Year: 1867

Second Lecture by Professor AEassIz


ON the Amazon and Its Tributaries.


A large audience assembled last
evening in the Hall of the Cooper In
stitute, to listen to the second lecture
of Professor Agassiz on Brazil. The
special subject of his lecture was 1.-THE
Amazon and its Tributaries" We
make few extracts from this lecture /:


The Amazon flows nearly parallel to
the Equator in a WesteaSterly dfrec-
ton, the main trunk not deviating
from the Equator more than two or
three degrees, while its Southern tribu-
taries rise from IL to Is degrees South,
and its Northern, from to degrees
North; so that the width OF the valley
at some points is nearly as great as its
total length. The fact that this main
portion of the Amazon flows in one
and the same latitude, brings result
very different, with reference to the eli
mate, from that which we observe
along the banks of other large rivers
which flow in NorthsoutherIy direc-
ton, or in Southnortherly direction.
Our Mississippi begins its course in very
cold regions, and ends il almost in the
tropics. The Nile begins under the
Equator, and further South, and ter
inmates in the Mediterranean where
the climate is always temperate.


You see, therefore, that those rivers
are, as they flow on, under very chang
ing climatic influences. Not so with
the Amazon, which occupies a belt un-
der the Equator, and retains the same
climatic conditions for its whole length,
and would present a great monotony
were it not for the peculiar character of
its tributaries, and for the peculiar
economy of the waters which fill its
basin. Extending its trunk across the
whole continent and sending its
branches North and South over uch a
wide area, the basin of the Amazon es-
tablishes communication with all the
adjoining Republics of South America.
And this is a point of great importance
with reference to the fact that the Anna
Zon is this year to be opened to the
commerce of the world; for, in conse-
quence of the natural physical relation
of the Amazon, its tributaries, and the
areas drained by those tributaries, the
opening of the Amazon does not only
bring the internal commerce of Brazil
into immediate contact with the COM
merce of the world, but also that of
those republics, the surface of which is
mainly drained by the tributaries of
the Amazon.


An extensive prospect is open to the
enterprise of sea-faring nations by the
mere fact that the navigation of the
Amazon will be free as the sea itself TO
the mercantile shipping of all nations.
-YOu.may realize what il is for us by
considering for moment what it would
be to the shipping of England or of
France, if the United States We're at
once to declare that the Mississipni he
open to their navigation-if the flags of
Europe could float at Cincinnati or St.
Louis, and all the tributaries of the
Mississippi, as well as the main river
itself, should be allowed to be naviga.
ted by foreign ships. 1t is that step
which the Emperor of Brazil has tax
m TEa h Ia L. L


try to the enterprise OF the world, and
no nation is as likely to be as greatly
benefited by it as the people of the
United States.


Now you may ask: "How can it be
that a nation throws away its wealth
in that manner into the hands of for
eigners? 2" Very serious considerations
must have weighed in the scales to in
duce the Government to divest itselfto
that extent of its internal property,
The case is simple. The whole valley
of the Amazon has not vet been peo-
pied. The whole tract of this country
which is as large as many empires of
the first rank in the Old World-the
whole of that country drained by the
Amazon, does not nourish at this mo-
ment 25O, 900 individuals, including. the
Indians and no doubt the Government
of Brazil has thought that the only
way of settling that rich country was
~ OAAGL Llc LAGdSuEtS 70 dll udLlOQS.


When we speak of the Valley of the
Amazon, we ought to at once divest
ourselves of the ordinary idea which
we combine with the word "valley."
There is not a bottom, with walls or
banks rising on both sides and forming
an enclosure to the water that runs in
the bottom of the Valley. Here the
basin of the Amazon is an extensive
plain. 1t is so fiat that the slope is
hardly more than foot in ten miles
and over the whole of this extent of
$500 miles the slope is not more than
30 feet. 1t is only IS feet from Obidos
to the sea shore, and it is only 200 feet
from Sabatinga to the sea shore, and
yet the distance is, in a straight line,
over 800 miles, so that really the slope
is hardly a foot in ten miles. The i'm
preston to the eye is that of an abso-
lutte plain, and the flow of water is so
gentle generally that in many parts il
hardly seems TO flow. 1t makes the
impression of a fresh water ocean far
basin compares favorably to its extra
ordinary length. There is not one
channel through which the bulk of the
water flows, but a multitudinous num-
Der of channels connected with one
another in the most various ways so
that instead of travelling in straight
course, you may ascend the Amazon
in any number of parallel channels,
and pass from one to another by any
number of intersecting communica-
tious. And this network of rivers
spreads over an area which is some
times, 50, so, 100, $50, or nearly 200 miles
wide. In that region you have to trav-
el for about go miles from the mouth
of the Madeira before you come to the
rising land over which the water falls
in cascades. At the Tocatius and To-
pnjos and Niuga you have to ascend
one hundred and fifty or one hundred
and eighty miles before you come to
those higher grounds which determine
rapids into water courses, and on the
North side 1t is equally at considera-
bic distance from the centre of the basin
that the land rises into gates. over
the whole expanse of the valley, for
hundreds of miles on either side of the
main channel, the bottom of the valley
is as fiat at the side as it is in a Iongi-
tudinal direction; so that ii is all inun-
dated plain, rather than a river; and if
there are channels in which water flows
more constantly tan others, these
channels are so frequently overfowed
by the rise of the water, you have fire.
quently, for a month at a time, the


water covering this wide expanse with
out break. But there is a great differ
ence in the character OF these water
courses, and great difference also in
the nature of the water itself.


The hottest point of the Earth's tenn


perature extends to the North of the
Valley ofthe Amazon, along the North
ern shore of Guiana, and this part OF
! the continent referring to the map
The valley of the Amazon is of mildeE
stances-the extent OF submerged land,
| with the constant eyaporation and the