Color-vision and Color-blindness: A Practical Manual for Railroad SurgeonsF.A. Davis, 1895 - 115 pages |
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Common terms and phrases
after-images appear Archives of Ophthalmology arranged bangle blue-yellow candidate CHROMATIC ABERRATION color-blind person color-perception color-sense colored glass colored light colored paper complementary color confusion colors dark defect degree disc distance elements sensitive employés examined feeble chromatic sense field for white field of vision fixation-point green-blind Helmholtz Holmgren indigo intensity of light layer limit method millimetres mistakes mixture of red name the color Nicol prism normal eye objects odd numbers Oliver optic nerve orange patient Pennsylvania Railroad placed plate Polariscope primary colors primitive colors prism Pseudo-isochromatic pure green railroad recognized recorded red and green red-blind red-green blind retina right eye rods and cones rose sample saturated scotoma sense of color sensitive to red shades spectral colors Spectral Rays spectrum test colors test skeins tints tobacco-amblyopia violet violet-blind visual acuity visual field visual purple white light whitish wools WORSTED TEST yellow and blue Young-Helmholtz theory
Popular passages
Page 59 - The faculty possessed by the eye of distinguishing colors and that of defining the degrees of light and color (of "saturation") are relatively very different; but these special faculties have this in common, that they have their maximum activity in a certain intermediary region of absolute intensity of light and their minimum at the two limits of this region. Just as we experience the most difficulty in distinguishing between the shades of intensity of light by a very feeble or very strong illumination,...
Page 34 - Green is a strongly luminous but whitish green, which, in tending toward the blue, becomes more and more ' saturated ; ' so that greenish blue must be the type of these hues. The blue is a green of moderate luminosity, and strongly ' saturated ; ' and violet is green very feebly luminous, but also ' saturated ' in a much 1 higher degree than the normal.
Page 63 - He can, according to the manner in which the task is performed, form a judgment of a feeble chromatic sense in instances which are proved correct by the final result. He also can and must see whether the result is erroneous simply on account of a misunderstanding or a want of intelligence, just as he can see whether the really color-blind succeeds, in a certain degree, from much previous exercise or a considerable amount of caution. In short, the method supplies us with all necessary information,...
Page 60 - ... spectrum. In fact, it has been regarded as the eighth color of the spectrum, closing the circle of saturated colors. Purple is of especial importance in the examination of the color-blind, for the reason that it forms a combination of two fundamental colors — the two extreme colors — which are never confounded with each other. In fact, from a color-blind point of view, one of two things must happen, according to the theory : either it excites but one kind of perceptive organs, or it excites...
Page 60 - The examiner should explain that . resemblance in every respect is not necessary; that there are no two specimens exactly alike; that the only question is the resemblance of the color; and that, consequently, he must endeavor to find something similar of the same shade, something lighter and darker of the same color, etc.
Page 52 - ... blind" are not invisible to him. To the red-blind, the red light is a less luminous green ; to the green-blind, the green light is a less luminous red. The danger arises because the apparent differences are not sufficiently characteristic to lead to certain and prompt identification in all states of illumination and of atmosphere. It must be admitted, therefore, that a...
Page 49 - Strange as it may appear, my defective vision is, to a certain extent, a useful and valuable quality. Thus : an engraver has two negative colors to deal with; ie, white and black. Now, when I look at a picture, I see it only in white and black, or light and shade ; and any want of harmony in the coloring of a picture is immediately made manifest by a corresponding discord in the arrangement of its light and shade, or, as artists term it, the effect. I find at times many of my brother-engravers in...
Page 95 - A card or disc of large letters for testing distant sight. 2. A book or card of print for testing sight at a short distance. 3. An adjustable frame for supporting the print to be read, with a graduated rod attached for measuring the distance from the eye while reading. 4. A spectacle frame for obstructing the vision of either eye while testing the other. 5. An assortment of colored yarns for testing the sense of color. 6. A watch with a loud tick for testing the hearing. 7. A book or set of blanks...
Page 52 - Before being intrusted with a train he is taken over the line, and is shown the precise position of every light. If a light did not appear where it was due, he would naturally ask his fireman to aid in the lookout. It must be also remembered that to over-run a danger signal does not of necessity imply a collision. A driver may over-run the signal, and after doing so may see a train or other obstruction on the line, and may stop in time to avoid an accident. In such a case he would probably be reported...