Introductory course of natural philosophy for the use of schools and academies. Ed. from Ganot's popular physics. By William G. Peck (1869)
Ganot, Adolphe, 1804-1887, Peck, William Guy, 1820-1892 · New York A.S. Barnes · leaf 311
methods of illumination were afterwards replaced by oillamps placed in the foci of concave reflectors, which served to con-centrate the rays, and thus to heighten their illuminating effect.But the reflectors, being made of metal, were soon tarnished, andthe light afforded became feeble. In 1822,… … Fig. 201. Fist 202. Abandoning the reflectors, which became tarnished by the influenceof sea fogs, he substituted for them plano-convex lenses, in theprincipal foci of which he placed powerful lamps with four con-centric wicks, each of which, for the quantity of oil consumed, andthe amount of light…
Physics
Internet Archive · Gerstein Library, University of Toronto · Public Domain Mark 1.0. Free to use for anything.
