Uses of the Phonograph and Its Future
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.