let down the slope. The first
effect of the levees is to raise the surface; but this, by inducing
greater velocity of flow, inevitably causes an enlargement of section,
and if this enlargement is prevented from being made at the expense of
the banks, the bottom must give way and the form of the waterway be so
improved as to admit this flow with less rise. The actual experience
with levees upon the Mississippi River, with no attempt to hold the
banks, has been favorable, and no one can doubt, upon the evidence
furnished in the reports of the commission, that if the earliest levees
had been accompanied by revetment of banks, and made complete, we should
have to-day a river navigable at low water, and an adjacent country safe
from inundation.

Of course it would be illogical to conclude that the constrained river
can ever lower its flood slope so as to make levees unnecessary, but it
is believed that, by this lateral constraint, the river as a conduit may
be so improved in form that even those rare floods which result from the
coincident rising of many tributaries will find vent without destroying
levees of ordinary height. That the actual capacity of a channel through
alluvium depends upon its service during floods has been often shown,
but this capacity does not include anomalous, but recurrent, floods.

It is hardly worth while to consider the projects for relieving the
Mississippi River floods by creating new outlets, since these
sensational propositions have commended themselves only to unthinking
minds, and have no support among engineers. Were the river bed cast-
iron, a resort to openings for surplus waters might be a necessity; but
as the bottom is yielding, and the best form of outlet is a single deep
channel, as realizing the least ratio of perimeter to area of cross
section, there could not well be a more unphilosophical method of
treatment than the multiplication of avenues of escape.

In the foregoing statement the attempt has been made to condense in as
limited a space as the importance of the subject would permit, the
general elements of the problem, and the general features of the
proposed method of improvement which has been adopted by the Mississippi
River Commission.

The writer cannot help feeling that it is somewhat presumptuous on his
part to attempt to present the facts relating to an enterprise which
calls for the highest scientific skill; but it is a matter which
interests every citizen of the