s of the actual geography
of South Africa (i.e., from primeval times to the present
day), does, or does not, extend into Northern Africa. Looking
at that much broader portion of the continent, we have some
reason to surmise that the higher mountains also form, in a
general sense, its flanks only."--President's Address, Royal
Geographical Society, 1852, p. cxxiii.

The characteristics of the rainy season in this wonderfully humid region
may account in some measure for the periodical floods of the Zambesi,
and perhaps the Nile. The rains seem to follow the course of the sun,
for they fall in October and November, when the sun passes over this
zone on his way south. On reaching the tropic of Capricorn in December,
it is dry; and December and January are the months in which injurious
droughts are most dreaded near that tropic (from Kolobeng to Linyanti).
As he returns again to the north in February, March, and April, we
have the great rains of the year; and the plains, which in October and
November were well moistened, and imbibed rain like sponges, now
become supersaturated, and pour forth those floods of clear water which
inundate the banks of the Zambesi. Somewhat the same phenomenon probably
causes the periodical inundations of the Nile. The two rivers rise
in the same region; but there is a difference in the period of flood,
possibly from their being on opposite sides of the equator. The waters
of the Nile are said to become turbid in June; and the flood attains
its greatest height in August, or the period when we may suppose the
supersaturation to occur. The subject is worthy the investigation of
those who may examine the region between the equator and 10 Deg. S.;
for the Nile does not show much increase when the sun is at its farthest
point north, or tropic of Cancer, but at the time of its returning to
the equator, exactly as in the other case when he is on Capricorn, and
the Zambesi is affected.*

* The above is from my own observation, together with
information derived from the Portuguese in the interior of
Angola; and I may add that the result of many years'
observation by Messrs. Gabriel and Brand at Loanda, on the
west coast, is in accordance therewith. It rains there between
the 1st and 30th of November, but January and December are
usually both warm and dry. The heavier rains commence about
the 1st of February, and last until the 15th of May. Then no
rain fall