Historical sketch of the electric telegraph : including its rise and progress in the United States (1852)
Jones, Alexander, 1802-1863 · New York : G.P. Putnam · leaf 39
CAL SKECTH OF passage of tlie fluid, and raises it wlien tlie spring throwsback the lever and breaks the circuit—which can be donewith great rapidity. This may be understood from the fact,that it requires from one to four or five motions of the fingerto make a single letter or figure ; and yet an… … 11. The Call.—As the Bain Electfo-chemical EecordingTelegraph acts silently, it became necessary for him to contrivethis call^^^ whereby one operator at a distant point can givenotice at the opposite end of the wire that he is ready tosend a message; whereupon he can proceed to put the chemi-cal…
Telegraph
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