IMPEDIMENTS TO NAVIGATION. 
261 
what are called rapids ( raudales ). Such are the yellalas, or 
rapids of the River Zaire,* or Congo, which Captain Tuckey 
has recently made known to us ; the rapids oi the Orange 
River in Attica, above Pella; and the falls of the Missouri, 
which are four leagues in length, where the river issues 
from the Rocky Mountains. Such also are the cataracts of 
Atures and Maypures; the only cataracts which, situated 
in the equinoctial region of the New World, are adorned 
with the noble growth of palm-trees. A t all seasons they 
exhibit the aspect of cascades, and present the greatest 
obstacles to the navigation of the Orinoco, while the rapids 
of the Ohio and of TJpper Egypt are scarcely visible at the 
period of floods. A solitary cataract, like Niagara, or the 
cascade of Temi, affords a grand but single picture, varying 
only as the observer changes his place. Rapids, on the 
contrary, especially when adorned with large trees, embel- 
lish a landscape during a length of several leagues. Some- 
times the tumultuous movement of the waters is caused 
only by extraordinary contractions of the beds of the rivers. 
Such is the angoslura of Carare, in the river Magdalena, 
a strait that impedes communication between Santa Fe de 
Rogota and the coast of Carthagena ; and such is the pongc 
of Manseriche, in the Upper Maranon. 
The Orinoco, the Rio Negro, and almost all the con- 
fluents of the Amazon and the Maranon, have falls or rapids, 
either because they cross the mountains where they take 
Rse, or because they meet other mountains in their course. 
If the Amazon, from the pongo of Manseriche (or, to speak 
with more precision, from the pongo of Tayucbuc) as far as 
its mouth, a space of more than seven hundred and fifty 
leagues, exhibit no tumultuous movement of the waters, the 
ttver owes this advantage to the uniform direction of its 
course. It flow's from west to east in a vast plain, forming 
* Voyage to explore the River Zaire, 1818, pp. 152, 327, 340. 'What 
the inhabitants of Upper Egypt and Nubia call ohelldl in the Nile, is called 
Vellala in the River Congo. XhiB analogy between words signifying 
r apids is remarkable, on account of the enormous distance of the yellalas 
of the Congo from the chelldl and djenadel of the Nile. Did the word 
^lellal penetrate with the Moors into the west of Africa? If, with 
Eurckhardt, we consider the origin of this word as Arabic (Travels in 
Nubia, 1819), it must be derived from the root c/ialla, ‘ to disperse,* which 
0r ms chelil , ‘ water falling through a narrow channel.* 
