Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems (1921)
Smith, Arthur Bessey, b. 1875, Campbell, Wilson Lee · New York : McGraw-Hill · leaf 125
W … Fig. 88.—One-hundred-line switchboard, rotary lineswitches (front). groups of 25 switches per group. The two at the left (50 lines) aremounted on one shelf, which is hinged at the left. It may be swungout to give access to the wiring on its back. The right shelf carryingfifty lineswitches is hinged…
Telephone
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