23S RAPIDS— BIEDS. Chap. 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, winch 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 fall 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 Ingh 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 Tantalus cwpensis of Lich. 



