more rapids, with treacherous
submerged rocks. Yet another basin, 150 m. wide, was crossed, with large
blocks of black rock showing through on the left bank. More rapids were
met--quite easy to negotiate. The sky was half covered with feathery
radiations from the south.

To the north another hill, 120 ft. high, eroded by water, stood on the
left bank of the stream, where red volcanic rock was also visible in a
stratum 15 ft. thick, covered by a thick layer of yellow earth. Strong
rapids came next. We had had so much luck in the descent of the
rapids--which, bad as they were, really were so far quite unimportant as
compared to what we were to find later--that my men began to be quite
adventurous. Saving trifling mishaps, we were getting on well. The
tributaries of the Arinos we had seen so far that day were small
streamlets 1 m. wide on the right; another, 2 m. wide--a limpid
stream--coming from the south-west on the left. Several springs of clear
water filtered through the left bank. In the centre of the river was an
extensive bank of gravel held up by blocks of volcanic rock.

[Illustration: Preparing the Canoe to descend a Rapid.]

[Illustration: A Cataract on the Arinos River.]

In a basin 150 m. wide rose a pretty island. Rapids were found in the
channels, of which the western was wider and more free from obstacles.
For one entire kilometre there were strong eddies and rapids in
succession; then came 3,500 m. of fairly easy travelling. The river for
23,500 m. had been flowing almost in a straight line due north, with
slight variations of a few degrees to the north-east and once to the
north-west. Plenty of _tucum_ or _tucuma_ palms adorned the right
bank; whereas on the left bank was fairly open country.

Again, after some more rapids, the river was squeezed into a neck only 25
m. wide, gradually widening to some 150 m., where whirlpools and eddies
of considerable magnitude were formed. On several occasions the canoe was
caught in them and swerved right round, describing one or more circles
upon herself. Two islets were passed, then a tributary 10 m. wide coming
from the east on the right side of us.

A great number of submerged rocks close to the surface formed a ridge 200
m. in length all along the centre of the stream. In a wonderful stretch
4,000 m. long in a perfectly straight line north, the river was from 50
to 100 m. wide. A small tributary rivulet entered it on the west. At the
end of that long stret