THE ENGINEER

JUNE 21, 1878

We have often referred to this beautiful apparatus, but since its introduction to this country several improvements have been made, the latest form being that shown in the accompanying illustrations. The apparatus from which our illustrations are taken is not, however, in England, but at Paris, and we have every reason to believe that we here show the very latest development of the instrument. The phonograph proper is simply a cylinder B, Fig.2, supported on the screw shaft C. The cylinder B has a grooved surface- in fact, is a screw of larger diameter of the same pitch as C. Originally the machine was turned by hand, but the inconvenience of this was great, and the results obtained not at all satisfactory. Mr. Edison has added a clockwork action, with an excellent regulator, as shown in the drawings. The mouthpiece E opens on a diaphragm A, on the further side of which is mounted an agate point. In order to prepare for active operations the cylinder B is covered with tin foil, the agate point brought accurately into a position, which may be regulated to a nicety by the screw S. The heavy brass piece M, which carries the diaphragm and mouthpiece, runs in guides, and is approximately put in position by hand. Winding up the weight which activates the clockwork, and lifting the clamp O, the cylinder rotates uniformly, governed by the flat plate air resistance governors shown. If now the voice be directed on the diaphragm through the mouthpiece, a series of vibrations of the diaphragm occurs, and the agate point makes a set of indentations in the tin foil more or less deep according to the strength of the sound wave. The mouthpiece used when speaking is small, Fig.1, as the nearer the voice is to the diaphragm the more satisfactory the result. The mouthpiece T, Fig.1, allows two voices to speak, or a duet to be sung, and two series of indentations to be made and reproduced at one and the same time. The larger mouthpiece C, Fig.1, is used when reproducing the sounds. To do this the agate point is moved to its original position on the cylinder, a small spring keeping it in close contact. When the cylinder revolves the point enters the indentations previously made, and reproduces exactly the original vibrations in the diaphragm, and hence similar sound waves. Of course the reproduced sounds are feebler than the original ones, but Mr. Edison has, we believe, managed to invent an instrument that will magnify the sounds, so that it is simply a question of apparatus how loud the reproduced sound can be. The utility of the phonograph can be better imagined than described. One eager philologist desires to obtain specimens of all the Indian dialects of North America, and we can well imagine the extraordinary interest with which we should invest the instrument if we had a number of indented pieces of foil stored up from Chaldean, or those far off centuries, when the original Aryan tribe luxuriated in tent life in the center of Asia.

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