212 IMPORTAlSrCE OF SNOW. 



more or less impermeable or a satm-ated stratum, and then, by 

 unseen conduits, slowly finds its way to tlie channels of springs, 

 or oozes out of the ground in drops which unite in rills, and so 

 all is conveyed to the larger streams, and by them finally to the 

 sea. The water, in percolating through the vegetable and min- 

 eral layers, acquires their temperature, and is chemically affected 

 by their action, but it carries very Httle matter in mechanical 

 suspension. 



The process I have described is a slow one, and the supply of 

 moisture derived from the snow, augmented by the rains of the 

 following seasons, keeps the forest-ground, where the surface is 

 level or but moderately inclined, in a state of approximate satura- 

 tion throughout almost the whole year.* 



It may be proper to observe here that in Italy, and in many 

 parts of Spain and France, the Alps, the Apennines, and the 

 Pyrenees, not to speak of less important mountains, perform the 

 functions which provident nature has in other regions assigned to 

 the forest, that is, they act as reservoirs wherein is accumulated 

 in winter a supply of moisture to nourish the parched plains dur- 

 ing the droughts of summer. Hence, however enormous may be 

 the evils which have accrued to the above-mentioned countries 

 from the destruction of the woods, the absolute desolation which 

 would otherwise have smitten them through the folly of man, has 

 been partially prevented by those natural dispositions, by means 

 of which there are stored up in the glaciers, in the snow-fields, 

 and in the basins of mountains and valleys, vast deposits of con- 

 densed moisture which are afterwards distributed, in a liquid 



* The statements I have made, here and elsewhere, respecting the humidity 

 of the soil in natural forests, have been, I understand, denied by Mr. T. Mee- 

 han, a distinguished American naturalist, in a paper which I have not seen. 

 He is quoted as maintaining, among other highly questionable propositions, 

 that no ground is "so dry in its subsoil as that which sustains a forest on its 

 surface." In open, artificially planted woods, with a smooth and regular sur- 

 face, and especially in forests where the fallen leaves and branches are annu- 

 ally burnt or carried off, both the superficial and the subjacent strata may, 

 under certain circumstances, become dry, but this rarely, if ever, happens in a 

 wood of spontaneous growth, undeprived of the protection afforded by its own 

 droppings, and of the natural accidents of surface which tend to the retention 

 of water. See, on this point, a very able article by Mr. Henry Stewart, in the 

 Kew York Tribune of November 25, 1873. 



