VVILLIAM 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.

LONDON

IMPRINTED at the Chiswick Press ANNO

MCM.

PREFACE TO THE CANDID
READER, STUDIOUS OF
THE MAGNETICK
PHILOSOPHY.

TO THE MOST EMINENT AND LEARNED MAN

Dr. William Gilbert,

a distinguished Doctor of Medicine amongst the

Londoners, and Father of Magnetick Philosophy,

an Encomiastic Preface of Edward Wright

on the subject of these books

Magnetical.

It seems, however, that there has been some inconvenience and hindrance connected with the observation of this variation; because it cannot be observed excepting when the sun or the stars are shining. Accordingly this magnetick Mercury of the sea goes on still further to bless all shipmasters, being much to be preferred to Neptune himself, and to all the sea-gods and goddesses; not only does it show the direction in a dark night and in thick weather, but it also seems to exhibit the most certain indications of the latitude. For an iron index, suspended on its axis (like a pair of scales), with the most delicate workmanship so as to balance in æquilibrio, and then touched and excited by a loadstone, dips to some fixed and definite point beneath the horizon (in our latitude in London, for example, to about the seventy-second degree), at which it at length comes to rest. But under the æquator itself, from that admirable agreement and congruency which, in almost all and singular magnetical experiments, exists between the earth itself and a terrella (that is, a globular loadstone), it seems exceedingly likely (to say the very least), and indeed more than probable, that the same index (again stroked with a loadstone) will remain in æquilibrio in an horizontal position. Whence it is evident that this also is very probable, that in an exceedingly small progress from the South toward the North (or contrariwise) there will be at least a sufficiently perceptible change in that declination; so that from that declination in any place being once carefully observed along with the latitude, the same place and the same latitude may be very easily recognized afterward, even in the darkest night and in the thickest mist by a declination instrument. Wherefore to bring our oration at length back to you, most eminent and learned Dr. Gilbert (whom I gladly recognize as my teacher in this magnetick philosophy), if these books of yours on the Magnet had contained nothing else, excepting only this finding of latitude from magnetick declination, by you now first brought to light, our shipmasters, Britains, French, Belgians, and Danes, trying to enter the British Channel or the Straits of Gibraltar from the Atlantick Ocean in dark weather, would still most deservedly judge them to be valued at no small sum of gold. But that discovery of yours about the whole globe of the earth being magnetical, although perchance it will seem to many "most paradoxical," producing even a feeling of astonishment, has yet been so firmly defended by you at all points and confirmed by so many experiments so apposite and appropriate to the matter in hand, in Bk. 2, chap. 34; Bk. 3, chap. 4 and 12; and in almost the whole of the fifth book, that no room is left for doubt or contradiction. I come therefore to the cause of the magnetick variation, which hitherto has distracted the minds of all the learned; for which no mortal has ever adduced a more probable reason than that which has now been set forth by you for the first time in these books of yours on the Magnet. The ὀρθοβορεοδείξις of the index magnetical in the middle of the ocean, and in the middle of continents (or at least in the middle of their stronger and more lofty parts), its inclining near the shore toward those same parts, even by sea and by land, agreeing with the experiments Bk. 4, chap. 2, on an actual terrella (made after the likeness of the terrestrial globe, uneven, and rising up in certain parts, either weak or wanting in firmness, or imperfect in some other way),—this inclination having been proved, very certainly demonstrates the probability that that variation is nought else than a certain deviation of the magnetick needle toward those parts of the earth that are more vigorous and more prominent. Whence the reason is readily established of that irregularity which is often perceived in the magnetick variations, arising from the inæquality and irregularity of those eminences and of the terrestrial forces. Nor of a surety have I any doubt, that all those even who have either imagined or admitted points attractive or points respective in the sky or the earth, and those who have imagined magnetick mountains, or rocks, or poles, will immediately begin to waver as soon as they have perused these books of yours on the Magnet, and willingly will march with your opinion. Finally, as to the views which you discuss in regard to the circular motion of the earth and of the terrestrial poles, although to some perhaps they will seem most supposititious, yet I do not see why they should not gain some favour, even among the very men who do not recognize a sphærical motion of the earth; since not even they can easily clear themselves from many difficulties, which necessarily follow from the daily motion of the

whole sky. For in the first place it is against reason that that should be effected by many causes, which can be effected by fewer; and it is against reason that the whole sky and all the sphæres (if there be any) of the stars, both of the planets and the fixed stars, should be turned round for the sake of a daily motion which can be explained by the mere daily rotation of the earth. Then whether will it seem more probable, that the æquator of the terrestrial globe in a single second (that is, in about the time in which any one walking quickly will be able to advance only a single pace) can accomplish a quarter of a British mile (of which sixty equal one degree of a great circle on the earth), or that the æquator of the primum mobile in the same time should traverse five thousand miles with celerity ineffable; and in the twinkling of an eye should fly through about five hundred British miles, swifter than the wings of lightning, if indeed they maintain the truth who especially assail the motion of the earth). Finally, will it be more likely to allow some motion to this very tiny terrestrial globe; or to build up with mad endeavour above the eighth of the fixed sphæres those three huge sphæres, the ninth (I mean), the tenth, and the eleventh, marked by not a single star, especially since it is plain from these books on the magnet, from a comparison of the earth and the terrella, that a circular motion is not so alien to the nature of the earth as is commonly supposed. Nor do those things which are adduced from the sacred Scriptures seem to be specially adverse to the doctrine of the mobility of the earth; nor does it seem to have been the intention of Moses or of the Prophets to promulgate any mathematical or physical niceties, but to adapt themselves to the understanding of the common people and their manner of speech, just as nurses are accustomed to adapt themselves to infants, and not to go into every unnecessary detail. Thus in Gen. i. v. 16, and Psal. 136, the moon is called a great light, because it appears so to us, though it it is agreed nevertheless by those skilled in astronomy that many of the stars, both of the fixed and wandering stars, are much greater. Therefore neither do I think that any solid conclusion can be drawn against the earth's mobility from Psal. 104, v. 5; although God is said to have laid the foundations of the earth that it should not be removed for ever; for the earth will be able to remain evermore in its own and self-same place, so as not to be moved by any wandering motion, nor carried away from its seat (wherein it was first placed by the Divine artificer). We, therefore, with devout mind acknowledging and adoring the inscrutable wisdom of the triune Divinity (having more diligently investigated and observed his admirable work in the magnetical motions), induced by philosophical experiments and reasonings not a few, do deem it to be probable enough that the earth, though resting on its centre as on an immovable base and foundation, nevertheless is borne around circularly.

But passing over these matters (concerning which I believe no one has ever demonstrated anything with greater certainty), without any doubt those matters which you have discussed concerning the causes of the variation and of the magnetick dip below the horizon, not to mention many other matters, which it would take too long to speak of here, will gain very great favour amongst all intelligent men, and especially (to speak after the manner of the Chemists) amongst the sons of the magnetick doctrine. Nor indeed do I doubt that when you have published these books of yours on the Magnet, you will excite all the diligent and industrious shipmasters to take no less care in observing the magnetick declination beneath the horizon than the variation. Since (if not certain) it is at least probable, that the latitude itself, or rather the effect of the latitude, can be found (even in very dark weather) much more accurately from that declination alone, than can either the longitude or the effect of the longitude from the variation, though the sun itself is shining brightly or all the stars are visible, with the most skilful employment likewise of all the most exact instruments. Nor is there any doubt but that those most learned men, Peter Plancius (not more deeply versed in Geography than in observations magnetical), and Simon Stevinus, the most distinguished mathematician, will rejoice in no moderate degree, when they first see these magnetical books of yours, and observe their λιμενευρετική, or Haven-finding Art, enlarged and enriched by so great and unexpected an addition; and without doubt they will urge all their own shipmasters (as far as they can) to observe also everywhere the magnetick declination below the horizon no less than the variation. May your Magnetical Philosophy, therefore, most learned Dr. Gilbert, come forth into the light under the best auspices, after being kept back not till the ninth year only (as Horace prescribes), but already unto almost a second nine, a philosophy rescued at last by so many toils, studyings, watchings, with so much ingenuity and at no moderate expense maintained continuously through so many years, out of darkness and dense 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

Envy detracts from great Homer's genius;

but

Whoever thou art, Zoilus, thou hast thy name from him.

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

(If there is any truth in the forebodings of seers),

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 their own ores; & that all magnetick virtues, though weaker, exist in the ore itself & in smelted iron.

[Chap. 17]. That the globe of the earth is magnetick, & a magnet; & how in our hands the magnet stone has all the primary forces of the earth, while the earth by the same powers remains constant in a fixed direction in the universe.

Book 2.

[Chap. 1]. On Magnetick Motions.

[Chap. 2]. On the Magnetick Coition, and first on the attraction of Amber, or more truly, on the attaching of bodies to Amber.

[Chap. 3]. Opinions of others on Magnetick Coition, which they call Attraction.

[Chap. 4]. On Magnetick Force & Form, what it is; and on the cause of the Coition.

[Chap. 5]. How the Power dwells in the Loadstone.

[Chap. 6]. How magnetick pieces of Iron and smaller loadstones conform themselves to a terrella & to the earth itself, and by them are disposed.

[Chap. 7]. On the Potency of the Magnetick Virtue, and on its nature capable of spreading out into an orbe.

[Chap. 8]. On the geography of the Earth, and of the Terrella.

[Chap. 9]. On the Æquinoctial Circle of the Earth and of a Terrella.

[Chap. 10]. Magnetick Meridians of the Earth.

[Chap. 11]. Parallels.

[Chap. 12]. The Magnetick Horizon.

[Chap. 13]. On the Axis and Magnetick Poles.

[Chap. 14]. Why at the Pole itself the Coition is stronger than in the other parts intermediate between the æquator and the pole; and on the proportion of forces of the coition in various parts of the earth and of the terrella.

[Chap. 15]. The Magnetick Virtue which is conceived in Iron is more apparent in an iron rod than in a piece of Iron that is round, square, or of other figure.

[Chap. 16]. Showing that Movements take place by the Magnetical Vigour though solid bodies lie between; and on the interposition of iron plates.

[Chap. 17]. On the Iron Cap of a Loadstone, with which it is armed at the pole (for the sake of the virtue), and on the efficacy of the same.

[Chap. 18]. An armed Loadstone does not indue an excited piece of Iron with greater vigour than an unarmed.

[Chap. 19]. Union with an armed Loadstone is stronger; hence greater weights are raised; but the coition is not stronger, but generally weaker.

[Chap. 20]. An armed Loadstone raises an armed Loadstone, which also attracts a third; which likewise happens, though the virtue in the first be somewhat small.

[Chap. 21]. If Paper or any other Medium be interposed, an armed loadstone raises no more than an unarmed one.

[Chap. 22]. That an armed Loadstone draws Iron no more than an unarmed one: and that an armed one is more strongly united to iron is shown by means of an armed loadstone and a polished Cylinder of iron.

[Chap. 23]. The Magnetick Force causes motion toward unity, and binds firmly together bodies which are united.

[Chap. 24]. A piece of Iron placed within the Orbe of a Loadstone hangs suspended in the air, if on account of some impediment it cannot approach it.

[Chap. 25]. Exaltation of the power of the magnet.

[Chap. 26]. Why there should appear to be a greater love between iron & loadstone, than between loadstone & loadstone, or between iron & iron, when close to the loadstone, within its orbe of virtue.

[Chap. 27]. The Centre of the Magnetick Virtues in the earth is the centre of the earth; and in a terrella is the centre of the stone.

[Chap. 28]. A Loadstone attracts magneticks not only to a fixed point or pole, but to every part of a terrella save the æquinoctial zone.

[Chap. 29]. On Variety of Strength due to Quantity or Mass.

[Chap. 30]. The Shape and Mass of the Iron are of most importance in cases of coition.

[Chap. 31]. On long and round stones.

[Chap. 32]. Certain Problems and Magnetick Experiments about the Coition, and Separation, and regular Motion of Bodies magnetical.

[Chap. 33]. On the Varying Ratio of Strength, and of the Motion of coition, within the orbe of virtue.

[Chap. 34]. Why a Loadstone should be stronger in its poles in a different ratio; as well in the Northern regions as in the Southern.

[Chap. 35]. On a Perpetual Motion Machine, mentioned by authors, by means of the attraction of a loadstone.

[Chap. 36]. How a more robust Loadstone may be recognized.

[Chap. 37]. Use of a Loadstone as it affects iron.

[Chap. 38]. On Cases of Attraction in other Bodies.

[Chap. 39]. On Bodies which mutually repel one another.

Book 3.

[Chap. 1]. On Direction.

[Chap. 2]. The Directive or Versorial Virtue (which we call verticity): what it is, how it exists in the loadstone; and in what way it is acquired when innate.

[Chap. 3]. How Iron acquires Verticity through a loadstone, and how that verticity is lost and changed.

[Chap. 4]. Why Iron touched by a Loadstone acquires an opposite verticity, and why iron touched by the true Northern side of a stone turns to the North of the earth, by the true Southern side to the South; and does not turn to the South when rubbed by the Northern point of the stone, and when by the Southern to the North, as all who have written on the Loadstone have falsely supposed.

[Chap. 5]. On the Touching of pieces of Iron of divers shapes.

[Chap. 6]. What seems an Opposing Motion in Magneticks is a proper motion toward unity.

[Chap. 7]. A determined Verticity and a disponent Faculty are what arrange magneticks, not a force, attracting them or pulling them together, nor merely a strongish coition or unition.

[Chap. 8]. Of Discords between pieces of Iron upon the same pole of a Loadstone, and how they can agree and stand joined together.

[Chap. 9]. Figures illustrating direction and showing varieties of rotations.

[Chap. 10]. On Mutation of Verticity and of Magnetick Properties, or on alteration in the power excited by a loadstone.

[Chap. 11]. On the Rubbing of a piece of Iron on a Loadstone in places midway between the poles, and upon the æquinoctial of a terrella.

[Chap. 12]. In what way Verticity exists in any Iron that has been smelted though not excited by a loadstone.

[Chap. 13]. Why no other Body, excepting a magnetick, is imbued with verticity by being rubbed on a loadstone, and why no body is able to instil and excite that virtue, unless it be a magnetick.

[Chap. 14]. The Placing of a Loadstone above or below a magnetick body suspended in æquilibrio changes neither the power nor the verticity of the magnetick body.

[Chap. 15]. The Poles, Æquator, Centre in an entire Loadstone remain and continue steady; by diminution and separation of some part they vary and acquire other positions.

[Chap. 16]. If the Southern Portion of a Stone be lessened, something is also taken away from the power of the Northern Portion.

[Chap. 17]. On the Use and Excellence of Versoria: and how iron versoria used as pointers in sun-dials, and the fine needles of the mariners' compass, are to be rubbed, that they may acquire stronger verticity.

Book 4.

[Chap. 1]. On Variation.

[Chap. 2]. That the variation is caused by the inæquality of the projecting parts of the earth.

[Chap. 3]. The variation in any one place is constant.

[Chap. 4]. The arc of variation is not changed equally in proportion to the distance of places.

[Chap. 5]. An island in Ocean does not change the variation, as neither do mines of loadstone.

[Chap. 6]. The variation and direction arise from the disponent power of the earth, and from the natural magnetick tendency to rotation, not from attraction, or from coition, or from other occult cause.

[Chap. 7]. Why the variation from that lateral cause is not greater than has hitherto been observed, having been rarely seen to reach two points of the mariners' compass, except near the pole.

[Chap. 8]. On the construction of the common mariners' compass, and on the diversity of the compasses of different nations.

[Chap. 9]. Whether the terrestrial longitude can be found from the variation.

[Chap. 10]. Why in various places near the pole the variations are much more ample than in a lower latitude.

[Chap. 11]. Cardan's error when he seeks the distance of the centre of the earth from the centre of the cosmos by the motion of the stone of Hercules; in his book 5, On Proportions.

[Chap. 12]. On the finding of the amount of variation: how great is the arc of the Horizon from its arctick to its antarctick intersection of the meridian, to the point respective of the magnetick needle.

[Chap. 13]. The observations of variation by seamen vary, for the most part, and are uncertain: partly from error and inexperience, and the imperfections of the instruments: and partly from the sea being seldom so calm that the shadows or lights can remain quite steady on the instruments.

[Chap. 14]. On the variation under the æquinoctial line, and near it.

[Chap. 15]. The variation of the magnetick needle in the great Æthiopick and American sea, beyond the æquator.

[Chap. 16]. On the variation in Nova Zembla.

[Chap. 17]. Variation in the Pacifick Ocean.

[Chap. 18]. On the variation in the Mediterranean Sea.

[Chap. 19]. The variation in the interior of large Continents.

[Chap. 20]. Variation in the Eastern Ocean.

[Chap. 21]. How the deviation of the versorium is augmented and diminished by reason of the distance of places.

Book 5.

[Chap. 1]. On Declination.

[Chap. 2]. Diagram of declinations of the magnetick needle, when excited, in the various positions of the sphere, and horizons of the earth, in which there is no variation of the declination.

[Chap. 3]. An indicatory instrument, showing by the virtue of a stone the degrees of declination from the horizon of each several latitude.

[Chap. 4]. Concerning the length of a versorium convenient for declination on a terrella.

[Chap. 5]. That declination does not arise from the attraction of the loadstone, but from a disposing and rotating influence.

[Chap. 6]. On the proportion of declination to latitude, and the cause of it.

[Chap. 7]. Explanation of the diagram of the rotation of a magnetick needle.

[Chap. 8]. Diagram of the rotation of a magnetick needle, indicating magnetical declination in all latitudes, and from the rotation and declination, the latitude itself.

[Chap. 9]. Demonstration of direction, or of variation from the true direction, at the same time with declination, by means of only a single motion in water, due to the disposing and rotating virtue.

[Chap. 10]. On the variation of the declination.

[Chap. 11]. On the essential magnetick activity sphærically effused.

[Chap. 12]. Magnetick force is animate, or imitates life; and in many things surpasses human life, while this is bound up in the organick body.

Book 6.

[Chap. 1]. On the globe of the earth, the great magnet.

[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.

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.

[CHAP. II].

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

The Magnet's name the observing Grecians drew

From the Magnetick region where it grew.

It is called Heraclean from the city Heraclea, or from the invincible Hercules, on account of the great strength and domination and power which there is in iron of subduing all things: it is also called siderite, as being of iron; being not unknown to the most ancient writers, to the Greeks, Hippocrates, and others, as also (I believe) to Jewish and Egyptian writers; For in the oldest mines of iron, the most famous in Asia, the loadstone was often dug out with its uterine brother, iron. And if the tales be true which are told of the people of the Chinas, they were not unacquainted in primitive times with magnetical experiments, for even amongst

them the finest magnets of all are still found. The Egyptians, as Manetho relates, gave it the name Os Ori: calling the power which governs the turning of the sun Orus, as the Greeks call it Apollo. But later by Euripides, as narrated by Plato, it was designated under the name of Magnet. By Plato in the Io, Nicander of Colophon, Theophrastus, Dioscorides, Pliny, Solinus, Ptolemy, Galen, and other investigators of nature it was recognized and commended; such, however, is the variety of magnets and their points of unlikeness in hardness, softness, heaviness, lightness, density, firmness, and friability of substance: so great and manifold are the differences in colour and other qualities, that they have not handed down any adequate account of it, which therefore was laid aside or left imperfect by reason of the unfavourable character of the time; for in those times varieties of specimens and foreign products never before seen were not brought from such distant regions by traders and mariners as they have been lately, and now that all over the globe all kinds of merchandise, stones, woods, spices, herbs, metals, and ore in abundance are greedily sought after: neither was metallurgy so generally cultivated in a former age. There is a difference in vigour; as whether it is male or female: for it was thus that the ancients used often to distinguish many individuals of the same species. Pliny quotes from Sotacus five kinds; those from Æthiopia, Macedonia, Bœotia, the Troad, and Asia, which were especially known to the ancients: but we have posited as many kinds of loadstones as there are in the whole of nature regions of different kinds of soil. For in all climates, in every province, on every soil, the loadstone is either found, or else lies unknown on account of its rather deep site and inaccesible position; or by reason of its weaker and less obvious strength it is not recognized by us while we see and handle it. To the ancients the differences were those of colour[^[49]], how they are red and black in Magnesia and Macedonia, in Bœotia red rather than black, in the Troad black, without strength: While in Magnesia in Asia they are white, not attracting iron, and resemble pumice-stone. A strong loadstone of the kind celebrated so often nowadays in experiments presents the appearance of unpolished iron, and is mostly found in iron mines: it is even wont to be discovered in an unbroken lode by itself: Loadstones of this sort are brought from East India, China, and Bengal, of the colour of iron, or of a dark blood or liver colour; and these are the finest, and are sometimes of great size, as though broken off a great rock, and of considerable weight; sometimes single stones, as it were, and entire: some of these, though of only one pound weight, can lift on high four ounces of iron or a half-pound or even a whole pound. Red ones are found in Arabia, as broad as a tile, not equal in weight to those brought from China, but strong and good: they are a little darker in the island of Elba in the Tuscan sea, and together with

these also grow white ones, like some in Spain in the mines of Caravaca: but these are of lesser power. Black ones also are found, of lower strength, such as those of the iron mines in Norway and in sea-coast places near the strait of Denmark. Amongst the blue-black or dusky blue also some are strong and highly commended. Other loadstones are of a leaden colour, fissile and not-fissile, capable of being split like slates in layers. I have also some like gray marble of an ashen colour, and some speckled like gray marble, and these take the finest polish. In Germany there are some perforated like honeycombs, lighter than any others, and yet strong. Those are metallick which smelt into the best iron; others are not easily smelted, but are burned up. There are loadstones that are very heavy, as also others very light; some are very powerful in catching up pieces of iron, while others are weaker and of less capacity, others so feeble and barren that they with difficulty attract ever so tiny a piece of iron and cannot repel an opposite magnetick. Others are firm and tough, and do not readily yield to the artificer. Others are friable. Again, there are some dense and hard as emery, or loose-textured and soft as pumice; porous or solid; entire and uniform, or varied and corroded; now like iron for hardness, yea, sometimes harder than iron to cut or to file; others are as soft as clay. Not all magnets can be properly called stones; some rather represent rocks; while others exist rather as metallick lodes; others as clods and lumps of earth. Thus varied and unlike each other, they are all endowed, some more, some less, with the peculiar virtue. For they vary according to the nature of the soil, the different admixture of clods and humours, having respect to the nature of the region and to their subsidence in this last-formed crust of the earth, resulting from the confluence of many causes, and the perpetual alternations of growth and decline, and the mutations of bodies. Nor is this stone of such potency rare; and there is no region wherein it is not to be found in some sort. But if men were to search for it more diligently and at greater outlay, or were able, where difficulties are present, to mine it, it would come to hand everywhere, as we shall hereafter prove. In many countries have been found and opened mines of efficacious loadstones unknown to the ancient writers, as for instance in Germany, where none of them has ever asserted that loadstones were mined. Yet since the time when, within the memory of our fathers, metallurgy began to flourish there, loadstones strong and efficacious in power have been dug out in numerous places; as in the Black Forest beyond Helceburg; in Mount Misena not far from Schwartzenberg[^[50]]; a fairly strong kind between Schneeberg and Annaberg in Joachimsthal, as was noticed by Cordus: also near the village of Pela in Franconia. In Bohemia it occurs in iron mines in the Lessa district and other places, as Georgious Agricola and several other men learned in metallurgy

witness. In like manner in other countries in our time it is brought to light; for as the stone remarkable for its virtues is now famous throughout the whole world, so also everywhere every land produces it, and it is, so to speak, indigenous in all lands. In East India, in China, in Bengal near the river Indus it is common, and in certain maritime rocks: in Persia, Arabia, and the islands of the Red Sea; in many places in Æthiopia, as was formerly Zimiri, of which Pliny makes mention. In Asia Minor around Alexandria and the Troad; in Macedonia, Bœotia, in Italy, the island of Elba, Barbary; in Spain still in many mines as aforetime. In England quite lately a huge power of it was discovered in a mine belonging to Adrian Gilbert, gentleman[^[51]]; also in Devonshire and the Forest of Dean; in Ireland, too, Norway, Denmark, Sweden, Lapland, Livonia, Prussia, Poland, Hungary. For although the terrestrial globe, owing to the varied humours and natures of the soil arising from the continual succession of growth and decay, is in the lapse of time efflorescing through all its ambit deeper into its surface, and is girt about with a varied and perishable covering, as it were with a veil; yet out of her womb ariseth in many places an offspring nigher to the more perfect body and makes its way to the light of day. But the weak and less vigorous loadstones, enfeebled by the flow of humours, are visible in every region, in every strath. It is easy to discover a vast quantity of them everywhere without penetrating mountains or great depths, or encountering the difficulties and hardships of miners; as we shall prove in the sequel. And these we shall take pains so to prepare by an easy operation that their languid and dormant virtue shall be made manifest. It is called by the Greeks[^[52]] ἑράκλιος, as by Theophrastus, and μαγνῆτις; and μάγνης, as by Euripides, as quoted by Plato in the Io: by Orpheus[^[53]] too μαγνῆοσα, and σιδερίτης as though of iron: by the Latins magnes, Herculeus; by the French aimant[^[54]], corruptly from adamant; by the Spaniards piedramant: by the Italians calamita[^[55]]; by the English loadstone and adamant stone[^[56]], by the Germans magness[^[57]] and siegelstein: Among English, French, and Spaniards it has its common name from adamant; perhaps because they were at one time misled by the name sideritis being common to both: the magnet is called σιδερίτης from its virtue of attracting iron: the adamant is called σιδερίτης from the brilliancy of polished iron. Aristotle designates it merely by the name of the stone:[^[58]] Ἔοικε δὲ καὶ θαλῆς ἐξ ὧν ἀπομνημονεύουσι, κινητικόν τι τὴν ψυχὴν ὑπολαβεῖν, ἔιπερ τὸν λίθον ἔφη ψυχὴν ἔχειν, ὅτι τὸν σίδηρον κινεῖ: De Anima, Lib. I. The name of magnet is also applied to another stone differing from siderite, having the appearance of silver; it is like Amianth in its nature; and since it consists of laminæ (like specular stone)[^[59]], it differs in form: in German Katzensilber and Talke[^[60]].

[CHAP. III].

The Loadstone has parts distinct in their natural
power, & poles conspicuous for their property.

On the stone A B the versorium is placed in such a way that the versorium may remain in equilibrium: you will mark with chalk the course of the iron when at rest: Move the instrument to another spot, and again make note of the direction and aspect: do the same thing in several places, and from the concurrence of the lines of direction you will find one pole at the point A, the other at B. A versorium placed near the stone also indicates the true pole; when at right angles it eagerly beholds the stone and seeks the pole itself directly, and is turned in a straight line through the axis to the

centre of the stone. For instance, the versorium D faces toward A and F, the pole and centre, whereas E does not exactly respect * either the pole A or the centre F[^[64]]. A bit of rather fine iron wire, of the length of a barley-corn, is placed on the stone, and is moved over the regions and surface of the stone, until it rises to the perpendicular[^[65]]: for it stands erect at the actual pole, whether Boreal or austral; the further from the pole, the more it inclines from the vertical. The poles thus found you shall mark with a sharp file or gimlet.

[CHAP. IIII].

Which pole of the stone is the Boreal: & how it is
distinguished from the austral.

[CHAP. V].

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

And you will then see[^[68]] that A the northern point will turn to the south, as before; in like manner also the point D will move to the north, in the divided stone, as in the whole one. Whereas, of the parts B and C, which were before continuous, and are now divided, the one is southern B, the other northern C. B draws C, desirous to be united, and to be brought back into its pristine continuity: for these which are now two stones were formed out of one: and for this cause C of the one turning itself to B of the other, they mutually attract each other, and when freed from obstacles and relieved of their own weight, as upon the surface of water, they run together and are conjoined. But if you direct the part or point A to C in the other stone, the one repels or turns away from the other: for so were nature perverted, and the form of the stone perturbed, a form that strictly keeps the laws which it imposed upon bodies: hence, when all is not rightly ordered according to nature, comes the flight of one from the other's perverse position and from the discord, for nature does not allow of an unjust and inequitable peace, or compromise: but wages war and exerts force to make bodies acquiesce well and justly. Rightly arranged, therefore, these mutually attract each other; that is, both stones, the stronger as well as the weaker, run together, and with their whole forces tend to unity, a fact that is evident in all magnets, not in the Æthiopian only, as Pliny supposed. The Æthiopian magnets if they be powerful, like those brought from China, because all strong ones show the effect more quickly and more plainly, attract more strongly in the parts nearest the pole, and turn about until pole looks directly at pole. The pole of a stone more persistently attracts and more rapidly seizes the corresponding part (which they term the adverse part) of another stone; for instance, North pulls South; just so it also summons iron with more vehemence, and the iron cleaves to it more firmly whether it have been previously excited by the magnet, or is untouched. For thus, not without reason hath it been ordained by nature, that the parts nearer to the pole should more firmly attract: but that at the pole itself should be the seat, the throne, as it were, of a consummate and splendid virtue, to which magnetical bodies on being brought are more vehemently attracted, and from which they are with utmost difficulty dislodged. So the poles are the parts which more particularly spurn and thrust away things strange and alien perversely set beside them.

[CHAP. VI].

Loadstone attracts the ore of iron, as well as iron
proper, smelted and wrought.

[CHAP. VII].

What Iron is, and of what substance,
and its uses.

[^[70]]Here corn exults, and there the grape is glad,

Here trees and grass unbidden verdure add.

So mark how Tmolus yields his saffrone store,

But ivory is the gift of Indian shore;

With incense soft the softer Shebans deal;

The stark Chalybeans' element is steel:

With acrid castor reek the Pontic wares,

Epirus wins the palm of Elian mares.

But what the Chemists (as Geber, and others) call fixed earthy sulphur in iron is nothing else than the homogenic earth-substance concreted by its own humour, amalgamated with a double fluid: a metallick humour is inserted along with a small quantity of the substance of the earth not devoid of humour. Wherefore the common saying that in gold there is pure earth, but in iron mostly impure, is wrong; as though there were indeed such a thing as natural earth, and that the globe itself were (by some unknown process of refining) depurate. In iron, especially in the best iron, there is earth in its own nature true and genuine; in the other metals there is not so much earth as that in place of earth and precipitates there are consolidated and (so to speak) fixed salts, which are efflorescences of the globe, and which differ also greatly

in firmness and consistency: In the mines their force rises up along with a twofold humour from the exhalations, they solidify in the underground spaces into metallic veins: so too they are also connate by virtue of their place and of the surrounding bodies, in natural matrices, and take on their specific forms. Of the various constitutions of loadstones and their diverse substances, colours, and virtues, mention has been made before: but, now having stated the cause and origin of metals, we have to examine ferruginous matter not as it is in the smelted metal, but as that from which the metal is refined. Quasi-pure iron is found of its proper colour and in its own lodes; still, not as it will presently be, nor as adapted for its various uses. It is sometimes dug up covered with white silex or with other stones. It is often the same in river sand, as in Noricum. A nearly pure ore of iron is now often dug up in Ireland, which the smiths, without the labours of furnaces, hammer out in the smithy into iron implements. In France iron is very commonly smelted out of a liver-coloured stone, in which are glittering scales; the same kind[^[71]] without the scales is found in England, which also they use for craftsmen's ruddle[^[72]]. In Sussex in England[^[73]] is a rich dusky ore and also one of a pale ashen hue, both of which on being dried for a time, or kept in moderate fires, presently acquire a liver-colour; here also is found a dusky ore square-shaped with a black rind of greater hardness. An ore having the appearance of liver is often variously intermingled with other stones: as also with the perfect loadstone which yields the best of iron. There is also a rusty ore of iron, one of a leaden hue tending to black, one quite black, or black mixed with true cobalt: there is another sort mixed either with pyrites, or with sterile plumbago. One kind is also like jet, another like bloodstone. The emery used by armourers, and by glaziers for glass-cutting, called amongst the English Emerelstone, by the Germans Smeargel, is ferruginous; albeit iron is extracted from it with difficulty, yet it attracts the versorium. It is now and then found in deep iron and silver diggings. Thomas Erastus says he had heard from a certain learned man of iron ores, of the colour of iron, but quite soft and fatty, which can be smoothed with the fingers like butter, out of which excellent iron can be smelted: somewhat the same we have seen found in England, having the aspect of Spanish soap. Besides the numberless kinds of stony ores, iron is extracted from clay, from clayey earth, from ochre, from a rusty matter deposited from chalybeate waters; In England iron is copiously extracted in furnaces often from sandy and clayey stones which appear to contain iron not more than sand, marl, or any other clay soils contain it. Thus in Aristotle's book De Mirabilibus Auscultationibus[^[74]], "There is said" (he states) "to be a peculiar formation of Chalybean and Misenian iron, for instance the sort collected from river gravel; some say

that after being simply washed it is smelted in the furnace; others declare that it and the sediment which subsides after several washings are cast in and purified together by the fire; with the addition of the stone pyrimachus which is found there in abundance." Thus do numerous sorts of things contain in their various substances notably and abundantly this element of iron and earth. However, there are many stones, and very common ones, found in every soil, also earths, and various and mixed materials, which do not hold rich substances, but yet have their own iron elements, and yield them to skilfully-made fires, yet which are left aside by metallick men because they are less profitable; while other soils give some show of a ferruginous nature, yet (being very barren) are hardly ever smelted down into iron; and being neglected are not generally known. Manufactured irons differ very greatly amongst themselves. For one kind is tenacious in its nature, and this is the best; one is of medium quality: another is brittle, and this is the worst. Sometimes the iron, by reason of the excellency of the ore, is wrought into steel, as to-day in Noricum. From the finest iron, too, well wrought and purged from all dross, or by being plunged in water after heating, there issues what the Greeks call στόμωμα; the Latins acies; others aciarium, such as was at times called Syrian, Parthian, Noric, Comese, Spanish; elsewhere it is named from the water in which it is so often plunged, as at Como in Italy[^[75]], Bambola and Tarazona in Spain. Acies fetches a much larger price than mere iron. And owing to its superiority it better accords with the loadstone, from which more powerful quality it is often smelted, and it acquires the virtues from it more quickly, retains them longer at their full, and in the best condition for magnetical experiments. After iron has been smelted in the first furnaces, it is afterward wrought by various arts in large worksteads or mills, the metal acquiring consistency when hammered with ponderous blows, and throwing off the dross. After the first smelting it is rather brittle and by no means perfect. Wherefore with us (English) when the larger military guns are cast, they purify the metal from dross more fully, so that they may be stronger to withstand the force of the firing; and they do this by making it pass again (in a fluid state) through a chink, by which process it sheds its recremental matter. Smiths render iron sheets tougher with certain liquids, and by blows of the hammer, and from them make shields and breastplates that defy the blows of battle-axes. Iron becomes harder through skill and proper tempering, but also by skill turns out in a softer condition and as pliable as lead. It is made hard by the action of certain waters into which while glowing it is plunged, as at Bambola and Tarazona in Spain: It grows soft again, either by the effect of fire alone, when without hammering and without water, it is left to cool by itself; or by that of grease into which it is plunged; or

(that it may the better serve for various trades) it is tempered variously by being skilfully besmeared. Baptista Porta expounds this art in book 13 of his Magia Naturalis. Thus this ferric and telluric nature is included and taken up in various bodies of stones, ores, and earths; so too it differs in aspect, in form, and in efficiency. Art smelts it by various processes, improves it, and turns it, above all material substances, to the service of man in trades and appliances without end. One kind of iron is adapted for breastplates, another serves as a defence against shot, another protects against swords and curved blades (commonly called scimitars), another is used for making swords, another for horseshoes. From iron are made nails, hinges, bolts, saws, keys, grids, doors, folding-doors, spades, rods, pitchforks, hooks, barbs, tridents, pots, tripods, anvils, hammers, wedges, chains, hand-cuffs, fetters, hoes, mattocks, sickles, baskets, shovels, harrows, planes, rakes, ploughshares, forks, pans, dishes, ladles, spoons, spits, knives, daggers, swords, axes, darts, javelins, lances, spears, anchors, and much ship's gear. Besides these, balls, darts, pikes, breastplates, helmets, cuirasses, horseshoes, greaves, wire, strings of musical instruments, chairs, portcullises, bows, catapults, and (pests of human kind) cannon, muskets, and cannon-balls, with endless instruments unknown to the Latins: which things I have rehearsed in order that it may be understood how great is the use of iron, which surpasses a hundred times that of all the other metals; and is day by day being wrought by metal-workers whose stithies are found in almost every village. For this is the foremost of metals, subserving many and the greatest needs of man, and abounds in the earth above all other metals, and is predominant. Wherefore those Chemists are fools[^[76]] who think that nature's will is to perfect all metals into gold; she might as well be making ready to change all stones to diamonds, since diamond surpasses all in splendour and hardness, because gold excels in splendour, gravity, and density, being invincible against all deterioration. Iron as dug up is therefore, like iron that has been smelted, a metal, differing a little indeed from the primary homogenic terrestrial body, owing to the metallick humour it has imbibed; yet not so alien as that it will not, after the manner of refined matter, admit largely of the magnetick forces, and may be associated with that prepotent form belonging to the earth, and yield to it a due submission.

[CHAP. VIII].

In what countries and districts iron
originates.

[CHAP. IX].

Iron ore attracts iron ore.

[CHAP. X].

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

[CHAP. XI].

Wrought Iron, not excited by a loadstone,
draws iron.

[CHAP. XII].

A long piece of Iron, even though not excited by a
loadstone, settles itself toward North and South.

[CHAP. XIII].

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

[CHAP. XIIII].

Concerning other powers of loadstone, and its
medicinal properties.

[CHAP. XV].

The Medicinal Virtue of Iron.[^[93]]

[CHAP. XVI].

That loadstone & iron ore are the same, but iron an
extract from both, as other metals are from their own
ores; & that all magnetick virtues, though
weaker, exist in the ore itself & in
smelted iron.

[CHAP. XVII].

That the globe of the earth is magnetick, & a magnet; &
how in our hands the magnet stone has all the primary
forces of the earth, while the earth by the
same powers remains constant in a
fixed direction in the
universe.