116 THE CHEMISTRY OF CREATION. 



by figures or language. There are three 

 methods of explaining this curious fact. Very 

 probably all three together are actually necessary 

 in order to explain the whole phenomena of the 

 temperature of the crust of the earth. The first 

 supposes it to be chiefly due to the absorption 

 of heat from the sun. The second supposes 

 that it is due to great chemical changes taking 

 place in the substances forming the crust of the 

 earth. And the third conceives the existence 

 of a vast central body of fire in the interior of the 

 earth. It is certain that from each of these causes 

 separately heat may be communicated to the crust 

 of our globe. 



The heat-rays of the sun accompany the 

 beams of light, and striking upon the surface 

 of the earth, become absorbed by it. A large 

 portion of them are radiated back again into 

 the air, but another portion become conducted 

 from particle to particle of the rocks and other 

 materials of the earth's crust, and thus pene- 

 trate some distance into it. Of course the parts 

 of the earth nearest the equator, where most of 

 the solar influence is felt, receive most heat, 

 and there it penetrates farthest into the crust 

 of the earth. The regions near the poles receive 

 least, and there of course the heat of the sun 

 penetrates but a very short distance into the 

 crust. Although much heat is lost by radiation 



