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THE TELEPHONE 
 THE MICROPHONE AND THE PHONOGRAPH 
 
THE TELEPHONE 
 
 THE MICROPHONE AND THE PHONOGRAPH 
 
 BY COUNT DU MONCEL 
 
 ' i 
 MEMBRE DE L'lNSTITUT 
 
 AUTHORIZED TRANSLATION 
 WITH ADDITIONS AND CORRECTIONS BY THE AUTHOR 
 
 WITH 70 ILLUSTRATIONS ON WOOD 
 
 LIIU4A U : 
 
 UNIVERSITY 
 
 < 
 
 NEW YORK 
 
 HARPER & BROTHERS, PUBLISHERS 
 
 FRANKLIN SQUARE 
 
 1879 
 
/313S 
 
CONTENTS. 
 
 Page 
 
 History of the Telephone 11 
 
 MUSICAL TELEPHONES. 
 
 Reiss's Telephone. .. 18 
 
 Wray's Telephone 21 
 
 Electric Harmonica 23 
 
 Gray's Telephone 26 
 
 Pollard and Garnier's Singing Condenser 29 
 
 SPEAKING -TELEPHONES. 
 
 String Telephones 33 
 
 Bell's Electric Telephone 36 
 
 Gray's Share in Invention of Telephone 56 
 
 FUNDAMENTAL PRINCIPLES OF BELL TELEPHONE. 
 
 Explanation of Principles 60 
 
 ORDINARY ARRANGEMENT OF BELL TELEPHONE. 
 
 Description and Illustrations . 63 
 
 BATTERY TELEPHONES. 
 
 Edison's Telephone. , 72 
 
 Edison's Chemical Telephone 76 
 
 Navez's Telephones 78 
 
 Pollard and Garnier's Telephones 81 
 
 Hellesen's Telephone 83 
 
6 CONTENTS. 
 
 Page 
 
 Thomson and Houston's Telephone 84 
 
 Telephones with Liquid Senders 86 
 
 Telephones with Voltaic Arcs 88 
 
 Mercury Telephones 90 
 
 Friction Telephones 93 
 
 MODIFICATION OF BELL TELEPHONES. 
 
 Telephones with several Diaphragms 94 
 
 Gray's System 95 
 
 Phelps's System 96 
 
 Cox Walker's System 98 
 
 Trouve's System 99 
 
 Demoget's System 101 
 
 M'Tighe's Telephone 101 
 
 Modifications of Telephonic Organs 102 
 
 Righi's System 103 
 
 Ader's System 105 
 
 Jorgenson's System 106 
 
 EXPERIMENTS WITH THE TELEPHONE. 
 
 On the Effects of Voltaic and Induced Currents 107 
 
 On the Effects of different Telephonic Organs Ill 
 
 Edison's Experiments 112 
 
 Canestrelli's Experiments 114 
 
 Hughes's and Roy's Experiments 114 
 
 Breguet's Experiments 119 
 
 Luvini's Experiments , 119 
 
 Warwick's Experiments 121 
 
 Experiments on the Effects of Mechanical Shocks 123 
 
 Des Portes's Experiments 123 
 
 Thompson's Experiments 125 
 
 Theory of the Telephone 126 
 
CONTENTS. 7 
 
 Page 
 
 Nature of Vibrations 126 
 
 Action of Diaphragm 129 
 
 Action of Magnet 131 
 
 Action 6f Currents 133 
 
 Wiesendanger's Thermophone 134 
 
 OTHER EXPERIMENTS WITH THE TELEPHONE. 
 
 D'Arsonval's Experiments 136 
 
 Eick's Experiments 138 
 
 Demoget's Experiments 138 
 
 Sensitiveness of Telephone. . , 140 
 
 Hellesen's Experiments 141 
 
 Zetsche's Experiments v , 142 
 
 THE MICROPHONE. 
 
 History of the Microphone 143 
 
 Different Systems 146 
 
 Hughes's Microphone 147 
 
 Gaiffe's System 148 
 
 Carette's System 149 
 
 Ducretet's System. 150 
 
 Ducretet's Speaker 151 
 
 Boudet's Speaker 152 
 
 Gaiffe's Thermoscope 154 
 
 Blyth's System 155 
 
 Microphone as a Speaking Instrument 156 
 
 Hughes's System 157 
 
 Other Arrangements of Microphones 159 
 
 Varey's and Trouve's Microphones 161 
 
 Lippens's Microphone 162 
 
 Hughes's Experiments 164 
 
 Hughes's Theory... . 166 
 
8 CONTENTS. 
 
 Page 
 
 Microphone used as Thermoscope 169 
 
 Edison's Thermoscope 170 
 
 Experiments in London 170 
 
 Experiment at Bellinzona 172 
 
 APPLICATIONS OF THE MICROPHONE. 
 
 Its Application to Scientific Research 175 
 
 Application to Telephonic Relays 177 
 
 Application to Surgery. 179 
 
 Various Applications 182 
 
 EXTERNAL INFLUENCE ON TELEPHONIC TRANSMISSIONS. 
 
 Disturbing Influences 183 
 
 Confusion of Circuits 185 
 
 Induced Reactions 187 
 
 Mr. Preece's Suggestions 188 
 
 Effects of Heat and Moisture 191 
 
 ESTABLISHMENT OF TELEPHONE STATION. 
 
 Pollard and Garnier's System 193 
 
 Breguet and Roosevelt's System 195 
 
 Edison's System 199 
 
 CALL-BELLS AND ALARUMS. 
 
 Weinhold's System 201 
 
 Dutertre and Gouault's System 203 
 
 Puluj's System 205 
 
 Chiddey's System 205 
 
 APPLICATIONS OF THE TELEPHONE. 
 
 
 
 Its Application to Simultaneous Transmissions 207 
 
 Bell's System 209 
 
CONTENTS. 9 
 
 Page 
 
 Lacour's System 212 
 
 Gray's System 218 
 
 VARIOUS USES OF THE TELEPHONE. 
 
 Its Use in Offices 224 
 
 Its Use in Telegraphic Service 225 
 
 Its Application to Military Purposes 227 
 
 Its Application to Industry 231 
 
 Its Application to Scientific Research 231 
 
 THE PHONOGRAPH. 
 
 Edison's Patent : 235 
 
 Description of Phonograph , 240 
 
 Several Systems 246 
 
 Theory of Phonograph 250 
 
 USES OF THE PHONOGRAPH. 
 
 Account by Edison 255 
 
 Lambrigot's System 259 
 
 FABER'S SPEAKING MACHINE.. . 261 
 
 APPENDIX. 
 
 Perrodon's System of Telephonic Alarum 269 
 
 Yarey's Microphone Speaker 270 
 
 Fitch's Microphone Speaker 270 
 
 Theory of Telephone 270 
 
 Pollard's Microphone 272 
 
 Ader's Electrophone 273 
 
 Gower's New Telephone 273 
 
 Transmission of Speech by Telephones without Diaphragm 275 
 
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 THE TELEPHONE, ETC 
 
 HISTORY OF THE TELEPHONE. 
 
 STRICTLY speaking, the telephone is merely an instrument 
 adapted for the transmission of sound to a distance, and this 
 idea of transmitting sound is as old as the world itself. The 
 Greeks made use of means which might effect it, and there is 
 no doubt that these means were sometimes used for the pagan 
 oracles. But such transmission of sound was within some- 
 what narrow limits, and certainly did not exceed those of a 
 speaking-tube. Mr. Preece considers that the earliest document 
 in which this transmission of sound to a distance is distinctly 
 formulated dates from 1667 : he refers to a paper by one Rob- 
 ert Hooke, who writes to this effect : " It is not impossible to 
 hear a whisper at a furlong's distance, it having been already 
 done ; and perhaps the nature of the thing would not make it 
 more impossible, though that furlong should be ten times mul- 
 tiply'd. And though some famous authors have affirm'd it im- 
 possible to hear through the thinnest plate of Muscovy glass; 
 yet I know a way by which 'tis easie enough to hear one 
 speak through a wall a yard thick. It has not yet been thor- 
 oughly examin'd how far otacousticons may be improv'd, nor 
 what other wayes there may be of quickning our hearing, or 
 conveying sound through other bodies than the air; for that 
 that is not the only medium, I can assure the reader that I 
 have, by the help of a distended wire, propagated the sound to 
 a very considerable distance in an instant, or with as seemingly 
 
12 THE TELEPHONE. 
 
 quick a motion as that of light, at least incomparably quicker 
 than that which at the same time was propagated through the 
 air; and this not only in a straight line or direct, but in one 
 bended in many angles." 
 
 This plan for the transmission of sound is the principle of 
 the string telephones which have attracted attention for some 
 years, and it remained in the stage of simple experiment until 
 1819, when Sir Charles Wheatstone applied it to his magic 
 lyre. In this instrument sounds were transmitted through a 
 long strip of deal, with one end in connection with a sounding- 
 board : one step more led to the use of the membrane em- 
 ployed in string telephones. It would be difficult to say with 
 whom this idea originated, since it is claimed, as if beyond 
 dispute, by several telephone-makers. If we may believe some 
 travellers, it has long been used in Spain for the correspond- 
 ence of lovers. However this may be, it was not to be found 
 among the scientific appliances of some years ago, and it was 
 even supposed by many persons that the cord consisted of an 
 acoustic tube of slender diameter. Although the instrument 
 has become a child's toy, it has great scientific importance, 
 for it proves that vibrations capable of reproducing speech 
 may be extremely minute, since they can be mechanically 
 transmitted more than a hundred yards. 
 
 From the telegraphic point of view, however, the problem 
 of transmitting sounds to a distance was far from being solved 
 in this way, and the idea of applying electricity to this mode 
 of transmission naturally arose as soon as the wonderful effects 
 of electric telegraphy were observed, that is, in the years sub- 
 sequent to 1839. A surprising discovery made in America by 
 Mr. Page, in 1837, and afterward investigated by MM. Wert- 
 heim, De la Rive, and others, must also have led up to it ; for 
 it was observed that a magnetic bar could emit sounds when 
 rapidly magnetized and demagnetized ; and these sounds cor- 
 responded with the number of currents which produced them. 
 
ELECTRIC TRANSMISSION OF SOUND. 13 
 
 Again, the electric vibrators devised by MM. Macaulay, Wagner, 
 Neef, etc., and adapted to produce musical sounds, between 
 1847-1852, by MM. Frornent and Petrina, showed that the 
 problem of transmitting sounds to a distance was not insolu- 
 ble. Yet, up to 1854, no one had ventured to admit the pos- 
 sibility of transmitting speech by electricity; and when M. 
 Charles Bourseul published, in that year, a paper on the elec- 
 tric transmission of speech, the idea was regarded as a fanciful 
 dream. I confess that I myself thought it incredible ; and when 
 I produced the paper in the first edition of my account of the 
 applications of electricity, published in 1854, 1 felt bound to 
 add that the scheme seemed more than doubtful. Yet, as the 
 paper was thoughtfully written, I had no hesitation in publish- 
 ing it, affixing the signature of CH. B. Events justified this 
 daring idea ; and although it did not include the only principle 
 which could lead to the reproduction of articulate sounds, yet 
 it was the germ of the fertile invention which has made the 
 names of Graham Bell and Elisha Gray famous. For this rea- 
 son I will again quote M. Charles Bourseul's paper. 
 
 "After the telegraphic marvels which can reproduce at a 
 distance handwritings, or even more or less complicated draw- 
 ings, it may appear impossible to penetrate farther into the 
 region of the marvellous. Yet we will try to advance a few 
 steps farther. I haye, for example, asked myself whether 
 speech itself may not be transmitted by electricity in a word, 
 if what is spoken in Vienna may not be heard in Paris. The 
 thing is practicable in this way: 
 
 " We know that sounds are made by vibrations, and are 
 adapted to the ear by the same vibrations which are reproduced 
 by the intervening medium. But the intensity of the vibra- 
 tions diminishes very rapidly with the distance : so that it is, 
 even with the aid of speaking-tubes and trumpets, impossible 
 to exceed somewhat narrow limits. Suppose that a man speaks 
 near a movable disk, sufficiently flexible to lose none of the 
 
14 THE TELEPHONE. 
 
 vibrations of the voice, that this disk alternately makes and 
 breaks the currents from a battery : you may have at a dis- 
 tance another disk, which will simultaneously execute the same 
 vibrations. 
 
 " It is true that the intensity of the sounds produced will be 
 variable at the point of departure, at which the disk vibrates 
 by means of the voice, and constant at the point of arrival, 
 where it vibrates by means of electricity; but it has been 
 shown that this does not change the sounds. It is, moreover, 
 evident that the sounds will be reproduced at the same pitch. 
 
 " The present state of acoustic science does not permit us to 
 declare a priori if this will be precisely the case with syllables 
 uttered by the human voice. The mode in which these sylla- 
 bles are produced has not yet been sufficiently investigated. It 
 is true that we know that some are uttered by the teeth, others 
 by the lips, and so on ; but this is all 
 
 "However this may be, observe that the syllables can only 
 reproduce upon the sense of hearing the vibrations of the in- 
 tervening medium : reproduce precisely these vibrations, and 
 you will reproduce precisely these syllables. 
 
 " It is, at all events, impossible, in the present condition of 
 science, to prove the impossibility of transmitting sound by 
 electricity. Everything tends to show, on the contrary, that 
 there is such a possibility. When the application of electro- 
 magnetism to the transmission of messages was first discussed, 
 a man of great scientific attainments treated the idea as Utopi- 
 an, and yet there is now direct communication between Lon- 
 don and Vienna by means of a simple wire. Men declared it 
 to be impossible, but so it is. 
 
 " It need not be said that numerous applications of the high- 
 est importance will immediately arise from the transmission of 
 speech by electricity. Any one who is not deaf and dumb may 
 use this mode of transmission, which would require no appa- 
 ratus except an electric battery, two vibrating disks, and a 
 
APPLICATION OF ELECTRICITY. 15 
 
 wire. In many cases, as for example in large establishments, 
 orders might be transmitted in this way, although transmission 
 by electricity will not be used while it is necessary to go from 
 letter to letter, and to make use of telegraphs which require use 
 and apprenticeship. However this may be, it is certain that, 
 in a more or less distant future, speech will be transmitted by 
 electricity. / have made some experiments in this direction : 
 they are delicate, and demand timo and patience, but the ap- 
 proximations obtained promise a favorable result." 
 
 This description is certainly not full enough to enable us to 
 discern from it the arrangement which would lead to the solu- 
 tion of the problem, and if the vibrations of the disk at the re- 
 ceiving-station were to follow from making and breaking the 
 current at the sending-station, under the influence of vibrations 
 caused by the voice, they would only produce musical, and not 
 articulate sounds. Yet the idea was magnificent, as Mr. Preece 
 said, even when he thought it impossible to realize it. Besides, 
 it is easy to see that M. Bourseul himself was not deceived as 
 to the difficulties of the problem, as far as articulate sounds are 
 concerned, for he points out, as we have seen, the difference 
 existing between the simple vibrations which produce musi- 
 cal sounds, and the complex vibrations which cause articulate 
 sounds ; but, as he justly said, " Reproduce at the one end of 
 the line the vibrations of air caused at the other, and speech 
 will be transmitted, however complex the mechanism may be 
 by which it is effected." We shall presently see how the 
 problem was solved, and it is probable that some attempts had 
 already enabled M. Bourseul to anticipate the solution of the 
 question ; but there is nothing in his paper to show what were 
 the means he proposed, so that the discovery of the electric 
 transmission of speech cannot reasonably be ascribed to him, 
 and we do not understand why we should be reproached for 
 having at that time failed to appreciate the importance of a dis- 
 covery which seemed to be then only within the range of fancy. 
 
16 THE TELEPHONE. 
 
 It was not until 1876 that the problem of the electric trans- 
 mission of speech was finally solved ; and the discovery has late- 
 ly given rise to an interesting controversy as to priority be- 
 tween Mr. Elisha Gray, of Chicago, and Mr. Graham Bell, on 
 which we must say a few words. 
 
 As early as 1874 Mr. Elisha Gray was occupied with a sys- 
 tem of musical telephone, which he wished to apply to mani- 
 fold telegraphic transmissions, and the investigations which he 
 made, in order to establish this system under the best possible 
 conditions, gave him a glimpse of the possibility of transmit- 
 ting articulate words by electricity. While carrying on his ex- 
 periments on the telegraphic system, he arranged, in fact, about 
 the 15th January, 1876, a system of speaking telephone, and he 
 deposited the specification and drawings in the American Pat- 
 ent Office, in the form of a caveat or provisional specification. 
 The deposit was made on the 14th February, 1876: on the 
 very same day Mr. Graham Bell also deposited, in the Amer- 
 ican Patent Office, a request for a patent in which he spoke of 
 an instrument of the same kind, but with special application to 
 simultaneous telegraphic transmissions by means of a telephon- 
 ic apparatus ; and the few words which could, in this specifica- 
 tion, refer to a telephone with articulate sounds, applied to an 
 instrument which, by Mr. Bell's own admission, had not pro- 
 duced any satisfactory results. In Mr. Gray's caveat, on the 
 contrary, the application of the instrument to the electric trans- 
 mission of speech alone is indicated, the description of the sys- 
 tem is complete, and the drawings which accompany it are so 
 exact that a telephone made from them would work perfectly : 
 this was proved by Mr. Gray himself, when, some time after- 
 ward, he finished his instruments, which differed in no respect 
 from the one described in Mr. Bell's statement as worked by a 
 battery. On these grounds Mr. Elisha Gray would certainly 
 have obtained the patent, if the expiration of his caveat had 
 not been the result of an omission of form in the Patent Office, 
 
17 
 
 which, as we know, decides the priority of inventions in Amer- 
 ica. An action on the ground of this omission has lately been 
 brought against Mr. Bell, in the Supreme Court of the Amer- 
 ican Patent Office, to set aside the patent granted to him. If 
 Mr. Gray did not appeal before, it was because he was then 
 wholly occupied with experiments on the system of harmonic 
 telephone, applied to telegraphic communication, and he had 
 no time to attend to the matter. 
 
 However this may be, Mr. Bell did not begin to give serious 
 attention to the speaking telephone until he had obtained his 
 patent, and his efforts were soon crowned with success : a few 
 months later he exhibited his speaking telephone at Philadel- 
 phia, which has from that time attracted so much public atten- 
 tion, and which, when perfected in a practical point of view, 
 reached Europe in the autumn of 1877 under the form we 
 know. 
 
 To complete this summary account of the telephone, we 
 ought to say that since its success a good many claims of pri- 
 ority have arisen, as if by enchantment. Mr. John Camack, 
 of English origin, has among others claimed the invention of 
 the telephone, not merely relying on the description he gave of 
 the instrument in 1865, but on the drawings he executed; he 
 even adds, that if he had not lacked means for its construction, 
 this would have been the date of the discovery of the tele- 
 phone. A similar pretension has been put forward by Mr. 
 Dolbear, a fellow-cotfntryman of Mr. Bell, of whose claim we 
 shall speak presently. 
 
 Signor Manzetti, of Aosta, says the same thing, asserting 
 that his telephonic invention was described in several newspa- 
 pers of 1865, among others in Le Petit Journal, of Paris, on 
 the 22d November, 1865 ; H Diritto at Rome, 16th July, 1865 ; 
 UEcho d' Italia, New York, 9th August, 1865 ; I? Italia, Flor- 
 ence, 10th August, 1865; La Comuna d" 1 Italia, Genoa, 1st 
 December, 1865; La Verita, Novara, 4th January, 1866; H 
 
18 THE TELEPHONE. 
 
 Commercio, Genoa, 6th January, 1866. It is true that no de- 
 scription of the system was given, and that the journals in 
 question only asserted that experiments had been made, which 
 proved that the practical solution of the problem of transmit- 
 ting speech by electricity became possible by this system. At 
 any rate, M. Charles Bourseul must still have the credit of the 
 priority of the idea, and, in our opinion, all claims made after 
 the fact only merit slight consideration. 
 
 Before considering Bell's telephone, and the different modi- 
 fications which have been applied to it, it seems worth while, in 
 order to make the reader perfectly familiar with these kinds 
 of instruments, to study the electro-musical telephones which 
 preceded it, and especially that of M. Reiss, which was made 
 in 1860, and became the starting-point of all the others. We 
 shall find that these instruments have very important appli- 
 cations, and that telegraphy will probably be one day much 
 advanced by their use. 
 
 MUSICAL TELEPHONES. 
 
 Telephone of M. Reiss. This telephone is, as far as the re- 
 production of sound is concerned, based upon Mr. Page's dis- 
 coveries in 1837, and, as regards electric transmission, it is 
 based on the vibrating membrane of which Mr. L. Scott made 
 use in his phonautograph, in 1855. This instrument is com- 
 posed, like telegraphic systems, of two distinct parts, a sender 
 and a receiver, as represented in Fig. 1. 
 
 The sender was virtually composed of a sounding-box, K, 
 having on its upper surface a large circular opening, across 
 which a membrane was stretched, and in its centre there was 
 fitted a thin disk of platinum, o, above which a metallic point, 
 c, was fixed, and this, together with the disk, constituted the 
 contact-breaker. On one face of the sounding-box K there 
 was a sort of speaking-tube, for the purpose of collecting the 
 sound, and directing it to the interior of the box, in order that 
 
M. REISS S TELEPHONE. 
 
 10 
 
 it might then react upon the membrane. Part of the box K 
 is broken away in the plate, in order that the different parts of 
 which it is made may be seen. 
 
 Fiu. 1. 
 
 The rods a, c, which support the platinum point b, are in 
 metallic contact with a Morse key, t, placed on the side of the 
 box K, and with an electro-magnet, A, which belongs to a tele- 
 graphic system, intended to exchange the signals required 
 to start the action of the two instruments at their respective 
 stations. 
 
 The receiver consists of a sounding -box, B, on which rest 
 two supports, d, d, bearing an iron rod of the thickness of a 
 knitting-needle. An induction coil of insulated wire, g, is 
 wound round this rod, and the whole is enclosed by the lid D, 
 which concentrates the sound already increased by the sound- 
 
20 THE TELEPHONE. 
 
 ing-box: for this purpose the box is provided with two open- 
 ings below the coil. 
 
 The circuit is completed through the primary of this coil 
 by the two terminals 3 and 4, and a Morse key, t, is placed at 
 the side of box B, in order to exchange signals. 
 
 In order to work this system, the speaking instrument 
 should be placed before the opening T, and this instrument 
 may be a flute, a violin, or even the human voice. The vibra- 
 tions of air occasioned by these instruments cause the tele- 
 phonic membrane to vibrate in unison, and the latter, rapidly 
 moving the platinum disk o to and from the point 5, causes a 
 series of breaks in the current, which are repeated in the iron 
 wire d d, and transformed into metallic vibrations, of which 
 the number is equal to that of the sounds successively pro- 
 duced. 
 
 According to this mode of action, the possibility of trans- 
 mitting sounds with their relative value becomes intelligible ; 
 but it is equally clear .that sounds thus transmitted will not 
 have the timbre of those which produce them, since the tim- 
 bre is independent of the number of vibrations, and it must 
 be added that the sounds produced by M. Reiss's instrument 
 were as shrill as those of a child's penny trumpet, and by no 
 means attractive. The problem of transmitting musical sounds 
 by electricity was, however, really solved, and it can be said- 
 with truth that an air or a melody could be heard at any given 
 distance. 
 
 The invention of this telephone dates, as we have seen, from 
 1860, and Professor Heisler speaks of it in his treatise of tech- 
 nical physics, published at Vienna in 1866; he even asserts, 
 in the article which he devotes to the subject, that although 
 the instrument was still in its infancy, it was capable of trans- 
 mitting vocal melodies, and not merely musical sounds. The 
 system was afterward perfected by M. Vander Weyde, who, 
 after reading the account published by M. Heisler, sought to 
 
21 
 
 make the box of the sender more sonorous, and to strenothen 
 the sounds produced by the receiver. He writes as follows in 
 the American Scientific Journal : 
 
 "In 1868 I caused two telephones to be made, similar to 
 those I have described, and I exhibited them at a meeting of 
 the Polytechnic Club of the American Institute. The trans- 
 mitted sounds were produced at the farthest extremity of the 
 Cooper Institute, quite outside the hall in which the audience 
 sat : the receiver was placed on a table in the hall itself. The 
 vocal airs were faithfully reproduced, but the sound was rather 
 weak and nasal. I then tried to improve the instrument, and 
 I first obtained stronger vibrations in the box K by causing 
 reverberation from the sides of the box, by means of hollow 
 partitions. I next intensified the sounds produced by the re- 
 ceiver, by introducing several iron wires into the coil instead 
 of one. These improvements were submitted to the meeting 
 of the American Association for the Advancement of Science, 
 which was held in 1869, and it was considered that the inven- 
 tion contained the germ of a new method of telegraphic trans- 
 mission which might lead to important results." This opinion 
 was soon afterward justified by the discoveries of Bell and 
 Elisha Gray. 
 
 Messrs. Cecil and Leonard Wratfs Telephone. This system, 
 represented in Figs. 2 and 3, is simply an improvement on that 
 of M. Reiss, with the object of intensifying the effects pro- 
 duced. The sender is provided with two membranes instead 
 of one, and its receiver, instead of being formed of a single 
 iron wire covered with a magnetizing coil, is composed of two 
 distinct coils, H, H' (Fig. 2), placed in the same straight line, 
 and within which are two iron rods. These rods are fastened 
 by one of their ends to two copper disks, A, B ; these disks 
 are maintained in a fixed position by screws, I, I', and the two 
 other extremities of the rods, between the coils, are opposite 
 each other, not touching, but divided by a very small interval. 
 
22 THE TELEPHONE. 
 
 The instrument is set upon a sounding-box, in which there is 
 a hole, T, in the space corresponding to the interval between 
 the coils : these coils communicate with four terminals, which 
 
 FIG. 2. 
 
 are connected with the electric current in such a way that the 
 adjacent poles of the two rods are of opposite polarity, thus 
 forming a single magnet, divided in the centre. It seems that 
 by this arrangement the sound produced becomes much more 
 distinct. 
 
 The form of the sender, also, is somewhat different from the 
 one we have previously described : the upper part, instead of 
 being horizontal, is rather inclined, as it appears in Fig. 3 ; and 
 the opening E, through which the sound has to communicate 
 with the vibrating membrane, occupies a great part of the up- 
 per surface of the box, which consequently appears to be some- 
 what oblique. The second membrane, G, which is of caout- 
 chouc, forms a sort of partition which divides the box in two, 
 starting from the upper end of the opening: the inventor 
 states that this will protect the outer membrane, D, from the 
 breath and other injurious effects, while increasing the force 
 of the vibrations produced on the first membrane, as in a drum. 
 The contact-breaker itself also differs from the one in M. Reiss's 
 instrument. The platinum disk b is only placed in circuit by 
 means of two slender wires of platinum or steel, which are im- 
 mersed in two small cups, filled with mercury, and connected 
 
ELECTRIC HARMONICA. 
 
 23 
 
 with the circuit. In this way the movements of the mem- 
 brane D are free, and its vibration is rendered more easy. 
 
 The circuit is also broken by a little platinum point resting 
 on a lever with a spring-joint, K H, which is above the disk : 
 one end of the lever, which is fixed below a kind of Morse key, 
 M I, makes it possible to close the circuit with the hand, so as 
 to give the signal for setting the apparatus to work. 
 
 Fio. 3. 
 
 Electric Harmonica. Long before M. Reiss's invention, and 
 consequently still longer before that of Mr. Elisha Gray, I men- 
 tioned a sort of electric harmonica, and described it as follows 
 in the first edition of my "Expose des applications de 1'Elec- 
 tricite," published in 1853 : 
 
 " The power possessed by electricity to set metallic plates in 
 motion and cause their vibration has been used for the pro- 
 duction of distinct sounds, which can be combined and harmo- 
 nized ; but in addition to this purely physical application, elec- 
 tro-magnetism has come to the aid of certain instruments, such 
 
24 THE TELEPHONE. 
 
 as pianos, organs, etc., rendering them capable of being played 
 at a distance. So that this extraordinary force may be turned 
 to account in arts which are apparently the least susceptible 
 of any application of electricity. 
 
 "We have already spoken of M. de la Rive's contact-break- 
 er. It is, as we know, an iron disk, ired to a steel spring, 
 and maintained in a fixed position opposite to an electro-magnet 
 by another spring in connection with one branch ^ of the cur- 
 rent. As the other branch, after passing into the wire of the 
 electro-magnet, terminates in the iron disk itself, the electro- 
 magnet is only active at the moment when the disk touches 
 the terminal spring ; at the moment of leaving it, the magnet- 
 ism ceases, and the iron disk returns to its normal position, 
 and then leaves it again. In this way a vibration is produced, 
 rapid in proportion to the small size of the vibrating disk, and 
 to the greatness of the force produced by the approach of the 
 disk to the electro-magnet. 
 
 "In order to increase the acuteness of the sounds, one or 
 other of these expedients must be employed. The simplest 
 way is to use a screw which can be tightened or relaxed at 
 pleasure, and which in this manner removes the vibrating disk 
 to a greater or less distance from the electro-magnet. This is 
 the case in M. Froment's instrument, and by this means he has 
 obtained sounds of extraordinary acuteness, although not un- 
 pleasant to the ear. 
 
 " M. Frornent has not applied the apparatus to a musical in- 
 strument, but it is evident that it would be easy to do so ; it 
 would only be necessary to make the notes of a key-board act 
 on metallic levers, of a length corresponding to the position re- 
 quired by the disk for the vibration of different tones. These 
 different levers, resting on the disk, would act as a point of 
 contact, but the point would vary in position, according to the 
 touch. 
 
 "If the current were constant, such an instrument would 
 
ELECTRIC HARMONICA. 25 
 
 certainly have many advantages over the pipe instruments 
 which are in use, since the vibration might be prolonged at 
 will in the case of each note, and the sounds would be softer; 
 unfortunately the irregular action of the battery makes it diffi- 
 cult in practice. These kinds of instruments are therefore 
 only used as a means ofc$3gulating by ear the force of the bat- 
 tery a much more convenient regulator than the rheometers, 
 since it is possible to estimate by them the variations of the 
 battery during an experiment without any distraction of the 
 mind." 
 
 In 1856, M. Petrina, of Prague, invented an analogous ar- 
 rangement, to which he gave the name of electric harmonica, 
 although, strictly speaking, he had not thought of it as a mu- 
 sical instrument. This is what I have said on the subject in 
 vol. iv. of the second edition of my " Expose des applications 
 de PElectricite," published in 1859 : 
 
 " The principle of this instrument is similar to that of Neef 's 
 rheotome, in which the hammer is replaced by slender rods, 
 whose vibrations produce a sound. Four of these rods are 
 placed side by side, and when moved by keys, and arrested by 
 levers, produce combined sounds of which the origin may be 
 easily shown." 
 
 It is true that nothing is said in this passage of the capabil- 
 ity possessed by these instruments of being played at a dis- 
 tance ; but this idea was quite legitimate, and German periodi- 
 cals assert that it was accomplished by M. Petrina even, before 
 1856. It was the result of what I said at the outset: "that 
 electro-magnetism may come to the aid of certain instruments, 
 such as pianos, organs, etc., in order to enable them to be played 
 at a distance" and I also pointed out the expedients employed 
 for the purpose, and even for setting them at work, under the 
 influence of a small musical-box. I did not, however, ascribe 
 importance to the matter, and it is only by way of historical 
 illustration that I speak of these systems. 
 
 2 
 
26 THE TELEPHONE. 
 
 Telephone by Mr. JElisha Gray, of Chicago. This system, 
 invented in 1874, is in reality only an instrument of the nat- 
 ure of those which preceded it, but with important modifica- 
 tions, which made it possible to apply it usefully to telegraphy. 
 In an early model he made use of an induction coil, with two 
 helices, one over the other: the contact-breaker, which was 
 vibrating, was multiple, and so arranged as to produce vibra- 
 tions numerous enough to emit sounds. These sounds may, 
 as we have seen, be modified by this arrangement, according 
 to the mode in which the instrument is adjusted, and if there 
 are a certain number of such contact-breakers side by side, 
 with vibrating disks so ordered as to produce the different 
 notes of the scale on several octaves, it becomes possible, by a 
 combination of certain notes, to execute on this new kind of 
 instrument a piece of music such as may be produced by a 
 harmonium, an accordion, or any other instrument with blow- 
 ers. The contact-breakers are set in motion by means of the 
 primary current of the induction coil, as it circulates through 
 one or other of the electro-magnets of these contact-breakers, 
 actuated by the lowering of the notes of a key-board connect- 
 ed with them, and the secondary currents which arise in the 
 coil, in consequence of the interruptions in the primary cur- 
 rents, transmit the corresponding vibrations to a remote re- 
 ceiver. There is an analogy between this instrument and the 
 telephones of which we have already spoken by Reiss and 
 Wray,.but the effect is increased by Mr. Gray's modifications. 
 
 We represent in Fig. 4 the arrangement of the first system. 
 The vibrators are A and A', the key-board M and M', the in- 
 duction coil B, and the receiver C. This receiver consists, as 
 we see, of a simple electro -magnet, N N': above its poles 
 there is a metal cylindrical case, C, of which the bottom is 
 made of iron, to serve as an armature. This box, like a violin, 
 is pierced with two holes in the form S, to serve as a sounding- 
 board ; and Mr. Elisha Gray has ascertained that the.molecu- 
 
GKAY'S TELEPHONE. 27 
 
 lar motion which takes place in the magnetic core and its 
 armature, under the influence of alternate magnetization and 
 demagnetization, sufficed to produce vibrations corresponding 
 to the velocity of these alternations, and to emit sounds which 
 became audible when they were magnified by the sounding- 
 board. 
 
 FIG. 4. 
 
 It is quite intelligible that the effect obtained in this system 
 might be reproduced, if, instead of contact-breakers or electric 
 rheotomes, mechanical contact-breakers were used at the send- 
 ing-station, so arranged as to furnish the requisite number of 
 breaks in the current which communicates the vibrations of 
 the different notes of the scale. In this way also it would be 
 possible to dispense with the induction coil, by causing the 
 current which has been broken by the mechanical contact- 
 breaker to react upon the receiver. Mr. Elisha Gray has, more- 
 over, made a different arrangement of this telephonic system, 
 
28 THE TELEPHONE. 
 
 which he has applied to telegraphy for simultaneous electric 
 transmissions, of which we shall speak presently. 
 
 If we may believe Mr. Elisha Gray, the vibrations transmit- 
 ted by the secondary currents would be capable, by the inter- 
 vention of the human body, of causing the sounds to be re- 
 produced at a distance by conducting disks, which vibrate 
 readily, and are placed on a sounding-box. In this way musi- 
 cal sounds may be evoked from copper cylinders placed upon 
 a table, from a metallic disk fastened to a kind of violin, from 
 a membrane stretched on a drum, or from any other resonant 
 substance, by touching any of these objects with one hand, 
 while holding the end of the line with the other. These 
 sounds, of which the quality must vary with the substance 
 touched, would reproduce the transmitted note with the pre- 
 cise number of vibrations which belong to it. 1 
 
 Mr. Varletfs Telephone. This is, strictly speaking, merely 
 a musical telephone of the same kind as that of Mr. Gray, but 
 the arrangement of the receiver is original and interesting. 
 This part of the instrument essentially consists of a drum of 
 large size (three or four feet in diameter), within which is a 
 condenser formed of four sheets of tin-foil, divided by sheets 
 of some insulating material, and with a surface of about half 
 
 1 Mr. Gray, in an article inserted in the Telegrapher of October Yth, 1876, 
 enters into full details of this mode of transmitting sounds by the tissues 
 of the human body, and he gives the following as the conditions in which 
 it must be placed to obtain a favorable result : 
 
 1. The electricity must be of a high tension, in order to have an effect 
 perceptible to the ear. 
 
 2. The substance employed to touch the metallic plate must be soft, 
 flexible, and a good conductor, up to the point of contact : it must then 
 interpose a slight resistance, neither too great nor too small. 
 
 3. The disk and the hand, or any other tissue, must not only be in con- 
 tact, but the contact must result from rubbing or gliding over the surface. 
 
 4. The parts in contact must be dry, so as to maintain the required de- 
 gree of resistance. 
 
VAULEY'S TELEPHONE. 29 
 
 the size of the drum. The plates of the condenser are placed 
 parallel to the membranes of the drum, and very little removed 
 from its surface. 
 
 If an electric charge is communicated to one of the series of 
 conducting plates of the condenser, those which correspond to 
 it are attracted, and if they were movable they might commu- 
 nicate to the intervening strata of air a movement which, on 
 reaching the membranes of the drum, might, by a series of 
 charges in rapid succession, cause the membranes to vibrate, 
 and thus produce sounds : these sounds would correspond to 
 the number of charges and discharges which had occurred. 
 Since these charges and discharges are determined by the con- 
 tact of the two plates of the condenser, at the extremities of 
 the secondary circuit of an induction coil, of which the primary 
 circuit has been duly broken, it becomes evident that, in order 
 to cause the drum to emit any given sound, it will be enough 
 to produce the number of vibrations in the contact-breaker of 
 the induction coil which are required for this sound. 
 
 The means employed by Mr. Yarley to produce these inter- 
 ruptions are the same which are in use in several electrical in- 
 struments, and especially in chronographs an electro-magnetic 
 tuning-fork, regulated so as to emit the sound required. This 
 tuning-fork may, by acting as contact-breaker, react on the pri- 
 mary current of the induction coil ; if the number of the tun- 
 ing-forks equals that of the musical notes which are to be trans- 
 mitted, and if the electro-magnets which set them in motion 
 are connected with the key-board of a piano, it would be possi- 
 ble to transmit a melody to a distance by this system, as well 
 as by that of Mr. Elisha Gray. 
 
 The peculiarity of this system consists in the reproduction 
 of sounds by the action of a condenser ; and we shall presently 
 see that this idea, adopted by Messrs. Pollard and Gamier, led 
 to interesting results. 
 
 Singing Condenser of MM. Pollard and Gamier. This in- 
 
30 THE TELEPHONE. 
 
 strument, which astonishes all who hear it, attracted public at- 
 tention in London some time ago. It is difficult to say why 
 its fame was not greater, since much attention has been be- 
 stowed on less curious instruments. It is a fact that we have 
 been able, thanks to MM. Pollard and Gamier, to hear songs 
 issue from a sort of copybook, so as to become audible through- 
 out the room. The songs thus reproduced are certainly not 
 always perfectly true ; yet when the person who sings into the 
 sender is a musician, and understands how to make use of it, 
 the condenser in question will emit sounds somewhat resem- 
 bling those of the violoncello or the hautbois. 
 
 The singing instrument consists of a condenser, K, formed 
 of thirty sheets of paper, laid one over the other, from nine to 
 thirteen centimetres in thickness : between these, twenty-eight 
 sheets of tin-foil, from six to twelve centimetres thick, are in- 
 tercalated, so joined as to form the two plates of the condenser. 
 For this purpose the pair sheets are joined together at one end 
 of the copybook, and the odd sheets at the other end. This 
 system is fastened to a stiff carton, after taking care to bind it 
 with a strip of paper, and the sheets of tin-foil are joined to 
 the two ends of the condenser by two copper rims, D, D, which 
 are provided with terminals for the circuit wire, and in this 
 way the singing instrument is constructed. A somewhat heavy 
 weight, placed upon the condenser to compress the sheets, does 
 not in any way prevent it from working ; and this vitiates the 
 theory first put forward to explain its effects, that the sheets 
 were moved by attraction. 
 
 The sending instrument consists of a sort of telephone with- 
 out a handle, E, of which the vibrating disk is formed of a very 
 thin plate of tin. A cylindrical piece of carbon, C, is fastened 
 to its centre, and is supported by another cylinder of the same 
 material, H. This rests on a transverse piece of wood, A B, 
 jointed on the side A, on the edge opposite to the box, by 
 means of a regulating screw, V. An arched spring, R (the end 
 
SINGIXG CONDENSER. 
 
 31 
 
 of a watch-spring), placed across this piece of wood gives it a 
 certain elasticity beneath the pressure, and this elasticity is nec- 
 essary in order that the instrument may act properly, and it 
 thus becomes a sort of microphone with a diaphragm. 
 
 FIG. 5. 
 
 The tin plate is put into communication with one pole of a 
 battery, P, of six Leclanche cells, and the lower carbon cylinder, 
 H, corresponds to the primary helix of an induction coil, M, 
 previously connected with the second pole of the battery. Fi- 
 nally, the two extremities of the secondary helix of the coil, a 
 and 6, are in immediate connection with the two plates, D, D', 
 of the condenser. 
 
32 THE TELEPHONE. 
 
 This secondary helix should consist of twenty strands of wire 
 No. 32, covered with silk, and the primary helix is made of five 
 strands of wire No. 16. The length of the coil should not ex- 
 ceed seven centimetres, and the diameter of the core of fine 
 iron wire ought to be about one centimetre. 
 
 In order to produce song on the condenser, the sender must 
 be so regulated that the two carbons C and H do not touch 
 each other in their normal condition, but they should be so 
 close that in singing the vibrations of the disk L L may effect 
 the needful contacts. The adjustment can be easily made by 
 the touch, and by uttering the same note until it is repeated 
 by the condenser. If three notes, given in succession, are 
 faithfully reproduced, the instrument may be assumed to be 
 properly regulated, and, in order to make it work, it is enough 
 to apply the mouth to the mouth-piece as it is applied to a 
 reed pipe. 
 
 In order to obtain a satisfactory result, the disk of the instru- 
 ment must be heard to vibrate, as in a flute a Toignon. Instead 
 of carbons, contacts of platinum may be used; but when ar- 
 ranged as we have described, the instrument may be employed 
 for several purposes, as we shall see presently. This instrument 
 is made by MM. Chardin and Prayer. M. Janssens has made 
 the system more portable by fastening the sender, represented 
 in Fig. 5, to a handle in which the induction coil is placed : the 
 instrument then resembles an ordinary telephone, and the vibra- 
 tion of the diaphragm is made more easy by piercing two holes 
 in it. On the side of the sending-box, above and below the 
 diaphragm, there are binding screws in connection with the end 
 of the handle, since the instrument may be used as an ordinary 
 telephonic sender, and even as a telephonic receiver. 
 
 SPEAKING TELEPHONES. 
 
 We have seen that the telephones just described can only 
 transmit musical sounds, since they can merely repeat simple 
 
STRING TELEPHONES. 33 
 
 vibrations, in greater or less number, it is true, but not in si- 
 multaneous combinations like those which reproduce articulate 
 sounds. Up to the time of Mr. Bell's invention, the transmis- 
 sion of speech could only take place with the aid of acoustic 
 tubes, or of the string telephones of which we have spoken. 
 Although these instruments have no connection with the ob- 
 ject of our study in this work, we have thought it necessary to 
 say a few words about them, since they may sometimes be 
 combined with electric telephones, and also represent the first 
 stage of the invention. 
 
 String Telephones. These instruments, which have flooded 
 the cities of Europe for several years, since the date of the in- 
 vention was 1867, are interesting in themselves, and we are sur- 
 prised that they have not hitherto taken a place in the collec- 
 tions of physical science. They are made of two metal or 
 card-board tubes, in the form of a cylindrical cone : one end is 
 closed by a tightly stretched membrane of parchment, in the 
 centre of which the cord or string intended to connect the two 
 cylinders is fastened by a knot. When two such tubes are 
 connected in this way, and the cord is tightly stretched, as in 
 Fig. 6, it is only necessary to apply one tube to the ear, while 
 another speaks into the opening of the other tube : the words 
 spoken by the latter are instantly transmitted, and it is even 
 possible to converse in quite an undertone. Under these con- 
 ditions the vibrations of the membrane affected by the voice 
 are mechanically transmitted to the other membrane by the 
 string, which, as Robert Hooke declared in 1667, is a better 
 transmitter of sound than the air. In this way it is possible 
 to communicate at a distance of 170 yards, and the size and 
 nature of the cord have some influence. The sellers of these 
 instruments say that the best results are obtained from silken 
 cords, and the worst from those made of hemp. Cords of 
 plaited cotton are usually employed for the sake of cheapness. 
 
 In some patterns the tubes are so arranged as to present, be- 
 
 o* 
 
34 
 
 THE TELEPHONE. 
 
 tween the membrane and the mouth, a diaphragm pierced with 
 a hole, and the instrument somewhat resembles a bell with its 
 base bored and closed again a little above the parchment mem- 
 brane; but I have not observed that this pattern is decidedly 
 superior to the others. 
 
 FIG. 6. 
 
 It has also been asserted that horn-shaped tubes of nickel 
 silver are to be preferred, of which I am equally doubtful. At 
 any rate, these instruments have produced unexpected results ; 
 and although their practical use is very limited, they are inter- 
 esting from a scientific point of view, and are instructive toys 
 for children. 
 
 Mr. Millar, of Glasgow, declares that the effect produced by 
 these telephones depends very much on the nature of the 
 string, the way in which it is attached, and the way in which 
 the membrane is fastened to the mouth-piece. 
 
 Improvements made in the String Telephone. The amazing 
 effects of the Bell telephones have lately brought the string 
 telephones, which were only regarded as children's toys, again 
 
IMPROVEMENTS. 35 
 
 into fashion. Since they have made it possible to transmit to 
 several persons the words reproduced by an electric telephone, 
 means have been sought for combining them usefully with the 
 latter, and the best mode of making them speak on a string 
 presenting several angles has been sought for: it has been 
 shown that, under the usual conditions, these instruments only 
 speak distinctly when the string is stretched in a right line. 
 To solve this problem, it occurred to M. A. Breguet to make 
 use of a sort of tambourine for the supports, with the string 
 passed through their centre ; the sound conveyed by that part 
 of the string which is in connection with the speaking-horn 
 causes the membrane of the tambourine to vibrate, which again 
 communicates the vibration to the next portion of string. In 
 this way the angles may be multiplied at will, and the string 
 may be supported throughout the length compatible with this 
 kind of telephone, which does not exceed 112 yards. 
 
 M. A. Breguet has also invented a system of relays to ac- 
 complish the same object. He makes the strings terminate in 
 two membranes which close the two openings of a brass cylin- 
 der. The sounds reproduced on one of these membranes react 
 upon the other, which vibrates under its influence, as if it were 
 affected by the voice. The cylinder then acts as an ordinary 
 acoustic tube, and its form may be varied at pleasure. 
 
 M. A. Badet, on February 1st, 1878, succeeded in making 
 string telephones in an analogous way, and he used parchment 
 stretched upon frames which acted as resonant boards. The 
 string was fixed in the centre of the membrane, and made with 
 it the angle desired. 
 
 Several scientific men, among others Messrs. Wheatstone, 
 Cornu, and Mercadier, have long been occupied about these 
 ways of transmission by wire, and Messrs. Millar, Heaviside, 
 and Nixon have lately made some interesting experiments, on 
 which we must say a few words. Mr. Millar ascertained that 
 by means of a telegraphic wire, stretched and connected by 
 
36 THE TELEPHONE. 
 
 two copper wires with two vibrating disks, musical sounds 
 might be conveyed to a distance exceeding 160 yards, and that 
 by stretching these wires through a house, and connecting 
 them with mouth and ear holes in different rooms, communica- 
 tion between them became perfectly easy. 
 
 For the vibrating disks he employed wood, metal, or gutta- 
 percha, in the form of a drum, with wires fixed in the centre. 
 The sound seems to become more intense in proportion to the 
 thickness of the wire. 
 
 Messrs. Heaviside and Nixon, in their experiments at New- 
 castle-on-Tyne, have ascertained that the most effective wire 
 was No. 4 of the English gauge. They employed wooden 
 disks an eighth of an inch in thickness, and these may be 
 placed in any part of the length of the wire. When the wire 
 was well stretched and motionless, it was possible to hear what 
 was said at a distance of 230 yards, and it seems that Mr. 
 Huntley, by using very thin iron diaphragms, and by insula- 
 ting the line wire on glass supports, was able to transmit speech 
 for 2450 feet, in spite of the zigzags made by the line on its 
 supports. 
 
 Mr. Graham BelVs Electric Telephone. Telephonic instru- 
 ments were at this stage when Bell's telephone was shown at 
 the Philadelphia Exhibition of 1876. Sir William Thompson 
 did not hesitate to call it " the wonder of wonders," and it in- 
 stantly attracted universal attention, although there was at first 
 much incredulity as to its genuineness. This telephone, in 
 fact, reproduced articulate words, a result which surpassed all 
 the conceptions of physicists. In this case it was no longer a 
 conception, to be treated as visionary until there was proof to 
 the contrary : the instrument spoke, and even spoke so loud- 
 ly that it was not necessary to apply the ear. Sir William 
 Thompson spoke to this effect, on the subject at the meeting 
 of the British Association at Glasgow in September, 1876 : 
 
 " In the department of telegraphs in the United States I saw 
 
BELL'S TELEPHONE. 37 
 
 and heard Mr. Elisha Gray's electric telephone, of wonderful 
 construction, which can repeat four despatches at the same 
 time in the Morse code, and, with some improvements in detail, 
 this instrument is evidently capable of a fourfold delivery. In 
 the Canadian department I heard * To be or not to be ? There's 
 the rub,' uttered through a telegraphic wire, and its pronuncia- 
 tion by electricity only made the rallying tone of the mono- 
 syllables more emphatic. The wire also repeated some extracts 
 from New York papers. With my own ears I heard all this, 
 distinctly articulated through the slender circular disk formed 
 by the armature of an electro-magnet. It was my fellow-jury- 
 man, Professor Watson, who, at the other extremity of the 
 line, uttered these words in a loud and distinct voice, while ap- 
 plying his mouth to a tightly stretched membrane provided 
 with a small piece of soft iron, which executed movements cor- 
 responding to the sound vibrations of the air close to an elec- 
 tro-magnet introduced into the circuit. This discovery, the 
 wonder of wonders in electric telegraphy, is due to a young 
 fellow-countryman of our own, Mr. Graham Bell, a native of 
 Edinburgh, and now naturalized in New York. 
 
 "It is impossible not to admire the daring invention by 
 which we have been able to realize with these simple expedi- 
 ents the complex problem of reproducing by electricity the 
 tones and delicate articulations of voice and speech; and it 
 was necessary, in order to obtain this result, to find out the 
 means of varying the intensity of the current in the same pro- 
 portion as the inflections of the sound emitted by the voice." 
 
 If we are to believe Mr. Graham Bell, the invention of the 
 telephone was not due to a spontaneous and fortunate concep- 
 tion : it was the result of his long and patient studies in acous- 
 tic science, and of the labors of the physicists who preceded 
 him. 1 His father, Mr. Alexander Melville Bell, of Edinburgh, 
 
 1 He cites the following names in his account of electric telephony : 
 
38 THE TELEPHONE. 
 
 had studied this science deeply, and had even succeeded in 
 representing with great ingenuity the adaptation of the vocal 
 organs for the emission of sound. It was natural that he 
 should instil a taste for his favorite studies into his son's mind, 
 and they made together numerous researches in order to dis- 
 cover the relations which exist between the different elements 
 of speech in different languages, and the musical relations of 
 vowels. It is true that several of these researches had been 
 made by M. Helmholtz, and under more favorable conditions ; 
 but these studies were of great use to Mr. Bell when he was 
 afterward occupied with the telephone, and Helmholtz's exper- 
 iments, which he repeated with one of his friends, Mr. Hellis, 
 of London, concerning the artificial reproduction of vowels by 
 means of electric tuning-forks, launched him into the study of 
 the application of electricity to acoustic instruments. He first 
 invented a system of an electric harmonica with a key-board, 
 in which the different sounds of the scale were reproduced 
 by electric diapasons of different forms, adapted to different 
 notes, and which, when set in motion by the successive lower- 
 ing of the keys, could reproduce sounds corresponding to the 
 notes touched, just as in an ordinary piano. 
 
 He next, as he tells us, turned his attention to telegraphy, 
 and thought of making the Morse telegraphs audible by causing 
 the electro-magnetic organ to react on sounding contacts. It 
 is true that this result had already been obtained in the sound- 
 ers used in telegraphy, but he thought that by applying this 
 system to his electric harmonica, and by employing such an 
 intensifying instrument as Helmholtz's resonator at the receiv- 
 ing-station, it would be possible to obtain through a single 
 wire simultaneous transmissions which should be due to the 
 
 Page, Marrian, Beatson, Gassiot, De la Rive, Matteucci, Guillemin, Wert- 
 heim, Wartmann, Janniar, Joule, Laborde, Legat, Reiss, Poggendorf, Du 
 Moncel, Delezenne, Gore, etc. Vide Mr. Bell's paper, in the Journal of the 
 Society of Telegraphic Engineers in London, vol. vi. p. 390, 391. 
 
ELECTRIC CURRENTS. 
 
 39 
 
 action of the voice. We shall see presently that this idea was 
 realized almost at the same time by several inventors, among 
 others by M. Paul Lacour, of Copenhagen, Mr. Elisha Gray, of 
 Chicago, and Messrs. Edison and Varley. 
 
 Mr. Bell's study of electric telephones really dates from this 
 time, and he passed from complex to simple instruments, mak- 
 ing a careful study of the different modes of vibration which 
 arise from different modes of electric action. The following is 
 an abstract, with the omission of more technical details, of the 
 paper read by Mr. Bell to the Society of Telegraphic Engineers, 
 London, October 31st, 1877: 
 
 If the intensity of an electric current is represented by the 
 ordinatcs of a curve, and the duration of breaks in the current 
 by the abscissa, the given curve may represent the waves of 
 the positive or negative current respectively, above and below 
 the line of X, and these waves will be more or less accentuated, 
 just as the transmitted currents are more or less instantaneous. 
 
 If the currents which are interrupted to produce a sound 
 are quite instantaneous in their manifestation, the curve repre- 
 sents a series of isolated indentations, as we see in Fig. 7 ; 
 
 fr 
 
 -4'M'I 
 
 Fis T. 
 
40 
 
 THE TELEPHONE. 
 
 
 
 
 
 
 a. 
 
 
 
 
 0| | / N 
 
 [ 
 
 
 
 
 rJol v!/ 
 
 r a. 
 
 
 B 
 
 ilililil 
 
 
 R 
 
 /. 
 
 FIG. 8. 
 
 and if the interruptions are so made as only to produce dif- 
 ferences of intensity, the curve is presented under the form 
 of Fig. 8. Finally, if the emissions of current are so ordered 
 that their intensity alternately increases and diminishes, the 
 
 
 e'\ 
 
 
 l\ 
 
 f 
 
 o 
 
 
 
 
 
 
 
 B 
 
 ilili 
 
 I . 
 
 FIG. 9. 
 
ANALYSIS OF CURRENTS. 
 
 41 
 
 curve takes the form represented in Fig. 9. In the first case, 
 the currents are intermittent; in the second, pulsatory; in the 
 third case, they are undulatory. 
 
 These currents are necessarily positive or negative, accord- 
 ing to their position above or below the line a?, and if they are 
 alternately reversed, the curves present the form given in Fig. 
 10, curves which essentially differ from the first, not merely 
 in the different form of the indentations, but especially in the 
 suppression of the extra current, which is always found in the 
 pulsatory and undulatory currents. 
 
 FIG. 10. 
 
 The two former systems of currents have long been in use 
 for the electric transmission of musical sounds, of which we 
 have an interesting example in Reiss's telephone, already de- 
 scribed. But Mr. Bell claims to have been the first to employ 
 the undulatory currents, which made it possible to solve the 
 problem of transmitting speech. 1 In order to estimate the im- 
 
 1 This statement is disputed by Mr. Elisha Gray, owing, as we shall see, 
 to a misunderstanding as to the word undulatory current. 
 
42 iHE TELEPHONE. 
 
 portance of this discovery, it will be enough to analyze the ef- 
 fects produced with these different systems of currents when 
 several notes of varying pitch are to be combined. 
 
 Fig. 7 shows a combination in which the styles a, a', of two 
 sending instruments cause the interruption of the current from 
 the same battery B, so that the given vibrations should be be- 
 tween them in the relation of a tierce major, that is, in the re- 
 lation of four to five. Under such conditions the currents are 
 intermittent, and four contacts of a are produced in the same 
 space of time as the five contacts of a', and the corresponding- 
 electric intensities will be represented by the indentations we 
 see in A 2 and in B a : the combination of these intensities, A 2 -f 
 B 2 , will produce the indentations at unequal intervals which may 
 be observed on the third line. It is evident that although the 
 current maintains a uniform intensity, there is less time for 
 the breaks when the interrupting styles act together than when 
 they act separately, so that when there are a number of con- 
 tacts effected simultaneously by styles working at different de- 
 grees of velocity, the effects produced will have the effect of a 
 continuous current. The maximum number of distinct effects 
 which can be produced in this way will, however, greatly de- 
 pend on the relation which exists between the durations of the 
 make and break of the current. The shorter the contacts are, 
 and the longer the breaks, the more numerous will be the ef- 
 fects transmitted without confusion, and vice versa. 
 
 By the aid of pulsatory currents the transmission of musical 
 sounds is effected in the way indicated in Fig. 8, and it is seen 
 that when they are -produced simultaneously, the result A 2 -f-B 7 
 is analogous to that which would be produced by a continuous 
 current of minimum intensity. 
 
 In the case of undulatory currents the result is different, but 
 in order to produce them it is necessary to have recourse to in- 
 ductive effects, and Fig. 9 indicates" the manner in which the 
 experiment should be made. In this case, " the current from 
 
PHOXAUTOGRAPH. 43 
 
 the battery B is thrown into waves by the inductive action of 
 iron or steel reeds, M, M, vibrated in front of electro-magnets, 
 e, 0, placed in circuit with the battery : A a and B a represent 
 the undulations caused in the current by the vibration of the 
 magnetized bodies, and it will be seen that there are four undu- 
 lations of B a in the same time as five undulations of A a . The 
 resultant effect upon the main line is expressed by the curve 
 A a + B a , which is the algebraical sum of the sinusoidal curves 
 A a and B 3 . A similar effect is produced when reversed undu- 
 latory currents are employed, as in Fig. 10, where the current 
 is produced by the vibration of permanent magnets united upon 
 a circuit, without a voltaic battery. 
 
 "It will be understood from Figs. 9 and 10 that the effect 
 of transmitting musical signals of different pitches simultane- 
 ously along a single wire is not to obliterate the vibratory 
 character of the current, as in the case of intermittent and pul- 
 satory currents, but to change the shapes of the electrical undu- 
 lations. In fact, the effect produced upon the current is pre- 
 cisely analogous to the effect produced in the air by the vibra- 
 tion of the inducing bodies M, M'. Hence it should be possi- 
 ble to transmit as many musical tones simultaneously through 
 a telegraph wire as through the air." 
 
 After applying these principles to the construction of a tele- 
 graphic system for multiple transmissions, Mr. Bell lost no time 
 in making use of his researches to improve the vocal training 
 of deaf-mutes. " It is well known," he said, " that deaf-mutes 
 are dumb merely because they are deaf, and that there is no 
 defect in their vocal organs to incapacitate them from utter- 
 ance. Hence it was thought that my father's system of picto-* 
 rial symbols, popularly known as visible speech, might prove a 
 means whereby we could teach the deaf and dumb to use their 
 vocal organs and to speak. The great success of these experi- 
 ments urged upon me the advisability of devising methods of 
 exhibiting the vibrations of sound optically, for use in teaching 
 
44 THE TELEPHONE. 
 
 the deaf and dumb. For some time I carried on experiments 
 with the manometric capsule of Koenig, and with the phonau- 
 tograph of Leon Scott. The scientific apparatus in the Insti- 
 tute of Technology in Boston was freely placed at my disposal 
 for these experiments, and it happened that at that time a stu- 
 dent of the Institute of Technology, Mr. Maurey, had invented 
 an improvement upon the phonautograph. He had succeeded 
 in vibrating by the voice a stylus of wood about a foot in length 
 which was attached to the membrane of the phonautograph, 
 
 ^/Wvwvvv^^/wVA/WWy^^ 
 
 
 f 
 
 VVAA/Va/vVVOAA/V/VlA/YWWVta^ I 
 
 I 1 
 
 FIG. 11. 
 
 and in this way he had been enabled to obtain enlarged trac- 
 ings upon a plane surface of smoked glass. With this appara- 
 tus I succeeded in producing very beautiful tracings of the vi- 
 brations of the air for vowel sounds. Some of these tracings 
 are shown in Fig. 11. I was much struck with this improved 
 form of apparatus, and it occurred to me that there was a re- 
 markable likeness between the manner in which this piece of 
 wood was vibrated by the membrane of the phonautograph 
 
PH ON AUTOGRAPH. 
 
 45 
 
 and the manner in which the ossiculce of the human ear were 
 moved by the tympanic membrane. I determined, therefore, to 
 construct a phonautograph modelled still more closely upon the 
 mechanism of the human ear, and for this purpose I sought the 
 assistance of a distinguished aurist in Boston, Dr. Clarence J. 
 Blake. He suggested the use of the human ear itself as a 
 phonautograph, instead of making an artificial imitation of it. 
 The idea was novel, and struck me accordingly, and I requested 
 my friend to prepare a specimen for me, which he did. The 
 apparatus, as finally constructed, is shown in Fig. 12. The 
 
 Fio. 12. 
 
46 
 
 THE TELEPHONE. 
 
 stapes was removed, and a stylus of hay about an inch in length 
 was attached to the end of the incus. Upon moistening the 
 membrana tympani and the ossiculce with a mixture of glyce- 
 rine and water, the necessary mobility of the parts was obtained ; 
 and upon singing into the external artificial ear the stylus of 
 hay was thrown into vibration, and tracings were obtained upon 
 a plane surface of smoked glass passed rapidly underneath. 
 While engaged in these experiments I was struck with the re- 
 markable disproportion in weight between the membrane and 
 the bones that were vibrated by it. It occurred to me that if 
 a membrane as thin as tissue-paper could control the vibration 
 of bones that were, compared to it, of immense size and weight, 
 why should not a larger and thicker membrane be able to vi- 
 brate a piece of iron in front of an electro-magnet, in which 
 case the complication of steel rods shown in my first form of 
 telephone could be done away with, and a simple piece of iron 
 attached to a membrane be placed at either end of the tele- 
 graphic circuit ? 
 
 FIG. 13. 
 
 "For this purpose I attached the reed A (Fig. 13) loosely 
 by one extremity to the uncovered pole, h, of the magnet, and 
 fastened the other extremity to the centre of a stretched mem- 
 brane of gold-beater's-skin, n. I presumed that, upon speaking 
 in the neighborhood of the membrane n, it would be thrown 
 into vibration, and cause the steel reed A to move in a similar 
 manner, occasioning undulations in the electrical current that 
 would correspond to the changes in the density of the air dur- 
 
BELL TELEPHONE. 47 
 
 ing the production of the sound ; and I further thought that 
 the change of the intensity of the current at the receiving end 
 would cause the magnet there to attract the reed A' in such a 
 manner that it should copy the motion of the reed A, in which 
 case its movements would occasion a sound from the membrane 
 n f similar in timbre to that which had occasioned the original 
 vibration. 
 
 " The results, however, were unsatisfactory and discouraging. 
 My friend Mr. Thomas A. Watson, who assisted me in this first 
 experiment, declared that he heard a faint sound proceed from 
 the telephone at his end of the circuit, but I was unable to 
 verify his assertion. After many experiments attended by the 
 same only partially successful results, I determined to reduce 
 the size and weight of the spring as much as possible. For 
 this purpose I fastened a piece of clock spring, about the size 
 and shape of my thumb-nail, firmly to the centre of the dia- 
 phragm, and had a similar instrument at the other end (Fig. 
 14) ; we were then enabled to obtain distinctly audible effects. 
 
 FIG. 14. 
 
 I remember an experiment made with this telephone, which at 
 the time gave me great satisfaction and delight. One of the 
 telephones was placed in my lecture-room in the Boston Uni- 
 
48 THE TELEPHONE. 
 
 versity, and the other in the basement of the adjoining build- 
 ing. One of my students repaired to the distant telephone to 
 observe the effects of articulate speech, while I uttered the 
 sentence, * Do you understand what I say ?' into the telephone 
 placed in the lecture-hall. To my delight an answer was re- 
 turned through the instrument itself, articulate sounds pro- 
 ceeded from the steel spring attached to the membrane, and I 
 heard the sentence, ' Yes, I understand you perfectly.' It is a 
 mistake, however, to suppose that the articulation was by any 
 means perfect, and expectancy no doubt had a great deal to do 
 with my recognition of the sentence ; still, the articulation was 
 
 FIG. 15. 
 
 there, and I recognized the fact that the indistinctness was en- 
 tirely due to the imperfection of the instrument. I will not 
 trouble you by detailing the various stages through which the 
 apparatus passed, but shall merely say that after a time I pro- 
 duced the form of instrument shown in Fig. 15, which served 
 very well as a receiving telephone. In this condition my inven- 
 tion was exhibited at the Centennial Exhibition in Philadelphia. 
 The telephone shown in Fig. 14 was used as a transmitting 
 instrument, and that in Fig. 15 as a receiver, so that vocal com- 
 munication was only established in one direction. 
 
 " The articulation produced from the instrument shown in 
 Fig. 15 was remarkably distinct, but its great defect consisted 
 
BELL TELEPHONE. 
 
 49 
 
 in the fact that it could not be used as a transmitting instru- 
 ment, and thus two telephones were required at each station, 
 one for transmitting and one for receiving spoken messages. 
 
 " It was determined to vary the construction of the tele- 
 phone, and I sought, by changing the size and tension of the 
 membrane, the diameter and thickness of the steel spring, the 
 size and power of the magnet, and the coils of insulated wire 
 around their poles, to discover empirically the exact effect of 
 each element of the combination, and thus to deduce a more 
 perfect form of apparatus. It was found that a marked in- 
 crease in the loudness of the sounds resulted from shortening 
 the length of the coils of wire, and by enlarging the iron dia- 
 phragm which was glued to the membrane. In the latter case, 
 also, the distinctness of the articulation was improved. Final- 
 ly, the membrane of gold-beater's-skin was discarded entirely, 
 and a simple iron plate was used instead, and at once intelligi- 
 ble articulation was obtained. The new form of instrument is 
 that shown in Fig. 16, and, as had been long anticipated, it 
 
 FIG. 16. 
 
 was proved that the only use of the battery was to magnet- 
 ize the iron core of the magnet, for the effects were equally 
 audible when the battery was omitted and a rod of magnetized 
 steel substituted for the iron core of the magnet. 
 
 " It was my original intention, and it was always claimed by 
 me, that the final form of telephone would be operated by per- 
 
 3 
 
50 THE TELEPHONE. 
 
 manent magnets in place of batteries, and numerous experi- 
 ments had been carried on by Mr. Watson and myself privately 
 for the purpose of producing this effect. 
 
 " At the time the instruments were first exhibited in public 
 the results obtained with permanent magnets were not nearly 
 so striking as when a voltaic battery was employed, where- 
 fore we thought it best to exhibit only the latter form of in- 
 strument. 
 
 " The interest excited by the first published accounts of the 
 operation of the telephone led many persons to investigate the 
 subject, and I doubt not that numbers of experimenters have 
 independently discovered that permanent magnets might be 
 employed instead of voltaic batteries. Indeed one gentleman, 
 Professor Dolbear, of Tufts College, not only claims to have' 
 discovered the magneto - electric telephone, but I understand 
 charges me with having obtained the idea from him through 
 the medium of a mutual friend. 
 
 "A still more powerful form of apparatus was constructed 
 by using a powerful compound horseshoe magnet in place of 
 
 the straight rod which had been 
 previously used (see Fig. 17). 
 Indeed the sounds produced by 
 means of this instrument were 
 of sufficient loudness to be 
 faintly audible to a large audi- 
 ence, and in this condition the 
 instrument was exhibited in the 
 Essex Institute, in Salem, Mas- 
 sachusetts, on February 12th, 1877, on which occasion a short 
 speech shouted into a similar telephone in Boston, sixteen 
 miles away, was heard by the audience in Salem. The tones 
 of the speaker's voice were distinctly audible to an audience of 
 600 people, but the articulation was only distinct at a distance 
 of about six feet. On the same occasion, also, a report of the 
 
BELL TELEPHONE. 
 
 51 
 
 lecture was transmitted by word of mouth from Salem to Bos- 
 ton, and published in the papers the next morning. 
 
 "From the form of telephone shown in Fig. 16 to the pres- 
 ent form of the instrument (Fig. 18) is but a step. It is, in 
 fact, the arrangement of Fig. 16 in a portable form, the magnet 
 
 FIG. IS. 
 
 N S being placed inside the handle, and a more convenient 
 form of mouth-piece provided. 
 
 "And here I wish to express my indebtedness to several sci- 
 entific friends in America for their co-operation and assistance. 
 I would specially mention Professor Peirce and Professor 
 Blake, of Brown University, Dr. Channing, Mr. Clarke, and Mr. 
 Jones. It was always my belief that a certain ratio would be 
 found between the several parts of a telephone, and that the 
 size of the instrument was immaterial ; but Professor Peirce 
 was the first to demonstrate the extreme smallness of the 
 magnets which might be employed. The convenient form of 
 mouth-piece shown in Fig. 17, now adopted by me, was invent- 
 ed solely by my friend Professor Peirce." 
 
 Another form of transmitting telephone exhibited in Phila- 
 delphia, intended for use with the receiving telephone (Fig. 15), 
 is represented by Fig. 19. 
 
 A platinum wire attached to a stretched membrane com- 
 pleted a voltaic circuit by dipping into water. Upon speaking 
 
52 
 
 THE TELEPHONE. 
 
 to the membrane, articulate sounds proceeded from the tele- 
 phone in the distant room. The sounds produced by the tele- 
 phone became louder when dilute sulphuric acid, or a saturated 
 
 FIG. 19. 
 
 solution of salt, was substituted for the water. Audible effects 
 were also produced by the vibration of plumbago in mercury, 
 in a solution of bichromate of potash, in salt and water, in 
 dilute sulphuric acid, and in pure water. 
 
 Mr. Bell goes on to say : 
 
 " I have found, also, that a musical tone proceeds from a 
 piece of plumbago or retort carbon when an intermittent cur- 
 rent of electricity is passed through it, and I have observed the 
 most curious audible effects produced by the passage of re- 
 versed intermittent currents through the human body. A 
 rheotome was placed in circuit with the primary wires of an 
 induction coil, and the fine wires were connected with two 
 strips of brass. One of these strips was held closely against 
 
BELL'S EXPERIMENTS. 53 
 
 the ear, and a loud sound proceeded from it whenever the oth- 
 er slip was touched with the other hand. The strips of brass 
 were next held one in each hand. The induced currents occa- 
 sioned a muscular tremor in the fingers. Upon placing my 
 forefinger to my ear, a loud crackling noise was audible, seem- 
 ingly proceeding from the finger itself. A friend who was 
 present placed my finger to his ear, but heard nothing. I re- 
 quested him to hold the strips himself. He was then distinct- 
 ly conscious of a noise (which I was unable to perceive) pro- 
 ceeding from his finger. In this case a portion of the induced 
 currents passed through the head of the observer when he 
 placed his ear against his own finger ; and it is possible that 
 the sound was occasioned by a vibration of the surfaces of the 
 ear and finger in contact. 
 
 "When two persons receive a shock from a RuhmkorfFs 
 coil by clasping hands, each taking hold of one wire of the 
 coil with the free hand, a sound proceeds from the clasped 
 hands. The effect is not produced when the hands are moist. 
 When either of the two touches the body of the other, a loud 
 sound comes from the parts in contact. When the arm of one 
 is placed against the arm of the other, the noise produced can 
 be heard at a distance of several feet. In all these cases a 
 slight shock is experienced so long as the contact is pre- 
 served. The introduction of a piece of paper between the 
 parts in contact does not materially interfere with the pro- 
 duction of the sounds, but the unpleasant effects of the shock 
 are avoided. 
 
 "When an intermittent current from a Ruhmkorff's coil is 
 passed through the arms, a musical note can be perceived when 
 the ear is closely applied to the arm of the person experiment- 
 ed upon. The sound seems to proceed from the muscles of 
 the forearm and from the biceps muscle. Mr. Elisha Gray 1 
 
 1 Elisha Gray. Eng. Pat, Spec. No. 2646, Aug. 1874. 
 
54 THE TELEPHONE. 
 
 has also produced audible effects by the passage of electricity 
 through the human body. 
 
 " An extremely loud musical note is occasioned by the spark 
 of a Ruhmkorff's coil when the primary circuit is made and 
 broken with sufficient rapidity ; when two rheotomes of differ- 
 ent pitch are caused simultaneously to open and close the 
 primary circuit, a double tone proceeds from the spark. 
 
 "A curious discovery, which may be of interest to you, has 
 been made by Professor Blake. He constructed a telephone 
 in which a rod of soft iron, about six feet in length, was used 
 instead of a permanent magnet. A friend sang a continuous 
 musical tone into the mouth -piece of a telephone, like that 
 shown in Fig. 17, which was connected with -the soft iron in- 
 strument alluded to above. It was found that the loudness of 
 the sound produced in this telephone varied with the direction 
 in which the iron rod was held, and that the maximum effect 
 was produced when the rod was in the position of the dipping- 
 needle. This curious discovery of Professor Blake has been 
 verified by myself. 
 
 "When a telephone is placed in circuit with a telegraph line, 
 the telephone is found seemingly to emit sounds on its own 
 account. The most extraordinary noises are often produced, 
 the causes of which are at present very obscure. One class of 
 sounds is produced by the inductive influence of neighboring 
 wires and by leakage from them, the signals of the Morse 
 alphabet passing over neighboring wires being audible in the 
 telephone, and another class can be traced to earth currents 
 upon the wire, a curious modification of this sound revealing 
 the presence of defective joints in the wire. 
 
 " Professor Blake informs me that he has been able to use 
 the railroad track for conversational purposes in place of a tel- 
 egraph-wire, and he further states that when only one tele- 
 phone was connected with the track the sounds of Morse op- 
 erating were distinctly audible in the telephone, although the 
 
BELL'S EXPERIMENTS. 55 
 
 nearest telegraph-wires were at least forty feet distant; and 
 Professor Peirce has observed the most curious sounds pro- 
 duced from a telephone in connection with a telegraph-wire 
 during the aurora borealis." 
 
 Mr. Bell went on to describe instances in which airs sung or 
 played upon a musical instrument are transmitted by a tele- 
 phone, when it is not known whence they come; but the 
 strongest proof of the extraordinary sensibility of this instru- 
 ment consists in its becoming possible by its means to trans- 
 mit speech through bodies which might be supposed to be 
 non-conductors. Thus communication with the earth through 
 the human body can be made in spite of the intervention of 
 shoes and stockings ; and it may even be effected if, instead 
 of standing on the ground, the person stands- on a brick wall. 
 Only hewn stone and wood are a sufficient hinderance to com- 
 munication, and if the foot touches the adjoining ground, or 
 even a blade of grass, it is enough to produce electric mani- 
 festations. 
 
 Mr. Bell says in conclusion : 
 
 " The question will naturally arise, Through what length of 
 wire can the telephone be used ? In reply to this I may say 
 that the maximum amount of resistance through' which the un- 
 dulatory current will pass, and yet retain sufficient force to pro- 
 duce an audible sound at the distant end, has yet to be deter- 
 mined ; no difficulty has, however, been experienced in labora- 
 tory experiments in conversing through a resistance of 60,000 
 ohms, which has been the maximum at my disposal. On one 
 occasion, not having a rheostat at hand, I may mention having 
 passed the current through the bodies of sixteen persons, who 
 stood hand-in-hand. The longest length of real telegraph line 
 through which I have attempted to converse has been about 
 250 miles. On this occasion no difficulty was experienced so 
 long as parallel lines were not in operation. Sunday was chosen 
 as the day on which it was probable other circuits would be at 
 
56 THE TELEPHONE. 
 
 rest. Conversation was carried on between myself in New York, 
 and Mr. Thomas A. Watson in Boston, until the opening of 
 business upon the other wires. When this happened the vocal 
 sounds were very much diminished, but still audible. It seemed, 
 indeed, like talking through a storm. Conversation, though 
 possible, could be carried on with difficulty, owing to the dis- 
 tracting nature of the interfering currents. 
 
 " I am informed by my friend Mr. Preece that conversation 
 has been successfully carried on through a submarine cable, six- 
 ty miles in length, extending from Dartmouth to the Island of 
 Guernsey, by means of hand telephones." 
 
 Mr. Elisha Gray's Share in the Invention of the Telephone. 
 We have seen that if Mr. Bell was the first to construct the 
 speaking telephone in a practical form, Mr. Gray had at the 
 same time conceived the idea of an instrument also capable of 
 reproducing speech, and the description given of it in his ca- 
 veat was so precise that if it had been made from his design it 
 would have acted perfectly. This was, in fact, afterward proved 
 by him. In order that our readers may judge from their own 
 knowledge of the share which should be ascribed to Mr. Elisha 
 Gray in the invention of the telephone, we reproduce in Fig. 20 
 the drawing which accompanied the caveat in question. 
 
 The sender, as we see, is composed of a sort of tube, closed 
 at, its lower end by a membrane to which a platinum wire is 
 fixed ; this wire dips into a liquid of moderate conducting pow- 
 er, and an electrode made of platinum, in communication with 
 a battery, is fixed at the bottom of the vessel containing the 
 liquid. The receiver is composed of an electro - magnet, of 
 which the armature is fixed to the centre of a membrane, 
 stretched on a kind of resonator or ear-trumpet which is held 
 to the ear, and the two instruments are united by the line wire 
 as we see in the plate. 
 
 Under these conditions, the undulatory currents necessary 
 for the reproduction of speech were obtained in a mode analo- 
 
GKAY TELEPHONE. 
 
 gous to that pointed out by Mr. Bell in his specification, that 
 is, by the variations of resistance in the liquid layer interposed 
 
 FIG. 20. 
 
 between the platinum wires of the transmittei: ; and their ac- 
 tion, exerted on an electro-magnet, of which the armature was 
 fixed on the diaphragm of the resonator, was produced under 
 more favorable conditions than in Mr. Bell's specification (see 
 Fig. 13), since that gentleman" regards this arrangement (repre^ 
 sented in Fig. 14) as an important improvement on his first 
 conception. 
 
 The whole importance of the invention rests on the interven- 
 tion of undulatory currents, which, as we have seen, are indis- 
 pensable for the reproduction of speech, and it concerns us to 
 know whether it was Mr. Bell or Mr. Gray who first declared 
 their importance ; for in both the specifications deposited on 
 February 14th, 1876, the use of undulatory currents was de- 
 clared to be indispensable. Mr. Gray asserts that he had rec- 
 ognized their importance for the transmission of combined 
 sounds as early as 1874 ; but Mr. Bell believes that the undula- 
 
 3* 
 
58 THE TELEPHONE. 
 
 tory currents mentioned by Mr. Gray at that time were only 
 currents analogous to those he had designated under the name 
 of pulsatory currents, which we have represented in Fig. 8. We 
 have seen that since these currents only represent the abrupt 
 elevations and depressions of intensity, they are unfit for the 
 reproduction of articulate sounds, which, on the contrary, de- 
 mand that the variations of intensity should result from suc- 
 cessive efforts, in exact correspondence with all the inflections 
 of the sonorous vibrations effected by the voice. Mr. Bell's 
 claim to priority on this question has been recognized by the 
 American Patent Office, since he has been placed in possession 
 of the patent. However this may be, Mr. Gray's telephonic 
 system was complete, and we see in it, as we have already said, 
 the origin of the battery telephones, which have recently pro- 
 duced such important results. Let us now consider the rela- 
 tion which this system bears to Mr. Bell's. 
 
 The Bell system, as we have seen, although making use of 
 a battery in the first instance, only obtained the diminution 
 and increase of. electric force necessary for the articulation of 
 words by means of induction currents produced by the move- 
 ments of an armature of soft iron currents of which the in- 
 tensity was consequently due to the range and inflections of 
 these movements. The battery only intervened in order to 
 communicate magnetic force to the inducer. This use of in- 
 duced currents in telephonic transmissions was already of great 
 importance, since various experiments subsequently made have 
 proved their superiority to voltaic currents for this purpose. 
 But experience soon convinced Mr. Bell that a powerful in- 
 ductive apparatus worked by a battery was not only unneces- 
 sary for the action of this apparatus, but that a permanent 
 magnet, very small and weak, would provide sufficient currents. 
 This discovery, in which, as we have seen, Mr, Peirce had some 
 share, was of great importance, since it became possible to re- 
 duce the size of the instrument considerably, so as to make it 
 
MB. OKAY'S CLAIM TO THE TELEPHONE. 59 
 
 portable and adapted for sending and receiving; and it was 
 shown that the telephone was the most sensitive of all instru- 
 ments in revealing the action of currents. If, therefore, Mr. 
 Bell was not the first to employ the successful mode of trans- 
 mitting articulate words, it must be said that he sought, like 
 Mr. Gray, to solve the problem by means of undulatory cur- 
 rents, and that he obtained these currents by the effect of in- 
 duction, a system which, as soon as it was perfected, led to 
 the important results with which we are all acquainted. If he 
 had only given to the astonished world an instrument capable 
 of reproducing speech telegraphically, his fame would be great ; 
 for this problem had hitherto been regarded as insoluble. 
 
 Mr. Gray's claims to the invention of the telephone are given 
 in the following summary from a very interesting work, entitled 
 " Experimental Researches on Electro-harmonic Telegraphy and 
 Telephony :" 
 
 "I.I was the first to discover the means of transmitting 
 compound sounds and variable inflections through a closed 
 circuit by means of two or more electric waves. 
 
 "2. I assert that I" was the first to discover and utilize the 
 mode of reproducing vibrations by the use of a magnet re- 
 ceiver constantly supplied with electric action. 
 
 " 3. I also assert that I was the first to construct an instru- 
 ment consisting of a magnet with a circular diaphragm of mag- 
 netic substance, supported by its edge at a little distance from 
 the poles of a magnet, and capable of being applied to the 
 transmission and reception of articulate sounds." 
 
 It is a curious fact, worth recording here, that Mr. Yates, of 
 Dublin, in 1865, when trying to improve Reiss's telephone, real- 
 ized to a certain extent Mr. Gray's conception of the liquid 
 transmitter; for he introduced into the platinum contacts of 
 Mr. Reiss's instrument a drop of water, which adapted it for 
 the reproduction of articulate sounds. However, no notice 
 was then taken of this result. 
 
60 THE TELEPHONE. 
 
 EXAMINATION INTO THE FUNDAMENTAL PRINCIPLES ON 
 WHICH BELL'S TELEPHONE IS BASED. 
 
 Although the preceding account would suffice to make the 
 principle of Bell's telephone intelligible to persons acquainted 
 with electric science, this would not be the case with the ma- 
 jority of our readers, and we therefore think it necessary to 
 enter into some details as to the source of the electric currents 
 which are employed in telephonic transmissions. These details 
 seem to us the more necessary, since many persons still believe 
 that Bell's telephones are not electric, because they do not re- 
 quire a battery, and they are often confounded with string 
 telephones, so that the difference of price between Bell's in- 
 struments and those hawked in the streets seems astonishing. 
 
 Without defining what is meant by an electric current, 
 which would be too elementary, we may say that electric cur- 
 rents can be produced by different causes, and that, in addi- 
 tion to those which are due to batteries, strong currents are 
 also produced by the force exerted by magnets on a conduct- 
 ing circuit properly arranged. Such currents are called induc- 
 tion currents, and are used in Bell's telephone. In order to 
 understand how they are developed under these conditions, it 
 will be enough to examine what takes place when the pole of 
 a magnet is brought near to, and withdrawn from, a closed 
 circuit. To do this, let us suppose a copper wire attached to 
 a galvanometer in the form of a circle, and that one pole of a 
 permanent magnet is directed toward the centre of the circle. 
 Now observe what happens : 
 
 1. At the moment when the magnet approaches an electric 
 current arises, causing the galvanometer to deviate to one side. 
 This deviation will be great in proportion to the extent of the 
 movement, and the tension of the current will be great in pro- 
 portion to the abruptness of the movement. The current will, 
 however, be only instantaneous. 
 
ELECTRIC CURRENTS. 61 
 
 2. At the moment when the magnet is withdrawn, a fresh 
 current of the same nature will arise, but it will appear in an 
 opposite direction from the former. It will be what is called 
 a direct current, because it is in the same direction as the mag- 
 netic current of the magnet which produces it, while the other 
 current is called inverse. 
 
 3. If, instead of advancing or withdrawing the magnet by 
 means of a single movement, it is advanced in jerks, a succes- 
 sion of currents in the same direction is produced, of which 
 the existence can be ascertained by the galvanometer when 
 there is a sufficient interval between the movements, but when 
 the intervals are very slight the currents are interfused; and 
 since inverse effects take place when the magnet is moved in 
 a contrary direction, the needle of the galvanometer follows 
 the movements of the magnet, and to a certain extent stereo- 
 types them. 
 
 4. If, instead of reacting o a simple closed circuit, the mag- 
 net exerts its force on a considerable number of circumvolu- 
 tions of this circuit, that is, on a bobbin of coiled wire, the ef- 
 fects will be considerably increased, and they will be still greater 
 if there be a magnetic core within the bobbin, since the induc- 
 ing action will then be more effectually exerted throughout the 
 bobbin. As the magnetic core, when it is magnetized and 
 demagnetized under the influence of its approach to or with- 
 drawal from the inducing magnet, is subject to the reaction 
 from all the fluctuations which occur in the movements of the 
 magnet, the induced currents which ensue are perfectly defined. 
 
 5. If, instead of a movable magnet, we suppose it to be fixed 
 in the centre of the coil, the induced currents of which we have 
 spoken may then be determined by modifying its force. In 
 order to do so, it is enough that an iron armature should react 
 upon its poles. When this armature is brought close to one of 
 the poles, or to both at once, it acquires force, and produces -an 
 inverse current, that is, a current in the direction which would 
 
62 THE TELEPHONE. 
 
 have corresponded to an approach of the magnet to the closed 
 circuit. On its withdrawal the inverse effect is produced ; but 
 in both cases the induced currents correspond with the extent 
 and direction of the movements accomplished by the armature, 
 and consequently they may reproduce its movements by their 
 effects. If this armature is an iron plate, which vibrates under 
 the influence of any sound in this disposition of the electro- 
 magnetic system, the alternate movements of the plate will be 
 transformed into the induced currents, and these will be strong- 
 er or weaker, more or less definite, according to the range and 
 complexity of the vibrations : they will, however, be undulato- 
 ry, since they will always result from successive and continuous 
 movements, and will consequently be in the conditions which, 
 as we have seen, are required for the transmission of speech. 
 
 As for the action produced upon the receiver that is, on the 
 instrument for reproducing speech it is somewhat complex, 
 and we shall have occasion to speak of it presently ; but we 
 can get a general impression of it, if we consider that the ef- 
 fects produced by the induced currents of variable intensity, 
 which traverse the coil of the electro -magnetic system, must 
 determine, by the magnetizations and demagnetizations which 
 ensue, the vibrations of the armature disk ; these vibrations, 
 more or less amplified and defined, exactly represent those of 
 the disk before which the speaker stands, and can only be ob- 
 tained from them. The effects are, however, in reality more 
 complex, although they are produced under analogous condi- 
 tions, and we shall have more to say about them when we 
 come to speak of the experiments made with the telephone. 
 It must, meanwhile, be observed that, for the reproduction of 
 speech, it is not necessary that the magnetic core should be of 
 soft iron, since the vibratory effects may follow from differen- 
 tial as well as from direct magnetization. 
 
BELL TELEPHONE. 63 
 
 ORDINARY ARRANGEMENT OF THE BELL TELEPHONE. 
 The arrangement most generally adopted for the telephone 
 the one represented in Fig. 21. It consists of a kind of cir- 
 
 FiQ. 21. 
 
 cular wooden box, fitted to the extremity of a handle, M, which 
 is also of wood, and contains the magnetic bar, N S. This 
 bar is fixed by means of a screw, t, and is so arranged as to be 
 moved forward and backward by tightening or loosening the 
 screw, a condition necessary in order to regulate the instru- 
 ment. At the free extremity of the bar the magnetic coil B is 
 fixed ; this must, according to MM. Pollard and Gamier, be 
 made of wire No. 42, so as to present a considerable number of 
 spirals. The ends of this coil generally terminate at the lower 
 end of the handle in two copper rods, /, /, which traverse its 
 length, and are fastened to two binding - screws, I, I', where 
 the line wires, C, C, are fixed. In the instruments made by M. 
 Breguet there are, however, no binding-screws, but a little twist, 
 made of two flexible wires covered with gutta-percha and silk, 
 is fastened to the two rods. A wooden cap is screwed to the 
 end of the handle, and the twist passes through a hole made in 
 this cap, so that there is no inconvenience in working the in- 
 strument. By laying hold of the ends of the wire twist with 
 pliers it is possible to join them to the circuit. This instru- 
 ment is represented in Fig. 22. 
 
64 THE TELEPHONE. 
 
 By another arrangement, the wires of the coil end immedi- 
 ately in the binding-screws which are placed below the wooden 
 box, but this arrangement is inconvenient. 
 
 FIG. 22. 
 
 Above the pole of the magnetic bar is placed the iron vibra- 
 ting plate, L L, which is coated either with black or yellow 
 varnish, with tin or blue oxide, but which must always be very 
 thin. This plate is in the form of a disk, and by its rim, resting 
 
BREGUET TELEPHONE. 65 
 
 on a caoutchouc ring, it is firmly fixed to the circular edges of 
 the wooden box, which is for this purpose made in two pieces. 
 These pieces are adjusted to each other, either by screws or by 
 spirals cut in half the thickness of the wood. This disk ought 
 to be as near as possible to the polar end of the magnet, yet 
 not so near as to produce contact between the two by the vi- 
 brations of the voice. Finally, the mouth-piece, R R' (Fig. 21), 
 which is in form of a wide funnel, terminates the upper part of 
 the box, and should be so arranged as to leave a certain space 
 between the disk and the edges of the hole V, which is open 
 in its centre. The size of the box should be so calculated as to 
 permit of its acting as a sounding-box, without, however, pro- 
 voking echoes and a confusion of sounds. 
 
 AVhen the instrument is properly made, it will produce very 
 marked effects ; and M. Pollard, one of the first Frenchmen to 
 take up the study of telephones, has written as follows on the 
 subject : 
 
 " The instrument which I have prepared gives results which 
 are truly astonishing. In the first place, when considering the 
 resistance, the introduction into the circuit of five or six per- 
 sons does not sensibly diminish the intensity of sounds. On 
 putting an instrument to each ear, the sensation is precisely 
 the same as if the correspondent were speaking some yards 
 behind. The intensity, the clearness, the purity of tone are 
 irreproachable. 
 
 " I can speak to my colleague in quite an undertone, scarce- 
 ly breathing, as I may say, and persons placed within two 
 yards of me will be unable to catch a single word of our con- 
 versation. 
 
 " On the part of the receiver, if any one raises his voice to 
 call me, I hear the call in all parts of my office, at least when 
 silence prevails there ; at any rate, when I am seated at my 
 table with the instrument some yards off, I can always hear 
 the call. In order to increase the intensity of sound, I fitted 
 
66 THE TELEPHONE. 
 
 the mouth-piece with a copper horn of conical shape, and un- 
 der these conditions words spoken in my bureau two or three 
 yards from the mouth-piece can be heard at the other end of 
 the line ; from my station, a little more than a yard from the 
 tube, I can hear and speak to my colleague without effort." 
 
 In using the ordinary Bell telephone, it is necessary to speak 
 distinctly before the mouth -piece of the telephone which is 
 handled, while the listener placed at the corresponding station 
 keeps the mouth-piece of the receiver to his ear. These two 
 
 FIG. 23. 
 
 instruments form a closed circuit with the two wires which 
 connect them, but one is enough to make the transmission per- 
 fect, if care is taken to place both instruments in connection 
 with the earth, which thus takes the place of the second wire. 
 M. Bourbouze asserts that the intensity of sound in the tele- 
 phone is much increased by employing this expedient, but we 
 believe that this increase depends upon the conditions of the 
 circuit, although he asserts that the fact can be proved in a 
 circuit not exceeding eighty yards. 
 
WILMOT'S EXPERIMENTS. 07 
 
 For practical purposes it is necessary to have two telephones 
 at each station, so as to hold one to the ear while speaking 
 through the other, as in Fig. 23. It is also much more easy to 
 hear with a telephone applied to each ear, in which case they 
 are held as in Fig. 24. In order not to fatigue the arms, an ar- 
 rangement has been made by which they are held before the 
 ears by a strap and spring which goes round the head. 
 
 The sending power of the telephone varies with different 
 voices. Mr. Preece asserts that shouting has no effect, and 
 
 PIG. 24. 
 
 that, in order to obtain a favorable result, the intonation must 
 be clear, the articulation distinct, and the sounds emitted must 
 resemble musical sounds as much as possible. 
 
 Mr. Wilmot, one of the electricians employed by the Post- 
 office, says that he has been able to make himself heard on 
 circuits through which no other voices were audible. The 
 vowel sounds are most readily transmitted, and among other 
 otters c,gj,k,fmd q are always repeated more imperfectly. 
 The ear requires practice, and the faculty of hearing varies in 
 
68 THE TELEPHONE. 
 
 a surprising degree in different people. Singing is very dis- 
 tinctly heard, as well as wind-instruments, especially the cor- 
 net- a -piston, which, when played in London, was heard by 
 thousands of people in the Corn Exchange at Basingstoke. 
 
 According to Mr. Hollo Russell, it is not necessary to isolate 
 the circuit of a telephone when the distance is relatively slight ; 
 thus, with a circuit of about 430 yards, it is possible to use a 
 simple copper wire, laid on the grass, without destroying the 
 telephonic transmission from a small musical-box, as long as 
 the two wires do not touch each other. Transmission took 
 place, even when the circuit was buried in moist earth for a 
 length of thirty-five yards, or immersed in a well for a length 
 of forty-eight yards. The words transmitted under such con- 
 ditions did not differ from those transmitted by an isolated 
 circuit. 
 
 The telephone may be heard at the same moment by several 
 listeners, either by connecting the wires which unite the tele- 
 phones in correspondence (near the receiving telephone) with 
 branch wires of other telephones, which may be done up to 
 the number of five or six, in short circuits ; or by means of 
 a little sounding-box closed by two thin membranes, one of 
 which is fixed on the vibrating disk. When a certain num- 
 ber of acoustic tubes are connected with the membrane, Mr. 
 M'Kendrick asserts that several people can hear distinctly. 
 
 Telephones may also transmit speech to different stations 
 simultaneously, by inserting them on the same circuit, and ex- 
 periments made at New York showed that five instruments 
 placed in different parts of the same telegraphic line could be 
 made to speak in this way. In the telephonic experiments 
 made on the canal lines in the department of the Yonne, it 
 was ascertained that on a wire seven miles and a half in length, 
 on which several telephones were placed at varying distances, 
 three or four persons were able to converse with each other 
 through the telephones, and each could hear what the other was 
 
EXPERIMENTS AT CHERBOURG. 69 
 
 saying. The questions and answers could be understood, even 
 in crossing. It was also possible, by placing a telephone on a 
 second wire, a little over five miles in length, and half a yard 
 distant from the other, to hear the conversation exchanged on 
 the first wire by following it to a distance not exceeding a 
 mile and a quarter. Even the different voices of the two 
 speakers could be distinguished. 
 
 Since the telephone made its appearance in Europe, several 
 inventors have asserted that they are able to make a telephone 
 speak so as to be audible in all parts of a large hall. It has 
 been shown that this was accomplished by Mr. Bell, and in 
 this respect we do not see that those who have attempted to 
 improve the telephone have attained results of greater impor- 
 tance. It is certain that the ordinary telephone can emit musi- 
 cal sounds which become perfectly audible in a tolerably large 
 room, while the instrument is still attached to the wall. We 
 should also remember the results obtained by MM. Pollard and 
 Gamier in the experiments made at Cherbourg to connect the 
 mole with the Prefecture Maritime. 
 
 The mole at Cherbourg is, as we know, a kind of artificial 
 island thrown up before the town in order to make an anchor- 
 age. The forts which have been constructed on the mole are 
 connected by submarine cables with the military port and with 
 the Prefecture Maritime. On one occasion, after making ex- 
 periments in the prefet's study on one of the cables applied to 
 a telephone, several persons were talking together in the room, 
 and were much surprised to hear the bugle sound the retreat, 
 the sound appearing to come from one part of the room. It 
 was found, on examination, that the telephone hung to the 
 wall was occupied with this performance. On inquiry, it ap- 
 peared that one of the manipulators on the mole station had 
 amused himself by sounding the bugle before the telephone on 
 that station. The mole is more than three miles from Cher- 
 bourg, and the Prefecture Maritime is in the centre of the 
 
70 THE TELEPHONE. 
 
 town. Yet these telephones had been roughly made in the 
 dock-yard workshops ; and we have here another proof of the 
 small amount of accuracy required for the successful working 
 of these instruments. 
 
 Telephones of various construction on the Bell model are to 
 be seen, at M. C. Roosevelt's, Mr. Bell's agent in Paris, 1 Rue 
 de la Bourse. They are, for the most part, constructed by M. 
 Breguet, and the model in the greatest request, exclusive of 
 the one we have described, is the great square model, with a 
 horseshoe magnet enclosed in a flat box, and a horn on its up- 
 per side, which serves as a mouth-piece. This system is repre- 
 sented in Fig. 25, and it has been neatly constructed at Boston 
 
 FIG. 25. 
 
 under the best conditions. In this new model, made by Mr. 
 Gower, the magnet is composed of several plates terminated by 
 magnetic cores of iron, to which the coils are fixed, and the 
 whole is covered with a thick layer of paraffine. The sounds 
 thus reproduced are much stronger and more distinct. Mr. 
 Gower, who is now Mr. Roosevelt's partner, has made consider- 
 able improvements in the different forms of Mr. Bell's instru- 
 ment. There is one model in the form of a snuffbox, in 
 which the magnet is twisted into a spiral, so as to maintain its 
 length in a circular form. The pole, which is in the centre of 
 
DIFFERENT MODELS OF TELEPHONES. 71 
 
 the spiral, is furnished with an iron core, to which the induc- 
 tion coil is fastened, and the cover of the snuffbox supports 
 the vibrating disk as well as the mouth-piece : this model is 
 represented in Fig. 26. In another model, called the mirror 
 
 FIG. 26. 
 
 telephone, the preceding arrangement is fitted on to a handle 
 like the glass of a portable mirror, and there is a mouth-piece 
 on one of the lateral faces, so that the speaker uses the instru- 
 ment as if he were speaking before a chimney screen. 
 
 Mr. Bailey has different models of telephones worked by a bat- 
 tery or by the Edison carbon, of which we shall speak presently, 
 and these, as well as the telephones by Messrs. Gray and Phelps, 
 are more successful in conveying sound on a long line of wire. 
 
 DIFFERENT ARRANGEMENTS OF TELEPHONES. 
 The prodigious results attained with the Bell telephones, 
 which were at first discredited by many scientific men, neces- 
 sarily provoked, as soon as their authenticity was proved, in- 
 numerable researches on the part of inventors, and even of 
 those who were originally the most incredulous. A host of 
 improvements and modifications have consequently been sug- 
 
72 THE TELEPHONE. 
 
 gested, which are evidently not without interest, and must now 
 be considered by us. 
 
 BATTEKY TELEPHONES. 
 
 The Edison Telephone. One of the earliest and most inter- 
 esting improvements made in the Bell telephone is that intro- 
 duced by Mr. Edison in the early part of the year 1876. This 
 system is indeed more complicated than the one we have just 
 considered, since it requires a battery, and the sending instru- 
 ment differs from the receiving instrument; but it is less apt 
 to be affected by external causes, and transmits sound to a 
 greater distance. 
 
 The Edison telephone, like Mr. Gray's, which we have al- 
 ready had occasion to mention, is based upon the action of 
 undulatory currents, determined by the variations in the re- 
 sistance of a conductor of moderate conducting power, which 
 is inserted in the circuit, and the vibrations of a diaphragm be- 
 fore which the speaker stands react upon it. Only, instead of 
 employing a liquid conductor, which is practically useless, Mr. 
 Edison has attempted to use semi -conducting solid bodies. 
 Those which were most suitable from this point of view were 
 graphite and carbon, especially the carbon extracted from com- 
 pressed lamp-black. When these substances are introduced 
 into a circuit between two conducting plates, one of which is 
 movable, they are capable of modifying the resistance of the 
 circuit almost in the same proportion as the pressure exerted 
 upon them by the movable plate, 1 and it was seen that, in or- 
 
 1 This property has long been known, but not applied. In 1856, in the 
 second edition of my Expose des applications d Electridte, I pointed them 
 out in speaking of the contact-breakers. I also spoke of them in a paper 
 on electro-magnets (published in the Annales telegraphiques, 1865), and in 
 several articles laid before the Academic des Scietices in 1872 and 1875 on 
 the conductivity of filings and conducting powders. M. Clerac, in 1865, 
 also used them to obtain variable resistances. 
 
EDISOX TELEPHONE. 
 
 der to obtain the undulatory currents necessary for the pro- 
 duction of articulate sounds, it was enough to introduce a disk 
 of plumbago or of lamp-black between the vibrating plate of a 
 telephone and a platinum plate placed in connection with the 
 battery. When the telephone disk is placed in circuit, its vi- 
 brations before the disk of carbon produce a series of increas- 
 ing and decreasing pressures, thus causing corresponding ef- 
 fects in the intensity of the transmitted current, and these 
 effects react in an analogous manner on the undulatory cur- 
 rents determined by induction in the Bell system. In order 
 to obtain good results, however, several accessory arrangements 
 were necessary, and we represent in Fig. 27 one of the arrange- 
 ments made in this part 
 of Mr. Edison's telephon- 
 ic system. 
 
 In this figure a sec- 
 tion of the instrument 
 is given, and its form 
 greatly resembles that 
 of Bell. L L is the vi- 
 brating disk ; 0' 0, the 
 mouth -piece; M, the 
 opening to the mouth- 
 piece ; N N N, the case 
 for the instrument, 
 which is, like the mouth- 
 piece, made of ebonite, 
 and below the disk it 
 presents a rather large 
 cavity, and a tubular hole 
 which is scooped in the 
 handle. In its upper part this tube terminates in a cylindrical 
 rim, furnished with a worm on which is screwed a little rod with 
 a ridge on its inner side, and the rheostatic system is placed 
 
 4 
 
74 THE TELEPHONE. 
 
 within this tube. The system consists, first, of a piston, E, fitted 
 to the end of a long screw, E F, and the turning of the button 
 will move the piston up or down within a certain limit. Above 
 this piston there is fitted a very thin platinum plate, A, con- 
 nected by a flexible chain and a wire with a binding-screw, P'. 
 Another plate, B, exactly similar, is connected with the bind- 
 ing-screw P, and the carbon disk, C, is placed between these 
 two plates. This disk is composed of compressed lamp-black 
 and petroleum, and its resistance is one ohm, or 110 yards, of 
 telegraphic wire. Finally, an ebonite disk is fastened to the 
 upper platinum plate, and an elastic pad, composed of a piece 
 of caoutchouc tube, G, and of a cork disk, H, is interposed be- 
 tween the vibrating plate L L and the disk B, in order that 
 the vibrations of the plate may not be checked by the rigid 
 obstacle formed by the whole rheostatic system. When these 
 different parts are in position, the instrument is regulated by 
 the screw F, and this is easily done by screwing or unscrewing 
 it until the receiving telephone gives out its maximum of 
 sound. 
 
 In another model, represented in Fig. 28, which has produced 
 the best results in the distinctness with which sounds are trans- 
 mitted, the vibrating plate, L L, is supported on the disks of 
 
 the secondary carbon 
 conductor, C, by means 
 of a little iron cylinder, 
 A, instead of the caout- 
 chouc pad, and the 
 pressure is regulated by 
 a screw placed below e. 
 FlG ' 28 ' The mouth -piece, E, of 
 
 the instrument is more prominent, and its opening is larger. 
 Finally, the instrument, which is cased in nickel silver, is with- 
 out a handle. The rigid disk, 5, resting on the first platinum 
 plate, p, is of aluminium instead of ebonite. 
 
ANOTHER EDISON TELEPHONE. 
 
 75 
 
 The receiving telephone somewhat resembles that of Mr. 
 Bell, yet it presents some differences which can be understood 
 from the examination of Fig. 
 29. The magnet, N S, is C 
 horseshoe in form, and the 
 magnetizing coil, E, only cov- 
 ers one of the poles, N : this 
 pole is precisely in the centre 
 of the vibrating plate, L L, 
 while the second pole is near 
 the edge of this plate. The 
 size of the plate itself is con- 
 siderably reduced: its super- 
 ficies is about the same as 
 that of a five-franc piece, and 
 it is enclosed in a kind of 
 circular groove, which keeps 
 it in a definite position. In 
 consequence of this arrange- 
 ment, the handle of the in- 
 strument is of solid wood, 
 and the vacant space for the electro-magnetic system is some- 
 what larger than in the Bell model ; but an arrangement is 
 made for subduing the echo, and there is a kind of sounding- 
 box to magnify the sound. It is evident that the relation 
 which the electro-magnetic system bears to the vibrating disk 
 must increase the sensitiveness of the instrument; for as the 
 pole S is in close contact with the disk, L L, the latter is polar- 
 ized, and becomes more susceptible to the magnetic influence 
 of the second pole, N, which is separated from it by an interval 
 not exceeding the thickness of a sheet of coarse paper. In Mr. 
 Edison's two instruments, the receiver and sender, the upper 
 part, C C, corresponding to the vibrating disk, instead of being 
 fixed by screws to the handle, is screwed on to the handle it- 
 
 FIG. 29. 
 
76 THE TELEPHONE. 
 
 self, which makes it much more easy to dismount the instru- 
 ment. 
 
 Mr. Edison has varied the form of his instruments in many 
 ways, and their cases have of late been made of metal with a 
 funnel-shaped mouth-piece of ebonite. 
 
 When Mr. Edison had ascertained, as indeed Mr. Elisha Gray 
 had done before him, that induced currents are more favorable 
 to telephonic transmissions than voltaic currents, he transformed 
 the currents from the battery which passed through his sender 
 into induced currents by making them pass through the pri- 
 mary circuit of a carefully insulated induction coil ; the line 
 wire was then put into communication with the secondary wire 
 of the coil. We shall afterward describe some experiments 
 which show the advantages of this combination : for the pres- 
 ent we can only point out the fact, for it is now an integral 
 quality of almost all the systems of battery telephones. 
 
 Edison's Chemical Telephone. The curious and really useful 
 effects produced by Mr. Edison with his electro - motograph 
 prompted, about the beginning of the year 1877, his idea of 
 applying the principle of this instrument to the telephone for 
 the reproduction of transmitted sounds ; and he obtained such 
 interesting results that the author of an article on telephones, 
 published in the Telegraphic Journal, August 15th, 1877, put 
 forward this invention as one of the finest of the nineteenth 
 century. It certainly appears to have given birth to the pho- 
 nograph, which has lately become famous, and has so much 
 astonished men of science. 
 
 To understand the principle of this telephone, we must give 
 some account of Mr. Edison's electro-motograph, discovered in 
 1872. This instrument is based upon the principle that if a 
 sheet of paper, prepared with a solution of hydrate of potash, 
 is fastened on a metallic plate which is united to the positive 
 pole of a battery, and if a point of lead or platinum connected 
 with the negative pole is moved about the paper, the friction 
 
TELEPHONIC RECEIVER. 77 
 
 which this point encounters ceases after the passage of the cur- 
 rent, and it is then able to slide as if upon a mirror until the 
 current is interrupted. Now, as this reaction may be effected 
 instantaneously under the influence of extremely weak currents, 
 the mechanical effects produced by these alternations of arrest 
 and motion may, by a suitable arrangement of the instrument, 
 determine vibrations in correspondence with the interruptions 
 of current produced by the transmitter. 
 
 In this system the telephonic receiver consists of a resonator 
 and a drum mounted on an axis and turned by a winch. A 
 paper band, wound upon a reel, passes over the drum, of which 
 the surface is rough, and a point tipped with platinum, and fit- 
 ted to the end of a spring which is fixed in the centre of the 
 resonator, presses strongly on the paper. f The current from 
 the battery, first directed on the spring, passes by the platinum 
 point through the chemical paper, and returns by the drum to 
 the battery. On turning the winch, the paper moves forward, 
 and the normal friction which is produced between the paper 
 and the platinum point pushes the point forward, while pro- 
 ducing, by means of the spring, a tension on one side of the 
 resonator; but since the friction ceases at each passage of the 
 current through the paper, the spring is no longer drawn out, 
 and the resonator returns to its normal position. Since this 
 double effect is produced by each vibration made in the sender, 
 a series of vibrations takes place in the resonator, repeating 
 those of the sender, and consequently the musical sounds 
 which affected the sender are reproduced to a certain extent. 
 According to the American journals, the results produced by 
 this instrument are astonishing: the weakest currents, which 
 would have no effect on an electro-magnet, become perfectly effi- 
 cacious in this way. The instrument can even reproduce with 
 great intensity the highest notes of the human voice, notes 
 which can hardly be distinguished by the use of electro-magnets. 
 
 The sender nearly resembles the one we have previously de- 
 
78 THE TELEPHONE. 
 
 scribed, except that, when it is used for musical sounds, a plati- 
 num point is employed instead of the disk of carbon, and it 
 ought not to be in constant contact with the vibrating plate. 
 According to the Telegraphic Journal, it consists simply of a 
 long tube, two inches in diameter, having one end covered with 
 a diaphragm formed of a thin sheet of copper, and kept in its 
 place by an elastic ring. A small platinum disk is riveted to 
 the centre' of the copper diaphragm, and a point of the same 
 metal, fitted with a firm support, is adjusted before the disk. 
 When the singer stands before the diaphragm, its vibration 
 causes it to touch the platinum point, and produces the num- 
 ber of breaks in the current which corresponds to the vibration 
 of the notes uttered. 
 
 The experiments lately made in America, in order to decide 
 on the merits of various telephonic systems, show that Mr. 
 Edison's telephone gives the best results. The Telegraphic 
 Journal, May 1st, 1878, states that on April 2d Mr. Edison's 
 carbon telephone was tested between New York and Phila- 
 delphia on one of the numerous lines of the Western Union. 
 The length of the line was 106 miles, and ran parallel to other 
 wires almost throughout its length. The effects of induction 
 caused by telegraphic transmissions through the adjacent wires 
 were enough to make speech inaudible through the other tele- 
 phones, but they had no influence on Edison's telephone, which 
 was worked With a battery of two cells and a small induction 
 coil, and Messrs. Batchelor, Phelps, and Edison were able to 
 converse with ease. Mr. Phelps's magnetic telephone, which is 
 considered to be the most powerful of its kind, did not afford 
 such good results. 
 
 In the experiments made between the Paris Exhibition build- 
 ing and Versailles, the jury commission was able to ascertain 
 that the results were equally favorable. 
 
 Telephones by Colonel Navez. Colonel Navez, of the Bel- 
 gian Artillery, inventor of the well-known balistic chronograph, 
 
NAVEZ TELEPHONE. 79 
 
 has endeavored to improve the Edison telephone by employ- 
 ing several disks of carbon instead of one. He considers that 
 the variations of electric resistance produced by carbon disks 
 under the influence of unequal pressure depend chiefly on their 
 surface of contact, and he consequently believes that the more 
 these surfaces are multiplied, the greater the differences in 
 question will be, just as it happens when light is polarized 
 through ice. He adds that these disks act well by their sur- 
 faces of contact, since, if they are separated by copper disks, 
 the speech reproduced ceases to be articulate. 1 
 
 I am not surprised to learn that Colonel Navez has found a 
 limit to the number of carbon disks, for the reproduction of 
 speech in this system is due both to the greatness of the dif- 
 ferences of resistance in the circuit and to the intensity of the 
 transmitted current. If, therefore, the instrument's sensitive- 
 ness to articulate sounds is increased by increasing the number 
 of imperfect contacts in the circuit, the intensity of the trans- 
 mitted sounds is diminished, and thus sounds lose their power. 
 There is consequently a limit to be observed in the number of 
 carbon disks placed upon each other; and it depends on the 
 nature of the imperfect contacts which are employed, and on 
 the tension of the electric generator. 
 
 In order to stop the unpleasant musical vibrations which ac- 
 company telephonic transmissions, Colonel Navez employs for 
 the vibrating plate of the sender a silver-plated copper disk, 
 and for the vibrating plate of the receiver an iron disk lined 
 with brass and soldered together. He also employs caout- 
 chouc tubes with mouth-pieces and ear-tubes for the transmis- 
 sion and reception of sound, and these instruments are placed 
 level on a table. For this purpose the magnetized bar of the 
 
 1 In 1865 I was able to verify this observation when tightening the 
 spirals of an electro-magnet on a naked wire. The greater the number 
 of spirals under pressure, the more definite were the differences of resist- 
 ance in the magnetizing helix. 
 
80 
 
 THE TELEPHONE. 
 
 receiving telephone is replaced by two horizontal magnets, act- 
 ing through a pole of the same nature on a little iron core 
 which carries the coil, and which is placed vertically between 
 the two magnets. He necessarily makes use of a small Ruhm- 
 korff coil to transform the electricity of the battery into in- 
 duced electricity. 
 
 FIG. 30. 
 
 Figs. 30 and 31 represent the two parts of this telephonic 
 system. The carbon battery is in C (Fig. 30), the vibrating 
 disk in L L, and the mouth -piece, E, fitted to a caoutchouc 
 tube, T E, corresponds at the lower end to the vibrating disk. 
 The carbon battery is placed in metallic contact with the cir- 
 cuit by a platinum rod, E C, and the vibrating disk also com- 
 municates with the circuit through a binding-screw. In the 
 receiving telephone (Fig. 31) the upper part is arranged much 
 as in the ordinary telephones, except that, instead of a mouth- 
 
POLLABD AND GAKXIER TELEPHONE. 
 
 81 
 
 piece, the instrument is fitted with an ear-tube, T O. The two 
 horseshoe magnets, A A, which communicate a uniform polar- 
 ity to the iron core, N, support the induction coil B. The 
 two terminals of this receiver are connected with the supple- 
 mentary wire of the induction coil, and the two terminals of 
 the sender are connected with the two ends of the primary of 
 this coil, and with the battery which is inserted in the circuit 
 near this instrument. 
 
 o 
 
 -I/./, '''' 
 
 
 FIG. 31. 
 
 The Pollard and Gamier Telephones. The battery tele- 
 phone made by MM. Pollard and Gamier differs from the 
 foregoing in this particular : it simply employs two points of 
 graphite, mounted in metallic porte-crayons, and these points 
 are directly applied against the vibrating plate with a" pressure 
 which must be regulated. Fig. 32 represents the arrangement 
 adopted, which, however, may be infinitely varied. 
 
 L L is the vibrating tin plate, above which is the mouth- 
 4* 
 
82 THE TELEPHONE. 
 
 piece E, and P, P' are the two graphite points, with their porte- 
 
 crayons. There is a screw on 
 the lower part of the porte-cray- 
 ons which is fixed in a hole 
 pierced in a metallic plate, C C, 
 and by this means the pressure 
 of the pencils against the disk 
 L L can be regulated. The me- 
 tallic plate C C is made in two 
 
 pieces, placed side by side, but insulated from each other, so 
 that they may be placed in communication with a cylindrical 
 commutator, and by its means the circuit can be arranged in 
 different ways. Since the commutator consists of five sheets, 
 the transition from one combination to another is instantane- 
 ous, and these combinations are as follows : 
 
 1. The current enters by the pencil P, passes into the plate, 
 and so to line. 
 
 2. The current enters by the pencil P', passes into the plate, 
 and so to line. 
 
 3. The current comes simultaneously by the two pencils, P 
 and P', goes into the plate, and thence to line. 
 
 4. The current comes by the pencil P, goes thence to the 
 plate, then into the pencil P', and so to line. 
 
 By this means there are two elements of combination, which 
 may be employed separately, or by coupling them for tension 
 or quantity. 
 
 When the pencils are properly regulated and give a regular 
 transmission of equal intensity, the effects produced in the tran- 
 sition from one combination to another may be easily studied, 
 and it has been ascertained : first, that in a short circuit there 
 is no appreciable change, whatever be the combination employ- 
 ed ; secondly, that when the circuit is long, or of great resist- 
 ance, the tension arrangement is the best, and this in propop 
 tion to the length of the line. 
 
HELLESEN'S REACTION TELEPHONE. 83 
 
 This telephonic system, like the two preceding ones, requires 
 an inducing machine to transform voltaic into induced cur- 
 rents : we shall presently speak of this important accessory of 
 these instruments. 
 
 Besides this arrangement, MM. Pollard and Gamier have 
 employed the one we have represented in Fig. 5, which has 
 given better results. We shall see presently that it can be 
 used as the receiving organ of sounds. In each case the two 
 carbons must be placed in contact, and subjected to a certain 
 initial pressure, which should be regulated by the screw fitted 
 to the support of the lower carbon. 
 
 As for the receiving telephone, the arrangement adopted by 
 MM. Pollard and Gamier is the same as Bell's, except that they 
 employ tin plates and helices of, greater resistance. This re- 
 sistance ranges, in fact, from 100 to 125 miles. "We have al- 
 ways held," these gentlemen say, " that whatever may be the 
 resistance of the outer circuit, there is an advantage in increas- 
 ing the number of spirals, even when using wire No. 42, which 
 is the one we prefer." 
 
 M. Hellesen's Reaction Telephone. M. Hellesen believed 
 that the vibrations produced by the voice on the carbon of a 
 telephonic sender would be magnified if the movable part of 
 the rheotome were subjected to an electro-magnetic action re- 
 sulting from the vibrations themselves, and he has contrived a 
 sender, which is based on the principle shown in Fig. 33, and 
 which has the merit of forming in itself the inducing appara- 
 tus intended to transform the voltaic currents employed. This 
 instrument is composed of a vertical iron tube, supported on a 
 magnetic bar, N S, and surrounded by a magnetizing coil, B B, 
 above which is fixed an inducing helix of fine wire, I I, com- 
 municating with the circuit. Within the tube there is a lead 
 pencil, C, held by a porte-crayon, which can be raised or lower- 
 ed by means of a screw, V, fixed below the magnetic bar. 
 Finally, above this pencil there is an iron vibrating plate, L L, 
 
84 
 
 THE TELEPHONE. 
 
 with a platinum point in communication with the battery in 
 its centre ; the local circuit communicates with the pencil by 
 means of the magnetizing helix B, and for this purpose one 
 end is soldered to the iron tube. 
 
 FIG. 33. 
 
 From this arrangement it follows that the vibrations of the 
 plate L L, at the moment when it comes nearest to the pencil, 
 tend to become greater in consequence of the attractive force 
 exerted on the plate ; and as the pressure of the lead pencil is 
 increased, it increases the differences of resistance which result 
 from it, and consequently causes greater variations in the in- 
 tensity of the transmitted currents. 
 
 Reaction Telephone of Messrs. Thomson and Houston. The 
 telephonic arrangement we have described has lately been 
 adopted by Mr. Elihu Thomson and Mr. Edwin J. Houston, 
 who, on June 21st, 1878, two months after M. Hellesen ex- 
 plained his system to me, 1 published an article in The English 
 
 1 M. Hellesen communicated the plan of his instrument to me on May 
 3d, 1878, and his experiments were made in Copenhagen three weeks ear- 
 lier. 
 
THOMSON AND HOUSTON TELEPHONE. 85 
 
 Mechanic and World of Science about an instrument very sim- 
 ilar to that of M. Hellesen. 
 
 In their instrument the current, which passes through a 
 body of moderately conducting capacity, acts on an electro- 
 magnet provided with an induction coil, and this electro-mag- 
 net reacts on the diaphragm, in order to increase the range of 
 its vibrations, and to create at the same moment two electric 
 actions in the same direction : the only difference lies in the 
 arrangement of the contact of this indifferent conductor with 
 the vibrating plate. Instead of a simple contact effected by 
 pressure between this plate and a carbon pencil, a fragment of 
 the same substance with a sharpened point is fixed on the vi- 
 bratirg plate, and it dips into a drop of mercury which has 
 been poured into the receptacle made for it at the upper end 
 of the electro-magnet. In other respects the arrangement of 
 the instrument is that of an ordinary telephone, and the iron 
 rod of the electro-magnet represents the magnetized bar of the 
 Bell telephone. The inventors assert that this instrument can 
 be used both as a sender and receiver, and it is in the follow- 
 ing manner that it is worked in each case : 
 
 AVhen the instrument is transmitting, the morsel of carbon 
 dips more or less into the mercury, and consequently differ- 
 ences are produced in the surfaces of contact, according to the 
 range of vibrations made by the plate; the current varies in 
 intensity in proportion to this range, and induced currents in 
 the induction coil result from these variations; the induced 
 currents react on the receiving telephone, as in Bell's instru- 
 ment, and are further strengthened by those which are pro- 
 duced electrically by the movement of the diaphragm before 
 the induction coil, and the iron of the electro-magnet. 
 
 When the instrument is used as a receiver, the usual effects 
 are displayed ; for since the iron of the electro-magnet is mag- 
 netized by the current, its conditions are precisely those of the 
 ordinary Bell telephone, and the induced currents reach it in 
 
86 THE TELEPHONE. 
 
 the same manner, only with greater intensity. Messrs. Thom- 
 son and Houston assert that their system has produced excel- 
 lent results, and that by it the sound of the voice is much less 
 altered than in other telephones. 
 
 Telephones with Batteries and Liquid Senders. - We have 
 seen that in 1867 Mr. Gray conceived the idea of a telephonic 
 system based on the differences of resistance effected in a cir- 
 cuit completed by a liquid, when the layer of liquid interposed 
 between the electrodes varies in thickness under the influence 
 of the vibrations of the telephonic plate which is in communi- 
 cation with one of these electrodes. This system has since been 
 the subject of study by several inventors, among others by 
 MM. Richemond and Salet, and I give some of the accounts 
 which have been published respecting their researches. 
 
 Another telephone for the reproduction of articulate sounds, 
 which M. Richemond terms the electro-hydro telephone, has been 
 recently patented in the United States. It resembles that of 
 Mr. Edison in some respects ; but instead of making use of car- 
 bon disks to modify the resistance of the circuit, water is em- 
 ployed, and this water is placed in communication with the cir- 
 cuit and battery by means of two platinum points, one of which 
 is fixed on the metallic diaphragm which vibrates under the 
 influence of the voice. As the vibrations of the diaphragm 
 transport the point which is attached to it to different parts 
 of the interpolar layer of liquid, they diminish or increase the 
 electric resistance of this layer, and cause corresponding varia- 
 tions in the intensity of the current traversing the circuit. The 
 receiving telephone is of the usual kind. (See Telegraphic 
 Journal, September 15th, 1877.) 
 
 M. Salet writes : " I thought it would be interesting to con- 
 struct a telephone in which there should be absolute solidarity 
 in the movements of the two membranes, and for this purpose 
 I have availed myself of the great resistance of liquids. Mr. 
 Bell had already obtained some results by attaching to the vi- 
 
LIQUID TELEPHONE. 87 
 
 brating membrane a platinum wire communicating with a bat- 
 tery, and dipping more or less into a metallic vessel, itself con- 
 nected by the line with the receiving telephone and containing 
 some acidulated water. I have substituted for the platinum 
 wire a small aluminium lever supporting a disk of platinum, 
 and at a very slight distance from it there is a second disk in 
 connection with the line. The vibrations of the membrane, 
 tripled or quadrupled in their range, are not altered in form, 
 thanks to the small size and light weight of the lever : they 
 cause variations in the thickness of the liquid layer traversed 
 by the current, and consequently in its intensity, and these va- 
 riations cause corresponding differences in the attractive force 
 of the receiving electro-magnet. Under its influence the re- 
 ceiving membrane executes movements which are identical with 
 those of the sending membrane. The sound transmitted is 
 very distinct, and its timbre is perfectly maintained a result 
 which might have been anticipated. The consonants, however, 
 are not so clearly pronounced as those transmitted by Mr. Bell's 
 instrument. This inconvenience is most apparent when the 
 lever is heavy, and might easily be obviated. The electrolysis 
 also produces a continual murmur, but this does not interfere 
 with the distinctness of the sound. 
 
 " Since, on this system, the voice is not required to produce, 
 but only to direct, the electric current generated by a battery, 
 the intensity of the sound received might in theory be increased 
 at pleasure. I have, in fact, been able to make the receiver emit 
 very powerful sounds, and I think that this advantage greatly 
 counterbalances the necessity of employing a battery, and a 
 somewhat delicate sending instrument. Unfortunately it can 
 only be used for moderate distances. Assuming that any dis- 
 placement of the transmitting membrane increases the resist- 
 ance to a degree equivalent to five or six hundred yards of 
 wire : if the line is five hundred yards long, the intensity of 
 the current will be reduced by one-half, and the receiving mem- 
 
88 THE TELEPHONE. 
 
 brane will take up a fresh position, considerably differing from 
 the first ; but if the line is three hundred miles in length, the 
 intensity of the current will only be modified by a thousandth 
 part. An immense battery must therefore be employed in or- 
 der that this variation may be translated by a sensible change 
 in the position of the receiving membrane." (See Comptes 
 Rendus de V Academic des Sciences, February 18th, 1878.) 
 
 M. J. Luvini, in an article inserted in Les Mondes, March 7th, 
 1878, has suggested a system of rheotome by means of a cur- 
 rent, for battery telephones, which, although complicated, possi- 
 bly offers some advantages, since it produces currents alternate- 
 ly reversed. In this system the vibrating disk of the sender, 
 which should be in a vertical position, reacts on a movable hor- 
 izontal wire, turned back at a right angle, and supporting on 
 each of its branches two platinum points which dip into two 
 bulbs, filled with a liquid of moderate conducting capacity. 
 The two branches of this wire, insulated from each other, are 
 placed in communication with the two poles of the battery, and 
 the four cups into which the platinum wire dips communicate 
 inversely with the line and the earth by means of platinum 
 wires immovably fixed in the cups. It follows from this ar- 
 rangement that, when the distances are duly regulated between 
 the fixed and movable wires, two equal currents will be opposed 
 to each other across the line circuit when the diaphragm is mo- 
 tionless ; but as soon as it vibrates, the respective distances of 
 the wires will vary, and it follows from this that there will be 
 a differential current, of which the intensity will correspond 
 with the extent of the displacement of the system, or with the 
 range of vibrations, and the direction will vary with the move- 
 ments above or below the line of the nodes of vibration. In 
 this way the advantage of the induced currents is obtained. 
 
 Telephones with a Battery and Voltaic Arcs. In order to 
 obtain variations of resistance of still greater sensitiveness than 
 is the case with liquids or pulverized substances, the idea has 
 
VOLTAIC ABC TELEPHONE. 89 
 
 been suggested of employing conductors of heated gas, and 
 several arrangements of battery telephones have been made in 
 which the circuit was completed by a stratum of air, separating 
 the vibrating disk from a platinum point, which serves to ex- 
 cite an electric discharge of high tension. Under these condi- 
 tions, the stratum of air becomes the conductor, and the inten- 
 sity of the current which traverses it corresponds to its thick- 
 ness. This problem has been solved, either by means of vol- 
 taic currents of high tension, or by a Ruhmkorff coil. 
 
 The former system was arranged by M. Trouve, and he 
 writes as follows on the subject in the journal La Nature of 
 April 6th, 1878: "A metallic vibrating membrane forms one 
 of the poles of a high-tension battery ; the other pole is fast- 
 ened before the disk by a micrometer screw, which can be ad- 
 justed so as to vary the distance from the disk according to 
 the tension of the battery, but without ever coming in contact 
 with it. The distance must not in any case exceed that to 
 which the discharge of the batteiy can extend. Under these 
 conditions, the membrane which vibrates under the influence 
 of the waves of sound has the effect of constantly modifying 
 the distance between the two poles, and thus of continually 
 varying the intensity of the current : consequently the receiv- 
 ing instrument (a Bell telephone, or telephone with an electro- 
 magnet) is subjected to magnetic variations, corresponding to 
 the variations of the current which affect it, and this has the 
 effect of making the receiving instrument vibrate at the same 
 moment. This kind of telephonic instrument relies, therefore, 
 on the possibility of varying within wide limits the resistance 
 of the outer circuit of a high-tension battery, in which the 
 poles are not in contact. In order to vary the conditions of 
 this resistance, it is also possible to interpose some vapor or 
 "other medium, such as air, or gas of greater or less rarity." 
 
 M. Trouve thinks that he was successful with his battery 
 of small disks, moistened with sulphate of copper and sulphate 
 
90 THE TELEPHONE. 
 
 of zinc, arranging these elements, to the number of five or six 
 hundred, in glass tubes of small diameter. It is well known 
 that it is unnecessary for the elements to be of large size in 
 order to obtain tension currents. 
 
 M. de Lalagade has suggested an analogous mode by em- 
 ploying for the formation of the arc a current of which the 
 tension is increased by inserting a strong electro-magnet into 
 the circuit. This electro-magnet acts on a Hughes magnet in 
 order to produce induction currents capable of making the re- 
 ceiving instrument act. M. de Lalagade says that a Bunsen 
 battery, or one of six cells with bichromate of potash, will be 
 enough to produce a continuous voltaic arc between the vibra- 
 ting plate of a telephone and a platinum point which is suffi- 
 ciently remote to avoid contact. It is necessary, however, to 
 begin with a contact, in order to produce the formation of this 
 arc. In M. de Lalagade's system the vibrating plate should 
 have in its centre a small platinum plate, in order to obviate 
 the oxidizing effects of the spark. The inventor asserts that 
 sounds transmitted in this way, and reproduced in a telephone 
 of which the electro-magnetic system is set upon a sounding- 
 box, will have greater intensity than the sounds transmitted 
 by an ordinary telephone, and the speaker will appear to be 
 close to the ear. 
 
 Mercury Telephones. These systems are based on the phys- 
 ical principle discovered by M. Lippmann, that if a layer of 
 acidulated water is placed above mercury, and connected with 
 it by an electrode and wire, every mechanical action which ex- 
 erts pressure on the surface of the mercury, and alters the 
 form of its meniscus, will cause an electric reaction, capable of 
 producing a current with a force which corresponds to the 
 mechanical action exerted. Conversely, every electric action 
 produced on the circuit of such a system will occasion a dis- 
 placement of the meniscus, and consequently its movement, 
 which will be more marked in proportion to the smallness of 
 
MERCURY TELEPHONE. 
 
 91 
 
 the tube in which the mercury is placed, and to the greatness 
 of the electric action. This electric action may result from a 
 difference of potential in the electric condition of the two ex- 
 tremities of the circuit, which communicate with the electric 
 source employed, or with some electric generator. 1 
 
 In accordance with these effects, it is intelligible that if two 
 tubes, T T, pointed at the end, and containing mercury, are 
 plunged into two vessels, V V (Fig. 34), containing acidulated 
 
 hlllllilulllilllllllllilllM 
 
 FIG. 34. 
 
 water and mercury, and metallic wires, P P, Q Q, are used, first 
 to connect the columns of mercury in the tubes, and secondly 
 the layers of mercury at the bottom of the two vessels, the 
 tubes being a little removed from the surface of the mercury 
 in the vessels, we shall then have a metallic circuit, completed 
 by two electrolytes, one of which will be subjected to the me- 
 
 1 M. M. J. Page had already noticed that if a telephone is placed in the 
 circuit of the primary helix of an induction coil, while the secondary helix 
 of this instrument is placed in the circuit of one of M. Lippmann's capil- 
 lary electrometers, a movement of the mercurial column of the electrome- 
 ter takes place at each word, and this movement is effected toward the 
 capillary end of the tube, in whatever direction the current is sent by the 
 telephone. This is because the mercury always tends to move more rapid- 
 ly at its capillary end than at the other extremity. 
 
92 THE TELEPHONE. 
 
 chanical or electrical effects produced in the other. If two vi- 
 bratory plates, B B, are placed above the tubes, and one of 
 these is caused to vibrate, the other will reproduce these vibra- 
 tions, influenced by the vibratory movements communicated 
 by the corresponding column of mercury. The vibrations 
 themselves will be in connection with the electrical discharges 
 resulting from the movements of the column of mercury in the 
 first tube, which are mechanically produced. If an electric 
 generator is introduced into the circuit, the effect which we 
 have just analyzed will be caused by modifications in the po- 
 tential of this generator, in consequence of electro-capillary ef- 
 fects. But if no generator is employed, the action will result 
 from electric currents determined by the electro-capillary at- 
 traction itself. In the latter case, however, the instrument 
 must be more delicately made, in order to obtain more sensi- 
 tive electric reaction, and M. A. Begruet describes his instru- 
 ment as follows : 
 
 " The instrument consists of a tube of thin glass, a few cen- 
 timetres in length, containing alternate drops of mercury and 
 acidulated water, so as to constitute so many electro-capillary 
 elements, connected in tension. The two ends of the tube are 
 fused together, yet so as to allow a platinum wire to touch the 
 nearest drop of mercury on each side. A small circle of thin 
 deal is fixed at right angles to the tube by its centre, thus pro- 
 viding a surface of some extent, which can be applied to the 
 ear when the instrument is a receiver, and to make the tube 
 more mobile under the influence of the voice when the instru- 
 ment is a sender. The following are the advantages offered 
 by instruments of this construction : 
 
 " 1. They do not involve the use of a battery. 
 
 " 2. The disturbing influence of the resistance of a long line 
 is almost destroyed in these instruments, although it is still ap- 
 preciable in the Bell telephone. 
 
 "3. Two mercury telephones, coupled together as we de- 
 
FBICTION TELEPHONES. 93 
 
 scribed above, are absolutely correlative, in this sense, that even 
 different positions in the equilibrium of the mercury in one of 
 them produce different positions of equilibrium in the opposite 
 instrument. It is therefore possible to reproduce at a distance, 
 without a battery, not merely faithful indications of oscillatory 
 movements, which is done by the Bell telephone, but also the 
 exact image of the most general movements." 
 
 Friction Telephones. Mr. E. Gray has quite recently applied 
 the principle of producing sounds by the friction of animal 
 tissues to the construction of a speaking telephone which may 
 be heard through a whole room, like the singing condenser. 
 He obtains this result by means of clock-work, which causes 
 the rotation of the metallic disk of which we have spoken 
 (p. 27), and on which a piece of skin is so arranged as to pro- 
 duce friction. A carbon or liquid telephone is placed at the 
 sending-station, in such a way as to react on an induction coil, 
 as in^the systems of Edison, Navez, or Pollard, and speech is 
 reproduced on the rotating disk, and is audible, as we have 
 said, without the necessity of approaching the ear to the in- 
 strument. 
 
 The best arrangement of the metallic disk on which the ani- 
 mal tissue rubs is that of a cylindrical box, of which the outer 
 lid is made of a thin sheet of zinc with a highly polished, 
 slightly oxidized surface ; for the agent of friction, glove- 
 leather slightly moistened with acidulated water may be used, 
 or a sinew of an ox, or skin taken from the ear or tail of 
 a pig. 
 
 MODIFICATIONS INTRODUCED IN THE CONSTRUCTION OF THE 
 BELL TELEPHONES. 
 
 The modifications which we have been considering relate to 
 the principle of the instrument ; those which we have now to 
 consider are only modifications in the form and arrangement 
 of the different organs which form the Bell telephone itself, 
 
94 THE TELEPHONE. 
 
 and which have been designed with the object of increasing 
 the intensity and distinctness of the sounds produced. 
 
 Telephones with Several Diaphragms. When we remember 
 that the induced currents caused in a magnet result from the 
 vibratory movements of the diaphragm, and that these are pro- 
 duced by the vibrations of the stratum of air interposed be- 
 tween this diaphragm and the vocal organ, it necessarily fol- 
 lows that if these vibrations of the air react on several dia- 
 phragms, each attached to its electro-magnetic organ, several 
 induced currents might be caused simultaneously, and if these 
 were properly connected, their effects on the receiver would be 
 so much the more intense, since the sounds produced would re- 
 sult from the combination of several sources of sound. Sev- 
 eral inventors, starting from this argument, have planned in- 
 struments of varying ingenuity, which we will now describe, 
 but without being able to declare who was the first to realize 
 this idea. It is, in fact, so simple that it probably suggested 
 itself to the minds of several inventors at the same time ; and 
 we see that while M. Trouve proposed this improvement in 
 France in November, 1877, it was tried in America and dis- 
 cussed in England, where indeed it was not expected to pro- 
 duce very favorable results. Mr. Preece wrote on the subject 
 in a paper entitled "On some Physical Points connected with 
 the Telephone," which was published in April, 1878. He ob- 
 serves that all the attempts to improve the telephone have end- 
 ed in disappointment and failure. One of the first attempts 
 of the kind was made by Mr. Wilmot, who expected to obtain 
 favorable results by augmenting the number of diaphragms, 
 helices, and magnets, connecting the helices in a series, and 
 causing them to act simultaneously, so as to increase the ener- 
 gy of the currents developed by the influence of the voice; 
 but experience showed that when the instrument acted direct- 
 ly, the vibratory effect of each of the diaphragms decreased in 
 proportion to their number, and the general effect remained 
 
95 
 
 the same as with a single diaphragm. Mr. Wilmot's instru- 
 ment was made in the beginning of October, 1877, and that of 
 M. Trouve was only an imitation of it. 
 
 On the other hand, we see that if the telephones with several 
 membranes were not successful in England, this was not the 
 case in America, for the telephones which experience has shown 
 to give the best results in that country are those of Mr. Elisha 
 Gray and Mr. Phelps, and these have several diaphragms. It 
 is evident that there are details of construction in these instru- 
 ments which may appear insignificant in theory, and which are 
 notwithstanding very important from a practical point of view, 
 and we believe that it is to this circumstance that instruments 
 of this kind owe their success or failure. Thus, for example, 
 it seems that the vibrations of air caused in the mouth-piece 
 ought to be immediately directed on the surface of the dia- 
 phragms by means of distinct channels; it is necessary that 
 the empty space round each diaphragm should be sufficiently 
 limited to prevent echoes and interruptions, unless the case is 
 so large that there is no danger of such effects. Above all, it 
 is necessary that the organs should be fixed in some material 
 unsusceptible of reverberation, and for this reason a preference 
 is given to iron or ebonite. It is certain that, when the instru- 
 ment is properly made, its effects are superior to those of the 
 Bell telephones ; and it is asserted in the Telegraphic Journal 
 that experiments were made with one of these instruments be- 
 fore the Royal Society, in London, May 1st, 1878, and that the 
 intensity of sound was in proportion to the number of dia- 
 phragms. This instrument was designed by Mr. Cox Walker, 
 of York, and possessed eight diaphragms. He considers that 
 this is the arrangement which gives the best results. 
 
 Mr. Elisha Gray's System. Mr. Elisha Gray's last system, 
 which we represent in Fig. 35, is one of those which have given 
 the best effects. It is made, as we see, of two telephones, side 
 by side, to which correspond two tubes, issuing from a common 
 
THE TELEPHONE. 
 
 mouth-piece, E. One of these telephones is seen in section in 
 the plate, the other in elevation, and they correspond to the 
 
 FIG. 35. 
 
 two branches of a nickel - plated horseshoe magnet, N IT S, 
 which may serve as a suspension ring. In that part of the 
 plate which represents the section, the induction coil is shown 
 in B, and the magnetic core, of soft iron, in A, which is screwed 
 to the polar end of the magnet S ; the vibrating plate is in L L, 
 and, as we see, the tube of the mouth-piece terminates on its 
 surface. 
 
 In another model there are four telephones side by side, in- 
 stead of two, and the effects produced are still more marked. 
 
 Mr. Phelps's System. This system is only deduced from the 
 last, but there are two models of it. In the larger one, which 
 
97 
 
 makes it possible to hear as distinctly as if the person with 
 whom conversation is held were speaking in a loud voice in the 
 same room, the two telephones are placed parallel to each other, 
 and so as to present their diaphragms vertically ; the space be- 
 tween these two diaphragms is occupied by a vertical tube, ter- 
 minating at its lower end in a horizontal tube corresponding to 
 the centres of the two diaphragms, and on this tube the mouth- 
 piece is fitted, which projects outside the box in which the in- 
 strument is enclosed. The induction coils, and the magnetic 
 cores which traverse them, follow the axis of the system, and 
 seem to constitute the axis of a wheel which is polarized by 
 the poles of a horseshoe magnet, of which the position with 
 reference to the surface of the diaphragms can be regulated by 
 movable screws. The appearance of the instrument somewhat 
 resembles a gyroscope, resting by a horizontal axis on two 
 shafts which issue from a flattened horseshoe magnet. 
 
 Above this system there is the electro-magnetic apparatus of 
 the call-bell, in which there is nothing peculiar, and which is 
 like the German alarums, of which we shall speak at the end 
 of this account. This instrument is remarkable for strength 
 and clearness of sound, and especially for its freedom from the 
 Punch and Judy voice so displeasing in other telephones. 
 
 Mr. Phelps's small model is in the form of an oblong or el- 
 liptical snuffbox, of which the two centres are occupied by two 
 telephonic systems, influenced by the same magnet. This mag- 
 net is placed in a horizontal position below the snuffbox, and 
 its poles correspond to the magnetic cores of the coils. These 
 cores are made of iron tubes, split longitudinally in order to 
 destroy irregular induction reactions, and the iron diaphragms 
 rest on five spiral springs, which raise them above the mag- 
 netic system. On their other surface the diaphragms are 
 provided with rings of some semi -elastic substance, which 
 prevent the central vibrations of the disks from becoming com- 
 plicated by those of their edges. The lid, hollowed out in very 
 
 5 
 
98 THE TELEPHONE. 
 
 shallow cavities, is next placed upon the disks, and there are 
 channels of communication in it to serve as a sounding-box. 
 The mouth-piece corresponds to one of these cavities, and the 
 other is closed by a small metallic stopper, which can be with- 
 drawn to regulate the instrument when necessary. Since the 
 vibrations of air are transmitted by the channels to both cavi- 
 ties, the two telephones act together, although at first sight 
 only one of them seems to be required to produce the effect. 
 
 Mr. Phelps praises the simultaneous effects produced on the 
 two instruments, which he ascribes, first, to the semi-elastic ring 
 surrounding the rim of each disk, and acting as the hammer of 
 the ear, that is, as a damper; then, to the longitudinal splits of 
 the magnetic core, and lastly to the small size of the cavities 
 left above the vibrating disks. The instrument is made of 
 ebonite, grooved on the surface in order to give a better grasp 
 to the hand. 
 
 Mr. Phelps has a new model, called the crown telephone, which 
 is now in use in America, together with Mr. Edison's carbon 
 sender. In it each of the two systems of the large model we 
 have described is worked by six horseshoe magnets radiating 
 round the magnetic core, and so arranged &at the north poles 
 correspond to this core, and the other poles to the circular rim 
 of the diaphragm. In this way the magnetic field is consider- 
 ably enlarged, and the sound much intensified. 
 
 In experiments recently made at Dr. Wells' s church, New 
 York, an assembly of three hundred people were able to hear 
 speech and vocal or instrumental music distinctly in different 
 parts of the hall. 
 
 Mr. Cox Walker's System. This system, on which we have 
 already said a few words, has exactly the arrangement of that 
 by Mr. Elisha Gray. The magnets which act upon the dia- 
 phragms are horseshoe, and separate pipes, issuing from a 
 common mouth-piece, direct the vibrations of air on the dia- 
 phragms. These, indeed, are only defined parts of one dia- 
 
TBOUVE'S SYSTEM. 99 
 
 phragm, bounded in a circle by mouth-pieces corresponding to 
 the air-pipes, and sufficiently restricted on their edges to limit 
 the field of vibration. 
 
 3/. Trouvffs System. M. Trouve has simplified the arrange- 
 ment of telephones with a double diaphragm, by designing the 
 instrument so as to make Bell's bar magnet react by both 
 poles at once on several disks. For this purpose he employs 
 a tubular magnet, and winds a helix throughout its whole 
 length, as we see in Fig. 36. This magnet is maintained in a 
 
 FIG. 36. 
 
 fixed position in the centre of a small cylindrical box, of which 
 the base is slightly funnel-shaped, thus acting as a mouth-piece 
 and acoustic tube. It is consequently pierced in the centre 
 with a hole larger at a, the station for speaking, than on the 
 opposite side, b. Between the base and the poles of the mag- 
 net there are two vibrating iron plates, M, M', one of which, M, 
 is pierced with a hole, a, of the same diameter as the hollow 
 part of the magnet, and consequently smaller than that of the 
 mouth-piece. Finally, several other plates, n y n, n, are ranged 
 in parallel lines between these two plates, so that the magnet 
 and its helix may pass through them. 
 
 When anything is said before the mouth-piece cr, the waves 
 of sound encountering the edges of the plate M place it in vi- 
 
100 THE TELEPHONE. 
 
 bration, and, continuing their passage inside the tubular mag- 
 net, they cause the plate M' to vibrate at the same time as M. 
 A double inducing action, therefore, takes place on the tubular 
 magnet, and this is translated by the induced currents devel- 
 oped in the helix, which have greater energy, since each of the 
 plates intensifies the magnetic effects produced at the pole op- 
 posite to the one they influence, which is always the case with 
 bar magnets when the inactive pole is provided with an arma- 
 ture. This advantage may even be obtained in the case of 
 ordinary telephones, if the screw which holds the magnet is 
 placed in contact with a mass of soft iron. 
 
 In M. Trouve's arrangement the induced currents, therefore, 
 possess greater energy; but he adds that the sounds repro- 
 duced will also be strengthened by the multiplicity of vibra- 
 tory effects, and by the enlargement of the magnetic effects, 
 which results from a better arrangement of the magnets. 
 
 " When the ear is placed at a," M. Trouve writes, " it per- 
 ceives immediately the sounds produced by the first plate, M, 
 and those of the second plate reach the ear through the inte- 
 rior of the magnet. This new arrangement is well adapted for 
 an experimental comparison of the results produced by a tele- 
 phone with a single membrane (a Bell telephone), and those 
 produced by a telephone with several membranes. It is, in 
 fact, enough to listen at the two faces of the telephone alter- 
 nately, in order to perceive at once the difference of intensity 
 in the sounds produced. Those collected at a, on the side of 
 the pierced iron plate, appear manifestly doubled in intensity 
 compared with those collected at b on the side of the simple 
 membrane which forms the ordinary telephone. 
 
 " The difference is still more striking if, in transmitting or 
 receiving a sound of invariable intensity through a multiple 
 telephone, the unbroken membrane M' is repeatedly prevented 
 from vibrating." 
 
 Before making this arrangement M. Trouve had planned an- 
 
DEMOGET'S SYSTEM. 101 
 
 other, which he presented to the Academic des Sciences, No- 
 vember 26th, 1877, and which we have glanced at in the be- 
 ginning of this chapter. He describes it in these terms : 
 
 " In order to increase the intensity of the effects produced 
 in the Bell telephone, I have substituted for the single mem- 
 brane a cubic chamber, of which each face is, with one excep- 
 tion, formed of a vibrating membrane. Each of these mem- 
 branes, put in vibration by the same sound, influences a fixed 
 magnet, which is also provided with an electric circuit. In 
 this way, by connecting all the currents generated by the mag- 
 nets, a single intensity is obtained, which increases in propor- 
 tion to the number of magnets influenced. The cube might 
 be replaced by a polyhedron, of which the faces might be 
 formed of an indefinite number of vibrating membranes, so 
 as to obtain the desired intensity. 
 
 M. DemoyeCs System. Several other systems of telephones 
 with multiple membranes have been proposed. One of them, 
 planned by M. Demoget, consists in placing before the vibra- 
 ting disk of the ordinary Bell telephone, separated by the 
 space of a millimetre, one or two similar vibrating disks, tak- 
 ing care to pierce in the centre of the first a circular hole of 
 the same diameter as that of the bar magnet, and to pierce a 
 larger hole in the second membrane. The inventor asserts 
 that the distinctness as well as the intensity of sounds is in- 
 creased in this way. 
 
 "By this arrangement," says M. Demoget, "since the vibra- 
 ting magnetic mass is larger in proportion to the magnet, the 
 electro-motive force of the currents generated is increased, and 
 consequently the vibrations of the disks of the second telephone 
 are more perceptible." 
 
 Mr. M' Tiff he's Telephone. In this telephone, which has sev- 
 eral diaphragms, there is a horseshoe magnet, and instead of 
 placing the coils upon the poles, there is a single coil fastened 
 to an iron core, which is inserted between wide polar appen- 
 
102 
 
 THE TELEPHONE. 
 
 dices fitted to the two poles of the magnet. These appendices 
 consist of thin plates, which act as vibrating plates. 
 
 Modifications in the Arrangement of Telephonic Organs. 
 We see that the forms given to the Bell telephone are very va- 
 ried, and this is still more the case with its constituent organs, 
 without, however, producing any remarkable improvements. 
 Mr. Preece observes that little has been gained by varying the 
 size and strength of the magnets, and the best effects have been 
 
 Fia. 37. 
 
 obtained by using the horseshoe magnets directed by Mr. Bell 
 himself. The telephone was certainly introduced into Europe 
 with the arrangement which is theoretically the best, although 
 Mr. Bell is still occupied in improving it. This is also tlio 
 opinion of M. Hellesen, who, like Mr. Preece, has made many 
 experiments on this point; but this has not deterred several 
 people from declaring that they have discovered the way of 
 making a telephone speak so as to be audible to an assembly 
 of people. 
 
EIGHI TELEPHONE. 
 
 103 
 
 Of the different instruments made with this object, that of 
 M. Righi seems to be the most important. It was lately tried 
 with success at the Academic dcs Sciences, the Conservatoire 
 des Arts et Metiers, and the Press pavilion of the Exhibition. 
 
 The receiver is only a Bell telephone of large size, with a 
 diaphragm of parchment, L L (Fig. 37), in the centre of which 
 there is a sheet-iron disk, F. This membrane is stretched on 
 a large funnel, E, which is fixed on a box, C C, containing the 
 electro -magnetic coil B; and the magnet N S, much larger 
 than in the ordinary instruments, issues from the box, and 
 serves as its support. 
 
 The sender resembles the one represented in Fig. 19, except 
 that, instead of liquid, M. Righi employs plumbago mixed with 
 powdered silver, and the platinum needle is replaced by a me- 
 tallic disk, D (Fig. 38). The receiver I, which contains the 
 powder, is supported on a spring, R, which can be pushed up 
 and down by a regulating screw, V, and the whole is fitted into 
 a box, C C, and supported on a foot, P. The speaker places 
 
 Fio. SS. 
 
 himself above the mouth-piece E, and the vibrations transmit- 
 ted to the membrane L L cause the variations of resistance in 
 I which are necessary for the transmission of speech, as in the 
 Edison svstem. Two Bunsen cells are enough to set the in- 
 
104 THE TELEPHONE. 
 
 strument at work, and it will make the sound of a trumpet or 
 flute audible throughout a room. Vocal music, which is less 
 intense, is necessarily transmitted to a rather less distance, and 
 words spoken in the natural voice are heard by those standing 
 about two yards and a half from the instrument. 
 
 The maximum distance at which the instrument has been 
 worked with the battery only is twenty-eight miles, the dis- 
 tance between Bologna and Ferrara ; and for greater distances 
 it is necessary to have recourse to induction coils. 
 
 In this case an induction coil is introduced into the circuit 
 at each station, and its primary wire is traversed by a current 
 from the local battery, and so also is the sender, which is else- 
 where connected with the receiver by a commutator. The sec- 
 ondary circuit of these coils is completed through the earth and 
 line wire. From this arrangement it follows that the induced 
 current which influences the receiver in correspondence only 
 produces its effect after a second induction, produced on the 
 primary wire of the local coil, and it appears that this is a suffi- 
 cient effect ; but the advantage of this arrangement is, that it 
 is possible to receive and transmit sounds without the aid of 
 anything but the commutator. 
 
 Among other arrangements which have been suggested, we 
 may mention one in which, instead of the bar magnet, a horse- 
 shoe magnet is used, with a vibrating plate placed between its 
 poles. For this purpose the poles are tipped with iron, and 
 one of them is pierced with a hole which corresponds to the 
 mouth-piece of the instrument. The two branches of the mag- 
 net are also furnished with magnetizing helices. When any- 
 thing is spoken before the hole, the vibrating plate causes in- 
 duced currents in the two helices : these currents would be of 
 opposite direction if the poles were of like nature, but, since 
 the magnetic poles are of contrary nature, they are in the same 
 direction. The vibrating plate then acts like the two plates of 
 M. Trouve's instrument, which we have described above. 
 
ARRANGEMENT. 105 
 
 In another arrangement, lately made by Ader, the receiver is 
 only an ordinary two-branched magnet, of which the armature 
 is supported, at about two millimetres from its poles, by a glass 
 plate to which it is glued, and the plate itself is fastened to 
 two rigid supports. In order to hear, it is only necessary to 
 apply the ear to the plate. The sender is a movable rod of 
 iron or carbon, which rests on a fixed piece of carbon, with no 
 pressure except its own weight, and it supports a concave disk, 
 to which the speaker applies his mouth. These two parts are 
 so arranged as to move horizontally, so that, when the instru- 
 ment is suspended, the circuit is forcibly disconnected by the 
 fact of its position, and is therefore closed until any one takes 
 it up to speak. Speech is well reproduced by this system, and 
 may be transmitted to some distance if it is made on a larger 
 scale. 
 
 Again, an anonymous inventor, in a little note inserted in 
 Les Mondes, February 7th, 1878, writes as follows: "Since the 
 intensity of the currents produced in the telephone is in pro- 
 portion to the mass of soft iron which vibrates before the pole 
 of the magnet, and since, on the other hand, the plate is sensi- 
 tive in proportion to its tenuity, I employ, instead of the or- 
 dinary plate, one reduced by nitric acid to the least possible 
 thickness, and I fix it to a circle of soft iron, which keeps it 
 stretched and forms part of the same substance. This circle 
 is placed in a circular opening made inside the compartment. 
 The intensity of a telephone is much increased when such a 
 system replaces the ordinary plate, even at one end of the line." 
 
 In order to obtain vibrating plates of extreme tenuity, M. E. 
 Duchemin thought of employing very thin plates of mica, 
 sprinkled with pulverized iron fixed to the plate by a layer of 
 silicate of potash. The inventor asserts that it is possible to 
 correspond in a low voice with the aid of this system ; but it 
 has this inconvenience, that the plate will be broken by speak- 
 ing too loud. 
 
 5* 
 
106 THE TELEPHONE. 
 
 Professor Jorgenson, of Copenhagen, has also made a Bell 
 telephone which produces very intense sounds, and which has 
 permitted him to observe some curious effects. In this instru- 
 ment the magnet is made in a mode analogous to Nickles's 
 tubular magnets. There is, first, a cylindrical magnet with a 
 core of soft iron at its upper end, to which the coil is fitted ; 
 next, a magnetized tube, formed of a steel ring, which encloses 
 the first magnetic system, and is connected with it by an iron 
 tube. Finally, above the polar extremities of this system, there 
 is the vibrating disk, with the same arrangement as that of or- 
 dinary telephones, and of which the superficies is large. If 
 this plate is only a millimetre in thickness, the words spoken 
 can be heard throughout a room ; but the sounds lose their 
 clearness when the ear is approached to the vibrating plate, the 
 words are confused, and there is the reverberation which is ob- 
 served on speaking in a place apt to produce echoes: the lis- 
 tener is, in fact, stunned by the sounds produced. On using a 
 thicker plate one, for example, of three or four millimetres 
 the telephone only produces the effect of the ordinary instru- 
 ments, and it is necessary to apply the ear to it. 
 
 M. Marin Maillet, of Lyons, has suggested that the sounds 
 reproduced by the telephone might be increased by reflecting 
 them through a certain number of reflectors, which, by concen- 
 trating them in a focus on a resonator, would considerably en- 
 large them. Since this idea was not accompanied by experi- 
 ments, it can hardly be regarded as serious. 
 
 TELEPHONIC EXPERIMENTS. 
 
 Since Mr. Bell's experiments, of which an account has been 
 given in the early part of this work, much study has been 
 given by men of science and inventors to the effects produced 
 in this curious instrument, so as to ascertain its theory and de- 
 duce improvements in its construction. We will take a glance 
 at these researches in succession. 
 

 
 I/. 
 
 TELEPHONIC EXPERIMENTS. */rV, 10 ^ 
 
 // 
 
 Experiments on the Effects produced by Voltaic and Indul 
 Currents. The comparative study of the effects produced in 
 the telephone by voltaic and induced currents was one of the 
 first and most important. In 1873, as we have seen, Mr. Eli- 
 sha Gray converted the voltaic currents, which he employed to 
 cause the vibrations of his transmitting plate, into induced cur- 
 rents by means of an induction coil, such as Ruhmkorff's. The 
 voltaic currents then traversed the primary helix of the coil, 
 and the induced currents reacted on the receiving instrument, 
 producing on its electro-magnetic system the vibrations excited 
 at the sending -station. When Mr. Edison designed his bat- 
 tery telephone, he had recourse to the same means to work his 
 receiving telephone, since he had, ascertained that induced cur- 
 rents were superior to voltaic currents. But this peculiarity 
 of Mr. Edison's arrangement was not clearly understood from 
 the descriptions which reached Europe, so that several persons 
 believed that they had invented this arrangement among oth- 
 ers, Colonel Navez and MM. Pollard and Gamier. 
 
 Colonel Navez, in an interesting paper on the new telephon- 
 ic system, presented to the Belgian Royal Academy February 
 2d, 1878, only suggests this arrangement as a mode of repro- 
 ducing speech at a great distance; but he quotes no experi- 
 ment which distinctly shows the advantages of this combina- 
 tion. Twenty days later, MM. Pollard and Gamier, unac- 
 quainted with Colonel Navez's researches, sent to me the re- 
 sults they had obtained by similar means, and these results 
 appeared to me so interesting that I communicated them to the 
 Academic des Sciences, February 25th, 1878. In order that 
 the importance of these results may be clearly understood, I 
 will repeat the text of M. Pollard's letter, addressed to me on 
 February 20th, 1878 : 
 
 " With the object of increasing the variations of electric in- 
 tensity in the Edison system, we induce a current in the cir- 
 cuit of a small Ruhmkorff coil, and we fix the receiving tele- 
 
108 THE TELEPHONE. 
 
 phone to the extremities of the induced wire. The current 
 received has the same intensity as that of the inducing current, 
 and consequently the variations produced in the current which 
 works the telephone have a much wider range. The intensity 
 of the transmitted sounds is strongly increased, and the value 
 of this increase depends upon the relative number of spirals in 
 the inducing and induced circuits. Our attempts to determine 
 the best proportions have been laborious, since it is necessary 
 to make a coil for each experiment ; we have hitherto obtain- 
 ed excellent results with a small Ruhmkorff coil reduced to its 
 simplest form, that is, without condenser or contact-breaker. 
 The inducing wire is No. 16, and is wound in five layers; the 
 induced wire is Xo. 32, and in twenty layers. The length of 
 the coil is seven centimetres, 
 
 "The following is the most remarkable and instructive ex- 
 periment: When setting the sender to work with a single 
 Daniell cell, there is no appreciable effect at the receiving-sta- 
 tion, at least in the telephone which I have made, when it is 
 in immediate connection with the circuit ; after inserting the 
 small induction coil, sounds become distinctly audible, and 
 their intensity equals that of good ordinary telephones. Since 
 the battery current is only moderately intense, the points of 
 plumbago are not worn down, and the regulating apparatus 
 lasts for a long while, AVhen a stronger battery is used, con- 
 sisting of six cells of bichromate of potash (in tension) or 
 twelve Leclanche cells, sufficient intensity is obtained by the 
 direct action to make sounds nearly as audible as in ordinary 
 telephones ; but when the induction coil is inserted, the sounds 
 become much more intense, and may be heard at a distance of 
 from fifty to sixty centimetres from the mouth-piece. Songs 
 may, under such circumstances, be heard at a distance of sev- 
 eral yards ; but the relative increase does not appear to be so 
 great as in the case of the single Daniell cell" 
 
 On the other hand, Les Mondes^ March 7th, 1878, contains 
 
LurrsrTs EXPEEIMESTTS. 109 
 
 -.:' -. =- '.:'. 
 
 ?::;--: : J ;.;.--.-.- 
 proved that the introdoction of 
 csrit which connect* the two 
 tensity of sonnd. Tbe maxsanm effect produced fey placing 
 one dose to the tiansmitfiug, and the ether dose to the remr- 
 
 use. The inducing wire of a Ruhmkorff coO, when introdnced 
 into such a circuit, excited no sensible effects of ind action in 
 
 phone in connection with this enemt at wott. Bnt the ear- 
 
 vou> ot a v-jJuJke macnme pvmtnees soands icsenuunf the IIPJBH 
 of a dram, which are deafening when the ear is appfied to the 
 
 of a metre. Ilie carrents of a Bahadborff nnehne are ftm 
 more c ncigetic, and the sonnd fib a whole room. I>T 
 :;-_- :-.: ? -<: -. : :\; ..-: : :-; - ;.. : ., 
 thron^i different tones, winch are always in unison with the 
 breaks of the emreut, at feast up to a certain pitch. 
 
 ::..: : : . '.irj : : ' -. - - v. : -1- ,: ;-. -" : - 
 the telephone he proposes to regulate in the ciren^ of an in- 
 
 - - ::,:- 
 
110 THE TELEPHONE. 
 
 phones in correspondence are intense in proportion to the de- 
 gree of unison in the vibrations produced by them, it is neces- 
 sary to select those which emit the same sounds for the same 
 given note ; and the mode we have just described may be em- 
 ployed with advantage, since it will be enough to observe what 
 instruments give the same note in the condition of maximum 
 sensibility, when regulated in the same way by the induction 
 machine. 
 
 It is very important that the telephones in correspondence 
 should be well matched, not only to insure clear transmissions, 
 but also with reference to the tone of voice of those who are 
 to use it. The sound becomes more audible when the tone of 
 voice corresponds to the telephonic tone ; and for this reason 
 some telephones repeat the voices of women and children bet- 
 ter than those of men, and with others the reverse takes place. 
 
 The telephonic vibrations vary in different instruments, and 
 these variations may be noted in the way we have indicated. 
 
 The advantages of induced currents in telephonic transmis- 
 sions may be easily understood, if we consider that the varia- 
 tions of resistance in the circuit, resulting from the greater or 
 less range in the vibrations of the transmitting plate, are of 
 constant value, and can only manifest their effects distinctly in 
 short circuits ; consequently the articulate sounds which result 
 from them can only be really appreciable in circuits of great 
 resistance. According to Mr. Warren de la Rue's experiments 
 (reported in the Telegraphic Journal, March 1st, 1878), tho 
 currents produced by the vibrations of the voice in an ordinary 
 telephone represent in intensity those of a Daniell cell travers- 
 ing 100 megohms of resistance (or 10,000,000 kilometres) ; 
 and it is plain that the simple question of greater or less inten- 
 sity in the currents acting on the receiving telephone is not 
 the only thing we have to consider. "With an energetic bat- 
 tery, it is evident, in fact, that the differential currents will al- 
 ways be more intense than the induced currents produced by 
 
INDUCED CURRENTS. Ill 
 
 the action of the instrument I myself am inclined to believe 
 that induced currents owe the advantages they possess to the 
 succession of inverse currents and their brief duration. These 
 currents, of which M. Blaserna considers that the duration does 
 not exceed -^ of a second, are much more susceptible than 
 voltaic currents of the multiplied vibrations which are charac- 
 teristic of phonetic vibrations, and especially since the succes- 
 sion of inverse currents which, take place discharge the line, 
 reverse the magnetic effects, and contribute to make the action 
 more distinct and rapid. We cannot, therefore, be surprised 
 that the induced currents of the induction coil, which can be 
 produced under excellent conditions at the sending -station, 
 since the circuit of the voltaic current is then very short, are 
 able to furnish results, not only more effective than the voltaic 
 currents from which they take their origin, but even than the 
 induced currents resulting from the action of the Bell tele- 
 phone, since they are infinitely more energetic. 
 
 As for the effects produced by the currents of Bell tele- 
 phones, which are relatively great when we consider their size, 
 they are easily explained from the fact that they are produced 
 under the influence of the vibrations of the telephone plate, 
 so that their variations of intensity always maintain the same 
 proportion, whatever may be the resistance of the circuit, and 
 consequently they are not effaced by the distance which divides 
 the two telephones. 
 
 Experiments on the Part taken by the Different Telephonic 
 Organs in the Transmission of Speech. In order to introduce 
 all the improvements of which a telephone is capable, it is im- 
 portant to be quite decided as to the effects produced in the 
 several parts of which it is composed, and as to the part taken 
 by the several organs which are at work. To attain this ob- 
 ject several men of science and engineers have undertaken a 
 series of experiments which have produced very interesting 
 results. 
 
112 THE TELEPHONE. 
 
 One of the points on -which it was most important to throw 
 light was that of ascertaining whether the vibrating plate used 
 in their telephone receivers by Messrs. Bell and Gray is the 
 only cause of the complex vibrations which reproduce speech, 
 or if the different parts of the electro-magnetic system of the 
 instrument all conduce to this effect. The experiments made 
 by Mr. Page in 1837 on the sounds produced by the resonant 
 electro-magnetic rods, and the researches pursued in 1846 by 
 Messrs, de la Rive, Wertheim, Matteucci, etc., on this curious 
 phenomenon, allow us to state the question, which is certainly 
 more complex than it at first appears. 
 
 In order to start from a fixed point, it must first be ascer- 
 tained whether a telephone can transmit speech without a vi- 
 brating plate. Experiments made by Mr. Edison 1 in Novem- 
 ber, 1877, with telephones provided with copper diaphragms, 
 which produced sounds, make the hypothesis credible; and 
 it received greater weight from the experiments made by Mr. 
 Preece and Mr. Blyth. The fact was placed beyond a doubt 
 by Mr. Spottiswoode (see the Telegraphic Journal of March 
 1st, 1878), who assures us that the vibrating plate of the tele- 
 phone may be entirely suppressed without preventing the 
 transmission of speech, provided that the polar extremity of 
 the magnet be placed quite close to the ear ; and it was after 
 this that I presented to the Academic des Sciences my paper 
 
 1 Mr. Edison, in a letter written November 25th, 1877, writes that he 
 has made two telephones which act with copper diaphragms, based on 
 Arago's effects of magnetism by rotation. He ascertained that a copper 
 diaphragm might replace the iron plate, if its thickness did not exceed one 
 thirty-second of an inch. The effect produced is slight when the copper 
 diaphragm is placed between two corresponding instruments ; but when 
 the sender only is furnished with the copper diaphragm, and the receiver 
 is arranged as usual, communication becomes easy. 
 
 Mr. Preece repeated these experiments, but he only obtained very slight 
 and indistinct effects : lie consequently believes that they are of no prac^ 
 tical use, although very interesting in theory. 
 
MILLAK TELEPHONE. 113 
 
 on tlie theory of the telephone, which led to an interesting dis- 
 cussion of which I shall speak presently. At first the authen- 
 ticity of these results was denied, and then an attempt was 
 made to explain the sounds heard by Mr. Spottiswoode as a me- 
 chanical transmission of the vibrations, effected after the man- 
 ner of string telephones ; but the numerous experiments which 
 have subsequently been made by Messrs. Warwick, Rossetti, 
 Hughes, Millar, Lloyd, Buchin, Canestrelli, Wiesendanger, Var- 
 ley, and many others, show that this is not the case, and that a 
 telephone without a diaphragm can transmit speech electrically. 
 
 Colonel ISTavez himself, who had first denied the fact, now 
 admits that a telephone without a diaphragm can emit sounds, 
 and even, under certain exceptional conditions, can reproduce 
 the human voice; but he still believes that it is impossible to 
 distinguish articulate words. 
 
 This uncertainty as to the results obtained by the different 
 physicists who have studied the matter shows that at any rate 
 the sounds thus reproduced are not clearly defined, and that in 
 physical phenomena, only appreciable to our senses, the appre- 
 ciation of an effect so undefined must depend on the perfection 
 of our organs. We shall presently see that this very slight 
 effect can be largely increased by the arrangement adopted by 
 Messrs. Bell and Gray, and we shall also see that, by a certain 
 mode of magnifying the vibrations, it has- been decisively 
 proved that a telephone without a diaphragm can readily re- 
 produce speech. I proceed to give the description of such a 
 telephone, which was shown by Mr. Millar at the meeting of 
 the British Association at Dublin in August, 1878. 
 
 This instrument consists of a small bar magnet, three inches 
 in length and five-sixteenths of an inch in width and thick- 
 ness, and a copper helix (No. 30) of about six metres in length 
 is wound round the bar. It is fixed in a box of rather thick 
 pasteboard, fitted above and below with two zinc plates, which 
 render it very portable. With a telephonic battery sender and 
 
114 THE TELEPHONE. 
 
 a single Leclanche cell, speech can be perfectly transmitted; the 
 whistling of an air, a song, and even the act of respiration be- 
 come audible. It seems also that the instrument can act with- 
 out a magnet, merely with a piece of iron surrounded by the 
 helix ; but the sounds are then much fainter. 
 
 Signer Ignace Canestrelli obtained the same results by mak- 
 ing one of the carbon telephonic senders react on a telephone 
 without a diaphragm, by means of an induction coil influenced 
 by two Bunsen cells. He writes as follows on the subject : 
 
 "With this arrangement I was able to hear the sound of any 
 musical instrument on a telephone without a diaphragm : sing- 
 ing, speaking, and whistling were perfectly audible. Whistling 
 could be heard, even when the telephone without a diaphragm 
 was placed at some distance from the ear. In some cases, de- 
 pending on the pitch of the voice, on the distance of the send- 
 ing-station, and on the joint pressure exerted by the carbons, I 
 could even distinguish words. 
 
 " I finally discharged the currents of the transmitter into the 
 coils of insulated copper wire with which the two poles of a 
 magnet were provided. This magnet was placed on a musical 
 box, made of very thin slips of wood, and on placing the ear at 
 the opening of the box I obtained the same results as with the 
 ordinary telephones without a diaphragm." 
 
 M. Buchin, after repeating experiments of the same kind as 
 the above, intimates that it is easy to hear the sounds produced 
 by a telephone without a diaphragm, by introducing into the 
 ear the end of an iron rod, of which the other end is applied 
 to the active pole of the bar magnet of the telephone. (Sec 
 Le Journal tfElectrkite, October 5th, 1878.) 
 
 I repeat finally the account of some experiments made by 
 Mr. Hughes and M. Paul Roy which are interesting from our 
 present point of view. 
 
 1. If an armature of soft iron is applied to the poles of an 
 electro-magnet, with its two branches firmly fixed on a board, 
 
HUGHES S EXPERIMENTS. 115 
 
 and if pieces of paper are inserted between this armature and 
 the magnetic poles, so as to obviate the effects of condensed 
 magnetism ; if, finally, this electro-magnet is connected with a 
 speaking microphone, of the form given in Fig. 39, it is possi- 
 ble to hear the words spoken in the microphone on the board 
 which supports the electro-magnet. 
 
 2. If two electro-magnets are placed in communication with 
 a microphone, with their poles of 'contrary signs opposite to 
 each other, and if their poles are separated by pieces of paper, 
 speech will be distinctly reproduced, without employing arma- 
 ture or diaphragm. These experiments are, however, delicate, 
 and demand a practised ear. 
 
 3. If, instead of causing the current produced by a micro- 
 phone to pass through the helix of a receiving telephone, it 
 is sent directly into the bar magnet of this telephone in the 
 direction of its axis that is, from one pole to another the 
 words pronounced in the microphone may be distinctly heard. 
 This experiment by M. Paul Roy indicates, if it is exact, that 
 the electric pulsations which traverse a magnet longitudinally 
 will modify its magnetic intensity. The experiment, however, 
 demands verification. 
 
 Another point was obscure. It was important to know 
 whether the diaphragm of a telephone really vibrates, or at 
 least if its vibrations could involve its displacement, such as 
 occurs in an electric vibrator, or in wind-instruments which 
 vibrate with a current of air. M. Autoine Breguet has made 
 some interesting experiments on the subject, which show that 
 such a movement cannot take place, since speech was repro- 
 duced with great distinctness from telephones with vibrating 
 plates of various degrees of thickness, and he carried the ex- 
 periment so far as to employ plates fifteen centimetres in thick- 
 ness. 1 When pieces of wood, caoutchouc, and other substances 
 
 1 Mr. Bell had previously made a like experiment, which suggested to 
 
116 THE TELEPHONE. 
 
 were laid upon these thick plates, the results were the same. 
 In this case it cannot be supposed that the plates were moved 
 to and fro. I have, moreover, ascertained, by placing a layer 
 of water or of mercury on these plates, and even on thin dia- 
 phragms, that no sensible movement took place, at least when 
 the induced currents produced by the action of speaking were 
 used as the electric source. No ripples could be seen on the 
 surface of the liquid, even when luminous reflectors were em- 
 ployed to detect them. And indeed it can hardly be admitted 
 that a current not more intense than that of a Daniell element, 
 which has traversed 10,000,000 kilometres of telegraphic wire 
 a current which can only show deviation on a Thomson gal- 
 vanometer should be powerful enough to make an iron plate 
 as tightly stretched as that of a telephone vibrate by attrac- 
 tion, even if we grant that the current was produced by laying 
 a finger on the diaphragm. 
 
 Very nice photographic experiments do, however, show that 
 vibrations are produced on the * diaphragm of the receiving 
 telephone ; they are, indeed, excessively slight, but Mr. Blake 
 asserts that they are enough to cause a very light index, rest- 
 ing on the diaphragm, to make slight inflections on a line 
 which it describes on a register. Yet this small vibration of 
 the diaphragm does not show that it is due to the effect of 
 attraction, for it may result from the act of magnetization itself 
 in the centre of the diaphragm. 1 An interesting experiment 
 
 him that molecular vibrations had as much to do with the action of the 
 telephone as mechanical vibrations. 
 
 1 M. Bosscha, who has published in the Archives Neerlandaises an inter- 
 esting paper on the intensity of electric currents in the telephone, says 
 that the minimum intensity of currents necessary to produce a sound in a 
 telephone by the vibration of its diaphragm may be less than -iVz/V of a 
 Daniell element, and the displacement of the centre of the diaphragm 
 would then be invisible. He was unable to measure exactly the range of 
 movements produced in the diaphragm by the influence of the voice, but 
 
ROY'S EXPERIMENTS. 117 
 
 by Mr. Hughes, repeated under different conditions by Mr. 
 Millar, confirms this opinion. 
 
 If the magnet of a receiving telephone consists of two 
 magnetized bars, perfectly equal, separated from each other by 
 a magnetic insulator, and they are so placed in the coil as to 
 bring alternately the poles of the same and of contrary signs 
 opposite to the diaphragm, it is known that the telephone will 
 reproduce speech better in the latter case than in the former. 
 Now, if the effects were due to attraction, this would not be 
 the case ; for the actions are in disagreement when the poles 
 of contrary signs are subjected to the same electric influence, 
 while they are in agreement when these poles are of like signs. 
 
 On the other hand, it is known that if several iron plates 
 are put together in order to form the diaphragm of the re^ 
 ceiver, the transmission of sounds is much stronger than with 
 a simple diaphragm ; and yet the attraction, if it has any- 
 thing to do with it, could only be exerted on one of the dia- 
 phragms. 
 
 It further appears that it is not merely the magnetic core 
 which emits sounds, but that they are also produced with some 
 distinctness by the helices. Signor Rossetti had already ascer- 
 tained this fact, and had even remarked that they could be 
 animated by a slight oscillatory movement along the bar 
 magnet, when they were not fixed upon it. Several observers, 
 among others M. Paul Roy, Herr Wiesendanger, and Signor 
 Canestrelli, have since mentioned similar facts, which are really 
 interesting. 
 
 " If," writes M. Paul Roy, " a coil of fine wire, which is at the 
 extremity of the bar magnet of a Bell telephone, receives the 
 
 he believes it to be less than the thousandth part of a millimetre ; and 
 from this it follows that, for a sound of 880 vibrations, the intensity of the 
 induced currents developed would be 0.0000v92 of the unit of electro- 
 magnetic intensity. 
 
118 THE TELEPHONE. 
 
 pulsatory currents transmitted by a carbon telephone, it is 
 only necessary to bring the coil close to the ear in order to 
 hear the sounds. 
 
 "The sounds received in this way are very faint, but be- 
 come much stronger if a piece of iron is introduced into the 
 circuit coil. A magnet acts with still greater force, even when 
 it consists of a simple magnetized needle. Finally, the sound 
 assumes its maximum intensity when an iron disk is inserted 
 between the ear and the coil. 
 
 " By placing the end of the coil to the ear, and sending a 
 current through it from the bar magnet, it is ascertained that 
 the sound is at its minimum when the neutral line of the 
 magnet is enclosed by the coil, and that it increases until at- 
 taining its maximum, when the magnet is moved until one of 
 its poles corresponds to the coil. 
 
 " This fact of the reproduction of sounds by a helix is uni- 
 versal. Every induction coil and every electro -magnet are 
 capable of reproducing sound when the currents of the sender 
 are of sufficient intensity." 
 
 Signor Canestrelli writes as follows : " With the combina- 
 tion of a carbon telephone and one without diaphragm or 
 magnet that is, with only a simple coil I was able to hear 
 whistling through the coil, placed close to the ear. This coil 
 was of very fine copper wire, and the currents were produced 
 through an induction coil by two Bunsen elements. The con- 
 tacts of the telephone were in carbon, and it was inserted in 
 the primary circuit. 
 
 " I fastened the coil to the middle of a tightly stretched 
 membrane which served as the base of a short metal cylinder. 
 When a magnet was placed near this part of the coil, the 
 sounds were intensified, and when I fixed the magnet in this 
 position, I could hear what was said. 
 
 " I afterward substituted for the magnet a second coil, fast- 
 ened to a wooden bar, and on causing the induced currents to 
 
LUVINIS EXPERIMENTS. 119 
 
 pass into both coils at once I was able to hear articulate 
 speech, although not without difficulty. 
 
 " Under these latter conditions I found it possible to con- 
 struct a telephone without a magnet, but it required a strong 
 current, and it was necessary to speak into the sender in a spe- 
 cial manner, so as to produce strong and concentrated sounds." 
 
 Another very interesting experiment by M. A. Breguet shows 
 that all the constituent parts of the telephone the handle, 
 the copper rims, and the case, as well as the diaphragm and the 
 electro-magnet can transmit sounds. M. Breguet ascertained 
 this fact by the use of string telephones, which he attached to 
 different parts of the telephone on which the experiment was 
 made. In this way he was not only able to establish a corre- 
 spondence between the person who worked the electric tele- 
 phone and the one who was listening through the string tele- 
 phone, but he also made several string telephones act, which 
 were attached to different parts of the electric telephone. 
 
 These two series of experiments show that sounds may be 
 obtained from different parts of the telephone without any 
 very appreciable vibratory movements. But Signor Luvini 
 wished for a further assurance of the fact, by ascertaining 
 whether the magnetization of any magnetic substance, followed 
 by its demagnetization, would involve a variation in the form 
 arid dimensions of this substance. He consequently caused a 
 large tubular electro-magnet to be made, which he filled with a 
 quantity of water, so that, when its two ends were corked, the 
 liquid should rise in a capillary tube fitted to one of the corks. 
 In this way the slightest variations in the capacity of the hol- 
 low part of the electro-magnet were revealed by the ascent or 
 descent of the liquid column. He next sent an electric current 
 of varying intensity through the electro-magnet, but he was 
 never able to detect any change in the level of the water in 
 the tube ; although by this arrangement he could measure a 
 change of volume of one-thirtieth of a cubic millimetre. It 
 
120 THE TELEPHONE. 
 
 appears from this experiment that the vibrations produced in a 
 magnetic substance under the influence of successive magnetiza- 
 tions and demagnetizations, are wholly molecular. Yet other 
 experiments made by M. Canestrelli seem to show that these 
 vibrations are so far sensible as to produce sounds which can 
 be detected by the microphone. He writes as follows on the 
 subject : 
 
 "When the broken currents of an induction coil are dis- 
 charged into a coil placed on a sounding -box, it is possible 
 to hear at a little distance the sounds produced by the induced 
 currents thus generated. On approaching the magnet to the 
 opening of the coil, these sounds are intensified, and the vibra- 
 tions of the magnet become sensible to the touch ; this vibra- 
 tion might even be made visible by suspending the magnet in- 
 serted into the coil to a metallic wire, which is fitted to a 
 membrane stretched on a drum, and the latter will then repro- 
 duce sounds. When the same magnet is suspended to a mi- 
 crophone, it is possible, with the aid of a telephone, to ascer- 
 tain the same effects, which are then increased." 
 
 We shall presently consider how these different deductions 
 are to be interpreted, so as to render the true theory of the 
 telephone intelligible; but, before doing so, we will mention 
 some other experiments which are not without interest. 
 
 We have seen that the experiments of Messrs. Edison, Blyth, 
 and Preece show that sounds may be reproduced by a tele- 
 phone with a diaphragm made of some unmagnetic substance, 
 and they also show, which is still more curious, that these 
 sounds may be transmitted under the influence of induced cur- 
 rents produced by these diaphragms when they are placed in 
 vibration before the magnet. Messrs. Edison and Blyth had 
 already adduced this fact, which was received with incredulity, 
 but it has been confirmed by Mr. Warwick in an article pub- 
 lished in the English Mechanic. He writes that in order to 
 act upon the magnet, so as to produce induced currents, some- 
 
EXPERIMENTS. 121 
 
 thing possessed of greater energy than gas must first be made 
 to vibrate. It is not, however, necessary that this substance 
 should be magnetic, for diamagnetic substances act perfectly. 1 
 
 1 Mr. Warwick describes his experiments as follows : " The magnets 
 employed were nearly of the usual size, one inch and a half in diameter, 
 and nearly eight times as long. At first I employed iron disks, but I found 
 them to be unnecessary. When I had discarded them, I tried several sub- 
 stances : first a thin disk of iron, which answered perfectly both for sender 
 and receiver. A disk of sheet-iron, about one-tenth of an inch in thick- 
 ness, did not act so well, but all that was said was quite understood. In 
 making experiments with the disks, I simply placed them above the instru- 
 ment, without fixing them in any way : the wooden cover and the conical 
 cavity were also laid aside, because the transmission and reception could 
 be effected as well without them. This .part of the instrument seems to 
 be superfluous, since, when the disk is simply placed level to the ear, the 
 sound seems to be increased by being brought nearer. Although iron acts 
 better than anything, it appears that iron disks are not absolutely neces- 
 sary, and that diamagnetic substances also act perfectly. I wished that 
 my assistant, who was at some distance, and could not hear any direct 
 sound, should continue his calculations. I took away the iron disk and 
 placed across the instrument a wide iron bar an inch thick. On applying 
 my ear to it, I could hear every sound distinctly, but somewhat more faint- 
 ly. A piece of copper, three inches square, was substituted for it : al- 
 though the sound was still distinct, it was fainter than before. Thick 
 pieces of lead, zinc, and steel were alternately tried. The steel acted in 
 almost the same way as the iron, and, as in the other cases, each word was 
 heard faintly but distinctly. Some of these metals are diamagnetic, and 
 yet the action took place. Some non-metallic substances were next tried ; 
 first a piece of window-glass, w^hich acted very well. The action was faint 
 with a piece of a wooden match-box ; but on using pieces of gradually in- 
 creasing thickness the sound was sensibly increased, and with a piece of 
 solid wood, one inch and a half in thickness, the sound was perfectly dis- 
 tinct. I next replaced it by an empty wooden box, which acted very well. 
 A piece of cork, half an inch thick, acted, but somewhat faintly. A block 
 of razor-stone, two inches thick, was placed upon the instrument, and, on 
 applying the ear to it, it was quite easy to follow the speaker. I then 
 tried to hear without the insertion of any substance, and, on applying my 
 ear quite close to the coil and magnet, I heard a faint sound, and on listen- 
 
 G 
 
122 THE TELEPHONE. 
 
 Mr. Preece sought for the cause in the induced currents devel- 
 oped in any conducting body when a magnet is moved before 
 it, currents which give rise to the phenomenon discovered by 
 Arago, and known by the name of magnetism by rotation. 
 Yet these facts do not appear to us to be sufficiently well es- 
 tablished to make the theory worthy of serious consideration, 
 and it is possible that the effects observed resulted from simple 
 mechanical transmissions. 
 
 To conclude the account of these experiments, we will add 
 that Mr. W. F. Barrett thinks it somewhat difficult to define 
 the mode of vibration of the diaphragm, since, while a certain 
 amount of compression exerted on the iron destroys the sounds 
 resulting from the peculiar effects of magnetization, a still 
 stronger compression causes them to reappear. It is certain 
 
 ing attentively I understood all that was said. In all these experiments 
 the sounds were perceived, but the sounds transmitted or attempted did 
 not act precisely alike. The sound of a tuning-fork, placed on the iron 
 disk itself or on the case of the instrument, was clearly heard : thin iron 
 disks were more effective for articulate speech. With other substances, 
 stone, solid wood, glass, zinc, etc., the sound of the tuning-fork was heard, 
 whether it rested upon them, or the vibrating fork was held above them. 
 These substances were not adapted for transmitting the sound of the 
 voice. These were all laid aside, and the sounding instrument was held 
 directly above the pole of the magnet : the sound was clearly heard, al- 
 though there was nothing but air between the end of the magnet and the 
 tuning-fork. The sound was perhaps less intense when the tuning-fork 
 was held directly above the pole than when it was at the end of the mag- 
 net. I next tried if my voice could be heard with this arrangement. The 
 result was rather doubtful, but I think that some action must have taken 
 place, for the tuning-fork was heard when it was simply vibrated near the 
 pole. The effect of the voice can only have differed in the degree of in- 
 tensity : it was too faint to be heard at the other extremity. I repeated 
 these effects ; I assured myself of them, and I succeeded in transmitting 
 sounds distinctly on the pole without a disk, and, on the other hand, by 
 applying my ear to the instrument, I was able to hear distinctly all that 
 was said, although there was no disk." 
 
DES PORTES'S EXPERIMENTS. 123 
 
 that the question is full of obscurity, and demands great re- 
 search : it is enough to have shown that the theory hitherto 
 held is insufficient. 
 
 On the other hand, Colonel Navez considers that the inten- 
 sity of sound reproduced in a telephone depends not only on 
 the range of vibrations, but also on the vibrating surface and 
 the effect it produces on the stratum of air which transmits 
 the sound. (See paper by Colonel Navez in the Bulletin de 
 VAcademie de Belyique, July 7th, 1878.) 
 
 Experiments on the Effects which result from Mechanical 
 Shocks communicated to different parts of a Telephone. If a 
 piece of iron is applied to the screw which holds the magnet 
 of the ordinary telephone, it is observed that the transmitted 
 sounds are more distinct, owing to the force supplied to the 
 active pole of the magnet ; but at the moment when the piece 
 of iron is applied to the screw a distinct noise is heard, which 
 seems to be due to the mechanical vibrations caused in the 
 magnet at the moment of the shock. M. des Fortes, a lieuten- 
 ant in the French navy, has lately made some interesting ex- 
 periments on this class of phenomena. He has observed that 
 if, in a telephonic circuit of ninety yards completed by the 
 earth, the sending telephone is reduced to a simple magnet, 
 provided with the coil which constitutes its electro-magnetic 
 organ, and if this magnet is suspended vertically by a silken 
 thread, with the coil above it, a blow struck upon the magnet, 
 either by a copper rod or a piece of wood, will cause distinct 
 sounds to be produced in the receiving telephone sounds 
 which will increase in intensity when the blow is struck close 
 to the coil, and which will become still stronger, but less clear, 
 if a vibrating plate of soft iron is placed in contact with the 
 upper pole of the magnet. 
 
 "When the striking instrument is made of iron, the sounds 
 in question are more strongly marked than if it is of wood; 
 and when the magnet has a vibrating disk applied to its active 
 
124 THE TELEPHONE. 
 
 pole, a vibration of the disk takes place at the moment when 
 the shock is heard. 
 
 If the striking body is a magnet, the sounds produced re- 
 semble those obtained when it is of iron, if the effect is pro- 
 duced between poles of the same nature ; but if the poles are 
 of contrary natures, a second noise is heard after each blow, 
 which is produced by drawing away the magnet, and which ap- 
 pears to be a blow struck with much less force. The sound is of 
 course increased if the magnet is provided with its vibrating disk. 
 
 If words are uttered on the vibrating disk of the sending 
 telephone, when it is applied to the pole of the magnet, various 
 sounds are heard on the receiving telephone, somewhat similar 
 to those produced by vibrating one of the strings of a violin, 
 and the sound made in withdrawing the disk from contact with 
 the magnet is distinctly heard in the receiver. 
 
 The person who applies his ear to the vibrating disk of the 
 sender when it is arranged as above, may hear the voice of 
 any one who speaks into the receiver, but cannot distinguish 
 the words, owing, no doubt, to the condensed magnetism at the 
 point of contact between the magnet and the vibrating disk, 
 which slackens the magnetic variations, and makes it more 
 difficult for them to take place. 
 
 A coil is not necessary in order to perceive the blows struck 
 upon the magnet with a rod of soft iron. It is enough to wind 
 three turns of naked conducting wire, which acts as line wire, 
 round one end of the magnet, and the sounds perceived cease, 
 as in other experiments, when the circuit is broken, plainly 
 showing that they are not due to mechanical transmission. It 
 is a still more curious fact that if the magnet is placed in the 
 circuit, so as to form an integral part of it, and if the two ends 
 of the conducting wire are wound round the ends of the mag- 
 net, the blows struck upon the latter with the soft iron rod are 
 perceived in. the telephone as soon as one pole of the magnet 
 is provided with a vibrating disk. 
 
THOMPSON'S EXPERIMENTS. 125 
 
 I have myself repeated M. des Portes's experiments by sim- 
 ply striking on the screw which, in ordinary telephones, fastens 
 the magnet to the instrument, and I have ascertained that, 
 whenever the circuit was complete, the blows struck with an 
 ivory knife were repeated by the telephone : they were, it is 
 true, very faint when the vibrating disk was removed, but very 
 marked when the disk was in its place. On the other hand, 
 no sound was perceived when the circuit was broken. These 
 sounds were louder when the blows were struck upon the screw 
 than when they were struck on the pole of the magnet itself 
 above the coil : for this reason, that in the first case the mag- 
 net could vibrate freely, while in the second the vibrations were 
 stifled by the fixed position of tha bar magnet. 
 
 These effects may be to some extent explained by saying 
 that the vibrations caused in the magnet by the shock pro- 
 duce undulatory displacements of the magnetized particles in 
 the whole length of the bar, and that induced currents would, 
 according to Lenz's law, result in the helix from these displace- 
 ments currents of which the force would increase when the 
 power of the magnet was further excited by the reaction of 
 the diaphragm, which acts as an armature, and also by that 
 of the striking instrument when it also is magnetic. Yet it is 
 more difficult to explain M. des Portes's later experiments, and 
 the effect may be produced by something more than the or- 
 dinary induced currents. 
 
 These are not the only experiments which show the effects 
 produced under the influence of molecular disturbance of vari- 
 ous kinds. Mr. Thompson, of Bristol, has observed that if a 
 piece of iron and a tin rod placed perpendicularly on the iron 
 are introduced into the circuit of an ordinary telephone, it is 
 enough to strike the tin rod in order to produce a loud sound 
 in the telephone. He has also shown that if the two ends of 
 a bar magnet arc enclosed by two induction coils which are 
 placed in connection with the circuit of a telephone, and if the 
 
126 THE TELEPHONE. 
 
 flame of a spirit-lamp is moved below the magnet in the space 
 dividing the two coils, a distinct sound is heard as soon as the 
 flame exerts its influence on the bar magnet. This effect is 
 undoubtedly due to the weakening of the magnetic force of 
 the bar which is produced by the action of heat. I have my- 
 self observed that a scratching sound on one of the wires which 
 connect the telephones is heard in both of them, at whatever 
 point in the circuit the scratch is made. The sounds produced 
 are indeed very faint, but they can be distinctly heard, and 
 they become more intense when the scratch is made on the 
 binding-screws of the telephone wires. These sounds cannot 
 result from the mechanical transmission of vibrations, since 
 they are imperceptible when the circuit is broken. From these 
 experiments it appears that some sounds which have been ob- 
 served in telephones tried on telegraph stations may arise from 
 the friction of the wires on their supports a friction which 
 produces those very intense sounds which are sometimes heard 
 on telegraphic wires. 
 
 Theory of the Telephone. It appears from the several ex- 
 periments of which we have spoken that the explanation gen- 
 erally given of the effects produced in the telephone is very 
 imperfect, and that the transmission of speech, instead of re- 
 sulting from the- repetition by the. membrane of the receiv- 
 ing telephone (influenced by electro-magnetism) of vibrations 
 caused by the voice on the membrane of the transmitting 
 membrane, is due to molecular vibrations produced in the 
 whole electro-magnetic system, and especially on the magnetic 
 core contained in the helix. These vibrations must be of the 
 same nature as those which have been observed in resonant 
 electro-magnetic rods by MM. Page, de la Rivc,Wertheim, Mat- 
 tcucci, etc., and these have been employed in telephones by 
 Reiss, by Cecil and Leonard Wray, and by Vanderwcyde. 
 
 According to this hypothesis, the principal office of the vi- 
 brating plate consists in its reaction, in order to produce the 
 
DE LA KITE'S OPINION. 127 
 
 induced currents when the voice has placed it in vibration, and 
 by this reaction on the polar extremity of the bar magnet it 
 strengthens the magnetic effects caused in the centre of the 
 bar when it vibrates under the electro-magnetic influence, or at 
 least when it is affected by the magnet. Since the range of 
 these vibrations for a single note is great in proportion to the 
 flexibility of the note, and since, on the other hand, the varia- 
 tions in the magnetic condition of the plate are rapid in pro- 
 portion to the smallness of its mass, the advantage of employ- 
 ing, as Mr. Edison has done, very thin and relatively small 
 plates is readily understood. In the case of transmission, the 
 wider range of vibration increases the intensity of the induced 
 currents transmitted. In the case of reception the variations 
 in the magnetizing force which produces the sounds are ren- 
 dered clearer and more distinct, both in the armature mem- 
 brane and in the bar magnet : something is gained, therefore, 
 in each case. This hypothesis by no means excludes the pho- 
 netic effects of the mechanical and physical vibrations which 
 may be produced in the armature plate under the influence of 
 magnetization and demagnetization to which it is subjected, 
 and these join their influence to that of the magnetic core. 
 
 What is the nature of the vibrations sent into the receiving 
 telephone ? This question is still obscure, and those who have 
 studied it are far from being in agreement : as early as 1846 it 
 was the subject of an interesting discussion between MM.Wert- 
 lieim and de la Rive, and the new discoveries render it still 
 more complex. M. Wertheim considers that these vibrations 
 are at once longitudinal and transverse, and arise from attrac- 
 tions exchanged between the spirals of the magnetizing helix 
 and the magnetic particles of the core. M. de la Rive holds 
 that in the case we are considering the vibrations are simply 
 longitudinal, and result from molecular contractions and ex- 
 pansions produced by the different combinations assumed by 
 the magnetic molecules under the influence of magnetization 
 
128 THE TELEPHONE. 
 
 and demagnetization. This appears to us to be the most nat- 
 ural explanation, and it seems to be confirmed by the experi- 
 ment made by M. Guillemin in 1846. M. Guillemin ascertained 
 that if a flexible iron rod, surrounded by a magnetizing helix, 
 is kept in position by a vise at one end, arid bent back by a 
 weight at the other, it can be made to return instantly to its 
 normal position by sending a current through the magnetizing 
 helix. This recovery can in such a case be due to nothing but 
 the contraction caused by the magnetic molecules, which, under 
 the influence of their magnetization, tend to produce intermo- 
 lecular attractions, and to modify the elastic conditions of the 
 metal. It is known that when iron is thus magnetized it be- 
 comes as hard as steel, and a file makes no impression on its 
 surface. 
 
 It is, at any rate, impossible to dispute that sounds are pro- 
 duced in the magnetic core, as well as in the armature, under 
 the influence of intermittent electric action. These sounds 
 may be musical or articulate; for as soon as the sender has 
 produced the electric action required, there is no reason why 
 vibrations which are effected in a transverse or longitudinal 
 direction should transmit the one more than the other. These 
 vibrations may, as we have seen, be termed microscopic. 
 
 Signor Luvini, who shares our opinion of the foregoing the- 
 ory, does not, however, think it wholly satisfactory, unless ac- 
 count is taken of the reaction caused by the bar magnet on 
 the helix which surrounds it. " There cannot," he says, " be 
 action without reaction, and consequently the molecular action 
 produced in the magnet ought to cause corresponding varia- 
 tions in the helix, and these two effects ought to contribute to 
 the production of sounds." He supports this remark by a ref- 
 erence to Professor Rossetti's experiment, of which we have 
 spoken above.- 
 
 We believe, however, that this double reaction of which 
 Signor Luvini speaks is not indispensable, for we have seen 
 
A 
 
 ACTION OF DlAPimAGSfc-'j / 
 
 that insulated helices can produce sounds; it is true itf 
 spirals, reacting on each other, may be the cause of this. ' 
 
 The difficulty of explaining the production of sounds in an 
 electro-magnetic organ destitute of armature caused the authen- 
 ticity of the experiments we have described to be at first de- 
 nied, and Colonel Navez started a controversy with us which is 
 not likely to be soon terminated ; yet one result of this con- 
 troversy is that Colonel Navez was obliged to admit that the 
 sound of the human voice may be reproduced by a telephonic re- 
 ceiver without a disk. But he still believes that this reproduc- 
 tion is so faint that it is not possible to recognize articulate 
 words, and he maintains that the transverse vibrations of the 
 disk, which are due to effects o attraction, are the only ones 
 to reproduce articulate speech with such intensity as to be of 
 any use. 
 
 It is certain that the articulation of speech requires a some- 
 what intense vibration which cannot easily be produced in a 
 telephone without a diaphragm ; for it must be remembered 
 that in an instrument so arranged, the magnetic effects are 
 reduced in a considerable ratio, which is that of the magnetic 
 force developed in the magnet, multiplied by itself, and that 
 so faint an action as that effected in a telephone becomes al- 
 most null when, in consequence of the suppression of the arma- 
 ture, it is only represented by the square root of the force 
 which produced it. It is therefore possible that the sounds 
 which are hardly perceptible in a telephone without a dia- 
 phragm become audible when the cause which provokes them 
 is multiplied by itself, and when there are in addition the 
 vibrations produced in the heart of the armature itself, in- 
 fluenced by the magnetizations and demagnetizations to which 
 it is subjected. 
 
 In order to show that the action of the diaphragm is less 
 indispensable than Colonel Navez seems to imagine, and that 
 its vibrations are not due to electro -magnetic attractions, it 
 
 6* 
 
130 THE TELEPHONE. 
 
 will be enough to refer to Mr. Hughes's experiments, which 
 we have mentioned above. It is certain that if this were the 
 effect produced, we should hear better when the two bar 
 magnets present their poles of the same nature before the dia- 
 phragm, than when they present the poles of contrary natures, 
 since the whole action would then converge in the same direc- 
 tion. Again, the more marked effects obtained with multiple 
 diaphragms in juxtaposition completely exclude this hypothe- 
 sis. It is, however, possible that in electro-magnetic telephones 
 the iron diaphragm, in virtue of the rapid variations of its mag- 
 netic condition, may contribute to render the sounds clearer and 
 more distinct; it may react in the way the tongue does; but 
 we believe that the greater or less distinctness of the articulate 
 sounds must be chiefly due to the range of vibrations. Thus 
 Mr. Hughes has shown that the carbons of metallized wood 
 employed in his microphonic speakers were to be preferred to 
 retort carbons for the transmission of speech, for the very rea- 
 son that they had less conductivity, so that the differences of 
 resistance which result from differences of pressure are more 
 marked, and consequently it is easier to seize the different 
 degrees of vocal sounds which constitute articulate speech. 
 
 It must be clearly understood that what we have just said 
 only applies to the Bell telephone, that is, to a telephone in 
 which the electric currents have such a faint intensity that it 
 cannot be supposed there is any external attractive effect. 
 When these currents are so energetic as to produce such an 
 effect, a transverse electro -magnetic vibration certainly takes 
 place, which is added to the molecular vibration, and helps to 
 increase the sounds produced. But it is no less true that 
 this transverse vibration by attraction or by movement of the 
 diaphragm is not necessary for the reproduction of sounds, 
 whether musical or articulate. 
 
 We are not now concerned with the discussion of magnetic 
 effects; there has been an advance in science since Colonel 
 
EFFECTS OF REACTION. 131 
 
 Xavez started the controversy, and we must ask how his theory 
 of the movements of the telephone diaphragm by attraction 
 will explain the reproduction of speech by a receiving micro- 
 phone destitute of any electro-magnetic organ, and I can assert 
 that my experiments show that there can be no mechanical 
 transmission of vibrations, since no sound is heard when the 
 circuit is broken or deprived of its battery. Colonel Navez 
 must therefore accept the molecular vibrations. This certainly 
 gives us a new field for study ; but it is because European 
 men of science persist in remaining bound by incomplete theo- 
 ries that we have allowed the Americans who despise them to 
 reap the glory of the great discoveries by which we have lately 
 been astonished. 
 
 The experiments quoted above show that sounds may be 
 reproduced not only by simple helices without an electro- 
 magnetic organ, but also by the plates of a condenser, in spite 
 of the pressure exerted upon them ; and when we add to this 
 the effects I have just pointed out, it may be supposed that 
 vibrations of sound must result from every reaction between 
 two bodies which has the effect of producing abruptly and at 
 close intervals modifications in the condition of their electric 
 or magnetic equilibrium. It is known that the presence of 
 ponderable matter is necessary for the production of electric 
 effects, and it is possible that the molecular vibrations of which 
 I have spoken may be the result of molecular movements, due 
 to the variations of the electric force which holds the mole- 
 cules in a special condition of reciprocal equilibrium. 
 
 In conclusion, the theory of the telephone and microphone, 
 considered as reproductive organs of speech, is still far from 
 being perfectly clear, and it would be imprudent to be too 
 positive on questions of such recent origin. 
 
 The theory of the electric transmission of sounds in electro- 
 magnetic telephones is somewhat complex. It has been seen 
 that they can be obtained from diaphragms of non-magnetic 
 
132 THE TELEPHONE. 
 
 substance, and even from simple mechanical vibrations produced 
 by shocks. Are \ve to ascribe them in the first case to the 
 inductive reaction of the magnet on the vibrating plate, and in 
 the second case to the movements of magnetic particles before 
 the spirals of the helix ? The matter is still very obscure ; yet 
 it is conceivable that the modifications of the inducing action 
 of the magnet on the vibrating diaphragm may involve varia- 
 tions in the magnetic intensity, just as we can admit an effect 
 of the same kind due to the approach and withdrawal of the 
 magnetic particles of the spirals of the helix ; M. Treve, how- 
 ever, believes that there is in the latter case a special action, 
 which he has already had occasion to study under other cir- 
 cumstances, and he sees in the current thus caused the effect 
 of the transformation of the mechanical labor produced amidst 
 the magnetic molecules. The question is complicated by the 
 fact that these effects are often produced by purely mechanical 
 transmissions. 
 
 There is another point to consider, on which Colonel Navcz 
 has made some interesting remarks; that is, whether the effects 
 in the receiver are stronger with permanent than with tempo- 
 rary magnets. In the first model of the telephone, exhibited 
 by Mr. Bell at Philadelphia, the receiver was, as I have said, 
 made of a tubular electro-magnet, furnished with a vibrating 
 disk at its cylindrical pole ; but this arrangement was aban- 
 doned by Mr. Bell, with the object, as he states in his paper, of 
 rendering his instrument both a receiver and a sender. 1 Yet 
 Colonel Navez maintains that the magnet plays an important 
 part, and is even indispensable under the present conditions 
 of its form. " It is possible," he says, " under certain circum- 
 
 1 These are his own words : " The articulation produced from the instru- 
 ment was remarkably clear, but its great defect consisted in the fact that 
 it could not be used as a sending instrument, and thus two telephones were 
 required at each station, one for transmitting and one for receiving spoken 
 messages." 
 
ACTION OF CURRENTS. 133 
 
 stances, and by making the instrument in a special way, to 
 make a Bell receiver speak without a permanent magnet, yet 
 with an instrument of the usual construction the sound ceases 
 when the magnet is withdrawn and replaced by a cylinder of 
 soft iron. In order to restore the voice of the telephone, it is 
 enough to approach the pole of a permanent magnet to the 
 cylinder of soft iron. It follows from these experiments that 
 a Bell telephone cannot act properly unless the disk is subject- 
 ed to an initial magnetic tension obtained by means of a per- 
 manent magnet. It is easy to deduce this assertion from a 
 consideration of the theory." 
 
 The assertion may be true in the case of Bell telephones, 
 which are worked by extremely weak currents, but when these 
 currents are relatively strong, all electro-magnets will reproduce 
 speech perfectly, and we have seen that M. Ader made a tele- 
 phone with the ordinary electro-magnet which acted perfectly. 
 
 The action of the currents sent through the helix of a tele- 
 phone can be easily explained. "Whatever may be the magnet- 
 ic conditions of the bar, the induced currents of different in- 
 tensity which act upon it produce modifications in its magnetic 
 state, and hence the molecular vibrations follow from contrac- 
 tion and expansion. These vibrations are likewise produced in 
 the armature under the influence of the magnetizations and de- 
 magnetizations which are produced by the magnetic action of 
 the core, and they contribute to the vibrations of the core it- 
 self, while at the same time the modifications in the magnetic 
 condition of the system are increased by the reaction of the 
 two magnetic parts upon each other. 
 
 When the bar is made of soft iron, the induced currents act 
 by creating magnetizations of greater or less energy, followed by 
 demagnetizations which are the more prompt since inverse cur- 
 rents always succeed to those which have been active, and this 
 causes the alternations of magnetization and demagnetization 
 to be more distinct and rapid. When the bar is magnetized, 
 
134 THE TELEPHONE. 
 
 the action is differential, and may be exerted in either direc- 
 tion, according as the induced currents corresponding to the vi- 
 brations which are effected pass through the receiving coil in 
 the same or opposite direction as the magnetic current of the 
 bar. If these currents are in the same direction, the action is 
 strengthening, and the modifications are effected as if a mag- 
 netization had taken place. If these currents are of opposite 
 direction, the inverse effect is produced ; but, whatever the ef- 
 fects may be, the molecular vibrations maintain the same re- 
 ciprocal relations and the same height in the scale of musical 
 sounds. If the question is considered from the mathematical 
 point of view, we find the presence of a constant, correspond- 
 ing with the intensity of the current, which does not exist in 
 mechanical vibrations, and which may possibly be the cause of 
 the peculiar tone- of speech reproduced by the telephone, a tone 
 which has been compared to the voice of Punch. M. Dubois 
 Kaymond has published an interesting paper on this theory, 
 which appeared in Les Mondes, February 21st, 1878, but we do 
 not reproduce it here, since his remarks are too scientific for 
 the readers for whom this work is intended. We will only 
 add that Mr. C. W. Cunningham asserts that the vibrations 
 produced in a telephone cannot be manifested under precisely 
 the same conditions as those which affect the tympanum of 
 the ear, because the latter has a peculiar funnel-shaped form, 
 which excludes every fundamental note, specially adapted to 
 it, and this is not the case with the bars and magnetic plates 
 which possess fundamental notes capable of greatly altering 
 the half-tones of the voice. He considers the alteration of the 
 voice observed in the telephone must be ascribed to these fun- 
 damental notes. 
 
 M. Wiesendanger 's Thermophone. M. Wiesendanger, in an 
 article inserted in the English Mechanic and World of Science, 
 September 13th, 1878, ascribes the reproduction of speech in 
 certain telephones to vibratory movements resulting from mo- 
 
135 
 
 lecular expansions and contractions produced by variations of 
 temperature, and these variations would follow from the cur- 
 rents of varying intensity which are transmitted through the 
 telephonic circuits. He was conscious of one objection to this 
 theory, namely, that the movements of expansion and contrac- 
 tion due to heat are slowly produced, and consequently are not 
 capable of substantial action, rapid enough to produce vibra- 
 tions ; but he considers that molecular effects need not take 
 place under the same conditions as those which are displayed 
 in the case of material substances. 
 
 M. Wiesendanger believes that this hypothesis will explain 
 the reproduction of speech in the receiving microphones of. 
 Mr. Hughes, and that it may even be applied to the theory of 
 the electro-magnetic telephone, if we consider that a magnetiz- 
 ing helix, as well as a magnetic core, round which an electric 
 current circulates, is more or less heated, according to the in- 
 tensity of the current which traverses it, especially when the 
 wire of the helix and the core are bad conductors of electricity 
 and of magnetism. Pursuing this idea, M. Wiesendanger has 
 sought to construct telephones in which calorific effects are 
 more fully developed, and with this object he used very fine 
 wire of German silver and platinum to make the coils. He 
 ascertained that these coils could produce sounds themselves, 
 and, to increase their intensity, he put them between disks of 
 iron, or on tin tubes, placed on resonant surfaces close to the 
 disks. In this way he says that he was able to make a good 
 receiving telephone without employing magnets. He after- 
 ward arranged the instrument in different ways, of which the 
 following two are the most noteworthy : 
 
 In the first, the electro-magnetic system was simply formed 
 by a magnetic disk with a helix wound round it, of which the 
 wire was in connection with the circuit of a microphone, and 
 which was fastened to the centre of the parchment membrane 
 of an ordinary string telephone ; the disk consisted of two 
 
136 THE TELEPHONE. 
 
 iron plates separated by a carbon disk of smaller diameter, and 
 the whole was so compressed as to form a solid mass. 
 
 In the second, the helix was wound on a tin tube, six inches 
 long and five-eighths of an inch in diameter, which was solder- 
 ed by merely a point to the centre of the diaphragm of an or- 
 dinary telephone. 
 
 The inventor asserts that the tube and diaphragm only act 
 as resonators, and that the sounds produced by this instrument 
 are nearly the same as those obtained from the ordinary string 
 telephone : the tunes of a musical box were heard, and the re- 
 production of speech was perfect, both in intensity and in dis- 
 tinctness of sound ; it even appeared that telephonic sounds 
 were audible with the tin tube alone, surrounded by the he- 
 lix. M.Wiesendanger says that " these different receiving tele- 
 phones show clearly that the diaphragm and magnet are not 
 essential, but merely accessory, parts of a telephone." 
 
 VARIOUS EXPERIMENTS MADE WITH THE TELEPHONE. 
 
 We must now consider a series of experiments which dem- 
 onstrate the wonderful properties of the telephone, and which 
 may also give some indication of the importance of the influ- 
 ences by which it is liable to be affected. 
 
 Experiments by M. d 1 Arsonval. We have seen that the tel- 
 ephone is an extremely sensitive instrument, but its sensitive- 
 ness could scarcely be appreciated by ordinary means. In or- 
 der to gauge it, M. d'Arsonval has compared it to the nerve of 
 a frog, which has hitherto been regarded as the most perfect 
 of all galvanoscopes, and it appears from his experiments that 
 the sensitiveness of the telephone is two hundred times greater 
 than that of the frog's nerve. M. d'Arsonval has given the 
 following account of his researches in the records of the Aca- 
 demic des Sciences, April 1st, 1878 : 
 
 " I prepared a frog in Galvani's manner. I took Siemens's 
 instrument of induction, used in physiology under the name of 
 
D'ABSONVAL'S EXPE RIME NTS. 137 
 
 the chariot instrument. I excited with the ordinary pincers 
 the sciatic nerve, and I withdrew the induced coil until the 
 nerve no longer responded to the electric excitement. I then 
 substituted the telephone for the nerve, and the induced cur- 
 rent, which had ceased to excite the latter, made the instru- 
 ment vibrate strongly. I withdrew the induced coil, and the 
 telephone continued to vibrate. 
 
 " In the stillness of night I could hear the vibration of the 
 telephone when the induced coil was at a distance fifteen times 
 greater than the minimum at which the excitement of the 
 nerve took place ; consequently, if the same law of inverse 
 squares applies to induction and to distance, it is evident that 
 the sensitiveness of the telephone is two hundred times greater 
 than that of the nerve. 
 
 "The sensitiveness of the telephone is indeed exquisite. 
 We see how much it exceeds that of the galvanoscopic frog's 
 leg, and I have thought of employing it as a galvanoscope. 
 It is very difficult to study the muscular and nervous currents 
 with a galvanometer of 30,000 turns, because the instrument is 
 deficient in instantaneous action, and the needle, on account of 
 its inertia, cannot display the rapid succession of electric varia- 
 tions, such as are effected, for example, in a muscle thrown into 
 electric convulsion. The telephone is free from this incon- 
 venience, and it responds by vibration to each electric change, 
 however rapid it may be. The instrument is, therefore, well 
 adapted for the study of electric tetanus in the muscle. It is 
 certain that the muscular current will excite the telephone, 
 since this current excites the nerve, which is less sensitive than 
 the telephone. But for this purpose some special arrange- 
 ment of the instrument is required. 
 
 " It is true that the telephone can only reveal the variations 
 of an electric current, however faint they may be ; but I have 
 been able, by the use of a very simple expedient, to reveal by 
 its means the presence of a continuous current, also of extreme 
 
138 THE TELEPHONE. 
 
 faintncss. I send the current in question into the telephone, 
 and, to obtain its variations, I break this current mechanically 
 with a tuning-fork. If no current is traversing the telephone, 
 it remains silent. If, on the other hand, the faintest current 
 exists, the telephone vibrates in unison with the tuning-fork." 
 
 Professor Eick, of Wurzburg, has also used the telephone for 
 physiological researches, but in a direction precisely opposite to 
 that explored by M. d'Arsonval. He ascertained that when the 
 nerves of a frog were placed in connection with a telephone, 
 they were forcibly contracted when any one was speaking into 
 the instrument, and the force of the contractions chiefly de- 
 pended on the words pronounced. For instance, the vowels a, 
 e, i produced hardly any effect, while o, and especially u, caused 
 a very strong contraction. The words Liege still, pronounced 
 in a loud voice, only produced a faint movement, while the 
 word Tucker, even when spoken in a low voice, strongly agi- 
 tated the frog. These experiments, reminding us of those by 
 Galvani, were necessarily based on the effects produced by the 
 induced currents developed in the telephone, and they show 
 that if this instrument is a more sensitive galvanoscope than 
 the nerve of a frog, the latter is more susceptible than the most 
 perfect galvanometer. 
 
 Experiments by M. Demoget. In order that he might com- 
 pare the intensity of the sounds transmitted by the telephone 
 with the intensity of original sounds, M. Demoget placed two 
 telephones in an open space. He held the first to his ear, 
 while his assistant withdrew to a distance, constantly repeating 
 the same syllable with the same intensity of tone in the sec- 
 ond instrument. He first heard the sound transmitted by the 
 telephone, and then the sound which reached him directly, so 
 that comparison was easy, and he obtained the following results : 
 
 At a distance of ninety -three yards the original and the 
 transmitted sounds were received with equal intensity, while 
 the vibrating disk was about five centimetres from the ear. 
 
DEMOGET'S EXPERIMENTS. 139 
 
 At this moment, therefore, the relative intensity was as 25 to 
 81,000,000. In other words, the sound transmitted by the 
 telephone was only auuuuou f ^ e emitted sound. "But," 
 said M. Demoget, " since the stations at which we worked could 
 not be regarded as two points freely vibrating in space, the 
 ratio may be reduced by one-half on account of the influence 
 of the earth, and the sound transmitted by the telephone may 
 be supposed to be 1,500,000 times weaker than that emitted 
 by the voice. 
 
 " Again, since we know that the intensity of the two sounds 
 is in proportion to the square of the range of vibrations, it 
 may be concluded that the vibrations of the two telephone 
 disks were in direct proportion to the distance, that is, as 5 to 
 9000, or that the vibrations of the sending telephone were 
 eighteen hundred times greater than those of the receiving tel- 
 ephone. These latter may, therefore, be compared to molecu- 
 lar vibrations, since the range of those of the sending telephone 
 was extremely small. 
 
 " Without in any degree detracting from the merit of Bell's 
 remarkable invention," continues M. Demoget, " it follows, from 
 what I have said above, that the telephone, considered as a 
 sending instrument, leaves much to be desired, since it only 
 transmits the -$*$ part of the original power ; and if it has 
 produced such unexpected results, this is due to the perfection 
 of the organ of hearing, rather than to the perfection of the 
 instrument itself." 
 
 M. Demoget considers this loss of power which takes place 
 in the telephone to be chiefly owing to the eight transforma- 
 tions in succession to which sound is subjected before reaching 
 the ear, setting aside the loss due to the electric resistance of 
 the line, which might in itself suffice to absorb the whole force. 
 
 In order to estimate the force of the induced currents which 
 act upon a telephone, M. Demoget has attempted to compare 
 them with currents of which the intensity is known, and which 
 
140 THE TELEPHONE. 
 
 produce vibrations of like nature and force : for tins purpose 
 he has made use of two telephones, A and B, communicating 
 through a line twenty-two yards in lepgth. He placed a small 
 file in slight contact with the vibrating disk of the telephone 
 A, and caused friction between the file and a metallic plate : 
 the sound thus produced was necessarily transmitted by the 
 telephone B, with an intensity which could be estimated. He 
 then substituted a battery for the telephone A, and the file was 
 introduced into the circuit by connecting it with one of the 
 poles. The current could only be closed by the friction of the 
 file with the plate, which had a spring, and was in communica- 
 tion with the other end of the circuit. In this way broken cur- 
 rents were obtained, which caused vibration in the telephone B, 
 and produced a sound of which the intensity varied with the 
 strength of the battery current. In this way M. Dcmoget en- 
 deavored to find the electric intensity capable of producing a 
 sound similar to that of the telephone A, and he ascertained 
 that it corresponded in intensity to that produced in a small 
 thermo-electric battery formed of an iron and a copper wire, 
 two millimetres in diameter, flattened at the end, and soldered 
 to the tin : the faint current produced by this battery only 
 caused a short wire galvanometer to deviate two degrees. 
 
 This estimate does not appear to us to unite so many con- 
 ditions, of accuracy as to enable us to deduce from it the de- 
 gree of sensitiveness possessed by a telephone a sensitiveness 
 which the experiments of Messrs. Warren de la Rue, Brongh, 
 and Peirce show to be much greater. Mr. Warren de la Rue, 
 as we have seen, used Thomson's galvanometer, and compared 
 the deviation produced on the scale of this galvanometer with 
 that caused by a Daniell cell traversing a circle completed by a 
 rheostat : he ascertained that the currents discharged by an or- 
 dinary Bell telephone are equivalent to those of a Daniell cell 
 traversing 100 megohms of resistance that is, 6,200,000 miles 
 of telegraphic wire. Mr. Brough, the Director of Indian Tele- 
 
IIELLESEX'S EXPERIMENTS. 141 
 
 graphs, considers that the strongest current which at any given 
 moment causes a Bell telephone to work does not exceed 
 loooooo f tne un it f current, that is, one Weber, and the 
 current transmitted to the stations on the Indian telegraphic 
 line is 400,000 times as strong. Finally, Professor Peirce, of 
 Boston, compares the effects of the telephonic current with 
 those which would be produced by an electric source of which 
 the electro -motive force should be ? ^ part of a volt, or 
 one Daniell cell. Mr. Peirce justly remarks that it is difficult 
 to estimate the real value of these kinds of currents at any pre- 
 cise sum, since it essentially varies according to the intensity 
 of the sounds produced on the transmitting telephone; but it 
 may be affirmed that it is less than the -nro"o-o<ro- P art f tue 
 current usually employed to work the instruments on tele- 
 graphic lines. 
 
 Signer Galileo Ferraris, who has recently published an inter- 
 esting treatise on this question in the Atti della Reale Acade- 
 mia delle Scienze di Torino (June 13th, 18Y8), states that the in- 
 tensity of the currents produced by the ordinary Bell telephone 
 varies with the pitch of the sound emitted. 
 
 Experiments by M. Hellesen, of Copenhagen. In order to 
 estimate the reciprocal effects of different parts of a telephone, 
 M. Hellesen has made telephones of the same size with three 
 different arrangements which act inversely to each other. The 
 first was of the ordinary form ; the second like that of Bell's 
 first system, that is, with a membrane supporting a small iron 
 armature on its centre, instead of a vibrating disk; and the 
 third telephone consisted of a hollow cylindrical magnet, with 
 the vibrating disk fixed to one of its poles, and the disk was 
 adapted to move before a flat, snail-shaped spiral, of which the 
 number of spirals equalled those of the two other helices. In 
 this last arrangement, the induced currents resulting from the 
 vibrations of the voice might be assimilated to those which fol- 
 low from the approximation and withdrawal of the two parallel 
 
142 THE TELEPHONE. 
 
 spirals, one of which should be traversed by a current. It is 
 this last arrangement which Mr. Bell has adopted as produ- 
 cing the best effects and, it is rare in the history of discover- 
 ies that an inventor hits at once on the best arrangement of his 
 instrument. 
 
 Experiments by M. Zetsche. There are always a few per- 
 verse minds, impelled by a spirit of contradiction to deny evi- 
 dence, and thus they attempt to depreciate a discovery of which 
 the glory irritates them. The telephone and the phonograph 
 have been the objects of such unworthy criticism. It has been 
 said that electric action had nothing to do with the effects pro- 
 duced in the telephone, and that it only acted under the influ- 
 ence of mechanical vibrations transmitted by the conducting 
 wire, just as in a string telephone. It was in vain to demon- 
 strate to these obstinate minds that no sound is produced when 
 the circuit is broken, and in order to convince them M. Zetsche 
 has made some experiments to show, from the mode in which 
 sound is propagated, that it is absurd to ascribe the sound pro- 
 duced in a telephone to mechanical vibration. He wrote to 
 this effect in an article inserted in the Journal Telegraphique, 
 Berne, January 25th, 1878 : 
 
 "The correspondence by telephone between Leipzig and 
 Dresden affords another proof that the sounds which reproduce 
 words at the receiving-station are due to electric currents, and 
 not to mechanical vibrations. The velocity with which sound 
 is transmitted by vibrations on the wire, in the case of longitu- 
 dinal undulations, may be estimated at three miles one furlong 
 a second, so that the sound ought to traverse the distance from 
 Leipzig to Dresden in twenty -five seconds. The same time 
 ought to elapse before receiving the answer; consequently, 
 there should be an interval of more than three-quarters of a 
 minute allowed for each exchange of communication, which is 
 by no means the case." 
 
 Experiments which may be made by any one, We will con- 
 
THE MICKOPI10XE. 143 
 
 elude tLis chapter, devoted to the account of the different ex- 
 periments made with the telephone, by the mention of a singu- 
 lar experiment, which, although easily performed, has only been 
 suggested a few months ago by a Pennsylvania newspaper. It 
 consists in the transmission of speech by a telephone simply 
 laid on some part of the human body adjacent to the chest. 
 It has been asserted that any part of the body will produce 
 this effect, but according to my experience, I could only suc- 
 ceed when the telephone was firmly applied to my chest. Un- 
 der such conditions, and even through my clothes, I could make 
 myself heard when speaking in a very loud voice, from which 
 it appears that the whole of the human body takes part in the 
 vibrations produced by the voice. In this case the vibrations 
 are mechanically transmitted to the" diaphragm of the sending 
 telephone not by the air, but by the body itself, acting on the 
 outside of the telephone. 
 
 THE MICROPHOXE. 
 
 The microphone is, in fact, only the sender of a battery tele- 
 phone, but with such distinctive characteristics that it may be 
 regarded as an original invention which is entitled to a special 
 name. The invention has lately given rise to an unfortunate 
 controversy between its inventor, Mr. Hughes, and Mr. Edison, 
 the inventor of the carbon telephone and the phonograph a 
 controversy which has been embittered by the newspapers, and 
 for which there were no grounds ; for, although the scientific 
 principle of the microphone may appear to be the same as that 
 of Mr. Edison's carbon sender, its arrangement is totally differ- 
 ent; its mode of action is not the same, and the effect required 
 of it is of quite another kind. Less than this is needed to 
 constitute a new invention. Besides, a thorough examination 
 of the very principle of the instrument must make us wonder 
 at Mr. Edison's claim to priority. He cannot, in fact, regard as 
 his exclusive possession the discovery of the property possessed 
 
144 THE TELEPHONE. 
 
 by some substances of moderate conductivity of having tins 
 power modified by pressure. In 1856, and often subsequent- 
 lyas, for example, in 1864, 1872, 1874, and 18751 made 
 numerous experiments on this point, which are described in the 
 first volume of the second edition of my "Expose des Appli- 
 cations de FElectricite," and also in several papers presented 
 to the Academic des Sciences, and inserted in their comptes 
 rendus. M. Clarac again, in 1865, employed a tube made of 
 plumbago, and provided with a movable electrode, to produce 
 variable resistances in a telegraphic circuit. Besides, in Mr. 
 Edison's telephonic sender, the carbon disk, as we have seen, 
 must be subjected to a certain initial pressure, in order that 
 the current may not be broken by the vibrations of the plate 
 on which it rests, and consequently the modifications of resist- 
 ance in the circuit which produce articulate sounds are only 
 caused by greater or less increase and diminution of pressure, 
 that is, by differential actions. "We shall presently see that 
 this is not the case with the microphone. In the first place, 
 the carbon contact is effected in the latter instrument on oth- 
 er carbons and not with platinum disks, and these contacts are 
 multiple. In the second place, the pressure exerted on all the 
 points of contact is excessively slight, so that the resistances 
 can be varied in an infinitely greater ratio than in Mr. Edison's 
 system ; and for this very reason it is possible to magnify the 
 sounds. In the third place, a microphone can be made of 
 other substances besides carbon. Finally, no vibrating disk is 
 needed to make the microphone act; the simple medium of 
 air is enough, so that it is possible to work the instrument 
 from some little distance. 
 
 We do not, therefore, see the grounds for Mr. Edison's as- 
 sertions, and especially for the way in which he has spoken of 
 Messrs. Hughes and Preece, who are well known in science, 
 and are in all respects honorable men. I repeat my regret 
 that Mr. Edison should have made this ill-judged attack on 
 
145 
 
 them, since it must injure himself, and is unworthy of an in- 
 ventor of such distinction. If we look at the question from 
 another point of view, we must ask Mr. Edison why, if he in- 
 vented the microphone, he did not make us acquainted with 
 its properties and results. These results are indeed startling, 
 since the microphone has in so short a time attracted general 
 attention; and it is evident that the clear-sighted genius of 
 this celebrated American inventor would have made the most 
 of the discovery if it were really his. The only justification 
 for Mr. Edison's claim consists in his ignorance of the purely 
 scientific discoveries made in Europe, so that he supposed the 
 invention of the microphone to be wholly involved in the 
 principle which he regards as his peculiar discovery. 
 
 In Mr. Hughes's instrument, which we are now considering, 
 the sounds, instead of reaching the receiving-stations much di- 
 minished, which is the case with ordinary telephones, and even 
 with that of Mr. Edison, are often remarkably increased, and it 
 is for this reason that Mr. Hughes has given to this telephonic 
 system the name of microphone, since it can be employed to 
 discover very faint sounds. Yet we must add that this in- 
 crease really takes place only when the sounds result from me- 
 chanical vibrations transmitted by solid substances to the send- 
 ing instrument. The sounds propagated through the air are 
 undoubtedly a little more intense than in the ordinary system, 
 but they lose some of their force, and therefore it cannot be 
 said that in this case the microphone has the same effect upon 
 sounds as the microscope has on objects on which light is 
 thrown. It is true that with this system it is possible to 
 speak at a distance from the instrument, and I have even been 
 able to transmit conversation in a loud voice, when standing at 
 a distance of nine yards from the microphone. When close 
 to the instrument, I was also perfectly able to make myself 
 heard at the receiving-station while speaking in a low voice, 
 and even to send the sounds to a distance of ten or fifteen cen- 
 
 7 
 
146 THE TELEPHONE. 
 
 timetres from the mouth-piece of the receiving telephone by 
 raising the voice a little ; but the increase of sound is not real- 
 ly very evident unless it is produced by a mechanical action 
 transmitted to the standard of the instrument. 
 
 Thus the steps of a fly walking on the stand are clearly 
 heard, and give the sensation of a horse's tread; and even a 
 fly's scream, especially at the moment of death, is said by Mr. 
 Hughes to be audible. The rustling of a feather or of a piece 
 of stuff on the board of the instrument, sounds completely in- 
 audible in ordinary circumstances, are distinctly heard in the 
 microphone. It is the same with the ticking of a watch 
 placed upon the stand, which may be heard at ten or fifteen 
 centimetres from the receiver. A small musical box placed 
 upon the instrument gives out so much sound, in consequence 
 of its vibratory movements, that it is impossible to distinguish 
 the notes, and in order to do so it is necessary to place the 
 box close to the instrument, without allowing it to come in 
 contact with any of its constituent parts. It therefore ap- 
 pears that the instrument is affected by the vibrations of air, 
 and the transmitted sounds are fainter than those heard close 
 to the box. On the other hand, the vibrations produced by 
 the pendulum of a clock, when placed in communication with 
 the standard of the instrument by means of a metallic rod, are 
 heard perfectly, and may even be distinguished when the con- 
 nection is made by the intervention of a copper wire. A cur- 
 rent of air projected on the system gives the sensation of a 
 trickle of water heard in the distance. Finally, the rumbling 
 of a carriage outside the house is transformed into a very in- 
 tense crackling noise, which may combine with the ticking of 
 a watch, and will often overpower it. 
 
 Different Systems of Microphones. The microphone has 
 been made in several ways, but the one represented in Fig. 39 
 is the arrangement which renders it the most sensitive. In 
 this system, two small carbon cubes, A, B, are placed one above 
 
DIFFERENT SYSTEMS. 147 
 
 the other on a vertical wooden prism ; two holes are pierced 
 in the cubes to serve as sockets for a spindle-shaped carbon 
 pencil, that is, with the points fined off at the two ends, and 
 
 FIG. 39. 
 
 about four centimetres long: if of a large size, the inertia will 
 be too great. One end of this pencil is in the cavity of the 
 lower carbon, and the other must move freely in the upper 
 cavity which maintains it in a position approaching to that of 
 instable equilibrium, that is, in a vertical position. Mr. Hughes 
 states that the carbons become more effective if they are steeped 
 in a bath of mercury at red heat, but they will act well without 
 undergoing this process. The two carbon cubes are also pro- 
 vided with metallic contacts which admit of their being placed 
 in connection with the circuit of an ordinary telephone in which 
 a Leclanche battery has been placed, or one, two, or three Daniell 
 cells, with an additional resistance introduced into the circuit. 
 
148 THE TELEPHONE. 
 
 In order to use this instrument, it is placed on a table, with 
 the board which serves to support it, taking care to deaden any 
 extraneous vibrations by interposing between this board and 
 the table several folds of stuff so arranged as to form a cushion, 
 or, which is better, a belt of wadding, or two caoutchouc tubes : 
 what is said by a person standing before this system is immedi- 
 ately reproduced in the telephone, and if a watch is placed on 
 the stand, or a box with a fly enclosed in it, all its movements 
 are heard. The instrument is so sensitive that words said in a 
 low voice are most easily heard, and it is possible, as I have al- 
 ready said, to hear the speaker when he is standing nine yards 
 from the microphone. Yet some precautions are necessary in 
 order to obtain good results with this system, and besides the 
 cushions placed beneath the instrument to guard it from the 
 extraneous vibrations which might ensue from any movements 
 communicated to tie table, it is also necessary to regulate the 
 position of the carbon pencil. It must always rest on some 
 point of the rim of the upper cavity ; but as the contact may 
 be more or less satisfactory, experience alone will show when it 
 is in the best position, and it is a good plan to make use of a 
 watch to ascertain this. The ear is then applied to the tele- 
 phone, and the pencil is placed in different positions until the 
 maximum effect is obtained. To avoid the necessity of regu- 
 lating the instrument in this way, which must be done repeat- 
 edly by this arrangement, MM. Chardin and Berjot, who are 
 ingenious in the construction of telephones on this pattern, 
 have added to it a small spring-plate, of which the pressure can 
 be regulated, and which rests against the carbon pencil itself. 
 This system works well. 
 
 M. Gaiffe, by constructing it like a scientific instrument, has 
 given the instrument a more elegant form. Fig. 40 represents 
 one of his two models. In this case, the cubes or carbon dice 
 are supported by metallic holders, and the upper one,.E, is made 
 to move up and down a copper column, G, so as to be placed 
 
CABETTE SYSTEM. 
 
 149 
 
 in the right position by tightening the screw, V. In this way 
 the carbon pencil can be made to incline more or less, and its 
 pressure on the upper carbon can be altered at pleasure. When 
 
 Fio. 40. 
 
 the pencil is in a vertical position, the instrument transmits 
 articulate sounds with difficulty, on account of the instability 
 of the points of contact, and rustling sounds are heard. When 
 the inclination of the pencil is too great, the sounds are purer 
 and more distinct, but the instrument is less sensitive. The 
 exact degree of inclination should be ascertained, which is easily 
 done by experiment. In another model M. Gaiffe substitutes 
 for the carbon pencil a very thin square plate of the same ma- 
 terial, bevelled on its lower and upper surfaces, and revolving 
 in a groove cut in the lower carbon. This plate must be only 
 slightly inclined in order to touch the upper carbon, and under 
 these conditions it transmits speech more loudly and distinctly. 
 I must also mention another arrangement, devised by Cap- 
 tain Carette, of the French Engineers, which is very successful 
 in transmitting inarticulate sounds. In this case the vertical 
 carbon- is pear-shaped, and its larger end rests in a hole made 
 
150 
 
 THE TELEPHONE. 
 
 in the lower carbon ; its upper and pointed end goes into a 
 small hole made in the upper carbon, but so as hardly to touch 
 it, and there is a screw to regulate the distance between the 
 two carbons. Under such conditions, the contacts are so un- 
 stable that almost anything will put an end to them, and con- 
 sequently the variations in the intensity of the transmitted 
 current are so strong that the sounds produced by the tele- 
 phone may be heard at the distance of several yards. 
 
 Fig. 41 represents another arrangement, devised by M. Du- 
 cretet. The two carbon blocks are at D D', the movable carbon 
 pencil is at C, the telephone at T, and the binding screws at 
 B B'. An enlarged figure of the arrangement of the carbons 
 is given on the left. The arm which holds the upper carbon, 
 D, is fastened to a rod, bearing a plate, P', of which the sur- 
 
 FIG. 41. 
 
 face is rough, and a little cage, C', made of wire netting, can 
 be placed upon the plate, so as to enable us to study the move- 
 
 ments of living insects. 
 
151 
 
 When speech is to be transmitted with a force which can 
 make the telephone audible in a large room, the microphone 
 must have a special arrangement, and Fig. 42 represents the 
 one which Mr. Hughes considers the most successful, to which 
 he has given the name of speaker. 
 
 In this new form, the movable carbon which is required to 
 produce the variable contacts is at C, at the end of a horizon- 
 
 Fio. 42. 
 
 tal bar, B A, properly balanced so as to move up and down on 
 its central point. The support on which the bar oscillates is 
 fastened to the end of a spring -plate in order that it may 
 vibrate more easily, and the lower carbon is placed at D, below 
 the first. It consists of two pieces laid upon each other, so as 
 to increase the sensitiveness of the instrument, and we repre- 
 sent the upper piece at E, which is raised, so as to show that 
 when it is desired only one of these carbons need be used. 
 For this purpose the carbon, E. is fastened to a morsel of paper, 
 which is fixed to the little board, and contributes to the articu- 
 lation. A spring, R, of which the tension can be regulated by 
 the screw ,* serves to regulate the pressure of the two carbons. 
 Mr. Hughes recommends the use of metallized charcoal pre- 
 pared from deal. 1 The whole is then enclosed in a semi- 
 
 1 These carbons are made by heating, in a temperature gradually raised 
 
152 THE TELEPHONE. 
 
 cylindrical case, H I G, made of very thin pieces of deal, and 
 the system is fixed, together with another similar system, in a 
 flat box, M J L I, which, on the side M I, presents an opening 
 before which the speaker stands, taking care to keep his lower 
 lip at a distance of two centimetres from the bottom of the 
 box. If the two telephones are connected for strength, and if 
 the battery employed consists of two cells of bichromate of 
 potash, it is possible to act so strongly on the current, that, 
 after traversing an induction coil only six centimetres long, a 
 telephone of Bell's square model can be made to speak, so as 
 to be heard from all parts of a room ; a speaking-tube, about 
 a yard long, must indeed be applied to it. Mr. Hughes asserts 
 that the sounds produced by it are nearly as loud as those of 
 the phonograph, and this is confirmed by Mr. Thomson. 
 
 M. Boudet de Paris has lately invented a microphone speak- 
 er of the same kind, with which it is possible to make a small 
 telephone utter a loud sound. An induction coil, influenced 
 by a single Leclanche cell, must be employed. 
 
 Suppose that a very small carbon rod with pointed ends is 
 placed at the bottom of a box, of about the size of a watch. 
 One end of the rod rests against a morsel of carbon, which is 
 fastened to a very thin steel diaphragm, placed before a mouth- 
 piece which acts as a lid to the box, and is screwed above it. 
 Next, suppose that a small piece of paper, folded in two, in the 
 shape of the letter V, is fixed above that part of the carbon in 
 contact with the carbon of the diaphragm. This constitutes 
 the instrument, and in order to work it, it must be held in a 
 vertical position before the mouth, at a distance of about three 
 centimetres, and it is necessary to speak in the ordinary tone. 
 If the telephone is placed in direct communication with this 
 instrument, it will send the voice to a distance. Without em- 
 
 to white heat, fragments of deal of a close fibre, which is enclosed in an 
 iron tube or box hermetically sealed. 
 
BOUDET'S SPEAKER. 153 
 
 ploying a Leclanche cell, the voice may be heard at the dis- 
 tance of ten yards, if one of the carbons used for the phono- 
 graph is placed before the mouth-piece of the telephone. 
 
 In this system, the sensitiveness of the instrument is entirely 
 due to the slightness of the contact between the two carbons, 
 and the slight elasticity of the folded paper constitutes the 
 contact. Perhaps the paper itself has some influence ; at any 
 rate the most delicate spiral spring is incapable of producing 
 the same effect, and it is necessary to suspend the instrument 
 vertically, in order that the weight of the movable carbon may 
 not affect it. It can be regulated by depressing or elevating 
 that part of the paper which rests on the carbon rod. 
 
 Although it is possible to work all telephones with this in- 
 strument, some are more effective than others. The mouth- 
 piece must be concave, and the diaphragm must be close to its 
 rira, and must be made of a particular kind of tin. The or 
 dinary diaphragm does not act well, and M. Boudet de Paris 
 has tried several, so as to obtain the maximum effect. 
 
 It is certain that when the instruments are as well regulated 
 as those which the inventor has deposited with me, their re- 
 sults are really surprising. It is even possible, by using several 
 microphones at the sending station, to obtain the reproduction 
 of duets, and even of trios, with remarkable effect. 
 
 With this kind of microphone speaker M. Boudet de Paris 
 is able to transmit speech into a snuffbox telephone, merely 
 consisting of a flat helix of wire, placed before a slightly mag- 
 netized steel plate, and without insertion of a magnetic core. 
 A single Leclanche cell was enough. An experiment of the 
 same nature was tried in England, but it was found necessary 
 to use six Leclanche cells. 
 
 The microphone may also be made of morsels of carbon 
 pressed into a box between two metallic electrodes, or enclosed 
 in a tube with two electrodes represented by two elongated 
 fragments of carbon. In the latter case the carbons ought to 
 
 7* 
 
154 
 
 THE TELEPHONE. 
 
 be as cylindrical as possible, and those made by .M. Carre for 
 the Jablochkoff candles are very suitable. Fig. 43 represents 
 an instrument of this kind which M. Gaiffe arranged for me, 
 and which, as we shall see, serves as a thermoscope (Fig. 44). 
 
 FIGS. 43, 44. 
 
 It is composed of a quill filled with morsels of carbon, and 
 those at the two ends are tipped with metal. One of these 
 metal tips ends in a large-headed screw which, by means of its 
 supports A B, is able to press more or less on the morsels of 
 carbon in the tube, and consequently to establish a more or 
 less intimate contact between them. When the instrument 
 is properly regulated, speech can be reproduced by speaking 
 above the tube. It is therefore a microphone as well as a 
 thermoscope. Mr. Hughes has remarked one curious fact, 
 namely, that if the different letters of the alphabet are pro- 
 nounced separately before this sort of microphone, some of 
 them are much more distinctly heard than others, and it is pre- 
 cisely those which correspond to the breathings of the voice. 
 A microphone of this kind may be made by substituting for 
 
155 
 
 the carbon powders of more or less conductivity, or even metal 
 filings. I have shown in my paper on the action of substances 
 of moderate conductivity, that such power varies considerably 
 with the pressure and the temperature ; and as the microphone 
 is based on the differences of conducting power which result 
 from differences of pressure, we can understand that these pow- 
 ders may be used as a means of telephonic transmission. In 
 a recent arrangement of this system Mr. Hughes has made the 
 powder adhere together with a sort of gum, and has thus made 
 a cylindrical pencil which, when connected with two electrodes 
 which are good conductors, can produce effects analogous to 
 those we have just described. As I have said, it is possible to 
 use metal filings, but Mr. Hughes prefers powdered charcoal. 
 
 Mr. Blyth states that a flat box,*about 15 -inches by 9, filled 
 with coke, and with two tin electrodes fixed to the two ends, is 
 one of the best arrangements for a microphone. He says that 
 three of these instruments, hung like pictures against the wall 
 of a room, would suffice, when influenced by a single Leclanche 
 cell, to make all the sounds produced in a telephone audible, 
 and especially vocal airs. Mr. Blyth even asserts that a micro- 
 phone capable of transmitting speech can be made with a sim- 
 ple piece of coke, connected with the circuit by its two ends, 
 but it must be coke : a retort carbon, with electrodes, will 
 not act. 
 
 It is a remarkable property of these kinds of microphones 
 that they can act without a battery, at least when they are so 
 arranged as to form a voltaic element for themselves, and this 
 can be done by throwing water on the carbons. Mr. Blyth, 
 who was the first to speak of this system, does not distinctly 
 indicate its arrangement, and we may assume that his instru- 
 ment did not differ from the one we have already described, to 
 which water must have been added. In this way, indeed, I 
 have been able to transmit not only the ticking of a watch and 
 the sounds of a musical box, Tbut speech itself, which was often 
 
156 THE TELEPHONE. 
 
 more distinctly expressed than in an ordinary microphone, since 
 it was free from the sputtering sound which is apt to accom- 
 pany the latter. Mr. Blyth also asserts that sounds may be 
 transmitted without -the addition of water, but in this case he 
 considers that the result is due to the moisture of the breath. 
 Certainly much moisture is not required to set a voltaic couple 
 in action, especially when a telephone is the instrument of man- 
 ifestation. The ordinary microphone may be used without a 
 battery, if the circuit in which it is inserted is in communica- 
 tion with the earth by means of earthen cakes ; the currents 
 which then traverse the circuit will suffice to make the tickings 
 of a watch placed upon the microphone perfectly audible. M. 
 Cauderay, of Lausanne, in a paper sent to the Academic des Sci- 
 ences, July 8, 1878, informs us that he made this experiment 
 on a telegraphic wire which unites the Hotel des Alpes at Mon- 
 treux with a chalet on the hill a distance of about 550 yards. 
 The Microphone used as a Speaking Instrument. The mi- 
 crophone cannot only transmit speech, but it can also, under 
 certain conditions, reproduce it, and consequently supply the 
 place of the receiving telephone. This seems difficult to un- 
 derstand, since a cause for the vibratory motion produced in 
 part of the circuit itself can only be sought in the variations in 
 intensity of the current, and the effects of attraction and mag- 
 netization have nothing to do with it. Can the action be re- 
 ferred to the repulsions reciprocally exerted by the contiguous 
 elements of the same current 1 Or are we to consider it to be 
 of the same nature as that which causes the emission of sounds 
 from a wire when a broken current passes through it, so that 
 an electric current is itself a vibratory current, as Mr. Hughes 
 believes? It is difficult to reply to these questions in the 
 present state of science ; we can only state the fact, which has 
 been published by Messrs. Hughes, Blyth, Robert Courtenay, 
 and even by Mr. Edison himself. I have been able to verify 
 the fact myself under the experimental conditions indicated by 
 
CAPABILITIES OF THE MICROPHONE. 157 
 
 Mr. Hughes, but I was not so successful in the attempt to repeat 
 Mr. Blyth's experiments. This gentleman stated that in order 
 to hear speech in a microphone it would be enough to use the 
 model made from fragments of carbon, as we have described, 
 to join to it a second microphone of the same kind, and to in- 
 troduce into the circuit a battery consisting of two Grove ele- 
 ments. If any one then speaks above the carbons of one of 
 the microphones, what is said should be distinctly heard by the 
 person who puts his ear to the other, and the importance of 
 the sounds thus produced will correspond with the intensity of 
 the electric source employed. As I have said, I was unable by 
 following this method to hear any sound, still less articulate 
 speech ; and if other experiments had not convinced me, I 
 should have doubted the correctness of the- statement. But 
 this negative experiment does not, in fact, prove anything, since 
 it is possible that my conditions were wrong, and that the cin- 
 ders which I employed were not subject to the same conditions 
 as Mr. Blyth's fragments of coke. 
 
 With respect to Mr. Hughes' s experiments, I have repeated 
 them with the microphone made by M M. Chardin and Berjot, 
 using that by M. Gaiffe as the sender, and I ascertained that 
 with a battery of only four Leclanche cells, a scratch made on 
 the sender, and even the tremulous motion and the airs played 
 in a little musical box placed on the sender, were reproduced 
 very faintly, it is true in the second microphone ; in order to 
 perceive them, it was enough to apply the ear to the vertical 
 board of the instrument. It is true that speech was not re- 
 produced, but of this Mr. Hughes had warned me ; it was 
 evident that with this arrangement the instrument was not 
 sufficiently sensitive. 
 
 A different arrangement of the microphone is required for 
 the transmission and the reproduction of speech by this system, 
 and a section of the one which Mr. Hughes found most suc- 
 cessful is given in Fig. 45. It somewhat resembles Mr. Hnghes's 
 
158 
 
 THE TELEPHONE. 
 
 microphone speaker, placed in a vertical position, and the fixed 
 carbon is fastened to the centre of the stretched membrane of 
 
 a string telephone. The ear 
 or mouth tube is at A, the 
 membrane at DD,the carbon 
 just mentioned at C: this 
 carbon is of metallized char- 
 coal prepared from deal, and 
 so also is the double carbon, 
 E, which is in contact with 
 it, and is fastened to the up- 
 per end of the little bar, G I. 
 The whole is enclosed in a 
 small box, and the pressure 
 exerted on the contact of 
 the two carbons is regulated 
 by a spring, R, and a screw, 
 FlG - 45 ' H. The tube of the tele- 
 
 phone serves as an acoustic tube for the listener, and Mr. 
 Hughes's speaker, described above, acts as sender. It is hardly 
 necessary to say that the two instruments are placed at each 
 end of the circuit, that the carbons are connected with the two 
 poles of a battery of one or two cells of bichromate of potash, 
 or two Bunsen or six Leclanche cells, and the two instruments 
 are connected by the line wire. Under such conditions, con- 
 versation may be exchanged, but the sounds are always much 
 less distinct than they are in a telephone. 
 
 I was able to ascertain this fact with a roughly made instru- 
 ment brought from England by Mr. Hughes. MM. Berjot, 
 Chardin, and de Meritens, who were also present at the experi- 
 ments, were able with me to hear speech perfectly, and I have 
 since successfully repeated the experiment alone, but it does not 
 always succeed, and under its present conditions the instrument 
 has no importance in a scientific point of view. It is evident 
 
OTHER SYSTEMS. 159 
 
 that the instrument can dispense with any support, and the 
 little box then forms the handle of the instrument; in this 
 case the two binding screws are placed at the end of this han- 
 dle, as in a telephone. The microphone speaker with a disk, 
 represented in Fig. 5, which acts as sender to the singing con- 
 denser, can be used, when properly regulated, as a receiving mi- 
 crophone. M. Berjot has obtained good results from a little 
 instrument of the same kind as that in Fig. 45, but with a 
 metal diaphragm, and the microphonic system consists of a 
 cylindrical piece of carbon resting on a small disk of the same 
 substance, which is galvanized and soldered to the diaphragm. 
 The whole is enclosed in a small round box, with its upper 
 part cut in the form of a mouth-piece. 
 
 It seems that all microphone senders with -disks can repro- 
 duce speech more or less perfectly ; it is a question of adjust- 
 ing and refining the carbon points of contact. A weak battery, 
 consisting of a single Leclanche cell, is better for these instru- 
 ments than a strong battery, precisely because of the effects of 
 oxidation and polarization, which are so energetically produced 
 at these points of contact when the battery is strong. 
 
 The effects of the microphone receiver explain the sounds, 
 often very intense, produced by the Jablochkoff candles when 
 they are influenced by electro - magnetic machines. These 
 sounds always vibrate in unison with those emitted by the ma- 
 chine itself, and they result, as I have already shown, from the 
 rapid magnetizations and demagnetizations which are effected 
 by the machine. These effects, observed by M. Marcel Deprez, 
 were particularly marked in M. de Meritens's first machines. 
 
 Other Arrangements of Microphones. An arrangement such 
 as we have just described has been employed by M. Carette to 
 form an extremely powerful microphone speaker. The only 
 difference is that the stretched membrane is replaced by a thin 
 metallic disk : he fastens one of the carbons to the centre of 
 this disk, and applies to it the other carbon, which is pointed, 
 
160 THE TELEPHONE. 
 
 and held by a porte-carbon with a regulating screw, so that the 
 pressure which takes place between the two carbons may be 
 regulated at pleasure. By this arrangement speech may be 
 heard at a distance from the telephone. In other respects it 
 resembles the telephone sender represented in Fig. 5. 
 
 M. de Meritens has executed the system represented, Fig. 45, 
 on a large scale, forming the tube, A B, of a zinc funnel a yard 
 in length, and in this way he has been able to magnify the 
 sounds, so that a conversation held in a low voice, three or four 
 yards from the instrument, has been produced in a telephone 
 with more sonorous distinctness. The instrument was placed 
 on the floor of the apartment, with the opening of the funnel 
 above, and the telephone was in the cellars of the house. 
 
 The form of the microphone has been varied in a thousand 
 ways, to suit the purposes to which it was to be applied. In 
 the English Mechanic and World of Science, June 28th, 1878, 
 we see the drawings of several arrangements, one of which is 
 specially adapted for hearing the steps of a fly. It is a box, 
 with a sheet of straw paper stretched on its upper part; two 
 carbons, separated by a morsel of wood, and connected with 
 the two circuit wires, are fastened to it, and a carbon pencil, 
 placed crosswise between the two, is kept in this position by a 
 groove made in the latter. A very weak battery will be enough 
 to set the instrument at work, and when the fly walks over the 
 sheet of paper it produces vibrations strong enough to react 
 energetically on an ordinary telephone. The instrument must 
 be covered with a glass globe. When a watch is placed on the 
 membrane, with its handle applied to the morsel of wood which 
 divides the two carbons, the noise of its ticking may be heard 
 through a whole room. Two carbon cubes placed side by side, 
 and only divided by a playing-card, may also be used instead 
 of the arrangement of carbons described above. A semicircular 
 cavity, made in the upper part of the two carbons, in which are 
 placed some little carbon balls, smaller than a pea and larger 
 
TROUVE'S SYSTEM. 161 
 
 than a mustard-seed, will make it possible to obtain multiple 
 contacts which are very mobile and peculiarly fit for telephon- 
 ic transmissions. This arrangement has been made by Mr. T. 
 Cuttriss. 
 
 Several other arrangements of microphones have been devised 
 by different makers and inventors, such as those of Messrs. Va- 
 rey, Trouve, Vereker, De Combettes, Loiseau, Lippens, De Cour- 
 tois, Pollard, Voisin, Dumont, Jackson, Paterson, Taylor, etc., 
 and they are more or less satisfactory. The instruments of 
 MM. Yarey, Trouve, Lippens, and De Courtois are the most in- 
 teresting, and we will describe them. 
 
 M. Varey's microphone consists of a sounding-box of deal, 
 mounted in a vertical position on a stand, and two microphones 
 are arranged on either side of it, with vertical carbons united 
 for tension. A small Gaiffe cell of chloride of silver, without 
 liquid, is applied to the standard of the instrument, and is 
 enough to make it work perfectly. This system is extremely 
 sensitive. 
 
 M. Trouve's microphones, represented in Figs. 46, 47, 48, are 
 extremely simple, so that he is able to sell them at a very mod- 
 erate price. They generally consist of a small vertical cylindri- 
 cal box, as we see in the figure, with disks of carbon at its two 
 
 FIG. 46. 
 
 ends, which are united by a carbon rod, or by a metallic tube 
 tipped with carbon. This rod or tube turns freely in two cav- 
 
162 THE TELEPHONE. 
 
 ities made in the carbons, and the box, while acting as a sound- 
 ing-box, becomes at the same time a prison for the insects 
 whose movements and noises are the objects of study. 
 
 These boxes may be suspended on a cross-bar (Fig. 4*7) by 
 the two communicating wires, so as to be completely insulated. 
 In this case the ticking of a watch placed upon the board, fric- 
 tion, and external shocks are hardly heard ; but, on the other 
 hand, the sound vibrations of the air alone are transmitted, and 
 
 FIG. 4T. 
 
 they acquire great distinctness. We have often repeated these 
 experiments, and have always found that the tones of the voice 
 were perfectly preserved. 
 
 The model represented, Fig. 48, is still more simple, and ap- 
 pears to be the latest development of this kind of instrument. 
 It consists of a stand and a disk united by a central rod. The 
 upper disk moves round the central rod, and permits the verti- 
 cal carbon to assume any inclination which is desired. It is 
 evident that the instrument will become less sensitive when the 
 carbon is more oblique. 
 
 We must also mention a very successful microphone devised 
 by M. Lippens. It is a slightly made box, like that of M. Va- 
 
M. LIPPENS'S MICROPHONE. 163 
 
 rey, and on its opposite faces there are applied, on two frames 
 left empty for the purpose, two thin plates of hardened caout- 
 chouc, in the centre of which, inside the box, two carbons are 
 fastened, and on their outer surface a half-sphere is hollowed. 
 
 FIG. 48. 
 
 The interval between the two carbons hardly amounts to two 
 millimetres, and a carbon ball is inserted into the two cavities 
 which form its spherical case. This ball is supported by a spi- 
 ral spring which can be extended more or less by means of a 
 wire wound on a windlass which is fixed above the instrument, 
 like the spring of an electric telegraph instrument. By means 
 of this spring, the pressure of the carbon bait against the sides 
 of the cavity which contains it can be regulated at pleasure, and 
 the sensitiveness of the instrument and its capacity for trans- 
 mitting speech can be adjusted. Under these conditions, the 
 vibrations of the caoutchouc plates directly affect the micro- 
 phone, and the currents of air have no influence on it, so that 
 the effects are more distinct. It is so sensitive that it is best 
 for the speaker to place himself at the distance of at least fifty 
 centimetres from the instrument. M. Lippens's instrument is 
 a pretty one, mounted on a wooden stand which is neatly 
 turned. 
 
 In order to put an end to the sputtering usual in micro- 
 phones, it occurred to M. de Courtois to prevent any cessation 
 of contact between the carbons by keeping them close together, 
 
164 THE TELEPHONE. 
 
 and to effect the variations of resistance necessary for articu- 
 late sounds by making them slide over each other, so as to in- 
 sert a shorter or longer portion of the carbon in the circuit. 
 For this purpose a vibrating disk is placed in a vertical posi- 
 tion in a rigid frame, and a small conducting rod, terminated 
 by a pointed carbon, is applied to it, with this carbon point 
 resting on another flat piece of carbon placed below it. Influ- 
 enced by the vibrations of the disk, the carbon point moves to 
 and fro, effecting more or less extensive contacts with the lower 
 carbon, and thus producing variations of resistance which al- 
 most correspond to the range of vibrations on the disk. 
 
 Experiments made with the Microphone. I must now men- 
 tion the interesting experiments which led Mr. Hughes to the 
 invention of the remarkable instrument of which we have spo- 
 ken, as well as those undertaken by other scientific men, either 
 from a scientific or a practical point of view. 
 
 Believing that light and heat can modify the conductivity 
 of bodies, Mr. Hughes went on to consider whether sound vi- 
 brations, transmitted to a conductor traversed by a current, 
 would not also modify this conductivity by provoking the 
 contraction and expansion of the conducting molecules, which 
 would be equivalent to the shortening or lengthening of the 
 conductor thus affected. If such a property existed, it would 
 make it possible to transmit sounds t<? a distance, since varia- 
 tions in the conductivity would result from variations corre- 
 sponding to the intensity of the current acting on the tele- 
 phone. The experiment which he made on a stretched metal 
 wire did not, however, fulfil his expectation, and it was only 
 when the wire vibrated so strongly as to break, that he heard 
 a sound at the moment of its fracture. When he again joined 
 the two ends of the wire, another sound was produced, and he 
 soon perceived that imperfect contact between the two broken 
 ends of wire would enable him to obtain a sound. Mr. Hughes 
 was then convinced that the effects he wished to produce could 
 
HUGHES'S EXPEKIMENTS. 
 
 165 
 
 only be obtained with a divided conductor, and by means of 
 imperfect contacts. 
 
 He then sought to discover the degree of pressure which it 
 was most expedient to exert between the two adjacent ends of 
 the wire, and for this purpose he effected the pressure by means 
 of weights. He ascertained that when the pressure did not ex- 
 ceed the weight of an ounce on the square inch at the point of 
 connection, the sounds were reproduced with distinctness, but 
 somewhat imperfectly. He next modified the conditions of 
 the experiment, and satisfied himself that it was unnecessary to 
 join the wires end to end in order to obtain this result. They 
 might be placed side by side on a board, or even separated 
 (with a conductor placed crosswise between them), provided 
 that the conductors were of iron, and that they were kept in 
 metallic connection by a slight and constant pressure. The ex- 
 
 FIG. 40. 
 
 periment was made with three Paris points, and arranged as it 
 appears in Fig. 49, and it has since been repeated under very 
 favorable conditions by Mr. Willoughby Smith with three of 
 the so-called rat-tail files, which made it possible to transmit 
 even the faint sound of the act of respiration.' 
 
 1 Mr. Willoughby Smith varied this experiment by placing a packet of 
 
166 . THE TELEPHONE. 
 
 He afterward tried different combinations of the same nat- 
 ure, which offered several solutions of continuity, and a steel 
 chain produced fairly good results, but slight inflections, like 
 those caused by the timbre of the voice, were not reproduced, 
 and he tried other arrangements. He first sought to apply me- 
 tallic powders to the points of contact ; powdered zinc and tin, 
 known in commerce under the name of white bronze, greatly 
 increased the effects obtained ; but they were unstable, on ac- 
 count of the oxidation of the contacts ; and it was in seeking 
 to solve this difficulty, as well as to discover the most simple 
 means of obtaining a slight and constant pressure on the con- 
 tacts, that Mr. Hughes was led to the arrangement, previously 
 described, of carbons impregnated with mercury, and he thus 
 obtained the maximum effect. 1 
 
 Mr. Hughes considers that the successful effects of the micro- 
 phone depend on the number and perfection of the contacts, 
 and this is doubtless the reason why some arrangements of the 
 
 silk threads coated with copper on the disconnected ends of the circuit, 
 which were arranged at right angles with each other. Under these con- 
 ditions the instrument became so sensitive, that the current of air pro- 
 duced by a lamp placed above the system caused a decided crackling 
 noise in the telephone. 
 
 1 Mr. Hughes observes on this subject that carbon is a valuable mate- 
 rial for such purposes, since it does not oxidize, and its effects are greater 
 when combined with mercury. He takes the prepared charcoal used by 
 artists, brings it to a white heat, and suddenly plunges it in a bath of mer- 
 cury, of which the globules instantly penetrate the pores of charcoal, and 
 may be said to metallize it. He also tried charcoal coated with a deposit 
 of platinum, or impregnated with chloride of platinum, but this was not . 
 more successful than the former method. If the charcoal of fir-wood is 
 brought to a white heat in an iron tube, containing tin and zinc, or any 
 other metal which readily evaporates, it is metallized, and is adapted for 
 use if the metal is subdivided in the pores of charcoal and not combined 
 with it. When iron is introduced into carbon in this way, it is one of the 
 most effective metals. The charcoal of fir-wood, in itself a bad conductor, 
 may thus acquire great conducting power. 
 
' 
 
 V J /> 
 f \ .- 
 
 THEOR^. S , / ' , 167 
 
 V> - f * <"* ' 
 
 carbon pencil in the instrument described above^A^ce more/''*, 
 favorable than others. Jf \ 
 
 In order to reconcile these experiments with his precoQceivol,/ 
 ideas, Mr. Hughes thought that, since the differences of resist- * , 
 ance proceeding from the vibrations of the conductor were 
 only produced when it was broken, the molecular movements 
 were arrested by the lateral resistances which were equal and 
 opposite, but that if one of these resistances were destroyed, 
 the molecular movement could be freely developed. He con- 
 siders that an imperfect contact is equivalent to the suppres- 
 sion of one of these resistances, and as soon as this movement 
 can take place, the molecular expansions and contractions 
 which result from the vibrations must correspond to the in- 
 crease or diminution of resistance in the circuit. We need 
 not pursue Mr. Hughes's theory farther, since it would take 
 too long to develop it, and we must continue our examination 
 of the different properties of the microphone. 1 
 
 Carbon, as we have said, is not the only substance which can 
 be employed to form the sensitive organ of this system of 
 transmission. Mr. Hughes has tried other substances, includ- 
 ing those which are good conductors, such as metals. Iron 
 afforded rather good results, and the effect produced by sur- 
 faces of platinum when it was greatly subdivided was equal, if 
 
 1 Mr. Hughes remarks that the vibrations which affect the microphone, 
 even in speaking at a distance from the instrument, do not proceed from 
 the direct action of the sound waves on the contacts of the microphone, 
 but from the molecular vibrations produced by it on the board which 
 serves to support the instrument ; he shows, in fact, that the intensity of 
 sounds produced by the microphone is in proportion to the size of the sur- 
 face of this board, and when the sending microphone is enclosed in a 
 cylindrical case, its sensitiveness is not much diminished if the surface of 
 the box enclosing the whole is sufficiently large. From this point of view 
 he has sought to increase the sensitiveness of his instruments by fixing 
 the frame on which the movable parts of the sender and receiver revolve 
 on a spring-plate. 
 
168 THE TELEPHONE. 
 
 not superior, to that furnished by the mercurized carbon. Yet 
 since the difficulty of making instruments with this metal is 
 greater, he prefers the carbon, which resembles it in being 
 incapable of oxidation. 
 
 We have already said that the microphone may be used as 
 a thermoscope, in which case it must have the special arrange- 
 ment represented in Fig. 43. Under these conditions, heat, 
 reacting on the conductivity of these contacts, may cause such 
 variations in the resistance of the circuit that the current of 
 three Daniell cells will be annulled by approaching the hand to 
 the tube. In order to estimate the relative -intensity of the 
 different sources of heat, it will be enough to introduce into 
 the circuit of the two electrodes, A and B, Fig. 43, a battery, 
 P, of one or two Daniell cells, and a moderately sensitive 
 galvanometer, G. For this purpose one of 120 turns will suf- 
 fice. When the deviation decreases, it shows that the source 
 of heat is superior to the surrounding atmosphere ; and con- 
 versely, that it is inferior when the deviation increases. Mr. 
 Hughes says that the effects resulting from the intervention 
 of sunshine and shadow are shown on the instrument by con- 
 siderable variations in the deviations of the galvanometer. In- 
 deed, it is so sensitive to the slightest variations of temperature 
 that it is impossible to maintain it in repose. 
 
 I have repeated Mr. Hughes's experiments with a single 
 Leclanche cell, and for this purpose I employed a quill, filled 
 with five fragments of carbon, taken from the cylindrical car- 
 bons of small diameter which are made by M. Carre for the 
 electric light. I have obtained the results which are men- 
 tioned by Mr. Hughes, but I ought to say that the experiment 
 is a delicate one. When the pressure of the fragments of 
 carbon against each other is too great, the current traverses 
 them with too much force to allow the calorific effects to vary 
 the deviation of the galvanometer, and when the pressure is 
 too slight, the current will not pass through them. A medium 
 
169 
 
 degree of pressure must, therefore, be effected to insure the 
 success of the experiment, and when it is obtained, it is ob- 
 served that on the approach of the hand to the tube, a devia- 
 tion of 90 will, after a few seconds, diminish, so that it seems 
 to correspond with the approach or withdrawal of the hand. 
 But breathing produces the most marked effects, and I am 
 disposed to believe that the greater or less deviations produced 
 by the emission of articulate sounds, when the different letters 
 of the alphabet are pronounced separately, are due to more or 
 less direct emissions of heated gas from the chest. It is cer- 
 tain that the letters which require the most strongly marked 
 sounds, such as A, F, H, I, K, L, M, N, O, P, R, S,W, Y, Z, pro- 
 duce the greatest deviations of the galvanometric needle. 
 
 In my paper on the conductivity of such bodies as are mod- 
 erately good conductors, I had already pointed out this effect 
 of heat upon divided substances, and I also showed that after 
 a retrograde movement, which is always produced at once, a 
 movement takes place in an inverse direction to the index of 
 the galvanometer when heat has been applied for some in- 
 stants, and this deviation is much greater than one which is 
 first indicated. 
 
 In a paper published in the American Scientific Journal, 
 June 28th, 1878, Mr. Edison gives some interesting details on 
 the application of his system of a telephonic sender to measur- 
 ing pressures, expansions, and other forces capable of varying 
 the resistance of the carbon disk by means of greater or less 
 compression. Since his experiments on this subject date from 
 December, 1877, he again claims priority in the invention of 
 using the microphone as a thermoscope ; but we must observe 
 that according to Mr. Hughes's arrangement of his instrument, 
 the effect produced by heat is precisely the reverse of the ef- 
 fect described by Mr. Edison. In fact, in the arrangement 
 adopted by the latter, heat acts by increasing the conductivity 
 acquired by the carbon under the increased pressure produced 
 
 8 
 
170 THE TELEPHONE. 
 
 by the expansion of a body sensitive to heat ; in Mr. Hughes's 
 system, the effect produced by heat is precisely the contrary, 
 since it then acts only on the contacts, and not by means of 
 pressure. Therefore the resistance of the microphone-thermo- 
 scope is increased under the influence of heat, instead of being 
 diminished. This contrary effect is due to the division of 
 some substance which is only a moderate conductor, and I 
 have shown that under such conditions these bodies, when only 
 slightly heated, always diminish the intensity of the current 
 which they transmit. I believe that Mr. Edison's arrangement 
 is the best for the thermoscopic instrument, and makes it pos- 
 sible to measure much less intense sources of heat. Indeed he 
 asserts that by its aid the heat of the luminous rays of the 
 stars, moon, and sun may be measured, and also the variations 
 of moisture in the air, and barometric pressure. 
 
 This instrument, which we give, Fig. 50, with its several de- 
 tails, and with the rheostatic arrangement employed for meas- 
 uring, consists of a metallic piece, A, fixed on a small board, C, 
 and on one of its sides there is the system of platinum disks 
 and carbons shown in Fig. 28. A rigid piece, G, furnished 
 with a socket, serves as the external support of the system, and 
 into this socket is introduced the tapering end of some sub- 
 stance which is readily affected by heat, moisture, or barome- 
 tric pressure. The other extremity is supported by another 
 socket, I, fitted to a screw-nut, H, which may be more or less 
 tightened by a regulating screw. If this system is introduced 
 into a galvanometric circuit, a, >, c, i, g, provided with all the 
 instruments of the electric scale of measure, the variations in 
 length of the substance inserted are translated by greater or 
 less deviations of the galvanometric needle, which follow from 
 the differences of pressure resulting from the lengthening or 
 shortening of the surface capable of expansion which is inserted 
 in the circuit. 
 
 The experiments on the microphone made in London at the 
 
EFFECTS OF THE MICROPHONE. 
 
 171 
 
 meeting of the Society of Telegraphic Engineers on May 25th, 
 1878, were wonderfully successful, and they were the subject 
 of an interesting article in the Engineer of May 31st, which as- 
 serts that the whole assembly heard the microphone speak, and 
 
 that its voice was very' like that of the phonograph. When 
 the meeting was informed that these words had been uttered 
 at some distance from the microphone, the Duke of Argyll, 
 
172 THE TELEPHONE. 
 
 who was present, while admiring the important discovery, could 
 not help exclaiming that this invention might have terrible 
 consequences, since, for instance, if one of Professor Hughes's 
 instruments were placed in the room in Downing Street, in 
 which Her Majesty's ministers hold their cabinet council, their 
 secrets might be heard in the room in which the present meet- 
 ing took place. He added that if one of these little instru- 
 ments were in the pocket of Count Schouvaloff, or of Lord 
 Salisbury, we should at once be in possession of the secrets for 
 which all Europe was anxiously waiting. If these instruments 
 were able to repeat all the conversations held in the room in 
 which they stood, they might be really dangerous, and the 
 Duke thought that Professor Hughes, who had invented such 
 a splendid yet perilous instrument, ought next to seek an anti- 
 dote for his discovery. Dr. Lyon Playfair, again, thought that 
 the microphone ought to be applied to the aerophone, so that, 
 by placing these instruments in the two Houses of Parliament, 
 the speeches of great orators might be heard by the whole 
 population within five or six square miles. 
 
 The experiments lately made with the microphone at Halifax 
 show that the Duke of Argyll's predictions were fully justified. 
 It seems that a microphone was placed on a pulpit-desk in a 
 church in Halifax, and connected by a wire about two miles 
 long with a telephone placed close to the bed of a sick person, 
 who was able to hear the prayers, the chanting, and the sermon. 
 This fact was communicated to me by Mr. Hughes, who heard 
 it from a trustworthy source, and it is said that seven patients 
 have subscribed for the expense of an arrangement by which 
 they may hear the church services at Halifax without fatigue. 
 
 The microphone has also lately been applied to the transmis- 
 sion of a whole opera, as we learn from the following account 
 in the Journal Telegraphique, Berne, July 25th, 1878 : 
 
 "A curious micro -telephonic experiment took place on 
 June 19th at Bellinzona, Switzerland. A travelling company 
 
EXPERIMENT AT BELLINZONA. 173 
 
 of Italian singers was to perform Donizetti's opera, "Don Pas- 
 quale," at the theatre of that town. M. Patocchi, a telegraphic 
 engineer, took the opportunity of making experiments on the 
 combined effects of Hughes's carbon microphone as the send- 
 ing instrument, and Bell's telephone as the receiver. With 
 this object he placed a Hughes microphone in a box on the 
 first tier, close to the stage, and connected it by two wires, 
 from one to half a millimetre in thickness, to four Bell re- 
 ceivers, which were placed in a billiard-room above the vesti- 
 bule of the theatre, and inaccessible to sounds within the thea- 
 tre itself. A small battery of two cells, of the ordinary type 
 used in the Swiss telegraphic service, was inserted in the cir- 
 cuit, close to the Hughes microphone. 
 
 " The result was completely successful. The telephones ex- 
 actly reproduced, with wonderful purity and distinctness, the 
 instrumental music of the orchestra, as well as the voices of the 
 singers. Several people declared that they did not lose a note 
 of either, that the words were heard perfectly ; the airs were 
 reproduced in a natural key, with every variation, whether 
 piano or forte, and several amateurs assured M. Patocchi that 
 "by listening to the telephone they were able to estimate the 
 musical beauty, the quality of the singers' voices, and the gen- 
 eral effect of the piece, as completely as if they had been 
 among the audience within the theatre. 
 
 " The result was the same when resistances equivalent to ten 
 kilometres were introduced into the circuit, without increasing 
 the number of cells in the battery. We believe that this is 
 the first experiment of the kind which has been made in Eu- 
 rope, at least in a theatre, and with a complete opera; and 
 those who are acquainted with the delicacy and grace of the 
 airs in " Don Pasquale " will be able to appreciate the sensi- 
 tiveness of the combined instruments invented by Hughes and 
 Bell, which do not suffer the most delicate touches of this 
 music to be lost." 
 
174 THE TELEPHONE. 
 
 Although experiments with the microphone are of such re- 
 cent date, they have been very various, and among other curi- 
 ous experiments we learn from the English newspapers that 
 the attempt has been made to construct an instrument on the 
 same principle as the telephone, which shall be sensitive to the 
 variations of light. It is known that some substances, and 
 particularly selenium, are electrically affected by light, that is, 
 that their conductivity varies considerably with the greater or 
 less amount of light which is shed upon them. If, therefore, 
 a circuit in which a substance of this nature is inserted is ab- 
 ruptly subjected to a somewhat intense light, the increase of 
 resistance which results from it ought to produce a powerful 
 sound in a telephone inserted in the circuit. This fact has 
 been verified by experiment, and Mr. Willoughby Smith infers 
 from it, as we have already suggested, that the effects produced 
 in the microphone are due to variations of resistance in the 
 circuit, which are produced by more or less close contacts be- 
 tween imperfect conductors. 
 
 In order to obtain this effect under the most favorable con- 
 ditions, Mr. Siemens employs two electrodes, consisting of net- 
 work of very fine platinum wire, fitting into each other like 
 two forks, of which the prongs are interlaced. These elec- 
 trodes are inserted between two glass plates, and a drop of 
 selenium, dropped in the centre of the two pieces of network, 
 connects them on a circular surface large enough to establish 
 sufficient conductivity in the circuit. It is on this flattened 
 drop that the ray of light must be projected. 
 
 APPLICATIONS OF THE MICROPHONE. 
 
 The applications of the microphone increase in number 
 every day, and in addition to those of which we have just 
 spoken there are others of really scientific and even of practi- 
 cal interest. Among the number is the use which can be made 
 of it as a system of relays for telegraphy, in science for the 
 
APPLICATIONS OF THE MICROPHONE. 175 
 
 study of vibrations imperceptible to our senses, in medicine 
 and surgery, and even in manufactures. 
 
 Its Application to Scientific Research. We have seen that 
 several physicists, including Messrs. Spottiswoode, Warwick, 
 Rossetti, Canestrelli, Wiesendanger, Lloyd, Millar, Buchin, and 
 Blyth, have been able to hear what is said in a telephone 
 which has no iron diaphragm, but it was so difficult to estab- 
 lish the fact that it has been often disputed. More certain 
 evidence was desirable, and the microphone is an opportune 
 agent for affording it. 
 
 The Telegraphic Journal of September 1st, 1878, observes 
 that M. du Moncel, in order to claim the victory in his con- 
 troversy with Colonel Navez, had still to show that the sounds 
 which appeared to be inarticulate in telephones without a dia- 
 phragm might become intelligible if they were intensified. 
 This has been done for him by the use of Mr. Hughes' s micro- 
 phone, and the following experiments w r ere made for the pur- 
 pose: 
 
 1. If a magnetizing coil, surrounding a bar of soft iron, is 
 inserted in the circuit of a microphone, with a battery of three 
 cells, the ticking of a watch and other sounds of the same 
 kind may be heard on approaching the ear to the electro-mag- 
 net which has been thus constituted. It is true that these 
 sounds are very faint when they are not amplified, but if the 
 electro - magnet is fastened to a board, and a second micro- 
 phone is fixed to the same board, the sounds produced by the 
 electro-magnet are magnified, and become distinctly audible in 
 the telephone which is placed in connection with this second 
 microphone. 
 
 2. These sounds may be further amplified by resting one of 
 the extremities of the core of the electro-magnet on one of the 
 poles of a permanent magnet, which is fixed upon the board. 
 Articulate speech may then be heard in the telephone which 
 is placed in connection with the microphone resting on the 
 
176 THE TELEPHONE. 
 
 board, and the point at issue between MM. Navez and Du 
 Moncel is completely decided in this way : for the auxiliary 
 microphone can only propagate and amplify the vibration of 
 articulate sounds, which are communicated by the bar magnet 
 of the coil to the board on which the two instruments are 
 placed. In this way it would be possible to render articulate 
 sounds perceptible to M. Navez, when transmitted by the bar 
 magnet of a telephone without a diaphragm. 
 
 3. When a second bar magnet rests on the free pole of the 
 electro-magnet, so as to present to it a pole of the same nat- 
 ure as the one with which it is already in communication in 
 a word, if a bar is placed between the two poles of a horseshoe 
 electro-magnet, the effects are still more marked, and hence it 
 may be assumed that the bar reacts as an armature, by concen- 
 trating the lines of magnetic force in the vicinity of the helix. 
 
 4. When the two poles of a horseshoe magnet are inserted 
 together inside a coil, their effects are equally energetic, al- 
 though by this arrangement one of the poles might be expect- 
 ed to neutralize the effect of the other; but the most important 
 effects have been obtained by placing an armature of soft iron 
 across the poles of the magnet which has been already inserted 
 in the coil. Under these conditions articulate sounds are dis- 
 tinctly heard. 
 
 These experiments were confirmed by Mr. F. Varley, in a let- 
 ter published in the Telegraphic Journal of September 15th, 
 1878, and among the fresh experiments mentioned by him we 
 will quote those which he made with an iron tube inserted in a 
 helix, in which the two opposite poles of two bar magnets are 
 introduced. These poles are only separated from each other 
 by the interval of an inch, so that the centre of the iron tube 
 may be strongly magnetized. 
 
 Mr. Varley says that this last arrangement reproduces the 
 articulate sounds which issue from a sending microphone, and 
 this experiment is more decisive than that of Professor Hughes ; 
 
HICROPHOXIC RELAYS. 177 
 
 in which case it might be supposed that the bar magnet, rest- 
 ing on the polar end of an electro-magnetic bar, was only a 
 modification of the disk in the Bell telephone, set in vibration 
 by the alternate currents passing through the helix, and that 
 these vibrations were communicated to the board, and became 
 sensible when enlarged by the microphone. But such an ob- 
 jection cannot be alleged in the case of the arrangement de- 
 scribed above, for since the sound is produced between the cur- 
 rent passing into the helix and the magnetic current of the bar, 
 it can only be the result of a vibration produced by a disturb- 
 ance of the reciprocal relations subsisting between these two 
 elements. Mr. Varley adds that these experiments confirm M. 
 du Mon eel's researches, which have thrown considerable light 
 upon the causes which are at work in the action of the speak- 
 ing telephone, and with which we have hitherto been imper- 
 fectly acquainted. 
 
 Its Application to Telephonic Relays. In February, 1878, 1 
 first began to consider the mode of forming telephonic relays, 
 but I was checked by the discovery that there was no vibration 
 in the receiving telephone, and I made the following communi- 
 cation on the subject to the Academic des Sciences on February 
 25th : "If the vibrations of the disk in the receiving telephone 
 were the same as those of the sending telephone, it is easy to 
 see that if a telephone with a local battery, acting both as 
 sender and receiver, were substituted for the receiving tele- 
 phone, it might, by the intervention of the induction coil, act 
 as a relay, and might therefore not only amplify the sound, 
 but also transmit it to any distance. It is, however, doubtful 
 whether the vibrations of the two corresponding disks are of 
 the same nature, and if the sound be due to molecular contrac- 
 tions and expansions, the solution of the problem becomes much 
 more difficult. Here is, therefore, a field for experiments." 
 These experiments have been successfully made by Mr. Hughes, 
 who acquainted me with them early in June, 1878, and they 
 
 8* 
 
178 THE TELEPHONE. 
 
 led to the discovery of a most interesting system of microphonic 
 relays. 
 
 On a wooden board of moderate size, such as a drawing- 
 board, he placed a microphone with a carbon brought to a fine 
 point at each end, and fixed in a vertical position. One or more 
 telephones were placed in the circuit, with their membranes 
 facing the board, and a continuous sound was heard, sometimes 
 resembling a musical note, sometimes the singing of boiling wa- 
 ter in an oven ; and the sound, which could be heard at a distance, 
 went on indefinitely, as long as the electric force was exerted. 
 Mr. Hughes explains this phenomenon in the following way : 
 
 The slightest shock which affects the microphone has the 
 effect of sending currents, more or less broken, through the 
 telephones, which transform them into sound vibrations, and 
 since these are mechanically transmitted by the board to the 
 microphone, they maintain and even amplify its action, and 
 produce fresh vibrations on the telephones. Thus a fresh 
 action is exerted on the microphone, and so on indefinitely. 
 Again, if a second microphone, in connection with another tele- 
 phonic circuit, be placed upon the same board, we have an in- 
 strument which acts as a telephonic relay, that is, it transmits 
 to a distance the sounds communicated to the board, and these 
 sounds may serve either as a call, or as the elements of a mes- 
 sage in the Morse code, if a Morse manipulator is placed in the 
 circuit of the first microphone. Mr. Hughes adds that he has 
 made several very successful experiments with this system of 
 instruments, although he only employed a Daniell battery of 
 six cells without any induction coil. By fastening a pasteboard 
 tube, forty centimetres in length, to the receiving telephone, he 
 was able to hear in all parts of a large room the continuous 
 sound of the relay, the ticking of a watch, and the scratching 
 of a pen upon paper. He did not try to transmit speech, since 
 it would not have been reproduced with sufficient distinctness 
 under such conditions. 
 
STETHOSCOPIC MICROPHONE. 179 
 
 Since this first attempt, Mr. Hughes has arranged another 
 and still more curious system of microphonic relays, for which 
 two microphones with vertical carbons are required. He places 
 two microphones of this description on a board, and connects 
 one of them with a third microphone, which acts as a sender, 
 while the second is in communication with a telephone and a 
 second battery : in this way the words uttered before the sen- 
 der are heard in the telephone, without employing any electro- 
 magnetic organ for the telephonic relay. 
 
 In August, 1878, Messrs. Houston and Thomson likewise ar- 
 ranged a system of telephonic relays, which only differs from 
 that of Mr. Hughes in the particular of having the microphone 
 fixed on the diaphragm of the telephone, and not on the board 
 beside it. The system consists of three vertical microphones, 
 which can be combined for tension or quantity, according to 
 the conditions for which they are required. The model of 
 this instrument was represented in the Telegraphic Journal of 
 August 15th, 1878, to which we must refer our readers, if they 
 wish for further information on the subject. 
 
 Its Application to Medicine and Surgery. The extreme 
 sensitiveness of the microphone suggested its use for the ob- 
 servation of sounds produced within the human body, so that 
 it might serve as a stethoscope for listening to the action of 
 the lungs and heart. Dr. Richardson and Mr. Hughes are now 
 busy in the attempt to carry out this idea, but so far the result 
 is not very satisfactory, although they still hope to succeed. 
 Meanwhile, M. Ducretet has made a very sensitive stethoscopic 
 microphone, which we represent in Fig. 51. It consists of a 
 carbon microphone, C P, with a simple contact, of which the 
 lower carbon, P, is fitted to one of M. Marais's tambourines 
 with a vibrating membrane, T. This tambourine is connected 
 with another, T', by a caoutchouc tube, which is to be applied 
 to the different parts of the body which demand auscultation, 
 and which is therefore termed the tambour explorateur. The 
 
180 
 
 THE TELEPHONE. 
 
 sensitiveness of the instrument is regulated by means of a 
 counterpoise, P O, which is screwed upon the arm of a bent 
 lever, and to this the second carbon, C, is fixed. The extreme 
 
 FIG. 51. 
 
 sensitiveness of M. Marais's tambourines in transmitting vibra- 
 tions is well known, and since their sensitiveness is further in- 
 creased by the microphone, the instrument becomes almost too 
 impressionable, since it reveals all sorts of sounds, which it is 
 difficult to distinguish from each other. Such an instrument 
 can only be of use when intrusted to experienced hands, and a 
 special education of the organ of hearing is needful, in order 
 to turn it to account. 
 
ITS USE IN SURGERY. 181 
 
 In a work lately published by M. Giboux, on the applica- 
 tion of the microphone to medicine, this stethoscopic system is 
 rather severely criticised, and not without reason, if, as M. Gi- 
 boux asserts, it is only sensitive to the movements which takes 
 place on the surface of the body, and those which are internal 
 are either lost or altogether changed in character. But with- 
 out pronouncing on the improvements which may ultimately 
 be made in the instrument, M. Giboux thinks that its most im- 
 portant use in medical practice consists in its allowing a cer- 
 tain number of students to observe, with the professor, the dif- 
 ferent sounds of the body, to study them with him in their dif- 
 ferent phases, and thus to profit more readily by his teaching. 
 A microphonic circuit might bifurcate between several tele- 
 phones, so that each person might hear for himself what is 
 heard by others. 
 
 The most important application of the instrument to surgical 
 purposes has lately been made by Sir Henry Thomson, aided 
 by Mr. Hughes, for the examination of the bladder in cases of 
 stone. It enables him to ascertain the presence and precise 
 position of calculi, however small they may be. For the pur- 
 pose of research, he uses a sound, made of a Maillechort rod, a 
 little bent at the end, and placed in communication with a sen- 
 sitive carbon microphone. When the sound is moved about 
 in the bladder, the rod comes in contact with stony particles, 
 even if they are no larger than a pin's head, and friction ensues, 
 producing in the telephone vibrations which can be easily dis- 
 tinguished from those caused by the simple friction of the rod 
 on the soft tissues of the sides of the bladder. The arrange- 
 ment of the instrument is shown in Fig. 52. The microphone 
 is placed in the handle which contains the sound, and is the 
 same as that given in Fig. 42, but of smaller size, and the two 
 conducting wires, e, which lead to the telephone, issue from the 
 handle by the end, a, opposite to that, bb, to which the sound, 
 dd, is screwed. As this instrument is not intended to repro- 
 
182 
 
 THE TELEPHONE. 
 
 duce speech, retort carbons instead of wood carbons may be 
 used. 
 
 Some deaf people, whose sense of hearing is not completely 
 destroyed, have been able to hear by an expedient 
 based upon the principle of the microphone. For 
 this purpose two telephones, connected by a me- 
 tallic crown, which is placed on the temples, are 
 applied to the ears of the deaf person, and the 
 telephones are placed in communication with a 
 battery microphone, which hangs to the end of 
 a double conducting wire. The deaf man keeps 
 the microphone in his pocket, and presents it as 
 an acoustic tube to the person who wishes to con- 
 verse with him. Mr. Hughes's speaker, repre- 
 sented by Fig. 42, is the one used. 
 
 Various Applications. The microphone may 
 be used in many other ways, some of which are 
 suggested in the English Mechanic of June 21st, 
 1878. The article states that, by means of this 
 instrument, engineers will be able to estimate the 
 effects of the vibrations caused on old and new 
 buildings by the passage of heavy loads ; a sol- 
 dier will be able to discover the enemy's ap- 
 proach when he is several miles off, and may 
 even ascertain whether he has to do with artil- 
 lery or cavalry ; the approach of ships to the 
 neighborhood of torpedoes may be automatically 
 heralded on the coast by this means, so that an 
 explosion may be produced at the right moment. 
 
 It has also been proposed to use the microphone to give 
 notice of an escape of gas in coal-mines. The gas, in escaping 
 from between the seams of coal, makes a whistling noise, which 
 might, with the aid of the microphone and telephone, be heard 
 at the top of the shaft. Again, it has been suggested that the 
 
 FIG. 52. 
 
DISTURBING INFLUENCES. 183 
 
 microphone might be used as a seismograph to reveal the sub- 
 terranean noises which generally precede earthquakes and vol- 
 canic eruptions, and which would be much intensified by this 
 instrument. It might even be of use to Signor Palmieri for 
 his observations in the Vesuvius Observatory. 
 
 The microphone has also been used by Mr. Chandler Roberts 
 to render the diffusion of gaseous molecules through a porous 
 membrane sensible to the ear. 
 
 As might have been expected, the acclamation with which 
 Mr. Hughes' s invention was received led to the assertion of 
 
 O 
 
 other claims to priority, and in addition to that of Mr. Edison, 
 on which we have already given our opinion, there are several 
 others, showing that if some microphonic effects were discover- 
 ed at different times before the date of Mr. Hughes' s discovery, 
 they could not have been considered important, since they were 
 not even announced. Among the number was that of Mr. 
 AVentworth Lascelles Scott, specified in the Electrician of May 
 25th, 1878, and that of M. Weyher, presented to the Societe de 
 Physique, Paris, in June, 1878. Another, made by M. Dutertre, 
 is of somewhat greater importance, for his experiments were 
 reported in the Rouen papers in February of the same year: 
 yet there is no just ground for such claims, since the earliest 
 date of his experiments is subsequent to the experiments first 
 made by Mr. Hughes. These began early in December, 1877, 
 and in January, 1878, they were exhibited to officials of the 
 Submarine Telegraph Company, as Mr. Preece declared in a 
 letter addressed to the several scientific men. 
 
 EXTERXAL IXFLUEXCE OX TELEPHOXIC TRAXSMISSIOXS. 
 
 The obstacles which occur in telephonic transmissions pro- 
 ceed from three causes: 1. The intensity of sound is diminish- 
 ed by the loss of current in transmission a loss which is much 
 greater in the case of induced currents than in those received 
 from a battery. 2. Confusion is caused by the influence of ad- 
 
184 THE TELEPHONE. 
 
 jacent currents. 3. The induction from one wire to another. 
 This last influence is much greater than is usually supposed. 
 If two perfectly insulated wires are placed side by side, one in 
 communication with the circuit of an electric bell, and the 
 other with the circuit of a telephone, the latter will repeat the 
 sounds of the bell with an intensity often great enough to act 
 as a call without applying the instrument to the ear. MM. 
 Pollard and Gamier, in their interesting experiments with the 
 induced currents of the Ruhmkorff coil, have ascertained that 
 in this way not merely sounds may be obtained which corre- 
 spond with the induced currents resulting from the action of 
 the primary current, but also those which result from the action 
 of the secondary current on other helices, which are termed 
 currents of the second order. These different reactions fre- 
 quently cause the telephonic transmissions made on telegraphic 
 lines to be disturbed by irregular sounds, arising from the 
 electric transmissions on adjoining lines ; but it does not ap- 
 pear that these influences altogether neutralize each other, so 
 that conversation held in the ordinary way, and a message sent 
 in the Morse code, may be heard simultaneously. 
 
 At the artillery school, Clermont, a telephonic communica- 
 tion has been established, for the sake of experiments, between 
 the school and the butts, which are at a distance of about eight 
 miles. Another communication of the same kind has been es- 
 tablished between the Clermont Observatory and the one at 
 Puy-de-D6me, which is nearly nine miles from the former. 
 These two lines are carried on the same posts for a course of 
 six miles, together with an ordinary telegraphic wire, and for a 
 distance of 330 yards there are seven other such wires. The 
 two telephonic wires are ssparated from each other by a space 
 of eighty-five centimetres. The following facts have been ob- 
 served under these conditions : 
 
 1. The school telephone is perfectly able to read off from 
 their sound the Morse messages which pass through the two ad- 
 
TELEPHONIC CIRCUITS. 185 
 
 jacent telegraph wires, and the ticking of the instrument does 
 not at all interfere with the vocal communication of the tele- 
 phone, nor render it inaudible. 
 
 2. The two adjacent telegraphic lines, although not in con- 
 tact, confuse their messages together, and it has sometimes been 
 possible to hear messages from Puy-de-D6me at the school 
 through the wire which runs to the butts, although the distance 
 between the two lines is nowhere less than eighty-five cen- 
 timetres. 
 
 These inconveniences have been in some degree remedied by 
 inserting strong resistances in the circuit, or by putting the 
 current to earth at some distance from the telephonic stations. 
 
 M. Izarn, Professor of Physics at the Lycee, Clermont, holds 
 that telephonic electric currents may readily be turned aside 
 by the earth, especially if in the course of their passage they 
 encounter metallic conductors, such as gas or water-pipes. He 
 writes as follows on the subject, in a paper addressed to the 
 Academic des Sciences, on May 13th, 1878: "I set up a tele- 
 phone in the Clermont Lycee with a single wire, more than 
 fifty yards in length, which crosses the court-yard of the Lycee, 
 and goes from the laboratory, where it is suspended to a gas- 
 burner, to a room near the porter's lodge, where it is suspended 
 to another gas-burner. When I applied my ear to the tele- 
 phone, I could distinctly hear the telegraphic signals, Morse or 
 otherwise, which came either from the telegraph office at Cler- 
 mont, or from the telephone office which was at work between 
 the School of Artillery and the butts below Puy-de-D6me, a 
 distance of eight miles. I could overhear words, and especially 
 the military orders issued at the butts for the purpose of being 
 heard at the school. Yet my wire is perfectly independent of 
 those used for signalling, and is even very remote from them ; 
 but as the wires of the telegraph office and of the School of 
 Artillery go to earth at a little distance from the gas-pipes, it 
 is probable that this phenomenon is caused by a diversion of 
 
186 THE TELEPHONE. 
 
 the current produced in my wire, by means of the earth and 
 the network of metal pipes." 
 
 Mr. Preece made the same remark in his notice of " some 
 physical points connected with the telephone." Again, we 
 read in the Telegraphic Journal of June 15th, 1878, that in a 
 telephonic concert, transmitted from Buffalo to New York, the 
 singers at Buffalo were heard in an office placed outside the 
 telegraphic circuit in which the transmission was effected. On 
 inquiry, it was ascertained that the wire through which the 
 telephonic transmission took place was at one point in its 
 course close to the one which directly transmitted the musical 
 sounds, but the distance between the two wires was not less 
 than ten feet. 
 
 When the circuits are altogether metallic there is much less 
 risk of confusion, and M. Zetzche declares that sounds proceed- 
 ing from other wires are in this case little heard, and then only 
 momentarily, so that it is much more easy to hear with this ar- 
 rangement than with the one in ordinary use. " It is not," he 
 says, " the resistances of the wire, but rather the diversions of 
 the current near the posts, which interfere with telephonic cor- 
 respondence on long lines above ground. This was proved by 
 the following experiments : I connected the telegraphic line 
 from Dresden to Chemnitz with a line from Chemnitz to Leip- 
 sic (fifty-four miles), which made a circuit of one hundred and 
 three miles, going to earth at its two extremities. There was 
 no communication between Dresden and Leipsic, but Leipsic 
 and Dresden could communicate with ease, in spite of the 
 greater extent of line. I broke the connection with earth, 
 first at Leipsic, then simultaneously at Leipsic and Dresden, 
 and I observed the following effects: When insulation took 
 place at Leipsic only, the telephone could be heard at the sta- 
 tions of Dresden, Riesa, and Wurzen ; when the line was in- 
 sulated at both ends, the communication was good between the 
 two latter stations, but it was observed that at the intermediate 
 
TELEPHONIC CIRCUITS. 187 
 
 station the words spoken at Wurzen were more distinctly 
 heard than the words spoken at Riesa were heard at Wurzen. 
 Since the distance from AVurzen to Leipsic is little more than 
 half that from Riesa to Dresden, there are consequently nearly 
 twice as many posts on the latter line, which carry the currents 
 to earth, and hence I conclude that these diversions of current 
 explain the possibility of conversing on an insulated line, and 
 also why sounds are more distinctly heard at the Riesa station 
 in consequence of the greater intensity of current still remain- 
 ing on the line." 
 
 Some vibrations also result from the action of currents of 
 air on telegraphic wires, which produce the humming sound so 
 well known on some lines, and these may also react on the tel- 
 ephone ; but they are in this case generally mechanically trans- 
 mitted, and they may be distinguished from the others, if the 
 sounds which ensue are heard after the telephone is excluded 
 from the circuit by a break with a short circuit, and after the 
 communication to earth established behind the telephone has 
 been broken. 
 
 The induced reactions caused by the line wires on each oth- 
 er are not the only ones which may be observed on a tele- 
 phonic circuit : every manifestation of electricity near a tele- 
 phone may produce sounds of greater or less force. Of this 
 we have already given a proof in M. d'Arsonval's experiments, 
 and others by M. Demoget demonstrate the fact still more 
 clearly. In fact, if a small bar magnet provided with a vibra- 
 tor be placed before one of the telephones of a telephonic cir- 
 cuit, and the vibrating plate of the telephone be removed, in 
 order to draw away the sound produced by the vibrator, its 
 humming noise may be distinctly heard on the second tele- 
 phone of the circuit ; a noise which attains its maximum when 
 the two extremities of the electro-magnet are at their nearest 
 point to the telephone without a diaphragm, and it is at its 
 minimum when this electro-magnet is presented to it along its 
 
188 THE TELEPHONE. 
 
 neutral line. M. Demoget supposes that the action which is 
 exerted in this instance is that of a magnet exerting two in- 
 ducing actions which are opposite and symmetrical, with a 
 field limited by a double paraboloid, and with an axis, accord- 
 ing to his experiments, which extended fifty -five centimetres 
 beyond the magnetic core, and a vertical diameter of sixty 
 centimetres. He believes that in this way it would be easy to 
 telegraph on the Morse system, and that, in order to do so, it 
 would only be necessary to apply a key to the inducing elec- 
 tro-magnet. 
 
 Mr. Preece points out three ways of overcoming the diffi- 
 culty presented by the induced reactions caused by the wires 
 on each other : 
 
 1. By increasing the intensity of the transmitted currents, 
 so as to make them decidedly stronger than the induced cur- 
 rents, and to reduce the sensitiveness of the receiving tele- 
 phone. 
 
 2. To place the telephonic wire beyond the range of induc- 
 tion. 
 
 3. To neutralize the effects of induction. 
 
 The first mode may be effected by Edison's battery system, 
 and we have seen that it is very successful. 
 
 In order to put the second mode in practice, Mr. Preece says 
 that it would be necessary to study the two kinds of induction 
 which are developed on telegraphic lines : electro-static induc- 
 tion, analogous to that produced on submarine cables, and elec- 
 tro-dynamic induction, resulting from electricity in motion. 
 In the former case, Mr. Preece proposes to interpose between 
 the telephone wire and the other wires a conducting body in 
 communication with the earth, capable of becoming a screen 
 to the induction by itself absorbing the electro-static effects. 
 He says that this might be accomplished by surrounding the 
 telegraphic wires adjacent to the telephonic wire with a metal- 
 lic envelope, and then plunging them in water. He adds that 
 
EFFECTS OF INDUCTION. 189 
 
 tbe effects of static induction are not completely destroyed in 
 tins way, since tbe substance used is a bad conductor, but tbey 
 are considerably reduced, as be lias proved by experiments be- 
 tween Dublin, Holybead, Manchester, and Liverpool. In tbe 
 second case, Mr. Preece admits tbat an iron envelope might 
 paralyze tbe electro -dynamic effects produced by absorbing 
 them, so that if insulated wires were employed, covered with 
 an iron case, and communicating with the earth, the two in- 
 duced reactions would be annulled. We will not follow Mr. 
 Preece in his theory as to these effects a theory which seems 
 to us open to question, but we content ourselves with pointing 
 out his proposed mode of attenuation. 
 
 In order to carry out the third expedient, it might be 
 thought that it would be enough to employ a return wire in- 
 stead of going to earth, for under such conditions the currents 
 induced on one of the w 7 ires would be neutralized by those re- 
 sulting from the same induction on the second wire, which 
 would then act in an opposite direction ; but this mode would 
 only be successful when there is a very small interval between 
 the two telephone wires, and they are at a considerable distance 
 from the other wires. AVhen this is not the case, and they are 
 all close together, as in submarine or subterranean cables, con- 
 sisting of several wires, this mode is quite inefficient, A small 
 cable, including two conductors, insulated with gutta-percha, may 
 be successfully carried through the air. 
 
 The use of two conductors has the further advantage of 
 avoiding the inconvenience of stray currents on the line and 
 through the earth, which, when the communications to earth 
 are imperfect, permit the line current to pass more or less easily 
 into tbe telephonic line. 
 
 In addition to the disturbing causes in telephonic transmis- 
 sion we have just mentioned, there are others which are also 
 very appreciable, and among them are the accidental currents 
 which are continually produced on telegraphic lines. These 
 
190 THE TELEPHONE. 
 
 currents may proceed from several causes at one time, from at- 
 mospheric electricity ; at another, from terrestrial magnetism ; at 
 another, from thermo-electric effects produced upon the lines ; at 
 another, from the hydro-electric reactions produced on the wires 
 and disks in communication with the earth. These currents 
 are always very unstable, and consequently they are likely, by 
 reacting on the transmitted currents, to modify them so as to 
 produce sounds upon the telephone. Mr. Preece asserts that 
 the sound proceeding from earth currents somewhat resembles 
 that of falling water. The discharges of atmospheric elec- 
 tricity, even when the storm is remote, produce a sound which 
 varies with the nature of the discharge. When it is diffused 
 and the clap takes place near at hand, Dr. Channing, of Provi- 
 dence, United States, says that the sound resembles that pro- 
 duced by a drop of fused metal when it falls into water, or, 
 still more, that of a rocket discharged at a distance : in this 
 case it might seem that the sound would be heard before the 
 appearance of the flash, which clearly shows that the electric 
 discharges of the atmosphere only take place in consequence of 
 an electric disturbance in the air. Mr. Preece adds that a wail- 
 ing sound is sometimes heard, which has been compared to 
 that of a young bird, and which must proceed from the in- 
 duced currents which terrestrial magnetism produces in the 
 metallic wires when placed in vibration by currents of air. 
 
 M. Gressier, in a communication made to the Academic des 
 Sciences on May 6th, 1878, has spoken of some of these sounds, 
 but he is totally mistaken in the source to which he ascribes 
 them. 
 
 " In addition to the crackling sound caused by the working 
 of telegraph instruments on the adjacent lines, a confused mur- 
 mur takes place in the telephone, a friction so intense that it 
 might sometimes be thought that the vibrating disk was split- 
 ting. This murmur is heard more by night than by day, and 
 is sometimes intolerable, since it becomes impossible to under- 
 
EFFECTS OF HEAT AND MO1STUHE. 191 
 
 stand the telephone, although nothing is going on in the office 
 to disturb the sound. The same noise is heard when only one 
 telephone is used. A good galvanometer inserted in the cir- 
 cuit reveals the presence of sensible currents, sometimes in one 
 direction, sometimes in another." 
 
 I studied these currents for a long time with the galvanome- 
 ter, and made them the subject of four papers which were laid 
 before the Academic des Sciences in 1872, and I am convinced 
 that they have in general nothing to do with atmospheric elec- 
 tricity, but result either from thermo-electric or hydro-electric 
 influence. They take place constantly and in all weathers on 
 telegraph lines, whether these lines are insulated at one end, or 
 in contact with the earth at both ends. In the first case, the 
 polar electrodes of the couple are formed by the telegraph wire 
 and the earth plate, generally of the same nature, and the in- 
 termediate conducting medium is represented by the posts 
 which support the wire and the earth which completes the 
 circuit. In the second case, the couple is formed in almost the 
 same way, but the difference in the chemical composition of 
 the ground at the two points where the earth plates are buried, 
 and sometimes their different temperature, exert a strong influ- 
 ence. If only the first case be considered, it generally happens 
 that on fine summer days the currents produced during the 
 day are inverse to those which are produced by night, and vary 
 with the surrounding temperature in one or the other direction. 
 The presence or absence of the sun, the passage of clouds, the 
 currents of air, involve abrupt and strongly marked variations, 
 which may be easily followed on the galvanometer, and which 
 cause more or less distinct sounds in the telephone. 
 
 During the day the currents are directed from the telegraph 
 line to the earth plate, because the heat of the wire is greater 
 than that of the plate, and these currents are then thermo- 
 electric. During the night, on the other hand, the wire is cool- 
 ed by the dew, which causes a greater oxidation on the wire 
 
192 THE TELEPHONE. 
 
 than that which takes place on the plate, and the currents then 
 become hydro-electric. 
 
 I say more about these currents, because, in consequence of 
 a mistaken belief as to their origin, it has been supposed that 
 the telephone might serve for the study of the variations of 
 the atmospheric electricity generally diffused through the air. 
 Such an application of the telephone would, under these con- 
 ditions, be not only useless, but also misleading, by inducing 
 the study of very complex phenomena, which could lead to 
 nothing more than I have already stated in my different pa- 
 pers on the subject. 
 
 Certain local influences will also produce sounds in the tele- 
 phone. Thus the distention of the diaphragm by the moist 
 heat of the breath, when the instrument is held before the 
 mouth in speaking, causes a perceptible murmur. 
 
 From the electro - static reactions, so strongly produced on 
 the submarine cables, in consequence of electric transmissions, 
 it might be supposed that it would not be easy to hold tele- 
 phonic correspondence through this kind of conductor, and, to 
 ascertain the fact, an experiment was made on the cable be- 
 tween Guernsey and Dartmouth, a distance of sixty miles. 
 Articulate speech, only a little indistinct, was, however, perfect- 
 ly transmitted. Other experiments, made by Messrs. Preece 
 and Wilmot, on an artificial submarine cable, placed in condi- 
 tions analogous to those of the Atlantic cable, showed that a 
 telephonic correspondence might be kept up at a distance of 
 a hundred miles, although the effects of induction were appar- 
 ent. At the distance of 150 miles it was somewhat difficult 
 to hear, and the sounds were very faint, as if some one were 
 speaking through a thick partition. The sound diminished 
 rapidly until the distance of 200 miles was reached, and after 
 that it became perfectly indistinct, although singing could still 
 be heard. It was even possible to hear through the whole 
 length of the cable, that is, for 3000 miles, but Mr. Preece be- 
 
TELEPHONIC STATION. 193 
 
 lieved this to be due to the induction of the condenser on it- 
 self : he holds, however, that singing may be heard at a much 
 greater distance than speech, owing to the more regular suc- 
 cession of electric waves. 
 
 Mr. Preece also made experiments on the subterranean tele- 
 graphs between Manchester and Liverpool, a distance of thirty 
 miles, and found no difficulty in exchanging correspondence ; 
 and it was the same with the cable from Dublin to Holyhead, 
 a distance of sixty-seven miles. This cable had seven conduct- 
 ing wires, and when the telephone was connected with one of 
 them, the sound was repeated through all the others, but in a 
 fainter degree. "When the currents of the telegraphic instru- 
 ments passed through the wires, the induction was apparent, 
 but not so great as to prevent telephonic communication. 
 
 ESTABLISHMENT OF A TELEPHONIC STATION. 
 
 Although the telephonic system of telegraphy is very sim- 
 ple, yet certain accessory arrangements are indispensable for 
 its use. Thus, for example, an alarum call is necessary, in or- 
 der to know when the exchange of correspondence is to take 
 place, and information that the call has been heard is like- 
 wise necessary. An electric bell is therefore an indispensable 
 addition to the telephone, and since the same circuit may be 
 employed for both systems, if a commutator is used, it was 
 necessary to find a mode of making the commutator act au- 
 tomatically, so as to maintain the simple action of the system 
 which constitutes its principal merit. 
 
 MM. Pollard and Garnier's System. With this object, 
 MM. Pollard and Gamier devised a very successful arrange- 
 ment last March, which employs the weight of the instrument 
 to act upon the commutator. 
 
 For this purpose they suspended the instrument to the end 
 of a spring plate, fastened between the two contacts of the 
 commutator. The circuit wire corresponds with this plate, 
 
 9 
 
194 THE TELEPHONE. 
 
 and the two contacts correspond, the one with the telephone, 
 the other with the bell. When the telephone hangs below the 
 spring-support, that is, when it is not at work, its weight low- 
 ers the spring plate on the lower contact, and the communi- 
 cation of the line with the bell is established : when, on the 
 other hand, the telephone is raised for use, the spring plate 
 touches the higher contact, and communication is established 
 between the line and telephone. In order to make the bell 
 sound, it is only necessary to establish, on the wire which con- 
 nects the line with the bell contact of the commutator, a break- 
 er which can both join and break the current, and which com- 
 municates on one side with the contact of the bell, and on the 
 other with its battery. The ordinary push of an electric bell 
 will be sufficient, if it is supplied with a second contact, but 
 MM. Pollard and Gamier wished to make this action also auto- 
 matic, and consequently they devised the arrangement repre- 
 sented in Fia\ 53. 
 
 FIG. 53. 
 
 In tnis system, as well as in those which have since been 
 devised, two telephones are employed, one of which is con- 
 stantly applied to the ear, and the other to the mouth, so as to 
 
BREGUET AND KOOSEVELT SYSTEM. 195 
 
 make it possible to speak while listening. The telephones are 
 supported by three wires, two of which contain flexible con- 
 ductors, while the third only acts as a support. 
 
 Two of the four wires of the two telephones are connected 
 with each other, and the other two are connected with the two 
 binding screws of the commutator t, t' : the wires without con- 
 ductors are suspended to the extremities of the two flexible 
 plates, /, /', which correspond with earth and line. 
 
 When at rest, the weight of the telephones presses the two 
 plates, /, /', on the lower contacts, S, S', but when the instru- 
 ments are taken up these plates press against the higher con- 
 tacts. 
 
 The two bell wires terminate on the lower contacts, those of 
 the telephones on the higher contacts ; and one of the poles of 
 the battery is connected with the lower contact on the left, S', 
 the other with the higher contact on the right, T. 
 
 When at rest, the system is applied to the electric bell, and 
 the current sent from the opposite station will follow the cir- 
 cuit L I S S' S' /' T, so'that the call will be made. On taking 
 up the two telephones, the circuit of the bell system is broken, 
 and that of the telephones is established, so that the current 
 follows the course L I T 1 1' T' /' T. If only one telephone is 
 held at a time, the current is sent into the bell system of the 
 opposite station, and follows the route + P S I L T /' T' t P . 
 In this way the three actions necessary for calling, correspond- 
 ing, and enabling the corresponding instrument to give a call, 
 are almost involuntarily made. 
 
 System by MM. Breguet and Roosevelt. In the system 
 established by the Paris agents of the Bell company, the. ar- 
 rangement resembles the one just described, except that there 
 is only one spring commutator, and the call is made with the 
 push of an ordinary electric bell. A mahogany board is sus- 
 pended from the wall, and on it are arranged, first, the ordinary 
 electric bell system, with a sending push fixed below it ; second, 
 
196 THE TELEPHONE. 
 
 two forks supporting two telephones, one of which is fastened 
 to the bar of a commutator, arranged as a Morse key. The 
 two telephones are connected by two conducting wires, so ar- 
 ranged as to be capable of extension, and two of their four 
 binding-screws are in immediate connection with each other, 
 and the Other two with the earth, line, and battery, by means 
 of the commutator, the sending push, and the bell system. 
 The arrangement is shown in Fig. 54. 
 
 The commutator A consists of a metallic bar, 0, c, bearing 
 the suspension fork Of one of the telephones, F', below its 
 point of articulation : it ends in two pins, a and c, below 
 which the two contacts of the commutator are fixed, and a 
 spring compresses the lower arm of the bar, so as to cause the 
 other arm to rest constantly on the higher contact. For 
 greater security, a steel tongue, a 6, is fastened to the lower 
 end of the bar, and rubs against the small shaft &, which is 
 provided with two insulated contacts, corresponding to those 
 of the board. The bar is in communication with the line wire 
 by means of the call-push, and the upper of the two contacts 
 we have just described corresponds with one of the telephone 
 wires which is inserted in the same circuit, while the other cor- 
 responds with the bell system, S, which is in communication 
 with earth. It follows from this arrangement, that when the 
 right telephone presses its whole weight on the support, the 
 bar of the commutator is inclined on the lower contact, and 
 consequently the line is in direct communication with the bell, 
 so that the call can be made. When, on the other hand, the 
 telephone is removed from its support, the bar rests on the 
 higher contact, and the telephones are connected with the line. 
 
 Pressure on the sending push serves to call the corresponding 
 station : the connection of the line with the telephones is then 
 broken, and it is established with the battery of the sending- 
 station, which sends its current through the bell of the corre- 
 sponding station. In order to obtain this double effect, the 
 
BREGUET AND ROOSEVELT SYSTEM. 197 
 
 contact spring of the sending push generally rests upon a con- 
 tact fastened to a piece of wood shaped like a joiner's rule, 
 
 FIG. 54. 
 
 which covers it in front, and below this spring there is a second 
 contact, which communicates with the positive pole of the sta- 
 tion battery. The other contact corresponds with the line wire, 
 
198 
 
 THE TELEPHONE. 
 
 FIG. 55. 
 
 and a connection takes place between the earth wire and the 
 negative pole of the station battery, so that the earth wire is 
 common to three circuits : 
 
EDISON'S SYSTEM. 199 
 
 1st. To the telephone circuit; 2d. To that of the bell sys- 
 tem ; 3d. To that of the local battery. 
 
 The second fork, which supports the telephone on the right, 
 is fixed to the board, and is independent of any electric current. 
 
 It is clear that this arrangement may be varied in a thousand 
 ways, but the model we have just described is the most prac- 
 tical. 
 
 Edison's System. The problem becomes more complex in 
 the case of battery telephones, since the battery must be com- 
 mon to both systems, and the induction coil must be inserted 
 in two distinct circuits. Fig. 55 represents the model adopted 
 in Mr. Edison's telephone. 
 
 In this arrangement there is a small stand, C, on the mahog- 
 any board on which the bases of the two telephones rest. The 
 bell system, S, is worked by an electro -magnetic speaker, P, 
 which serves, when a Morse key is added to the system, for ex- 
 change of correspondence in the Morse code, if there should be 
 any defect in the telephones, or to put them in working order. 
 Above the speaker there is a commutator with a stopper, D, to 
 adapt the line for sending or receiving, with or without the bell ; 
 and below the stand, C, the induction coil, destined to transform 
 the voltaic currents into induced currents, is arranged in a small 
 closed box, E. 
 
 When the commutator is at reception, the line is in imme- 
 diate correspondence either with the speaker or with the re- 
 ceiving telephone, according to the hole in which the stopper 
 is inserted ; when, on the other hand, it is at sending, the line 
 corresponds to the secondary circuit of the induction coil. 
 Under these conditions the action is no longer automatic ; but 
 since this kind of telephone can only be usefully employed for 
 telegraphy, in which case those who work it are acquainted 
 with electric apparatus, there is no inconvenience in this com- 
 plication. 
 
200 THE TELEPHONE. 
 
 CALL-BELLS AND ALARUMS. 
 
 The call-bells applied to telegraphic service have been ar- 
 ranged in different ways. When the vibrating bells are in use, 
 like those of which we have just spoken, it is necessary to use 
 a battery, and the advantages offered by telephones with in- 
 duced currents are thus sensibly diminished. In order to dis- 
 pense with the battery, the use of the electro-magnetic bell has 
 been suggested. 
 
 In this case there are usually two bells, with a hammer oscil- 
 lating between them, and a support formed of the polarized ar- 
 mature of an electro-magnet. The electro-magnetic instrument 
 is placed below this system ; it is turned by a winch, and sends 
 the currents, alternately reversed, which are necessary to com- 
 municate the vibratory movement to the hammer, and this 
 movement is enough to make the two bells tinkle. Below the 
 winch of this electro-magnetic instrument there is a commuta- 
 tor with two contacts, which adapts the instrument for sending 
 or receiving. 
 
 M. Mandroux has simplified this system, and has reduced it 
 to small dimensions by the following arrangement : He fixes 
 two magnetic cores, furnished with coils, on each of the two 
 poles of a horseshoe magnet, composed of two bars connected 
 by an iron coupler, and between the poles expanded by these 
 four cores he inserts an armature, within which there is a steel 
 spring fastened to one of these poles. In this way the arma- 
 ture is polarized, and oscillates under the influence of the re- 
 versed currents transmitted by an instrument of the same kind 
 provided with an induction system. These oscillations may 
 have the effect of producing the sound of a call-bell, and the 
 induction system may consist of a manipulating key, fastened 
 to a duplex system of armature, regularly applied to the mag- 
 netic cores, taken in pairs. On communicating a series of 
 movements to this manipulator, a series of induced currents in 
 
WEINH OLD'S SYSTEM. 201 
 
 an inverse direction are produced, which cause the armature of 
 the corresponding station to act as we have already seen, and 
 which may even, when necessary, furnish a series of Morse sig- 
 nals for a suitable manipulation. On account of the small size 
 of this system, it might be applied to the telephonic service of 
 the army. 
 
 The Bell Telephone Company in Paris has arranged another 
 little call-system which is quite satisfactory, and has the ad- 
 vantage of acting as a telephone at4he same time. The model 
 resembles the one we have termed a snuffbox telephone, and 
 it has a button commutator by means of which the instrument 
 is placed in communication with the electro-magnetic system of 
 the instrument, or with a battery which is able to make the 
 telephone vibrate with some force. To make a call, the but- 
 ton must be pressed, and the battery current is communicated 
 to the corresponding instrument, which begins to vibrate when 
 the call is made; and when notice is given of the receipt of 
 the signal, the pressure on the button is removed, and it be- 
 comes possible to speak and receive as in ordinary telephones. 
 
 M. de WeinholcCs System. M. Zetzche speaks highly of an 
 alarum devised by Professor A. de Weinhold, which resembles 
 that by M. Lorenz, represented in Fig. 56. Its organ of sound 
 consists of a steel bell, T, from thirteen to fourteen centimetres 
 in diameter, and toned to give about 420 double vibrations in 
 a second. " Its diameter and tone," he says, " are important, 
 and any great departure from the rule laid down diminishes 
 the effect. The opening of the bell is below, and it is fixed on 
 a stand by its centre. A slightly curved bar magnet, provided 
 at its two ends with iron appendices enclosed in a coil, trav- 
 erses the stand. The bar magnet of the telephone also termi- 
 nates in an iron appendix enclosed in a coil. In both cases 
 the changes produced in the magnetic condition appear to be 
 more intense than they are in magnets without appendices. 
 The bar magnet is placed within the bell in the direction of 
 
 9* 
 
202 
 
 THE TELEPHONE. 
 
 one of its diameters, so that the appendices almost touch its 
 sides. 
 
 " When the bell is struck on a spot about 90 from this 
 diameter with a wooden clapper, M, which acts with a spring, 
 
 FIG. 56. 
 
 and is withdrawn by stretching the spring and then letting it 
 go, as in a bell for the dinner-table, the vibrations imparted 
 to it send currents into the coils, and these currents produce 
 identical vibrations on the iron disk of the telephone, which 
 are intensified by a conical resonator fitted to the telephone, so 
 as to be easily heard some paces off. For ordinary use, the 
 bell coil is broken into a short circuit by means of a metallic 
 spring, R ; and consequently, when the bell is struck, the spring 
 must be opened so as not to break the circuit. An instrument 
 of the same kind has also been devised by Herr W. E. Fein at 
 Stuttsrardt." 
 
DUTERTRE AND GOTJAULT's SYSTEM. 
 
 203 
 
 MM. Dutertre and Gouaulfs System. One of the most in- 
 genious solutions of the problem of making the telephone call 
 has recently been proposed by MM. Dutertre and Gouault. 
 Figs. 57 and 58 represent the opposite faces of the instrument. 
 It consists of a kind of snuffbox telephone, like the one shown 
 in Fig. 26, and it is so arranged as to send or receive the call, 
 according to the way in which it is placed on its stand, which 
 is only an ordinary bracket fastened to the wall. When it is 
 placed on the bracket so as to have the telephone mouth-piece 
 on the outside, it is adapted for receiving, and can then give 
 the call. When, on the other hand, its position on the bracket 
 is reversed, it permits the other station to make the call, by 
 producing vibrations on a vibrator under the influence of a 
 battery, and these vibrations reverberate in the corresponding 
 
 FIG. 57 
 
 FIG. 6S. 
 
 instrument with sufficient force to produce the call. If the in- 
 strument is taken up, and the finger is placed on a small spring 
 button, it may then be used as an ordinary telephone. 
 
 In this instrument the magnet, N S (Fig. 57), is snail-shaped, 
 like others we have mentioned, but the core of soft iron, S, to 
 which the coil E is fastened, can produce two different effects 
 on its two extremities. On the one side, it reacts on a small 
 
204 THE TELEPHONE. 
 
 armature which is fastened to the end of a vibrating disk, C, 
 Fig. 58 ; the armature is placed against a contact fastened to 
 the bridge B, and constitutes an electro-magnetic vibrator. For 
 this purpose the bridge is in metallic communication with the 
 coil wire, of which the other end corresponds with the line 
 wire, and the spring C is mounted on an upright, A, which 
 also supports another spring, D G, acting on two contacts, one 
 placed at G, and corresponding to the earth wire, the other at 
 H, and connected with the positive pole of the battery. A 
 small movable button, which passes through a hole in the lid of 
 the box, and projects beyond it, is fixed at G, and all this part 
 of the instrument faces the bottom of the box. The upper 
 part consists of the vibrating disk and the mouth-piece, so that 
 the mechanism we have described is all mounted on an inner 
 partition forming a false bottom to the box. 
 
 When the box rests upon its base, on the side shown in Fig. 
 58, the button at G presses on the spring D G, and raises it so 
 as to break the connection with the battery ; the coil of the in- 
 strument is then united to the circuit, and consequently receives 
 the transmitted currents, which follow this route : line wire, 
 coil E, bridge B, spring C, spring D G, earth contact. If these 
 currents are transmitted by a vibrator, they are strong enough 
 to produce a noise which can be heard in all parts of a room, 
 and consequently the call may be given in this way. If the 
 currents are due to telephonic transmission, the instrument is 
 applied to the ear, care being taken to put the finger on the 
 button G, and the exchange of correspondence takes place as in 
 ordinary instruments ; but it is simpler and more manageable 
 to insert a second telephone in the circuit for this purpose. 
 When the box is inverted on its mouth-piece, and the button 
 G ceases to press on the spring D G, the battery current reacts 
 on the vibrator of the instrument, and sends the call to the cor- 
 responding station, following this route : I D A C B E, line, 
 earth, and battery ; and the call goes on until the correspond- 
 
'-,.'** 
 
 f , ' ''/?? ' l / 
 
 \ * A' 
 
 ent breaks the current by taking up his insirament^Jirfs/warn- / ' \ . 
 
 ing the other that he is ready to listen. ^ ^ / * 
 
 System of M, Puluj. There is yet another call system, <fo- \ V 
 vised by M. Puluj. It consists of two telephones without mouth- ' ' . 
 pieces, connected together, and with coils placed opposite the 
 branches of two tuning-forks, tuned as nearly as possible to the 
 same tone. A small metal bell is fixed between the opposite 
 faces of the tuning-forks, and a wire stretched near them is pro- 
 vided with a small ball in contact with their branches. "When 
 the tuning-fork at the sen ding-station is put in vibration by 
 striking it with an iron hammer covered with skin, the tuning- 
 fork at the other station vibrates also, and its ball strikes upon 
 the bell. As soon as the signal is returned by the second sta- 
 tion, mouth-pieces with iron diaphragms are fastened to the tel- 
 ephones, and the correspondence begins. It seems that, by the 
 use of a resonator, the sound which reaches the receiving-sta- 
 tion may be so intensified as to become audible in a large hall, 
 and the bell signal may be heard in an adjoining room, even 
 through a closed door. 
 
 Mr. Alfred Chiddey's System. This arrangement consists 
 of a slender copper tube, eight inches long, and with an orifice 
 of one-thirtieth of an inch, of which the lower end is soldered 
 to the diaphragm of a telephone. A branch joint, to which an 
 India-rubber tube is fitted, connects it with a gas-jet, which is 
 lighted and surrounded with a lamp shade, in such a way as 
 to make it produce, under given conditions, sounds resembling 
 those of the singing flames. A perfectly similar system is ar- 
 ranged at the other end of the line, in such a way that the 
 sounds emitted in each case shall be precisely in unison. If 
 the two systems are so regulated as not to emit sounds in their 
 normal condition, they can be made to sing by causing a tun- 
 ing-fork in the vicinity of one or the other to vibrate the same 
 note, and then the corresponding flame will begin to sing, pro- 
 ducing a vibration in the diaphragm of the telephone with 
 
206 THE TELEPHONE. 
 
 which it is in correspondence, and hence will follow the vibra- 
 tion of the diaphragm of the other telephone, and consequently 
 the vibration of the flame of the calling instrument. In this 
 way the call signal may be made without the intervention of 
 any battery. 
 
 APPLICATIONS OF THE TELEPHONE. 
 
 The applications of the telephone are much more numerous 
 than might be supposed at the first glance. As far as the tele- 
 graphic service is concerned, its use must evidently be rather 
 limited, since it cannot register the messages sent, and the 
 speed of transmission is inferior to that of the improved sys- 
 tem of telegraphs ; yet in many cases it would be very valuable, 
 even for a telegraphic system, since it is possible to work it 
 without any special telegraphic training. The first comer may 
 send and receive with the telephone, and this is certainly not 
 the case even with the simplest forms of telegraphic instru- 
 ments. This system is, therefore, already in use in public offices 
 and factories, for communication in mines, for submarine works, 
 for the navy, especially when several vessels manosuvre in the 
 same waters, some towed by others ; finally, for military pur- 
 poses, either to transmit orders to different corps, or to com- 
 municate with schools of artillery and rifle practice. In Amer- 
 ica the municipal telegraphic service and that of telegraphs lim- 
 ited to the area of towns are conducted in this way, and it is 
 probable that this system will soon be adopted in Europe. In- 
 deed, a service of this kind was established in Germany last 
 autumn at the telegraph offices of some towns, and the Lon- 
 don Post-office is now thinking of establishing it in England. 
 
 But, besides its use for the purposes of correspondence, the 
 telephone can be useful to the telegraphic service itself by af- 
 fording one of the simplest means of obtaining a number of 
 simultaneous transmissions through the same wire, and even of 
 being combined in duplex with the Morse telegraphs. Its ap- 
 
SIMULTANEOUS TRANSMISSION. 207 
 
 plications in the microphonic form are incalculable, and the 
 proverb which declares that " walls have ears" may in this way 
 be literally true. It is alarming to think of the consequences 
 of such an indiscreet organ. Diplomatists must certainly re- 
 double their reserve, and tender confidences will no longer be 
 made with the same frankness. On this point we cannot think 
 that much will be gained, but, on the other hand, the physician 
 will probably soon make use of this invention to ascertain more 
 readily the processes going on within the human body. 
 
 APPLICATION OF THE TELEPHONE TO SIMULTANEOUS 
 TELEGRAPHIC TRANSMISSIONS. 
 
 The simultaneous transmission of several messages through 
 the same wire is one of the most curious and important appli- 
 cations of the telephone to telegraphic instruments which can 
 be made, and we have seen that it was this application which 
 led Messrs. Gray and Bell to the invention of speaking tele- 
 phones. The admiration which these instruments have excited 
 has thrown the original idea into the background, although it 
 has perhaps a more practical importance. We will now con- 
 sider these systems. 
 
 An articulating telephone is not necessary in order to obtain 
 simultaneous transmission : the musical telephones devised by 
 MM. Petrina, Gray, Froment, etc., are quite sufficient, and a brief 
 explanation of their principle will make this intelligible. Sup- 
 pose that there are seven electro-magnetic vibrators at the two 
 corresponding stations, which are tuned with the same tuning- 
 fork on the different notes of the scale, and suppose that a key- 
 board, resembling the Morse telegraph key, is arranged so that, 
 by lowering the keys, electric reaction takes place on each vi- 
 brator : it is easy to see that these vibrators may be made to 
 react in the same way on the corresponding vibrators of the 
 opposite station ; but they must be tuned on the same note, 
 and the sounds emitted will continue while the keys are low- 
 
208 THE TELEPHONE. 
 
 ered. By keeping them down for a shorter or longer time, the 
 long or short sounds which constitute the elements of tele- 
 graphic language in the Morse system may be obtained, and 
 consequently an audible transmission becomes possible. Let 
 us now suppose that a telegraphist accustomed to this mode of 
 transmission is placed before each of the vibrators, and that 
 they transmit different messages at the same moment in this 
 way : the telegraphic wire will be instantaneously traversed by 
 seven currents, broken and massed upon each other, and they 
 might be expected to produce a medley of confused sounds on 
 the vibrators at the receiving-station ; but since they each har- 
 monize with the corresponding vibrator, they have no sensible 
 influence except on those for which they are intended. The 
 dominant sound may be made still more distinct by applying a 
 Helmholtz resonator to each vibrator j 1 that is, an acoustic in- 
 strument which will only vibrate under the influence of the 
 note to which it is tuned. In this way it is possible to select 
 the transmitted sounds, and only to allow each employe to hear 
 that which is intended for him. Consequently, however con- 
 fused the sounds may be on the receiving vibrators, the person 
 to whom do is assigned will only receive do sounds, the person 
 to whom sol is assigned will only receive sol sounds, so that 
 
 1 Helmholtz's resonator is based upon the principle that a volume of air 
 contained in an open vase emits a certain note when placed in vibration, 
 and that the height of the note depends on the size of the vase and of its 
 opening. Helmholtz makes use of a globe with a large opening on one 
 side and a small one on the other, and the small one is applied to the ear. 
 If a series of musical notes take place in the air, the one which is in har- 
 mony with the fundamental note of the globe is intensified, and can be dis- 
 tinguished from the rest. The same effect takes place when, on singing to 
 a piano accompaniment, some strings are heard to vibrate more strongly 
 than others, namely, those which vibrate in unison with the sounds emitted. 
 The resonators are made in various ways ; those most generally used ara 
 cases of different lengths, which also serve as sounding-boxes. 
 
ORIGIN OF THE PRINCIPLE. 209 
 
 correspondence may be carried on as well as if they had each a 
 special wire. 
 
 In the mode we have described, this telegraphic system only 
 admits of audible transmissions, and consequently cannot reg- 
 ister messages. To supply this defect, it has been suggested 
 to make the receiving vibrators react on registers, so arranging 
 the latter that their electric organ may present such magnetic 
 inertia that, when it is influenced by the vibrations of sound, 
 its effect may be maintained throughout the time of vibration. 
 Experiments show that a Morse receiver, worked by the current 
 of a local battery, will be enough for this purpose ; so that if 
 the musical vibrator is made to react as a relay, that is, on a 
 contact in connection with the local battery and the receiver, 
 the dots and dashes may be obtained on it which are the con- 
 stituent elements of the Morse code. 
 
 On these principles, and considering that the musical spaces 
 separating the different notes of the scale are such as may be 
 easily distinguished by the resonator, seven simultaneous trans- 
 missions may be obtained on the same wire; but experience 
 shows that it is necessary to be content with a much smaller 
 number. Yet this number may easily be doubled by apply- 
 ing the mode of transmission in an opposite direction to the 
 system. 
 
 Mr. Bell states that the idea of applying the telephone to 
 multiple electric transmissions occurred simultaneously to M. 
 Paul Lacour of Copenhagen, to Mr. Elisha Gray of Chicago, 
 to Mr. Varley of London, and to Mr. Edison of New York ; 
 but there is some confusion here, for we have already seen, 
 from reference to the patents, that Mr. Yarley's system dates 
 from 1870 ; that of M. Paul Lacour from September, 1874 ; that 
 of Mr. Elisha Gray from February, 1875; and those of Messrs. 
 Bell and Edison were still later. Yet it appears from Mr. 
 Gray's specification that he was the first to conceive and exe- 
 cute instruments of the kind. In fact, in a specification drawn 
 
210 THE TELEPHONE. 
 
 up on August 6th, 1874, he distinctly put forward the system 
 we have described, and which is the basis of those of which 
 we have still to speak. This specification was only an addi- 
 tion to two others made out in April and June, 1874. Mr. 
 Varley's system has only an indirect relation to the one we 
 have described. It appears from what Mr. Bell said on the 
 subject, in a paper addressed to the Society of Telegraphic 
 Engineers in London, that he himself only attaches a second- 
 ary interest to this invention. 
 
 He said that he had been struck with the idea that the 
 greater or less duration of a musical sound might represent 
 the dot and dash of the telegraphic alphabet, and it occurred 
 to him that simultaneous telegraphic transmissions, of which 
 the number should only be limited by the delicacy of the 
 sense of hearing, might be obtained by suitable combinations 
 of long and short sounds, and that these should be effected by 
 a key-board of tuning-forks applied to one end of a telegraphic 
 line, and so arranged as to react electrically on electro -mag- 
 netic instruments striking on the strings of a piano. For this 
 purpose it would be necessary to assign an employe to each 
 of the keys for the service of transmission, and to arrange that 
 his correspondent should only distinguish his peculiar note 
 among all those transmitted. It was this idea, Mr. Bell adds, 
 which led to his researches in telephony. 
 
 For several years he sought for the best mode of reprodu- 
 cing musical sounds at a distance by means of vibrating rheo- 
 tomes: the best results were given by a steel plate vibrating 
 between two contacts, of which the vibrations were electrically 
 produced and maintained by an electro -magnet and a local 
 battery. In consequence of its vibration, the two contacts 
 were touched alternately, and the two circuits were alternately 
 broken the local circuit which kept the plate in vibration, and 
 the other which was connected with the line, and reacted on 
 the distant receiver, so as to effect simultaneous vibrations in 
 
211 
 
 it. A Morse key was placed in the latter circuit near the 
 sending instrument, and when it was lowered, vibrations were 
 sent through the line ; when it was raised, these vibrations 
 ceased, and it is easy to see that, by lowering the key for a 
 longer or shorter time, the short and long sounds necessary for 
 the different combinations of telegraphic language could be 
 obtained. Moreover, if the vibrating plate of the receiving in 
 strument were so regulated as to vibrate in unison with the 
 sending instrument in correspondence, it would vibrate better 
 with this sender than with another whose plate was not so 
 adjusted. 
 
 It is evident that different sounds might be simultaneously 
 transmitted with several plates by this arrangement of con- 
 tact breaker, and that at the receiving-station the sounds might 
 be distinguished by each employe, since the one which corre- 
 sponds to the fundamental note of each vibrating plate is re- 
 produced by that plate. Consequently, the sounds produced 
 by the vibrating plate of do, for example, will only be audible 
 at the receiving-station on the plate tuned to do, and the same 
 will be the case with the other plates ; so that the sounds will 
 reach their destination, if not without confusion, yet with suffi- 
 cient clearness to be distinguished by the employes. 
 
 Mr. Bell sums up the defects still existing in his system as 
 follows: 1st. The receiver of the messages must have a good 
 musical ear, in order to distinguish the value of sounds. 2d. 
 Since the signals can only take place when the transmitted cur- 
 rents are in the same direction, two wires must be employed 
 in order to exchange messages on each side. 
 
 He surmounted the first difficulty by providing the receiver 
 with an instrument which he called the vibrating contact 
 breaker, and which registered automatically the sounds pro- 
 duced. This contact breaker was placed in the circuit of a 
 local battery, which could work a Morse instrument under cer- 
 tain conditions. When the sounds emitted by the instrument 
 
212 THE TELEPHONE. 
 
 did not correspond with those for which it had been tuned, 
 the contact breaker had no effect on the telegraphic instru- 
 ment: it only acted when the sounds were those which were 
 to be interpreted, and its action necessarily corresponded to 
 the length of the sounds. 
 
 Mr. Bell adds that he applied the system to electro-chemi- 
 cal telegraphs; but we need not dwell on this part of the in- 
 vention, since, as we have said, it is no longer his special 
 study. 
 
 System of M. Lacour of Copenhagen. M. Lacour's system 
 was patented on the 2d September, 1874, but his experiments 
 were commenced on the 5th June of the same year. Since M. 
 Lacour believed that the vibrations would be imperceptible on 
 long lines, his first attempts were made on a somewhat short 
 line; but in November, 1874, fresh experiments were made 
 between Fredericia and Copenhagen on a line 225 miles in 
 length and, it was ascertained that vibratory effects could be 
 easily transmitted, even under the influence of a rather weak 
 battery. 
 
 In M. Lacour's system the sending instrument is a simple 
 tuning-fork, placed in a horizontal position, and one of its arms 
 reacts on a contact breaker, which can produce precisely the 
 same number of discharges of currents as there are vibrations 
 
 FIG. 59. 
 
 of the tuning-fork. If a Morse manipulator is inserted in the 
 circuit, it is evident that if it is worked so as to produce the 
 dots and dashes of the Morse alphabet, the same signals will 
 be reproduced at the opposite station, and the signals will be 
 
213 
 
 manifested by long and short sounds, if an electro - magnetic 
 receiver is connected with the circuit. This sender is shown 
 Fig. 59. 
 
 Fig. 60 represents M. Lacour's receiver. It consists of a 
 tuning-fork, F, made of soft iron, not of steel, like the sending 
 
 FIG. 60. 
 
 tuning-fork, and each of its branches is inserted in the bobbin 
 of an electro-magnetic coil, C C ; two distinct electro-magnets, 
 M M, react close to the extremities of the fork, in such a way 
 that the polarities developed on the two branches of the fork 
 under the influence of the coils, C C, should be of contrary 
 signs to those of the electro-magnets, M M. 
 
 If this double electro-magnetic system is inserted in a line 
 circuit, it follows that, for each discharge of the transmitted 
 current, a corresponding attraction of the branches of the tun- 
 ing-fork will take place, and consequently there will be a vibra- 
 tion, producing a sound, if the discharges are numerous. This 
 sound will naturally be short or long in proportion to the dura- 
 tion of the sender's action, and it will be the same as that of 
 the tuning-fork in that instrument. Again, if one branch of 
 
214 THE TELEPHONE. 
 
 the tuning- fork reacts on a contact, P, inserted in the circuit of 
 the local battery communicating with a Morse receiver, traces 
 will be produced on this receiver of length varying with the 
 duration of the sounds, for the Morse electro-magnet will be so 
 quickly affected by the successive breaks in the current that its 
 armature will remain stationary throughout each vibration. " I 
 have not yet been able," said M. Lacour, in an address delivered 
 before the Danish Academy of Science in 1875, "to calculate 
 the time necessary for the production of definite vibrations in 
 the tuning-fork. Different factors have to be considered ; but 
 experiment has shown that the time which elapses before the 
 local circuit is broken is such a small fraction of a second as 
 to be almost inappreciable, even when the current is very weak. 
 
 "Since intermittent currents only affect a tuning-fork on 
 condition that it vibrates in unison with the one which pro- 
 duces them, it follows that if a series of sending tuning-forks, 
 tuned to the different notes of the scale, is placed at one end of 
 a circuit, and if a similar series of electro-magnetic tuning-forks, 
 in exact accordance with the first, is placed at the other end of 
 the circuit, the intermittent currents transmitted by the send- 
 ing tuning-forks will be added to each other without becoming 
 confused, and each of the receiving tuning-forks will only be 
 affected by the currents emitted by the tuning-fork in unison 
 with it. In this way the combinations of elementary signals 
 representing a word may be telegraphed simultaneously." 
 
 M. Lacour enumerates the ways in which this system may 
 be applied as follows: "If the keys in connection with the 
 sending tuning-forks are placed side by side, and are lowered 
 in succession, or two or three together, it will be enough to 
 play on the keys as on a musical instrument, in order that the 
 air may be heard at the receiving station, or the signals trans- 
 mitted simultaneously may each belong to a different message. 
 This system will therefore allow the farthest station on a line 
 to communicate with one or several intermediate stations, and 
 
215 
 
 vice versa, without disturbing the communication at other sta- 
 tions. In this way two stations can exchange signals unper- 
 ceived by the rest. The power of sending many signals at 
 once affords a good means of improving the autographic tele- 
 graph. In the instruments now in use, such as those of Ca- 
 selli and D'Arlincourt, there is only one tracing stylus, and this 
 stylus must pass over the whole surface of the telegram in or- 
 der to obtain a copy of it; but with the telephone a certain 
 number of styli may be placed side by side in the form of a 
 comb, and this comb need only be drawn in a certain direction 
 to pass over the surface of the telegram. In this way a more 
 faithful copy will be obtained in a shorter time." 
 
 M. Lacour also observes that his system possesses a merit al- 
 ready pointed out by Mr. Varley, namely, that the instruments 
 permit the passage of ordinary currents without revealing their 
 presence, whence it follows that the accidental currents which 
 often disturb telegraphic transmission will have no effect on 
 these systems. 
 
 M. Lacour began without applying an electro-magnetic sys- 
 tem to his instrument in order to maintain the movement of 
 the tuning-fork; but he soon saw that this accessory was in- 
 dispensable, and he made the tuning-forks themselves electro- 
 magnetic. It also occurred to him to convert the transmitted 
 currents into pulsatory currents by inserting an induction coil 
 in the circuit, which was also done by Mr. Elisha Gray. Final- 
 ly, in order to obtain the immediate action of the tuning-forks 
 and the immediate cessation of their action, he constructed 
 them so as to reduce their inertia as much as possible. This 
 was effected by inserting the two branches of the tuning-fork 
 in the same coil and by lengthening its handle, and turning it 
 back so that it might pass through a second coil, dividing into 
 two branches, and embracing the two vibrating branches, but 
 without touching them. When a current traverses both coils, 
 it produces, in the kind of horseshoe magnet formed by the 
 
216 
 
 THE TELEPHONE. 
 
 two systems, opposite polarities, which provoke a double reac- 
 tion in the vibrating branches a reaction by repulsion exerted 
 by the two branches in virtue of the same polarity, and a re- 
 action by attraction by the other two branches in virtue of 
 their opposite polarities ; and this double action is repeated 
 by the movements of a contact breaker applied to one of the 
 vibrating branches of the tuning-fork. 
 
 Mr. Elisha Gray's System. According to the system origi- 
 nally patented, each sender, represented in Fig. 61, consists of an 
 electro-magnet, M M, resting below a small copper tablet, B S, in 
 such a way that its poles pass through this tablet and are on 
 a level with its upper surface. A steel plate, A S, is fixed 
 above these poles ; its tension can be regulated by means of a 
 screw, S ; and another screw, c, is placed on the plate, and is in 
 electric communication with a local battery, R', by means of a 
 Morse key. Below the plate A S there is a contact, d, con- 
 
 . 61. 
 
 nected with the line wire, L ; this contact is met by the plate 
 at the moment of its attraction by the electro - magnet, and 
 breaks the current of a line battery, P, which acts on the re- 
 ceiver of the opposite station. Finally, the electric communi- 
 cation established between the local battery R' and the electro- 
 magnet, as may be seen in the figure, produces vibrations in 
 the steel plate A S at each lowering of the key, as in the case 
 of ordinary vibrations vibrations which, with a suitable ten- 
 sion of the plate and a given intensity of the battery R', can 
 
GRAY'S SYSTEM. 
 
 217 
 
 produce a definite musical note. Moreover, since at eacli vibra- 
 tion the plate A S meets the contact, discharges of the line 
 current take place through the line L, and react on the receiv- 
 ing instrument, causing it to reproduce exactly the same vibra- 
 tions as those of the sending instrument. 
 
 The receiving instrument represented in Fig. 62 exactly re- 
 sembles the one we have just described, except that there is no 
 
 FIG. 02. 
 
 contact, d, below the vibrating plate A S, and the contact c, in- 
 stead of communicating with the line wire, is in electric con- 
 nection with a register, E, and a local battery, P. It follows 
 from this arrangement that when the plate A S vibrates under 
 the influence of the broken currents passing through the elec- 
 tro-magnet M M, similar vibrations are sent through the regis- 
 ter ; but if the electro-magnetic organ of this register is prop- 
 erly regulated, these vibrations can only produce the effect of 
 a continuous current, and hence the length of the traces left 
 on the instrument will vary with the duration of the sounds 
 produced. In this way the registration of the dashes and dots 
 which constitute the signs of the Morse vocabulary will be 
 effected. 
 
 If it is remembered that the plate A S vibrates under the 
 influence of electro-magnetic attractions more readily in pro- 
 portion to their approximation in number to the vibrations 
 corresponding to the fundamental sound it can emit, it be- 
 comes clear that if this plate is tuned to the same note as that 
 
 10 
 
218 THE. TELEPHONE. 
 
 of the corresponding instrument, it will be rendered peculiar- 
 ly sensitive to the vibrations transmitted by the sender, and 
 the other vibrations which may affect it will only act faintly. 
 Moreover, a resonator placed above the plate will greatly in- 
 crease this predisposition; so that if several systems of this 
 kind, tuned to different notes, produce simultaneous transmis- 
 sions, the sounds corresponding to the different vibrations 
 will be in a certain sense selected and distributed, in spite of 
 their combination, into the receivers for which they are spe- 
 cially adapted, and each of them may retain the traces of the 
 sounds emitted by adding the register, which may be so ar- 
 ranged as to act as an ordinary Morse receiver. Mr. Gray 
 states that the number of sending instruments and indepen- 
 dent local circuits may be equal to that of the tones and semi- 
 tones of two or more octaves, provided that each vibrating 
 plate be tuned to a different note of the scale. The instru- 
 ments may be placed side by side, and their respective local 
 keys, arranged like the keys of a piano, will make it easy to 
 play an air combining notes and chords ; there may also be an 
 interval between the instruments, which may be sufficiently far 
 from each other to allow the employes to work without being 
 distracted by sounds not intended for them. 
 
 In a nQVf arrangement, exhibited at the Paris Exhibition, 
 1878, Mr. Gray considerably modified the way of working the 
 various electro-magnetic organs which we have just described. 
 In this case, the plates consist of tuning-forks with one branch 
 kept in continual vibration at both stations, and the signals 
 only become perceptible by intensifying the sounds produced. 
 This arrangement follows from the necessity of keeping the 
 line circuit always closed for multiple transmissions of this 
 nature, so as to react with pulsatory currents, which are alone 
 able, as we have already seen, to retain the individual character 
 of several sounds simultaneously transmitted. 
 
 Under these conditions the sender consists, as we see 
 
GRAY S SYSTEM. 
 
 219 
 
 (Fig. 63), of a bar tuning-fork, a, which is grooved for the 
 passage of a runner, heavy enough to tune the fork to the 
 desired note, and it oscillates between two electro-magnets, e 
 
 B^L 
 
 Earth 
 
 FIG. 63. 
 
 and /, and two contacts, I and G. The difference of resistance 
 in the electro-magnets is very great : in the one,/, the resist- 
 ance is equal to two and three-quarter miles of telegraphic 
 wire, in the other it does not exceed 440 yards. When elec- 
 tric communication is established, as we see in the figure, the 
 following effect takes place: Since the current of the local 
 battery through the two electro-magnets is broken by the rest- 
 contact of the Morse key H, the plate a is subject to two con- 
 trary actions ; but since the electro-magnet / has more turns 
 than the electro-magnet e, its action is preponderant, and the 
 plate is attracted toward f, and produces a contact with the 
 spring G, which opens a way of less resistance for the current. 
 
220 
 
 THE TELEPHONE. 
 
 Since the current then passes almost wholly through G, ft, 1, 
 2, B, the electro-magnet is now able to act ; the plate a is then 
 attracted toward e, and, by producing a contact on the spring 
 I, it sends the current of the line B P through the telegraphic 
 line, if the key II is at the same time lowered on the sending 
 contact : if not, there will be no effect in this direction ; but 
 since the plate a has left the spring G, the first effect of attrac- 
 tion by the electro-magnet/will be repeated, and this tends 
 to draw the plate again toward/. This state of things is re- 
 peated indefinitely, so as to maintain the vibration of the plate, 
 and to send out signals corresponding with these vibrations 
 whenever the key II is lowered. The elastic nature of the 
 plate makes these vibrations more easy, and it ought also to 
 be put in mechanical vibration at the outset. 
 
 The receiver, represented in Fig. 64, consists of an electro- 
 
 FIG. 04. 
 
 magnet, M, mounted on a sounding -box, C, and having an 
 armature formed by a tuning-fork, L L, firmly buttressed on 
 the box by a cross-bar, T. There is a runner, P, on the arma- 
 
221 
 
 ture, sliding in a groove, which makes it possible to tune the 
 vibrations of the tuning-fork to the fundamental note of the 
 sounding-box C, which is so arranged as to vibrate in unison 
 with it. Under these conditions the box as well as the tun- 
 ing-fork will act as an analyzer of the vibrations transmitted 
 by the currents, and may set the register at work by itself 
 reacting on a breaker of the local current. To obtain this re- 
 sult, a membrane of gold-beater's skin or parchment must be 
 stretched before the opening of the box, and a platinum con- 
 tact must be applied to it, so arranged as to meet a metallic 
 spring connected with any kind of register or a Morse instru- 
 ment, when the membrane vibrates. As, however, in America 
 the messages are generally received by sound, this addition to 
 the system is not in use. 
 
 The instrument is not only regulated by the runner P, but 
 also by a regulating screw, Y, which allows the electro-magnet 
 M to be properly adjusted. The regulating system is made 
 more exact by the small screw, V, and the instrument is con- 
 nected with the line by the binding-screw, B. Of course this 
 double arrangement is necessary for each of the sending sys- 
 tems. 
 
 As I have already said, seven different messages might theo- 
 retically be sent at once in this way, but Mr. Gray has only 
 adapted his instrument for four ; he has, however, made use of 
 the duplex system, which allows him to double the number of 
 transmissions, so that eight messages may be sent at the same 
 time four in one direction, and four in another. 
 
 Mr. Hoskins asserts that this system has been worked with 
 complete success on the lines of the Western Union Telegraph 
 Company, from Boston to New York, and from Chicago to 
 Milwaukee. Since these experiments were made, fresh im- 
 provements have rendered it possible to send a much larger 
 number of messages. 
 
 Mr. Gray has also, aided by Mr. Hoskins, devised a system 
 
222 THE TELEPHONE. 
 
 by which telephonic messages may be sent on a wire previous- 
 ly used for Morse instruments. Mr. Varley had already solved 
 this problem, but Mr. Gray's system seems to have produced 
 important results, and has therefore a claim to our attention. 
 We do not, however, describe it here, since it is not within the 
 lines marked out for us, and those who are interested in the 
 subject will find all the necessary details in a paper inserted in 
 the Journal of the Society of Telegraphic Engineers, London, 
 vol. vi. 
 
 Mr. Var ley's System. This system is evidently the earliest 
 in date, since it was patented in 1870, and the patent describes 
 the principle of most of the arrangements which have since 
 been adopted by Messrs. Lacour, Gray, and Bell. It is based 
 upon the use of his own musical telephone, which we have al- 
 ready described, but with some variations in its arrangement, 
 which make it somewhat like the Reiss system. 
 
 It was Mr. Varley's aim to make his telephone work in con- 
 junction with instruments with ordinary currents, by the addi- 
 tion of rapid electric waves, incapable of making any practical 
 change in the mechanical or chemical capacity of the currents 
 which serve for the ordinary signals, yet able to make distinct 
 signals, perceptible to the ear and even to the eye. He says : 
 "An electro-magnet offers at first a great resistance to the pas- 
 sage of an electric current, and may consequently be regarded 
 as a partially opaque body with respect to the transmission of 
 very rapid inverse currents or of electric waves. Therefore, if 
 a tuning-fork, or an instrument with a vibrating plate, tuned to 
 a given note, be placed at the sending station, and so arranged 
 as to be kept in constant vibration by magnetic influence, the 
 current which acts upon it must be passed into, two helices 
 placed one above the other, so as to constitute the primary 
 helix of an induction coil ; in this way it will be possible to 
 obtain in two distinct circuits two series of rapidly broken cur- 
 rents, which will correspond to the two directions of the vibra- 
 
223 
 
 tions of the tuning-fork, and we shall also have the induced 
 currents produced in the secondary helix by these currents, 
 which may act on a third circuit. This third circuit may be 
 placed in connection with a telegraphic line previously used by 
 an ordinary telegraphic system, if a condenser is applied to it, 
 and in this way two different transmissions may be obtained 
 simultaneously." 
 
 Fig. 65 represents the arrangement of this system. D is the 
 
 vibrating plate of the tuning-fork designed to produce the elec- 
 tric contacts necessary to maintain it in motion. These con- 
 tacts are at S and S', and the electro-magnets which affect it 
 are at M and M'. The induction coil is at I', and the three 
 helices of which it is composed are indicated by the circular 
 lines which surround it. There is a Morse manipulator at A, 
 another at A', and the two batteries which work the system are 
 at P and P'. The condenser is at C, and the telephone is at 
 the end of the line L. 
 
 AVhen the vibration of the plate D tends to the right, and 
 the electric contact takes place at S', the current of the battery 
 P', after traversing the primary helix, reaches the electro-mag- 
 nets M M', which give it an impulse in the contrary direction. 
 AVhen, on the other hand, it tends to the left, the current is 
 sent through the second primary circuit, which will be balanced 
 by the first. Consequently there will be a series of reversed 
 currents in the induced circuit corresponding to the key A', 
 which will alternately charge and discharge the condenser C, 
 
224 THE TELEPHONE. 
 
 thus sending into the line a corresponding series of electric un- 
 dulations, which will react on the telephone placed at the end 
 of the line ; and as the duration of the transmitted currents 
 will vary with the time that the key A' is lowered, a corre- 
 spondence in the Morse code may be obtained in the telephone, 
 while another correspondence is exchanged with the key A and 
 the ordinary Morse receivers. 
 
 In order to render the vibratory signals visible, Mr. Varley 
 proposes to use a fine steel wire, stretched through a helix and 
 facing a narrow slit, to reproduce the vibrations. A light, 
 which is intercepted by the wire, is placed behind the slit. 
 As soon as a current passes, the wire vibrates and the light 
 appears. A lens is placed so as to magnify the image of the 
 luminous slit, and project it on a white screen while the wire is 
 in vibration. 
 
 VARIOUS USES OF THE TELEPHONE. 
 
 Its Domestic Application. We have seen that telephones 
 may be used with advantage in public and private offices : they 
 can be set up at a much less expense than acoustic tubes, and 
 in cases where the latter would never be employed. With the 
 aid of the calls we have described, they offer the same advan- 
 tages, and the connection between the instruments is more 
 easily concealed. The difference of price in establishing them 
 is in the ratio of one to seven. 
 
 For this purpose electro-magnetic telephones are evidently 
 the best, since they require no battery, and are always ready to 
 work. They are already in use in many government offices, 
 and it is probable that they will soon be combined with elec- 
 tric bells for the service of hotels and of large public and private 
 establishments ; they may even be used in private houses for 
 giving orders to servants and porters, who may thus save visi- 
 tors from the fatigue of a useless ascent of several stories. 
 
 In factories, telephones will certainly soon replace the tele- 
 
ITS APPLICATIOX TO THE TELEGKAPII. 225 
 
 graphic communication which has already become general. 
 They may not only be used for ordinary messages, but to call 
 for help in case of fire, and they will become an integral part 
 of several systems already established for this purpose. 
 
 In countries which have free telegraphic communication, the 
 telephone has already replaced, in great measure, the private 
 telegraph instruments which have hitherto been in use ; and if 
 the same privilege is extended to France, no other mode of cor- 
 respondence will be used. 
 
 Its Application to Telegraphic Service. The advantage to 
 be derived by the telegraphic service from the telephone is 
 rather limited, since, as far as the speed of transmission is con- 
 cerned, it is of less value than many of the telegraphic instru- 
 ments now in use, and the messages which it produces cannot 
 be registered. Yet in municipal offices not overburdened with 
 messages they offer the advantage of not requiring a trained 
 service. On longer lines their use would be of little value. 
 The Berne Telegraphic Journal has published some interesting 
 remarks on this subject, of which the following is a summary : 
 
 1st. In order to send a message with the special advantages 
 of the system, the sender ought to be able to address his corre- 
 spondent without the intervention of an official. Those who 
 are acquainted with the network of wires know this to be im- 
 possible. Intermediate offices for receiving messages are essen- 
 tial, and the public cannot be admitted to those set apart for 
 sending and receiving, consequently the sender must deliver a 
 written message. 
 
 2d. If the message is written, the chief advantage of the in- 
 strument is lost, since it must be read and uttered aloud, which 
 could not be done if expressed in a language with which the 
 employes were unacquainted. 
 
 3d. The instruments now in use at the telegraph-offices can 
 transmit messages more quickly than if they were spoken. 
 
 In Germany, however, a telephone service has been establish- 
 
 10* 
 
226 THE TELEPHONE. 
 
 ed in several telegraph-offices, and its possible advantages are 
 enumerated as follows in the official circular which created it : 
 
 " The offices which will be opened to the public for the ser- 
 vice of telephonic messages in Germany will be regarded as in- 
 dependent establishments ; yet they will be in connection with 
 the ordinary telegraph - offices, which will undertake to send 
 telephonic messages through their wires. 
 
 "The transmission will take place as follows: The sending- 
 office will request the receiving-office to preparethe instrument ; 
 as soon as the tubes are adjusted, the sending-office will give 
 the signal for despatching the verbal message. 
 
 " The sender must speak slowly and clearly, without raising 
 his voice ; each syllable must be distinctly pronounced ; the 
 final syllables especially must be well articulated, and there 
 must be a pause after each word, in order to give the receiver 
 time to write it down. 
 
 " When the telegram has been received, the employe at the 
 receiving - office must verify the number of words; then he 
 must repeat through the telephone the whole message without 
 pausing, so as to make sure that there is no mistake. 
 
 " In order to insure secrecy, the telephones are placed apart, 
 where persons unconnected ' with the service cannot hear the 
 verbal message, and the employes are forbidden to reveal to 
 any one the names of the correspondents. 
 
 "The charge for telephonic messages, as for the ordinary 
 telegraphic services, is at the rate of so much a word." 
 
 The use of the telephone has also been suggested for verify- 
 ing the perfect junction of telegraphic wires. It is certain that, 
 if the junction is complete, no abnormal sounds will be heard, 
 or only those which result from accidental currents ; but if the 
 junction is bad, the imperfect contacts which take place pro- 
 duce variations in electric intensity which are translated into 
 the more or less marked sounds observed in the telephone. 
 
 M. Mauborgne, the electrician attached to the Northern Rail- 
 
ITS APPLICATION TO THE ARMY. 227 
 
 way of France, has lately used the telephone instead of the 
 galvanometer to ascertain the condition of the circuits in cor- 
 respondence with the instruments in~use for electric signals. 
 The reactions produced on the galvanometer needle by the 
 pieces of iron which are placed at the sides of the railway often 
 make its indications uncertain, and a strong wind produces 
 irregular movements in the instrument which interfere with 
 observations. It was also necessary to place the galvanometer 
 with due regard* to the points of the compass, and to wait for 
 the needle to settle, which involved loss of time. The opera- 
 tion is easily accomplished with the telephone, since the strokes 
 of the call-bell are distinctly reproduced ; it is made to ring 
 by working the contacts which need verification, and in the 
 same way the condition of the battery can be ascertained. 
 
 Application to Military Purposes. Since the telephone was 
 invented, numerous experiments have been made in different 
 countries to ascertain whether it would be of use in military 
 operations. These experiments have hitherto been only mod- 
 erately satisfactory, on account of the noise inseparable from 
 an army, which generally makes it impossible to hear the tele- 
 phone, and every means of intensifying its sounds has been 
 eagerly sought. It was at first supposed that the discovery of 
 the microphone had solved the problem, and I received many 
 inquiries from military schools on the subject, but I have not 
 been able to see that anything has been gained from this point 
 of view. The telephone is, however, of great use in schools of 
 artillery and rifle practice. Now that fire-arms carry so far, it 
 has become necessary to be informed by telegraph of the points 
 hit on the target, in order to judge of the accuracy of aim, and 
 for this purpose telegraphic targets were suggested ; but tele- 
 phones are much to be preferred, and they are now used with 
 good effect. 
 
 If the telephone is unsuited for the service of the flying tel- 
 egraph in the field, it may be of great use, in the defence of 
 
228 THE TELEPHONE. 
 
 towns, to transmit the orders of the commandant to different 
 batteries, and even for the exchange of correspondence with 
 captive balloons sent to hover over fields of battle. 
 
 In spite of the difficulties attending its use, the experiment 
 was made by the Russians in the late war; the cable wire of 
 communication was 500 or 600 yards long, and so light that it 
 could be laid by one man. The Telegraphic Journal of March 
 15th, 1878, states that the bad weather did not interfere with 
 the working of the instruments ; but the noise made it difficult 
 to hear, and it was necessary to cover the head with a hood to 
 intercept external sounds. This cannot be considered a satis- 
 factory result, yet the telephone may be of great service to an 
 army by intercepting the enemy's messages : a bold man pro- 
 Tided with a pocket telephone, who placed himself in a retired 
 spot, might divert the current of the enemy's telegraphic wire 
 into his telephone, and get possession of all his despatches, 
 as we saw was the case at Clermont. He might even do 
 this by diverting the current to earth or to a rail of the 
 railway line. These are suggestions for future research, and 
 it is probable that they may some day be turned to practical 
 account. 
 
 Its Application to the Navy. The telephone may be of the 
 greatest use in naval matters, for the service of electro-sema- 
 phores, for island forts, and ships at anchor. M. Pollard says 
 that " experiments made between the Prefecture Maritime at 
 Cherbourg, the semaphores and the forts on the^mole, demon- 
 strate the advantage there would be in establishing telephones 
 at these stations, since they would insure an easy communica- 
 tion between the vessels of a squadron and the land they are 
 approaching. By sinking small cables which come to the sur- 
 face of the water along mooring-chains, and terminate in buoys 
 or cases which remain permanently in the harbor, the ships of 
 war may in this way place themselves in communication with 
 the Prefecture Maritime as they cast anchor, and, by tempo- 
 
ITS APPLICATION TO THE NAVY. 229 
 
 rarily connecting the vessels together with light cables, the 
 admiral may communicate freely with the whole squadron." 
 
 The telephone has been tried on board ship for transmitting 
 orders, but without success, on account of the noise always 
 going on in a vessel. 
 
 The telephone may be usefully applied to the service of sub- 
 marine torpedoes. We have already seen how it may be ap- 
 plied in connection with the microphone, but it may also be 
 used in firing the torpedoes after the exact position of the ene- 
 my's ship has been ascertained from two reconnaissances taken 
 from different parts of the coast. 
 
 The telephone, again, makes it possible to verify the condi- 
 tion of torpedoes, and to ascertain if there is any fault in the 
 circuit within the explosives. For this purpose a very weak 
 current has been used, and a galvanometer is not always able 
 to indicate the fault, while the extreme sensitiveness of the 
 telephone will do so in the simplest way. 
 
 Captain M'Evoy, of the American army, suggested a way of 
 ascertaining, while on shore, the condition of torpedoes under 
 water, by connecting the buoys which support them with the 
 land by means of a telephonic line. By inserting, in the buoy 
 which supports the torpedo, metallic disks, so arranged as to 
 vibrate with every movement caused by the waves upon the 
 buoy, a continuous noise will be heard in the telephone, after 
 the circuit has been completed by the metallic disks ; and the 
 noise will go on as long as the disks continue to oscillate, and 
 will cease as soon as the buoy is completely covered by the 
 water. When it ceases, therefore, if not affected by some 
 accidental cause, it may be supposed that the enemy's ship is 
 passing over the buoy. 
 
 M. Treve, again, has shown that the telephone might be used 
 with advantage for the telegraphic communication between 
 vessels in tow, and M. des Fortes has applied it with good 
 effect to diving operations. In this instance, one of the glass 
 
230 THE TELEPHONE. 
 
 panes in the helmet is replaced by a copper plate in which the 
 telephone is framed, so that the diver need only make a slight 
 movement of his head in order to receive or address communi- 
 cations to those in charge of the apparatus. With this system 
 the keels of vessels may be examined, and an account given 
 of their condition, without bringing up the divers, which has 
 hitherto been necessary. 
 
 M. de Parville, the able and learned editor of the Journal 
 Scientifique and the science department of the Journal des 
 Debats, has suggested a new and interesting application of the 
 telephone. It concerns the possibility of making use of it to 
 determine the precise position of the magnetic meridian ; that 
 is, the true direction of the magnetized needle. 
 
 For this purpose a Bell telephone is necessary, of which the 
 magnetic core is formed of an iron rod a metre in length, kept, 
 by a suitable suspension, at nearly the same angle of inclina- 
 tion as a dipping-needle. This rod will be magnetized under 
 the influence of terrestrial magnetism, and the telephone will 
 be able to transmit the sounds produced by some sort of vibra- 
 tor placed near its mouth-piece. These sounds will be strong 
 in proportion to the degree of magnetization of the bar; and 
 if the telephone is turned round the horizon, keeping the bar 
 at the same angle of inclination, the sounds transmitted to the 
 receiving telephone will be greatest when the axis of the bar is 
 in the plane of the magnetic meridian, and least when it is at 
 90. It will, therefore, be possible to ascertain from the direc- 
 tion of the axis at the moment when the sounds are no longer 
 heard the exact inclination of the magnetic needle from north 
 to south, for it will be given by the perpendicular to the line 
 which is followed by the axis of the iron bar at that moment. 
 
 It is possible that, with this system, the disturbing influence 
 on the magnetic needle of the mass of iron in iron-plated ves- 
 sels might be almost destroyed, and a more exact orientation 
 than that of the compass might be obtained. The same proc- 
 
ITS APPLICATION TO INDUSTRY AND SCIENCE. 231 
 
 ess may make it possible to estimate and measure the varia- 
 tions of terrestrial magnetism. M. de Parville has not himself 
 tried to apply this system, but Mr. Blake's experiments, of which 
 we spoke in an early part of this work, make it probable that 
 it might be done with advantage. 
 
 Application to Industry. One of the earliest and most im- 
 portant applications of the telephone is that which was first 
 made to the service of mines in England and America in the 
 autumn of 1877. The great length of the galleries is well 
 known, and had already involved the use of the electric tele- 
 graph for transmitting orders ; but the miners did not under- 
 stand how to work these instruments, and the service was ill 
 performed. Thanks to the telephone, through which the first 
 comer can send and receive a message, there is no longer any 
 difficulty in the communication between the galleries and the 
 surface of the mine. 
 
 The ventilation of mines can also be regulated by the aid of 
 telephones. If one of these instruments is placed near a wheel 
 kept in motion by the air which passes through the ventilating 
 shaft, and another is placed in the inspector's office, he can as- 
 certain by the sound if the ventilation is duly carried on, and 
 if the machine works regularly. 
 
 Application to Scientific Research. M. d' Arson vaFs experi- 
 ments, which we have already mentioned, show that the tele- 
 phone can be used as an extremely sensitive galvanoscope ; but 
 since it can only produce sounds under the influence of broken 
 currents, the circuit on which the experiment is made must be 
 divided at rather close intervals. It has-been seen that" it is 
 not even necessary to insert the telephone in the circuit: it 
 may be influenced, when at a distance, either immediately or 
 by the induction of the broken current on a circuit placed par- 
 allel to the first, and the force of these effects may be increased 
 by the reaction of a core of iron, round which the inducing cir- 
 cuit is wound. The drawback to this system is that the direc- 
 
232 THE TELEPHONE. 
 
 tion of the current is not ascertained, so that it cannot be used 
 as a measuring instrument ; but, on the other hand, it is so sen- 
 sitive, so easy to arrange, and so inexpensive, that it might be 
 of the greatest use as a galvanoscope. 
 
 Mr. Warren de la Rue has also made use of the telephone in 
 his researches into the electric discharges of high-tension bat- 
 teries, in order to follow the different phases of the discharge 
 during the luminous phenomena which it produces. In this 
 way he ascertained that when a condenser is placed in connec- 
 tion with a battery formed of a considerable number of insu- 
 lated elements, and is gradually discharged through a Geissler 
 tube, a dull and faint sound is heard in the telephone, as long 
 as the stratifications of light appear to be perfectly stable ; but 
 the sound becomes considerably stronger, and sometimes even 
 piercing, in proportion to the diffusion of these stratifications, 
 and to their approach to the point of extinction : whence it 
 is shown that the discharge of a battery into tubes in which a 
 vacuum has been made is intermittent. 
 
 Mr. Spottiswoode has repeated the same experiments with 
 the discharges of Holtz machines, and with large condensers, 
 and he found that the most piercing sounds produced by the 
 telephone coincided with the greatest development of the strati- 
 fications. These sounds, however, sometimes ceased for a mo- 
 ment. It was even possible to ascertain, from the intensity of 
 the sounds produced, the differences of tension which might be 
 manifested in the charge of the condenser and the slackening 
 of the machine's motion, and the differences of intensity in 
 these sounds might in some cases exceed an octave. The fall 
 in the scale generally appeared in half-tones instead of gradu- 
 ally, and the introduction of resistances into the circuit modi- 
 fied the sounds very much : they might even be intensified by 
 approaching the finger to the discharging tube. 
 
 From experiments made with the telephone between Calais 
 and Boulogne, it appears that this instrument might be ap- 
 
ITS USE IN ARTILLERY PRACTICE. 233 
 
 plied with advantage to the science of projectiles. In fact, in 
 some artillery practice which took place on the shore at Bou- 
 logne, a telephone was placed close to the gun, and the explo- 
 sion was heard at a distance of nearly two miles, where the 
 projectile fell. It was possible to estimate its velocity by 
 measuring the lapse of time between the moment when the 
 projectile left the gun, and its fall. This calculation is usually 
 made by observing the flash from the cannon's mouth ; but in 
 some cases, as in a fog or in practice at long ranges, the tele- 
 phone may be usefully substituted for ocular observation. On 
 the field of battle, an observer, provided with a telephone and 
 placed on a hill, might rectify from a distance the aim of his 
 battery, which is generally established in a sheltered and less 
 elevated place. 
 
L I P> K A It V 
 
 UNIVKKSITY < ) 
 
 (^CALIFORNIA 
 
 THE PHONOGRAPH. 
 
 MR. EDISON'S Phonograph,, which has for ike last year at- 
 tracted so much attention, is an instrument which not only 
 registers the different vibrations produced by speech on a 
 vibrating plate, but reproduces the same words in correspond- 
 ence with the traces registered. " The first function of this 
 instrument is not the result of a new discovery. Physicists 
 have long sought to solve the problem of registering speech, 
 and in 1856 Mr. Leo Scott invented an instrument well known 
 to physicists under the name of phonautograph, which com- 
 pletely solved the difficulty : this instrument is described in all 
 the more detailed treatises on physics. But the second function 
 of the Edison instrument was not realized nor even mentioned 
 by Mr. Scott, and we are surprised that this able inventor should 
 have regarded Mr. Edison's invention as an injurious act of 
 spoliation. We regret on his own account, since no one has 
 wished to deprive him of the credit he deserves, that he should 
 have published a pamphlet on the subject, couched in terms of 
 such asperity, which proves nothing, and only states facts which 
 were well known to all physicists. If any other person could 
 claim the invention of the phonograph, at least in its most cu- 
 rious property of reproducing speech, it would certainly be M. 
 Charles Cros ; for in a sealed paper deposited at the Academic 
 des Sciences, April 30th, 1877, he pointed out the principle of 
 an instrument by means of which speech might be reproduced 
 in accordance with the marks traced on a register like that of 
 
236 THE PHONOGRAPH. 
 
 the phonautograph. 1 Mr. Edison's patent, in which the princi- 
 
 1 I give the text of M. Cros's sealed paper, opened by his request, at 
 the Academic des Sciences, December 3d, 1877: "Speaking generally, my 
 process consists in obtaining traces of the movement to and fro of a 
 vibrating membrane, and in using this tracing to reproduce the same move- 
 ments, with their intrinsic relations of duration and intensity, either on the 
 same membrane, or on one adapted to give out the sounds which result 
 from this series of movements. 
 
 " It is therefore necessary that an extremely delicate tracing, such as may 
 be obtained by passing a needle over a surface blackened by fire, should 
 be transformed into a tracing, capable of sufficient resistance to guide an 
 index which will transmit its movements to the membrance of sound. 
 
 "A light index is fastened to the centre of a vibrating membrane; it 
 terminates in a point (a metallic wire or tip of a feather) which rests on a 
 surface which has been blackened by fire. This surface forms part of a 
 disk, to which the double action of rotation and rectilinear progression has 
 been given. If the membrane is at rest, the point will trace a simple spi- 
 ral ; if the membrane vibrates, tbere will be undulations in the spiral, and 
 these undulations will represent the precise movements of the membrane 
 in their duration and intensity. 
 
 " By a well-known photographic process, a transparent tracing of the 
 undulations of the spiral can be represented by a line of similar dimen- 
 sions on some resisting substance tempered steel, for example. 
 
 " When this is done, this resisting surface is placed in a turning machine, 
 which causes it to revolve and advance with a velocity and motion similar 
 to those by which the registering surface was actuated. A metallic point, 
 if the tracing is concave, or a grooved index if it is in relief, is kept upon 
 the tracing by a spring, and the index which supports this point is con- 
 nected with the centre of the membrane which produces the sounds. Un- 
 der these conditions, the membrane will be actuated not by the vibrating 
 air, but by the tracing which guides the index, and the impulses will be 
 precisely similar in duration and intensity to those to which the registering 
 membrane was subjected. 
 
 " The spiral tracing represents equal successions of time by increasing 
 or decreasing lengths. There is no inconvenience in this, since the turns 
 of the spiral are very close together, if only the circumference of the turn- 
 ing circle is used ; but then the central surface is lost. 
 
 " In all cases the tracing of the helix on a cylinder is much more satis- 
 factory, and I am now trying to make this idea practicable." 
 
EDISON'S PATENT. 237 
 
 pie of the phonograph is first indicated, is dated July 31st, 1877, 
 and he was still only occupied with the repetition of the Morse 
 signals. In this patent Mr. Edison described a mode of regis- 
 tering these signals by means of indentations traced with a 
 stylus on a sheet of paper wound round a cylinder, and this 
 cylinder had a spiral groove cut on its surface. The tracings 
 thus produced were to be used for the automatic transmission 
 of the same message, by passing it again under a stylus which 
 should react on a current breaker. In this patent, therefore, 
 nothing is said of the registration of speech or of its reproduc- 
 tion; but, as the Telegraphic Journal of May 1st, 1878, ob- 
 serves, the foregoing invention gave him the means of solving 
 this double problem as soon as it was suggested to him. If 
 we may believe the American journals, this suggestion soon 
 came, and it was the result of an accident. 
 
 In the course of some experiments Mr. Edison was making 
 with the telephone, a stylus attached to the diaphragm pierced 
 his finger at the moment when the diaphragm began to vibrate 
 under the influence of the voice, and the prick was enough to 
 draw blood. It then occurred to him that if the vibrations of 
 the diaphragm enabled the stylus to pierce the skin, they might 
 produce on a flexible surface such distinct outlines as to repre- 
 sent all the undulations produced by the voice, and even that 
 the same outlines might mechanically reproduce the vibrations 
 which had caused them, by reacting on a plate capable of vi- 
 brating in the same way as that which he had already used for 
 the reproduction of the Morse signals. From that moment the 
 phonograph was discovered, since there was only a step between 
 the idea and its realization, and in less than two days the in- 
 strument was made and tried. 
 
 This is an ingenious story, yet we would rather believe that 
 the discovery was made in a more serious spirit. In fact, -such 
 an inventor as Mr. Edison, who had discovered the electro- 
 motograph and had applied it to the telephone, was already on 
 
238 THE PHONOGRAPH. 
 
 the way to discover the phonograph, and we think too well of 
 his powers to attach much credit to this American romance. 
 Besides, Mr. Edison was well acquainted with Mr. Scott's phon- 
 autograph. 
 
 Mr. Edison's phonograph was only patented in January, 
 1877. Consequently, when we look at the principle of the in- 
 vention, M. Cros undoubtedly may claim priority ; but it is a 
 question whether the system described in his sealed paper, and 
 published in the Semaine du Clerge, October 8th, 1877, would 
 have been capable of reproducing speech. Our doubt seems 
 justified by the unsuccessful attempts of the Abbe Leblanc to 
 carry out M. Cros's idea. When we have to do with such un- 
 dulating and complex vibrations as those involved in the re- 
 production of articulate words, it is necessary that the stereo- 
 typing should in some sense be effected by the words them- 
 selves, and their artificial reproduction will necessarily fail to 
 mark the slight differences which distinguish the delicate com- 
 binations of speech. Besides, the movements performed by a 
 point confined to a groove that follows a sinusoidal curve can- 
 not be effected with all the freedom necessary for the develop- 
 ment of sounds, and the friction exerted on the two edges of 
 the groove will often be of a nature to stifle them. A distin- 
 guished member of the Societe de Physique, when I exhibited 
 the phonograph to that society, justly said that Mr. Edison's 
 whole invention consisted in the thin metallic sheet on which 
 the vibrations are inscribed ; this sheet permits the movements 
 of the vibrating plate to be directly stereotyped, and thereby 
 the problem is solved. It was necessary to find such an expe- 
 dient, and it was done by Mr. Edison, who is therefore the in- 
 ventor of the phonograph. 
 
 After M. Cros, and before Mr. Edison, MM. Napoli and Mar- 
 cel Deprez attempted to make a phonograph, but with so little 
 success that they believed at one time the problem to be in- 
 soluble, and threw doubts on Mr. Edison's invention when it 
 
EDISON'S PATENT. 239 
 
 was announced to the Societe de Physique. They subsequent- 
 ly resumed their labors, and lead us to hope that they may 
 eventually produce a phonograph of more perfect construction 
 than that of Mr. Edison. We shall have more to say on this 
 subject. 
 
 In conclusion, the mechanical reproduction of speech was 
 first effected by Mr. Edison, and in so doing he has accom- 
 plished one of the most curious and important discoveries of 
 our time, since it has shown that this reproduction was much 
 less complicated than had been supposed. Yet the theoretical 
 consequences of the discovery must not be exaggerated, since I 
 do not consider it by any means proved that our theories on 
 the voice are incorrect. There is, in fact, a great difference be- 
 tween the reproduction of a sound'which has been uttered, and 
 the mode in which the same sound was produced. The repro- 
 duction may be easily effected, as M. Bourseul has remarked, as 
 soon as a mode has been discovered of transmitting the vibra- 
 tions of air, however complex they may be ; but in order to 
 produce the complex vibrations of speech by the voice, several 
 special organs must be exercised first, the muscles of the 
 throat ; secondly, the tongue, the lips, and even the teeth 
 and for this reason an articulating machine is necessarily very 
 complex. 
 
 Surprise was expressed that the speaking machine, which 
 was brought from America two years ago, and exhibited at the 
 Grand Hotel, Paris, was so extremely complicated, since the 
 phonograph solved the problem in such a simple way. This 
 is because the latter instrument only reproduces speech, while 
 the former utters it, and the inventor of the speaking machine 
 had to employ in his mechanism all the organs which are nec- 
 essary in our organism for the reproduction of speech. The 
 problem was infinitely more complex, and this invention has 
 not attracted all the attention it deserved. We shall speak of 
 it presently. We must now describe the phonograph, and the 
 
240 
 
 THE PHONOGRAPH. 
 
 different applications which have been, or which may be, made 
 of it. 
 
 Description of the Phonograph, and Mode of Using it. The 
 first and best-known model of this instrument, which we rep- 
 resent in Fig. 66, simply consists of a registering cylinder, 11, 
 set in motion with the hand by a winch, M, before which a 
 vibrating plate is placed, furnished on its face with a telephone 
 mouth-piece, E, and on the reverse side with a tracing-point. 
 This tracing-point, which is seen at 6- in the section of the in- 
 strument given in Fig. 68, is not fixed directly on the plate ; it 
 
 C 
 
 FIG. 66. 
 
 rests on a spring, r, and a caoutchouc pad, c, is placed between 
 it and the vibrating disk. This pad is formed of the end of a 
 tube which is designed to send the vibrations of the plate to 
 the point s without stifling them. Another pad, a, placed be- 
 tween the plate L L and the rigid support of the point, mod- 
 erates in some degree these vibrations, which, without this 
 precaution, would generally be too powerful. 
 
 The cylinder, of which the axis A A (Fig. 66) is cut at one 
 end like a screw, to enable it to make a lateral progressive 
 
DESCRIPTION OF THE INSTRUMENT. 241 
 
 movement simultaneously with the rotatory movement effected 
 on itself, has on its surface a narrow screw-thread coinciding 
 with that of the axis; and when the tracing-point is inserted, 
 it is able to pass along it for a distance corresponding to the 
 time occupied in turning the cylinder. A sheet of tin-foil or 
 of very- thin copper is carefully applied to the surface of the 
 cylinder, and it should be slightly pressed down upon it, so as 
 to show a faint tracing of the groove, and to allow the point 
 of the vibrating disk to be placed in a proper position. The 
 point rests on the foil under a pressure which must be regu- 
 lated, and for this purpose, as well as to detach the cylinder 
 when it is desired to place or take away the tin-foil, there is 
 the articulated system S N, which sustains the support S of 
 the vibrating disk. This system consists of a jointed lever in 
 which there is a nut-screw for the screw R. The handle N at 
 the end of the lever allows the tracing system to be turned 
 aside when the screw R is loosened. In order to regulate the 
 pressure of the tracing-point on the sheet of tin-foil, it is enough 
 to turn the screw R loosely in its socket, and to tighten it as 
 soon as the right degree of pressure is obtained. 
 
 This is the simple system by which speech can engrave itself 
 'on a plate in durable characters, and it works in the following 
 manner : 
 
 The speaker stands before the mouth-piece E, as before a 
 telephone or an acoustic tube, and speaks in a strong, emphatic 
 voice, with his lips pressed against the walls of the mouth- 
 piece, as we see in Fig. 67 ; at the same moment he turns the 
 handle of the cylinder, which is provided with a heavy fly- 
 wheel in order that the movement may be regular. Influenced 
 by the voice, the plate L L begins to vibrate, and sets the trac- 
 ing-point at work, which presses on the tin-foil at each vibra- 
 tion, and produces a furrow whose depth varies along its course 
 in correspondence with the unequal vibrations of the disk. 
 The cylinder which moves at the same time presents the differ- 
 
 11 
 
242 THE PHONOGRAPH. 
 
 ent parts of the groove of which we have spoken to the trac- 
 ing-point in succession; so that, when the spoken sentence 
 comes to an end, the design which has been pricked out, con- 
 
 FIG. 6T. 
 
 sisting of a succession of reliefs and depressions, represents the 
 registration of the sentence itself. The first part of the op- 
 eration is therefore accomplished, and by detaching the sheet 
 from the instrument the words may be put away in a portfolio. 
 We have now to see how the instrument is able to reproduce 
 what has been so easily inscribed. 
 
 For this purpose it is only necessary to repeat the process, 
 and the identical effect will be reproduced in an inverse sense. 
 The tracing stylus is replaced at the end of the groove it has 
 already traversed, and the cylinder is again set in motion. 
 When the engraved track passes again under the point, it has 
 a tendency to raise it, and to impart to it movements which 
 must necessarily be the repetition of those which first produced 
 the tracing. The vibrating plate is obedient to these move- 
 ments, and begins to vibrate, thus reproducing the same 
 sounds, and consequently the same words ; yet since there is 
 necessarily a loss of power in this double transformation of 
 
REPRODUCTION OF WORDS. 
 
 243 
 
 mechanical effects, the speaking-tube C is attached to the 
 mouth-piece E in order to intensify the effects. Under these 
 conditions the words reproduced by the instrument may be 
 heard in all parts of a hall, and it is startling to hear this voice 
 somewhat shrill, it must be admitted which seems to utter 
 its sentences from beyond the grave. If this invention had 
 taken place in the Middle Ages, it would certainly have been 
 applied to ghostly apparitions, and it would have been invalu- 
 able to miracle-mongers. 
 
 As the height of the notes of the musical scale depends on 
 the number of vibrations effected by a vibrating substance in 
 a given time, speaking will be reproduced in a tone of which 
 the pitch will depend on the velocity of rotation given to the 
 cylinder on which the tin-foil is wound. If the velocity is the 
 same as that which was used in registration, the tone of the 
 
244 THE PHONOGRAPH. 
 
 words reproduced is the same as that in which they were 
 uttered. If the velocity is greater, the tone is higher ; if less, 
 the tone is lower ; but the accent of the speaker may always be 
 recognized. Owing to this peculiarity the reproduction of songs 
 is nearly always defective in instruments turned by the hand ; 
 they sing out of tune. This is not the case when the instrument 
 is moved by a well-regulated system of clock-work, and in this 
 way a satisfactory reproduction of a duet has been obtained. 
 
 The words registered on tin-foil can be often reproduced; 
 but the sounds become fainter and more indistinct at each rep- 
 etition, since the tracings in relief are gradually effaced. The 
 reproduction on copper is more successful, but if intended to 
 be permanent the sheets must be stereotyped, and in this case 
 the instrument must be differently arranged. 
 
 An attempt has been made to obtain speech from the 
 phonograph by taking the words registered inversely to their 
 true direction. In this way the sounds obtained were necessa- 
 rily quite unlike the words uttered ; yet Messrs. Fleeming Jen- 
 kin and Ewing have observed that not only are the vowels un- 
 changed by this inverse action, but consonants, syllables, and 
 even whole words may be reproduced with the accent they 
 would have if spoken backward. 
 
 The sounds produced by the phonograph, although fainter 
 than those of the voice which produced the registered tracing, 
 are strong enough to react on the ordinary string telephone, 
 and even on a Bell telephone; and as in this case the sounds 
 do not go beyond the instrument, and can only be heard by 
 the person who is using it, it is easy to ascertain that the 
 sound has not been produced by trickery. 
 
 Mr. Edison presented his phonograph to the Academic des 
 Sciences through me, March llth, 1878, and when his agent, 
 M. Puskas, caused the wonderful instrument to speak, a mur- 
 mur of admiration was heard from all parts of the hall a 
 murmur succeeded by repeated applause. A letter appeared 
 
RECEPTION BY THE ACADEMY. 245 
 
 in the newspapers from one of the persons present, in which 
 he said that " the learned Academy, generally so cold, had nev- 
 er before abandoned itself to such enthusiasm. Yet some mem- 
 bers of a sceptical turn of mind, instead of examining the 
 physical fact, ascribed it to moral causes, and a report soon 
 ran through the room which seemed to accuse the Academy of 
 having been mystified by a clever ventriloquist. Certainly the 
 spirit of ancient Gaul is still to be found among the French, 
 and even in the Academy. One said that the sounds emitted 
 by the instrument were precisely those of a ventriloquist. 
 Another asked if the movements, of M. Puskas's face and lips 
 as he turned the instrument did not resemble the grimaces of 
 a ventriloquist. A third admitted that the phonograph might 
 emit sounds, but believed that it" was much helped by the 
 manipulator. Finally, the Academy requested M. du Moncel 
 to try the experiment, and as he was not accustomed to speak 
 into the instrument, it was unsuccessful, to the great joy of the 
 incredulous. Some members of the Academy, however, desir- 
 ing to ascertain the real nature of the effects, begged M. Pus- 
 kas to repeat the experiments before them in the secretary's 
 office, under such conditions as they should lay down. M. 
 Puskas complied with this request, and they were absolutely 
 satisfied with the result. Yet others remained incredulous, 
 and it was necessary that they should make the experiment 
 for themselves before they accepted the fact that speech could 
 be reproduced in so simple a way." 
 
 The anecdote I have just related cannot be interpreted to 
 the discredit of the Academic des Sciences, since it is especial- 
 ly bound to preserve the true principles of science intact, and 
 only to accept startling facts after a careful examination. Ow- 
 ing to this attitude, all which emanates from the Academy 
 can be received with complete confidence; and we cannot ap- 
 prove too highly of reserve which does not give way to the 
 first impulse of enthusiasm and admiration. 
 
246 THE PHONOGRAPH. 
 
 The failure of my experiment at the Academy was simply 
 due to the fact that I spoke at too great a distance from the 
 vibrating disk, and that my lips did not touch the sides of the 
 mouth-piece. Some days later, at the request of several of my 
 colleagues, I made repeated trials of the instrument, and I 
 soon succeeded in making it speak as well as the supposed 
 ventriloquist; but I learned at the same time that practice is 
 necessary to insure success. Some words are reproduced more 
 readily than others; those which include many vowels and 
 many r's come out better than those which abound in conso- 
 nants, and especially in s's. It is, therefore, not surprising 
 that, even in the case of an experienced manipulator like Mr. 
 Edison's agent, some of the sentences uttered by him are more 
 audible than others. 
 
 The simultaneous repetition of several sentences in different 
 languages by registering one over the other is one of the most 
 surprising effects of the phonograph. As many as three dif- 
 ferent sentences have been obtained ; but in order to distin 
 guish them through the confused sounds which result from 
 placing one over the other, -it is necessary that different per- 
 sons, giving special attention to a particular sentence, should 
 thus separate them and understand their sense. Vocal airs 
 may, in the same way, be registered over the word tracings, 
 and in this case it is more easy to distinguish them. 
 
 There are several models of phonographs. The one repre- 
 sented in Fig. 66 has been chiefly used for public experiments ; 
 but there is a small model, generally sold to the public, in 
 which the cylinder is much longer, and serves at once for reg- 
 ister and fly-wheel. This instrument gives good results, but 
 can only be used for short sentences. In this model, as in- 
 deed in the other, the words are more easily registered by fas- 
 tening a small tube in the form of a prolonged speaking- 
 trumpet to the mouth-piece ; the vibrations of the air are thus 
 concentrated on the vibrating disk, and act with greater ener- 
 
CLOCK-WORK SYSTEM. 247 
 
 gy. The tenuity of the vibrating disk adds to the efficiency 
 of the instrument, and the tracing-point may be fitted directly 
 to this disk. 
 
 I need not describe particularly the phonograph which acts 
 by clock-work. The instrument resembles the one represented 
 in Fig. 66, except that it is mounted on a rather high table, 
 to give room for the descent of the weight which moves the 
 clock-work; the mechanism is applied directly to the axis of 
 the cylinder, supplying the place of the winch, and is regulated 
 by a small fly-wheel. The wheel used in an English system 
 has been adopted, but we prefer that of M. Villarceau, which 
 has small wings. 
 
 Since it is always difficult to fit the tin-foil to the cylinder, 
 Mr. Edison has tried, with good success, to obtain the tracing 
 on a plane surface of tin - foil, by means of the arrangement 
 represented in Fig. 69. In this new model, the plate on which 
 
 FIG. 
 
 the tin or copper sheet is to be applied has a spiral grooving, 
 of which one end corresponds to the centre of the plate, and 
 the other to its outer edges. The plate is set in motion by a 
 powerful system of clock-work, of which the velocity is regu- 
 lated with reference to the length of the turns of the spiral. 
 The vibrating disk is arranged as in the former instrument, and 
 
248 
 
 THE PHONOGRAPH. 
 
 is placed above this plate ; the tracing-point may, by means of 
 a movement of progression imparted to the system, follow the 
 spiral groove from the centre of the plate to its circumference. 
 It must not be supposed that all the tin-foil used for phono- 
 graphic registration is equally good. The foil must be of a 
 definite thickness, and combined with a definite amount of lead. 
 That which is used for wrapping chocolate, and indeed all foil 
 of French manufacture, is too thin and too exclusively made of 
 
 FIG. 70. 
 
 tin to produce good results, and M. Puskas was obliged to im- 
 port some from America to continue his experiments. The 
 relative proportion of lead and tin has not yet been defined, 
 and the selection of foil has been made empirically ; but as the 
 use of the phonograph becomes more general, this proportion 
 must be ascertained, and it may easily be done by analyzing 
 the composition of the foil which gives the best results. 
 
THE TEACING-POINT. 249 
 
 The arrangement of the tracing - point is also of much im- 
 portance for the successful action of the phonograph. It must 
 be very slender and very short (not exceeding a millimetre in 
 length), so as to register distinctly the smallest vibrations of 
 the vibrating disk without deviating from the normal direction 
 of the cylinder, which might be the case if it were long, on ac- 
 count of the unequal friction exerted on the tin-foil. It must 
 also be made of a metal which has no tendency to tear the me- 
 tallic sheet. Iron appears to combine most of the conditions 
 demanded. 
 
 The phonograph is still in its infancy, and it is probable that 
 it may soon be enabled to register speech without the necessity 
 of speaking into a mouth-piece. According to the newspapers, 
 Mr. Edison has already discovered a way of collecting, without 
 the aid of an acoustic tube, the sounds uttered at a distance of 
 three or four feet from the instrument, and of printing them 
 on a metallic sheet. From this there is only a step to the 
 power of inscribing a speech uttered in a large hall at any dis- 
 tance from the phonograph ; and if this step is taken, phonog- 
 raphy may be substituted with advantage for short-hand. We 
 add in a note the instructions given by M. Roosevelt to the 
 purchasers of phonographs, so as to enable them to work the 
 instrument. 1 
 
 1 Never make a contact between the stylus and the cylinder until the 
 latter is covered with the tin-foil. Do not begin to turn the cylinder until 
 assured that everything is in its place. Take care, when the stylus returns 
 to the point of departure, to bring the mouth-piece forward. Always leave 
 a margin of from five to ten millimetres on the left and at the beginning 
 of the sheet of tin-foil ; for if the stylus describes the curve on the ex- 
 treme edge of the cylinder, it may tear the sheet or come out of the groove. 
 Be careful not to detach the spring of the caoutchouc pad. 
 
 To fix the tin-foil, apply varnish to the end with a paint-brush ; take 
 this end between the finger and thumb of the left hand, with the sticky 
 part toward the cylinder ; raise it with the right hand and apply it quite 
 smoothly to the cylinder ; bring round the sticky end, and join them firmly. 
 
 11* 
 
250 THE PHONOGRAPH. 
 
 Considerations on the Theory. Although the explanation 
 we have given will make the effects of the phonograph intelli- 
 
 To adjust the stylus, and place it in the centre of the groove, bring the 
 cylinder to the right, so as to place the stylus opposite the left extremity 
 of the tin-foil ; bring forward the cylinder gently and by degrees, until the 
 stylus touches the tin-foil with force enough to imprint a mark. Observe 
 if this mark is quite in the centre of the groove (in order to do this, make 
 a mark with the nail across the cylinder), and if it is not, adjust the stylus 
 to the right or left by means of the little screw placed above the mouth- 
 piece. The depth of the impression made by the stylus should be one- 
 third millimetre, just enough for it to leave a slight tracing, whatever the 
 range of vibrations may be. 
 
 To reproduce the words, the winch must be turned with the same veloc- 
 ity as when they were inscribed. The average velocity should be about 
 eighty turns a minute. 
 
 In speaking, the lips must touch the mouth-piece, and deep guttural 
 sounds are better heard than those which are shrill. In reproducing, the 
 tightening screw must be loosened and brought in front of the mouth- 
 piece, the cylinder must be brought back to its point of departure, the con- 
 tact between the stylus and the foil must be renewed, and the cylinder must 
 again be turned in the same direction as when the sentence was spoken. 
 
 To increase the volume of reproduced sound, a tube of card-board, wood, 
 or horn may be applied to the mouth-piece ; it must be of a conical form, 
 and its lower end should be rather larger than the opening of the mouth- 
 piece. 
 
 The stylus consists of a No. 9 needle, somewhat flattened on its two 
 sides by friction on an oiled stone. The caoutchouc pad which connects 
 the plate with the disk serves to weaken the vibrations of the plate. If 
 this pad should come off, heat the head of a small nail, apply it to the 
 wax which fastens the pad to the plate or to the spring, so as to soften 
 it ; then press the caoutchouc lightly, until it adheres to the place from 
 which it was detached. The pads must be renewed from time to time, as 
 they lose their elasticity. Care must be taken, in replacing them, not to 
 injure the vibrating plate, either by too strong a pressure or by grazing it 
 with the instrument employed to fix the pad. 
 
 The first experiments should be with single words or very short sen- 
 tences, which can be extended as the ear becomes accustomed to the in- 
 strument's peculiar tone. 
 
THEORY OP THE PHONOGRAPH. 251 
 
 gible, it leads to a curious question which has greatly interest- 
 ed physicists namely, how it is that the tracing made on so 
 yielding a surface as tin can, when retraced by the stylus, of 
 which the rigidity is relatively great, produce a vibratory move- 
 ment without being completely destroyed. To this we reply 
 that the retracing is effected with such extreme rapidity that 
 the effects of active force which are developed only manifest 
 themselves locally, and that under these conditions the me- 
 chanical effects exerted are as energetic in soft as in hard 
 substances. The curious experiment, related in so many books 
 on physics, must be remembered, of a plank pierced when a 
 candle serves as the projectile of a gun. The various acci- 
 dents caused by the discharge of paper waddings must also be 
 remembered. Under such conditions the motion imparted to 
 the molecules which receive the shock has not time to be trans- 
 mitted to the whole mass of the substance to which they be- 
 long, and these molecules are compelled to separate from it, or 
 at any rate to produce, when the substance is capable of vibra- 
 tion, a centre of vibration which diffuses waves throughout its 
 surface, and produces sounds. 
 
 Several scientific men among others Messrs. Preece and 
 Mayer have carefully studied the form of the tracing left by 
 the voice on the tin-foil of the phonograph, and they observe 
 that it greatly resembles the outline of the singing flames so 
 well shown by Herr Koenig's instruments. Mr. Mayer wrote 
 on this subject in the Popular Science Monthly Review of 
 April, 1878. 
 
 He said that he had been successful in reproducing a splen- 
 
 The tone is varied by accelerating or slackening the rotatory movement 
 of the cylinder. The cries of animals may be imitated. Instrumental 
 music may be reproduced by placing a card-board tube before the mouth- 
 piece. The airs should be played in rapid time, since, when there is no 
 system of clock-work, they will be more perfectly reproduced than those 
 which are played slowly. 
 
252 THE PHONOGKAPH. 
 
 did tracing on smoked glass, which gave in profile the outline 
 of the vibrations of sound registered on the tin-foil with their 
 varying curves. For this purpose he fastened to the spring 
 support of the tracing-point of the phonograph a slender rod, 
 terminating in a point, which pressed obliquely against the 
 plate of smoked glass, and, since the latter was in a vertical po- 
 sition, a movement imparted to the rod enabled it to produce 
 a sinusoidal tracing. By this arrangement, when the phono- 
 graph was at work, two systems of tracings were produced at 
 the same moment, of which one was the profile of the other. 
 
 Mr. Mayer had not, at the time he wrote, been long enough 
 in possession of the instrument to make many experiments 
 with it, but from a study of some of its curves it appeared to 
 him that the registered outlines bore a strong resemblance to 
 those of Koenig's singing flames. 
 
 O O O QO G2 o OO 13 A 
 
 FIG. Tl. 
 
 Fig. 71 represents the tracing which corresponds to the let- 
 ter a when pronounced as in bat, in the three systems of regis- 
 tration. That corresponding to line A is an enlarged repro- 
 duction of the tracing left on the tin-foil ; that corresponding 
 to line B represents its profile on the sheet of smoked glass. 
 Finally, line C shows the outline of Koenig's singing flames, 
 when the same sound is produced quite close to the membrane 
 of the register. It must be quite close, since the form of the 
 tracing produced by a pointer attached to a vibrating mem- 
 brane, when influenced by composite sounds, depends on the 
 
253 
 
 distance intervening between the membrane and the source of 
 sound, and an infinite variety in the form of the tracing may 
 be obtained by modifying the distance. In fact, when this 
 distance is increased, the waves of sound which result from 
 composite sounds react on the membrane at different moments 
 of their emission. For example, if the composite sound is 
 formed of six harmonics, the displacement of the source of 
 vibration from the first harmonic by one-quarter the length of 
 a wave will respectively remove the second, third, fourth, fifth, 
 and sixth harmonics -J, f, 1, 1^, 1-J the length of a wave, and 
 consequently the outline resulting from the combination of 
 waves will no longer be the same as it was before the displace- 
 ment of the source of sound, although the perception of the 
 sounds remains the same in both cases. This principle is clear- 
 ly demonstrated by Koenig's instrument, by lengthening and 
 shortening an extensible tube, inserted between the resonator 
 and the vibrating membrane, which is placed close to the 
 flame ; and this explains the disagreement of physicists as to 
 the composition of vocal sounds which they have analyzed by 
 means of the singing flames. 
 
 Mr. Mayer adds that these facts further show that we cannot 
 hope to read the impressions and tracings of the phonograph, 
 which not only vary with the nature of the voice, but also with 
 the different moments at which the harmonics of the voice are 
 emitted, and with the relative differences in the intensities of 
 these harmonics. 
 
 Notwithstanding this assertion, we reproduce (Fig. 72) an 
 extremely curious tracing sent to us by Mr. Blake, which repre- 
 sents the vibrations produced by the words " Brown, Univer- 
 sity : how do you do ?" They were photographed by means 
 of an index fastened to a vibrating disk on which a ray of 
 light was thrown. The word " how " is particularly remark- 
 able for the combined forms of the inflections of the vibra- 
 tions. 
 
254 
 
 THE PHONOGRAPH. 
 
 Recent experiments seem to show that the more the vibrat- 
 ing membrane of the phonograph resembles the human ear in 
 its construction, the better it repeats and registers the sound 
 
 FIG. 72. 
 
 vibrations : it should be stretched, as far as possible, in the 
 same way as the tympanum is stretched by the hammer of the 
 ear, and moreover it should have the same form, since the 
 vibrations of air are in this case much more effective. 
 
 Mr. Edison considers that the size of the opening of the 
 mouth-piece has considerable influence on the distinct articula- 
 tion of speech. When the sounds are pronounced before the 
 whole surface of the diaphragm, some hissing sounds are lost. 
 They are, on the contrary, intensified when these sounds reach 
 the diaphragm through a narrow orifice with sharp rims. If 
 the opening is toothed on its flattened rims, the hissing con- 
 sonants are delivered more clearly. Speech is reproduced 
 more perfectly when the mouth-piece has a covering of some 
 
USES OF THE PHONOGRAPH. 255 
 
 thickness, so arranged as to deaden the sounds arising from 
 the friction of the tracing-point on the tin. 
 
 Mr. Hardy has rendered the registration of phonographic 
 tracings more easy by adding a small ebonite tube, resembling 
 the mouth-piece of a wind instrument, to the mouth-piece of 
 the phonograph. 
 
 USES OF THE PHONOGRAPH, AND ITS FUTURE. 
 
 Mr. Edison has lately published in the North American Re- 
 view of May to June, 1878, an article on the future of the 
 phonograph, in which he himself discusses the different ap- 
 plications which may be made of this instrument. Without 
 sharing all his anticipations, which appear to us to be very 
 premature, we think that some extracts from his paper may be 
 interesting. 
 
 " In order to furnish a basis on which the reader may take 
 his stand ... a few categorical questions and answers are given 
 upon the essential features of the principle involved. 
 
 "1. Is a vibrating plate or disk capable of receiving a com- 
 plex motion which shall correctly represent the peculiar property 
 of each and all the multifarious vocal and other sound waves ? 
 
 " The telephone answers affirmatively. 
 
 " 2. Can such complex movement be transmitted from such 
 plate by means of a single embossing-point attached thereto, 
 to effect a record upon a plastic material, by indentation, with 
 such fidelity as to give to such indentations the same varied 
 and complex form ? And if so, will this embossing-point, upon 
 being passed over the record thus made, follow it with such 
 fidelity as to transmit to the disk the same variety of move- 
 ment, and thus effect a restoration or reproduction of the vocal 
 or other sound waves, without loss of any property essential to 
 producing on the ear the same sensation as if coming direct 
 from the original source ? 
 
 "The answer to this may be summed up in a statement of 
 
256 THE PHONOGRAPH. 
 
 the fact that . . . the writer has at various times during the 
 past weeks reproduced these waves with such degree of accura- 
 cy in each and every detail as to enable his assistants to read, 
 without the loss of a word, one or more columns of a news- 
 paper article unfamiliar to them, and which were spoken into 
 the apparatus when they were not present. The only percep- 
 tible loss was found to be in the quality of the utterance, a 
 non-essential in the practical application of the instrument. 
 Indeed, the articulation of some individuals has been percepti- 
 bly improved by passage through the phonograph, the original 
 utterance being mutilated by some imperfection of lip and 
 mouth formation, and these mutilations corrected or eliminated 
 by the mechanism of the phonograph. 1 
 
 " 3. Can a record be removed from the apparatus on which 
 it was made, and replaced upon a second without mutilation or 
 loss of effective power to vibrate the second plate ? 
 
 " This is a mere mechanical detail, presenting no greater ob- 
 stacle than having proper regard for the perfect interchange- 
 ableness of the various working parts of the apparatus not so 
 nice a problem as the manufacture of the American watch. 
 
 "4. What as to the facility of placing and removing the 
 second sheet, and as to its transportation by mail ? 
 
 " But ten or fifteen seconds suffice for such placing or re- 
 moving. A special envelope will probably be required, the 
 weight and form of which, however, will but slightly increase 
 the cost of postage. 
 
 " 5. What as to durability ? 
 
 "Repeated experiments have proved that the indentations 
 possess wonderful enduring power, even when the reproduction 
 has been effected by the comparatively rigid plate used for 
 
 1 We confess that we find it difficult to believe in this property of the 
 phonograph, from which we have only heard the harsh and unpleasant 
 voice of Punch. 
 
257 
 
 their production. It is proposed, however, to use a more 
 flexible plate for reproducing, which, with a perfectly smooth 
 stone point diamond or sapphire will render the record ca- 
 pable of from fifty to one hundred repetitions, enough for all 
 practical purposes. 
 
 " 6. What as to duplication of a record and its permanence ? 
 
 " Many experiments have been made, with more or less suc- 
 cess, in the effort to obtain electrotypes of a record, and the 
 writer is informed that it has very recently been successfully 
 accomplished. He can certainly see no great practical obstacle 
 in the way. This, of course, permits of an indefinite multipli- 
 cation of a record, and its preservation for all time. 
 
 " 7. What is the requisite force of wave impinging upon the 
 diaphragm, and the proximity of the mouth to the diaphragm, 
 to effect a record ? 
 
 " These depend in great measure upon the volume of sound 
 desired in the reproduction. If the reproduction is to be made 
 audible to an assembly, considerable force is requisite in the 
 original utterance ; if for the individual ear, only the ordinary 
 conversational tone (even a whisper has been reproduced). In 
 both cases the original utterances are delivered directly in the 
 mouth-piece of the instrument. An audible reproduction may, 
 however, be had by speaking at the instrument from a distance 
 of from two to three feet in a loud tone. The application of a 
 flaring tube or funnel to collect the sound waves, and the con- 
 struction of an especially delicate diaphragm and embossing- 
 point, etc., are the simple means which suggest themselves to 
 effect this. . . . 
 
 " The foregoing presentment of the stage of development 
 reached by the several essential features of the phonograph 
 demonstrates the follow ing faits accomplis : 
 
 " 1. The captivity of all manner of sound waves, hitherto 
 designated as * fugitive,' and their retention. 
 
 " 2. Their reproduction with all their original characteristics, 
 
258 THE PHONOGRAPH. 
 
 without the presence or consent of the original source, and after 
 the lapse of any period of time. 
 
 " 3. The transmission of such captive sounds through the 
 ordinary channels of commercial intercourse and trade in a 
 material form, for purposes of communication. 
 
 " 4. Indefinite multiplication and preservation of such sounds, 
 without regard to the existence or non-existence of the original 
 source. 
 
 " 5. The captivation of sounds, with or without the knowl- 
 edge or consent of the source of their origin. . . . 
 
 "The apparatus now being perfected in mechanical details 
 will be the standard phonograph, and may be used for all pur- 
 poses except such as require special form of matrix, such as 
 toys, clocks, etc., for an indefinite repetition of the same thing. 
 The main utility of the phonograph being, however, for the 
 purposes of letter- writing and other forms of dictation, the 
 design is made with a view to its utility for that purpose. 
 
 " The general principles of construction are, a flat plate or 
 disk, with spiral groove on the face, worked by clock-work un- 
 derneath the plate ; the grooves are cut very closely together, 
 so as to give a great total length to each length of surface 
 a close calculation gives as the capacity of each sheet of foil 
 nearly 40,000 words. The sheets being but ten inches square, 
 the cost is so trifling that but a hundred words might be put on 
 a single sheet economically. . . . 
 
 "The practical application of this form of phonograph is 
 very simple. A sheet of foil is placed in the phonograph, the 
 clock-work set in motion, and the matter dictated into the 
 mouth-piece without other effort than when dictating to a ste- 
 nographer. It is then removed, placed in suitable form of en- 
 velope, and sent through the ordinary channels to the corre- 
 spondent for whom it is designed. He, placing it upon his 
 phonograph, starts his clock-work, and listens to what his cor- 
 respondent has to say." 
 
LAMBEIGOT'S SYSTEM. 259 
 
 Since this paper by Mr. Edison appeared, in June, 1878, he 
 has applied the phonograph to several other purposes, among 
 which we may mention that of registering the force of sounds 
 on railways, and especially on the Metropolitan Atmospheric 
 Railway in New York. The instrument which he has made 
 for this purpose resembles that by Mr. Leo Scott, and bears 
 the same name. It is described and represented in the Daily 
 Graphic of July 19th, 1878, as well as the aerophone, the mega- 
 phone, and the microtasimeter, which is adapted for astronom- 
 ical observations. We should exceed the limits laid down for 
 this volume, if we were to give a more detailed account of these 
 inventions. 
 
 M. Lambrigot, one of the officials on the telegraphic lines in 
 France, and the author of various improvements in the Caselli 
 telegraph, has shown me a phonographic system of his own in- 
 vention in which it is reduced to its simplest form. He sent 
 me the following description of his system: 
 
 " The instrument consists of a wooden slab placed vertically 
 on a stand and firmly fixed upon it. There is a round open- 
 ing in the middle of the slab, covered by a tightly stretched 
 sheet of parchment bearing a steel knife, which, like the trac- 
 ing-point of the phonograph, is intended to trace the vibra- 
 tions. A solid block rises from the stand to the middle of the 
 slab, and supports a slide on which a runner can move in front 
 of the slab. There is a strip of glass on this runner, of which 
 one side is covered with stearine. When the runner is moved 
 to and fro, the stearine comes in contact with the knife and 
 takes the mould of its form, which is curved throughout. 
 
 "A sound places the sheet of parchment in vibration, and 
 imparts its movement to the knife, which traces various lines 
 on the surface of the stearine. 
 
 " The reproduction thus obtained on the strip of glass is 
 subjected to the ordinary processes of metallization. By gal- 
 vanism a deposit of copper is obtained which reproduces the 
 
260 THE PHONOGRAPH. 
 
 lines in an inverse way. In order to make the metallic plate 
 speak, it is necessary to pass a point of ivory, wood, or horn 
 lightly over the signs, and, by moving it more or less quickly, 
 the different tones can be heard, just as they were spoken. 
 
 "Since copper is relatively harder than lead, the copper 
 plate on which the vibrations are traced will afford an unlim- 
 ited number of reproductions. To obtain this result, a lead 
 wire must be applied to the plate, and due pressure must be 
 exerted on it. The wire is flattened and takes the impression 
 of all the traces, which then appear in relief. If the edge of a 
 card is passed through this impressed tracing, the same sounds 
 are produced as those which are obtained from the copper 
 plate." 
 
 M. Lambrigot suggests that the speaking -plates might be 
 useful in many ways : for example, they might make it easy to 
 learn the correct pronunciation of foreign languages, since a 
 sufficient number might be collected to make a sort of vocabu- 
 lary which would give the accent of the words most in use in 
 a given language. 
 
 By this simple process M. Lambrigot has been able to ob- 
 tain a strong impression, within a copper groove, of the vibra- 
 tions caused by the voice, and they are so distinctly engraved 
 that whole sentences may be heard, if they are retraced by the 
 sharpened point of a match. It is true that the reproduction 
 is imperfect, and that those words are only to be distinguished 
 which were previously known ; but it is possible that better 
 results will be obtained from improvements in the system, and 
 at any rate the distinct impression of the vibrations of the 
 voice on a hard metal is a really interesting discovery. 
 
 I have made one somewhat important observation in the 
 working of the phonograph, namely, that if speech is registered 
 on the instrument in a very hot room, and it is then carried to 
 a colder room, the reproduction of speech is imperfect in pro- 
 portion to the difference of temperature. This is probably 
 
SPEAKING-MACHINE. 261 
 
 owing to considerable modifications in the elasticity of the 
 caoutchouc pad which is inserted between the tracing -point 
 and the vibrating disk : perhaps differences of expansion in 
 the tin-foil have also some effect. 
 
 FABER'S AMERICAN SPEAKIXG-MACHIXE. 
 
 About two years ago the newspapers announced with some 
 pomp that a speaking -machine had reached Paris, which far 
 surpassed Vaucanson's duck, and which would attract general 
 attention. Unfortunately the invention was not, in the first 
 instance, brought forward with any scientific authority, and 
 was soon relegated to take a place among the curiosities ex- 
 hibited by conjurors. In a country so essentially critical and 
 sceptical as France, there are always those who profess incre- 
 dulity, and who will even resist evidence, and it was asserted 
 that the machine only spoke because its exhibitor was an able 
 ventriloquist. This is an old assertion which has lately been 
 made with reference to the phonograph. Some scientific pa- 
 pers echoed the absurdity, and the speaking-machine was so 
 discredited that it is now unnoticed, although it is a most in- 
 genious and interesting conception. When will our country 
 be cured of the error of denying everything without due ex- 
 amination ? 
 
 Since we ourselves only judge of things after having serious- 
 ly considered them, we think it just to vindicate the truth as 
 to Mr. Faber's machine, and this can only be done by an exact 
 description of it. 
 
 As I said in the last chapter, there is a great difference be- 
 tween the production and the reproduction of a sound, and a 
 machine like the phonograph, adapted for the reproduction of 
 sound, may differ essentially from a machine which really 
 speaks. In fact, the reproduction even of articulate sounds 
 may be very simple, as soon as we possess the means of stereo- 
 typing the vibrations of air necessary to transmit these sounds ; 
 
262 THE PHONOGRAPH. 
 
 but in order to produce them, and especially to emit the com- 
 plex vibrations which constitute speech, it is necessary to set 
 in motion a number of special organs, fulfilling more or less 
 exactly the functions of the larynx, the mouth, the tongue, the 
 lips, and even the nose. For this reason, a speaking-machine 
 is necessarily very complicated, and this is precisely the case 
 with the machine we are now considering. Such a machine is 
 not now made for the first time, and the Academy has lately 
 been reminded of a speaking-head which was in the possession 
 of the philosopher Albertus Magnus in the thirteenth century, 
 and which was destroyed by St. Thomas Aquinas as a diaboli- 
 cal invention. 
 
 Mr. Faber's speaking-machine was exhibited two years ago 
 at the Grand Hotel, and may now be seen in the room ad- 
 joining M. Robert Houdin's theatre, the same room in which 
 Mr. Giffard exhibited the telephone. It consists of three dis- 
 tinct parts : 1st, of a large bellows worked by a pedal, which 
 produces the currents of air necessary for the production of 
 sounds, and to some extent acts as the lungs ; 2d, a vocal in- 
 strument, consisting of a larynx accompanied by diaphragms 
 of various forms to modify the sounds, of a mouth with caout- 
 chouc lips and tongue, and of a tube with an outlet somewhat 
 resembling the nasal cavities ; 3d, of a system of jointed levers 
 and of pedals, terminating in keys like those of a piano. 
 
 The most interesting part of the machinery, of which we 
 represent the principle, Fig. 73, is the vocal apparatus, which 
 involved the severest study of physics in order to succeed in 
 the production of articulate sounds. It consists, first, of a 
 rather thick caoutchouc tube, within which there is a kind of 
 whistle, L, as in a clarionet. The whistle consists of a small 
 caoutchouc cylinder with a longitudinal slit, and before this 
 is placed a very thin ivory plate lined with caoutchouc. This 
 plate is fixed at one end to the cylinder, and deviates slightly 
 from it at its free end, so as to permit the current of air pro- 
 
SPEAKING-MACUIXE. 
 
 263 
 
 jected from the bellows, S, to penetrate between the two parts, 
 and to cause the vibrations in the ivory plate necessary for the 
 production of a sound. The extremity of the caoutchouc cyl- 
 inder is closed on this side, and is fitted to an iron rod, t, which 
 comes out of the pipe, and is connected with a system of bars, 
 corresponding to the key-board of a piano, by which the force 
 of sounds can be regulated. This force depends on the width 
 of the opening between the tongue and the cylinder. 
 
 ' 
 
 V 
 
 / 
 
 FIG. 73. 
 
 The whistle, which plays the part of the larynx, is neces- 
 sarily placed opposite the opening of the bellows, and a sort of 
 tourniquet, M, is fastened to the opening itself, which is able to 
 move on certain conditions, so that it may produce the rolling 
 sound of r. This is done by fastening before the opening a 
 diaphragm in which there is a somewhat wide and long slit, 
 and this slit can be almost closed by a little bar of the same 
 size, M, revolving on a transverse axis which supports it by its 
 centre. In its normal condition, this little bar is kept in a 
 slanting position by cords attached to the key-board, and the 
 
264 THE PHONOGRAPH. 
 
 air ejected by the bellows readily traverses the slit in order to 
 reach the larynx ; but two dampers are fastened to the rods 
 which transmit movement, with which the cords just mention- 
 ed are also connected. On lowering the notes of the key-board, 
 the passage of air is contracted, and the little plate begins to 
 oscillate and to press against a band of leather, producing by 
 its vibration an action similar to that produced by the cricket. 
 This little tourniquet only begins to act when the dampers are 
 lowered by a pedal worked by the hand ; and this is also the 
 case with the iron rod t, which modifies the acuteness of the 
 sounds passing through the larynx. 1 
 
 Below the larynx tube, which is only five centimetres in 
 length, there is another pipe, G, also of caoutchouc, which ter- 
 minates in a spherical cavity connected with the outer air by 
 a caoutchouc tube, I, slightly raised, and closed by a valve, of 
 which the movements are regulated by a pedal worked by the 
 key-board. When the valve is open, the sounds emitted through 
 the larynx are somewhat nasal. 2 The larynx communicates with 
 the mouth through a square funnel-shaped pipe to which six 
 metallic diaphragms, D, are fastened ; the diaphragms are placed 
 in a vertical position behind each other, and have indentations 
 on their lower end, which are intended to dimmish more or 
 less the orifice for the current of air, and to impede its passage 
 with greater or less force. The diaphragms, which we repre- 
 
 1 The action of this pedal is effected by two little rockers, so connected 
 that the upper damper is lowered a little before the lower damper is raised 
 a condition necessary to produce the quivering motion of the plate which 
 furnishes the rolling r. 
 
 a The arrangement of this part of the instrument is remarkable in this 
 particular, that in the case of certain letters the air is ejected with more 
 or less force through the pipe I, while in the case of other letters the air 
 is drawn into the same tube. Since I was unable to see the internal ar- 
 rangement of these cavities, I can only give an imperfect account of the 
 mechanism at work. 
 
SPEAKING-MACHINE. 
 
 2G5 
 
 sent separately, Fig. 74, are connected with the key-board by 
 jointed iron rods, , and, for the emission of most articulate 
 sounds, several of the diaphragms are moved at the same mo- 
 ment and at different heights. We shall return to this subject. 
 
 FIG. 74. 
 
 The mouth consists of a caoutchouc cavity, O, somewhat 
 resembling the human mouth, and forming a continuation to 
 the channel we have just described. The tongue, C, likewise 
 modelled on the human tongue, is placed within the mouth, 
 and connected with two jointed rods, t, t, fastened to its two 
 opposite ends, so as to enable the tongue to raise its tip, or 
 touch the palate, in obedience to the notes of the key-board. 
 The lower caoutchouc lip, A, can also be more or less closed, 
 according to the action of the key-board on its special rod. 
 Finally, a circular metallic piece, E, following the shape of the 
 mouth, is placed above the upper lip, with a small opening in 
 it to admit of the pronunciation of the letter/. 
 
 The key -board has fourteen notes, of different lengths, pro- 
 ducing the following letters when lowered : a, o, w, i, e, /, r, v,f, 
 s, ck, 6, d, g. The longest corresponds to g, and the shortest to 
 
 12 
 
266 THE PHONOGRAPH. 
 
 a. There are two pedals below the g note and those of b and 
 d, corresponding with the opening of the tube which produces 
 nasal sounds, and to the rod which regulates the opening of 
 the larynx, and this makes it possible to obtain p, t, and k from 
 the notes b, d, g. The mechanical effects produced by lower- 
 ing the different notes in succession are as follows : 
 
 1. The a note moves the first five diaphragms. 
 
 2. o also moves these five diaphragms, but varies the pitch, 
 and closes the mouth a little. 
 
 3. u does the same, only farther closing the mouth. 
 
 4. t moves a single diaphragm, raises the tip of the tongue, 
 and opens the mouth more widely. 
 
 5. e moves six diaphragms, throw's the tongue farther back, 
 and opens the mouth still more. 
 
 6. I moves five diaphragms, sends the tongue against the 
 palate, and farther opens the mouth. 
 
 7. r moves six diaphragms and the tourniquet, lowers the 
 tongue, and somewhat closes the mouth. 
 
 8. v moves five diaphragms, almost closes the mouth, and 
 keeps the tongue down. 
 
 9. / lowers the circular appendix of the upper lip, and almost 
 entirely closes the mouth. 
 
 10. s moves three diaphragms, half closes the mouth, and 
 half raises the tongue. 
 
 11. ch moves three diaphragms, keeps the mouth half closed, 
 and farther lowers the tongue. 
 
 , 12. b moves five diaphragms, closes the mouth, and keeps 
 the tongue completely down. 
 
 13. d moves six diaphragms, keeps the mouth three parts 
 closed, and raises the tongue a little. 
 
 14. g moves five diaphragms, keeps the mouth three parts 
 closed, and the tongue completely down. 
 
 m is produced by lowering note b, and opening the valve of 
 the pipe which gives nasal sounds. 
 
SPEAKING-MACHINE. 267 
 
 n is obtained by lowering note d, and opening the same 
 valve. 
 
 h is obtained from note s by lowering the pedal which acts 
 upon the larynx, and half closing it. 
 
 Since the other letters of the alphabet are compound sounds, 
 they can be produced by combinations of the preceding 
 letters. 
 
 Although the words pronounced by this machine are dis- 
 tinct, they are spoken in a uniform, drawling tone, which 
 might, I should have thought, have excluded the idea of im- 
 position. Some of them are indeed far from distinct, yet the 
 results are not less remarkable; and when we consider the 
 amount of study and experience which must have been applied 
 to the combination of all these arrangements; it seems surpris- 
 ing that physicists have not given more attention to such an 
 interesting machine. 
 
 As for the mechanical execution, it is impossible to admire 
 too highly the simple and ingenious manner in which all the 
 complicated movements of the different vocal organs have been 
 connected with the key - board, of which the mechanism has 
 been so calculated as only to produce the precise action of the 
 organ which is required for any given effect. For this pur- 
 pose, the notes of the key-board regularly increase in length, 
 so as to produce at a single touch different mechanical effects 
 on the rods which act upon the mechanism ; and since most 
 of the notes are required to react simultaneously on the whole 
 mechanism, the rods which transmit the movement are fastened 
 to a series of jointed levers which cross the notes of the key- 
 board at right angles. Pegs of different length are fastened 
 to the notes at this junction, so as to produce the simultaneous 
 action of the different organs of the machine. 
 
 The public will believe that the assertions of ventriloquism 
 are unfounded when I add that I myself have made the 
 machine speak. 
 
APPENDIX. 
 
 The Ferrodon System of Telephonic Alarum. Captain Perrodou, of 
 the French Artillery, has lately improved the system invented by 
 MM. Dntertre and Gouault, by a self-acting call. For this purpose 
 he has fastened a spring contact before the diaphragm, combined 
 with the diaphragm and the electro-magnetic system so as to form 
 a vibrator. The vibrations thus produced are strong enough to 
 resound in an ordinary telephone, so as to make the call audible in 
 spite of external noises. 
 
 The system has been arranged in different ways. In one ar- 
 rangement, a small plate of tin-foil is glued to the outer surface of 
 the diaphragm, and the end of the telephone coil-wire is connected, 
 below the inner surface of the mouth-piece, with a silver wire sol- 
 dered to a spring plate, which constitutes the contact of the vibra- 
 tor. This spring plate, slightly curved, is fixed below one of the 
 binding-screws of the telephone, and terminates at its free end in a 
 regulating screw by which the interval between the contacts can 
 be regulated, and the instrument can be arranged as a telephonic 
 organ. To do this, the screw can be withdrawn, and inserted in a 
 nut which establishes direct connection between the line and the 
 telephone coil. It is easy to adapt an ordinary telephone to this 
 system. 
 
 In another arrangement M. Courtot's mirror telephone has been 
 employed, and a sort of spring pedal is inserted in the wood of the 
 mouth-piece, which terminates in a bent silver wire, supporting an 
 index adapted to make a contact with a square plate soldered to 
 the diaphragm. The battery is placed in connection with the 
 spring of the pedal, and one end of the telephone coil-wire com- 
 municates as before with the diaphragm. When a call is to be 
 made, the pedal must be pressed, aud the battery immediately 
 communicates with the silver wire which, with the diaphragm, 
 constitutes the vibrator, and an electric vibration is sent through 
 the circuit, and produces the call. For receiving, the pedal is al- 
 
270 APPENDIX. 
 
 lowed to revert to its normal position, arid the index of the pedal, 
 touching the contact in connection with the diaphragm, establishes 
 direct communication between the two telephones, while breaking 
 the contact of the silver wire with the diaphragm, so that the bat- 
 tery cannot act. 
 
 It appears that experiments made at the musketry school at 
 Orleans for a distance of 370 miles have been very successful. 
 
 M. Varey's Microphone Speaker. M. Varey has recently arranged 
 a successful microphonic speaker, in which the principle of the 
 microphone represented in Fig. 39 is maintained. The system of 
 three vertical carbons is arranged inside a sort of snuffbox, of 
 which the lid is made of a thin plate of mica, horn, or ebonite. 
 The snuffbox is provided with two hinged arms, so that it may be 
 placed in the most convenient position for speaking, and at the 
 same time the sensitiveness of the instrument can be regulated. A 
 small battery, consisting of two Gaiffe cells of chloride of silver, is 
 placed in the pedestal on which the instrument stands, and sets 
 the microphone at work without further trouble. In this way the 
 speaker can be used like an ordinary telephone, and is not affected 
 by vibrations of air. Only vibrations of sound react upon it. 
 
 Microphonic Speaker l)y Fitch. Mr. Pope states that this speaker 
 has produced excellent results in America. It is merely Edison's 
 carbon telephone reduced to its simplest form. It consists of a 
 small cylindrical box, which has a mouth-piece like the one repre- 
 sented in Fig. 28. The box contains two carbon disks of the same 
 diameter as itself, and is lined with a kind of felt. Metal wires, 
 inlaid in a groove scooped on the circumference of the carbons, 
 place them in communication with the circuit and battery, and 
 transmission takes place by means of the vibrations of the upper 
 carbon, which is directly influenced by the voice without the inter- 
 vention of any diaphragm. These vibrations, which can be freely 
 developed in consequence of the elasticity of the felt pad which 
 supports the lower carbon, produce on the surface of contact of the 
 two carbons the modifications of intensity of current necessary for 
 the reproduction of speech, in the same way as other microphones. 
 
 An induction coil is necessarily employed for a long circuit, and 
 the effects of induction in the adjacent wires are modified by two 
 rheostats introduced into the circuit at its two extremities. 
 
 Further Remarks on the Theory of the Telephone. Following the ex- 
 ample of a certain sceptic in the Acaddmie des Sciences, Colonel 
 Navez continues to maintain the theory first formed as to the mode 
 in which the telephone acts, in spite of the clearest proofs of its in- 
 
APPENDIX. 271 
 
 sufficiency ; but most scientific men -who consider the question liave 
 come round to our opinion, and admit the concurrence of several 
 causes in the reproduction of speech by this remarkable instru- 
 ment. Mr. Fleeming Jenkiu writes to this effect in the new edi- 
 tion of a treatise on electricity and magnetism. 
 
 He observes that a singular fact has been discovered by several 
 persons, who have ascertained that not merely non-magnetic and 
 non-conducting bodies can be substituted for the diaphragms of 
 receiving telephones, but that they will act without a diaphragm 
 at all. In this case it is evident that we have to do with the 
 sounds discovered by Page, and that they are produced by the 
 magnet itself, in which each molecular movement constitutes the 
 source of the sound produced. This sound becomes articulate as 
 soon as its increase and decrease can follow the increasing or de- 
 creasing action of the voice which produces it at the seuding-sta- 
 tion. It is certain that when the transmitted currents are due to 
 the action of the Bell diaphragm, the sounds due to the Page effects 
 ought to correspond with those which would be given by iron dia- 
 phragms adapted to the receiving instruments ; so that, when a 
 telephone has an iron diaphragm, there are, in fact, two voices, that 
 of the diaphragm, which is strong, and that of the magnet, which 
 is weak. When a disk of wood is substituted for one of iron, it 
 acts as a sounding-board for the Page effect, and when the disk is 
 of metal, induction is developed by the magnetic modifications, and 
 tends to produce vibration, thus developing a third source of sound, 
 which may be called the Ampere effect. Finally, a fourth source 
 of sound may result from the induced effects produced in the wire 
 itself in consequence of changes in the intensity of current. These 
 sounds, first observed by M. de la Rive, have since been studied by 
 Mr. Fergusson, of Edinburgh (vide Telegraphic Journal of November 
 1st, 1878). 
 
 Mr. Fleeming Jenkin's opinion only differs from mine in his as- 
 cribing the energy of sound acquired by a telephone with an iron 
 diaphragm to the preponderance of sounds in the latter, whereas I 
 consider it to be chiefly due to the increase of energy in the whole 
 magnetic system produced by the reaction of the two magnetic 
 parts on each other. If the two effects could be taken singly, it 
 is probable that the sounds produced by each of them separately 
 would be similar, since in magnetic effects the reaction and action 
 are equal. But as they are combined, it becomes difficult to assign 
 to each the share which belongs to it in the general effect observed. 
 Besides, it is quite possible that the sounds of the diaphragm may 
 
272 APPENDIX. 
 
 appear to be stronger and more distinct, because it is nearer to the 
 ear than the magnet, and because the effects of magnetization and 
 demagnetization are then more easily produced in consequence of 
 the mass of the magnetic body being smaller. 
 
 Mr. Fleemiug Jeukin goes on to say that the question of the dis- 
 placement of surface in the diaphragm and magnet is very com- 
 plex, but that he thinks it impossible to deny the existence of such 
 displacement, since the air which acts as the vehicle of sound be- 
 tween the ear and the source of sound is placed in vibration ; yet 
 this displacement may be effected quite otherwise than by flexion. 
 Suppose that the magnetic molecules of these bodies are drawn to- 
 gether by magnetization, which tends to diminish the iutermolecu- 
 lar space which separates them, the points of surface of the sub- 
 stance corresponding to these intervals will be elevated in a man- 
 ner equivalent to a displacement of surface, and the effect of this 
 will be the same as a flexion movement. At the moment of de- 
 magnetization a depression instead of an elevation will take place, 
 and the vibratory movements will thus be produced without any 
 electro -magnetic attraction, and it is precisely these vibrations 
 which Mr. Fleeming Jenkin terms molecular vibrations. He evi- 
 dently does not mean that such attractions cannot take place: 
 they may react, together with the molecular vibrations, when the 
 electric force is capable of producing them. He adds that the re- 
 production of sounds by a condenser, by simple coils, and by a car- 
 bon microphone, has convinced him that the action just analyzed 
 requires generalization. 
 
 We have recently seen an article by Mr. Hughes in the Tele- 
 graphic Journal, Nov. 15th, 1878, in which, to our surprise, he not 
 only opposes all the theories he has hitherto held, but cites experi- 
 ments which are quite inconclusive, since they were performed un- 
 der conditions in which electro-magnetic effects must necessarily 
 be displayed. He made use of voltaic currents produced by a bat- 
 tery of three Daniell cells. In order to estimate the transverse ef- 
 fects resulting in such a case from attraction, the experiments ho 
 mentions are wholly unnecessary : they may be felt with the hand. 
 On the other hand, he has evidently forgotten that the currents 
 employed in a Bell telephone have no influence on a very sensitive 
 galvanometer. 
 
 M. Pollard's Microphone. This microphone, which has been ar- 
 ranged in several ways, essentially consists of a carbon rod kept in 
 a horizontal position by a wire, and resting on two other vertical 
 carbons. The upright of the arm which holds the wire can revolve 
 
APPENDIX. 273 
 
 together with this arm, and is thus able to regulate the pressure of 
 the horizontal carbon on the two vertical carbons. It appears that 
 this instrument is extremely sensitive, and that the regulation ef- 
 fected on the two contacts is better than when it is effected on one 
 only. It is fair to add that M. Voisin previously sent me the sketch 
 of a somewhat similar arrangement. 
 
 M. Dutertre has also made use of such an arrangement in what 
 he calls the Dolmen microphone. Three pieces of coke in the form 
 of a dolmen, that is, two uprights, supporting a third and horizon- 
 tal carbon, are placed in circuit. M. Gouault has informed me that 
 speech was well transmitted by this instrument, and it is, like that 
 of Mr. Blyth, which succeeded it, of wonderful simplicity. 
 
 This microphone, as well as one composed of two pieces of lead- 
 pencil placed in a watch-case, and connected by a piece of money, 
 were exhibited to the Industrial Society at Rouen, February 1st, 
 1878, of which an account was published in the Bulletin of that 
 society. 
 
 M. Adc^s Electrophone. M. Ader has recently constructed a re- 
 markable telephonic instrument, which reproduces speech and song 
 in a quite exceptional and simple way. It consists of a drum fif- 
 teen centimetres in diameter, covered with parchment at one end 
 only. Six small tin armatures, one centimetre in length and two 
 millimetres in width, are fixed in the centre of the parchment in a 
 circle six centimetres in diameter. Six microscopic electro-mag- 
 nets, whose distance from the armatures can be regulated by a 
 screw, are placed opposite the armatures within a wooden circle. 
 The magnets are horseshoe, with branches twelve millimetres long 
 and four millimetres in diameter, including the coils, and the mag- 
 netic core is one and a half millimetre thick. They are all in con- 
 nection, and act simultaneously under the sole influence of the bat- 
 tery current. The sender is the same as that of M. Ader described 
 before. With this instrument speech may be heard at a distance 
 of six or seven yards, and songs are much more distinctly heard 
 than in the singing condenser. Owing to the simplicity of the ar- 
 rangement, the instrument is not costly. 
 
 The extraordinary effects of this telephone are due to the small 
 size of the electro -magnets, which, as we believe, produce much 
 more rapid magnetic effects than those of larger size. M. Ader has 
 also made a small ordinary telephone based on this principle, of 
 which the sounds are much stronger than in others. 
 
 Modification of Bell Telephone. Mr. Gower has recently made a 
 new system of telephone without a battery, which not only repro- 
 
 12* 
 
274 APPENDIX. 
 
 duces speech loudly enough to he heard at the distance of eight or 
 nine yards from the instrument, but will also transmit it when the 
 speaker is at a moderate distance from the sending instrument. In 
 this latter case, indeed, the receiving telephone must he brought 
 close to the ear. Although this double problem had already been 
 solved by the use of telephones with microphonic senders, the re- 
 sults furnished by the instruments in question are still more curi- 
 ous, since they are obtained without batteries, and are even more 
 distinct. 
 
 In this new system, which is only an improvement on Bell's 
 square model, the horseshoe-magnet is of a peculiar form, which 
 renders it more powerful. It is formed of a kind of half-circle of 
 magnetized steel, with its two ends turned back, so as to form a 
 diameter of the circle, only this diameter is divided in the centre : 
 so that the two poles of the magnet are placed one before the 
 other, as in Faraday's electro-magnet. The poles are tipped with 
 iron, terminating in front in two thin iron plates, on which are 
 placed the electro-magnetic coils, which are oblong, and constitute 
 the magnetic core. The diaphragm, thicker than the ordinary 
 diaphragms, is of tin, and is fixed firmly to the edges of the circular 
 box which encloses the whole, and which forms a kind of sounding- 
 box. The box is made of copper, and the diaphragm is so firmly 
 fastened to it as to become homogeneous with it, and to give out a 
 sound when the box is touched, which is not the case in ordinary 
 telephones. This is one of the conditions which make the instru- 
 ment a better conductor of sound. The magnetos also much more 
 powerful. It is magnetized by a current from a powerful Gramme 
 machine, which acts upon it for almost twenty minutes. The in- 
 strument has, strictly speaking, no mouth-piece : the lid of the box 
 which supports the diaphragm, and is separated from it by a space 
 of two millimetres, has merely a hole bored in it above the centre 
 of the diaphragm, and into this hole either a tin trumpet, fifty cen- 
 timetres in length, is screwed, when the instrument is required to 
 reproduce or transmit speech to a distance, or an acoustic tube 
 when it is to be used like an ordinary telephone. The remarkable 
 part of the system is that the instrument can itself give a very 
 loud call by only breathing into it instead of speaking. 
 
 For this purpose a small oblong opening is made in the dia- 
 phragm at a half diameter from its centre, and behind this the reed ' 
 of an harmonium is applied to a square copper plate fixed on the 
 diaphragm itself. On using the bellows the expelled air passes 
 through this little hole, and, on reaching the reed, sets it in vibra- 
 
APPENDIX. 275 
 
 tion, and produces a sound of which the acuteuess depends on the 
 conditions of the vibrating plate. This addition to the diaphragm 
 in no way alters its properties in the reproduction of speech, so 
 that, after using the bellows, conversation may begiu, and the re- 
 ceiving telephone repeats what is said after emitting a sound some- 
 what resembling the note of a bugle. The instrument is then pro- 
 vided with the speaking-tube of which we have spoken. 
 
 Nothing can be more remarkable than this power of listening to 
 conversation while seated in an arm-chair six or seven yards from 
 the instrument, nor is it necessary to move in order to reply. The 
 correspondent, indeed, must be close to the acoustic tube in order 
 to speak and listen, and he must speak rather loud in order to bo 
 heard at any distance from the other station. But the listener 
 receives the sounds so amplified that it might be supposed that a 
 giant was speaking, and conversation held in a low tone may even 
 be distinguished. These results are really extraordinary, and even 
 to those familiar with such effects this incessant progress is sur- 
 prising. 
 
 These results may be ascribed to the following causes: 
 
 1. First, that the conditions of the magnet are better than those 
 of ordinary instruments. 
 
 2. That the diaphragm is also thicker, larger, and better stretched. 
 
 3. That the box is of metal, and calculated to act as a sounding- 
 box. 
 
 4. The speaking-trumpet magnifies the sounds. 
 
 5. The acoustic tubes concentrate the sound waves on the centre 
 of the diaphragm. 
 
 Note on some fresh Experiments with Telephones without any 
 Diaphragm. 
 
 In a paper published March 4th, 1878, 1 made some suggestions 
 on the theory of the sounds produced in the telephone, and on the 
 contradictory assertions of physicists as to the transmission of 
 speech by ordinary telephones when devoid of diaphragm. These 
 remarks induced M. Ader to undertake some experiments which 
 not only demonstrate the truth of my opinion, but bring to light 
 some fresh facts which may be of great importance to acoustic 
 science. 
 
 M. Ader has in fact not only succeeded in making a telephone 
 without a diaphragm speak, but he has made it speak more loudly 
 
27G APPENDIX. 
 
 aud with less alteration of the voice than we find to be the case 
 with a small model of the ordinary telephone. No one, therefore, 
 can now maintain that the sounds produced by the magnetic cores 
 are so faint that they cannot be taken into account among the 
 effects produced, and that it is at any rate impossible for them to 
 reproduce articulate sounds. 
 
 To obtain this result, M. Ader reduced the size of the magnetic 
 core to that of a simple iron wire, one millimetre in diameter, and 
 ho fastened it by one of its ends to a small wooden board. Under 
 these conditions, it was enough to fasten a small helix of fine wire 
 on this iron wire, aud to apply the board to the ear in order to hear 
 speech distinctly, with the aid of a microphonic speaker actuated 
 by a voltaic current. But the range of sound was considerably 
 increased if a mass of metal was applied to the free end of the iron 
 wire : in this case it was possible to hear when the wooden board 
 was removed to a distance of ten or fifteen centimetres from the 
 ear. 
 
 If the wire is in contact with masses of metal at each end, the 
 effect is further increased ; but the two masses must not be in me- 
 tallic communication with each other, and must bo to some extent 
 insulated by a more or less elastic medium. If the metallic masses 
 are soldered to the wire, the effects are still greater. 
 
 M. Ader was also able to reproduce speech by using a simple coil 
 without a magnetic core, but in this case the spirals must be open, 
 aud not pressed together. If they are steeped in gum, no sound is 
 heard, but speech will become instantly audible if a wire or a mag- 
 netized needle is inserted in the coil, or even if a second metallic 
 helix is placed in the circuit : always provided that one of the 
 ends of these magnetic organs rests upon, or is fastened to, the 
 board on which the coil is fixed. 
 
 M. Ader has likewise obtained a very distinct reproduction of 
 speech at a distance of two or three yards from the instrument by 
 inserting between the two stretched membranes of two tambou- 
 rines a bent wire which acts as a spring aud passes through an 
 electro-magnetic coil. Under these conditions, magnetization of 
 the wire in a greater or less degree affects its elasticity and causes 
 vibrations which are magnified by the membranes, and transmitted 
 sounds are reproduced with intensity. Unfortunately, articulate 
 speech is less distinct with this system than with the one I de- 
 scribed before. 
 
 M. Ader has often had occasion to make one curious remark, 
 namely, that the timbre of the voice and its high or low key varies 
 
APPENDIX. 277 
 
 with the degree of tension given to the wire; but if the funda- 
 mental note of the wire is deadened by pressing it between the 
 fingers, the sounds reproduced then become dull and monotonous. 
 They are also somewhat fainter. 
 
 Signer Carlo Resio has also observed that in a telephone sender 
 the variations of intensity in the current correspond with the vi- 
 brations caused by speech, and these are reproduced by correspond- 
 ing variations in a liquid column, which may thus act as a tele- 
 phone receiver, and consequently may reproduce speech without 
 any electro-magnetic organ, as in a microphone-speaker. Under 
 these conditions, however, a layer of water is inserted between the 
 platinum electrodes and the surrounding air, and consequently this 
 liquid layer must be put in vibration under the influence of vary- 
 ing intensities of current. 
 
 Mr. Edison has also now made a practical application of the 
 chemical telephone we have mentioned before. The trials made 
 with it have been very satisfactory, showing that sounds transmit- 
 ted in this way can be heard in a large room. 
 
 THE END. 
 
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