SCIENTIFIC INTELLIGENCE.

METEOROLOGY.

1. First View of Sierra Leone.-Dr Boyle, in his interesting work on the medical topography of the western coast of Africa, says, "There are very few parts in the tropical world which at first sight hold out more allurements, even to the experienced traveller, than Sierra Leone. Its splendid scenery, and its beautiful river, together with its extensive, commodious, and generally secure harbour, and pleasant-looking town and villages, are calculated to excite the most flattering hopes in respect of health and enjoyment, notwithstanding strong previous impressions with regard to the contrary. On making Sierra Leone from the north, the mountains from which the peninsula was named first excite attention. They are They are lofty, perpetually clothed, from their summits to their bases, in all the fertile gaity of Nature's verdant scenery; and there is a pleasing and endless/variety in the outline of their countless peaks and declivities. As the ship draws in with the shore, signs of cultivation appear, and increase with rapidity, both in number and attractiveness. Freetown, and the lately formed villages in its neighbourhood, at first appear like anomalous patches in the view; but on a nearer approach, they add greatly to its beauty and its interest. When the ship has arrived just at that point of distance from which a person may see all the broad outlines and apparent characteristics of an extensive scene, without being able to discern the minute details, the effect is magnificent. On the left hand is the Bulloon shore, low, but covered with luxurious and richly coloured bush, an occasional palm and pullom tree, rising in graceful form above the neighbouring mangroves:—in appearance it seems to embody the notions formed of fairy-land, but its realities most sadly illustrate the folly of such dreams. The middle ground also occurs on the left hand, and it gives a variety to the view. In front are the spacious river, extending farther than the eye can reach, and the north side of the peninsula, with its lofty mountains, and Freetown, running to the waVOL. XIII. NO. XXV.-JULY 1832.

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ter's edge, and surmounted by the barracks, and protected by a handsome fort, and a coast, forming small and convenient bays, from the town to its termination at the Cape, which runs boldly into the sea. On the right is the Atlantic. That a scene, composed of such ostensible material features, is grand and imposing, may readily be supposed; but those who are ignorant of the peculiarities of a tropical climate, and its seductive influence on a stranger, can form no adequate notion of the character and extent of its actual power. For the moment home is forgotten; or if remembered, the remembrance is accompanied with a desire it should be situated in such a seeming paradise. In thus speaking of the view on arriving at Sierra Leone, we are supposing the settlement to be made on a fine clear day, when the atmosphere is bright and comparatively devoid of malaria, and the river runs its natural course, unswollen, and free from discoloration. Should the arrival, however, happen at a different period, when the atmosphere is dense, oppressive, and fraught with deleterious exhalations, and the rains are deluging the face of the country, and at once augmenting the river, and destroying its beauty, then Sierra Leone presents a very different appearance; there is nothing to excite a pleasing anticipation, but there is a world of causes for apprehension and for dread. The realities of the scene are, of course, unaltered, for the two periods are the property of the climate, and must be alike endured by the colonists; but the appearances present a melancholy and fearful contrast."

2. Description of an African Tornado.-The seasons at Sierra Leone are divided into the wet and the dry. The latter is generally ushered in by the explosion of two or three tornados, which, although formidable in themselves, are still so long connected with the approach of a pleasant time, as that the inhabitants have sometimes prayed for their appearance. One of those strange commotions of nature is thus described by Mr Boyle:" A violent tornado appears to strangers a most appaling visitation, and produces an extraordinary effect upon their feelings. It consists of successive flashes of the most vivid lightning, tremendous shocks of thunder, rapidly and alarmingly reiterated, impetuous gusts of wind, deluging rain. This terrific combination of the elements sweeps along the whole of

the coast under consideration; but it occurs with peculiar force on what is called the windward coast, especially at Sierra Leone. Its denomination is derived from the Portugese, it being a corruption of the word trueno, which means thunder-storm. Its approach is first discernible by the appearance of a small clear silvery speck, at a high altitude in the heavenly expanse, which increases and descends towards the horizon, with a gradual and slow, but visible motion. In its descent it becomes circumscribed by a dark ring, which extends itself on every side, and as soon as the silvery cloud approaches the horizon, veils it in impenetrable gloom. At the moment the elements seem to have ceased their operations, and the very functions of nature to be paralysed; the atmosphere appears to be deprived of the spirit of vitality, and a sensation of approaching suffocation pervades and oppresses the physical system. The mind is wrapped in awe and suspense, but the latter is speedily relieved by the dark horizon being suddenly illuminated by one broad blaze of electric fluid; peals of distant thunder then break upon the ear, and rapidly approach, and increase in fervency and violence, till the shocks become appaling; when the thunder is at its loudest, a tremendous gust of wind rushes with incredible and often irresistible vehemence from the darkened part of the horizon, not rarely in its course carrying away roofs of houses and chimney-tops, blowing down or uprooting trees, and laying the stoutest and largest ships on their beam-ends, or sinking them under weigh or at anchor; and to that succeeds a furious deluge of rain, which falls in one vast sheet, rather than in drops, and concludes this terrible convulsion. The lightning is of the most vivid description, and, contrary to what has been reported of it, seldom sheet-lightning, but forked and piercing, and often extremely destructive, both to things animate and inanimate. Its apparently doubtful, wild course, is sometimes directed to a large and lofty tree, and the foliage, at the points of contact, is blasted on the instant, the exposed branches are severed from the trunk, and probably the enormous trunk itself is rent to its basis and destroyed. When it comes in contact with a house, it frequently leaves it as great a wreck as ships have been seen to be on coming out of a severe action, or after a destructive storm; and, occasionally, the building entered by it may happen to re

main untouched, and its inmates, some, or all of them, as the author has known to occur, perish under its scorching influence. Occasionally the spindle of a ship's mast, the most elevated part of it, may appear to be the point of attraction, and it will sometimes dart among the spars and cordage harmless, descending till it reach the deck, when it suddenly quits the vessel by some aperture, and rapidly returning through another, seems to have acquired a new character with incredible velocity; for, steering its strange and rapid course into the maindeck or hold, it will kill, maim, or injure every animate or inanimate with which it comes in contact. Much good has unquestionably been effected by conductors; but those who have watched the progress of the electric fluid, will hold the theorist in no estimation, who does not make the atmosphere the first and most important point of consideration. The heavy peals, or rather the terrifying shocks, of thunder which follow the lightning, frequently not only shake the buildings at Freetown, but the very foundations on which they stand; and the reverberations from the surrounding mountains increase, if possible, the awe excited by elementary commotion. The succeeding rain, or rather deluge, is happily of short duration, and rushing down the various inlets and indentations in the adjoining mountains, it forms into streams even a few minutes after its commencement, which sweeps through the streets of Freetown with astonishing velocity, bearing with them all the exposed vegetable and other matter, in a state of putridity or decay. Such is the tornado, and it is by the preponderating power of its gusts, and the atmospheric influence of lightning and its rains, that noxious exhalations from the earth, and deleterious miasmata, before confined to the neighbourhood of their origin by opposed or light currents of air in the day, or attracted by the land (the more lofty the more attractive) in the night, are removed, and consequently, the indescribably distressing feelings occasioned by a foul atmosphere, are superseded by those comparatively pleasurable and enlivening sensations which have been already noticed, pp. 40-42. The average time for the tornados to set in, is the termination of the month of September, from which time until Christmas, tolerably calm weather may be expected At Christmas, the periodical winds called the harmatan commence, and