American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 591
one apparatus.3K is an ordinary strap-key, on which code signals may be tapped out by an officer. The apparatus at the central office, CO, is shown at the right of the figure. Itconsists of the relay r, register kg, a push jack h, magnetic coil mc, line galvano-meter G, main battery b, local… … CHICAGO POLICE PATROL CIRCUITS—THEORY, ; \Mien a signal is received, it is, as stated, acknowledged by th attendant in thecentral office, either by the telephone, or by means of the push-jack. The function ofthe push-jack, when depressed by the hand and withdrawn by a spring, is, first, tocharge…
Telegraph
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