494 LEVEES OF THE MISSISSIPPI. 



But in any event, these theoretical objections are counsels 

 ajpres coup. The dikes of the Po, and probably of some of ita 

 tributaries, were begun before we have any trustworthy physical 

 or political annals of the provinces they water. The civilization 

 of the valley has accommodated itseK to these arrangements, and 

 the interests which might be sacrificed by a change of system are 

 too vast to be hazarded by what, in the present state of our knowl- 

 edge, can be only considered as a doubtful experiment.* 



The embankments of the Po, though they are of vast extent 

 and have employed centuries in their construction, are inferior 

 in magnitude to the dikes or levees of the Mississippi, which are 

 the work of scarcely a hundred years and of a comparatively 

 sparse population. On the right or western bank of the river, 

 the levee extends, with only occasional interruptions from high 

 bluffs and the mouths of rivers, for a distance of more than. 

 1,100 miles. The left bank is, in general, higher than the right, 

 find upon that side a continuous embankment is not needed ; but 

 the total length of the dikes of the Mississippi, including those of 

 the lower course of its tributaries and of its hayous or natural 

 emissaries, is not less than 2,500 miles. They constitute, there- 

 fore, not only one of the greatest material achievements of the 

 American people, but one of the most remarkable systems of 

 physical improvement which has been anywhere accomplished 

 in modern times. 



Those who condemn the system of longitudinal embankments 

 have often advised that, in cases where that system can not be 



gia flumale e delV Idraulica pratica, a manual which serves both as a sum- 

 mary of the recent progress of that science and as an index to the literature of 

 the subject. The professional student, therefore, as well as the geographer, 

 wiU have very frequent occasion to consult Italian authorities, and in the very 

 valuable Report of Humphreys and Abbot on the Mississippi, America has- 

 lately made a contribution to our potamological knowledge, which, in scien- 

 tific interest and practical utility, does not fall short of the ablest European 

 productions in the same branch of inquiry. 



* Duponchel advises a resort to the "heroic remedy" of sacrificing, or con 

 verting into cellars, the lower stories of houses in cities exposed to river inun 

 dation, filling up the streets, and admitting the water of floods freely over the 

 adjacent country, and thus allowing it to raise the level of the soil to that 

 of the highest inundations. — Traite d' Rydraulique et de Qeologie Agricolea^ 

 Paris, 1868, p. 241. 



