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 165
anch office for transmission. But rivalry between 2,258 HAWKINS ELECTRICITY competing companies finally resulted in the installation ofmechanical call boxes in houses throughout New York City,whereby a patron could summon a messenger boy by turning ahandle. By the turning of this handle, or lever,… … Fig. 3,097.—Messenger call box (cover removed). This box operates the Gill selector and isconnected around a Morse key, the combination number of the box being stamped on thehandle. In order to transmit the combination over the line the handle is given a quarterturn and then released. Ques. Of what…
Electrical engineering
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