William Gilbert of Colchester, physician of London, On the magnet : magnetick bodies also, and on the great magnet the earth ; a new physiology, demonstrated by many arguments & experiments / William Gilbert.

  • Gilbert, William, 1544-1603.
Date:
1901
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Licence: In copyright

Credit: William Gilbert of Colchester, physician of London, On the magnet : magnetick bodies also, and on the great magnet the earth ; a new physiology, demonstrated by many arguments & experiments / William Gilbert. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    CHAP. VIII. On the Przeceffion of the ^Equinoxes, from the mag- netick motion of the poles of the Earth, in the Ardtick and AntarSlick circle of the Zodiack. RIMITIVE mathematicians, fince they did not pay attention to the inequalities of the years, made no diftindtion between the aequinodtial, or folftitial revolving year, and that which is taken from fome one of the fixed ftars. Even the Olympick years, which they ufed to reckon from the rifing of the dogftar, they thought to be the fame as thofe counted from the fol- ftice. Hipparchus of Rhodes was the firft to call attention to the fadt that thefe differ from each other, and difcovered that the year was longer when meafured by the fixed ftars than by the equinox or folftice: whence he fuppofed that there was in the fixed ftars alfo fome motion in a common fequence ; but very flow, and not at once perceptible. After him Menelaus, a Roman geometer, then Ptolemy, and long afterward Mahometes Aradtenfis, and feveral more, in all their literary memoirs, perceived that the fixed ftars and the whole firmament proceeded in an orderly fequence, regarding as they did the heaven, not the earth, and not under- ftanding the magnetical inclinations. But we fhall demonftrate that it proceeds rather from a certain rotatory motion of the Earth’s axis, than that that eighth fphere (fo called) the firmament, or non- moving empyrean, revolves ftudded with innumerable globes and ftars, whofe diftances from the Earth have never been proved by anyone, nor can be proved (the whole univerfe gliding, as it were). And furely it fhould feem much more likely that the appearances in the heavens fhould be clearly accounted for by a certain infledtion and inclination of the comparatively fmall body of the Earth, than by the fetting in motion of the whole fyftem of the univerfe ; especially if this motion is to be regarded as ordained folely for the Earth’s advantage: While for the fixed ftars, or for the planets, it is of no ufe at all. For by this motion the rifings and fettings of ftars in every Horizon, as well as their culminations at the height of the heavens, are fhifted fo much that the ftars which once were vertical are now fome degrees diftant from the zenith. For Nature has taken care, through the Earth’s foul or magnetick vigour, that, juft as it was needful in tempering, receiving, and warding off the fun’s rays and light, by fuitable feafons, that the points toward which the Earth’s pole is diredted fhould be 23 degrees and more from