A voyage to Guinea, Brasil and the West Indies

by John Atkins

I shall give two or three other Remarks on Trade-winds, proper, tho’ made at other Periods of the Voyage.

1. You must be distant from the Influence of Land to Windward, before the Trade blows true and fresh, (from this Coast we may suppose twenty or thirty Leagues) and then a Ship bound to America will make a constant and smooth Run of forty or fifty Leagues every twenty-four Hours. And as there are no Storms, vast numbers of flying Fish sporting near the Ship, (found every where within the Verge of these Winds, and no where else that ever I saw,) Bonetoes pursuing them; with Birds of various sorts, Garnets, Boobys, Tropick-Birds, and Sheerwaters, it makes a very delightful sailing.

2. Although the N. E. and S. E. Trade-Winds on this and that side the Line, do not blow adverse, yet by approaching to it, are in my Thoughts, the Occasion of becalming the Latitudes between 4 and 12° N, the Point of Contest; as we found, and will be hereafter remarked in our Passage from Brasil to the West-Indies, in July and August: and this I think, First, because the East southerly Trade is known ordinarily to extend E. S. E. to 4° of Northern Latitude: and consequently, as the East northerly is bounded a little nearer or further from the Equinoctial, as is the Station of the Sun; Calms and small Breezes, the Attendant of them, may vary a little, yet they will always happen about these Latitudes, and near the windward Shores be attended with Thunder, Lightning, and perpetual Rains. Secondly, all Ships actually find this in their Passage from Guinea to the West-Indies in any Month, or from England thither; the true Trade decreasing as they approach those Latitudes, and up between Cape Verd and the Islands, those Calms by all our Navigators are said to be as constantly attended with Rains and Thunder.

Thirdly, Because the same thing happens at the Commencement of the Trade, from the variable Winds in 27 or 28°° of Northern Latitude, sooner or later as I observed is the Station of the Sun: From all which I would infer, that from Guinea these calm Latitudes are easier passed, not nigh, but within 100 Leagues of the Continent of Africa, and at America not to get into them till a Ship has nigh run her Distance; for the Land, I think, either to Windward or Leeward does give a better Advantage to the Breezes, than nearer or more remote: Ships from England do not want this Caution so much, because the N. E. Trade does not fail till a little beyond the Parallel of Barbadoes, the Southermost of our Islands.

Land and Sea-Breezes are Gales of no great Extent, the former much fainter and inconstant will blow off an Island to a Roadsted, be on which side of it you will, but whether at the same time or no, or now here, now there, I am not experienced enough to say, tho’ their Weakness and Inconstancy makes either way defensible.—They are found at all shores within or near the Tropicks, the Sea-breeze coming in about ten in the morning, fresh and sweet, enlivening every thing. The Land-breeze when it does succeed, is at the same distance from Sun-set or later, small, sultry, and stinking, especially when from Rivers whose Banks are pestered with rotten Mangroves, stagnating Waters, &c.

They seem to arise entirely from the Heat of the Sun-beams: That the Air is more rarified by their Reflections on the solid Body of the Earth than on a fluid, is certain; therefore till their rarified Air, made so by three or four hours Sun, is brought to an Equilibrium, the Breezes must be from the Sea at all parts of the Coast, because at all parts, the same Cause is operating. And if this Rarefaction is limited by a determined heighth of the Atmosphere, the Sea-breezes that are to fill up the Vacuities will last a determined time only; two, three, or more hours: this is fact, but whether properly solved, must be submitted. Of affinity with this are the frequent Breezes we find with meridian Suns at shores, even to the Latitude of England, tho’ very still before and after. Again, the Land-breezes which succeed at night when the Sun has lost it’s Power, seem by their Weakness to be the return of Air heaped up by the preceding day’s Heat, like other Fluids when higher or fuller from any Cause (in one part than another) of course has it’s reflux to make an even Surface.

Tornadoes, by the Spaniard called Travadoes, are in no part of the World so frequent as at Guinea. They are fierce and violent Gusts of Wind that give warning for some hours by a gradual lowering and blackening of the Sky to Windward whence they come, accompanied with Darkness, terrible Shocks of Thunder and Lightning, and end in Rains and Calm. They are always off shore, between the N. and N. E. here, and more Easterly at the Bites of Benin, Calabar, and Cape Lopez; but although they are attended with this favourable Property of blowing from the shore, and last only three or four hours, yet Ships immediately at the appearance of them furl all their Sails and drive before the Wind.

We have sometimes met with these Tornadoes two in a day, often one; and to shew within what a narrow Compass their effects are, Ships have felt one, when others at ten Leagues distance have known nothing: Nay, at Anamaboo (3 or 4 Leagues off) they have had serene Weather while we have suffered under a Tornado in Cape Corso Road. And vice versa. A Proof of what Naturalists conjecture, that no Thunder is heard above 30 Miles; in these Storms it seems to be very near, one we felt the Afternoon of taking Roberts the Pyrate, that seemed like the ratling of 10000 small Arms within three yards of our Heads; it split our Maintop-Mast, and ended as usual in excessive Showers, and then calm; the nearness is judged by the Sound instantly following the Flash. Lightning is common here at other times, especially with the shutting in of Evening, and flashes perpendicularly as well as horizontally.

Both arise from a plenty of nitrous and sulphurous Exhalations that make a Compound like Gun-powder, set on fire in the Air; and if the Clouds that retain them be compact, and their heterogeneous Contents strong, various, and unequal, then like a Cannon in proportion to these, the disjection is with more or less Violence, producing Thunder, which as with a [32]Shot has frequently split the Masts of Ships; and strengthens the above Observation of their being discharged near hand; because if at any considerable distance, they would spread in the Explosion, and lose their Force. It furnishes also another, viz. That neither Thunder nor Lightning can be felt or heard far from shores; Winds may impel such Exhalations something, but at a hundred Leagues from any Land the Appearance must be rare and uncommon, because the matter of their Compound cannot be collected there.

Air-mattans, or Harmatans, are impetuous Gales of Wind from the Eastern Quarter about Midsummer and Christmas; they are attended with Fogs, last three or four hours, (seldom with Thunder or Lightning, as the Tornados) and cease with the Rain; are very dry, shriveling up Paper, Parchment, or Pannels of Escruitores like a Fire. They reach sometimes this Gold Coast, but are frequentest and in a manner peculiar to the Bite of Benin, named so some think from Aer Montain, respecting whence they come; or by others Mattan, the Negrish Word for a pair of Bellows, which they having seen, compare this Wind to.