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 295
Fig. 234.—500-line installation. … Fig. 235.— Wipers and magnet of rotary switch. AUTOMANUAL SYSTEM 273 trunks between offices are handled by the first selector, requiring only asingle call figure to establish the connection. The trunk terminates asusual at the B board in the manual office, under the charge of a Boperator, who is…
Telephone
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