616 Mr. mann’s Treat if e 
as much or more difcharge of the water, and confequently 
of declivity for the running off of the back-waters, may 
be loft, as has been gained by the reparation into dif- 
ferent beds. 
This difadvantage may be eafily remedied in thole 
new channels and months of rivers which are dug by 
hands, and have fluices placed in them at the point of 
reparation from the original bed; for thefe fluices of 
communication need be opened only when there is a 
fuper-abundance of water in the river, fufficient to keep 
up the velocity in each of the channels ; at other times 
they may be kept fhut, and the waters retained in their 
original bed. 
52. It was for this purpofe, of preventing the damages 
proceeding from immoderate inundations, that the an-r 
cient Egyptians dug vaft lakes, and made fo many canals 
and fluices of communication between the Nile and thofe 
lakes, and from thence to the fea; that they might 
thereby be able to difcharge the waters into thofe refer- 
voirs if they came down in too great abundance, or let 
them off again from thence upon the land, if the quan- 
tity of the natural inundation at any time was lefs than 
what was neceffary for the good of the country. By thefe 
means ancient Egypt was always matter of its waters. 
1 If 
