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 229
Fig. 185.-—View from below of three Chris- Fig. 186.—View from above of Christensentensen pneumatic selectors. pneumatic selectors. … Fig. 187.—Racks with Christensen pneumatic selectors mounted upon them. This selector, which belongs to the line switch type, differs from otherwell-known selectors both in its construction and in its method of opera- AUTOMATIC TRAFFIC DISTRIBUTOR EQUIPMENT 209 tion. The motion is rectilinear (not…
Telephone
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