Mr. Edison has lately published in the ‘North American Review’ of May-June 1878 an article on the future of the phonograph, in which he himself discusses the different applications 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 complex 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 movement, 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 the fact that ... the writer has at various times during the past weeks reproduced these waves with such degree of accuracy in each and every detail as to enable his assistants to read, without the loss of a word, one or more columns of a newspaper article unfamiliar to them, and which were spoken into the apparatus when they were not present. The only perceptible 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 perceptibly 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.21
‘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 obstacle than having proper regard for the perfect interchangeableness 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 removing. 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 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 capable 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 success, 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 multiplication 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 mouthpiece 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 loud tone. The application of a flaring tube or funnel to collect the sound waves, and the construction of an especially delicate diaphragm and embossing point, &c., 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 following 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, 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 knowledge 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 purposes, except such as require special form of matrix, such as toys, clocks, &c., 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 clockwork underneath 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 clockwork set in motion, and the matter dictated into the mouthpiece without other effort than when dictating to a stenographer. It is then removed, placed in suitable form of envelope, and sent through the ordinary channels to the correspondent for whom it is designed. He, placing it upon his phonograph, starts his clockwork, and listens to what his correspondent has to say.’
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 19, 1878, as well as the aerophone, the megaphone, and the microtasimeter, which is adapted for astronomical 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 invention 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 opening in the middle of the slab, covered by a tightly stretched sheet of parchment bearing a steel knife, which, like the tracing point of the phonograph, is intended to trace the vibrations. 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 metallisation. By galvanism a deposit of copper is obtained which reproduces the 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 unlimited 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 vocabulary 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 obtain a strong impression, within a copper groove, of the vibrations 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 proportion to the difference of temperature. This is probably 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 tinfoil have also some effect.
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 exhibited by conjurors. In a country so essentially critical and sceptical as France, there are always those who profess incredulity, 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 papers echoed the absurdity, and the speaking machine was so discredited that it is now unnoticed, although it is a most ingenious and interesting conception. When will our country be cured of the error of denying everything without due examination?
Since we ourselves only judge of things after having seriously 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 between 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 stereotyping the vibrations of air necessary to transmit these sounds; but in order to produce them, and especially to emit the complex 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 diabolical invention.
Mr. Faber’s speaking machine was exhibited two years ago at the Grand Hôtel, and may now be seen in the room adjoining M. Robert Houdin’s theatre, the same room in which Mr. Giffard exhibited the telephone. It consists of three distinct 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; 2nd, a vocal instrument, consisting of a larynx accompanied by diaphragms of various forms to modify the sounds, of a mouth with caoutchouc lips and tongue, and of a tube with an outlet somewhat resembling the nasal cavities; 3rd, 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 projected 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 cylinder 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 keyboard 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.
The whistle, which plays the part of the larynx, is necessarily 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 keyboard, and the 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 mentioned 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.22
Below the larynx tube, which is only five centimètres in length, there is another pipe G, also of caoutchouc, which terminates 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 keyboard. When the valve is open, the sounds emitted through the larynx are somewhat nasal.23 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 diminish more or less the orifice for the current of air, and to impede its passage with greater or less force. The diaphragms, which we represent separately fig. 74, are connected with the keyboard by jointed iron rods t, and, for the emission of most articulate sounds, several of the diaphragms are moved at the same moment and at different heights. We shall return to this subject.
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 keyboard. The lower caoutchouc lip A can also be more or less closed, according to the action of the keyboard 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 f.
The keyboard has fourteen notes, of different lengths, producing the following letters when lowered, a, o, u, i, e, l, r, v, f, s, ch, b, d, g. The longest corresponds to g, and the shortest to 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 lowering 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 further 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, throws the tongue further back, and opens the mouth still more.
6. l moves five diaphragms, sends the tongue against the palate, and further 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. f 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 further 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.
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 distinct, they are spoken in a uniform, drawling tone, which might, I should have thought, have excluded the idea of imposition. 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 surprising 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 keyboard, 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 purpose, the notes of the keyboard 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 keyboard 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.