Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book (1903)
Swoope, Coates Walton. [from old catalog] · New York, D. Van Nostrand company · leaf 348
is the contact of aconductor in any circuit with the earth, permitting an escapeof current if another ground exists. 313. The Telegraph.—The telegraph instrument is anapparatus for transmitting signals by the aid of an electriccurrent. It consists ofthe line, the transmitteror key, the receiver… … -Telegraph Sounder. contact point, B, which pivoted at AA, carrying a platinum is brought into contact by depressing the knob against theaction of the spring, S. On depressing the lever by the knob,N, the two platinum points, B, P, connected to the line byposts C and D, are brought into contact and…
Electricity · Magnetism
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