THE GREAT CATARACTS. 
253 
the freat cataracts are not found near the sources of the 
rivers. After a tranquil course of more than one hundred 
and sixty leagues from the little Eaudal of Guaharibos, east 
of Esmeralda, as far as the mountains of Sipapu, the river, 
augmented by the waters of the Jao, the A entuari, the 
Atabapo, and the Guaviare, suddenly changes its primitive 
direction from east to west, and runs from south to north : 
then, in crossing the land-strait* in the plains of Meta, 
meets the advanced buttresses of the Cordillera of Parima. 
This obstacle causes cataracts far more considerable, and 
presents greater impediments to navigation, than all the 
Pongos of the Upper Maranon, because they are propor- 
tionally nearer to the mouth of the river. These geogra- 
phical details serve to prove, in the instances of the two 
greatest rivers of the N ew AY orld, 1st, that it cannot be 
ascertained in an absolute manner that, beyond a certain 
number of toises, or a certain height above the level of the 
sea, rivers are not navigable ; 2ndly, that the rapids are not 
always occasioned, as several treatises ol general topography 
affirm, by the height of the first obstacles, by the first lines 
of ridges which the waters have to surmount near their 
sources. 
The most northern of the great cataracts of the Orinoco 
Is the only one bounded on each side by lofty mountains. 
The left hank of the river is generally lower, hut it makes 
part of a plane which rises again west of Atures, towards the 
Peak of Uniana, a pyramid nearly three thousand feet high, 
and placed on a wall of rock with steep slopes. The situa- 
tion of this solitary peak in the plain contributes to render 
its aspect more imposing arid majestic. Near the Mission, 
in the country which surrounds the cataract, the aspect of 
''he landscape varies at every step. AVithin a small space 
"'e find all that is most rude and gloomy in nature, united 
" ith an open country and lovely pastoral scenery. In the 
Physical, as in the moral world, the contrast of effects, the 
comparison of what is powerful and menacing with what is 
s °ft and peaceful, is a never-failing source of our pleasures 
an d our emotions. 
I shall here repeat some scattered features ot a picture 
* This strait, which I have several times mentioned, is formed hy the 
L °rniUe.-as of the Andes of New Granada, and the Cordillera of Parima. 
