CONDUCTION. 



33 



from the body. It -escapes more or less through all 

 substances, but less rapidly through the fibrous materi- 

 als just mentioned, and therefore their superiority for 

 winter clothing. If we lived in an atmosphere hotter 

 than our bodies, the object of clothing would be to ex- 

 clude heat, and the same non-conducting materials now 

 used would be best adapted for this purpose also. 

 Sometimes it is actually the object of clothing to keep 

 out heat ; as, when workmen enter hot furnaces in cer- 

 tain manufacturing processes. Thick clothing, of non- 

 conducting materials, is obviously best in this case also. 

 In summer, coarser fibre of linen, which is a better 

 conductor than cotton or wool, is more used, because 

 it conveys away the heat of the body more rapidly, as 

 is desirable in the warmer season. 



63. FURS OF ANIMALS. We see, in 



Why has the , . , , . 



Deity varied what has been stated, the reason why the 

 ninuffl 9 * Deity has clothed animals inhabiting cold 

 climates with fine furs. While the elephant 

 of the torrid zone has but a few straggling hairs, the 

 polar bear has a thick coat of fine fur to keep in his vi- 

 tal heat, and enable him to endure the extreme rigor 

 of a northern climate. So the sea-fowl has a thick 

 covering of soft down to protect him from the cold of 

 the ocean, while the ostrich has an open coat of scanty 

 feathers. 

 ,, r , , 64. WARMTH OF SNOW. Snow keeps 



Why does snow r 



tend to keep the earth warmer in winter than it would 



otherwise be, not because of any heat it 

 imparts, but because, by reason of its low 

 conducting power, and that of the air which it con- 



2* 



