258 



SCIENCE OF COMMON THINGS. 



No two persons see the same rainbow. Formation of two rainbows at the same time 



great an altitude above the horizon. Hence, within a 

 certain interval each day, no visible rainbows can be 

 formed, on account of the sun's high altitude above the 

 horizon. 



1684 How do we know that the rainbow results from the decomposition 

 of the solar rays by drops of water 1 



Because in the case of cascades and water-falls, the 

 \spray and the drops of moisture dispersed over the 

 igrass and the spiders -webs produce the same phenomena. 



1635 Does every person see the same colors from the same drops? 



No ; no two persons see the same rainbow. 



To another spectator, the rays from S B (Fig. 70) might be red instead 

 of yellow ; the ray from S C, yellow ; and the blue might be reflected 

 from some drop below C. To a third person, the red may issue from a 

 drop above A, and then A would reflect the yellow, and B the blue, and 

 so on. 



1686 Why are there often two rainbows at one and the same time f 



The first, or primary bow, is formed by two refrac- 

 tions of the solar ray, and one reflection, tne rays of the 

 sun entering the drops at the top, and being reflected 

 to the eye from the bottom. 



Thus in Fig. 71, the ray S A of the 

 primary rainbow strikes the drop at A, 

 is refracted or bent to B, the back part 

 of the inner surface of the drop ; it is 

 then refracted to C, the lower part of 

 the drop, when it is refracted again, 

 and so bent as to come directly to the 

 eye of the spectator. 



The secondary, or outer bow, is pro- 

 duced, on the contrary, by two refrac- 

 tions and two reflections, the ray of 

 light entering the drops from the bot- 

 tom, and being reflected to the eye 

 from the top. 



Thus in Fig. 72, the ray S B of the 

 secondary bow strikes the bottom of 

 the drop at B, is refracted to A, is then 

 reflected to C, is again reflected to D, 

 when it is again refracted or bent, till 

 it reaches the eye of the spectator. 



1687 Why are the colors of the 

 second bow all reversed 1 



jn e . re. Because in one bow we sea 



