mist of the idle and feeble philosophizers, by means of endless experiments skilfully applied to it; yet without neglecting anything which has been handed down in the writings of any of the ancients or of the moderns, all which you did diligently peruse and perpend. Do not fear the boldness or the prejudice of any supercilious and base philosophaster, who by either enviously calumniating or stealthily arrogating to himself the investigations of others seeks to snatch a most empty glory. Verily

but

May your new physiology of the Magnet, I say (kept back for so many years), come forth now at length into the view of all, and your Philosophy, never to be enough admired, concerning the great Magnet (that is, the earth); for, believe me

these books of yours on the Magnet will avail more for perpetuating the memory of your name than the monument of any great Magnate placed upon your tomb.

Interpretation of certain words.^[1]

Terrella, a globular loadstone.

Verticity, polar vigour, not περιδίνησις but περιδίνεισιος δύναμις: not a vertex or πόλος but a turning tendency.

Electricks, things which attract in the same manner as amber.

Excited Magnetick, that which has acquired powers from the loadstone.

Magnetick Versorium, a piece of iron upon a pin, excited by a loadstone.

Non-magnetick Versorium, a versorium of any metal, serving for electrical experiments.

Capped loadstone, which is furnished with an iron cap, or snout.

Meridionally, that is, along the projection of the meridian.

Paralleletically, that is, along the projection of a parallel.

Cusp, tip of a versorium excited by the loadstone.

Cross, sometimes used of the end that has not been touched and excited by a loadstone, though in many instruments both ends are excited by the appropriate termini of the stone.

Cork, that is, bark of the cork-oak.

Radius of the Orbe of the Loadstone, is a straight line drawn from the summit of the orbe of the loadstone, by the shortest way, to the surface of the body, which, continued, will pass through the centre of the loadstone.

Orbe of Virtue, is all that space through which the Virtue of any loadstone extends.

Orbe of Coition, is all that space through which the smallest magnetick is moved by the loadstone.

Proof, for a demonstration shown by means of a body.

Magnetick Coition: since in magnetick bodies, motion does not occur by an attractive faculty, but by a concourse or concordance of both, not as if there were an ἑλκτικὴ δύναμις of one only, but a συνδρομή of both; there is always a coition of the vigour: and even of the body if its mass should not obstruct.

Declinatorium, a piece of Iron capable of turning about an axis, excited by a loadstone, in a declination instrument.

I N D E X O F C H A P T E R S.

Book 1.

Chap. 1. Ancient and modern writings on the Loadstone, with certain matters of mention only, various opinions, & vanities.

Chap. 2. Magnet Stone, of what kind it is, and its discovery.

Chap. 3. The loadstone has parts distinct in their natural power, & poles conspicuous for their property.

Chap. 4. Which pole of the stone is the Boreal: and how it is distinguished from the austral.

Chap. 5. Loadstone seems to attract loadstone when in natural position: but repels it when in a contrary one, and brings it back to order.

Chap. 6. Loadstone attracts the ore of iron, as well as iron proper, smelted & wrought.

Chap. 7. What iron is, and of what substance, and its uses.

Chap. 8. In what countries and districts iron originates.

Chap. 9. Iron ore attracts iron ore.

Chap. 10. Iron ore has poles, and acquires them, and settles itself toward the poles of the universe.

Chap. 11. Wrought iron, not excited by a loadstone, draws iron.

Chap. 12. A long piece of Iron (even though not excited by a loadstone) settles itself toward North & South.

Chap. 13. Wrought iron has in itself certain parts Boreal & Austral: a magnetick vigour, verticity, and determinate vertices or poles.

Chap. 14. Concerning other powers of loadstone, & its medicinal properties.

Chap. 15. The medicinal virtue of iron.

Chap. 16. That loadstone & iron ore are the same, but iron an extract from both, as other metals are from