202 DIMINUTION OF THE WATER OF RIVERS AND STREAMS. 



It must be generally acknowledged that forests, on account of their 

 peculiar vegetation of lichens, mosses, &c., are preeminently qualified 

 to absorb the precipitations, accumulate them, and give them up by 

 degrees. 



In this connection are the observations which have already been men- 

 tioned in regard to the water which penetrates the soil very slowly to a 

 certain depth ; on the one hand, upon the receptive power of different 

 kinds of soils, upon the influence of different plants with which the soil 

 is covered ; on the other hand, upon the distribution in the soil of this 

 penetrating moisture, as indicated l)y the yearly registers. It appears 

 from the latter that the influence of the woods is greater in warm years. 



According to Ebernuiyer, the percentage of precipitation in summer 

 was, at the depth of — 



Older observations were undertaken by Maurice in Ghent, Gasparin 

 in Orange, and some more recent, on a larger scale, were instituted by 

 E. Kisler at Caleve, near ISTyon, (canton Wallis.) He sowed for the 

 experiment a field containing 12,300 square meters with grain, clover, 

 &c., determined the drainage at 0.35 meter depih, and compared the 

 humidity of this soil with that of others cultivated under different cir- 

 cumstances. ( Aunuaire Met^orologique de I'Observatoire de Paris, pour 

 1873, page 277.) 



In reference to the ])ortion of the precipitation which does not pene- 

 trate the soil but flows off the surface, and to which the rising of the 

 water is esi>ecially attributed, there is no difference of oj)inion in regard 

 to the influence of the w'oods. All admit that with the leveling of the 

 latter, the supply of the water-courses flows in more rapidly, and that 

 in mountainous regions the water drains off" so fast from unwooded 

 steep declivities that the streams are converted into rushing torrents. 



To the cutting down of the woods and the consequent removal of the 

 check they offered, through their interlaced roots, their mosses, lichens, 

 &c., to the downfall of the rain, must be attributed the more frequent and 

 destructive floods and inundations which are always to be dreaded. 



The fact of the diminution of water in streams, which diminution is 

 connected with the cojjiousness of the springs which supply them, being 

 admitted, the commission find the causes of this phenomenon : 1st. In the 

 continued cutting down of the woods, whose salutary influence in the 

 raising of the hygrometer, the amelioration of extreme temperature, the 



