ACROSS UNKNOWN SOUTH AMERICA 
that evening was but 400 metres from that of the day 
before. 
The minimum temperature of August twelfth had 
been 70° Fahrenheit, whereas during the night of August 
thirteenth it was 62° Fahrenheit. 
That little adventure had pulled the men together 
somewhat. I spoke in great praise of the courage that 
Antonio and Filippe had shown in swimming across the 
stream. 
The river was smooth for a little distance, when we 
proceeded once more with our navigation; but soon it 
became narrow — only forty to fifty metres wide — with 
strong eddies in its deep channel between rocky sides. 
Some magnificent sand beaches fifteen to twenty feet high 
were observed, particularly on the right bank, not far from 
a tributary three metres wide, which entered the main 
river on the left side. Lower down, the river described a 
sharp turn, and there we met another most dangerous 
rapid. It was entered by a passage fifty metres wide, 
after which a circular basin of rock, evidently an ancient 
crater, 100 metres in diameter, appeared; then the water 
flowed out with terrific force by a channel only thirty 
metres wide. The stream produced prodigious eddies in 
the circular basin. Waves of great height were dashed 
to and fro from one side to the other of the narrow channel, 
between high rocks on either side. The water flowed first 
in a direction east-southeast for 500 metres, then turned 
off suddenly to due east for a distance of 400 metres. 
That spot was most difficult for us to go through. 
Soon after, the river turned due north and broadened 
to a width of 120 metres for some 4,000 metres. A great 
basin was crossed, with submerged rocks, forming counter 
currents of great power and most unpleasant whirlpools. 
I observed with some concern a stupendous vortex thirty 
metres in diameter and with a deep central depression, 
the water revolving with such velocity and force that it 
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