on Rivers and Canals. 
S&7 
14. Therefore, the motion of water flowing freely in 
an inclined channel, is accelerated by its own weight 
combined with the quantity of declivity in the bed, 
Neverthelefs, the velocity of waters which flow in 
an inclined bed, during their adtual flowing, is not acce- 
lerated by the weight which the inferior waters fuftain 
from the fuperior ones, in cafe the lower parts have already, 
by the declivity of the bed, a greater velocity than that 
which the weight of the fuperior ones imprefles upon 
them. Thereafon of which is, that no body which follows 
another with a lefler velocity can adt by impulfion upon 
that which precedes it with a greater velocity, as is the 
cafe with regard to thefe fuperior and inferior waters. But 
the weight of the upper waters begins to accelerate the 
lower as foon as they fall into an horizontal bed, or one 
that is fo nearly horizontal as to deftroy the greater velo- 
city of the lower waters above that of the upper. 
15. The velocity of rivers depends fometimes upon 
the foie declivity of their beds ; fometimes alfo upon the 
foie gravity of their waters : and if thefe two caufes fome- 
times adt together, the effedt produced is only the refpec- 
tive excefs of the one above the other. It often happens 
in the fame fedtion of a river, that the acceleration of 
velocity in the inferior parts proceeds from the weight of 
4 E % the 
