Page:Popular Science Monthly Volume 14.djvu/153

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EDISON'S ACOUSTIC INVENTIONS.
141

A downward movement lets the chamber communicate with the outlet H, an upward movement with the outlet G. The compressed air enters at A, and fills the chamber, which, in its normal position, has no outlet. Every downward vibration of the diaphragm will thus condense

Fig. 34.

the air in the pipe C, at the same time allowing the air in B to escape via F. An upward movement condenses the air in C, but opens I.

The third and last part is shown in section in Fig. 35. It consists of a cylinder and piston, P, like that employed in an ordinary engine.

Fig. 35.

The piston-rod is attached to the centre of a large diaphragm, D. The pipes C and B are continuations of those designated in Fig. 34 by the same letters. The pipe C communicates with one chamber of the cylinder, and B with the other. The piston, moving under the influence of the compressed air, moves also the diaphragm, its vibrations being, in number and duration, identical with those of the diaphragm in the mouth-piece.