Anatomy and physiology of the eye, with hints for the preservation of the eyesight (1901)
Herbert, John Frederick, 1860- · Philadelphia, Pa., The author · leaf 30
e object is brought to the eye the greaterbeing the visual angle and the larger is the image. In order that the retinal image may be of the necessarysize to excite perception, the object producing it mustform a certain visual angle, which must not be too small. A good illustration and test of the… … Figure 12. The letters at 8 and 12 feet are as plainly seen by the eye as the one at 4 feet;the lines suhteiul from all of the letters at the same angle. but if the coin be removed to arms length distance it willappear much smaller, allowing the distant object to beseen. VISUAL ACUTENESS. In…
Eye · Lenses
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