THE FUNCTION OF THE FOREST 675 



A second function of great moment streams ; prevent extremes of dampness 

 is the regulation of the temperature, and drought and keep the precipitation 

 They truly measure out rain and sun- from Mowing off too rapidly. The rain- 

 shine. They absorb the vast quantities drops falling on the leaves and trickling 

 of water that men do not use. Close down the stems reach the ground with 

 observation has shown that a leaf of much less force. There, if not to a 

 ordinary size can absorb about fifteen large extent immediately absorbed, the 

 to forty-five grains of water in a day, water is at least retarded in its flow, so 

 and a leaf of larger dimensions some- that it gradually sinks into the real 

 times even as much as a small pailfull. ground below (which is always kept 

 But where evaporation proceeds tin- open by the mass of dead leaves lying- 

 hampered, warmth is held bound and on it), whereas on a bare, sloping plane 

 cold produced. Forests, therefore, tern- it flows off in large measure. The snows, 

 per the heat, hinder radiation and so too, melt more slowly under the in- 

 lessen also the amount of lost heat, fluence of the milder conditions foster- 

 This warmth, necessary for the process ed by the protection of the trees, and 

 of evaporation, can only be taken from penetrate into the ground, which for the 

 the atmosphere, the temperature of same reason is seldom frozen hard be- 

 which is thereby lessened. A wooded neath its blanket of grass and fallen 

 region, then, slowly warms and cools by foliage. These waters are slowly and 

 turns, and produces a corresponding constantly drained off to feed the 

 change in the temperature of the neigh- springs, wells and rivulets. Men have 

 borhood. The moisture acts as a cool- often found the ordinary sources of 

 ing influence in evaporating, while the their water-supply exhausted, because 

 atmosphere and clouds hold their heat the mountain and hill-tops had been 

 because radiation is in a large measure cleared of their woods, and that, too, 

 checked. The numberless vapor-laden at times when the water was most need- 

 leaves facilitate the formation of mist ed in the houses and on the farms, 

 and dew. Their warm dampness as- This also explains why after a heavy 

 sists in cloud building; while the whole rainfall the water may be so murky as 

 wide area of vapor, inhaling and exhal- to be entirely unfit for use. There are 

 ing foliage at the top of the trees, holds no cheaper, better and more sanitary 

 them and the mists, to the decided ad- water reservoirs than the forests. Arti- 

 vantage of the neighborhood. Thus, ficial water reservoirs in the shape of 

 this process of cooling and evaporating, ponds or produced by dams can never 

 itself productive of rain and mist, in equal them because their capacities are 

 turn benefits the forests themselves and limited, their contents may be diminish- 

 the neighboring fields and meadows. All ed by evaporation and may become 

 the phenomena of the atmosphere work poorer in quality as the drouth pro- 

 together to the great end of making ceeds. The water that is drawn from 

 possible the existence and well-being of the bare floor of such a reservoir into 

 earthly life. the pipes for daily consumption is often 



The forests are, however, even in contaminated, and entirely lacking in 

 another sense essential to the natural refreshing carbonates. Ponds and res- 

 organization of forces, as water-gather- ervoirs must, indeed, be constructed 

 ers and distributors and spring-builders where the forest lands have Ixvn 

 and feeders. We have seen how life cleared, but they are at best only make- 

 on earth is dependent on air and water, shifts. 



Now, the forests absorb much moisture That many regions may be made un- 

 from the air and again surrender it productive and even uninhabitable be- 

 freely. They retain a great part of the cause of the destruction of their wood- 

 moisture collected in their locality, and lands is evident from what has been 

 so act as reservoirs for all atmospheric said. Persia, once the most productive 

 condensations. In this way they become and prosperous of lands, is now nearly 

 the sources of numerous springs and all a desert ; it is only with grave dan- 



