FT. i. Astronomy and Geology compared. 17 



been so firmly established. We may attain a yet 

 wider knowledge, we may complete our acquaintance 

 of a still more comprehensive scheme of Omnipo- 

 tence, but such additions cannot disturb the know- 

 ledge we have already attained. I will only remark, 

 that the reasoning of these gentlemen seems in great 

 degree to be founded upon the third method that 

 of experimental philosophy ; the use of the spectro- 

 scope seems to belong to it. 



When we turn to Geology, we perceive at once 

 that it stands on a far narrower basis than its sister 

 science; it derives no support from pure mathe- 

 matics. A state of things which has passed away, 

 and which we can only imperfectly conjecture, 

 cannot afford the data necessary for mathematical 

 demonstration. Perhaps some small exception may 

 be made in favour of those calculations as to time, 

 which are afforded by the accumulation of deposits 

 at the mouths of great rivers, by the rate of the 

 formation of peat morasses, or of the growth of 

 primeval forests, which may afford a loose and 

 general ground of arithmetical calculation. With 

 these trifling exceptions, Geology must rest entirely 

 upon the evidence of facts, and it must be owned 

 that these facts are neither so numerous nor so well 



