. A treatise on diseases of the eye . The schematic or . normaleye, natural size. The atiterior andposterior principal foci are ;lby F and F respectively; the andsecond principal points by // and // ,and the nodal points by A and A^.. Ilhistratiiig the projection of the retinal imaRc alouK th It is a})j)arent from this diagrani that the rcdiiai image is alwaysinverted with respect to the object seen. The mind, however, does nottake cognizance of the retinal image; it possesses the ])()wer of externalprojection so that objects are normally seen in their true j)()sit
. A treatise on diseases of the eye . The schematic or . normaleye, natural size. The atiterior andposterior principal foci are ;lby F and F respectively; the andsecond principal points by // and // ,and the nodal points by A and A^.. Ilhistratiiig the projection of the retinal imaRc alouK th It is a})j)arent from this diagrani that the rcdiiai image is alwaysinverted with respect to the object seen. The mind, however, does nottake cognizance of the retinal image; it possesses the ])()wer of externalprojection so that objects are normally seen in their true j)()siti()n. The size of tlte inuKje on the retina is detenniiied by the distance ofthe object; for it is apparent diat O 0^ (Fig. 70) is as many times longerthan //j as ON is longer than NI. 100 GENERAL PRINCIPLES OF OPTICS Emmetropia and Ametropia. ^Mien the retina and posterior principalfocus of the eve coincide in jiosition, the eye is adapted to receive aclear impression of a distant ol) ject. This condition, occurring in relax-ation of the ciliary muscle, is called ctnmcfrnpin. Any deviation fromennnetropia is called ametropia. An ametro])ic eye is said to be attectedwith an error of refrnrfion. Tli/peropia.—Hyperopia is that form of ametropia in wiiicli
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecteyediseases, bookyear
