TORRENTS 01' THE HIGH ALPS. 63 



by little if the foot of the banks be undermined by the waters, but this 

 constitutes another point to be attended to, and one to which I shall attend 

 immediately, and on which, until I do so, I crave for a moment a suspension 

 of judgment. 



" To return, I give in one word the eifect of these arrangements. I may 

 say that the torrent will iind itself placed in the same conditions as if it 

 issued from the bosom of a deep forest, which will surround it in all its 

 windings, and in which it will be as if it were drowned. Elsewhere I have 

 described the results to which such a condition of things gives birth. It 

 may be remembered as the forest struggling with the water ends in extin- 

 guishing the torrent, the same effects will reproduce themselves here, and 

 it is unnecessary to repeat them. 



" By the same analogy it may be understood that the vegetation advancing 

 always, and gaining each day upon the ground, should descend on the banks 

 and carpet them almost to the bottom of the bed, as has happened in exten- 

 sive torrents ; but the giving of permanence to the banks is a result of too 

 great importance to be left thus to the caprices of the soil, and of the free 

 wiU of nature. We come thus to a third department of the work. It is one 

 in which it is especially necessary to redouble care and to multiply devices. 



" To draw the vegetation over the banks they should be cut with small 

 canals of irrigatipn derived from the torrent. These will impregnate with 

 fertilizing humidity the land now rent and dry ; they will break also the 

 slope of the declivities, and serve to render them more stable, and soon they 

 will disappear under the tufts of various plants brought to light by the water. 



" The formation of these canals being extended ultimately to the summit 

 of the bank, the water will thence penetrate the zones of enclosure and 

 fertilize their soil. It is in the retention of the water, and in the possibility 

 of opening everywhere and multiplying almost indefinitely provision for this, 

 that rests in reality the whole future of the work. 



" In fine, I pass to the fourth phase of the work, which is also the last. 

 Whilst all these plantations retain the gTOunds through which the torrent 

 flows, the undermining may be prevented by the construction of artificial 

 harrages, or wears. 



" We thus borrow from existing systems of defence that which is most 

 efficacious in them ; but in doing this how gTeatly have we ameliorated the 

 circumstances in which we set to work ! 



" Indeed, we shall find in the plantations, everywhere where it is thought 

 fit to establish these works, the best material for their construction. The 

 yoimg trees will supply stakes, prunings and bushes will supply faoines. 

 We can then construct the barricades of facines, or the wicker palisades 

 recommended by Fabre. These works will cost little for manufacture, the 

 materials will cost absolutely nothing. They will be cheap ; and they do not 

 present the dangers which accompany walls of masonry. One can then multiply 

 them everywhere without any inconvenience, and almost without expense. 



" These barricades will be like the completement of the works of extinction ; 

 they will serve to defend certain banks till the vegetation has reclothed 

 them over all their extent, and till the torrent itself shall have lost the 

 greater part of its violence. They can be employed also to stop up the 

 secondary ravines, to intercept the little ramifications, to fill up small holes ; 

 in fine, to lead over the surface of the soil, and thus completely efface those 

 innumerable streamlets divided like the hair-like fibres of a root, which are 

 really and indeed the root of the evil. 



