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. In fact, between the mean and the higher level the
height of the Amazon could vary as much as forty feet, and between the
mean and the lower level as much as thirty feet. A difference of seventy
feet like this gave the fazender all he required.

The building was commenced without delay. Along the huge bank the trunks
were got into place according to their sizes and floating power, which
of course had to be taken into account, as among these thick and heavy
woods there were many whose specific gravity was but little below that
of water.

The first layer was entirely composed of trunks laid side by side.
A little interval had to be left between them, and they were bound
together by transverse beams, which assured the solidity of the whole.
_"Piacaba"_ ropes strapped them together as firmly as any chain cables
could have done. This material, which consists of the ramicles of a
certain palm-tree growing very abundantly on the river banks, is in
universal use in the district. Piacaba floats, resists immersion, and
is cheaply made--very good reasons for causing i