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HUTTONIAN THEORY. 



457 



is an anticipation, which future ages muft cer 

 tainly modify, and corred. The bell thing, 

 in the mean time, that can be done for the 

 advancement of this branch of geological know- 

 ledge. 



is to afcertain with 



adlnefs the re- 



i level of the fea, and of fuch points upon 

 the land as can be diftindly marked, and point- 



ed 



to fucceeding 



g 



This is not fo eafy 



as it may at firft appear. Where every objedt 

 changes, it is difficult to find a meafure of 

 change, or a fixed point from which the compu- 

 tation may begin. The aftronomers already feel 

 this inconvenience, and when they would refer 



their obfervations to an immoveable pla 

 fhall preferve its pofition the fam 

 they meet with difficulties, v 



all 



that 

 ages. 



:ulties, which cannot be re- 

 moved but by a profound mathematical invelli- 



gation. 



In geology, we cannot hope to be delivered 

 from this embarraffinent in the fame manner 



> 



and we have no refource but to multiply ob- 

 fervations of the difference of level ; to make 



J 



them as exad: as poffible, and to fele(5t points of 

 comparifon that have a chance of being long 

 diliinguifhed. The improvements in barome- 



^ 



trical meafurements, which give fuch facility to 

 the determination of heights, along with fo con- 



, r 



fiderable a degree of accuracy, will furnifh an 



F 



accumulation of fa'ds that muft one day be of 

 reat value to the geologift. 



Note 



