In the foregoing History are contained several Problems, that merit well the Consideration of our acutest Naturalists, both by reason of the constancy of the Effect, and of the immense Extent thereof; near half the Surface of the Globe being concerned. The chief of these Problems are, 1. Why these Winds are perpetually from the East in the _Atlantic_ and _Æthiopick_; as likewise in the _Pacifick_ Ocean, between the Latitudes of 30 North and South? 2. Why the said Winds extend no farther with constancy than to the Latitude of 30 Degrees? 3. Why there should be a constant South-Westerly Wind upon and near the Coast of _Guinea_? 4. Why in the North part of the _Indian_ Ocean, the Winds, which for one half Year do agree with those of the other two Oceans, should change in other half Year, and blow from the opposite Points; whilst the Southern part of that Ocean follows the General Rule, and has perpetual Winds about S. E? 5. Why in these General Trade-Winds it should be always true, that to the Northward of the _Æquator_ it is inclin'd to the Northwards of the East; and in South Latitudes, to the Southward thereof? 6. Why in these Seas of _China_ there should be so great an Inclination from the East to the North, more than elsewhere? with many more, which it would be much easier to propose than answer. But lest I should seem to propose to others, Difficulties which I have not thought worth my own Time and Pains, take here the result of an earnest Endeavour after the true reason of the aforesaid _Phænomena_; wherein if I am not able to account for all Particulars, yet 'tis hoped the Thoughts I have spent thereon, will not be judged wholly lost, by the Curious in Natural Enquiries. Wind is most properly defined to be the Stream or Current of the Air, and where such a Current is perpetual and fixt in its Course, 'tis necessary that it proceed from a permanent un-intermitting Cause. Wherefore some have been inclin'd to propose the diurnal _Rotation_ of the Earth upon its _Axis_, by which, as the _Globe_ turns Eastwards, the loose and _fluid_ Particles of the Air, being so exceeding light as they be, are left behind, so that in respect of the Earths _Surface_ they move Westwards, and become a constant Easterly Wind. This Opinion seems confirm'd, for that these Winds are found only near the _Æquinoctial_, in those Parallels of Latitude where the diurnal Motion is swiftest; and I should readily assent to it, if the constant Calms in the _Atlantick_ Sea, near the _Æquator_, the Westerly Winds near the Coast of _Guinea_; and the _Periodical_ Westerly _Monsoons_ under the _Æquator_ in the _Indian_ Seas, did not declare the insufficency of that _Hypothesis_. Besides the Air being kept to the Earth by the Principle of _Gravity_, would acquire the same degree of _Velocity_ that the Earths _Surface_ moves with, as well in respect of the diurnal _Rotation_, as of the Annual about the Sun, which is about thirty times swifter.