pp., super-royal 8vo, cloth, 
 2/. I2i'. (id. 
 
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4 
 
 CATALOGUE OF SCIENTIFIC BOOKS 
 
 A Practical Treatise on Coal Mining. By George 
 
 G. Andre, F.G.S., Assoc. Inst. C.E., Member of the Society of Engineers. 
 With 82 lithographic plates. 2 vols., royal 4to, cloth, 3/. 12s. 
 
 Iron Roofs : Examples of Design, Description. Illus- 
 trated with 64 Working Drawings of Executed Roofs. By Arthur T. 
 Walmisley, Assoc. Mem. Inst. C.E. Imp. 4to, half-morocco, £2 \2s. 6 d. 
 
 A History of Electric Telegraphy, to the Year 1837. 
 
 Chiefly compiled from Original Sources, and hitherto Unpublished Docu- 
 ments, by J. J. Fahie, Mem. Soc. of Tel. Engineers, and of the Inter- 
 national Society of Electricians, Paris. Crown 8vo, cloth, gs. 
 
 Spons' Information for Colonial Engineers. Edited 
 
 by J. T. Hurst. Demy 8vo, sewed. 
 
 No. I, Ceylon. By Abraham Deane, C.E. 2 s. 6 d. 
 
 Contents ; 
 
 Introductory Remarks — Natural Productions — Architecture and Engineering — Topo- 
 graphy, Trade, and Natural History — Principal Stations — Weights and Measures, etc., etc. 
 
 No. 2. Southern Africa, including the Cape Colony, Natal, and the 
 Dutch Republics. By Henry Hall, F.R.G.S., F.R.C.I. With 
 Map. 3J. 6 d. 
 
 Contents : 
 
 General Description of South Africa — Physical Geography with reference to Engineering 
 Operations — Notes on Labour and Material in Cape Colony — Geological Notes on Rock 
 Formation in South Africa — Engineering Instruments for Use in South Africa — Principal 
 Public Works in Cape Colony: Railways, Mountain Roads and Passes, Harbour Works, 
 Bridges, Gas Works, Imgation and Water Supply, Lighthouses, Drainage and Sanitary 
 Engineering, Public Buildings, Mines — Table of Woods in South Africa — Animals used for 
 Draught Purposes — Statistical Notes — Table of Distances — Rates of Carriage, etc. 
 
 No. 3. India. By F. C. Danvers, Assoc. Inst. C.E. With Map. 4^. 6 d. 
 Contents ; 
 
 Physical Geography of India — Building Materials — Roads — Railways — Bridges — Irriga- 
 tion — River Works — Harbours — Lighthouse Buildings — Native Labour — The Principal 
 Trees of India — Money — Weights and Measures — Glossary of Indian Terms, etc. 
 
 A Practical Treatise on Casting and Founding, 
 
 including descriptions of the modem machinery employed in the art. By 
 N. E. Spretson, Engineer. Third edition, with 82 plates drawn to 
 scale, 412 pp., demy 8vo, cloth, i8r. 
 
 Steam Heating for Buildings ; or, Hints to Steam 
 
 Fitters, being a description of Steam Heating Apparatus for Warming 
 and Ventilating Private Houses and Large Buildings, with remarks on 
 Steam, Water, and Air in their relation to Heating. By W. J. Baldwin. 
 With many ilhistrations. Fourth edition, crown 8vo, cloth, lor. (id. 
 
PUBLISHED BY E. & F. N. SPON. 
 
 5 
 
 The Depreciation of Factories and their Valuation, 
 
 By Ewing Matheson, M. Inst. C.E. 8vo, cloth, 6j. 
 
 A Handbook of Electrical Testing. By H. R. Kempe, 
 
 M.S.T.E. Third edition, revised and enlarged, crown 8vo, cloth, i5j-. 
 
 Gas Works : their Arrangement, Construction, Plant, 
 
 and Machinery. By F. Colyer, M. Inst. C.E. 31 folding plates^ 
 
 8vo, cloth, 245'. 
 
 The Clerk of Works: a Vade-Mecum for all engaged 
 
 in the Superintendence of Building Operations. By G. G. Hoskins, 
 F.R.I.B.A. Third edition, fcap. 8vo, cloth, u. C)d. 
 
 American Foundry Practice: Treating of Loam, 
 
 Dry Sand, and Green Sand Moulding, and containing a Practical Treatise 
 upon the Management of Cupolas, and the Melting of Iron. By T. D. 
 West, Practical Iron Moulder and Foundry Foreman. Second edition, 
 with numerous illustrations^ crown 8vo, cloth, loj-. (id. 
 
 The Maintenance of Macadamised Roads. By T. 
 
 CoDRiNGTON, M.I.C.E, F.G.S., General Superintendent of County Roads 
 for South Wales. 8vo, cloth, (>s. 
 
 Hydraulic Steam and Hand Power Lifting and 
 
 Pressing Machinery. By Frederick Colyer, M. Inst. C.E., M. Inst. M.E, 
 With T 2 »flates, 8vo, cloth, i8j. 
 
 Pumps and Pumping Machinery. By F. Colyer, 
 
 M.I.C.E., M.I.M.E. With 2 T, folding plates ^ 8vo, cloth, 12s. 6 d. 
 
 The Municipal and Sanitary Engineer s Handbook. 
 
 By H. Percy Boulnois, Mem. Inst. C.E., Borough Engineer, Ports- 
 mouth. With numerous illustrations^ demy 8vo, cloth, 12s. 6 d. 
 
 Contents : 
 
 The Appointment and Duties of the Town Surveyor — Traffic — Macadamised Roadways — 
 Steam Rolling — Road Metal and Breaking — Pitched Pavements — Asphalte — Wood Pavements 
 — Footpaths — Kerbs and Gutters — Street Naming and Numbering— Street Lighting — Sewer- 
 age — Ventilation of Sewers — Disposal of Sewage — House Drainage — Disinfection — Gas and 
 Water Companies, &c.. Breaking up Streets — Improvement of Private Streets — Borrowing 
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 Openings — Public Pleasure Grounds — Cemeteries — Mortuaries — Cattle and Ordinary Markets 
 — Public Slaughter-houses, etc. — Giving numerous Forms of Notices, Specifications, and 
 General Information upon these and other subjects of great importance to Municipal Engi- 
 neers and others engaged in Sanitary Work. 
 
6 
 
 CATALOGUE OF SCIENTIFIC BOOKS 
 
 Tables of the Principal Speeds occurring in Mechanical 
 
 Engineerings expressed in metres in a second. By P. Keerayeff, Chief 
 Mechanic of the ObouchofF Steel Works, St. Petersburg; translated by 
 Sergius Kern, M.E. Fcap. 8vo, sewed, (id. 
 
 A Treatise on the Origin^ Progress, Prevention^ and 
 
 Cure of Dry Rot in Timber; with Remarks on the Means of Preserving 
 Wood from Destruction by Sea- Worms, Beetles, Ants, etc. By Thomas 
 Allen Britton, late Suiweyor to the Metropolitan Board of Works, 
 etc., etc. With lo plates ^ crown 8vo, cloth, *js. 6 d. 
 
 Metrical Tables. By G. L. Molesworth, M.I.C.E. 
 
 32mo, cloth, ij. (id. 
 
 Contents. 
 
 General — Linear Measures — Square Measures — Cubic Measures — Measures of Capacity — 
 Weights — Combinations — ^Thermometers. 
 
 Elements of Construction for Electro-Magnets. By 
 
 Count Th. Du Moncel, Mem. de ITnstitut de France. Translated from 
 the French by C. J. Wharton. Crown 8vo, cloth, 4^. (id. 
 
 Electro -Telegraphy. . By Frederick S. Beechey, 
 
 Telegraph Engineer. A Book for Beginners. Illustrated. Fcap. 8vo, 
 sewed, (id. 
 
 Handrailing : by the Square Cut, By John Jones, 
 
 Staircase Builder. Fourth edition, with seven plates, 8vo, cloth, 3J. (id. 
 
 Handrailing : by the Square Cut. By John Jones, 
 
 Staircase Builder. Part Second, with eight plates, 8vo, cloth, 3^. (id. 
 
 Practical Electrical Units Popularly Explained, with 
 
 numerous illustrations and Remarks. By James Swinburne, late of 
 J. W. Swan and Co., Paris, late of Brush-Swan Electric Light Company, 
 U.S.A. i8mo, cloth, u. (id. 
 
 Philipp Reis, Inventor of the Telephone: A Biographical 
 
 Sketch. With Documentary Testimony, Translations of the Original 
 Papers of the Inventor, &c. By Silvanus P. Thompson, B.A., Dr. Sc., 
 Professor of Experimental Physics in University College, Bristol. With 
 illustrations, 8vo, cloth, ^s. (id. 
 
 A Treatise on the Use of Belting for the Transmis- 
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 cloth, 15J. 
 
PUBLISHED BY E. & F. N. SPON. 
 
 7 
 
 A Pocket-Book of Useful FormulcB and Memoranda 
 
 for Civil and Mechanical Engineers. By Guilford L. Molesworth, 
 Mem. Inst. C.E., Consulting Engineer to the Government of India for 
 State Railways. With numerous illustrations^ 744 pp. Twenty-first 
 edition, revised and enlarged, 32mo, roan, 6 s. 
 
 Synopsis of Contents; 
 
 Surveying, Levelling, etc. — Strength and Weight of Materials — Earthwork, Brickwork, 
 Masonry, Arches, etc. — Struts, Columns, Beams, and Trusses — Flooring, Roofing, and Roof 
 Trusses — Girders, Bridges, etc. — Railways and Roads — Hydraulic Formulae — Canals, Sewers, 
 Waterworks, Docks — Irrigation and Breakwaters — Gas, Ventilation, and Warming — Heat, 
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 Wheels, Shafting, etc. — Workshop Recipes — Sundry Machinery — Animal Power — Steam and 
 the Steam Engine — Water-power, Water-wheels, Turbines, etc. — Wind and Windmills — 
 Steam Navigation, Ship Building, Tonnage, etc. — Gunnery, Projectiles, etc. — Weights, 
 Measures, and Money — Trigonometry, Conic Sections, and Curves — ^Telegraphy — Mensura- 
 tion — Tables of Areas and Circumference, and Arcs of Circles — Logarithms, Square and 
 Cube Roots, Powers — Reciprocals, etc. — Useful Numbers — Differential and Integral Calcu- 
 lus — Algebraic Signs — Telegraphic Construction and Formulae. 
 
 Spons Babies and Memoranda for Engineers ; 
 
 selected and arranged by J. T. Hurst, C.E., Author of ‘Architectural 
 Surveyors’ Handbook,’ ‘ Hurst’s Tredgold’s Carpentry,’ etc. Fifth edition, 
 64mo, roan, gilt edges, ij", ; or in cloth case, u. 6 d. 
 
 This work is printed in a pearl type, and is so small, measuring only 24^ in. by if in. by 
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 “ It is certainly an extremely rare thing for a reviewer to be called upon to notice a volume 
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 would imagine could be compressed into so small a space The little volume has been 
 
 compiled with considerable care and judgment, and we can cordially recommend it to our 
 readers as a useful little pocket companion.” — Engineering. 
 
 A Practical Treatise on Natural and Artificial 
 
 Concrete, its Varieties and Constructive Adaptations. By Henry Reid, 
 Author of the ‘ Science and Art of the Manufacture of Portland Cement.’ 
 New Edition, with 59 woodcuts and ^plates, 8vo, cloth, 15^. 
 
 Hydrodynamics : T reatise relative to the T esting of 
 
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 Electricity as a Motive Power. By Count Th. Du 
 
 Moncel, Membre de I’lnstitut de France, and Frank Gerald y, Inge- 
 nieur des Fonts et Chaussees. Translated and Edited, with Additions, by 
 C. J. Wharton, Assoc. Soc. Tel. Eng. and Elec. With 113 engravings 
 and diagrams, crown 8vo, cloth, *js. 6 d. 
 
 Hints on Architectural Draughtsmanship. By G. W. 
 
 Tuxford Hallatt. Fcap. 8vo, cloth, u. 6 d. 
 
8 
 
 CATALOGUE OF SCIENTIFIC BOOKS 
 
 Treatise on Valve-Gears, with special consideration 
 
 of the Link-Motions of Locomotive Engines. By Dr. Gustav Zeuner, 
 Professor of Applied Mechanics at the Confederated Polytechnikum of 
 Zurich. Translated from the Fourth German Edition, by Professor J. F. 
 Klein, Lehigh University, Bethlehem, Pa. Illustrated, 8vo, cloth, \ 2 s. 6 d. 
 
 The French- Polisher s Manual. By a French- 
 
 Polisher; containing Timber Staining, Washing, Matching, Improving, 
 Painting, Imitations, Directions for Staining, Sizing, Embodying, 
 Smoothing, Spirit Varnishing, French-Polishing, Directions for Re- 
 polishing. Third edition, royal 32mo, sewed, (>d. 
 
 Hops, their Cultivation, Commerce, and Uses in 
 
 various Countries. By P. L. SiMMONDS. Crown 8vo, cloth, 4J. (id. 
 
 A Practical Treatise on the Manufacture and Distri- 
 bution of Coal Gas. By William Richards. Demy4to, with numerous 
 wood engravings and 2 ().plates, cloth, 28^. 
 
 Synopsis of Contents : 
 
 Introduction — History of Gas Lighting — Chemistry of Gas Manufacture, by Lewis 
 Thompson, Esq., M.R.C.S. — Coal, with Analyses, by J. Paterson, Lewis Thompson, and 
 G. R. Hislop, Esqrs. — Retorts, Iron and Clay — Retort Setting — Hydraulic Main — Con- 
 densers — Exhausters — Washers and Scrubbers — Purifiers — Purification — History of Gas 
 Holder — Tanks, Brick and Stone, Composite, Concrete, Cast-iron, Compound Annular 
 Wrought-iron — Specifications — Gas Holders — Station Meter — Governor — Distribution — 
 Mains — Gas Mathematics, or Formulae for the Distribution of Gas, by Lewis Thompson, Esq. — 
 Services — Consumers’ Meters — Regulators — Burners — Fittings — Photometer — Carburization 
 of Gas — Air Gas and Water Gas — Composition of Coal Gas, by Lewis Thompson, Esq. — 
 Analyses of Gas — Influence of Atmospheric Pressure and Temperature on Gas — Residual 
 Products — Appendix — Description of Retort Settings, Buildings, etc., etc. 
 
 Practical Geometry., Perspective., and Engineering 
 
 Drawing; a Course of Descriptive Geometry adapted to the Require- 
 ments of the Engineering Draughtsman, including the determination of 
 cast shadows and Isometric Projection, each chapter being followed by 
 numerous examples ; to which are added rules for Shading, Shade-lining, 
 etc., together with practical instructions as to the Lining, Colouring, 
 Printing, and general treatment of Engineering Drawings, with a chapter 
 on drawing Instruments. By George S. Clarke, Capt. R.E. Second 
 edition, %vith 21 plates. 2 vols., cloth, loj. (d. 
 
 The Elements of Graphic Statics. By Professor 
 
 Karl Von Ott, translated from the German by G. S. Clarke, Capt. 
 R.E., Instructor in Mechanical Drawing, Royal Indian Engineering 
 College. With 93 illustrations, crown 8vo, cloth, 5^. 
 
 The Principles of Graphic Statics. By George 
 
 Sydenham Clarke, Capt. Royal Engineers. With 112 illustrations. 
 4to, cloth, I2J-. (id. 
 
 Dynamo- Electric Machinery : A Manual for Students 
 
 of Electro-technics. By Silvanus P. Thompson, B.A., D.Sc., Professor 
 of Experimental Physics in University College, Bristol, etc., etc. Illus- 
 trated, 8vo, cloth, 12s. (id. 
 
PUBLISHED BY E. & F. N. SPON. 
 
 9 
 
 The New Formula for Mean Velocity of Discharge 
 
 of Rivers and Canals. By W. R. K utter. Translated from articles in 
 the ‘ Cultur-Ingenieur,’ by Lowis D’A. Jackson, Assoc. Inst. C.E. 
 8vo, cloth, 12S. 6 d. 
 
 Practical Hydraulics ; a Series of Rules and Tables 
 
 for the use of Engineers, etc., etc. By Thomas Box. Fifth edition, 
 numerous plates^ post 8vo, cloth, 5 j. 
 
 A Practical Treatise on the Construction of Hori- 
 zontal and Vertical Waterwheels specially designed for the use of opera- 
 tive mechanics. By William Cullen, Millwright and Engineer. With 
 II plates. Second edition, revised and enlarged, small 4to, cloth, I2s. 6 d. 
 
 Tin: Describing the Chief Methods of Mining, 
 
 Dressing and Smelting it abroad ; with Notes upon Arsenic, Bismuth and 
 Wolfram. By Arthur G. Charleton, Mem. American Inst, of 
 Mining Engineers. With plates, 8vo, cloth, 12s. 6 d. 
 
 Perspective., Explained and Illustrated. By G. S. 
 
 Clarke, Capt. R.E. With illustrations, 8vo, cloth, 3^. Cid. 
 
 The Essential Elements of Practical Mechanics ; 
 
 based on the Principle of Work, designed for Engineering Students. By 
 Oliver Byrne, formerly Professor of Mathematics, College for Civil 
 Engineers. Third edition, with 148 wood engravings, post 8vo, cloth, 
 *js. 6 d. 
 
 Contents : 
 
 Chap. I. How Work is Measured by a Unit, both with and without reference to a Unit 
 of Time — Chap. 2. The Work of Living Agents, the Influence of Friction, and introduces 
 one of the most beautiful Laws of Motion — Chap. J. The principles expounded in the first and 
 second chapters are applied to the Motion of Bodies — Chap. 4. The Transmission of Work by 
 simple Machines — Chap. 5. Useful Propositions and Rules. 
 
 The Practical Millwright and Engineer s Ready 
 
 Reckoner; or Tables for finding the diameter and power of cog-wheels, 
 diameter, weight, and power of shafts, diameter and strength of bolts, etc. 
 By Thomas Dixon. Fourth edition, i2mo, cloth, 3^, 
 
 Breweries and Maltings : their Arrangement, Con- 
 struction, Machinery, and Plant. By G.. ScAMELL, F.R.I.B.A. Second 
 edition, revised, enlarged, and partly rewritten. By F. CoLYER, M.I.C.E., 
 M.I.M.E. With 20 plates, 8vo, cloth, i8j. 
 
 A Practical Treatise on the Manufacture of Starchy 
 
 Glucose, Starch-Sugar, and Dextrine, based on the German of L. Von 
 Wagner, Professor in the Royal Technical School, Buda Pesth, and 
 other authorities. By Julius Frankel ; edited by Robert Hutter, 
 proprietor of the Philadelphia Starch ^ Works. With 58 illustrations, 
 344 pp., 8 VO, cloth, i8j. 
 
lO 
 
 CATALOGUE OF SCIENTIFIC BOOKS 
 
 A Practical Treatise on Mill- gearing, Wheels, Shafts, 
 
 Riggers, etc. ; for the use of Engineers. By Thomas Box. Third 
 edition, with 1 1 plates. Crown 8vo, cloth, *js. 6 d. 
 
 Mining Machinery: a Descriptive Treatise on the 
 
 Machinery, Tools, and other Appliances used in Mining. By G. G. 
 Andre, F.G.S., Assoc. Inst. C.E., Mem. of the Society of Engineers. 
 Royal 4to, uniform with the Author’s Treatise on Coal Mining, cori- 
 .taining 182 plates, accurately drawn to scale, with descriptive text, in 
 2 VOls., cloth, 3/. I2S. 
 
 Contents : 
 
 Machinery for Prospecting, Excavating, Hauling, and Hoisting — Ventilation — Pumping — 
 Treatment of Mineral Products, including Gold and Silver, Copper, Tin, and Lead, Iron 
 Coal, Sulphur, China Clay, Brick Earth, etc. 
 
 Tables for Setting out Curves for Railways, Canals, 
 
 Roads, etc., varying from a radius of five chains to three miles. By A. 
 Kennedy and R. W. Hackwood. Illustrated, 32mo, cloth, 2 s. 6 d. 
 
 The Science and Art of the Manufacture of Portland 
 
 Cement, with observations on some of its constructive applications. With 
 66 illustrations. By Henry Reid, C.E., Author of ‘A Practical 
 Treatise on Concrete,’ etc., etc. 8vo, cloth, i8j‘. 
 
 The Draughtsman s Handbook of Plan and Map 
 
 Drawing; including instructions for the preparation of Engineering, 
 Architectural, and Mechanical Drawings. With numerous illustrations 
 in the text, and 33 plates (15 printed in colours). By G. G. Andre, 
 F.G.S., Assoc. Inst. C.E. 4to, cloth, 9^. 
 
 Contents : 
 
 The Drawing Office and its Furnishings — Geometrical Problems — Lines, Dots, and their 
 Combinations — Colours, Shading, Lettering, Bordering, and North Points — Scales — Plotting 
 — Civil Engineers’ and Surveyors’ Plans — Map Drawing — Mechanical and Architecturzd 
 Drawing — Copying and Reducing Trigonometrical Formulae, etc., etc. 
 
 The Boiler-maker s andiron Ship-builders Companion, 
 
 comprising a series of original and carefully calculated tables, of the 
 utmost utility to persons interested in the iron trades. By James Foden, 
 author of ‘ Mechanical Tables,’ etc. Second edition revised, with illustra- 
 tions, crown 8vo, cloth, ^s. 
 
 Rock Blasting: a Practical Treatise on the means 
 
 employed in Blasting Rocks for Industrial Purposes. By G. G. Andre, 
 F.G.S., Assoc. Inst. C.E. With 56 illustrations and 12 plates, 8vo, cloth, 
 lOj. Csd, 
 
 Painting and Painters Manual: a Book of Fact^ 
 
 for Painters and those who Use or Deal in Paint Materials. By C. L. 
 CoNDiT and J. Scheller. Illustrated, 8vo, cloth, loj. (id. 
 
PUBLISHED BY E. & F. N. SPON. 
 
 II 
 
 A Treatise on Ropemaking as practised in public and 
 
 private Rope-yards^ with a Description of the Manufacture, Rules, Tables 
 of Weights, etc., adapted to the Trade, Shipping, Mining, Railways, 
 Builders, etc. By R. Chapman, formerly foreman to Messrs. Huddart 
 and Co., Limehouse, and late Master Ropemaker to H.M. Dockyard, 
 Deptford. Second edition, i2mo, cloth, 3J. 
 
 Laxtons Builders and Contractors Tables ; for the 
 
 use of Engineers, Architects, Surveyors, Builders, Land Agents, and 
 others. Bricklayer, containing 22 tables, with nearly 30,000 calculations. 
 4to, cloth, 5 j. 
 
 Laxtons Builders and Contractors Tables. Ex- 
 cavator, Earth, Land, Water, and Gas, containing 53 tables, with nearly 
 24,000 calculations. 4to, cloth, 5^. 
 
 Sanitary Engineering: a Guide to the Construction 
 
 of Works of Sewerage and House Drainage, with Tables for facilitating 
 the calculations of the Engineer. By Baldwin Latham, C.E., M. Inst. 
 C.E., F.G.S., F.M.S., Past-President of the Society of Engineers. Second 
 edition, with numerous plates and woodcuts, 8vo, cloth, i/. ioj. 
 
 Screw Cutting Tables for Engineers and Machinists, 
 
 giving the values of the different trains of Wheels required to produce 
 Screws of any pitch, calculated by Lord Lindsay, M.P., F.R.S., F.R.A.S., 
 etc. Cloth, oblong, 2s. 
 
 Screw Cutting Tables, for the use of Mechanical 
 
 Engineers, showing the proper arrangement of Wheels for cutting the 
 Threads of Screws of any required pitch, with a Table for making the 
 Universal Gas-pipe Threads and Taps. By W. A. Martin, Engineer. 
 Second edition, oblong, cloth, u., or sewed, 6d. 
 
 A Treatise on a Practical Method of Designing Slide- 
 
 Valve Gears by Simple Geometrical Construction, based upon the principles 
 enunciated in Euclid’s Elements, and comprising the various forms of 
 Plain Slide-Valve and Expansion Gearing ; together with Stephenson’s, 
 Gooch’s, and Allan’s Link-Motions, as applied either to reversing or to 
 variable expansion combinations. By Edward J. Cowling Welch, 
 Memb. Inst. Mechanical Engineers. Crown 8vo, cloth, 6s. 
 
 Cleaning and Scouring : a Manual for Dyers, Laun- 
 
 dresses, and for Domestic Use. By S. Christopher. i8mo, sewed, 6d. 
 
 A Handbook of House Sanitation ; for the use of all 
 
 persons seeking a Healthy Home. A reprint of those portions of Mr. 
 Bailey-Denton’s Lectures on Sanitary Engineering, given before the 
 School of Military Engineering, which related to the “Dwelling,” 
 enlarged and revised by his Son, E. F. Bailey-Denton, C.E., B.A. 
 With 140 illustrations, 8vo, cloth, Ss. 6d. 
 
12 
 
 CATALOGUE OF SCIENTIFIC BOOKS 
 
 3 
 
 A Glossary of Terms used in Coal Mining, By 
 
 William Stukeley Gresley, Assoc. Mem. Inst. C.E., F.G.S., Member 
 of the North of England Institute of Mining Engineers. Illustrated with 
 numerous woodcuts and diagrams^ crown 8vo, cloth, 5^". 
 
 A Pocket-Book for Boiler Makers and Steam Users, 
 
 comprising a variety of useful information for Employer and Workman, 
 Government Inspectors, Board of Trade Surveyors, Engineers in charge 
 of Works and Slips, Foremen of Manufactories, and the general Steam- 
 using Public. By Maurice John Sexton. Second" edition, royal 
 32mo, roan, gilt edges, 5^. 
 
 The Strains upon Bridge Girders and Roof Trusses, 
 
 including the Warren, Lattice, Trellis, Bowstring, and other Forms of 
 Girders, the Curved Roof, and Simple and Compound Trusses. By 
 Thos. Cargill, C.E.B.A.T., C.D., Assoc. Inst. C.E., Member of the 
 Society of Engineers. With 64 illustrations, drawn and worked out to scale, 
 8vo, cloth, I2S. 6d. 
 
 A Practical Treatise on the Steam Engine, con- 
 taining Plans and Arrangements of Details for Fixed Steam Engines, 
 with Essays on the Principles involved in Design and Construction. By 
 Arthur Rigg, Engineer, Member of the Society of Engineers and of 
 the Royal Institution of Great Britain. Demy 4to, copiously illustrated 
 with woodcuts and 96 plates, in one Volume, half-bound morocco, 2/. 2s . ; 
 or cheaper edition, cloth, 25J. 
 
 This work is not, in any sense, an elementary treatise, or history of the steam engine, hut 
 is intended to describe examples of Fixed Steam Engines without entering into the wide 
 domain of locomotive or marine practice. To this end illustrations will be given of the most 
 recent arrangements of Horizontal, Vertical, Beam, Pumping, Winding, Portable, Semi- 
 portable, Corliss, Allen, Compound, and other similar Engines, by the most eminent Firms in 
 Great Britain and America. The laws relating to the action and precautions to be observed 
 in the construction of the various details, such as Cylinders, Pistons, Piston-rods, Connecting- 
 ^ods,.Cross-heads, Motion- blocks. Eccentrics, Simple, Expansion, Balanced, and Equilibrium 
 Slide-valves, and Valve-gearing will be minutely dealt with. In this connection will be found 
 articles upon the Velocity of Reciprocating Parts and the Mode of Applying the Indicator, 
 Heat and Expansion of Steam Governors, and the like. It is the writer’s desire to draw 
 illustrations from every possible source, and give only those rules that present practice deems 
 correct. 
 
 Barlow s Tables of Sqtiares, Cubes, Square Roots, 
 
 Cube Roots, Reciprocals of all Integer Numbers up to 10,000. Post 8vo, 
 cloth, (is. 
 
 Camus (M.) Treatise on the Teeth of Wheels, demon- 
 strating the best forms which can be given to them for the purposes of 
 Machinery, such as Mill-work and Clock-work, and the art of finding 
 their numbers. Translated from the French, with details of the present 
 practice of Millwrights, Engine Makers, and other Machinists, by 
 Isaac Hawkins. Third edition, with 18 plates, 8vo, cloth, 5^. 
 
PUBLISHED BY E. & F. N. SPON. 
 
 13 
 
 A Practical Treatise on the Science of Land and 
 
 Enginetring Surveying, Levelling, Estimating Quantities, etc., with a 
 general description of the several Instruments required for Surveying, 
 Levelling, Plotting, etc. By H. S. Merrett. Third edition, 41 plates 
 with illustrations and tables, royal 8vo, cloth, 12s. 6d. 
 
 Principal Contents : 
 
 Part I. Introduction and the Principles of Geometry. Part 2. Land Surveying ; com- 
 prising General Observations — The Chain — Offsets Surveying by the Chain only — Surveying 
 Hilly Ground — To Survey an Estate or Parish by the Chain only — Surveying with the 
 Theodolite — Mining and Town Surveying — Railroad Surveying — Mapping — Division and 
 Laying out of Land — Observations on Enclosures — Plane Trigonometry. Part 3. Levelling — 
 Simple and Compound Levelling — The Level Book — Parliamentary Plan and Section — 
 Levelling with a Theodolite — Gradients — ^Wooden Curves — To Layout a Railway Curve- 
 Setting out Widths. Part 4. Calculating Quantities generally for Estimates — Cuttings and 
 Embankments — Tunnels — Brickwork — Ironwork — Timber Measuring. Part 5. Description 
 and Use of Instruments in Surveying and Plotting — The Improved Dumpy Level — Troughton’s 
 Level — The Prismatic Compass — Proportional Compass — Box Sextant — Vernier — Para- 
 graph — Merrett’s Improved Quadrant — Improved Computation Scale — ^The Diagonal Scale — 
 Straight Edge and Sector. Part 6. Logarithms of Numbers — Logarithmic Sines and 
 Co-Sines, Tangents and Co-Tangents — Natural Sines and Co-Sines — Tables for Earthwork, 
 for Setting out Curves, and for various Calculations, etc., etc., etc. 
 
 Saws: the History, Development, Action, Classifica- 
 tion, and Comparison of Saws of all kinds. By Robert Grimshaw. 
 With 220 illustrations, 410, cloth, 12^. 6t/. 
 
 A Supplement to the above ; containing additional 
 
 practical matter, more especially relating to the forms of Saw Teeth for 
 special material and conditions, and to the behaviour of Saws under 
 particular conditions. With 120 illustrations, cloth, <)s. 
 
 A Guide for the Electric Testing of Telegraph Cables. 
 
 By Capt. V. Hoskicer, Royal Danish Engineers. With illustrations, 
 second edition, crown 8vo, cloth, 4^. 6d. 
 
 Laying and Repairing Electric Telegraph Cables. By 
 
 Capt. V. Hoskicer, Royal Danish Engineers. Crown 8vo, cloth, 
 
 3j. 6t/. 
 
 A Pocket-Book of Practical Rules for the Proportions 
 
 of Modern Engines and Boilers for Land and Marine purposes. By N. P. 
 Burgh. Seventh edition, royal 32mo, roan, 4s. 6d. 
 
 The Assayers^ Manual: an Abridged Treatise on 
 
 the Docimastic Examination of Ores and Furnace and other Artificial 
 Products. By Bruno Kerl. Translated by W. T. Brannt. With 65 
 illustrations, 8vo, cloth, I2j. (id. 
 
 The Steam Engine considered as a Heat Engine : a 
 
 Treatise on the Theory of the Steam Engine, illustrated by Diagrams, 
 Tables, and Examples from Practice. By Jas. H. Cotterill, M.A., 
 F.R.S., Professor of Applied Mechanics in the Royal Naval College. 
 8 VO, cloth, I 2 S. 6 d. 
 
NOW COMPLETE. 
 
 With nearly 1500 illustrations^ in super-royal 8vo, in 5 Divisions, cloth. 
 Divisions 1 to 4, 13J. (id. each ; Division 5, \^s. 6 d . ; or 2 vols., cloth, £‘^ loj. 
 
 SPONS’ ENCYCLOPEDIA 
 
 OF THE 
 
 INDUSTRIAL ARTS, MANUFACTURES, AND COMMERCIAL 
 PRODUCTS. 
 
 Edited by C. G. WARNFORD LOCK, F.L.S. 
 
 Among the more important of the subjects treated of, are the 
 following : — 
 
 Acids, 207 pp. 220 figs. 
 Alcohol, 23 pp. 16 figs. 
 Alcoholic Liquors, 13 pp. 
 Alkalies, 89 pp. 78 figs. 
 Alloys, Alum. 
 
 Asphalt. Assaying. 
 
 Beverages, 89 pp. 29 figs. 
 Blacks. 
 
 Bleaching Powder, 1 5 pp. 
 Bleaching, 5 1 pp. 48 figs. 
 Candles, 18 pp. 9 figs. 
 Carbon Bisulphide. 
 Celluloid, 9 pp. 
 
 Cements. Clay. 
 Coal-tar Products, 44 pp. 
 
 14 figs. 
 
 Cocoa, 8 pp. 
 
 Coffee, 32 pp. 13 figs. 
 Cork, 8 pp. 17 figs. 
 Cotton Manufactures, 62 
 PP- 57 figs. 
 
 Drugs, 38 pp. 
 
 Dyeing and Calico 
 Printing, 28 pp. 9 figs. 
 Dyestuffs, 16 pp. 
 Electro-Metallurgy, 13 
 
 pp. 
 
 Explosives, 22 pp. 33 figs. 
 Feathers. 
 
 Fibrous Substances, 92 
 pp. 79 figs. 
 
 Floor-cloth, 16 pp. 21 
 
 figs- 
 
 Food Preservation, 8 pp. 
 Fruit, 8 pp. 
 
 Fur, 5 pp. 
 
 Gas, Coal, 8 pp. 
 
 Gems. 
 
 Glass, 45 pp. 77 figs. 
 Graphite, 7 pp. 
 
 Hair, 7 pp. 
 
 Hair Manufactures. 
 
 Hats, 26 pp. 26 figs. 
 Honey. Hops. 
 
 Horn. 
 
 Ice, 10 pp. 14 figs. 
 Indiarubber Manufac- 
 tures, 23 pp. 1 7 figs. 
 Ink, 17 pp. 
 
 Ivory. 
 
 Jute Manufactures, ii 
 pp., II figs. 
 
 Knitted Fabrics — 
 Hosiery, 15 pp. 13 figs. 
 Lace, 13 pp. 9 figs. 
 Leather, 28 pp. 3 1 figs. 
 Linen Manufactures, 16 
 pp. 6 figs. 
 
 Manures, 2I pp. 30 figs. 
 Matches, 17 pp. 38 figs. 
 Mordants, 13 pp. 
 Narcotics, 47 pp. 
 
 Nuts, 10 pp. 
 
 Oils and Fatty Sub- 
 stances, 125 pp. 
 
 Paint. 
 
 Paper, 26 pp. 23 figs. 
 Paraffin, 8 pp. 6 figs. 
 Pearl and Coral, 8 pp. 
 Perfumes, 10 pp. 
 
 Photography, 13 pp. 20 
 figs. 
 
 Pigments, 9 pp. 6 figs. 
 
 Pottery, 46 pp. 57 figs. 
 
 Printing and Engraving, 
 20 pp. 8 figs. 
 
 Rags. 
 
 Resinous and Gummy 
 Substances, 75 pp. 16 
 figs. 
 
 Rope, 16 pp. 17 figs. 
 
 Salt, 31 pp. 23 figs. 
 
 Silk, 8 pp. 
 
 Silk Manufactures, 9 pp. 
 II figs. 
 
 Skins, 5 pp. 
 
 Small Wares, 4 pp. 
 
 Soap and Glycerine, 39 
 pp. 45 figs. 
 
 Spices, 16 pp. 
 
 Sponge, 5 pp. 
 
 Starch, 9 pp. lo figs. 
 
 Sugar, 155 pp. 134 
 figs. 
 
 Sulphur. 
 
 Tannin, 1 8 pp. 
 
 Tea, 12 pp. 
 
 Timber, 13 pp. 
 
 Varnish, 15 pp. 
 
 Vinegar, 5 pp. 
 
 Wax, 5 pp. 
 
 Wool, 2 pp. 
 
 Woollen Manufactures, 
 58 pp. 39 figs. 
 
 London: E. & F. N. SPON, 125, Strand. 
 
 New York : 35, Murray Street. 
 
Crown 8vo, cloth, with illustrations, 5^-, 
 
 WOEKSHOP EECEIPTS, 
 
 FIRST SERIES. 
 
 By ERNEST SPON. 
 
 Bookbinding. 
 
 Bronzes and Bronzing. 
 
 Candles. 
 
 Cement. 
 
 Cleaning. 
 
 Colourwashing. 
 
 Concretes. 
 
 Dipping Acids. 
 
 Drawing Office Details. 
 
 Drying Oils. 
 
 Dynamite. 
 
 Electro - Metallurgy — 
 (Cleaning, Dipping, 
 Scratch-brushing, Bat- 
 teries, Baths, and 
 Deposits of every 
 description). 
 
 Enamels. 
 
 Engraving on Wood, 
 Copper, Gold, Silver, 
 Steel, and Stone. 
 
 Etching and Aqua Tint. 
 
 Firework Making — 
 (Rockets, Stars, Rains, 
 Gerbes, Jets, Tour- 
 billons, Candles, Fires, 
 Lances, Lights, Wheels, 
 Fire-balloons, and 
 minor Fireworks). 
 
 Fluxes. 
 
 Foundry Mixtures. 
 
 Synopsis of Contents. 
 
 Freezing. 
 
 Fulminates. 
 
 Furniture Creams, Oils, 
 Polishes, Lacquers, 
 and Pastes. 
 
 Gilding. 
 
 Glass Cutting, Cleaning, 
 Frosting, Drilling, 
 Darkening, Bending, 
 Staining, and Paint- 
 ing. 
 
 Glass Making. 
 
 Glues. 
 
 Gold. 
 
 Graining. 
 
 Gums. 
 
 Gun Cotton. 
 
 Gunpowder. 
 
 Horn Working. 
 
 Indiarubber. 
 
 Japans, Japanning, and 
 kindred processes. 
 
 Lacquers. 
 
 Lathing. 
 
 Lubricants. 
 
 Marble Working. 
 
 Matches. 
 
 Mortars. 
 
 Nitro-Glycerine. 
 
 Oils. 
 
 Paper. 
 
 Paper Hanging. 
 
 Painting in Oils, in Water 
 Colours, as well as 
 Fresco, House, Trans- 
 parency, Sign, and 
 Carriage Painting. 
 
 Photography. 
 
 Plastering. 
 
 Polishes. 
 
 Pottery — (Clays, Bodies, 
 Glazes, Colours, Oils, 
 Stains, Fluxes, Ena- 
 mels, and Lustres). 
 
 Scouring. 
 
 Silvering. 
 
 Soap. 
 
 Solders. 
 
 Tanning. 
 
 Taxidermy. 
 
 Tempering Metals. 
 
 Treating Horn, Mother- 
 o’-Pearl, and like sub- 
 stances. 
 
 Varnishes, Manufacture 
 and Use of. 
 
 Veneering. 
 
 Washing. 
 
 Waterproofing. 
 
 Welding. 
 
 Besides Receipts relating to the lesser Technological matters and processes, 
 such as the manufacture and use of Stencil Plates, Blacking, Crayons, Paste, 
 Putty, Wax, Size, Alloys, Catgut, Tunbridge Ware, Picture Frame and 
 Architectural Mouldings, Compos, Cameos, and others too numerous to 
 mention. 
 
 London : E. & F. N. SPON, 126, Strand. 
 
 New York: 36, Murray Street. 
 
Crown 8vo, cloth, 485 pages, with illustrations, 5 j. 
 
 WOEKSHOP 
 
 SECOND 
 
 EECEIPTS, 
 
 SERIES. 
 
 By ROBERT HALDANE. 
 
 Synopsis of Contents. 
 
 Acidimetry and Alkali- 
 metry. 
 
 Albumen. 
 
 Alcohol . 
 
 Alkaloids. 
 
 Baking-powders. 
 
 Bitters. 
 
 Bleaching. 
 
 Boiler Incrustations. 
 Cements and Lutes. 
 Cleansing. 
 
 Confectionery. 
 
 Copying. 
 
 Disinfectants. 
 
 Dyeing, Staining, and 
 Colouring. 
 
 Essences. 
 
 Extracts. 
 
 Fireproofing. 
 
 Gelatine, Glue, and Size. 
 Glycerine. 
 
 Gut. 
 
 Hydrogen peroxide. 
 
 Ink. 
 
 Iodine. 
 
 Iodoform. 
 
 Isinglass. 
 
 Ivory substitutes. 
 Leather. 
 
 Luminous bodies. 
 
 Magnesia. 
 
 Matches. 
 
 Paper. 
 
 Parchment. 
 Perchloric acid. 
 Potassium oxalate. 
 Preserving. 
 
 Pigments, Paint, and Painting : embracing the preparation of 
 Pigments, including alumina lakes, blacks (animal, bone, Frankfort, ivory, 
 lamp, sight, soot), blues (antimony, Antwerp, cobalt, coeruleum, Egyptian, 
 manganate, Paris, Peligot, Prussian, smalt, ultramarine), browns (bistre, 
 hinau, sepia, sienna, umber, Vandyke), greens (baryta, Brighton, Bnmswick, 
 chrome, cobalt, Douglas, emerald, manganese, mitis, mountain, Prussian, 
 sap, Scheele’s, Schweinfurth, titanium, verdigris, zinc), reds (Brazilwood lake, 
 carminated lake, carmine, Cassius purple, cobalt pink, cochineal lake, colco- 
 thar, Indian red, madder lake, red ch^k, red lead, vermilion), whites (alum, 
 baryta, Chinese, lead sulphate, white lead — by American, Dutch, French, 
 German, Kremnitz, and Pattinson processes, precautions in making, and 
 composition of commercial samples — whiting, Wilkinson’s white, zinc white), 
 yellows (chrome, gamboge, Naples, orpiment, realgar, yellow lakes) \ Faint 
 (vehicles, testing oils, driers, grinding, storing, applying, priming, dr}dng, 
 filling, coats, brushes, surface, water-colours, removing smell, discoloration ; 
 miscellaneous paints — cement paint for carton-pi erre, copper paint, gold paint, 
 iron paint, lime paints, silicated paints, steatite paint, transparent paints, 
 tungsten paints, window paint, zinc paints) ; Painting (general instructions, 
 proportions of ingredients, measuring paint work ; carriage painting — priming 
 paint, best putty, finishing colour, cause of cracking, mixing the paints, oils, 
 driers, and colours, varnishing, importance of washing vehicles, re- varnishing, 
 how to dry paint ; woodwork painting). 
 
 London: E. &; F. N. SPON, 126, Strand. 
 
 New York: 36, Murray Street. 
 

 Crown 8 VO, cloth, 480 pages, with 183 illustrations, 5 ^. 
 
 WOEKSHOP EECEIPTS, 
 
 THIRD SERIES. 
 
 By C. G. WARNFORD LOCK. 
 
 Uniform with the First and Second Series. 
 
 Synopsis of Contents. 
 
 Alloys. 
 
 Indium. 
 
 Rubidium. 
 
 Aluminium. 
 
 Iridium. 
 
 Ruthenium. 
 
 Antimony. 
 
 Iron and Steel. 
 
 Selenium. 
 
 Barium. 
 
 Lacquers and Lacquering. 
 
 Silver. 
 
 Beryllium. 
 
 Lanthanum. 
 
 Slag. 
 
 Bismuth. 
 
 Lead. 
 
 Sodium. 
 
 Cadmium. 
 
 Lithium. 
 
 Strontium. 
 
 Caesium. 
 
 Lubricants. 
 
 Tantalum. 
 
 Calcium. 
 
 Magnesium. 
 
 Terbium. 
 
 Cerium. 
 
 Manganese. 
 
 Thallium. 
 
 Chromium. 
 
 Mercury. 
 
 Thorium. 
 
 Cobalt. 
 
 Mica. 
 
 Tin. 
 
 Copper. 
 
 Molybdenum. 
 
 Titanium. 
 
 Didymium. 
 
 Nickel. 
 
 Tungsten. 
 
 Electrics. 
 
 Niobium. 
 
 Uranium. 
 
 Enamels and Glazes. 
 
 Osmium. 
 
 Vanadium. 
 
 Erbium. 
 
 Palladium. 
 
 Yttrium. 
 
 Gallium. 
 
 Platinum. 
 
 Zinc. 
 
 Glass. 
 
 Potassium. 
 
 Zirconium. 
 
 Gold. 
 
 Rhodium. 
 
 
 London : E. (& F. N. SPON, 1S6, Strand 
 
 New York : 35, Murray Street. 
 
JUST FXJBLISHEO. 
 
 In demy 8vo, cloth, 600 pages, and 1420 Illustrations, 6 s. 
 
 SPONS’ 
 
 MECHANIC’S OWN BOOK; 
 
 A MANUAL FOR HANDICRAFTSMEN AND AMATEURS. 
 
 Contents. 
 
 Mechanical Drawing — Casting and Founding in Iron, Brass, Bronze, 
 and other Alloys — Forging and Finishing Iron — Sheetmetal Working 
 — Soldering, Brazing, and Burning — Carpentry and Joinery, embracing 
 descriptions of some 400 Woods, over 200 Illustrations of Tools and 
 their uses. Explanations (with Diagrams) of 116 joints and hinges, and 
 Details of Construction of Workshop appliances, rough furniture. 
 Garden and Yard Erections, and House Building — Cabinet-Making 
 and Veneering — Carving and Fretcutting — Upholstery — Painting, 
 Graining, and Marbling — Staining Furniture, Woods, Floors, and 
 Fittings — Gilding, dead and bright, on various grounds — Polishing 
 Marble, Metals, and Wood — Varnishing — Mechanical movements, 
 illustrating contrivances for transmitting motion — Turning in Wood 
 and Metals — Masonry, embracing Stonework, Brickwork, Terracotta, 
 and Concrete — Roofing with Thatch, Tiles, Slates, Felt, Zinc, &c. — 
 Glazing with and without putty, and lead glazing — Plastering and 
 Whitewashing — Paper-hanging — Gas-fitting — Bell-hanging, ordinary 
 and electric Systems — Lighting — W arming — V entilating — Roads, 
 Pavements, and Bridges — Hedges, Ditches, and Drains — Water 
 Supply and Sanitation— Hints on House Construction suited to new 
 countries. 
 
 London : E. & F. N. SPON, 126, Strand. 
 
 New York : 35, Murray Street. 
 
S XJ Xj E E 3Sr T 
 
 TO 
 
 E. & F. N. SPON’S 
 
 CATALOGUE OF BOOKS. 
 
 Canoes and Boats. ^ 
 
 Canoe and Boat Building : a complete Manual for Amateurs, 
 containing plain and comprehensive directions for the con- 
 struction of Canoes, Rowing and Sailing Boats, and Hunting 
 Craft, by W. P. Stephens, with numerous illustrations and 
 24 plates of Working Drawings^ crown 8vo, cloth 0 
 
 Colonial Agriculture. 
 
 Cultural Industries for Queensland : Papers on the cultivation 
 of useful Plants suited to the climate of Queensland, their 
 value as Food, in the Arts, and in Medicine, and methods of 
 obtaining their products, by L. A. Bernays, F.L.S., F.R.G.S., 
 
 8vo, half calf 0 7 6 
 
 The same, in cloth 0 6 0 
 
 Electricians’ Conference. 
 
 Proceedings of the National Conference of Electricians, Phila- 
 delphia, October 8th to 13th, 1884, i8mo, cloth 0 3 0 
 
 Electricity. 
 
 Dynamo- Electricity, its Generation, Application, Transmis- 
 sion, Storage, and Measurement, by G. B. Prescott, with 
 545 illustrations, 8vo, cloth 110 
 
 Electricity in the House. 
 
 Domestic Electricity for Amateurs, translated from the French 
 of E. Hospitaller, Editor of “ L’Electricien,” by C. J. Wharton, 
 
 Assoc. Soc. Tel. Eng., numerous illustrations, demy8vo, cloth 0 9 0 
 Contents : 
 
 I. Production of the Electric Current — 2. Electric Bells — 3. Automatic Alarms — 4. Domestic 
 Telephones— 5. Electric Clocks — 6. Electric Lighters — 7. Domestic Electric Lighting — 
 8. Domestic Application of the Electric Light — 9. Electric Motors — 10. Electrical Locomo- 
 tion — II. Electrotyping, Plating, and Gilding — 12. Electric Recreations — 13. Various appli- 
 cations — Workshop of the Electrician. 
 
 Electric Lighting. 
 
 Wrinkles in Electric Lighting, by Vincent Stephen, zvith 
 illustrations, i8mo, cloth 0 2 6 
 
 Contents : 
 
 I. The Electric Current and its production by Chemical means — 2. Production of Electric 
 Currents by Mechanical means — 3. Dynamo-Electric Machines — 4. Electric Lamps — 
 5. Lead — 6. Ship Lighting. 
 
 s. d. 
 
 7 6 
 
22 
 
 Supplement to E. & F. N. Spon’s 
 
 Flax Spinning. ^ 
 
 The Practical Flax Spinner ; being a Description of the 
 Growth, Manipulation, and Spinning of Flax and Tow, by 
 Leslie C. Marshall, of Belfast, with illustrations^ 8vo, cloth C 
 
 Foundations. 
 
 Foundations and Foundation Walls for all classes of Buildings, 
 Pile Driving, Building Stones and Bricks, Pier and Wall 
 construction. Mortars, Limes, Cements, Concretes, Stuccos, 
 &c., 64 illustrations, by G. T. Powell and F. Bauman, 8vo, 
 cloth ( 
 
 Free Trade. 
 
 The British Jugernath. Free Trade! Fair Trade!! Reci- 
 procity ! ! ! and Retaliation ! ! ! ! by G. L. M., 8vo, sewed ( 
 
 Gas. 
 
 Manual for Gas Engineering Students, by D. Lee, i8mo, cloth ( 
 
 Hydraulic Machinery. 
 
 Hydraulic Machinery, Past and Present. A Lecture delivered 
 to the London^ and Suburban Railway Officials’ Association, 
 by H. Adams, Mem. Inst. C. Y.., folding plate, 8vo, sewed ( 
 
 Indicator. 
 
 Twenty Years with the Indicator, by Thomas Pray, Jun., 
 C.E., M.E., Member of the American Society of Civil 
 Engineers, 2 vols., royal 8vo, cloth C 
 
 Iron Trade. 
 
 Annual Statistical Report of the Secretary to the Members of 
 the Iron and Steel Association on the Home and Foreign 
 Iron and Steel Industries in 1884. Issued March 1885. 8vo, 
 sewed C 
 
 Locomotive. 
 
 Locomotive Engine Running and Management ; a Treatise 
 on Locomotive Engines, showing their performance in running 
 different kinds of trains with economy and dispatch, also 
 directions regarding the care, management, and repairs of 
 Locomotives and all their connections, by Augustus Sinclair, 
 crown 8vo, cloth 0 
 
 Machinist’s Calculator. 
 
 The Machinist’s and Steam Engineer’s Practical Calculator, 
 a compilation of useful Rules and Problems arithmetically 
 solved, together with general information applicable to Shop- 
 tools, Mill-gearing, Pulleys and Shafts, Steam Boilers, and 
 Engines, by D. B. Dixon, royal 32mo, roan, vermilion edges 0 
 
 Ordnance. 
 
 The new Gun-System — Longridge, or the use of Wire in the 
 Manufacture of Guns. A Lecture read at Coblence, Jan. 23rd, 
 1885, by Callegberg, Captain and Chief of Battery ist 
 Rhenish Field Artillery, Regiment No. 8, 8vo, sewed 0 
 
 s. d. 
 15 0 
 
 10 6 
 
 0 6 
 1 0 
 
 1 0 
 
 12 G 
 
 5 0 
 
 7 G 
 
 9 0 
 1 0 
 
Catalogue of Books. 
 
 23 
 
 Plumbing. 
 
 Standard Practical Plumbing, being a complete Encyclopaedia 
 for Practical Plumbers and Guide for Architects, Builders, 
 Gas Fitters, Hot- water Fitters, Ironmongers, Lead Burners, 
 Sanitary Engineers, Zinc Workers, &c., illustrated by over 
 2000 engravings, by P. J. Davies. Vol. i, royal 8vo, cloth 
 
 Pneumatic Transmission. 
 
 Pneumatic Transmission of Messages and Parcels between 
 Paris and London, via Calais and Dover, by J. B. Berlier, 
 C.E., small folio, sewed 
 
 Reagents. 
 
 List of Tests (Reagents) arranged in alphabetical order, 
 according to the names of the originators. Designed especially 
 for the convenient reference of Chemists, Pharmacists, and 
 Scientists, by Hans M. Wilder, crown 8vo, cloth 
 
 Rivers Pollution. 
 
 Address on River Pollution, delivered at the Parkes Museum 
 of Hygiene, by Professor Henry Robinson, Mem. Inst. C.E., 
 8vo, sewed 
 
 Sanitary Engineering. 
 
 Hand-book of Sanitary Information for Householders, con- 
 taining facts and suggestions about Ventilation, Drainage, 
 care of Contagious Diseases, Disinfection, Food and Water, 
 with appendices on Disinfectants and Plumbers, by Roger 
 S. Tracy, M.D., Sanitary Inspector, New York City, i8mo, 
 cloth 
 
 Sanitary Engineering. 
 
 Women, Plumbers, and Doctors, or Household Sanitation, 
 by Mrs. H. M. Plunkett, showing that if Women and 
 Plumbers do their whole sanitary duty there will be compara- 
 tively little occasion for the services of the Doctor, illustrated, 
 crown 8vo, cloth 
 
 Sewage. 
 
 Ten Years’ Experience in Works of Intermittent Downward 
 Filtration, by J. Bailey Denton, Mem. Inst. C.E., second 
 edition, with additions, royal 8vo, sewed 
 
 Sewage. 
 
 Some recent phases of the Sewage question, with remarks on 
 “Ensilage,” as applied to the storing and preservation of 
 Sewage-grown Green Crops, by Henry Robinson, Mem. Inst. 
 C.E., 8vo, sewed 
 
 Soap. 
 
 A Treatise on the Manufacture of Soap and Candles, Lubri- 
 cants and Glycerin, by W. Lant Carpenter, B.A., B.Sc. (late 
 of Messrs. C. Thomas and Brothers, Bristol), with illustrations, 
 crown 8vo, cloth ' 
 
 Society of Engineers. 
 
 Transactions of the Society of Engineers for 1884, 8vo, cloth 
 
 s. d. 
 
 5 0 
 0 6 
 
 4 6 
 1 0 
 
 2 6 
 
 6 0 
 4 0 
 
 1 0 
 
 10 6 
 10 6 
 
24 Supplement to E. & F. N. Spon’s Catalogue of Books. 
 
 Shipbuilding. ^ 
 
 The^Stability of Ships explained simply, and calculated by a 
 
 new Graphic method, by J. C. Spence, M.I.N.A., 410, sewed 0 3 6 
 
 Steam Boilers. 
 
 Steam Making, or Boiler Practice, by Charles A. Smith, C.E., 
 
 8vo, cloth 090 
 
 Contents : 
 
 I. The Nature of Heat and the Properties of Steam — 2. Combustion — 3. Externally Fired 
 Stationary Boilers — 4. Internally Fired Stationary Boilers — 5. Internally Fired Portable 
 Locomotive and Marine Boilers — 6. Design, Construction, and Strength of Boilers — 7. Pro- 
 portions of Heating Surface, Economic Evaporation, Explosions — 8. Miscellaneous Boilers, 
 Choice of Boiler Fittings and Appurtenances. 
 
 Steam Boilers. 
 
 The Fireman’s Guide ; a Handbook on the care of Boilers, 
 by Teknolog. foreningen T. I. Stockholm, translated from 
 the third edition, and revised by Karl P. Dahlstrom, M.E., 
 second edition, fcap. 8vo, cloth 0 2 0 
 
 Steam Engine. 
 
 A Treatise on Modern Steam Engines and Boilers, including 
 Land Locomotive, and Marine Engines and Boilers, for the 
 use of Students, by Frederic Colyer, M. Inst. C.E., Mem. Inst. 
 
 M.E., with 36 plates^ 4to, cloth {Nearly ready.) 
 
 Contents : 
 
 I. Introduction — 2. Original Engines — 3. Boilers — 4. High-Pressure Beam Engines — 5. 
 Cornish Beam Engines — 6. Horizontal Engines — 7. Oscillating Engines — 8. Vertical High- 
 Pressure Engines — 9. Special Engines — 10. Portable Engines— ii. Locomotive Engines — 
 12. Marine Engines. 
 
 Steam Engine. 
 
 Steam-engine Management ; a Treatise on .the Working and 
 Management of Steam Boilers, by F. Colyer, M. Inst. C.E., 
 
 Mem. Inst. M.E., i8mo, cloth 0 
 
 Surveying. 
 
 Land Surveying on the Meridian and Perpendicular System, 
 by William Penman, C.E., 8vo, cloth 0 
 
 Surveying. 
 
 The Topographer, his Instruments and Methods, designed for 
 the use of Students, Amateur Photographers, Surveyors, 
 Engineers, and all persons interested in the location a,nd con- 
 struction of works based upon Topography, illustrated with 
 numerous plates^ maps., and engravings, by Lewis M. Haupt, 
 
 A.M., 8vo, cloth 0 
 
 Tanning. 
 
 A Text-Book of Tanning, embracing the preparation of all 
 kinds of Leather, by Harry R. Proctor, F.C.S., of Low Lights 
 Tanneries, with illustrations, crown 8vo, cloth {Nearly ready.) 
 
 War Ships. 
 
 War Ships and Navies of the World, by J. W. King, Chief 
 Engineer, U.S.A., new edition, revised {^In preparation.') 
 
 2 0 
 8 6 
 
 18 0 
 
 London : 125, Strand. New York : 35, Murray Street.