118 WTERATURE ON TOERENTS, 



and the same time, on the deKvery of water, and on the consolidation of 



the soil. , , . , , 



" M. Surell did not confine himself to preacmng the reboisement of the 

 mountains, he pointed out at the same time the advantages to be derived 

 from ffozonnement, and from small artificial works of consolidation formed of 

 facines properly disposed in the ravines. 



" His logical mind perceived the advantages which might be derived from 

 more extensive and costly artificial works, but he did not believe it possible 

 to guarantee their solidity and their durability under the circumstances in 

 which they would be erected. 



" MM. Scipion Gras et Phillipe Breton have also loudly proclaimed, in a 

 way the most e^splicit, that the boisement of the valley appeared to them the 

 most efficacious measure which could be adopted against torrents, and that 

 it was only in default of proceedings with a view to extinction being adopted 



the application of which, when they wrote, was still surrounded with 



obscurity and uncertainty — that they proposed the measures they did, as 

 means of diminishing, at least provisionally, the danger. 



" I do not feel called upon to relate here the difficulties and vicissitudes, 

 moral and administrative, which the foresters had to encounter and over- 

 come in the commencement of the operation. 



" The alarms of the peasants, in regard to their pastoral interests, were 

 such that they rose in open rebellion. The ferment was extreme in all the 

 mountain regions, more especially in the region of the Alps ; and, as always, 

 political passions and local animosities mixed themselves up with the question 

 at issue and envenomed the discussion. 



" Now this agitation is almost calmed down, and it is but right to acknow- 

 ledge that this happy result is due in a great measure to the spirit which 

 presided over the direction of the operation. 



" The means at our command form three categories : boisement, gazonne- 

 ment, and artificial works of consolidation. In order to determine precisely 

 to what extent, and in what circumstances, each of these means should be 

 adopted, it is necessary to study apart their respective actions, and after- 

 wards resume, in a general discussion of the question, the system to be 

 adopted in a plan of extinction." And he proceeds accordingly. 



In speaking of the good done by forests on the face of mountains, forming 

 a basin drained.by water-ooiirses, he says their beneficial action is manifold ; 

 and though this manifold action it may be difficult to unfold, the attempt 

 to do this wiU place, beyond all question that their beneficial action of the 

 water-course is at once most marked and considerable. 



" In the discussions which have taken place on this subject," says he, 

 " the point which has engrossed attention to some extent has been almost 

 exclusively the permeability or impermeability of the soil, and the propor- 

 tion borne by the water absorbed to that which flows off'. This is certainly 

 an important question, and no difficulty is found in showing that forests 

 diminish to an enormous extent the amount of water which flows aft'ay ; 

 but the service which they render is perhaps greater still in regulating, as 

 they do, the flow, and in securing the delivery of only water of perfect 

 fluidity. 



" The study of torrents has shown that the evil done consists not so much 

 in the greater or less volume of water discharged as in the disturbances or 

 perturbations of the flow connected with this. The principal causes of 

 these are sudden changes or variations in the delivery and in the degree of 



