The actual circuit arrangements of a bridging party line are better shown in Fig. 168. There are three stations and it will be seen that at each station there are three possible bridges, or bridge paths, across the two limbs of the line. The first of these bridges is controlled by the hook switch and is normally open. When the hook is raised, however, this path is closed through the receiver and secondary of the induction coil, the primary circuit being also closed so as to include the battery and transmitter. This constitutes an ordinary local-battery talking set.

Fig. 166. Grounded Bridging Line
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Fig. 167. Metallic Bridging Line
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Fig. 168. Metallic Bridging Line
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