230 INFLTJEJSrCE OF THE FOREST OlST FLOODS. 



The value of tlie forest as a meclianical check to a too rapid dis- 

 charge of rain-water was exemplified in numerous instances in 

 the great floods of 1866 and 1868, in France and Switzerland, 

 and I refer to the observations made on those occasions as of spe- 

 cial importance, because no previous inundations in those coun- 

 tries had been so carefully watched and so well described by com- 

 petent investigators. In the French Department of Lozere, which 

 was among those most severely injured by the inundation of 1866 

 — an inundation caused by diluvial rains, not by melted snow — 

 it was everywhere remarked that "grounds covered with wood 

 sustained no damage even on the steepest slopes, while in cleared 

 and cultivated fields the very soil was washed away and the rocks 

 laid bare by the pouring rain." * 



The Italian journals of the day state that the province of Bres- 

 cia and a part of that of Bergamo, which have heretofore been 

 exposed to enormous injury, after every heavy rain, from floods 

 of the four principal streams which traverse them, in a great de- 

 gree escaped damage in the terrible inundation of October, 1872, 

 and their immunity is ascribed to the forestal improvements exe- 

 cuted by the former province, within ten or twelve years, in the 

 Yal Camonica and in the upper basins of the other rivers which 

 drain that territory. Similar facts were noticed in the extraor- 

 dinary floods of September and October, 1868, in the valley of 

 the Upper Rhine, and Coaz makes the interesting observation 

 that not even dense greensward was so efficient a protection to 

 the earth as trees, because the water soaked through the sod and 

 burst it up by hydrostatic pressure.f 



known to me has so "well illustrated this function of forest vegetation as Men- 

 gotti, though both he and Rossmassler ascribe to plants a power of absorbing 

 water from the atmosphere which they do not possess, or rather can only rarely 

 exercise. 



* See, for other like observations, an article entitled Le Reboisement et les In- 

 ondations, in the Bevue des Eaux et Forets of September, 1868. 



■)■ Die Hochwasser in 1868 im Bundnerisehen Rheingebiet, pp. 12, 68. 



Observations of Forster, cited by Cezanne from the Annales Forestikres for 

 1859, p. 358, are not less important than those adduced in the text. The field 

 of these observations was a slope of 45° divided into three sections, one luxuri- 

 antly wooded from summit to base with oak and beech, one completely cleared 

 through its whole extent, and one cleared in its upper portion, but retaining 



