THE EARTH. 1?5 



selves, in their journeys through those trackless 

 forests. As those sinuosities, therefore, increase 

 as the river approaches the sea, it is not to be 

 wondered at that they sometimes divide, and 

 thus disembogue by different channels. The 

 Danube disembogues into the Euxine by seven 

 mouths ; the Nile by the same number j and the 

 Wolga, by seventy. 



The currents * of rivers are to be estimated 

 very differently from the manner in which those 

 writers who have given us mathematical theories 

 on this subject, represent them. They found 

 their calculations upon the surface being a per- 

 fect plain, from one bank to the other : but this 

 is not the actual state of nature ; for rivers, in 

 general, rise in the middle ; and this convexity 

 is greatest in proportion as the rapidity of the 

 stream is greater. Any person, to be convinced 

 of this, need only lay his eye as nearly as he can 

 on a level with the stream, and looking across to 

 the opposite bank, he will perceive the river in 

 the midst to be elevated considerably above what 

 it is at the edges. This rising in some rivers is 

 often found to be three feet high ; and is ever 

 increased, in proportion to the rapidity of the 

 stream. In this case, the water in the midst of a 

 current loses a part of its weight, from the velo- 

 city of its motion ; while that at the sides, for the 

 contrary reason, sinks lower. It sometimes how- 

 ever happens, that this appearance is reversed ; 

 for when tides are found to flow up with violence 



* Baffon. De Fleuves, passim, vol. ii. 



