Influence of trees upon Climate.
--Joachim Frederic Sahouw, Professor of Botany at Copenhagen, speaks as follows of the influence of forests upon the atmosphere:‘"We find the most evident signs of it in the torrid zone. The forests increase the rain and moisture, and produce springs and running streams. Tracts destitute of woods become very strongly heated, the air above them ascends perpendicularly, and thus prevents the clouds from sinking, and the constant winds (trade winds or monsoons,) where they can blow uninterruptedly over large surfaces, do not allow the transition of vapors into the form of drops. In the forests, on the contrary, the clothed soil does not become so heated, and, besides the evaporation from the trees favors cooling; therefore, when the currents of air loaded with vapors reach, the forests, they meet with that which condenses them and change into rain. Since, moreover, evaporation of the earth goes on more slowly beneath the trees, and since these also evaporate very copiously in a hot climate, the atmosphere in those forests has a high degree of humidity, this great humidity at the same time producing many springs and streams."’
