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THE POPULAR SCIENCE MONTHLY 



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 un- 

 saturated hues may be caused to assume much greater degrees of satura- 

 tion while, if the apposition be false, hues in themselves of almost com- 

 plete 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 Eood. To construct such a circle we must know 

 the wave-lengths of the various colors which we desire to contrast. 3 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. 



?9-* 



Fig. 2. Rood's Chromatic Circles as used to show the Influence of one Color) 



on the others. 



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 accu- 

 rately 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 



3 This can be done by comparing the colors with those of a highly magnified 

 spectrum of white light alongside of which is a scale of wave-lengths. 



