. Refraction and how to refract : including sections on optics, retinoscopy, the fitting of spectacles and eye-glasses, Fig. 41. Fig. 42. Fig. 43. which it is a part is spoken of as the axis, and is indicatedon the lens of the trial-case by a short diamond scratch onthe lens at its periphery, or by having a small portion of. Fig. 44. its surface corresponding to the axis ground at the edges,or it may be marked in both ways. (See Fig. 43.) Cylin-ders are of two kinds—convex and concave. (Figs. 41, 42.)Cylinder Action.—A convex cylinder converges parallel 44 REFRACTION AND HOW TO REFRACT,
. Refraction and how to refract : including sections on optics, retinoscopy, the fitting of spectacles and eye-glasses, Fig. 41. Fig. 42. Fig. 43. which it is a part is spoken of as the axis, and is indicatedon the lens of the trial-case by a short diamond scratch onthe lens at its periphery, or by having a small portion of. Fig. 44. its surface corresponding to the axis ground at the edges,or it may be marked in both ways. (See Fig. 43.) Cylin-ders are of two kinds—convex and concave. (Figs. 41, 42.)Cylinder Action.—A convex cylinder converges parallel 44 REFRACTION AND HOW TO REFRACT, F-c:
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Keywords: ., bookcentury1900, bookdecade1900, bookidref, booksubjecteyeglasses
