human
The telephone hears and speaks; why not make it write in its own way; then its record could be kept, and any time after, the instrument might read aloud its own writing. Like a great genius as he is, Mr. Edison went to work in the simplest way to make the sound-recorder he wanted. You know how the diaphragm of the telephone vibrates when spoken to? Mr. Edison took away from the telephone all except the mouth-piece and the diaphragm, fastened a point of metal, which we will call a