THE HEASON WHY. 61 



' But the wise answered saying, Not so ; lest there be not enough for us and 

 you : but go ye rather to them that sell, and buy for yourselves." MATT. xxv. 



Because rays of heat may be reflected in the same manner as the 

 lays of light. 



21 1. Why would not the same effect arise if the plate were 

 of a black or dark substance ? 



Because black and dark substances are not good reflectors of 

 heat. 



212. What are the lest reflectors of heat ? 



Smooth, light-coloured, and highly polished surfaces, especially 

 those of metal. 



213. Why does meat become cooked more thoroughly and 

 quickly when a tin screen is placed before the fire ? 



Because the bright tin reflects the rays of heat back again to the 

 meat. 



214. Wliy is reflected heat less intense than the primary 

 heat ? 



Because it is impossible to collect all the rays, and also because a 

 portion of the caloric, imparting heat to the rays, is absorbed by the 

 air, and by the various other bodies with which the rays come in 

 contact. 



215. Can heat be reflected in any great degree of intensity? 



Yes ; to such a degree that inflammable matters may be ignited 

 by it. If a cannon ball be made red hot, and then be placed in an 

 iron stand between two bright reflectors, inflammable materials, 

 placed in a proper position to catch the reflected rays, will ignite 

 from the heat. 



There is a curious and an exceptional fact with reference to reflected heat, 

 for which we confess that we are unable to give " The Reason Why." It is 

 found that snow, which lies near the trunks of trees or the base of upright 

 stones, melts before that which is at a distance from them, though the sun may 

 shine equally upon both. If a blackened card is placed upon ice or snow under 

 the sun's rays, the frozen body underneath it will be thawed before that winch 

 surrounds it. But if we reflect the sun's rays from a metal surface, the result is 

 directly contrary the exposed snow is the first to melt, leaving the card 

 standing as upon a pyramid. Snow melts under heat which is reflected from tho 

 trees or stones while it withstands the effect of the direct solar raw.?. la 

 passing through a cemetery this winter (1857), when the snow lay deep, we 



