History, theory, and practice of the electric telegraph (1866)
Prescott, George B.(George Bartlett),1830-1894 · Boston, Ticknor and Fields · leaf 115
Fig. 48. left, it being held by the detent until it is released by the closingof its own relay, which also closes the repeating armature. … Fig. 49. Fig. 50. If both circuits are closed, the armature that first opens throwsa detent under the other before opening the other circuit, and THE MORSE SYSTEM. 97 when the circuit is to be closed, instead of depending upon theprompt action of the relay in closing to prevent a false break,the…
Telegraph
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