306 DENSE FORESTS. 



slope of the Cashan Mountains, and here at considerably greater 

 heights (four thousand feet), the difference of climate prevents 

 the botanical range being considered as affording a good approxi- 

 mation to the altitude. The rapid flow of the Leeambye, which 

 once seemed to me evidence of much elevation of the country 

 from which it comes, I now found, by the boiling point of water, 

 was fallacious.* 



The forests became more dense as we went north. We travel- 

 ed much more in the deep gloom of the forest than in open sun- 

 light. No passage existed on either side of the narrow path made 

 by the axe. Large climbing plants entwined themselves around 

 the trunks and branches of gigantic trees like boa constrictors, 

 and they often do constrict the trees by which they rise, and, kill- 

 ing them, stand erect themselves. The bark of a fine tree found 

 in abundance here, and called " motuia," is used by the Barotse 

 for making fish-lines and nets, and the "molompi," so well 

 adapted for paddles by its lightness and flexibility, was abund- 

 ant. There were other trees quite new to my companions ; many 

 of them ran up to a height of fifty feet of one thickness, and with- 

 out branches. 



In these forests we first encountered the artificial beehives 

 so commonly met with all the way from this to Angola. They 

 consist of about five feet of the bark of a tree fifteen or eighteen 



* On examining this subject when I returned to Linyanti, I found that, accord- 

 ing to Dr. Arnott, a declivity of three inches per mile gives a velocity in a smooth, 

 straight channel of three miles an hour. The general velocity of the Zambesi is 

 three miles and three quarters per hour, though in the rocky parts it is some- 

 times as much as four and a half. If, however, we make allowances for rough- 

 ness of bottom, bendings of channel, and sudden descents at cataracts, and say the 

 declivity is even seven inches per mile, those 800 miles between the east coast and 

 the great falls would require less than 500 feet to give the observed velocity, and 

 the additional distance to this point would require but 150 feet of altitude more. 

 If my observation of this altitude may be depended on, we have a steeper declivity 

 for the Zambesi than for some other great rivers. The Ganges, for instance, is 

 said to be at 1800 miles from its mouth only 800 feet above the level of the sea, 

 and water requires a month to come that distance. But there are so many modi- 

 fying circumstances, it is difficult to draw any reliable conclusion from the cur- 

 rents. The Chobe is sometimes heard of as flooded, about 40 miles above Linyan- 

 ti, a fortnight before the inundation reaches that point, but it is very tortuous. The 

 threat river Magdalena falls only 500 feet in a thousand miles ; other rivers much 

 more. 



