116 THE SEASON WHY. 



" I am come a light into the world, that whosoever believeth in me should not 

 abide in darkness." JOHN xui. 



493. Why is the lunar rainbow fainter than a solar 

 rainbow ? 



Because the light of the moon is the reflected light oj the sun, 

 and is therefore less intense. 



494. What is a halo ? 



A halo is a luminous ring, which forms between the eye of the 

 observer and a luminous body. 



Haloes may appear around the disc of the sun, moon, or stars. 

 But in this country the lunar haloes are the most remarkable and 

 frequent. 



495. What is the cause of the luminous ring ? 



The refraction of light as it passes through an intervening cloud, 

 or a stratum of moist and cold air. 



496. Why are haloes -sometimes large and at other times 

 small ? 



Because they are sometimes formed very high in the atmosphere, 

 at other times very low. Being high, and farther removed from the 

 spectator, and nearer the source of light, they appear smaller ; 

 while the nearer they are, the larger they appear. 



497. Why do haloes foretell wet weather ? 



Because they show that there is a great amount of atmospheric 

 moisture, which will probably form rain. 



498. Why do glass lustres and chandeliers exhibit* 

 " rainbow colours" ? 



Because they refract the rays of light in the same manner as 

 the rain drops. 



499. Why does a soap bubble show the prismatic colours ? 

 Because, like a large rain drop, it refracts the rays of light, and 



shows the elementary rays. 



500. What causes the rich tints displayed by " mother-of- 

 pearl?" 



The refraction, of the light that falls upon the surface of the 

 pearL 



