1849.] 



exercised hy Trees on Climate. 



427 



were found dry for more than six months of the year. At the last 

 epoch to which I have alluded, the streams being no longer so 

 diverted, flowed without interruption. Thus, then, during the pro- 

 gress and continuance of agricultural industry in the valley of 

 Aragua, when the process of clearing was pushed farther and farther, 

 and when cultivation in every shape was advancing, the level of the 

 water gradually subsided. More lately, on the contrary, during a 

 period of misfortune, and, we would ftiin hope, but temporary, when 

 the clearing was no longer continued and the cultivated lands have 

 fallen back into their wild state, the waters having ceased to fall, 

 are now very speedily assuming a decided rising movement. 



I shall now direct my remarks to another quarter, without how- 

 ever leaving America, in which we find a climate analogous to that 

 of Europe, and where we traverse immense districts producing the 

 most valuable grains. I shall direct attention to the higher lands of 

 New Grenada, and to those elevated valleys from 6,000 to 9,000 feet 

 above the level of the sea which enjoy, throughout the year, a tem- 

 perature of from 58*^ to 62° Fahr. Lakes are frequent among the 

 Cordilleras ; I might easily dwell upon many of these, but shall bring 

 under review only those which have been the subject of previous 

 observations. 



The village of Ubata is placed in the vicinity of two lakes. It is 

 an important fact that sixty years ago, those two sheets of water 

 formed one only. The older inhabitants have observed the waters 

 gradually diminish, and their shores extend themselves year after 

 year. Fields of corn of the greatest fertility at the present time cover 

 districts which thirty years ago were completely covered with water. 

 The falling of the mean level of this lake will the more readily be 

 credited by the consideration that an occasional fall of three or four 

 inches lays bear a great extent of surface. If we inquire in the 

 neighbourhood of Ubata of any of the old men, who in their younger 

 days were devoted to the chase, or if we examine the records of any 

 of the different parishes, no doubt will remain that numerous forests 

 have been felled. The clearing still goes on : and it is equally cer- 

 tain that the retreat of the water has not ceased, though it does not 

 advance so rapidly as it was wont to do. 



The lake of Fuquena in the same valley and to the east of Ubata 

 deserves marked attention. By barometrical measurements, made 



VOL. XV. JTO. XSXYI, G 1 



