Equinoctial Regions of America, vol 3 | Page 8

zodiacs contain the signs of the Monkey and the
Tiger, they, no doubt, originated in the torrid zone. With the Muyscas,
inhabitants of New Grenada, the first sign, as in eastern Asia, was that

of water, figured by a Frog. It is also remarkable that the astrological
worship of the Muyscas came to the table-land of Bogota from the
eastern side, from the plains of San Juan, which extend toward the
Guaviare and the Orinoco.) Thus we find the general results of
comparative hydrography in the astrological monuments, the divisions
of time and the religious traditions of nations the most remote from
each other in their situation and in their degree of intellectual
advancement.
As the equatorial rains take place in the flat country when the sun
passes through the zenith of the place, that is, when its declination
becomes homonymous with the zone comprised between the equator
and one of the tropics, the waters of the Amazon sink, while those of
the Orinoco rise perceptibly. In a very judicious discussion on the
origin of the Rio Congo,* (* Voyage to the Zaire page 17.) the
attention of philosophers has been already called to the modifications
which the periods of the risings must undergo in the course of a river,
the sources and the mouth of which are not on the same side of the
equinoctial line.* (* Among the rivers of America this is the case with
the Rio Negro, the Rio Branco, and the Jupura.) The hydraulic systems
of the Orinoco and the Amazon furnish a combination of circumstances
still more extraordinary. They are united by the Rio Negro and the
Cassiquiare, a branch of the Orinoco; it is a navigable line, between
two great basins of rivers, that is crossed by the equator. The river
Amazon, according to the information which I obtained on its banks, is
much less regular in the periods of its oscillations than the Orinoco; it
generally begins, however, to increase in December, and attains its
maximum of height in March.* (* Nearly seventy or eighty days after
our winter solstice, which is the summer solstice of the southern
hemisphere.) It sinks from the month of May, and is at its minimum of
height in the months of July and August, at the time when the Lower
Orinoco inundates all the surrounding land. As no river of America can
cross the equator from south to north, on account of the general
configuration of the ground, the risings of the Orinoco have an
influence on the Amazon; but those of the Amazon do not alter the
progress of the oscillations of the Orinoco. It results from these data,
that in the two basins of the Amazon and the Orinoco, the concave and
convex summits of the curve of progressive increase and decrease

correspond very regularly with each other, since they exhibit the
difference of six months, which results from the situation of the rivers
in opposite hemispheres. The commencement of the risings only is less
tardy in the Orinoco. This river increases sensibly as soon as the sun
has crossed the equator; in the Amazon, on the contrary, the risings do
not commence till two months after the equinox. It is known that in the
forests north of the line the rains are earlier than in the less woody
plains of the southern torrid zone. To this local cause is joined another,
which acts perhaps equally on the tardy swellings of the Nile. The
Amazon receives a great part of its waters from the Cordillera of the
Andes, where the seasons, as everywhere among mountains, follow a
peculiar type, most frequently opposite to that of the low regions.
The law of the increase and decrease of the Orinoco is more difficult to
determine with respect to space, or to the magnitude of the oscillations,
than with regard to time, or the period of the maxima and minima.
Having been able to measure but imperfectly the risings of the river, I
report, not without hesitation, estimates that differ much from each
other.* (* Tuckey, Maritime Geogr. volume 4 page 309. Hippisley,
Expedition to the Orinoco page 38. Gumilla volume 1 pages 56 to 59.
Depons volume 3 page 301. The greatest height of the rise of the
Mississippi is, at Natchez, fifty-five English feet. This river (the largest
perhaps of the whole temperate zone) is at its maximum from February
to May; at its minimum in August and September. Ellicott, Journal of
an Expedition to the Ohio.) Foreign pilots admit ninety feet for the
ordinary rise in the Lower Orinoco. M. Depons, who has in general
collected very accurate notions during his stay at Caracas, fixes it at
thirteen fathoms. The heights naturally vary according to the breadth of
the bed and the number of tributary streams