604 Mr. mann’s freatife 
percuffion of the ftream, and open new beds in grounds 
lower than what the old one is become. 
8thly, Hereupon the ftate of the okl bed will entirely 
depend on the quantity of water, and on the velocity and 
direction of the current in the new one; for immediately 
after this divifion of the waters into two beds is made, 
the velocity of the current in the old one will be dimi- 
nilhed in proportion to its lefs depth. In confequence 
thereof, the waters therein will precipitate more of their 
mud, occ. in equal fpaces than they did before; which 
will more and more raife up the bottom, fometimes even 
till it becomes equal with the furface of the ftream. In 
this cafe, all the water of the river will pafs into the new 
bed, arid the old one will remain intirely dry. It is well 
known, that this has happened to the Rhine near Ley- 
den, and to many other rivers. 
, 9thly, Hence the caufe of the formation of the new 
branches and mouth, whereby many great rivers dis- 
charge their waters into the fea. 
43. But in proportion as a river , that has none of the fe 
objlacles in its bed , approaches towards its mouth, we fee 
the velocity of its current augment, at the fame time 
that the declivity of the bed diminifhes, the caufes of 
which have been explained above (N° 29.). It is for this 
xeafon, that inundations are more frequent and conft- 
1 derable 
