590 Mr. mann’s 'freatife 
fhall proceed to point out the moft efficacious methods of 
preventing them, or at leaft of diminifhing their effedts. 
Perhaps it would have been more proper to have deferred 
doing this till I Ihould have faid all I have to fay upon 
the nature of rivers and canals : however, I fhall forego 
the more fcientific order of things, for the fake of 
bringing the means of remedying the accidents and 
inconveniences which happen, nearer to the caufes 
that produce them, whereby their connexion and effi- 
cacity may be better judged of. For this end, I fhall 
here lay down, briefly and in general terms, the methods 
moft proper for the purpofe in queftion. They flow im- 
mediately from the principles already laid down in this 
effay, and do not need many words to make them com- 
pleatly underftood. 
37. A work of this kind, if it is properly conduced,, 
muft be begun at the lower end of the river or canal; 
that is to fay, at that end where their waters are dif- 
charged into the fea, or where they fall into fome other 
greater river or canal, from whence their waters are car- 
ried off without farther hindrance. If it is a river whofe 
bed, by being filled up with mud, fand, or other obfta- 
cles, and by being otherwife become irregular in its 
courfe, is thereby often fubjecft to inundations, and in- 
capable of internal navigation, the point, from which 
2 the 
