154 BOARD OF AGRICULTURE. 



emptying into it, and, on inquiry, we were told by the pilot, who 

 was familiar with that region, that it was a branch of the 

 Amazon which poured into the Rio Negro, which Rio Negro 

 is itself a tributary of the Amazon.' And higher up you have 

 tlie same phenomenon repeated in the Japura, which sends 

 branches into this network to which I have referred, but which, 

 higher up, receives its branches from the Amazon. Therefore 

 these tributaries of the river, near their junction, are so nearly 

 level with the general surface of the whole land, that while they 

 pour the bulk of their water into the main river, they receive 

 branches from the main river ; and this especially at the time 

 when the rise of the mass of the waters alternates from the 

 south to the north. 



I will now, as I have this diagram before me, just recall what 

 I said concerning the alternate rise and fall of the waters. 

 From September to December all the tributaries of the Amazon 

 which are on its southern side rise gradually. By December 

 this flood has reached the axis of the valley, and pushed to the 

 north all the water from those northern tributaries, which at 

 that time are at their lowest. In the latter part of January and 

 in February and March, all these northern streams swell and 

 rise, and press against the southern rivers, which by that time 

 have emptied the bulk of their waters into the Amazon, and so 

 the northern waters are now pressing south. And it is this 

 swinging of the great mass -of waters right and left, (this is, 

 north and south,) while it flows east, which has established all 

 this network of inter-communications which is the characteristic 

 feature of the Amazon, and in which that river differs from all 

 other rivers known. 



The first indication of this singular and striking system was 

 obtained when Humboldt visited South America, when from the 

 waters of the Oronoco he passed, without interruption, into the 

 waters of the Rio Negro. There is a stream known as the Cassi- 

 quiare, which, after flowing from the east westwards, divides 

 into two branches, one of which flows northwards and empties 

 into the Oronoco, while the other flows southwards and empties 

 into the Rio Negro. Now Humboldt ascended the Oronoco to 

 the point where it receives the north branch of the Cassiquiare, 

 and, ascending that north branch, passed into the south branch, 

 and thus reached the Rio Negro without interruption. Now 



