_An Historical Account of the _Trade Winds_ and _Monsoons_, observable in the Seas between and near the _Tropicks_, with an attempt to assign the Physical Cause of the said Winds, by Mr. _Ed. Halley_._ An exact Relation of the constant and periodical Winds, observable in several Tracts of the Ocean, is a part of Natural History not less desireable and useful, than it is difficult to obtain, and its _Phænomena_ hard to explicate: I am not ignorant that several Writers have undertaken this Subject, and although _Varenius_ (_Lib. 1. Chap. 21. Geo. Gen._) seems to have endeavour'd after the best information from _Voyagers_, yet cannot his Accounts be admitted for accurate, by those that shall attentively consider and compare them together, and some of them are most evident Mistakes; which, as near as I can, I shall attempt to rectify, having had the opportunity of conversing with Navigators, acquainted with all parts of _India_, and having liv'd a considerable time between the _Tropicks_, and there made my own Remarks. The Substance of what I have collected is briefly as follows. The Universal _Ocean_ may most properly be divided into three Parts, _viz._ 1. The _Atlantick_ and _Æthiopick-Sea_. 2. The _Indian Ocean_. 3. The Great _South Sea_, or the _Pacifick Ocean_; and though these Seas do all communicate by the South, yet as to our present purpose of the _Trade Winds_, they are sufficiently separated by the interposition of great Tracts of _Land_; the first lying between _Africa_ and _America_, the second between _Africa_ and the _Indian Islands_, and _Hollandia Nova_; and the last between the _Phillipine Isles_, _China_, _Japan_ and _Hollandia Nova_ on the _West_, and the Coast of _America_ on the _East_. Now following this natural division of the Seas, so will we divide our History into three parts in the same order. I. In the _Atlantick_ and _Æthiopick_ Seas between the _Tropicks_, there is a general _Easterly Wind_ all the Year long, without any considerable Variation, excepting that it is subject to be deflected therefrom, some few Points of the Compass towards the _North_ or _South_, according to the Position of the place. The Observations which have been made of these Deflections, are the following. 1. That near the Coast of _Africa_, as soon as you have pass'd the _Canary Isles_, you are sure to meet a fresh Gale of _North East_ Wind, about the Latitude of 28 Degrees _North_, which seldom comes to the _Eastwards_ of the _East North-East_, or passes the _North North-East_. This Wind accompanies those bound to the Southward, to the Latitude of ten North, and about a hundred Leagues from the _Guinea_ Coast, where, till the fourth Degree of North Latitude, they fall into the Calms and Tornadoes; of which more hereafter.