6i 2 Mr. mann’s ¥, 'reatife 
tent of their courfe. This is evident to every one who 
only cafts his eyes over a map. The Rhine and the Po, 
in particular, receive each above one hundred others 
great and fmall; the Danube above two hundred; the 
Wolga as many ; the river of Amazons receives into its vaft 
bed a prodigious number, fome of which are five or fix 
hundred leagues in length, and are of fuch a depth and 
breadth as would make them elfewhere pafs for capital 
rivers. M. de buffon lt> gives a lift of the more confi- 
derable of thofe which fall into other great rivers 
throughout the known world. Many curious particulars 
may be feen in varenius’s General Geography, part I. 
chap. xvi. concerning rivers; but of a nature which 
does not enter into my plan. The works themfelves are 
in every body’s hands, and may be confulted by thofe 
who pleafe. 
This confluence of rivers is fo neceflary for propagat- 
ing the motion of the water throughout a long courfe, 
and for renewing and accelerating from time to time its 
velocity, which otherwife would be too greatly dimi- 
nilhed by the refiftance of fo many obftacles as they 
meet with in their way, that, as we have faid above (N° 
2,8.) after Signor guglielmini, it can only be attributed 
(e) Hift. Nat. tom. II. p. 75, 76. 
to 
