Experimental philosophy, in three books containing new experiments microscopical, mercurial, magnetical : with some deductions, and probable hypotheses, raised from them, in avouchment and illustration of the now famous atomical hypothesis / by Henry Power ...

CHAP. VI.

ANd now we come to his Second great Invention, with which he thunders against the Copernicans, and that is his great Magnetical Experiment to avouch the Earth's Immobability.

To this Experiment therefore drawn from the per∣pendicular position of the Magnet, we answer, That the reason why the Terrella does wheel about, and direct certain parts of its Aequator, to certain and determinate points of the Horizon, is, Because it is overpower'd by the Magnetical Effluxions of the Earth; which, as a greater Magnet, does violently reduce it to that Situati∣on, which probably is the same that those Aequatorial parts had in their Mineral Beds: And therefore this great Argument against the Dinetical Motion of the Earth, is no Argument at all, unless that he could prove to us that the Terrella could play this trick; it were remo∣ved out of the sphaere of the Earth's Magnetisme, which is beyond his Philosophy ever to demonstrate.

2. Again, If this Motion of the Magnet did proceed from an Intrinsecal Tendency that it has of its own, to bring all its parts to their right and determinate points, there to remain in a perfect Stability, then would those parts constantly affect this (and no other) Situation, howsoever the Loadstone was posited (provided it be at Liberty to move it self to its desired position.) But this is false; For, in Grandamicus his Experiment, if you in∣vert the Poles of the Magnet, and set the North-Pole in the Zenith, and the South in the Nadir, you shall see the Stone to Counterchange its Situation, and those aequa∣torial

parts of the Magnet, which before respected the East, shall now wheel about, and fix themselves in the West; and the Northern parts turn to the South: which shews, That the Stone does not Tack about from an in∣trinsecal principle and form of its own, but is turned by the extrinsecal Effluxions of the whole Earth; or rather by the stream of those Magnetical Atoms, that strike not onely through the Axis of the Earth, but also through the Body of every petty Loadstone, accordingly as they are best received by the Grain or Bait of the said Stone.

And now I am engaged in this Magnetick Discourse, I must tell you that I think our famous Gilbert has drawn a more prevalent Argument from this Magnetical Philo∣sophy, to prove the Earth's Motion by, than Grandami∣cus has done to destroy it; for since it is demonstrated of late, that all the whole Earth is nothing but a great and Globular Loadstone, and that all the Circles of the Armillary Sphaere, are really, truly, and naturally inhae∣rent in the Earth, by virtue of the transcurrent Atoms, How can we conclude otherwise but with Gilbert? Quis in posterum eum de facto moveri dubitabit, quum ei omnia ad motum planè requisita, dedit natura; i. e. figuram rotundam, pendulam in medio Fluido positionem, & omnes terminos motui Circulari inservientes, polos nempè, aequatorem, meridianos & polares circulos, & parallelos?

Lastly, As for his Universal Meridian, it is likewise de∣duced from his Anti-Copernican Experiment of the Loadstone swimming in a Boat, with its Poles vertically erected: For (saith he,) Since the Stone being Horizon∣tally-placed, does not shew the true Meridian, but with an Angle of Variation, in most, if not in all places of the Earth, if you set it with its Axis perpendicular as before, it will (after some undulations to and fro) rest quietly,

with certain parts facing the Meridian; which points must be exactly marked, and through them a Circle drawn round about the Stone; by help of which, you may strike a true Meridian-Line, when and where you please.

Now, though we grant this Experiment to be true, and, probably, to hold good in all Longitudes and Lati∣tudes; yet he that shall perpend▪ how many ticklish Curi∣osities, and nice Circumstances there are to perform this Experiment exactly, will find the Invention only plea∣sing in the Theory, but not in the Practice: For, 1. It is very difficult to place the Terrella in an exact perpendi∣cular; 2. When 'tis so, 'tis as difficult to keep it invaria∣ble under the same Zenith; 3. Most difficult to draw an exact Meridian-Line from it: Not to mention how hard a thing it is; first, to find the two Polary points in a Globe-Loadstone; also to keep the Boat in a Fluctua∣tion, parallel to the Horizon.