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 273
Fig. 216.—General view of panel type switch installation. setting up a call. There is a position indicator at the right, showing thatthere are 18 positions, each of which is centered by the cam and roller Aat the left. 250 AUTOMATIC TELEPHONY … n.i.u.iiiij
Telephone
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