. A text-book of animal physiology [microform] : with introductory chapters on general biology and a full treatment of reproduction, for students of human and comparative (veterinary) medicine and of general biology. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. (•bfonnwIitSiS, h which they IX lens being B believed to ixtent, by the )d outer rays, lo that those mated by it. lens are cor- >n of the lens does not increase regularly from the c^iuter to th cirownf '' ence. ArtiffBMtifB.—In this defect the vertical meridian Ih ,>- posed to be m
. A text-book of animal physiology [microform] : with introductory chapters on general biology and a full treatment of reproduction, for students of human and comparative (veterinary) medicine and of general biology. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. (•bfonnwIitSiS, h which they IX lens being B believed to ixtent, by the )d outer rays, lo that those mated by it. lens are cor- >n of the lens does not increase regularly from the c^iuter to th cirownf '' ence. ArtiffBMtifB.—In this defect the vertical meridian Ih ,>- posed to be more convex than the horizontal, as is partJ iy the case with the cornea of the eye, and it is to this body t^it astigmatism is usually referable, rather than to the lens, though the latter may also be clefective. In astigmatism, when a vertical line is in focus a horizontal can not be distinctly seen, and the reverse. This any one may readily demonstrate to himself by drawing one straight line at right angles to the center of another and looking at the figure; when the one is seen distinctly, the other is blurred. It is to be borne in mind that, in order to see a horizontal line distinctly, it is of most importance that the rays that diverge from this line, in a series of vertical planes, be well focused, rather than those which diverge in the plane of the line itself; so that, when the cornea is most curved in the vertical meridian, a horizontal line will be represented by an image of a horizontal line at the nearer focus—i. e., when the vertical is the most con- vex meridian, horizontal lines are soonest focused, and this holds, in fact, of most eyes. When the astigmatism affects several meridians," irregular astigmatism " results. The defect in question is to be corrected by glasses made of sections of a cylinder, thickest in the region corresponding to that of greatest corneal, etc., dbfect. duromatie Abenratton.—In the figure below, in which 7i A rep-
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Keywords: ., bookauthormillswes, bookcentury1800, bookdecade1880, bookyear1889
