252 STUDIES OF NATURE. 



penditure. Mod of thofe lakes are of an incredible 

 depth ; they anfwer feveral other purpofes, fuch 

 as that of receiving the melted fnows of the adja- 

 cent mountains, which would otherwife flow with 

 too great rapidity. When they are once full, it 

 requires a very conliderable time to exhauil them. 

 They exift, either internally or externally, at the 

 fource of all regular currents of water ; but when 

 they are external, they are proportioned, either by 

 their extent, or by their depth and their difcharges, 

 to the fize of the river which they are defigned to 

 emit, as well as the peaks which are in the vici- 

 nity. Thefe correfpondencies mufh have undoubt- 

 edly been known to Antiquity ; fori think 1 have 

 feen fome very ancient medals, in which rivers 

 were reprefented by figures leaning on an urn, and 

 flretched along at the bafis of a pyramid ; which 

 was probably defigned to denote at once their 

 fource and their difcharge. 



If, then, we come to apply thefe general difpo- 

 fitions of Nature to the particular conformation of 

 iflands, we fliall fee that they have, like Conti- 

 nents, mountains with branches parallel to their 

 bays ; that thefe mountains are of an elevation 

 correfponding to their diftance from the Sea ; and 

 that they contain peaks, lakes, and rivers, propor- 

 tional to the extent of their territory. Like Con- 

 tinents, too, they have their mountains difpofed in 



a fuit- 



