This defect is thus defined by Dr. B. Joy Jeffries, who is an expert on the subject:
The defect exists in three main varieties, red-blindness green-blindness and violet-blindness,—the latter extremely rare. All colors containing the one in which the color-blind are deficient will be grayish, and this in proportion to their individual amount of defect. The red-blind sees all objects of this color of a darker hue than they are. The same is true to the green-blind, as to green. Both confound these colors with each other and with gray. A mixture of white and black, in proper proportions to represent the luminosity of any shade of red or green, will give the colorblind the same sensation as that shade.
Very ludicrous mistakes are made by the color-blind. One gentleman says: "Yellow and blue are my only distinct colors. Red is the most indistinct." An architect's apprentice copied a brown house in bluish-green paint, making the sky rose-color, and the roses blue. A tradesman's boy offered pink and pale-green paper as good matches. A weaver could not distinguish between red and green threads, but had to have them selected by another. Dr. Dalton, a color-blind English chemist,—whose careful study and accurate description of his own case have made the name Daltonism synonymous with red-blindness,—had an amusing experience when about to be present at court. Being a Quaker, it was known that the scarlet robe of a Doctor would be objectionable to him on account of its color. Luckily it was recollected that as the cherries and the leaves of a cherry-tree were to him of the same color, the scarlet gown would present to him no extraordinary appearance. So perfect, indeed, was the color-blindness, that this most modest and simple of men, after having received the Doctor's grow at Oxford, actually wore it for several days, in happy unconsciousness of the effect he produced on the street.
