well-designed instruments, by great mechanical nicety in manufacture.

Almost any transmitter may be packed by drawing the diaphragm forward
so as to widely separate the electrodes. This allows the granules to
settle to a lower level than they normally occupy and when the
diaphragm is released and attempts to resume its normal position it is
prevented from doing so by the mass of granules between. Transmitters
of the early types could be packed by placing the lips against the
mouthpiece and drawing in the breath. The slots now provided at the
base of standard mouthpieces effectually prevent this.

In general it may be said that the packing difficulty has been almost
entirely eliminated, not by the employment of remedial devices, such
as those often proposed for stirring up the carbon, but by preventing
the trouble by the design and manufacture of the instruments in such
forms that they will not be subject to the evil.

Carrying Capacity. Obviously, the power of a transmitter is
dependent on the amount of current that it may carry, as well as on
the amount of variation that it may make in the resistance of the path
through it. Granular carbon transmitters are capable of carrying much
heavier current than the old Blake or other single or multiple
electrode types. If forced to carry too much current, however, the
same frying or sizzling sound is noticeable as in the earlier types.
This is due to the heating of the electrodes and to small arcs that
occur between the electrodes and the granules.

One way to increase the current-carrying capacity of a transmitter is
to increase the area of its electrodes, but a limit is soon reached in
this direction owing to the increased inertia of the moving electrode,