414: THE RAINBOW. 



refracted at m'. In passing thus through the drop, the 

 light is also decomposed. If m'E represent the path of 

 a red ray, the violet ray will traverse a path above, because 

 violet is refracted more than red. The path of this violet 

 ray may be represented by m'B. If the raindrop be in the 

 exact position for the red ray, m'E, to enter the eye of the 

 observer, the violet and other colored rays will pass over* 

 head and not be seen. This drop will appear red. 



643. Successive Colors of the Rainbow. In order 



that a violet ray 

 may enter the eye 

 at E, it must pro- 

 ceed from a drop 

 situated below the 

 one that sends the 

 red ray. This drop 

 will appear violet. 

 Intervening drops 

 will give the inter- 

 vening colors of 

 the solar spectrum 

 in their proper or- 

 der as is shown in 

 Fig. 319. Owing 

 to the distance of 

 the sun, all of the 

 incident rays are 

 FIG. 310. parallel with the 



axis EO, drawn 



from the sun through E, the eye of the observer, to 0, the centre 

 of the circle of which the bow forms a part. The angle between 

 the incident and the emergent ray, SRE, and consequently the angle 

 REO, is, for the red ray, about 42. The angles S' VE and VEO are, 

 for the violet ray, about 40. The other colors lying between these, 

 it will be seen that the angular width of the rainbow is about two 

 degrees. 



644. Form and Extent of the Rainbow. 



From Fig. 320, it will be seen that every drop in the arc of 



