The John Adams, after a short stay at Loanda, again appeared off Ambriz, and resumed her cruising. The Perry’s provisions had now become nearly exhausted; and she was ordered by the John Adams to proceed to the north coast with dispatches to the commodore.
The land along the southern African coast, from lat. 7° south, extending to Benguela, and even to the Cape of Good Hope, is more elevated than the coast to the northward towards the equator. Long ranges of high bluff may be seen, extending, in some cases, from twenty to thirty miles. A short distance to leeward, or north, of Ambriz, is a remarkable range of hills, with heavy blocks of granite around them, resembling, at a distance, a small village. The “granite pillar,” which shoots up in the air, towering above the surrounding blocks like a church-spire, is a good landmark to the cruisers off Ambriz. They often find themselves at daylight, after beating, during the night, to the southward, drifted down abreast of it by the northerly current.
The natives along this coast, unlike those of northern Guinea, who are bold, energetic and effective, comparatively, when muscular force is required, are marked by very opposite traits; softness, pliancy and flexibility, distinguish their moral and mental character. They are mostly below the middle stature, living in villages, in rude, rush-thatched huts; subsisting principally upon fish, and the plantain, which is the African bread-fruit tree.
These people present some of the lowest forms of humanity.
The temperature of both the air and water within southern intertropical Africa, averages, during the months of August and September, 72°, and off Benguela, on one occasion, early in July, the air temperature was as low as 60°, while in the month of February, the thermometer seldom reaches a higher point than 82°.
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.