18 Hydraulics of the Mississippi River. 
tudes, in the same proportion they are defiant of all the dogmas 
of the books, and all the laws, however carefully elaborated, of — 
hydraulic theorists. Indeed, in the very year in which the sur- — 
vey, of which we have in this report the results, was commenced, | 
there was submitted to the Bureau of Topographical Engineers, 
at Washington, a report covering a portion of the same ground, — 
viz: the question of the best means of preventing the overflows — 
of the Delta of the Mississippi, by a gentleman reputed to be 
one of the ablest civil engineers the country has produced—the 
late Col. Ellet-—in which all the received formule for determin- 
ing one of the most important elements in the inquiry—the 
mean velocity of the stream—are set aside, and a new one intro- 
duced; and in which the conclusion is reached that protection 
by levees in the lower parts of the valley, is entirely impractica- 
ble. The latter view is one which many others, both before and 
since, have strongly held: and inasmuch as this river is a subject 
which has more or less occupied the mind of every.man in the 
country having any pretensions to engineering skill, or any taste 
for this class of physical inquiries, it is a view which has been 
just as strongly discountenanced and as stoutly controverted, as 
1 n confidently maintained. Now if the science of river 
hydraulics had not been in the condition of uncertainty and im- 
perfection which we have presumed to impute to it, how could 
it be possible that a great practical problem like this, the very 
foremost in magnitude of importance that could be stated in 
regard to the grandest of our rivers, could thus divide for years — 
the opinions, not merely of the inexperts who dwell upon the | 
banks of the stream and suffer from its ravages, but of the 
mathematicians and philosophers of the whole country, who — 
exhaust, for its solution, all the resources of science; and of the — 
The Mississippi has undoubtedly been, in this country, the 
ie scl er streams, 0 
their occasional outbursts of disobedience, when they roar defi- — 
Bee 
