Merchant, F. W. (Francis Walter), 1855-1937, Chant, Clarence Augustus, 1865-1956 · Toronto : Copp Clark · leaf 440
P W A B C - Earfh Earth Pig. 520.—Connection of instruments in a telegraph circuit. A, B, and C, and indicates how the connections are made ineacli office. When the line is not in use the switch on each key K isclosed and the current in the main circuit flows from the positivepole of the main…
Physics
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