Johnson's natural philosophy and key to philosophical charts : illustrated with 500 cuts; being reduced photographic copies of all the diagrams contained in the author's philosophical series of indestructible school charts ; for the use of schools and families (1878)
Long-sightedness, on the contrary, is caused by too little curvature ofthe cornea and crystalline lens, which throws the image S, of the objectA, beyond the retina. This defect, therefore, is corrected by holdingthe object at a greater distance from the eye, or by employing convexspectacles, either… … 4r59. Figure 16.-Short-sightedness and long-sighted-ness caused by defective forms of the eyeball.—Although 262 OPTICS. the cornea and crystalline lens have the proper curvature, and all partsof the eye possess their usual powers of adjustment, yet sJiorf-sighfed-ness may result from an elongation…
Physics · Astronomy
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