378 Phenomena of the [Book III. 



part of the globe j the yellow, the green, the blue 4 

 and the purple rays will each be refracted to another 

 point. A part of the light, as refracted, will be tranf- 

 mitted, but a part will alfo be reflected ; the red rays 

 at the point A, and the others at certain other points, 

 agreeably to their angle of refraction. 



It is very evident, that if the fpectator's eye is placed 

 in the direction of M W, or the courfe of the red- 

 making rays, he will only diftinguifli the red colour j 

 if in another flation, he will fee only by the yellow 

 rays j in another by the, blue, &c. : but as in a fhower 

 of rain there are drops at all heights and all ditlances, 

 all thofe that aye in a certain pofidon with refpect to 

 the fpectator will reflect the reel' rays, all thbfe in the 

 next flation the orange, thofe in the next the gretn, 

 &c. 



To avoid confufion let us for the prejent imagine 

 only three drops of rain, and three degrees of colours 

 in the fection of a bow (Plate XXIV. Fig. 54.) It 

 is evident that the angle C E P is lefs than the angle 

 B E P, and that the angle A E P is the greateft of 

 the three. This largeft angle then is formed by the 

 red rays, the middle one confifts of the green, and 

 the fmalleft is the purple. All the drops of rain, 

 therefore, that happen to be in a certain pofition to 

 the eye of the fpctator, will reflect the red rays, and 

 form a band or femicircle of red ; thofe again in a 

 certain pofition will prefent a band of green, &c. If 

 lie alters his ftation, the fpectator will ftill fee a bow, 

 though not the iame bow as before ; and if there arc 

 many fpectators they will each fee a different bow, 

 though it appears to be the lame. 



There are fometimes feen two bows, one formed as 

 has been defcr.bed, the other appearing externally to 

 embrace jhe primary bow, and which is fometimes 



' called 



