American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 598
.. CO. ii—V .- • I I - £\ _4 ^ »>ip^ llllllll MB Rh. A s\ … STOVER SPECIAL ALARM DEVICE. To produce this increase of current on the line, special arrangements are provided in the signal box 13 and in the central office. In the signal box a springconnected with the ground, is so placed that, when the crank lever is turned beyond the ordinary stopping point,…
Telegraph
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