ji 



THE SEASON WHT. 51 



' He casteth forth his ice like morsels : who can stand before his word."-* 



* PS AIM CXLVIT. 



149. Why are woollen fabrics bad conductors of heat T 

 Because there is a considerable amount of air occupying thd 



spaces of the texture. 



150. Is air a good or a lad conductor ? 



Air is a lad conductor, and it chiefly transmits heat, as water 

 does, by convection. 



151. Is water a gvod or a lad conductor ? 



"Water is an indifferent conductor, but it is a letter conductor 

 than air. 



152. W ' hy, when we place our hands in water, which may 

 le of the same temperature as the air, does the^ water feel 

 some degrees colder ? 



Because water, leing a letter conductor than air, takes up the 

 warmth of the hand more rapidly. 



153. Why, when we taJce our hands out of water do they 

 feel warmer ? 



Because the air does not abstract the heat of the hand so rapidly 

 as the water did, and the change in the degree of rapidity with 

 which the heat is abstracted produces a sensation of increased 

 warmth. 



154. Why do we see llocTcs of ice wrapped in thick flannel 

 in summer time ? 



Because the flannel, being a non-conductor, prevents the external 

 heat from dissolving the ice. 



[Flannel wrapped around a warm body keeps in its "heat; and wrapped 

 around a cold body, prevents heat from passing into it.] 



155. How do we know that air is not a good conductor 

 of heat? 



Because, in still air, heat would travel to a given point much 

 more rapidly, and in greater intensity, through even an indifferent 

 solid conductor, than it would through the air. 



156. How do we know that water is not a good conductor 

 tfkeatf 



