350 A JOURNEY IN BRAZIL. 



its southernmost limit during our summer months. In con- 

 sequence of this, the bottom of the valley is constantly shift- 

 ing, and there is a tendency to form channels from the main 

 river to its tributaries, such as we have seen to exist be- 

 tween the Solimoens and the Rio Negro, such as Hum- 

 boldt mentions between the Hyapura and the Amazons. In- 

 deed, all these rivers are bound together by an extraordi- 

 nary network of channels, forming a succession of natural 

 highways which will always make artificial roads, to a great 

 degree, unnecessary. Whenever the country is settled, it 

 will be possible to pass from the Purus, for instance, to the 

 Madeira, from the Madeira to the Tapajoz, from the Tapajoz 

 to the Xingu, and thence to the Tocantins, without entering 

 the course of the main river. The Indians call these passes 

 'furoj literally, a bore, a passage pierced from one river 

 to another. Hereafter, when the interests of commerce 

 claim this fertile, overflowed region, these channels will be 

 of immense advantage for intercommunication." 



