This is that part of the telephone which is held to the ear, and
by which we can hear the words spoken into the transmitter of the
telephone at the other end of the line.
[Illustration: Fig. 14]
The receiver is made of hard rubber, and contains a permanent bar
magnet, which is wound with wire so as to make it also an electromagnet
when desired. In front of this magnet is placed loosely a diaphragm
of thin sheet iron. This diaphragm is placed so as to be within the
influence of the magnet, but just so that neither one can touch the
other.
Fig. 14 is a sketch of the receiver. A and B are the wires leading to
the magnet, C, and D is the diaphragm. E and F are where the wires
connect, one from the secondary of the induction-coil in the other
telephone, and the other connected with the earth.