They have only an ax and a saw, and they work on woods so hard that the edge of their tools gets absolutely jagged; yet they square up trunks, shape beams out of enormous stems, and get out of them joists and planking without the aid of any machinery whatever, and, endowed with prodigious natural ability, do all these things easily with their skilled and patient hands.
The trees had not been launched into the Amazon to begin with; Joam Garral was accustomed to proceed in a different way.

The whole mass of trunks was symmetrically arranged on a flat part of the bank, which he had already leveled up at the junction of the Nanay with the great river.
There it was that the jangada was to be built; thence it was that the Amazon was to float it when the time came for it to start for its destination.
And here an explanatory note is necessary in regard to the geography of this immense body of water, and more especially as relating to a singular phenomenon which the riverside inhabitants describe from personal observation.
The two rivers which are, perhaps, more extensive than the great artery of Brazil, the Nile and the Missouri-Mississippi, flow one from south to north across the African continent, the other from north to south through North America.

They cross districts of many different latitudes, and consequently of many different climates.
The Amazon, on the contrary, is entirely comprised--at least it is from the point where it turns to the east, on the frontiers of Ecuador and Peru--between the second and fourth parallels of south latitude.

Hence this immense river system is under the same climatic conditions during the whole of its course.
In these parts there are two distinct seasons during which rain falls.
In the north of Brazil the rainy season is in September; in the south it occurs in March.

Consequently the right-hand tributaries and the left-hand tributaries bring down their floods at half-yearly intervals, and hence the level of the Amazon, after reaching its maximum in June, gradually falls until October.
This Joam Garral knew by experience, and he intended to profit by the phenomenon to launch the jangada, after having built it in comfort on the river bank.