Skiascopy and its practical application to the study of refraction . ies tofind the one sought, would be a way of consuming timerather than saving it. Other forms of elaborate apparatusfor the purpose have been suggestedby Sureau of Paris,and one by Perkins and Tait of Philadelphia. A series Fig. 25. MERIDIAN INDICATORS. 103 sufficient for the approximate testing of the majority ofeyes may save time where many are to be tested, especiallyif the concave mirror be employed. The writer, usinghabitually the plane mirror, has discarded all special formsof apparatus, and depends on the trial frame a
Skiascopy and its practical application to the study of refraction . ies tofind the one sought, would be a way of consuming timerather than saving it. Other forms of elaborate apparatusfor the purpose have been suggestedby Sureau of Paris,and one by Perkins and Tait of Philadelphia. A series Fig. 25. MERIDIAN INDICATORS. 103 sufficient for the approximate testing of the majority ofeyes may save time where many are to be tested, especiallyif the concave mirror be employed. The writer, usinghabitually the plane mirror, has discarded all special formsof apparatus, and depends on the trial frame and test Indicators.—In working with lenses in thegraduated trial frame one may refer to its graduation toascertain the direction of the bands of astigmatism. Butin the darkened room this is not convenient. To meetthis want, Thorington (Medical News, March 3, 1894) andPrince (Ophthalmic Review, July, 1894) have suggested disksspecially graduated for the purpose. The former, figure 26,is called an axonometer; the latter, figure 27, an
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectretinos, bookyear1896
