Telegraph engineering : a manual for practicing telegraph engineers and engineering students (1922)
Hausmann, Erich, 1886- · New York : D. Van Nostrand Company · leaf 22
T … Fig. 3. the letters having the same significance as before. The de-pression of a key at a station introduces the source ofcurrent at that station into the circuit and causes theoperation of the relays at all the other stations. These inturn operate the sounders through the local batteries,…
Telegraph
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