[Footnote A: _Gentleman's Magazine, Supplement, 1763. Extract of a
letter wrote from the island of Senegal, by Mr. Boone, practitioner of
physic there, to Dr. Brocklesby of London._

"To form just idea of the unhealthiness of the climate, it will
be necessary to conceive a country extending three hundred
leagues East, and more to the North and South. Through this
country several large rivers empty themselves into the sea;
particularly the Sanaga, Gambia and Sherbro; these, during the
rainy months, which begin in July and continue till October,
overflow their banks, and lay the whole flat country under
water; and indeed, the very sudden rise of these rivers is
incredible to persons who have never been within the tropicks,
and are unacquainted with the violent rains that fall there. At
Galem, nine hundred miles from the mouth of the Sanaga, I am
informed that the waters rise one hundred and fifty feet
perpendicular, from the bed of the river. This information I
received from a gentleman, who was surgeon's mate to a party
sent there, and the only survivor of three captains command,
each consisting of one captain, two lieutenants, one ensign, a
surgeon's mate, three serjeants, three corporals, and fifty
privates.

"When the rains are at an end, which usually happens in October,
the intense heat of the sun soon dries up the waters which lie
on the higher parts of the earth, and the remainder forms lakes
of stagnated waters, in which are found all sorts of dead
animals. These waters every day decrease, till at last they are
quite exhaled, and then the effluvia that arises is almost