ACROSS UNKNOWN SOUTH AMERICA 
camped on the river Piraputangas, a tributary on the left 
side of the Cuyaba Grande River — the Cuyaba Grande 
being in its turn a tributary on the right of the Cuyaba 
River. 
The Cuyaba River described almost an arc of a circle, 
in fact, quite a semicircle, its birth taking place in the 
Serra Azul. Where we crossed it we were only a short 
distance to the west from its point of origin. 
Where we had made our camp we were in a large 
grassy plain about six kilometres long and nearly two 
kilometres wide. The rainy season was fast approaching. 
We came in for a regular downpour during the night, 
accompanied by high wind, which knocked down all our 
tents, as the pegs would not hold in the soft, moist ground. 
We had a busy time endeavouring to protect the baggage. 
We all were absolutely soaked. The minimum tempera¬ 
ture was 52° Fahrenheit. In the morning, after the wind 
had abated and the rain had stopped, we were enveloped 
in thick fog. 
We had descended to so low an altitude as 750 feet 
above the sea level on the north side of the Serra Azul, 
the lowest elevation we had been at for some considerable 
time. We had descended altogether from the highest part 
of the great Central Brazilian plateau. From that point 
all the waters would be flowing to the northeast or north. 
We were, in fact, within a stone’s throw, to be more 
accurate, within the radius of a few kilometres, of the 
birthplace of the Rio Novo, the head-waters of the River 
Arinos, of the Rio Verde (Green River), and of the 
several sources of the Rio S. Manoel or das Tres Barras, 
or Paranatinga; and not distant from the sources of the 
great Xingu River. 
The Serra Azul, extending from west to east, was 
interesting geographically, not only because it marked the 
northern terminus of the highest terrace of the great 
central plateau, but also because from it or near it rose 
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