8 THE POPULAR SCIENCE MONTHLY. 



leads to : The two colors are to be moved farther apart ; they are al- 

 ready situated on the opposite extremities of a diameter of the circle, 

 and, if they are to recede still farther from each other, they can accom- 

 plish this in no other way than by moving outside of the circumference 

 of the circle ; but this corresponds, as explained in the previous chapter, 

 to an increase of saturation. If the experiments indicated in the pre- 

 vious table are carefully repeated, it will be found that all the pairs of 

 colors there enumerated are not equally affected by contrast. The 

 changes of tint are greatest with the colors which are situated nearest 

 to each other in the chromatic circle, and much less with those at a 

 distance. Thus both red and yellow are much changed by contrast, 

 the red becoming purplish, the yellow greenish, while red -udth cyan- 

 blue, or blue, is much less affected in the matter of displacement or 

 change of hue. On the other hand, the colors which are distant from 

 each other in the chromatic circle, while suffering but slight changes. 

 in hue, are made to appear more brilliant and saturated — that is, they 

 are virtually moved somewhat outside of the circle, the maximum effect 

 taking place with colors which are complementary. Colors which are 

 identical are affected by contrast in exactly the opposite way from 

 those which are complementary — that is, they are made to appear duller 

 and less saturated. The author finds that these and other effects of 

 contrast can be studied with great advantage by the aid of two identical 

 chromatic circles laid down on paper. One set of these lines should be 

 traced on a sheet of transparent paper, which is afterward to be placed 

 over the companion-circle. The use of these circles will best be made 

 evident with the aid of an example : Let us suppose that we wish to 

 ascertain with their aid the effect produced by red, as far as contrast 

 goes, on all the other colors, and also on red itself. We place the trans- 

 parent circle on its companion so that the two drawings may coincide 

 in position, and we then move the upper circle along the diameter join- 

 ing the red and green-blue some little distance, so that the two circles 

 no longer have the same common centre. We then transfer the points 

 marked red, orange, yellow, etc., on the upper circle, by pricking with 

 a pin through to the lower circle ; these pin-marks on the lower circle 

 will indicate the changes produced on all the colors by competition 

 with red. Fig. 11 gives the result. The dotted circle with the crosses 

 represents the new positions of the different colors when contrasted 

 with red. If we examine it we find that red, when contrasted with 

 greenish-blue, causes this last color to move away from the centre of 

 the circle in a straight line ; hence, as the new point is on the same 

 diameter, but farther from the centre, we know that the greenish-blue 

 is not made more or less blue or green, but is simply caused to appear 

 more saturated or brilliant. The new point for the red lies also on the 

 same diameter, but is nearer to the centre of the circle ; that is, the 

 color remains red, but appears duller or less saturated. Experience 

 confirms this : if a considerable number of pieces of red cloth are ex- 



