Elementary lessons in electricity and magnetism (1906)
Thompson, Silvanus P. (Silvanus Phillips), 1851-1916, Schwetzky, Otto H. L. [from old catalog] · Chicago, Thompson & Thomas · leaf 429
trip), the currentruns through the earth and back by the line, or in thenegative direction. Telegraphists ordinarily speak ofthese as positive and negative currents respectively. As it is necessary that a line should be capable ofbeing worked from either end, a battery is used at each,and the wires… … 404 ELEMENTARY LESSONS ON [chap, xii. zc^ one pole of which is put to earth, and the other com-municates with a key K. This key is arranged (like thatin Fig. 164), so that when it is depressed, so as to senda signal through the line, it quits contact with thereceiving instrument at its own end. The…
Electricity · Magnetism
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