The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 178
act (when a plug isinserted) by an insulating studattached to the shorter of thetwo outer springs. The 5 - point and 7 - pointbreak-jacks are those mostlyused on small switch-boards. Branching-Jacks are constructed in a similar manner tobreak-jacks, but are usually less complicated. The 3-point… … 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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