M. BECQUEREL, ON THE CLIMATIC EFFECTS OF FORESTS. 329 



Choiseul Gouffier was unable to find now in the Troad the Scamander 

 Eiver, which was still navigable in the days of Pliny. Its bed is now 

 entirely dry; and the cedars that once covered Mount Ida, where it 

 takes its source, as did also the Simois, no longer exist. 



M. Boussingault,^ who has studied this question during his sojourn 

 in'Bolivia, took for the subject of his observations the lakes situated 

 in the plains or upon different stages of the mountains. The valley 

 of Aragua, in the province of Venezuela, is a short distance from the 

 coast, in a very favorable climate, and is very fertile. It is land-locked, 

 the streams that flow into it having no outlet into the sea, but unite in 

 forming Lake Tacarigua or Yalenciana, which, when Humboldt saw it, 

 at the beginning of this century, had been showing for thirty years a 

 gradual drying up, of which they knew not the cause. 



O video, the historian of Venezuela, in the sixteenth century, reports 

 that the city of New Valencia was founded in 1555, at half a league from 

 Lake Tacarigua. This city, when seen by Humboldt in 1800, was 2,700 

 toises distant, showing, by many proofs, the retreat of the waters. Ac- 

 cording to this celebrated traveler, the diminution of the waters should 

 be attributed to numerous clearings that had been made in the valley. 



In 1822 Boussiugault learned from the inhabitants that the waters 

 of the lake had very considerably raised, and that lands once cultivated 

 were now under water. 



We should add, that during the period of twenty- two years, the valley 

 had been the theater of a bloody contlict in the war of independence. 

 Its population was decimated, the lands remained uncultivated, and the 

 forests, which grow with astonishing rapidity within the tropics, had re- 

 occupied a lar^e part of the country. We see from this the influence that 

 forests may exert upon the waters of a country, as the lake had lost its 

 waters by clearing, and had regained them as the country was restored 

 in forests. 



M. Boussiugault cites several other examples leading to the same con- 

 clusion relative to the influence exerted by great masses of forests upon 

 the living waters of a country. We will cite two of these that are re- 

 markable. 



In 182C the metalliferous mountains of Marinato presented but a few 

 miserable cabins, inhabited by negro slaves. In 1830 this state of things 

 no longer existed. There were numerous establishments and a popula- 

 tion of 3,000 inhabitants. They had been obliged to cut much of the 

 wood. The clearings had only begun two years before, yet the effects 

 were already seen in the failing of the waters used in driving the mills. 

 Yet a rain-gauge showed to M. Boussiugault that the amount of waters 

 falliog the second year had been greater than that of the first. 



The second example is taken upon the plateau of New Grenada, at an 

 elevation of 2,000 to 3,000 meters, where the temperature of the year is 

 from 14° to 16^0. Theinhabitantsof the village of Dubat^, situated near 

 the two lakes that were united some sixty years before, had noticed a 

 gradual wasting of the waters, so that lands which were under water 

 thirty years before were now cultivated, and an inquiry as to the cause 

 led tc the conclusion that the decrease had been caused by the numer- 

 ous clearings of the forests that had taken place. Some lakes, such as 

 that of Tota, a short distance from Tuguen6, in localities not cleared, 

 had suffered no diminution in their waters. 



Mr. Desbassyres de Richemont has likewise shown, that there exists 

 on Ascension Island a fine spring of water, which was lost by clearing 

 and restored when the mountain was reforested. 



^Annales de Chimie et de Physique, xiv, p. 113. 



