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 72
Figs. 3,882 to 3,884.—Various film perforations. These are called: fig. 3,882, round; fig. 3,883,square; fig. 3,884, barrel. The square and barrel holes seem to be more durable than theround hole. The shape of the holes should correspond to the shape of the sprocket teeth.A standard perforation is… … Fig. 3,885.—The arc controller or device designed to control the rate of feed of the carbons of anarc lamp, with the object of maintaining at all times a predetermined size of arc. It consistsof the controller proper, direct coupled to a fractional horse power motor. There are twoshafts, primary…
Electrical engineering
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