510 TRANSVERSE EMBANKMENTS. 
man, too, spared a reasonable proportion of the forests of the 
Alps, and not attempted to control the natural drainage of the 
surface, the Po, it has been said, would resemble the Nile in all 
its essential characteristics, and, in spite of the difference of 
climate, perhaps be regarded as the friend and ally, not the 
enemy and the inyader, of the population which dwells upon 
its banks. 
But it has been shown by Humphreys and Abbot that the 
system of longitudinal dikes is the only one susceptible of ad- 
vantageous application to the Mississippi, and if we knew the 
primitive geography and hydrography of the basin of the Po as 
well as we do those of the valley of the great American river, 
we should very probably find that the condemnation of the 
plan pursued by the ancient inhabitants of Lombardy is a 
too hasty generalization, and that the case of the Nile is an 
exception, not an example of the normal régime and condition 
of a great river.* 
But in any event, these theoretical objections are counsels 
apres coup. The dikes of the Po and probably of some of its 
tributaries were begun before we have any trustworthy physical 
or political annals of the provinces they water. The civilization 
of the valley has accommodated itself to these arrangements, 
* Embankments have been employed on the lower course of the Po for at 
least two thousand years, and for some centuries they have been connected in 
a continuous chain from the sea tothe vicinity of Cremona. From early ages 
the Italian hydrographers have stood in the front rank of their profession, and 
the Italian literature of this branch of material improvement is exceedingly 
voluminous, exhaustive, and complete. 
‘“‘ The science of rivers after the barbarous ages,” says Mengotti, ‘‘ may be 
said to have been born and perfected in Italy.” The eminent Italian engineer 
Lombardini published in 1870, under the title of Guida allo studio del? idrolo- 
gia fluviale e del? Idraulica pratica, which serves both as asummary 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, will have very 
frequent occasion to consult Italian authorities, and in the very valuable Re- 
port of Humphreys and Abbot on the Mississippi, America has lately made a 
contribution to our potamological knowledge, which, in scientific interest and 
practical utility, does not fall short of the ablest European productions in the 
same branch of inquiry. 
