Page:Philosophical Transactions - Volume 029.djvu/435

 to the Figures in which the Circulation is performed. Thus in Fig. II. Let ABCD be a Terrella, and its Poles A the South, and B the North; and by doing as preſcribed, it will be found that the Filings will lie in a Right Line perpendicular to the Surface of the Ball, when in the Line of the Magnetical Axis continued. But for about forty five Degrees on either ſide, from B to G or I, and from A to H or K, they will form themſelves into Curves, more and more crooked as they are remoter from the Poles; aad withall more and more oblique to the Surface of the Stone: as our Figure truly repreſents, and as may readily be ſhewn by the Terrella and Apparatus for that Purpoſe in the Repoſitory of the Royal Society Hence it may appear how this exceeding ſubtile Matter revolves; and particularly how it permeates the Magnet with more force and in greater Quantity in the circumpolar Parts, entring into it on the one ſide, and emerging from it on the other, under the ſame oblique Angles: whilſt in the middie Zone about C and D, near the Magnet’s Equator (if I may uſe the Word) very few if any of theſe Particles do impinge. and thoſe very obliquely.

Now by many and very evident Arguments it appears that our Globe of Earth is no other than one great Magnet, or (if | may be allowed to alledge an Invention of my own) rather two; the one including the other as the Shell includes the Kernel (for ſo and not otherwiſe we may explain the changes of the Variation of the Magnetical Needle) but to our preſent Purpoſe the Reſult is the ſame. it ſuffices that we may ſuppoſe the ſame ſort of Circulation of ſuch an exceeding fine Matter to be perpetually performed in the Earth, as we obſerve in the Terella; which ſubtile Matter freely pervading the Pores of the Earth, and entring into it near its Southern Pole, may paſs out again in to the Ether, at the ſame Diſtance from the Northern, and with a like Force; its Direction being