famous from all Antiquity. Besides, against both Des Cartes and Gilbert, the change of the Variation, which has been within these Hundred Years last past more than 15 gr. at London, is an entire Demonstration; tho' Des Cartes does not stick to say, that the transportation of Iron from place to place, and the growth of new Iron within the Earth, where there was none before, may be the cause thereof. The same holds likewise against the Hypothesis of Magnetical Fibres, which Kircher maintains.
Now to propose something that may answer the several appearances, and introduce nothing strange in Philosophy, after a great many close Thoughts, I can come to no other Conclusion than that, The whole Globe of the Earth is one great Magnet, having four Magnetical Poles, or Points of Attraction, near each Pole of the Equator. Two; and that, in those parts of the World which lie near adjacent to any one of those Magnetical Poles, the Needle is govern'd thereby, the nearest Pole being always predominant over the more remote . The parts of the Earth wherein these Magnetical Poles lie, cannot as yet be exactly determin'd for want of sufficient Data to proceed Geometrically; but, as near as Conjecture can reach, I reckon that the Pole , which is at present nearest to us, lies in or near the Meridian of the Lands-end of England , and not above seven Degrees from the Pole Arctick; by this Pole the Variations in all Europe and Tartary , and the North Sea are principally govern'd, though with regard to the other Northern Pole, whose situation is in a Meridian passing about the middle of California , and about 15 gr. from the North Pole of the World; to this the Needle has chiefly respect in all the North America , and in the two Oceans on either side thereof, from the Azores Westward to Japan , and farther. The two Southern Poles are rather farther distant from the South Pole