If a
telephonic set at T1 (Fig. 2) communicate through the line to a
distant station, T2, through a condenser, C, of a capacity of half a
microfarad, conversation is still perfectly audible, provided the
telephonic system is one that acts by induction currents. And since in
this case the interposition of the condenser prevents any continuous
flow of current through the line, no perceptible weakening will be
felt if a shunt S, of as high a resistance as 500 ohms and of great
electromagnetic rigidity, that is to say, having a high coefficient of
self-induction, be placed across the circuit from line to earth. In
this, as well as in the other figures, the telephones indicated are of
the Bell pattern, and if set up as shown in Fig. 2, without any
battery, would be used both as transmitter and receiver on Bell's
original plan. But as a matter of fact any ordinary telephone might be
used. In practice the Bell telephone is not advantageous as a
transmitter, and has been abandoned except for receiving; the Blake,
Ader, or some other modification of the microphone being used in
conjunction with a separate battery.
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