THE PHONOGRAPH.

Thames Star, Volume VIII, Issue 2836, 18 March 1878, Page 3

THE PHONOGRAPH.

Not mimy weeks have passed since wo were startled by the announcement that we "could converse audibly with eiich other, although hundreds of miles apart, by means of so many miles of wire with a little electro magnet nt each end, yet we are on tlte point of realising some of the many advuntiißes promised by the tele, phone. Another wonder is now pronrscd us—an invention, purely mechanical in its nature, by means of which words spoken by the human voice can be, so to speak, stored up and reproduced nt will over and over again, hundreds, it may be thousands, of timeß. What will be thought of a piece of mechanism by means of which a message of any length can be spoken on to a plate of metal, that plate sent by post to any part of the world, and the message absolutely reipolten in the very voice of the sender purely by mechauical agency ? What, too, shall be said of a mere machine by means of which the old familiar voice of onerwho is no longer with us on earth can be heard speaking to us in the Tery tones and measures to which, our ears were once accustomed ?

The highly ingenious apparatus by which the wonder is effected is the invention of Mr Thomas A. Edison, of Jianlowepark, New Jersey, U.S.A., the electrical adviser to the Western Union Telegraph Company. Mr Edison is well known in the States, and scarcely less so in England, for several valuable practical applications of-electric science, among Mr Kdison's other invention being an exceedingly well-arranged telephone. To the present invention Mr Edison has given the name of the Phonograph, and it depends for its action upon certain well known laws in acoustics.

The Phonograph is composed of three parts mainly—namely, a receiving, a recording, and a transmitting apparatus. The receiving apparatus consists of a «urved . tube, one end of which is fitted with a mouthpiece for the convenience of speaking into it. The other end is about two inches in diameter, and is closed in with a disc or diaphragm of exceedingly thin metal, capable of being thrust slightly outwards or vibrated upon, a gentle pressure being applied to it from within the tube. To the centre of this diaphragm—which forms a right angle to the horizon—is fired a small blunt steel pin, which, of cpurse, partakes of the vibratory motion of the diaghragm. This arrangement is carried on a table and is fitted with a set screw by means of which it can be adjusted relatively to the second part of tbe apparatus —the recorder. This is a brass cylinder, about four inches in length and four inches in diameter, cut with a continuous V groove from one end to the other, so that in effect it represents a large screw. Measuring along this cylinder from one end to the other there are 10 of these groves to the inch, or about 40 in the whole length. The total length of this continuous groove or screw thread, is about 42 feet—that is to say, that would be the length of the grove if it were stretched out in a straight line. This cylinder is mounted on a horizontal axis or shaft, carried in bearings at either end, and having its circumferential face presented to the steel point of the receiving apparatus. The shaft is prolonged for four inches or so beyond.the ends of > the cylinder^ and one of the prolongations is cut with a screw thread and works in a screwed bearing. This end terminates in a handle, and as this is turned round the cylinder is not only revolved, but by means of the screwed spindle is caused to travel its whole length in front of the steel point, either backward or forward. We now see that if the pointer be set in the groove in the cylinder at its commencement and the handle turned, the groove would be traversed over the point from the beginning to the end, or, conversely, the point would always be presented to the groove. A voice speaking in the receiver would produce waves of sound which would cause the point to enter to greater or less depths into this groove, according to the degree of intensity given to the pressure upon the diaphragm set tip by the vjbrations of the sound produced. Thia, of course, of itself would mean nothing; but in order to arrest and preserve these sonnd-pressures, a sheet of tinfoil is iriterposed.the foil being inelastic and well adapted for receiving impressions. This sheet is placed around the cylinder and its edges lightly fastened together by mouth-glue, forming an endless band, and held on the cylinder at the edges by the india-rubber rings. If a person now ipeaks into, the receiving tube and the handle of me cylinder be turned, it; will be seen that the vibrations of the pointer will be impressed tfpoh that portion of the tin-foil over, the hollow groove and retained by it. These impressions will be more or less deeply marked according to the-modulations and inflexions of the speaker's voice. We have now a message verbally imprinted npon a strip of metal. Bound has,'in fact, been concerted into risible, form, and we have now to translate that message by reconverting it into •ound. We are about, in effect, to hear our own voice speaking from a machine the words which have just fallen from our lips. To do this we require the third portion of Mr Edison's apparatus—the transmitter.

,-:,,! This consist* of what may be called a conical metal drum, having its larger end open, the smaller end, which is about SU». in diameter, being covered with paper, -tvlbich is stretched taut as is the parchment of a drum-head. Just in front of this paper diaphragm is a light, flat steel spring, held in a vertical position arid terminating in a blunt steel point projecting from it, and corresponding with that on the diaphragm of the receiver. The spring is connected with the paper diaphragm of the transmitter'by means of a silken thread, which is placed just sufficiently in tension to cause the outer face of the diaphragm to assume a. slightly ,:, convex form. This apparatus is placed on the opposite side of the cylinder to the receiver. Having set tbe latter apparatus back from the cylinder, and having, by turning the handle in a reverse direction, set the cylinder back to. what we may term the zero point, the transmitting apparatus is advanced towards the cylinder by means of a set screw until the steel point rests wiiboufc absolute pressure in the first indentation made by the point of the receiver. If now the handle be turned at the same speed as it was when the message was being recorded, the steel, point will follow the line of impression and will vibrate in periods corresponding to the impressions previously produced on the foil by the point of the receiving apparatus. Vibrations of the requisite number and depth being thus communicated to the paper diaphragm there will be produced precisely the same

sounds that in the first instance' were required to produce the impressions formed on the tin-foil. Thus th« words of tho speaker will be heard issuing from the conical drum in his own voice, tinned, however, with a sliuiit metalic or mechanical tone. If the cylinder l>e revolved more slowly than when tbe message was being recorded, the voice assumes a bnss tone ; if more quickly, the message i« given with n childish treble. TJ I*^1 *^ variations occur accord'np us the vibrations are more or less frequi'uh

Such is the apparatus, and it promises t<i one of the most remarkable of the recent marvels of science. The machine we have rfrscrihrd is the fir.<t Mr Kdisun has made, but he is now constructing one to be set in motion by flock-work, the cylinder being 16 inches long. In the present machine, for recording a long message, as soon as one strip of the tin foil is filled, it is removed and replaced by others until the communication has been completed. In using the machine f<>r the purpose of correspondence the metal strips are removed from the cylinder and sent to the person with whom the speaker desires to correspond, and who must possess a machine similar to that used by the sender. Tho per«on receiving tbe strips places them in turn on the cylinder of bis apparatus, applies the transmitter, and puts the cylinder in motion, when he hears his friend's voice speaking to him from the indented metal. And he.can repeat the contents of the misiive as often as; he pleases until he has worn the metal through. The sender can make an indefinite number of copies of his communication Ly taking a plaster of Pariscast of the original strip end rubbing off impressions from it on a clean sheet of foil. It will thus be seen, as we stated at the commencement of this article, that the voices of those who have left ns, either for ever or for a season only, can be heard talking with us if wo so desire it. The invention has been so recently and sO quickly developed into existence by Mr Edison that he himself can hardly say what its practical value is or will prove to be. Numerous applications suggest themselves, but beyond those to which we have alluded, it is difficult to say with precision how they would work out in practice. In cases of depositions it might be of the highest importance to have oral evidence mechanically reproduced in- a court -of justice. Authors, too, may perhaps be saved the trouble of writing their compositions.— The Times.