1ABLT GEOGRAPHICAL DOUBTS. 425 



hundred and fifty miles* before reaching Angostura, but we 

 should go with the stream ; and this consideration lessened 

 our discouragement. In descending great rivers, the rowers 

 take the middle of the current, where there are few mosqui- 

 tos; but in ascending, they are obliged, in order to avail them- 

 selves of the dead waters and counter-currents, to sail near 

 the shore, where the proximity of the forests, and the 

 remains of organic substances accumulated on the beach, 

 harbour the tipulary insects. The point of the celebrated 

 bifurcation of the Orinoco has a very imposing aspect. Lofty 

 granitic mountains rise on the northern bank ; and amidst 

 them are discovered at a distance the Maraguaca and the 

 Puida. There are no mountains on the left bank of the 

 Orinoco, west or east of the bifurcation, till opposite the 

 mouth of the Tamatama. On that spot stands the rock 

 Guaraco, which is said to throw out flames from time to 

 time in the rainy season. When the Orinoco is no longer 

 bounded by mountains towards the south, and when it 

 reaches the opening of a valley, or rather a depression of the 

 ground, which terminates at the Rio Negro, it divides itself 

 into two branches. The principal branch (the Eio Paragua 

 of the Indians) continues its course west-north-west, turning 

 round the group of the mountains of Parime; the other branch 

 forming the communication with the Amazon runs into 

 plains, the general slope of which is southward, but of which 

 the partial planes incline, in the Cassiquiare, to south-west, 

 and in the basin of the Eio Negro, south-east. A pheno- 

 menon so strange in appearance, which I verified on the 

 spot, merits particular attention; the more especially as it 

 may throw some light on analogous facts, which are supposed 

 to have been observed in the interior of Africa. 



The existence of a communication of the Orinoco with the 

 Amazon by the Eio Negro, and a bifurcation of the Caqueta, 

 was believed by Sanson, and rejected by Father Fritz and by 

 Blaeuw : it was marked in the first maps of De 1'Isle, but 

 abandoned by that celebrated geographer towards the end of 

 his days. Those who had mistaken the mode of this com- 

 munication hastened to deny the communication itself. It 

 is in fact well worthy of remark that, at the time when the 



* Of nine hundred and fifty toiges each, or two hundred and fiffrj 

 lautica] leagues. 



