Philosophical instructor, or, Webster's elements of natural philosophy : subdivided into principles and illustrations ; intended for academies, medical schools, and the popular class-room (1824)
Eaton, Amos, 1776-1842, Webster, John, fl. 1804-1824 · Albany : Printed by Websters and Skinners ... · leaf 175
of a large sphere, is madeeither double convex or plano-convex ; the eye-glassis double convex, formed from a segment of a smallsphere; and these glasses are placed in the tube atthe common distance of their foci. Suppose rays of light issuing from every part ot theobject h i fail upon the… … shorter focal distance, be so placed as to include e k,the rays will pass on through c d in a position nearlyparallel, cross each other at f, and form a large, butinverted image of the object on the retina at g. Theobjects will be magnified by this glass in proportionas the distance of the focus of…
Physics
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