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 219
controlled by an electromagnet so as to run onlywhile a completed call is held. In appearance it is a rectangular box,with a clock face appearing near the lower end. (Fig. 179.) There are two varieties. The first counts time only, the second makesan arbitrary charge of one minute at the beginning… … Fig. 179. When the subscriber takes the receiver from the hook to make acall, it is necessary to turn a knob on the meter box. This takes theshort circuit off the calling device. He now dials the call. When thecalled station answers, the reversal of current actuates a polarizedmagnet which starts…
Telephone
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