THE EBASON WHY. 125 



" When it is evening ye say it will be fair weather, for the sky is red." 

 MATT. xvi. 



Because it shows that the air is heavy with vapours. The 

 refraction that produces yellow requires a greater degree of density. 



535. W hy does a red sunset foretell fine weather? 



Because the redness shows that the vapours in the air toward* 

 the West, or wet quarter, are light, as is evidenced by the degree of 

 refraction of the sun's rays. 



536. Why does a red sunrise foretell wet? 



Because it shows that towards the East, or dry quarter, the air 

 is charged with vapour, and therefore probably at other points the 

 air has reached saturation. 



537. Why does a grey sunrise foretell a dry day ? 

 Because it shows that the vapours in the air are not very dense. 



538. Why is " a rainbow in the morning the shepherd's 

 warning?" 



Because it shows that in the West, or wet quarter, the air is 

 saturated to the ram point. 



539. WJiy is " a rainbow at night the shepherd's delight ?" 

 Because it shows that the rain is falling in the East, and as that 



is a dry quarter, it will soon be over. Kainbows are always seen 

 in opposition to the sun. 



CHAPTER XXVI. 



540. Wliat is the difference between light and heat ? 



The most obvious distinction is, that light acts upon vision, and 

 heat upon sensation, or feeling. 



Another distinction is, that heat expands all bodies,and alters their 

 atomic condition ; while light, though usually attended by heat, 

 does not display the same expansive force, but produces varioui 

 effects which are p&yuliar ti itself. 



