American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 589
MULTIPLE TRANSMITTER OR BREAK WHEEL. Gamewell police telegraph boxes.—The Gamewell police telegrapli box isshown in its three positions in Figs. 355, 356 and 357: namely,with both doors closed,with the outer door open, and with both doors open. 478 AMERICAN TELEGRAPHY. In the practical operation… … when the outer door is closed;grounding of the circuitoperates the central officebell as described. Normal h^, the gong mag-net G, within the box, iscut out of the circuit whenthe outer door is closed^by the pressure of thatdoor upon a knob n, Figs.356, 35 7- When, how-ever, the citizens keyis…
Telegraph
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