umidity of the watershed as compared
with the rest of the country, but by the prevailing winds and the
rains being from the south-east, and thus from the Indian Ocean: with
this wind generally on the surface one can observe an upper strong
wind from the north-west, that is, from the low humid West Coast and
Atlantic Ocean. The double strata of winds can easily be observed when
there are two sheets of clouds, or when burning grass over scores of
square miles sends up smoke sufficiently high to be caught by the
upper or north-west wind. These winds probably meet during the heavy
rains: now in August they overlap each other. The probability arises
from all continued rains within the tropics coming in the opposite
direction from the prevailing wind of the year. Partial rains are
usually from the south-east.

The direction of the prevailing wind of this region is well marked on
the islands in Lake Bangweolo: the trunks are bent away from the
south-east, and the branches on that side are stunted or killed; while
those on the north-west run out straight and make the trees appear
lopsided. The same bend away from the south-east is seen on all
exposed situations, as in the trees covering the brow of a hill. At
Kizinga, which is higher than the Lake, the trees are covered with
lichens, chiefly on the south-east sides, and on the upper surfaces of
branches, running away horizontally to or from the north-west. Plants
and trees, which elsewhere in Africa grow only on the banks of streams
and other damp localities, are seen flourishing all over the country:
the very rocks are covered with lichens, and their crevices with
ferns.

But that which demonstrates the humidity of the climate most
strikingly is the number of earthen sponges or oozes met with. In
going to Bangweolo from Kizinga, I crossed twenty-nine of these
reservoirs in thirty miles of latitude, on a south-east course: this
may give about one sponge for every two miles. The word "Bog" conveys
much of the idea of these earthen sponges; but it is inseparably
connected in our minds with peat, and these contain not a particle of
peat, they consist of black porous earth, covered with a hard wiry
grass, and a few other damp-loving plants. In many places the sponges
hold large quantities of the oxide of iron, from the big patches of
brown haematite that crop out everywhere, and streams of this oxide,
as thick as treacle, are seen moving slowly along in the sponge-like
small red