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To serve as an ear, the telephone must be able to take up quickly and nicely the sound-waves of the air. A tightened drum-head will do that; or better, a strip of goldbeaters'-skin drawn tightly over a ring or the end of a tube.
He said to himself, "The sound of my voice will give motion to a thin plate of iron as well as to a sheet of goldbeaters'-skin; and if I bring this vibrating plate of iron close to a magnet, the motion will set up in it waves of electricity answering exactly to the sound-waves which move the iron plate." So far, good. But something more was wanted.
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