eighty miles
from its mouth, large vessels might sail from the Amazon into the very
heart of Bolivia. When full, it has a three-mile current, and at its
junction with the Amazon it is two miles wide and sixty-six feet deep.
Five hundred miles from its mouth it is a mile wide and one hundred feet
deep. It contains numerous islands, and runs in a comparatively straight
course. It received its name from the vast quantity of drift-wood often
seen floating down. The value of Brazilian commerce with Bolivia by the
Madeira was, in 1867, $43,000.[152]

[Footnote 152: In the map of Friar Fritz, published in 1707, the Madeira
is one of the most insignificant of the tributaries, and the Ucayali and
Putumayo are the largest.]

At Santarem the Amazon receives another great tributary, the Tapajos (or
Rio Preto, as the Portuguese call it), a thousand miles long, and, for
the last eighty miles, from four to twelve miles in breadth. It rises
amid the glittering mines of Matto Grosso, only twenty miles from the
headwaters of the Rio Plata, and flows rapidly down through a
magnificent hilly country to the last cataract, which is one hundred and
sixty miles above Santarem, and is the end of navigation to sailing
vessels. Thence to the Amazon it has little current and no great depth.
From Santarem to Diamantino it is about twenty-six days' travel. Large
quantities of sarsaparilla, rubber, tonka beans, mandioca, and guarana
are brought down this river.

Parallel to the Tapajos, and about two hundred miles distant, flows the
Xingu. It rises in the heart of the empire, has the length of the Ohio
and Monongahela, and can be navigated one hundred and fifty miles. This
is the last great tributary of the Amazon proper; if, however, we
consider the Para as only one of the outlets of the great river, we may
then add to the list the grand Tocantins.[153] This splendid river has
its source in the rich province of Minas (the source, also, of the San
Francisco and Uruguay), not six hundred miles from Rio Janeiro--a region
possessing the finest climate in Brazil, and yielding diamonds and
rubies, the sapphire, topaz and opal, gold, silver, and petroleum. The
Tocantins is sixteen hundred miles long, and ten miles broad at its
mouth; but, unfortunately, rapids commence one hundred and twenty miles
above Cameta. The Araguaia, its main branch, is, according to Castelnau,
one mile wide, with a current of three fourths of a mile an hour.

[Footnote 153: We