A pleasant _"pampero"_ tempered the ardor of the sun--one of those winds which in June or July come from off the Cordilleras, many hundred leagues away, after having swept across the huge plain of the Sacramento.

Had the raft been provided with masts and sails she would have felt the effects of the breeze, and her speed would have been greater; but owing to the sinuosities of the river and its abrupt changes, which they were bound to follow, they had had to renounce such assistance.
In a flat district like that through which the Amazon flows, which is almost a boundless plain, the gradient of the river bed is scarcely perceptible.

It has been calculated that between Tabatinga on the Brazilian frontier, and the source of this huge body of water, the difference of level does not exceed a decimeter in each league.

There is no other river in the world whose inclination is so slight.
It follows from this that the average speed of the current cannot be estimated at more than two leagues in twenty-four hours, and sometimes, while the droughts are on, it is even less.

However, during the period of the floods it has been known to increase to between thirty and forty kilometers.
Happily, it was under these latter conditions that the jangada was to proceed; but, cumbrous in its movements, it could not keep up to the speed of the current which ran past it.