Hawkins electrical guide ... : questions, answers & illustrations : a progressive course of study for engineers, electricians, students and those desiring to acquire a working knowledge of electricity and its applications ; a practical treatise (1914)
Hawkins, N. (Nehemiah), 1833-1928 · New York : T. Audel & Co. · leaf 51
en key is thrown onouter contacts, hand generator cannot be used, as inner contacts are broken from circuit.6. Key normal, main alone can talk; key thrown, both instruments can talk. This iscalled plan 8 by the New York Telephone Co. 2,144 HAWKINS ELECTRICITY Ques. What is a P.B.X. emergency… … EXTENSIONSTATION LISTENINGKEY CONTACT5PRINGS
Electrical engineering
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