Color-vision and color blindness, a practical manual for railroad surgeons (1920)
Jennings, John Ellis · Philadelphia F.A. Davis · leaf 99
is asked to name the colorsas tlie disc is rotated in front of the flame. If lie rec-ognize tlie red light through the 1-millimetre opening, his color-sense is normal, If an opening of 20 millimetres is needed, his color-sense r= oV- I^ ^^g failto recognize the color throngh the largest opening… … Fig. 21.—Color-Sense Measure. (Oliver.) there is inserted a movable, graduated slide. The disc isbolted to two circular cards, upon which are placed thethree primary colors and blue and a series of confusioncolors. The disc is placed at 5 metres distance, in agood light, and the candidate requested…
Color-blindness · Eye
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