It is known that the southeast trade-winds prevail in the Atlantic ocean, between the African and American continents, south of the equator to the tropic of Capricorn, and the northeast trade to the southward of the tropic of Cancer. It is of course generally understood, that the sun heats the equatorial regions to a higher temperature than is found anywhere else, and that the air over these regions is consequently expanded and rendered lighter than that which envelops the regions at a distance. This causes the whole mantle of air round the earth, for a short distance near the equator, to be displaced and thrown upwards (like the draft of a chimney), by the cooler and heavier air rushing in, in steadfast and continuous streams, from the north and south. The earth’s revolution carries every thing on its surface somewhat against these air-currents in their progress, so that they appear to sweep aslant along the earth and sea, coming from northeast and southeast. In consequence of the greater amount of heated land being in the northern hemisphere, its peculiar wind, or the northeast trade, is narrower; while the other, the southeast trade, blowing from the greater expanse of the Southern Ocean, is broader. The latter, therefore, sometimes extends considerably beyond, or north of the equinoctial line. Thus the winds over all the Gulf of Guinea are generally from the south. The coast of Africa, both north and south of the equator, greatly modifies the force and direction of the winds. On the southern coast the wind blows lightly, in a sea-breeze from the southwest. But at the distance of one hundred miles from the land, it begins gradually to veer round, as it connects itself with the S. E. trades. A line drawn on the chart, from the southern tropic, in 5° east to the lat. of 5° south, may be regarded as the eastern boundary of the southeast trade-winds. Hence a vessel, as in the case of the Perry, on her first passage to the southern coast, when in 10° south and 20° west, on going about and standing for the African coast by the wind, although she at first will not be able to head higher than N. E., will gradually come up to the eastward as the wind veers to the southward; until it gradually hauls as far as S. W., and even W. S. W.--enabling her to fetch Benguela in 12° 34´ south lat., although on going about she headed no higher than Prince’s Island in 1° 20´ north lat. On the entire intertropical coast of Africa, it may be said that there are but two seasons, the rainy season and the dry season. On the southern coast, the rainy season commences in November, and continues until April, although the rains are neither as frequent nor as heavy as on the northern coast, where they commence in May and continue through the month of November. The months of March and April are the most unhealthy seasons on the southern coast, arising probably from the exhalations of the earth, which are not dispelled by the light sea-breezes prevailing at this period.