122 
AFRICA AND ITS EXPLORATION. 
the Zambeze ; and that therefore a voyage pittoresque up 
the Congo should be made at that season. 
Before leaving the Yellala, I wandered along the 
right bank, and found a cliff, whose overhanging brow 
formed a fine cavern ; it remarkably resembled the 
Martianez Fountain under the rock near the beautiful 
Puerto de Orotava. Here the fishermen were disport- 
ing themselves^ and cooking their game, which they 
willingly exchanged for beads. All were of the Silurus 
family, varying from a few inches to two feet. Fish- 
eagles sat upon the ledges overhanging the stream, and 
a flight of large cranes wheeled majestically in the upper 
air : according to the people, they are always to be seen 
at the Yellalas. 
The extent of a few hundred feet afforded a good 
bird’s-eye view of the scene. The old river-valley, 
shown by the scarp of the rocks, must have presented 
gigantic features, and the height of the trough-walls, at 
least a thousand feet, gives the Yellala a certain beauty 
and grandeur. The site is apparently the highest axis 
of the dividing ridge separating the maritime lowlands 
from the inner plateau. Looking eastward the land 
smoothens, the dorsa fall more gently towards the 
counter-slope, and there are none of the “ Morros ” 
which we have traversed. 
With the members of the Congo Expedition, I was 
somewhat startled by the contrast between the appa- 
rently shrunken volume of waters and the vast breadth 
of the lower river ; hence Professor Smith’s theory of 
underground caverns and communications, in fact of a 
subterraneous river, a favourite hobby in those days. 
But there is not a trace of limestone formation around, 
nor is there the hollow echo which inevitably would 
result from such a tunnel. Evidently the difference is 
to be accounted for by the rapidity of the torrent, the 
effect of abnormal slope deceiving the eye. At the 
Mosi-wa-tunya Falls the gigantic Zambeze, from a 
breadth of a thousand yards suddenly plunges into a 
trough only forty-five to sixty feet wide ; the same is 
the case with the Brazilian Sao Francisco, which, a mile 
