150 SCIENCE OF COMMON THINGS. 



Coolness of spring water. Snow protects the soil from cold. 



the intense heat cannot penetrate to the roots of the 

 plants and trees. 



908 Show the wisdom of the Creator in making the soil a bad con- 

 ductor. 



If the heat and cold could penetrate the soil deeply 

 (as freely as the heat of a fire penetrates iron), the 

 springs would be dried up in summer and frozen in 

 winter ; and all vegetation would perish. 



909 Why is water from a spring always cool, even in summer f 



Because the soil is so bad a conductor, that the burn- 

 ing rays of the sun can penetrate only a few inches below 

 the surface ; in consequence of which the springs of 

 water are not affected by the heat of summer. 



97*O How does the non-conducting power of snow protect vegetabks from 

 the frost and cold f 



It prevents the heat of the soil from being drawn off 

 by the cold air which rests upon it. 



97*1 Why is snow a non-conductor of heat ? 



Principally because it contains a large quantity of 

 air between its particles. 



97*3 Why is it cool under a shady tree in a hot summer's day ? 



1. Because the overhanging foliage screens off the 

 rays of the sun / 



2. As the rays of the sun are warded off, the cir 

 (beneath the tree) is not heated by the reflection of the 

 soil; and 



3. The leaves of the trees, being non-conductors, 

 also obstruct the transmission of heat. 



97*3 Why does a metal spoon (left in a kettle) retard the process of 

 boiling f 



Because the metal spoon (being an excellent con- 

 ductor) carries off the heat from the water , and (as 

 heat is carried off by the spoon) the water takes a 

 longer time to boil. 



97*4 Why does paint preserve wood f 



1. Because it covers the surface of the wood, and 

 prevents both air and damp from penetrating into the 

 pores ; 



