RIVER EMBANKMENTS. 503 
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 country 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.* 
But here, as in so many other fields where nature is brought 
into conflict with man, she first resists his attempts at inter- 
ference with her operations, then, finding him the stronger, 
quietly submits to his rule, and ends by contributing her aid to 
strengthen the walls and shackles by which he essays to confine 
her. If, by assiduous repair of his dikes, he, for a considerable 
time, restrains the floods of a river within new bounds, na- 
ture, by a series of ingenious compensations, brings the fluc- 
tuating bed of the stream to a substantially constant level, and 
eddies, and of course deposits, and because the prolongation of the course of 
the stream, or the advance of its delta into the sea, is accelerated.’’— Dei congi- 
amentt ciu soggiacque Vidraukca condizione de Po, etc., pp. 41, 42. 
Del Noce states that in the levellings for the proposed Leopolda railway, he 
found that the bed of the Sieue had been permanently elevated two yards be-. 
tween 1708 and 1844, and that of the Fosso di San Gaudenzio more than a 
yard and a half between 1752 and 1845. These, indeed, are not rivers of the 
rank of the Po; but neither are they what are technically called torrents or 
mountain streams, whose flow is only an occasional effect of heavy rains or 
melting snow.—Z7attato delle Macchie e Foreste di Toscana, Firenze, 1857, p. 
29. 
* The Noang-ho has repeatedly burst its dikes and changed the channel of 
its lower course, sometimes delivering its waters into the sea to the north, 
sometimes to the south of the peninsula of Chan-tung, thus varying ils point of 
discharge by a distance of 220 miles.—HLIs&E Recuus, La Terre, t. i., p. 477, 
See interesting notices of the lower course of the Noang-ho in Nature, Nov. 
25, 1869. 
The frequent changes of channel and mouth in the deltas of great rivers are 
by no means always an effect of diking. The mere accumulation of deposits 
in the beds of rivers which transport much sediment compels them continually 
to seek new outlets, and it is only by great effort that art can keep their points 
of discharge approximately constant. The common delta of the Ganges and 
the Brahmapootra is in a state of incessant change, and the latter river is said 
to have shifted its main channel 200 miles to the west since 1785, the revolu- 
tion having been principally accomplished between 1810 and 1830. 
