down, having a high and flat central plateau, with a higher rim
of hills surrounding it; from below which, exterially, it
suddenly slopes down to the flat strip of land bordering on the
sea. A dish, however, is generally uniform in shape--Africa is
not. For instance, we find in its centre a high group of hills
surrounding the head of the Tanganyika Lake, composed chiefly of
argillaceous sandstones which I suppose to be the Lunae Montes of
Ptolemy, or the Soma Giri of the ancient Hindus. Further,
instead of a rim at the northern end, the country shelves down
from the equator to the Mediterranean Sea; and on the general
surface of the interior plateau there are basins full of water
(lakes), from which, when rains overflow them, rivers are formed,
that, cutting through the flanking rim of hills, find their way
to the sea.


Atmospheric Agents

On the east coast, near Zanzibar, we find the rains following the
track of the sun, and lasting not more than forty days on any
part that the sun crosses; whilst the winds blow from south-west
or north-east, towards the regions heated by its vertical
position. But in the centre of the continent, within 5§ of the
equator, we find the rains much more lasting. For instance, at
5§ south latitude, for the whole six months that the sun is in
the south, rain continues to fall, and I have heard that the same
takes place at 5§ north; whilst on the equator, or rather a
trifle to northward of it, it rains more or less the whole year
round, but most at the equinoxes, as shown in the table on the
following page. The winds, though somewhat less steady, are