102 ILLUSTRATIONS OF THE 



changing ; the alluvial land at the mouths of the 

 rivers ; the bars that feem to oppofe their dif- 

 charge into the fea, and the {hallow nefs of the 

 fea itfelf. On fuch coafts, the land ufually 

 feems to gain upon the fea, whereas, on iliores 

 of a bolder afped, it is the fea that generally 

 appears to gain upon the land. What the land 

 acquires in extent, however, it lofes in eleva- 

 tion ; and, whether its furface increafe or di- 

 minilh, the depredations made on it are in both 

 cafes evinced with equal certainty. 



99. If w^e proceed in our furvey from the 

 ihores, inland, we meet at every ftep with the 

 fuUeft evidence of the fame truths, and parti- 

 cularly in the nature and economy of rivers. 

 Every river appears to confifl of a main trunk, 

 fed from a variety of branches, each running in 

 a valley proportioned to its lize, and all of them 

 together forming a fyftem of vallies, communi- 

 cating with one another, and having fuch a nice 

 adjuftment of their declivities, that none of 

 them join the principal valley, either on too 

 high or too low a level ; a circumftance which 

 would be infinitely improbable, if each of thefe 

 vallies were not the work of the flream that 

 flows in it. 



If indeed a river confifled of a fingle ftream, 

 without branches, running in a ftraight val- 

 ley, it might be fuppofed that fome great con- 



cuffion 



} 



A. 



