CHAPTER XXIX 



t COLOR 



The rainbow. One of the most beautiful and well-known 

 enomena in nature is the rainbow. From time immemorial 

 it has been considered Jehovah's signal to mankind that the 

 storm is over and that the sunshine will remain. Practically 

 every one knows that a rainbow can be seen only when the sun's 

 rays shine upon a mist of tiny drops of water. It is these tiny 

 drops which by their refraction and their scattering of light pro- 

 duce the rainbow in the heavens. 



The exquisite tints of the rainbow can be seen if we look at 

 an object through a prism or chandelier crystal, and a very 

 simple experiment enables us to produce on the wall of a room 

 the exact colors of the rainbow in all their beauty. 



How to produce rainbow colors. The spectrum. When 

 a beam of sunlight is admitted into a dark room through a 

 narrow opening in the 

 shade, and falls upon a 

 prism, as shown in Fig- 

 ure 139, a beautiful band 

 of colors appears on the 

 opposite wall of the 

 room. The ray of light 

 which entered the room 

 as ordinary sunlight has not only been refracted and bent from 

 its straight path, but it has been spread out into a band of 

 colors similar to those of the rainbow. 



Whenever light passes through a prism or lens, it is dispersed 



271 



FIG. 139. White light is a mixture of lights of 

 rainbow colors. 



