160 VIEWS OF NATURE. 



cal data, the Guaviare, flowing in from the west, was long 

 regarded as the true source of the Orinoco. The doubts 

 advanced since 1797 by an eminent geographer, M. Buache, 

 regarding the possibility of a connection with the Amazon, 

 have, I trust, been completely set at rest by my expedition. 

 In an uninterrupted voyage of 920 miles, I penetrated through 

 a remarkable net- work of rivers, from the Rio Negro, along 

 the Cassiquiare, into the Orinoco; across the interior of 

 the continent, from the Brazilian boundary to the coast of 

 Caracas. 



In the upper portion of this fluvial district, between 3 and 

 4 north lat., nature has exhibited, at many different points, 

 the puzzling phenomenon of the so-called black waters. The 

 Atabapo, whose banks are adorned with Carolinias and arbo- 

 rescent Melastomas, the Terni, Tuamini, and Guainia, are all 

 rivers of a brown or coffee colour, which, under the deep 

 shade of the palms, assumes a blackish, inky tint. When 

 placed in a transparent vessel, the water appears of a golden 

 yellow colour. These black streams reflect the images of the 

 southern stars with the most remarkable clearness. Where 

 the waters flow gently they afford the astronomer, who is 

 making observations with reflecting instruments, a most ex- 

 cellent artificial horizon. 



An absence of crocodiles as well as of fish greater coolness 

 less torment from stinging mosquitoes and salubrity of 

 atmosphere, characterize the region of the black rivers. They 

 probably owe their singular colour to a solution of carburetted 

 hydrogen, to the rich luxuriance of tropical vegetation, and 

 to the abundance of plants on the soil over which they flow. 

 Indeed, I have observed that on the western declivity of the 

 Chimborazo, towards the shores of the Pacific, the over- 

 flowing waters of the Rio de Guayaquil gradually assume a 

 golden yellow, approaching to a coffee colour, after they have 

 covered the meadows for several weeks. 



Near the mouths of the Guaviare and Atapabo grows one 



