The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 156
clearer view of the connections is given in Figs. 146 and147, in which the different parts are lettered so as to corre-spond with Fig. 145. As shown in Fig. 146, the exchangeline is connected to the main instrument, and the ex- SWITCHES AND EXTENSION INSTRUMENTS 133 tension line is on to the extra… … L2 fci
Telephone
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