The powerful influence of the sun, which at this period is almost vertical, quickly dissipates the clouds which obscure the sky, and produces an almost insupportable effect; but new clouds soon condense, and intercept the solar rays; a mitigating heat follows; the pores are compressed, and prespiration ceases. Variations succeeding so rapidly, are attended with the most serious 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.