RAPIDS AND TnUNDER-STOUM. 203 



mals were larger, the rivers wider and deeper. There CHAKXVII 

 stop the monuments of nature which we can consult. ~: — 

 We are ignorant if the human race, whicli at the time iaccs. 

 of the discovery of America scarcely presented a few 

 feeble tribes to the east of the Cordilleras, had yet 

 descended into the plains, or if the ancient tradition of 

 the Great Waters, which we find among all the races of 

 the Orinoco, Erevato, and Caura, belongs to other cli- 

 mates, whence it had been transferred to this part of the 

 new continent." 



On the 11th they left Carichana at two in the after- piedradel 

 noon, and found the river more and more encumbered '^'gre. 

 by blocks of granite. At the large rock known by the 

 name of Piedra del Tigre, the depth is so great that no 

 bottom can be found with a line of 140 feet. Towards 

 evening they encountered a thunder-storm, which for a 

 time drove away the mosquitoes il'Mt had tormented 

 them during the day. At the cataract of Cariven the cataract of 

 current was so rapid that they had great difficulty in Curiven. 

 landing ; but at length two Saliva Indians swam to the 

 shore, and drew the canoe to the side with a rope. The 

 thunder continued a part of the night, and the river in- 

 creased considerably. The granitic rock on which they 

 slept is one of those from Avhich travellers on the 

 Orinoco have heard subterranean sounds, resembling 

 those of an organ, emitted about sunrise. Humboldt 

 supposes that these must be produced by the passage of 

 rarified air through the fissures, and seems to think, 

 that the impulse of the fluid against the elastic scales of 

 mica which intercept the crevices may contribute to 

 modify their expression.* 



* Many examples of mysterious sounds produced under similar 

 circumstances are on record. In the autumn of 1828, a recent tra- 

 veller crossinjj;' the Pyrenees, when in a wild pass with the jNIala- 

 detta mountain opposite, heard " a dull, low, moaning, ^Eolian sound, 

 which alone broke upon the deathly silence, evidently proceeding 

 from the body of this mighty mass." The air was perfiectly calm, 

 and clear to an extraordinary defjree ; no waterfall could be seen 

 even with the aid of a telescope, and no cause could be assigned for 

 the phenomenon, unless the suu's rays, " at that moment impinging 



