. Physiological optics : being an essay contributed to the American encyclopedia of ophthalmology . Fig. 57.—The Rules of the Optometer of Young. the most important instruments for the study of physiologic optics,—enables us to measure spherical aberration directly. It is in the formof a little rule carrying a fine white line on a black background onone side. The observer looks along this line through a -J- 10 3D. front of the lens is placed a small horizontal rule, free to move andcarrying different groups of slits. Two slits in this rule will act likethe openings in the experiments o
. Physiological optics : being an essay contributed to the American encyclopedia of ophthalmology . Fig. 57.—The Rules of the Optometer of Young. the most important instruments for the study of physiologic optics,—enables us to measure spherical aberration directly. It is in the formof a little rule carrying a fine white line on a black background onone side. The observer looks along this line through a -J- 10 3D. front of the lens is placed a small horizontal rule, free to move andcarrying different groups of slits. Two slits in this rule will act likethe openings in the experiments of Schemer. Each point of the lineappears double except that which is seen distinctly; in this manner itmay be used to determine the far point of an eye by placing a smallcursor at the point where the observer sees the lines intersect. Therule carries various sets of slits differing in number and positionthereby permitting the determination of the refraction at differentparts of the pupillary space. One may also make use of a secondform of rule,—placed vertical and having an M-opening thus
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectphysiologicaloptics
