s, its principal mouth
entering the Amazon opposite the town of Ega; but it has numberless
small channels, the streams of which, two hundred miles apart, flow into
the great river. The upper part of the Amazon is frequently called the
Solimoens, which name it retains as far south as the mouth of the River
Negro.

About sixty miles further east, its largest southern affluent--the
gigantic Madeira--unites its milky waters with the turbid stream of the
main river. One branch, the Beni, rises in the neighbourhood of the
ancient Cuzco in Peru, near Lake Titicaca, its whole extent from the
centre of the province of Bolivia being nearly the length of the Amazon
itself. At its mouth it is two miles wide and sixty-six feet deep; and
five hundred miles up it is a mile wide. Numerous islands are found in
its course: for nearly five hundred miles it is navigable for large
vessels, when a cataract intervenes. Were it not for this, there would
be a free navigation from the centre of the province of Bolivia to the
ocean, embracing islands the size of many of the Old World provinces,
and widening into broad lakes. The monarch of waters flows on between
its low forest-clothed banks till, four hundred miles from its mouth, it
reaches the Strait of Obydos, where it is narrowed to two thousand
paces. Through this channel its waters rush with immense force,
calculated at five hundred thousand cubic feet in one second--sufficient
to fill all the streams in Europe, and swell them to overflowing. No
plummet has hitherto sounded the depth of its bed at this point, the
force of the stream probably rendering the operation almost
impracticable.

Its last two great tributaries are the Tapajos, six times the length of
the Thames, and the Xingu, twice that of the Rhine; while further east a
narrow channel unites it with the River Para, into which flows the broad
stream of the Tocantins. This river, rising in the Minas-Geraes, six
hundred miles from Rio Janeiro, is one thousand six hundred miles long,
and ten miles wide at its mouth. Opposite to Para is the large island
of Marajo; and if Professor Agassiz is right in supposing that the
continent once extended much further to the east than it now does, this
island may properly be considered in the centre of the mouth of the
river, and the River Para might then properly be called one of its true
embouchures. But only a few of the streams which feed the Amazon have
been named. Numberless ot