326 Through the Brazilian Wilderness 



It was astonishing before, when we were on a river of 

 about the size of the upper Rhine or Elbe, to realize that 

 no geographer had any idea of its existence. But, after 

 all, no civilized man of any grade had ever been on it. 

 Here, however, was a river with people dwelling along 

 the banks, some of whom had lived in the neighborhood 

 for eight or ten years ; and yet on no standard map was 

 there a hint of the river's existence. We were putting on 

 the map a river, running through between five and six 

 degrees of latitude — of between seven and eight if, as 

 should properly be done, the lower Aripuanan is included 

 as part of it — of which no geographer, in any map 

 published in Europe, or the United States, or Brazil had 

 even admitted the possibility of the existence; for the 

 place actually occupied by it was filled, on the maps, by 

 other — imaginary — streams, or by mountain ranges. 

 Before we started, the Amazonas Boundary Commis- 

 sion had come up the lower Aripuanan and then the 

 eastern branch, or upper Aripuanan, to 8° 48', follow- 

 ing the course which for a couple of decades had 

 been followed by the rubber-men, but not going as 

 high. An employee, either of this commission or of 

 one of the big rubber-men, had been up the Castanho, 

 which is easy of ascent in its lower course, to 

 about the same latitude, not going nearly as high as 

 the rubber-men had gone; this we found out while we 

 ourselves were descending the lower Castanho. The 

 lower main stream, and the lower portion of its main 

 affluent, the Castanho, had been commercial highways for 

 rubber-men and settlers for nearly two decades, and, as 

 we speedily found, were as easy to traverse as the upper 



