The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 113
o PRACTICAL TELEPHONE HANDBOOK Magneto Switch-Bells.—In the early days of the telephone,batteries were almost exclusively used for signalling purposes,but they were soon superseded by mechanical generators ofelectricity, based on Faradays discovery that currents couldbe generated by the relative… … Fig. 79 Scale J
Telephone
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