Lockyer, Norman, Sir, 1836-1920, Seabroke, G. M. (George Mitchell), 1848-1918 · London, Macmillan and co. · leaf 86
t of light; andevery one knows that if this experiment be performedwith the sun, one brings all the rays falling on the lensalmost to a point, and the longer waves of light will setfire to the paper; and on this principle burning-glassesare constructed. If, however, the rays are not parallelwhen… … Fk.;. 28.—Cciijuirate Foci oi Convex Lens. If matters are reversed, and the luminous source beplaced in the focus, the rays of light, when they leavethe lens, will converge to the position of the originalsource; so that there- are two points, one on eitherside of the lens, which are the foci of…
Astronomy · Telescopes
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