RIVER EMBANKMENTS. 
385 
lower point, where the rapidity of its flow is checked by a 
diminution in the inclination of the bed, by a wider channel, 
or finally by a lacustrine or marine basin which receives its 
waters. Wherever it lets fall solid material, its channel is 
raised in consequence, and the declivity of the whole bed 
between the head of the embankment and the slack of the 
stream is reduced. Hence the current, at first accelerated by 
confinement, is afterward checked by the mechanical resist¬ 
ance of the matter deposited, and by the diminished inclina¬ 
tion of its channel, and then begins again to let fall the earth 
it holds in suspension, and to raise its bed at the point where 
its overflow had been before prevented by embankment. The 
bank must now be raised in proportion, and these processes 
would be repeated and repeated indefinitely, had not nature 
provided a remedy in floods, which sweep out recent deposits, 
burst the bonds of the river and overwhelm the adjacent coun¬ 
try with final desolation, or divert the current into a new 
channel, destined to become, in its turn, the scene of a similar 
struggle between man and the waters. 
Few rivers, like the Nile, more than compensate by the 
fertilizing properties of their water and their slime for the 
damage they may do in inundations, and, consequently, there 
are few whose floods are not an object of dread, few whose 
encroachments upon their banks are not a source of constant 
anxiety and expense to the proprietors of the lands through 
which they flow. River dikes, for confining the spread of 
currents at high water, are of great antiquity in the East, and 
those of the Po and its tributaries were begun before we have 
any trustworthy physical or political annals of the provinces 
upon their borders. From the earliest ages, the Italian hy¬ 
draulic engineers have stood in the front rank of their profes¬ 
sion, and the Italian literature of this branch of material im¬ 
provement is exceedingly voluminous. But the countries for 
which I write have no rivers like the Po, no plains like those 
of Lombardy, and the dangers to which the inhabitants of 
English and American river banks are exposed are more nearly 
analogous to those that threaten the soil and population in the 
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