The Rhode Island American, And General Advertiser

FROM AFRICA.

Captain Hallowell, of the brig Richard, recently arrived at this port, from the coast of Africa, informs that he witnessed, while at Sierra Leone, one of those tornadoes to which the African Coast is exposed, for nearly six months in the year. Their violence and the frequency of their occurrence are determined by the state of the atmosphere. Ten or twelve of them are generally experienced at Sierra Leone, in the course of a year.

The precursors and characteristics of these tornadoes are worthy of philosophical investigation. The sky is clear—a perfect calm has prevailed for several hours—and the air becomes oppressive; when, suddenly in the most elevated region of the atmosphere appears, as the indication of a tornado, a little round, white cloud—not exceeding 5 or 6 feet in diameter, and which seems to be perfectly motionless.

The air becomes gradually agitated and acquires a circular motion. The leaves and plants, with which the land is always covered, raised by the force of the air several feet from their bed, keep incessantly revolving around the same spot, to the infinite diversion of the natives, who amuse themselves with this rotary motion.

The little cloud, which portended the approach of the tornado, having increased in size, insensibly descends to the lower region of the visible horizon. The whirlwind now increases in violence—and soon becomes terrific. Vessels are obliged to double their moorings—they often part their cables, and are driven foul of each other. Many negro huts are swept away, trees are torn up by the roots, and wherever these whirlwinds exert their full force, they leave deplorable traces of their progress.

These terrible agents of desolation happily continue for only 20 or 30 minutes, and terminate in a heavy rain.