rently; for the Tropics are distant from the Equator on both Sides twenty three Degrees and thirty Minutes; and the General Wind extends itself in one Meridian to the Latitude of twenty Degrees; in another to fifteen, in another to twelve. THUS in the Indian Ocean, when the Eaft or South-Eaft Wind blows, in the Month of January and February, 'tis not fenfible 'till you come to the fifteenth Degree of Latitude. SO in going from Goa to the Cape of Good-Hope, they have not the General Wind 'till they come to the twelfth Degree of South Latitude; which they have to the twenty-eighth Degree of the fame Latitude. LIKEWISE in the Sea between Africa and America, between the fourth Degree of North Latitude, and the tenth or eleventh Degree, Seamen have not observed the General Wind to blow; for when they have failed from St Helena beyond the Equator with that Wind, to the fourth Degree of North Latitude, then they have been without it 'till they came to the tenth Degree of North Latitude; from which to the thirtieth Degree the North-Eaft Wind is found to blow conftantly, tho' that thirtieth Degree is seven Degrees from the Torrid Zone; yet in the Parallel of fix, feven, or eight Degrees of Latitude, &c. it blows in fome Places, but in the tenth Degree in all Places 'till they come to the thirtieth. In the fame manner beyond the Tropic of Capricorn, between the Cape of Good-Hope and Brafil, the South-Eaft Wind blows to the thirtieth Degree thro' the whole Year. AND tho', as we faid, this Wind is not fenfible on all Shores, and much less in the inland Parts, yet on fome it is fenfible enough; thus on the Shores of Brafil, and on the Shores of the Kingdom of Lowango, in Africa, the South-Eaft Winds blow SECT. VI. daily, although other Winds are mixed with them. THERE is a threefold Caufe affigned by Naturalifts for this General Wind (for the Antients knew nothing of it, nor of the Torrid Zone itfelf). Some think the Sun's moving from Eaft to Weft is the Cause of it; because it rarifies the Air that it goes over; which Rarifaction follows the Sun, still thrufting the Air before it. OTHERS, viz. thofe who fuppofe the Heavens fixed, and the Earth to revolve, are of Opinion, that the General Wind comes from the Earth's moving from Weft to Eaft, and the Air with it, but not fo faft as we; and therefore that we go against the Air, or the Air against us, from Eaft to Weft. A third Cause is brought by des Cartes, which is altogether new; (Part 4. Prop. 49. of his Principles) where he endeavours to fhew that the Moon caufes this Motion of the Air as well as the Tides; but because the Knowledge of his Opinion requires alfo the Knowledge of his other Suppofitions, we shall not say any thing of it here; being afterwards to fhew that it cannot be fo. The first Caufe pleases us beft; and the fecond feems not to be received; because feveral of the Copernicans do not admit it; and no Reafon can be thus given why it fhould blow only within the Tropics, and not alfo beyond them (u). (u) Dr Halley, a Perfon well skilled in Meteorology, as well as in all parts of Phyfics, has, with extraordinary Accuracy, profecuted the Hiftory of the Conftant periodical Winds; which he deduces not only from the Obfervations of Seamen, but alfo from his own Expe PRO rience. But he only takes Notice of fuch Winds as blow in the Ocean; there being so much inconftancy and variableness in Land-Winds, that from them a Perfon can make out nothing clear or certain. First of all then, he divides the Ocean into three ample Seas PROPOSITION III. Some Winds have a stated Time and Period, others are unfixed, and blow at uncertain Times. THOSE are called Stated and Periodical Winds that blow at certain Times of the Year, and South; whofe violence they obferved perpetually to abate. Seas, viz. 1. The Atlantic. 2.The Indian; and, 3. The Pacific Sea; proceeding to defcribe in order, the Winds that generally blow in each of thefe. In the Atlantic Ocean, thro' the whole Year, blows the Eaft Wind; yet so as to turn a little South or North, according to the different Situation of Places. Of which Turnings this is the Sum. 1. Seamen near the African Shore, as foon as they have failed paft the Canary Islands, about twenty eight Degrees of North Latitude, obferve the Wind to blow pretty loud from South-Eaft. This Wind continues with them in their Course fouthward 'till they come at the tenth Degr. of North Latitude, provided they be an hundred or more Leagues from the Coaft of Guinea, between which Degree, and the 4th of North Latitude, there are interchangeably frequent Calms and Hurricanes. 2. They who fail to the Caribbee Islands, as they approach the Coast of America, perceive the North-Eaft Wind more and more to retire eastward, infomuch that fometimes it is full Eaft; fometimes alfo, tho' rarely, it may turn a little to the VOL. I. 3. As to the conftant Winds, they don't extend further than twenty eight Degrees North Latitude, to the Coast of Afri ca, and near the Border of America they go to thirty, thirty one, or thirty two Degrees. The fame is obfervable South of the Equator; where, near the Cape of Good-Hope, the Limits of these Winds are three or four Degrees further diftant from the Equinoctial Line, than on the Coafts of Brafil. 4.. From the fourth Degree of North Latitude to the abovementioned Bounds on the South Side of the Equator, the Wind is obferved almost perpetually to blow from the intermediate Parts 'twixt South and East, tho' for the most part 'twixt East and South-Eaft; yet fo, as that thofe who fail near the Coast of Africa have the Wind turning rather South, but proaching America they obferve it decline fo much to the eastward, that it almost blows direct Eaft. I had Occafion to tarry for the Space of a Year on this part of the Ocean, during which time the Changes of the Weather were Kk ap and ceafe for a fet Time, and then begin to blow again; fome of thefe are anniversary, others blow after fo frequent, that I had fufficient Employment in obferving thefe Matters. I found therefore the Wind almost always to poffels the third or fourth Point from the East. As oft as it approached nearer the Eaft, it blew more vehemently and raised a Storm; but when it came from the Points more fouthward, it was much more calm, and made the Air clear. But I never perceived a Wind blowing from Eaft to North, or from South to Weft. 5. Thefe Winds undergo fome Change, which is owing to the different Seafons of the Year. For when the Sun paffes the Equator northward a pretty way, this South-Eaft Wind, efpecially in this narrow Tract of Sea between Guinea and Brafil, declines fomewhat more to the South, as the NorthEaft does to Eaft. And again, upon the Sun's entering the Tropic of Capricorn, the SouthEaft Wind approaches nigher to Eaft, as doth the North-Eaft to North. 6. There is found a certain Tract of Sea in this Ocean, which, near the Coast of Guinea, extends for the Space of five hundred Leagues, from Mount Leo to St Thomas's life, wherein South, or South-Weft, Winds conftantly blow. For the South-Eat Wind having once paffed the Equator becomes conftant, which in our fourth Obfervation we demon ftrated to blow to the South of the Equator. About eighty or one hundred Leagues from the Coast of Guinea, it turns bydegrees fouthward, and having turned that Point, it declines to Points near the West, 'till touching the very Shore, it either obtains the South West Point, or that 'twixt it and direct Weft. Such kind of Winds on this Coaft are fix'd, tho' frequently interrupted with Calms and Tempefts, which violently proceed from any Air. Seamen alfo, much to their lofs, fometimes find the Winds easterly; which being attended with Clouds and a groffer Air, are very unwholefome. 7.'Twixt the tenth and fourth Degrees of North Lat. in that Tract which is bounded by the Meridians of Cape Verd, and the remote Iflands adjacent to it, I know not if I can fay that any Wind blows either conftant or variable. The Calm is almofi perpetual, the Thunder and Lightening extreamly terrible, and Rains fo very frequent, that from them the Tract is named rainy. If there happen any Winds they go off into Blafts, blowing with fuch inconftancy, that they don't continue for the Space of one. Hour, without Calms; and the Ships of the fame Fleet, which are all in Sight one of another, have each of them their proper Winds. On which Account failing is fo difficult in thefe Places, that after they have ceafed half a Year, and others return in a Month's time: and fome blow once a Day. that fometimes Ships with great difficulty fail thefe fix Degrees in whole Months. From the three foregoing Observations two things may be explained, which Mariners experience in failing betwixt Europe and India, or Gui nea. In the firft Place, that tho' this Sea, in that Part where it is narrowest between Guinea and Brafil, extends no less than five hundred Leagues, yet with great Difficulty Ships, fleering their Course fouthward, pass this Tract, especially in the Months July and August; which arifes hence, that during thefe Months the South Ealt Wind, blowing on the South of the Equator, paffes it's ordinary bounds four Degreees North Latitude; and further, turns fo far South, that fometimes 'tis carried ftrait from that Point, fometimes alfo from the intermediate Points betwixt it and the Weft. When therefore the Course mult be fleered against the Wind, if that be towards the South Weft Point, they have a Wind that turns more and more to Eaft, as they retire from the Continent of Africa; but the Dan ger is in paffing the Coaft of Brafil, where Quickfands are fo frequent, But if they go towards South-Eaft, they must of neceffity come near the Coaft of Guinea, from which they can't otherwife retire, than by failing towards the Eift as far as St Thomas's Island. 2. What all Ships loofing from Guinea to Europe, neceffarily do for the Reafon laid down in our Sixth Obfervation. For near the Shore blows the South-Weft Wind, with which they can neither fail, the land lying in the way, nor go fo against it, as to direct their Course northward to Europe. They fail then in a Courfe quite different from that intended, viz. either South, or to the Point next to South eastward. Following this Course they indeed retire from the Shore, but have the Wind more and more contrary, and are obliged to fteer ftill more to the Eaft, 'till they make the Ifland of St Thomas, and the Lopefian Cape; where finding a Wind declining from South to Eaft, fail wefterly with it 'till they come to the fourth Degree of South Latitude, where they find a South-eaft Wind blowing perpetually. On Account of these conftant Winds, all Mariners who fail to America, or Virginia, first steer fouthward, that by the Affiftance of this conftant EaftWind they may be carried weftward. For the fame Reafon, they who come from those Countries for Europe, directing their Course northward, endea vour, as foon as poffible, to come at the thirtieth Degreee of North Latitude. For here, first, they find the Winds variable; Kk 2 yet |