| | | DIMENSIONS IN INCHES |
| CAPACITY | SHAPE |----------+----------+-----------+
| | | Height | Width | Thickness |
+------------+---------------+----------+----------+-----------+
| 2 m. f. | Rectangular | 9-1/6 | 4-3/4 | 11/16 |
| 1 m. f. | " | 9-1/6 | 4-3/4 | 11/16 |
| 1 m. f. | " | 4-3/4 | 2-3/32 | 13/16 |
| 1/2 m. f. | " | 2-3/4 | 1-1/4 | 3/4 |
| 1 m. f. | " | 4-13/16 | 2-1/32 | 25/32 |
| 1/2 m. f. | " | 4-3/4 | 2-3/32 | 13/16 |
| 3/10 m. f. | " | 4-3/4 | 2-3/32 | 13/16 |
| 1 m. f. | " | 2-3/4 | 3 | l |
+------------+---------------+----------+----------+-----------+

Conventional Symbols. The conventional symbols usually employed to
represent condensers in telephone diagrams are shown in Fig. 124.
These all convey the idea of the adjacent conducting plates separated
by insulating material.

[Illustration: Fig. 124. Condenser Symbols]

Functions. Obviously, when placed in a circuit a condenser offers a
complete barrier to the flow of direct current, since no conducting
path exists between its terminals, the dielectric offering a very high
insulation resistance. If, however, the condenser is connected across
the terminals of a source of alternating current, this current flows
first in one direction and then in the other, the electromotive force
in the circuit increasing from zero to a maximum in one direction, and
then decreasing back to zero and to a maximum in the other direction,
and so on. With a condenser connected so as to be subjected to such
alternating electromotive forces, as the electromotive force begins to
rise the electromotive force at the condenser terminals will also rise
and a current will, therefore, flow into the condenser. When the
electromotive force reaches its maximum, the condenser will have
received its full charge for that potential, and the current flow into
it will cease. When the electromotive force begins to fall, the
condenser can no longer retain its charge and a current will,
therefore, flow out of it. Apparently, therefore, there is a flow of
current through the condenser the same as if it were a conductor.

Means for Assorting Currents. In conclusion, it is obvious that the
telephone engineer has within his reac