RIVERS. 
down with the stream, as to the rising of the 
earth in Egypt, that has for so many ages 
received tins extraneous supply. Rut we 
do not find, by the buildings that have re- 
mained since the times of the antients, that 
the earth is much raised since then. Besides 
the Nile in Africa, we may reckon Zara, and 
the Coanza, from the greatness of whose 
openings into the sea, and the rapidity of 
whose streams, we form an estimate oi the 
1 great distance whence they come. Their 
courses, however, are spent in watering de- 
serts and savage countries, whose poverty or 
fierceness have kept strangers away. 
But of all parts of the world, America, as 
it exhibits the most lofty mountains, so also 
it supplies the largest rivers. The principal 
of these is the great river Amazons, which, 
: from its source in the lake of Lauricocha, to 
| its discharge into the Western Ocean, per- 
forms a course or' more than twelve hundred 
leagues. The breadth and depth of this river 
is answerable to its vast length ; and, where 
its width is most contracted, its depth is aug- 
mented in proportion. So great is the body 
of its waters, that other rivers, though before 
the objects of admiration, are lost in its bo- 
som. It proceeds after their junction, with 
its usual appearance, without any visible 
change in its breadth or rapidity; and, if we 
i may so express it, remains great without os- 
| tentation. In some places it. displays its 
whole magnificence, dividing into several 
large branches, and encompassing a multi- 
tude of islands ; and at length, discharging 
itself into tiie ocean, by a channel of an hun- 
dred and fifty miles broad. Another river, 
that may almost rival the former, is the St. 
Lawrence, in Canada, which rising in the 
lake Assiniboils, passes from one lake to an- 
other, from Christinaux to Alempigo ; and 
thence to lake Superior ; thence to the lake 
Ilurons ; to lake Erie ; to lake Ontario ; 
and, at last, after a course of nine hundred 
leagues, pours their collected waters into the 
Atlantic Ocean. The river Mississippi is 
more than seven hundred leagues in length, 
beginning at its source near the lake Assi- 
niboils, and ending at its opening into the 
Gulph of Mexico. The river Plata runs a 
length of more than eight hundred leagues 
from its source in the river Parana, to its 
mouth. The river Oroonoko is -seven hun- 
dred and fifty leagues in length, from its 
source near Pasto, to its discharge into the 
Atlantic ocean. 
Such is the amazing length of the greatest 
rivers ; and even in some of these, the most 
remote sources very probably yet continue 
unknown. In fact, if we consider the num- 
ber of rivers which they receive, and the little 
acquaintance we have with the regions 
through which they run, it is not to be won- 
dered at that geographers are divided con- 
cerning the sources of most of them. As 
among a number of roots by which nourish- 
ment is conveyed to a stately tree, it is diffi- 
cult to determine precisely that by which the 
tree is chiefly supplied ; so among the many 
* branches of a great river, it is equally diffi- 
cult to tell which is the original. Hence it 
may easily happen, that a similar branch is 
taken for the capita! stream; and its run- 
nings are pursued and delineated, in preju- 
dice of some other branch that better deserv- 
ed the name and the description. In this 
VoL. II. 
manner, in Europe, the Danube is known 
to receive thirty lesser rivers; the Wolga 
thirty-two or thirty-three. In Asia, the IIo- 
hanno receives thirty-five ; the Jenisca above 
sixty ; the Obv as many ; the Amour about 
forty ; the Nanquin receives thirty rivers ; 
the Ganges twenty ; and the Euphrates 
about eleven. In ‘Africa, the Senegal re- 
ceives more than twenty rivers ; the Nile 
receives not one for five hundred leagues 
upwards, and then only twelve or thirteen. 
Iii America, the river Amazons receives 
above sixty, and those very considerable ; 
the river St. Lawrence about forty, counting 
those which fall into its lakes ; the Missis- 
sippi receives forty ; and the river Plata above 
fifty. 
The inundations of the Ganges and the 
Nile have been already mentioned, and it 
might be added, that almost all great rivers 
have their periodical inundations from simi- 
lar causes. The author already quoted ob- 
serves, that, “ besides these annually peri- 
odical inundations, there are many rivers 
that overflow at much shorter intervals. 
Thus most of those in Peru and Chili have 
scarce any motion by night; but upon the 
appearance of the morning sun they assume 
their former rapidity ; this proceeds from the 
mountain snows, which, melting with the 
heat, encrease the stream, and continue to 
drive on the current while the sun continues 
to dissolve them.” 
There are some rivers which are said to 
lose themselves in chasms under the earth, 
and to flow for several miles in secret and 
undiscovered channels. On this circum- 
stance is founded one of the most beautiful 
fables of antiquity, relative to the fountain of 
Arethusa, in Sicily. The same thing is af- 
firmed of the Rhine, and evenof the river 
Mole, in Surrey, which, from this circum- 
stance derives its name. With respect to 
the two latter rivers, however, some doubts 
are entertained of the fact. 
On this subject there is a memoir of the 
academy of sciences lately published, by the 
abbe Guettard. “ It is very surprising (he 
observes) if we reflect on it, that a river in 
its course, which is very often very extensive, 
should not meet with spongious soils to swal- 
low up its waters, or gulphs in which they are 
lost; nevertheless, as there has been hitherto 
known but a small number of rivers whose 
waters thus disappear, this phenomenon lias 
been accounted very extraordinary, both by 
the ancients and moderns. Mr. Guettard 
next describes what he has observed in seve- 
ral rivers of Normandy, which are lost and 
afterwards appear again ; these are five in 
number, viz. the Rille, the Ithon, the Aure, 
the river of Sap-Audre, and tlie Drome. 
The three first disappear gradually, and then 
come in sight again; the fourth loses itself 
entirely by degrees, but afterwards re-ap- 
pears; the fifth loses some of its water in its 
course, and ends by precipitating itself into 
a cavity, whence it is never seen to rise 
again. 
What seems to occasion the loss of the 
Rille, the Ithon, and the Aure, is the nature 
of the soil through which they pass. M. 
Guettard has observed that it is in general 
porous, and composed of a thick sand, the 
grains of which are not well compacted to- 
gether; it sinks suddenly down by its own 
501 
weight in some places, and there. forms great 
holes; and when the water overflows the 
meadows, it frequently makes many cavities 
in several parts of them. If we therefore 
suppose inequalities in the channels of these 
rivers, and that there are certain places in 
which the water stagnates longer .than in 
others, it must there dilute the ground, it we 
may use that expression ; and having carried 
away the parts which united the grains of 
sand together, those grains will become after- 
wards no other than a kind of sieve, through 
which the waters will filtrate themselves, pro- 
vided nevertheless that they find a passage 
under ground through which they may run. 
This conjecture appears to be so well found- 
ed, that each of these three rivers loses itself 
nearly in the same manner, that is, through, 
cavities which the people of the country call 
betoirs, and which swallow up more or less 
according to their largeness. M. Guettard, 
who lias carefully examined them, remarks, 
that these betoirs are holes in the form of a 
tunnel, whose diameter and aperture is at 
least two feet, and sometimes exceeds eleven ; 
and whose depth varies in like manner from 
one and two feet, to five, six, and even 
twenty. The Rille during the summer season 
loses almost all its water in the space of two 
short leagues ; the Ithon does very near the 
same. But M. Guettard observes something 
curious concerning this river, that formerly 
it was not lost, but kept its course without 
any interruption, as appears by the history of 
the country ; very likely the mud, which 
had been collected'together in several parts 
of its channel, might have occasioned the 
waters remaining in others, and have caused 
many betoirs. This is the more likely, as 
the mud having been collected together in 
the bed of the river Aure, it appears that, in 
consequence, the cavities were greatly en- 
creased, which makes it lose itself much 
sooner than formerly. Besides, possibly an 
earthquake happening in the country might 
have caused several subterraneous canals 
through which the water of the Ithon has 
forced its way. Jn effect, it appears, that a 
soil’s being porous is not sufficient to cause 
the loss of a river ; for if it was, then to do 
so it would occasion many fens round about, 
nor would it renew its course after having dis- 
appeared a certain time; it must besides, 
find ways underground through which it may 
take its course. M. Guettard seems also 
mcuh inclined to believe, that there are, 
in these parts, subterraneous cavities through 
which the waters may flow ; and in conse- 
quence of this he reports a number of facts, 
all tending to prove the truth of it, or at 
least to prove that there must be hollow quar- 
ries serving for strainers to these waters. 
Upon which occasion he goes into a discus- 
sion of this question : Are there any subter- 
raneous rivers, and is the prepossession of 
some persons in favour of this particular well 
founded ? He makes it appear by several in- 
stances which he quotes, and by many rea- 
sons which he alleges, that, there are at least 
very great presumptions in favour of this 
opinion. We are too apt not to look be- 
yond the exterior of things : we feel resist- 
ance upon the .surface of the earth ; when we- 
go deep, we often find it compact. It i s 
therefore hard for us to imagine that it < au 
contain subterraneous cavities sufficient to 
form channels for hidden rivers, or ior any 
