Modern practice of the electric telegraph. A handbook for electricians and operators (1872)
Pope, Frank L. (Franklin Leonard), 1840-1895 · New York : D. Van Nostrand · leaf 69
^, exhausting the batteries, and interfering with theoperation of every wire connected with them. Thecause of these troubles being somewhat obscure, it might,for a considerable time, escape detection. 86. LOCAL CIRCUIT CHANGER.—In offices containingtwo sets of instruments on different circuits, it… … represented at M and M; S and S are the sounders orregisters, E and E are the local batteries. B is a simplebutton or circuit closer (62), having four connectingpoints, 1, 2, 3, 4. When the button is in the position1, 2, as shown in the figure, the relay M works thesounder S, and the relay M the…
Telegraph
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