1849.] 



exercised hy Trees 07i Climate. 



429 



though it may be an unknown cause, and so must be ranked amongst 

 the many phenomena whose existence is ascertained, though any 

 thing like satisfactory explications is beyond our power. 



It is true I cannot adduce here, as I did in the former case of 

 Lake Valencia, a returning increase of the water on the suspension 

 of the cultivation, and the renewed appearance of the woods. I 

 may, however, procure some support for the opinion I am propound- 

 ing from the extreme slowness of the present desiccation of the val- 

 ley of Fuquena, since there have been no more forests to cut down. 

 The cultivators of the soil perceiving that there is no longer the 

 same retiring of the waters as formerly and a corresponding appear- 

 ance of land, have been thinking of some more direct method 

 than the clearing by which they might attain the same end. It was 

 with this object that some speculative individuals thought of a plan 

 by which they might drain otF the whole water by cutting a deep 

 water course. But, instead of dwelling on such speculative points 

 as these I shall here adduce a direct proof ; and I believe it may be 

 found in continued attention to the same class of phenomena we 

 have been dwelling on ; I proceed, therefore, to demonstrate, that 

 those lakes which are so circumstanced that no clearing has ever 

 taken place in their environs, are not subjected to any alteration of 

 their level. 



I begin with lake Tota, because it is not far distant from Fuque- 

 na ; also because these two are in very similar circumstances in a 

 geological point of view ; and, finally, because it is the most curious 

 lake that is to be met with throughout the whole of New Grenada. 



The lake Tota is situated at a great height in the Cordillera of 

 Sogamoso; its elevation is above 12,000 feet. At this height ve- 

 getation almost entirely disappears. In the year 1652 the road 

 skirted, as it still does, the margin of the lake, and the Seiches, which 

 occurred then as frequently as they do now, often made the journey 

 sufficiently dangerous as it is confined between the lake and a wall 

 of elevated rocks. The waters lave the said rocks, and their level 

 has undergone no more change than the sterile and desert country 

 which surrounds them. 



It rnay here perhaps be objected that I ought not to have intro- 

 duced as an element in this discussion, the description of a lake 

 which is situated on the extreme limit of vegetable existence, In 



