CAUSE OF THE EIVEE-FLOOD3. 
11 
■Witli the Eio Guaviare, the sources of the Orinoco were 
sought towards the south-west, on the eastern hack of the 
Andes, the risings of this river were attributed to a perio- 
dical melting of the snows. This reasoning was as far from 
the truth as that in which the Nile was formerly supposed 
p he swelled by the waters of the snows of Abyssinia. The 
^ordilleras of New Grenada, near which the western tribu- 
tary streams of the Orinoco, the Guaviare, the Meta, and 
the Apure, take their rise, enter no more into the limit of 
peiyetual snows, with the sole exception of the Paramos of 
t^hita and Mucuchies, than the Alps of Abyssinia. Sno^vy 
fountains are much more rare in the torrid zone than is 
generally admitted ; and the melting of the snows, which is 
ot copious there at any season, does not at all increase at 
e time of the inimdations of the Orinoco, 
the cause ot the periodical swellings of the Orinoco acts 
on all the rivers that take rise in the torrid zone, 
ter the vernal equinox, the cessation of the breezes 
the season of rains. The increase of the rivers 
t^nich may be considered as natural pluviometers), is in 
proportion to the quantity of water that falls in the different 
egions. This quantity, in the centre of the. forests ot the 
pper Orinoco and the Eio Negro, appeared to me to exceed 
inches annually. Such of the natives, therefore, 
th beneath the misty sky of the Esmeralda and 
know, without the .smallest notion of natural 
Eudoxus and Eratosthenes knew hereto- 
solei r inundations of the great rivers are owing 
-arnJ' equatorial rains. The following is the usual 
oscillations of the Orinoco. Immediately 
Mar equinox (the people say on the 25th of 
is at*fi 1 eoHimeucement of the rising is perceived. It 
river an inch in twenty-four hours ; sometimes the 
™ April; it attains its maximum in July; 
*be same level from the end of J uly till the 25th 
slowl then decreases progressively, but more 
a.Tirl ■p n Mcreased. It is at its minimum in January 
torrirl ^ Ih both worlds the rivers of the northern 
DerinrI greatest height nearly at the same 
F • Ihe Ganges, the Niger, and the Gambia, reach the 
• StraOo, lib. 17, p 739. Digd. Sic., lib. 1, c. 5 . 
