Henderson, C. Hanford (Charles Hanford), 1861-1941, Woodhull, John F. (John Francis), 1857-1941 · New York, D. Appleton and company · leaf 356
ct image shall beformed on the retina. As the object, the crystalline lens,and the retina are fixed in position, the focusing can onlybe brought about by a change in the curvature of the lens.This is a matter of muscular contraction, and in normal REFRACTION OF LIGHT 333 eyes is done so quickly and… … Double-concave glass for near-sightedness. images in front of the retina. It is remedied by the useof glasses which cause rays of light to diverge (Fig. 231).Far-sightedness, on the contrary, results from too littlecurvature of the lens, so that images form back of the ret-ina. It must be remedied…
Physics
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