8 " THE LEAVES OF THE TREE WCTS FOR TUB HEALING OF THE NATIONS." 



through subsoil almost and in many instances quite impervious to water, 

 and in such cases the moisture which would otherwise remain above the 

 subsoil and convert the surface earth into a bog, follows the roots down- 

 wards into more porus strata, or is received by subterranean canals or 

 reservoirs. When the forest is felled the roots perish and decay, the 

 orifices opened by them are soon obstructed and the water having satur- 

 ated the vegetable earth-mould stagnates and transforms it into ponds 

 and disease-germ breeding morasses. 



In M. Marchand's excellent work, entitled "Les lorrents des Alpes et le 

 Paturage" is the following passage descriptive of what is now going on 

 in the civilized world: " Unhappily, man, improvident and avaricious, 

 has frequently destroyed tLe forests that he .may thereby get possession 

 of the soil. He has substituted for them pasture grounds, often ill 

 maintained. With the ruin of the soil begins that of the people. The 

 more unhappy they are, the more selfish do they become (and the converse 

 of the proposition holds equally good) and the more they destroy, so that 

 from the time evil begins it cannot but go on increasing." 



BOUSSINGAULT. 



Boussingault speaks of the two lakes near Ubate in New Grenada, which 

 a century ago formed but one. When he visited them he found the waters 

 gradually retiring, and vegetation encroaching on the abandoned bed. 

 The enquiries which he instituted, satisfied him that the circumstances 

 were attributable to the extensive clearings which were going on all around 

 it. In the same valley he ascertained that the length of the lake Fuquene 

 had been reduced in five centuries, from ten leagues to one and a half, 

 and its breadth from three leagues to one. At the former period the 

 neighboring mountains were well wooded, but at the time of his visit they 

 had been almost entirely stripped. 



HUMBOLDT. 



That close observer, Alexander Von Humboldt, noticed the same thing 

 in regard to the Lake of Valencia which had been diminished from year 

 to year because the loss by evaporation is not made good by precipitation. 

 So rapidly had this been proceeding that some people imagined the lake 

 must have a subteranean outlet; but Humboldt clearly perceived and has 

 lucidly explained the cause: " By felling the trees which cover the tops 

 and sides of mountains he observes " men in every climate prepare at 

 oace, two calamities for future generations, 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 as in the regions of which he was 

 writing surround themselves with an atmosphere constantly cold and 

 misty. They aft'ect the copiousness of springs, not as was long believed 

 by a peculiar attraction for the vapors diffused through the air, but be- 

 cause 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 European planters, with imprudent 

 precipitancy, the springs are entirely dried up, or become less abundant. 

 The beds of the rivers remaining dry during a part of the year, are con- 

 verted into torrents wherever great rains fall on the heights. Hence, it 

 results that the clearing of forests, the want of permanent springs and the 

 existence of torrents are three phenomena closely connected together." 

 Humboldt might safely have added another and equally serious phenomena 

 namely, a foul destructive insect pest breeding atmosphere. 



