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chettoes was so thick near the ground, that I 

 could not succeed in levelling the artificial hori- 

 zon ; consequently, I lost the opportunity of 

 observing the stars. Had I been furnished with 

 an horizon of mercury on this voyage, it would 

 have been of great use to me. 



April the 18th. We set out at three in the 

 morning, in order to be more sure of arriving 

 before the close of day at the cataract known 

 by the name of the Raudal des Guahibos. We 

 stopped at the mouth of the Rio Tomo. The 

 Indians went on shore, to prepare their food, 

 and take some repose. When we reached the 

 foot of the raudal, it was near five in the after- 

 noon. It was extremely difficult to go up the 

 current and struggle against a mass of water, 

 which is precipitated from a bank of gneiss seve- 

 ral feet high. An Indian threw himself into the 

 water, to reach by swimming the rock, that 

 divides the cataract into two parts. A rope 

 was fastened to the point of this rock, and when 

 the canoe was hauled near enough, our instru- 

 ments, our dry plants, and the little provision 

 we had collected at Atures, were landed in the 

 raudal itself. We remarked with surprise, that 

 the natural dam, over which the river is precis 

 pitated, furnishes a dry space of considerable 

 extent ; where we stopped to see the boat go 

 up. 



The rock of gneiss exhibits circular holes, the 



