_B._ I forgot it. It is in the motion of the magnetic poles. For precedently (p. 7), he had said “that their period or revolution was six hundred years; their yearly motion thirty-six minutes; and (p. 8) that their motion is by sixes. Six tenths of a degree in one year; six degrees in ten years; sixty degrees in a hundred years; and six times sixty degrees in six hundred years.” _A._ But what natural cause doth he assign of this revolution of six hundred years? _B._ None at all. For the magnet lying upon the earth, can have no motion at all but what the earth and the air give it. And because it is always at 8 deg. 30 min. distance from the pole of the earth, the earth can give it no other motion than what it gives to its own poles by the precession of the equinoctial points. Nor can the air give it any motion but by its stream; which must needs vary when the stream varieth. But what a vast difference does he make between the period of the motion of the equinoctial points, which is about or near thirty-six thousand years according to Copernicus (lib. iii. cap. 6), which makes the annual precession to be 36 seconds, and the period of the magnetical poles’ motion, which is but six hundred years. _A_. Go on. _B_. He comes now (p. 15) to the inclinatory needle upon a spherical loadstone. Where he shows, by diagram, that the needle and the instrument together moved towards the magnetical pole, make the sum of the inclinations equal to two quadrants, setting the north-point of the needle southward: which I confess is true. But, in the same page, he ascribeth the same motion to the earth in these words: “as the horizontal needle hath a double motion about the round loadstone or terrella, so also the inclinatory needle hath a double motion about the earth.” What is this, but a confession that the poles of the magnet and of the earth are the same? _A._ It is plain enough. _B._ Besides, seeing he placeth the magnetical pole at M in the meridian of Vaygates, the needle being touched shall incline to the pole of the earth which is P, as well there as at London, and make the north-pole of the earth point south. _A._ It is certain, because he puts both the magnetical pole and the pole of the earth in the same meridian of the earth. Nor see I any cause why, the needle being the same, it should not be as subject to variation, and to variation of variation, and to all accidents of the earth there, as in any other part. _B._ He putteth (p. 16) a question, “at what distance from the earth are the magnetic poles? and answers to it, they are very near the earth, because the nearer the earth, the greater the strength.” What think you of this? _A._ I think they are in the superficies of the magnet, as the pole of the earth is in the superficies of the earth. And consequently, that then the earth must be a part of the magnet, and their poles the same. For the body of the magnet and the body of the earth, if they be two, cannot be in one place.