On the Declivities of Mountains. 29 



This, and other queftions which will fugged themfelves, 

 can only be fatisfadorily anfwered by experiment. It teems 

 at leaft poffible, however, that the remits might be different 

 if fufion could be effe&ed under circumftances which fliould 

 preclude the poffibility of extraneous admixture. It is, per- 

 haps, not altogether abfurd to fuppofe that the mafs might in 

 that cafe entirely retain its original colour ; and that at fome 

 future, and perhaps not a very diftant period, fmall ftones and 

 fragments may be fufed into larger maffes poffefiing all the 

 properties of the natural gems with as much certainty as 

 metals are now caft into ingots. 



[To be continued.] 



V. An EJfay on the Declivities of Mountains. By Rich akd 

 Kirwan, Efq. LL.D. F.R.S. and Prejident of the Royal 

 Irijh Academy *. 



XXMONG the various caufes to whofe activity the planet 

 we inhabit owes its prefent wonderfully diverfified appear- 

 ance, fome undoubtedly exerted their influence from its very 

 origin, and others at fubfequent periods ; of thefe laft, one 

 at leaft, namely, the Noachian deluge, was univerfal in its 

 operation, while the effe&s of many more were partial and 

 local, fuch as thofe refulting from earthquakes, volcanos, 

 particular inundations, &c. 



In a general furvey of the globe it is only to general caufes 

 whofe operation was univerfal that our attention can be di- 

 reded, the effefts of partial caufes being the proper objects 

 of the geological hiftory of thofe countries that were parti-, 

 cularly aflecled by them. 



But to diftinguifh caufes of the former clafs from thofe 

 whofe operation was more confined, it is necefiary to difcover 

 fome character by which their efle&s may unequivocally be 

 difcemed. 



Now, a general uniformity, or agreement in fome particular 

 circumftance, in every part of the globe, feems to be a fure 

 tefl of the operation of fome general caufe. The difcovery 

 of uniform appearances is therefore of primary importance 



; ' From the Tumjaclkns of (be Royal Irijb Academy for 1S00. 



in 



