When the wind sets in from the north-east it produces a wonderful change on the face of the country. The grass soon becomes dry and withered; the rivers subside very rapidly, and many of the trees shed their leaves. About this period is commonly felt the _harmattan_, a dry and parching wind, blowing from the north-east, and accompanied by a thick smoky haze, through which the sun appears of a dull red colour. This wind, in passing over the Great Desert of Sahara, acquires a very strong attraction for humidity, and parches up every thing exposed to its current. It is, however, reckoned very salutary, particularly to Europeans, who generally recover their health during its continuance. I experienced immediate relief from sickness, both at Dr. Laidley's and at Kamalia, during the harmattan. Indeed, the air, during the rainy season, is so loaded with moisture, that clothes, shoes, trunks, and every thing that is not close to the fire, become damp and mouldy; and the inhabitants may be said to live in a sort of vapour bath: but this dry wind braces up the solids, which were before relaxed, gives a cheerful flow of spirits, and is even pleasant to respiration. Its ill effects are, that it produces chaps in the lips, and afflicts many of the natives with sore eyes.
Whenever the grass is sufficiently dry, the Negroes set it on fire; but in Ludamar, and other Moorish countries, this practice is not allowed: for it is upon the withered stubble that the Moors feed their cattle, until the return of the rains. The burning the grass in Mandingo exhibits a scene of terrific grandeur. In the middle of the night, I could see the plains and mountains, as far as my eye could reach, variegated with lines of fire; and the light reflected on the sky made the heavens appear in a blaze. In the day-time, pillars of smoke were seen in every direction; while the birds of prey were observed hovering round the conflagration, and pouncing down upon the snakes, lizards, and other reptiles, which attempted to escape from the flames. This annual burning is soon followed by a fresh and sweet verdure, and the country is thereby rendered more healthful and pleasant.
Of the most remarkable and important of the vegetable productions, mention has already been made; and they are nearly the same in all the districts through which I passed. It is observable, however, that although many species of the edible roots which grow in the West India Islands are found in Africa, yet I never saw, in any part of my journey, either the sugar-cane, the coffee, or the cocoa-tree; nor could I learn, on inquiry, that they were known to the natives. The pine-apple, and the thousand other delicious fruits, which the industry of civilized man (improving the bounties of nature) has brought to such great perfection in the tropical climates of America, are here equally unknown. I observed, indeed, a few orange and banana-trees, near the mouth of the Gambia; but whether they were indigenous, or were formerly planted there by some of the white traders, I could not positively learn. I suspect that they were originally introduced by the Portuguese.