THE 



POPULAR SCIENCE 

 MONTHLY. 



.NOVEMBER, 1878. 



THE CONTRAST OF COLOES. 



By Peofessor 0. N. EOOD. 



IN a previous chapter we have studied the changes which colored 

 surfaces experience when viewed under various kinds of illumina- 

 tion, or when modified in appearance by the admixture of more or less 

 white or colored light. The appearance which a colored surface pre- 

 sents to us can, however, be altered very materially, by a method which 

 is quite different from any of those that have thus far been mentioned: 

 we can actually change color to a considerable extent without at all 

 meddling with it directly, it being for this purpose only necessary to 

 alter the color which lies adjacent to it. The truth of this can be seen 

 by a very simple experiment: If we cut out of a sheet of red paper 

 two square pieces, about an inch in size, and then place one of them on 



Fig. 1.— Sheets of Red and Green Paper with Red Squares. 



a sheet of red, the other on a sheet of green paper, as indicated in Fig. 

 1, it will be found that the red square on the red paper will not appear 

 nearly so brilliant and saturated in color as that placed on the green 

 ground; hence the observer will be disposed to doubt whether the two 



^ From the advance-sheets of a work on " Chromatics, with Applications to Art and 

 Industry." 



VOL. xiv. — 1 



