which necessarily comes with its larger size.

The carrying capacity of transmitters may also be increased by
providing special means for carrying away the heat generated in the
variable-resistance medium. Several schemes have been proposed for
this. One is to employ unusually heavy metal for the electrode
chamber, and this practice is best exemplified in the White solid-back
instrument. It has also been proposed by others to water-jacket the
electrode chamber, and also to keep it cool by placing it in close
proximity to the relatively cool joints of a thermopile. Neither of
these two latter schemes seems to be warranted in ordinary commercial
practice.

Sensitiveness. In all the transmitters so far discussed damping
springs of one form or another have been employed to reduce the
sensitiveness of the instrument. For ordinary commercial use too great
a degree of sensitiveness is a fault, as has already been pointed out.
There are, however, certain adaptations of the telephone transmitter
which make a maximum degree of sensitiveness desirable. One of these
adaptations is found in the telephone equipments for assisting
partially deaf people to hear. In these the transmitter is carried on
some portion of the body of the deaf person, the receiver is strapped
or otherwise held at his ear, and a battery for furnishing the current
is carried in his pocket. It is not feasible, for this sort of use,
that the sound which this transmitter is to reproduce shall always
occur immediately in front of the transmitter. It more often occurs at
a distance of several feet. For this reason the transmitter is made as
sensitive as possible, and yet is so constructed that it will not be
caused to produce too loud or unduly harsh sounds in response to a
loud sound taking place immediately in front of it. Another adaptation