The Rainbow. 209 



light will escape at *, and the rest, instead of 

 escaping to w 9 will be reflected to t ; from this, 

 part will escape to x, and part will be again re- 

 flected to u 9 where it suffers another refraction, 

 and is sent to the eye at g, where the violet rays 

 will be first visible, and then the others in suc- 

 cession. 



Now each drop of rain may be considered as 

 a small globe, and within a certain range will 

 refract and reflect the light in the manner above 

 described. To make the matter still plainer, 

 therefore, let us for the present imagine only 

 three drops of rain, and three degrees of colours 

 in the section of a bow (fig. 82). It is evident 

 that the angle CFE is less than the angle BFE, 

 and that the angle AFE is the greatest of the 

 three. This largest angle then is formed by the 

 red rays, the middle one consists of the green* 

 and the smallest is the purple. All the drops 

 of rain, therefore, that happen to be in a cer- 

 tain position to the eye of the spectator, will 

 reflect the red rays, and form a band or semi- 

 circle of red; those again in a certain position 

 will present a band of green, &c. If he alters 

 his station, the spectator will still see a bow, 

 though not the same bow as before; and if there 

 are many spectators, they will each see a different 

 bow, though it appears to be the same. 



The phsenomenon assumes a circular appear- 

 ance, because it is only at certain angles that the 

 coloured or refracted rays are visible to our eyes, 



