SENSE OF SIGHT. 589 



sented by w. The colors at the extremities of straight lines are 

 complementary colors ; orange and blue, o and B, make white, w. 

 But neither B nor o is at the extremities of the line from n, but, 

 if this line was continued, it would strike the curved line between 

 B and G i. e., red and bluish green are complementary colors. 

 One can see also from this diagram what color results from the 

 union of two others. Thus red and yellow will produce the inter- 

 mediate color, orange ; red and violet will produce purple, and 

 this and green will produce white. If complementary colors are 

 put beside each other, both colors are more pronounced ; on the 

 other hand, if colors which are not complementary are so placed, 

 the colors are subdued. 



It may be well here to refer to some of the fundamental facts 

 in connection with colors, and for this purpose we shall quote 

 statements and experiments from Elements of Physics, by Carhart 

 and Chute. Color is not a property inherent in objects i. e., 

 bodies have no color of their own. Thus in the case of opaque 

 bodies, the color which they appear to have depends upon the 

 kind of light which they reflect. A red body is red because it 

 absorbs the other colors of the spectrum than the red and reflects 

 this color from its surface. If all the colors are reflected in proper 

 proportion, the body appears white. This can be proved by 

 looking through a glass prism at a piece of white paper 3 cm. 

 long and 2 mm. wide, pasted on a piece of black cardboard 

 several times larger, the edges of the prism being held parallel 

 to the length of the strip. The image seen through the prism 

 will be a spectrum similar to the solar spectrum. If a piece 

 of red paper is substituted for the white paper, on looking through 

 the prism the red end of the spectrum will be seen, but the other 

 colors will be dim or absent. If a blue strip is looked at, the 

 spectral image will show the blue, the other colors being lacking. 

 In other words, white paper is white because it reflects all the 

 colors in due proportion, while red paper reflects only red, and 

 blue, only blue. If in the red of the solar spectrum a piece of 

 red paper or ribbon is held, it will appear brilliantly red ; else- 

 where it will be nearly black ; a piece of blue will appear blue in 

 the blue of the spectrum, and there only. The color of opaque 

 bodies varies as the light which falls upon them varies ; thus if 

 any fabric into which blue or violet enters, as purple and pink, 

 is examined by artificial lights, all of which are deficient in blue 

 and violet rays, its color will vary from that which it has in sun- 

 light. It is on this account that matching colors by artificial 

 light is so difficult. 



Transparent bodies, on the other hand, are colorless when they 

 absorb no light i. e., transmit it all ; or when they absorb all the 

 colors in like proportion. It is the color or colors which are trans- 

 mitted that give the color to transparent bodies. If one color is 



