I was swept down by the mighty, though narrow current, and was beginning to feel sure that I was being carried into some underground rapids, when I was suddenly dumped into a deep pool, where the course of the river was running smooth and placidly along almost at right angles with the rapids above.

At this abrupt turn, evidences of former floods were plain.

Immense rocks were cut and carved in spiral columns as skillfully as any sculptor could have chiseled them.

Great flocks of wild black ducks peculiar to the Tagus, were continually rising at my approach.
"At ten o'clock that night, hearing the heavy roar of rapids below and the river becoming wilder, I decided to stop until daylight.

I crept cautiously in shore until I found an opening and there landed.