2 76 GENERAL SCIENCE 



the opposite surface of the drop so that it comes out 

 of the drop in the direction toward us. The falling 

 drops act on the light just as the flask in the illustra- 

 tion did. 



The illustration on this page represents a natural 

 rainbow with a secondary one above it. The secondary 

 bow is usually seen only in part. Since the rainbow is 

 in a comparatively fixed position at any one time, and 

 since a drop of falling water must be in a certain position 



with respect to us in 

 order to refract and 

 reflect the light to 

 us, the time during 

 which one drop helps 

 to make the rainbow 

 is a very small frac- 



SHOWING HOW PRIMARY AND SECONDARY tion of a second. So 

 RAINBOWS ARE FORMED ,, . ,,. , 



the falling drops must 



be quite numerous in order to make a continuous colored 

 arch. Since violet is refracted more than red, the violet 

 appears on the inside of the circle and the red at the 

 outer edge, with the other colors between. As the drop 

 descends through the position where it will throw the 

 colors to our eye, the ray of light, a, passes into the lower 

 part of the drop, is reflected twice from the opposite sur- 

 face, and then refracted again as it comes out. As violet 

 is refracted most, the drop will throw violet color to our 

 eyes first from position v, followed by the other colors of 

 the spectrum, ending with red in position r. From r the 

 drop passes down into a space from which it cannot throw 

 any colors to our eyes until it descends to position /. 

 Here the ray of light fr, passing into the upper part of 

 the drop, is refracted, then reflected from the opposite side, 



