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. There are also to be taken into account the stoppages occasioned by the bends in the river, the numerous islands which had to be rounded, the shoals which had to be avoided, and the hours of halting, which were necessarily lost when the night was too dark to advance securely, so that we cannot allow more than twenty-five k
