The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 324
he battery, and its bright-ness serves for compari-son with that of otherlamps, caused by exces-sive leakage, etc., so thatthe resistance, etc., incircuit may be judged. Each block of lamps isconnected to an opera-tors position, but onlyas many lamps are fittedas there are subscriberslines attended…
Telephone
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