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 48
gth of that of the lens used for films. It should be noted that it is possible to match the size of the imagein one dimension only (either width or height) because the two openingsare not proportionate in size; accordingly, it is necessary in orderinglenses to specify whether the images are to be… … Fig. 3,814.—Bausch & Lomb standard projection lens. It consists of two combinations fittedinto a cell and mounted in a brass tube which slides through a brass tube or sleeve. Thefocusing is by rack and prism, as shown. Connection is made for spherical and achromaticaberration. Equivalent focus…
Electrical engineering
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