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the Upper Oroonoko. In the Carte generate cte 

 Guyane, published in 1798, the Cassiquiare, and 

 that part of the Upper Oroonoko situate to the 

 east of Esmeralda, are marked as a tributary 

 river of the Rio Negro, and as not being con- 

 nected with the Oroonoko. A chain of moun- 

 tains is made to pass across the plain, that 

 forms the isthmus between the Tuamini and the 

 Pimichin ; this chain is supposed to run toward 

 the north-east, and form a point of partition 

 between the waters of the Oroonoko and those 

 of the Rio Negro and the Cassiquiare, twenty 

 leagues west of Esmeralda. In a note added to 

 this map, it is said, that, " the long-supposed 

 communication between the Oroonoko and the 

 Amazon is a monstrous error in geography, 

 which the map of La Cruz has multiplied, with- 

 out foundation ; and that, to rectify the ideas 

 entertained on this point, it is necessary to 

 observe the direction of the great chain, which 

 separates the waters." 



I was fortunate enough to reconnoitre this 

 chain on the spot. I passed with my boat in 

 the night of the 24th of May, along that part of 

 the Oroonoko, where Mr. Buache supposes the 

 bed of the river to be cut by a Cordillera. If 

 there had been a line of summits, (a point of 

 partition) on that spot, I should have gone up 

 a river for the first twenty leagues to the west 

 of the Esmeralda, instead of descending, as I 



vol. v. 2 k 



