. Color-vision and color blindness, a practical manual for railroad surgeons . FlG. 9.—DiAGRASI ILLUSTRATING THE RECOMPOSITION OF WHITE LIGHT. duced by combining the colored rays. If the spectrumbe allowed to fall upon a double-convex lens (Fig. 9),the rays are re-united to form a pencil of white light onthe screen F^ placed at the focus of the lens. That white light can be produced from a combina-. FiG. 10.—Newtons Disc. tion of the spectral colors can be demonstrated by meansof Newtons disc. This consists of a card-board discabout one foot in diameter, upon which is pasted stripsof colored p
. Color-vision and color blindness, a practical manual for railroad surgeons . FlG. 9.—DiAGRASI ILLUSTRATING THE RECOMPOSITION OF WHITE LIGHT. duced by combining the colored rays. If the spectrumbe allowed to fall upon a double-convex lens (Fig. 9),the rays are re-united to form a pencil of white light onthe screen F^ placed at the focus of the lens. That white light can be produced from a combina-. FiG. 10.—Newtons Disc. tion of the spectral colors can be demonstrated by meansof Newtons disc. This consists of a card-board discabout one foot in diameter, upon which is pasted stripsof colored paper to represent five spectra; the centreis covered with black paper. (See Fig. 10.) When thedisc is rapidly rotated the retina receives the impression 22 COLOR-VISION AND COLOR-BLINDNESS. of white (gray). It is not a pure white, because pig-ment-colors are not pure, and because it is difficult toarrange the colors in the same proportion as they existin the spectrum. This experiment may be explained by the fact thatretinal impressions always last a little longer than thestimulus which gives rise to the impression. Hence,when the retina receives the impression of all thespectral colors in rapid succession, the impressions aremixed together and the resulting sensation is white (giay). Mixed Colors. Thus far Ave have only spoken of the simple, satu-rated colors of the spectrum; but in nature
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Keywords: ., boo, bookcentury1900, bookdecade1920, booksubjecteye, bookyear1920
