STATEMENT BY M. LEMOINE. 221 



have observed, in connection with this, numerous muddy floods in 

 ravines which, spreading themselves out in the middle of a forest, 

 come out thence very limpid, depositing in it their slime, and leaving 

 in it also almost the whole of the water. 



" The great forest of the Ofen, in the Orisons has supplied me 

 me with many instances of this. The soil, composed of the dolomite 

 limestone of the triassic period, is somewhat unstable ; in the middle, 

 of the pasture lands which surmount the forest there are formed every 

 year numerous torrents, which to an enormous extent carry off the 

 small pebbles, which are characteristic of the dolomite. All these 

 torrents arriving in the forest, then expand and diffuse themselves, 

 and very rarely do they penetrate to the bottom of the valleys. In 

 the upper portion of the Munster-Thal, I have seen on the right-hand 

 side an enormous ravine, the muddy torrents of which are arrested by 

 the forest. And the waters of the Munster, so well enclosed at this 

 point, are a proof of the beneficial action of the forests. In fine, from 

 the moment that the forests begin to retain the mud they retain also 

 temporarily the greater portion of the water in which this was sus- 

 pended, which are arrested by the enormous absorbent powers they 

 possess." 



At the meeting of the Brititsh Association held at Brighton in 

 1876, M. G. Lemoine, Ingenieur des Fonts et Chaussees, read a paper 

 " Sur les Forets dans lew Rapports avec l^ Hydrologie." In which he 

 stated that in the basin of the Seine it had been established that, com- 

 pared with soil covered with grass, or even with other permanent culti- 

 vation forests had no special influence on watercourses. The only 

 absolutely certain action of forests was their influence in protecting 

 the soil and preventing it from being carried away ; but from this 

 single fact it followed that in mountainous countries they would 

 retard the flow of torrential water. In the Department of the Hautes 

 Alpes the presence of forest vegetation prevented the formation of 

 torrents ; re-planting woods led to the drying up of torrents already 

 formed ; but in most cases turfing, alone, was sufficient to produce 

 the same effect. 



M. Cezanne, in writing of what he calls the Mecanisme de Vlnonda- 

 tion, remarks that the rain as soon as it has fallen becomes divided 

 into three portions, the first of which, taken up again by evaporation 

 returns into the atmosphere to be formed into new showers • the 

 second, after infiltration into the soil, appears again at a lower level 

 in the form of springs, when it loses not itself in the deeper 



