that of the lower animals and man. In a telegraph circuit, with
its clicking key at one end and its chattering sounder at the
other, we have, in fact, an apish forerunner of the exquisite
telephone, with its mysterious microphone and oracular plate.
Nevertheless, the telephone descended from the telegraph in a very
indirect manner, if at all, and certainly not through the sounder.
The first practical suggestion of an electric telephone was made
by M. Charles Bourseul, a French telegraphist, in 1854, but to all
appearance nothing came of it. In 1860, however, Philipp Reis, a
German schoolmaster, constructed a rudimentary telephone, by which
music and a few spoken words were sent. Finally, in 1876, Mr.
Alexander Graham Bell, a Scotchman, residing in Canada, and
subsequently in the United States, exhibited a capable speaking
telephone of his invention at the Centennial Exhibition,
Philadelphia.

Figure 56 represents an outside view and section of the Bell
telephone as it is now made, where M is a bar magnet having a
small bobbin or coil of fine insulated wire C girdling one pole.
In front of this coil there is a circular plate of soft iron
capable of vibrating like a diaphragm or the drum of the ear. A
cover shaped like a mouthpiece O fixes the diaphragm all round,
and the wires W W serve to connect the coil in the circuit.

The soft iron diaphragm is, of course, magnetised by the induction
of the pole, and would be attracted bodily to the pole were it not
fixed by the rim, so that only its middle is free to move. Now,
when a person speaks into the mouthpiece the sonorous waves
impinge on the diaphragm and make it vibrate in sympathy with
them. Being magnetic, the movement of the diaphragm to and from