394 



RAINBOW. 



Q. What is meant by the EEFBACTION of a ray P 

 A. Bending it from its straight line. 



Thus the ray A B of the last figure is refracted at B 

 into three courses, C, D, and E. 



Q. What is the cause of a RAINBOW ? 



A. When the clouds opposite the 

 sun are very dark, and rain is still falling 

 from them, the rays of the bright sun are 

 divided ly the rain-drops, as they would 

 be by a prism. 



Let A, B, and C be three drops of rain ; S A, SB, and 

 S C three rays of the sun. S A is divided into the 3 

 colours ; the blue and yellow are bent above the eye D, 

 and the red enters it. 



