1849.] 



exercised ly Trees on Climate. 



42§ 



tional evidence of a great change. The rising grounds uhich are 

 somewhat elevated above the plain maintain to the present day 

 the name of islands, which at a former period, was most accurate- 

 ly assigned to them, seeing they Avere surrounded with water. The 

 space which has been exposed by the retreat of the waters has 

 been transferred into most fertile fields for the cultivation of cot- 

 ton, sugar cane and the banana tree. Those buildings which were 

 reared in the immediate vicinity of the water are seen to be more 

 and more forsaken by it. New islands made their appearance in 

 the year 1796. An important military post in the shape of a for- 

 tress which was built in 1740, in the island of Cabrera, is now 

 situated on a peninsula. Lastly, in two islands of granite, those 

 namely of Cura and of Cabo-Blanco, M. de Humboldt discovered 

 among the bramble -bushes, several yards above the level of the 

 water, deposits of fine sand containing many helecites. Facts which 

 are so speaking as these, and withal so well ascertained, could 

 scarcely fail of exciting the ingenuity of the learned on the spot, 

 in the way of supplying explanations of the remarkable change, 

 and they all agreed thus far, that some subterranean conduit 

 had been opened up which allowed the waters to flow freely to the 

 ocean. M. de Humboldt when on the spot paid all due regard 

 to this supposition and after an accurate examination, of the lo- 

 calities, came very decidedly to the conclusion, that the cause of 

 the diminution of the waters of the lake of Tacarigua was nothing 

 more than the extensive clearing away of the woods over the 

 whole valley, during the course of the former half century. * In 

 laying low the trees,' he observes, ' which covered the tops and 

 flanks of the mountains mankind in all climates, are at one and 

 the same time entailing two great calamities upon succeeding 

 generations, they are producing a scarcity both of wood and 

 water.' 



Since the time of Oviedo, who like all the older chronologists, is 

 perfectly silent concerning any subsidence of the water of the lake, 

 the cultivation of indigo, sugar, cotton, and cocoa, had been car- 

 ried to a great extent. In the year 1800 the valley of Aragua 

 maintained a population as dense as that of any of the most popu- 

 lous portions of France. The smiling prosperity which existed in 

 the numerous vilhges which teemed with its industrious popula- 



