Each house of these hamlets has a palisade of thick stakes around it, and the door is made to resemble the rest of the stockade; the door is never seen open; when the owner wishes to enter, he removes a stake or two, squeezes his body in, then plants them again in their places, so that an enemy coming in the night would find it difficult to discover the entrance. These palisades seem to indicate a sense of insecurity in regard to their fellow-men, for there are no wild beasts to disturb them; the bows and arrows have been nearly as efficacious in clearing the country here as guns have in the country farther south. This was a disappointment to us, for we expected a continuance of the abundance of game in the north which we found when we first came up to the confluence of the Leeba and Leeambye. A species of the silver-tree of the Cape ('Leucodendron argenteum') is found in abundance in the parts through which we have traveled since leaving Samoana's. As it grows at a height of between two and three thousand feet above the level of the sea, on the Cape Table Mountain, and again on the northern 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 approximation 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.* * On examining this subject when I returned to Linyanti, I found that, according 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 sometimes as much as four and a half. If, however, we make allowances for roughness 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 modifying circumstances, it is difficult to draw any reliable conclusion from the currents. The Chobe is sometimes heard of as flooded, about 40 miles above Linyanti, a fortnight before the inundation reaches that point, but it is very tortuous. The great river Magdalena falls only 500 feet in a thousand miles; other rivers much more.