(529)
Yet know, that Gilbert, though the first, that has writ rationally of the Magnet, and began to say no follies of it, writes about the end of this Book (yet without being positive) that if a Magnet altogether round were placed on a Meridian, and its Poles so posited, as to answer to the Poles of the World, and consequently it Axis to the Axis the World, the Stone would continually of its self turn round in 24 hours. Whence he inferrs, that the whole Earth, as a great Magnet, turns also round about its Axis in the same space of time.
To explore the truth of this Proposition (which I wish were true; since then we should have a perpetual motion without Wheels, and a Watch yet juster than Pendulums) I found the means of causing two Magnets to be turn'd with the powder of Emery; the one whereof having been made Spherical with all possible exactness, became very solid, plain, and without any visible pores, or diversity of matter, being 1½ inch in diameter: the other, bigger, of 3½ inches diameter, but of less vigour, porous also and uneven; which made me lay it aside as useless for this Experiment, because, though it had been perfectly spherical, as the lesser, I could not be assured, that its Center of Magnitude was the same with those of its Gravity, and Strength; which was requisite to make good Gilberts Proposition.
But for the other smaller Magnet, that had no defect, and its three Centers were the same, with so much justness, that after I had exactly found the two Poles of this Stone, I caused two small holes to be made therein, to support it by two points of Needles, as by two pivots: which having put in a Meridian of Brass, and suspended the Ball betwixt them like a little Globe, it was so easily moveable that I made it turn every way with a blast only of my mouth, and it stopp'd indifferently, now in one, then in another place, not any side of it prevailing by its gravity, nor descending, as it would have done, if any of them had been heavier than another.
This Stone thus prepared without any defect in virtue or figure, uniform, homogeneous, equilibrated, being adjusted on its Meridian and a Horizon, so placed on its Meridian-line, that the Poles thereof answer'd to the Poles of the Heavens (as hath been said already;) the success was, that it had not any Motion,
and
