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- · New York, T. Audel · leaf 194
Fig. 1.0.J.i.—Operating keyboard for three number National carriage call. The keyboard hereshown is designed to control a three number call, there being a row of keys for each mono-gram or unit of the call. Its dimensions are 4 inches deep. 18 inches wide and 19 mcheslong. The base is of slate.… … Fig. 1.036.—Clock monogram or electric sign clock, operated by the mechanism shown infig. 1,037.
Electrical engineering
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