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 124
Fig. 86.—One-hundred-line switchboard,Keith lineswitches (front). Fig. 87.—One-hundred-line switchboard,Keith lineswitches (back). twenty-seven years and new arrangements are still being considered.Each has its own advantages, and an engineer can lay out a systemwith the assurance that the…
Telephone
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