238 
RAPIDS—BIEDS. 
CiiAr. XIII. 
leap into the water without the least hesitation, to save the 
canoe from being caught by eddies or dashed against the rocks. 
Many parts were now quite shallow, and it required great 
address and power in balancing themselves to keep the vessel 
free from rocks, which lay just beneath the surface. We might 
have got deeper water in the middle, but the boatmen always 
keep near the banks, on account of danger from the hippo¬ 
potami. But though we might have had deeper water farther 
out, I believe that no part of the rapids is very deep. The river 
is spread out more than a mile, and the water flows rapidly over 
the rocky bottom. The portions only three hundred yards wide 
are very deep, and contain large volumes of flowing water in 
narrow compass, which, when spread over the much larger sur¬ 
faces at the rapids, must be shallow. Still, remembering that 
this was the end of the dry season, when such rivers as the 
Orange do not even contain a fifth part of the water of the 
Chobe, the difference between the rivers in the north and south 
must be sufficiently obvious. 
The rapids are caused by rocks of dark-brown trap, or of 
hardened sandstone, stretching across the stream. In some 
places they form miles of flat rocky bottom, with islets covered 
with trees. At the cataracts noted in the map, the fail is from 
four to six feet, and in guiding up the canoe, the stem goes 
under the water, and takes in a quantity before it can attain 
the higher level. We lost many of our biscuits in the ascent 
through this. 
These rocks are covered with a small hard aquatic plant, 
which, when the surface is exposed, becomes dry and crisp, 
crackling under the foot, as if it contained much stony matter in 
its tissue. It probably assists in disintegrating the rocks, for, in 
parts so high as not to be much exposed to the action of the 
water or the influence of the plant, the rocks are covered with a 
thin black glaze. 
In passing along under the overhanging trees of the banks, 
we often saw the pretty turtle-doves sitting peacefully on their 
nests above the roaring torrent. An ibis^' had perched her 
home on the end of a stump. Her loud, harsh scream of 
The Hagidash, Latham ; or Tcndalus capensis of Lich. 
