PHONOGRAPH. This apparatus, invented in 1877 by Mr. Thomas A. Edison, an American electrician of note, differs from the vibrograph and phonautograph. The latter are constructed to record sound vibrations graphically, while Mr. Edison's inven tion, which is properly called the " talkino. phonograph," is designed to obtain such a record that the sound vibrations resulting from articulate speech can be mechanically reproduced at a distance of time. The invention, at the time these words arc written, is only in the experimental stage, and it has been successfully exhibited both in America and in Britain. As originally made, the instrument consisted of three parts—the sender, the receiver or recorder, and the transcriber; but in the phonograph exhibited by pro-1 fessor Fleeming Jenkin before the royal society of Edinburgh, the last apparatus was dispensed with, the sender being constructed to fulfill both functions. This sender con sists of a tube, having an open mouth-piece at one end, and bearing at the other end a thin diaphragm of metal or other substance, with a sharp point or style affixed to the center of its outer surface. The second apparatus consists of a cylinder, about 4 inches in diameter, having on its periphery a V-shaped groove cut spirally from end to end. Over this grooved cylinder a sheet of tinfoil is placed, and the sender is advanced till the point of the style lightly touches the tinfoil, over the opening of the V-shaped cut. While the words to be recorded arc spoken or sung, the cylinder is turned rapidly, the apparatus for moving it giving a literal as well as a circular motion. The point of the style thus traverses the tinfoil spirally from end to end, and the vibrations in the dia phragm caused by the sounds result in a series of indentations in the tinfoil. To reproduce
the sounds in the "transcriber" (or in the "sender" under professor Jenkin's arrange ment), the cylinder is again presented to a style attached to a diaphragin, the style being pressed against the tinfoil by a slight spring. The cylinder is now made to revolve, and the motion of the style upon the inequalities in the indented tinfoil produce vibrations in the diaphragm corresponding to the sound-caused vibrations originally created in the instrument by the voice. The sounds are thus reproduced with great exactness, but with a softening of the to some extent alters the chameter of the voice. If the. tinfoil record of sung or spokeu,Words be sent to a distance, or kept for a length of time, tlte original sounds can be reproduced on applying it to the proper instrument. It is stated that rubbings in tinfoil can be taken from a plaster-cast of the original indented slip, so that copies may be sent to different persons, all of whom can thus original the sounds so long as their tinfoil copy remains intact. In using the phonograph to repeat sounds, the cylinder must be revolved at the same speed as at first, Otherwise the pitch will he changed. For as sound is the result of air-vibrations at known intervals, if a speech spoken in a high key were reproduced slower at the repeating instrument, the result would lie to convert a treble voice into a bass one, or vice versa, while the lower speed would convert smartly spoken words into a drawl.
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