erious effects, and the most fatal consequences. And, lastly, the noxious
exhalations arising from the inaccessible forests and marshy swamps which
abound in Africa, and from numerous animal and vegetable remains of the dry
season, which cover the soil every where, are productive of putrid
effluvia. These rains, or rather periodical torrents of water, which
annually visit the tropics, invariably continue for about four months of
the year, and during the other eight it rarely happens that one single drop
falls; in some instances, however, periodical showers have happened in the
dry season, but the effects of these are scarcely perceptible on
vegetation; the consequence is, that the surface of the earth forms an
impervious stratum or crust, which shuts up all exhalation.

When the rains cease, and the heat of the sun absorbs the evaporations from
the earth, which have been so long concealed during the dry season, a most
offensive and disgusting effluvia is produced, which then fastens upon the
human system, and begets diseases that in a short time shew their effects
with dreadful violence; and no period is more to be guarded against than
when the rains cease, for the intense heat completely impregnates the
atmosphere with animalculae and corrupted matter.

The principal complaints which attack Europeans are, malignant nervous
fevers, which prevail throughout the rainy season, but they are expelled by
the winds which blow in the month of December; from hence these _harmatans_
are considered healthy, but I have heard various opinions among medical men
on this subject. Dr. Ballard (now no more), whose long residence at Bance
Island, and in Africa, and whose intimate acquaintance with the diseases of
these climates, peculiarly qualified him to decide upon the fact, was of
opinion, most decidedly, that the _harmatan_ season was not the most
healthy.

When this malignant fever takes place in all its virulence, its
consequences are the most disastrous; the symptoms are violent and without
gradation, and the blood is heated to an increased degree beyond what is
experienced in Europe; the ninth day is generally decisive, and this is a
crisis that requires the most vigilant attention and care over the patient.
I speak this from personal experience. In consequence of the fatigues I
underwent in the Rio Pongo, and other rivers, and having been for several
days and nights exposed to an open sea, and to torrents of rain upon land,
I