The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 179
7-POINT BREAK JACK Fig. 171.—Scale & 154 PRACTICAL TELEPHONE HANDBOOK ing-jack made by the Kellogg Co. of America. This has onlyone contact spring. Fig. 173 shows a form of 3-point branching-jack made bythe Western Electric Co., and used in their common battery -b A
Telephone
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