EMBANKMENTS OF THE TO. 
411 
Tlie valley of the Po has probably not been cultivated or 
inhabited so dong as that of the Nile, but embankments have 
been employed on its lower course for at least two thousand 
years, and for many centuries they have been connected in a 
continuous chain. I have pointed out in a former chapter the 
effects produced on the geography of the Adriatic by the de¬ 
posit of river sediment in the sea at the mouths of the Po, the 
Adige, and the Brenta. If these rivers had been left uncon¬ 
fined, like the Nile, and allowed to spread their muddy waters 
at will, according to the laws of nature, the slime they have 
carried to the coast would have been chiefly distributed over the 
plains ol Lombardy. Their banks would have risen as fast as 
their beds, the coast line would not have been extended so far 
into the Adriatic, and, the current of the streams being conse¬ 
quently shorter, the inclination of their channel and the 
rapidity of their flow would not have been so greatly dimin¬ 
ished. Had man spared a reasonable proportion of the forests 
of the Alps, and not attempted to control the natural drainage 
of the surface, the Po would resemble the Nile in all its essen¬ 
tial characteristics, and, in spite of the difference of climate, 
perhaps be regarded as the friend and ally, not the enemy and 
the invader, of the population which dwells upon its banks.* 
it spreads over the soil of Egypt every hundred years. Not from the 
White Nile, for that river drops nearly all its suspended matter in the 
broad expansions and slow current of its channel south of the tenth degree 
of north latitude. Nor does it appear that much sediment is contributed 
by the Bahr-el-Azrek, which flows through forests for a great part of its 
course. I have been informed by an old European resident of Egypt, who 
is very familiar with the Upper Nile, that almost the whole of the earth 
with which its waters are charged is brought down by the Takazz6. 
* It is very probably true that, as Lombardini supposes, the plain of 
Lombardy was anciently covered with forests and morasses (Baumgarten, 
1. c. p. 156) ; but, had the Po remained unconfined, its deposits would have 
raised its banks as fast as its bed, and there is no obvious reason why this 
plain should be more marshy than other alluvial flats traversed by great 
rivers. Its lower course would probably have become more marshy than 
at present, but the banks of its middle and upper course would have been 
in a better condition for agricultural use than they now are. 
