122 
r i v 
are not familiar. The Hoangho, the great river of China, 
rises on the south side of the great eastern ridge we have 
so often mentioned. This elevation, which is a continua¬ 
tion of the former, is somewhat of the same complexion, 
being very sandy, and at present is a desert of prodigious 
extent. It is described, however, as interspersed with vast 
tracts of rich pasture ; and we know that it was formerly 
the residence of a great nation, who came south, by the 
name of Turks, and possessed themselves of most of the 
richest kingdoms of Asia. In the south-western extremity 
of this country are found remains not only of barbaric mag¬ 
nificence, but even of cultivation and elegance. It was a 
profitable privilege granted by Peter the Great to some ad¬ 
venturers to search these sandy deserts for remains of former 
opulence, and many pieces of delicate workmanship (though 
not in a style which nue should admire) in gold and silver were 
found. Vaults were found buried in the sand filled with 
written papers, in a character wholly unknown ; and a wall 
was discovered extending several miles, built with hewn stone, 
and ornamented with corniche and battlements. But we 
are forgetting ourselves, and return to the consideration of 
the distribution of the rivers on the surface of the earth. A 
great ridge of mountains begins at the south-east corner of 
the Euxine sea, and proceeds eastward, ranging along the 
south side of the Caspian, and still advancing unites with the 
mountains first mentioned in Thibet, sending off some branch¬ 
es to the south, which divide Persia, India and Thibet. From 
the south side of this ridge flow the Euphrates, Tigris, Indus, 
Ganges, &c. and from the north the ancient Oxus and many 
unknown streams. ' 
There is a remarkable circumstance in this quarter of the 
globe. Although it seems to be nearest to the greatest ele¬ 
vations, it seems also to have places of the greatest depression. 
We have already said that the Caspian sea is lower than the 
ocean. There is in its neighbourhood another great bason 
of salt water, the lake Aral, which receives the waters of the 
Oxus or Gihon, which were said to have formerly run into 
the Caspian sea. There cannot, therefore, be a great differ¬ 
ence in the level of these two basons; neither have they any 
outlet, though they receive great rivers. There is another 
great lake in the very middle of Persia, the Zare or Zara, which 
receives the river Hindemend, of near 250 miles in length, 
besides other streams. 'There is another such in Asia Minor. 
The sea of Sodom and Gomorrah is another instance. And 
in the high countries we mentioned, there are many small 
salt lakes, which receive little rivers, and have no outlet. 
The lake Zara in Persia, however, is the only one which 
indicates a considerable hollow of the country. It is 
now ascertained, by actual survey, that the sea of Sodom 
is considerably higher than the Mediterranean. This fea¬ 
ture is not, however, peculiar to Asia; it obtains also in 
Africa. 
In America, a chain of mountains begins, or at least is 
found, in longitude 110° west of London, and latitude 40° 
north, on the northern confines of the kingdom of Mexico, 
and stretching southward through that kingdom, forms the 
ridge of the neck of land which separates North from South 
America, and keeping almost close to the shore, ranges along 
the whole western coast of South America, terminating at 
Cape Horn. In its course it sends off branches, which after 
separating from it for a few leagues, rejoin it again, inclosing 
valleys of great extent from north to south, and of prodigious 
elevatiou. In one of these, under the equatorial sun, stands 
the city of Quito, in the midst of extensive fields of barley, 
oats, wheat, and gardens, containing apples, pears, and goose¬ 
berries, and in short, all the grains and fruits of the cooler 
parts of Europe; and although the vine is also there in per¬ 
fection, the olive is wanting. Not a dozen miles from it, in 
the low countries, the sugar-cane, the indigo, and all the 
fruits of the torrid zone, find their congenial heat, and the 
inhabitants swelter under a burning sun. At a small distance 
on the other hand tower aloft the pinnacles of Pichincha, 
Corambourou, and Chimboracao, crowned with never- 
melting snows. 
The individual mountains of this stupendous range not 
E R. 
only exceed in height all others in the world (if we except 
the Peak of Teneriffe, Mount iEtna, and Mont Blanc); but 
they are set down On a base incomparably more elevated 
than any other country. They cut off therefore all commu¬ 
nication between the Pacific ocean and the inland continent; 
and no rivers are to be found on the west coast of South 
America which have any considerable length of course or 
body of waters. The country is drained, like Africa, in the 
opposite direction. Not 100 miles from the city of Lima, 
the capital of Peru, which lies almost on the sea shore, and 
just at the foot of the high Cordilleras, arises out of a small 
lake, the Maragnon, or Amazon’s-river, which, after running- 
northward for about 100 miles, takes an easterly direction, 
and crosses nearly the broadest part of South America, and 
falls into the great western ocean at Para, after a course of 
not less than 3500 miles. In the first half of its descent, 
it receives a few middle-sized rivers from the north, and from 
the south it receives the great river Combos, springing from 
another little lake, not 50 miles distant from the head of the 
Maragnon, and inclosing between them a wide extent of 
country. Then it receives the Yuta, the Yuerva, the Cu- 
chivara, and Parana Mire, each of which is equal to the 
Rhine; and then the Madeira, which has flowed above 
1300 miles. At their junction the breadth is so great, that 
neither shore can be seen by a person standing up in a 
canoe; so that the united stream must be about 20 miles 
broad. In this majestic form it rolls along at a prodigious 
rate, through a flat country, covered with impenetrable fo¬ 
rests, and most of it as yet untrodden by human feet. Mr. 
Condamine, who came down the stream, says, that all is 
silent as the desert, and the wild beasts and numberless birds 
crowd round the boat, eyeing it as some animal of which 
they did not seem afraid. The bed was cut deep through 
an equal and yielding soil, which seemed rich in every part, 
if he could judge by the vegetation, which was rank in the 
extreme : and although the velocity in the main stream was 
great, he observed that it was extremely moderate, nay, 
almost still, at the sides; so that in those parts where the 
country was inhabited by men, the Indians paddled up the 
river with perfect ease. Boats could go from Para to near 
the mouth of the Madeira in 38 days, which is near 1200 
miles. 
The origin of rivers appears to be in all cases the springs 
of the earth, and as springs are most abundant in the highest 
lands, we accordingly find the heads of rivers appearing in 
mountains. The melting of snows, and the collection of 
rains from declivities, augment the rivulet by slow, but 
manifold degrees, until it assumes the form of a river. 
The laws that govern the flowing of rivers are among the 
most important in the science of hydraulics: for in civilized 
countries, where every stream is a channel of communication, 
and an assistant to traffic, all circumstances connected with 
embankments, bridges, &c. are highly interesting. Hence, 
in this country, the theory of currents has been investigated 
with much attention and correspondent success: but we 
are indebted to Italy for the first information on this sub¬ 
ject. Among several contradictions and absurdities, Gu- 
glielmini developed a mode of considering the phenomena of 
currents that has been of the utmost use to all subsequent in¬ 
quirers. 
When it was discovered experimentally (as we have shewn 
in the article Mechanics), that the velocities of water issu¬ 
ing from orifices at various depths under the surface were 
as the square roots of those depths, and the fact was verified 
by repeated experiments, this principle was immediately and 
without modification applied to every motion of water. Gug- 
lielmiui made it the basis of a complete system of hydraulics. 
He considers every point P (fig.‘1.) in a mass of fluid as 
an orifice in the side of a vessel, and conceives the particle 
as having a tendency to move with the same velocity with 
which it would issue from the orifice. Therefore, it a verti¬ 
cal line A P C be drawn through that point, and if this be 
made the axis of a parabolic A D E, of which A at the sur¬ 
face of the fluid is the vertex, and A B (four times the 
' height 
