48 HISTORY OF 



is above four thousand miles ? All, therefore, that 

 has been said of the earth, to a deeper degree, is 

 merely fabulous or conjectural : we may suppose 

 with one, that it is a globe of glass ;t with ano- 

 ther, a sphere of heated iron jt with a third, a 

 great mass of waters ; and with a fourth, one 

 dreadful volcano :|| but let us, at the same time, 

 show our consciousness, that all these are but 

 suppositions. 



Upon examining the earth, where it has been 

 opened to any depth, the first thing that occurs, 

 is the different layers or beds of which it is com- 

 posed ; these all lying horizontally one over the 

 other, like the leaves of a book, and each of 

 them composed of materials that increase in 

 weight in proportion as they lie deeper. This is, 

 in general, the disposition of the different mate- 

 rials where the earth seems to have remained un- 

 molested ; but this order is frequently inverted ; 

 and we cannot tell whether from its original for- 

 mation, or from accidental causes. Of different 

 substances, thus disposed, the far greatest part of 

 our globe consists, from its surface downwards to 

 the greatest depths we ever dig or mine.^f 



The first coat, most commonly found at the sur- 

 face, is that light coat of blackish mould which is 

 called by some garden earth. With this the earth 

 is every- where invested, unless it be washed off by 

 rains, or removed by some other external violence. 

 This seems to have been formed from animal and 

 vegetable bodies decaying, and thus turning into 



f Buffon. \ Whiston. Burnet. 



|| Kircher. \ Woodward, p. 9. 



