SUITE DE li'^TUDE, ETC., BY CEZANNE. 101 



whether it be accompanied by snow or by rain, &c. These observations are so 

 simple that the guards who live on the mountains will be able to make them. , 

 " What I have mentioned will, I trust, make it very plain that on the 

 Alps gazonnement alone is not enough ; this opinion is no longer disputed in 

 Tessino, where, as I have already said, the herbage is exceedingly good ; 

 observations on the rise of torrents in the ravines which descend from the 

 pastures of our own Alps give the same results. 



" Lb Buissonnement. — I have often spoken of huissonnement, or planting 

 with shrubs, as being enough to put an end to Alpine torrents ; this opinion 

 I now beheve to be erroneous. Shrubs may undeniably be of great use — 

 they may be able to cope with purely local accidents, but in no circum- 

 stances can they be substituted for a zone of forest. I think I have explained 

 before that Alpine forests create on the surface a bed of humus possessing 

 great hydroscopicity. Shrubs do not supply similar results — it is in this 

 they are inferior. They consolidate the earth well enough, but with rare 

 exceptions there is not found under them the thick mobile layer which 

 carpets large forests, and thus the soil receives atmospheric influences too 

 directly. In conclusion, I may cite in support of my opinions the mountains of 

 Tessino, which surround BeUinzona; which are well turfed, and covered 

 with beautiful shrubs, but amongst which are found ravines and erosions. 



" Looked at in regard to the regulation of the water flow, there is not 

 much difference to be remarked between places which are turfed and those 

 which are covered with bushes ; whilst in the upper part of the valley of 

 Tessino, towards Airolo, there is proved to be an enormous difference 

 between the rise of torrents in the wooded valleys and in those which are 

 not wooded. 



"Les Forets. — Forests are on a grand scale what meadows and shrubberies 

 are on a small one ; their effects are — (1) The formation by their detritus of 

 a highly hydroscopioal bed, and in consequence of this auginenting the quan- 

 tity of water retained by the soil ; (2) The augmentation of the surface of 

 the dispersion of the water ; (3) The augmentation of the permeability 

 and capillarity of the subsoil." 



In 1872 appeared the Supplement by M. Ernest Cezanne, Tngdnieur des 

 Fonts et Chaussies, Representant des Eautes Alpes a VAssemhlee Nationale, 

 to the work of M. Surell, published conjointly with a second edition of the 

 work, and containing a review of treatises which had been published, and of 

 works which had been executed, in the interval which had elapsed subse- 

 quently to the original publication of that work. 



In this work, while holding that deboisement, or clearing away of forests, 

 is not always aud everywhere to be condemned, but is imnany circumstances 

 necessary for agriculture and the promotion of civilization, and that the 

 general reboisement of the Alps would be the ruin of the country, M. C6zanne 

 states that the great service rendered by Surell was the disengaging and 

 treating apart from the general question of forest science the special pro- 

 blem, of local importance, relative to the effect of forests on water-courses, 

 which, being carefully defined, was thus prepared for treatment according 

 to scientific method. 



In an introductory chapter he gives a condensed history of deboisement, 

 or the destruction of woods in France. In a second chapter he gives a 

 careful discussion of the question, — Has the deboisement of France modified 

 the mean annual temperature of the country either one way or the otherj 



