93 deg. in the shade. Lat. 11 deg.
23'.9 S.; long. 57 deg. 39' W.

When we left, we saw 3,500 m. beyond our halting place, beside a great
heap of rocks on the left side of the river, a rivulet, 3 m. wide,
entering the Arinos on the left.

From that spot the river was contracted from a width of 800 m. to one of
only 120 m. Naturally the water was of great depth and the current
swift.

Two great volcanic rocks stuck out in the centre of the stream, and two
extensive heaps of volcanic rock stood on the right side of us, the rocks
being at all angles in a confused mass. Where these rocks were--a spot
which my men called the "porteira" or gateway--the river turned sharply
from 70 deg. b.m. to 290 deg. b.m. The water seemed almost stagnant there, and we
had to make a great effort to get on. It seemed as if there had been an
undercurrent pushing us back. The water was surely held up by some
obstacle, and I feared we had at last reached the extensive rapids which
I had expected for some days. Rocks were to be seen in abundance all
along, and three more sets of giant boulders were reached, one after the
other, in the centre of the river, there only 150 m. broad. Strange heaps
of broken-up boulders of immense size were to be seen on the right bank;
then farther on more great heaps in confusion on the left bank.

A tiny rivulet found its way among the rocks on the right side. The
channel was much strewn with dangerous submerged rocks. I thought I would
take the navigation into my own hands for a little while, and found a
comparatively easy channel on the left side of the river close to the
bank.

As I had expected, the rumbling noise of troubled waters was getting
louder and louder, and the whitish mist which rose above the horizon line
was an unmistakable sign that we had come to a dangerous spot. Soon
after, in fact, we arrived at a large circular basin, some 600 m. in
diameter, with rocks in the centre of it. Two clusters of magnificent
rocks, 30 ft. high, towered on the left side of the river. Then came a
long row of rocks, also gigantic, and a sandy beach which had accumulated
against them. A little farther another great mass of rocks in disorder
stood up against the now once more fierce current.

We made our way tentatively along what seemed to us the safest channel,
to 320 deg. b.m., and with trepidation shot the rapids, which were quite
fearsome. I must say for my men that by now they had acquired a certain
amount o