GEOLOGY. 79 



distance from its surface to its centre, almost 4OOO 

 milc;s ; but of this no greater depth than somewhat 

 more than half a mile has beeu actually investigated, 

 nor more than ten miles can be at all speculated 

 upon ; consequently it is the very external part, or mere 

 crust of the earth, with which we are at all acquainted. 



The Scripture informs us, that " in the beginning 

 God created the heavens and the earth," but when that 

 beginning was we know not. 



The creation of the earth has been referred as to 

 time, to the creation of man, which may have been 

 nearly 60OO years since ; but the geologist, from various 

 observations, is led to conclude that the earth must 

 have existed for ages antecedent to that period. 



In order to explain the various changes that the earth 

 has undergone, various theories have been adduced ; 

 but as they, for the most part, appear chimerical and 

 absurd, they will be here passed over. An opinion of 

 "VVhiston, however, deserves notice, as it has been some- 

 what strengthened by recent experiments. He sup- 

 posed that the earth was originally a comet, and that 

 its nucleus, or internal part, was still in a state of in- 

 candescence, from its having retained a great portion 

 of the heat which it w r as supposed to have acquired 

 through its proximity to the sun. 



That the earth had originally a cometic form has been 

 argued and supported by philosophers of the present day; 

 and it is known, by experience, that the lower we 

 descend into the earth the warmer it is, the heat in- 

 creasing, below a certain depth, according to Professor 

 Phillips, one degree in about every 60 feet, so that in 

 some deep mines the heat is so oppressive, that the 

 miner, although very thinly clad, can with difficulty 

 pursue his labours.* 



Assuming that the materials which compose the 

 lower rocks were once in a fluid state and there is 



* The Bath and Bristol, and other mineral waters, as also the 

 waters from the Artesian Wells in France, afford a presumptive proof 

 of the internal heat of the earth. 



