Chap. 2. The Magnetick axis of the Earth persists invariable. Chap. 3. On the magnetick diurnal revolution of the Earth's globe, as a probable assertion against the time-honoured opinion of a Primum Mobile. Chap. 4. That the Earth moves circularly. Chap. 5. Arguments of those denying the Earth's motion, and their confutation. Chap. 6. On the cause of the definite time of an entire rotation of the Earth. Chap. 7. On the primary magnetick nature of the Earth, whereby its poles are parted from the poles of the Ecliptick. Chap. 8. On the Præcession of the Æquinoxes, from the magnetick motion of the poles of the Earth, in the Arctick & Antarctick circle of the Zodiack. Chap. 9. On the anomaly of the Præcession of the Æquinoxes, & of the obliquity of the Zodiack. [Illustration] * * * * * {1} [Illustration] WILLIAM GILBERT ON THE LOADSTONE, BK. I. _CHAP. I._ ANCIENT AND MODERN WRITINGS on the Loadstone, with certain matters of mention only, _various opinions, & vanities_. At an early period, while philosophy lay as yet rude and uncultivated in the mists of error and ignorance, few were the virtues and properties of things that were known and clearly perceived: there was a bristling forest of plants and herbs, things metallick were hidden, and the knowledge of stones was unheeded. But no sooner had the talents and toils of many brought to light certain commodities necessary for the use and safety of men, and handed them on to others (while at the same time reason and experience had added a larger hope), than a thorough examination began to be made of forests and fields, hills and heights; of seas too, and the depths of the waters, of the bowels of the earth's body; and all things began to be looked into. And at length by good luck the magnet-stone was discovered in iron lodes, probably by smelters of iron or diggers of metals. This, on being handled by metal folk, quickly displayed that powerful and strong attraction for iron, a virtue not latent and obscure, but easily proved by all, and highly praised and commended. And in after time when it had emerged, as it were out of darkness and deep dungeons, and had become dignified of men on account of its strong and amazing attraction for iron, many philosophers as well as physicians of ancient days discoursed of it, in short celebrated, as it were, its memory only; as for instance Plato in the _Io_[2], Aristotle in the _De Anima_[3], in Book I. only, Theophrastus the Lesbian, Dioscorides, C. Plinius Secundus, and Julius Solinus[4]. As handed down by them the loadstone merely attracted iron, the rest of its virtues were all undiscovered. But that the story of the {2} loadstone might not appear too bare and too brief, to this singular and sole known quality there were added certain figments and falsehoods, which in the earliest times, no less than nowadays, used to be put forth by raw smatterers and copyists to be swallowed of men. As for instance, that