the granular carbon is retained in the chamber and the necessary
flexibility or freedom of motion is permitted between the front and
the rear electrodes. As in the Kellogg and the later Bell instruments,
the entire working parts of this transmitter are insulated from the
metal containing case, the inner chamber, formed by the cup _2_ and
the diaphragm _3_, being insulated from the transmitter front and its
locking ring by means of insulating washers, as shown.

Fig. 44. Automatic Electric Company Transmitter

Monarch Transmitter. The transmitter of the Monarch Telephone
Manufacturing Company, shown in Fig. 45, differs from both the
stationary-cup and the vibrating-cup types, although it has the
characteristics of both. It might be said that it differs from each
of these two types of transmitters in that it has the characteristics
of both.

This transmitter, it will be seen, has two flexible mica washers
between the electrodes and the walls of the electrode cup. The front
and the back electrodes are attached to the diaphragm and the bridge,
respectively, by a method similar to that employed in the solid-back
transmitters, while the carbon chamber itself is free to vibrate with
the diaphragm as is characteristic of the Kellogg transmitter.

[Illustration: Fig. 45. Monarch Transmitter]

An aluminum diaphragm is employed, the circumferential edge of which
is forwardly deflected to form a seat. The edge of the diaphragm rests
_against_ and is separated _from_ the brass front by means of a
one-piece gasket of specially treated linen. This forms an insulator