DIMINUTION or FORESTS. 
9 
The changes which the destruction of forests, the clearing 
of plains, and the cultivation of indigo, have produced within 
half a century in the quantity of water flowing in on the 
one hand, and on the other the evaporation of the soil, and 
the dryness of the atmosphere, present causes sufficiently 
powerful to explain the progressive diminution of the lake of 
Valencia. I cannot concur in the opinion of M. Depons * 
(who visited these countries since I was there) “ that to 
set the mind at rest, and for the honour of science,” a sub- 
terranean issue must be admitted. By felling the trees 
which cover the tops and the sides of mountains, men in 
every climate prepare at once two calamities for future gene- 
rations ; want of fuel and scarcity of water. Trees, by the 
nature of their perspiration, and the radiation from their 
leaves in a sky without clouds, surround themselves with an 
atmosphere constantly cold and misty. They affect the 
copiousness of springs, not, as was long believed, by a pecu- 
liar attraction for the vapours diffused through the air, but 
because, by sheltering the soil from the direct action of the 
sun, they diminish the evaporation of water produced by 
rain. When forests are destroyed, as they are everywhere 
in America by the European planters, with imprudent pre- 
cipitancy, the springs arc, entirely dried up, or become less 
abundant. The beds of the rivers, remaining dry during 
a part of the year, are converted into torrents whenever 
great rains fall on the heights. As the sward and moss 
disappear with the brushwood from the sides of the moun- 
tains, the waters falling in ram are no longer impeded in 
their course ; and instead of slowly augmenting the level of 
the rivers by progressive filtrations, they furrow, during 
heavy snovyers, the sides of the hills, bearing down the 
loosened soil, and forming sudden and destructive inunda- 
tions. Hence it results, that the clearing of forests, the 
■want of permanent springs, and the existence of torrents, 
are three phenomena closely connected together. Countries 
In lus ‘ Voyage & la Terre Feme,’ M. Depons says, "The small 
ex ent of the surface of the lake renders impossible the supposition that 
evaporation alone, however considerable within the tropics, could remove 
as much water as the rivers furnish.” In the sequel, the author himself 
ems o abandon what he terms “ this occult case, the hypothesis of an 
aperture.” 
