Transcriber’s Note: Italics are enclosed in _underscores_. Additional
notes will be found near the end of this ebook.
THE
TELEPHONE, MICROPHONE, & PHONOGRAPH
THE TELEPHONE
THE MICROPHONE & THE PHONOGRAPH
BY
COUNT DU MONCEL
MEMBRE DE L’INSTITUT
_AUTHORISED TRANSLATION
WITH ADDITIONS AND CORRECTIONS BY THE AUTHOR_
WITH 70 ILLUSTRATIONS ON WOOD
_FOURTH EDITION_
LONDON
KEGAN PAUL, TRENCH, TRÜBNER, & CO. LTD.
PATERNOSTER HOUSE, CHARING CROSS ROAD
1892
(_The rights of translation and of reproduction are reserved_)
_CONTENTS._
PAGE
History of the telephone 1
_MUSICAL TELEPHONES._
Reiss’s telephone 11
Wray’s telephone 15
Electric harmonica 18
Gray’s telephone 21
Pollard and Garnier’s singing condenser 26
_SPEAKING TELEPHONES._
String telephones 31
Bell’s electric telephone 35
Gray’s share in invention of telephone 62
_FUNDAMENTAL PRINCIPLES OF BELL TELEPHONE._
Explanation of principles 67
_ORDINARY ARRANGEMENT OF BELL TELEPHONE._
Description and illustrations 71
_BATTERY TELEPHONES._
Edison’s telephone 83
Edison’s chemical telephone 90
Navez’ telephone 93
Pollard and Garnier’s telephone 97
Hellesen’s telephone 100
Thomson and Houston’s telephone 101
Telephones with liquid senders 103
Telephones with voltaic arcs 107
Mercury telephones 110
Friction telephones 113
_MODIFICATION OF BELL TELEPHONES._
Telephones with several diaphragms 114
Gray’s system 118
Phelps’s system 118
Cox Walker’s system 121
Trouvé’s system 121
Demoget’s system 124
Mac Tighe’s system 125
Modifications of telephonic organs 125
Righi’s system 126
Ader’s system 129
Jorgenson’s system 131
_EXPERIMENTS WITH THE TELEPHONE._
On the effects of voltaic and induced currents 132
On the effects of different telephonic organs 139
Edison’s experiments 140
Canestrelli’s experiments 142
Hughes’s and Roy’s experiments 143
Bréguet’s experiments 149
Luvini’s experiments 149
Warwick’s experiments 151
Experiments on the effects of mechanical shocks 154
Des Portes’ experiments 154
Thompson’s experiments 158
Theory of telephone 159
Nature of vibrations 160
Action of diaphragm 163
Action of magnet 167
Action of currents 169
Wiesendanger’s thermophone 171
_OTHER EXPERIMENTS WITH THE TELEPHONE._
D’Arsonval’s experiments 173
Eick’s experiments 175
Demoget’s experiments 176
Sensitiveness of telephone 179
Hellesen’s experiments 180
Zetsche’s experiments 181
_THE MICROPHONE._
History of microphone 182
Different systems 187
Hughes’s microphone 188
Gaiffe’s system 190
Carette’s system 191
Ducretet’s system 192
Ducretet’s speaker 193
Boudet’s speaker 195
Gaiffe’s thermoscope 197
Blyth’s system 199
Microphone as a speaking instrument 200
Hughes’s system 203
Other arrangements of microphones 205
Varcy’s and Trouvé’s microphones 207
Lippens’s microphone 209
Hughes’s experiments 211
Hughes’s theory 215
Microphone used as thermoscope 217
Edison’s thermoscope 219
Experiments in London 220
Experiment at Bellinzona 223
_APPLICATIONS OF MICROPHONE._
Its application to scientific research 226
Application to telephonic relays 229
Application to surgery 232
Various applications 236
_EXTERNAL INFLUENCE ON TELEPHONIC TRANSMISSIONS._
Disturbing influences 239
Confusion of circuits 241
Induced reactions 243
Mr. Preece’s suggestions 245
Effects of heat and moisture 249
_ESTABLISHMENT OF TELEPHONE STATION._
Pollard and Garnier’s system 252
Bréguet and Roosevelt’s system 254
Edison’s system 257
_CALL-BELLS AND ALARUMS._
Weinhold’s system 262
Dutertre and Gouault’s system 264
Puluj’s system 266
Chiddey’s system 267
_APPLICATIONS OF TELEPHONE._
Its application to simultaneous transmissions 270
Bell’s system 273
Lacour’s system 276
Gray’s system 282
_VARIOUS USES OF THE TELEPHONE._
Its use in offices 293
Its use in telegraphic service 294
Its application to military purposes 297
Its application to industry 302
Its application to scientific research 303
_THE PHONOGRAPH._
Edison’s patent 309
Description of phonograph 313
Several systems 322
Theory of phonograph 327
_USES OF PHONOGRAPH._
Account by Edison 333
Lainbrigot’s system 339
_FABER’S SPEAKING MACHINE_ 341
_APPENDIX._
Perrodon’s system of telephonic alarum 351
Varey’s microphone speaker 352
Fitch’s microphone speaker 353
Theory of telephone 353
Pollard’s microphone 356
Ader’s electrophone 357
Gower’s new telephone 358
Transmission of speech by telephones without diaphragm 360
THE TELEPHONE,
_&c._
_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
somewhat 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 Robert 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 multiply’d. And though some famous authors have affirm’d
it impossible 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 thoroughly 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 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 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 employed 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 correspondence
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 subsequent to 1839. A surprising
discovery made in America by Mr. Page, in 1837, and afterwards
investigated by MM. Wertheim, 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 magnetised and demagnetised, and these sounds corresponded
with the number of currents which produced them. Again, the electric
vibrators devised by MM. Macaulay, Wagner, Neef, etc., and adapted
to produce musical sounds, between 1847–1852, by MM. Froment and
Pétrina, showed that the problem of transmitting sounds to a distance
was not insoluble. Yet, up to 1854, no one had ventured to admit the
possibility of transmitting speech by electricity, and when M. Charles
Bourseul published in that year a paper on the electric 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, I felt bound to add that the scheme seemed more
than doubtful. Yet, as the paper was thoughtfully written, I had no
hesitation in publishing 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 reason I will again
quote M. Charles Bourseul’s paper.
‘After the telegraphic marvels which can reproduce at a distance
hand-writings, or even more or less complicated drawings, it may appear
impossible to penetrate further into the region of the marvellous. Yet
we will try to advance a few steps further. I have, 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 vibrations 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 moveable disk, sufficiently flexible to lose none
of the vibrations of the voice, that this disk alternately makes and
breaks the currents from a battery: you may have at a distance 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 _à
priori_ if this will be precisely the case with syllables uttered by
the human voice. The mode in which these syllables 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 intervening 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 utopian, and yet there is now direct
communication between London 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 highest
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 apparatus, except an electric
battery, two vibrating disks, and a 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. _I have made some experiments in this
direction_: they are delicate, and demand time and patience, but _the
approximations obtained_ promise a favourable result.’
This description is certainly not full enough to enable us to
discern from it the arrangement which would lead to the solution
of the problem, and if the vibrations of the disk at the receiving
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 realise 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 musical 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 discovery which
seemed to be then only within the range of fancy.
It was not until 1876 that the problem of the electric transmission of
speech was finally solved, and the discovery has lately given rise to
an interesting controversy as to priority between 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 system of
musical telephone, which he wished to apply to manifold 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 transmitting articulate words by
electricity. While carrying on his experiments 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 Patent 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 American 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 telephonic apparatus; and the few words
which could, in this specification, refer to a telephone with
articulate sounds, applied to an instrument which, by Mr. Bell’s own
admission, had not produced any satisfactory results. In Mr. Gray’s
_caveat_, on the contrary, the application of the instrument to the
electric transmission of speech alone is indicated, the description
of the system 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 afterwards, 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, which, as we know, decides the priority of inventions
in America. An action on the ground of this omission has lately been
brought against Mr. Bell, in the Supreme Court of the American 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 Philadelphia, which has from that
time attracted so much public attention, 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 priority 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
telephone. A similar pretension has been put forward by Mr. Dolbear, a
fellow countryman 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 newspapers of 1865, among
others in ‘Le Petit Journal,’ of Paris, on the 22nd November, 1865;
‘Il Diritto’ at Rome, 16th July, 1865; ‘L’Echo d’Italia,’ New York,
9th August, 1865; ‘L’Italia,’ Florence, 10th August, 1865; ‘La Comuna
d’Italia,’ Genoa, 1st December, 1865; ‘La Verità,’ Novara, 4th January,
1866; ‘Il Commercio,’ Genoa, 6th January, 1866. It is true that no
description 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 transmitting 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 modifications
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 applications, 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 reproduction
of sound is concerned, based upon Mr. Page’s discoveries 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 composed, like telegraphic systems, of two distinct
parts, a sender and a receiver, as represented in fig. 1.
[Illustration: 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 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.
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 telegraphic 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 sounding-box: for this purpose the box is provided
with two openings 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 vibrations of air occasioned by these
instruments cause the telephonic membrane to vibrate in unison, and the
latter, rapidly moving the platinum disk _o_ to and from the point
_b_, 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 produced.
According to this mode of action, the possibility of transmitting
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 _timbre_ 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 technical 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 transmitting vocal melodies, and not merely
musical sounds. The system was afterwards perfected by M. Van der
Weyde, who, after reading the account published by M. Heisler, sought
to make the box of the sender more sonorous, and to strengthen 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 transmitted 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 receiver, 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 invention contained the germ of a new method of telegraphic
transmission which might lead to important results.’ This opinion was
soon afterwards justified by the discoveries of Bell and Elisha Gray.
_Messrs. Cecil and Leonard Wray’s 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 produced. 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 magnetising 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. 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 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.
[Illustration: FIG. 2.]
[Illustration: FIG. 3.]
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 upper surface of the box, which
consequently appears to be somewhat oblique. The second membrane G,
which is of caoutchouc, 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 immersed in two small cups, filled with
mercury, and connected with the circuit. In this way, the movements of
the membrane 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.
_Electric Harmonica._--Long before M. Reiss’s invention, and
consequently still longer before that of Mr. Elisha Gray, I mentioned
a sort of electric harmonica, and described it as follows in the first
edition of my ‘Exposé des applications de l’Electricité,’ published in
1853:--
‘The power possessed by electricity to set metallic plates in motion
and cause their vibration has been used for the production of distinct
sounds, which can be combined and harmonised; but in addition to this
purely physical application, electro-magnetism has come to the aid
of certain instruments, such as pianos, organs, &c., 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-breaker. It is, as
we know, an iron disk, soldered 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 current. 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
magnetism 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 unpleasant to the ear.
‘M. Froment has not applied the apparatus to a musical instrument,
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 required 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 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 difficult in practice. These kinds of instruments are
therefore only used as a means of regulating by ear the force of the
battery, 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. Pétrina, of Prague, invented an analogous arrangement,
to which he gave the name of electric harmonica, although, strictly
speaking, he had not thought of it as a musical instrument. This is
what I have said on the subject in vol. iv. of the second edition of my
‘Exposé des applications de l’Electricité,’ 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 capability
possessed by these instruments of being played at a distance; but
this idea was quite legitimate, and German periodicals assert that it
was accomplished by M. Pétrina 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, &c., _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.
_Telephone by Mr. Elisha Gray, of Chicago._--This system, invented in
1874, is in reality only an instrument of the nature of those which
preceded it, but with important modifications, 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 vibrations 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 an harmonium, an accordion, or any other instrument with
blowers. 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 connected with them, and the secondary
currents which arise in the coil, in consequence of the interruptions
in the primary currents, transmit the corresponding vibrations to a
remote receiver. 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 induction 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 molecular motion which takes place in the magnetic core and
its armature, under the influence of alternate magnetisation and
demagnetisation, 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.
[Illustration: 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 sending 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
moreover made a different arrangement of this telephonic system, 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 transmitted by
the secondary currents would be capable, by the intervention of the
human body, of causing the sounds to be reproduced at a distance
by conducting disks, which vibrate readily, and are placed on a
sounding-box. In this way musical 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 precise number of vibrations which belong
to it.[1]
_Mr. Varley’s 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
tinfoil, divided by sheets of some insulating material, and with a
surface of about half 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 communicate 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
contact 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. Varley to produce these interruptions are
the same which are in use in several electrical instruments, 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 primary current of the induction coil;
if the number of the tuning-forks equals that of the musical notes
which are to be transmitted, and if the electro-magnets which set them
in motion are connected with the key-board of a piano, it would be
possible 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 Garnier._--This instrument, which
astonishes all who hear it, attracted public attention in London some
time ago. It is difficult to say why its fame was not greater, since
much attention has been bestowed on less curious instruments. It is
a fact that we have been able, thanks to MM. Pollard and Garnier, to
hear songs issue from a sort of copy-book, so as to become audible
throughout 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 resembling 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
centimètres in thickness: between these, twenty-eight sheets of
tinfoil, from six to twelve centimètres thick, are intercalated, 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 copy-book, 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 tinfoil 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.
[Illustration: FIG. 5.]
The sending instrument consists of a sort of telephone without 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 of a watch spring) placed across this piece of wood gives
it a certain elasticity beneath the pressure, and this elasticity is
necessary in order that the instrument may act properly, and it thus
becomes a sort of microphone with a diaphragm.
The tin plate is put into communication with one pole of a battery P,
of six Leclanché 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: Finally, the two extremities of the
secondary helix of the coil, _a_ and _b_, are in immediate connection
with the two plates D, D, of the condenser.
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 exceed seven centimètres
and the diameter of the core of fine iron wire ought to be about one
centimètre.
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 mouthpiece as it is applied to a reed pipe.
In order to obtain a satisfactory result, the disk of the instrument
must be heard to vibrate, as in a _flûte à l’oignon_. Instead of
carbons, contacts of platinum may be used; but when arranged 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 vibration 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 vibrations,
in greater or less number, it is true, but not in simultaneous
combinations like those which reproduce articulate sounds. Up to the
time of Mr. Bell’s invention, the transmission 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 object 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 invention was 1867,
are interesting in themselves, and we are surprised that they have not
hitherto taken a place in the collections of physical science. They
are made of two metal or cardboard 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 conditions 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.
[Illustration: FIG. 6.]
In some patterns, the tubes are so arranged as to present, between
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 membrane; but I have not observed
that this pattern is decidedly superior to the others.
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 interesting 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 mouthpiece.
_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 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. Bréguet 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. Bréguet has also invented a system of relays to accomplish the
same object. He makes the strings terminate in two membranes which
close the two openings of a brass cylinder. 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 1, 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 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, communication 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 Newcastle-on-Tyne,
have ascertained that the most effective wire was No. 4 of the English
gauge. They employed wooden disks ⅛ 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 insulating the line wire on glass
supports, was able to transmit speech for 2,450 feet, in spite of the
zigzags made by the line on its supports.