Page:Popular Science Monthly Volume 83.djvu/462

458 if a gray or a tint of low saturation (see p. 460) is apposed against a saturated color field it will assume a complementary hue of greater or less saturation according to the relative area of brightness of the apposing areas. By applying these principles in picture painting unsaturated hues may be caused to assume much greater degrees of saturation while, if the apposition be false, hues in themselves of almost complete saturation may become dull and subdued.

To the artist it comes to be of the highest importance that he possess some easily remembered scheme by which he can predict these contrast effects. The color triangle may be thus employed, but a simpler, though perhaps less scientific device, for the same purpose is the chromatic circle of Rood. To construct such a circle we must know the wave-lengths of the various colors which we desire to contrast. The differences in wave-lengths are then calculated so as to correspond to angular differences, these angles being formed by the radii of the circle. As in the color triangle, opposite radii will join complementary colors and the center will represent white light, i. e., the nearer the center the less will be the saturation of the color.

If one such circle, drawn on transparent paper, be superimposed on another, the effect which is produced by contrasting two colors can be readily ascertained. Thus, suppose we desire to determine the influence which red has when contrasted with the other colors. Having accurately superimposed the two circles we move the transparent one so that the point on it which corresponds to red is displaced along the line joining red and its complementary, blue-green. The colors on the upper circle will now stand in positions on the lower corresponding to the