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seldom been ascertained by direct observation, because there are few meteorological sta- 

 tions in or near the forest. According to Thompson, the proportion of water which falls 

 in snow in the Northern States does not exceed one fifth of the total precipitation, but 

 the moisture derived from it is doubtless considerably increased by the atmospheric vapour 

 absorbed by it, or condensed and frozen on its surface. I think I can say from experi- 

 ence — and I am confirmed in this opinion by the testimony of competent observers whose 

 attention has been directed specially to the point — that though much snow is intercepted 

 by the trees, and the quantity on the ground in the woods is consequently less than in 

 the open land in the first part of the winter, yet most of what reaches the ground at that 

 season remains under the protection of the wood until melted, and as it occasionally re- 

 ceives new supplies, the depth of the snow in the forest in the latter half of the winter is 

 considerably greater than in the cleared fields. Careful measurements in a snowy region 

 in New England, in the month of February, gave a mean of thirty-eight inches in the 

 open ground and forty-four inches in the woods. 



"The general effect of the forest in cold climates is to assimilate, the winter state 

 of the ground to that of wooded regions under softer skies ; and it is a circumstance 

 well worth noting, that in Southern Europe, where nature has denied to the earth a 

 warm winter garment of flocculent snow, she has, by one of those compensations in 

 which her empire is so rich, clothed the hill-sides with umbrella and other pines, ilexes, 

 cork-oaks, bays, and other trees of persistent foliage, whose evergreen leaves afford to 

 the soil a protection analogous to that which it derives from snow in more northern 

 climates. 



" The water imbibed by the soil in winter sinks until it meets a more or less imper- 

 meable or saturated stratum, and then, by unseen conduits, slowly finds its way to the 

 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 mineral layers, acquires their temperature, and is chemically 

 affected by their action, but it carries very little 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 saturation 

 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 Appenines, and the Pyrenees, not to speak of less important moun- 

 tains, 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 mois- 

 ture to nourish the parched plains during 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 condensed moisture which are afterwards dis- 

 tributed in a liquid form during the season in which the atmosphere furnishes a slender 

 supply of the beneficent fluid so indispensable to vegetable and animal life." 



An elegant French writer upon forest economy, Jules Clavfe, in a work entitled 

 " fetudes sur I'Economie Forestifere," thus clearly describes the processes of nature by 

 which forests maintain and equalize the flow of waters : — 



" Bains. — The first phenomenon that offers for our inquiry, in the study" of the regu- 

 lation of the waters, is rain. It is this that gives rise to springs and rivers, and that in 

 certain conditions of continuance occasions inundations. 



" Rain is caused by the precipitation of the vapour held by the atmosphere, and this 

 precipitation is commonly caused by cold and humid winds. When these winds come to 

 us (in France) from the ocean or the Mediterranean, and pass over a place where the 

 temperature is too low to hold these vapours in suspension, they condense and fall as 



