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+Project Gutenberg's On the magnet, by William Gilbert of Colchester
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: On the magnet;
+       a new physiology, demonstrated by many arguments & experiments
+
+Author: William Gilbert of Colchester
+
+Release Date: September 26, 2010 [EBook #33810]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK ON THE MAGNET ***
+
+
+
+
+Produced by Curtis Weyant, Keith Edkins and the Online
+Distributed Proofreading Team at http://www.pgdp.net (This
+file was produced from images generously made available
+by the Posner Memorial Collection
+(http://posner.library.cmu.edu/Posner/))
+
+
+
+
+
+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.
+
+[Illustration]
+
+LONDON
+
+       *       *       *       *       *
+
+
+IMPRINTED AT THE CHISWICK PRESS ANNO
+
+MCM.
+
+       *       *       *       *       *
+
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+{ij} [Illustration]
+
+PREFACE TO THE CANDID
+READER, STUDIOUS OF
+THE MAGNETICK
+PHILOSOPHY.
+
+Clearer proofs, in the discovery of secrets, and in the investigation of
+the hidden causes of things, being afforded by trustworthy experiments and
+by demonstrated arguments, than by the probable guesses and opinions of the
+ordinary professors of philosophy: so, therefore, that the noble substance
+of that great magnet, our common mother (the earth), hitherto quite
+unknown, and the conspicuous and exalted powers of this our globe, may be
+the better understood, we have proposed to begin with the common magnetick,
+stony, and iron material, and with magnetical bodies, and with the nearer
+parts of the earth which we can reach with our hands and perceive with our
+senses; then to proceed with demonstrable magnetick experiments; and so
+penetrate, for the first time, into the innermost parts of the earth. For
+after we had, in order finally to learn the true substance of the globe,
+seen and thoroughly examined many of those things which have been obtained
+from mountain heights or ocean depths, or from the profoundest caverns and
+from hidden mines: we applied much prolonged labour on investigating the
+magnetical forces; so wonderful indeed are they, compared with the forces
+of all other minerals, surpassing even the virtues of all other bodies
+about us. Nor have we found this our labour idle or unfruitful; since daily
+during our experimenting, new and unexpected properties came to light; and
+our Philosophy hath grown so much from the things diligently observed, that
+we have attempted to expound the interior parts of the terrene globe, and
+its native substance, upon magnetick principles; and to reveal to men the
+earth (our common mother), and to point it out as if with the finger, by
+real demonstrations and by experiments manifestly apparent to the senses.
+And as geometry ascends from sundry very small and very easy principles to
+the greatest and most difficult; by which the wit of man climbs above the
+firmament: so our magnetical doctrine and science first sets forth in
+convenient order the things which are less obscure; from these there come
+to light others that are more remarkable; and at length in due order there
+are opened the concealed and most secret things of the globe of the earth,
+and the causes are made known of those things which, either through the
+ignorance of the ancients or the neglect of moderns, have remained
+unrecognized and overlooked. But why should I, in so vast an Ocean of Books
+by which the minds of studious men are troubled and fatigued, through which
+very foolish productions the world and unreasoning men are intoxicated, and
+puffed up, rave and create literary broils, and while professing to be
+philosophers, physicians, mathematicians and astrologers, neglect and
+despise men of learning: why should I, I say, add aught further to this
+so-perturbed republick of letters, and expose this noble philosophy, which
+seems new and incredible by reason of so many things hitherto unrevealed,
+to be damned and torn to pieces by the maledictions of those who are either
+already sworn to the opinions of other men, or are foolish corruptors of
+good arts, learned idiots, grammatists, sophists, wranglers, and perverse
+little folk? But to you alone, true philosophizers, honest men, who seek
+knowledge not from books only but from things themselves, have I addressed
+these magnetical principles in this new sort of Philosophizing. But if any
+see not fit to assent to these self-same opinions and paradoxes, let them
+nevertheless mark the great array of experiments and discoveries (by which
+notably every philosophy flourisheth), which have been wrought out and
+demonstrated by us with many pains and vigils and expenses. In these
+rejoice, and employ them to better uses, if ye shall be able. I know how
+arduous it is to give freshness to old things, lustre to the antiquated,
+light to the dark, grace to the despised, credibility to the doubtful; so
+much the more by far is it difficult to win and establish some authority
+for things new and unheard-of, in the face of all the opinions of all men.
+Nor for that do we care, since philosophizing, as we deemed, is for the
+few. To our own discoveries and experiments we have affixed asterisks,
+larger and smaller, according to the importance and subtlety of the matter.
+Whoso desireth to make trial of the same experiments, let him handle the
+substances, not negligently and carelessly, but prudently, deftly, and in
+the proper way; nor let him (when a thing doth not succeed) ignorantly
+denounce our discoveries: for nothing hath been set down in these books
+which hath not been explored and many times performed and repeated amongst
+us. Many things in our reasonings and hypotheses will, perchance, at first
+sight, seem rather hard, when they are foreign to the {iij} commonly
+received opinion; yet I doubt not but that hereafter they will yet obtain
+authority from the demonstrations themselves. Wherefore in magnetical
+science, they who have made most progress, trust most in and profit most by
+the hypotheses; nor will anything readily become certain to any one in a
+magnetical philosophy in which all or at least most points are not
+ascertained. This nature-knowledge is almost entirely new and unheard-of,
+save what few matters a very few writers have handed down concerning
+certain common magnetical powers. Wherefore we but seldom quote antient
+Greek authors in our support, because neither by using greek arguments nor
+greek words can the truth be demonstrated or elucidated either more
+precisely or more significantly. For our doctrine magnetical is at variance
+with most of their principles and dogmas. Nor have we brought to this work
+any pretence of eloquence or adornments of words; but this only have we
+done, that things difficult and unknown might be so handled by us, in such
+a form of speech, and in such words as are needed to be clearly understood:
+Sometimes therefore we use new and unusual words, not that by means of
+foolish veils of vocabularies we should cover over the facts with shades
+and mists (as Alchemists are wont to do) but that hidden things which have
+no name, never having been hitherto perceived, may be plainly and correctly
+enunciated. After describing our magnetical experiments and our information
+of the homogenick parts of the earth, we proceed to the general nature of
+the whole globe; wherein it is permitted us to philosophize freely and with
+the same liberty which the Egyptians, Greeks, and Latins formerly used in
+publishing their dogmas: whereof very many errors have been handed down in
+turn to later authors: and in which smatterers still persist, and wander as
+though in perpetual darkness. To those early forefathers of philosophy,
+Aristotle, Theophrastus, Ptolemy, Hippocrates, and Galen, let due honour be
+ever paid: for by them wisdom hath been diffused to posterity; but our age
+hath detected and brought to light very many facts which they, were they
+now alive, would gladly have accepted. Wherefore we also have not hesitated
+to expound in demonstrable hypotheses those things which we have discovered
+by long experience. Farewell.
+
+       *       *       *       *       *
+
+
+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_.
+
+_Should there by chance be any one, most eminent Sir, who reckons as of
+small account these magnetical books and labours of yours, and thinks these
+studies of yours of too little moment, and by no means worthy enough of the
+attention of an eminent man devoted to the weightier study of Medicine:
+truly he must deservedly be judged to be in no common degree void of
+understanding. For that the use of the magnet is very important and wholly
+admirable is better known for the most part to men of even the lowest class
+than to need from me at this time any long address or commendation. Nor
+truly in my judgment could you have chosen any topick either more noble or
+more useful to the human race, upon which to exercise the strength of your
+philosophic intellect; since indeed it has been brought about by the divine
+agency of this stone, that continents of such vast circuit, such an
+infinite number of lands, islands, peoples, and tribes, which have remained
+unknown for so many ages, have now only a short time ago, almost within our
+own memory, been quite easily discovered and quite frequently explored, and
+that the circuit of the whole terrestrial globe also has been more than
+once circumnavigated by our own countrymen, Drake and Cavendish; a fact
+which I wish to mention to the lasting memory of these men. For by the
+pointing of the iron touched by a loadstone, the points of South, North,
+East, and West, and the other quarters of the world are made known to
+navigators even under an overcast sky and in the darkest night; so that
+thus they always very easily understand to which point of the world they
+ought to direct their ship's course; which before the discovery of this
+wonderful virtue of the magnetick [Greek: boreodeixis] was clearly
+impossible. Hence in old times (as is established in histories), an
+incredible anxiety and immense danger was continually threatening sailors;
+for at the coming on of a tempest and the obscuring of the view of sun and
+stars, they were left entirely in ignorance whither they were making; nor
+could they find out this by any reasoning or skill. With what joy then may
+we suppose them to have been filled, to what feelings of delight must all
+shipmasters have given utterance, when that index magnetical first offered
+itself to them as a most sure guide, and as it were a Mercury, for their
+journey? But neither was this sufficient for this magnetical Mercury; to
+indicate, namely, the right way, and to point, as it were, a finger in the
+direction toward which the course must be {iiij} directed; it began also
+long ago to show distinctly the distance of the place toward which it
+points. For since the index magnetical does not always in every place look
+toward the same point of the North, but deviates from it often, either
+toward the East or toward the West, yet always has the same deviation in
+the same place, whatever the place is, and steadily preserves it; it has
+come about that from that deviation, which they call variation, carefully
+noticed and observed in any maritime places, the same places could
+afterwards also be found by navigators from the drawing near and approach
+to the same variation as that of these same places, taken in conjunction
+with the observation of the latitude. Thus the Portuguese in their voyages
+to the East Indies had the most certain indications of their approach to
+the Cape of Good Hope; as appears from the narrations of Hugo van
+Lynschoten and of the very learned Richard Hakluyt, our countryman. Hence
+also the experienced skippers of our own country, not a few of them, in
+making the voyage from the Gulf of Mexico to the islands of the Azores,
+recognized that they had come as near as possible to these same islands;
+although from their sea-charts they seemed to be about six hundred British
+miles from them. And so, by the help of this magnetick index, it would seem
+as though that geographical problem of finding the longitude, which for so
+many centuries has exercised the intellects of the most learned
+Mathematicians, were going to be in some way satisfied; because if the
+variation for any maritime place whatever were known, the same place could
+very readily be found afterward, as often as was required, from the same
+variation, the latitude of the same place being not unknown._
+
+_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
+aequilibrio, 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 aequator 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 aequilibrio 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 [Greek: orthoboreodeixis] 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 inaequality 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 sphaerical motion of the earth; since not even they can
+easily clear themselves from many difficulties, which necessarily follow
+from the daily motion of the {v} 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
+sphaeres (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 aequator 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 aequator 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 sphaeres those three huge sphaeres, 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 _[Greek: limeneuretike]_, 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._
+
+{vj}
+
+       *       *       *       *       *
+
+
+_Interpretation of certain words.[1]_
+
+Terrella, a globular loadstone.
+
+Verticity, polar vigour, not [Greek: peridinesis] but [Greek: peridineisios
+dunamis]: not a vertex or [Greek: polos] 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 [Greek: helktike dunamis] of one only, but a [Greek:
+sundrome] 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.
+
+       *       *       *       *       *
+
+
+INDEX OF CHAPTERS.
+
+_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 Aequinoctial Circle of the Earth and of a Terrella.
+
+Chap. 10. Magnetick Meridians of the Earth.
+
+Chap. 11. Parallels.
+
+{vij} 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 aequator 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 aequinoctial 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 aequinoctial 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 aequilibrio changes neither the power nor the verticity of the
+magnetick body.
+
+Chap. 15. The Poles, Aequator, 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.
+
+{viij} _Book 4._
+
+Chap. 1. On Variation.
+
+Chap. 2. That the variation is caused by the inaequality 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 aequinoctial line, and near it.
+
+Chap. 15. The variation of the magnetick needle in the great Aethiopick and
+American sea, beyond the aequator.
+
+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 sphaerically 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 Praecession of the Aequinoxes, 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 Praecession of the Aequinoxes, & 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
+if a loadstone be anointed with garlick, or if a diamond be near, it does
+not attract iron[5]. Tales of this sort occur in Pliny, and in Ptolemy's
+_Quadripartitum_; and the errors have been sedulously propagated, and have
+gained ground (like ill weeds that grow apace) coming down even to our own
+day, through the writings of a host of men, who, to fill put their volumes
+to a proper bulk, write and copy out pages upon pages on this, that, and
+the other subject, of which they knew almost nothing for certain of their
+own experience. Such fables of the loadstone even Georgius Agricola
+himself, most distinguished in letters, relying on the writings of others,
+has embodied as actual history in his books _De Natura Fossilium_. Galen
+noted its medicinal power in the ninth book of his _De Simplicium
+Medicamentorum Facultatibus_, and its natural property of attracting iron
+in the first book of _De Naturalibus Facultatibus_; but he failed to
+recognize the cause, as Dioscorides before him, nor made further inquiry.
+But his commentator Matthiolus repeats the story of the garlick and the
+diamond, and moreover introduces Mahomet's shrine vaulted with
+loadstones[6], and writes that, by the exhibition of this (with the iron
+coffin hanging in the air) as a divine miracle, the public were imposed
+upon. But this is known by travellers to be false. Yet Pliny relates that
+Chinocrates the architect had commenced to roof over the temple of Arsinoe
+at Alexandria with magnet-stone[7], that her statue of iron placed therein
+might appear to hang in space. His own death, however, intervened, and also
+that of Ptolemy, who had ordered it to be made in honour of his sister.
+Very little was written by the ancients as to the causes of attraction of
+iron; by Lucretius and others there are some short notices; others only
+make slight and meagre mention of the attraction of iron: all of these are
+censured by Cardan for being so careless and negligent in a matter of such
+importance and in so wide a field of philosophizing; and for not supplying
+an ampler notion of it and a more perfect philosophy: and yet, beyond
+certain received opinions and ideas borrowed from others and ill-founded
+conjectures, he has not himself any more than they delivered to posterity
+in all his bulky works any contribution to the subject worthy of a
+philosopher. Of modern writers some set forth its virtue in medicine only,
+as [8]Antonius Musa Brasavolus, Baptista Montanus, Amatus Lusitanus, as
+before them Oribasius in his thirteenth chapter _De Facultate
+Metallicorum_, Aetius Amidenus, Avicenna, Serapio Mauritanus, Hali Abbas,
+Santes de Ardoynis, Petrus Apponensis, Marcellus[9], Arnaldus. Bare mention
+is made of certain points relating to the loadstone in very few words by
+Marbodeus Callus, Albertus, {3} Matthaeus Silvaticus, Hermolaus Barbarus,
+Camillus Leonhardus, Cornelius Agrippa, Fallopius, Johannes Langius,
+Cardinal Cusan, Hannibal Rosetius Calaber; by all of whom the subject is
+treated very negligently, while they merely repeat other people's fictions
+and ravings. Matthiolus compares the alluring powers of the loadstone which
+pass through iron materials, with the mischief of the torpedo, whose venom
+passes through bodies and spreads imperceptibly; Guilielmus Pateanus in his
+_Ratio Purgantium Medicamentorum_ discusses the loadstone briefly and
+learnedly. Thomas Erastus[10], knowing little of magnetical nature, finds
+in the loadstone weak arguments against Paracelsus; Georgius Agricola, like
+Encelius[11] and other metallurgists, merely states the facts; Alexander
+Aphrodiseus in his _Problemata_ considers the question of the loadstone
+inexplicable; Lucretius Carus, the poet of the Epicurean school, considers
+that an attraction is brought about in this way: that as from all things
+there is an efflux of very minute bodies, so from the iron atoms flow into
+the space emptied by the elements of the loadstone, between the iron and
+the loadstone, and that as soon as they have begun to stream towards the
+loadstone, the iron follows, its corpuscles being entangled. To much the
+same effect Johannes Costaeus adduces a passage from Plutarch; Thomas
+Aquinas[12], writing briefly on the loadstone in Chapter VII. of his
+_Physica_, touches not amiss on its nature, and with his divine and clear
+intellect would have published much more, had he been conversant with
+magnetick experiments. Plato thinks the virtue divine. But when three or
+four hundred years afterwards, the magnetick movement to North and South
+was discovered or again recognized by men, many learned men attempted, each
+according to the bent of his own mind, either by wonder and praise, or by
+some sort of reasonings, to throw light upon a virtue so notable, and so
+needful for the use of mankind. Of more modern authors a great number have
+striven to show what is the cause of this direction and movement to North
+and South, and to understand this great miracle of nature, and to disclose
+it to others: but they have lost both their oil and their pains; for, not
+being practised in the subjects of nature, and being misled by certain
+false physical systems, they adopted as theirs, from books only, without
+magnetical experiments, certain inferences based on vain opinions, and many
+things that are not, dreaming old wives' tales. Marsilius Ficinus ruminates
+over the ancient opinions, and in order to show the reason of the direction
+seeks the cause in the heavenly constellation of the Bear, supposing the
+virtue of the Bear to prevail in the stone and to be transferred to the
+iron. Paracelsus asserted that there are stars, endowed with the power of
+the loadstone, which attract to themselves iron. Levinus Lemnius describes
+and praises the compass[13], and infers its antiquity on certain grounds;
+he does not divulge the hidden miracle which he propounds. In the kingdom
+{4} of Naples the Amalfians were the first (so it is said) to construct the
+mariners' compass: and as Flavius Blondus says the Amalfians[14] boast, not
+without reason, that they were taught by a certain citizen, Johannes Goia,
+in the year thirteen hundred after the birth of Christ. That town is
+situated in the kingdom of Naples not far from Salerno, near the promontory
+of Minerva; and Charles V. bestowed that principality on Andrea Doria, that
+great Admiral, on account of his signal naval services. Indeed it is plain
+that no invention of man's device has ever done more for mankind than the
+compass: some notwithstanding consider that it was discovered by others
+previously and used in navigation, judging from ancient writings and
+certain arguments and conjectures. The knowledge of the little mariners'
+compass seems to have been brought into Italy by Paolo, the Venetian[15],
+who learned the art of the compass in the Chinas about the year MCCLX.; yet
+I do not wish the Amalfians to be deprived of an honour so great as that of
+having first made the construction common in the Mediterranean Sea.
+Goropius[16] attributes the discovery to the Cimbri or Teutons, forsooth
+because the names of the thirty-two winds inscribed on the compass are
+pronounced in the German tongue by all ship-masters, whether they be
+French, British, or Spaniards; but the Italians describe them in their own
+vernacular. Some think that Solomon, king of Judaea, was acquaint with the
+use of the mariners' compass, and made it known to his ship-masters in the
+long voyages when they brought back such a power of gold from the West
+Indies: whence also, from the Hebrew word _Parvaim_[17], Arias Montanus
+maintains that the gold-abounding regions of Peru are named But it is more
+likely to have come from the coast of lower Aethiopia, from the region of
+Cephala, as others relate. Yet that account seems to be less true, inasmuch
+as the Phoenicians, on the frontier of Judaea, who were most skilled in
+navigation in former ages (a people whose talents, work, and counsel
+Solomon made use of in constructing ships and in the actual expeditions, as
+well as in other operations), were ignorant of magnetick aid, the art of
+the mariners' compass: For had it been in use amongst them, without doubt
+the Greeks and also Italians and all barbarians would have understood a
+thing so necessary and made famous by common use; nor could matters of much
+repute, very easily known, and so highly requisite ever have perished in
+oblivion; but either the learning would have been handed down to posterity,
+or some memorial of it would be extant in writing. Sebastian Cabot was the
+first to discover that the magnetick iron varied[18]. Gonzalus Oviedus[19]
+is the first to write, as he does in the _Historia_, that in the south of
+the Azores it does not vary. Fernelius in his book _De Abditis Rerum
+Causis_ says that in the loadstone there is a hidden and abstruse cause,
+elsewhere calling it celestial; and he brings forth nothing but the unknown
+by means of what is still more unknown. {5} For clumsy, and meagre, and
+pointless is his inquiry into hidden causes. The ingenious Fracastorio, a
+distinguished philosopher, in seeking the reason for the direction of the
+loadstone, feigns Hyperborean magnetick mountains attracting magnetical
+things of iron: this view, which has found acceptance in part by others, is
+followed by many authors and finds a place not in their writings only, but
+in geographical tables, marine charts, and maps of the globe: dreaming, as
+they do, of magnetick poles and huge rocks, different from the poles of the
+earth. More than two hundred years earlier than Fracastorio there exists a
+little work, fairly learned for the time, going under the name of one Peter
+Peregrinus[20], which some consider to have originated from the views of
+Roger Bacon, the Englishman of Oxford: In which book causes for magnetick
+direction are sought from the poles of the heaven and from the heaven
+itself. From this Peter Peregrinus, Johannes Taisnier of Hainault[21]
+extracted materials for a little book, and published it as new. Cardan
+talks much of the rising of the star in the tail of the Greater Bear, and
+has attributed to its rising the cause of the variation: supposing that the
+variation is always the same, from the rising of the star. But the
+difference of the variation according to the change of position, and the
+changes which occur in many places, and are even irregular in southern
+regions, preclude the influence of one particular star at its northern
+rising. The College of Coimbra[22] seeks the cause in some part of the
+heaven near the pole: Scaliger in section CXXXI. of his _Exercitationes_ on
+Cardan suggests a heavenly cause unknown to himself, and terrestrial
+loadstones nowhere yet discovered. A cause not due to those sideritic
+mountains named above, but to that power which fashioned them, namely that
+portion of the heaven which overhangs that northern point. This view is
+garnished with a wealth of words by that erudite man, and crowned with many
+marginal subtilities; but with reasonings not so subtile. Martin Cortes[23]
+considers that there is a place of attraction beyond the poles, which he
+judges to be the moving heavens. One Bessardus[24], a Frenchman, with no
+less folly notes the pole of the zodiack. Jacobus Severtius[25], of Paris,
+while quoting a few points, fashions new errors as to loadstones of
+different parts of the earth being different in direction: and also as to
+there being eastern and western parts of the loadstone. Robert Norman[26],
+an Englishman, fixes a point and region respective, not attractive; to
+which the magnetical iron is collimated, but is not itself attracted.
+Franciscus Maurolycus[27] treats of a few problems on the loadstone, taking
+the trite views of others, and avers that the variation is due to a certain
+magnetical island mentioned by Olaus Magnus[28]. Josephus Acosta[29],
+though quite ignorant about the loadstone, nevertheless pours forth vapid
+talk upon the loadstone. Livio Sanuto[30] in his Italian _Geographia_,
+discusses at length the question whether the prime magnetick {6} meridian
+and the magnetick poles are in the heavens or in the earth; also about an
+instrument for finding the longitude: but through not understanding
+magnetical nature, he raises nothing but errors and mists in that so
+important notion. Fortunius Affaytatus[31] philosophizes foolishly enough
+on the attraction of iron, and its turning to the poles. Most recently,
+Baptista Porta[32], no ordinary philosopher, in his _Magia Naturalis_, has
+made the seventh book a custodian and distributor of the marvels of the
+loadstone; but little did he know or ever see of magnetick motions; and
+some things that he noted of the powers which it manifested, either learned
+by him from the Reverend Maestro Paolo, the Venetian[33], or evolved from
+his own vigils, were not so well discovered or observed; but abound in
+utterly false experiments, as will be clear in due place: still I deem him
+worthy of high praise for having attempted so great a subject (as he has
+done with sufficient success and no mean result in many other instances),
+and for having given occasion for further research. All these
+philosophizers of a previous age, philosophizing about attraction from a
+few vague and untrustworthy experiments, drawing their arguments from the
+hidden causes of things; and then, seeking for the causes of magnetick
+directions in a quarter of the heavens, in the poles, the stars,
+constellations, or in mountains, or rocks, space, atoms, attractive or
+respective points beyond the heavens, and other such unproven paradoxes,
+are whole horizons wrong, and wander about blindly. And as yet we have not
+set ourselves to overthrow by argument those errors and impotent reasonings
+of theirs, nor many other fables told about the loadstone, nor the
+superstitions of impostors and fabulists: for instance, Franciscus
+Rueus'[34] doubt whether the loadstone were not an imposture of evil
+spirits: or that, placed underneath the head of an unconscious woman while
+asleep, it drives her away from the bed if an adulteress: or that the
+loadstone is of use to thieves by its fume and sheen, being a stone born,
+as it were, to aid theft: or that it opens bars and locks, as Serapio[35]
+crazily writes: or that iron held up by a loadstone, when placed in the
+scales, added nothing to the weight of the loadstone, as though the gravity
+of the iron were absorbed by the force of the stone: or that, as Serapio
+and the Moors relate, in India there exist certain rocks of the sea
+abounding in loadstone, which draw out all the nails of the ships which are
+driven toward them, and so stop their sailing; which fable Olaus Magnus[36]
+does not omit, saying that there are mountains in the north of such great
+powers of attraction, that ships are built with wooden pegs, lest the iron
+nails should be drawn from the timber as they passed by amongst the
+magnetick crags. Nor this: that a white loadstone may be procured as a love
+potion: or as Hali Abbas[37] thoughtlessly reports, that if held in the
+hand it will cure gout and spasms: Or that it makes one acceptable and in
+favour with princes, or eloquent, as Pictorio[38] has {7} sung; Or as
+Albertus Magnus[39] teaches, that there are two kinds of loadstones, one
+which points to the North, the other to the South: Or that iron is directed
+toward the Northern stars by an influence imparted by the polar stars, even
+as plants follow the sun, as Heliotrope does: Or that there is a
+magnet-stone situated under the tail of the Greater Bear, as Lucas Gauricus
+the Astrologer stated: He would even assign the loadstone, like the
+Sardonyx and onyx, to the planet Saturn, yet at the same time he assigns it
+with the adamant, Jasper, and Ruby, to Mars; so that it is ruled by two
+planets. The loadstone moreover is said by him to pertain to the sign
+Virgo; and he covers many such shameful pieces of folly with a veil of
+mathematical erudition. Such as that an image of a bear is engraved on a
+loadstone when the Moon faces towards the north, so that when hung by an
+iron wire it may conciliate the influence of the celestial Bear, as
+Gaudentius Merula[40] relates: Or that the loadstone drew iron and directed
+it to the north, because it is superior in rank to iron, at the Bear, as
+Ficinus writes, and Merula repeats: Or that by day it has a certain power
+of attracting iron, but by night the power is feeble, or rather null: Or
+that when weak and dulled the virtue is renewed by goats' blood, as
+Ruellius[41] writes: Or that Goats' blood sets a loadstone free from the
+venom of a diamond, so that the lost power is revived when bathed in goats'
+blood by reason of the discord between that blood and the diamond: Or that
+it removed sorcery from women, and put to flight demons, as Arnaldus de
+Villanova dreams: Or that it has the power to reconcile husbands to their
+wives, or to recall brides to their husbands, as Marbodeus Gallus[42],
+chorus-leader of vanities, teaches: Or that in a loadstone pickled in the
+salt of a sucking fish[43] there is power to pick up gold which has fallen
+into the deepest wells, according to the narratives of Caelius Calcagninus.
+With such idle tales and trumpery do plebeian philosophers delight
+themselves and satiate readers greedy for hidden things, and unlearned
+devourers of absurdities: But after the magnetick nature shall have been
+disclosed by the discourse that is to follow, and perfected by our labours
+and experiments, then will the hidden and abstruse causes of so great an
+effect stand out, sure, proven, displayed and demonstrated; and at the same
+time all darkness will disappear, and all error will be torn up by the
+roots and will lie unheeded; and the foundations of a grand magnetick
+philosophy which have been laid will appear anew, so that high intellects
+may be no further mocked by idle opinions. Some learned men there are who
+in the course of long voyages have observed the differences of magnetick
+variation: the most scholarly Thomas Hariot[44], Robert Hues, Edward
+Wright, Abraham Kendall, all Englishmen; Others there are who have invented
+and produced magnetical instruments, and ready methods of observation,
+indispensable for sailors and to those travelling afar: {8} as William
+Borough[45] in his little book on the _Variation of the Compass_ or
+Magneticall Needle, William Barlowe[46] in his _Supply_, Robert Norman in
+his _Newe Attractive_. And this is that Robert Norman[47] (a skilful seaman
+and ingenious artificer) who first discovered the declination of the
+magnetick needle. Many others I omit wittingly; modern Frenchmen, Germans,
+and Spaniards, who in books written for the most part in their native
+tongues either misuse the placets of others, and send them forth furbished
+with new titles and phrases as tricky traders do old wares with
+meretricious ornaments; or offer something not worthy of mention even: and
+these lay hands on some work filched from other authors and solicit some
+one as their patron, or go hunting after renown for themselves among the
+inexperienced and the young; who in all branches of learning are seen to
+hand on errors and occasionally add something false of their own.
+
+       *       *       *       *       *
+
+
+CHAP. II.
+
+Magnet Stone, of what kind it is, and its
+_discovery._
+
+Loadstone, the stone which is commonly called the Magnet, derives its name
+either from the discoverer (though he was not Pliny's fabulous
+herdsman[48], quoted from Nicander, the nails of whose shoes and the tip of
+whose staff stuck fast in a magnetick field while he pastured his flocks),
+or from the region of Magnesia in Macedonia, rich in loadstones: Or else
+from the city Magnesia in Ionia in Afia Minor, near the river Maeander.
+Hence Lucretius says,
+
+          _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 {9} 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 Aethiopia, Macedonia, Boeotia, 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 Boeotia 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 {10} 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 {11} 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 Aethiopia, as was formerly Zimiri, of
+which Pliny makes mention. In Asia Minor around Alexandria and the Troad;
+in Macedonia, Boeotia, 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] [Greek: heraklios], as by Theophrastus, and [Greek: magnetis];
+and [Greek: magnes], as by Euripides, as quoted by Plato in the _Io_: by
+Orpheus[53] too [Greek: magneosa], and [Greek: siderites] 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 [Greek: siderites] from its virtue of attracting iron: the adamant
+is called [Greek: siderites] from the brilliancy of polished iron.
+Aristotle designates it merely by the name of _the stone_:[58] [Greek:
+Eoike de kai thales ex hon apomnemoneuousi, kinetikon ti ten psuchen
+hupolabein, eiper ton lithon ephe psuchen echein, hoti ton sideron kinei]:
+_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 laminae (like specular
+stone)[59], it differs in form: in German _Katzensilber_ and _Talke_[60].
+
+       *       *       *       *       *
+
+
+{12} CHAP. III.
+
+The Loadstone has parts distinct in their natural
+_power, & poles conspicuous for their property._
+
+The stone itself manifests many qualities which, though known afore this,
+yet, not having been well investigated, are to be briefly indicated in the
+first place so that students may understand the powers of loadstone and
+iron, and not be troubled at the outset through ignorance of reasonings and
+proofs. In the heaven astronomers assign a pair of poles for each moving
+sphere: so also do we find in the terrestrial globe natural poles
+preeminent in virtue, being the points that remain constant in their
+position in respect to the diurnal rotation, one tending to the Bears and
+the seven stars; the other to the opposite quarter of the heaven. In like
+manner the loadstone has its poles, by nature northern and southern, being
+definite and determined points set in the stone, the primary boundaries of
+motions and effects, the limits and governors of the many actions and
+virtues. However, it must be understood that the strength of the stone does
+not emanate from a mathematical point, but from the parts themselves, and
+that while all those parts in the whole belong to the whole, the nearer
+they are to the poles of the stone the stronger are the forces they acquire
+and shed into other bodies: these poles are observant of the earth's poles,
+move toward them, and wait upon them. Magnetick poles can be found in every
+magnet, in the powerful and mighty (which Antiquity used to call the
+masculine) as well as in the weak, feeble and feminine; whether its figure
+is due to art or to chance, whether long, flat, square, three-cornered,
+polished; whether rough, broken, or unpolished; always the loadstone
+contains and shows its poles. * But since the spherical form, which is also
+the most perfect, agrees best with the earth, being a globe, and is most
+suitable for use and experiment, we accordingly wish our principal
+demonstrations by the stone to be made with a globe-shaped magnet as being
+more perfect and adapted for the purpose. Take, then, a powerful loadstone,
+solid, of a just size, uniform, hard, without flaw[61]; make of it a globe
+upon the turning tool used for rounding crystals and some other stones, or
+with other tools as the material and firmness of the stone requires, for
+sometimes it is difficult to be worked. The stone thus perpared is a true,
+homogeneous offspring of the earth and of the same shape with it:
+artificially possessed of the orbicular form which nature granted from the
+beginning to the common mother earth: and it is a physical corpuscle imbued
+with many virtues, by {13} means of which many abstruse and neglected
+truths in philosophy buried in piteous darkness may more readily become
+known to men. This round stone is called by us a [Greek: mikroge] or
+_Terrella_[62]. To find, then, the poles conformable to the earth's, take
+the round stone in hand, and place upon the stone a needle or wire of iron:
+the ends of the iron move upon their own centre and suddenly stand still.
+Mark the stone with ochre or with chalk where the wire lies and sticks:
+move the middle or centre of the wire to another place, and so on to a
+third and a fourth, always marking on the stone along the length of the
+iron where it remains at rest: those lines show the meridian circles, or
+the circles like meridians on the stone, or terrella, all of which meet as
+will be manifest at the poles of the stone. By the circles thus continued
+the poles are made out, the Boreal as well as the southern, and in the
+middle space betwixt these a great circle may be drawn for an aequator,
+just as Astronomers describe them in the heavens and on their own globes,
+or as Geographers do on the terrestrial globe: for that line so drawn on
+this our terrella is of various uses in our demonstrations and experiments
+magnetical. Poles are also found in a round stone by a versorium, a piece
+of iron touched with a loadstone, and placed upon a needle or point firmly
+fixed on a foot so as to turn freely about in the following way:[63]
+
+[Illustration]
+
+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 {14} 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_.
+
+One pole of the earth turns toward the constellation of the Cynosure, and
+constantly regards a fixed point in the heaven (except so far as it changes
+by the fixed stars being shifted in longitude, which motion we recognize as
+existing in the earth, as we shall hereafter prove): While the other pole
+turns to the opposite face of heaven, unknown to the ancients, now visible
+on long voyages, and adorned with multitudinous stars: In the same way the
+loadstone has the property and power of directing itself North and South
+(the earth herself consenting and contributing force thereto) according to
+the conformation of nature, which arranges the movements of the stone
+towards its native situation. Which thing is proved thus: Place a magnetick
+stone (after finding the poles) in a round wooden vessel, a Bowl or dish,
+at the same time place it together with the vessel (like a sailor in a
+skiff) upon water in some large vessel or cistern, so that it may be able
+to float freely in the middle, nor touch the edge of it, and where the air
+is not disturbed by winds, which would thwart the natural movement of the
+stone. Hereupon the stone placed as it were in a ship, in the middle of the
+surface of the still and unruffled water, will at once put itself in motion
+along with the vessel that carries it, and revolve circularly, until its
+austral pole points to the north, and its boreal pole to the south. For it
+reverts from the contrary position to the poles: and although by the first
+too-vehement impulse it over-passes the poles; yet after returning again
+and again, it rests at length at the poles, or at the meridian (unless
+because of local reasons it is diverted some little from those points, or
+from the meridional line, by some sort of variation[66], the cause of which
+we will hereafter state). However often you move it away from its place, so
+often by virtue of nature's noble dower does it seek again those sure and
+{15} determined goals; and this is so, not only if the poles have been
+disposed in the vessel evenly with the plane of the horizon, but also in
+the case of one pole, whether austral or boreal, being raised in the vessel
+ten, or twenty, or thirty, or fifty or eighty degrees, above * the plane of
+the horizon, or lowered beneath it: Still you shall see the boreal part of
+the stone seek the south, and the austral part seek the north; So much so
+that if the pole of the stone shall be only one degree distant from the
+Zenith and highest point of the heaven, in the case of a spherical stone,
+the whole stone revolves until the pole occupies its own site; though not
+in the absolutely direct line, it will yet tend toward those parts, and
+come to rest in the meridian of the directive action. With a like impulse
+too it is borne if the austral pole have been raised toward the upper
+quarters, the same as if the Boreal had been exalted above the Horizon. But
+it is always to be noted that, though there are various kinds of unlikeness
+in the stones, and one loadstone may far surpass another in virtue and
+efficiency; yet all hold to the same limits, and are borne toward the same
+points. Further it is to be remembered * that all who before our time wrote
+of the poles of the stone, and all the craftsmen and navigators, have been
+very greatly in error in considering the part of the stone which tended to
+the north as the north pole of the stone, and that which verged toward the
+south, the south pole, which we shall hereafter prove to be false. So badly
+hitherto hath the whole magnetick philosophy been cultivated, even as to
+its foundation principles.
+
+       *       *       *       *       *
+
+
+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_.
+
+First of all we must declare, in familiar language, what are the apparent
+and common virtues of the stone; afterward numerous subtilities, hitherto
+abstruse and unknown, hidden in obscurity, are to be laid open, and the
+causes of all these (by the unlocking of nature's secrets) made evident, in
+their place, by fitting terms and devices. It is trite and commonplace that
+loadstone draws iron; in the same way too does loadstone attract loadstone.
+Place the stone which you have seen to have poles clearly distinguished,
+and marked austral and boreal, in its vessel so as to float; and let the
+poles be rightly arranged with respect to the plane of the horizon, or, at
+any rate not much raised or awry: hold in your hand another stone the poles
+of which are also known; in {16} such a way that its austral pole may be
+toward the boreal pole of the one that is swimming, and near it, sideways:
+for the floating stone forthwith follows the other stone (provided it be
+within its force and dominion) and does not leave off nor forsake it until
+it adhaeres; unless by withdrawing your hand, you cautiously avoid contact.
+In like manner if you set the boreal pole of the one you hold in your hand
+opposite the austral pole of the swimming stone, they rush together and
+follow each other in turn. For contrary poles allure contrary. If, however,
+you apply in the same way the northern to the northern, and the austral to
+the austral pole, the one stone puts the other to flight, and it turns
+aside as though a pilot were pulling at the helm and it makes sail in the
+opposite ward as one that ploughs the sea, and neither stands anywhere, nor
+halts, if the other is in pursuit. For stone disposeth stone; the one turns
+the other around, reduces it to range, and brings it back to harmony with
+itself. When, however, they come together and are conjoined according to
+the order of nature, they cohaere firmly mutually. For instance, if you
+were to set the boreal pole of that stone which is in your hand before the
+tropic of Capricorn of a round floating loadstone (for it will be well to
+mark out on the round stone, that is the terrella, the mathematical circles
+as we do on a globe itself), or before any point between the aequator and
+the austral pole; at once the swimming stone revolves, and so arranges
+itself that its austral pole touches the other's boreal pole, and forms a
+close union with it. In the same way, again, at the other side of the
+aequator, with the opposite poles, you may produce similar results; and
+thus by this art and subtilty we exhibit attraction, repulsion, and
+circular motion for attaining a position of agreement and for declining
+hostile encounters. Moreover 'tis in one and the same stone that we are
+thus able to demonstrate all these things and also how the same part of one
+stone may on division become either boreal or austral. Let A D be an oblong
+stone, in which A is the northern, D the southern pole; cut this into two
+equal parts, then set part A in its vessel on the water[67], so as to
+float.
+
+[Illustration]
+
+{17} 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 Aethiopian only,
+as Pliny supposed. The Aethiopian 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.
+
+       *       *       *       *       *
+
+
+{18} CHAP. VI.
+
+Loadstone attracts the ore of iron, as well as iron
+_proper, smelted and wrought_.
+
+Principal and manifest among the virtues of the * magnet, so much and so
+anciently commended, is the attraction of iron; for Plato states that the
+magnet, so named by Euripides, allures iron, and that it not only draws
+iron rings but also indues the rings with power to do the same as the
+stone; to wit, draw other rings, so that sometimes a long chain of iron
+objects, nails or rings is formed, some hanging from others. The best iron
+(like that which is called _acies_ from its use, or _chalybs_ from the
+country of the Chalybes) is best and strongly drawn by a powerful
+loadstone; whereas the less good sort, which is impure, rusty, and not
+thoroughly purged from dross, and not wrought in second furnaces, is more
+feebly drawn; and yet more weakly when covered and defiled with thick,
+greasy, and sluggish humours. It also draws ores of iron, those that are
+rich and of iron colour; the poorer and not so productive ores it does not
+attract, except they be prepared with some art. A loadstone loses some
+attractive virtue, and, as it were, pines away with age, if exposed too
+long to the open air instead of being laid in a case with filings or scales
+of iron. Whence it should be buried in such materials; for there is nothing
+that plainly resists this exhaustless virtue which does not destroy the
+form of the body, or corrode it; not even if a thousand adamants were
+conjoined. Nor do I consider that there is any such thing as the
+Theamedes[69], or that it has a power opposite to that of the loadstone.
+Although Pliny, that eminent man and prince of compilers (for it is what
+others had seen and discovered, not always or mainly his own observations,
+that he has handed down to posterity) has copied from others the fable now
+made familiar by repetition: That in India there are two mountains near the
+river Indus; the nature of one being to hold fast all that is iron, for it
+consists of loadstone; the other's nature being to repel it, for it
+consists of the Theamedes. Thus if one had iron nails in one's boots, one
+could not tear away one's foot on the one mountain, nor stand still on the
+other. Albertus Magnus writes that a loadstone had been found in his day
+which with one part drew to itself iron, and repelled it with its other
+end; but Albertus observed the facts badly; for every loadstone attracts
+with one end iron that has been touched with a loadstone, and drives it
+away with the other; and draws iron that been touched with a loadstone more
+powerfully than iron that has not been so touched.
+
+       *       *       *       *       *
+
+
+{19} CHAP. VII.
+
+What Iron is, and of what substance,
+_and its uses._
+
+For that now we have declared the origin and nature of the loadstone, we
+think it necessary first to add a history of iron and to indicate the
+hitherto unknown forces of iron, before this our discourse goes on to the
+explanation of magnetick difficulties and demonstrations, and to deal with
+the coitions and harmonies of loadstone with iron. Iron is by all reckoned
+in the class of metals, and is a metal livid in colour, very hard, glows
+red-hot before it melts, being most difficult of fusion, is beaten out
+under the hammer, and is very resonant. Chemists say that if a bed of fixed
+earthy sulphur be combined with fixed earthy quicksilver, and the two
+together are neither pure white but of a livid whiteness, if the sulphur
+prevail, iron is formed. For these stern masters of metals who by many
+inventions twisting them about, pound, calcine, dissolve, sublime, and
+precipitate, decide that this metal, both on account of the earthy sulphur
+and of the earthy mercury, is more truly a son of the earth than any other;
+they do not even think gold or silver, lead, tin, or copper itself so
+earthy; for that reason it is not smelted except in the hottest furnaces,
+with bellows; and when thus fused, on having again grown hard it is not
+melted again without heavy labour; but its slag with the utmost difficulty.
+It is the hardest of metals, subduing and breaking all things, by reason of
+the strong concretion of the more earthy matter. Wherefore we shall better
+understand what iron is, when we shall declare what are the causes and
+substance of metals, in a different way from those who before our time have
+considered them. Aristotle takes the material of the metals to be vapour.
+The chemists in chorus pronounce their actual elements to be sulphur and
+quicksilver. Gilgil Mauritanus gives it as ashes moistened with water.
+Georgius Agricola makes it out to be water and earth mixed; nor, to be
+sure, is there any difference between his opinion and the position taken by
+Mauritanus. But ours is that metals arise and effloresce at the summits of
+the earth's globe, being distinguished each by its own form, like some of
+the other substances dug out of it, and all bodies around us. The earth's
+globe does not consist of ashes or inert dust. Nor is fresh water an
+element, but a more simple consistency of evaporated fluids of the earth.
+Unctuous bodies, fresh water devoid of properties, quicksilver and sulphur,
+none of these are principia of metals: these latter, {20} things are the
+results of a different nature, they are neither constant nor antecedent in
+the course of the generation of metals. The earth emits various humours,
+not begotten of water nor of dry earth, nor from mixtures of these, but
+from the substance of the earth itself: these humours are not distinguished
+by contrary qualities or substance, nor is the earth a simple substance, as
+the Peripateticks dream. The humours proceed from vapours sublimated from
+great depths; all waters are extracts and, as it were, exudations from the
+earth. Rightly then in some measure does Aristotle make out the matter of
+metals to be that exhalation which in continuance thickens in the lodes of
+certain soils: for the vapours are condensed in places which are less hot
+than the spot whence they issued, and by help of the nature of the soils
+and mountains, as in a womb, they are at fitting seasons congealed and
+changed into metals: but it is not they alone which form ores, but they
+flow into and enter a more solid material, and so form metals. So when this
+concreted matter has settled down in more temperate beds, it begins to take
+shape in those tepid places, just as seed in the warm womb, or as the
+embryo acquires growth: sometimes the vapour conjoins with suitable matter
+alone: hence some metals are occasionally though rarely dug up native, and
+come into existence perfect without smelting: but other vapours which are
+mixed with alien soils require smelting in the way that the ores of all
+metals are treated, which are rid of all their dross by the force of fires,
+and being fused flow out metallick, and are separated from earthy
+impurities but not from the true substance of the earth. But in so far as
+that it becomes gold, or silver, or copper, or any other of the existing
+metals, this does not happen from the quantity or proportion of material,
+nor from any forces of matter, as the Chemists fondly imagine; but when the
+beds and region concur fitly with the material, the metals assume forms
+from the universal nature by which they are perfected; in the same manner
+as all the other minerals, plants, and animals whatever: otherwise the
+species of metals would be vague and undefined, which are even now turned
+up in such scanty numbers that scarce ten kinds are known. Why, however,
+nature has been so stingy as regards the number of metals, or why there
+should be as many as are known to man, it is not easy to explain; though
+the simple-minded and raving Astrologers refer the metals each to its own
+planet. But there is no agreement of the metals with the planets, nor of
+the planets with the metals, either in numbers or in properties. For what
+connexion is there of iron with Mars? unless it be that from the former
+numerous instruments, particularly swords and engines of war, are
+fashioned. What has copper to do with Venus? or how does tin, or how does
+spelter correspond with Jupiter? They should rather be dedicated to Venus.
+But this is old wives' talk. Vapour is then a remote cause in the
+generation of the metals; the fluid condensed from {21} vapours is a more
+proximate one, like the blood and semen in the generation of animals. But
+those vapours and juices from vapours pass for the most part into bodies
+and change them into marcasites and are carried into lodes (for we have
+numerous cases of wood so transmuted), the fitting matrices of bodies,
+where they are formed as metals. They enter most often into the truer and
+more homogeneal substance of the globe, and in the process of time a vein
+of iron results; loadstone is also produced, which is nought else than a
+noble kind of iron ore: and for this reason, and on account of its
+substance being singular, alien from all other metals, nature very rarely,
+if ever, mixes with iron any other metal, while the other metals are very
+often minutely mixed, and are produced together. Now when that vapour or
+those juices happen to meet, in fitting matrices, with efflorescences
+deformed from the earth's homogenic substance, and with divers precipitates
+(the forms working thereto), the remainder of the metals are generated (a
+specifick nature affecting the properties in that place). For the hidden
+primordial elements of metals and stones lie concealed in the earth, as
+those of herbs and plants do in its outer crust. For the soil dug out of a
+deep well, where would seem to be no suspicion of a conception of seed,
+when placed on a very high tower, produces, by the incubation of sun and
+sky, green herbage and unbidden weeds; and those of the kind which grow
+spontaneously in that region, for each region produces its own herbs and
+plants, also its own metals.
+
+  _[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 {22} 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 {23} 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 [Greek: stomoma]; 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 {24} (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.
+
+       *       *       *       *       * {25}
+
+
+CHAP. VIII.
+
+In what countries and districts iron
+_originates._
+
+Plenty of iron mines exist everywhere, both those of old time recorded in
+early ages by the most ancient writers, and the new and modern ones. The
+earliest and most important seem to me to be those of Asia. For in those
+countries which abound naturally in iron, governments and the arts
+flourished exceedingly, and things needful for the use of man were
+discovered and sought after. It is recorded to have been found about
+Andria, in the region of the Chalybes near the river Thermodon in Pontus;
+in the mountains of Palestine which face Arabia; in Carmania: in Africa
+there was a mine of iron in the Isle of Meroe; in Europe in the hills of
+Britain, as Strabo writes; in Hither Spain, in Cantabria. Among the
+Petrocorii and Cubi Biturges[77] (peoples of Gaul), there were worksteads
+in which iron used to be wrought. In greater Germany near Luna, as recorded
+by Ptolemy; Gothinian iron is mentioned by Cornelius Tacitus; Noric iron is
+celebrated in the verses of poets; and Cretan, and that of Euboea; many
+other iron mines were passed over by these writers or unknown to them; and
+yet they were neither poor nor scanty, but most extensive. Pliny[78] says
+that Hither Spain and all the district from the Pyrenees is ferruginous,
+and on the part of maritime Cantabria washed by the Ocean (says the same
+writer) there is (incredible to relate) a precipitously high mountain
+wholly composed of this material. The most ancient mines were of iron
+rather than of gold, silver, copper or lead; since mainly this was sought
+because of the demand; and also because in every district and soil they
+were easy to find, not so deep-lying, and less beset by difficulties. If,
+however, I were to enumerate modern iron workings, and those of this age
+and over Europe only, I should have to write a large and bulky volume, and
+sheets of paper would run short quicker than the iron, and yet for one
+sheet they could furnish a thousand worksteads. For amongst minerals, no
+material is so ample; all metals, and all stones distinct from iron, are
+outdone by ferric and ferruginous matter. For you will not readily find any
+region, and scarcely any country district over the whole of Europe (if you
+search at all deeply), that does not either produce a rich and abundant
+vein of iron or some soil containing or slightly charged with ferruginous
+stuff; and that this is {26} true any expert in the arts of metals and
+chemistry will easily find. Beside that which has ferruginous nature, and
+the metallick lode, there is another ferric substance which does not yield
+the metal in this way because its thin humour is burnt out by fierce fires,
+and it is changed into an iron slag like that which is separated from the
+metal in the first furnaces. And of this kind is all clay and argillaceous
+earth, such as that which apparently forms a large part of the whole of our
+island of Britain: all of which, if subjected very vehemently to intense
+heat, exhibits a ferric and metallick body, or passes into ferric vitreous
+matter, as can be easily seen in buildings in bricks baked from clay,
+which, when placed next the fires in the open kilns (which our folk call
+_clamps_)[79] and burned, present an iron vitrification, black at the other
+end. Moreover all those earths as prepared are drawn by the magnet, and
+like iron are attracted by it. So perpetual and ample is the iron offspring
+of the terrestrial globe. Georgius Agricola says that almost all
+mountainous regions are full of its ores, while as we know a rich iron lode
+is frequently dug in the open country and plains over nearly the whole of
+England and Ireland; in no other wise than as, says he, iron is dug out of
+the meadows at the town of Saga in pits driven to a two-foot depth. Nor are
+the West Indies without their iron lodes, as writers tell us; but the
+Spaniards, intent upon gold, neglect the toilsome work of iron-founding,
+and do not search for lodes and mines abounding in iron. It is probable
+that nature and the globe of the earth are not able to hide, and are
+evermore bringing to the light of day, a great mass of inborn matter, and
+are not invariably obstructed by the settling of mixtures and
+efflorescences at the earth's surface. It is not only in the common mother
+(the terrestrial globe) that iron is produced, but sometimes also in the
+air from the earth's exhalations, in the highest clouds. It rained iron in
+Lucania, the year in which M. Crassus was slain. The tale is told, too,
+that a mass of iron, like slag, fell from the air in the Nethorian forest,
+near Grina, and they narrate that the mass was many pounds in weight; so
+that it could neither be conveyed to that place, on account of its weight,
+nor be brought away by cart, the place being without roads. This happened
+before the civil war waged between the rival dukes in Saxony. A similar
+story, too, comes to us from Avicenna. It once rained iron in the
+Torinese[80], in various places (Julius Scaliger telling us that he had a
+piece of it in his house), about three years before that province was taken
+over by the king. In the year 1510 in the country bordering on the river
+Abdua (as Cardan writes[81] in his book _De Rerum Varietate_) there fell
+from the sky 1200 stones, one weighing 120 pounds, another 30 or 40 pounds,
+of a rusty iron colour and remarkably hard. These occurrences being rare
+are regarded as portents, like the showers of earth and stones mentioned in
+Roman history. But that it ever rained other metals is not {27} recorded;
+for it has never been known to rain from the sky gold, silver, lead, tin,
+or spelter[82]. Copper, however, has been at some time noticed to fall from
+the sky, and this is not very unlike iron; and in fact cloud-born iron of
+this sort, or copper, are seen to be imperfectly metallick, incapable of
+being cast in any way, or wrought with facility. For the earth hath of her
+store plenty of iron in her highlands, and the globe contains the ferric
+and magnetick element in rich abundance. The exhalations forcibly derived
+from such material may well become concreted in the upper air by the help
+of more powerful causes, and hence some monstrous progeny of iron be
+begotten.
+
+       *       *       *       *       *
+
+
+CHAP. IX.
+
+Iron ore attracts iron ore.
+
+From various substances iron (like all the rest of the * metals) is
+extracted: such substances being stones, earth, and similar concretions
+which miners call veins because it is in veins[83], as it were, that they
+are generated. We have spoken above of the variety of these veins. If a
+properly coloured ore of iron and a rich one (as miners call it) is placed,
+as soon as mined, upon water in a bowl or any small vessel (as we have
+shown before in the case of a loadstone), it is attracted by a similar
+piece of ore brought near by hand, yet not so powerfully and quickly as one
+loadstone is drawn by another loadstone, but slowly and feebly. Ores of
+iron that are stony, cindery, dusky, red, and several more of other
+colours, do not attract one another mutually, nor are they attracted by the
+loadstone itself, even by a strong one, no more than wood, or lead, silver,
+or gold. Take those ores and burn, or rather roast them, in a moderate
+fire, so that they are not suddenly split up, or fly asunder, keeping up
+the fire ten or twelve hours, and gently increasing it, then let them grow
+cold, skill being shown in the direction in which they are placed: These
+ores thus prepared a loadstone will now draw, and they now show a mutual
+sympathy, and when skilfully arranged run together by their own forces.
+
+       *       *       *       *       *
+
+
+{28}
+
+CHAP. X.
+
+*
+
+Iron ore has poles, and acquires them, and settles
+_itself toward the poles of the universe_.
+
+Deplorable is man's ignorance in natural science, and modern philosophers,
+like those who dream in darkness, need to be aroused, and taught the uses
+of things and how to deal with them, and to be induced to leave the
+learning sought at leisure from books alone, and that is supported only by
+unrealities of arguments and by conjectures. For the knowledge of iron
+(than which nothing is in more common use), and that of many more
+substances around us, remains unlearned; iron, a rich ore of which, placed
+in a vessel upon water, by an innate property of its own directs itself,
+just like the loadstone, North and South, at which points it rests, and to
+which, if it be turned aside, it reverts by its own inherent vigour. But
+many ores, less perfect in their nature, which yet contain amid stone or
+earthy substances plenty of iron, have no such motion; but when prepared by
+skilful treatment in the fires, as shown in the foregoing chapter, they
+acquire a polar vigour (which we call verticity[84]); and not only the iron
+ores in request by miners, but even earth merely charged with ferruginous
+matter, and many rocks, do in like manner tend and lean toward those
+portions of the heavens, or more truly of the earth, if they be skilfully
+placed, until they reach the desired location, in which they eagerly
+repose.
+
+       *       *       *       *       *
+
+
+{29} CHAP. XI.
+
+*
+
+Wrought Iron, not excited by a loadstone,
+_draws iron_.
+
+From the ore, which is converted, or separated, partly into metal, partly
+into slag, by the intense heat of fires, iron is smelted in the first
+furnaces in a space of eight, ten, or twelve hours, and the metal flows
+away from the dross and useless matter, forming a large and long mass,
+which being subjected to a sharp hammering is cut into parts, out of which
+when reheated in the second hearth of the forge, and again placed on the
+anvil, the smiths fashion quadrangular lumps, or more specially bars which
+are bought by merchants and blacksmiths, from which in smithies usually it
+is the custom to fashion the various implements. This iron we term
+_wrought_, and its attraction by the loadstone is manifest to all. But we,
+by more carefully trying everything[85], have found out that iron merely,
+by itself alone, not excited by any loadstone, not charged by any alien
+forces, attracts other iron; though it does not so eagerly snatch and
+suddenly pluck at it as would a fairly strong loadstone; this you may know
+thus: A small piece of cork, the size of a hazel-nut, rounded, is traversed
+by an iron wire up to the middle of the wire: when set swimming on still
+water apply to one end of it, close (yet so as not to touch), the end of
+another iron wire; and wire draws wire, and one follows the other when
+slowly drawn back, and this goes on up to the proper boundaries. Let A be
+the cork with the iron wire, B one end of it raised a little above the
+surface of the water, C the end of the second wire, showing the way in
+which B is drawn by C. You may prove it in another way in a larger body.
+Let a long bright iron rod (such as is made for hangings and window
+curtains) be hung in balance by a slender silken cord: to one end of this
+as it rests in the air bring a small oblong mass of polished iron, with its
+proper {30} end at the distance of half a digit. The balanced iron turns
+itself to the mass; do you with the same quickness draw back the mass in
+your hand in a circular path about the point of equilibrium of the
+suspension; the end of the balanced iron follows after it, and turns in an
+orbit.
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+CHAP. XII.
+
+*
+
+A long piece of Iron, even though not excited by a
+_loadstone, settles itself toward North and South._
+
+Every good and perfect piece of iron, if drawn out in length, points North
+and South, just as the loadstone or iron rubbed with a magnetical body
+does; a thing that our famous philosophers have little understood, who have
+sweated in vain to set forth the magnetick virtues and the causes of the
+friendship of iron for the stone. You may experiment with either large or
+small iron works, and either in air or in water. A straight piece of iron
+six feet long of the thickness of your finger is suspended (in the way
+described in the foregoing chapter) in exact aequipoise by a strong and
+slender silken cord. But the cord should be cross-woven of several silk
+filaments, not twisted simply in one way; and it should be in a small
+chamber with all doors and windows closed, that the wind may not enter, nor
+the air of the room be in any way disturbed; for which reason it is not
+expedient that the trial should be made on windy days, or while a storm is
+brewing. For thus it freely follows its bent, and slowly moves until at
+length, as it rests, it points with its ends North and South, just as iron
+touched with a loadstone does in shadow-clocks, and in compasses, and in
+the mariners' compass. You will be able, if curious enough, to balance all
+at the same time by fine threads a number of small rods, or iron wires, or
+long pins with which women knit stockings; you will see that all of them at
+the same time are in accord, unless there be some error in this delicate
+operation: for unless you prepare everything fitly and skilfully, the
+labour will be void. Make trial of this thing in water also, which is done
+both more certainly and more easily. Let an iron wire two or three digits
+long, more or less, be passed through a round cork, so that it may just
+float upon water; and as soon as you have committed it to the waves, it
+turns upon its own centre, and one end tends to the North, the other to the
+South; the causes {31} of which you will afterwards find in the laws of the
+direction. This too you should understand, and hold firmly in memory, that
+* as a strong loadstone, and iron touched with the same, do not invariably
+point exactly to the true pole but to the point of the variation; so does a
+weaker loadstone, and so does the iron, which directs itself by its own
+forces only, not by those impressed by the stone; and so every ore of iron,
+and all bodies naturally endowed with something of the iron nature, and
+prepared, turn to the same point of the horizon, according to the place of
+the variation in that particular region (if there be any variation
+therein), and there abide and rest.
+
+       *       *       *       *       *
+
+
+CHAP. XIII.
+
+*
+
+Wrought iron has in itself certain parts Boreal and Austral:
+A magnetick vigour, verticity, and determinate
+_vertices, or poles_.
+
+Iron settles itself toward the North and South; not with one and the same
+point toward this pole or that: for one end of the piece of ore itself and
+one extremity also of a wrought-iron wire have a sure and constant
+destination to the North, the other to the South, whether the iron hang in
+the air, or float on water, be the iron large rods or thinner wires. Even
+if it be a little rod, or a wire ten or twenty or more ells in length; one
+end as a rule is Boreal, the other Austral. If you cut off part of that
+wire, and if the end of that divided part were Boreal, the other end (which
+was joined to it) will be Austral. Thus if you divide it into several
+parts, before making an experiment on the surface of water, you can
+recognize the vertex[86]. In all of them a Boreal end draws an Austral and
+repels a Boreal, and contrariwise, according to the laws magnetical. Yet
+herein wrought iron differs from the loadstone and from its own ore,
+inasmuch as in an iron ball of any size, such as those used for artillery
+or cannon, or bullets used for carbines or fowling-pieces, verticity is
+harder to acquire and is less apparent than in a piece of loadstone, or of
+ore itself, or than in a round loadstone. But in long and extended pieces
+of iron a power is at once discerned; the causes of which fact, and the
+methods by which it acquires its verticity and its poles without use of a
+loadstone, as well as the reasons for all the other obscure features of
+verticity, we shall set forth in describing the motion of direction.
+
+       *       *       *       *       *
+
+
+{32} CHAP. XIIII.
+
+Concerning other powers of loadstone, and its
+_medicinal properties_.
+
+Dioscorides prescribes loadstone to be given with sweetened water, three
+scruples' weight, to expel gross humours. Galen writes that a like quantity
+of bloodstone avails. Others relate that loadstone perturbs the mind and
+makes folk melancholick, and mostly kills. Gartias ab Horto[87] thinks it
+not deleterious or injurious to health. The natives of East India tell us,
+he says, that loadstone taken in small doses preserves youth. On which
+account the aged king, Zeilam, is said to have ordered the pans in which
+his victuals were cooked to be made of loadstone. The person (says he) to
+whom this order was given told me so himself. There are many varieties of
+loadstone produced by differences in the mingling of earths, metals, and
+juices; hence they are altogether unlike in their virtues and effects, due
+to propinquities of places and of agnate bodies, and arising from the pits
+themselves as it were from the matrices being soul. One loadstone is
+therefore able to purge the stomach, and another to check purging, to cause
+by its fumes a serious shock to the mind, to produce a gnawing at the
+vitals, or to bring on a grave relapse; in case of which ills they exhibit
+gold and emerald, using an abominable imposture for lucre. Pure loadstone
+may, indeed, be not only harmless, but even able to correct an over-fluid
+and putrescent state of the bowels and bring them back to a better
+temperament; of this sort usually are the oriental magnets from China, and
+the denser ones from Bengal, which are neither misliking nor unpleasant to
+the actual senses. Plutarch and Claudius Ptolemy[88], and all the copyists
+since their time, think that a loadstone smeared with garlick does not
+allure iron. Hence some suspect that garlick is of avail against any
+deleterious power of the magnet: thus in philosophy many false and idle
+conjectures arise from fables and falsehoods. Some physicians[89] have that
+a loadstone has power to extract the iron of an arrow from the human body.
+But it is when whole that the loadstone draws, not when pulverized and
+formless, buried in plasters; for it does not attract by reason of its
+material, but is rather adapted for the healing of open wounds, by reason
+of exsiccation, closing up and drying the sore, an effect by which the
+arrow-heads would rather be retained in the wounds. Thus vainly and
+preposterously do the sciolists {33} look for remedies while ignorant of
+the true causes of things. The application of a loadstone for all sorts of
+headaches no more cures them (as some make out) than would an iron helmet
+or a steel cap. To give it in a draught to dropsical persons is an error of
+the ancients, or an impudent tale of the copyists, though one kind of ore
+may be found which, like many more minerals, purges the stomach; but this
+is due to some defect of that ore and not to any magnetick property.
+Nicolaus puts a large quantity of loadstone into his divine plaster[90],
+just as the Augsburgers do into a black plaster[91] for fresh wounds and
+stabs; the virtue of which dries them up without smart, so that it proves
+an efficacious medicament. In like manner also Paracelsus to the same end
+mingles it in his plaster for stab wounds[92].
+
+       *       *       *       *       *
+
+
+CHAP. XV.
+
+The Medicinal Virtue of Iron.[93]
+
+Not foreign to our present purpose will it be to treat briefly also of the
+medicinal virtue of iron: for it is a prime remedial for some diseases of
+the human body, and by its virtues, both those that are natural and those
+acquired by suitable preparation, it works marvellous changes in the human
+body, so that we may the more surely recognize its nature through its
+medicinal virtue and through certain manifest experiments. So that even
+those tyros in medicine who abuse this most famous medicament may learn to
+prescribe it with better judgment for the healing of the sick, and not, as
+too often they use it, to their harm. The best iron, Stomoma, or Chalybs,
+Acies, or Aciarium, is reduced to a fine powder by a file; the powder is
+steeped in the sharpest vinegar, and dried in the sun, and again soused in
+vinegar, and dried; afterwards it is washed in spring water or other
+suitable water, and dried; then for the second time it is pulverized and
+reduced on porphyry, passed through a very fine sieve, and put back for
+use. It is given chiefly in cases of laxity and over-humidity of the liver,
+in enlargement of the spleen, after due evacuations; for which reason it
+restores young girls when pallid, sickly, and lacking colour, to health and
+beauty; since it is very siccative, and is astringent without harm. But
+some who in every internal malady always talk of obstruction {34} of the
+liver and spleen, think it beneficial in those cases because it removes
+obstructions, mainly trusting to the opinions of certain Arabians[94]:
+wherefore they administer it to the dropsical and to those suffering from
+tumour of the liver or from chronic jaundice, and to persons troubled with
+hypochondrical melancholia or any stomachic disorder, or add it to
+electuaries, without doubt to the grievous injury of many of their
+patients. Fallopius commends it prepared in his own way for tumours of the
+spleen, but is much mistaken; for loadstone is pre-eminently good for
+spleens relaxed with humour, and swollen; but it is so far from curing
+spleens thickened into a tumour that it mightily confirms the malady. For
+those drugs which are strong siccatives and absorb humour force the viscera
+when hardened into a tumour more completely into a quasi-stony body. There
+are some who roast iron in a closed oven with fierce firing, and burn it
+strongly, until it turns red, and they call this Saffron of Mars; which is
+a powerful siccative, and more quickly penetrates the intestines. Moreover
+they order violent exercise, that the drug may enter the viscera while
+heated and so reach the place affected; wherefore also it is reduced to a
+very fine flour; otherwise it only sticks in the stomach and in the chyle
+and does not penetrate to the intestines. As a dry and earthy medicament,
+then, it is shown by the most certain experiments to be, after proper
+evacuations, a remedy for diseases arising from humour (when the viscera
+are charged and overflowing with watery rheum). Prepared steel is a
+medicament proper for enlarged spleen. Iron waters too are effectual in
+reducing the spleen, although as a rule iron is of a frigid and astringent
+efficiency, not a laxative; but it effects this neither by heat nor by
+cold, but from its own dryness when mixed with a penetrative fluid: it thus
+disperses the humour, thickens the villi, hardens the tissues, and
+contracts them when lax; while the inherent heat in the member thus
+strengthened, being increased in power, dissipates what is left. Whereas if
+the liver be hardened and weakened by old age or a chronic obstruction, or
+the spleen be shrivelled and contracted to a schirrus, by which troubles
+the fleshy parts of the limbs grow flaccid, and water under the skin
+invades the body, in the case of these conditions the introduction of iron
+accelerates the fatal end, and considerably increases the malady. Amongst
+recent writers there are some who in cases of drought of the liver
+prescribe, as a much lauded and famous remedy, the electuary of iron slag,
+described by Rhazes[95] in his ninth book _ad Almansorem_, Chap. 63, or
+prepared filings of steel; an evil and deadly advice: which if they do not
+some time understand from our philosophy, at least everyday experience, and
+the decline and death of their patients, will convince them, even the
+sluggish and lazy. Whether iron be warm or cold is variously contended by
+{35} many. By Manardus, Curtius, Fallopius and others, many reasons are
+adduced on both sides; each settles it according to his own sentiment. Some
+make it to be cold, saying that iron has the property of refrigerating,
+because Aristotle in his _Meteorologica_ would put iron in the class of
+things which grow concreted in cold by emission of the whole of their Heat:
+Galen, too, says that iron has its consistency from cold; also that it is
+an earthy and dense body. Further that iron is astringent, also that
+Chalybeate water quenches thirst: and they adduce the cooling effect of
+thermal iron waters. Others, however, maintain that it is Warm, because of
+Hippocrates making out that waters are warm which burst forth from places
+where iron exists. Galen says that in all metals there is considerable
+substance, or essence, of fire. Paolo[96] affirms that iron waters are
+warm. Rhazes will have it that iron is warm and dry in the third degree.
+The Arabians think that it opens the spleen and liver; wherefore also that
+iron is warm. Montagnana recommends it in cold affections of the uterus and
+stomach. Thus do the smatterers cross swords together, and puzzle inquiring
+minds by their vague conjectures, and wrangle for trifles as for goats'
+wool, when they philosophize, wrongly allowing and accepting properties:
+but these matters will appear more plainly by and by when we begin to
+discuss the causes of things; the clouds being dispersed that have so
+darkened all Philosophy. Filings, scales, and slag of iron are, as Avicenna
+makes out, not wanting in deleterious power (haply when they are not well
+prepared or are taken in larger quantity than is fit), hence they cause
+violent pain in the bowels, roughness of the mouth and tongue, marasmus,
+and shrivelling of the limbs. But Avicenna wrongly[97] and old-womanishly
+makes out that the proper antidote to this iron poison is loadstone to the
+weight of a drachm taken as a draught in the juice of mercurialis or of
+Beet; for loadstone is of a twofold nature, usually malefiant and
+pernicious, nor does it resist iron, since it attracts it; nor when drunk
+in a draught in the form of powder does it avail to attract or repel, but
+rather inflicts the same evils.
+
+       *       *       *       *       * {36}
+
+
+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._
+
+Hitherto we have declared the nature & powers of the loadstone, & also the
+properties & essence of iron; it now remains to show their mutual
+affinities, & kinship, so to speak, & how very closely conjoined these
+substances are. At the highest part of the terrestrial globe, or at its
+perishable surface & rind, as it were, these two bodies usually originate &
+are produced in one and the same matrix, as twins in one mine. Strong
+loadstones are dug up by themselves, weaker ones too have their own proper
+vein. Both are found in iron mines. Iron ore most often occurs alone,
+without strong loadstone (for the more perfect are rarely met with). Strong
+loadstone is a stone resembling iron; out of it is usually smelted the
+finest iron, which the Greeks call _stomoma_, the Latins _acies_, the
+Barbarians (not amiss) _aciare_, or _aciarium_. This same stone draws,
+repels, controls other loadstones, directs itself to the poles of the
+world, picks up smelted iron, and works many other wonders, some already
+set forth by us, but many more which we must demonstrate more fully. A
+weaker loadstone, however, will exhibit all these powers, but in a lesser
+degree; while iron ore, & also wrought iron (if they have been prepared)
+show their strength in all magnetick experiments not less than do feeble
+and weak * loadstones; & an inert piece of ore, & one possessed of no
+magnetick properties, & just thrown out[98] of the pit, when roasted in the
+fire & prepared with due art (by the elimination of humours & foreign
+excretions) awakes, and becomes in power & potency a magnet, * occasionally
+a stone or iron ore is mined, which attracts forthwith without being
+prepared: for native iron of the right colour attracts and governs iron
+magnetically. One form then belongs to the one mineral, one species, one
+self-same essence. For to me there seems to be a greater difference, &
+unlikeness, between the strongest {37} loadstone, & a weak one which scarce
+can attract a single chip of iron; between one that is stout, strong,
+metallick, & one that is soft, friable, clayey; amidst such variety of
+colour, substance, quality, & weight; than there is on the one hand between
+the best ore, rich in iron, or iron that is metallick from the beginning,
+and on the other the most excellent loadstone. Usually, too, there are no
+marks to distinguish them, and even metallurgists cannot decide between
+them, because they agree together in all respects. Moreover we see that the
+best loadstone and the ore of iron are both as it were distressed by the
+same maladies & diseases, both run to old age in the same way & exhibit the
+same marks of it, are preserved & keep their properties by the same
+remedies & safeguards; & yet again the one increases the potency of the
+other, & by artfully devised adjuncts marvellously intensifies, & exalts
+it. For both are impaired by the more acrid juices as by poisons, & the
+aqua fortis of the Chemists inflicts on both the same wounds, and when
+exposed too long to harm from the atmosphere, they both alike pine away, so
+to speak, & grow old; each is preserved by being kept in the dust &
+scrapings of the other; & when a fit piece of steel or iron is adjoined
+above its pole, the loadstone's vigour is augmented through the firm union.
+The loadstone is laid up in iron filings, not that iron is its food; as
+though loadstone were alive and needed feeding, as Cardan
+philosophizes[99]; nor yet that so it is delivered from the inclemency of
+the weather (for which cause it as well as iron is laid up in bran by
+Scaliger; mistakenly, however, for they are not preserved well in this way,
+and keep for years their own fixed forms): nor yet, since they remain
+perfect by the mutual action of their powders, do their extremities waste
+away, but are cherished & preserved, like by like. For just as in their own
+places, in the mines, bodies like to each other endure for many ages entire
+and uncorrupt, when surrounded by bodies of the same stuff, as the lesser
+interior parts in a great mass: so loadstone and ore of iron, when inclosed
+in a mound of the same material, do not exhale their native humour, do not
+waste away, but retain their soundness. A loadstone lasts longer in filings
+of smelted iron, & a piece of iron ore excellently also in dust of
+loadstone; as also smelted iron in filings of loadstone & even in those of
+iron. Then both these allied bodies have a true & just form of one & the
+same species; a form which until this day was considered by all, owing to
+their outward unlikeness & the inequality of the potency that is the same
+innate in both, to be different & unlike in kind; the smatterers not
+understanding that the same powers, though differing in strength, exist in
+both alike. And in fact they both are true & intimate parts of the earth, &
+as such retain the prime natural properties of mutually attracting, of
+moving, & of disposing themselves toward the position of the world, {38}
+and of the terrestrial globe; which properties they also impart to each
+other, and increase, confirm, receive, and retain each other's forces. The
+stronger fortifies the weaker, not as though aught were taken away from its
+own substance, or its proper vigour, nor because any corporeal substance is
+imparted, but the dormant virtue of the one is aroused by the other,
+without loss. For if with a single small stone you touch a thousand bits of
+iron for the use of mariners[100], that loadstone attracts iron no less
+strongly than before; with the same stone weighing one pound, any one will
+be able to suspend in the air a thousand pounds of iron. For if any one
+were to fix high up on the walls so many iron nails of so great a weight, &
+were to apply to them the same number of nails touched, according to the
+art, by a loadstone, they would all be seen to hang in the air through the
+force of one small stone. So this is not solely the action, labour, or
+outlay of the loadstone; but the iron, which is in a sense an extract from
+loadstone, and a fusion of loadstone into metal, & conceives vigour from
+it, & by proximity strengthens the magnetick faculties, doth itself, from
+whatever lode it may have come, raise its own inborn forces through the
+presence & contact of the stone, even when solid bodies intervene. Iron
+that has been touched, acts anew on another piece of iron by contact, &
+adapts it for magnetick movements, & this again a third. But if you rub
+with a loadstone any other metal, or wood, or bones, or glass, as they will
+not be moved toward any particular and determinate quarter of heaven, nor
+be attracted by any magnetick body, so they are able not to impart any
+magnetick property to other bodies or to iron itself by attrition, & by
+infection. Loadstone differs from iron ore, as also from some weaker
+magnets, in that when molten in the furnace into a ferric & metallick fused
+mass, it does not so readily flow & dissolve into metal; but is sometimes
+burnt to ashes in large furnaces; a result which it is reasonable to
+suppose arises from its having some kind of sulphureous matter mixed with
+it, or from its own excellence & simpler nature, or from the likeness &
+common form which it has with the common mother, the Great Magnet. For
+earths, and iron stones, magnets abounding in metal, are the more imbued &
+marred with excrementitious metallick humours, and earthy corruptions of
+substance, as numbers of loadstones are weaker from the mine; hence they
+are a little further remote from the common mother, & are degenerate, &
+when smelted in the furnace undergo fusion more easily, & give out a more
+certain metallick product, & a metal that is softer, not a tough steel. The
+majority of loadstones (if not unfairly burnt[101]) yield in the furnace a
+very excellent iron. But iron ore also agrees in all those primary
+qualities with loadstone; for both, being nearer and more closely akin to
+the earth above all bodies known to us, have in themselves {39} a magnetick
+substance, & one that is more homogenic, true & cognate with the globe of
+the earth; less infested & spoiled by foreign blemish; less confused with
+the outgrowths of earth's surface, & less debased by corrupt products. And
+for this reason Aristotle in the fourth book of his _Meteora_ seems not
+unfairly to separate iron from all the rest of the metals. Gold, he says,
+silver, copper, tin, lead, belong to water; but iron is of the earth.
+Galen, in the fourth chapter of _De Facultatibus Simplicium
+Medicamentorum_, says that iron is an earthy & dense body. Accordingly a
+strong loadstone is on our showing especially of the earth: the next place
+is occupied by iron ore or weaker loadstone; so the loadstone is by nature
+and origin[102]** of iron, and it and magnetick iron are both one in kind.
+Iron ore yields iron in furnaces; loadstone also pours forth iron in the
+furnaces, but of a much more excellent sort, that which is called steel or
+blade-edge; and the better sort of iron ore is a weak loadstone, the best
+loadstone being a most excellent ore of iron, in which, as is to be shown
+by us, the primary properties are grand and conspicuous. Weaker loadstone
+or iron ore is that in which these properties are more obscure, feeble, and
+are scarce perceptible to the senses.
+
+       *       *       *       *       *
+
+
+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._
+
+Prior to bringing forward the causes of magnetical motions, & laying open
+the proofs of things hidden for so many ages, & our experiments (the true
+foundations of terrestrial philosophy), we have to establish & present to
+the view of the learned our New & unheard of doctrine about the earth; and
+this, when argued by us on the grounds of its probability, with subsequent
+{40} experiments & proofs, will be as certainly assured as anything in
+philosophy ever has been considered & confirmed by clever arguments or
+mathematical proofs. The terrene mass, which together with the vasty ocean
+produces the sphaerick figure & constitutes our globe, being of a firm &
+constant substance, is not easily changed, does not wander about, &
+fluctuate with uncertain motions, like the seas, & flowing waves: but holds
+all its volume of moisture in certain beds & bounds, & as it were in
+oft-met veins, that it may be the less diffused & dissipated at random. Yet
+the solid magnitude of the earth prevails & reigns supreme in the nature of
+our globe. Water, however, is attached to it, & as an appendage only, & a
+flux emanating from it; whose force from the beginning is conjoined with
+the earth through its smallest parts, and is innate in its substance. This
+moisture the earth as it grows hot throws off freely when it is of the
+greatest possible service in the generation of things. But the thews and
+dominant stuff of the globe is that terrene body which far exceeds in
+quantity all the volume of flowing streams and open waters (whatever vulgar
+philosophers may dream of the magnitudes and proportions of their
+elements), and which takes up most of the whole globe and almost fills it
+internally, and by itself almost suffices to endow it with sphaerick shape.
+For the seas only fill certain not very deep or profound hollows, since
+they rarely go down to a depth of a mile and generally do not exceed a
+hundred or 50 fathoms. For so it is ascertained by the observations of
+seamen when by the plumb-line and sinker its abysms are explored with the
+nautical sounder; which depths relatively to the dimensions of the globe,
+do not much deform its globular shape. Small then appears to be that
+portion of the real earth that ever emerges to be seen by man, or is turned
+up; since we cannot penetrate deeper into its bowels, further than the
+wreckage of its outer efflorescence, either by reason of the waters which
+gush up in deep workings, as through veins, or for want of a wholesome air
+to support life in the miners, or on account of the vast cost that would be
+incurred in pumping out such huge workings[103], and many other
+difficulties; so that to have gone down to a depth of four hundred, or
+(which is of rarest occurrence) of five hundred fathoms[104] as in a few
+mines, appears to all a stupendous undertaking. But it is easy to
+understand how minute, how almost negligibly small a portion that 500
+fathoms is of the earth's diameter, which is 6,872 miles. It is then parts
+only of the earth's circumference and of its prominences that are perceived
+by us with our senses; and these in all regions appear to us to be either
+loamy, or clayey, or sandy, or full of various soils, or marls: or lots of
+stones or gravel meet us, or beds of salt, or a metallick lode, and metals
+in abundance. In the sea and in deep waters, however, either reefs, and
+huge boulders, or smaller stones, or sands, or mud {41} are found by
+mariners as they sound the depths. Nowhere does the Aristotelian element of
+_earth_ come to light; and the Peripateticks are the sport of their own
+vain dreams about elements. Yet the lower bulk of the earth and the inward
+parts of the globe consist of such bodies; for they could not have existed,
+unless they had been related to and exposed to the air and water, and to
+the light and influences of the heavenly bodies, in like manner as they are
+generated, and pass into many dissimilar forms of things, and are changed
+by a perpetual law of succession. Yet the interior parts imitate them, and
+betake themselves to their own source, on the principle of terrene matter,
+albeit they have lost the first qualities and the natural terrene form, and
+are borne towards the earth's centre, and cohaere with the globe of the
+earth, from which they cannot be wrenched asunder except by force. But the
+loadstone and all magneticks, not the stone only, but every magnetick
+homogenic substance, would seem to contain the virtue of the earth's core
+and of its inmost bowels, and to hold within itself and to have conceived
+that which is the secret and inward principle of its substance; and it
+possesses the actions peculiar to the globe of attracting, directing,
+disposing, rotating, stationing itself in the universe, according to the
+rule of the whole, and it contains and regulates the dominant powers of the
+globe; which are the chief tokens and proofs of a certain distinguishing
+combination, and of a nature most thoroughly conjoint. For if among actual
+bodies one sees something move and breathe, and experience sensations, and
+be inclined and impelled by reason, will one not, knowing and seeing this,
+conclude that it is a man or something rather like a man, than that it is a
+stone or a stick? The loadstone far excels all other bodies known to us in
+virtues and properties pertaining to the common mother: but those
+properties have been far too little understood or realized by philosophers:
+for to its body bodies magnetical rush in from all sides and cleave to it,
+as we see them do in the case of the earth. It has poles, not mathematical
+points, but natural termini of force excelling in primary efficiency by the
+co-operation of the whole: and there are poles in like manner in the earth
+which our forefathers sought ever in the sky: it has an aequator, a natural
+dividing line between the two poles, just as the earth has: for of all
+lines drawn by the mathematicians on the terrestrial globe, the aequator is
+the natural boundary, and is not, as will hereafter appear, merely a
+mathematical circle. It, like the earth, acquires Direction and stability
+toward North and South, as the earth does; also it has a circular motion
+toward the position of the earth, wherein it adjusts itself to its rule: it
+follows the ascensions and declinations of the earth's poles, and conforms
+exactly to the same, and by itself raises its own poles above the {42}
+horizon naturally according to the law of the particular country and
+region, or sinks below it. The loadstone derives temporary properties, and
+acquires its verticity from the earth, and iron is affected by the
+verticity of the globe even as iron is by a loadstone: Magneticks are
+conformable to and are regulated by the earth, and are subject to the earth
+in all their motions. All its movements harmonize with, and strictly wait
+upon, the geometry and form of the earth, as we shall afterwards prove by
+most conclusive experiments and diagrams; and the chief part of the visible
+earth is also magnetical, and has magnetick motions, although it be
+disfigured by corruptions and mutations without end. Why then do we not
+recognize this the chief homogenic substance of the earth, likest of
+substances to its inner nature and closest allied to its very marrow? For
+none of the other mixed earths suitable for agriculture, no other
+metalliferous veins, nor stones, nor sand, nor other fragments of the earth
+which have come to our view possess such constant and peculiar powers. And
+yet we do not assume that the whole interior of this globe of ours is
+composed of stones or iron (although Franciscus Maurolycus, that learned
+man, deems the whole of the earth's interior to consist of solid stone).
+For not every loadstone that we have is a stone, it being sometimes like a
+clod, or like clay and iron either firmly compacted together out of various
+materials, or of a softer composition, or by heat reduced to the metallick
+state; and the magnetick substance by reason of its location and of its
+surroundings, and of the metallick matrix itself, is distinguished, at the
+surface of the terrene mass, by many qualities and adventitious natures,
+just as in clay it is marked by certain stones and iron lodes. But we
+maintain that the true earth is a solid substance, homogeneous with the
+globe, closely coherent, endowed with a primordial and (as in the other
+globes of the universe) with a prepotent form; in which position it
+persists with a fixed verticity, and revolves with a necessary motion and
+an inherent tendency to turn, and it is this constitution, when true and
+native, and not injured or disfigured by outward defects, that the
+loadstone possesses above all bodies apparent to us, as if it were a more
+truly homogenic part taken from the earth. Accordingly native iron which
+_sui generis_ (as metallurgists term it), is formed when homogenic parts of
+the earth grow together into a metallick lode; Loadstone being formed when
+they are changed into metallick stone, or a lode of the finest iron, or
+steel: so in other iron lodes the homogenic matter that goes together is
+somewhat more imperfect; just as many parts of the earth, even the high
+ground, is homogenic but so much more deformate. Smelted iron is fused and
+smelted out of homogenic stuffs, and cleaves to the earth more tenaciously
+than the ores themselves. Such then is our earth in its {43} inward parts,
+possessed of a magnetick homogeneal nature, and upon such more perfect
+foundations as these rests the whole nature of things terrestrial,
+manifesting itself to us, in our more diligent scrutiny, everywhere in all
+magnetick minerals, and iron ores, in all clay, and in numerous earths and
+stones; while Aristotle's simple element, that most empty terrestrial
+phantom of the Peripateticks, a rude, inert, cold, dry, simple matter, the
+universal substratum, is dead, devoid of vigour, and has never presented
+itself to any one, not even in sleep, and would be of no potency in nature.
+Our philosophers were only dreaming when they spoke of a kind of simple and
+inert matter. Cardan does not consider the loadstone to be any kind of
+stone, "but a sort of perfected portion of some kind of earth that is
+absolute; a token of which is its abundance, there being no place where it
+is not found. And there is" (he says) "a power of iron in the wedded Earth
+which is perfect in its own kind when it has received fertilizing force
+from the male, that is to say, the stone of Hercules" (in his book _De
+Proportionibus_). And later: "Because" (he says) "in the previous
+proposition I have taught that iron is true earth." A strong loadstone
+shows itself to be of the inward earth, and upon innumerable tests claims
+to rank with the earth in the possession of a primary form, that by which
+Earth herself abides in her own station and is directed in her courses.
+Thus a weaker loadstone and every ore of iron, and nearly all clay, or
+clayey earth, and numerous other sorts (yet more, or less, owing to the
+different labefaction of fluids and slimes), keep their magnetick and
+genuine earth-properties open to view, falling short of the characteristic
+form, and deformate. For it is not iron alone (the smelted metal) that
+points to the poles, nor is it the loadstone alone that is attracted by
+another and made to revolve magnetically; but all iron ores, and other
+stones, as Rhenish slates and the black ones from Avignon (the French call
+them _Ardoises_) which they use for tiles, and many more of other colours
+and substances, provided they have been prepared; as well as all clay,
+grit[105], and some sorts of rocks, and, to speak more clearly, all the
+more solid earth that is everywhere apparent; given that that earth be not
+fouled with fatty and fluid corruptions; as mud, as mire, as accumulations
+of putrid matter; nor deformate by the imperfections of sundry admixtures;
+nor dripping with ooze, as marls; all are attracted by the loadstone, when
+simply prepared by fire, and freed from their refuse humour; and as by the
+loadstone so also by the earth herself they are drawn and controlled
+magnetically, in a way different from all other bodies; and by that
+inherent force settle themselves according to the orderly arrangement and
+fabric of the universe and of the Earth, as will appear {44} later. Thus
+every part of the earth which is removed from it exhibits by sure
+experiments every impulse of the magnetick nature; by its various motions
+it observes the globe of the earth and the principle common to both.
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+{45} [Illustration]
+
+BOOK SECOND.
+
+_CHAP. I._
+
+ON MAGNETICK
+Motions.
+
+Divers things concerning opinions about the magnet-stone, and its variety,
+concerning its poles and its known faculties, concerning iron, concerning
+the properties of iron, concerning a magnetick substance common to both of
+these and to the earth itself, have been spoken briefly by us in the former
+book. There remain the magnetical motions, and their fuller philosophy,
+shown and demonstrated. These motions are incitements of homogeneal parts
+either among themselves or toward the primary conformation of the whole
+earth. Aristotle admits only two simple motions of his elements, from the
+centre and toward the centre; of light ones upward, heavy ones downward; so
+that in the earth there exists one motion only of all its parts towards the
+centre of the world,--a rude and inert precipitation. But what of it is
+light, and how wrongly it is inferred by the Peripateticks from the simple
+motion of the elements, and also what is its heavy part, we will discuss
+elsewhere. But now our inquiry must be into the causes of other motions,
+depending on its true form, which we have plainly seen in our magnetick
+bodies; and these we have seen to be present in the earth and in all its
+homogenic parts also. We have noticed that they harmonize with the earth,
+and are bound up with its forces. Five movements[106] or differences of
+motions are then observed by us: Coition (commonly called attraction), the
+{46} incitement to magnetick union; Direction towards the poles of the
+earth, and the verticity and continuance of the earth towards the
+determinate poles of the world; Variation, a deflexion from the meridian,
+which we call a perverted movement; Declination, a descent of the magnetick
+pole below the horizon; and circular motion, or Revolution. Concerning all
+these we shall discuss separately, and how they all proceed from a nature
+tending to aggregation, either by verticity or by volubility. Jofrancus
+Offusius[107] makes out different magnetick motions; a first toward a
+centre; a second toward a pole at seventy-seven degrees; a third toward
+iron; a fourth toward loadstone. The first is not always to a centre, but
+exists only at the poles in a straight course toward the centre, if the
+motion is magnetick; otherwise it is only motion of matter toward its own
+mass and toward the globe. The second toward a pole at seventy-seven
+degrees is no motion, but is direction with respect to the pole of the
+earth, or variation. The third and fourth are magnetick and are the same.
+So he truly recognizes no magnetick motion except the Coition toward iron
+or loadstone, commonly called attraction. There is another motion in the
+whole earth, which does not exist towards the terrella or towards its
+parts; videlicet, a motion of aggregation, and that movement of matter,
+which is called by philosophers a right motion, of which elsewhere.
+
+       *       *       *       *       *
+
+
+CHAP. II.
+
+On the Magnetick Coition, and first on the
+Attraction of Amber, or more truly, on the
+_Attaching of Bodies to Amber_.
+
+Celebrated has the fame of the loadstone and of amber ever been in the
+memoirs of the learned. Loadstone and also amber do some philosophers
+invoke when in explaining many secrets their senses become dim and
+reasoning cannot go further. Inquisitive theologians also would throw light
+on the divine mysteries set beyond the range of human sense, by means of
+loadstone and amber; just as idle Metaphysicians, when they are setting up
+and teaching useless phantasms, have recourse to the loadstone as if it
+were a Delphick sword, an illustration always applicable to everything. But
+physicians even (with the authority of {47} Galen), desiring to confirm the
+belief in the attraction of purgative medicines by means of the likeness of
+substance and the familiarities of the juices--truly a vain and useless
+error--bring in the loadstone as witness as being a nature of great
+authority and of conspicuous efficacy and a remarkable body. So in very
+many cases there are some who, when they are pleading a cause and cannot
+give a reason for it, bring in loadstone and amber as though they were
+personified witnesses. But these men (apart from that common error) being
+ignorant that the causes of magnetical motions are widely different from
+the forces of amber, easily fall into error, and are themselves the more
+deceived by their own cogitations. For in other bodies a conspicuous force
+of attraction manifests itself otherwise than in loadstone; like as in
+amber, concerning which some things must first be said, that it may appear
+what is that attaching of bodies, and how it is different from and foreign
+to the magnetical actions; those mortals being still ignorant, who think
+that inclination to be an attraction, and compare it with the magnetick
+coitions. The Greeks call it [Greek: elektron][108] because it attracts
+straws to itself, when it is warmed by rubbing; then it is called [Greek:
+harpax][109]; and [Greek: chrusophoron] from its golden colour. But the
+Moors call it Carabe[110], because they are accustomed to offer the same in
+sacrifices and in the worship of the Gods. For Carab signifies to offer in
+Arabic; so Carabe, an offering: or seizing chaff, as Scaliger quotes from
+Abohalis, out of the Arabic or Persian language. Some also call it Amber,
+especially the Indian and Ethiopian amber, called in Latin _Succinum_, as
+if it were a juice[111]. The Sudavienses or Sudini[112] call it _geniter_,
+as though it were generated terrestrially. The errors of the ancients
+concerning its nature and origin having been exploded, it is certain that
+amber comes for the most part from the sea, and the rustics collect it on
+the coast after the more violent storms, with nets and other tackle; as
+among the Sudini of Prussia; and it is also found sometimes on the coast of
+our own Britain. It seems, however, to be produced also in the soil and at
+spots of some depth, like other bitumens; to be washed out by the waves of
+the sea; and to become concreted more firmly from the nature and saltness
+of the sea-water. For it was at first a soft and viscous material;
+wherefore also it contains enclosed and entombed in pieces of it, shining
+in eternal sepulchres, flies, grubs, gnats, ants; which have all flown or
+crept or fallen into it when it first flowed forth in a liquid state[113].
+The ancients and also more recent writers recall (experience proving the
+same thing), that amber attracts straws and chaff[114]. The same is also
+done by jet[115], which is dug out of the earth in Britain, in Germany, and
+in very many lands, and is a rather hard concretion from black bitumen, and
+as it were a transformation into stone. There are many modern authors[116]
+who have written and copied from others about amber and jet[117] attracting
+chaff, and about other {48} substances generally unknown; with whose
+labours the shops of booksellers are crammed. Our own age has produced many
+books about hidden, abstruse, and occult causes and wonders, in all of
+which amber and jet are set forth as enticing chaff; but they treat the
+subject in words alone, without finding any reasons or proofs from
+experiments, their very statements obscuring the thing in a greater fog,
+forsooth in a cryptic, marvellous, abstruse, secret, occult, way. Wherefore
+also such philosophy produces no fruit, because very many philosophers,
+making no investigation themselves, unsupported by any practical
+experience, idle and inert, make no progress by their records, and do not
+see what light they can bring to their theories; but their philosophy rests
+simply on the use of certain Greek words, or uncommon ones; after the
+manner of our gossips and barbers nowadays, who make show of certain Latin
+words to an ignorant populace as the insignia of their craft, and snatch at
+the popular favour. For it is not only amber and * jet (as they suppose)
+which entice small bodies[118]; but Diamond, Sapphire, Carbuncle, Iris
+gem[119], Opal, Amethyst, Vincentina, and Bristolla (an English gem or
+spar)[120], Beryl, and Crystal[121] do the same. Similar powers of
+attraction are seen also to be possessed by glass (especially when clear
+and lucid), as also by false gems made of glass or Crystal, by glass of
+antimony, and by many kinds of spars from the mines, and by Belemnites.
+Sulphur also attracts, and mastick, and hard sealing-wax[122] compounded of
+lac tinctured of various colours. Rather hard resin entices, as does
+orpiment[123], but less strongly; with difficulty also and indistinctly
+under a suitable dry sky[124], Rock salt, muscovy stone, and rock alum.
+This one may see when the air is sharp and clear and rare in mid-winter,
+when the emanations from the earth hinder electricks less, and the
+electrick bodies become * more firmly indurated; about which hereafter.
+These substances draw everything, not straws and chaff only[125], but all
+metals, woods, leaves, stones, earths, even water and oil, and everything
+which is subject to our senses, or is solid; although some write that amber
+does not attract anything but chaff and certain twigs; (wherefore Alexander
+Aphrodiseus falsely declares the question of amber to be inexplicable,
+because it attracts dry chaff only, and not basil leaves[126]), but these
+are the utterly false and disgraceful tales of the writers. But in order
+that you may be able clearly to test how such attraction occurs[127], and
+what those materials[128] are which thus entice other bodies (for even if
+bodies incline towards some of these, yet on account of weakness they seem
+not to be raised by them, but are more easily turned), make yourself a
+versorium of any metal you like, three or four digits in length, resting
+rather lightly on its point of support after the manner of a magnetick
+needle, to one end of which bring up a piece of amber or a smooth {49}
+[Illustration] and polished gem which has been gently rubbed; for the
+versorium turns forthwith. Many things are thereby seen to attract, both
+those which are formed by nature alone, and those which are by art
+prepared, fused, and mixed; nor is this so much a singular property of one
+or two things (as is commonly supposed), but the manifest nature of very
+many, both of simple substances, remaining merely in their own form, and of
+compositions, as of hard sealing-wax, & of certain other mixtures besides,
+made of unctuous stuffs. We must, however, investigate more fully whence
+that tendency arises, and what those forces be, concerning which a few men
+have brought forward very little, the crowd of philosophizers nothing at
+all. By Galen three kinds of attractives in general were recognized in
+nature: a First class of those substances which attract by their elemental
+quality, namely, heat; the Second is the class of those which attract by
+the succession of a vacuum; the Third is the class of those which attract
+by a property of their whole substance, which are also quoted by Avicenna
+and others. These classes, however, cannot in any way satisfy us; they
+neither embrace the causes of amber, jet, and diamond, and of other similar
+substances (which derive their forces on account of the same virtue); nor
+of the loadstone, and of all magnetick substances, which obtain their
+virtue by a very dissimilar and alien influence from them, derived from
+other sources. Wherefore also it is fitting that we find other causes of
+the motions, or else we must wander (as in darkness), with these men, and
+in no way reach the goal. Amber truly does* not allure by heat, since if
+warmed by fire and brought near straws, it does not attract them, whether
+it be tepid, or hot, or glowing, or even when forced into the flame. Cardan
+(as also Pictorio) reckons that this happens in no different way[129] than
+with the cupping-glass, by the force of fire. Yet the attracting force of
+the cupping-glass does not really come from the force of fire. But he had
+previously said that the dry substance wished to imbibe fatty humour, and
+therefore it was borne towards it. But these statements are at variance
+with one another, and also foreign to reason. For if amber had moved
+towards its food, or if other bodies had inclined towards amber as towards
+provender, there would have been a diminution of the one which was
+devoured, just as there would have been a growth of the other which was
+sated. Then why should an attractive force of fire be looked for in amber?
+If the attraction existed from heat, why should not very many other bodies
+also attract, if warmed by fire, by the sun, or by friction? Neither can
+the attraction be on account of the dissipating of the air, when it takes
+place in open air (yet Lucretius the poet adduces this as the reason for
+magnetical motions). Nor in the cupping-glass can heat or fire attract by
+feeding on air: in the cupping-glass air, having been exhausted into flame,
+{50} when it condenses again and is forced into a narrow space, makes the
+skin and flesh rise in avoiding a vacuum. In the open air warm things
+cannot attract, not metals even or stones, if they should * be strongly
+incandescent by fire. For a rod of glowing iron, or a flame, or a candle,
+or a blazing torch, or a live coal, when they are brought near to straws,
+or to a versorium, do not attract; yet at the same time they manifestly
+call in the air in succession; because they consume it, as lamps do oil.
+But concerning heat, how it is reckoned by the crowd of philosophizers, in
+natural philosophy and in _materia medica_ to exert an attraction otherwise
+than nature allows, to which true attractions are falsely imputed, we will
+discuss more at length elsewhere, when we shall determine what are the
+properties of heat and cold. They are very general qualities or kinships of
+a substance, and yet are not to be assigned as true causes, and, if I may
+say so, those philosophizers utter some resounding words; but about the
+thing itself prove nothing in particular. Nor does this attraction
+accredited to amber arise from any singular quality of the substance or
+kinship, since by more thorough research we find the same effect in very
+many other bodies; and all bodies, moreover, of whatever quality, are
+allured by all those bodies. Similarity also is not the cause; because all
+things around us placed on this globe of the earth, similar and dissimilar,
+are allured by amber and bodies of this kind; and on that account no cogent
+analogy is to be drawn either from similarity or identity of substance. But
+neither do similars mutually attract one another, as stone stone, flesh
+flesh, nor aught else outside the class of magneticks and electricks.
+Fracastorio would have it that "things which mutually attract one another
+are similars, as being of the same species, either in action or in right
+subjection. Right subjection is that from which is emitted the emanation
+which attracts and which in mixtures often lies hidden on account of their
+lack of form, by reason of which they are often different in act from what
+they are in potency. Hence it may be that hairs and twigs move towards
+amber and towards diamond, not because they are hairs, but because either
+there is shut up in them air or some other principle, which is attracted in
+the first place, and which bears some relation and analogy to that which
+attracts of itself; in which diamond and amber agree through a principle
+common to each." Thus far Fracastorio. Who if he had observed by a large
+number of experiments that all bodies are drawn to electricks except those
+which are aglow and aflame, and highly rarefied, would never have given a
+thought to such things. It is easy for men of acute intellect, apart from
+experiments and practice, to slip and err. In greater error do they remain
+sunk who maintain these same substances to be not similar, but to be
+substances near akin; and hold that on that account a thing moves towards
+another, its like, by which it is brought to more perfection. But these are
+{51} ill-considered views; for towards all electricks all things move[130]
+except such as are aflame or are too highly rarefied, as air, which is the
+universal effluvium of this globe and of the world. Vegetable substances
+draw moisture by which their shoots are rejoiced and grow; from analogy
+with that, however, Hippocrates, in his _De Natura Hominis_, Book I.,
+wrongly concluded that the purging of morbid humour took place by the
+specifick force of the drug. Concerning the action and potency of
+purgatives we shall speak elsewhere. Wrongly also is attraction inferred in
+other effects; as in the case of a flagon full of water, when buried in a
+heap of wheat, although well stoppered, the moisture is drawn out; since
+this moisture is rather resolved into vapour by the emanation of the
+fermenting wheat, and the wheat imbibes the freed vapour. Nor do elephants'
+tusks attract moisture, but drive it into vapour or absorb it. Thus then
+very many things are said to attract, the reasons for whose energy must be
+sought from other causes. Amber in a fairly large mass allures, if* it is
+polished; in a smaller mass or less pure it seems not to attract without
+friction. But very many electricks (as precious stones and some other
+substances) do not attract at all unless rubbed. On the other hand many
+gems, as well as other bodies, are polished, yet do* not allure, and by no
+amount of friction are they aroused; thus the emerald, agate, carnelian,
+pearls, jasper, chalcedony, alabaster, porphyry, coral, the marbles,
+touchstone, flint, bloodstone, emery[131], do not acquire any power; nor do
+bones, or ivory, or the hardest woods, as ebony, nor do cedar, juniper, or
+cypress; nor do metals, silver, gold, brass, iron, nor any loadstone,
+though many of them are finely polished and shine. But on the other hand
+there are some other polished substances of which we have spoken before,
+toward which, when they have been rubbed, bodies incline. This we shall
+understand only when we have more closely looked into the prime origin of
+bodies. It is plain to all, and all admit, that the mass of the earth, or
+rather the structure and crust of the earth, consists of a twofold
+material, namely, of fluid and humid matter, and of material of more
+consistency and dry. From this twofold nature or the more simple compacting
+of one, various substances take their rise among us, which originate in
+greater proportion now from the earthy, now from the aqueous nature. Those
+substances which have received their chief growth from moisture, whether
+aqueous or fatty, or have taken on their form by a simpler compacting from
+them, or have been compacted from these same materials in long ages, if
+they have a sufficiently firm hardness, if rubbed after they have been
+polished and when they remain bright with the friction--towards those
+substances everything, if presented to them in the air, turns, if its too
+heavy weight does not prevent it. For amber has been compacted of moisture,
+and jet also. Lucid gems are made of water; just as Crystal[132], which has
+been concreted from clear water, not {52} always by a very great cold, as
+some used to judge, and by very hard frost, but sometimes by a less severe
+one, the nature of the soil fashioning it, the humour or juices being shut
+up in definite cavities, in the way in which spars are produced in mines.
+So clear glass is fused out of sand, and from other substances, which have
+their origin in humid juices. But the dross of metals, as also metals,
+stones, rocks, woods, contain earth rather, or are mixed with a good deal
+of earth; * and therefore they do not attract. Crystal, mica, glass, and
+all electricks do not attract if they are burnt or roasted; for their
+primordial supplies of moisture perish by heat, and are changed and
+exhaled. All things therefore which have sprung from a predominant moisture
+and are firmly concreted, and retain the appearance of spar and its
+resplendent nature in a firm and compact body, allure all bodies, whether
+humid or dry. Those, however, which partake of the true earth-substance or
+are very little different from it, are seen to attract also, but from a far
+different reason, and (so to say) magnetically; concerning these we intend
+to speak afterwards. But those substances which are more mixed of water and
+earth, and are produced by the equal degradation of each element (in which
+the magnetick force of the earth is deformed and remains buried; while the
+watery humour, being fouled by joining with a more plentiful supply of
+earth, has not concreted in itself but is mingled with earthy matter), can
+in no way of themselves attract or move from its place anything which they
+do not touch. On this account metals, marbles, flints, woods, herbs, flesh,
+and very many other things can neither allure nor solicit any body either
+magnetically or electrically. (For it pleases us to call that an electrick
+force, which hath * its origin from the humour.) But substances consisting
+mostly of humour, and which are not very firmly compacted by nature
+(whereby do they neither bear rubbing, but either melt down and become
+soft, or are not levigable, such as pitch, the softer kinds of resin,
+camphor, galbanum, ammoniack[133], storax, asafoetida, benzoin, asphaltum,
+especially in rather warm weather) towards them small bodies are not borne;
+for without rubbing most electricks do not * emit their peculiar and native
+exhalation and effluvium. The resin turpentine when liquid does not
+attract; for it cannot be rubbed; but if it has hardened into a mastick it
+does attract. But now at length we must understand why small bodies turn
+towards those substances which have drawn their origin from water; by what
+force and with what hands (so to speak) electricks seize upon kindred
+natures. In all bodies in the world two causes or principles have been laid
+down, from which the bodies themselves were produced, matter and form[134].
+Electrical motions become strong from matter, but magnetick from form
+chiefly; and they differ widely from one another and turn out unlike, since
+the one is ennobled by numerous virtues and is prepotent; the other is
+ignoble and of less potency, and {53} mostly restrained, as it were, within
+certain barriers; and therefore that force must at times be aroused by
+attrition or friction, until it is at a dull heat and gives off an
+effluvium and a polish is induced on the body. For spent air, either blown
+out of the mouth or given* off from moister air, chokes the virtue. If
+indeed either a sheet of paper or a piece of linen be interposed, there
+will be no movement. But a loadstone, without friction or heat, whether dry
+or suffused with moisture, as well in air as in water, invites magneticks,
+even with the most solid bodies interposed, even planks of wood or pretty
+thick slabs of stone or sheets of metal. A loadstone appeals to magneticks*
+only; towards electricks all things move. A loadstone[135] raises great
+weights; so that if there is a loadstone weighing two ounces and strong, it
+attracts half an ounce or a whole ounce. An electrical substance only
+attracts very small weights; as, for instance, a piece of amber of three
+ounces weight, when rubbed, scarce raises a fourth part of a grain of
+barley. But this attraction of amber and of electrical substances must be
+further investigated; and since there is this particular affection of
+matter, it may be asked why is amber rubbed, and what affection is produced
+by the rubbing, and what causes arise which make it lay hold on everything?
+As a result of friction it grows slightly warm and becomes smooth; two
+results which must often occur together. A large polished fragment of amber
+or jet attracts indeed, even without friction, but less strongly; but if it
+be brought gently near a flame or a live coal, so that it equally becomes
+warm, it does not attract small bodies because* it is enveloped in a cloud
+from the body of the flaming substance, which emits a hot breath, and then
+impinges upon it vapour from a foreign body which for the most part is at
+variance with the nature of amber. Moreover the spirit of the amber which
+is called forth is enfeebled by alien heat; wherefore it ought not to have
+heat excepting that produced by motion only and friction, and, as it were,
+its own, not sent into it by other bodies. For as the igneous heat emitted
+from any burning substance cannot be so used that electricks may acquire
+their force from it; so also heat from the solar rays does not fit an
+electrick by the loosening of its* right material, because it dissipates
+rather and consumes it (albeit a body which has been rubbed retains its
+virtue longer exposed to the rays of the sun than in the shade; because in
+the shade the effluvia are condensed to a greater degree and more quickly).
+Then again the fervour from the light of the Sun aroused by means of a*
+burning mirror confers no vigour on the heated amber[136]; indeed it
+dissipates and corrupts all the electrick effluvia. Again, burning* sulphur
+and hard wax, made from shell-lac, when aflame do not allure; for heat from
+friction resolves bodies into effluvia, which flame consumes away. For it
+is impossible for solid electricks to be resolved into their own true
+effluvia otherwise than by attrition, save {54} in the case of certain
+substances which by reason of innate vigour emit effluvia constantly. They
+are rubbed with bodies which do not befoul their surface, and which produce
+a polish, as pretty stiff silk or a rough wool rag which is as little
+soiled as possible, or the dry palm. Amber also is rubbed with amber, with
+diamond, and with glass, and numerous other substances. Thus are electricks
+manipulated. These things being so, what is it which moves? Is it the body
+itself, inclosed within its own circumference? Or is it something
+imperceptible to us, which flows out from the substance into the ambient
+air? Somewhat as Plutarch opines, saying in his _Quaestiones
+Platonicae_[137]: That there is in amber something flammable or something
+having the nature of breath, and this by the attrition of the surface being
+emitted from its relaxed pores attracts bodies. And if it be an effusion
+does it seize upon the air whose motion the bodies follow, or upon the
+bodies themselves? But if amber allured the body itself, then what need
+were there of friction, if it is bare and smooth? Nor does the force arise
+from the light which is reflected from a smooth and polished body; for a
+Gem of Vincent's rock[138], Diamond, and clear glass, attract when they are
+rough; but not so powerfully and quickly, because they are not so readily
+cleansed from extraneous moisture on the surface, and are not rubbed
+equally so as to be copiously resolved at that part. Nor does the sun by
+its own beams of light and its rays, which are of capital importance in
+nature, attract bodies in this way; and yet the herd of philosophizers
+considers that humours are attracted by the sun, when it is only denser
+humours that are being turned into thinner, into spirit and air; and so by
+the motion of effusion they ascend into the upper regions, or the
+attenuated exhalations are raised up from the denser air. Nor does it seem
+to take place from the effluvia attenuating the air, so that bodies
+impelled by the denser air penetrate towards the source of the rarefaction;
+in this case both hot and flaming bodies would also allure other bodies;
+but not even the lightest chaff, or any versorium moves towards a flame. If
+there is a flow and rush of air towards the body, how can a small diamond
+of the size of a pea[139] summon towards itself so much air, that it seizes
+hold of a biggish long body placed in equilibrio (the air about one or
+other very small part of an end being attracted)? It ought also to have
+slopped or moved more slowly, before it came into contact with the body,
+especially if the piece of amber was rather broad and flat, from the
+accumulation of air on the surface of the amber and its flowing back again.
+If it is because the effluvia are thinner, and denser vapours come in
+return, as in breathing, then the body would rather have had a motion
+toward the electrick a little while after the beginning of the application;
+but when electricks which have been rubbed are applied quickly to *  a
+versorium then especially at once they act on the versorium, and it is
+attracted more when near them. But if it is because the rarefied {55}
+effluvia produce a rarefied medium, and on that account bodies are more
+prone to slip down from a denser to a more attenuated medium; they might
+have been carried from the side in this way or downwards, but not to bodies
+above them; or the attraction and apprehension of contiguous bodies would
+have been momentary only. But with a single friction jet and amber draw and
+attract bodies to them strongly and for a long time, sometimes for the
+twelfth part of an hour, especially in clear weather. But if the mass of
+amber be rather large, and the surface polished, it attracts without
+friction. Flint is rubbed and emits by attrition an inflammable matter that
+turns into sparks and heat. Therefore the denser effluvia of flint
+producing fire are very far different from electrical effluvia, which on
+account of their extreme attenuation do not take fire, nor are fit material
+for flame. Those effluvia are not of the nature of breath, for when emitted
+they do not propel anything, but are exhaled without sensible resistance
+and touch bodies. They are highly attenuated humours much more subtile than
+the ambient air; and in order that they may occur, bodies are required
+produced from humour and concreted with a considerable degree of hardness.
+Non-electrick bodies are not resolved into humid effluvia, and those
+effluvia mix with the common and general effluvia of the earth, and are not
+peculiar. Also besides the attraction of bodies, they retain them longer.
+It is probable therefore that amber does exhale something peculiar to *
+itself, which allures bodies themselves, not the intermediate air. Indeed
+it plainly does draw the body itself in the case of a spherical drop of
+water standing on a dry surface; for a piece of amber applied to it at a
+suitable distance pulls the nearest parts out of their position and draws
+it up into a cone; otherwise, if it were * drawn by means of the air
+rushing along, the whole drop would have moved. That it does not attract
+the air is thus demonstrated: take a very thin wax candle, which makes a
+very small and clear flame; bring up to this, within two digits or any
+convenient distance, a piece of amber or jet, a broad flat piece, well
+prepared * and skilfully rubbed, such a piece of amber as would attract
+bodies far and wide, yet it does not disturb the flame; which of necessity
+would have occurred, if the air was disturbed, for the flame would have
+followed the current of air. As far as the effluvia are sent out, so far it
+allures; but as a body approaches, its motion is accelerated, stronger
+forces drawing it; as also in the case of magneticks and in all natural
+motion; not by attenuating or by expelling the air, so that the body moves
+down into the place of the air which has gone out[140]; for thus it would
+have allured only and would not have retained; since it would at first also
+have repelled approaching bodies just as it drives the air itself; but
+indeed a particle, be it ever so small, does not avoid the first
+application made very quickly after rubbing. An effluvium exhales from
+amber and is emitted by rubbing: pearls, carnelian, agate, jasper,
+chalcedony, coral, metals, {56} and other substances of that kind, when
+they are rubbed, produce no effect. Is there not also something which is
+exhaled from them by heat and attrition? Most truly; but from grosser
+bodies more blended with the earthy nature, that which is exhaled is gross
+and spent; for even towards very many electricks, if they are rubbed * too
+hard, there is produced but a weak attraction of bodies, or none at all;
+the attraction is best when the rubbing has been gentle and very quick; for
+so the finest effluvia are evoked. The effluvia arise from the subtile
+diffusion of humour, not from excessive and turbulent violence; especially
+in the case of those substances which have been compacted from unctuous
+matter, which when the atmosphere is very thin, when the North winds, and
+amongst us (English) the East winds, are blowing, have a surer and firmer
+effect, but during South winds and in damp weather, only a weak one; so
+that those * substances which attract with difficulty in clear weather, in
+thick weather produce no motion at all; both because in grosser air lighter
+substances move with greater difficulty; and especially because the
+effluvia are stifled, and the surface of the body that has been rubbed is
+affected by the spent humour of the air, and the effluvia are stopped at
+their very starting. On that account in the case of amber, jet, and
+sulphur, because they do not so easily take up moist air on their surface
+and are much more plenteously set free, that force is not so quickly
+suppressed as in gems, crystal, glass, and substances of that kind which
+collect on their surface the moister breath which has grown heavy. But it
+may be asked why does amber allure water, when water placed on its surface
+removes its action? Evidently because it is one thing to suppress it at its
+very start, and quite another to extinguish it when it has been * emitted.
+So also thin and very fine silk, in common language _Sarcenet_, placed
+quickly on the amber, after it has been rubbed, * hinders the attraction of
+the body; but if it is interposed in the intervening space, it does not
+entirely obstruct it. Moisture also from spent air, and any breath blown
+from the mouth, as well as water put on the amber, immediately extinguishes
+its force. But oil, which is light and pure, does not hinder it; for
+although amber * be rubbed with a warm finger dipped in oil, still it
+attracts. But * if that amber, after the rubbing, is moistened with _aqua
+vitae_ or spirits of wine, it does not attract; for it is heavier than oil,
+denser, and when added to oil sinks beneath it. For oil is light and rare,
+and does not resist the most delicate effluvia. A breath therefore,
+proceeding from a body which had been compacted from humour or from a
+watery liquid, reaches the body to be attracted; the body that is reached
+is united with the attracting body, and the one body lying near the other
+within the peculiar radius of its effluvia makes one out of two; united,
+they come together into the closest accord, and this is commonly called
+attraction. This unity, according to {57} the opinion of Pythagoras, is the
+principle of all things, and through participation in it each several thing
+is said to be one. For since no action can take place by means of matter
+unless by contact, these electricks are not seen to touch, but, as was
+necessary, something is sent from the one to the other, something which may
+touch closely and be the beginning of that incitement. All bodies are
+united and, as it were, cemented together in some way by moisture; so that
+a wet body, when it touches another body, attracts it, if it is small. So
+wet bodies on the surface of water attract wet bodies. But the peculiar
+electrical effluvia, which are the most subtile material of diffuse humour,
+entice corpuscles. Air (the common effluvium of the earth) not only unites
+the disjointed parts, but the earth calls bodies back to itself by means of
+the intervening air; otherwise bodies which are in higher places would not
+so eagerly make for the earth. Electrical effluvia differ greatly from air;
+and as air is the effluvium of the earth, so electricks have their own
+effluvia and properties, each of them having by reason of its peculiar
+effluvia a singular tendency toward unity, a motion toward its origin and
+fount, and toward the body emitting the effluvia. But those substances
+which by attrition emit a gross or vapourous or aeriform effluvium produce
+no effect; for either such effluvia are alien to the humour (the uniter of
+all things), or being very like common air are blended with the air and
+intermingle with the air, wherefore they produce no effect in the air, and
+do not cause motions different from those so universal and common in
+nature. In like manner * bodies strive to be united and move on the surface
+of water, just [Illustration] as the rod C, which is put a little way under
+water. It is plain that the rod E F, which floats on the water by reason of
+the cork H, and only has its wet end F above the surface of the water, is
+attracted by the rod C, if the rod C is wet a little above the surface of
+the water; they are suddenly united, just as a drop adjoining a drop is
+attracted. So a wet thing on the surface of water seeks union with a wet
+thing, since the surface of the water is raised on both; and they
+immediately flow together, just like drops or bubbles. But they are in much
+greater proximity than electricks, and are united by their clammy natures.
+If, however, the whole rod be dry * above the water, it no longer attracts,
+but drives away the stick E F. The same is seen in those bubbles also which
+are made on {58} water. For we see one drive towards another, and the
+quicker the nearer they are. Solids are impelled towards solids by the
+medium of liquid: for example, touch the end of a versorium with the end of
+a rod on which a drop of water is projecting; as soon as the versorium
+touches the top of the droplet, immediately it is joined * strongly by a
+swift motion to the body of the rod. So concreted humid things attract when
+a little resolved into air (the effluvia in the intermediate space tending
+to produce unity); for water has on wet bodies, or on bodies wet with
+abundant moisture on the top of water, the force of an effluvium. Clear air
+is a convenient medium for an electrical effluvium excited from concreted
+humour. Wet bodies projecting above the surface of water (if they are near)
+run together so that they may unite; for the surface of the water is raised
+around wet substances. But a dry thing is not impelled to a wet one, nor a
+wet to a dry, but seems to run away. For if all is dry above the water, the
+surface of the water close to it does not rise, but shuns it, the wave
+sinking around a dry thing. So neither does a wet thing move towards the
+dry rim of a vessel; but it seeks [Illustration] a wet rim. A B is the
+surface of the water; C D two rods, which stand up wet above the water; it
+is manifest that the surface of the water is raised at C and D along with
+the rods; and therefore the rod C, by reason of the water standing up
+(which seeks its level and unity), moves with the water to D. On E, on the
+other hand, a wet rod, the water also rises; but on the dry rod F the
+surface is depressed; and as it drives to depress also the wave rising on E
+in its neighbourhood, the higher wave at E turns away from F[141]; for it
+does not suffer itself to be depressed. All electrical attraction occurs
+through an intervening humour; so it is by reason of humour that all things
+mutually come together; fluids indeed and aqueous bodies on the surface of
+water, but concreted things, if they have been resolved into vapour, in
+air;--in air indeed, the effluvium of electricks being very rare, that it
+may the better permeate the medium and not impel it by its motion; for if
+that effluvium had been thick, as that of air, or of the winds, or of
+saltpetre burnt by fire, as the thick and foul effluvia given out with very
+great force, from other bodies, or air set free from humour by heat rushing
+out through a pipe (in the instrument of Hero of Alexandria, described in
+his {59} book _Spiritalia_), then the effluvium would drive everything
+away, not allure it. But those rarer effluvia take hold of bodies and
+embrace them as if with arms extended, with the electricks to which they
+are united; and they are drawn to the source, the effluvia increasing in
+strength with the proximity. But what is that effluvium from crystal,
+glass, and diamond, since these are bodies of considerable hardness and
+firmly concreted? In order that such an effluvium should be produced, there
+is no need of any marked or perceptible flux[142] of the substance; nor is
+it necessary that the electrick should be abraded, or worn away, or
+deformed. Some odoriferous substances are fragrant for many years, exhaling
+continually, yet are not quickly consumed. Cypress wood as long as it is
+sound, and it lasts a very long time indeed, is redolent; as many learned
+men attest from experience. Such an electrick only for a moment, when
+stimulated by friction, emits powers far more subtile and more fine beyond
+all odours; yet sometimes amber, jet, sulphur, when they are somewhat
+easily let free into vapour, also pour out at the same time an odour; and
+on this account they allure with the very gentlest rubbing, often even
+without rubbing; they also excite more strongly, and retain hold for a
+longer time, because they have stronger effluvia and last longer. But
+diamond, glass, rock-crystal, * and numerous others of the harder and
+firmly concreted gems first grow warm: therefore at first they are rubbed
+longer, and then they also attract strongly; nor are they otherwise set
+free into vapour. Everything rushes towards electricks[143] excepting
+flame, and flaming bodies, and the thinnest air. Just as they do not draw
+flame, in like manner they do not affect a versorium, if on any side it is
+very near to a flame, either the flame of a lamp or of any burning matter.
+It is manifest indeed that the effluvia are destroyed by flame and igneous
+* heat; and therefore they attract neither flame nor bodies very near a
+flame. For electrical effluvia have the virtue of, and are analogous with,
+extenuated humour; but they will produce their effect, union and
+continuity, not by the external impulse of vapours, not by heat and
+attenuation of heated bodies, but by their humidity itself attenuated into
+its own peculiar effluvia. Yet they entice * smoke sent out by an
+extinguished light; and the more that smoke is attenuated in seeking the
+upper regions, the less strongly is it turned aside; for things that are
+too rarefied are not drawn to them; and at length, when it has now almost
+vanished, it does not * incline towards them at all, which is easily seen
+against the light. When in fact the smoke has passed into air, it is not
+moved, as has been demonstrated before. For air itself, if somewhat thin,
+is not attracted in any way, unless on account of succeeding that which has
+vacated its place, as in furnaces and such-like, where the air is fed in by
+mechanical devices for drawing it in. Therefore an effluvium resulting from
+a non-fouling friction, and one which {60} is not changed by heat, but
+which is its own, causes union and coherency, a prehension and a congruence
+towards its source, if only the body to be attracted is not unfitted for
+motion, either by the surroundings of the bodies or by its own weight. To
+the bodies therefore of the electricks themselves small bodies are borne.
+The effluvia extend out their virtue--effluvia which are proper and
+peculiar to them, and _sui generis_, differing from common air, being
+produced from humour, excited by a calorifick motion from attrition and
+attenuation. And as if they were material rays[144], they hold and take up
+chaff, straws, and twigs, until they become extinct or vanish away: and
+then they (the corpuscles) being loosed again, attracted by the earth
+itself, fall down to the earth. The difference between Magneticks and
+Electricks[145] is that all magneticks run together with mutual forces;
+electricks only allure; that which is allured is not changed by an
+implanted force, but that which has moved up to *  them voluntarily rests
+upon them by the law of matter. Bodies are borne towards electricks in a
+straight line towards the centre of the electrick; a loadstone draws a
+loadstone directly at the poles only, in other parts obliquely and
+transversely, and in this way also they adhere and hang to one another.
+Electrical motion is a motion of aggregation of matter; magnetical motion
+is one of disposition and conformation. The globe of the earth is
+aggregated and cohaeres by itself electrically. The globe of the earth is
+directed and turned magnetically; at the same time also it both cohaeres,
+and in order that it may be solid, is in its inmost parts cemented
+together.
+
+       *       *       *       *       *
+
+
+CHAP. III.
+
+Opinions of others on Magnetick Coition,
+_which they call Attraction_.
+
+Discussion having now been made concerning electricks, the causes of
+magnetick coition must be set forth. We say coition, not attraction[146].
+The word attraction unfortunately crept into magnetick philosophy from the
+ignorance of the ancients; for there seems to be force applied where there
+is attraction and an imperious violence dominates. For, if ever there is
+talk about magnetick attraction, we understand thereby magnetick coition,
+or a primary running together. Now in truth it will not be useless here
+first briefly to set forth the views given by others, both the ancient {61}
+and the more modern writers. Orpheus in his hymns[147] narrates that iron
+is attracted by loadstone as the bride to the arms of her espoused.
+Epicurus holds that iron is attracted by a loadstone just as straws by
+amber; "and," he adds, "the Atoms and indivisible particles which are given
+off by the stone and by the iron fit one another in shape; so that they
+easily cling to one another; when therefore these solid particles of stone
+or of iron strike against one another, then they rebound into space, being
+brought against one another by the way, and they draw the iron along with
+them." But this cannot be the case in the least; since solid and very dense
+substances interposed, even squared blocks of marble, do not obstruct this
+power, though they can separate atoms from atoms; and the stone and the
+iron would be speedily dissipated into such profuse and perpetual streams
+of atoms. In the case of amber, since there is another different method of
+attracting, the Epicurean atoms cannot fit one another in shape. Thales, as
+Aristotle writes, _De Anima_, Bk. I., deemed the loadstone to be endowed
+with a soul of some sort, because it had the power of moving and drawing
+iron towards it. Anaxagoras also held the same view. In the _Timaeus_ of
+Plato there is an idle fancy[148] about the efficacy of the stone of
+Hercules. For he says that "all flowings of water, likewise the fallings of
+thunderbolts, and the things which are held wonderful in the attraction of
+Amber, and of the Herculean stone, are such that in all these there is
+never any attraction; but since there is no vacuum, the particles drive one
+another mutually around, and when they are dispersed and congregated
+together, they all pass, each to its proper seat, but with changed places;
+and it is forsooth, on account of these intercomplicated affections that
+the effects seem to arouse the wonder in him who has rightly investigated
+them." Galen does not know why Plato should have seen fit to select the
+theory of circumpulsion rather than that of attraction (differing almost on
+this point alone from Hippocrates), though indeed it does not agree in
+reality with either reason or experiment. Nor indeed is either the air or
+anything else circumpelled; and the bodies themselves which are attracted
+are carried towards the attracting substance not confusedly, or in an orbe.
+Lucretius, the poet of the Epicurean sect, sang his opinion of it thus:
+
+                      [149]_First, then, know,_
+  _Ceaseless effluvia from the magnet flow,--_
+  _Effluvia, whose superior powers expel_
+  _The air that lies between the stone and steel._
+  _A vacuum formed, the steely atoms fly_
+  _In a link'd train, and all the void supply;_
+  _While the whole ring to which the train is join'd_
+  _The influence owns, and follows close behind. &c._
+
+{62} Such a reason Plutarch also alleges in the _Quaestiones Platonicae_:
+That that stone gives off heavy exhalations, whereby the adjacent air,
+being impelled along, condenses that which is in front of it; and that air,
+being driven round in an orbe and reverting to the place it had vacated,
+drags the iron forcibly along with it. The following explanation of the
+virtues of the loadstone and of amber is propounded by Johannes Costaeus of
+Lodi[150]. For he would have it that "there is mutual work and mutual
+result, and therefore the motion is partly due to the attraction of the
+loadstone and partly to a spontaneous movement on the part of the iron: For
+as we say that vapours issuing from the loadstone hasten by their own
+nature to attract the iron, so also the air repelled by the vapours, whilst
+seeking a place for itself, is turned back, and when turned back, it impels
+the iron, lifts it up, as it were, and carries it along; the iron being of
+itself also excited somehow. So by being drawn out and by a spontaneous
+motion, and by striking against another substance, there is in some way
+produced a composite motion, which motion would nevertheless be rightly
+referred to attraction, because the terminus from which this motion
+invariably begins is the same terminus at which it ends, which is the
+characteristic proper of an attraction." There is certainly a mutual
+action, not an operation, nor does the loadstone attract in that way; nor
+is there any impulsion. But neither is there that origination of the motion
+by the vapours, and the turning of them back, which opinion of Epicurus has
+so often been quoted by others. Galen errs in his _De Naturalibus
+Facultatibus_, Book I., chap. 14, when he expresses the view that whatever
+agents draw out either the venom of serpents or darts also exhibit the same
+power as the loadstone. Now of what sort may be the attraction of such
+medicaments (if indeed it may be called attraction) we shall consider
+elsewhere. Drugs against poisons or darts have no relation to, no
+similitude with, the action of magnetical bodies. The followers of Galen
+(who hold that purgative medicaments attract because of similitude of
+substance) say that bodies are attracted on account of similitude, not
+identity, of substance; wherefore the loadstone draws iron, but iron does
+not draw iron. But we declare and prove that this happens in primary
+bodies, and in those bodies that are pretty closely related to them and
+especially like in kind one to another, on account of their identity;
+wherefore also loadstone draws loadstone and likewise iron iron; every
+really true earth draws earth; and iron fortified by a loadstone within the
+orbe of whose virtue it is placed draws iron more strongly than it does the
+loadstone. Cardan asks why no other metal is attracted by any other stone;
+because (he replies) no metal is so cold as iron; as if indeed cold were
+the cause of the attraction, or as if iron were much colder than lead,
+which neither follows nor is deflected towards a loadstone. {63} But that
+is a chilly story, and worse than an old woman's tale. So also is the
+notion that the loadstone is alive and that iron is its food. But how does
+the loadstone feed on the iron, when the filings in which it is kept are
+neither consumed nor become lighter? Cornelius Gemma, _Cosmographia_, Bk.
+X.[151], holds that the loadstone draws iron to it by insensible rays, to
+which opinion he conjoins a story of a sucking fish and another about an
+antelope. Guilielmus Puteanus[152] derives it, "not from any property of
+the whole substance unknown to any one and which cannot be demonstrated in
+any way (as Galen, and after him almost all the physicians, have asserted),
+but from the essential nature of the thing itself, as if moving from the
+first by itself, and, as it were, by its own most powerful nature and from
+that innate temperament, as it were an instrument, which its substance, its
+effective nature uses in its operations, or a secondary cause and deprived
+of its intermediary"; so the loadstone attracts the iron not without a
+physical cause and for the sake of some good. But there is no such thing in
+other substances springing from some material form; unless it were primary,
+which he does not recognize. But certes good is shown to the loadstone by
+the stroke of the iron (as it were, association with a friend); yet it
+cannot either be discovered or conceived how that disposition may be the
+instrument of form. For what can temperament do in magnetical motions,
+which must be compared with the fixed, definite, constant motions of the
+stars, at great distances in case of the interposition of very dense and
+thick bodies? To Baptista Porta[153] the loadstone seems a sort of mixture
+of stone and iron, in such a way that it is an iron stone or stony iron.
+"But I think" (he says) "the Loadstone is a mixture of stone and iron, as
+an iron stone, or a stone of iron. Yet do not think the stone is so changed
+into iron, as to lose its own Nature, nor that the iron is so drowned in
+the stone, but it preserves itself; and whilst one labours to get the
+victory of the other, the attraction is made by the combat between them. In
+that body there is more of the stone than of iron; and therefore the iron,
+that it may not be subdued by the stone, desires the force and company of
+iron; that being not able to resist alone, it may be able by more help to
+defend itself.... The Loadstone draws not stones, because it wants them
+not, for there is stone enough in the body of it; and if one Loadstone draw
+another, it is not for the stone, but for the iron that is in it." As if in
+the loadstone the iron were a distinct body and not mixed up as the other
+metals in their ores! And that these, being so mixed up, should fight with
+one another, and should extend their quarrel, and that in consequence of
+the battle auxiliary forces should be called in, is indeed absurd. But iron
+itself, when excited by a loadstone, seizes iron no less strongly than the
+loadstone. Therefore those fights, seditions, and conspiracies in the
+stone, as if it were nursing up perpetual quarrels, {64} whence it might
+seek auxiliary forces, are the ravings of a babbling old woman, not the
+inventions of a distinguished mage. Others have lit upon sympathy as the
+cause. There may be fellow-feeling, and yet the cause is not
+fellow-feeling; for no passion can rightly be said to be an efficient
+cause. Others hold likeness of substance, many others insensible rays as
+the cause; men who also in very many cases often wretchedly misuse rays,
+which were first introduced in the natural sciences by the mathematicians.
+More eruditely does Scaliger[154] say that the iron moves toward the
+loadstone as if toward its parent, by whose secret principles it may be
+perfected, just as the earth toward its centre. The Divine Thomas[155] does
+not differ much from him, when in the 7th book of his _Physica_ he
+discusses the reasons of motions. "In another way," he says, "it may be
+said to attract a thing, because it moves it to itself by altering it in
+some way, from which alteration it happens that when altered it moves
+according to its position, and in this manner the loadstone is said to
+attract iron. For as the parent moves things whether heavy or light, in as
+far as it gives them a form, by means of which they are moved to their
+place; so also the loadstone gives a certain quality to the iron, in
+accordance with which it moves towards it." This by no means ill-conceived
+opinion this most learned man shortly afterwards endeavoured to confirm by
+things which had obtained little credence respecting the loadstone and the
+adverse forces of garlick. Cardinal Cusan[156] also is not to be despised.
+"Iron has," he says, "in the loadstone a certain principle of its own
+effluence; and whilst the loadstone by its own presence excites the heavy
+and ponderous iron, the iron is borne by a wonderful yearning, even above
+the motion of nature (by which in accordance with its weight it ought to
+tend downwards) and moves upwards, in uniting itself with its own
+principle. For if there were not in the iron a certain natural foretaste of
+the loadstone itself, it would not move to the loadstone any more than to
+any other stone; and unless there were in the stone a greater inclination
+for iron than for copper, there would not be that attraction." Such are the
+opinions expressed about the loadstone attracting (or the general sense of
+each), all dubious and untrustworthy. But those causes of the magnetical
+motions, which in the schools of the Philosophers are referred to the four
+elements and the prime qualities, we relinquish to the moths and the worms.
+
+       *       *       *       *       *
+
+
+{65} CHAP. IIII.
+
+On Magnetick Force & Form, what it is; and on the
+_cause of the Coition_.
+
+Relinquishing the opinions of others on the attraction of loadstone, we
+shall now show the reason of that coition and the translatory nature of
+that motion. Since there are really two kinds of bodies, which seem to
+allure bodies with motions manifest to our senses, Electricks and
+Magneticks, the Electricks produce the tendency by natural effluvia from
+humour; the Magneticks by agencies due to form, or rather by the prime
+forces. This form is unique, and particular, not the formal cause of the
+Peripateticks, or the specifick in mixtures, or the secondary form; not the
+propagator of generating bodies, but the form of the primary and chief
+spheres and of those parts of them which are homogeneous and not corrupted,
+a special entity and existence, which we may call a primary and radical and
+astral form; not the primary form of Aristotle, but that unique form, which
+preserves and disposes its own proper sphere. There is one such in each
+several globe, in the Sun, the moon, and the stars; one also in the earth,
+which is that true magnetick potency which we call the primary vigour.
+Wherefore there is a magnetick nature peculiar to the earth and implanted
+in all its truer parts in a primary and astonishing manner; this is neither
+derived nor produced from the whole heaven by sympathy or influence or more
+occult qualities, nor from any particular star; for there is in the earth a
+magnetick vigour of its own, just as in the sun and moon there are forms of
+their own, and a small portion of the moon settles itself in moon-manner
+toward its termini and form; and a piece of the sun to the sun, just as a
+loadstone to the earth and to a second loadstone by inclining itself and
+alluring in accordance with its nature. We must consider therefore about
+the earth what magnetical bodies are, and what is a magnet; then also about
+the truer parts of it, which are magnetical, and how they are affected as a
+result of the coition. A body which is attracted by an electrick is not
+changed by it, but remains unshaken and unchanged, as it was before, nor
+does it excel any the more in virtue. A loadstone draws magnetical
+substances, which eagerly acquire power from its strength, not in their
+extremities only, but in their inward parts and * their very marrow. For
+when a rod of iron is laid hold of, it is magnetically excited in the end
+by which it is laid hold of, and that {66} force penetrates even to the
+other extremity, not through its surface only, but through the interior and
+all through the middle. Electrical bodies have material and corporeal
+effluvia. Is any such magnetical effluvium given off, whether corporeal or
+incorporeal? or is nothing at all given off that subsists? If it really has
+a body, that body must be thin and spiritual, since it is necessary that it
+should be able to enter into iron. Or what sort of an exhalation is it that
+comes from lead, when quicksilver which is bright and fluid is bound
+together by the odour merely and vapour of the lead, and remains, as it
+were, a firm metal? But even gold, which is exceedingly solid and dense, is
+reduced to a powder by the thin vapour of lead. Or, seeing that, as the
+quicksilver has entrance into gold, so the magnetical odour has entrance
+into the substance of the iron, how does it change it in its essential
+property, although no change is perceptible to our senses in the bodies
+themselves? For without ingression into the body, the body is not changed,
+as the Chemists not incorrectly teach. But if indeed these things resulted
+from a material ingression, then if strong and dense and thick substances
+had been interposed between the bodies, or if magnetical substances had
+been inclosed in the centres of the most solid and the densest bodies, the
+iron particles would not have suffered anything from the loadstone. But
+none the less they strive to come together and are changed. Therefore there
+is no such conception and origin of the magnetick powers; nor do the very
+minute portions of the stone exist, which have been wrongly imagined to
+exist by Baptista Porta, aggregated, as it were, into hairs, and arising
+from the rubbing of the stone which, sticking to the iron, constitute its
+strength. Electrick effluvia are not only impeded by any dense matter, but
+also in like manner by flames, or if a small flame is near, they do not
+allure. But as iron is not hindered by any obstacle from receiving force or
+motion from a loadstone, so it will pass through the midst of flames to the
+body of the loadstone and adhaere to the stone. Let there be a flame or a
+candle near the stone; bring up a short piece of iron wire, and when it has
+come near, it will penetrate through the midst of the flames to the stone;
+* and a versorium turns towards the loadstone nor more slowly nor less
+eagerly through the midst of flames than through open air. So flames
+interposed do not hinder the coition. But if the iron itself became heated
+by a great heat, it is demonstrable that it would not be attracted. Bring a
+strongly ignited rod of iron near a magnetized versorium; the versorium
+remains steady and does not turn towards * such iron; but it immediately
+turns towards it, so soon as it has lost somewhat of its heat. When a piece
+of iron has been touched by a loadstone, if it be placed in a hot fire
+until it is perfectly red hot * and remain in the fire some considerable
+time, it will lose that magnetick strength it had acquired. Even a
+loadstone itself through a {67} longish stay in the fire, loses the powers
+of attracting implanted and innate in it, and any other magnetick powers.
+And although certain veins of loadstone exhale when burnt a dark vapour of
+a black colour, or of a sulphurous foul odour, yet that vapour was not the
+soul, or the cause of its attraction of iron (as Porta thinks), nor do all
+loadstones whilst they are being baked or burnt smell of or exhale sulphur.
+It is acquired as a sort of inborn defect from a rather impure mine or
+matrix. Nor does anything analogous penetrate into the iron from that
+material corporeal cause, since the iron conceives the power of attracting
+and verticity from the loadstone, even if glass or gold or any other stone
+be interposed. Then also cast iron acquires the power of attracting iron,
+and verticity, from the verticity of the earth, as we shall afterwards
+plainly demonstrate in _Direction_. But fire destroys the magnetick virtues
+in a stone, not because it takes away any parts specially attractive, but
+because the consuming force of the flame mars by the demolition of the
+material the form of the whole; as in the human body the primary faculties
+of the soul are not burnt, but the charred body remains without faculties.
+The iron indeed may remain after the burning is completed and is not
+changed into ash or slag; nevertheless (as Cardan not inaptly says) burnt
+iron is not iron, but something placed outside its nature until it is
+reduced. For just as by the rigour of the surrounding air[157] water is
+changed from its nature into ice; so iron, glowing in fire, is destroyed by
+the violent heat, and has its nature confused and perturbed; wherefore also
+it is not attracted by a loadstone, and even loses that power of attracting
+in whatever way acquired, and acquires another verticity when, being, as it
+were, born again, it is impregnated by a loadstone or the earth, or when
+its form is revived, not having been dead but confused, concerning which
+many things are manifest in the change of verticity. Wherefore
+Fracastorio[158] does not confirm his opinion, that the iron is not
+altered; "for if it were altered," he says, "by the form of the loadstone,
+the form of the iron would have been spoiled." This alteration is not
+generation, but the restitution and reformation of a confused form. There
+is not therefore anything corporeal which comes from the loadstone or which
+enters the iron, or which is sent back from the iron when it is stimulated;
+but loadstone disposes loadstone by its primary form; iron, however, which
+is closely related to it, loadstone at the same time recalls to its
+conformate strength, and settles it; on account of which it rushes to the
+loadstone and eagerly conforms itself to it (the forces of each in harmony
+bringing them together). The coition also is not vague or confused, not a
+violent inclination of body to body, no rash and mad congruency; no
+violence is here applied to the bodies; there are no strifes or discords;
+but there is that concord (without which the universe would go to pieces),
+that analogy, namely, of the {68} perfect and homogeneous parts of the
+spheres of the universe to the whole, and a mutual concurrency of the
+principal forces in them, tending to soundness, continuity, position,
+direction, and to unity. Wherefore in the case of such wonderful action and
+such a stupendous implanted vigour (diverse from other natures) the opinion
+of Thales of Miletus[159] was not very absurd, nor was it downright
+madness, in the judgment of Scaliger, for him to grant the loadstone a
+soul; for the loadstone is incited, directed, and orbitally moved by this
+force, which is all in all, and, as will be made clear afterwards, all in
+every part; and it seems to be very like a soul. For the power of moving
+itself seems to point to a soul; and the supernal bodies, which are also
+celestial, divine, as it were, are thought by some to be animated, because
+they move with admirable order. If two loadstones be set one over against
+the other, each in a boat, on the surface of water, they do not immediately
+run together, but first they turn towards one another, or the lesser
+conforms to the greater, by moving itself in a somewhat circular manner,
+and at length, when they are disposed according to their nature, they run
+together. In smelted iron which has not been excited by a magnet there is
+no need for such an apparatus; since it has no verticity, excepting what is
+adventitious and acquired, and that not stable and confirmed (as is the
+case with loadstone, even if the iron has been smelted from the best
+loadstone), on account of the confusion of the parts by fire when it flowed
+as a liquid; it suddenly acquires polarity and natural aptitude by the
+presence of the loadstone, by a powerful mutation, and by a conversion into
+a perfect magnet, and by an absolute metamorphosis; and it flies to the
+body of the magnet as if it were a real piece of loadstone. For a loadstone
+has no power, nor can a perfect loadstone do anything which iron when
+excited by loadstone cannot perform, even when it has not been touched but
+only placed in its vicinity. For when first it is within the orbe of virtue
+of the loadstone, though it may be some distance away, yet it is
+immediately changed, and has a renovated form, formerly indeed dormant and
+inert in body, now lively and strong, which will be clearly apparent in the
+demonstrations of _Direction_. So the magnetick coition is a motion of the
+loadstone and of the iron, not an action of one[160]; an [Greek:
+entelecheia], of each, not [Greek: ergon]; a [Greek: sunentelecheia] or
+conjoint action, rather than a sympathy. There is properly no such thing as
+magnetick antipathy. For the flight and declination of the ends, or an
+entire turning about, is an action of each towards unity by the conjoint
+action and [Greek: sunentelecheia] of both. It has therefore newly put on
+the form, and on account of this being roused, it then, in order that it
+may more surely acquire it, rushes headlong on the loadstone, not with
+curves and turnings, as a loadstone to a loadstone. For since in a
+loadstone both verticity and the power disponent have existed through many
+ages, or from the very beginnings, {69} have been inborn and confirmed, and
+also the special form of the terrestrial globe cannot easily be changed by
+another loadstone, as iron is changed; it happens from the constant nature
+of each, that one has not the sudden power over another of changing its
+verticity, but that they can only mutually come to agreement with each
+other. Again, iron which has been excited by a loadstone, * if that iron on
+account of obstacles should not be able to turn round immediately in
+accordance with its nature, as happens with a versorium, is laid hold of,
+when a loadstone approaches, on either side or at either end. Because, just
+as it can implant, so it can suddenly change the polarity and turn about
+the formal energies to any part whatever. So variously can iron be
+transformed when its form is adventitious and has not yet been long
+resident in the metal. In the case of iron, on account of the fusion of the
+substance when magnetick ore or iron is smelted, the virtue of its primary
+form, distinct before, is now confused; but an entire loadstone placed near
+it again sets up its primal activity; its adjusted and arranged form joins
+its allied strength with the loadstone; and both mutually agree and are
+leagued together magnetically in all their motions towards unity, and
+whether joined by bodily contact or adjusted within the orbe, they are one
+and the same. For when iron is smelted out of its own ore, or steel (the
+more noble kind of iron) out of its ore, that is, out of loadstone, the
+material is loosed by the force of the fire, and flows away, and iron as
+well as steel flow out from their dross and are separated from it; and the
+dross is either spoiled by the force of the fire and rendered useless, or
+is a kind of dregs of a certain imperfection and of mixture in the
+prominent parts of the earth. The material therefore is a purified one, in
+which the metallick parts, which are now mixed up by the melting, since
+those special forces of its form are confused and uncertain, by the
+approach of a loadstone are called back to life, as if to a kind of
+disponent form and integrity. The material is thus awakened and moves
+together into unity, the bond of the universe and the essential for its
+conservation. On this account and by the purging of the material into a
+cleaner body, the loadstone gives to the iron a greater force of attracting
+than there is in itself. For if iron dust * or an iron nail be placed over
+a large loadstone, a piece of iron joined to it takes away the filings and
+nail from the loadstone and retains them so long as it is near the
+loadstone; wherefore iron attracts iron more than loadstone does, if it
+have been conformed by a loadstone and remains within the orbe of its
+communicated form. A piece of iron even, skilfully placed near the pole of
+a loadstone, lifts up more than the loadstone. Therefore the material of
+its own ore is better, and by the force of fire steel and iron are
+re-purged; and they are again impregnated by the loadstone with its own
+forms; therefore they move towards it by a spontaneous {70} approach as
+soon as they have entered within the orbe of the magnetick forces, because
+they were possessed by it before, connected and united with it in a perfect
+union; & they have immediately an absolute continuity within that orbe, &
+have been joined on account of their harmony, though their bodies may have
+been disjoined. For the iron is not taken possession of and allured by
+material effluvia, after the manner of electricks, but only by the
+immaterial action of its form or an incorporeal progression, which in a
+piece of iron as its subject acts and is conceived, as it were, in a
+continuous homogeneous body, and does not need more open ways. Therefore
+(though the most solid substances be interposed) the iron is still moved
+and attracted, and by the presence of loadstone the iron moves and attracts
+the loadstone itself, and by mutual forces a concurrency is made towards
+unity, which is commonly called attraction of the iron. But those formal
+forces pass out and are united to one another by meeting together; a force
+also, when conceived in the iron, begins to flow out without delay. But
+Julius Scaliger, who by other examples contends that this theory is absurd,
+makes in his 344th Exercise a great mistake. For the virtues of primary
+bodies are not to be compared with bodies formed from and mixed with them.
+He would now have been able (had he been still alive) to discern the nature
+of effused forms in the chapter on forms effused by spherical magneticks.
+But if iron is injured somewhat by rust, it is affected either only
+slightly or not at all by the stone. For the metal is spoiled when eaten
+away and deformed by external injuries or by lapse of time (just as has
+been said about the loadstone), and it loses its prime qualities which are
+conjoined to its form; or, being worn out by age, retains them in a languid
+and weak condition; indeed it cannot be properly re-formed, when it has
+been corrupted. But a powerful and fresh loadstone attracts sound and clean
+pieces of iron, and those pieces of iron (when they have conceived
+strength) have a powerful attraction for other iron wires and iron nails,
+not only one at a time, but even successively one behind another, three,
+four or five, end to end, sticking and hanging in order like a chain. The
+loadstone, however, would not attract the last one following in such a row,
+if there were no nails between. [Illustration] A loadstone placed as at A
+draws a nail or a bar B; similarly behind B it draws C; and after C, D. But
+the nails B and C being removed, the loadstone A, if it remain at the same
+distance, does not raise the nail D into the air. This occurs for this
+reason: because in the case of a continuous row of nails the presence of
+the loadstone A, besides its own powers, raises the magnetick natures of
+the iron works B and C, and makes them, as it were, forces auxiliary to
+itself. But B and C, like a continuous magnetical body, extend as far as
+{71} D the forces by which D is taken and conformed, though they are weaker
+than those which C receives from B. And those iron nails indeed from that
+contact only, and from the presence of the loadstone even without contact,
+acquire powers which they retain in their own bodies, as will be
+demonstrated most clearly in the passage _on Direction_. For not only
+whilst the stone is present does the iron assume these powers, and take
+them, as it were, vicariously from the stone, as Themistius lays down in
+his 8th book on Physicks[161]. The best iron, when it has been melted down
+(such is steel), is allured by a loadstone from a greater distance, is
+raised though of greater weight, is held more firmly, assumes stronger
+powers than the common and less expensive, because it is cast from a better
+ore or loadstone, imbued with better powers. But what is made from more
+impure ore turns out weaker and is moved more feebly. As to
+Fracastorio's[162] statement that he saw a piece of loadstone draw a
+loadstone by one of its faces, but not iron; by another face iron, but not
+loadstone; by another both; which he says is an indication that in one part
+there is more of the loadstone, in another more of the iron, in another
+both equally, whence arises that diversity of attraction; it is most
+incorrect and badly observed on the part of Fracastorio, who did not know
+how to apply skilfully loadstone to loadstone. A loadstone draws iron and
+also a loadstone, if both are suitably arranged and free and unrestrained.
+That is removed more quickly from its position and place which is lighter;
+for the heavier bodies are in weight, the more they resist; but the lighter
+both moves itself to meet the heavier and is allured by the other.
+
+       *       *       *       *       *
+
+
+CHAP. V.
+
+How the Power dwells in the
+_Loadstone_.
+
+That a loadstone attracts loadstone, iron and other magnetical bodies, has
+been shown above in the previous book, and also with what strength the
+magnetick coition is ordered; but now we must inquire how that vigour is
+disposed in a magnetick substance. And indeed an analogy must be inferred
+from a large loadstone. Any magnetick substance joins itself with a
+loadstone strongly, if the loadstone itself is strong; but more weakly,
+when it is somewhat imperfect or has been weakened by some flaw. A
+loadstone does not draw iron equally well with every part; or a magnetick
+substance does not approach every part of a loadstone alike; because a
+loadstone has its points, that is its true poles, in which an exceptional
+virtue excels. Parts nearer the pole are {72} stronger, those far away more
+weak, and yet in all the power is in a certain way equal. The poles of a
+terrella are A, B; the aequinoctial is C, D. At A and B the alluring force
+seems greatest.
+
+[Illustration]
+
+At C and D there is no force alluring magnetick ends to the body, for the
+forces tend toward both poles. But direction is powerful on the aequator.
+At C, D, the distances are equal from both poles; therefore iron which is
+at C, D, when it is allured in contrary ways, does not adhaere with
+constancy; but it remains and is joined to the stone, if only it incline to
+the one or other side. At E there is a greater power of alluring than at F,
+because E is nearer the pole. This is not so because there is really
+greater virtue residing at the pole, but since all the parts are united in
+the whole, they direct their forces towards the pole. From the forces
+flowing from the plane of the aequinoctial towards the pole, the power
+increases. A fixed verticity exists at the pole, so long as the loadstone
+remains whole; if it is divided or broken, the verticity obtains other *
+positions in the parts into which it is divided. For the verticity always
+changes in consequence of any change in the mass, and for this cause, if
+the terrella be divided from A to B, so that there are two stones, the
+poles will not be A, B, in the divided parts, but F, G, and H, I.
+
+[Illustration] {73}
+
+Although these stones now are in agreement with one another, so that F
+would not seek H, yet if A was previously the boreal pole[163], F is now
+boreal, and H also boreal; for the verticity is not changed (as Baptista
+Porta incorrectly affirms in the fourth chapter of his seventh book);
+since, though F and H do not agree, so that the one would incline to the
+other, yet both turn to the same point of the horizon. If the hemisphere H
+I be divided into two quadrants, the one pole takes up its position in H,
+the other in I. The whole mass of the stone, as I have said, retains the
+site of its vertex constant; and any part of the stone, before it was cut
+out from the block[164], might have been the pole or vertex. But concerning
+this more under _Direction_. It is important now to comprehend and to keep
+firmly in mind that the vertices are strong on account of the force of the
+whole, so that (the command being, as it were, divided by the aequinoctial)
+all the forces on one side tend towards the north; but those of an opposite
+way towards the south, so long as the parts are united, as in the following
+demonstration.
+
+[Illustration]
+
+For so, by an infinite number of curves from every point of the equator
+dividing the sphere into two equal parts, and from every point of the
+surface from the aequator towards the North, and from the aequator towards
+the Southern pole, the whole force tends asunder toward the poles. So the
+verticity is from the aequinoctial {74} circle towards the pole in each
+direction. Such is the power reposed in the undivided stone. From A vigour
+is sent to B, from A, B, to C, from A, B, C, to D, and from them likewise
+to E. In like manner from G to H, and so forth, as long as the whole is
+united. But if a piece A B be cut out (although it is near the aequator),
+yet it will be as strong in its magnetical actions as C D or D E, if torn
+away from the whole in equal quantity. For no part excels in special worth
+in the whole mass except by what is owing to the other adjoining parts by
+which an absolute and perfect whole is attained.
+
+_Diagram of Magnetic Vigour
+transmitted from the plane of the Aequator
+to the peripherery of the terella
+or of the earth_
+
+[Illustration]
+
+{75} HEQ is a terrella, E a pole, M the centre, HMQ the aequinoctial plane.
+From every point of the aequinoctial plane vigour extends to the periphery,
+but by various methods; for from A the formal force is transmitted towards
+C, F, N, E, and to every point from C up to E, the pole; but not towards B;
+so neither from G towards C. The power of alluring is not strengthened in
+the part FHG from that which is in GMFE, but FGH increases the force in the
+eminence FE. So no force rises from the internal parts, from the lines
+parallel to the Axis above those parallels, but always inwards from the
+parallels to the pole. From every point of the plane of the equator force
+proceeds to the pole E, but the point F has its powers only from GH, and N
+from OH; but the pole E is strengthened from the whole plane HQ. Wherefore
+in it the mighty power excels (just as in a palace); but in the
+intermediate intervals (as in F) only so much force of alluring is exerted
+as the portion HG of the plane can contribute.
+
+       *       *       *       *       *
+
+
+CHAP. VI.
+
+How magnetick pieces of Iron and smaller
+_loadstones conform themselves to a terrella & to_
+the earth itself, and by them are
+_disposed_.
+
+Coition of those bodies which are divided, and do not naturally cohaere, if
+they are free, occurs through another kind of motion. A terrella sends out
+in an orbe its powers in proportion to its vigour and quality. But when
+iron or any other magnetick of convenient magnitude comes within its orbe
+of virtue, it is allured; but the nearer it comes to the body, the more
+quickly it runs up to it. They move towards the magnet, not as * to a
+centre, nor towards its centre. For they only do this in the case of the
+poles themselves, when namely that which is being allured, and the pole of
+the loadstone, and its centre, are in the same straight line. But in the
+intervening spaces they tend obliquely, just as is evident in the following
+figure, in which it is shown how the influence is extended to the adjoining
+magneticks within the orbe; in the case of the poles straight out.
+
+{76} [Illustration]
+
+The nearer the parts are to the aequinoctial, the more obliquely are
+magneticals allured; but the parts nearer the poles appeal more directly,
+at the poles quite straight. The principle of the turning of all
+loadstones, of those which are round and those which are long, is the same,
+but in the case of the long ones the experiment is easier. For in whatever
+form they are the verticity exists, and there are poles; but on account of
+bad and unequal form, they are often hindered by certain evils. If the
+stone were long, the vertex is at the ends, not on the sides; it allures
+more strongly at the vertex. For the parts bring together stronger forces
+to the pole in right lines than oblique. So the stone and the earth conform
+their magnetick motions by their nature.
+
+       *       *       *       *       *
+
+
+CHAP. VII.
+
+On the Potency of the Magnetick Virtue, and on
+its nature capable of spreading out into an orbe.
+
+From about a magnetical body the virtue magnetical is poured out on every
+side around in an orbe; around a terrella; in the case of other shapes of
+stones, more confusedly and unevenly. But yet there exists in nature no
+orbe or permanent or essential virtue spread through the air, but a magnet
+{77} only excites magneticks at a convenient distance from it. And as light
+comes in an instant (as the opticians teach), so much more[165] quickly is
+the magnetick vigour present within the limits of its strength; and because
+its activity is much more subtile than light, and does not consent with a
+non-magnetick substance, it has no intercourse with air, water, or any
+non-magnetick; nor does it move a magnetick with any motion by forces
+rushing upon it, but being present in an instant, it invites friendly
+bodies. And as light strikes an object, so a loadstone strikes a magnetick
+body and excites it. And just as light does not remain in the air above
+vapours and effluvia, and is not reflected from those spaces, so neither is
+the magnetick ray held in air or water. The appearances of things are
+apprehended in an instant in mirrors and in the eye by means of light; so
+the magnetick virtue seizes upon magneticks. Without the more intangible
+and shining bodies, the appearances of things are not seized or reflected;
+so without magnetical objects the magnetick power is not perceived, nor are
+the forces thus conceived sent back again to the magnetick substance. In
+this, however, the magnetick power excels light, in that it is not hindered
+by any opaque or solid substance, but proceeds freely, and extends its
+forces on every side. In a terrella and globe-shaped loadstone the
+magnetick power is extended outside the body in an orbe; in a longer one,
+however, not in an orbe, but it is extended in an ambit conformably to the
+shape of the stone. As in the somewhat long stone A, the vigour is extended
+to the ambient limit F C D, equidistant on every side from the stone A.
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+{78} CHAP. VIII.
+
+On the geography of the Earth,
+_and of the Terrella_.
+
+Desiring that what follows may be better understood, we must now say
+something also about magnetick circles and limits. Astronomers, in order to
+understand and observe methodically the motion of the planets and the
+revolution of the heavens, and to describe with more accuracy the celestial
+attire of the fixed stars, settled upon certain circles and definite limits
+in the sky (which geographers also imitate), so that the varied face of the
+earth and the beauty of its districts might be delineated. But we, in a way
+differing from them, recognize those limits and circles, and have found
+very many fixed by nature, not merely conceived by the imagination, both in
+the earth and in our terrella. The earth they mark out[166] chiefly by
+means of the aequator and the poles; and those limits indeed have been
+arranged and marked out by nature. The meridians also indicate straight
+paths from pole to pole through distinct points on the aequator; by which
+way the magnetick virtue directs its course and moves. But the tropics and
+arctic circles, as also the parallels, are not natural limits placed on the
+earth; but all parallel circles indicate a certain agreement of the lands
+situated in the same latitude, or diametrically opposite. All these the
+Mathematicians use for convenience, painting them on globes and maps. In
+like manner also in a terrella all these are required; not, however, in
+order that its exterior appearance may be geographically delineated, since
+the loadstone may be perfect, even, and uniform on all sides. And there are
+no upper and lower parts in the earth, nor are there in a terrella; unless
+perchance some one considers those parts superior which are in the
+periphery, and those inferior which are situated more towards the centre.
+
+       *       *       *       *       *
+
+
+{79} CHAP. IX.
+
+On the Aequinoctial Circle of the Earth
+_and of a Terrella_.
+
+As conceived by astronomers the aequinoctial circle is equidistant from
+both poles, cutting the world in the middle, measures the motions of their
+_primum mobile_ or tenth sphere, and is named the zone of the _primum
+mobile_. It is called aequinoctial, because when the sun stands in it
+(which must happen twice in the year) the days are equal to the nights.
+That circle is also spoken of as _aequidialis_, wherefore it is called by
+the Greeks [Greek: isemerinos]. In like manner it is also properly called
+Aequator, because it divides the whole frame of the earth between the poles
+into equal parts. So also an aequator may be rightly assigned to a
+terrella, by which its power is naturally divided, and by the plane of
+which permeating through its centre, the whole globe is divided into equal
+parts both in quantity and strength (as if by a transverse septum) between
+verticities on both sides imbued with equal vigour.
+
+       *       *       *       *       *
+
+
+CHAP. X.
+
+Magnetick Meridians of the Earth.
+
+Meridians have been thought out by the geographer, by means of which he
+might both distinguish the longitude and measure the latitude of each
+region. But the magnetick meridians are infinite, running in the same
+direction also, through fixed and opposite limits on the aequator, and
+through the poles themselves. On them also the magnetick latitude is
+measured, and declinations are reckoned from them; and the fixed direction
+in them tends to the poles, unless it varies from some defect and the
+magnetick is disturbed from the right way. What is commonly called a
+magnetick meridian is not really magnetick, nor is it really a meridian,
+but it is understood to pass through the termini of the variation on the
+horizon. The variation is a depraved deviation from a meridian, nor is it
+fixed and constant in various places on any meridian.
+
+       *       *       *       *       *
+
+
+{80} CHAP. XI.
+
+Parallels.
+
+In parallel circles the same strength and equal power are perceived
+everywhere, when various magneticks are placed on one and the same parallel
+either on the earth or on a terrella. For they are distant from the poles
+by equal intervals and have equal tendencies of declination, and they are
+attracted and held, and they come together with like forces; just as those
+regions which are situated under the same parallel, even if they differ in
+longitude, yet we say possess the same quantity of daylight and a climate
+equally tempered.
+
+       *       *       *       *       *
+
+
+CHAP. XII.
+
+The Magnetick Horizon.
+
+Horizon is the name given to the great circle, separating the things which
+are seen from those which are not seen; so that a half part of the heaven
+always is open and easily seen by us, half is always hidden. This seems so
+to us on account of the great distance of the star-bearing orbe: yet the
+difference is as great as may arise from the ratio of the semi-diameter of
+the earth compared with the semi-diameter of the starry heaven, which
+difference is in fact not perceived by our senses. We maintain, however,
+that the magnetick horizon is a plane level throughout touching the earth
+or a terrella in the place of some one region, with which plane the
+semi-diameter, whether of the earth or of the terrella, produced to the
+place of the region, makes right angles on every side. Such a plane is to
+be considered in the earth itself and also in the terrella, for magnetick
+proofs and demonstrations. For we consider the bodies themselves only, not
+the general appearances of the world. Therefore not with the idea of
+outlook (which varies with the elevations of the lands), but taking it as a
+plane which makes equal angles with the perpendicular, we accept in
+magnetick demonstrations a sensible horizon or boundary, not that which is
+called by Astronomers the rational horizon.
+
+       *       *       *       *       *
+
+
+{81} CHAP. XIII.
+
+On the Axis and Magnetick Poles.
+
+Let the line be called the axis which is drawn in the earth (as in a
+terrella) through the centre to the poles. They are called [Greek: poloi]
+by the Greeks from [Greek: polein], to turn, and by the Latins they are
+also called _Cardines_ or _Vertices_; because the world rotates and is
+perpetually carried around them. We are about to show, indeed, that the
+earth and a terrella are turned about them by a magnetick influence. One of
+them in the earth, which looks towards the Cynosure, is called Boreal and
+Arctic; the other one, opposite to this, is called Austral and Antarctic.
+Nor do these also exist on the earth or on a terrella for the sake of the
+turning merely; but they are also limits of direction and position, both as
+respects destined districts of the world, and also for correct turnings
+among themselves.
+
+       *       *       *       *       *
+
+
+CHAP. XIIII.
+
+Why at the Pole itself the Coition is stronger than in
+_the other parts intermediate between the aequator and the pole;_
+and on the proportion of forces of the coition in
+_various parts of the earth and of the terrella_.
+
+Observation has already been made that the highest power of alluring exists
+in the pole, and that it is weaker and more languid in the parts adjacent
+to the aequator. And as this is apparent in the declination, because that
+disponent and rotational virtue has an augmentation as one proceeds from
+the Aequator towards the poles: so also the coition of magneticks grows
+increasingly fresh by the same steps, and in the same proportion. For in
+the parts more remote from the poles the loadstone does not draw magneticks
+straight down towards its own viscera; but they tend obliquely and they
+allure obliquely. For as the smallest chords in a circle differ from the
+diameter, so much do the forces of attracting differ between themselves in
+different parts of the terrella. {82} For since attraction is coition
+towards a body, but magneticks run together by their versatory tendency, it
+comes about that in the diameter drawn from pole to pole the body appeals
+directly, but in other places less directly. So the less the magnetick is
+turned toward the body, the less, and the more feebly, does it approach and
+adhaere. [Illustration] Just as if A B were the poles and a bar of iron or
+a magnetick fragment C is allured at the part E; yet the end laid hold of
+does not tend towards the centre of the loadstone, but verges obliquely
+towards the pole; and a chord drawn from that end obliquely as the
+attracted body tends is short; therefore it has less vigour and likewise
+less inclination. But as a greater chord proceeds from a body at F, so its
+action is stronger; at G still longer; longest at A, the pole (for the
+diameter is the longest way) to which all the parts from all sides bring
+assistance, in which is constituted, as it were, the citadel and tribunal
+of the whole province, not from any worth of its own, but because a force
+resides in it contributed from all the other parts, just as all the
+soldiers bring help to their own commander. Wherefore also a slightly
+longer stone attracts more than a spherical one, since the length from pole
+to pole is extended, even if the stones are both from the same mine and of
+the same weight and size. The way from pole to pole is longer in a longer
+stone, and the forces brought together from other parts are not so
+scattered as in a round magnet and terrella, and in a narrow one they agree
+more and are better united, and a united stronger force excels and is
+preeminent. A much weaker office, however, does a plane or oblong stone
+perform, when the length is extended according to the leading of the
+parallels, and the pole stops neither on the apex nor in the circle and
+orbe, but is spread over the flat. Wherefore also it invites a friend
+wretchedly, and feebly retains him, so that it is esteemed as one of an
+abject and contemptible class, according to its less apt and less suitable
+figure.
+
+       *       *       *       *       *
+
+
+{83} CHAP. XV.
+
+*
+
+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_.
+
+Duly was it said before that the longer magnet attracts the greater weight
+of iron[167]; so also in a longish piece of iron which has been touched the
+magnetick force conceived is stronger when the poles exist at the ends. For
+the magnetick forces which are driven from the whole in every part into the
+poles are not scattered but united in the narrow ends. In square and other
+angular figures the influence is dissipated, and does not proceed in
+straight lines or in convenient arcs. Suppose also an iron globe have the
+shape of the earth, yet for the same reasons it drags magnetick substances
+less; wherefore a small iron sphere, when excited, draws another piece of
+iron more sluggishly than an excited rod of equal weight.
+
+       *       *       *       *       *
+
+
+CHAP. XVI.
+
+Showing that Movements take place by the Magnetical
+Vigour though solid bodies lie between; and on
+_the interposition of iron plates_.
+
+Float a piece of iron wire on the surface of water by transfixing it
+through a suitable cork; or set a versatory piece of iron on a pin or in a
+seaman's compass (a magnet being brought near or moved about underneath),
+it is put into a state of motion; neither the water, nor the vessel, nor
+the compass-box offering resistance in any way. Thick boards do not
+obstruct[168], nor earthen vessels nor marble vases, nor the metals
+themselves; nothing is so solid as to carry away or impede the forces
+excepting an iron plate. Everything which is interposed (even though it is
+very dense) does not carry away its influence or obstruct its path, or
+indeed in any way hinder, diminish, or retard it. But all the force is not
+suppressed by an iron plate, but it is in some measure diverted aside. For
+when the vigour passes into the middle of an iron plate within the orbe of
+the magnetick virtue or placed just {84} opposite the pole of the stone,
+that virtue is scattered in very large measure towards its extremities; so
+that the edges of a small round * plate of suitable size allure iron wires
+on every side. This is also apparent in the case of a long iron wand,
+which, when it has been touched by a magnet in the middle, has a like
+verticity at either end. *
+
+[Illustration]
+
+B is a loadstone, C D a long rod magnetized in the middle A; E being the
+Boreal pole; C is an Austral end or pole; in like manner also the end D is
+another Austral pole. But observe here the exactness with which a versorium
+touched by a pole, when a round plate is interposed, turns towards the same
+pole in the same * way as before the interposition, only weaker; the plate
+not standing in the way, because the vigour is diverted through the edges
+of the small plate, and passes out of its straight course, but yet the
+plate retains in the middle the same verticity, when it is in the
+neighbourhood of that pole, and close to it; wherefore the versorium tends
+towards the plate, having been touched by the same pole. If a loadstone is
+rather weak, a versorium hardly turns when a plate is put in between; for
+the vigour of the rather weak loadstone, being diffused through the
+extremities, passes less through the * middle. But if the plate has been
+touched in this way by a pole in the middle and has been removed from the
+stone outside its orbe of virtue, then you will see the point of the same
+versorium tend in the contrary direction and desert the centre of the small
+plate, which formerly it desired; for outside the orbe of virtue it has an
+opposite verticity, in the vicinity the same; for in the vicinity it is, as
+it were, a part of the loadstone, and has the same pole.
+
+[Illustration]
+
+A is an iron plate near the pole, B a versorium which tends with its point
+towards the centre of the small plate, which has been touched by the pole
+of the loadstone C. But if the same small plate be {85} placed outside the
+orbe of magnetick virtue, the point will not turn towards its centre, but
+the cross E of the same versorium does. But an iron globe interposed (if it
+is not too large) attracts the * point of the iron on the other side of the
+stone. For the verticity of that side is the same as that of the adjoining
+pole of the stone. And this turning of the cusp (that is, of the end
+touched by that pole) as well as of the cross-end, at a greater distance,
+takes place with an iron globe interposed, which would not happen at all if
+* the space were empty, because the magnetick virtue is passed on and
+continued through magnetick bodies.
+
+[Illustration]
+
+A is a terrella, B an iron globe; between the two bodies is F, a versorium
+whose point has been excited by the pole C. In the other figure A is a
+terrella, C its pole, B an iron globe; where the versorium tends towards C,
+the pole of the terrella, through the iron globe. So a versorium placed
+between a terrella and an iron globe vibrates more forcibly towards the
+pole of the terrella; because the loadstone sends an instantaneous
+verticity into the opposite globe. There is the same efficiency in the
+earth, produced from the same cause. For if a revolvable needle is shut up
+in a rather thick gold box (this metal indeed excels all others in density)
+or a glass or stone box, nevertheless that magnetick needle has its forces
+connected and united with the influences of the earth, and the iron will
+turn freely and readily (unhindered by its prison) to its desired points,
+North and South. * It even does this when shut up in iron caverns, if they
+are sufficiently spacious. Whatever bodies are produced among us, or are
+artificially forged from things which are produced, consist of matter of
+the terrestrial globe; nor do those bodies hinder the prime forces of
+nature which are derived from their primary form, nor can they resist them
+except by contrary forms. But no forms of mixed bodies are inimical to the
+primary implanted earth-nature, although some often do not agree[169] with
+one another. But in the case of all those substances which have a material
+cause for their inclining (as amber, {86} jet, sulphur), their action is
+impeded by the interposition of a body (as paper, leaves, glass, or the
+like) when that way is impeded and obstructed, so that that which
+exhales[170] cannot reach the corpuscle to be allured. Terrestrial and
+magnetick coition and motion, when corporeal impediments are interposed, is
+demonstrated also by the efficiencies of other chief bodies due to their
+primary form. The moon (more than all the stars) agrees with internal parts
+of the earth on account of its nearness and similarity in form. The moon
+produces the movements of the waters and the tides of the sea; twice it
+fills up the shores and empties them whilst it moves from a certain
+definite point in the sky back to the same point in a daily revolution.
+This motion of the waters is incited and the seas rise and fall no less
+when the moon is below the horizon and in the lowest part of the heavens,
+than if it had been raised at a height above the horizon. So the whole mass
+of the earth interposed[171] does not resist the action of the moon, when
+it is below the earth; but the seas bordering on our shores, in certain
+positions of the sky when it is below the horizon, are kept in motion, and
+likewise stirred by its power (though they are not struck by its rays nor
+illuminated by its light), rise, come up with great force, and recede. But
+about the reason of the tides anon[172]; here let it suffice to have merely
+touched the threshold of the question. In like manner nothing on the earth
+can be hidden from the magnetick disposition of the earth or of the stone,
+and all magnetical bodies are reduced to order by the dominant form of the
+earth, and loadstone and iron show sympathy with a loadstone though solid
+bodies be interposed.
+
+       *       *       *       *       *
+
+
+CHAP. XVII.
+
+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._
+
+Conceive a small round plate, concave in shape, of the breadth of a digit
+to be applied to the convex polar surface of a loadstone and skilfully
+attached; or a piece of iron shaped like an acorn, rising from the base
+into an obtuse cone, hollowed out a little and fitted to the surface of the
+stone, to be tied to the loadstone. Let the iron be the best steel,
+smoothed, shining, and even. A loadstone with such an appliance, which
+before only bore four ounces of iron, will now raise twelve. But the
+greatest force of a combining or rather united nature is seen {87} when two
+loadstones, armed with iron caps, are so joined by their concurrent
+(commonly called contrary) ends, that they mutually * attract and raise one
+another. In this way a weight of twenty ounces is raised, when either stone
+unarmed would only allure four ounces of iron. Iron unites to an armed
+loadstone more firmly than to a loadstone; and on that account raises
+greater weights, because the pieces of iron stick more pertinaciously to
+one that is armed. For by the near presence of the magnet they are cemented
+together, and since the armature[173] conceives a magnetick vigour from its
+presence and the other conjoined piece of iron is at the same time endued
+with vigour from the presence of the loadstone, they are firmly bound
+together. Therefore by the mutual contact of strong pieces of iron, the
+cohesion is strong. Which thing is also made clear and is exhibited by
+means of rods sticking together, Bk. 3, chap 4[174]; and also when the
+question of the concretion of iron dust into a united body was discussed.
+For this reason a piece of iron set near a loadstone draws away any
+suitable piece of iron from the loadstone, if only it touch the iron;
+otherwise it does not snatch it away, though in closest proximity. For
+magnetick pieces of iron within the orbe of virtue, or near a loadstone, do
+not rush together with a greater endeavour[175] than the iron and the
+magnet; but joined they are united more strongly and, as it were, cemented
+together, though the substance remain the same with the same forces acting.
+
+       *       *       *       *       *
+
+
+CHAP. XVIII.
+
+An armed Loadstone does not endow an
+excited piece of Iron with greater vigour
+_than an unarmed_.
+
+Suppose there are two pieces of iron, one of * which has been excited by an
+armed loadstone, the other by one unarmed; and let there be applied to one
+of them another piece of iron of a weight just proportional to its
+strength, it is manifest that the remaining one in like manner raises the
+same and no more. Magnetick versoria also touched by an armed loadstone
+turn with the same velocity and constancy towards the poles of the earth as
+those magnetized by the same loadstone unarmed.
+
+       *       *       *       *       *
+
+
+{88} CHAP. XIX.
+
+Union with an armed Loadstone is stronger;
+_hence greater weights are raised; but the_
+coition is not stronger[176], but
+_generally weaker_.
+
+An armed magnet raises a greater weight, as is manifest to all; but a piece
+of iron moves towards a stone at an equal, or rather greater, distance when
+it * is bare, without an iron cap. This must be tried with two pieces of
+iron of the same weight and figure at an equal distance, or with one and
+the same versorium, the test being made first with an armed, then with an
+unarmed loadstone, at equal distances.
+
+       *       *       *       *       *
+
+
+[Illustration]
+
+CHAP. XX.
+
+*
+
+An armed Loadstone raises an armed Loadstone,
+_which also attracts a third; which likewise_
+happens, though the virtue in the first
+_be somewhat small_.
+
+Magnets armed cohaere firmly when duly joined, and accord into one; and
+though the first be rather weak, yet the second one adhaeres to it not only
+by the strength of the first, but of the second, which mutually give
+helping hands; also to the second a third often adheres and in the case of
+robust stones, a fourth to the third.
+
+       *       *       *       *       *
+
+
+{89}
+
+CHAP. XXI.
+
+*
+
+If Paper or any other Medium be interposed,
+an armed loadstone raises no more than an
+_unarmed one_.
+
+Observation has shown above that an armed loadstone does not attract at a
+greater distance than an unarmed one; yet raises iron in greater quantity,
+if it is joined to and made continuous with the iron. But if Paper be
+placed between, that intimate cohaesion of the metal is hindered, nor are
+the metals cemented together at the same time by the operation of the
+magnet.
+
+       *       *       *       *       *
+
+
+[Illustration]
+
+CHAP. XXII.
+
+*
+
+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_.
+
+If a cylinder be lying on a level surface, of too great a weight for an
+unarmed loadstone to lift, and (a piece of paper being interposed) if the
+pole of an armed loadstone be joined to the middle of it; if the cylinder
+were drawn from there by the loadstone, it would follow rolling; but if no
+medium were interposed, the cylinder would be drawn along firmly united
+with the armed loadstone, and in no wise rolling. But if the same loadstone
+be unarmed, it will draw the cylinder rolling with the same speed as the
+armed loadstone with the paper between or when it was wrapped in paper.
+
+Armed loadstones of diverse weights, of the same ore vigour * and form,
+cling and hang to pieces of iron of a convenient size and proportionate
+figure with an equal proportion of strength. The same is apparent in the
+case of unarmed stones. A suitable piece * of iron being applied to the
+lower part of a loadstone, which is * hanging from a magnetick body,
+excites its vigour, so that the loadstone hangs on more firmly. For a
+pendent loadstone clings {90} more firmly to a magnetick body joined to it
+above with a hanging piece of iron added to it, than when lead or any other
+non-magnetick body is hung on.
+
+A loadstone, whether armed or unarmed, * joined by its proper pole to the
+pole of another loadstone, armed or unarmed, makes the loadstone raise a
+greater weight by the opposite end[177]. A piece of iron also applied to
+the pole of a magnet produces the same result, namely, that the other pole
+will carry a greater weight of iron; just as a loadstone with a piece of
+iron superposed on it (as in this figure) holds up a piece of iron below,
+which it cannot hold, if the upper one be removed. * Magneticks in
+conjunction make one magnetick. Wherefore as the mass increases, the
+magnetick vigour is also augmented.
+
+An armed loadstone, as well as an unarmed * one, runs more readily to a
+larger piece of iron and combines more firmly with a larger piece than with
+a lesser one.
+
+       *       *       *       *       *
+
+
+CHAP. XXIII.
+
+Magnetick Force causes motion towards unity,
+_and binds firmly together bodies which are united_.
+
+Magnetick fragments cohaere within their strength well and harmoniously
+together. Pieces of iron in the presence of a loadstone (even if they are
+not * touching the loadstone) run together, seek one another anxiously and
+embrace one another, and when joined are as if they were cemented. Iron *
+filings or the same reduced to powder inserted in paper tubes, placed upon
+a stone meridionally or merely brought rather close to it, coalesce into
+one body, and so many parts suddenly are concreted * and combine; and the
+whole company of corpuscles thus conspiring together affects another piece
+of iron and attracts it, as if it constituted one integral rod of iron; and
+above the stone it is directed toward the North and South. But when they
+are removed a long * {91} way from the stone, the particles (as if loosed
+again) are separated and move apart singly. In this way also the
+foundations of the world are connected and joined and cemented together
+magnetically. So let Ptolemy of Alexandria, and his followers, and those
+philosophers of ours, be the less terrified if the earth do move round in a
+circle, nor threaten its dissolution.
+
+Iron filings, after being heated for a long time, are attracted by a
+loadstone, yet not so strongly or from so great a distance as when not
+heated. A loadstone loses some of its virtue by too great a heat; for its
+humour is set free, whence its peculiar nature is marred. Likewise also, if
+iron filings are well burnt in a reverberatory furnace and converted into
+saffron of Mars, they are not attracted by a loadstone; but if they are
+heated, but not thoroughly burnt, they do stick to a magnet, but less
+strongly than the filings themselves not acted upon by fire. For the
+saffron has become totally deformate, but the heated metal acquires a
+defect from the fire, and the forces in the enfeebled body are less excited
+by a loadstone; and, the nature of the iron being now ruined, it is not
+attracted by a loadstone.
+
+       *       *       *       *       *
+
+
+CHAP. XXIIII.
+
+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_.
+
+Within the magnetick orbe a piece of iron moves towards the more powerful
+points of the stone, if it be not hindered by force or by the material of a
+body placed between them; either it falls down from above, or tends
+sideways or obliquely, or flies up above. But if the iron cannot reach the
+stone on account of some obstacle, it cleaves to it and remains there, but
+with a less firm and constant connection, since at greater intervals or
+distances the alliance is less amicable. Fracastorio, in the eighth chapter
+of his _De Sympathia_, says that a piece of iron is suspended in the air,
+so that it can be moved neither up nor down, if a loadstone be placed above
+which is able to draw the iron up just as much as the iron itself inclines
+downwards with equal force; for thus the iron would be supported in the
+air: which thing is absurd; because the force of a magnet is {92} always
+the stronger the nearer it is. So that when a piece of iron is raised a
+very little from the earth by the force of the magnet, it needs must be
+drawn steadily on towards the magnet (if nothing else come in the way) and
+cleave to it. Baptista Porta suspends a piece of iron in the air[178] (a
+magnet being fixed above), and, by no very subtile process, the iron is
+detained by a slender thread from its lower part, so that it cannot rise up
+to the stone. The iron is raised upright by the magnet, although the magnet
+does not * touch the iron, but because it is in its vicinity; but when the
+whole iron on account of its greater nearness is moved by that which
+erected it, immediately it hurries with a swift motion to the magnet and
+cleaves to it. For by approaching the iron is more and more excited, and
+the coition grows stronger.
+
+       *       *       *       *       *
+
+
+CHAP. XXV.
+
+Exaltation of the power of the Magnet.
+
+One loadstone far surpasses another in power, since one draws iron of
+almost its own weight, another can hardly stir some shreds. Whatever
+things, whether animals or plants, are endowed with life need some sort of
+nourishment, by which their strength not only persists but grows firmer and
+more vigorous. But iron is not, as it seemed to Cardan and to Alexander
+Aphrodiseus, attracted by the loadstone in order that it may feed on shreds
+of it, nor does the loadstone take up vigour from iron filings as if by a
+repast on victuals. Since Porta had doubts on this and resolved to test it,
+he took a loadstone of ascertained weight, and buried it in iron filings of
+not unknown weight; and when he had left it there for many months, he found
+the stone of greater weight, the filings of less. But the difference was so
+slender that he was even then doubtful as to the truth. What was done by
+him does not convict the stone of voracity, nor does it show any nutrition;
+for minute portions of the filings are easily scattered in handling. So
+also a very fine dust is insensibly born on a loadstone in some very slight
+quantity, by which something might have been added to the weight of the
+loadstone but which is only a surface accretion and might even be wiped off
+with no great difficulty. Some think that a weak and sluggish stone can
+bring itself back into better condition, and that a very powerful one also
+might present it with the highest powers. Do they acquire strength like
+animals when {93} they eat and are sated? Is the medicine prepared by
+addition or subtraction? Is there anything which can re-create this primary
+form or bestow it anew? And, certes, nothing can do this which is not
+magnetical. Magneticks can restore a certain soundness to magneticks (when
+not incurable); some can even exalt them beyond their proper strength; but
+when a body is at the height of perfection in its own nature, it is not
+capable of being strengthened further. So that that imposture of
+Paracelsus, who affirms that the force and virtue can be increased and
+transmuted tenfold, turns out to be the more infamous. The method of
+effecting this is as follows, viz., you make it semi-incandescent in a fire
+of charcoal (that is, you heat it very hot), so that it does not become
+red-hot, however, and immediately slake it, as much indeed as it can
+imbibe, in oil of saffron of Mars, made from the best Carynthian steel. "In
+this way you will be able so to strengthen a loadstone that it can draw a
+nail out of a wall and accomplish many other like wonderful things, which
+are not possible for a common loadstone." But a loadstone thus slaked in
+oil not only does not gain power, but suffers also a certain loss of its
+inborn strength. A loadstone is improved if polished and rubbed with steel.
+Buried in filings of the best iron or of pure steel, not rusty, it
+preserves its strength. Sometimes also a somewhat good and strong one gains
+[Illustration] some strength when it is rubbed on the pole of another, on
+the opposite part, and receives virtue. In all these experiments it is an
+advantage to observe the pole of the earth, and to adjust according to
+magnetick laws the stone which we wish to strengthen; which we shall set
+forth below. A somewhat powerful and fairly large loadstone increases the
+strength of a loadstone as it does of iron. A loadstone being placed over
+the boreal pole of a loadstone, * {94} the boreal pole becomes stronger,
+and an iron rod (like an arrow) sticks to the boreal pole A, but not at all
+to the pole B. The pole A also, when it is at the top in a right line with
+the axis of both loadstones joined in accordance with magnetick laws,
+raises the rod to the perpendicular, which it cannot do if the large
+loadstone be removed, on account of its own weaker strength. But as a small
+iron globe, when placed above the pole of a terrella, raises the rod to the
+* perpendicular, so, when placed at the side, the rod is not directed
+towards the centre of the globe, but is raised obliquely and cleaves
+anywhere, because the pole in a round piece of iron is always the point
+which is joined most closely to the pole of the terrella and is not
+constant as in a smaller terrella. The parts of the earth, as of all
+magneticks, are in agreement and take delight in their mutual proximity; if
+placed in the highest power, they do not harm their inferiors, nor slight
+them; there is a mutual love among them all, a perennial good feeling. The
+weaker loadstones are re-created by the more powerful, and the less
+powerful cause no harm to the stronger. But a powerful one attracts and
+turns a somewhat strong one more than it does an impotent one. Because a
+strenuous one confers a stronger activity, and itself hastens, flies up to
+the other, and solicits it more keenly; therefore there is a more certain
+and a stronger co-action and cohaerency.
+
+       *       *       *       *       *
+
+
+CHAP. XXVI.
+
+Why there should appear to be a greater love between
+_iron and loadstone, than between loadstone and loadstone, or_
+between iron and iron, when close to the loadstone,
+_within its orbe of virtue._
+
+Magnet attracts magnet, not in every part and on every side with equal
+conditions, as iron, but at one and a fixed point; therefore the poles of
+both must be exactly disposed, otherwise they do not cleave together duly
+and strongly. But this disposition is not easy and expeditious; wherefore a
+loadstone seems not to conform to a loadstone, when nevertheless they agree
+very well together. A piece of iron by the sudden impression of a loadstone
+is not only allured by the stone, but is renewed, its forces being drawn
+forth; by which it follows and solicits the loadstone with no less impulse,
+and even leads another piece of iron captive. Let there be a small iron
+spike above a loadstone clinging firmly to it; if you apply an unmagnetized
+rod of iron to the spike, not, however, {95} so that it touches the stone,
+you will see the spike when it has touched the iron, leaving the loadstone,
+follow the rod, try to grasp it by leaning toward it, and (if it should
+touch it) cleave firmly to it: for a piece of iron, when united and joined
+to another piece of iron placed within the orbe of virtue of the loadstone,
+draws it more strongly than does the loadstone itself. The natural
+magnetick virtue, confused and dormant in the iron, is aroused by the
+loadstone, is linked to the loadstone, and rejoices with it in its primary
+form; then smelted iron becomes a perfect magnetick, as robust as the
+loadstone itself. For as the one imparts and stirs, so the other conceives,
+and being stirred remains in virtue, and pours back the forces also by its
+own activity. But since iron is more like iron than loadstone, and the
+virtue in both pieces of iron is exalted by the proximity of the loadstone,
+so in the loadstone itself, in case of equal strength, likeness of
+substance prevails, and iron gives itself up rather to iron, and they are
+united by their very similar homogenic powers. Which thing happens not so
+much from a coition, as from a firmer unition; and a knob or snout of
+steel, fixed skilfully on the pole of the stone, raises greater weights of
+iron than the stone of itself could. When steel or iron is smelted from
+loadstone or iron ore, the slag and corrupt substances are separated from
+the better by the fusion of the material; whence (in very large measure)
+that iron contains the nature of the earth, purified from alien flaw and
+blemish, and more homogenic and perfect, though deformed by the fusion. And
+when that material indeed is provoked by a loadstone, it conceives the
+magnetick virtues, and within their orbe is raised in strength more than
+the weaker loadstone, which with us is often not free from some admixture
+of impurities.
+
+       *       *       *       *       *
+
+
+CHAP. XXVII.
+
+*
+
+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_.
+
+Rays of magnetick virtue spread out in every direction in an orbe; the
+centre of this orbe is not at the pole (as Baptista Porta reckons, Chap.
+22), but in the centre of the stone and of the terrella. So also the centre
+of the earth is the centre of the magnetick motions of the earth; though
+magneticks are not borne directly toward the centre by magnetical motion,
+except when they are attracted by the true pole. For since the formal {96}
+power of the stone and of the earth does not promote anything but the unity
+and conformity of disjoined bodies, it comes about that everywhere at an
+equal distance from the centre or from the circumference, just as it seems
+to attract perpendicularly at one place, so at another it is able even to
+dispose and to turn, provided the stone is not uneven in virtue. For if at
+the distance C from the pole D the stone is able to allure a versorium, *
+at an equally long interval above the aequator at A that stone can also
+direct and turn the versorium. So the very centre and middle of the
+terrella is the centre of its virtue, and from this to the circumference of
+the orbe (at equal intervals on every side) its magnetick virtues are
+emitted.
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+CHAP. XXVIII.
+
+A Loadstone attracts magneticks not only to a
+fixed point or pole, but to every part of a
+_terrella save the aequinoctial zone_.
+
+Coitions are always more powerful when poles are near poles, since in them
+by the concordancy of the whole there exists a stronger force; wherefore
+the one embraces the other more strongly. Places declining from the poles
+have attractive forces, but a little weaker and languid in the ratio of
+their distance; so that at length on the aequinoctial circle they are
+utterly enervated and evanescent. Neither do even the poles attract as
+mathematical points; nor do magneticks come into conjunction by their own
+poles, only on the poles of a loadstone. But coition {97} is made on every
+part of the periphery, both Northern and Southern, by virtue emanating from
+the whole body; magneticks nevertheless incline languidly towards
+magneticks in the parts bordering on the aequator, but quickly in places
+nearer the pole. Wherefore not the poles, not the parts alone nearest to
+the pole allure and invite magneticks, but magneticks are disposed and
+turned round and combine with magneticks in proportion as the parts facing
+and adjoined unite their forces together, which are always of the same
+potency in the same parallel, unless they are distributed otherwise from
+causes of variation.
+
+       *       *       *       *       *
+
+
+CHAP. XXIX.
+
+On Variety of Strength due to Quantity
+_or Mass_.
+
+Quite similar in potency are those stones which are of the same mine, and
+not corrupted by adjacent ores or veins. Nevertheless that which excels in
+size shows greater powers, since it seizes greater weights and has a wider
+orbe of virtue. For a loadstone weighing one ounce does not lift a large
+nail as does one weighing a pound, nor does it rule so widely, nor extend
+its forces; and if from a loadstone of a pound weight a portion is taken
+away, something of its power will be seen to go also; for when a portion is
+abstracted the virtue is lessened. But if that part is properly applied and
+united to it, though it is not fastened * to nor grown into it, yet by the
+application it obtains its pristine power and its vigour returns.
+Sometimes, however, when a part is taken away, the virtue turns out to be
+stronger on account of the * bad shape of the stone, namely, when the
+vigour is scattered through inconvenient angles. In various species the
+ratio is various, for one stone of a drachm weight draws more than another
+of twenty pounds. Since in very many the influence is so effete that it can
+hardly be perceived, those weak stones are surpassed by prepared pieces of
+clay. But, it may be asked[179], if a stone of the same species and
+goodness weighing a drachm would seize upon a drachm of iron, would a stone
+of an ounce weight seize on an ounce, a pound on a pound, and so on? And
+this is indeed true; for it both strains and remits its strength
+proportionately, so that if a loadstone, one drachm of which would attract
+one drachm of iron, were in equal proportion applied either to a suitably
+large obelisk or to an immense pyramid of iron, it would lift it directly
+in such {98} proportion and would draw it towards itself with no greater
+effort of its nature or trouble than a loadstone of a drachm weight
+embraces a drachm. But in all such experiments as this let the vigour of
+the magnets be equal; let there be also a just proportion in all of the
+shapes of the stones, and let the shape of the iron to be attracted be the
+same, and the goodness of the metal, and let the position of the poles of
+the loadstones be most exact. This is also no less true in the case of an
+armed loadstone than of an unarmed one. For the sake of experiment, let
+there be given a loadstone of eight ounces weight, which when armed lifts
+twelve ounces of iron; if you cut off from that loadstone a certain
+portion, which when it has been * reduced to the shape of the former whole
+one is then only of two ounces, such a loadstone armed lifts a piece of
+iron applied to it of three ounces, in proportion to the mass. In this
+experiment also the piece of iron of three ounces ought to have the same
+shape as the former one of twelve ounces; if that rose up into a cone, it
+is necessary that this also in the ratio of its mass should be given a
+pyramidal shape proportioned to the former.
+
+       *       *       *       *       *
+
+
+CHAP. XXX.
+
+The Shape and Mass of the Iron are of most
+_importance in coition_.
+
+Observation has shown above that the shape and mass of the loadstone have
+great influence in magnetick coitions; likewise also the shape and mass of
+the iron bodies give back more powerful and steady forces. Oblong iron rods
+are both drawn more quickly to a loadstone and cleave to it with greater
+obstinacy than round or square pieces, for the same reasons which we have
+proven in the case of the loadstone. But, moreover, this is also worthy of
+observation, that a smaller piece of iron, to which is hung a weight of
+another material, so that it is altogether in weight equal to another large
+whole piece of iron of a right weight * (as regards the strength of the
+loadstone), is not lifted by the loadstone as the larger piece of iron
+would be. For a smaller piece of iron does not join with a loadstone so
+firmly, because it sends back less strength, and only that which is
+magnetick conceives strength; the foreign material hung on cannot acquire
+magnetick forces.
+
+       *       *       *       *       *
+
+
+{99} CHAP. XXXI.
+
+On Long and Round Stones.
+
+Pieces of iron join more firmly with a long stone than with a round one,
+provided that the pole of the stone is at the extremity and end of its
+length; because, forsooth, in the case of a long stone, a magnetick is
+directed at the end straight towards the body in which the virtue proceeds
+in straighter lines and through the longer diameter. But a somewhat long
+stone has but little power on the side, much less indeed than a round one.
+It is demonstrable[180], indeed, that at A and B the coition is * stronger
+in a round stone than at C and D, at like distances from the pole.
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+CHAP. XXXII.
+
+Certain Problems and Magnetick Experiments about
+the Coition, and Separation, and regular Motion
+_of bodies magnetical_.
+
+Equal loadstones come together with equal incitation. *
+
+Also magnetick bodies of iron, if alike in all respects, * come together
+when excited with similar incitation.
+
+Furthermore, bodies of iron not excited by a * loadstone, if they are alike
+and not weighed down by their bulk, move towards one another with equal
+motion.
+
+Two loadstones, disposed on the surface of some water in {100} suitable
+skiffs, if they are drawn up suitably within their orbes of virtue, incite
+one another mutually to an embrace. So a proportionate * piece of iron in
+one skiff hurries with the same speed towards the loadstone as the
+loadstone itself in its boat strives towards the iron. From their own
+positions, indeed, they are so borne together, that they are joined and
+come to rest at length in the middle of the space. Two iron wires
+magnetically excited, floating in water by means of * suitable pieces of
+cork, strive to touch and mutually strike one another with their
+corresponding ends, and are conjoined.
+
+Coition is firmer and swifter than repulsion and separation in * equal
+magnetick substances. That magnetick substances are more sluggishly
+repelled than they are attracted is manifest in all magnetical experiments
+in the case of stones floating on water in suitable skiffs; also in the
+case of iron wires or rods swimming (transfixed through corks) and well
+excited by a loadstone, and in the case of versoria. This comes about
+because, though there is one faculty of coition, another of conformation or
+disposition, repulsion and aversion is caused merely by something
+disposing; on the other hand, the coming together is by a mutual alluring
+to contact and a disposing, that is, by a double vigour.
+
+A disponent vigour is often only the precursor of coition, in order that
+the bodies may stand conveniently for one another before conjunction;
+wherefore also they are turned round to the corresponding ends, if they can
+[not][181] reach them through the hindrances.
+
+[Illustration]
+
+If a loadstone be divided through a meridian into two equal parts, the
+separate parts mutually repel one another, the poles being * placed
+directly opposite one another at a convenient and equal distance. They
+repel one another also with a greater velocity than when pole is put
+opposite pole incongruously. Just as the part B of the loadstone, placed
+almost opposite the part A, repels it floating in its skiff, because D
+turns away from F, and E from C; but if B is exactly joined with A again,
+they agree and become one body {101} magnetical; but in proximity they
+raise enmities. But if one part of the stone is turned round, so that C
+faces D and F faces E, then A pursues B within its orbe until they are
+united.
+
+The Southern parts of the stone avoid the Southern parts, and the Northern
+parts the Northern. Nevertheless, if by force you move up the Southern cusp
+of a piece of iron too near the Southern part of the stone, the cusp is
+seized and both are linked together in friendly embraces: because it
+immediately reverses the implanted verticity of the iron, and it is changed
+by the presence of the more powerful stone, which is more constant in its
+forces than the iron. For they come together according to their nature, if
+by reversal and mutation true conformity is produced, and just coition, as
+also regular direction. Loadstones of the same shape, size, and vigour,
+attract one another mutually with like efficacy, and in the opposite
+position repel one another mutually with a like vigour.
+
+Iron rods not touched, though alike and equal, do yet often act * upon one
+another with different forces; because as the reasons of their acquired
+verticity, also of their stability and vigour, are different, so the more
+strongly they are excited, the more vigorously do they incite.
+
+Pieces of iron excited by one and the same pole mutually repel * one
+another by those ends at which they were excited; then also the opposite
+ends to those in these iron pieces raise enmities one to another.
+
+In versoria whose cusps have been rubbed, but not their cross-ends, * the
+crosses mutually repel one another, but weakly and in proportion to their
+length.
+
+In like versoria the cusps, having been touched by the same * pole of the
+loadstone, attract the cross-ends with equal strength.
+
+In a somewhat long versorium the cross-end is attracted rather * weakly by
+the cusp of a shorter iron versorium; the cross of the shorter more
+strongly by the cusp of the longer, because the cross of the longer
+versorium has a weak verticity, but the cusp has a stronger.
+
+The cusp of a longer versorium drives away the cusp of a * shorter one more
+vehemently than the cusp of the shorter the cusp of the longer, if the one
+is free upon a pin, and the other is held in the hand; for though both were
+equally excited by the same loadstone, yet the longer one is stronger at
+its cusp on account of its greater mass.
+
+The Southern end of an iron rod which is not excited attracts * the
+Northern, and the Northern the Southern; moreover, also the Southern parts
+repel the Southern, and the Northern the Northern.
+
+If magnetick substances are divided or in any way broken in pieces, each
+part has a Northern and a Southern end.
+
+{102} A versorium is moved as far off by a loadstone when an obstacle * is
+put in the way, as through air and an open medium.
+
+Rods rubbed upon the pole of a stone strive after the same pole * and
+follow it. Therefore Baptista Porta errs when he says, chapter 40[182], "If
+you put that part to it from which it received its force, it will not
+endure it, but drives it from it, and draws to it the contrary and opposite
+part."
+
+The principles of turning round and inclining are the same in the case of
+loadstone to loadstone, of loadstone to iron, of iron also to iron.
+
+When magnetick substances which have been separated by force and dissected
+into parts flow together into a true union and are suitably connected, the
+body becomes one, and one united virtue, nor have they diverse ends.
+
+The separate parts assume two opposite poles, if the division has * not
+been made along a parallel: if the division has been made along a parallel,
+they are able to retain one pole in the same site as before.
+
+Pieces of iron which have been rubbed and excited by a loadstone are more
+surely and swiftly seized by a loadstone at fitting ends than such as have
+not been rubbed.
+
+If a spike is set up on the pole of a loadstone, a spike or style * of iron
+placed on the upper end is strongly cemented to it, and draws away the
+erect spike from the terrella when motion is made.
+
+If to the lower end of the erect spike the end of another spike * is
+applied, it does not cohaere with it, nor do they unite together.
+
+As a rod of iron draws away a piece of iron from a terrella, so is it also
+with a minute loadstone and a lesser terrella, though weaker in strength.
+
+[Illustration]
+
+The piece of iron C comes into conjunction with the terrella A, and the
+vigour in it is magnetically exalted and excited, both in the adjoining end
+and in the other also which is turned away through {103} its conjunction
+with the terrella. The end that is turned away also conceives vigour from
+the loadstone B; likewise the pole D of that loadstone is powerful on
+account of its suitable aspect and the nearness of the pole E of the
+terrella. Several causes therefore concur why the piece of iron C should
+cleave to the terrella B, to which it is joined more firmly than to the
+terrella A; the vigour excited in the rod, the vigour also excited in the
+stone B, and the strength implanted in B concur; therefore D is more firmly
+cemented magnetically with C than E with C.
+
+But if you were to turn the vertex F round to the iron C, C would not
+adhaere to F as formerly to D; for stones so arranged being within the orbe
+of virtue are placed contrary to natural order; wherefore F does not
+receive power from E.
+
+Two loadstones or excited pieces of iron, duly cohaering, fly * asunder on
+the approach of another more powerful loadstone or magnetized piece of
+iron. Because the new-comer repels the other with its opposing face, and
+dominates it, and ends the relationship of the two which were formerly
+joined. So the forces of the other are lessened and succumb; but if it
+conveniently could, being diverted of its association with the weaker, and
+rolling round, it would turn about to the stronger. Wherefore also
+magnetick bodies suspended in the air fall when a loadstone is brought near
+them with an opposing face, not (as Baptista Porta teaches) because the
+faculty of both those which were joined before grows faint and torpid, for
+no face can be hostile to both the ends which cohaere, but to one only; and
+when the stronger loadstone, coming fresh with opposing face, impels this
+further from it, it is put to flight by the friendly reception of the
+former.
+
+       *       *       *       *       *
+
+
+CHAP. XXXIII.
+
+On the Varying Ratio of Strength, and of the Motion
+_of coition, within the orbe of virtue_.
+
+Should a very large weight, which at a very small distance is drawn towards
+a loadstone, be divided into ever so many equal parts, and should the
+radius of the orbe of magnetick attraction be divided into the same number
+of parts, the like named parts of the weight will correspond to the
+intermediate parts of the radius.
+
+The orbe of virtue extends more widely than the orbe of motion of any
+magnetick; for the magnetick is affected at its extremity, even if it is
+not moved with local motion, which effect is produced {104} by the
+loadstone being brought nearer. A small versorium also is turned when a
+good distance off, even if at the same distance it would not flow towards
+the loadstone, though free and disengaged from impediment.
+
+The swiftness of the motion of a magnetick body to a loadstone is dependent
+on either the power of the loadstone, on its mass, on its shape, on the
+medium, or on its distance within the magnetick orbe.
+
+A magnetick moves more quickly towards a more powerful * stone than towards
+a sluggish one in proportion to the strength, and [as appears] by a
+comparison of the loadstones together. A lesser mass of iron also is
+carried more quickly towards a loadstone, just as also one that is a little
+longer in shape. The swiftness of magnetick motion towards a loadstone is
+changed by reason of the medium; for bodies are moved more quickly in air
+than in water, and in clear air than in air that is thick and cloudy.
+
+By reason of the distance, the motion is quicker in the case of bodies near
+together than when they are far off. At the limits of the orbe of virtue of
+a terrella a magnetick is moved feebly and slowly. At very short distances
+close to the terrella the moving impetus is greatest.
+
+A loadstone which in the outmost part of its orbe of virtue * hardly moves
+a versorium when one foot removed from it, doth, if a long piece of iron is
+joined to it, attract and repel the versorium more strongly with its
+opposite poles when even three feet distant. The result is the same whether
+the loadstone is armed or unarmed. Let the iron be a suitable piece of the
+thickness of the little finger.
+
+For the vigour of the loadstone excites verticity in the iron and proceeds
+in the iron and through the iron much further than it extends through the
+air.
+
+The vigour proceeds even through several pieces of iron (joined * to one
+another end to end), not so regularly, however, as through one continuous
+solid.
+
+Dust of steel placed upon paper rises up when a loadstone is moved near
+above it in a sort of steely hairiness; but if the loadstone is placed
+below, such a hairiness is likewise raised.
+
+Steel dust (when the pole of a loadstone is placed near) is cemented * into
+one body; but when it desires coition with the loadstone, the mass is split
+and it rises in conglomerated parts.
+
+But if there is a loadstone beneath the paper, the mass is split in the
+same way and many portions result, each of which consists of very many
+parts, and remains cemented together, as individual bodies. Whilst the
+lower parts of these pursue greedily the pole of the loadstone placed
+directly beneath, even they also are raised up as magnetick wholes, just as
+a small iron wire of the length of a grain or two grains of barley is
+raised up, both when the loadstone is moved near both beneath and above.
+
+       *       *       *       *       *
+
+
+{105} CHAP. XXXIIII.
+
+Why a Loadstone should be stronger in its poles
+in a different ratio; as well in the Northern
+_regions as in the Southern_.
+
+The extraordinary magnetick virtue of the earth is * remarkably
+demonstrated by the subtility of the following magnetical experiment. Let
+there be given a terrella of no contemptible power, or a long loadstone
+with equal cones as polar extremities; but in any other shape which is not
+exactly round error is easy, and the experiment difficult. In the Northern
+regions, raise the true North pole of the terrella above the horizon
+straight toward the zenith; it is demonstrable that it raises up a larger
+iron spike on its North pole, than the South pole of the same terrella is
+able to raise, when turned in the same way toward the highest point of the
+sky. The same thing is shown by a small terrella placed in the same way
+above a larger.
+
+[Illustration]
+
+Let _a b_ be the earth or a somewhat large terrella, also _a b_ a smaller
+terrella. There is set up above the Northern pole of the smaller terrella a
+spike larger than the pole _b_ of the smaller terrella can raise, if it is
+turned round to the higher parts. And the pole _a_ of the {106} smaller
+terrella has its strength from the larger, declining from the Zenith to the
+plane of the horizon or to the level. But now, if, * leaving the terrella
+disposed in the same way, you bring a piece of iron to the lower and
+Southern pole, it will attract and retain a greater weight than the Boreal
+pole could, if it were turned round to the lower parts. Which thing is
+demonstrated thus: let A be the earth or a terrella; E the Boreal pole or
+some place in some great latitude; B a rather large terrella above the
+earth or a smaller terrella on the top of a larger; D its Southern pole. It
+is manifest that D (the Southern pole) attracts a larger piece of iron, C,
+than F (the Boreal pole) will be able to, if it is turned round downward to
+the position D, toward the earth or the terrella in the Northern regions.
+
+[Illustration]
+
+Magneticks acquire strength through magneticks, if they are properly placed
+according to their nature, in near neighbourhood and within the orbe of
+virtue. Wherefore when a terrella is placed on the earth or on a terrella,
+so that its Southern pole is turned round toward the Northern pole, its
+Northern pole, however, turned away from the Northern pole, the influence
+and strength of {107} its poles are increased. And so the Northern pole of
+a terrella in such a position lifts up a larger spike than the Southern
+pole, if the Southern pole is turned away. Similarly the Southern pole in a
+proper and natural arrangement, acquiring strength from the earth or from a
+larger terrella, attracts and retains larger rods of iron. In * the other
+part of the terrestrial globe toward the South, as also in the Austral
+portion of a terrella, the reasoning is converse; for the Southern pole of
+the terrella being turned away is more robust, as also the Northern pole
+when turned round. The more a region on the earth is distant from the
+aequinoctial (as also in a larger terrella), the larger is the accession of
+strength perceived; near the aequator, indeed, the difference is small, but
+on the aequator itself null; at the poles finally it is greatest.
+
+       *       *       *       *       *
+
+
+CHAP. XXXV.
+
+On a Perpetual Motion Machine, mentioned
+by authors, by means of the attraction
+_of a loadstone_.
+
+Cardan writes[183] that out of iron and the Herculean stone can be made a
+perpetual motion machine; not that he himself had ever seen one, but only
+conceived the idea from an account by Antonius de Fantis[184], of Treves.
+Such a machine he describes, Book 9, _De Rerum Varietate_. But they have
+been little practised in magnetick experiments who forge such things as
+that. For no magnetick attraction can be greater (by any skill or by any
+kind of instrument) than the retention. Things which are joined and those
+which are approaching near are retained with a greater force than those
+which are enticed and set in motion, and are moved; and that coition is, as
+we have shown above, a motion of both, not an attraction of one. Such a
+machine Peter Peregrinus feigned many centuries before or else depicted one
+which he had received from others, and one which was much better fitted for
+the purpose. Johannes Taysnier published it also, spoiled by wretched
+figures, and copied out the whole theory of it word for word. O that the
+gods would at length bring to a miserable end such fictitious, crazy,
+deformed labours, with which the minds of the studious are blinded!
+
+       *       *       *       *       *
+
+
+{108} CHAP. XXXVI.
+
+How a more robust Loadstone may be
+_recognized_.
+
+Very powerful loadstones sometimes lift into the air a weight of iron equal
+to their own; a weak one barely attracts a slender wire. Those therefore
+are more robust which appeal to and retain larger bodies, if there is no
+defect in their form, or the pole of the stone is not suitably moved up.
+Moreover, when placed in a boat a keener influence turns its own poles
+round more quickly to the poles of the earth or the limits of variation on
+the horizon. One which performs its function more feebly indicates a defect
+and an effete nature. There must always be a similar preparation, a similar
+figure, and a like size; for in such as are very dissimilar and unlike, the
+experiment is doubtful. The method of testing the strength is the same also
+with a versorium in a place somewhat remote from a loadstone; for the one
+which is able to turn the versorium round at the greater distance, that one
+conquers and is held the more potent. Rightly also is the force of a
+loadstone weighed in a balance by B. Porta; a piece of loadstone is placed
+in one scale-pan, in the other just as much weight of something else, so
+that the scale-pans hang level. Soon a piece of iron lying on the table is
+adjusted so that it sticks to the loadstone placed in the scale, and they
+cling together most perfectly, according to their friendly points; into the
+other scale-pan sand is gradually thrown, and that until the scale in which
+the loadstone is placed is separated from the iron. Thus by weighing the
+weight of sand, the magnetick force becomes known. Similarly also it will
+be pleasing to try with another stone, in equilibrium, the weight of the
+sand being observed, and to find out the stronger by means of the weights
+of sand. Such is the experiment of Cardinal Cusan in his _De
+Staticis_[185], from whom it would seem that B. Porta learnt the
+experiment. The better loadstones turn themselves round more quickly toward
+the poles or points of variation; then they also lead along and turn round
+more quickly, according to the greater quantity and mass of wood, a boat
+and other stuff. In a declination instrument, the more powerful force of a
+loadstone is looked for and required. Those therefore are more lively when
+they get through their work readily, and pass through and come back again
+with speed, and swiftly at length settle at their own point. Languid and
+effete ones move more sluggishly[186], settle more tardily, adhaere more
+uncertainly, and are easily disturbed from their possession.
+
+       *       *       *       *       *
+
+
+{109} CHAP. XXXVII.
+
+Use of a Loadstone as it affects
+_iron._
+
+By magnetick coition we test iron ore in a blacksmith's forge. It is burnt,
+broken in pieces, washed and dried, in which way it lays down its alien
+humours; in the bits collected from the washing is placed a loadstone,
+which attracts the iron dust to itself; this, being brushed off with
+feathers, is received in a crucible, and the loadstone is again placed in
+the bits collected from the washing, and the dust wiped off, as long as any
+remains which it will attract to itself. This is then heated in the
+crucible along with _sal nitri_[187] until it is liquid, and from this a
+small mass of iron is cast. But if the loadstone draws the dust to itself
+quickly and readily, we conjecture that the iron ore is rich; if slowly,
+poor; if it seems altogether to reject it, there is very little iron in it
+or none at all. In like manner iron dust can be separated from another
+metal. Many tricks there are also, when iron is secretly applied to lighter
+bodies, and, being attracted by the motion of a loadstone which is kept out
+of sight, causes movements which are amazing to those who do not know the
+cause. Very many such indeed every ingenious mechanician will perform by
+sleight of hand, as if by incantations and jugglery[188].
+
+       *       *       *       *       *
+
+
+CHAP. XXXVIII.
+
+On Cases of Attraction in other Bodies.
+
+Very often the herd of philosophizers and plagiarists repeat from the
+records of others in natural philosophy opinions and errors about the
+attractions of various bodies; as that Diamond attracts iron, and snatches
+it away from a magnet; that there are various kinds or magnets, some which
+attract gold, others silver, brass, lead; even some which attract flesh,
+water, fishes. The flame of sulphur is said to seek iron and stones; so
+white naphtha is said to attract fire. I have said above that {110}
+inanimate natural bodies do not attract, and are not attracted by, others
+on the earth, excepting magnetically or electrically. Wherefore it is not
+true that there are magnets which attract gold or other metals; because a
+magnetick substance draws nothing but magnetick substances. Though
+Fracastorio says that he has shown a magnet drawing silver; if this were
+true, it must have happened on account of iron skilfully mixed with that
+silver or concealed in it, or else because nature (as she does sometimes,
+but rarely) had mixed iron with the silver; iron indeed is rarely mixed
+with silver by nature; silver with iron very rarely or never. Iron is mixed
+with silver by forgers of false coin or from the avarice of princes in the
+coining of money, as was the case with the denarius of Antony[189],
+provided that Pliny is recording a true incident. So Cardan (perhaps
+deceived by others) says that there is a certain kind of loadstone which
+draws silver; he adds a most foolish test of this: "If therefore" (he says)
+"a slender rod of silver be steeped in that in which a versatory needle has
+stood, it will turn toward silver (especially toward a large quantity)
+although it be buried; by this means anyone will be able easily to dig up
+concealed treasures." He adds that "it should be very good stone, such as
+he has not yet seen." Nor indeed will either he or anyone else ever see
+such a stone or such an experiment. Cardan brings forward an attraction of
+flesh, wrongly so named and very dissimilar from that of the loadstone; for
+his _magnes creagus_ or flesh-magnet, from the experiment that it sticks to
+the lips, must be hooted out from the assembly of loadstones, or by all
+means from the family of things attractive. Lemnian earth, ruddle, and very
+many minerals do this, and yet they are fatuously said to attract. He will
+have it that there is another loadstone, as it were, a third species, into
+which, if a needle is driven and afterwards stuck into the body, it is not
+felt. But what has attraction to do with stupefaction, or stupor with a
+Philosopher's intellect, when he is discoursing about attraction? There are
+many stones, both found in nature and made by art, which have the power of
+stupefying. Sulphur flame is said by some to attract, because it consumes
+certain metals by its power of penetration. So white naphtha attracts
+flame, because it gives off and exhales an inflammable vapour, on which
+account it is kindled at some distance, just as the smoke of a recently
+extinguished candle takes fire again from another flame; for fire creeps to
+fire through an inflammable medium. Why the sucking fish Echineis or the
+Remora should stay ships has been variously treated by Philosophers, who
+are often accustomed to fit this fable (as many others) to their theories,
+before they find out whether the thing is so in nature. Therefore, in order
+that they may support and agree with the fatuities of the ancients, they
+put forward even the most fatuous ratiocinations and ridiculous problems,
+cliffs that attract, where the {111} sucking fish tarry, and the necessity
+of some vacuum, I know not what, or how produced. Pliny and Julius Solinus
+make mention of a stone Chatochitis[190]. They say that it attracts flesh,
+and keeps hold of the hands, just as a loadstone does iron, and amber
+chaff. But that happens only from a stickiness and from glue contained in
+it, since it sticks more easily to the hands when they are warm. Sagda or
+Sagdo[191], of the colour of a sard, is a precious stone mentioned by
+Pliny, Solinus, Albertus, and Evax[192]; they describe its nature and
+relate, on the authority of others, that it specially attracts wood to
+itself. Some even babble that woods cannot be wrenched away except they are
+cut off. Some also narrate that a stone is found which grows pertinaciously
+into ships, in the same way as certain testacea on long voyages. But a
+stone does not draw because it sticks; and if it drew, it would certainly
+draw shreds electrically, Encelius saw in the hands of a sailor such a
+stone of feeble virtue, which would hardly attract even the smallest twigs;
+and in truth, not of the colour of the sard. So Diamond, Carbuncle,
+Crystal, and others do attract. I pass over other fabulous stones;
+Pantarbe, about which Philostratus writes that it draws other stones to
+itself; Amphitane also, which attracts gold. Pliny in his origin of glass
+will have it that a loadstone is an attractor of glass, as well as of iron.
+For in his method of preparing glass, when he has indicated its nature, he
+subjoins this about loadstone. "Soon (such is the astute and resourceful
+craft) it was not content to have mixed natron; loadstone also began to be
+added, since it was thought to attract to itself the liquor of glass (as it
+does iron)." Georgius Agricola writes that to the material of glass (sand
+and natron) one part also of loadstone is added. "Because that force is
+believed, in our times just as in former times, to attract the liquor of
+glass to itself, as it attracts iron to itself, purges it when drawn, and
+makes clear glass from green or muddy; but the fire afterwards burns up the
+loadstone." It is true indeed that some sort of _magnes_ (as the magnesia
+of the glass-makers imbued with no magnetick virtues) is sometimes put in
+and mixed with the material of the glass; not, however, because it attracts
+glass. But when a loadstone is burnt, it does not lay hold of iron at all,
+nor is iron when red-hot allured by any loadstone; and loadstone also is
+burnt up by more powerful fires and loses its attractive potency. Nor is
+this a function of loadstone alone in the glass furnaces; but also of
+certain pyrites and of some easily combustible iron ores, which are the
+only ones used by our glass-makers, who make clear, bright glass. They are
+mixed with the sand, ashes, and natron (just as they are accustomed to make
+additions in the case of metallick ores whilst they are smelted), so that
+when the material slows down into glass, the green and muddy colour of the
+glass may be purged by the penetrating heat. For no other material becomes
+so hot, {112} or bears the fire for such a convenient time, until the
+material of the glass is perfectly fluid, and is at the same time burnt up
+by that ardent fire. It happens, however, sometimes, that on account of the
+magnetick stone, the magnesia, or the ore, or the pyrites, the glass has a
+dusky colour, when they resist the fire too much and are not burnt up, or
+are put in in too great quantity. Wherefore manufacturers are seeking for a
+stone suitable for them, and are observing also more diligently the
+proportion of the mixture. Badly therefore did the unskilful philosophy of
+Pliny impose upon Georgius Agricola and the more recent writers, so that
+they thought the loadstone was wanted by glass-makers on account of its
+magnetick strength and attraction. But Scaliger in _De Subtilitate ad
+Cardanum_, in making diamond attract iron, when he is discussing
+magneticks, wanders far from the truth, unless it be that diamond attracts
+iron electrically, as it attracts wood, straws, and all other minute bodies
+when it is rubbed. Fallopius reckons that quicksilver draws metals by
+reason of an occult property, just as a loadstone iron, amber chaff. But
+when quicksilver enters metals, it is wrongly called attraction. For metals
+imbibe quicksilver, just as clay water; nor do they do this unless they are
+touching, for quicksilver does not allure gold or lead to itself from afar,
+but they remain motionless in their places.
+
+       *       *       *       *       *
+
+
+CHAP. XXXIX.
+
+On Bodies which mutually repel one another.
+
+Writers who have discoursed on the forces of bodies which attract others
+have also spoken about the powers of bodies which repel, but especially
+those who have instituted classes for natural objects on the basis of
+sympathy and antipathy. Wherefore it would seem necessary for us to speak
+also about the mutual strife of bodies, so that published errors should not
+creep further, and be received by all to the ruin of true philosophy. They
+say that, just as like things attract for the sake of preservation, so
+unlike and contrary things for the same purpose mutually repel and put one
+another to flight. This is evident in the reaction of many things, but it
+is most manifest in the case of plants and animals, which attract kindred
+and familiar things, and in like manner reject foreign and unsuitable
+things. But in other bodies there is not the same reason, so that when they
+are separated, they should come together by mutually {113} attracting one
+another. Animals take food (as everything which grows), and draw it into
+their interior; they absorb the nourishment by certain parts and
+instruments (through the action and operation of the _anima_). They enjoy
+by natural instinct only the things set in front of them and near them, not
+things placed afar off; and this without any alien force or motion.
+Wherefore animals neither attract any bodies nor drive them away. Water
+does not repel oil (as some think) because the oil floats on water; nor
+does water repel mud, because the mud, if mixed in water, settles down in
+time. This is a separation of unlike bodies or such as are not perfectly
+mixed as respects the material; the separated bodies nevertheless remain
+joined without any natural strife. Wherefore a muddy sediment settles
+quietly on the bottom of vessels, and oil remains on the top of the water
+and is not sent further away. A drop of water remains intact on a dry
+surface, and is not expelled from the dry substance. Wrongly therefore do
+those who discourse on these matters infer an antipathy (that is, the force
+of repelling by contrary passions); for there is no repelling force in
+them; and repulsion comes[193] from action, not from passion. But their
+greek vocables please them too much. We, however, must inquire whether
+there is any body which drives anything else further off without material
+impetus, as a loadstone attracts. But a loadstone seems even to repel
+loadstone. For the pole of one loadstone repels the pole of another, which
+does not agree with it according to nature; by repelling, it turns it round
+in an orbit so that they may exactly agree according to their nature. But
+if a somewhat weak loadstone, floating freely on water, cannot readily be
+turned round on account of impediments, the whole loadstone is repelled and
+sent further away from the other. All electricks attract all things: they
+never repel or propel anything at all[194]. As to what is related about
+certain plants (as about the cucumber, which turns aside when oil is
+applied to it), there is a material change from the vicinity, not a hidden
+antipathy. But when they show a candle flame put against a cold solid
+substance (as iron) turn away to the side, and allege antipathy as the
+cause, they say nothing. The reason of this they will see clearer than the
+day, when we discourse on what heat is[195]. But Fracastorio's opinion that
+a loadstone can be found, which would drive iron away, on account of some
+opposing principle lurking in the iron, is foolish.
+
+       *       *       *       *       *
+
+
+{115} [Illustration]
+
+BOOK THIRD.
+
+_CHAP. I._
+
+ON DIRECTION.
+
+On referring to the earlier books it will be found shown that a loadstone
+has its poles, and that a piece of iron has also poles, and rotation, and a
+certain verticity; finally, that the loadstone and the iron direct their
+poles toward the poles of the earth. Now, however, we must make clear the
+causes of these things and their admirable workings, pointed out indeed
+before, but not proven. All those who have written before us about these
+rotations have left us their opinions so briefly, so meagrely, and with
+such hesitating judgment that they seem hardly likely ever to persuade
+anyone, or even to be able to satisfy themselves; and all their petty
+reasons are rejected by the more prudent as useless, uncertain, and absurd,
+being supported by no proofs or arguments; whence also magnetick science,
+being all the more neglected and not understood, has been in exile. The
+true austral pole of a loadstone, not the boreal (as all before us used to
+think), * if the loadstone is placed in its boat on the surface of water,
+turns to the North; in the case of a piece of iron also, whether it has
+been excited by a loadstone or not, the southern end moves toward the
+North. An oblong piece of iron of three or four digits' length[196], when
+skilfully rubbed with a loadstone, quickly turns north and south. Wherefore
+mechanicians, taking a piece of iron prepared in this way, balance it on a
+pin in a box, and fit it up with the requisites of a sun-dial; or they
+prepare the versorium out of two curved pieces of iron with their ends
+touching one another, so that the motion may be more constant. In this way
+the mariners' versorium is arranged, which is an instrument beneficial,
+useful, and auspicious to sailors for indicating, like a good genius,
+safety and the right way. But it must be understood on the threshold of
+this argument (before we proceed further) that these pointings of the
+loadstone or of iron are not perpetually made {116} toward the true poles
+of the world, do not always seek those fixed and definite points, or remain
+on the line of the true meridian; but usually diverge some distance to the
+East or to the West. Sometimes also at certain places on land or sea they
+do indicate exactly the true poles. This discrepancy is called the
+_Variation_ of the iron or of the loadstone; and since this is brought
+about by other causes, and is merely a certain disturbance and perversion
+of the true direction, we are directing our attention in this place to the
+true direction of the compass and of the magnetick iron (which would be
+equally toward the true poles and on the true meridian everywhere on the
+earth, unless other obstacles and an untoward pervertency hindered it). Of
+its variation and the cause of the perversion we shall treat in the next
+book. Those who wrote about the world and about natural philosophy a
+century ago, especially those remarkable elementary philosophers, and all
+those who trace their knowledge and training to them down to our own times,
+those men, I say, who represented the earth as always at rest and, as it
+were, a useless weight, placed in the centre of the universe at an equal
+distance from the sky on every side, and its nature to be simple, imbued
+only with the qualities of dryness and cold, sought diligently for the
+causes of all things and of all effects in the heavens, the stars, the
+planets, in fire, air, waters and substances of mixed natures. Never indeed
+did they recognize that the terrestrial globe had, besides dryness and
+cold, some special, effective, and predominant properties, strengthening,
+directing, and moving the globe itself through its whole mass and its very
+deepest vitals; nor did they ever inquire whether there were any such. For
+this reason the crowd of philosophizers, in order to discover the reasons
+of the magnetical motions, called up causes lying remote and far away. And
+one man seems to me beyond all others worthy of censure, Martin Cortes,
+who, since there was no cause which could satisfy him in the whole of
+nature, dreamed that there was a point of magnetical attraction beyond the
+heavens, which attracted iron. Peter Peregrinus thinks that the direction
+arises from the poles of the sky. Cardan thought that the turning of iron
+was caused by a star in the tail of the Great Bear; Bessard, the Frenchman,
+opines that a magnetick turns toward the pole of the zodiack. Marsilius
+Ficinus will have it that the loadstone follows its own Arctick pole; but
+that iron follows the loadstone, straws amber; whilst this perhaps follows
+the Antarctick pole--a most foolish dream. Others have recourse to I know
+not what magnetick rocks and mountains. Thus it is always customary with
+mortals, that they despise things near home, whilst foreign and distant
+things are dear and prized. But we study the earth itself and observe in it
+the cause of so great an effect. The earth, as the common mother, has these
+causes inclosed in her innermost parts; in accordance with her rule, {117}
+position, condition, verticity, poles, aequator, horizons, meridians,
+centre, circumference, diameter, and the nature of the whole interior of
+her substance, must all magnetical motions be discussed. The earth has been
+ordered by the highest Artificer and by nature in such a way that it should
+have parts dissimilar in position, bounds of the whole and complete body,
+ennobled by certain functions, by which it might itself remain in a
+definite direction. For just as a loadstone, when it is floated on water in
+a suitable vessel, or is hung by slender threads in the air, by its
+implanted verticity conforms its poles to the poles of the common mother in
+accordance with magnetick laws; so if the earth were to deviate from its
+natural direction and its true position in the universe, or if its poles
+were to be drawn aside (if this were possible) toward the sun-rising or the
+sun-setting or toward any other points whatsoever in the visible firmament,
+they would return again to the north and south by magnetical motion, and
+would settle at the same points at which they are now fixed. The reason why
+the terrestrial globe seems to remain more steadily with the one pole
+toward those parts and directed toward the Cynosure, and why its pole
+diverges by 23 degrees 29 minutes, with a certain variation not
+sufficiently investigated as yet by Astronomers, from the poles of the
+ecliptick, depends on its virtue magnetical. The causes of the precession
+of the aequinoxes and the progression of the fixed stars, and of the
+change, moreover, in the declinations of the sun and of the tropicks, must
+be sought from magnetick influences; so that neither that absurd motion of
+trepidation of Thebit Bencora[197], which is at great variance with
+observations, nor the monstrous superstructures of other heavens, are any
+longer needed. A versatory iron turns to the position of the earth, and if
+disturbed ever so often returns always to the same points. For in the far
+regions of the north, in a latitude of 70 or 80 degrees (to which at the
+milder seasons of the year our sailors are accustomed to penetrate without
+injury from the cold); in the regions halfway between the poles; on the
+aequator in the torrid zone; and again in all the maritime places and lands
+of the south, in the highest latitude which has thus far been reached,
+always the iron magnetick finds its way, and points to the poles in the
+same manner (excepting for the difference of variation); on this side of
+the aequator (where we live), and on the other side to the south, less well
+known, but yet in some measure explored by sailors: and always the lily of
+the compass points toward the North. This we have had confirmed by the most
+eminent captains, and also by very many of the more intelligent sailors.
+These facts have been pointed out to me and confirmed by our most
+illustrious Sea-god, Francis Drake, and by another circumnavigator of the
+globe, Thomas Candish; our terrella also indicates the same thing. This is
+demonstrated in the case of the {118} [Illustration] orbicular stone, whose
+poles are A and B; an iron wire CD, which is placed upon the stone, always
+points directly along the meridian toward the poles AB, whether the centre
+of the wire is on the central line or aequator of the stone, or on any
+other part situated between the aequator and the poles, as at H, G, F, E.
+So the cusp of a versorium on this side of the aequator points toward the
+north; * on the other side the cross is always directed toward the south;
+but the cusp or lily[198] does not, as some one has thought, turn toward
+the south beyond the aequator. Some inexperienced people indeed, who in
+distant parts beyond the aequator have seen the versorium sometimes become
+more sluggish and less prompt, thought that the distance from the arctick
+pole or from the magnetick rocks was the cause of this. But they are very
+much mistaken; for it is as powerful[199], and adjusts itself as quickly to
+the meridian or to the point of variation in the southern as in the
+northern parts of the earth. Yet sometimes the motion appears slower,
+namely, when the supporting pin by lapse of time and long voyaging has
+become somewhat blunt, or the magnetick iron parts have lost, by age or
+rust, some of their acquired vigour. This may also be shown experimentally
+by the versatory iron of a small sun-dial placed on a very short pin set
+perpendicular to the surface of the stone, for the iron when touched by a
+loadstone points toward the poles of the stone and leaves the poles of the
+earth; for the general and remoter cause is overcome by the particular and
+powerful cause which is so near at hand. Magnetick bodies have of
+themselves an inclination toward the position of the earth and are
+influenced by a terrella. Two equal stones of equal strength adjust
+themselves to a terrella in accordance with magnetick laws. The iron
+conceives vigour from the loadstone and is influenced by the magnetical
+motions. Wherefore true direction is the motion of a magnetick body in
+regard to the verticity of the earth, the natures of both agreeing and
+working together toward a natural position and unity. For indeed we have
+found out at length, by many experiments and in many ways, that there is a
+disposing nature, moving them together by reason of their various positions
+by one form that is common {119} to both, and that in all magnetick
+substances there is attraction and repulsion. For both the stone[200] and
+the magnetick iron arrange themselves by inclination and declination,
+according to the common position of their nature and the earth. And the
+force of the earth by the virtue of the whole, by attracting toward the
+poles, and repelling, arranges all magneticks which are unfixed and loose.
+For in all cases all magneticks conform themselves to the globe of the
+earth in the same ways and by the same laws by which another loadstone or
+any magneticks do to a terrella.[201]
+
+       *       *       *       *       *
+
+
+CHAP. II.
+
+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._
+
+Directive force, which is also called by us verticity, is a virtue which
+spreads by an innate vigour from the aequator in both directions toward the
+poles. That power, inclining in both directions towards the termini, causes
+the motion of direction, and produces a constant and permanent position in
+Nature, not only in the earth itself but also in all magneticks. Loadstone
+is found either in veins of its own or in iron mines, when the homogeneous
+substance of the earth, either having or assuming a primary form, is
+changed or concreted into a stony substance, which besides the primary
+qualities of its nature has various dissimilitudes and differences in
+different quarries and mines, as if from different matrices, and very many
+secondary qualities and varieties in its substance. A loadstone which is
+dug out in this breaking up of the earth's surface and of protuberances
+upon it, whether formed complete in itself (as sometimes in China) or in a
+larger vein, is fashioned by the earth and follows the nature of the whole.
+All the interior parts of the earth mutually conspire together in
+combination and produce direction toward north and south. But those
+magnetical bodies which come together in the uppermost parts of the earth
+are not true united parts of the whole, but appendages and parts joined on,
+imitating the nature of the whole; wherefore when floating free on water,
+they dispose themselves just in the same way as they are placed in the
+terrestrial system of nature. We had a large loadstone of twenty pounds *
+weight, dug up and cut out of its vein, after we had first observed and
+marked its ends; then after it was dug out, we placed it in a boat on
+water, so that it could turn freely; then immediately the face which had
+looked toward the north in the quarry began to {120} turn to the north on
+the waves and at length settled toward that point. For that face which
+looked toward the north in the quarry is the southern, and is attracted by
+the northern parts of the earth, [Illustration] in the same way as pieces
+of iron which acquire their verticity from the earth. About this point we
+intend to speak afterwards[202] under change of verticity. But there is a
+different rotation of the internal parts of the earth, which are perfectly
+united to the earth and which are not separated from the true substance of
+the earth by the interposition of bodies as are loadstones in the upper
+portion of the earth, which is maimed, corrupt, and variable. Let A B be a
+piece of magnetick ore; between which and the uniform globe of the earth
+lie various soils or mixtures which separate the ore to a certain extent
+from the globe of the true earth. It is therefore influenced by the forces
+of the earth just in the same way as C D, a piece of iron, in the air. So
+the face B of some ore or of that piece of it is moved toward the Boreal
+pole G, just as the extremity C of the iron, not A or D. But the condition
+of the piece E F is different, which piece is produced in one connected
+mass with the whole, and is not separated from it by any earthy mixture.
+For if the part E F were taken out and floated freely in a boat by itself,
+it is not E that would be directed toward the Boreal pole, but F. So in
+those substances which acquire their verticity in the air, C is the
+southern part and is seen to be attracted by the Boreal pole G. In the case
+of others which are found in the upper unstable portion of the earth, B is
+the south, and in like manner inclines toward the Boreal pole. But if those
+pieces deep down which are produced along with the earth are dug up, they
+turn about on a different plan. For F turns toward the Boreal parts of the
+earth, because * is the southern part; E toward the south, because it is
+the northern. So of a magnetick body, C D, placed close to the earth, the
+end C turns toward the Boreal pole; of one that is adnate to it B A, B
+inclines to the North; of one that is innate in it, E F, E turns toward the
+southern pole; which is confirmed by the {121} [Illustration] following
+demonstration, and comes about of necessity according to all magnetick
+laws. Let there be a terrella with poles A B; from its mass cut out a small
+part E F; if this be suspended by a fine thread above the hole or over some
+other place, E does not seek the pole A but the pole B, and F turns to A;
+very differently from a rod of iron C D; because C, touching some northern
+part of the terrella, being magnetically carried away makes a turn round to
+A, not to B. And yet here it should be observed, that if the pole A of *
+the terrella were moved toward the earth's south, the end E of the piece
+cut out by itself, if not brought too near to the stone, would also move of
+itself toward the south. But the end C of the piece of iron, placed beyond
+its orbe of virtue, will turn toward the north. The part E F of the
+terrella, whilst in the mass, produced the same direction as the whole; but
+when it is separated and suspended by a thread, E turns to B, and F to A.
+[Illustration] {122} So parts having the same verticity with the whole,
+when separated, are impelled in the contrary direction; for contrary parts
+solicit contrary parts. Nor yet is this a true contrariety, but the highest
+concordancy, and the true and genuine conformation of bodies magnetical in
+the system of nature, if they shall have been divided and separated: for
+the parts thus divided should be raised some distance from the whole, as
+will be made clear afterwards. Magnetick substances seek a unity as regards
+form; they do not so much respect their own mass. Wherefore the part F E is
+not attracted into its former bed; but when once it is unsettled and at a
+distance, it is * solicited by the opposite pole. But if the small piece F
+E is placed back again in its bed or brought close to, without any
+substances intervening, it acquires its former combination, and, as a part
+of the whole once more united, accords with the whole and sticks readily in
+its former position; and E remains toward A, and F toward B, and they
+settle steadily in their mother's lap. The reasoning is the same when the
+stone is divided into equal parts through the poles. [Illustration] A
+spherical stone is divided into two equal parts along the axis A B; *
+whether therefore the surface A B is in the one part facing upward (as in
+the former diagram) or lying on its face in both parts (as in * the
+latter), the end A tends toward B. But it must also be understood that the
+point A is not carried with a definite aim always toward the point B,
+because in consequence of the division the verticity proceeds to other
+points, as to F G, as appears in the fourteenth chapter of this book. And L
+M are now the axes in each, and A B is no longer the axis; for magnetick
+bodies, as soon as they are divided, become single magnetick wholes; and
+they have {123} vertices in accordance with their mass, new poles arising
+at each end in consequence of the division. Yet the axis and the poles
+always follow the leading of a meridian; because that force passes along
+the meridians of the stone from the aequator to the poles, by an
+everlasting rule, the inborn virtue of the substance agreeing thereto from
+the long and lasting position and the facing of a suitable substance toward
+the poles of the earth; by whose strength continued through many centuries
+it has been fashioned; toward fixed and determined parts of which it has
+remained since its origin firmly and constantly turned.
+
+       *       *       *       *       *
+
+
+CHAP. III.
+
+How Iron acquires Verticity through
+a Loadstone, and how that verticity
+_is lost and changed_.
+
+Friction between an oblong piece of iron and a loadstone imparts to the
+former magnetick virtues, which are not corporeal nor inherent and
+persistent in any body, as we showed in the discussion on coition. It is
+plain that the iron, when it has been rubbed hard with one end and applied
+to the stone for a pretty long time, receives no stony nature, acquires no
+weight; for if, before the iron is touched by the stone, you weigh * it in
+a small and very exact goldsmith's balance, you will see after the rubbing
+that it has exactly the same weight, neither diminished nor increased. But
+if you wipe the iron with cloths after it has been touched, or wash it in
+water, or scour it with sand or on a grindstone, still it in nowise lays
+aside its acquired strength. For the force is spread through the whole body
+and conceived in the inmost parts, and cannot in any way be washed or wiped
+away. Let an experiment then be made in fire, that untamed tyrant of
+nature. Take a piece of iron of the length of a palm and the thickness of a
+goosequill pen; let this iron be passed through a suitable round cork and
+placed on the surface of water, and observe the end which turns to the
+north; rub this particular end with the true southern end of a loadstone;
+the iron so rubbed turns toward the south. Remove the cork, and place the
+end * which was excited in the fire until the iron is just red-hot; when it
+is cooled, it will retain the strength of the loadstone and the verticity,
+though it will not be so prompt, whether because the force of the fire had
+not yet continued long enough to overcome all its {124} strength, or
+because the whole iron was not heated to redness, for the virtue is
+diffused through the whole. Remove the cork a second time, and putting the
+whole iron in the fire, blow the fire with the bellows, so that it may be
+all aglow, and let it remain a little longer time red-hot; when cooled (so,
+however, that, whilst it is cooling, it does not rest in one position),
+place it again on the water with the cork, and you will see that it has
+lost the verticity * which it had acquired from the stone. From these
+experiments it is clear how difficult it is for the property of polarity
+implanted by the loadstone to be destroyed. But if a small loadstone had
+remained as long in the same fire, it would have lost its strength. Iron,
+because it does not so easily perish, and is not so easily burnt up as very
+many loadstones, retains its strength more stably, and when it is lost can
+recover it again from a loadstone; but a loadstone when burnt does not
+revive. But now that iron, which has * been deprived of its magnetick form,
+moves in a different way from any other piece of iron, for it has lost its
+polar nature; and whereas before the touch of the loadstone it may have had
+a motion toward the north, and after contact toward the south; now it turns
+to no definite and particular point; but afterwards, very slowly and after
+* a long time, it begins to turn in a doubtful fashion toward the poles of
+the earth (having acquired some power from the earth). I have said that the
+cause of direction was twofold, one implanted in the stone and iron, but
+the other in the earth, implanted by the disponent virtue; and for that
+reason (the distinction of poles and the verticity in the iron having now
+been destroyed) a slow and weak directive power is acquired anew from the
+verticity of the earth. We may see, therefore, with what difficulty and
+only by the application of hot fires and by long ignition of the iron
+heated to softness, the imparted magnetick virtue is eradicated. When this
+ignition has overcome the acquired polarity, and it has been now completely
+subdued and not awakened again, that iron is left unsettled and utterly
+incapable of direction. But we must further inquire how iron remains
+affected by verticity. It is manifest that it strongly affects and changes
+the nature of the iron, because the presence of a loadstone attracts the
+iron to itself with an altogether wonderful readiness. Nor is it only the
+part that is rubbed, but on account of the rubbing (on one end only) the
+whole iron is affected together, and gains by it a permanent though an
+unequal power. This is demonstrated as follows. Rub an iron wire on the end
+so * that it is excited, and it will turn towards the north; afterward cut
+off some portion of it; you will see that it still turns toward the north
+(as before), but more feebly. For it must be understood that the loadstone
+excites a steady verticity in the whole iron (if the rod be not too long)
+more vigorous throughout the whole mass in a shorter bar, and as long as
+the iron remains touching the loadstone a little {125} stronger. But when
+the iron is separated from contact with it, then it becomes much weaker,
+especially in the end that was not touched. Just as a long rod, one end of
+which is placed in the fire and heated, grows exceedingly hot at that end,
+less so in the parts adjoining and in the middle, whilst at the other end
+it can be held in the hand, and that end is only warm; so the magnetical
+vigour diminishes from the excited end to the other end; but it is present
+there instantly, and does not enter after an interval of time nor
+successively, as the heat in the iron; for as soon as a piece of iron has
+been touched by a loadstone it is excited throughout its whole length. For
+the sake of experiment, let there be a rod of iron 4 or * 5 digits long,
+untouched by a loadstone; as soon as you touch one end only with a
+loadstone, the opposite end immediately, or in the twinkling of an eye, by
+the power that it has conceived, repels or attracts a versorium, if it be
+applied to it ever so quickly.
+
+       *       *       *       *       *
+
+
+CHAP. IIII.
+
+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._
+
+Demonstration has already been given that the northern part of a loadstone
+does not attract the northern part of another stone, but the southern, and
+repels the northern part of another stone from its northern side when it is
+applied[203] to it. That general magnet, the terrestrial globe, disposes
+iron touched by a loadstone in the same way, and likewise magnetick iron
+stirs this same iron by its implanted strength, and excites motion and
+controls it. For whether the comparison and experiment has been made
+between loadstone and loadstone, or loadstone and iron, or iron and iron,
+or the earth and loadstone, or the earth and iron conformed * by the earth
+or strengthened by the power of a loadstone, the strength and inclinations
+of each must mutually harmonize and accord in the same way. But the reason
+must be sought, why a piece of iron when touched by a loadstone acquires a
+disposition to motion toward the opposite pole of the earth, and not toward
+that {126} pole of the earth to which that pole of that loadstone turned by
+which it was excited. It has been pointed out that iron and loadstone are
+of one primary nature; when the iron is joined to the loadstone, they
+become, as it were, one body, and not only is the end of the iron changed,
+but the remaining parts also are affected along with it. A, the north pole
+of a loadstone, is placed against the cusp of a piece of iron; the cusp of
+the iron has now become the southern part of the iron, [Illustration]
+because it is touching the northern part of the stone; the cross-end of the
+iron has become the northern. For if that contiguous magnetick substance be
+separated from the pole of the terrella, or from the parts near the pole,
+the one end (or the end which, whilst the connection was kept up, was
+touching the northern part of the stone) is the southern, whilst the other
+is the northern. So also if a versorium excited by a loadstone be divided
+into ever so many parts (however small), those parts when separated will,
+it is clear, arrange themselves in the same disposition as that in which
+they were disposed before, when they were undivided. Wherefore whilst the
+cusp remains over the northern pole A, it is not the southern end, but is,
+as it were, part of a whole; but when it is taken away from the stone, it
+is the southern end, because when rubbed it tended toward the northern
+parts of the stone, and the cross (the other end of the versorium) is the
+northern end. The loadstone and the iron make one body; B is the south pole
+of the whole; C (that is, the cross) is the northern end of the whole;
+divide the iron also at E, and E will be the southern end with respect to
+the cross; and E will likewise be the northern end in respect to B. A is
+the true northern pole of the stone and is attracted by the southern pole
+of the earth. The end of the iron which is touched by the true boreal part
+of the stone becomes the southern end, and turns to A, the north [pole] of
+the stone, if it be near; or if it be some distance from the stone it turns
+to the north [pole] of the earth. So always iron which is touched (if it is
+free and unrestrained) tends to the opposite part of the earth from that
+part to which the loadstone that touched it tends. Nor does it * make any
+difference how it is rubbed, whether straight up or slanting in some way.
+For in any case the verticity flows into the iron, {127} [Illustration]
+provided it is touched by either end. Wherefore all the cusps at B acquire
+the same verticity, after they are separated, but opposite to that pole of
+the stone; wherefore also they are united to the loadstone at the pole B;
+and all the crosses in the present figure have the opposite verticity to
+the pole E, and are moved and laid hold of by E when they are in a
+convenient position. It is exactly the same in the case of the long stone F
+H divided at G; F and H always move, both in the whole and in the divided
+stone, to opposite poles of the earth, and O and P mutually attract one
+another, the one of them being the northern, the other the southern. For,
+supposing H to have been the southern in the whole stone and F the
+northern, P will be the northern with respect to H in the divided stone,
+and O the southern with respect to F. So also F and H mutually incline to a
+connection, if they are turned a very little toward one another, and run
+together at length and join. But supposing the division of the stone to
+have been meridional (that is, according to the line of a meridian, not of
+any parallel circle), then they turn [Illustration] round, and A attracts
+B, and the end B is attracted to A and attracts A, until, being turned
+round, they are connected and cemented together; because magnetick
+attraction is not made along the parallels, but meridionally. For this
+reason pieces of iron placed on a terrella whose poles are A B, near the
+aequator along parallels, * do not combine or stick together firmly: {128}
+[Illustration] But if applied to one another along a meridian they are
+immediately * joined firmly together, not only on and near the stone, but
+even at some distance within the force of the controlling orbe. Thus they
+are joined and cemented together at E, but not at C in the other figure.
+For the opposite ends C and F meet and adhaere together in the case of the
+iron just in the same way as A and B before in the case of the stone. But
+they are opposite ends, because the pieces of iron proceed from the
+opposite sides and poles of the terrella; and C in reference to the
+northern pole A is southern, and F is boreal in reference to the * southern
+pole B. In like manner also they are cemented together, if the rod C (being
+not too long[204]) be moved further toward A, and F toward B, and they be
+joined together over the terrella, like A and B of the divided stone above.
+But now if the cusp A, * which has been touched by a loadstone, be the
+southern end, and you were to touch and rub with this the cusp of another
+iron needle B, which has not been touched, B will be northern, and will
+point to the south. But if you were to touch with the northern point B any
+other iron needle, still new, on its cusp, this again will be southern, and
+will turn to the north. The iron not only receives the necessary strength
+from the loadstone, if it be a good loadstone, but also imparts its
+acquired strength to another piece of iron, and the second to a third
+(always in strict accordance with magnetick laws). In all these
+demonstrations of ours it should always be borne in mind that the poles of
+a stone, as well as those of iron, whether touched or untouched, are always
+in fact and by nature opposite to the pole toward which they point and are
+so designated by us, as we have laid down above. For in them all it is
+always the northern * which tends to the south, either of the earth or of
+the stone, and the southern which tends to the north of the stone. Northern
+parts are attracted by the southern of the earth; so in the boat they {129}
+tend toward the south. A piece of iron touched by the northern parts of a
+loadstone becomes south at the one end and tends always (if it is near and
+within the orbe of the loadstone) to the north of the stone, and if it be
+free and left to itself at some distance from the stone, it tends to the
+northern part of the earth. The northern pole A of a loadstone turns to G,
+the south of the earth; a versorium touched at its cusp by the part A
+follows A, because it has become southern. But the versorium C, placed
+farther away from the loadstone, turns its cusp to F, the north of the
+earth, because * the cusp has become southern by contact with the boreal
+part of the stone. So the ends touched by the northern part of the stone
+are made southern, or are excited with a southern polarity, and tend toward
+the north of the earth; those touched by the southern pole are made
+northern, or are excited with a northern force, and turn to the south of
+the earth.
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+CHAP. V.
+
+On the Touching of pieces of Iron
+_of divers shapes._
+
+Bars of iron, when touched by a loadstone, have one end north, the other
+south, and in the middle is the limit of verticity, like the aequinoctial
+circle on the globe of a terrella or on an iron globe. But when an iron
+ring is rubbed on one side on a * loadstone, then the one pole is on the
+place that was in contact, whilst the other is at the opposite point; and
+the magnetick power divides the ring into two parts by a natural
+distinction which, though not in shape, yet in power and effect is like an
+aequator. But if a thin straight rod be bent into a ring without any
+welding or union of the ends, and be touched in the middle by a loadstone,
+both ends will be of the same verticity. Let a ring be taken which is whole
+and continuous, and which has been * touched by a loadstone at one place,
+and let it be divided afterward {130} at the opposite point and
+straightened out, both ends will also be * of the same verticity, no
+otherwise than a thin rod touched in the middle or a ring not cohaerent at
+the joint.
+
+       *       *       *       *       *
+
+
+CHAP. VI.
+
+What seems an Opposing Motion in Magneticks
+_is a proper motion toward unity_.
+
+[Illustration]
+
+In things magnetical nature always tends to unity, not merely to confluence
+and agglomeration, but to harmony; in such a way that the rotational and
+disponent faculty should not be disturbed, as is variously shown in the
+following example. Let C D be an entire body of some magnetick substance,
+in which C tends to B, the north of the earth, and D to the south, A.
+Then[205] divide it in the middle in its aequator, and it will be E that is
+tending toward A, and F tending toward B. For just as in the undivided
+body, so in the divided, nature aims at these bodies being united; the end
+E again joins with F harmoniously and * eagerly and they stick together,
+but E is never joined to D, nor F to C; for then C must be turned contrary
+to nature toward A, the south, or D toward B, the north, which is foreign
+to them and incongruous. Separate the stone in the place where it is cut
+and turn D round to C; they harmonize and combine excellently. For D is
+tending to the south, as before, and C to the north; E and F, parts which
+were cognate in the ore, are now widely separated, for they do not move
+together on account of material affinity, but they take their motion and
+inclination from their form. So the ends, whether joined or divided, tend
+magnetically in the same way to the earth's poles in the first figure where
+there is one whole, or divided as in the second figure; and F E in the
+second figure is a perfect magnetick joined together into one body and C D,
+just as it was primarily produced in its ore, and F E in its boat, turn in
+{131} this way to the poles of the earth and are conformed to them. * This
+harmony of the magnetick form is shown also in the forms of vegetables. Let
+A B be a twig from a branch of osier or other * tree which sprouts easily.
+Let A be the upper part, B the lower part toward the root; divide it at C
+D; I say that the end D, if grafted again to C by the primer's art, grows
+to it; just as also if B is grafted to A, they grow together and germinate.
+But D being grafted on A, or C on B, they are at variance, and never grow
+into one another, but one of them dies on account of the inverted and
+inharmonious arrangement, since the vegetative force, which moves in one
+way, is now impelled in opposite directions.
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+CHAP. VII.
+
+A determined Verticity and a disponent Faculty are what
+arrange magneticks, not a force, attracting or pulling them
+_together, nor merely strongish coition or unition_.
+
+[Illustration] {132}
+
+In the neighbourhood of the aequinoctial A there is no coition of the ends
+of a piece of iron with the terrella; at the poles there is the strongest.
+The greater the distance from the aequinoctial, the stronger is the coition
+with the stone itself, and with any part of it, not with its pole alone.
+Yet pieces of iron are not raised up on account of some peculiar attracting
+force or a stronger combined force, but on account of that common directing
+or conforming and rotating force; nor indeed is a spike in the part about
+B, even one that is very small and of no * weight[206], raised up to the
+perpendicular by the strongest terrella, but cleaves to it obliquely. Also
+just as a terrella attracts magnetick bodies variously with dissimilar
+forces, so also an iron snout placed on the stone obtains a different
+potency in proportion to the latitude, * just as a snout at L by its firmer
+connection resists a greater weight more stoutly than one at M, and at M
+than at N. But neither does the snout raise the spike to the perpendicular
+except at the poles, as is shown in the figure. A snout at L may hold and
+lift from the earth two ounces of iron in one piece; yet it is not strong
+enough to raise an iron wire of two grains weight to the perpendicular,
+which would happen if the verticity arose on account of a * stronger
+attraction, or rather coition or unition.
+
+       *       *       *       *       *
+
+
+CHAP. VIII.
+
+Of Discords between pieces of Iron upon the same pole
+of a loadstone, and how they can agree and
+_stand joined together_.
+
+Suppose two iron wires or a pair of needles stuck on the pole of a
+terrella; though they ought to stand perpendicularly, they mutually repel
+one another at the upper * end, and produce the appearance of a fork; and
+if one end be forcibly impelled toward the other, the other declines and
+bends away from association with it, as in the following figure.
+[Illustration] {133} A and B, iron spikes, adhaere obliquely[207] upon the
+pole on account of their nearness to one another; either alone would
+otherwise stand erect and perpendicular. For the extremities A B, being of
+the same verticity, mutually abhor and fly one another. For if C be the
+northern pole of the terrella, A and B are also northern ends; but the ends
+which are joined to and held at the pole C are both * southern. But if
+those spikes be a little longer (as, for example, of two digits length) and
+be joined by force, they adhaere together and unite in a friendly style,
+and are not separated without force. For they are magnetically welded, and
+there are now no longer two distinct ends, but one end and one body; no
+less than a wire which is doubled and set up perpendicularly. But here is
+seen also another subtile point, that if those spikes were shorter, not as
+much as the * breadth of one digit, or even the length of a barleycorn,
+they are in no way willing to harmonize or to stand straight up at the same
+time, because naturally in shorter wires the verticity is stronger in the
+ends which are distant from the terrella and the magnetick discord more
+vehement than in long ones. Wherefore they in no way admit of an intimate
+association and connection.
+
+[Illustration]
+
+Likewise if those lighter pieces of iron or iron wires be suspended,
+hanging, as A and B, from a very fine silk thread, not twisted * but
+braided, distant from the stone the length of a single barleycorn, then the
+opposing ends, A and B, being situated within the orbe of virtue above the
+pole, keep a little away from one another for the same reason; except when
+they are very near the pole of the stone C, the stone then attracting them
+more strongly toward one end.
+
+       *       *       *       *       *
+
+
+{134} CHAP. IX.
+
+Figures illustrating direction and showing varieties
+_of rotations_.
+
+[Illustration]
+
+Passing from the probable cause of motion toward fixed points (according to
+magnetick laws and principles), it remains for us to indicate those
+motions. Above a round loadstone (whose poles are A, B) let a versatory
+needle be placed whose cusp has been excited by the pole A; that cusp is
+certainly directed toward A, and is strongly attracted by A; because,
+having been touched by A, it is in true harmony with A, and combines with
+it; and yet it is called contrary, because when the versorium is separated
+from the stone, it is seen to be moved toward the opposite part of the
+earth to that toward which the pole A of the loadstone is moved. For if A
+be the northern pole of the terrella, the cusp is the southern end of the
+needle, of which the other end (namely, the cross) is pointed to B; so B is
+the southern pole of the loadstone, but the cross is the northern end of
+the versorium. So also the cusp is attracted by E, F, G, H, and by every *
+part of a meridian, from the aequator toward the pole, by the faculty
+disponent; and when the versorium is on the same parts of the meridian, the
+cusp is directed toward A. For it is not the point A that turns the
+versorium toward it, but the whole loadstone; as also the whole earth does,
+in the turning of loadstones to the earth.
+
+[Illustration]
+
+_Figures illustrating magnetick directions in a right sphere[208] of stone,
+and in the right sphere of the earth, as well as the polar directions to
+the perpendicular of the poles._ All these cusps have been touched by the
+pole A; all the cusps are turned toward A, excepting that one which is
+repelled by B.
+
+{135}
+
+[Illustration] _Figures illustrating horizontal directions above the body
+of a loadstone._ All the cusps that have been made southern by rubbing on
+the boreal pole, or some place round the northern pole A, turn toward the
+pole A, and turn away from the southern pole B, toward which all the
+crosses look. I call the direction horizontal, because it is arranged along
+the plane of the horizon; for nautical and * horological instruments are so
+constructed that the iron hangs or is supported in aequilibrium on the
+point of a sharp pin, which prevents the dipping of the versorium, about
+which we intend to speak later. And in this way it is of the greatest use
+to man, indicating and distinguishing all the points of the horizon and the
+winds. Otherwise on every oblique sphere (whether of stone or the earth)
+versoria and all magnetick substances would have a dip by their own nature
+below the horizon; and at the poles the directions would be perpendicular,
+which appears in our discussion _On Declination_.
+
+[Illustration]
+
+_A round stone (or terrella) cut in two at the aequator;_ and all the cusps
+have been touched by the pole A. The points at the centre of the earth, and
+between the two parts of the terrella which has been cut in two through the
+plane of the aequator, {136} are directed as in the present[209] diagram.
+This would also happen in the same way if the division of the stone were
+through the plane of a tropick, and the mutual separation of the divided
+parts and the interval between them were the same as before, when the
+loadstone was divided through the plane of the aequator, and the parts
+separated. For the cusps are repelled by C, are attracted by D; and the
+versoria are parallel, the poles or the verticity in both ends mutually
+requiring it.
+
+[Illustration]
+
+_Half a terrella by itself and its directions, unlike the directions * of
+the two parts close to one another as shown in the figure above_. All the
+cusps have been touched by A; all the crosses below except the middle one
+tend toward the loadstone, not straight, but obliquely; because the pole is
+in the middle of the plane which before was the plane of the aequator. All
+cusps touched by places distant from the pole move toward the pole (exactly
+the same as if they had been rubbed upon the pole itself), not toward the
+place where they were rubbed, wherever that may have been in the undivided
+stone in some latitude between the pole and the aequator. And for this
+reason there are only two distinctions of regions, northern and southern,
+in the terrella, just {137} as in the general terrestrial globe, and there
+is no eastern nor western place; nor are there any eastern or western
+regions, rightly speaking; but they are names used in respect of one
+another toward the eastern or western part of the sky. Wherefore it does
+not appear that Ptolemy did rightly in his _Quadripartitum_, making eastern
+and western districts and provinces, with which he improperly connects the
+planets, whom the common crowd of philosophizers and the superstitious
+soothsayers follow.
+
+       *       *       *       *       *
+
+
+CHAP. X.
+
+On Mutation of Verticity and of Magnetick
+Properties, or on alteration in the power
+_excited by a loadstone_.
+
+Friction with a loadstone gives to a piece of iron a verticity strong
+enough; not, however, so stable that the iron may not by being rubbed on
+the opposite part (not only with a more powerful loadstone, but with the
+same) be changed and deprived of all its former verticity, and indued with
+a new and opposite one. Take a piece of iron wire and rub each end of the
+wire equally with one and the same pole of a loadstone, and let it be
+passed through a suitable cork and place it on water. Then truly one end of
+the wire will be directed toward that pole of the earth toward which that
+end of the stone will not turn. But which end of the iron wire will it be?
+That certainly which was rubbed last. Rub the other end of this again with
+the same pole, and immediately * that end will turn itself in the opposite
+direction. Again touch the former end of the iron wire only with the same
+pole of the loadstone as before; and that[210] end, having gained the
+command, immediately changes to the contrary side. So you will be able to
+change the property of the iron frequently, and that end of the wire rules
+which has been touched the last. Now then merely hold the boreal pole of
+the stone for some time near the boreal part of the wire which was last
+touched, so that it does not touch, but so that it is removed from it by
+one, two, or even three digits, if the stone have been pretty * strong; and
+again it will change its property and will turn round to the contrary side;
+which will also happen (albeit rather more feebly) even if the loadstone be
+removed to a distance of four digits. You will be able to do the same
+thing, moreover, with both the austral and the boreal part of the stone in
+all these experiments. Verticity may likewise be acquired and changed when
+thin plates of gold, * silver, and glass are interposed between the stone
+and the end of the iron or iron wire, if the stone were rather strong, even
+if the {138} intermediate lamina is not touched either by the iron or the
+stone. And these changes of verticity take place in smelted iron. Indeed
+what the one pole of the stone implants and excites, the other disturbs and
+extinguishes, and confers a new force. For it does not require a stronger
+loadstone to take away the weaker and sluggish virtue and to implant the
+new one; nor is iron inebriated by the equal strength of loadstones, and
+made utterly uncertain and neutral, as Baptista Porta teaches; but by one
+and the same loadstone, or by loadstones endowed with equal power and
+might, its strength is, in accordance with magnetick rules, turned round
+and changed, excited, repaired, or disturbed. But a loadstone itself, by
+being rubbed on another, whether a larger or a more powerful stone, is not
+disturbed from its own property and verticity, nor does it turn round
+toward the opposite direction in its boat, or to the other pole opposite to
+that to which it inclines by its own nature and implanted verticity. For
+strength which is innate and has been implanted for a very long time abides
+more firmly, nor does it easily yield from its ancient holding; and that
+which has grown for a long time is not all of a sudden brought to nothing,
+without the destruction of the substance containing it. Nevertheless in a
+long interval of time a change * does take place; in one year, that is to
+say, or two, or sometimes in a few months; doubtless when a weaker
+loadstone remains lying by a stronger one contrary to the order of nature,
+namely, with the northern pole of one loadstone adjoined to the northern
+pole of another, or the southern to the southern. For so the weaker
+strength gradually declines with the lapse of time.
+
+       *       *       *       *       *
+
+
+CHAP. XI.
+
+On the Rubbing of a piece of Iron on a Loadstone
+in places midway between the poles, and upon
+_the aequinoctial of a terrella_.
+
+Select a piece of iron wire of three digits length, not touched by a
+loadstone (but it will be better if its acquired verticity be rather weak
+or have been damaged in some way); touch it and rub it on the aequator of a
+terrella, exactly on the aequinoctial line in the direction of its length,
+on the one end, or the ends only, or in all its parts; place the wire
+touched in this * way on water in a cork fitted for it; it will swim about
+doubtfully on the waves without any acquired verticity, and the verticity
+previously implanted will be disturbed. If, however, it float by chance
+toward the poles, it will be checked a little by the poles of the earth,
+and will at length by the influence of the earth be indued with verticity.
+
+       *       *       *       *       *
+
+
+{139} CHAP. XII.
+
+In what way Verticity exists in any Iron that has
+_been smelted though not excited by a lodestone_.
+
+[Illustration]
+
+Having thus far[211] demonstrated natural and inborn causes and powers
+acquired by means of the stone, we will now examine the causes of magnetick
+virtues in smelted iron that has not been excited by a stone. Loadstone and
+iron furnish and exhibit to us wonderful subtilities. It has been
+repeatedly shown above that iron not excited by a stone turns north and
+south; further that it has verticity, that is, special and peculiar polar
+distinctions, just as a loadstone, or iron which has been rubbed upon a
+loadstone. This indeed seemed to us at first wonderful and incredible; the
+metal of iron from the mine is smelted in the furnace; it runs out of the
+furnace, and hardens into a great mass; this mass is divided in great
+worksteads, and is drawn into iron bars, from which smiths again construct
+many instruments and necessary pieces of iron-work. Thus the same mass is
+variously worked up and transformed into very many similitudes. What is it,
+then, which {140} preserves its verticity, and whence is it derived? So
+take this first from the above[212] smithy. Let the blacksmith beat out
+upon his anvil a glowing mass of iron of two or three ounces weight into an
+iron spike of the length of a span of nine inches. Let the smith be
+standing with his face to the north, his back to the south, so that * the
+hot iron on being struck has a motion of extension to the north; and let
+him so complete his work with one or two heatings of the iron (if that be
+required); let him always, however, whilst he is striking the iron, direct
+and beat out the same point of it toward the north, and let him lay down
+that end toward the north. Let him in this way complete two, three, or more
+pieces of iron, nay, a hundred or four hundred; it is demonstrable that all
+those which are thus beaten out toward the north, and so placed whilst they
+are cooling, turn round on their centres; and floating pieces of iron
+(being transfixed, of course, through suitable corks) make a motion in the
+water, the determined end being toward the north. In the same way also
+pieces of iron acquire verticity from their direction whilst they are being
+beaten out and hammered or drawn out, * as iron wires are accustomed to do
+toward some point of the horizon between east and south or between south
+and west, or in the opposite direction. Those, however, which are pointed
+or drawn out rather toward the eastern or western point, conceive * hardly
+any verticity or a very undecided one. That verticity is especially
+acquired by being beaten out. But a somewhat inferior iron ore, in which no
+magnetick powers are apparent, if put in a * fire (its position being
+observed to be toward the poles of the world or of the earth) and heated
+for eight or ten hours, then cooled away from the fire, in the same
+position towards the poles, acquires a verticity in accordance with the
+position of its heating and cooling. Let a rod of cast iron be heated
+red-hot in a strong fire, in which it lies * meridionally (that is, along
+the path of a meridian circle), and let be removed from the fire and
+cooled, and let it return to its former temperature, remaining in the same
+position as before; then from this it will turn out that, if the same ends
+have been turned to the same poles of the earth, it will acquire verticity,
+and the end which looked toward the North on water with a cork before the
+heating, if it have been placed during the heating and cooling toward the
+fourth, now turns round to the south. But if perchance sometimes the
+rotation have been doubtful and somewhat feeble, let it be placed again in
+the fire, and when it is taken out at a red heat, let it be perfectly
+cooled toward the pole from which we desire the verticity, and the
+verticity will be acquired. Let the same rod be heated * in the contrary
+position, and let it be placed so at a red heat it is cool; for it is from
+its position in cooling (by the operation of the verticity of the earth)
+that verticity is put into the iron, and it turns round to parts contrary
+to its former verticity. So {141} the end which formerly looked toward the
+north now turns to the south. In accordance with these reasonings and in
+these ways the boreal pole of the earth gives to the end of a piece of iron
+turned toward it a southern verticity, and that end is attracted by that
+pole. * And here it must be observed that this happens to iron not only
+when it is cooled in the plane of the horizon, but also at any angle to it
+almost up to the perpendicular toward the centre of the earth. So the
+heated iron conceives vigour and verticity from the earth more quickly in
+the course of its return to its normal state, and in its recovery, as it
+were (in the course of which it is transformed), than by its mere position
+alone. This is effected better and more * perfectly in winter and in colder
+air, when the metal returns more certainly to its natural temperature, than
+in summer and in warm regions. Let us see also what position alone and a
+direction toward the poles of the earth can effect by itself without fire
+and heat. Iron rods which have been placed and fixed for a long time,
+twenty * or more years, from south to north (as they not infrequently are
+fixed in buildings and across windows), those rods, I say, by that long
+lapse of time acquire verticity and turn round, whether hanging in the air,
+or floating (being placed on cork), to the pole toward which they were
+pointing, and magnetically attract and repel a balanced iron magnetick; for
+the long continued position of the body toward the poles is of much avail.
+This fact (although conspicuous by manifest experiments) is confirmed by an
+incident related in an Italian letter[213] at the end of a book of Maestro
+Filippo Costa, of Mantua, _Sopra le Compositioni degli Antidoti_ written in
+Italian, which translated runs thus: "A druggist of Mantua showed me a
+piece of iron entirely changed into a magnet, drawing another piece of iron
+in such a way that it could be compared with a loadstone. Now this piece of
+iron, when it had for a long time held up a brick ornament on the top of
+the tower of the church of St. Augustine at Rimini, had been at length bent
+by the force of the winds, and remained so for a period of ten years. When
+the monks wished to bend it back to its former shape, and had handed it
+over to a blacksmith, a surgeon named Maestro Giulio Caesare discovered
+that it was like a magnet and attracted iron." This was caused by the
+turning of its extremities toward the poles for so long a time. And so what
+has been laid down before about change of verticity should be borne in
+mind; how in fact the poles of iron spikes are altered, when a loadstone is
+placed against them only with its pole and points toward them, even at a
+rather long distance. Clearly it is in the same way that that large magnet
+also (to wit, the earth itself) affects a piece of iron and changes its
+verticity. For, although the iron may not touch the pole of the earth, nor
+any magnetick part of the earth, yet verticity is acquired and changed; not
+because the poles of the earth and the point itself which is 39deg distant
+{142} from our city of London, changes the verticity at a distance of so
+many miles; but because the whole magnetick earth, that which projects to a
+considerable height, and to which the iron is near, and that which is
+situated between us and the pole, and the vigour existing within the orbe
+of its magnetick virtue (the nature of the whole conspiring thereto),
+produces the verticity. For the magnetick effluence of the earth rules
+everywhere within the orbe of its virtue, and transforms bodies; but those
+things which are more similar to it, and specially connected with it by
+nature, it rules and controls; as loadstone and iron. Wherefore in very
+many matters of business and actions it is clearly not superstitious and
+idle to observe the positions and conditions of lands, the points of the
+horizon and the places of the stars. For as when a babe is brought forth
+into the light from its mother's womb, and acquires respiration and certain
+animal activities, then the planets and celestial bodies[214], according to
+their position in the universe, and according to that configuration which
+they have with regard to the horizon and the earth, instil peculiar and
+individual qualities into the newly born; so that piece of iron, whilst it
+is being formed and lengthened out, is affected by the common cause (to
+wit, the earth); whilst it is returning also from its heated condition to
+its former temperature, it is imbued with a special verticity in accord
+with its position. Rather long pieces of iron sometimes have the same
+verticity * at each end; wherefore they have motions which are less certain
+and well ordered on account of their length and of the aforesaid processes,
+exactly as when an iron wire four feet long is rubbed at each end upon the
+same pole of a loadstone.
+
+       *       *       *       *       *
+
+
+CHAP. XIII.
+
+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._
+
+Ligneous substances floating on water never by their own strength turn
+round toward the poles of the earth, save by chance. So wires of gold,
+silver, brass, tin, lead, or glass, pushed through corks and floating, have
+no sure direction; and for this reason they do not show poles or points of
+variation when rubbed with a loadstone. For those things which do not of
+themselves incline toward the poles and obey the earth are also not ruled
+by {143} the touch of a loadstone; for the magnetick vigour has no entrance
+into their inward parts; neither is the magnetick form received by them,
+nor are their forms magnetically excited; nor, if it did enter, would it
+effect anything, because in those bodies (mixed up with various kinds of
+efflorescent humours and forms, corrupted from the original property of the
+earth) there are no primary qualities. But those prime qualities of iron
+are excited by the juxtaposition of a loadstone, just as brute animals or
+men, when they are awakened out of sleep, move and put forth their
+strength. Here one must marvel at a demonstrable error of B. Porta, who,
+while rightly opposing a very old falsehood about the diamond, in speaking
+of a power contrary to that of the loadstone, introduces another still
+worse opinion; that forsooth iron, when touched by a diamond, turns to the
+north. "If" (he says) "you rub a steel-Needle on a Diamond, and then put it
+in a Boat, or thrust it through a reed, or hang it up by a Thread, it will
+presently turn to the North, almost as well as if it had been touched with
+the Loadstone; but something more faintly. And, what is worth noting, the
+contrary part will turn the iron to the South: and when I had tried this in
+many steel-Needles, and put them all into the Water, I found, that they all
+stood equi-distant, pointing to the North." This indeed would * be contrary
+to our magnetick rules. For this reason we made an experiment with seventy
+excellent diamonds, in the presence of many witnesses, on a large number of
+spikes and wires, with the most careful precautions, floating (thrust, of
+course, through their corks) on the surface of water; never, however, could
+we observe this. He was deceived by the verticity acquired from the earth
+(as stated above) in the spike or wire of iron itself, and the iron itself
+turned aside to its own definite pole; and he, being ignorant of this,
+thought it was done by the diamond. But let the investigators of natural
+phenomena take heed that they are not the more deceived by their own badly
+observed experiments, and disturb the commonwealth of letters with their
+errors and stupidities. Diamond is sometimes designated by the name of
+_Sideritis_, not because it is made of iron or because it draws iron, but
+on account of its lustre, resembling flashing steel; with such a lustre do
+the choicest pieces of diamond shine; hence by very many writers many
+qualities are imputed to diamond which really belong to siderite loadstone.
+
+       *       *       *       *       *
+
+
+{144} CHAP. XIIII.
+
+The Placing of a Loadstone above or below a magnetick
+body suspended in aequilibrium changes neither the power
+_nor the verticity of the magnetick body._
+
+Quietly to pass this over would be improper, because a recent error arising
+from a defective observation of Baptista Porta must be overthrown; on which
+he (by an unfortunate repetition) even writes three chapters, namely, the
+18th, the 31st, and the 42nd. For if a loadstone or a piece of magnetick
+iron, hanging in aequilibrium or floating on water, is attracted and
+disposed toward certain definite points, when you bring above it a piece of
+iron or another loadstone, it will not, if you afterward put the same[215]
+below it, turn round to the contrary parts; but the same ends of the iron
+or the loadstone will always be directed toward the same ends of the stone,
+even if the loadstone or the iron is suspended in any way in aequilibrium
+or is poised on a needle, so that it can turn round freely. He was deceived
+by the irregular shape of some stone, or because he did not arrange the
+experiment suitably. Wherefore he is led astray by a vain opinion, and
+thinks he may infer that, just as a stone has an arctic and antarctic pole,
+so also it has a western and an eastern, and an upper and a lower pole. So
+from foolish ideas conceived and admitted arise other fallacies.
+
+       *       *       *       *       *
+
+
+CHAP. XV.
+
+The Poles, Aequator, Centre in an entire Loadstone
+_remain and continue steady; by diminution and_
+separation of some part they vary and
+_acquire other positions._
+
+[Illustration] *
+
+Suppose A B to be a terrella, whose centre is E, and whose diameter (as
+also its aequinoctial circle) is D F. If you cut off a portion (through the
+arctic circle, for example), G H, it is demonstrable that the pole which
+was at A now has a position at I. But the centre and the aequinoctial
+recede toward B {145} merely so that they are always in the middle of the
+mass that is left between the plane of the arctick circle G I H and the
+antarctick pole B. Therefore the segment of the terrella comprised between
+the plane of the former aequinoctial (that, of course, which was the
+aequator before cutting that part away) D E F and the newly acquired
+aequator M L N will always be equal to the half of that part which was cut
+off, G I H A. [Illustration] * But if the portions have been taken away
+from the side C D, the poles and axis will not be in the line A B, but in E
+F, and the axis would be changed in the same proportion as the aequator in
+the former figure. For those positions of forces and virtues, or rather
+limits of the virtues, which are derived from the whole form, are moved
+forward by change of quantity and shape; since all these limits arise from
+the conspiring together of the whole and of all {146} the parts united; and
+the verticity or the pole is not a virtue innate in one part, or in some
+definite limit, or fixed in the substance; but it is an inclination of the
+virtue to that part. And just as a terrella separated from the earth has no
+longer the earth's poles and aequator, but individual ones of its own; so
+also if it again be divided, those limits and distinctions of the qualities
+and virtues pass on to other parts. But if a loadstone be divided in any
+way, either along a parallel, or meridionally, so that by the change of
+shape either the poles or the aequator move to other positions, if the part
+cut off be merely applied in its natural position and joined to the whole,
+even without any agglutination or cementing together, the determining
+points of the virtues return again to their former sites, as if no part of
+the body had been cut off. When a body is entire, its form remains entire;
+but when the body is lessened, a new whole is made, and there arises a new
+entirety, determined for every loadstone, however small, even for magnetick
+gravel, and for the finest sand.
+
+       *       *       *       *       *
+
+
+CHAP. XVI.
+
+If the Southern Portion of a Stone be lessened,
+something is also taken away from the power
+_of the Northern Portion._
+
+Now although the southern end of a magnetick iron is attracted by a
+northern end, and repelled by a southern, yet the southern portion of a
+stone does not diminish, but increases the potency of the boreal part.
+Wherefore if a stone be cut in two and divided through the arctick circle,
+or through the tropick of Cancer or the aequator, the southern portion does
+not attract magnetick substances so strongly with its pole as before;
+because a new whole arises, and the aequator is removed from its old
+position and moves forward on account of that cutting of the stone. In the
+former condition, since the opposite portion of the stone increases the
+mass beyond the plane of the aequator, it strengthens also the verticity,
+and the potency, and the motion to unity.
+
+       *       *       *       *       *
+
+
+{147} CHAP. XVII.
+
+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._
+
+Versoria prepared by the loadstone subserve so many actions in human life
+that it will not be out of place to record a better method of touching them
+and exciting them magnetically, and a suitable manner of operating. Rich
+ores of iron and such as yield a greater proportion of metal are recognized
+by means of an iron needle suspended in aequilibrium and magnetically
+prepared; and magnetick stones, clays, and earths are distinguished,
+whether crude or prepared. An iron needle (the soul of the mariners'
+compass), the marvellous director in voyages and finger of God, one might
+almost say, indicates the course, and has pointed out the whole way around
+the earth (unknown for so many ages). The Spaniards (as also the English)
+have frequently circumnavigated (by an immense circuit) the whole globe by
+aid of the mariners' compass. Those who travel about through the world or
+who sit at home have sun-dials. A magnetick pointer follows and searches
+out the veins of ore in mines. By its aid mines are driven in taking
+cities; catapults and engines of war are aimed by night; it has been of
+service for the topography of places, for marking off the areas and
+position of buildings, and for excavating aqueducts for water under ground.
+On it depend instruments designed to investigate its own dip and variation.
+
+When iron is to be quickened by the stone, let it be clean and bright,
+disfigured by no rust or dirt, and of the best steel[216]. Let the stone
+itself be wiped dry, and let it not be damp with any moisture, but let it
+be filed gently with some smooth piece of iron. But the hitting of the
+stone with a hammer is of no advantage. By these means let their bare
+surfaces be joined, and let them be rubbed, so that they may come together
+more firmly; not so that the material substance of the stone being joined
+to the iron may cleave to it, but they are rubbed gently together with
+friction, and (useless parts being rubbed off) they are intimately united;
+whence a more notable [Illustration] virtue arises in the iron that is
+excited. A is the best way of touching a versorium when the cusp touches
+the pole and faces it; B is a moderately good way, when, though facing it,
+it is a little way {148} distant from the pole; also in like manner C is
+only moderately good on account of the cusp being turned away from the
+pole; D, which is farther distant, is hardly so good; F, which is prepared
+crosswise along a parallel, is bad; of no virtue and entirely irresponsive
+and feeble is the magnetick index L, which is rubbed along the aequator;
+oblique and not pointing towards the pole as G, and oblique, not pointing
+toward but turned away from the pole as H, are bad. These have been placed
+so that they might indicate the distinct forces of a round stone. But
+mechanicians very often have a stone tending more to a cone shape, and more
+powerful on account of that shape since the pole, on which they rub their
+wires, is at the apex of the projecting part. Sometimes the stone has on
+the top and above its own pole an artificial acorn or snout made of steel
+for the sake of its power. Iron needles are rubbed on the top of this;
+wherefore they turn toward the same pole as if they had been prepared on
+that part of the stone with the acorn removed. Let the stone be large
+enough and strong; the needle, even if it be rather long, should be
+sufficiently thick, not very slender; with a moderate cusp, not too sharp,
+although the virtue is not in the cusp itself only, but in the whole piece
+of iron. A strong large stone is not unfit for rubbing all needles on,
+excepting that sometimes by its strength it occasions some dip and
+disturbance in the iron in the case of longer needles; so that one which,
+having been touched before, rested in equilibrium in the plane of the
+horizon, now when touched and excited dips at one end, as far as the
+upright pin on which it turns permits it. Wherefore in the case of longer
+versoria, the end which is going to be the Boreal, before it is rubbed,
+should be a little lighter, so that it may remain exactly in aequilibrio
+after it is touched. But a needle in this way prepared does its * {149}
+work worse the farther it is beyond the aequinoctial circle. Let the
+prepared needle be placed in its capsule, and let it not be touched by any
+other magneticks, nor remain in the near vicinity of them, lest by their
+opposing forces, whether powerful or sluggish, it should become uncertain
+and dull. If you also rub the other end of the needle on the other pole of
+the stone, the needle will perform its functions more steadily, especially
+if it be rather long. A piece of iron touched by a loadstone retains the
+magnetick virtue, excited in it even for ages[217], firm and strong, if it
+is placed according to nature meridionally and not along a parallel, and is
+not injured by rust or any external injury from the surrounding medium.
+Porta wrongly seeks for a proportion between the loadstone and the iron:
+because, he says, a little piece of iron will not be capable of holding
+much virtue; for it is consumed by the great force of the loadstone. A
+piece of iron receives its own virtue fully, even if it be only of the
+weight of one scruple, whilst the mass of the loadstone is a thousand
+pounds. It is also useless to make the needle rather flat at the end that
+is touched, so that it may be better and more perfectly magnetick, and that
+it may best receive and hold certain magnetick particles; since hardly any
+part will stick on a sharp point; because he thought that it was by the
+adhesion of parts of the loadstone (as it were, hairs) that the influence
+is imparted and conserved, though those particles are merely rubbed off by
+the rubbing of the iron over the softer stone, and the iron none the less
+points toward the North and South, if after it is touched it be scoured
+with sand or emery powder, or with any other material, even if by long
+rubbing of this kind the external parts of it are lessened and worn away.
+When a needle is being rubbed, one should always leave off at the end;
+otherwise, if it is rubbed on the loadstone from the point toward the
+middle, less verticity is excited in the iron, sometimes none at all, or
+very little. For where the last contact is, there is the pole and goal of
+verticity. In order that a stronger verticity may be produced in the iron
+by rubbing on the loadstone, one * ought in northern lands to turn the true
+northern pole of the loadstone toward the highest part of the sky; on this
+pole that end of the needle is going to be rubbed, which shall afterwards
+turn toward the north of the earth; whilst it will be an advantage for the
+other end of the needle to be rubbed on the southern pole of the terrella
+turned toward the earth, and this being so excited will incline toward the
+south. In southern regions beyond the aequator the plan is just the
+contrary. The reason of this dissimilarity is demonstrated, Book II., chap,
+xxxiv., in which it is shown (by a manifest combination of a terrella and
+the earth) why the poles of a loadstone, for different reasons, are one
+stronger than the other. If a needle be touched between the mutually
+accordant * poles of two loadstones, equal in power, shape, and mass, no
+strength {150} [Illustration] is acquired by the needle. A and B are two
+loadstones attracting one another, according to nature, at their dissimilar
+ends; C, the * point of a needle touched by both at once, is not excited
+(even if those loadstones be connected according to nature), if they are
+equal; but if they are not equal, virtue is acquired from the stronger.
+When a needle is being excited by a loadstone, begin in the middle, and
+draw the needle toward its end; at the end let the application be continued
+with a very gentle rubbing around the end for some time; that is to say,
+for one or two minutes; do not repeat the motion from the middle to the end
+(as is frequently done) for in this way the verticity is injured. Some
+delay is desirable, for although the power is imparted instantly, and the
+iron excited, yet from the vicinity of the loadstone and a suitable delay,
+a more steady verticity arises, and one that is more firmly durable in the
+iron. Although an armed stone raises a greater weight of iron than an
+unarmed one, yet a needle is not more strongly excited by an armed stone
+than by an unarmed one. Let there be two iron wires of the same length,
+wrought from the same wire; let one be excited by an armed end, the other
+by an unarmed end; it is manifest that the same needles have a beginning of
+motion or a sensible inclination at equal distances from the same armed and
+unarmed loadstone; this is ascertained by measuring with a longish reed.
+But objects which are more powerfully excited move more quickly; those
+which are less powerfully excited, more feebly, and not unless brought
+rather close; the experiment is made on water with equal corks.
+
+       *       *       *       *       *
+
+
+{151} [Illustration]
+
+BOOK FOURTH.
+
+_CHAP. I._
+
+ON VARIATION.
+
+Direction has hitherto been spoken of as if in nature there were no
+variation; for in the preceding natural history we wished to omit and
+neglect this, inasmuch as in a terrestrial globe, perfect and in every
+sense complete, there would be none. Since, however, in fact, the earth's
+magnetick direction, owing to some fault and slip, deviates from its right
+course and from the meridian, we must extract and demonstrate the obscure
+and hidden cause of that variance which has troubled and sore racked in
+vain the minds of many. Those who before us have written on the magnetick
+movements have made no distinction between direction and variation, but
+consider the motion of magnetick iron to be uniform and simple. Now true
+direction is the motion of the magnetick body to the true meridian and its
+continuance therein with its appropriate ends towards the poles. But it
+very often happens at sea and on land that the magnetick iron does not
+point to the true pole, and that not only a versorium and magnetick pieces
+of iron, and the needle of a compass, or a mariners' compass, but also a
+terrella in its boat, as well as * iron ore, iron stones, and magnetick
+earths, properly prepared, are drawn aside and deviate towards some point
+of the Horizon very near to the meridian. For they with their poles
+frequently face termini away from the meridian. This variation {152}
+(observed by means of instruments or a nautical variation compass) is
+therefore the arc of the horizon between the common point of intersecion of
+it with the true meridian, and the terminus of the deflecion on the horizon
+or projection of the deviating needle. That arc varies and differs with
+change of locality. To the terminus of the variation is commonly assigned a
+great circle, called the circle of variation, and also a magnetick meridian
+passing through the zenith and the point of variation on the horizon. In
+the northern regions of the earth this variation is either from the north
+toward the east or from the north toward the west: similarly in the
+southern regions it is from the south toward the east or toward the west.
+Wherefore one should observe in the northern regions of the earth * that
+end of the versorium or compass which turns toward the North; but in the
+southern regions the other end looking to the south--which seamen and
+sciolists for the most part do not understand, for in both regions they
+observe only the boreal lily of the compass (that which faces North). We
+have before said that all the motions of the magnet and iron, all its
+turning, its inclination, and its settlement, proceed from bodies
+themselves magnetical and from their common mother the earth, which is the
+source, the propagatrix, and the origin of all these qualities and
+properties. Accordingly the earth is the cause of this variation and
+inclination toward a different point of the horizon: but how and by what
+powers must be more fully investigated. And here we must at the outset
+reject that common opinion of recent writers concerning magnetick
+mountains, or any magnetick rock, or any phantasmal pole distant from the
+pole of the earth, by which the motion of the compass or versorium is
+controlled. This opinion, previously invented by others, Fracastorio
+himself adopted and developed; but it is entirely at variance with
+experience. For in that case in different places at sea and on land the
+point of variation would change toward the east or west in proportion and
+geometrical symmetry, and the versorium would always respect the magnetick
+pole: but experience teaches that there is no such definite pole or fixed
+terminus on the earth to account for the variation. For the arcs of *
+variation are changed variously and erratically, not only on different
+meridians but on the same meridian; and when, according to this opinion of
+the moderns, the deviation should be more and more toward the east, then
+suddenly, with a small change of locality, the deviation is from the north
+toward the west as in the northern regions near Nova Zembla. Moreover, in
+the southern regions, and at sea at a great distance from the aequator
+towards the antarctick pole, there are frequent and great variations, and
+not only in the northern regions, from the magnetick mountains. But the
+cogitations of others are still more vain and trifling, such as that of
+Cortes about a moving influence beyond all the heavens; that of {153}
+Marsilius Ficinus about a star in the Bear; that of Peter Peregrinus about
+the pole of the world; that of Cardan, who derives it from the rising of a
+star in the tail of the Bear[218]; of Bessardus, the Frenchman, from the
+pole of the Zodiack; that of Livio Sanuto from some magnetick meridian;
+that of Franciscus Maurolycus from a magnetical island; that of Scaliger
+from the heavens and mountains; that of Robert Norman, the Englishman, from
+a point respective. Leaving therefore these opinions, which are at variance
+with common experience or by no means proved, let us seek the true cause of
+the variation. The great magnet or terrestrial globe directs iron (as I
+have said) toward the north and south; and excited iron quickly settles
+itself toward those termini. Since, however, the globe of the earth is
+defective and uneven on its surface and marred by its diverse composition,
+and since it has parts very high and convex (to the height of some miles),
+and those uniform neither in composition nor body, but opposite and
+dissimilar: it comes to pass that the whole of that force of the earth
+diverts magnetical bodies in its periphery toward the stronger and more
+prominent connected magnetick parts. Hence on the outermost surface of the
+earth magnetical bodies are slightly perverted from the true meridian.
+Moreover, since the surface of the globe is divided into high lands and
+deep seas, into great continental lands, into ocean and vastest seas, and
+since the force of all magnetical motions is derived from the constant and
+magnetick terrestrial nature which is more prevalent on the greater
+continent and not in the aquaeous or fluid or unstable part; [219]it
+follows that in certain parts there would be a magnetick inclination from
+the true pole east or west away from any meridian (whether passing through
+seas or islands) toward a great land or continent rising higher, that is,
+obviously toward a stronger and more elevated magnetick part of the
+terrestrial globe. For since the diameter of the earth is more than 1,700
+German miles, those large lands can rise from the centre of the earth more
+than four miles above the depth of the ocean bottom, and yet the earth will
+retain the form of a globe although somewhat uneven at the top. Wherefore a
+magnetical body is turned aside, so far as the true verticity, when
+disturbed, admits, and departs from its right (the whole earth moving it)
+toward a vast prominent mass of land as though toward what is stronger. But
+the variation does really take place, not so much because of the more
+prominent and imperfect terrestrial parts and continent lands as because of
+the inaequality of the magnetick globe, and because of the real earth,
+which stands out more under the continent lands than under the depths of
+the seas. We must see, therefore, how the _apodixis_ of this theory can be
+sustained by more definite observations. Since throughout all the course
+from the coast of Guinea to Cape Verde, the Canary Isles, and the border of
+the kingdom of Morocco, and {154} thence along the coasts of Spain, France,
+England, Belgium, Germany, Denmark, and Norway, there lie on the right hand
+and toward the east a continent and extensive connected regions, and on the
+left extensive seas and a vast ocean lie open far and wide, it is consonant
+with the theory (as has been carefully observed by many) that magnetical
+bodies should turn slightly to the East from the true pole toward the
+stronger and more remarkable elevations of the earth. But it is far
+otherwise on the eastern shores of northern America; for from Florida by
+Virginia and Norumbega to Cape Race and away to the north the versorium is
+turned toward the west. But in the middle spaces, so to speak, as in the
+more westerly Azores, it looks toward the true pole. That any magnetick
+body turns itself similarly to the same regions of the earth is not,
+however, because of that meridian or because of the concordancy of the
+meridian with any magnetick pole, as the crowd of philosophizers reckon,
+for it is not so throughout the whole of that meridian. For on the same
+meridian * near Brazil something very different occurs, as we will show
+further on. The variation (caeteris paribus) is always less near the
+aequator, greater in higher latitudes, with the limitation that it be not
+very near the pole itself. Hence the variation is greater on the coast of *
+Norway and Belgium than on the coast of Morocco or Guinea: greater also
+near Cape Race than in the harbours of Norumbega or of Virginia. On the
+coast of Guinea magnetick implements deviate by a third part of one rumbe
+to the East: in Cape Verde Islands by a half: on the coast of Morocco by
+two thirds: in England at the mouth of the Thames by a whole rumbe: and at
+London by nearly eleven degrees and one third. For indeed the moving
+magnetick virtue is stronger in a higher latitude; and the larger regions
+extending toward the poles dominate the more, as is easily apparent
+anywhere on a terrella. For as in the case of true Direction magnetick
+bodies tend toward the pole (namely, toward the stronger end, the whole
+earth causing the motion), so also do they incline a little toward the
+stronger and higher parts by the action of the whole along with the
+conjoint action of iron bodies.
+
+       *       *       *       *       *
+
+
+{155} CHAP. II.
+
+That the variation is caused by the inaequality of the
+_projecting parts of the earth_.
+
+Demonstration of this may manifestly be made [Illustration] * by means of a
+terrella in the following way: let there be a round loadstone somewhat
+imperfect in some part, and impaired by decay (such an one we had with a
+certain part corroded to resemble the Atlantick or great Ocean): place upon
+it some fine iron wire of the length of two barleycorns, as in the
+following figure. A B, a Terrella in certain parts somewhat imperfect and
+of unaequal virtue on the circumference. The versoria E, F, do not vary,
+but look directly to the pole A; for they are placed in the middle of the
+firm and sound part of the terrella and somewhat distant from the imperfect
+part: that part of the surface which is distinguished by dots and
+transverse lines is the weaker. The versorium O also does not vary (because
+it is placed in the middle of the imperfect part), but is directed toward
+the pole, {156} just as near the western Azores on the earth. The versoria
+H and L do vary, for they incline toward the sounder parts very near them.
+As this is manifest in a terrella whose surface is sensibly rather
+imperfect, so also is it in others whole and perfect, when often one part
+of the stone has stronger external parts, which nevertheless do not
+disclose themselves manifestly to the senses. In such a terrella the
+demonstration of the variation and the discovery of the stronger parts is
+on this wise. [Illustration] * Let A be the pole, B the place of the
+variation, C the stronger regions; then the horizontal versorium at B
+varies from the pole A toward C: so that both the variation is shown and
+the stronger places of the loadstone recognized. The stronger surface is
+also found by a fine iron wire of the length of two barleycorns: for since
+at the pole of the terrella it rears up perpendicularly, but in other
+places inclines toward the aequator, if in one and the same parallel circle
+it should be more erect in one place than in another; where the wire is
+raised more upright, there the part and surface of the terrella is
+stronger. Also when the iron wire placed over the pole inclines more to one
+part than to another. [Illustration] * {157} Let the experiment be made by
+means of a fine iron wire of three digits length placed over the pole A, so
+that its middle lies over the pole. Then one end is turned away from B
+toward C, and is not willing to lie quietly toward B; but on a terrella
+which is perfect[220] all round and even it rests on the pole directed
+toward any point of the aequator you please. Otherwise, let there be two *
+[Illustration] meridians meeting in the poles A B, let iron wires be reared
+just at the ends D and C of the equal arcs D A and C A; then the wire at D
+(the stronger region) will be more raised up than that at C, the weaker.
+And thus the sounder and stronger part of the loadstone is recognized,
+which otherwise would not be perceived by the touch. In a terrella which is
+perfect, and even, and similar in all its parts, there is, at equal
+distances from the pole, no variation[221]. Variation is shown by means of
+a terrella, a considerable part of which, forming a surface a little higher
+than the rest, does, although it be not decayed and broken, allure the
+versorium from the true * direction (the whole terrella co-operating).
+
+A terrella uneven in surface.
+
+[Illustration] {158} It is shown by a small spike placed over a terrella or
+by a small versorium; for they are turned by the terrella toward the mass
+that stands out and toward the large eminences. In the same way on the
+earth the verticity is perturbed by great continents, which are mostly
+elevated above the depths of the seas and make the versorium deviate
+sometimes from the right tracks (that is, from the true meridians). On a
+terrella it is thus demonstrated: the end of the versorium A is not
+directed straight to the pole P, if there be a large protuberance B on the
+terrella; so also the cusp C deviates from the pole because of the eminence
+F. In the middle between the two eminences the versorium G collimates to
+the true pole because, being at equal distances from the two eminences B
+and F, it turns aside to neither, but observes the true meridian,
+especially when the protuberances are of equal vigour. But the versorium N
+on the other side varies from the pole M toward the eminences H, and is not
+held back, stopped, or restrained by the small eminence O on the terrella
+(as it were, some island of land in the ocean). L, however, being
+unimpeded, is directed to the pole M. The variation is demonstrated in
+another way on a terrella, just as on the earth. Let A be the pole of the
+earth, B the equator, C the parallel circle of latitude of 30 degrees, D a
+great eminence spread out toward the pole, E another eminence spread out
+from the pole toward the aequator. It is manifest that in the middle of D
+the versorium F {159} does not vary; while G is very greatly deflected: but
+H very little, because it is further removed from D. Similarly also the
+versorium I placed directly toward E does not deviate from the pole: but L
+and M turn themselves away from the pole A toward the eminence E.
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+CHAP. III.
+
+The variation in any one place
+_is constant_.
+
+[Illustration]
+
+Vnless there should be a great dissolution of a continent and a subsidence
+of the land such as there was of the region Atlantis of which Plato and the
+ancients tell, the variation will continue perpetually immutable; the arc
+of the variation remains the same in the same place or region, whether it
+be at sea or on land, as in times past a magnetick body has declined toward
+the East or the West. The constancy of the variation and the pointing of
+the versorium to a definite point on the horizon in individual regions is
+demonstrated by a small versorium placed over a terrella the surface of
+which is uneven: for it always deviates from the meridian by an equal arc.
+It is also shown by the inclination of a versorium toward a second magnet;
+although in reality it is by the turning power of the whole, whether in the
+earth or in a terrella. Place upon a plane a versorium whose cusp is
+directed toward the north A: place beside it a loadstone, B, at such a
+distance that the versorium may turn aside toward B to the point C, and not
+beyond. Then move the needle of the versorium as often as you will (the box
+and the loadstone not being moved), and it will certainly always return to
+the point C. In the same manner, if you {160} placed the stone so that it
+may be truly directed toward E, the cusp always reverts to E, and not to
+any other point of the compass. Accordingly, from the position of the land
+and from the distinctive nature of the highest parts of the earth (certain
+terrene and more magnetick eminences of the regions prevailing), the
+variation indeed becomes definite in one and the same place, but diverse
+and unaequal from a change of place, since the true and polar direction
+originating in the whole terrestrial globe is diverted somewhat toward
+certain stronger eminences on the broken surface.
+
+       *       *       *       *       *
+
+
+CHAP. IIII.
+
+The arc of variation is not changed equally
+_in proportion to the distance of places_.
+
+In the open sea, when a vessel is borne by a favourable wind along the same
+parallel, if the variation be changed by one degree in the course of one
+hundred miles, the next hundred miles do not therefore lessen it by another
+degree; for the magnetick [needle] varies erratically as respects position,
+form, and vigour of the land, and also because of the distance. As, for
+example, when a course from the Scilly Isles to Newfoundland has proceeded
+so far that the compass is directed to the true pole, then, as the vessel
+proceeds, in the first part of the course the variation increases toward
+the north-west[222], but rather indistinctly and with small difference:
+thence, after an equal distance, the arc is increased in a greater
+proportion until the vessel is not far from the continent: for then it
+varies most of all. But before it touches actual land or enters port, then
+at a certain distance the arc is again slightly diminished. But if the
+vessel in its course should decline greatly from that parallel either
+toward the south or the north, the magnetick [needle] will vary more or
+less, according to the position of the land and the latitude * of the
+region. For (caeteris paribus) the greater the latitude the greater the
+variation.
+
+       *       *       *       *       *
+
+
+{161} CHAP. V.
+
+An island in Ocean does not change the variation[223], as
+_neither do mines of loadstone_.
+
+Islands, although they be more magnetick than the sea, yet do not change
+the magnetick directions or variations. For since direction is a motion
+derived from the power of the whole earth, not from the attraction of any
+hill but from the disposing and turning power of the whole; so variation
+(which is a perturbation of the direction) is an aberration of the real
+turning power arising from the great inequalities of the earth, in
+consequence of which it, of itself, slightly diverts movable magneticks
+toward those which are the largest and the more powerful. The cause now
+shown may suffice to explain that which some so wonder at about the Island
+of Elba (and although this is productive of loadstone, yet the versorium
+(or mariners' compass) makes no special inclination toward it whenever
+vessels approach it in the Tyrrhenian sea); and the following causes are
+also to be considered, viz.: that the virtue of smaller magnetick bodies
+extends scarcely or not at all of itself beyond their own mines: for
+variation does not occur because of attraction, as they would have it who
+have imagined magnetick poles. Besides, magnetick mines are only agnate to
+the true earth, not innate: hence the whole globe does not regard them, and
+magneticks are not borne to them, as is demonstrated by the diagram of
+eminences.
+
+       *       *       *       *       *
+
+
+CHAP. VI.
+
+That 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_.
+
+Owing to the loadstone being supposed (amongst the crowd of philosophizers)
+to seize and drag, as it were, magnetick bodies; and since, in truth,
+sciolists have remarked no other forces than those so oft besung of
+attractive ones, they therefore deem every motion toward the north and
+south to be caused by some alluring and inviting quality. But the
+Englishman, {162} Robert Norman, first strove to show that it is not caused
+by attraction: wherefore, as if tending toward hidden principles, he
+imagined a _point respective_[224], toward which the iron touched by a
+loadstone would ever turn, not a _point attractive_; but in this he erred
+greatly, although he effaced the former error about attraction. He,
+however, demonstrates his opinion in this way:
+
+[Illustration]
+
+Let there be a round vessel filled with water: in the middle of the surface
+of the water place a slender iron wire on a perfectly round cork, so that
+it may just float in aequilibrium on the water; let the wire be previously
+touched by a magnet, so that it may more readily show the point of
+variation, the point D as it were: and let it remain on the surface for
+some time. It is demonstrable that the wire together with the cork is not
+moved to the side D of the vessel: which it would do if an attraction came
+to the iron wire by D: and the cork would be moved out of its place. This
+assertion of the Englishman, Robert Norman, is plausible and appears to do
+away with attraction because the iron remains on the water not moving
+about, as well in a direction toward the pole itself (if the direction be
+true) as in a variation or altered direction; and it is moved about its own
+centre without any transference to the edge of the vessel. But direction
+does not arise from attraction, but from the disposing and turning power
+which exists in the whole earth, not in the pole or in some other
+attracting part of the stone, or in any mass rising above the periphery of
+the true circle so that a [Illustration] variation should occur because of
+the attraction of that mass. Moreover, it is the directing power of the
+loadstone and iron and its natural power of turning around the centre which
+cause the motion of direction, and of conformation, in which is included
+also the motion of the dip. And the terrestrial pole does not attract as if
+the terrene force were implanted only in the pole, for the magnetick force
+exists in the whole, although it predominates and excels at the pole.
+Wherefore that the cork should rest quiescent in the middle and that the
+iron excited by a loadstone should not be moved toward the side of the
+vessel are agreeable to and in conformity {163} with the magnetick nature,
+as is demonstrated by a terrella: for an iron spike placed on the stone at
+C clings on at C, and is not pulled * further away by the pole A, or by the
+parts near the pole: hence it persists at D, and takes a direction toward
+the pole A; nevertheless it clings on at D and dips also at D in virtue of
+that turning power by which it conforms itself to the terrella: of which we
+will say more in the part _On Declination_.
+
+       *       *       *       *       *
+
+
+CHAP. VII.
+
+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_.
+
+The earth, by reason of lateral eminences of the stronger globe, diverts
+iron and loadstone by some degrees from the true pole, or true meridian.
+As, for example, with us English at London it varies eleven degrees and
+1/3: in some other places the variation is a little greater, but in no
+other region is the end of the iron ever moved aside very much more from
+the meridian. For as the iron is always directed by the true verticity of
+the earth, so the polar nature of the continent land (just as of the whole
+terrene globe) acts toward the poles: and even if that mass divert
+magnetick bodies from the meridian, yet the verticity of those lands (as
+also of the whole earth) controls and disposes them so that they do not
+turn toward the East by any greater arc. But it is not easy to determine by
+any general method how great the arc of variation is in all places, and how
+many degrees and minutes it subtends on the horizon, since it becomes
+greater or less {164} from diverse causes. For both the strength of true
+verticity of the place and of the elevated regions, as well as their
+distances from the given place and from the poles of the world, must be
+considered and compared; which indeed cannot be done exactly: nevertheless
+by our method the variation becomes so known that no grave error will
+perturb the course at sea. If the positions of the lands were uniform and
+straight along meridians, and not defective and rugged, the variations near
+lands would be simple; such as appear in the following figure.
+
+[Illustration]
+
+This is demonstrated by a long loadstone the poles of which are in the ends
+A B; let C D be the middle line and the aequinoctial, and let G H and E F
+(the lines) be for meridians on which versoria are disposed, the variations
+of which are greater at a greater distance from the aequator. But the
+inequalities of the maritime parts of the habitable earth, the enormous
+promontories, the very wide gulfs, the mountainous and more elevated
+regions, render the variations more unequal, or sudden, or more obscure;
+and, moreover, less certain and more inconstant in the higher latitude.
+
+       *       *       *       *       *
+
+
+{165} CHAP. VIII.
+
+On the construction of the common mariners'
+compass[225], and on the diversity of the compasses
+_of different nations_.
+
+In a round[226] hollow wooden bowl, all the upper part of which is closed
+with glass, a versorium is placed upon a rather long pin which is fixed in
+the middle. The covering prevents the wind, and the motion of air from any
+external cause. Through the glass everything within can be discerned. The
+versorium is circular, consisting of some light material (as card), to the
+under part of which the magnetick pieces of iron are attached. On the upper
+part 32 spaces (which are commonly called _points_) are assigned to the
+same number of mathematical intervals in the horizon or winds which are
+distinguished by certain marks and by a lily indicating the north. The bowl
+is suspended in the plane of the horizon in aequilibrium in a brass ring
+which also is itself suspended transversely in another ring within a box
+sufficiently wide with a leaden weight attached; hence it conforms to the
+plane of the horizon even though the ship be tossed to and fro by the
+waves. The iron works are either a pair with their ends united, or else a
+single one of a nearly oval shape with projecting ends, which does its work
+more certainly and more quickly. This is to be fitted to the cardboard
+circle so that the centre of the circle may be in the middle of the
+magnetick iron. But inasmuch as variation arises horizontally from the
+point of the meridian which cuts the horizon at right angles, therefore on
+account of the variation the makers in different regions and cities mark
+out the mariners' compass in different ways, and also attach in different
+ways the magnetick needles to the cardboard circle on which are placed the
+32 divisions or points. Hence there are commonly in Europe 4 different
+constructions and forms. First that of the States on the Mediterranean Sea,
+Sicily, Genoa, and the Republick of Venice. In all these the needles are
+attached under the rose or lily on the cardboard versorium, so that (where
+there is no variation) they are directed to the true north and south
+points. Wherefore the north part marked with the lily always shows exactly
+the point of variation when the apex itself of the lily on the movable
+circle, together with the ends of the magnetick wires attached below, rests
+at the point of variation. Yet another is that of Dantzig, and throughout
+the Baltic Sea, and the Belgian provinces; {166} in which the iron works
+fixed below the circle diverge from the lily 1/4 of a rumbe to the east.
+For navigation to Russia the divergency is 2/3. But the compasses which are
+made at Seville, Lisbon, Rochelle, Bordeaux, Rouen, and throughout all
+England have an interval of 1/2 a rumbe. From those differences most
+serious errors have arisen in navigation, and in the marine science. For as
+soon as the bearings of maritime places (such as promontories, havens,
+islands) have been first found by the aid of the mariners' compass, and the
+times of sea-tide or high water determined from the position of the moon
+over this or that point (as they say) of the compass, it must be further
+inquired in what region or according to the custom of what region that
+compass was made by which the bearings of those places and the times of the
+sea-tides were first observed and discovered. For one who should use the
+British compass and should follow the directions of the marine charts of
+the Mediterranean Sea would necessarily wander very much out of the
+straight course. So also he that should use the Italian compass in the
+British, German, or Baltic Sea, together with marine charts that are made
+use of in those parts, will often stray from the right way. These different
+constructions have been made on account of the dissimilar variations, so
+that they might avoid somewhat serious errors in those parts of the world.
+But Pedro Nunez seeks the meridian by the mariners' compass, or versorium
+(which the Spanish call the needle), without taking account of the
+variation: and he adduces many geometrical demonstrations which (because of
+his slight use and experience in matters magnetical) rest on utterly
+vicious foundations. In the same manner Pedro de Medina, since he did not
+admit variation, has disfigured his _Arte de Navegar_ with many errors.
+
+       *       *       *       *       *
+
+
+CHAP. IX.
+
+Whether the terrestrial longitude can be found from
+_the variation_.
+
+Grateful would be this work to seamen, and would bring the greatest advance
+to Geography. But B. Porta in chap. 38 of book 7 is mocked by a vain hope
+and fruitless opinion. For when he supposes that the magnetick needle would
+follow order and proportion in moving along meridians, so that "the neerer
+it is to the east, the more it will decline from the Meridian line, toward
+the east; and the neerer it comes to the west, the {167} point of the
+needle will decline the more to the west" (which is totally untrue), he
+thinks that he has discovered a true index of longitude. But he is
+mistaken. Nevertheless, admitting and assuming these things (as though they
+were perfectly true), he makes a large compass indicating degrees and
+minutes, by which these proportional changes of the versorium might be
+observed. But those very principles are false, and ill conceived, and very
+ill considered; for the versorium does not turn more to the east because a
+journey is made toward the east: and although the variation in the more
+westerly parts of Europe and the adjoining ocean is to the east and beyond
+the Azores is changed a little to the west, yet the variation is, in
+various ways, always uncertain, both on account of longitude and of
+latitude, and because of the approach toward extensive tracts of land, and
+also because of the form of the dominant terrestrial eminences; nor does
+it, as we have before demonstrated, follow the rule of any particular
+meridian. It is with the same vanity also that Livio Sanuto so greatly
+torments himself and his readers. As for the fact that the crowd of
+philosophizers and sailors suppose that the meridian passing through the
+Azores marks the limits of variation, so that on the other and opposite
+side of that meridian a magnetick body necessarily respects the poles
+exactly, which is also the opinion of Joannes Baptista Benedictus and of
+many other writers on navigation, it is by no means true. Stevinus (on the
+authority of Hugo Grotius) in his _Havenfinding Art_ distinguishes the
+variation according to the meridians: "It may be seene in the Table of
+variations, that in _Coruo_ the Magneticall needle pointeth due North: but
+after that, the more a man shal goe towards the East, so much the more also
+shall he see the needle varie towards the East [[Greek: anatolizein]], till
+he come one mile to the Eastward from _Plimouth_, where the variation
+comming to the greatest is 13 degr. 24 min. From hence the Northeasting
+[Anatolismus] beginneth to decrease, til you come to _Helmshude_ (which
+place is Westward from the North Cape of Finmark) where againe the needle
+pointeth due North. Now the longitude from _Coruo_ to _Helmshude_ is 60
+degr. Which things being well weighed, it appeareth that the greatest
+variation [Chalyboclysis] 13 degr. 24 minutes at _Plimmouth_ (the longitude
+whereof is 30 degr.) is in the midst betweene the places where the needle
+pointeth due North." But although this is in some part true in these
+places, yet it is by no means true that along the whole of the meridian of
+the island of Corvo the versorium looks truly to the north; nor on the
+meridian of Plymouth is the variation in other places 13 deg. 24 min.--nor
+again in other parts of the meridian of Helmshuda does it point to the true
+pole. For on the meridian passing through Plymouth in Latitude 60 degrees
+the North-easterly variation is greater: in Latitude 40 deg. much less; in
+Latitude 20 deg. very small indeed. On the meridian of Corvo, although
+there is no variation near the {168} island, yet in Latitude 55 degrees the
+variation is about 1/2 a rumbe to the North-west; in Latitude 20 deg. the
+versorium inclines 1/4 of a rumbe toward the East. Consequently the limits
+of variation are not conveniently determined by means of great circles and
+meridians, and much less are the ratios of the increment or decrement
+toward any part of the heavens properly investigated by them. Wherefore the
+rules of the abatement or augmentation of Northeasting or Northwesting, or
+of increasing or decreasing the magnetick deviation, can by no means be
+discovered by such an artifice. The rules which follow later for variation
+in southern parts of the earth investigated by the same method are
+altogether vain and absurd. They were put forth by certain Portuguese
+mariners, but they do not agree with the observations, and the observations
+themselves are admitted to be bad. But the method of haven-finding in long
+and distant voyages by carefully observed variation (such as was invented
+by Stevinus, and mentioned by Grotius) is of great moment, if only proper
+instruments are in readiness, by which the magnetick deviation can be
+ascertained with certainty at sea.
+
+       *       *       *       *       *
+
+
+CHAP. X.
+
+Why in various places near the pole the variations
+are much more ample than in a
+_lower latitude_.
+
+Variations are often slight, and generally null, when the versorium is at
+or near the earth's aequator. In a higher Latitude of 60, 70 or 80 deg.
+there are not seldom very wide variations. The cause of this is to be
+sought partly from the nature of the earth and partly from the disposition
+of the versorium. The earth turns magnetick bodies and at the aequator
+directs them strongly toward the pole: [227]at the poles there is no
+direction, but only a strong coition through the congruent poles. Direction
+is therefore weaker near the poles, because by reason of its own natural
+tendency to turn, the versorium dips very much, and is not strongly
+directed. But since the force of those elevated lands is more vigorous, for
+the virtue flows from the whole globe, and since also the causes of
+variation are nearer, therefore the versorium deflects the more from its
+true direction toward those eminences. It must also be known that the
+direction of the versorium on its pin along the plane of the Horizon is
+much stronger at the aequator than anywhere else by reason of the
+disposition of the {169} versorium; and this direction falls off with an
+increase of latitude. For on the aequator the versorium is, following its
+natural property, directed along the plane of the horizon; but in other
+places it is, contrary to its natural property, compelled into
+aequilibrium, and remains there, compelled by some external force: because
+it would, according to its natural property, dip below the horizon in
+proportion to the latitude, as we shall demonstrate in the book _On
+Declination_. Hence the direction falls off and at the pole is itself
+nothing: and for that reason a feebler direction is easily vanquished by
+the stronger causes of variation, and near the pole the versorium deflects
+the more from the meridian. It is demonstrated by means of a terrella: if
+an iron wire of two digits length be placed on its aequator, it will be
+strongly and rapidly directed toward the poles along the meridian, but more
+weakly so in the mid-intervals; while near the poles one may discern a
+precipitate variation.
+
+       *       *       *       *       *
+
+
+CHAP. XI.
+
+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_.
+
+One may very easily fall into mistakes and errors when one is searching
+into the hidden causes of things, in the absence of real experiments, and
+this is easily apparent from the crass error of Cardan; who deems himself
+to have discovered the distances of the centres of the cosmos and of the
+earth through a variation of the magnetick iron of 9 degrees. For he
+reckoned that everywhere on the earth the point of variation on the Horizon
+is always distant nine degrees from the true north, toward the east: and
+from thence he forms, by a most foolish error, his demonstrative ratio of
+the separate centres.
+
+       *       *       *       *       *
+
+
+{170} CHAP. XII.
+
+On the finding of the amount of variation: how great
+_is the arc of the Horizon from its arctick or antarctick_
+intersection of the meridian, to the point
+_respective of the magnetick needle_.
+
+Virtually the true meridian is the chief foundation of the whole matter:
+when that is accurately known, it will be easy by a mariners' compass (if
+its construction and the mode of attachment of the magnetick iron works are
+known) or by some other larger horizontal versorium to exhibit the arc of
+variation on the Horizon. By means of a sufficiently large nautical
+variation compass (two equal altitudes of the sun being observed before and
+after midday), the variation becomes known from the shadow; the altitude of
+the sun is observed either by a staff or by a rather large quadrant.
+
+On land the variation is found in another way which is easier, and because
+of the larger size of the instrument, more accurate. Let a thick squared
+board be made of some suitable wood, the surface of which is two feet in
+length and sixteen inches in width: describe upon it some semicircles as in
+the following figure, only more in number. In the centre let a brass style
+be reared perpendicularly: let there be also a movable pointer reaching
+from the centre to the outmost semicircle, and a magnetick versorium in a
+cavity covered over with glass: then let the board be exactly adjusted to
+the level of the Horizon by the plane instrument with its perpendicular;
+and turn the lily of the instrument toward the north, so that the versorium
+may rest truly over the middle line of the cavity, which looks toward the
+point of variation on on the Horizon. Then at some convenient hour in the
+morning (eight or nine for instance) observe the apex of the shadow thrown
+by the style when it reaches the nearest semicircle and mark the place of
+the apex of this shadow with chalk or ink: then bring round the movable
+index to that mark, and observe the degree on the Horizon numbered from the
+lily, which the index shows. In the afternoon see when the end of the
+shadow shall again reach the periphery of the same semicircle, and,
+bringing the index to the apex of the shadow, seek for the degree on the
+other side of the lily. From the difference of the degrees becomes known
+[Illustration] {172} the variation; the less being taken from the greater,
+half the remainder is the arc of variation. The variation is sought by many
+other instruments and methods in conjunction with a convenient mariners'
+compass; also by a globe, by numbers, and by the ratios of triangles and
+sines, when the latitude is known and one observation is made of the sun's
+altitude: but those ways and methods are of less use, for it is superfluous
+to try to find in winding and roundabout ways what can be more readily and
+as accurately found in a shorter one. For the whole art is in the proper
+use of the instruments by which the sun's place is expeditiously and
+quickly taken (since it does not remain stationary, but moves on): for
+either the hand trembles or the sight is dim, or the instrument makes an
+error. Besides, to observe the altitude on both sides of the meridian is
+just as expeditious as to observe on one side only and at the same time to
+find the elevation of the pole. And he who can take one altitude by the
+instrument can also take another; but if the one altitude be uncertain,
+then all the labour with the globe, numbers, sines and triangles is lost;
+nevertheless those exercises of ingenious mathematicians are to be
+commended. It is easy for anyone, if he stand on land, to learn the
+variation by accurate observations and suitable instruments, especially in
+a nearly upright sphere; but on the sea, on account of the motion and the
+restlessness of the waters, exact experiments in degrees and minutes cannot
+be made: and with the usual instruments scarcely within the third or even
+the halt of a rumbe, especially in a higher latitude; hence so many false
+and bad records of the observations of navigators. We have, however, taken
+care for the finding of the deviation by a sufficiently convenient and
+ready instrument, by means of the rising of certain stars, by the rising or
+setting of the sun, and in northern regions by the Pole Star: for the
+variation is learned with greater certainty even by the skilful with an
+instrument which is at once simple and less sensitive to the waves of the
+sea. Its construction is as follows.
+
+[228]Let an instrument be made of the form of a true and meridional
+mariners' compass of at least one foot in diameter (with a versorium which
+is either nude or provided with a cardboard circle): let the limb be
+divided into four quadrants, and each quadrant into 90 degrees. The movable
+compass-box (as is usual in the nautical instrument) is to be balanced
+below by a heavy weight of sixteen pounds. On the margin of the suspended
+compass-box, where opposite quadrants begin, let a half-ring rising in an
+angular frame in the middle be raised (with the feet of the half-ring fixed
+on either side in holes in the margin) so that the top of the frame may be
+perpendicular to the plane of the compass; on its top let a rule sixteen
+digits in length be fastened at its middle on a joint like a balance beam,
+so that it may move, as it were, about a central axis. At the ends of the
+rule there are small plates with holes, {173} [Illustration] {174} through
+which we can observe the sun or stars. The variation is best observed and
+expeditiously by this instrument at the equinoxes by the rising or setting
+sun. But even when the sun is in other parts of the zodiack, the deviation
+becomes known when we have the altitude of the pole: that being known, one
+can learn the amplitude on the Horizon and the distance from the true east
+both of the sun and of the following fixed stars by means of a globe, or
+tables, or an instrument. Then the variation readily becomes known by
+counting from the true east the degrees and minutes of the amplitude at
+rising. Observe the preceding star of the three in the Belt of Orion as
+soon as it appears on the horizon; direct the instrument toward it and
+observe the versorium, for since the star has its rising in the true east
+about one degree toward the south, it can be seen how much the versorium is
+distant from the meridian, account being taken of that one degree. You will
+also be able to observe the arctick pole star when it is on the meridian,
+or at its greatest distance from the meridian of about three degrees (the
+pole star is distant 2 deg. 55 min. from the pole, according to the
+observations of Tycho Brahe), and by the instrument you will learn the
+variation (if the star be not on the meridian) by adding or subtracting,
+_secundum artem_, the proper reduction [_prostaphaeresis_][229] of the
+star's distance from the meridian. You will find when the pole star is on
+the meridian by knowing the sun's place and the hour of the night: for this
+a practised observer will easily perceive without great error by the
+visible inclination of the constellation: for we do not take notice of a
+few minutes, as do some who, when they toil to track the minutes of degrees
+at sea, are in error by a nearly whole rumbe. A practised observer will, in
+the rising of sun or stars, allow something for refraction, so that he may
+be able to use a more exact calculation.
+
+Bright and conspicuous stars[230] which are
+_not far distant from the equator which it
+will be useful to observe at their rising and
+setting: the amplitude at the Horizon on
+rising being known from the altitude of the
+pole and from the declination of the stars, by
+means of a globe, or tables, or an instrument
+whence the variation is perceived by
+technical calculation._
+
+{175}
+
+                                 _Right Ascension_   _Declination_
+  |Oculus Tauri                 |     62deg  55'   | 15deg  53' N |
+  |Sinister humerus Orionis     |     72deg  24'   |  4deg   5' N |
+  |Dexter humerus Orionis       |     83deg  30'   |  6deg  19' N |
+  |Praecedens in cingulo Orionis|     77deg  46'   |  1deg  16' S |
+  |Canis major                  |     97deg  10'   | 15deg  55' S |
+  |Canis minor                  |    109deg  41'   |  5deg  55' N |
+  |Lucida Hydrae                |    137deg  10'   |  5deg   3' S |
+  |Caput Geminorum australe     |    110deg  21'   | 28deg  30' N |
+  |Caput boreale                |    107deg   4'   | 32deg  10' N |
+  |Cor Leonis                   |    146deg   8'   | 13deg  47' N |
+  |Cauda Leonis                 |    171deg  38'   | 16deg  30' N |
+  |Spica Virginis               |    195deg  44'   |  8deg  34' S |
+  |Arcturus                     |     29deg  13'   | 21deg  54' N |
+  |Cor Aquilae                  |    291deg  56'   |  7deg  35' N |
+
+_An instrument for finding the amplitude at rising on the horizon._
+
+Describe the circumference of a circle and let it be divided into quadrants
+by two diameters intersecting each other at right angles at its centre. One
+of these will represent the aequinoctial circle, the other the axis of the
+world. Let each of these quadrants be divided (in the accustomed way) into
+90 degrees; on every fifth or tenth of which at each end of each diameter
+and on each side let marks (showing the numbers) be inscribed on the two
+limbs or margins made for that purpose outside the circumference. Then from
+each degree straight lines are drawn parallel to the aequator. You will
+then prepare a rule or alhidade equal to the diameter of that circle and
+divided throughout into the same parts into which the diameter of the
+circle representing the axis of the world is divided. Let there be left a
+small appendage attached to the middle of the rule, by which the middle of
+the fiducial line itself of the rule may be connected with the centre of
+the circle: but to every fifth or tenth part of that rule let numbers be
+attached proceeding from the centre toward each side. This circle
+represents the plane of the meridian; its centre the actual point of east
+or west, _i.e._, the common intersection of the horizon and aequator; all
+those lines aequidistant from the aequator denote the parallels of the sun
+and stars; the fiducial line of the rule or alhidade represents the
+horizon; and its parts signify the degrees of the horizon, beginning from
+the point of setting or of rising. {176}
+
+[Illustration]
+
+Therefore if the fiducial line of the rule be applied to the given latitude
+of the place reckoned from either end of that diameter which represents the
+axis of the world; and if further the given declination of the sun or of
+some star from the aequator (less than the complement of the latitude of
+the place) be found on the limb of the instrument; then the intersection of
+the parallel drawn from that point of the declination with the horizon, or
+with the fiducial line of the rule or alhidade, will indicate for the given
+latitude of the place the amplitude at rising of the given star or the sun.
+
+       *       *       *       *       *
+
+
+{177} CHAP. XIII.
+
+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_.
+
+After the variation of the compass had first been noticed, some more
+diligent navigators took pains to investigate in various ways the
+difference of aspect of the mariners' compass. Yet, to the great detriment
+of the nautical art, this has not been done so exactly as it ought to have
+been. For either being somewhat ignorant they have not understood any
+accurate method or they have used bad and absurd instruments, or else they
+merely follow some conjecture arising from an ill-formed opinion as to some
+prime meridian or magnetick pole; whilst others again transcribe from
+others, and parade these observations as their own; and they who, very
+unskilful themselves, first of all committed their observations to writing
+are, as by the prerogative of time, held in esteem by others, and their
+posterity does not think it safe to differ from them. Hence in long
+navigations, especially to the East Indies, the records by the Portuguese
+of the deviating compass are seen to be unskilful: for whoever reads their
+writings will easily understand that they are in error in very many things,
+and do not rightly understand the construction of the Portuguese compass
+(the lily of which diverges by half a rumbe from the needles toward the
+west), nor its use in taking the variation. Hence, while they show the
+variation of the compass in different places, it is uncertain whether they
+measure the deviation by a true meridional compass or by some other whose
+needles are displaced from the lily. The Portuguese (as is patent in their
+writings) make use of the Portuguese compass, whose magnetick needles are
+fixed aside from the lily by half of one rumbe toward the east. Moreover on
+the sea the observation of the variation is a matter of great difficulty,
+on account of the motion of the ship and the uncertainty of the deviation,
+even with the more skilful observers, if they use the best made instruments
+hitherto known and used. Hence there arise different opinions concerning
+the magnetick deviation: as, for instance, near the Island of St. Helena
+the Portuguese Rodriguez de {178} Lagos measures half a rumbe. The Dutch in
+their nautical log fix it at a whole rumbe. Kendall, the expert Englishman,
+with a true meridional compass admits only a sixth part of a rumbe. A
+little to the East of Cape Agullias Diego Alfonso makes no variation, and
+shows by an Astrolabe that the compass remains in the true meridian.
+Rodriguez shows that the compass at Cape Agulhas has no variation if it is
+of Portuguese construction, in which the needles are inclined half a rumbe
+to the East. And there is the same confusion, negligence, and vanity in
+very many other instances.
+
+       *       *       *       *       *
+
+
+CHAP. XIIII.
+
+On the variation under the aequinoctial line,
+_and near it_.
+
+In the North the magnetick needle varies because of the Boreal eminences of
+the continent; in the South because of the Austral; at the aequator, if the
+regions on both sides were equal, there would be no variation. But because
+this rarely happens some variation is often observed under the aequator;
+and even at some distance from the aequator of three or 4 degrees toward
+the North, there may be a variation arising from the south, if those very
+wide and influential southern continents be somewhat near on one side.
+
+       *       *       *       *       *
+
+
+CHAP. XV.
+
+The variation of the magnetick needle in the great
+Aethiopick and American sea, beyond
+_the aequator_.
+
+Discourse hath already been had of the mode and reason of the variation in
+the great Atlantick Ocean: but when one has advanced beyond the aequator
+off the east coast of Brazil the magnetick needle turns aside toward the
+mainland, namely, with that end of it which points to the south; so that
+with that end of the versorium it deviates from the true meridian toward
+the west; which navigators observe at the other end and suppose a variation
+to occur toward the east. But throughout the whole way from the first
+promontory on the east of Brazil, by {179} Cape St. Augustine and thence to
+Cape Frio, and further still to the mouth of the Strait of Magellan, the
+variation is always from the south toward the west with that end of the
+versorium which tends toward the antarctick pole. For it is always with the
+accordant end that it turns toward a continent. The variation, however,
+occurs not only on the coast itself, but at some distance from land, such
+as a space of fifty or sixty German miles or even more. But when at length
+one has progressed far from land, then the arc begins to diminish: for the
+magnetick needle turns aside the less toward what is too far off, and is
+turned aside the less from what is present and at hand, since it enjoys
+what is present. In the Island of St. Helena (the longitude of which is
+less than is commonly marked on charts and globes) the versorium varies by
+one degree or nearly two. The Portuguese and others taught by them, who
+navigate beyond the Cape of Good Hope to the Indies, set a course toward
+the Islands of Tristan d'Acunha, in order that they may enjoy more
+favourable winds; in the former part of their course the change of
+variation is not great; but after they have approached the islands the
+variation increases; and close to the islands it is greater than anywhere
+else in the whole course. For the end of the versorium tending to the south
+(in which lies the greatest source of the variation) is caught and allured
+toward the south-west by the great promontory of the southern land. But
+when they proceed onward toward the Cape of Good Hope the variation
+diminishes the more they approach it. But on the prime meridian in the
+latitude of 45 degrees, the versorium tends to the south-east: and one who
+navigates near the coast from Manicongo to the tropick, and a little
+beyond, will perceive that the versorium tends from the south to the east,
+although not much. At the promontory of Agulhas it preserves slightly the
+variation which it showed near the islands of d'Acunha, which nevertheless
+is very much diminished because of the greater remoteness from the cause of
+variation, and consequently there the southern end of the versorium does
+not yet face exactly to the pole.
+
+       *       *       *       *       *
+
+
+CHAP. XVI.
+
+On the variation in Nova Zembla.
+
+Variations in parts near the pole are greater (as has been shown before)
+and also have sudden changes, as in former years the Dutch explorers
+observed not badly, even if those observations were not exact--which indeed
+is pardonable in them; for with the usual instruments it is with difficulty
+{180} that the truth becomes known in such a high latitude (of about 80
+degrees). Now, however, from the deviation of the compass the reason for
+there being an open course to the east by the Arctick Ocean appears
+manifest; for since the versorium has so ample a variation toward the
+north-west, it is demonstrable that a continent does not extend any great
+distance in the whole of that course toward the east. Therefore with the
+greater hope can the sea be attempted and explored toward the east for a
+passage to the Moluccas by the north-east than by the north-west.
+
+       *       *       *       *       *
+
+
+CHAP. XVII.
+
+Variation in the Pacifick Ocean.
+
+Passing the Strait of Magellan the deviation on the shore of Peru is toward
+the south-east, _i.e._, from the south toward the east. And a similar
+deflection would be continued along the whole coast of Peru as far as the
+aequator. In a higher latitude up to 45 deg. the variation is greater than
+near the aequator; and the deflection toward the south-east is in nearly
+the same proportion as was the deviation from the south toward the west on
+the eastern shore of South America. From the aequator toward the North
+there is little or no variation until one comes to New Galicia; and thence
+along the whole shore as far as Quivira the inclination is from the north
+toward the east.
+
+       *       *       *       *       *
+
+
+CHAP. XVIII.
+
+On the variation in the Mediterranean Sea.
+
+Sicilian and Italian sailors think that in the Sicilian Sea and toward the
+east up to the meridian of the Peloponnesus (as Franciscus Maurolycus
+relates) the magnetick needle "graecizes," that is, turns from the pole
+toward what is called the greek wind or Boreas; that on the shore of the
+Peloponnesus it looks toward the true pole; but that when they have
+proceeded further east, then it "mistralizes," because it tends from the
+pole toward the mistral or north-west wind: which agrees with our rule for
+the variation. For as the Mediterranean Sea is extended toward the west
+from that meridian, so on the side {181} toward the east the Mediterranean
+Sea lies open as far as Palestine; as toward North and East lie open the
+whole Archipelago and the neighbouring Black Sea. From the Peloponnesus
+toward the north pole the meridian passes through the largest and most
+elevated regions of all Europe; through Achaia, Macedonia, Hungary,
+Transylvania, Lithuania, Novogardia, Corelia and Biarmia.
+
+       *       *       *       *       *
+
+
+CHAP. XIX.
+
+The variation in the interior of large
+_Continents_.
+
+Most of the great seas have great variations; in some parts, however, they
+have none, but the true directions are toward the pole. On continents,
+also, the magnetick needle often deviates from the meridian, as on the edge
+of the land and near the borders; but it is generally accustomed to deviate
+by a somewhat small arc. In the middle, however, of great regions there are
+no variations. Hence in the middle lands of Upper Europe, in the interior
+of Asia, and in the heart of Africa, of Peru, and in the regions of North
+or Mexican America, the versorium rests in the meridian.
+
+       *       *       *       *       *
+
+
+CHAP. XX.
+
+Variation in the Eastern Ocean.
+
+Variation in the Eastern Ocean throughout the whole voyage to Goa and the
+Moluccas is observed by the Portuguese; but they err greatly in many
+things, following, as they do, the first observers who note down variations
+in certain places with ill-adapted instruments, and by no means accurate
+observations, or by some conjectures. As, for instance, in Brandoee Island,
+they make the versorium deviate by 22 degrees to the north-west. For in no
+region or place in the whole world, of not greater latitude, is there so
+great a deviation; and, in reality, there the deviation is slight. Also
+when they make out that at Mosambique the compass deviates by one rumbe to
+the north-west, it is false; even though they use (as they are accustomed
+to do) the Portuguese compass: for beyond all doubt on the shore of {182}
+Mosambique the versorium inclines 1/4 rumbe or even more to the south-west.
+Very wrongly also beyond the aequator in the course to Goa they make the
+little compass incline by 1-1/2 rumbe to the west: whereas they should
+rather have said that in the first part of the course the Portuguese
+compass inclines by 1 rumbe: but that the true meridional compass inclines
+by 1/2 rumbe only. In order that the amount of variation in the Eastern
+Ocean may be accurately settled in most places by our rules, there is
+needed a more exact and truer survey of the southern land, which spreads
+out from the south to the aequinoctial more than is commonly described on
+maps and globes.
+
+       *       *       *       *       *
+
+
+CHAP. XXI.
+
+How the deviation of the versorium is augmented and
+_diminished by reason of the distance of places_.
+
+In the middle of great and continent lands there is no variation. Nor,
+generally, in the middle of very great seas. On the margin of those lands
+and seas the variation is often ample, yet not so great as at a little
+further distance on the sea. As, for example, near Cape St. Augustine the
+compass varies; but at 50 miles from land toward the East it varies more;
+and 80 miles off it varies still more; and yet still more at a distance of
+100 miles. But from a distance of 100 miles the diminutions of deviation
+are slower, when they are navigating toward the mainland, than at a
+distance of 80 miles, and at a distance of 80 miles than at 50: for the
+deviations change and are diminished rather more swiftly the more they
+approach and draw near land than when at a great distance off. As, for
+instance, navigating toward Newfoundland the change of variation is more
+rapid (that is, it decreases a degree in a smaller arc of the course on the
+parallel) when they are not far from land than when they are a hundred
+miles distant: but when travelling on land toward the interiors of regions
+the changes are slower in the first parts of the journey than when they
+come more into the interior.
+
+The ratio of the arcs on a parallel circle, when a versorium is moved
+toward continents which extend to the pole, corresponds with the degrees of
+variation. Let A be the pole; B the eminences of the dominant lands; at C
+there is no variation caused by B, for it is too far away; at D the
+variation is very great because the versorium is allured or turned by the
+whole earth toward the eminent {183} land B; and moreover it is not
+hindered, or restrained or brought back to the pole by the verticity of the
+earth; but, tending of its own nature to the pole, it is nevertheless
+deflected from it by reason of the site, or position, and convenient
+distance of the dominant and high lands.
+
+[Illustration]
+
+Now from C toward D the variation increases; the versorium, however, does
+not deviate so rapidly in the first spaces as near D: for more miles are
+traversed on the parallel circle C D, near C, in order that the versorium
+may deviate by one degree from the pole A, than near D. So also in order
+that the variation may be diminished from D toward E more miles are
+required near D than near E. Thus the deviations become equal in unequal
+courses, whether the variation be increasing or decreasing; and yet the
+variation decreases by lesser intervals than it increases. There intervene,
+however, many other causes which perturb this proportion.
+
+       *       *       *       *       *
+
+
+{184} [Illustration]
+
+BOOK FIFTH.
+
+_CHAP. I._
+
+ON DECLINATION.
+
+In due course we have now come to that notable experiment, and remarkable
+motion of magnetick bodies dipping below the horizon by their own rotatory
+nature; by the knowledge of which is revealed a unity, a concordancy, and a
+mutual agreement between the terrestrial globe and the loadstone (or the
+magnetick iron), which is wonderful in itself, and is made manifest by our
+teaching. This motion we have made known in many striking experiments, and
+have established its rules; and in the following pages we shall demonstrate
+the causes of it, in such a way that no sound, logical mind can ever
+rightly set at nought or disprove our chief magnetick principles.
+Direction, as also variation, is demonstrated in a horizontal plane, when a
+balanced magnetick needle comes to rest at some definite point; but
+declination is seen to be the motion of a needle, starting from that point
+of the horizon, first balanced on its own axis, then excited by a
+loadstone, one end or pole of it tending toward the centre of the earth.
+And we have found that it takes place in proportion to the latitude of each
+region. But that motion arises in truth, not from any motion from the
+horizon toward the centre of the earth, but from the turning of the whole
+magnetick body toward the whole of the earth, as we shall show hereafter.
+Nor does the iron dip from the horizontal in some oblique sphere, according
+to the number of degrees of elevation of the pole in the given region, or
+by an equal arc in the quadrant, as will appear hereafter. {185}
+
+Instrument of the Declination
+
+[Illustration]
+
+{186} Now how much it dips at every horizon may be ascertained in the first
+place by a contrivance, which, however, is not so easily made as is that in
+dials for measuring time, in which the needle turns to the points of the
+horizon, or in the mariners' compass. From a plank of wood let a smooth and
+circular instrument be prepared, at least six digits in diameter, and affix
+this to the side of a square pillar, which stands upright on a wooden base.
+Divide the periphery of this instrument into 4 quadrants: then each
+quadrant into 90 degrees. At the centre of the instrument let there be
+placed a brass peg, at the centre of the end of which let there be a small
+hollow, well polished. To this wooden instrument let a brass circle or ring
+be fixed, about two digits in width, with a thin plate or flat rod of the
+same metal, representing the horizon, fixed across it, through the middle
+of the circle. In the middle of the horizontal rod let there be another
+hollow, which shall be exactly opposite the centre of the instrument, where
+the former hollow was made. Afterward let a needle be fashioned out of
+steel, as versoria are accustomed to be made. Divide this at right angles
+by a thin iron axis (like a cross) through the very middle and centre of
+the wire and the cross-piece. Let this dipping-needle be hung (with the
+ends of the cross resting in the aforesaid holes) so that it can move
+freely and evenly on its axis in the most perfect aequilibrium, so
+accurately that it turns away from no one point or degree marked on the
+circumference more than from another, but that it can rest quite easily at
+any. Let it be fixed upright to the front part of the pillar, whilst at the
+edge of the base is a small versorium to show direction. Afterward touch
+the iron, suspended by this ingenious method, on both ends with the
+opposite ends of a loadstone, according to the scientifick method, but
+rather carefully, lest the needle be twisted in any way; for unless you
+prepare everything very skilfully and cleverly, you will secure no result.
+Then let another brass ring be prepared, a little larger, so as to contain
+the former one; and let a glass or a very thin plate of mica be fitted to
+one side of it. When this is put over the former ring, the whole space
+within remains inclosed, and the versorium is not interfered with by dust
+or winds. Dispose the instrument, thus completed, perpendicularly on its
+base, and with the small versorium horizontal, in such a way that, while
+standing perpendicularly, it may be directed toward the exact magnetical
+point respective. Then the end of the needle which looks toward the north
+dips below the horizon in northern regions, whilst in southern regions the
+end of the needle which looks toward the south tends toward the centre of
+the earth, in a certain proportion (to be explained afterward) to the
+latitude of the district in question, from the aequator on either side. The
+needle, however, must be rubbed on {187} a powerful loadstone; otherwise it
+does not dip to the true point, or else it goes past it, and does not
+always rest in it. A larger instrument may also be used, whose diameter may
+be 10 or 12 digits; but in such an instrument more care is needed to
+balance the versorium truly. Care must be taken that the needle be of
+steel; also that it be straight; likewise that both ends of the cross-piece
+be sharp and fixed at right angles to the needle, and that the cross-piece
+pass through the centre of the needle. As in other magnetical motions there
+is an exact agreement between the earth and the stone, and a correspondence
+manifestly apparent to our senses by means of our experiments; so in this
+declination there is a clear and evident concordance of the terrestrial
+globe with the loadstone. Of this motion, so important and so long unknown
+to all men, the following is the sure and true cause. A magnet-stone is
+moved and turned round until one of its poles being impelled toward the
+north comes to rest toward a definite point of the horizon. [231]This pole,
+which settles toward the north (as appears from the preceding rules and
+demonstrations), is the southern, not the boreal; though all before us
+deemed it to be the boreal, on account of its turning to that point of the
+horizon. A wire or versorium touched on this pole of the stone turns to the
+south, and is made into a boreal pole, because it was touched by the
+southern terminal of the stone. So if the cusp of a versorium be excited in
+a similar manner, it will be directed toward the southern pole of the
+earth, and will adjust itself also to it; but the cross (the other end)
+will be southern, and will turn to the north of the earth (the earth itself
+being the cause of its motion); for so direction is produced from the
+disposition of the stone or of the excited iron, and from the verticity of
+the earth. But declination takes place when a magnetick is turned round
+toward the body of the earth, with its southern end toward the north, at
+some latitude away from the aequator. For this is certain and constant,
+that exactly under the coelestial aequator, or rather over the aequator of
+the terrestrial globe, there is no declination of a loadstone or of iron;
+but in whatever way the iron has been excited or rubbed, it settles in the
+declination instrument precisely along the plane of the horizon, if it were
+properly balanced before. Now this occurs thus because, when the magnetick
+body is at an equal distance from either pole, it dips toward neither by
+its own versatory nature, but remains evenly directed to the level of the
+horizon, as if it were resting on a pin or floating free and unhindered on
+water. But when the magnetick substance is at some latitude away from the
+aequator, or when either pole of the earth is raised (I do not say raised
+above the visible horizon, as the commonly imagined pole of the revolving
+universe in the sky, but above the horizon or its centre, or its proper
+diameter, aequidistant from the plane of the visible horizon, which is the
+true elevation of the terrestrial pole), {188} [Illustration] then
+declination is apparent, and the iron inclines toward the body of the earth
+in its own meridian. Let A B, for example, be the visible horizon of a
+place; C D the horizontal through the earth, dividing it into equal parts;
+E F the axis of the earth; G the position of the place. It is manifest that
+the boreal pole E is elevated above the point C by as much as G is distant
+from the aequator. Wherefore, since at E the magnetick needle stands
+perpendicularly in its proper turning (as we have often shown before), so
+now at G there is a certain tendency to turn in proportion to the latitude
+(the magnetick dipping below the plane of the horizon), and the magnetick
+body intersects the horizon at unequal angles, and exhibits a declination
+below the horizon. For the same reason, if the declinatory needle be placed
+at G, its southern end, the one namely which is directed toward the North,
+dips below the plane of the visible horizon A B. And so there is the
+greatest difference between a right sphere[232] and a polar or parallel
+sphere, in which the pole is at the very Zenith. For in a right sphere the
+needle is parallel to the plane of the horizon; but when the coelestial
+pole is vertically overhead, or when the pole of the earth is itself the
+place of the region, then the needle is perpendicular to the horizon. This
+is shown by a round stone. Let a small dipping-needle, of two digits length
+(rubbed with a magnet), be hung in the air like a balance, and let the
+stone be carefully placed under it; and first let the terrella be at right
+angles, as in a right sphere, and as in the first figure; for so the
+magnetick needle will remain in equilibrium. But in an oblique position of
+the terrella, as in an oblique sphere, and in the second figure, the needle
+dips obliquely at one end toward the near pole, but does not rest on the
+pole, nor is its dip ruled by the pole, but by the body and mass of the
+whole; for the {189} dip in higher latitudes passes beyond the pole. But in
+the third position of the terrella the needle is perpendicular; because the
+pole of the stone is placed at the top, and the needle tending straight
+toward the body reaches to the pole. The cross in the preceding figures
+always turns toward the boreal pole of the terrella, having been touched by
+the boreal pole of the terrella; the cusp of the needle, having been
+touched by the southern pole of the stone, turns to the south. Thus one may
+see on a terrella the level, oblique, and perpendicular positions of a
+magnetick needle. *
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+CHAP. II.
+
+Diagram of declinations of the magnetick needle, when
+_excited, in the various portions of the sphere, and horizons_
+of the earth, in which there is no variation
+_of the declination_.
+
+[Illustration]
+
+{190} As aequator let A B be taken, C the north pole, D the south, E G
+dipping-needles in the northern, H F in the southern part of the earth or
+of a terrella. In the diagram before us all the cusps have been touched by
+the true Arctick pole of the terrella.
+
+Here we have the level position of the magnetick needle on the aequator of
+the earth and the stone, at A and B, and its perpendicular position at C,
+D, the poles; whilst at the places midway between, at a distance of 45
+degrees, the crosses of the needle dip toward the south, but the cusps just
+as much toward the north. Of which thing the reason will become clear from
+the demonstrations that follow.
+
+_* Diagram of the rotation and declination of a terrella_
+conforming to the globe of the earth, for a
+_latitude of 50 degrees north._
+
+[Illustration]
+
+A is the boreal pole of the earth or of a rather large terrella, B the
+southern, C a smaller terrella, E the southern pole of the smaller
+terrella, dipping in the northern regions[233]. The centre C is placed on
+the surface of the larger terrella, because the smaller terrella shows some
+variation on account of the length of the axis; inappreciable, however, on
+the earth. Just as a magnetick needle dips in a regional latitude of 50
+degrees, so also the axis of a stone (of a spherical stone, of course) is
+depressed below the horizon, and its natural austral pole falls, and its
+boreal pole is raised on the {191} south toward the Zenith. In the same way
+also a circular disc of iron behaves, which has been carefully touched at
+opposite parts on its circumference; but the magnetical experiments are
+less clear on account of the feebler forces in round pieces of iron.
+
+_Variety in the declinations of iron spikes at various latitudes of a
+terrella._
+
+[Illustration]
+
+The declination of a magnetick needle above a terrella is shown by means of
+several equal iron wires, of the length of a barleycorn, arranged along a
+meridian. The wires on the aequator are directed by the virtue of the stone
+toward the poles, and lie down upon its body along the plane of its
+horizon. The nearer they are brought to the poles, the more they are raised
+up by their versatory nature. At the poles themselves they point
+perpendicularly toward the very centre. But iron spikes, if they are of
+more than a due length, are not raised straight up except on a vigorous
+stone.
+
+       *       *       *       *       *
+
+
+CHAP. III.
+
+*
+
+An indicatory instrument, showing by the virtue of a
+_stone the degrees of declination from the horizon_
+of each several latitude.
+
+{192} [Illustration] {193} _Description of the Instrument, and its use._
+
+Take a terrella of the best strong loadstone, and homogeneous throughout,
+not weakened by decay or by a flaw in any parts; let it be of a fair size,
+so that its diameter is six or seven digits; and let it be made exactly
+spherical. Having found its poles according to the method already shown,
+mark them with an iron tool; then mark also the aequinoctial circle.
+Afterwards in a thick squared block of wood, one foot in size, make a
+hemispherical hollow, which shall hold half of the terrella, and such that
+exactly one half of the stone shall project above the face of the block.
+Divide the limb close to this cavity (a circle having been drawn round it
+for a meridian) into 4 quadrants, and each of these into 90 degrees. Let
+the terminus of the quadrants on the limb be near the centre of a quadrant
+described on the block, also divided into 90 degrees. At that centre let a
+short, slender versorium (its other end being rather sharp and elongated
+like a pointer) be placed in aequilibrio on a suitable pin. It is manifest
+that when the poles of the stone are at the starting points of the
+quadrants, then the versorium lies straight, as if in aequilibrio, over the
+terrella. But if you move the terrella, so that the pole on the left hand
+rises, then the versorium rises on the meridian in proportion to the
+latitude, and turns itself as a magnetick body; and on the quadrant
+described on the flat surface of the wood, the degree of its turning or of
+the declination is shown by the versorium. The rim of the cavity represents
+a meridional circle, to which corresponds some meridian circle of the
+terrella, since the poles on both sides are within the circumference of the
+rim itself. These things clearly always happen on the same plan on the
+earth itself when there is no variation; but when there is variation,
+either in the direction or in the declination (a disturbance, as it were,
+in the true turning, on account of causes to be explained later), then
+there is some difference. Let the quadrant be near the limb, or have its
+centre on the limb itself, and let the versorium be very short, so as not
+to touch the terrella, because with a versorium that is longer or more
+remote, there is some error; for it has a motion truly proportionate to the
+terrella only on the surface of the terrella. But if the quadrant, being
+far distant from the terrella, were moved within the orbe of virtue of the
+terrella toward the pole on some circle concentrick with the terrella, then
+the versorium would indicate the degrees of declination on the quadrant, in
+proportion to and symmetrically with that circle, not with the terrella.
+
+       *       *       *       *       *
+
+
+{194} CHAP. IIII.
+
+Concerning the length of a versorium convenient
+_for declination on a terrella_.
+
+Declination being investigated on the earth itself by means of a
+declination instrument, we may use either a short or a very long versorium,
+if only the magnetick virtue of the stone that touches it is able to
+permeate through the whole of its middle and through all its length. For
+the greatest length of a versorium has no moment or perceptible proportion
+to the earth's semi-diameter. On a terrella, however, or in a plane near a
+meridian of a terrella, a short versorium is desirable, of the length, say,
+of a barleycorn; for longer ones (because they reach further) dip and turn
+toward the body of the terrella suddenly and irregularly in the first
+degrees of declination. [Illustration] For example, as soon as the long
+versorium is moved forward from the aequator A to C, it catches on the
+stone with its cusp (as if with a long extended wing), when the cusp
+reaches to the parts about B, which produce a greater rotation than at C.
+And the extremities of longer wires also and rods turn irregularly, just as
+iron wires and balls of iron and other orbicular loadstones are likewise
+turned about irregularly by a long non-orbicular loadstone. Just so
+magneticks or iron bodies on the surface of a terrella ought not to have
+too long an axis, but a very short one; so that they may make a declination
+on the terrella truly and naturally proportionate to that on the earth. A
+long versorium also close to a terrella with difficulty stands steady in a
+horizontal direction on a right sphere, and, beginning to waver, it dips
+immediately to one side, especially the end that was touched, or (if both
+were touched) the one which felt the stone last.
+
+       *       *       *       *       *
+
+
+{195} CHAP. V.
+
+That declination does not arise from the attraction
+of the loadstone, but from a disposing and
+_rotating influence_.
+
+In the universe of nature that marvellous provision of its Maker should be
+noticed, whereby the principal bodies are restrained within certain
+habitations and fenced in, as it were (nature controlling them). For this
+reason the stars, though they move and advance, are not thrown into
+confusion. Magnetical rotations also arise from a disposing influence,
+whether in greater and dominating quantity, or in a smaller, and compliant
+quantity, even though it be very small. For the work is not accomplished by
+attraction, but by an incitation of each substance, by a motion of
+agreement toward fixed bounds, beyond which no advance is made. For if the
+versorium dipped by reason of an attractive force, then a terrella made
+from a very strong magnetick stone would cause the versorium to turn toward
+itself more than one made out of an average stone, and a piece of iron
+touched with a vigorous loadstone would dip more. This, however, never
+happens. Moreover, an iron snout placed on a meridian in any latitude does
+not raise a spike more toward the perpendicular than the stone itself,
+alone and unarmed; although when thus equipped, it plucks up and raises
+many greater weights[234]. But if a loadstone be sharper toward one pole,
+toward the other blunter, the sharp end or pole allures a magnetick needle
+more strongly, the blunt, thick end makes it rotate more strongly; but an
+orbicular stone * makes it rotate strongly and truly, in accordance with
+magnetick rules and its globular form. A long stone, on the other hand,
+extended from pole to pole, moves a versorium toward it irregularly; for in
+this case the pole of the versorium always looks down on the pole itself.
+Similarly also, if the loadstone have been made in the shape of a circle,
+and its poles are on the circumference, whilst the body of it is plane, not
+globular, if the plane be brought near a versorium, the versorium does not
+move with the regular magnetick rotation, as on a terrella; but it turns
+looking always toward the pole of the loadstone, which has its seat on the
+circumference of the plane. Moreover, if the stone caused the versorium to
+rotate by attracting it, then in the first degrees of latitude, it would
+attract the end of a short versorium toward the body itself of the
+terrella; yet it does not so attract it that they are brought into contact
+and unite; but the versorium rotates just so far as nature demands, as is
+clear from this example. {196} [Illustration] * For the cusp of a versorium
+placed in a low latitude does not touch the stone or unite with it, but
+only inclines toward it. Moreover, when a magnetick body rotates in
+dipping, the pole of the versorium is not stayed or detained by the pole of
+the earth or terrella; but it rotates regularly, and does not stop at any
+point or bound, nor point straight to the pole toward which the centre of
+the versorium is advancing, unless on the pole itself, and once only
+between the pole and the aequator; but it dips as it advances, according as
+the change of position of its centre gives a reason for its inclination in
+accordance with rules magnetical. The declination of a magnetick needle in
+water also, as demonstrated in the following pages, is a fixed
+quantity[235]; the magnetick needle does not descend to the bottom of the
+vessel, but remains steady in the middle, rotated on its centre according
+to its due amount of declination. This would not happen, if the earth or
+its poles by their attraction drew down the end of the magnetick needle, so
+that it dipped in this way.
+
+       *       *       *       *       *
+
+
+CHAP. VI.
+
+On the proportion of declination to latitude[236], and
+_the cause of it_.
+
+Concerning the making of an instrument for finding declination, the causes
+and manner of declination, and the different degrees of rotation in
+different places, the inclination of the stone, and concerning an
+instrument indicating by the influence of a stone the degree of declination
+from any horizon we have already spoken. Then we spoke about needles on the
+meridian of a stone, and their rotation shown for various latitudes by
+their rise toward the perpendicular. We must now, however, treat more fully
+of the causes of the degree of that inclination. Whilst a loadstone and a
+magnetick iron wire are moved along a meridian from the aequator toward the
+pole, they rotate toward a round loadstone, as also toward the earth with a
+circular movement. On a right horizon (just as also on the aequinoctial of
+{197} the stone) the axis of the iron, which is its centre line, is a line
+parallel to the axis of the earth. When that axis reaches the pole, which
+is the centre of the axis, it stands in the same straight line with the
+axis of the earth. The same end of the iron which at the aequator looks
+south turns to the north. For it is not a motion of centre to centre, but a
+natural turning of a magnetick body to a magnetick body, and of the axis of
+the body to the axis; it is not in consequence of the attraction of the
+pole itself that the iron points to the earth's polar point. Under the
+aequator the magnetick needle remains in aequilibrio horizontally; but
+toward the pole on either side, in every latitude from the beginning of the
+first degree right up to the ninetieth, it dips. The magnetick needle does
+not, however, in proportion to any number of degrees or any arc of latitude
+fall below the horizon just that number of degrees or a similar arc, but a
+very different one: because this motion is not really a motion of
+declination, but is in [Illustration] reality a motion of rotation, and it
+observes an arc of rotation according to the arc of latitude. Therefore a
+magnetick body A, while it is advancing over the earth itself, or a little
+earth or terrella, from the aequinoctial G toward the pole B, rotates on
+its own centre, and halfway on the progress of its centre[237] from the
+aequator to the pole B it is pointing toward the aequator at F, midway
+between the two poles. Much more quickly, therefore, must the versorium
+rotate than its centre advances, in order that by rotating it may face
+straight toward the point F. Wherefore the motion of this rotation is rapid
+in the first degrees from the aequator, namely, from A to L; but more tardy
+in the later degrees from L to B, when facing from the aequator at F to C.
+But if the declination were equal to the latitude (_i.e._, always just as
+many degrees from the horizon, as the centre of the versorium has receded
+from the aequator), then the magnetick needle would be following some
+potency and peculiar virtue of the centre, as if it {198} were a point
+operating by itself. But it pays regard to the whole, both its mass, and
+its outer limits; the forces of both uniting, as well of the magnetick
+versorium as of the earth. *
+
+       *       *       *       *       *
+
+
+CHAP. VII.
+
+Explanation of the diagram of the rotation of
+_a magnetick needle_.
+
+[Illustration]
+
+Suppose A C D L to be the body of the earth or of a terrella, its centre M,
+Aequator A D, Axis C L, A B the Horizon, which changes according to the
+place. From the point F on a Horizon distant from the aequator A by the
+length of C M, the semi-diameter of the earth or terrella, an arc is
+described to H as the limit of the quadrants of declination; for {199} all
+the quadrants of declination serving the parts from A to C begin from that
+arc, and terminate at M, the centre of the earth. The semi-diameter of this
+arc is a chord drawn from the aequator A to the pole C; and a line produced
+along the horizon from A to B, equal to that chord, gives the beginning of
+the arc of the limits of arcs of rotation and revolution, which is
+continued as far as G. For just as a quadrant of a circle about the centre
+of the earth (whose beginning is on the horizon, at a distance from the
+aequator equal to the earth's semi-diameter) is the limit of all quadrants
+of declination drawn from each several horizon to the centre; so a circle
+about the centre from B, the beginning of the first arc of rotation, to G
+is the limit of the arcs of rotation. The arcs of rotation and revolution
+of the magnetick needle are intermediate between the arcs of rotation B L
+and G L. The centre of the arc is the region itself or place in which the
+observation is being made; the beginning of the arc is taken from the
+circle which is the limit of rotations, and it stops at the opposite pole;
+as, for example, from O to L, in a latitude of 45 degrees. Let any arc of
+rotation be divided into 90 equal parts from the limit of the arcs of
+rotation toward the pole; for whatever is the degree of latitude of the
+place, the part of the arc of rotation which the magnetick pole on or near
+the terrella or the earth faces in its rotation is to be numbered similarly
+to this. The straight lines in the following larger diagram show this. The
+magnetick rotation at the middle point in a latitude of 45 degrees is
+directed toward the aequator, in which case also that arc is a quadrant of
+a circle from the limit to the pole; but previous to this all the arcs of
+rotation are greater than a quadrant, whilst after it they are smaller; in
+the former the needle rotates more quickly, but in the succeeding positions
+gradually more slowly. For each several region there is a special arc of
+rotation, in which the limit to which the needle rotates is according to
+the number of degrees of latitude of the place in question; so that a
+straight line drawn from the place to the point on that arc marked with the
+number of degrees of latitude shows the magnetick direction, and indicates
+the degree of declination at the intersection of the quadrant of
+declination which serves the given place. Take away the arc of the quadrant
+of declination drawn from the centre to the line of direction; that which
+is left is the arc of declination below the horizon. As, for example, in
+the rotation of the versorium N, whose line respective proceeds to D, from
+the quadrant of declination, S M, take away its arc R M; that which is left
+is the arc of declination: how much, that is, the needle dips in the
+latitude of 45 degrees.
+
+       *       *       *       *       *
+
+
+{200} CHAP. VIII.
+
+Diagram of the rotation of a magnetick needle,
+_indicating magnetical declination in all latitudes, and_
+from the rotation and declination, the
+_latitude itself_.
+
+In the more elaborate diagram a circle of rotations and a circle of
+declinations are adjusted to the body of the earth or terrella, with a
+first, a last, and a middle arc of rotation and declination. Now from each
+fifth division of the arc which limits all the arcs of rotation (and which
+are understood[238] as divided into 90 equal parts) arcs are drawn to the
+pole, and from every fifth degree of the arc limiting the quadrants of
+declination, quadrants are drawn to the centre; and at the same time a
+spiral line is drawn, indicating (by the help of a movable quadrant) the
+declination in every latitude. Straight lines showing the direction of the
+needle are drawn from those degrees which are marked on the meridian of the
+earth or a terrella to their proper arcs and the corresponding points on
+those arcs.
+
+To ascertain the elevation of the pole or the latitude of a place
+anywhere
+_in the world, by means of the following diagram, turned into
+a magnetick instrument, without the help of the coelestial
+bodies, sun, planets, or fixed stars, in fog
+and darkness_.
+
+[Illustration]
+
+We may see how far from unproductive magnetick philosophy is, how
+agreeable, how helpful, how divine! Sailors when tossed about on the waves
+with continuous cloudy weather, and unable by means of the coelestial
+luminaries to learn anything about the place or the region in which they
+are, with a very slight effort and with a small instrument are comforted,
+and learn the latitude of the place. With a declination instrument the
+degree of declination of the magnetick needle below the horizon is
+observed; that degree is noted on the inner arc of the quadrant, and the
+quadrant is turned round about the centre of the instrument until that
+degree on the quadrant touches the spiral line; then in the open space B at
+the centre of the quadrant the latitude of the region on {201} the
+circumference of the globe is discerned by means of the fiducial line A B.
+Let the diagram be fixed on a suitable flat board, and let the centre of
+the corner A of the quadrant be fastened to the centre of it, so that the
+quadrant may rotate on that centre. But it must be understood that there is
+also in certain places a variation in the declination on account of causes
+already mentioned (though not a large one), which it will be an assistance
+also to allow for on a likely estimate; and it will be especially helpful
+to observe this variation in various places, as it seems to present greater
+difficulty than the variation in direction; but it is easily learnt with a
+declination instrument, when it dips more or less than the line in the
+diagram.
+
+[Illustration]
+
+_To observe magnetick declination at sea_.
+
+Set upon our variation instrument a declination instrument; a wooden disc
+being placed between the round movable {202} compass and the declination
+instrument: but first remove the versorium, lest the versorium should
+interfere with the dipping needle. In this way (though the sea be rough)
+the compass box will remain upright at the level of the horizon. The stand
+of the declination instrument must be directed by means of the small
+versorium at its base, which is set to the point respective of the
+variation, on the great circle of which (commonly called the magnetick
+meridian), the plane of the upright box is arranged; thus the declinatorium
+(by its versatory nature) indicates the degree of declination.
+
+In a declination instrument the magnetick needle, which
+_in a meridional position dips, if turned
+along a parallel hangs perpendicularly._
+
+In a proper position a magnetick needle, while by its rotatory nature
+conformed to the earth, dips to some certain degree below the horizon on an
+oblique sphere. But when the plane of the instrument is moved out of the
+plane of the meridian, the magnetick needle (which tends toward the pole)
+no longer remains at the degree of its own declination, but inclines more
+toward the centre; for the force of direction is stronger than that of
+declination, and all power of declination is taken away, if the plane of
+the instrument is on a parallel. For then the magnetick needle, because it
+cannot maintain its due position on account of the axis being placed
+transversely, faces down perpendicularly to the earth; and it remains only
+on its own meridian, or on that which is commonly called the magnetick
+meridian.
+
+       *       *       *       *       *
+
+
+CHAP. IX.
+
+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._
+
+[Illustration]
+
+Fix a slender iron wire of three digits length through * a round cork, so
+that the cork may support the iron in water. Let this water be in a
+good-sized glass vase or bowl. Pare the round cork little by little with a
+very sharp knife (so that it may remain round), until it will stay
+motionless one or two digits below the face of the water; and let the wire
+be evenly balanced. {203} [239]Rub one end of the wire thus prepared on the
+boreal end of a loadstone and the other on the southern part of the stone
+(very skilfully, so that the cork may not be moved ever so little from its
+place) and again place it in the water; then the wire will dip with a
+circular motion on its own centre below the plane of the horizon, in
+proportion to the latitude of the region; and, even while dipping, will
+also show the point of variation (the true direction being perturbed). Let
+the loadstone (that with which the iron is rubbed) be a strong one, such as
+is needed in all experiments on magnetick declination. When the iron, thus
+put into the water and prepared by means of the loadstone, has settled in
+the dip, the lower end remains at the point of variation on the arc of a
+great circle or magnetick meridian passing through the Zenith or vertex,
+and the point of variation on the horizon, and the lowest point of the
+heavens, which they call the Nadir. This fact is shown by placing a rather
+long magnetick versorium on one side a little way from the vase. This is a
+demonstration of a more absolute conformity of a magnetick body with the
+earth's body as regards unity; in it is made {204} apparent, in a natural
+manner, the direction, with its variation, and the declination. But it must
+be understood that as it is a curious and difficult experiment, so it does
+not remain long in the middle of the water, but sinks at length to the
+bottom, when the cork has imbibed too much moisture.
+
+       *       *       *       *       *
+
+
+CHAP. X.
+
+On the variation of the declination.
+
+Direction has been spoken of previously, and also * variation, which is
+like a kind of dragging aside of the direction. Now in declination such
+irregular motion is also noticed, when the needle dips beyond the proper
+point or when sometimes it does not reach its mark. There is therefore a
+variation of declination, being the arc of a magnetick meridian between the
+true and apparent declination. For as, on account of terrestrial
+elevations, magnetick bodies are drawn away from the true meridian, so also
+the needle dips (its rotation being increased a little) beyond its genuine
+position. For as variation is a deviation of the direction, so also, owing
+to the same cause, there is some error of declination, though often very
+slight. Sometimes, also, when there is no variation of direction in the
+horizontal, there may nevertheless be variation of the declination; namely,
+either when more vigorous parts of the earth crop out exactly meridionally,
+_i.e._ under the very meridian; or when those parts are less powerful than
+nature in general requires; or when the virtue is too much intensified in
+one part, or weakened in another, just as one may observe in the vast
+ocean. And this discrepant nature and varying effect may be easily seen in
+certain parts of almost any round loadstone. Inaequality of power is
+recognized in any part of a terrella by trial of the demonstration in chap.
+2 of this book. But the effect is clearly demonstrated by the instrument
+for showing declination in chap. 3 of this book.
+
+       *       *       *       *       *
+
+
+{205} CHAP. XI.
+
+On the essential magnetick activity sphaerically
+_effused._
+
+Discourse hath often been held concerning the * poles of the earth and of
+the stone, and concerning the aequinoctial zone; whilst lately we have been
+speaking about the declining of magneticks toward the earth and toward the
+terrella, and the causes of it. But while by various and complicated
+devices we have laboured long and hard to arrive at the cause of this
+declination, we have by good fortune found out a new and admirable (beyond
+the marvels of all virtues magnetical) science of the orbes themselves. For
+such is the power of magnetick globes, that it is diffused and extended
+into orbes outside the body itself, the form being carried beyond the
+limits of the corporeal substance; and a mind diligently versed in this
+study of nature will find the definite causes of the motions and
+revolutions. The same powers of a terrella exist also within the whole orbe
+of its power; and these orbes at any distance from the body of the terrella
+have in themselves, in proportion to their diameter and the magnitude of
+their circumference, their own limits of influences, or points wherein
+magnetick bodies rotate; but they do not look toward the same part of the
+terrella or the same point at any distance from the same (unless they be on
+the axis of the orbes and of the terrella); but they always tend to those
+points of their own orbes, which are distant by similar arcs from the
+common axis of the orbes. As, for example, in the following diagram, we
+show the body of a terrella, with its poles and aequator; and also a
+versorium on three other concentrick orbes around the terrella at some
+distance from it. In these orbes (as in all those which we may imagine
+without end) the magnetick body or versorium conforms to its own orbe in
+which it is located, and to its diameter and poles and aequator, not to
+those of the terrella; and it is by them and according to the magnitude of
+their orbes that the magnetick body is governed, rotated, and directed, in
+any arc of that orbe, both while the centre of the magnetick body stands
+still, and also while it moves along. And yet we do not mean that the
+magnetick forms and orbes exist in air or water or in any medium that is
+not magnetical; as if the air or the water were susceptible of them, or
+were induced by them; for the forms are only effused and really subsist
+when magnetick substances are there; whence a magnetick body is laid hold
+of within the forces and limits of the orbes; and within the orbes
+magneticks {206} dispose magneticks and incite them, as if the orbes of
+virtue were solid and material loadstones. For the magnetick force does not
+pass through the whole medium or really exist as in a continuous body; so
+the orbes are magnetick, and yet not real orbes nor existent by themselves.
+
+_Diagram of motions in magnetick orbes._
+
+[Illustration]
+
+A B is the axis of the terrella and of the orbes, C D the aequator. On all
+the orbes, as on the terrella, at the equator the versorium arranges itself
+along the plane of the horizon; on the axis it everywhere looks
+perpendicularly toward the centre; in the intermediate spaces E looks
+toward D; and G looks toward H, not toward F, as the versorium L does on
+the surface of the terrella. But as is the relation of L to F on the
+surface of the terella, so is that of G to H on its orbe and of E to D on
+its orbe; also all the rotations on {207} the orbes toward the termini of
+the orbes are such as they are on the surface of the terrella, or toward
+the termini of its surface. But if in the more remote orbes this fails
+somewhat at times, it happens on account of the sluggishness of the stone,
+or on account of the feebler forces due to the too great distance of the
+orbes from the terrella.
+
+_Demonstration._
+
+Set upon the instrumental diagram described farther back [chap. 3] a plate
+or stiff circle of brass or tin, on which may be described the magnetick
+orbes, as in the diagram above; and in the middle let a hole be made
+according to the size of the terrella, so that the plate may lie evenly on
+the wood about the middle of the terrella on a meridional circle. Then let
+a small versorium of the length of a barley-corn be placed on any orbe;
+upon which, when it is moved to various positions on the same circle, it
+will always pay regard to the dimensions of that orbe, not to those of the
+stone; as is shown in the diagram of the effused magnetick forms.
+
+While some assign occult and hidden virtues of substances, others a
+property of matter, as the causes of the wonderful magnetical effects; we
+have discovered the primary substantive form of globes, not from a
+conjectural shadow of the truth of reasons variously controverted; but we
+have laid hold of the true efficient cause, as from many other
+demonstrations, so also from this most certain diagram of magnetick forces
+effused by the form. Though this (the form) has not been brought under any
+of our senses, and on that account is the less perceived by the intellect,
+it now appears manifest and conspicuous even to the eyes through this
+essential activity which proceeds from it as light from a lamp. And here it
+must be noted that a magnetick needle, moved on the top of the earth or of
+a terrella or of the effused orbes, makes two complete rotations in one
+circuit of its centre, like some epicycle about its orbit.
+
+       *       *       *       *       *
+
+
+{208} CHAP. XII.
+
+Magnetick force is animate, or imitates life; and in
+many things surpasses human life, while this is bound
+_up in the organick body_.
+
+A loadstone is a wonderful thing in very many experiments, and like a
+living creature. And one of its remarkable virtues is that which the
+ancients considered to be a living soul in the sky, in the globes and in
+the stars, in the sun and in the moon. For they suspected that such various
+motions could not arise without a divine and animate nature, immense bodies
+turned about in fixed times, and wonderful powers infused into other
+bodies; whereby the whole universe flourishes in most beautiful variety,
+through this primary form of the globes themselves. The ancients, as
+Thales, Heraclitus, Anaxagoras, Archelaus, Pythagoras, Empedocles,
+Parmenides, Plato, and all the Platonists, and not only the older Greeks,
+but the Egyptians and Chaldaeans, seek for some universal life in the
+universe, and affirm that the whole universe is endowed with life.
+Aristotle affirms that not the whole universe is animate, but only the sky;
+but he maintains that its elements are inanimate; whilst the stars
+themselves are animate. We, however, find this life in globes only and in
+their homogenic parts; and though it is not the same in all globes (for it
+is much more eminent in the sun and in certain stars than in others of less
+nobility) yet in very many the lives of the globes agree in their powers.
+For each several homogenic part draws to its own globe in a similar manner,
+and has an inclination to the common direction of the whole in the
+universe; and the effused forms extend outward in all, and are carried out
+into an orbe, and have bounds of their own; hence the order and regularity
+of the motions and rotations of all the planets, and their courses, not
+wandering away, but fixed and determined. Wherefore Aristotle concedes life
+to the sphaeres themselves and to the orbes of the heavens (which he
+feigns), because they are suitable and fitted for a circular motion and
+actions, and are carried along in fixed and definite courses. It is surely
+wonderful, why the globe of the earth alone with its emanations is
+condemned by him and his followers and cast into exile (as senseless and
+lifeless), and driven out of all the perfection of the excellent universe.
+It is treated as a small corpuscle in comparison with the whole, and in the
+numerous concourse of many thousands it is obscure, disregarded, and
+unhonoured. {209} With it also they connect the kindred elements, in a like
+unhappiness, wretched and neglected. Let this therefore be looked upon as a
+monstrosity in the Aristotelian universe, in which everything is perfect,
+vigorous, animated; whilst the earth alone, an unhappy portion, is paltry,
+imperfect, dead, inanimate, and decadent. But on the other hand Hermes,
+Zoroaster, Orpheus, recognize a universal life. We, however, consider that
+the whole universe is animated, and that all the globes, all the stars, and
+also the noble earth have been governed since the beginning by their own
+appointed souls and have the motives of self-conservation. Nor are there
+wanting, either implanted in their homogenic nature or scattered through
+their homogenic substance, organs suitable for organic activity, although
+these are not fashioned of flesh and blood as animals, or composed of
+regular limbs, which are also hardly perceptible in certain plants and
+vegetables; since regular limbs are not necessary for all life. Nor can any
+organs be discerned or imagined by us in any of the stars, the sun, or the
+planets, which are specially operative in the universe; yet they live and
+imbue with life the small particles in the prominences on the earth. If
+there be anything of which men can boast, it is in fact life, intelligence;
+for the other animals are ennobled by life; God also (by whose nod all
+things are ruled) is a living soul. Who therefore will demand organs for
+the divine intelligences, which rise superior to every combination of
+organs and are not restrained by materialized organs? But in the several
+bodies of the stars the implanted force acts otherwise than in those divine
+existences which are supernaturally ordained; and in the stars, the sources
+of things, otherwise than in animals; in animals again otherwise than in
+plants. Miserable were the condition of the stars, abject the lot of the
+earth, if that wonderful dignity of life be denied to them, which is
+conceded to worms, ants, moths, plants, and toadstools; for thus worms,
+moths, grubs would be bodies more honoured and perfect in nature; for
+without life no body is excellent, valuable, or distinguished. But since
+living bodies arise and receive life from the earth and the sun, and grass
+grows on the earth apart from any seeds thrown down (as when soil is dug up
+from deep down in the earth, and put on some very high place or on a very
+high tower, in a sunny spot, not so long after various grasses spring up
+unbidden) it is not likely that they can produce what is not in them; but
+they awaken life, and therefore they are living. Therefore the bodies of
+the globes, as important parts of the universe, in order that they might be
+independent and that they might continue in that condition, had a need for
+souls to be united with them, without which there can be neither life, nor
+primary activity, nor motion, nor coalition, nor controlling power, nor
+harmony, nor endeavour, nor sympathy; and without which there would be no
+generation {210} of anything, no alternations of the seasons, no
+propagation; but all things would be carried this way and that, and the
+whole universe would fall into wretchedest Chaos, the earth in short would
+be vacant, dead, and useless. But it is only on the superficies of the
+globes that the concourse of living and animated beings is clearly
+perceived, in the great and pleasing variety of which the great
+master-workman is well pleased. But those souls which are restrained within
+a kind of barrier and in prison cells, as it were, do not emit immaterial
+effused forms outside the limits of their bodies; and bodies are not moved
+by them without labour and waste. They are brought and carried away by a
+breath; and when this has calmed down or been suppressed by some untoward
+influence, their bodies lie like the dregs of the universe and as the
+refuse of the globes. But the globes themselves remain and continue from
+year to year, move, and advance, and complete their courses, without waste
+or weariness. The human soul uses reason, sees many things, inquires about
+many more; but even the best instructed receives by his external senses (as
+through a lattice) light and the beginnings of knowledge. Hence come so
+many errors and follies, by which our judgments and the actions of our
+lives are perverted; so that few or none order their actions rightly and
+justly. But the magnetick force of the earth and the formate life or living
+form of the globes, without perception, without error, without injury from
+ills and diseases, so present with us, has an implanted activity, vigorous
+through the whole material mass, fixed, constant, directive, executive,
+governing, consentient; by which the generation and death of all things are
+carried on upon the surface. For, without that motion, by which the daily
+revolution is performed, all earthly things around us would ever remain
+savage and neglected, and more than deserted and absolutely idle. But those
+motions in the sources of nature are not caused by thinking, by petty
+syllogisms, and theories, as human actions, which are wavering, imperfect,
+and undecided; but along with them reason, instruction, knowledge,
+discrimination have their origin, from which definite and determined
+actions arise, from the very foundations that have been laid and the very
+beginnings of the universe; which we, on account of the infirmity of our
+minds, cannot comprehend. Wherefore Thales, not without cause (as Aristotle
+relates in his book _De Anima_), held that the loadstone was animate, being
+a part and a choice offspring of its animate mother the earth.
+
+       *       *       *       *       *
+
+
+{211} [Illustration]
+
+BOOK SIXTH.
+
+_CHAP. I._
+
+ON THE GLOBE OF THE EARTH, THE
+_great magnet_.
+
+Hitherto our subject hath been the loadstone and things magnetical: how
+they conspire together, and are acted upon, how they conform themselves to
+the terrella and to the earth. Now must we consider separately the globe
+itself of the earth. Those experiments which have been proved by means of
+the terrella, how magnetick things conform themselves to the terrella, are
+all or at least the principal and most important of them, displayed by
+means of the earth's Body: And to the earth things magnetical are in all
+respects associate. First, as in the terrella the aequator, meridians,
+parallels, axis, poles are natural boundaries, as numerous experiments make
+plain: So also in the earth these boundaries are natural, not mathematical
+only (as all before us used to suppose). These boundaries the same
+experiments display and establish in both cases alike, in the earth no less
+than in the terrella. Just as on the periphery of a terrella a loadstone or
+a magnetick piece of iron is directed to its proper pole: so on the earth's
+surface are there turnings-about, peculiar, manifest, and constant on
+either side of the aequator. Iron is indued with verticity by being
+extended toward a pole of the earth, just as toward a pole of the terrella:
+By its being placed down also, and cooling toward the earth's pole after
+the pristine verticity has {212} been annulled by fire, it acquires new
+verticity, conformable to its position earthward. Iron rods also, when
+placed some considerable time toward the poles, acquire verticity merely by
+regarding the earth; just as the same rods, if placed toward the pole of a
+loadstone, even without touching it, receive polar virtue. There is no
+magnetick body that in any way runs to the terrella which does not also
+wait upon the earth. As a loadstone is stronger at one end on one side or
+other[240] of its aequator: so is the same property displayed by a small
+terrella upon the surface of a larger terrella. According to the variety
+and artistick skill in the rubbing of the magnetick iron upon the terrella,
+so do the magnetick things perform their function more efficiently or more
+feebly. In motions toward the earth's body, as toward the terrella a
+variation is displayed due to the unlikeness, inequality, and imperfection
+of its eminences: So every variation of the versorium or mariners' compass,
+everywhere by land or by sea, which thing has so sorely disturbed men's
+minds, is discerned and recognized as due to the same causes. The magnetick
+dip (which is the wonderful turning of magnetick things to the body of the
+terrella) in systematick course, is seen in clearer light to be the same
+thing upon the earth. And that single experiment, by a wonderful
+indication, as with a finger, proclaims the grand magnetick nature of the
+earth to be innate and diffused through all her inward parts. A magnetick
+vigour exists then in the earth just as in the terrella, which is a part of
+the earth, homogenic in nature with it, but rounded by Art, so as to
+correspond with the earth's globous shape and in order that in the chief
+experiments it might accord with the globe of the earth.
+
+       *       *       *       *       *
+
+
+CHAP. II.
+
+The Magnetick axis of the Earth
+_persists invariable_.
+
+As in the very first beginnings of the moving world, the earth's magnetick
+axis passed through the midst of the earth: so now it tends through the
+centre to the same points of the superficies; the circle and plane of the
+aequinoctial line also persisting. For not without the vastest overthrow of
+the terrene mass can these natural boundaries be changed, as it is easy to
+gather from magnetick demonstrations. Wherfore the opinion of Dominicus
+Maria of Ferrara, a most talented man, who was the teacher of Nicolas
+Copernicus, must be cancelled; a view {213} which, according to certain
+observations of his own, is as follows.[241] "I," he says, "in former years
+while studying Ptolemy's _Geographia_ discovered that the elevations of the
+North pole placed by him in the several regions, fall short of what they
+are in our time by one degree and ten minutes: which divergence can by no
+means be ascribed to an error of the tables: For it is not credible that
+the whole series in the book is equally wrong in the figures of the tables:
+Hence it is necessary to allow that the North pole has been tilted toward
+the vertical point. Accordingly a lengthy observation has already begun to
+disclose to us things hidden from our forefathers; not indeed through any
+sloth of theirs, but because they lacked the prolonged observation of their
+predecessors: For before Ptolemy very few places were observed with regard
+to the elevations of the pole, as he himself also bears witness at the
+beginning of his _Cosmographia_: (For, says he) Hipparchus alone hath
+handed down to us the latitudes of a few places, but a good many have noted
+those of distances; especially those which lie toward sunrise or sunset
+were received by some general tradition, not owing to any sloth on the part
+of authors themselves, but to the fact that there was as yet no practice of
+more exact mathematicks. 'Tis accordingly no wonder, if our predecessors
+did not mark this very slow motion: For in one thousand and seventy years
+it shows itself to be displaced scarce one degree toward the apex of
+dwellers upon the earth. The strait of Gibraltar shows this, where in
+Ptolemy's time the North pole appears elevated 36 degrees and a quarter
+from the Horizon: whereas now it is 37 and two-fifths. The like divergence
+is also shown at Leucopetra in Calabria, and at particular spots in Italy,
+namely those which have not changed from Ptolemy's time to our own. And so
+by reason of this movement, places now inhabited will some day become
+deserted, while those regions which are now parched at the torrid zone
+will, though long hence, be reduced to our temper of climate. Thus, as in a
+course of three hundred and ninety five thousands of years, is that very
+slow movement completed." Thus, according to these observations of
+Dominicus Maria, the North pole is at a higher elevation, and the latitudes
+of places are greater than formerly; whence he argues a change of
+latitudes. Now, however, Stadius, taking just the contrary view, proves by
+observations that the latitudes have decreased. For he says: "The latitude
+of Rome in Ptolemy's _Geographia_ is 41 degrees 2/3: and that you may not
+suppose any error of reckoning to have crept in on the part of Ptolemy, on
+the day of the Aequinox in the city of Rome, the ninth part of the gnomon
+of the sun-dial is lacking in shadow, as Pliny relates and Vitruvius
+witnesseth in his ninth book." But the observation of moderns (according to
+Erasmus Rheinholdus) gives the same in our time as 41 degrees with a sixth:
+so that you are in doubt as to half of one degree in {214} the centre of
+the world, whether you show it to have decreased by the earth's obliquity
+of motion. One may see then how from inexact observations men rashly
+conceive new and contradictory opinions and imagine absurd motions of the
+mechanism of the earth. For since Ptolemy only received certain latitudes
+from Hipparchus, and did not in very many places make the observations
+himself; it is likely that he himself, knowing the position of the places,
+formed his estimate of the latitude of cities from probable conjecture
+only, and then placed it in the maps. Thus one may see, in the case of our
+own Britain, that the latitudes of cities are wrong by two or three
+degrees, as experience teaches. Wherefore all the less should we from those
+mistakes infer a new motion, or let the noble magnetick nature of the earth
+be debased for an opinion so lightly conceived. Moreover, those mistakes
+crept the more readily into geography, from the fact that the magnetick
+virtue was utterly unknown to those geographers. Besides, observations of
+latitudes cannot be made sufficiently exactly, except by experts, using
+also finer instruments, and taking into account the refraction of the
+lights.
+
+       *       *       *       *       *
+
+
+CHAP. III.
+
+On the magnetick diurnal revolution of the Earth's
+globe, as a probable assertion against the time-honoured
+_opinion of a Primum Mobile_.
+
+Among the ancients Heraclides of Pontus and Ecphantus, afterwards the
+Pythagoreans, as Nicetas of Syracuse and Aristarchus of Samos, and some
+others (as it seems), used to think that the earth moves, and that the
+stars set by the interposition of the earth and rose by her retirement. In
+fact they set the earth moving and make her revolve around her axis from
+west to east, like a wheel turning on its axle. Philolaus the
+Pythagorean[242] would have the earth to be one of the stars, and believed
+that it turned in an oblique circle around fire, just as the sun and moon
+have their own courses. He was a distinguished mathematician, and a most
+able investigator of nature. But after Philosophy became a subject treated
+of by very many and was popularized, theories adapted to the vulgar
+intelligence or based on sophistical subtility occupied the minds of most
+men, and prevailed like a torrent, the multitude consenting. Thereupon many
+valuable discoveries of the ancients were rejected, and were dismissed to
+perish in banishment; or at least by not being further cultivated and
+developed became obsolete. So that Copernicus[243] (among later
+discoverers, a man most deserving of literary honour) is the first who
+attempted to illustrate the [Greek: phainomena] of {215} moving bodies by
+new hypotheses: and these demonstrations of reasons others either follow or
+observe in order that they may more surely discover the phaenomenal harmony
+of the movements; being men of the highest attainments in every kind of
+learning. Thus supposed and imaginary orbs of Ptolemy and others for
+finding the times and periods of the motions are not necessarily to be
+admitted to the physical inquiries of philosophers. It is then an ancient
+opinion and one that has come down from old times, but is now augmented by
+important considerations that the whole earth rotates with a daily
+revolution in the space of 24 hours. Well then, since we see the Sun and
+Moon and other planets and the glory of all the stars approach and retire
+within the space of one natural day, either the Earth herself must needs be
+set in motion with a diurnal movement from West to East, or the whole
+heaven and the rest of nature from East to West. But, in the first place,
+it is not likely that the highest heaven and all those visible splendours
+of the fixed stars are impelled along that most rapid and useless course.
+Besides, who is the Master who has ever made out that the stars which we
+call fixed are in one and the same sphere, or has established by reasoning
+that there are any real and, as it were, adamantine sphaeres? No one has
+ever proved this as a fact; nor is there a doubt but that just as the
+planets are at unequal distances from the earth, [244]so are those vast and
+multitudinous lights separated from the Earth by varying and very remote
+altitudes; they are not set in any sphaerick frame or firmament (as is
+feigned), nor in any vaulted body: accordingly the intervals of some are
+from their unfathomable distance matter of opinion rather than of
+verification; others do much exceed them and are very far remote, and these
+being located in the heaven at varying distances, either in the thinnest
+aether or in that most subtile quintessence, or in the void: how are they
+to remain in their position during such a mighty swirl of the vast orbe of
+such uncertain substance. There have been observed by astronomers 1022
+stars; besides these, numberless others are visible, some indeed faint to
+our senses, in the case of others our sense is dim and they are hardly
+perceived and only by exceptionally keen eyes, and there is no one gifted
+with excellent sight who does not when the Moon is dark and the air at its
+rarest, discern numbers and numbers dim and wavering with minute lights on
+account of the great distance: hence it is credible both that these are
+many and that they are never all included in any range of vision. How
+immeasurable then must be the space which stretches to those remotest of
+fixed stars! How vast and immense the depth of that imaginary sphere! How
+far removed from the Earth must the most widely separated stars be and at a
+distance transcending all sight, all skill and thought! How monstrous then
+such a motion {216} would be! It is evident then that all the heavenly
+bodies set as if in destined places are there formed into sphaeres, that
+they tend to their own centres, and that round them there is a confluence
+of all their parts. And if they have motion, that motion will rather be
+that of each round its own centre, as that of the Earth is; or a forward
+movement of the centre in an orbit, as that of the Moon: there would not be
+circular motion in the case of a too numerous and scattered flock. Of these
+stars some situate near the Aequator would seem to be borne around at a
+very rapid rate, others nearer the pole to have a somewhat gentler motion,
+others, apparently motionless, to have a slight rotation. Yet no
+differences in point of light, mass or colours are apparent to us: for they
+are as brilliant, clear, glittering and duskish toward the poles, as they
+are near the Aequator and the Zodiack: those which remain set in those
+positions do not hang, and are neither fixed, nor bound to anything of the
+nature of a vault. All the more insane were the circumvolution of that
+fictitious _Primum Mobile_, which is higher, deeper, and still more
+immeasurable. Moreover, this inconceivable _Primum Mobile_ ought to be
+material and of enormous depth, far surpassing all inferior nature in size:
+for nohow else could it conduct from East to West so many and such vast
+bodies of stars, and the universe even down to the Earth: and it requires
+us to accept in the government of the stars a universal power and a
+despotism perpetual and intensely irksome. That _Primum Mobile_ bears no
+visible body, is nohow recognizable, is a fiction believed in by those
+people, accepted by the weak-minded folk, who wonder more at our
+terrestrial mass than at bodies so vast, so inconceivable, and so far
+separated from us. But there can be no movement of infinity and of an
+infinite body, and therefore no diurnal revolution of that vastest _Primum
+Mobile_. The Moon being neighbour to the Earth revolves in 27 days; Mercury
+and Venus have their own moderately slow motions; Mars finishes a period in
+two years, Jupiter in twelve years, Saturn in thirty. And those also who
+ascribe a motion to the fixed stars make out that it is completed in 36,000
+years, according to Ptolemy, in 25,816 years, according to Copernicus'
+observations; so that the motion and the completion of the journey always
+become slower in the case of the greater circles. And would there then be a
+diurnal motion of that _Primum Mobile_ which is so great and beyond them
+all immense and profound? 'Tis indeed a superstition and in the view of
+philosophy a fable now only to be believed by idiots, deserving more than
+ridicule from the learned: and yet in former ages, that motion, under the
+pressure of an importunate mob of philosophizers, was actually accepted as
+a basis of computations and of motions, by mathematicians. The motions of
+the bodies (namely planets) seem to take place eastward and following the
+order of the signs. {217} The common run of mathematicians and philosophers
+also suppose that the fixed stars in the same manner advance with a very
+slow motion: and from ignorance of the truth they are forced to join to
+them a ninth sphaere. Whereas now this first and unthinkable _Primum
+Mobile_, a fiction not comprehended by any judgment, not evidenced by any
+visible constellation, but devised of imagination only and mathematical
+hypothesis, unfortunately accepted and believed by philosophers, extended
+into the heaven and beyond all the stars, must needs with a contrary
+impulse turn about from East to West, in opposition to the inclination of
+all the rest of the Universe. Whatsoever in nature is moved naturally, the
+same is set in motion both by its own forces and by the consentient compact
+of other bodies. Such is the motion of parts to their whole, of all
+interdependent sphaeres and stars in the universe: such is the circular
+impulse in the bodies of the planets, when they affect and incite one
+another's courses. But with regard to the _Primum Mobile_ and its contrary
+and exceeding rapid movement, what are the bodies which incite it or propel
+it? What is the nature that conspires with it? Or what is that mad force
+beyond the _Primum Mobile_? Since it is in bodies themselves that acting
+force resides, not in spaces or intervals. But he who thinks that those
+bodies are at leisure and keeping holiday, while all the virtue of the
+universe appertains to the very orbits and sphaeres, is on this point not
+less mad than he who, in some one else's house, thinks that the walls and
+floors and roof rule the family rather than the wife and thoughtful
+paterfamilias. Therefore not by the firmament are they borne along, or are
+moved, or have their position; much less are those confused crowds of stars
+whirled around by the _Primum Mobile_, nor are they torn away and huddled
+along by a contrary and extremely rapid movement. Ptolemy of Alexandria
+seems to be too timid and weak-minded in dreading the dissolution of this
+nether world, were the Earth to be moved round in a circle. Why does he not
+fear the ruin of the Universe, dissolution, confusion, conflagration, and
+infinite disasters celestial and super-celestial, from a motion
+transcending all thoughts, dreams, fables, and poetic licences,
+insurmountable, ineffable, and inconceivable? Wherefore we are carried
+along by a diurnal rotation of the earth (a motion for sure more
+congruous), and as a boat moves above the waters, so do we turn about with
+the earth, and yet seem to ourselves to be stationary, and at rest. Great
+and incredible it seems to some philosophers, by reason of inveterate
+prejudice, that the Earth's vast body should be swirled wholly round in the
+space of 24 hours. But it would be more incredible that the Moon should
+travel through her orbit, or complete an entire course in a space of 24
+hours; more so the Sun or Mars; still more Jupiter and Saturn; more than
+marvellous would be the velocity in the case of the {218} fixed stars and
+the firmament; what in the world they would have to wonder at in the case
+of their ninth sphere, let them imagine as they like. But to feign a
+_Primum Mobile_ and to attribute to the thing thus feigned a motion to be
+completed in the space of 24 hours, and not to allow this motion to the
+Earth in the same interval of time, is absurd. For a great circle of the
+Earth is to the ambit of the _Primum Mobile_ less than a furlong to the
+whole Earth. If the diurnal rotation of the Earth seem headlong, and not
+admissible in nature by reason of its rapidity, worse than insane will be
+the movement of the _Primum Mobile_ both for itself and the whole universe,
+agreeing as it does with no other motion in any proportion or likeness. It
+seems to Ptolemy and the Peripateticks that nature must be disordered, and
+the framework and structure of this globe of ours be dissolved, by reason
+of so swift a terrestrial revolution. The Earth's diameter is 1718 German
+miles; the greatest elongation of the new Moon is 65, the least is 55
+semi-diameters of the Earth: the greatest altitude of the half moon is 68,
+the least 52: yet it is probable that its sphaere is still larger and
+deeper. The sun in its greatest eccentricity has a distance of 1142
+semi-diameters of the Earth; Mars, Jupiter, Saturn, being slower in motion,
+are so proportionately further remote from the Earth. The distances of the
+firmament and of the fixed stars seem to the best mathematicians
+inconceivable. Leaving out the ninth sphaere, if the convexity of the
+_Primum Mobile_ be duly estimated in proportion to the rest of the
+sphaeres, the vault of the _Primum Mobile_ must in one hour run through as
+much space as is comprised in 3000 great circles of the Earth, for in the
+vault of the firmament it would complete more than 1800; but what iron
+solidity can be imagined so firm and tough as not to be disrupted and
+shattered to fragments by a fury so great and a velocity so ineffable. The
+Chaldaeans indeed would have it that the heaven consists of light. In
+light, however, there is no so-great firmness, neither is there in
+Plotinus' fiery firmament, nor in the fluid or aqueous or supremely rare
+and transparent heaven of the divine Moses, which does not cut off from our
+sight the lights of the stars. We must accordingly reject the so deep-set
+error about this so mad and furious a celestial velocity, and the forced
+retardation of the rest of the heavens. Let theologians discard and wipe
+out with sponges those old women's tales of so rapid a spinning round of
+the heavens borrowed from certain inconsiderate philosophers. The sun is
+not propelled by the sphaere of Mars (if a sphaere there be) and by his
+motion, nor Mars by Jupiter, nor Jupiter by Saturn. The sphaere, too, of
+the fixed stars, seems well enough regulated except so far as motions which
+are in the Earth are ascribed to the heavens, and bring about a certain
+change of phaenomena. The superiors do not exercise a despotism over the
+inferiors; for the heaven of {219} philosophers, as of theologians, must be
+gentle, happy, and tranquil, and not at all subject to changes: nor shall
+the force, fury, swiftness, and hurry of a _Primum Mobile_ have dominion
+over it. That fury descends through all the celestial sphaeres, and
+celestial bodies, invades the elements of our philosophers, sweeps fire
+along, rolls along the air, or at least draws the chief part of it,
+conducts the universal aether, and turns about fiery impressions (as if it
+were a solid and firm body, when in fact it is a most refined essence,
+neither resisting nor drawing), leads captive the superior. O marvellous
+constancy of the terrestrial globe, the only one unconquered; and yet one
+that is holden fast, or stationary, in its place by no bonds, no heaviness,
+by no contiguity with a grosser or firmer body, by no weights. The
+substance of the terrestrial globe withstands and sets itself against
+universal nature. Aristotle feigns for himself a system of philosophy
+founded on motions simple and compound, that the heavens revolve in a
+simple circle, its elements moving with a right motion, the parts of the
+earth seeking the earth in straight lines, falling on its surface at right
+angles, and tending together toward its centre, always, however, at rest
+therein; accordingly also the whole Earth remains immovable in its place,
+united and compacted together by its own weight. That cohaesion of parts
+and aggregation of matter exist in the Sun, in the Moon, in the planets, in
+the fixed stars, in fine in all those round bodies whose parts cohaere
+together and tend each to their own centres; otherwise the heaven would
+fall, and that sublime ordering would be lost: yet these coelestial bodies
+have a circular motion. Whence the Earth too may equally have her own
+motion: and this motion is not (as some deem it) unsuitable for the
+assembling or adverse to the generation of things. For since it is innate
+in the terrestrial globe, and natural to it; and since there is nothing
+external that can shock it, or hinder it by adverse motions, it goes round
+without any ill or danger, it advances without being forced, there is
+nothing that resists, nothing that by retiring gives way, but all is open.
+For while it revolves in a space void of bodies, or in the incorporeal
+aether, all the air, the exhalations of land and water, the clouds and
+pendent meteors, are impelled along with the globe circularly: that which
+is above the exhalations is void of bodies: the finest bodies and those
+which are least cohaerent almost void are not impeded, are not dissolved,
+while passing through it. Wherefore also the whole terrestrial globe, with
+all its adjuncts, moves bodily along, calmly, meeting no resistance.
+Wherefore empty and superstitious is the fear that some weak minds have of
+a shock of bodies (like Lucius Lactantius, who, in the fashion of the
+unlettered rabble and of the most unreasonable men scoffs at an Antipodes
+and at the sphaerick ordering of the Earth all round). So for these
+reasons, not only probable but manifest, does the diurnal rotation of the
+earth seem, {220} since nature always acts through a few rather than
+through many; and it is more agreeable to reason that the Earth's one small
+body should make a diurnal rotation, than that the whole universe should be
+whirled around. I pass over the reasons of the Earth's remaining motions,
+for at present the only question is concerning its diurnal movement,
+according to which it moves round with respect to the Sun, and creates a
+natural day (which we call a nycthemeron[245]). And indeed Nature may be
+thought to have granted a motion very suitable to the Earth's shape, which
+(being sphaerical) is revolved about the poles assigned it by Nature much
+more easily and fittingly than that the whole universe, whose limit is
+unknown and unknowable, should be whirled round; and than there could be
+imagined an orbit of the _Primum Mobile_, a thing not accepted by the
+ancients, which Aristotle even did not devise or accept as in any shape or
+form existing beyond the sphaere of the fixed stars; which finally the
+sacred scriptures do not recognize any more than they do the revolution of
+the firmament.
+
+       *       *       *       *       *
+
+
+CHAP. IIII.
+
+That the Earth moves circularly.
+
+If then the philosophers of the common sort, with an unspeakable absurdity,
+imagine the whole heaven and the vast extent of the universe to rotate in a
+whirl, it yet remains that the earth performs a diurnal change. For in no
+third way can the apparent revolutions be explained. This day, then, which
+is called natural, is a revolution of some meridian of the Earth from Sun
+to Sun. It revolves indeed in an entire course, from a fixed star round to
+that star again. Those bodies which in nature are moved with a circular,
+aequable and constant motion, are furnished, in their parts, with various
+boundaries. But the Earth is not a Chaos nor disordered mass; but by reason
+of its astral virtue, it has boundaries which subserve the circular motion,
+poles not mathematical, an aequator not devised by imagination, meridians
+also and parallels; all of which we find permanent, certain and natural in
+the Earth: which by numerous experiments the whole magnetick philosophy
+sets forth. For in the earth there are poles set in fixed bounds, and at
+them the verticity mounts up on either side from the plane of the Earth's
+aequator, with forces which are mightier and praepotent from the common
+action of the whole; and with these poles the diurnal revolution is in
+agreement. But in no turnings-about of bodies, in none of the motions of
+the planets are there to be recognized, beheld, or assured to us by any
+reasoning any sensible or natural poles in the firmament, or in any
+_Primum_ {221} _Mobile_; but those are the conception of an unsettled
+imagination. Wherefore we, following an evident, sensible and tested cause,
+do know that the earth moves on its own poles, which are apparent to us by
+many magnetick demonstrations. For not only on the ground of its constancy,
+and its sure and permanent position, is the Earth endowed with poles and
+verticity: for it might be directed toward other parts of the universe,
+toward East or West or some other region. By the wondrous wisdom then of
+the Builder forces, primarily animate, have been implanted in the Earth,
+that with determinate constancy the Earth may take its direction, and the
+poles have been placed truly opposite[246], that about them as the termini,
+as it were, of some axis, the motion of diurnal turning might be performed.
+But the constancy of the poles is regulated by the primary soul. Wherefore,
+for the Earth's good, the collimations of her verticities do not
+continually regard a definite point of the firmament and of the visible
+heaven. For changes of the aequinoxes take place from a certain deflection
+of the Earth's axis; yet in regard to that deflection, the Earth has a
+constancy of motion [Illustration] derived from her own forces. The Earth,
+that she may turn herself about in a diurnal revolution, leans on her
+poles. For since at A and B there is constant verticity, and the axis is
+straight; at C and D (the aequinoctial line) the parts are free, the whole
+forces on either side being spread out from the plane of the aequator
+toward the poles, in aether which is free from renitency, or else in a
+void; and A and B remaining constant, C revolves toward D both from innate
+conformity and aptitude, and for necessary good, and the avoidance of evil;
+but being chiefly moved forward by the diffusion of the solar orbes of
+virtues, and by their lights. And 'tis borne around, not upon a new and
+strange course, but (with the {222} tendency common to the rest of the
+planets) it tends from West to East. For all planets have a like motion
+Eastward according to the succession of the signs, whether Mercury and
+Venus revolve beneath the Sun, or around the Sun. That the Earth is capable
+of and fitted for moving circularly its parts show, which when separated
+from the whole are not only borne along with the [Illustration] straight
+movement taught by the Peripateticks, but rotate also. A loadstone fixed in
+a wooden vessel is placed on water so as to swim freely, turn itself, and
+float about. If the pole B of the loadstone be set contrary to nature
+toward the South, F, the Terrella is turned about its own centre with a
+circular motion in the plane of the Horizon, toward the North, E, where it
+rests, not at C or D. So does a small stone if only of four ounces; it has
+the same motion also and just as quick, if it were a strong magnet of one
+hundred pounds. The largest magnetical mountain will possess the same
+turning-power also, if launched in a wide river or deep sea: and yet a
+magnetick body is much more hindered by water than the whole Earth is by
+the aether. The whole Earth would do the same, if the Boreal pole were to
+be diverted from its true direction; for the Boreal pole would run back
+with the circular motion of the whole around the centre toward the
+Cynosure. But this motion by which the parts naturally settle themselves in
+their own {223} resting-places is no other than circular. The whole Earth
+regards the Cynosure with her pole according to a steadfast law of her
+nature: and thus each true part of it seeks a like resting-place in the
+world, and is moved circularly toward that position. The natural movements
+of the whole and of the parts are alike: wherefore when the parts are moved
+in a circle, the whole also has the potency of [Illustration] moving
+circularly. A sphaerical loadstone placed in a vessel on water moves
+circularly around its centre (as is manifest) in the plane of the Horizon,
+into conformity[247] with the earth.
+
+So also it would move in any other great circle if it could be free; as in
+the declination instrument, a circular motion takes place in the meridian
+(if there were no variation), or, if there should be some variation, in a
+great circle drawn from the Zenith through the point of variation on the
+horizon. And that circular motion of the magnet to its own just and natural
+position shows that the whole Earth is fitted and adapted, and is
+sufficiently furnished with peculiar forces for diurnal circular motion. I
+omit what Peter Peregrinus[248] constantly affirms, that a terrella
+suspended above its poles on a meridian moves circularly, making an entire
+revolution in 24 hours: which, however, it has not happened to ourselves as
+yet to see; and we even doubt this motion on account of the weight of the
+stone itself, as well as because the whole Earth, as she is moved of
+herself, so also is she propelled by other stars: and this does not happen
+in proportion (as it does in the terrella) {224} in every part. The Earth
+is moved by her own primary form and natural desire, for the conservation,
+perfection, and ordering of its parts, toward things more excellent: and
+this is more likely than that the fixed stars, those luminous globes, as
+well as the Wanderers, and the most glorious and divine Sun, which are in
+no way aided by the Earth, or renewed, or urged by any virtue therein,
+should circulate aimlessly around the Earth, and that the whole heavenly
+host should repeat around the Earth courses never ending and of no profit
+whatever to the stars. The Earth, then, which by some great necessity, even
+by a virtue innate, evident, and conspicuous, is turned circularly about
+the Sun, revolves; and by this motion it rejoices in the solar virtues and
+influences, and is strengthened by its own sure verticity, that it should
+not rovingly revolve over every region of the heavens. The Sun (the chief
+agent in nature) as he forwards the courses of the Wanderers, so does he
+prompt this turning about of the Earth by the diffusion of the virtues of
+his orbes, and of light. And if the Earth were not made to spin with a
+diurnal revolution, the Sun would ever hang over some determinate part with
+constant beams, and by long tarriance would scorch it, and pulverize it,
+and dissipate it, and the Earth would sustain the deepest wounds; and
+nothing good would issue forth; it would not vegetate, it would not allow
+life to animals, and mankind would perish. In other parts, all things would
+verily be frightful and stark with extreme cold; whence all high places
+would be very rough, unfruitful, inaccessible, covered with a pall of
+perpetual shades and eternal night. Since the Earth herself would not
+choose to endure this so miserable and horrid appearance on both her faces,
+she, by her magnetick astral genius, revolves in an orbit, that by a
+perpetual change of light there may be a perpetual alternation of things,
+heat and cold, risings and settings, day and night, morn and eve, noon and
+midnight. Thus the Earth seeks and re-seeks the Sun, turns away from him
+and pursues him, by her own wondrous magnetick virtue. Besides, it is not
+only from the Sun that evil would impend, if the Earth were to stay still
+and be deprived of solar benefit; but from the Moon also serious dangers
+would threaten. For we see how the ocean rises and swells beneath certain
+known positions of the Moon: And if there were not through the daily
+rotation of Earth a speedy transit of the Moon, the flowing sea would be
+driven above its level into certain regions, and many shores would be
+overwhelmed with huge waves. In order then that Earth may not perish in
+various ways, and be brought to confusion, she turns herself about by
+magnetick and primary virtue: and the like motions exist also in the rest
+of the Wanderers, urged specially by the movement and light of other
+bodies. For the Moon also turns herself about in a monthly course, to
+receive in succession the Sun's beams in which she, like the Earth, {225}
+rejoices, and is refreshed: nor could she endure them for ever on one
+particular side without great harm and sure destruction. Thus each one of
+the moving globes is for its own safety borne in an orbit either in some
+wider circle, or only by a rotation of its body, or by both together. But
+it is ridiculous for a man a philosopher to suppose that all the fixed
+stars and the planets and the still higher heavens revolve to no other
+purpose, save the advantage of the Earth. It is the Earth, then, that
+revolves, not the whole heaven, and this motion gives opportunity for the
+growth and decrease of things, and for the generating of things animate,
+and awakens internal heat for the bringing of them to birth. Whence matter
+is quickened for receiving forms; and from the primary rotation of the
+Earth natural bodies have their primary impetus and original activity. The
+motion then of the whole Earth is primary, astral, circular, around its own
+poles, whose verticity arises on both sides from the plane of the aequator,
+and whose vigour is infused into opposite termini, in order that the Earth
+may be moved by a sure rotation for its good, the Sun also and the stars
+helping its motion. But the simple straight motion downwards of the
+Peripateticks is a motion of weight, a motion of the aggregation of
+disjoined parts, in the ratio of their matter, along straight lines toward
+the body of the Earth: which lines tend the shortest way toward the centre.
+The motions of disjoined magnetical parts of the Earth, besides the motion
+of aggregation, are coition, revolution, and the direction of the parts to
+the whole, for harmony of form, and concordancy.
+
+       *       *       *       *       *
+
+
+CHAP. V.
+
+Arguments of those denying the Earth's motion, and
+_their confutation._
+
+Now it will not be superfluous to weigh well the arguments of those who say
+the Earth does not move; that we may be better able to satisfy the crowd of
+philosophizers who assert that this constancy and stability of the Earth is
+confirmed by the most convincing arguments. Aristotle does not allow that
+the Earth moves circularly, on the ground that each several part of it
+would be affected by this particular motion; that whereas now all the
+separate parts of the Earth are borne toward the middle in straight lines,
+that circular motion would be violent, and strange to nature, and not
+enduring. But it has been before proved that all actual portions of the
+Earth move in a circle, and that all magnetick bodies (fitly disposed) are
+borne around in an orbe. They are borne, however, toward the centre of the
+Earth in a {226} straight line (if the way be open) by a motion of
+aggregation as though to their own origin: they move by various motions
+agreeably to the conformation of the whole: a terrella is moved circularly
+by its innate forces. "Besides" (says he), "all things which are borne in
+an orbe, afterwards would seem to be abandoned by the first motion, and to
+be borne by several motions besides the first. The Earth must also be borne
+on by two sorts of motion, whether it be situate around a mid-point, or in
+the middle site of the universe: and if this were so, there must needs be
+at one time an advance, at another time a retrogression of the fixed stars:
+This, however, does not seem to be the case, but they rise and set always
+the same in the same places." But it by no means follows that a double
+motion must be assigned to the Earth. But if there be but one diurnal
+motion of the Earth around its poles, who does not see that the stars must
+always in the same manner rise and set at the same points of the horizon,
+even although there be another motion about which we are not disputing:
+since the mutations in the smaller orbit cause no variation of aspect in
+the fixed stars owing to their great distance, unless the axis of the Earth
+have varied its position, concerning which we raise a question when
+speaking of the cause of the praecession of the aequinoxes. In this
+argument are many flaws. For if the Earth revolve, that we asserted must
+needs occur not by reason of the first sphaere, but of its innate forces.
+But if it were set in motion by the first sphaere, there would be no
+successions of days and nights, for it would continue its course along with
+the _Primum Mobile_. But that the Earth is affected by a double movement at
+the time when it rotates around its own centre, because the rest of the
+stars move with a double motion, does not follow. Besides, he does not well
+consider the argument, nor do his interpreters understand the same. [Greek:
+toutou de sumbainontos, anankaion gignesthai parodous kai tropas ton
+endedemenon astron.] (Arist. _de Coelo_, ii. chap. 14.) That is, "If this
+be so, there must needs be changes, and retrogressions of the fixed stars."
+What some interpret as retrogressions or regressions, and changes of the
+fixed stars, others explain as diversions: which terms can in no way be
+understood of axial motion, unless he meant that the Earth moved by the
+_Primum Mobile_ is borne and turned over other poles diverse even from
+those which correspond to the first sphaere, which is altogether absurd.
+Other later theorists suppose that the eastern ocean ought to be impelled
+so into western regions by that motion, that those parts of the Earth which
+are dry and free from water would be daily flooded by the eastern ocean.
+But the ocean is not acted upon by that movement, since nothing opposes it;
+and even the whole atmosphere is carried round: And for that reason in the
+Earth's course all the things in the air are not left behind by us nor do
+they seem to move toward the West: Wherefore also the clouds {227} are at
+rest in the air, unless the force of the winds drive them; and objects
+which are projected into the air fall again into their own place. But those
+foolish folk who think that towers, temples, and buildings must necessarily
+be shaken and overthrown by the Earth's motion, may fear lest men at the
+Antipodes should slip off into an opposite orbe, or that ships when sailing
+round the entire [249]globe should (as soon as they have dipped under the
+plane of our horizon) fall into the opposite region of the sky. But those
+follies are old wives' gossip, and the rubbish of certain philosophizers,
+men who, when they essay to treat of the highest truths and the fabrick of
+the universe, and hazard anything, can scarce understand aught _ultra
+crepidam_. They would have the Earth to be the centre of a circle; and
+therefore to rest motionless amid the rotation. But neither the stars nor
+the wandering globes move about the Earth's centre: the high heaven also
+does not move circularly round the Earth's centre; nor if the Earth were in
+the centre, is it a centre itself, but a body around a centre. Nor is it
+confident with reason that the heavenly bodies of the Peripateticks should
+attend on a centre so decadent and perishable as that of the Earth. They
+think that Nature seeks rest for the generation of things, and for
+promoting their increase while growing; and that accordingly the whole
+Earth is at rest. And yet all generation takes place from motion, without
+which the universal nature of things would become torpid. The motion of the
+Sun, the motion of the Moon, cause changes; the motion of the Earth awakens
+the internal breath of the globe; animals themselves do not live without
+motion, and the ceaseless activity of the heart and arteries. For of no
+moment are the arguments for a simple straight motion toward the centre,
+that this is the only kind in the Earth, and that in a simple body there is
+one motion only and that a simple one. For that straight motion is only a
+tendency toward their own origin, not of the parts of the Earth only, but
+of those of the Sun also, of the Moon, and of the rest of the sphaeres
+which also move in an orbit. Joannes Costaeus, who raises doubts concerning
+the cause of the Earth's motion, looking for it externally and internally,
+understands magnetick vigour to be internal, active, and disponent; also
+that the Sun is an external promotive cause, and that the Earth is not so
+vile and abject a body as it is generally considered. Accordingly there is
+a diurnal movement on the part of the Earth for its own sake and for its
+advantage. Those who make out that that terrestrial motion (if such there
+be) takes place not only in longitude, but also in latitude, talk nonsense.
+For Nature has set in the Earth determinate poles, and definite unconfused
+revolutions. Thus the Moon revolves with respect to the Sun in a monthly
+course; yet having her own definite poles, facing determinate parts of the
+heaven. To suppose that the air moves the Earth would be {228} ridiculous.
+For air is only exhalation, and is an enveloping effluvium from the Earth
+itself; the winds also are only a rush of the exhalations in some part near
+the Earth's surface; the height of its motion is slight, and in all regions
+there are various winds unlike and contrary. Some writers, not finding in
+the matter of the Earth the cause (for they say that they find nothing
+except solidity and consistency), deny it to be in its form; and they only
+admit as qualities of the Earth cold and dryness, which are unable to move
+the Earth. The Stoicks attribute a soul to the Earth, whence they pronounce
+(amid the laughter of the learned) the Earth to be an animal. This
+magnetick form, whether vigour or soul, is astral. Let the learned lament
+and bewail the fact that none of those old Peripateticks, nor even those
+common philosophizers heretofore, nor Joannes Costaeus, who mocks at such
+things, were able to apprehend this grand and important natural fact. But
+as to the notion that surface inequality of mountains and valleys would
+prevent the Earth's diurnal revolution, there is nothing in it: for they do
+not mar the Earth's roundness, being but slight excrescences compared with
+the whole Earth; nor does the Earth revolve alone without its emanations.
+Beyond the emanations, there is no renitency. There is no more labour
+exerted in the Earth's motion than in the march of the rest of the Stars:
+nor is it excelled in dignity by some stars. To say that it is frivolous to
+suppose that the Earth rather seeks a view of the Sun, than the Sun of the
+Earth, is a mark of great obstinacy and unwisdom. Of the theory of the
+rotation we have often spoken. If anyone seek the cause of the revolution,
+or of other tendency of the Earth, from the sea surrounding it, or from the
+motion of the air, or from the Earth's gravity, he would be no less silly
+as a theorist than those who stubbornly ground their opinions on the
+sentiments of the ancients. Ptolemy's reasonings are of no weight; for when
+our true principles are laid down, the truth comes to light, and it is
+superfluous to refute them. Let Costaeus recognize and philosophers see how
+unfruitful and vain a thing it becomes then to take one's stand on the
+principles and unproved opinions of certain ancients. Some raise a doubt
+how it can be that, if the Earth move round its own axis, a globe of iron
+or of lead dropped from the highest point of a tower falls exactly
+perpendicularly to a spot of the Earth below itself. Also how it is that
+cannon balls from a large culverin, fired with the same quantity and
+strength of powder, in the same direction and at a like elevation through
+the same air, would be cast at a like distance from a given spot both
+Eastward and Westward, supposing the Earth to move Eastward. But those who
+bring forward this kind of argument are being misled: not attending to the
+nature of primary globes, and the combination of parts with their globes,
+even though they be not adjoined by solid parts. Whereas the motion of the
+Earth in the diurnal revolution does not involve the separation of her more
+{229} solid circumference from the surrounding bodies; but all her effluvia
+surround her, and in them heavy bodies projected in any way by force, move
+on uniformly along with the Earth in general coherence. And this also takes
+place in all primary bodies, the Sun, the Moon, the Earth, the parts
+betaking themselves to their first origins and sources, with which they
+connect themselves with the same appetence as terrene things, which we call
+heavy, with the Earth. So lunar things tend to the Moon, solar things to
+the Sun, within the orbes of their own effluvia. The emanations hold
+together by continuity of substance, and heavy bodies are also united with
+the Earth by their own gravity, and move on together in the general motion:
+especially when there is no renitency of bodies in the way. And for this
+cause, on account of the Earth's diurnal revolution, bodies are neither set
+in motion, nor retarded; they do not overtake it, nor do they fall short
+behind it when violently projected toward East or West.
+
+[Illustration]
+
+Let E F G be the Earth's globe, A its centre, L E the ascending effluvia:
+Just as the orbe of the effluvia progresses with the Earth, so also does
+the unmoved part of the circle at the straight line L E progress along with
+the general revolution. At L and E, a heavy body, M, falls perpendicularly
+toward E, taking the shortest way to the centre, nor is that right movement
+of weight, or of aggregation compounded with a circular movement, but is a
+simple right motion, never leaving the line L E. But when thrown with an
+equal force from E toward F, and from E toward G, it completes an equal
+distance on either side, even though the daily rotation of the Earth is in
+process: just as twenty paces of a man mark an equal space whether toward
+East or West: so the Earth's diurnal motion {230} is by no means refuted by
+the illustrious Tycho Brahe, through arguments such as these.
+
+[Illustration] The tendency toward its origin (which, in the case of the
+Earth, is called by Philosophers weight) causes no resistance to the
+diurnal revolution, nor does it direct the Earth, nor does it retain the
+parts of the Earth in place, for in regard to the Earth's solidity they are
+imponderous, nor do they incline further, but are at rest in the mass. If
+there be a flaw in the mass, such as a deep cavity (say 1000 fathoms), a
+homogenic portion of the Earth, or compacted terrestrial matter, descends
+through that space (whether filled with water or air) toward an origin more
+assured than air or water, seeking a solid globe. But the centre of the
+Earth, as also the Earth as a whole, is imponderous; the separated parts
+tend toward their own origin, but that tendency we call weight; the parts
+united are at rest; and even if they were ponderable, they would introduce
+no hindrance to the diurnal revolution. For if around the axis A B, there
+be a weight at C, it is balanced from E; if at F, from G; if at H, from I.
+So internally at L, they are balanced from M: the whole globe, then, having
+a natural axis, is balanced in aequilibrio, and is easily set in motion by
+the slighted cause, but especially because the Earth in her own place is
+nowise heavy nor lacking in balance. Therefore weight neither hinders the
+diurnal revolution, nor influences either the direction or continuance in
+position. Wherefore it is manifest that no sufficiently strong reason has
+yet been found out by Philosophers against the motion of the Earth.
+
+       *       *       *       *       *
+
+
+{231} CHAP. VI.
+
+On the cause of the definite time, of an entire
+_rotation of the Earth._
+
+Diurnal motion is due to causes which have now to be sought, arising from
+magnetick vigour and from the confederated bodies; that is to say, why the
+diurnal rotation of the Earth is completed in the space of twenty-four
+hours. For no curious art, whether of Clepsydras or of sand-clocks, or
+those contrivances of little toothed wheels which are set in motion by
+weights, or by the force of a bent steel band, can discover any degree of
+difference in the time. But as soon as the diurnal rotation has been gone
+through, it at once begins over again. But we would take as the day the
+absolute turning of a meridian of the Earth, from sun to sun. This is
+somewhat greater than one whole revolution of it; in this way the yearly
+course is completed in 365 and nearly 1/4 turnings with respect to the sun.
+From this sure and regular motion of the Earth, the number and time of 365
+days, 5 hours, 55 minutes, in solar tropical years is always certain and
+definite, except that there are some slight differences due to other
+causes. The Earth therefore revolves not fortuitously, or by chance, or
+precipitately; but with a rather high intelligence, equably, and with a
+wondrous regularity, in no other way than all the rest of the movable
+stars, which have definite periods belonging to their motions. For the Sun
+himself being the agent and incitor of the universe in motion, other
+wandering globes set within the range of his forces, when acted on and
+stirred, also regulate each its own proper courses by its own forces; and
+they are turned about in periods corresponding to the extent of their
+greater rotation, and the differences of their effused forces, and their
+intelligence for higher good. And for that cause Saturn, having a wider
+orbit, is borne round it in a longer time, Jupiter a shorter, and Mars
+still less; while Venus takes nine months, Mercury 80 days, on the
+hypotheses of Copernicus; the Moon going round the Earth with respect to
+the Sun in 29 days, 12 hours, 44 minutes. We have asserted that the Earth
+moves circularly about its centre, completing a day by an entire revolution
+with respect to the Sun. The Moon revolves in a monthly course around the
+Earth, and, repeating a conjunction with the Sun after a former synodic
+conjunction, constitutes the month or Lunar day. The Moon's mean
+concentrick orbit, according to numerous observations of Copernicus and
+later astronomers, is found to be distant 29 and about 5/6 diameters of the
+Earth from the Earth's centre. The Moon's revolution with respect to the
+Sun takes place in 29-1/2 days and 44 minutes of time. We reckon the motion
+with respect to the sun, not the periodic motion, {232} just as a day is
+one entire revolution of the Earth with respect to the Sun, not one
+periodick revolution; because the Sun is the cause of lunar as of
+terrestrial motion: also, because (on the hypotheses of later observers)
+the synodical month is truly periodic, on account of the Earth's motion in
+a great orbit. The proportion of diameters to circumferences is the same.
+And the concentrick orbit of the Moon contains twice over 29 and 1/2 great
+circles of the Earth & a little more. The Moon & the Earth, then, agree
+together in a double proportion of motion; & the Earth moves in the space
+of twenty-four hours, in its diurnal motion; because the Moon has a motion
+proportional to the Earth, but the Earth a motion agreeing with the lunar
+motion in a nearly double proportion. There is some difference in details,
+because the distances of the stars in details have not been examined
+sufficiently exactly, nor are mathematicians as yet agreed about them. The
+Earth therefore revolves in a space of 24 hours, as the Moon in her monthly
+course, by a magnetick confederation of both stars, the globes being
+forwarded in their movement by the Sun, according to the proportion of
+their orbits, as Aristotle allows, _de Coelo_, bk. ii., chap. 10. "It
+happens" (he says) "that the motions are performed through a proportion
+existing between them severally, namely, at the same intervals in which
+some are swifter, others slower," But it is more agreeable to the relation
+between the Moon and the Earth, that that harmony of motion should be due
+to the fact that they are bodies rather near together, and very like each
+other in nature and substance, and that the Moon has more evident effects
+upon the Earth than the rest of the stars, the Sun excepted; also because
+the Moon alone of all the planets conducts her revolutions, directly
+(however diverse even), with reference to the Earth's centre, and is
+especially akin to the Earth, and bound to it as with chains. This, then,
+is the true symmetry and harmony between the motions of the Earth and the
+Moon; not that old oft-besung harmony of coelestial motions, which assumes
+that the nearer any sphaere is to the _Primum Mobile_ and that fictitious
+and pretended rapidest Prime Motion, the less does it offer resistance
+thereto, and the slower it is borne by its own motion from west to east:
+but that the more remote it is, the greater is its velocity, and the more
+freely does it complete its own movement; and therefore that the Moon
+(being at the greatest distance from the _Primum Mobile_) revolves the most
+swiftly. Those vain tales have been conceded in order that the _Primum
+Mobile_ may be accepted, and be thought to have certain effects in
+retarding the motions of the lower heavens; as though the motion of the
+stars arose from retardation, and were not inherent and natural; and as
+though a furious force were perpetually driving the rest of the heaven
+(except only the _Primum Mobile_) with frenzied incitations. Much more
+likely is it that the stars are borne around symmetrically by their own
+forces, with a certain mutual concert and harmony.
+
+       *       *       *       *       *
+
+
+{233} CHAP. VII.
+
+On the primary magnetick nature of the Earth,
+whereby its poles are parted from the poles
+_of the Ecliptick._
+
+Primarily having shown the manner and causes of the diurnal revolution of
+the Earth, which is partly brought about from the vigour of the magnetick
+virtue, partly effected by the prae-eminence and light of the Sun; there
+now follows an account of the distance of its poles from the poles of the
+Ecliptick--a supremely necessary fact. For if the poles of the universe or
+of the Earth remained fast at the poles of the Zodiack, then the Aequator
+of the Earth would lie exactly beneath the line of the Ecliptick, and there
+would be no variation in the seasons of the year, no Winter, no Summer, nor
+Spring, nor Autumn: but one and the same invariable aspect of things would
+continue. The direction of the axis of the Earth has receded therefore from
+the pole of the Zodiack (for lasting good) just so far as is sufficient for
+the generation and variety of things. Accordingly the declination of the
+tropicks and the inclination of the Earth's pole remain perpetually in the
+twenty-fourth degree; though now only 23 degrees 28 minutes are counted;
+or, as others make out, 29 minutes: But once it was 23 degrees 52 minutes,
+which are the extreme limits of the declinations hitherto observed. And
+that has been prudently ordained by nature, and is arranged by the primary
+excellence of the Earth. For if those poles (of the Earth and the
+Ecliptick) were to be parted by a much greater distance, then when the Sun
+approached the tropick, all things in the other deserted part of the globe,
+in some higher latitude, would be desolate and (by reason of the too
+prolonged absence of the Sun) brought to destruction. As it is, however,
+all is so proportioned that the whole terrestrial globe has its own varying
+seasons in succession, and alternations of condition, appropriate and
+needful: either from the more direct and vertical radiation of light, or
+from its increased tarriance above the horizon.
+
+Around these poles of the Ecliptick the direction of the poles of the Earth
+is borne: and by this motion the praecession of the aequinoxes is apparent
+to us.
+
+       *       *       *       *       *
+
+
+{234} CHAP. VIII.
+
+On the Praecession of the Aequinoxes, from the magnetick
+motion of the poles of the Earth, in the Arctick
+_and Antarctick circle of the Zodiack._
+
+Primitive mathematicians, since they did not pay attention to the
+inequaelities of the years, made no distinction between the aequinoctial,
+or solstitial revolving year, and that which is taken from some one of the
+fixed stars. Even the Olympick years, which they used to reckon from the
+rising of the dogstar, they thought to be the same as those counted from
+the solstice. Hipparchus of Rhodes was the first to call attention to the
+fact that these differ from each other, and discovered that the year was
+longer when measured by the fixed stars than by the aequinox or solstice:
+whence he supposed that there was in the fixed stars also some motion in a
+common sequence; but very slow, and not at once perceptible. After him
+Menelaus, a Roman geometer, then Ptolemy, and long afterward Mahometes
+Aractensis, and several more, in all their literary memoirs, perceived that
+the fixed stars and the whole firmament proceeded in an orderly sequence,
+regarding as they did the heaven, not the earth, and not understanding the
+magnetical inclinations. But we shall demomstrate that it proceeds rather
+from a certain rotatory motion of the Earth's axis, than that that eighth
+sphaere (so called) the firmament, or non-moving empyrean, revolves studded
+with innumerable globes and stars, whose distances from the Earth have
+never been proved by anyone, nor can be proved (the whole universe gliding,
+as it were). And surely it should seem much more likely that the
+appearances in the heavens should be clearly accounted for by a certain
+inflection and inclination of the comparatively small body of the Earth,
+than by the setting in motion of the whole system of the universe;
+especially if this motion is to be regarded as ordained solely for the
+Earth's advantage: While for the fixed stars, or for the planets, it is of
+no use at all. For this motion the rising and settings of stars in every
+Horizon, as well as their culminations at the height of the heavens, are
+shifted so much that the stars which once were vertical are now some
+degrees distant from the zenith. For nature has taken care, through the
+Earth's soul or magnetick vigour, that, just as it was needful in
+tempering, receiving, and warding off the sun's rays and light, by suitable
+seasons, that the points toward which the Earth's pole is directed should
+be 23 degrees and more {235} from the poles of the Ecliptick[250]: so now
+for moderating and for receiving the luminous rays of the fixed stars in
+due turn and succession, the Earth's poles should revolve at the same
+distance from the Ecliptick at the Ecliptick's arctick circle; or rather
+that they should creep at a gentle pace, that the actions of the stars
+should not always remain at the same parallel circles, but should have a
+rather slow mutation. For the influences of the stars are not so forceful
+as that a swifter course should be desired. Slowly, then, is the Earth's
+axis inflected; and the stars' rays, falling upon the face of the Earth,
+shift only in so long a time as a diameter of the arctick or polar circle
+is extended: whence the star at the extremity of the tail of the Cynosure,
+which once was 12 degrees 24 minutes (namely, in the time of Hipparchus)
+distant from the pole of the universe, or from that point which the pole of
+the Earth used to face, is now only 2 degrees and 52 minutes distant from
+the same point; whence from its nearness it is called by the moderns
+_Polaris._ Some time it will be only 1/2 degree away from the pole:
+afterward it will begin to recede from the pole until it will be 48 degrees
+distant; and this, according to the Prutenical tables, will be in Anno
+Domini 15000. Thus _Lucida Lyrae_ (which to us southern Britons now almost
+culminates) will some time approach to the pole of the world, to about the
+fifth degree. So all the stars shift their rays of light at the surface of
+the Earth, through this wonderful magnetical inflection of the Earth's
+axis. Hence come new varieties of the seasons of the year, and lands become
+more fruitful or more barren; hence the characters and manners of nations
+are changed; kingdoms and laws are altered, in accordance with the virtue
+of the fixed stars as they culminate, and the strength thence received or
+lost in accordance with the singular and specifick nature of each; or on
+account of new configurations with the planets in other places of the
+Zodiack; on account also of risings and settings, and of new concurrences
+at the meridian. The Praecession of the aequinoxes arising from the
+aequable motion of the Earth's pole in the arctick circle of the Zodiack is
+here demonstrated. Let A B C D be the Ecliptick line; I E G the arctic
+circle of the Zodiack. Then if the Earth's pole look to E, the aequinoxes
+are at D, C. Let this be at the time of Metho, when the horns of Aries were
+in the aequinoctial colure. Now if the Earth's pole have advanced to I;
+then the aequinoxes will be at K, L; and the stars in the ecliptick C will
+seem to have progressed, in the order of the signs, along the whole arc K
+C: L will be moved on by the praecession, against the order of the signs,
+along the arc D L. But this would occur in the contrary order, if the point
+G were to face the poles of the earth, and the motion were from E to G: for
+then the aequinoxes would be M N, and the fixed stars would anticipate the
+same at C and D, counter to the order of the signs.
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+{236} CHAP. IX.
+
+On the anomaly of the Praecession of the Equinoxes,
+_and of the obliquity of the Zodiack._
+
+At one time the shifting of the aequinoxes is quicker, at another slower,
+being not always equal: because the poles of the earth travel unequally in
+the arctick and antarctick circle of the Zodiack; and decline on both sides
+from the middle path: whence the obliquity of the Zodiack to the Aequator
+seems to change. And as this has become known by means of long
+observations, so also has it been perceived, that the true aequinoctial
+points have been elongated from the mean aequinoctial points, on this side
+and on that, by 70 minutes (when the prostaphaeresis is greatest): but that
+the solstices either approach the equator unequally 12 minutes nearer, or
+recede as far behind; so that the nearest approach is 23 degrees 28
+minutes, and the greatest elongation 23 degrees 52 minutes. Astronomers
+have given various explanations to account for this inequality of the
+praecession and also of the obliquity of the tropicks. Thebit, with the
+view of {237} laying down a rule for such considerable inequalities in the
+motion of the stars, explained that the eighth sphaere does not move with a
+continuous motion from west to east; but is shaken with a certain motion of
+trepidation, by which the first points of Aries and Libra in the eighth
+heaven describe certain small circles with diameters equal to about nine
+degrees, around the first points of Aries and Libra in the ninth sphaere.
+But since many things absurd and impossible as to motion follow from this
+motion of trepidation, that theory of motion is therefore long since
+obsolete. Others therefore are compelled to attribute the motion to the
+eighth sphaere, and to erect above it a ninth heaven also, yea, and to pile
+up yet a tenth and an eleventh: In the case of mathematicians, indeed, the
+fault may be condoned; for it is permissible for them, in the case of
+difficult motions, to lay down some rule and law of equality by any
+hypotheses. But by no means can such enormous and monstrous celestial
+structures be accepted by philosophers. And yet here one may see how hard
+to please are those who do not allow any motion to one very small body, the
+Earth; and notwithstanding they drive and rotate the heavens, which are
+huge and immense above all conception and imagination: I declare that they
+feign the heavens to be three (the most monstrous of all things in Nature)
+in order that some obscure motions forsooth[251] may be accounted for.
+Ptolemy, who compares with his own the observations of Timocharis and
+Hipparchus, one of whom flourished 260 years, the other 460 years before
+him, thought that there was this motion of the eighth sphaere, and of the
+whole firmament; and proved by help of numerous phenomena that it took
+place over the poles of the Zodiack, and, supposing its motion to be so far
+aequable, that the non-planetary stars in the space of 100 years completed
+just one degree beneath the _Primum Mobile_. After him 750 years
+Albategnius discovered that one degree was completed in a space of 66
+years, so that a whole period would be 23,760 years. Alphonsus made out
+that this motion was still slower, completing one degree and 28 minutes
+only in 200 years; and that thus the course of the fixed stars went on,
+though unequally. At length Copernicus, by means of the observations of
+Timocharis, Aristarchus of Samos, Hipparchus, Menelaus, Ptolemy, Mahometes
+Aractensis, Alphonsus, and of his own, detected the anomalies of the motion
+of the Earth's axis: though I doubt not that other anomalies also will come
+to light some ages hence. So difficult is it to observe motion so slow,
+unless extending over a period of many centuries; on which account we still
+fail to understand the intent of Nature, what she is driving after through
+such inequality of motion. Let A be the pole of the Ecliptick, B C the
+Ecliptick, D the Aequator; when the pole of the Earth near the arctick
+circle of the Zodiack faces the point M, then there is an anomaly of the
+praecession of the aequinox at F; {238} but when it faces N, there is an
+anomaly of the praecession at E. But when it faces I directly, then the
+maximum obliquity G is observed at the solstitial colure; but when it faces
+L, there is the minimum obliquity H at the solstitial colure.
+
+[Illustration]
+
+_Copernicus' contorted circlet in the Arctick circle of the Zodiack._
+
+Let F B G be the half of the Arctick circle described round the pole of the
+Zodiack: A B C the solstitial colure: A the pole of the Zodiack; D E the
+anomaly of longitude 140 minutes at either side on both ends: B C the
+anomaly of obliquity 24 minutes: B the greater obliquity of 23 degrees 52
+minutes: D the mean obliquity of 23 degrees 40 minutes: C the minimum
+obliquity of 23 degrees 28 minutes.
+
+{239} [Illustration]
+
+[Illustration]
+
+{240} The period of motion of the praecession of the aequinoxes is 25,816
+Aegyptian years; the period of the obliquity of the Zodiack is 3434 years,
+and a little more. The period of the anomaly of the praecession of the
+aequinoxes is 1717 years, and a little more. If the whole time of the
+motion AI were divided into eight equal parts: in the first eighth the pole
+is borne somewhat swiftly from A to B; in the second eighth, more slowly
+from B to C; in the third, with the same slowness from C to D; in the
+fourth, more swiftly again from D to E; in the fifth, with the same
+swiftness from E to F; again more slowly from F to G; and with the same
+slowness from G to H; in the last eighth, somewhat swiftly again from H to
+I. And this is the contorted circlet of Copernicus, fused with the mean
+motion into the curved line which is the path of the true motion. And thus
+the pole attains the period of the anomaly of the praecession of the
+aequinoxes twice; and that of the declination or obliquity once only. It is
+thus that by later astronomers, but especially by Copernicus (the Restorer
+of Astronomy)[252], the anomalies of the motion of the Earth's axis are
+described, so far as the observations of the ancients down to our own times
+admit; but there are still needed more and exact observations for anyone to
+establish aught certain about the anomaly of the motion of the
+praecessions, and at the same time that also of the obliquity of the
+Zodiack. For ever since the time at which, by means of various
+observations, this anomaly was first observed, we have only arrived at half
+a period of the obliquity. So that all the more all these matters about the
+unequal motion both of the praecession and of the obliquity are uncertain
+and not well known: wherefore neither can we ourselves assign any natural
+causes for it, and establish it for certain. Wherefore also do we to our
+reasonings and experiments magnetical here set an end and period.[253]
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+{241}
+
+INDEX.
+
+  Abano, Pietro di (Apponensis or Apianus), 2.
+  Abbas, Hali ('Ali ibn Al 'Abb[=a]s, _Al Majusi_, 2, 6.
+  Abohalis, 47. _See also_ Avicenna.
+  _aciarium_ or _acies_, also _aciare_, 18, 23, 33, 36.
+  Acosta, Josephus, 5.
+  adamant, 11.
+  aequator, the magnetick, 13, 79.
+  Aetius Amidenus, 2.
+  Affaytatus, Fortunius, 6.
+  agate, non electrick, 51, 53.
+  Agricola, Georgius, 2, 3, 10, 19, 26, 111, 112.
+  Agrippa, H. Cornelius, 3.
+  _aimant_, 11.
+  Albategnius (Muhammad ibn J[=a]bir, _Al-Batt[=a]ni_, 237.
+  Albertus Magnus, 2, 7, 18, 111.
+  Alexander Aphrodiseus, 3, 48, 92.
+  Alexandria, Hero of, 58.
+  Alfonso, Diego, 178.
+  Alfonsus the Wise (Alphonsus X.), 237.
+  Amalfians said to have first constructed the compass, 4.
+  Amatus Lusitanus, 2.
+  amber, 47, 49-60, 85, 112, 116.
+  amethyst, electrical properties of, 48.
+  amianth, 11.
+  Amidenus, Aetius, 2.
+  amphitane, 111.
+  Anatolismus, or Northeasting, 167.
+  Anaxagoras, 61, 208.
+  Andrea Doria (Admiral), 4.
+  Antonius de Fantis, 107.
+  Antonius Musa Brasavolus, 2.
+  Antony, the denarius of, 110.
+  Apianus. _See_ Abano.
+  Apponensis. _See_ Abano.
+  Aquinas, Thomas, 3, 64.
+  Aractensis, Mahometes, 234, 237.
+  Archelaus, 208.
+  Ardoynis, Santes de, 2.
+  Arias Montanus, 4.
+  Aristarchus, 214, 237.
+  Aristotle:
+    _De Anima_, 1, 11, 61, 210.
+    _De Coelo_, 226, 232.
+    _De Mirabilibus Auscultationibus_, 22.
+    _Meteorologica_, 35, 39.
+    on material of the metals, 19, 20.
+    on the element of earth, 43.
+    on motions, 45, 219, 225.
+    on primary form, 65.
+    on the _Primum Mobile_, 220.
+    on animate nature of planets, 208.
+  armature, 87.
+  armed loadstones, 86, 87, 88, 89.
+  Arnaldus de Villa nova, 2, 7.
+  Arsinoe, Temple of, 2.
+  Attraction, 46, 60, 64, 68, 90, 98, 109.
+  Avicenna (Abu 'Ali Husain ibn 'Abd Allah, _Ibn Sina_; also called
+      Abohalis):
+    writes on the magnet, 2.
+    on falling masses of iron, 26.
+    alleges loadstone an antidote to iron poison, 35.
+    on the property of attraction, 49.
+  Augsburgers (Augustani), the, prescribe loadstone in plaster, 33.
+  axis, the magnetick, 13, 81, 212.
+  Azores, variation of compass at the, 4, 154, 156, 167.
+
+  Bacon, Roger, 5.
+  Bambola, or Bilbilis, 23.
+  Baptista Montanus, 2.
+  Baptista Porta. _See_ Porta.
+  Barbarus, Hermolaus, 3.
+  Barlowe, William (Rev. Archdeacon), his book, _The Navigators Supply_, 8.
+  basil leaves alleged not to be attracted, 48.
+  belemnites are electrical, 48.
+  Bencora (Th[=a]bit ibn Kurrah, _Al Harrani_; also called Thebitius), 117,
+      236.
+  Benedictus, Joannes Baptista (Giambattista Benedetti), 167.
+  beryl, electrick properties of, 48.
+  Bessardus (Toussaincte de Bessard), 5, 116, 153.
+  Blondus, Flavius, the historian, 4.
+  Borough, William, his book on the _Variation of the Compass_, 8.
+  Borrholybicum (North-north-west), 160.
+  Brahe, Tycho, 174, 229.
+  Brandoe, the island of, 181.
+  Brasavolus, Antonius Musa, 2.
+  Bristolla, or Bristol gem, 48.
+  burnt clay, magnetick properties of, 26, 43.
+  {242}
+
+  Cabot, Sebastian, 4.
+  Caelius Calcagninus, 7.
+  Caesare, or Cesare, Giulio, 141.
+  Calaber, Hannibal Rosetius, 3,
+  _calamita_ or _kalamita_, 11.
+  Calcagninus, Caelius, 7.
+  Camillus Leonhardus, 3.
+  Candish, or Cavendish, Thomas, *iij, 117.
+  cap of iron for a loadstone, 86, 89, 90, 95.
+  _carabe_, or _karabe_, 47.
+  carbuncle, electrick properties of, 48, 111.
+  Cardan, Hieronymo, 2.
+    _De Proportionibus_:
+      on iron and earth, 43, 62, 67.
+      on distance of centre of cosmos, 169.
+    _De Rerum Varietate_:
+      on fall of meteorick iron, 26.
+      on attraction of amber, 49.
+      on a perpetual motion engine, 107.
+    _De Subtilitate_:
+      alleges magnet to feed on iron, 37, 63, 92.
+      on magnet that draws silver, 110.
+      on magnetick influence of star in tail of _Ursa Minor_, 5, 116, 153.
+  carnelian, the, 51, 55.
+  _catoblepas_, the antelope called, 63.
+  Cesare, Giulio, 141.
+  _chalybs_, 18, 25, 33.
+  chatochitis, 111.
+  chemists, the, 19, 20, 21, 24, 37, 66.
+  China, 4, 8, 9, 11, 17, 32, 119.
+  Chinocrates, 2.
+  circumpulsion, doctrine of, 3, 61.
+  clamps (open kilns), 26.
+  clay when burnt is magnetick, 26, 43, 97.
+  clepsydra, 231.
+  Coimbra, College of, 5.
+  coition (mutual attraction), 45, 46, 60, 65, 67, 68, 81, 98, 99, 103,
+      109, 131.
+    definition of, *vj, 68.
+    orbe of, *vj.
+  colours of loadstones, 9, 10, 27.
+  Como, 23.
+  compass, alleged invention of, by Amalfians, 4.
+    origin of the compass-card, 4, 165.
+    the mariners' (_pyxis_), 3, 115, 147, 165, 172.
+    the little (_pyxidula_), 181, 202.
+    different forms of, Italian, Baltic, Portuguese, English, 165, 166,
+        177, 181.
+  conduction, magnetick, 85, 104, 125.
+  consequent poles, 129, 142.
+  Copernican system, 231.
+  Copernicus, Nicolas, 212, 214, 216, 231, 237, 238, 240.
+  Cordus, Valerius, 10.
+  Cornelius Agrippa, 3.
+  Cornelius Gemma, 63.
+  Cornelius Tacitus, 25.
+  _corolla insorta_, or contorted circlet, 238, 240.
+  Cortes, Martin, 5, 116, 152.
+  Corvo, Island of, 167.
+  Costa, Filippo (of Mantua), 141.
+  Costaeus, Joannes, 3, 62, 227, 228.
+  _creagus_, the, or flesh-magnet, 110.
+  crystal, rock, 48, 52, 59, 111
+  Curtius, Nicolaus, 35.
+  Cusan  (Michael Khrypffs),  Cardinal de Cusa, 3, 64, 108.
+  Cynosure, the, or Pole-star, 14, 81, 117, 222, 235.
+
+  Dean, Forest of, loadstone found in the, 11.
+  decay of the magnetick virtue, 18, 37, 124, 138, 149.
+  declination, the, or dip, 184.
+  denarius of Antony, 110.
+  diamond, an electrick, 48, 50, 59, 111.
+    alleged power to attract iron, 109, 112.
+    alleged antipathy to magnet, 2, 7, 109, 143.
+    experiments upon, 143.
+  Diego Alfonso, 178.
+  Differences between electricks and magneticks, 47, 60, 65.
+  Dioscorides, 1, 2, 9, 32.
+  dip, the, also called declination, 8, 46, 184-204.
+  dipping-needle, or declination instrument, 185, 203.
+  direction, or directive force, 41, 46, 115, 119.
+  dividing a loadstone, 16, 72, 100, 121, 122, 127, 130, 136, 145, 146.
+  Dominicus Maria Ferrariensis, 212, 213.
+  Doria, Andrea (Admiral), 4.
+  Drake, Sir Francis, *iij _bis_, 117.
+  Du Puys (also called Puteanus), 3, 63.
+
+  Earth, the, a great magnet, 38, 39, 40, 41, 44, 119, 211.
+  _echeneis_ (the sucking fish), 7, 63, 110.
+  Ecphantus, 214.
+  effluvia, electrical, 52, 53, 59, 66.
+    magnetical, 61.
+  electrical attraction, 50, 51, 111.
+  electrick force, definition of, 52.
+  electricks, *vj, 46-60.
+  _electrum_ ([Greek: elektron]), 47.
+  emerald is non-electrick, 51.
+  emery, 22, 51.
+  Empedocles, 208.
+  Encelius (or Entzelt, Christoph.), 3, 111.
+  Epicurius, 61, 62.
+  Erasmus Rheinholdus, 213.
+  Erastus, Thomas, 3, 22.
+  errors in navigation, 166, 177.
+  Evax, King of Arabia, 111.
+  Euripides, 9, 11, 18.
+  {243}
+
+  Fallopius, Gabriellus, 3, 34, 35, 112.
+  Fantis, Antonius de, 107.
+  Fernelius, Joannes Franciscus, 4.
+  Ficinus, Marsilius (or Marsiglio Ficino), 3, 7, 116 153.
+  filings of iron, 37, 69, 90, 91, 92, 104.
+  Filippo Costa. _See_ Costa.
+  fire destroys magnetick properties, 66, 67, 91, 124.
+  flame destroys electrification, 59.
+  flame hinders not magnetick attractions, 66.
+  Flavius Blondus. _See_ Blondus.
+  flies in amber, 47.
+  form _versus_ matter, 52, 65.
+  Fra Paolo, 6.
+  Fracastorio, Hieronymo, 5, 50, 67, 71, 91, 110, 113, 152.
+  Franciscus Maurolycus. _See_ Maurolycus.
+  Franciscus Rueus. _See_ Rueus.
+
+  Gagates. _See_ jet.
+  Galen, 2, 9, 32, 35, 39, 46, 49, 61, 62, 63.
+  Gallus, Marbodaeus, 2, 7.
+  garlick, its reputed antagonism to magnetism, 2, 32, 64.
+  Gartias ab Horto, 32.
+  Gaudentius Merula, 7.
+  Gauricus, Lucas, 7.
+  Geber (J[=a]bir ibn Haiyan, _Al-Tarsus[=i]_) 21.
+  Gemma, Cornelius, 63.
+  gems, electrick properties of, 48, 51.
+  _geniter_, 47.
+  Georgius Agricola. _See_ Agricola.
+  Gilbert, Adrian, 11.
+  Gilgil Mauritanus, 19.
+  Gioia, or Goia, of Amalfi, 4.
+  Giulio Caesare, 141.
+  glass, an electrick by friction, 48, 54, 59.
+    use of loadstone in making, 111.
+  goat's blood, 7.
+  Gonzalus Oviedus, 4.
+  Goropius, Henricus Becanus, 4.
+  Grotius, Hugo, 167, 168.
+
+  Haematite, 22, 51.
+  Hali Abbas ('Ali ibn Al 'Abbas, _Al Masufi_), 2, 6.
+  Hannibal Rosetius Calaber, 3.
+  Hariot, Thomas, 7.
+  Heat, effect of on loadstone, 66, 67, 93, 123, 124.
+  Helmshuda, 167.
+  Heraclea, the city of, 8.
+  Heraclean stone, or stone of Hercules, 8, 43, 61, 169.
+  Heraclides, 214.
+  Heraclitus, 208.
+  Hermes, 209.
+  Hermolaus Barbarus, 3.
+  Hero of Alexandria, 58.
+  Hipparchus, 213, 214, 234, 235, 237.
+  Hippocrates, 8, 35, 51, 61.
+  horizon, the magnetick, defined, 80.
+  Horto, Gartias ab, 32.
+  Horus, the bone of, or _Os Ori_, 9.
+  hot iron not magnetick, 66.
+  Hues, Robert, 7.
+  Hugo Grotius, 167, 168.
+
+  Inclination. _See_ dip.
+  interposition of bodies, 53, 66, 83, 85, 89, 137.
+  iris gem, the, 48.
+  iron, its nature and occurrence, 19, 20, 22, 25.
+    filings of, 37, 69, 90, 91, 92, 104.
+    its various names and qualities, 23, 33, 36.
+    its various uses, 23, 24, 39, 86, 90, 95.
+    medical uses of, 33, 35.
+    surpasses loadstone, 69, 95.
+    verticity in, 85, 123, 139.
+  iron ore is magnetick, 18, 27, 38, 43.
+    has poles, 28.
+  islands, magnetick influence of, 5, 153,161.
+
+  Jacobus Severtius, 5.
+  jet, 47, 48, 53, 55, 86.
+  Joannes Baptista Porta. _See_ Porta.
+  Joannes Baptista Montanus, 2.
+  Joannes Costaeus. _See_ Costaeus.
+  Joannes Franciscus Offusius, 46.
+  Joannes Goia. _See_ Gioia.
+  Joannes Langius, 3.
+  Joannes Taisner, or Taisnier. _See_ Taisnier.
+  Jofrancus Offusius, 46.
+  Josephus Acosta, 5.
+  Julius Caesar Moderatus, 141.
+  Julius Caesar Scaliger. _See_ Scaliger.
+
+  Kendall, Abraham, 7, 178.
+  Korrah, Thebitius Ben. _See_ Bencora.
+
+  Lactantius, Lucius, 219.
+  Lagos, Rodriguez de, 177.
+  Langius, Joannes, 3.
+  _lapis magnetis_, 8.
+  _lapis specularis_, muscovy stone, or mica, 11, 48, 52.
+  latitude in relation to dip, 196, 200.
+  Leonardus (or Leonhardus), Camillus, 3.
+  Levinus Lemnius, 3.
+  {244}
+  lifting power of loadstones, 86, 89, 97.
+  lily of the compass, 117, 152, 165, 177.
+  liquids, electrical attraction of, 55.
+    attraction on surface of, 57.
+  Livio Sanuto, 5, 153, 167.
+  loadstone armed and unarmed, 86, 87, 88.
+    as medicine, 32.
+    in plasters, 33.
+    rock, the, 5, 6, 18, 116, 152.
+    various names of, 11.
+    colours of, 9, 10, 27.
+    various sources of, 8, 25, 32.
+  London, magnetick variation at, 154, 163.
+  longitude, magnetick finding at, 166.
+  long magnets, advantage of, 82, 83, 99, 101
+  Lucania, fall of meteorick stones in, 26.
+  Lucas Gauricus, 7.
+  Lucretius, 2, 3, 8, 49, 61.
+  Lusitanus, Amatus, 2.
+  Lynschoten, Hugo van, *iiij.
+
+  Magnes, [Greek: magnes], [Greek: magnetis], 11.
+  Magnesia, 8.
+  Magnetick axis of terrella, 81, 212.
+    axis of earth, 13, 81, 212.
+    horizon, 80.
+    meridian, 79, 152.
+    mountains or rocks, 5, 6, 18, 116, 152.
+    islands, 5, 153, 161.
+    motions, the five, 45.
+  Magnus, Albertus. _See_ Albertus.
+  Magnus, Olaus, 5, 6.
+  Mahometes Aractensis, 234, 237.
+  Mahomet's tomb, 2.
+  Manardus, Joannes, 35.
+  Marbodaeus Gallus, 2, 7.
+  Marcellus Empiricus, 2.
+  Marco Polo (Paulus Venetus), 4.
+  mariners' compass. _See_ compass.
+  Mars, saffron of (_Crocus Martis_), 34, 91.
+  Marsiglio Ficino. _See_ Ficinus.
+  Martin Cortes, 5, 116, 152.
+  matter and form, 52, 65.
+  Matthaeus Silvaticus, 3.
+  Matthiolus, Petrus, 2, 3.
+  Mauritanus, Gilgil, 19.
+  Mauritanus, Serapio, 2, 6.
+  Maurolycus, Franciscus, 5, 42, 153, 180.
+  medicinal use of iron, 33.
+    of loadstone, 32.
+  Medina, Pedro de, 166.
+  Menelaus, 234, 237.
+  meridian, magnetick, 79, 152, 163.
+  Merula, Gaudentius, 7.
+  meteorick stones, falls of, 26, 27.
+  mica (or muscovy stone), 11, 48, 52.
+  [Greek: mikroge]. _See_ terrella.
+  moisture stops electrick action, 53, 56.
+  Montagnana, B., 35.
+  Montanus, Arias, 4.
+  Montanus, Joannes Baptista, 2.
+  Moors, Serapio and the, 6.
+  mountains, magnetick, 5, 6, 18, 116, 152.
+  movement of trepidation, 117.
+  Musa Brasavolus, Antonius, 2.
+  muscovy stone, 11, 48, 52. _See also_ mica.
+  myths of the magnet, 2, 3, 5, 6, 7, 18, 32, 63, 107, 109, 110, 111, 116,
+      143, 153, 228
+  motions, the various magnetical, 46.
+
+  Names of amber, 47.
+  names of the loadstone, 11.
+  names given to the magnetick poles, 15, 115, 125, 129.
+  Nicander of Colophon, 8, 9.
+  Nicetas, 214.
+  Nicolas Copernicus, 212, 214, 216, 231, 237, 238, 240
+  Nicolaus Myrepsus, or Praepositas, 33.
+  non-electrick bodies, 51, 55.
+  Nonius, Petrus (Pedro Nunez), 166.
+  Norman, Robert, 5, 8, 153, 161, 162.
+    supposes a point respective, 5, 153, 161, 162.
+    his _Newe Attractive_, 8.
+    discoverer of the dip, 8.
+  Norumbega, the city of, 154.
+  Nova Zembla, 152, 179.
+
+  Offusius, Jofrancus, 46.
+  Olaus Magnus, 5, 6.
+  opal becomes electrical, 48.
+  orbe of virtue, 76, 96, 191, 205
+  orbes of planets, 208, 215.
+  Oribasius, 2.
+  Orpheus, 11, 61, 209.
+  Oviedus, Gonzalus (Gonzalo Fernandez de Oviedo y Valdes), 4.
+
+  Pantarbes, 111.
+  Paolo (Paulus Aeginae), 35.
+  Paolo, Rev. Maestro (Fra Paolo Sarpi), 6
+  Paolo the Venetian (Marco Polo), 4.
+  Paracelsus (Bombast von Hohenheim).
+    asserts the stars to attract iron, 3.
+    his emplastrum of loadstone, 33.
+    his method of strengthening loadstones, 93.
+  Parmenides, 208.
+  pearls are not electrick, 51, 55.
+  Pedro de Medina, 166.
+  percussion excites verticity, 139.
+  Peregrinus, Peter,
+    his book, 5.
+    on cause of magnetick direction, 5, 116, 153.
+    on perpetual motion engine, 107.
+    affirms a terrella to revolve daily, 223.
+  {245}
+  Peripateticks, the, 20, 41, 43, 45, 65, 218, 222, 225, 227, 228.
+  perpetual motion machine, 107.
+  Peter Peregrinus. _See_ Peregrinus.
+  Peter Plancius. _See_ Plancius.
+  Petrus Apponensis. _See_ Abano, Pietro di.
+  Petrus Nonius. _See_ Nonius or Nunez.
+  Philolaus, 214.
+  Philostratus, 111.
+  Pictorio, G., 6, 49.
+  _piedramant_, 11.
+  Plancius, Peter, *v _bis._
+  planets, influence of, 20, 137, 142.
+  plasters, magnetick, 32, 33.
+  Plato, 3.
+    in the _Io_, discusses name and properties of the magnet, 1, 9, 11, 18.
+    in the _Timaeus_, suggests the theory of circumpulsion, 61.
+    his Atlantis, 159.
+    on life in the universe, 208.
+  Pliny (C. Plinius Secundus).
+    on loadstone fables, 1, 2, 9, 18.
+    his mistake about Aethiopian loadstones, 17.
+    on the five kinds of loadstones, 9.
+    on the alleged discovery of the loadstones, 8.
+    on the alleged magnetick mountains, 18.
+    on a locality where loadstone was found, 11.
+    on the occurrence of iron in Spain, 25.
+    on the Sagda and the Catochites, 111.
+    on the silver denarius of Antony, 110.
+    on the use of loadstone by glass-makers, 111.
+    on the shadow of a gnomon of a sun-dial at Rome, 213.
+  Plotinus, 218.
+  Plutarch, Claudius.
+    on the garlick fable, 32.
+    says something flammable exists in amber, 54.
+    his theory of circumpulsion, 3, 62.
+  polarity. _See_ verticity.
+  pole, the, elevation of, 200, 213.
+  poles, magnetick, of a loadstone, 13, 41, 72, 81, 144.
+  poles are not points, 12, 41, 72, 96.
+  Polo, Marco, 4.
+  Porta, Joannes Baptista (Giambattista della Porta).
+    his narration of marvels, 6.
+    on various tempering of iron, 24.
+    asserts loadstone a mixture of stone and iron, 63.
+    on his assertion that loadstones have hairs, 66.
+    asserts vapour to be cause of attraction, 67.
+    his error as to change of verticity, 73.
+    suspends iron upwards by a thread, 92.
+    his error as to centre of the orbe of virtue, 95.
+    his error as to the polarity which causes repulsion, 102.
+    his error as to magnetick opposing forces, 103.
+    experiment with a balance, 108.
+    his error as to iron being intoxicated, 138.
+    his error as to iron excited by a diamond, 143.
+    his error as to the pointing of a magnet, 144.
+    proportion between loadstone and iron, 149.
+    his error as to variation and longitude, 166.
+  praecession of the Aequinoxes, 234, 236.
+  _primum mobile_, the, 79, 214, 216, 218, 220, 226, 232, 237.
+  prostaphaeresis, 174, 236.
+  Prutenical Tables, the, 235.
+  Ptolemaeus, Claudius.
+    on loadstone fables, 2, 32.
+    on the occurrence of loadstone and of iron, 9,25.
+    on the dissolution of the earth, 91, 217, 218.
+    alleged relation of regions with the planets, 137.
+    on the elevation of the pole at different latitudes, 213,  214.
+    on the _Primum Mobile_, and the diurnal movement of the stars, 216,
+        228, 234.
+    on the anomalies of the earth's motion, 237.
+  Puteanus, Gulielmus (Du Puys), 3, 63.
+  pyrimachus (_i.e._, pyrites), 23.
+  Pythagoras, 57, 208.
+  _pyxidula_, 4, 181.
+  _pyxis_, 3, 115, 147, 165, 172.
+
+  Radius, the, of the earth's orbit, 218.
+  Rasis. _See_ Rhazes.
+  rays of magnetick virtue, 95.
+  Reinoldus, Erasmus (or Rheinholdus), 213.
+  _remora_, the (or sucking fish), 7, 63, 110.
+  resin becomes electrical by friction, 48, 52.
+  respective points, 5, 153, 161, 162.
+  reversal of polarity, 101, 137.
+  revolution of the globe, 46, 81, 91, 220.
+  repulsion, electrical, denied to exist, 113.
+  Rhazes (Muhammad ibn Zakar[=i]y[=a]), 34, 35.
+  rings, on the verticity of, 129.
+  Rodriguez de Lagos, 177.
+  Rosetius Calaber, Hannibal, 3.
+  Ruellius, Joannes, 7.
+  Rueus, Franciscus (de la Rue), 6.
+
+  Saffron of Mars, 34, 91, 93.
+  sagda, or sagdo, the, 111.
+  Sanuto, Livio, 5, 153, 167.
+  sapphire, the, 48.
+  scales of iron, 22.
+  Scaliger, Julius Caesar.
+    on cause of magnetick direction, 5, 64, 153.
+    on a fall of meteorick iron, 26.
+    on preservation of loadstones, 37.
+    on amber, 47.
+    on magnetick attraction, 70.
+    admits the loadstone to have a soul, 68.
+    on diamond attracting iron, 112.
+  scoria or slag of iron, 34, 35.
+  sealing wax is electrical, 48, 53.
+  Sebastian Cabot. _See_ Cabot.
+  Serapio, or Serapio Mauritania (Yuhanna ibn Sarapion), 2, 6.
+  Severtius, Jacobus, 5.
+  shielding, magnetick, by iron plate, 83, 85.
+  {246}
+  _siderites_ ([Greek: siderites]) 8, 11, 143.
+  _siegelstein_ 11.
+  silk suspension for magnetick iron, 29, 30.
+  Silvaticus, Matthaeus, 3.
+  silver, loadstone for, 109, 110.
+  similars, doctrine of attraction of, 50, 62.
+  Simon Stevinus, *v _bis_, 167, 168.
+  slate, magnetick properties of, 43.
+  smeargel (emery), 22.
+  Solinus, Caius Julius, 1, 9, 111.
+  Solomon the King, 4.
+  Sotacus, 9.
+  Stadius, 213.
+  stars are at various distances, 215.
+  steel, 23, 39, 69, 71, 93, 95, 147.
+  Stevinus, Simon, *v _bis_, 167, 168.
+  _stomoma_ ([Greek: stomoma]) 23, 33, 36.
+  Strabo, 25.
+  _succinum_. _See_ amber.
+  Sudini, or Sudavienses, 47.
+  sulphur, electrical by friction, 48, 53, 56, 59.
+  [Greek: sundrome], *vj.
+  [Greek: sunentelecheia], 68.
+  Sussex, iron ore in, 22.
+  sympathy and antipathy, 65, 68, 112.
+
+  Tacitus, Cornelius, 25.
+  Taisner, or Taisnier, Joannes, 5, 107.
+  Tariassiona or Tarazona, 23.
+  terrella.
+    definition of, *vj, 12, 13.
+    poles and axis of, 13, 72, 81, 144.
+    divided into two parts, 72.
+    magnetick vigour, diagram of, 74, 75.
+    how small pieces of iron behave toward, 75, 76.
+    orbe of virtue of, 76, 77, 104.
+    "geography" of, 78.
+    aequinoctial circle of, 79, 144.
+    parallels of, 80, 211.
+    magnetick horizon of, 80.
+    proportion of the forces in, 81, 82.
+    experiment with iron sphere, 85.
+      small iron sphere and rod, 94, 102.
+    centre of magnetick virtue in, 95.
+    irregular terrella to exhibit variation, 155, 157.
+    to illustrate the dip of the needle, 190, 192.
+    analogy of, with the earth, 41, 78, 119, 211.
+  testing loadstones, methods of, 108.
+  Thales of Miletus, 11, 61, 68, 208, 210.
+  _theamedes_, the, 18.
+  Thebitius, or Thebit ben Korrah, 117, 236.
+  Themistius, 71.
+  Theophrastus, 1, 9, 11.
+  Thomas Aquinas, 3, 64.
+  tides, the cause of, 86.
+  Tycho Brahe, 174, 229.
+
+  Variation of the compass, 7, 46, 79, 116, 151-163, 166, 167, 180.
+  variation at the Azores, 4, 154, 156, 167.
+  versorium, magnetick, definition of, *vj.
+    use of, 13, 115, 147.
+  versorium, non-magnetick, use of, 48, 49, 50.
+  verticity, 28, 115, 119-147.
+    acquired, 67, 68, 84, 85, 104, 123, 125, 129, 138, 139, 141, 142, 211.
+      in iron plates touched by loadstone, 84.
+      in iron sphere, 85.
+      how, in iron, 123, 139, 212.
+      in bracket in tower of St. Augustine's Church, Rimini, 141.
+      similar at ends of rod touched in middle, 84, 129.
+      by percussion, 139.
+      through interposed matter, 67.
+    not in bodies other than magnetick, 142.
+    aequator separates two kinds of, 79.
+    possessed by the earth, as a "Cause," 117.
+    change of, through change of mass, 72.
+    definition of, *vj.
+    described, 119, 120, 121.
+    destroyed by heat, 66, 93, 124.
+    earth produces it in loadstone and iron, 42, 140, 211, 212.
+    excited through greater distances in iron than in air, 104.
+    exists in all shapes of loadstone, 76.
+    helps the earth to keep its orbit, 224.
+    inhaerent in wrought iron, 31, 115.
+    as a magnetick motion, 46.
+    mutation of, 120, 137.
+    magnitude of earth prevents variation of, 163, 164.
+    none acquired by iron rubbed on aequator of terrella, 148.
+    not affected by position of loadstone, 144.
+    of one loadstone as affected by another, 69, 138.
+    opposite, acquired by iron touched by loadstone, 115, 125, 129.
+    parts having same repel, 122, 133.
+    pole of, where last contact is, 149.
+    strengthened in versoria, 147-150.
+    strength of, decreases at once in both poles, 146.
+  Villa nova, Arnaldus de, 2, 7.
+  vincentina, the, 48.
+  Vincent's Rock, gem of, 54.
+
+  Weather affects electricks, 48, 53, 55, 56.
+  weighing the magnetick force, 108.
+  Wright, Edward, his prefatory address, *iij _bis_, 7.
+  wrought iron is magnetick, 29, 139.
+
+  Youth preserved by loadstone, 32.
+
+  Zeilam, the king of, 32.
+  Zimiri, 11.
+  Zoroaster, 209.
+
+{247} THIS TREATISE BY WILLIAM GILBERT, OF COLCHESTER, PHYSICIAN OF LONDON,
+ON THE MAGNET, WAS FIRST PUBLISHT IN THE LATIN TONGUE IN LONDON IN THE YEAR
+OF OUR LORD M.D.C.; THIS ENGLISH TRANSLATION, WHICH WAS COMPLETED IN THE
+YEAR M.C.M., IS PRINTED FOR THE GILBERT CLUB, TO THE NUMBER OF TWO HUNDRED
+AND FIFTY COPIES, BY CHARLES WHITTINGHAM AND COMPANY, AT THE CHISWICK
+PRESS, TOOKS COURT, CHANCERY LANE, LONDON.
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+NOTES
+
+ON THE
+
+DE MAGNETE
+
+OF
+
+DR. WILLIAM GILBERT
+
+[Illustration]
+
+PRIVATELY PRINTED
+
+LONDON MCMI
+
+  "For out of olde feldes, as men seith,
+  Cometh al this newe corn fro yeer to yere;
+  And out of olde bokes, in good feith,
+  Cometh al this newe science that men lere."
+                          --_Chaucer._
+
+    "I finde that you have vsed in this your tr[=a]slation greate art,
+    knowledge, and discretion. For walking as it were in golden fetters (as
+    al Translators doe) you notwithstanding so warilie follow your Auctor,
+    that where he trippeth you hold him vp, and where he goeth out of the
+    way, you better direct his foote. You haue not only with the Bee sucked
+    out the best iuyce from so sweete a flower, but with the Silke-worme as
+    it were wouen out of your owne bowels, the finest silke; & that which
+    is more, not rude & raw silke, but finely died with the fresh colour of
+    your owne Art, Invention, and Practise. If these Adamantes draw you not
+    to effect this which you haue so happilie begunne: then let these
+    spurres driue you forward: viz. Your owne promise, the expectation of
+    your friends, the losse of some credit if you should steppe backe, the
+    profit which your labours may yeeld to many, the earnest desire which
+    you yourselfe haue to reviue this Arte, and the vndoubted acceptation
+    of your paines, if you performe the same."--(Prefatory epistle of John
+    Case, D. of Physicke, printed in R. Haydocke's translation of _The
+    Artes of Curious Painting_, of Lomatius, Oxford, 1598.)
+
+    "This booke is not for every rude and unconnynge man to see, but for
+    clerkys and very gentylmen that understand gentylness and
+    scyence."--_Caxton._
+
+CHISWICK PRESS: CHARLES WHITTINGHAM AND CO.
+TOOKS COURT, CHANCERY LANE, LONDON.
+
+       *       *       *       *       *
+
+
+{ij}
+
+[Illustration]
+
+BIBLIOGRAPHY OF _DE MAGNETE_.
+
+I. (THE LONDON FOLIO OF 1600.) _Fol. *j. title_ GVILIELMI GIL | berti
+colcestren | sis, medici londi- | nensis, | DE MAGNETE, MAGNETI- | cisqve
+corporibvs, et de mag- | no magnete tellure; Physiologia noua, | plurimis &
+argumentis, & expe- | rimentis demonstrata. | _Printer's Mark_ | Londini |
+excudebat Petrvs Short anno | MDC. || _*j verso_ Gilbert's coat of arms. ||
+_*ij_ Ad Lectorem || _*iij verso_ Ad gravissimvm doctissimvmqve ... ||
+_*vj_ Verborum quorundam interpretatio. || _*vj verso_ Index capitum. || p.
+1. GVILIELMI GILBERTI | DE MAGNETE, LIB. I. || p. 240. FINIS. | Errata.
+Without any colophon, printer's Mark, or date at end. _Folio. 8 ll. of
+preliminary matter._ ABCDEFGHIKLMNOPQRSTV, _all ternions, making 120
+numbered leaves. One blank leaf at front and one at end. Page 114 at end of
+Liber II. blank. A folded woodcut plate inserted between p. 200 and p. 201.
+Woodcut initials, headlines and diagrams. All known copies except one have
+ink corrections in several pages, particularly pp. 11, 22, 47._
+
+II. (THE STETTIN QUARTO OF 1628.) _Four preliminary unnumbered leaves,
+viz._ (1) _Bastard title_ GULIELMI GILBERTI | Tractatus | DE MAGNETE ||
+_verso_ blank; (2) _Engraved title._ TRACTATVS | Siue | PHYSIOLOGIA NOVA |
+DE MAGNETE, | MAGNETICISQVE CORPO- | RIBVS ET MAGNO MAGNETE | tellure Sex
+libris comprehensus | a | Guilielmo Gilberto Colcestrensi, | Medico
+Londinensi | ... Omnia nunc diligenter recognita & emen- | datius quam ante
+in lucem edita, aucta & figu- | ris illustrata opera & studio | Wolfgangi
+LOCHMANS I.U.D. | & Mathemati: | Ad calcem libri adjunctus est Index Capi-
+| tum Rerum et Verborum locupletissimus | EXCVSVS SEDINI | Typis Gotzianis
+Sumptibus | _Ioh: Hallervordij._ | Anno MDC.XXVIII || _verso_ blank; (3)
+Praefatio; (4) Amicorum Acclamationes (verses) || _verso_ blank. _Sig._ A
+Ad Lectorem Candidum. _Sig._ A2 _verso_ Ad Gravissimum Doctissimum[=q]
+Virum. _Sig._ B2 Verborum quorundam interpretatio. _Verso_ blank, followed
+by twelve engraved plates numbered I. to XII. _Sig._ B3 is numbered as p.
+1, and begins GVILIELMI GILBERTI | DE MAGNETE. | LIBER I. _Sig._ C _begins
+as p. 5_; _Sig._ D as p. 13; and so forth. The collation therefore is: 4
+ll. unnumbered, ABCDEFGHIKLMNOPQRSTVXYZAaBbCcDdEeFfGgHhIiKkLlMm, _all
+fours. Pagination ends on_ p. 232, _which has Sig._ H_3 _in error for_
+Hh_3, _being the end of the text. Verso of_ Hh_3 blank. Index capitum
+_begins fol._ [Hh_4] _and_ with Index Verborum _continues to verso of_
+Mm_3. _Last leaf_ [Mm_4] _contains Errata, and instructions to binder to
+place plates: verso_ blank. _Quarto. Woodcut initials and diagrams. Without
+any colophon, printer's Mark, or date at end._ In some copies the engraved
+title differs, having the words _Ioh: Hallervordij._ replaced by the word
+_Authoris_.
+
+{iij} III. (THE STETTIN QUARTO OF 1633.) _Four preliminary unnumbered
+leaves_, viz., (1) _title._ Tractatus, sive Physiologia Nova | de |
+MAGNETE, | Magneticisq; corporibus & magno | Magnate tellure, sex libris
+comprehensus, | a GUILIELMO GILBERTO Colce- | strensi, Medico Londinensi. |
+... Omnia nunc diligenter recognita, & emendatius quam ante | in lucem
+edita, aucta & figuris illustrata, opera & studio D. | WOLFGANGI LOCHMANS,
+I.U.D. | & Mathematici. | Ad calcem libri adiunctus est Index capitum,
+Rerum & Verborum | locupletissimus, qui in priore aeditione desiderabatur |
+SEDINI, | Typis GOTZIANIS. | ANNO M.DC. XXXII. || _verso_ blank; (2)
+Praefatio; (3) Amicorum acclamationes (verses) || _verso_ Claudianus de
+Magnete (verses); (4) _ibid._ _Sig._ A Ad Lectorem Candidum. _Sig._ A2
+_verso_ Ad Gravissimum Doctissimumq. Virum. _Sig._ B2 Verborum quorundam
+interpretatio; _verso_ blank. _Sig._ B3 is numbered as p. 1, and begins
+GVILIELMI GILBERTI | DE MAGNETE. | LIBER I. _Sig._ C begins as p. 5; _Sig._
+D as p. 13; and so forth. The Collation therefore is: 4 _ll._ unnumbered, A
+_to_ Mm, _all fours_. Pagination _ends on p. 232, which bears Sig._ H3 _in
+error for_ Hh3. _Verso of Sig._ Hh3. Errata. Index capitum _begins_ Hh4,
+_and with_ Index Verborum _extends to verso_ of Mm3. _The last leaf_ [Mm4]
+_bears the Instructions to binder, with verso_ blank. _There is no
+colophon, printer's Mark, or date at end. Quarto. Woodcut initials, and
+diagrams. Twelve etched plates of various sizes inserted._
+
+With the exception of the preliminary matter and the Instructions to
+binder, the pagination is the same as in the edition of 1628, the pages in
+the body of the work being reprinted word for word; though with exceptions.
+For example, p. 18 in Ed. 1633 is one line shorter than in Ed. 1628. The
+etched plates are entirely different. It has been thought from the
+pagination being alike that these two editions were really the same with
+different plates, titles, and preliminary matter. But they are really
+different. The spacing of the words, letters and lines is different
+throughout, and there are different misprints. The watermarks of the paper
+also differ.
+
+IV. (THE BERLIN "FACSIMILE" FOLIO OF 1892.) This is a photozincograph
+reproduction of the London folio of 1600. It lacks the ink emendations on
+pages 11, 22, 47, &c., found in the original, and is wanting also in some
+of the asterisks in the margins.
+
+V. (THE AMERICAN TRANSLATION OF 1893.) Frontispiece portrait || _p. i.
+title_ WILLIAM GILBERT | OF COLCHESTER, | physician of London, | on the |
+Loadstone and Magnetic Bodies, | and on | the great magnet the earth. | A
+new Physiology, | demonstrated with many arguments and experiments. | A
+translation by | P. Fleury Mottelay, | ... | New York: | John Wiley & Sons,
+| 53 East Tenth Street | 1893. || _p. ii_ bears imprint of Ferris Bros.
+_Printers_, 326 Pearl Street, New York. || _p. iii._ reduced reproduction
+of title of 1600 edition || _verso_ the Gilbert arms || _p. v._
+Translator's Preface || _p. ix._ Biographical Memoir || _p. xxxi._ Contents
+|| _p. xxxvii._ Address of Edward Wright || _p. xlvii._ Author's Preface.
+|| _p. liii._ Explanation of some terms. || pp. 1-358 text of the work. ||
+p. 359 reduced reproduction of title of 1628 edition. || p. 360 _ditto_ of
+1633 edition. || p. 361 _ditto_ of Gilbert's _De Mundo Nostro_ of 1651. ||
+pp. 363 to 368 General Index. || Pages _xxx_, _xlvi_, _lii_, and 362 are
+blanks. There are no signatures. Octavo. Diagrams reduced from woodcuts of
+the folio of 1600. Some copies bear on title the imprint | London: |
+Bernard Quaritch, | 15 Piccadilly. ||
+
+       *       *       *       *       *
+
+
+{1} [Illustration]
+
+NOTES ON THE _DE MAGNETE_ OF
+DR. WILLIAM GILBERT.
+
+During the work of revising and editing the English translation of _De
+Magnete_, many points came up for discussion, requiring critical
+consideration, and the examination of the writings of contemporary or
+earlier authorities. Discrepancies between the texts of the three known
+editions--the London folio of 1600, and the two Stettin quartos of 1628 and
+1633 respectively--demanded investigation. Passages relating to astrology,
+to pharmacy, to alchemy, to geography, and to navigation, required to be
+referred to persons acquainted with the early literature of those branches.
+Phrases of non-classical Latin, presenting some obscurity, needed
+explanation by scholars of mediaeval writings. Descriptions of magnetical
+experiments needed to be interpreted by persons whose knowledge of
+magnetism enabled them to infer the correct meaning to be assigned to the
+words in the text. In this wise a large amount of miscellaneous criticism
+has been brought to bear, and forms the basis for the following notes. To
+make them available to all students of Gilbert, the references are given to
+page and line both of the Latin folio of 1600 and of the English edition of
+1900. S. P. T.
+
+[1] _THE GLOSSARY:_
+
+Gilbert's glossary is practically an apology for the introduction into the
+Latin language of certain new words, such as the nouns _terrella_,
+_versorium_, and _verticitas_, and the adjectival noun _magneticum_, which
+either did not exist in classical Latin or had not the technical meaning
+which he now assigns to them. His _terrella_, or [Greek: mikroge], as he
+explains in detail on p. 13, is a little magnetic model of the earth, but
+in the glossary he simply defines it as _magnes globosus_. Neither
+_terrella_ nor _versorium_ appears in any Latin dictionary. No older writer
+had used either word, though Peter Peregrinus (_De Magnete_, Augsburg,
+1558) had described experiments with globular loadstones, and pivotted
+magnetic needles suitable for use in a compass had been known for nearly
+three centuries. Yet the pivotted needle was not denominated _versorium_.
+Blondo (_De Ventis_, Venice, 1546) does not use the term. Norman (_The Newe
+Attractiue_, London, 1581) speaks of the "needle or compasse," and of the
+"wyre." Barlowe (_The Navigators Supply_, London, 1597) speaks of {2} the
+"flie," or the "wier." The term _versorium_ (literally, the _turn-about_)
+is Gilbert's own invention. It was at once adopted into the science, and
+appears in the treatises of Cabeus, _Philosophia Magnetica_ (Ferrara,
+1629), and of Kircher, _Magnes sive de Arte Magnetica_ (Coloniae, 1643),
+and other writers of the seventeenth century. Curiously enough, its
+adoption to denote the pivotted magnetic needle led to the growth of an
+erroneous suggestion that the mariners' compass was known to the ancients
+because of the occurrence in the writings of Plautus of the term
+_versoriam_, or _vorsoriam_. This appears twice as the accusative case of a
+feminine noun _versoria_, or _vorsoria_, which was used to denote part of
+the gear of a ship used in tacking-about. Forcellini defines _versoria_ as
+"funiculus quo extremus veli angulus religatur"; while _versoriam capere_
+is equivalent to "reverti," or (metaphorically) "sententiam mutare." The
+two passages in Plautus are:
+
+  EUT.  Si huc item properes, ut istuc properas, facias rectius,
+        Huc secundus ventus nunc est; cape modo vorsoriam;
+        Hic Favonius serenu'st, istic Auster imbricus:
+        Hic facit tranquillitatem, iste omnes fluctus conciet.
+              (in _Mercat._ Act. V., sc. 2.)
+
+  CHARM.  Stasime, fac te propere celerem recipe te ad dominum domum;
+          . . . . . . . . . . . . . . . . . .
+          . . . . . . . . . . . . . . . . . .
+          . . . . . . . . . . . . . . . . Cape vorsoriam
+          Recipe te ad herum.
+              (in _Trinum._ Act. IV., sc. 3.)
+
+The word _magneticum_ is also of Gilbert's own coinage, as a noun; as an
+adjective it had been certainly used before, at least in its English form,
+_magneticall_, which appears on the title-page of William Borough's
+_Discourse of the Variation of the Compasse_ (London, 1596). Gilbert does
+not use anywhere the noun _magnetismus_, _magnetism_. The first use of that
+noun occurs in William Barlowe's _Magneticall Aduertisements_ (1616), in
+the _Epistle Dedicatorie_, wherein, when speaking of Dr. Gilbert, he says
+"vnto whom I communicated what I had obserued of my selfe, and what I had
+built vpon his foundation of the _Magnetisme_ of the earth." Gilbert speaks
+of the _virtus magnetica_, or _vis magnetica_; indeed, he has a rich
+vocabulary of terms, using, beside _virtus_ and _vis_, _vires_, _robur_,
+_potestas_, _potentia_, _efficientia_, and _vigor_ for that which we should
+now call _magnetism_ or _the magnetic forces_. Nor does he use the verb
+_magnetisare_, or its participle, _magnetisatus_: he speaks of _ferrum
+tactum_, or of _ferrum excitatum a magnete_. In spite of certain
+obscurities which occur in places in his work, he certainly shows a nice
+appreciation of words and their use, and a knowledge of style. One finds
+occasionally direct quotations from, and overt references to, the classic
+authors, as in the references to Plato and Aristotle on page 1, and in the
+passage from the Georgics of Vergil on p. 21. But here and there one finds
+other traces of unmistakable scholarship, as in the reference to goat's
+wool on p. 35, or in the use, on p. 210, of the word _perplacet_, which
+occurs in the letter of Cicero _ad Atticum_, or in that of _commonstrabit_,
+occurring on p. 203, and found only in Cicero, Terence and Plautus; whilst
+the phrase on p. 3, in which Gilbert rallies the smatterers on having lost
+both their oil and their pains, has a delightfully classical echo. {3} The
+term _orbis virtutis_, defined by Gilbert in the glossary, and illustrated
+by the cuts on pages 76, 77, and 96, might be effectively translated by
+_sphere of influence_, or _orbit within which there is sensible
+attraction_. It has been preferred, however, to translate it literally as
+the _orbe of virtue_, or _orbe of magnetick virtue_. This choice has been
+determined by the desire to adopt such an English phrase as Gilbert would
+himself have used had he been writing English. T. Hood, writing in 1592 in
+his book _The Vse of both the Globes_, in using the word _orbe_, says that
+the word _globe_ signifies a solid body, while a _sphere_ is hollow, like
+two "dishes joyned by the brimme"; "The Latines properly call _Orbis_ an
+Orbe"; "Moreouer the word _Sphaera_ signifieth that instrument made of
+brasen hoopes (wee call it commonly a ringed Sphere) wherewith the
+Astronomers deliuer unto the nouices of that Science the vnderstanding of
+things which they imagine in the heauen." Further, Dr. Marke Ridley in his
+_Treatise of Magneticall Bodies and Motions_ (1613), has a chapter (XIIII)
+"Of the distance and Orbe of the Magnets vertue," throughout which the term
+Orbe is retained. Sir Thomas Browne also writes of "the orb of their
+activities."
+
+The word _Coitio_, used by Gilbert for the mutual force between magnet and
+iron, has been retained in its English form, _coition_. Gilbert evidently
+adopted this term after much thought. The Newtonian conception of action
+and reaction being necessarily equal had not dawned upon the mediaeval
+philosophers. The term _attraction_ had been used in a limited sense to
+connote an action in which a force was conceived of as being exerted on one
+side only. Diogenes of Apollonia, Alexander Aphrodiseus, Democritus, and
+others, conceived the magnet to draw at the iron without the iron in any
+way contributing to that action. Saint Basil specially affirms that the
+magnet is not drawn by iron. On the other hand, Albertus Magnus had
+conceived the idea that the iron sought the magnet by a one-sided effort in
+which the magnet took no part. Gilbert had the wit to discern that the
+action was mutual, and to mark the new conception he adopted the new term,
+and defined it as it stands in his glossary. It is "a concourse or
+concordancy of both," and to emphasize his meaning he adds, "not as if
+there were an [Greek: helktike dunamis] but a [Greek: sundrome]" not a
+tractile power, but a running together. The adjective [Greek: helktike] is
+obviously related to the verb [Greek: helko], I draw: but its meaning
+puzzled the subsequent editors of the text, for in the two Stettin editions
+of 1628 and 1633, the phrase appears in the respective forms of [Greek:
+heletike dunamis] and [Greek: helkustike dunamis]. In Creech's English
+version of Lucretius (edition of 1722, p. 72a, in the footnote) is the
+commentary "Galen, disputing against Epicurus, uses the term [Greek:
+helkein], which seems likewise too violent." It may be noted that the same
+verb occurs in the passage from the _Io_ of Plato quoted below. The term
+[Greek: sundrome] applied by Gilbert to explain his term _Coitio_ is used
+by Diodorus for the mutual onset of two hostile forces.
+
+A picturesque sentence from Sir Thomas Browne's _Pseudodoxia Epidemica_
+(London, 1650, p. 51) sets the matter succinctly forth. "If in two skiffs
+of cork, a Loadstone and Steel be placed within the orb of their
+activities, the one doth not move the other standing still, but both hoist
+sayle and steer unto each other; so that if the Loadstone attract, the
+Steel hath also its attraction; for in this action the Alliency is
+reciprocall, which jointly felt, they mutually approach and run into each
+others arms." {4} The page and line references given in these notes are in
+all cases first to the Latin edition of 1600, and secondly to the English
+edition of 1900.
+
+[2] PAGE 1, LINE 28. Page 1, line 28. _Plato in Ione._--The passage in the
+_Io_ of Plato is in chap. v. Socrates addressing the poet Io tells him that
+his facility in reciting Homer is not really an art: [Greek: theia de
+dunamis, he se kinei hosper en tei lithoi, hen Euripides men Magnetin
+onomasen, hoi de polloi Herakleian. kai gar aute he lithos ou monon autous
+tous daktulious agei tous siderous, alla kai dunamin entithesi tois
+daktuliois, ost au dunasthai tautou touto poiein, hoper he lithos, allous
+agein daktulious, host' enioth' hormathos makros panu siderion kai
+daktulion ex allelon ertetai pasi de toutois ex ekeines tes lithou he
+dunamis anertetai.] The idea is that as the loadstone in attracting an iron
+ring will make it into a magnet, which can in turn act magnetically on
+another ring, and this on yet another, so the inspiration of the Muse is
+transferred to the poet, who in turn hands on the inspiration through the
+reciter to the listener. After further expanding the same idea of the
+transference of influence, Socrates again mentions the magnet (chap. vii.):
+[Greek: Oisth' oun hoti outos estin ho theates ton daktulion ho eschatos,
+hon ego elegon hupo tes Herakleiotidos lithou ap' allelon ten dunamin
+lambanein, ho de mesos su ho rhapsodos kai hupokrites, ho de protos autos
+ho poietes? ho de theos dia panton touton helkei ten psuchen hopoi an
+bouletai ton anthropon, k.t.l.] (Edition Didot of 1856, vol. i., p. 391; or
+Stephanus, p. 533 D).
+
+There is another reference in Plato to the magnet, namely, in the _Timaeus_
+(p. 240, vol. ii., Edit. citat.). See the Note to p. 61.
+
+The reference by Euripides to the magnet occurs in the lost play of Oeneus,
+in a fragment preserved by Suidas. See _Fragmenta Euripidis_ (Ed. Didot,
+1846, p. 757, or Nauck's edition, No. 567).
+
+[Greek: hos Euripides en Oinei; tas broton gnomas skopon, hoste Magnetis
+lithos ten doxan helkei kai methistesin palin.]
+
+[3] PAGE 1, LINE 28. Page 1, line 29. The brief passage from Aristotle's
+_De Anima_ referring to Thales is quoted by Gilbert himself at the bottom
+of p. 11.
+
+[4] PAGE 2, LINE 1. Page 1, line 29. The edition of 1628 inserts commas
+between Theophrastus and Lesbius, and between Julius and Solinus, as though
+these were four persons instead of two.
+
+[5] PAGE 2, LINE 8. Page 2, line 5. _si allio magnes illitus fuerit, aut si
+adamas fuerit_. An excellent version of this myth is to be found in Julius
+Solinus, _Polyhistor, De Memorabilibus_, chap. lxiv., of which the English
+version of 1587, by A. Golding, runs thus: "The Diamonde will not suffer
+the Lodestone to drawe yron unto him: or if y^e Lodestone haue alreadie
+drawne a peece of yron to it, the Diamond snatcheth and pulleth away as hys
+bootye whatsoever the Lodestone hath taken hold of." Saint Augustine
+repeats the diamond myth in his _De Civitate Dei_, lib. xxi. Baptista Porta
+says (p. 211 of the English version of 1658): "It is a common Opinion
+amongst Sea-men, That Onyons and Garlick are at odds with the Loadstone:
+and Steers-men, and such as tend the Mariners Card are forbid to eat Onyons
+or Garlick, lest they make the Index of the Poles drunk. But when I tried
+all these things, found them to be false: for not onely breathing and
+belching upon the Loadstone after eating of Garlick, did not stop its
+vertues: but when it was all anoynted over with the juice of Garlick, it
+did perform its office as well as if it had never been touched with it: and
+I could observe almost not the least difference, lest I should make void
+the endeavours of the Ancients. {5} And again, When I enquired of Marines,
+whether it were so, that they were forbid to eat Onyons and Garlick for
+that reason; they said, they were old Wives fables, and things ridiculous;
+and that Sea-men would sooner lose their lives, then abstain from eating
+Onyons and Garlick."
+
+The fables respecting the antipathy of garlick and of the diamond to the
+operation of the magnet, although already discredited by Ruellius and by
+Porta, died hard. In spite of the exposure and denunciations of
+Gilbert--compare p. 32--these tales were oft repeated during the succeeding
+century. In the appendix to Sir Hugh Plat's _Jewel House of Art and
+Nature_, in the edition of 1653, by D. B. Gent, it is stated there (p.
+218): "The Loadstone which ... hath an admirable vertue not onely to draw
+Iron to it self, but also to make any Iron upon which it is rubbed to draw
+iron also, it is written notwithstanding, that being rubbed with the juyce
+of Garlick, it loseth that vertue, and cannot then draw iron, as likewise
+if a Diamond be layed close unto it."
+
+Pliny wrote of the alleged antipathy between diamond and goat's blood. The
+passage as quoted from the English version of Pliny's _Natural Historie of
+the World_, translated by Philemon Holland (London, 1601, p. 610, chap,
+iv.), runs: "But I would gladly know whose invention this might be to soake
+the Diamond in Goats bloud, whose head devised it first, or rather by what
+chance was it found out and knowne? What conjecture should lead a man to
+make an experiment of such a singular and admirable secret, especially in a
+goat, the filthiest beast ... in the whole world? Certes I must ascribe
+both this invention and all such like to the might and beneficence together
+of the divine powers: neither are we to argue and reason how and why Nature
+hath done this or that? Sufficient is it that her will was so, and thus she
+would have it."
+
+[6] PAGE 2, LINE 22. Page 2, line 22. _Machometis sacellum._ Gilbert
+credits Matthiolus (the well-known herbalist and commentator on
+Dioscorides) with producing the fable as to Mahomet's coffin being
+suspended in the air by a magnet. Sir Richard Burton, in his famous
+pilgrimage to El Medinah in 1855, effectually disposed of this myth. The
+reputed sarcophagus rests simply on bricks on the floor. But it had long
+been known that aerial suspension, even of the lightest iron object, in the
+air, without contact above or below, was impossible by any magnetic agency.
+
+In Barlowe's _Magneticall Aduertisements_ (London, 1616, p. 45) is the
+following: "As for the Turkes _Mahomet_, hanging in the ayer with his yron
+chest it is a most grosse untruth, and utterly impossible it is for any
+thing to hange in the ayer by any _magneticall_ power, but that either it
+must touch the stone it selfe, or else some intermediate body, that
+hindreth it from comming to the stone (like as before I haue shewed) or
+else some stay below to keepe it from ascending, as some small wier that
+may scantly bee seene or perceived."
+
+[7] PAGE 2, LINE 26. Page 2, line 26. _Arsinoes templum._--The account in
+Pliny of the magnetic suspension of the statue of Arsinoe in the temple
+built by Chinocrates is given as follows in the English version (London,
+1601) of Philemon Holland (p. 515): "And here I cannot chuse but acquaint
+you with the singular invention of that great architect and master deviser,
+of Alexandria in Aegypt _Dinocrates_, who began to make the arched roufe of
+the temple of _Arsinoe_ all of Magnet or this Loadstone, to the end, that
+within that temple the statue of the said princesse made of yron, might
+seeme to hang in the aire by nothing. But prevented he was by death {6}
+before hee could finish his worke, like as king _Ptolomaee_ also, who
+ordained that temple to be built in the honour of the said _Arsinoe_ his
+sister."
+
+There are a number of similar myths in Ausonius, Claudian, and Cassiodorus,
+and in the writings of later ecclesiastical historians, such as Rusinus and
+Prosper Aquitanus. The very meagre accounts they have left, and the
+scattered references to the reputed magical powers of the loadstone,
+suggest that there existed amongst the primitive religions of mankind a
+_magnet-worship_, of which these records are traces.
+
+[8] PAGE 2, LINE 37. Page 2, line 41. _Brasevolus_ [or _Brasavola_].--The
+list of authorities here cited consists mostly of well-known mediaeval
+writers on _materia medica_ or on minerals: the last on the list, _Hannibal
+Rosetius Calaber_, has not been identified.
+
+The following are the references in the order named by Gilbert:
+
+Antonio Musa Brasavola. _Examen omnium simplicium medicamentorum_, Section
+447 (Lugdun., 1537).
+
+Joannes Baptista Montanus. _Metaphrasis summaria eorum quae ad
+medicamentorum doctrina attinet_ (Augustae Rheticae, 1551).
+
+Amatus Lusitanus. _Amati Lusitani in Dioscoridis Anazarbei de materia
+medica libros quinque_ (Venet., 1557, p. 507).
+
+Oribasius. _Oribasii Sardiani ad Eunapium libri 4 quibus ... facultates
+simplicium ... continentur_ (Venet., 1558).
+
+Aetius Amidenus. _Aetii Amideni Librorum medicinalium ... libri octo nunc
+primum in lucem editi_ (Greek text, Aldine edition, Venet., 1534). A Latin
+edition appeared in Basel, 1535. See also his _tetrabiblos ex veteribus
+medicinae_ (Basil., 1542).
+
+Avicenna (Ibn Sina). _Canona Medicinae_ (Venice, 1486), liber ii., cap.
+474.
+
+Serapio Mauritanus (Yuhanna Ibn Sarapion). In hoc volumine continentur ...
+_Ioan. Sarapionis Arabis de Simplicibus Medicinis opus praeclarum et ingens
+..._ (edited by Brunfels, Argentorati, 1531, p. 260).
+
+Hali Abbas ('Ali Ibn Al 'Abb[=a]s). _Liber totius medicinae necessaria
+c[=o]tinens ... quem Haly filius Abbas edidit ... et a Stephano ex arabica
+lingua reductus_ (Lugd., 1523, p. 176 _verso_).
+
+Santes de Ardoniis (or Ardoynis). _Incipit liber de venenis quem magister
+santes de ardoynis ... edere cepit venetiis die octauo nou[=e]bris_, 1424
+(Venet., 1492).
+
+Petrus Apponensis (or Petrus de Abano). The loadstone is referred to in two
+works by this author.
+
+(1) _Conciliator differentiarum philosophorum: et precipue medicorum
+clarissimi viri Petri de Abano Patauini feliciter incipit_ (Venet., 1496,
+p. 72, _verso_, Quaestio LI.).
+
+(2) _Tractatus de Venenis_ (Roma, 1490, cap. xi.).
+
+Marcellus (called Marcellus Empiricus). _De Medicamentis_, in the volume
+_Medici antiqui omnes_ (Venet., 1547, p. 89).
+
+Arnaldus (Arnaldus de Villa Nova). _Incipit Tractatus de virtutibus
+herbarum_ (Venet., 1499). See also _Arnaldi Villanovani Opera omnia_
+(Basil., 1585).
+
+Marbodeus Gallus. _Marbodei Galli poetae vetustissimi de lapidibus
+pretiosis Enchiridion_ (Friburgi, 1530 [1531], p. 41).
+
+Albertus Magnus. _De Mineralibus et rebus metallicis_ (Venet., 1542, lib.
+ii., _de lapidibus preciosis_, p. 192). There is a reference to the
+loadstone {7} also in a work attributed falsely to Albertus, but now
+ascribed to Henricus de Saxonia, _De virtutibus herbarum, de virtutibus
+lapidum_, etc. (Rouen, 1500, and subsequent editions). An English version,
+_The Secrets of Albertus Magnus of the vertues of hearbs stones and
+certaine beasts_ was publisht in London in 1617.
+
+Matthaeus Silvaticus. _Pandectae Medicinae_ (Lugduni, 1541, cap. 446).
+
+Hermolaus Barbarus. His work, _Hermolai Barbari Patritii Veneti et
+Aqvileiensis patriarchae Corollarii Libri quinque ..._ Venet., 1516, is an
+early herbal. On p. 103 are to be found descriptions of _lapis gagatis_ and
+_lapis magnes_. The latter is mostly taken from Pliny, and mentions the
+alleged theamedes, and the myth of the floating statue.
+
+Camillus Leonardus. _Speculum Lapidum_ (Venet., 1502, fol. xxxviii.). An
+English translation, _The Mirror of Stones_, appeared in London in 1750.
+
+Cornelius Agrippa. _Henrici Cor. Agrippae ab Nettesheym ... De Occulta
+Philosophia Libri Tres_ (Antv., 1531). The English version _Of the Vanitie
+and uncertaintie of Artes_ was publisht in London, 1569, and again later.
+
+Fallopius (Gabriellus). _G. F. de simplicibus medicamentis purgantibus
+tractatus_ (Venet., 1566). See also his _Tractatus de compositione
+medicamentorum_ (Venet., 1570).
+
+Johannes Langius. _Epistolarum medicinalium volumen tripartitum_ (Paris,
+1589, p. 792).
+
+Cardinalis Cusanus (Nicolas Khrypffs, Cardinal de Cusa). _Nicolai Cusani de
+staticis experimentis dialogus_ (Argentorati, 1550). The English edition,
+entitled _The Idiot in four books_, is dated London, 1650.
+
+[9] PAGE 3, LINE 1. Page 2, line 42. _Marcellus_.--"Marcellus Empiricus,
+medecin de Theodose-le-Grand, dit que l'aimant, appele _antiphyson_, attire
+et repousse le fer." (Klaproth, _Sur l'invention de la boussole_, 1834, p.
+12.) The passage from Marcellus runs: "Magnetes lapis, qui antiphyson
+dicitur, qui ferrum trahit et abjicit, et magnetes lapis qui sanguinem
+emittit et ferrum ad se trahit, collo alligati aut circa caput dolori
+capitis medentur." (Marcellus, _de Medicamentis_: in the volume _Medici
+antiqui omnes, qui latinis literis morborum genera persecuti sunt_. Venet.,
+1547, p. 89.)
+
+[10] PAGE 3, LINE 11. Page 3, line 9. _Thomas Erastus_.--The work in
+question is _Dispvtationvm de Medicina nova Philippi Paracelsi, Pars Prima:
+in qua quae de remediis svperstitiosis & Magicis curationibus ille
+prodidit, praecipue examinantur a Thoma Erasto in Schola Heydebergensi,
+professore_. (Basiliae, 1572. Parts 2 and 3 appeared the same year, and
+Part 4 in 1573.)
+
+Gilbert had no more love for Paracelsus than for Albertus Magnus or others
+of the magic-mongers. Indeed the few passages in Paracelsus on the magnet
+are sorry stuff. They will mostly be found in the seventh volume of his
+collected works (_Opera omnia_, Frankfurt, 1603). A sample may be taken
+from the English work publisht in London, 1650, with the title: _Of the
+Nature of Things, Nine Books; written by Philipp Theophrastus of Hohenheim,
+called Paracelsvs_.
+
+"For any Loadstone that Mercury hath but touched, or which hath been
+smeered with Mercuriall oyle, or only put into Mercury will never draw Iron
+more" (p. 23).
+
+"The life of the Loadstone is the spirit of Iron; which may bee extracted,
+and taken away with spirit of Wine" (p. 32).
+
+[11] PAGE 3, LINE 13. Page 3, line 11. _Encelius_ (or _Entzelt_, Christoph)
+{8} wrote a work publisht in 1551 at Frankfurt, with the title _De re
+metallica, hoc est, de origine, varietate, et natura corporum metallicorum,
+lapidum, gemmarum, atque aliarum quae ex fodinis eruuntur, rerum, ad
+medicine usum deservientium, libri iii_. This is written in a singular
+medley of Latin and German. Gilbert undoubtedly took from it many of his
+ideas about the properties of metals. See the note to p. 27 on _plumbum
+album_.
+
+[12] PAGE 3, LINE 20. Page 3, line 21. _Thomas Aquinas._--The reference is
+to his commentaries upon the _Physica_ of Aristotle. The passage will be
+found on p. 96 _bis_ of the Giunta edition (Venet., 1539). The essential
+part is quoted by Gilbert himself on p. 64.
+
+[13] PAGE 3, LINE 39. Page 3, line 45. _pyxidem._--The word _pyxis_, which
+occurs here, and in the next sentence as _pyxidem nauticam_, is translated
+_compass_. Eleven lines lower occurs the term _nautica pyxidula_. This
+latter word, literally the "little compass," certainly refers to the
+portable compass used at sea. Compare several passages in Book IV. where a
+contrasting use is made of these terms; for example, on pp. 177 and 202.
+Calcagninus, _De re nautica_, uses the term _pyxidecula_ for an instrument
+which he describes as "vitro intecta." On p. 152, line 9, Gilbert uses the
+non-classical noun _compassus_, "boreale lilium compassi (quod Boream
+respicit)," and again on p. 178, line 3.
+
+[14] PAGE 4, LINE 2. Page 4, line 2. _Melphitani._--The inhabitants of
+Amalfi in the kingdom of Naples. The claim of the discovery or invention of
+the mariners' compass in the year 1302 by one Joannes Goia, or Gioia, also
+named as Flavio Goia, has been much disputed. In Guthrie's _New System of
+Modern Geography_ (London, 1792, p. 1036), in the Chronology, is set down
+for the year 1302:
+
+"The mariner's compass invented, or improved by Givia, of Naples. The
+flower de luce, the arms of the Duke of Anjou, then King of Naples, was
+placed by him at the point of the needle, in compliment to that prince."
+
+In 1808 an elaborate treatise was printed at Naples, by Flaminius Venanson
+with the title, _De l'invention de la Boussole Nautique_. Venanson, who
+cites many authorities, endeavours to prove that if Gioia did not discover
+magnetic polarity he at least invented the compass, that is to say, he
+pivotted the magnetic needle and placed it in a box, with a card affixed
+above it divided into sixteen parts bearing the names of the sixteen
+principal winds. He alleges in proof that the compass-card is emblazoned in
+the armorial bearings of the city of Amalfi. This view was combatted in the
+famous letter of Klaproth to Humboldt publisht in Paris in 1834. He shows
+that the use of the magnetized needle was known in Europe toward the end of
+the twelfth century; that the Chinese knew of it and used it for finding
+the way on land still earlier; that there is no compass-card in the arms of
+the city of Amalfi; but he concedes that Gioia may have improved the
+compass in 1302 by adding the wind-rose card. The most recent contributions
+to the question are a pamphlet by Signorelli, _Sull' invenzione della
+Bussola nautica, ragionamento di Pietro Napoli Signorelli, segretario
+perpetuo della Societa Pontaniana; letto nella seduta del 30 settembre
+1860_; Matteo Camera's _Memorie Storico-diplomatiche dell' antica citta e
+ducato di Amalfi_ (Salerno, 1876); and Admiral Luigi Fincati's work _Il
+Magnete, la Calamita, e la Bussola_ (Roma, 1878). An older mention of Gioia
+is to be found in Blundevile's _Exercises_ (3rd edition, 1606, pp.
+257-258). See also Crescentio _della Nautica Mediterranea_, (Roma, 1607, p.
+253), and Azuni, _Dissertazione sull' origine della bussola nautica_
+(Venezia, 1797). {9}
+
+There appears to be a slip in Gilbert's reference to Andrea Doria, as he
+has confounded the town of Amalfi in Principato Citra with Melfi in
+Basilicata.
+
+One of the sources relied upon by historians for ascribing this origin of
+the compass is the _Compendia dell' Istoria del Regno di Napoli_, of
+Collenuccio (Venet., MDXCI.), p. 5.
+
+"Ne in questo tacero Amalfi, picciola terra, & capo della costa di
+Picentia, alia quale tutti quelli, che'l mar caualcano, vfficiosamente
+eterno gratie debono referire, essendo prima in quella terra trovato l'vso,
+& l'artificio della calamita, & del bussolo, col quale i nauiganti, la
+stella Tramontana infallibilmente mirando, direzzano il lor corso, si come
+e publica fama, & gli Amalfitani si gloriano, ne senza ragione dalli piu si
+crede, essendo cosa certa, che gli antichi tale instromento non hebbero; ne
+essendo mai in tutto falso quello, che in molto tempo e da molti si
+diuolga."
+
+Another account is to be found in the _Historiarum sui temporis_, etc., of
+Paulus Jovius (Florent., 1552), tom. ii., cap. 25, p. 42.
+
+"Quum essem apud Philippum superuenit Ioachinus Leuantius Ligur a Lotrechio
+missus, qui deposceret captiuos; sed ille negauit se daturum, quando eos ad
+ipsum Andream Auriam ammirantem deducendos esse iudicaret. Vgonis uero
+cadauer, ut illudentium Barbarorum contumeliis eriperetur, ad Amalphim
+urbem delatum est, in aedeque Andreae apostoli, tumultuariis exequiis
+tumulatum. In hac urbe citriorum & medicorum odoratis nemoribus aeque
+peramoena & celebri, Magnetis usum nauigantibus hodie familiarem &
+necessarium, adinuentum suisse incolae asserunt."
+
+Flavius Blondus, whom Gilbert cites, gives the following reference, in
+which Gioia's name is not mentioned, in the section upon Campania Felix of
+his Italy (_Blondi Flavii Forlinensis ... Italia Illustrata_, Basiliae,
+1531, p. 420).
+
+"Sed fama est qua Amalphitanos audiuimus gloriari, magnetis usum, cuius
+adminiculo nauigantes ad arcton diriguntur, Amalphi suisse inuentum,
+quicquid uero habeat in ea re ueritas, certu est id noctu nauigandi
+auxilium priscis omnino suisse incognitum."
+
+There is a further reference to the alleged Amalphian in Caelius
+Calcagninus _De re nautica commentatio_. (_See Thesaurus Graecarum
+Antiquitatum_, 1697, vol. xi., p. 761.) On the other hand Baptista Porta,
+who wrote in Naples in 1558 (_Magia Naturalis_) distinctly sets aside the
+claim as baseless.
+
+William Barlowe, in _The Navigators Supply_ (1597, p. A3), says: "Who was
+the first inuentor of this Instrument miraculous, and endued, as it were,
+with life, can hardly be found. The lame tale of one _Flauius_ at
+_Amelphis_, in the kingdome of _Naples_, for to haue deuised it, is of very
+slender probabilitie. _Pandulph Collenutius_ writing the Neapolitane
+historie telleth vs, that they of _Amelphis_ say, it is a common opinion
+there, that it was first found out among them. But _Polidore Virgil_, who
+searched most diligently for the Inuentors of things, could neuer heare of
+this opinion (yet himselfe being an Italian) and as he confesseth in the
+later ende of his third booke _de inventoribus rerum_, could neuer
+vnderstand anything concerning the first inuention of this instrument."
+
+According to Park Benjamin (_Intellectual Rise in Electricity_, p. 146) the
+use of the pivotted compass arose and spread not from Amalfi at the hands
+of Italians in the fourteenth century, but from Wisbuy, at the hands of the
+Finns, in the middle of the twelfth century. {10}
+
+Hakewill (_An Apologie or Declaration of the Power and Providence of God_,
+London, 1673, pp. 284-285) says:
+
+"But _Blondus_, who is therein followed by _Pancirollus_, both _Italians_,
+will not haue _Italy_ loose the praise thereof, telling vs that about 300
+yeares agoe it was found out at Malphis or Melphis, a Citty in the Kingdome
+of _Naples_ in the _Province_ of _Campania_, now called _Terra di
+Lovorador_. But for the Author of it, the one names him not, and the other
+assures vs, he is not knowne: yet _Salmuth_ out of _Ciezus & Gomara_
+confidently christens him with the name of _Flavius_, and so doth _Du
+Bartas_ in those excellent verses of his touching this subject.
+
+  "'W' are not to _Ceres_ so much bound for bread,
+  Neither to _Bacchus_ for his clusters red,
+  As Signior _Flavio_ to thy witty tryall,
+  For first inventing of the Sea-mans dyall,
+  Th' vse of the needle turning in the same,
+  Divine device, O admirable frame!'
+
+"It may well be then that _Flavius_ the _Melvitan_ was the first inventor
+of guiding the ship by the turning of the needle to the _North_: but some
+_German_ afterwards added to the _Compasse_ the 32 points of the winde in
+his owne language, whence other Nations haue since borrowed it."
+
+[15] PAGE 4, LINE 14. Page 4, line 14. _Paulum Venetum_.--The reference is
+to Marco Polo. He returned in 1295 from his famous voyage to Cathay. But
+the oft-repeated tale that he first introduced the knowledge of the compass
+into Europe on his return is disposed of by several well-established facts.
+Klaproth (_op. citat._, p. 57) adduces a mention of its use in 1240 in the
+Eastern Mediterranean, recorded in a work written in 1242 by Bailak of
+Kibdjak. And the passages in the Iceland Chronicle, and in Alexander of
+Neckham are still earlier.
+
+[16] PAGE 4, LINE 17. Page 4, line 17. _Goropius_. See _Hispanica Ioannis
+Goropii Becani_ (Plantin edition, Antv., 1580), p. 29. This is a discussion
+of the etymologies of the names of the points of the compass: but is quite
+unauthoritative.
+
+[17] PAGE 4, LINE 23. Page 4, line 26. _Paruaim_.--Respecting this
+reference, Sir Philip Magnus has kindly furnisht the following note. A clue
+to the meaning of _Parvaim_, which should be written in English letters
+with a _v_, not a _u_, will be found in _2 Chronicles_, iii. 6. In the
+verse quoted the author speaks of gold as the gold of Parvaim, [Hebrew:
+WHAZAHAB ZHAB PARWAYIM], and [Hebrew: PRWYM] Parvaim is taken as a
+gold-producing region. It is regarded by some as the same as Ophir. The
+word is supposed to be cognate with a Sanskrit word _purva_ signifying
+"prior, anterior, oriental." There is nothing in the root indicating gold.
+A form similar to Parvaim, and also a proper name, is Sepharvaim, found in
+_2 Kings_, xix. 13, and in _Isaiah_, xxxvii. 13, and supposed to be the
+name of a city in Assyria.
+
+[18] PAGE 4, LINE 35. Page 4, line 41. Cabot's observation of the variation
+of the compass is narrated in the _Geografia_ of Livio Sanuto (Vinegia,
+1588, lib. i., fol. 2). See also Fournier's _Hydrographie_, lib. xi., cap.
+10.
+
+[19] PAGE 4, LINE 36. Page 4, line 42. _Gonzalus Oviedus_.--The reference
+is to Gonzalo Fernandez de Oviedo y Valdes. _Summario de la Historia
+general y natural de las Indias occidentales_, 1525, p. 48, where the
+author speaks of the crossing of "la linea del Diametro, donde las Agujas
+hacen la {11} diferencia del Nordestear, o Noroestear, que es el parage de
+las Islas de los Acores."
+
+[20] PAGE 5, LINE 8. Page 5, line 11. _Petri cujusdam Peregrini_.--This
+opusculum is the famous letter of Peter Peregrinus written in 1269, of
+which some twenty manuscript copies exist in various libraries in Oxford,
+Rome, Paris, etc., and of which the oldest printed edition is that of 1558
+(Augsburg). See also Libri, _Histoire des Sciences Mathematiques_ (1838);
+Bertelli in Boncompagni's _Bull. d. Bibliogr._ T. I. and T. IV. (1868 and
+1871), and Hellmann's _Rara Magnetica_ (1898). A summary of the contents of
+Peregrinus's book will be found in Park Benjamin's _Intellectual Rise in
+Electricity_ (1895), pp. 164-185.
+
+[21] PAGE 5, LINE 12. Page 5, line 15. _Johannes Taisner
+Hannonius._--Taisnier, or Taysnier, of Hainault, was a plagiarist who took
+most of the treatise of Peregrinus and publisht it in his _Opusculum... de
+Natura Magnetis_ (Coloniae, 1562), of which an English translation by
+Richard Eden was printed by R. Jugge in 1579.
+
+[22] PAGE 5, LINE 18. Page 5, line 23. _Collegium Conimbricense_.--This is
+a reference to the commentaries on Aristotle by the Jesuits of Coimbra. The
+work is _Colegio de Coimbra da Companhia de Jesu, Cursus Conimbricensis in
+Octo libros Physicorum_ (Coloniae, sumptibus Lazari Ratzneri, 1599). Other
+editions: Lugd. 1594; and Colon., 1596. The later edition of 1609, in the
+British Museum, has the title _Commentariorum Collegii Conimbricensis in
+octo libros physicorum_.
+
+[23] PAGE 5, LINE 25. Page 5, line 31. _Martinus Cortesius_.--His _Arte de
+Navegar_ (Sevilla, 1556) went through various editions in Spanish, Italian,
+and English. Eden's translation was publisht 1561, and again in 1609.
+
+[24] PAGE 5, LINE 26. Page 5, line 33. _Bessardus_.--Toussaincte de Bessard
+wrote a treatise, _Dialogue de la Longitude_ (Rouen, 1574), which gives
+some useful notes of nautical practice, and of the French construction of
+the compass. Speaking of the needle he says: "Elle ne tire pas au pole du
+monde: ains regarde, au Pole du Zodiaque, comme il sera discoursu, cy
+apres" (p. 34). On p. 50 he speaks of "l'aiguille Aymantine." On p. 108 he
+refers to Mercator's _Carte Generale_, and denies the existence of the
+alleged loadstone rock. On p. 15 he gives the most naive etymologies for
+the terms used: thus he assigns as the derivation of _Sud_ the Latin
+_sudor_, because the south is hot, and as that of _Ouest_ that it comes
+from _Ou_ and _Est_. "Come, qui diroit, Ou est-il? a scauoir le Soleil, qui
+estoit nagueres sur la terre."
+
+[25] PAGE 5, LINE 28. Page 5, line 35. _Jacobus Severtius_.--Jacques
+Severt, whose work, _De Orbis Catoptrici sev mapparvm mvndi principiis
+descriptione ac usu libri tres_ (Paris, 1598), would have probably lapsed
+into obscurity, but being just newly publisht was mentioned by Gilbert for
+its follies.
+
+[26] PAGE 5, LINE 30. Page 5, line 38. _Robertus Norman_.--Author of the
+rare volume _The Newe Attractiue_, publisht in London, 1581, and several
+times reprinted. This work contains an account of Norman's discovery of the
+Dip of the magnetic needle, and of his investigation of it by means of the
+Dipping-needle, which he invented. He was a compassmaker of the port of
+London, and lived at Limehouse.
+
+[27] PAGE 5, LINE 32. Page 5, line 40. _Franciscus Maurolycus_.--The work
+to which the myth of the magnetic mountains is thus credited is, _D.
+Francisci Abbatis Messanensis Opuscula Mathematica_, etc. (Venet, MDLXXV,
+p. 122a). "Sed cur sagitta, vel obelus a vero Septentrione, quandoque ad
+dextram, {12} quandoque ad sinistram declinat? An quia sagitta, sicut
+magnes (cuius est simia) non verum Septentrionem, sed insulam quandam (quam
+Olaus Magnus Gothus in sua geographia vocat insulam magnetum) semper ex
+natura inspicere cogitur?"
+
+[28] PAGE 5, LINE 35. Page 5, line 43. _Olaus Magnus_.--The famous
+Archbishop of Upsala, who wrote the history of the northern nations
+(_Historia de Gentibus Septentrionalibus_), of which the best edition,
+illustrated with many woodcuts, appeared in Rome in 1555. An English
+edition entitled _A Compendious History of the Goths, Swedes, and Vandals,
+and Other Northern Nations_ was printed in London in 1658; but it is much
+abbreviated and has none of the quaint woodcuts. The reference on p. 5
+appears to be to the following passage on p. 409 (ed. 1555). "Demum in
+suppolaribus insulis magnetum montes reperiuntur, quorum fragmentis ligna
+fagina certo tempore applicata, in saxeam duritiem, et vim attractivam
+convertuntur," or the following on p. 89: "Magnetes enim in extremo
+Septentrionis veluti montes, unde nautica directio constat, reperiuntur:
+quorum etiam magnetum tam vehemens est operatio, ut certis lignis fagineis
+conjuncti, ea vertunt in sui duritiem, & naturam attractivam." On p. 343 is
+a woodcut depicting the penalties inflicted by the naval laws upon any one
+who should maliciously tamper with the compass or the loadstone, "qui
+malitiose nauticum gnomonem, aut compassum, & praecipue portionem magnetis,
+unde omnium directio dependet, falsaverit." He was to be pinned to the mast
+by a dagger thrust through his hand. It will be noted that the ships
+carried both a compass, and a piece of loadstone wherewith to stroke the
+needle.
+
+There is in the Basel edition of this work, 1567, a note _ad lectorem_, on
+the margin of Carta 16a, as follows:
+
+"Insula 30 milliarium in longitud. & latitud. Polo arctico subjecta.
+
+"Vltra quam directorium nauticum bossolo dic[~u] uires amittit: propterea
+quod ilia insula plena est magnetum."
+
+This myth of the magnetic mountains, probably originating with Nicander,
+appears, possibly from an independent source, in the East, in China, and in
+the tales of the Arabian Nights.
+
+Ptolemy gives the following account in his _Geographia_ (lib. vii., cap.
+2):
+
+[Greek: Pherontai de kai allai sunecheis deka nesoi kaloumenai Maniolai en
+ais phasi ta siderous echonta helous ploia katechesthai, mepote tes
+Herikleias lithou peri autas genomenes, kai dia touto epiourois
+naupegeisthai.] Some editions omit the name of the Manioles from the
+passage.
+
+No two authorities agree as to the place of these alleged magnetic
+mountains. Some place them in the Red Sea. Fracastorio, _De Sympathia et
+Antipathia_, cap. 7 (_Opera omnia_, Giunta edition, 1574, p. 63), gives the
+following reason for the variation of the compass:
+
+"Nos igitur diligentius rem considerates dicimus causam, [~q] perpendiculum
+illud ad polum vertatur, esse montes ferri, & magnetis, qui sub polo sunt,
+vt negociatores affirmant, quorum species per incredibilem distantiam vsque
+ad maria nostra propagata ad perpendiculum vsq;, vbi est magnes, consuetam
+attractionem facit: propter distantiam autem quum debilis sit, non moueret
+quidem magnetem, nisi esset in perpendiculo: quare & si non trahit vsq; ac.
+principium, vnde effluxit, at mouet tam[~e], & propinquiorem facit, quo
+potest. Quod si naues sorte vllae propinquiores sint illis montibus, ferrum
+omne ear[~u] cuellitur, propter quod nauigijs incolae vtuntur clauis
+ligneis astrictis."
+
+In the last chapter of his _De Sympathia_, Fracastorio returns to the
+subject {13} in consequence of some doubts expressed by Giambattista
+Rhamnusio, seeing that the loadstones in the Island of Elba do not sensibly
+deflect the magnet. Fracastorio replies thus (p. 76, _op. citat._):
+
+"Primum igitur vtrum sub Polo sint. Magnetis m[~o]tes, nec ne, sub ambiguo
+relinquamus, scimus enim esse, qui scribat planas magis esse eas regiones,
+de quo Paulus Iouius E[~p]us Nucerinus Lucul[~e]tus historiar[~u] nostri
+t[~e]poris scriptor, circa ea Sarmatiae partem, quae Moscouia n[~u]c
+dicitur, diligent[~e] inquisitionem ab incolis fecit, qui ne eos etia
+inueniri montes retulere, qui Rhyphei ab antiquis dicti sunt: meminimus
+tam[~e] nos quasdam chartas vidisse earum, quas mundi mappas appellat, in
+quibus sub polo montes notati erant (qui Magnetis montes inscripti
+fuerant). Siue igitur sint, siue non sint ij montes, nihil ad nos in
+praesentiarum attinet, quando per montes polo subiectos cathenam illam
+montium intelligimus, qui ad septentrionem spectant tanti, & tam vasti, ac
+Ferri & Magnetis feraces: qui, & si magis distant a nostro mari, [~q] Iluae
+insulae montes, potentiores tamen sunt ad mouendum perpendiculum propter
+abundantiam & copia Ferri, & Magnetis. Fortasse autem, & qui in Ilua est
+Magnes, non multae actionis est in ea minera: multi enim d[~u] in minera
+sunt, minus valent, [~q] extracti, [~q] spirituales species sua habeant
+impedimenta: signum autem parum valere in sua minera Iluae insulae
+Magnetem, [~q] tam propinquus quum sit nauigijs illac praetereuntibus,
+perpendiculum tamen non ad se c[~o]uertit."
+
+Aldrovandi in the _Musaeum Metallicum_ (Bonon., 1648, p. 554) gives another
+version of the fable:
+
+"Nonnulli, animadversa hac Magnetis natura, scripserunt naves, quibus in
+Calecutanam regionem navigatur, clavis ferreis non figi, ob magneticorum
+frequentiam scopulorum, quoniam facile dissolverentur. Sed Garzias in
+Historia Aromatum id fabulosum esse tradidit: quandoquidem plures naues
+Calecutanae regionis, & illius tractus, ferreis clauis iunctas obseruauit:
+immo addidit naues in insulis Maldiuis ligneis quidem clauis copulari, non
+quia a Magnete sibi metuant, sed quoniam ferri inopia laborant."
+
+According to Aldrovandi (p. 563, _op. citat._) the magnetic mountains are
+stated by Sir John Mandeville to be in the region of Pontus.
+
+Lipenius in his _Navigatio Salomonis Ophritica illustrata_ (Witteb., 1660),
+which is a mine of curious learning, in discussing the magnetic mountains
+quotes the reply of Socrates to the inquirer who asked him as to what went
+on in the infernal regions, saying that he had never been there nor had he
+ever met any one who had returned thence.
+
+The loadstone rock figures in several early charts. In Nordenskioeld's
+_Facsimile Atlas_ (Stockholm, 1889) is given a copy of the Map of Johan
+Ruysch from an edition of Ptolemy, publisht in Rome in 1508, which shows
+four islands within the ice-bound Arctic regions. South of these islands
+and at the east of the coast of Greenland is the inscription: _Hic
+compassus navium non tenet, nec naves quae ferrum tenent revertere valent._
+To which (on p. 63) Nordenskioeld adds the comment: _Sagan on magnetberg,
+som skulle draga till sig fartyg foerande jern, aer gamal._ And he recalls
+the reference of Ptolemy to the magnetic rocks in the Manioles. A second
+inscription is added to Ruysch's map in the ornamental margin that borders
+the Arctic islands. _Legere est in libro de inventione fortunati sub polo
+arctico rupem esse excelsam ex lapide magnete 33 miliarium germanorum
+ambitu._ This refers to a matter recorded in Hakluyt's _Principall
+Navigations_ (Lond., 1589, p. 249), namely: "A Testimonie of the learned
+Mathematician, maister John Dee, {14} touching the foresaid voyage of
+Nicholas de Linna. Anno 1360 a frier of Oxford, being a good Astronomer,
+went in companie with others to the most Northren islands of the world, and
+there leaving his company together, he travelled alone, and purposely
+described all the Northern islands, with the indrawing seas: and the record
+thereof at his return he delivered to the king of England. The name of
+which booke is _Inventio Fortunata_ (_aliter fortunae_) _qui liber incipit
+a gradu 54 usq. ad polum_."
+
+The situation of the alleged loadstone rock is thus described by T.
+Blundevile in his _Exercises_ in the chapter entitled _A plaine and full
+description of Peter Plancius his vniuersall Map, seruing both for sea and
+land, and by him lately put foorth in the yeare of our Lord, 1592_....
+Written in our mother tongue by M. Blundeuill, Anno Domini 1594. The
+passage is quoted from p. 253 of the third edition (1606):
+
+"Now betwixt the 72. and 86. degrees of North latitude he setteth downe two
+long Ilands extending from the West towardes the East somewhat beyond the
+first Meridian, and from the saide Meridian more Eastward he setteth downe
+other two long Ilandes ... and hee saith further that right under the North
+pole there is a certaine blacke and most high rocke which hath in circuite
+thirtie and three leagues, which is nintie and nine miles, and that the
+long Iland next to the Pole on the West is the best and most healthfull of
+all the North parts. Next to the foresaide Ilandes more Southward hee
+setteth downe the Ilandes of Crocklande and Groynelande, making them to
+haue a farre longer and more slender shape then all other mappes doe....
+Moreouer at the East end of the last Ilande somewhat to the Southwarde, he
+placeth the Pole of the Lodestone which is called in Latine Magnes, euen as
+Mercator doth in his Mappe who supposing the first Meridian to passe
+through Saint Marie or Saint Michael, which are two of the outermost
+Ilandes of the Azores Eastwarde, placeth the Pole of the stone in the
+seuentie fiue degree of Latitude, but supposing the first Meridian to passe
+through the Ile Coruo, which is the furthest Ile of the Azores Westwarde,
+he placeth the Pole of the Lodestone in the seuentie seuen degree of
+Latitude."
+
+Further, in the chapter on _The Arte of Nauigation_ in the same work (p.
+332, _ed. citat._), Blundevile says:
+
+"But whereas Mercator affirmeth that there should bee a mine or great rocke
+of Adamant, wherunto all other lesser rockes or Needles touched with the
+Lodestone doe incline as to their chiefe fountaine, that opinion seemeth to
+mee verie straunge, for truely I rather beleeue with Robert Norman that the
+properties of the Stone, as well in drawing steele, as in shewing the North
+Pole, are secret vertues given of GOD to that stone for mans necessarie vse
+and behoofe, of which secrete vertues no man is able to shewe the true
+cause."
+
+The following is one of the inscriptions in the compartments of the great
+Chart of Mercator entitled _Ad Usum Navigantium_, published in 1569:
+
+"Testatur Franciscus Diepanus peritissimus nauarchus volubiles libellas,
+magnetis virtute infectas recta mundi polum respicere in insulis C.
+Viridis, Solis, Bonauista, et Maio, cui proxime astipulantur qui in
+Tercera, aut S. Maria (insulae sunt inter Acores) id fieri dicunt, pauci in
+earundem occidentalissima Corvi nomine id contingere opinantur. Quia vero
+locorum longitudinis a communi magnetis et mundi meridiano iustis de causis
+initium sumere oportet, plurium testimonium sequutus primum meridianum per
+dictas C. Viridis insulas protraxi, et quum alibi plus minusque a polo
+deuiante {15} magnete polum aliquum peculiarem esse oporteat quo magnetes
+ex omni mundi parte despiciant, euum hoc quo assignaui loco existere
+adhibita declinatione magnetis Ratisbonae obseruata didici. Supputaui autem
+eius poli situm etiam respectu insulae Corui, ut iuxta extremo primi
+meridiani positus extremi etiam termini, intra quos polum hunc inueniri
+necesse est, conspicui fierent, donec certius aliquod nauclerorum
+obseruatio attulerit."
+
+Not all the map-makers were as frank as Paulus Merula, the author of a
+_Cosmographia Generalis_, printed by Plantin in 1605, at Leyden. For in the
+description of his _tabula universalis_ (_op. citat._ lib. iii., cap. 9) he
+says that he does not believe in the magnetic islands; but that he has put
+them into his chart lest unskilful folk should think that he had been so
+careless as to leave them out!
+
+In the well-known myth of Ogier the Dane, immortalized by William Morris in
+the _Earthly Paradise_ (London, 1869, vol. i., p. 625), the loadstone rock
+is an island in the far North. But this story is not one of the
+Scandinavian sagas, and belongs to the Carlovingian cycle of heroic poems,
+of which the chief is the _Chanson de Roland_; and Ogier le Danois is
+really not a Dane but an _Ardennois_.
+
+In the Middle-High German epic of Kudrun, the adventures of the fleet of
+Queen Hilda when attracted by the loadstone mountain at Givers, in the
+North Sea, are narrated at some length. (See _Kudrun, herausgegeben und
+erklaert von Ernst Martin_. Halle, 1872.) One stanza will serve as a
+sample:
+
+  1126. Ze Givers vor dem berge | lac daz Hilden her.
+        swie guot ir anker waeren, | an daz vinster mer.
+        magneten die steine | heten si gezogen.
+        ir guote segelboume | stuonden alle gebogen.
+
+which may be rendered:
+
+  1126. At Givers before the mountain | lay Hilda's ships by.
+        Though good their anchors were, | upon the murky sea.
+        Magnets the stones were | had drawn them thither.
+        Their good sailing masts | stood all bent together.
+
+Recent magnetic research has shown that while there are no magnetic
+mountains that would account for the declination of the compass in general,
+yet there are minor local variations that can only be accounted for by the
+presence of magnetic reefs or rocks. The reader is referred to the account
+of the magnetic survey of Great Britain in the _Philosophical Transactions_
+(1890) by Professors Ruecker and Thorpe. The well-known rocky peak the
+Riffelhorn above Zermatt, in Switzerland, produces distinct perturbations
+in the direction of the compass within half a mile of its base. Such local
+perturbations are regularly used in Sweden for tracing out the position of
+underground lodes of iron ore. See Thalen, _Sur la Recherche des Mines de
+Fer a l'aide de Mesures magnetiques_ (Soc. Royale des Sciences d'Upsal,
+1877); or B. R. Brough, _The Use of the Magnetic Needle in exploring for
+Iron Ore_ (_Scientific American_, Suppl. No. 608, p. 9708, Aug. 27, 1887).
+
+Quite recently Dr. Henry Wilde, F.R.S., has endeavoured to elucidate the
+deviations of the compass as the result of the configurations of land and
+sea on the globe, by means of a model globe in which the ocean areas are
+covered with thin sheet iron. This apparatus Dr. Wilde calls a
+_Magnetarium_. See _Proc. Roy. Soc._, June, 1890, Jan., 1891, and June,
+1891. {16} An actual magnetic rock exists in Scandinavia, the following
+account of it being given in the _Electrical Review_ of New York, May 3,
+1899:
+
+"The island of Bornholm in the Baltic, which consists of a mass of magnetic
+iron ore, is much feared by mariners. On being sighted they discontinue
+steering by compass, and go instead by lighthouses. Between Bornholm and
+the mainland there is also a dangerous bank of rock under water. It is said
+that the magnetic influence of this ore bank is so powerful that a balanced
+magnetic needle suspended freely in a boat over the bank will take a
+vertical position."
+
+[29] PAGE 5, LINE 35. Page 5, line 43. _Josephus Costa._--This is
+unquestionably a misprint for _Acosta_ (Joseph de), the Jesuit, whose work
+_Historia natural y moral de las Indias_ was publisht at Seville in 1590.
+An Italian edition appeared at Venice in 1596. The English edition,
+translated by E. Grimestone, _The Naturall and Morall Historie of the East
+and West Indies_, was publisht in London in 1604 and 1878. There are in
+Gilbert's book references to two writers of the name of Costa or Costaeus,
+Joannes Costa of Lodi, who edited Galen and Avicenna (see pp. 3 and 62),
+and Filippo Costa of Mantua, who wrote on antidotes and medicaments (see p.
+141). The passage to which Gilbert refers is in Acosta's _Historia_ (ed.
+1590, p. 64).
+
+"Deziame a mi vn piloto muy diestro Portugues [~q] eran quatro puntos en
+todo el orbe, donde se afixaua el aguja con el Norte, y contaualas por sus
+nombres, de que no me acuerdo bien. Vno destos es el paraje de la Isla del
+Cueruo, en las Terceras, o Islas de Acores, como es cosa y a muy sabida.
+Passando di alli a mas altura, Noruestea, que es dezir, [~q] declina al
+Poniente ... que me diga la causa desta efecto?... Porque vn poco de hierro
+de fregarse c[~o] la piedra Iman ...
+
+"Mejor es, como dize Gregorio Theologo, que a la Fe se sujete la razon,
+pues aun en su casa no sabe bien entenderse...."
+
+[30] PAGE 5, LINE 36. Page 5, line 45. _Livius Sanutus._--Livio Sanuto
+publisht at Venice in 1588 a folio work, _Geografia distinta in xii Libri;
+ne' quali, oltre l'esplicatione di nostri luoghi di Tolomeo, della Bussola
+e dell' Aguglia, si dichiarono le provincie ... dell' Africa_. In this work
+all Liber i. (pages 1-13) deals with observations of the compass,
+mentioning Sebastian Cabot, and other navigators. He gives a map of Africa,
+showing the central lakes out of which flow the _Zaires fluvius_ and the
+_Zanberes fluvius_.
+
+[31] PAGE 6, LINE 2. Page 6, line 5. _Fortunius Affaitatus._--The work of
+Affaytatus, _Physicae ac astronomiae considerationes_, was publisht in
+Venice in 1549.
+
+[32] PAGE 6, LINE 3. Page 6, line 6. _Baptista Porta._--The reference is to
+his celebrated _Magia naturalis_, the first edition of which came out in
+1558 at Naples. An English edition, _Natural Magick by John Baptista Porta,
+a Neapolitaine_, was printed in London, 1658. Book seven of this volume
+treats "Of the wonders of the Load-stone." In the proem to this book Porta
+says: "I knew at Venice R. M. Paulus, the Venetian, that was busied in the
+same study: he was Provincial of the Order of servants, but now a most
+worthy Advocate, from whom I not only confess, that I gained something, but
+I glory in it, because of all the men I ever saw, I never saw any man more
+learned, or more ingenious, having obtained the whole body of learning; and
+is not only the Splendor and Ornament of Venice or Italy, but of the whole
+world." The reference is to Fra Paolo Sarpi, better known as the historian
+of the Council of Trent. Sarpi was himself known to Gilbert. {17}
+
+His relations with Gilbert are set forth in the memoir prefixt to the
+edition of his works, _Opere di Fra Paolo Sarpi, Servita_ ... in Helmstat,
+MDCCLXI, p. 83. "Fino a questi giorni continuava il Sarpi a raccorre
+osservazioni sulla declinazione dell' Ago Calamitato; e poi ch' egli,
+atteso il variare di tal declinazione, assurdita alcuna non trovava
+riguardo al pensamento dell' Inglese Guglielmo Gilberto, cioe, che
+l'interno del nostro Globo fosse gran Calamita...." Here follows a
+quotation from a letter of Sarpi to Lescasserio:
+
+"... Unde cuspidem trahi a tanta mole terrena, quae supereminet non absurde
+putavit Gullielmus Gilbertus, et in eo meridiano respicere recta polum,
+cave putes observatorem errasse. Est Vir accuratissimus, et interfuit
+omnibus observationibus, quas plures olim fecimus, et aliquas in sui
+gratiam, et cum arcubus vertici cupreo innitentibus, et cum innatantibus
+aquae, et cum brevibus, et cum longis, quibus modis omnibus et Hierapoli
+usus suit."
+
+Sarpi had correspondence with Gilbert, Bacon, Grotius, and Casaubon. He
+also wrote on magnetism and other topics _in materia di Fisica_, but these
+writings have perisht. He appears to have been the first to recognize that
+fire destroyed the magnetic properties. (See _Fra Paolo Sarpi, the greatest
+of the Venetians_ by the Rev. Alexander Robertson, London, 1894; see also
+the notice of Sarpi in Park Benjamin's _Intellectual Rise in Electricity_.)
+
+[33] PAGE 6, LINE 7. Page 6, line 11.: _R. M. Paulus Venetus_. See
+preceding note.
+
+[34] PAGE 6, LINE 21. Page 6, line 28.: _Franciscus Rueus_.--Francois de la
+Rue, author of _De Gemmis Aliquot_ ... (Paris, 1547). Amongst other fables
+narrated by Rueus is that if a magnet is hung on a balance, when a piece of
+iron is attracted and adheres to the magnet, it adds nothing to the weight!
+
+[35] PAGE 6, LINE 25. Page 6, line 33.: _Serapio_.--This account of the
+magnetic mountains will be found in an early pharmacology printed in 1531
+(Argentorati, G. Ulricher Andlenus), with the title "In hoc volumine
+continetur insignium medicorum Joan. Serapionis Arabis de Simplicibus
+Medicinis opus praeclarum et ingens, Averrois Arabis de eisdem liber
+eximius, Rasis filius Zachariae de eisdem opusculum perutile." It was
+edited by Otho Brunsels. Achilles P. Gasser, in his Appendix to the
+Augsburg edition of Peregrinus, gives a reference to Serapio Mauritanus,
+parte 2, cap. 394, libri _de medicinis compositis._
+
+[36] PAGE 6, LINE 30. Page 6, line 39.: _Olaus Magnus_. See note to p. 5.
+
+[37] PAGE 6, LINE 34. Page 6, line 44.: _Hali Abas_.--A reference is given
+in Gasser's (1558) edition of Peregrinus to Haliabbas Arabs, lib. 2,
+_practicae_ cap. 45, _Regalis Dispositionis Medicinae_. The passage to
+which Gilbert refers is found in the volume _Liber totius medicinae
+necessaria c[=o]tinens ... quem Haly filius Abbas ... edidit ... et a
+Stephano ex arabica lingua reductus_. (Lugd., 1523, 4to.) Liber Primus.
+Practice, Cap xlv. _de speciebus lapidum_, s. 466. "Lapis magnetes filis e
+[=v]tute sadenego: & aiunt q[=m] si teneat^r in manu mitigat [=q] sunt in
+pedib^s ipis dolores ac spasm[=u]."
+
+Mr. A. G. Ellis identifies the noun _sadenegum_ as a Latin corruption of
+the Arabic name of haematite, _shadanaj_.
+
+[38] PAGE 6, LINE 36. Page 6, line 46.: _Pictorius_.--His poem was publisht
+at Basel, 1567. See also note on Marbodaeus, p. 7, line 20, below.
+
+[39] PAGE 6, LINE 36. Page 7, line 1.: _Albertus Magnus_.--Albertus, the
+celebrated Archbishop of Ratisbon, is responsible for propagating sundry of
+the myths of the magnet; and Gilbert never loses a chance of girding at
+him. {18} The following examples are taken from the treatise _De
+mineralibus et rebus metallicis_ (Liber II. _de lapidibus preciosis_),
+Venet., 1542.
+
+p. 171. "Et quod mirabile videtur multis his lapis [adamas] quando Magneti
+supponitur ligat Magnetem et non permittit ipsum ferrum trahere."
+
+p. 193. "Vnctus aut[~e] lapis alleo non trahit, si superponitur ei Adamas
+iterum non attrahit, ita quod paruus Adamas magn[~u] ligat Magnet[~e].
+Inventus aut[~e] est nostris t[~e]poribus Magnes qui ab uno angulo traxit
+ferr[~u] et ab alio fugavit, et hunc Aristot. ponit aliud genus esse
+Magnetis. Narrauit mihi quidam ex nostris sociis experim[~e]tator quod
+uidit Federicum Imperatorem habere Magnetem qui non traxit ferrum, sed
+ferrum uiceuersa traxit lapidem."
+
+The first edition of this work _de mineralibus_ appears to have been
+publisht in Venice as a folio in 1495.
+
+[40] PAGE 7, LINE 9. Page 7, line 15. _Gaudentius Merula_.--This obscure
+passage is from Liber IIII., cap. xxi., _Lapides_, of the work
+_Memorabilium Gaudentii Merulae..._ (Lugd., 1556), where we find:
+
+"Qui magneti vrsae sculpserit imaginem, quado Luna melius illuc aspiciat, &
+filo ferreo susp[~e]derit, compos fiet vrsae caelestis virtutis: verum cum
+Saturni radiis vegetetur, satius fuerit eam imaginem non habere: scribunt
+enim Platonici malos daemones septentrionales esse" (p. 287).
+
+"Trahit autem magnes ferrum ad se, quod ferro sit ordine superior apud
+vrsum" (p. 287).
+
+The almost equally obscure passage in the _De triplici vita_ of Marsiglio
+Ficino (Basil., 1532) runs:
+
+"Videmus in specula nautarum indice poli libratum acum affectum in
+extremitate Magnete moueri ad Vrsam, illuc uidelicet trahente Magnete:
+quoniam & in lapide hoc praeualet uirtus Vrsae, & hinc transfertur in
+ferrum, & ad Vrsam trahit utrunq;. Virtus autem eiusmodi tum ab initio
+infusa est, tum continue Vrsae radijs uegetatur, Forsitan ita se habet
+Succinum ad polum alterum & ad paleas. Sed dic interea, Cur Magnes trahit
+ubiq; ferrum? non quia simile, alioquin & Magnetem Magnes traheret multo
+magis, ferrum[=q]; ferr[=u]: non quia superior in ordine corporum, imo
+superius est lapillo metallum ... Ego autem quum haec explorata hactenus
+habuissem admodum gratulabar, cogitabam[=q]; iuuenis adhuc Magneti pro
+uiribus inscluperet (_sic_) coelestis Vrsae figuram, quando Luna melius
+illuc aspiciat, & ferro t[=u]c filo collo suspendere. Sperabam equidem ita
+demum uirtutis me sideris illius compotem fore," &c. (p. 172).
+
+[41] PAGE 7, LINE 14. Page 7, line 20. _Ruellius_.--Joannes Ruellius wrote
+a herbal _De Natura Stirpium_, Paris, 1536, which contains a very full
+account of amber, and a notice of the magnet (p. 125) and of the fable
+about garlic. But on p. 530 of the same work he ridicules Plutarch for
+recording this very matter.
+
+[42] PAGE 7, LINE 20. Page 7, line 27. _Marbodaeus Gallus_.--This rare
+little book is entitled _Marbodei Galli Poetae vetustissimi de lapidibus
+pretiosis Enchiridion_. It was printed at Paris in 1531. The Freiburg
+edition, also of 1531, has the commentaries of Pictorius. The poem is in
+Latin hexameters. After a preface of twenty-one lines the virtues of stones
+are dealt with, the paragraph beginning with a statement that Evax, king of
+the Arabs, is said to have written to Nero an account of the species, names
+and colours of stones, their place of origin and their potencies; and that
+this work formed the basis of the poem. The alleged magical powers of the
+magnet are recited in Caput I., _Adamas_. Caput XLIII., _Magnes_, gives
+further myths. {19} The commentary of Pictorius gives references to earlier
+writers, Pliny, Dioscorides, Bartholomaeus Anglicus, Solinus, Serapio, and
+to the book _de lapidibus_ erroneously ascribed to Aristotle.
+
+The following is a specimen of the poem of Marbodeus:
+
+  _Magnetes lapis est inuentus apud Trogloditas,_
+  _Qu[=e] lapid[=a] genetrix nihilominus India mittit._
+  _Hic ferruginei cognoscitur esse coloris,_
+  _Et ui naturae uicinum tollere ferrum._
+  _Ededon magus hoc primum fere dic[=i]tur usus,_
+  _Conscius in magica nihil esse potentius arte._
+  _Post illum fertur famosa uenefica Circe_
+  _Hoc in praestigijs magicis specialiter usa._
+
+This poem was reprinted (1854) in Migne's _Patrologia_. In 1799 Johann
+Beckmann issued an annotated variorum edition of Marbodeus (_Marbodi Liber
+Lapidvm sev de Gemmis_..., Goettingae, 1799), in which there is a
+bibliography of the poem, the first edition of which appears to have been
+publisht in 1511, at Vienna, thirteen other editions being described.
+Beckmann adds many illustrative notes, and a notice of the Arabian Evax,
+who is supposed to have written the treatise _de lapidibus_. Not the least
+curious part is a French translation alleged to have been written in 1096,
+of which Chap. XIX. on the Magnet begins thus:
+
+  Magnete trovent Trogodite,
+  En Inde e precieus est ditte.
+  Fer resemble e si le trait,
+  Altresi cum laimant fait.
+  Dendor lama mult durement.
+  Qi lusoit a enchantement.
+  Circe lus a dot mult chere,
+  Cele merveillose forciere, &c.
+
+[43] PAGE 7, LINE 21. Page 7, line 28. _echeneidis._--The _echeneis_, or
+sucking-fish, reputed to have magical or magnetic powers, is mentioned by
+many writers. As an example, see Fracastorio, _De Sympathia et Antipathia_,
+lib. i., cap. 8, _De Echineide, quomodo firmare nauigia possit_ (Giunta
+edition, Venet., 1574, p. 63). For other references to the _Echeneis_ see
+Gaudentius Merula (_op. citat._) p. 209. Also Dr. Walter Charleton,
+_Physiologia Epicuro Gassendo-Charltoniana_ (Lond., 1654), p. 375. Compare
+p. 63, line 3.
+
+[44] PAGE 7, LINE 33. Page 7, line 43. _Thomas Hariotus_, etc.--The four
+Englishmen named were learned men who had contributed to navigation by
+magnetic observations. Harriot's account of his voyage to Virginia is
+printed in Hakluyt's _Voyages_. Robert Hues (or Hood) wrote a treatise _on
+Globes_, the Latin edition of which appeared in 1593 (dedicated to Sir
+Walter Raleigh), and the English edition in 1638. It was republisht by the
+Hakluyt Society, 1889. Edward Wright, the mathematician and writer on
+navigation, also wrote the preface to Gilbert's own book. Abraham Kendall,
+or Abram Kendal was "Portulano," or sailing-master of Sir Robert Dudley's
+ship the _Bear_, and is mentioned in Dudley's _Arcano del Mare_. On the
+return of Dudley's expedition in 1595, he joined Drake's last expedition,
+which sailed that year, and died on the same day as Drake himself, 28
+January, 1596. (See _Hakluyt_, ed. 1809, iv., p. 73.)
+
+[45] PAGE 7, LINE 36. Page 8, line 1. _Guilielmus Borough._--Borough's book
+has the title: _A Discours of the Variation of the Cumpas, or magneticall
+{20} Needle. Wherein is Mathematically shewed, the manner of the
+obseruation, effectes, and application thereof, made by W. B._ And is to be
+annexed to _The Newe Attractive_ of R. N., 1581 (London).
+
+[46] PAGE 7, LINE 37. Page 8, line 2. _Guilielmus Barlo_.--Archdeacon
+William Barlowe (author, in 1616, of the _Magneticall Aduertisements_)
+wrote in 1597 a little work called _The Navigators Supply_. It gives a
+description of the ordinary compass, and also one of a special form of
+meridian compass provided with sights for taking the bearings by the sun.
+
+[47] PAGE 7, LINE 37. Page 8, line 3. _Robertus Normannus_. See Note to p.
+5.
+
+[48] PAGE 8, LINE 14. Page 8, line 21. _illo fabuloso Plinij bubulco_.--The
+following is Pliny's account from Philemon Holland's English version of
+1601 (p. 586): "As for the name Magnes that it hath, it tooke it (as
+_Nicander_ saith) of the first inventor and deviser thereof, who found it
+(by his saying) upon the mountaine Ida (for now it is to be had in all
+other countries, like as in Spaine also;) and (by report) a Neat-heard he
+was: who, as he kept his beasts upon the aforesaid mountaine, might
+perceive as he went up and downe, both the hob-nailes which were on his
+shoes, and also the yron picke or graine of his staffe, to sticke unto the
+said stone."
+
+[49] PAGE 9, LINE 22. Page 9, line 30. _Differentiae priscis ex
+colore_.--Pliny's account of the loadstones of different colours which came
+from different regions is mainly taken from Sotacus. The white magnet,
+which was friable, like pumice, and which did not draw iron, was probably
+simply magnesia. The blue loadstones were the best. See p. 587 of Holland's
+translation of Pliny, London, 1601. St. Isidore (_Originum seu
+Etymologiarum_, lib. xvi., cap. 4) says: "Omnis autem magnes tanta melior
+est, quanto [magis] caeruleus est."
+
+[50] PAGE 10, LINE 29. Page 10, line 42. _Suarcebergo ... Snebergum &
+Annaebergum_.--In the Stettin editions of 1628 and 1633 these are spelled
+_Swarcebergs ... Schnebergum & Annebergum_. The Cordus given as authority
+for these localities is Valerius Cordus, the commentator on Dioscorides.
+
+[51] PAGE 11, LINE 3. Page 11, line 12. _Adriani Gilberti viri
+nobilis_.--"Adrian Gylbert of Sandridge in the Countie of Devon, Gentleman"
+is the description of the person to whom Queen Elizabeth granted a patent
+for the discovery of a North-West passage to China. See Hakluyt's
+_Voyages_, vol. iii., p. 96.
+
+[52] PAGE 11, LINE 17. Page 11, line 28. _Dicitur a Graecis_ [Greek:
+eraklios].--The discussion of the names of the magnet in different
+languages by Gilbert in this place is far from complete. He gives little
+more than is to be found in Pliny. For more complete discussions the reader
+is referred to Buttmann, _Bemerkungen ueber die Benennungen einiger
+Mineralien bei den Alten, vorzueglich des Magnetes und des Basaltes_
+(Musaeum der Alterthumswissenschaft, Bd. II., pp. 5-52, and 102-104, 1808);
+G. Fournier, _Hydrographie_ (livre xi., chap. I, 1643); Ulisse Aldrovandi,
+_Musaeum Metallicum_ (Bononiae, 1648, lib. iv., cap. 2, p. 554); Klaproth,
+_Lettre a M. le Baron A. de Humboldt, sur l'invention de la Boussole_,
+Paris, 1834; T. S. Davies, _The History of Magnetical Discovery_ (Thomson's
+_British Annual_, 1837, pp. 250-257); Th. Henri Martin, _De l'Aimant, de
+ses noms divers et de ses varietes suivant les Anciens_ (Memoires presentes
+par divers savants a l'Academie des Inscriptions et Belles-lettres, I^{re}
+serie, t. vi., I^{re} partie, 1861); G. A. Palm, _Der Magnet in Alterthum_
+(Programm des k. wuerttembergischen Seminars Maulbronn, Stuttgart, {21}
+1867). Of these works, those of Klaproth and of Martin are by far the most
+important. Klaproth states that in modern Greek, in addition to the name
+[Greek: magnetis], the magnet also has the names [Greek: adamas] and
+[Greek: kalamita]. The former of these, in various forms, _adamas_,
+_adamant_, _aimant_, _yman_, and _piedramon_, has gone into many languages.
+Originally the word [Greek: adamas] (the unconquered) was applied by the
+Greeks to the hardest of the metals with which they were acquainted, that
+is to say, to hard-tempered iron or steel, and it was subsequently because
+of its root-signification also given by them to the diamond for the same
+reason; it was even given to the henbane because of the deadly properties
+of that plant. In the writings of the middle ages, in St. Augustine, St.
+Isidore, Marbodeus, and even in Pliny, we find some confusion between the
+two uses of _adamas_ to denote the loadstone as well as the diamond.
+Certainly the word _adamas_, without ceasing to be applied to the diamond,
+also designated the loadstone. At the same time (says Martin) the word
+_magnes_ was preserved, as Pliny records, to designate a loadstone of
+lesser strength than the _adamas_. On the other hand, the word _diamas_, or
+_deamans_, had already in the thirteenth century been introduced into Latin
+to signify the diamond as distinguisht from the magnet. _Adamas_ was
+rendered _aymant_ in the romance version of the poem of Marbodeus on stones
+(see Beckmann's variorum edition of 1799, p. 102), and in this form it was
+for a time used to denote both the magnet and the diamond. Then it
+gradually became restricted in use to the stone that attracts iron.
+
+Some confusion has also arisen with respect to the Hebrew name of the
+magnet. Sir W. Snow Harris makes the following statement (_Magnetism_, p.
+5): "In the Talmud it [the loadstone] is termed _achzhab'th_, the stone
+which attracts; and in their ancient prayers it has the European name
+_magn[=e]s_." On this point Dr. A. Loewy has furnisht the following notes.
+The loadstone is termed in one of the Talmudical sections and in the
+Midrash, _Eben Shoebeth_ (lapis attrahens). This would of course be written
+[Hebrew: 'BN SHW'BT]. Omitting the [Hebrew: W] which marks the participial
+construction, the words would stand thus: [Hebrew: 'BN SH'BT] A person
+referring to Buxtorf's _Lexicon_ Talmudicum would in the index look out for
+"Lapis magnesius," or for "magnes." He would then, in the first instance,
+be referred to the two words already quoted. Not knowing the value of the
+letters of the Hebrew alphabet, he reads [Hebrew: 'BN SH'BT] thus: [Hebrew:
+'KZSH'BT] achzhab'th. It is true that Buxtorf has inserted in his _Lexicon_
+the vocable [Hebrew: MAGNIYSEIS], "corruptum ex gr. [Greek: magnes,
+magnetes, magnetis], named after the Asiatic city Magnesia." He goes on to
+say, "Inde Achilles Statius istum lapidem vocavit [Greek: magnesian
+lithon]. Hinc [Hebrew: 'BN HMGNJSS CHMSHWK HBRZL]. Lapis Magnesius trahit
+ferrum." Here he quotes from (Sepher) Ikkarem IV., cap. 35.
+
+Kircher, in his _Magnes, sive de Arte magnetica_ (Coloniae, 1643), gives
+several other references to Hebrew literature. Others have supposed that
+the word [Hebrew: CHLMYSH] _khallamish_, which signifies pebble, rock, or
+hard rock, to be used for the magnet.
+
+As to the other Greek name, [Greek: sideritis], or [Greek: lithos
+sideritis] this was given not only to the loadstone but also to
+non-magnetic iron. In the _Etymologicum magnum_ (under the word [Greek:
+magnetis]), and in Photius (_Quaest. amphiloch._, q. 131), it is stated
+that the name _sideritis_ was given to the loadstone either because of its
+action on iron, or of its resemblance in aspect to iron, _or rather_, they
+say, _because the loadstone was originally found in the mines of this
+metal_. Alexander of Aphrodisias expressly says (_Quaetiones Physicae_, II.
+23) that {22} the loadstone appears to be nothing else than [Greek: ge
+sideritis], the earth which yields iron, or the earth of iron.
+
+[53] PAGE 11, LINE 19. Page 11, line 29. _ab Orpheo_.--The reference is to
+v. 301-328 of the [Greek: Lithika]. The passage, as given in Abel's edition
+(Berol., 1881), begins:
+
+  [Greek: Tolma d' athanatous kai heneei meilissethai]
+  [Greek: magnessei, ten d' exoch' ephilato thousios Ares,]
+  [Greek: houneken, hoppote ken pelasei polioio siderou,]
+  [Greek: eute parthenike terenochroa chersin helousa]
+  [Greek: eitheon sternoi prosptussetai himeroenti,]
+  [Greek: hos heg' harpazousa poti spheteron demas haiei]
+  [Greek: aps palin ouk ethelei methemen polemista sideron.]
+
+[54] PAGE 11, LINE 20. Page 11, line 31. _Gallis aimant_.--The French word
+_aimant_, or _aymant_, is generally supposed to be derived from _adamas_.
+Nevertheless Klaproth (_op. citat._, p. 19) suggests that the word _aimant_
+is a mere literal translation into French of the Chinese word _thsu chy_,
+which is the common name of the magnet, and which means _loving stone_, or
+_stone that loves_. All through the east the names of the magnet have
+mostly the same signification, for example, in Sanskrit it is _thoumbaka_
+(the kisser), in Hindustani _tchambak_.
+
+[55] PAGE 11, LINE 20. Page 11, line 32. _Italis calamita_.--The name
+_calamita_, universal in Italian for the magnet, is also used in Roumanian,
+Croatian, Bosnian, and Wendish. Its supposed derivation from the Hebrew
+_khallamish_ is repudiated by Klaproth, who also points out that the use of
+[Greek: kalamita] in Greek is quite modern. He adds that the only
+reasonable explanation of the word _calamita_ is that given by Father
+Fournier (_op. citat._), who says:
+
+"Ils (les marins francais) la nomment aussi _calamite_, qui proprement en
+francais signifie une _grenouille verte_, parce qu'avant qu'on ait trouve
+l'invention de suspendre et de balancer sur un pivot l'aiguille aimantee,
+nos ancetres l'enfermaient dans une fiole de verre demi-remplie d'eau, et
+la faisaient flotter, par le moyen de deux petits fetus, sur l'eau comme
+une grenouille." Klaproth adds that he entirely agrees with the learned
+Jesuit, but maintains that the word _calamite_, to designate the little
+green frog, called to-day _le graisset_, _la raine_, or _la rainette_, is
+essentially Greek. For we read in Pliny (_Hist. Nat._ lib. xxxii., ch. x.):
+"Ea rana quam Graeci _calamiten_ vocant, quoniam inter arundines,
+fruticesque vivat, minima omnium est et viridissima."
+
+[56] PAGE 11, LINE 20. Page 11, line 32. _Anglis_ loadstone & adamant
+stone.
+
+The English term _loadstone_ is clearly connected with the Anglo-Saxon verb
+_loedan_, to lead, and with the Icelandic _leider-stein_. There is no doubt
+that the spelling _lodestone_ would be etymologically more correct, since
+it means _stone that leads_ not _stone that carries a load_. The correct
+form is preserved in the word _lode-star_.
+
+The word _adamant_, from _adamas_, the mediaeval word for both loadstone
+and diamond, also occurs in English for the loadstone, as witness
+Shakespeare:
+
+  "You draw me, you hard-hearted adamant
+  But yet you draw not iron; for my heart
+  Is true as steel."
+          _Midsummer Night's Dream_, Act II, Scene 1.
+
+[57] PAGE 11, LINE 21. Page 11, {23} line 33. _Germanis magness_, &
+_siegelstein_. The Stettin edition of 1628 reads _Germanis_ MAGNETSTEIN,
+_Belgis_ SEYLSTEEN; while that of 1633 reads _Germanis_ MAGNETSTEIN,
+_Belgis_ SYLSTEEN.
+
+[58] PAGE 11, LINE 26. Page 11, line 39. In this line the Greek sentence
+is, in every known copy of the folio of 1600, corrected in ink upon the
+text, [Greek: thales] being thus altered into [Greek: Thales], and [Greek:
+apomnemonuousi] into [Greek: apomnemoneuousi]. Four lines lower, brackets
+have been inserted around the words (lapidum specularium modo). These ink
+corrections must have been made at the printers', possibly by Gilbert's own
+hand. They have been carried out as errata in the editions of 1628 and
+1633. The "facsimile" Berlin reprint of 1892 has deleted them, however.
+Other ink corrections on pp. 14, 22, 38, 39, 47, 130, and 200 of the folio
+edition of 1600 are noted in due course.
+
+[59] PAGE 11, LINE 29. Page 11, line 45. _lapis specularis_. This is the
+mediaeval name for _mica_, but in Elizabethan times known as talc or
+muscovy stone. Cardan, _De Rerum Varietate_ (Basil., 1557, p. 418), lib.
+xiiii., cap. lxxii., mentions the use of _lapis specularis_ for windows.
+
+[60] PAGE 11, LINE 31. Page 11, line 46.: _Germanis Katzensilbar_ &
+_Talke_.--In the editions of 1628 and 1633 this is corrected to _Germanis_
+KATZENSILBER & TALCKE. Goethe, in _Wilhelm Meister's Travels_, calls mica
+"cat-gold."
+
+[61] PAGE 12, LINE 30. Page 12, line 35. _integtum_ appears to be a
+misprint for _integrum_, which is the reading of editions 1628 and 1633.
+
+[62] PAGE 13, LINE 4. Page 13, line 3. [Greek: mikroge] _seu Terrella_.
+Although rounded loadstones had been used before Gilbert's time (see
+Peregrinus, p. 3 of Augsburg edition of 1558, or Baptista Porta, p. 194, of
+English edition of 1658), Gilbert's use of the spherical loadstone as a
+model of the globe of the earth is distinctive. The name _Terrella_
+remained in the language. In _Pepys's Diary_ we read how on October 2,
+1663, he "received a letter from Mr. Barlow with a terella." John Evelyn,
+in his _Diary_, July, 1655, mentions a "pretty terella with the circles and
+showing the magnetic deviations."
+
+A Terrella, 4-1/2 inches in diameter, was presented in 1662 by King Charles
+I. to the Royal Society, and is still in its possession. It was examined in
+1687 (see _Phil. Transactions_ for that year) by the Society to see whether
+the positions of its poles had changed.
+
+In Grew's _Catalogue and Description of the Rarities belonging to the Royal
+Society and preserved at Gresham College_ (London, 1681, p. 364) is
+mentioned a Terrella contrived by Sir Christopher Wren, with one half
+immersed in the centre of a plane horizontal table, so as to be like a
+Globe with the poles in the horizon, having thirty-two magnet needles
+mounted in the margin of the table to show "the different respect of the
+_Needle_ to the several _Points_ of the _Loadstone_."
+
+In Sir John Pettus's _Fleta Minor_, London, 1683, in the _Dictionary of
+Metallick Words_ at the end, under the word _Loadstone_ occurs the
+following passage:
+
+"Another piece of Curiosity I saw in the Hands of Sir _William Persal_
+(since Deceased also) _viz._, a _Terrella_ or _Load-stone_, of little more
+than _6 Inches Diameter_, turned into a _Globular Form_, and all the
+_Imaginery Lines_ of our _Terrestrial Globe_, exactly drawn upon it: _viz._
+the _Artick _ and _Antartick Circles_, the _two Tropicks_, the _two
+Colures_, the _Zodiack_ and _Meridian_; and these _Lines_, and the several
+_Countryes_, artificially _Painted_ on it, and all of them with their true
+_Distances_, from the two _Polar Points_, and to find the truth of those
+_Points_, he took two _little pieces_ of a _Needle_, each of about _half_
+{24} _an Inch in length_, and those he laid on the _Meridian line_, and
+then with _Brass Compasses_, moved one of them towards the _Artick_, which
+as it was moved, still raised it self at one end higher and higher, keeping
+the other end fixt to the _Terrella_; and when it had compleated it Journy
+to the very _Artick Points_, it stood upright upon that _Point_; then he
+moved the other piece of _Needle_ to the _Antartick Point_, which had its
+_Elevations_ like the other, and when it came to the _Point_, it fixt it
+self upon that _Point_, and stood _upright_, and then taking the _Terrella_
+in my Hand, I could perfectly see that the two _pieces_ of _Needles_ stood
+so exactly one against the other, as if it had been one intire _long
+Needle_ put through the _Terrella_, which made me give credit to those who
+held, That there is an _Astral Influence_ that _darts_ it self through the
+_Globe_ of _Earth_ from _North_ to _South_ (and is as the _Axel-Tree_ to
+the _Wheel_, and so called the _Axis_ of the _World_) about which the
+_Globe_ of the _Earth_ is turned, by an _Astral Power_, so as what I
+thought _imaginary_, by this _Demonstration_, I found _real_."
+
+[63] PAGE 13, LINE 20. Page 13, line 22. The editions of 1628 and 1633 give
+a different woodcut from this: they show the terrella lined with meridians,
+equator, and parallels of latitude: and they give the compass needle, at
+the top, _pointing in the wrong direction_.
+
+[64] PAGE 14, LINE 3. Page 14, line 3. The Berlin "facsimile" reprint omits
+the asterisk here.
+
+[65] PAGE 14, LINE 5. Page 14, line 6. _erectus_ altered in ink in the
+folio to _erecta_. But _erectus_ is preserved in editions 1628 and 1633. In
+Cap. IIII., on p. 14, both these Stettin editions insert an additional cut
+representing the terrella A placed in a tub or vessel B floating on water.
+
+[66] PAGE 14, LINE 34. Page 14, line 39. _variatione quad[=a]._ The whole
+of Book IIII. is devoted to a discussion of the variation of the compass.
+
+[67] PAGE 16, LINE 28. Page 16, line 34. _aquae._--This curious use of the
+dative occurs also on p. 222, line 8.
+
+[68] PAGE 17, LINE 1. Page 17, line 1. _videbis._--The reading _vibebis_ of
+the 1633 edition is an error.
+
+[69] PAGE 18, LINE 24. Page 18, line 27. _Theamedem._--For the myth about
+the alleged _Theamedes_, or repelling magnet, see Cardan, _De Subtilitate_
+(folio ed., 1550, lib. vii., p. 186).
+
+Pliny's account, in the English version of 1601 (p. 587), runs:
+
+"To conclude, there is another mountaine in the same Aethyopia, and not
+farre from the said Zimiris, which breedeth the stone Theamedes that will
+abide no yron, but rejecteth and driveth the same from it."
+
+Martin Cortes, in his _Arte de Nauegar_ (Seville, 1556), wrote:
+
+"And true it is that Tanxeades writeth, that in Ethiope is found another
+kinde of this stone, that putteth yron from it" (Eden's translation,
+London, 1609).
+
+[70] PAGE 21, LINE 24. Page 21, line 25. _Hic segetes, &c._--The English
+version of these lines from Vergil's _Georgics_, Book I., is by the late
+Mr. R. D. Blackmore.
+
+[71] PAGE 22, LINE 18. Page 22, line 19. _quale_, altered in ink in the
+folio text to _qualis_. The editions of 1628 and 1633 both read _qualis_.
+
+[72] PAGE 22, LINE 19. Page 22, line 20. _rubrica fabrili_: in English
+_ruddle_ or _reddle_. See "Sir" John Hill, _A General Natural History_,
+1748, p. 47. In the _De Re Metallica_ of Entzelt (Encelius), Frankfurt,
+1551, p. 134, is a paragraph headed _De Rubrica Fabrili_, as follows:
+"Rubrica fabrilis duplex {25} est. a Germanis ant utraque dicitur rottel,
+roettelstein, wie die zimmerleuet vnd steynmetzen brauchen. a Graecis
+[Greek: miltos tektonike]. Est enim alia nativa, alia factitia. Natiua a
+Germanis proprie dicitur berckrottel. haec apud nos est fossilis.... Porro
+factitia est rubrica fabrilis, a Germanis braunrottel, quae fit ex ochra
+usta, ut Theophrastus et Dioscorides testantur."
+
+[73] PAGE 22, LINE 19. Page 22, line 20. _In Sussexia Angliae._--In
+Camden's _Britannia_ (1580) we read concerning the iron industry in the
+villages in Sussex: "They are full of iron mines in sundry places, where,
+for the making and founding thereof, there be furnaces on every side; and a
+huge deal of wood is yearly burnt. The heavy forge-hammers, worked by
+water-power, stored in hammer-ponds, ceaselessly beating upon the iron,
+fill the neighbourhood round about, day and night, with continual noise."
+
+[74] PAGE 23, LINE 1. Page 22, line 44. _in libro Aristotelis de admirandis
+narrationibus._--The reference is to the work usually known as the _De
+Mirabilibus Auscultationibus_, Cap. XLVIII.: "Fertur autem peculiarissima
+generatio esse ferri Chalybici Amisenique, ut quod ex sabulo quod a fluviis
+defertur, ut perhibent certe, conflatur. Alii simpliciter lotum in fornace
+excoqui, alii vero, quod ex lotura subsedit, frequentius lotum comburi
+tradunt adjecto simul et pyrimacho dicto lapide, qui in ista regio plurimus
+reperiri fertur." (Ed. Didot, vol. ii., p. 87.) According to Georgius
+Agricola, the stone pyrimachus is simply iron pyrites.
+
+[75] PAGE 23, LINE 22. Page 23, line 23. _vt in Italia Comi_, &c.--This is
+mostly taken from Pliny. Compare the following passage from Philemon
+Holland's translation (1601), p. 514:
+
+"But the most varietie of yron commeth by the meanes of the water, wherein
+the yron red-hot is eftsoones dipped and quenched for to be hardened. And
+verely, water only which in some place is better, in other worse, is that
+which hath ennobled many places for the excellent yron that commeth from
+them, as namely, Bilbilis in Spaine, and Tarassio, Comus also in Italie;
+for none of these places have any yron mines of their owne, and yet there
+is no talke but of the yron and steele that commeth from thence."
+
+Bilbilis is Bambola, and Tariassona the Tarazona of modern Spain.
+
+[76] PAGE 24, LINE 28. Page 24, line 27. _Quare vani sunt illi
+Chemici._--Gilbert had no faith in the alchemists. On pp. 19 and 21 he had
+poked fun at them for declaring the metals to be constituted of sulphur and
+quicksilver, and for pronouncing the fixed earth in iron to be sulphur. On
+p. 20 he had denied their proposition that the differences between silver,
+gold, and copper could arise from proportions of their constituent
+materials; and he likewise denounced unsparingly the supposed relation
+between the seven metals and the seven planets. He now denounces the vain
+dreams of turning all metals into gold, and all stones into diamonds. Later
+he rejects as absurd the magnetic curing of wounds. His detachment from the
+pseudo-science of his age was unique if not complete.
+
+[77] PAGE 25, LINE 15. Page 25, line 16. _Petro-coriis, & Cabis
+Biturgibus._--The Petro-corii were a tribe in the neighbourhood of
+Perigord; the Cubi Biturges another in that of Bourges.
+
+[78] PAGE 25, LINE 21. Page 25, line 23. Pliny's account, as translated by
+P. Holland (ed. 1601, p. 515), runs thus:
+
+"Of all mines that be, the veine of this mettall is largest, and spreadeth
+it selfe into most lengths every way: as we may see in that part of Biscay
+that coasteth along the sea, and upon which the Ocean beateth: where there
+{26} is a craggie mountaine very steep and high, which standeth all upon a
+mine or veine of yron. A wonderfull thing, and in manner incredible,
+howbeit, most true, according as I have shewed already in my Cosmographie,
+as touching the circuit of the Ocean."
+
+[79] PAGE 26, LINE 15. Page 26, line 12. _quas Clampas nostri vocant._--The
+name _clamp_ for the natural kiln formed by heaping up the bricks, with
+ventilating spaces and fuel within the heap, is still current.
+
+[80] PAGE 26, LINE 39. Page 26, line 38. _Pluebat in Taurinis ferrum._--The
+occurrence is narrated by Scaliger, _De Subtilitate_, Exercitat. cccxxiii.:
+
+"Sed falso lapidis pluviam creas tu ex pulvere hausto a nubibus, atque in
+lapidem condensato. At ferrum, quod pluit in Taurinis, cuius frustum apud
+nos extat, qua ex fodina sustulit nubes? Tribus circiter annis ante, quam
+ab Rege provincia illa recepta esset, pluit ferro multis in locis, sed
+raris" (p. 434, Editio Lutetiae, 1557).
+
+"During the latter ages of the Roman Empire the _city_ of Augusta
+Taurinorum seems to have been commonly known (as was the case in many
+instances in Transalpine Gaul) by the name of the tribe to which it
+belonged, and is called simply Taurini in the Itineraries, as well as by
+other writers, hence its modern name of Torino or Turin" (Smith's
+_Dictionary of Greek and Roman Geographies_, p. 1113).
+
+There exists a considerable literature respecting falls of meteors and of
+meteoric iron. Livy, Plutarch, and Pliny all record examples. See also
+_Remarks concerning stones said to have fallen from the clouds_, by Edward
+King (London, 1796); Chladni, _Ueber den Ursprung der von Pallas gefundenen
+und anderer ihr aehnlicher Eisenmassen_ (Riga, 1794); _Philosophical
+Transactions_, vol. lxxviii., pp. 37 and 183; vol. lxxxv., p. 103; vol.
+xcii., p. 174; Humboldt's _Cosmos_, vol. i. (p. 97 of London edition,
+1860); C. Rammelsberg, _Die chemische Natur der Meteoriten_ (Berlin, 1879);
+Maskelyne, _Some lecture-notes on Meteorites_ printed in _Nature_, vol.
+xii., pp. 485, 504, and 520, 1875. Maskelyne denominates as _siderites_
+those meteorites which consist chiefly of iron. They usually contain from
+80 to 95 per cent. of iron, often alloyed with nickel. This meteoric iron
+is sometimes so pure that it can at once be forged by the smith. An
+admirable summary of the whole subject is to be found in L. Fletcher's _An
+Introduction to the study of Meteorites_, publisht by the British Museum
+(Nat. Hist.), London, 1896.
+
+[81] PAGE 27, LINE 3. Page 26, line 41. _vt Cardanus ... scribit._--The
+passage runs:
+
+"Vidimus anno MDX cum cecidisset e coelo lapides circiter MCC in agrum
+fluvio Abduae conterminum, ex his unum CXX pondo, alium sexaginta delati
+fuerunt ad reges Gallor[~u] satrapes, plurimi: colos ferrugineus, durities
+eximia, odor sulphureus" (Cardan, _De Rerum Varietate_, lib. xiiii., cap.
+lxxii.; Basil., 1557, p. 545).
+
+[82] PAGE 27, LINE 9. Page 27, line 2. _aut stannum, aut plumbum album._
+Although most authorities agree in translating _plumbum album_ or _plumbum
+candidum_ as "tin" (which is unquestionably the meaning in such examples as
+Pliny's _Nat. Hist._, xxxiv. 347, and iv. 16; or Strabo, iii. 147),
+nevertheless it is certain that here _plumbum album_ is not given as a
+synonym of _stannum_ and therefore is not _tin_. That Gilbert meant either
+spelter or pewter is pretty certain. He based his metallic terms mainly
+upon Encelius (Christoph Entzelt) whose _De Re Metallica_ was published at
+Frankfurt in 1551. From this work are taken the following passages: {27}
+
+p. 61. _De Plumbo candido._ Cap. XXXI.
+
+"Veluti plumbum nigr[~u] uocatur a Germanis blei simpliciter, od'
+schwartzblei: ita plumb[~u] candid[~u] ab his uocatur weissblei, od' zin.
+Improprie autem plumbum hoc nostrum candidum zin, stannum dicitur. Et non
+sunt idem, ut hactenus voluerunt, stannum et plumbum candidum, unser zin.
+Aliud est stannum, de quo mox agemus: et aliud plumbum candidum nostrum,
+unser zin, quod nigro plumbo quasi est quidda purius et perfectius...."
+
+p. 62. _De Stanno._ Cap. XXXII.
+
+"In praecedenti capite indicauimus aliud esse stannum, aliud esse plumb[~u]
+candid[~u]. Illa ergo definitio plumbi candidi, dess zinnes, etia apud
+chimistas n[~o] de stanno, sed de plumbo candido (ut mihi uidetur)
+intelligenda est, cum dicunt: Stannum (es soll heyssen plumbum candidum)
+est metallicum album, non purum, lividum...."
+
+p. 63. "Sic uides stannum, secundum Serapionem, metallicum esse quod
+reperitur in sua propria uena, ut forsitan apud nos bisemut[~u]: ec[~o]tra
+nostr[~u] candid[~u] plumb[~u], est Plinij candid[~u] plumb[~u], das zin,
+quod c[~o]flatur ut plumbum nigrum, ex pyrite, galena, et lapillis nigris.
+Deinde uides stannum Plinio esse quidda de plumbo nigro, nempe primum
+fluorem plumbi nigri, als wann man vnser bley ertz schmeltzet, das erst das
+do fleuesset, zwaere Plinio stannum. Et hoc docet Plinius adulterari
+pl[~u]bo candido, mit vnserm zinn, vnd wann du ihm recht nachdenckest,
+daruon die kannen gemacht werden, das man halbwerck heist.... O ir losen
+vngelerten, vnckenbrenner. Stannum proculdubio Arabis metallum est
+preciosius nostro candido plumbo: sicuti apud nos bisemuthum quiddam plumbo
+preciosius."
+
+[83] PAGE 27, LINE 21. Page 27, line 17. _venas ... venis._--It is
+impossible to give in English this play on words between veins of ore and
+veins of the animal body.
+
+[84] PAGE 28, LINE 23. Page 28, line 20. _quem nos verticitatem
+dicimus._--See the notes on Gilbert's glossary, _ante_. The word verticity
+remained in the language. On p. 140 of Joseph Glanvill's _Vanity of
+Dogmatizing_ (Lond., 1661) we read: "We believe the _verticity_ of the
+_Needle_, without a Certificate from the _dayes_ of _old_."
+
+[85] PAGE 29, LINE 15. Page 29, line 16. _Nos vero diligentius omnia
+experientes._--The method of carefully trying everything, instead of
+accepting statements on authority, is characteristic of Gilbert's work. The
+large asterisks affixed to Chapters IX. X. XI. XII. and XIII. of Book I.
+indicate that Gilbert considered them to announce important original
+magnetical discoveries. The electrical discoveries of Book II., Chapter
+II., are similarly distinguished. A rich crop of new magnetical
+experiments, marked with marginal asterisks, large and small, is to be
+found in Book II., from Chapter XV. to Chapter XXXIV.; while a third series
+of experimental magnetical discoveries extends throughout Book III.
+
+[86] PAGE 31, LINE 30. Page 31, line 25. _verticem._--The context and the
+heading of the Chapter appear to require _verticitatem_. All editions,
+however, read _verticem_.
+
+[87] PAGE 32, LINE 12. Page 32, line 9. _Gartias ab horto._--The passage
+from Gartias ab Horto runs as follows in the Italian edition of 1616,
+_Dell' Historia dei Semplici Aromati._... di Don Garzia dall' Horto, Medico
+Portughese, ... Venezia MDCXVI., p. 208.
+
+"Ne meno e questa pietra velenosa, si come molti hanno tenuto; imperoche le
+genti di queste bande dicono che la Calamita presa per bocca, pero in poca
+{28} quantita, conserva la gioventu. La onde si racconta, che il Re di
+Zeilan il vecchio' s'haveva fatto fare tutti i vasi, dove si cocevano le
+vivade per lui, di Calamita. Et questo lo disse a me colui proprio, che fu
+a questo officio destinato."
+
+[88] PAGE 32, LINE 29. Page 32, line 29. _Plutarchus & C. Ptolemaeus._--The
+garlick myth has already been referred to in the note to p. 1. The
+originals are Plutarch, _Quaestiones Platonicae_, lib. vii., cap. 7, s. 1;
+C. Ptolemaeus, _Opus Quadripartitum,_ bk. i., cap. 3. The English
+translation of the latter, by Whalley (London, 1701), p. 10, runs: "For if
+the _Loadstone_ be _Rubbed_ with _Garlick_, the _Iron will not be drawn by
+it_."
+
+[89] PAGE 32, LINE 32. Page 32, line 33. _Medici nonnulli._--This is
+apparently a reference to the followers of Rhazes and Paracelsus. The
+argument of Gilbert as to the inefficacy of powdered loadstones is
+reproduced more fully by William Barlowe in his _Magneticall
+Aduertisements_ (1616, p. 7), as follows:
+
+"It is the goodnesse of the _Loadstone_ ioyned with a fit forme that will
+shew great force. For as a very good forme with base substance can doe but
+very litle, so the substance of the _Loadstone_ bee it neuer so excellent,
+except it haue some conuenient forme, is not auaileable. For example, an
+excellent _loadstone_ of a pound waight and of a good fashion, being vsed
+artificially, may take vp foure pounds of Iron; beate it into small pouder,
+and it shall bee of no force to take vp one ounce of Iron; yea I am very
+well assured that halfe an ounce of a Loadstone of good fashion, and of
+like vertue will take vp more then that pound will doe being beaten into
+powder. Whence (to adde this by the way) it appeareth manifestly, that it
+is a great error of those Physitions and Surgeons, which to remedy
+ruptures, doe prescribe vnto their Patients to take the pouder of a
+_Loadstone_ inwardly, and the small filing of iron mingled in some plaister
+outwardly: supposing that herein the _magneticall_ drawing should doe great
+wonders."
+
+[90] PAGE 33, LINE 11. Page 33, line 8. _Nicolaus in emplastrum
+divinum._...--Nicolaus Myrepsus is also known as Praepositas. In his _Liber
+de compositione medicamentorum_ (Ingoldstat, 1541, 4to) are numerous
+recipes containing loadstone: for example, Recipe No. 246, called "esdra
+magna," is a medicine given for inflammation of the stomach and for
+strangury, compounded of some forty materials including "litho demonis" and
+"lapis magnetis." The _emplastrum divinum_ does not, however, appear to
+contain loadstone. In the English tractate, _Praepositas his Practise, a
+worke ... for the better preservation of the Health of Man. Wherein are ...
+approved Medicines, Receiptes and Ointmentes. Translated out of Latin in to
+English by_ L. M. (London, 1588, 4to), we read on p. 35, "An Emplaister of
+D. N. [Doctor Nicolaus] which the Pothecaries call Divinum." This contains
+litharge, bdellium, and "green brasse," but no loadstone.
+
+Luis de Oviedo in his treatise _Methodo de la Coleccion y reposicion de las
+Medicinas simples_, edited by Gregorio Goncalez, Boticario (Madrid, 1622),
+gives (p. 502) the following: "Emplasto de la madre. _Recibe_: Nuezes
+moscadas, clauos, cinamono, artemisia, piedraimon. De cada uno dos
+oncas.... Entre otras differencias que ay de piedraiman se hallan dos. Vna
+que por la parte que mira al Septentrion, atrae el hierro, por lo quel se
+llama magnes ferrugineus. Y otra que atrae la carne, a la qual llaman
+magnes creaginus."
+
+An "Emplastrum sticticum" containing amber, mummy, loadstone, {29}
+haematite, and twenty other ingredients, and declared to be "vulnerum
+ulcerumque telo inflictorum sticticum emplastrum praestantissimum," is
+described on p. 267 of the _Basilica chimica_ of Oswaldus Crollius
+(Frankfurt, 1612).
+
+[91] PAGE 33, LINE 12. Page 33, line 9. _Augustani ... in emplastrum
+nigrum_....--Amongst the physicians of the Augsburg school the most
+celebrated were Adolphus Occo, Ambrosio Jung, and Gereone Seyler. This
+particular reference is to the _Pharmacopoeia Augustana_ ... _a Collegio
+Medico recognita_, published at Augsburg, and which ran through many
+editions. The recipe for the "_emplastrum nigrum vulgo Stichpflaster_" will
+be found on p. 182 of the seventh edition (1621-2). The recipe begins with
+oil of roses, colophony, wax, and includes some twenty-two ingredients,
+amongst them mummy, dried earthworms, and two ounces _lapidis magnetis
+praeparati_. The recipe concludes: "Fiat Emplastrum secundum artem. Perquam
+efficax ad recentia vulnera et puncturas, vnde denominationem habet." The
+volume is a handsome folio not unlike Gilbert's own book, and bears at the
+end of the prefatory address _ad Lectorem_ identically the same _cul de
+lampe_ as is found on p. 44 of _De Magnete_.
+
+The contradictions as to the alleged medicinal virtues of loadstone are
+well illustrated by Galen, who in his _De facultatibus_ says that loadstone
+is like haematite, which is astringent, while in his _De simplici medicina_
+he says it is purgative.
+
+[92] PAGE 33, LINE 14. Page 33, line 12. _Paracelsus in fodicationum
+emplastrum_.--Paracelsus's recipe for a plaster against stab-wounds is to
+be found in _Wundt vund Leibartznei_ ... D. Theoph. Paracelsus (Frankf.,
+1555, pp. 63-67).
+
+[93] PAGE 33, LINE 17. Page 33, line 15. _Ferri vis medicinalis_.--This
+chapter on the medicinal virtues of iron is a summary of the views held
+down to that time. Those curious to pursue the subject should consult
+Waring's _Bibliotheca Therapeutica_ (London, 1878). Nor should they miss
+the rare black-letter quarto by Dr. Nicholas Monardus, of Seville, _Joyfull
+Newes out of the New-found Worlde_, translated by John Frampton (London,
+1596), in which are recited the opinions of Galen, Rhazes, Avicenna, and
+others, on the medicinal properties of iron. In addition to the views of
+the Arabic authors, against whom his arguments are directed, Gilbert
+discusses those of Joannes Manardus, Curtius, and Fallopius. The treatise
+of Manardus, _Epistolarum medicinalium libri viginti_ (Basil., 1549), is a
+_resume_ of the works of Galen and the Arabic physicians, but gives little
+respecting iron. Curtius (Nicolaus) was the author of a book, _Libellus de
+medicamentis praeparatibus et purgantibus_ (Giessae Cattorum, 1614). The
+works of Fallopius are _De Simplicibus Medicamentis purgentibus tractatus_
+(Venet., 1566, 4to), and _Tractatus de Compositione Medicamentorum_
+(Venet., 1570, 4to).
+
+[94] PAGE 34, LINE 7. Page 34, line 3. _quorunda Arabum opiniones_.--The
+Arabian authorities referred to here or elsewhere by Gilbert are:
+
+_Albategnius_ (otherwise known as Machometes Aractensis), Muhammad Ibn
+J[=a]bir, _Al-Batt[=a]n[=i]_.
+
+_Avicenna_ (otherwise Abohali). Abou-'Ali al-'Hosein ben-'Abd-Allah
+Ibn-Sina, or, shortly, _Ibn Sina._
+
+_Averroes._ Muhammad Ibn Ahmed Ibn-Roschd, _Abou Al-Walid._
+
+_Geber._ Ab[=u] M[=u]s[=a] J[=a]bir Ibn Haiy[=a]n, _Al-Tars[=u]si._
+
+_Hali Abas._ 'Ali Ibn Al-'Abbas, _Al Majusi_. {30}
+
+_Rhazes_, or _Rasis_. Muhammad Ibn Zakar[=i]y[=a].
+
+_Serapio._ Yuhanna Ibn Sarapion.
+
+_Thebit Ben-Kora_ (otherwise Thabit Ibn Corrah). Ab[=u] Thabit Ibn Kurrah,
+_Al Harrani._
+
+[95] PAGE 34, LINE 38.: Page 34, line 40. _electuarium de scoria ferri
+descriptum a Raze._--Rhazes or Rasis, whose Arabic name was Muhammad Ibn
+Zakar[=i]y[=a], wrote _De Simplicibus, ad Almansorem._ In Chap. 63 of this
+work he gives a recipe for a stomachic, which includes fennel, anise,
+origanum, black pepper, cinammon, ginger, and iron slag. In the splendid
+folio work of Rhazes publisht at Venice in 1542, with the title _Habes
+candide lector Contin[~e]tem Rasis_, Libri ultimi, cap. 295, under the
+heading _De Ferro,_ are set forth the virtues of iron slag: "Virtus scorie
+est sicut virtus scorie [a]eris sed debilior in purgado: et erugo ferri
+est stiptica: et c[~u] superpositur retinet fluxus menstruor[~u].... Ait
+Paulus: aqua in qua extinguitur ferr[~u] calens.... Dico: certificatus sum
+experientia [~q] valet contra emorryodas diabetem et fluxum menstruorum."
+
+[96] PAGE 35, LINE 16.: Page 35, line 13. _Paulus._--This is not Fra Paolo
+Sarpi, nor Marco Polo, nor Paulus Jovius the historian, nor Paulus
+Nicolettus Venetus, but Paulus Aeginae.
+
+[97] PAGE 35, LINE 29.: Page 35, line 28. _Sed male Avicenna._--The advice
+of Avicenna to administer a draught containing powdered loadstone, reads as
+follows in the Giunta edition (Venice, 1608):
+
+Lib. ii., cap. 470, p. 356. "Magnes quid est? Est lapis qui attrahit
+ferrum, quum ergo aduritur, fit haematites, & virtus ejus est sicut virtus
+illius.... Datur in potu [ad bibitionem limaturae ferri, quum retinetur in
+ventre scoria ferri. Ipse enim extrahit] ipsam, & associatur ei apud
+exitum. Et dicitur, quando in potu sumuntur ex eo tres anulusat cum
+mellicrato, educit solutione humorem grossum malum."
+
+The passage is identical with that in the Venetian edition of 1486, in both
+of which the liquid prescribed is mellicratus--mead. Gilbert says that the
+iron is to be given in juice of _mercurialis_. Here he only follows
+Matthiolus, who, in his _Commentaries on Dioscorides_, says (p. 998 of the
+Basil. edition of 1598): "Sed (vt idem Auicenna scribit) proprium hujusce
+ferrei pharmaci antidotum, est lapis magnes drachmae pondere potus, ex
+mercurialis, vel betae succo."
+
+Serapio, in his _De Simplicibus Medicinis_ (Brunfels' edition, Argentorati,
+1531), p. 264, refers to Galen's prescription of iron scoriae, and under
+the article _de lapide magnetis_, p. 260, quotes Dioscorides as follows:
+"Et uirtus huius lapidis est, ut quado dantur in potu duo onolosat ex eo
+c[~u] melicrato, laxat humores grossos."
+
+The original passage in Dioscorides, _De Materia Medica,_ ch. 147
+(Spengel's edition of 1829) runs: "[Greek: Tou de magnetou lithou aristos
+estin ho ton sideron eucheros helkon, kai ten chroan kuanizon, puknos te
+kai ouk agan barus. Dunamin de echei pachous agogon didomenos meta
+melikratou triobolou baros; enioi de touton kaiontes anti haimatitou
+pipraskousin.]."
+
+In the Frankfurt edition of Dioscorides, translated by Ruellius (1543), the
+passage is:
+
+"Magnes lapis optimus est, qui ferrum facile trahit, colore ad coeruleum
+uergente, densus, nec admodum gravis. Datur cum aqua mulsa, trium obolorum
+pondere, ut crassos humores eliciat. Sunt qui magnetem cremat[=u] pro
+haematite vendant...."
+
+In the _Scholia_ of Joannes Lonicerus upon Dioscorides _In Dioscoridae {31}
+Anazarbei de re medica libros a Virgilio Marcello versos, Scholia nova,
+Ioanne Lonicero autore_ (Marburgi, 1543, p. 77), occurs the following:
+
+"_De recremento ferri._ Cap. XLIX.
+
+"[Greek: Skoria siderou]. scoria vel recrementum ferri. Quae per ignem a
+ferro et cupro sordes separantur ac reijciuntur, et ab aliis metallis
+[Greek: skoria] uocantur. Omnis scoria, maxime uero ferri exiccat. Acerrimo
+aceto macerauit Galenus ferri scoriam, ac deinde excocto, pharmacum efficax
+confecit ad purulentas quae multo tempore uexatae erant, aures, admirando
+spectantium effectu. Ardenti scoria uel recrementum [Greek: helkusma],
+inquit Galenus."
+
+See also the _Enarrationes eruditissimae_ of Amatus Lusitanus (Venet.,
+1597), pp. 482 and 507, upon iron and the loadstone.
+
+[98] PAGE 36, LINE 27. Page 36, line 29. _eijcitur_ for _ejicitur_.
+
+[99] PAGE 37, LINE 18. Page 37, line 22. _ut Cardanus
+philosophatur._--Cardan's nonsense about the magnet feeding on iron is to
+be found in _De Subtilitate_, lib. vii. (Basil., 1611, p. 381).
+
+[100] PAGE 38, LINE 4. Page 38, line 7. _ferramenta ... in usum
+navigantium._--Compare Marke Ridley's _A Short Treatise of Magneticall
+Bodies and Motions_ (Lond., 1613), p. _a2_ in the _Preface Magneticall_,
+where he speaks of the "iron-workes" used in building ships. The
+phraseology of Marke Ridley throws much light on the Latin terms used by
+Gilbert.
+
+[101] PAGE 38, LINE 36. Page 38, line 42. _vruntur;_ changed in ink to
+_vrantur_ in the folio of 1600; but _uruntur_ appears in the editions of
+1628 and 1633.
+
+[102] PAGE 39, LINE 12. Page 39, line 12. _virumque;_ altered in ink to
+_virunque_ in all copies of the folio edition of 1600.
+
+[103] PAGE 40, LINE 32. Page 40, line 33. _ad tantos labores
+exantlandos._--Pumping, as it was in mining before the invention of the
+steam engine, may best be realized by examining the woodcuts in the _De re
+metallica_ of Georgius Agricola (Basil., Froben, 1556).
+
+[104] PAGE 40, LINE 34. Page 40, line 36. _quingentas orgyas._--Gilbert
+probably had in his mind the works of the Rorerbuehel, in the district of
+Kitzbuehl, which in the sixteenth century had reached the depth of 3,107
+feet. See Humboldt's _Cosmos_ (Lond., 1860, vol. i., p. 149).
+
+[105] PAGE 43, LINE 34. Page 43, line 33. _glis._--This word, here
+translated _grit_, does not appear to be classical Latin; it may mean _ooze
+or slime_.
+
+[106] PAGE 45, LINE 25. Page 45, line 26. _Motus igitur ... quinque._ The
+five kinds of magnetic motions correspond in fact to the remaining sections
+of the book; as follows: _Coitio_, Book II.; _Directio_, Book III.;
+_Variatio_, Book IV.; _Declinatio_, Book V.; and _Revolutio_, Book VI.
+
+[107] PAGE 46, LINE 7. Page 46, line 8. _Jofrancus Offusius._--The
+reference is to the treatise _De divina astrorum faculitate_ of Johannes
+Franciscus Offusius (Paris, 1570).
+
+[108] PAGE 47, LINE 15. Page 47, line 18. _Graeci vocant_ [Greek:
+elektron], _quia ad se paleas trahit._ In this discussion of the names
+given to amber, Gilbert apparently conceives [Greek: elektron] to be
+derived from the verb [Greek: helkein]; which is manifestly a doubtful
+etymology. There has been much discussion amongst philologists as to the
+derivation of [Greek: elektron] or [Greek: elektron], and its possible
+connection with the word [Greek: elektor]. This discussion has been
+somewhat obscured by the circumstance that the Greek authors unquestionably
+used [Greek: elektron] (and the Latins their word _electrum_) in two
+different significations, some of them using these words to mean amber,
+others to mean a shining {32} metal, apparently of having qualities between
+those of gold and silver, and probably some sort of alloy. Schweigger,
+_Ueber das Elektron der Alten_ (Greifswald, 1848), has argued that this
+metal was indeed no other than platinum: but his argument partakes too much
+of special pleading. Those who desire to follow the question of the
+derivation of [Greek: elektron] may consult the following authorities: J.
+M. Gessner, _De Electro Veterum_ (Commentt. Soc. Reg. Scientt. Goetting.,
+vol. iii., p. 67, 1753); Delaunay, _Mineralogie der Alten_, Part II., p.
+125; Buttmann, _Mythologus_ (Appendix I., _Ueber das Elektron_), Vol. II.,
+p. 355, in which he adopts Gilbert's derivation from [Greek: helkein];
+Beckmann, _Ursprung und Bedeutung des Bernsteinnamens Elektron_
+(Braunsberg, 1859); Th. Henri Martin, _Du Succin, de ses noms divers et de
+ses varietes suivant les anciens_ (Memoires de l'Academie des Inscriptions
+et Belles-lettres, Tome VI., 1^{re} serie, 1^{re} partie, 1860); Martinus
+Scheins, _De Electro Veterum Metallico_ (Inaugural dissertation, Berlin,
+1871); F. A. Paley, _Gold Worship in relation to Sun Worship_ (Contemporary
+Review, August, 1884). See also Curtius, _Grundzuege der griechischen
+Etymologie_, pp. 656-659. The net result of the disputations of scholars
+appears to be that [Greek: elektor] (he who shines) is a masculine form to
+which there corresponds the neuter form [Greek: elektron] (that which
+shines). Stephanus admits the accentuation used by Gilbert, [Greek:
+elektron], to be justified from the _Timaeus_ of Plato; see Note to p. 61.
+
+[109] PAGE 47, LINE 16. Page 47, line 19. [Greek: harpax] dicitur, &
+[Greek: chrusophoron].--With respect to the other names given to amber, M.
+Th. Henri Martin has written (see previous note) so admirable an account of
+them that it is impossible to better it. It is therefore given here entire,
+as follows:
+
+    "Le succin a recu chez les anciens des noms tres-divers. Sans parler du
+    nom de [Greek: lunkourion], lyncurium, qui peut-etre ne lui appartient
+    pas, comme nous le montrerons plus loin, il s'est nomme chez les Grecs
+    le plus souvent [Greek: elektron] au neutre,^1 mais aussi [Greek:
+    elektros] au masculin^2 et meme au feminin,^3 [Greek:
+    chruselektros],^4 [Greek: chrusophoros]^5 et peut-etre, comme nous
+    l'avons vu, [Greek: chalkolithanon]; plus tard [Greek: souchion]^6 ou
+    [Greek: souchinos]^7, et [Greek: elektrianos lithos];^8 plus tard
+    encore [Greek: berenike], [Greek: beronike] ou [Greek: bernike];^9 il
+    s'est nomme [Greek: harpax] chez les Grecs etablis en Syrie;^{10} chez
+    les Latins _succinum_, _electrum_, et deux varietes, _chryselectrum_ et
+    _sualiternicum_ {33} ou _subalternicum_;^{11} chez les Germains,
+    _Gless_;^{12} chez les Scythes, _sacrium_;^{13} chez les Egyptiens,
+    _sacal_;^{14} chez les Arabes, _karabe_^{15} ou _kahraba_;^{16} en
+    persan, _karuba_.^{17} Ce mot, qui appartient bien a la langue persane,
+    y signifie _attirant la paille_, et par consequent exprime l'attraction
+    electrique, de meme que le mot [Greek: harpax] des Grecs de Syrie. En
+    outre, le nom de _haur roumi_ (_peuplier romain_) etait donne par les
+    Arabes, non-seulement a l'arbre dont ils croyaient que le succin etait
+    la gomme, mais au succin lui-meme. _Haur roumi_, transforme en _aurum_
+    par les traducteurs latins des auteurs arabes, et consondu mal a propos
+    avec _ambar_ ou _ambrum_, nom arabe latinise de l'ambre gris, a produit
+    le nom moderne d'_ambre_, nom commun a l'_ambre jaune_ ou succin, qui
+    est une resine fossile, et a l'_ambre gris_, concretion odorante qui se
+    forme dans les intestines des cachalots. On ne peut dire avec certitude
+    si le nom de basse grecite [Greek: bernike] est la source ou le derive
+    de _Bern_, radical du nom allemand du succin (_Bernstein_). Quoi qu'il
+    en soit, le mot [Greek: bernike] a produit _vernix_, nom d'une gomme
+    dans la basse latinite, d'ou nous avons fait _vernis_.^{18}"
+
+    ^1 Voyez Herodote, III., 115; Platon, _Timee_, p. 80 c; Aristote,
+    _Meteor._, IV., 10; Theophraste, _Hist. des plantes_, IX., 18 (19), s.
+    2; _Des pierres_, s. 28 et 29; Diodore de Sic., V., 23; Strabon, IV.,
+    6, n^o 2, p. 202 (Casaubon); Dioscoride, _Mat. med._, I., 110;
+    Plutarque, _Questions de table_, II., 7, s. 1; _Questions platoniques_,
+    VII., 1 et 7; Lucien, _Du succin et des cygnes_; le meme, _De
+    Pastrologie_, s. 19; S. Clement, _Strom._ II., p. 370 (Paris, 1641,
+    in-fol.); Alexandre d'Aphr., _Quest. phys. et mor._, II., 23;
+    Olympiodore, _Meteor._, I., 8, fol. 16, t. I., p. 197 (Ideler) et
+    l'abreviateur d'Etienne de Byzance au mot [Greek: Elektrides].
+
+    ^2 Voyez Sophocle, _Antigone_, v. 1038, et dans Eustathe, sur
+    l'_Iliade_, II., 865; Elien, _Nat. des animaux_, IV. 46; Quintus de
+    Smyrne, V., 623; Eustathe, sur la _Periegese_ de Denys, p. 142
+    (Bernhardy), et sur l'_Odyssee_, IV., 73; et Suidas au mot [Greek:
+    huale].
+
+    ^3 Voyez Alexandre, _Problemes_, sect. 1, prooem., p. 4 (Ideler);
+    Eustathe, sur l'_Odyssee_, IV., 73, et Tzetzes, _Chiliade_ VI., 650.
+
+    ^4 Voyez Psellus, _Des pierres_, p. 36 (Bernard et Maussac).
+
+    ^5 Voyez Dioscoride, _Mat. med._, I., 110.
+
+    ^6 Voyez S. Clement, _Strom._, II., p. 370 (Paris, 1641, in-fol.). Il
+    parait distinguer l'un de l'autre [Greek: to souchion] et [Greek: to
+    elektron], probablement parce qu'il attribue a tort au metal [Greek:
+    elektron] la propriete attractive du succin.
+
+    ^7 Voyez le faux Zoroastre, dans les _Geoponiques_, XV., 1, s. 29.
+
+    ^8 Voyez le faux Zoroastre, au meme endroit.
+
+    ^9 Voyez Eustathe, sur l'_Odyssee_, IV., 73; Tzetzes, _Chil._ VI., 650;
+    Nicolas Myrepse, _Antidotes_, ch. 327, et l'Etymol. Gud. au mot [Greek:
+    elektron]. Comparez Saumaise, Exert. plin., p. 778.
+
+    ^{10} Voyez Pline, XXXVII., 2, s. 11, n^o 37.
+
+    ^{11} Voyez Pline, XXXVII., 2, s. 11-13, et Tacite, _Germanie_, ch. 45.
+    La forme _sualiternicum_, dans Pline (s. 11, n^o 33), est donnee par le
+    manuscrit de Bamberg et par M. Sillig (t. V., p. 390), au lieu de la
+    forme _subalternicum_ des editions anterieures.
+
+    ^{12} Voyez Tacite et Pline, _ll. cc._
+
+    ^{13} Voyez Pline, XXXVII., 2, s. 11, n^o 40, Comp. J. Grimm, _Gesch.
+    der deutsch. Sprache_, Kap. x., p. 233 (Leipzig, 1848, in-8).
+
+    ^{14} Pline, _l. c._
+
+    ^{15} Voyez Saumaise, _De homon. hyles iatricae_, c. 101, p. 162 (1689,
+    in-fol.).
+
+    ^{16} Voyez Sprengel, sur Dioscoride, t. II., pp. 390-391.
+
+    ^{17} Voyez M. de Sacy, cite par Buttmann, _Mythologus_, t. II., pp.
+    362-363.
+
+    ^{18} Voyez Saumaise, _Ex. plin._, p. 778. Il n'est pas probable que le
+    mot [Greek: bernike] ou [Greek: berenike] nom du succin dans la grecite
+    du moyen age, soit lie etymologiquement avec le nom propre [Greek:
+    berenike], qui vient de l'adjectif macedonien [Greek: berenikos] pour
+    [Greek: pherenikos].
+
+[110] PAGE 47, LINE 17. Page 47, line 20. _Mauri vero Carabem appellant,
+quia solebant in sacrificijs, & deorum cultu ipsum libare. Carab enim
+significat offerre Arabice; ita Carabe, res oblata; aut rapiens paleas, vt
+Scaliger ex Abohali citat, ex lingua Arabica, vel Persica._--The printed
+text, line 18, has "Non rapiens paleas," but in all copies of the folio of
+1600, the "Non" has been altered in ink into "aut," possibly by Gilbert's
+own hand. Nevertheless the editions of 1628 and 1633 both read "Non." There
+appears to be no doubt that the origin of the word _Carabe_, or _Karabe_,
+as assigned by Scaliger, is substantially correct. As shown in the
+preceding note, Martin adopted this view. If any doubt should remain it
+will be removed by the following notes which are due to Mr. A. Houtum
+Schindler (member of the Institution of Electrical Engineers), of Terahan.
+
+Reference is made to the magnetic and electric properties of stones in
+three early Persian lapidaries. There are three stones only mentioned,
+amber, loadstone, and garnet. The electric property of the diamond is not
+mentioned. The following extracts are from the _Tansuk namah_, by Nasir ed
+din Tusi, A.D. 1260. The two other treatises give the first extracts in the
+same words.
+
+"_Kahruba_, also _Kahraba_ [Amber],
+
+"Is yellow and transparent, and has its name from the property, which it
+possesses, of attracting small, dry pieces of straw or grass, after it has
+been rubbed with cloth and become warm. [Note. In Persian, Kah = straw;
+ruba = the robber, hence Kahruba = the straw-robber.] Some consider it a
+mineral, and say that it is found in the Mediterranean and Caspian seas,
+floating on the surface, but this is not correct. The truth is that Kahruba
+{34} is the gum of a tree, called joz i rumi [_i.e._, roman nut; walnut?],
+and that most of it is brought from Rum [here the Eastern Rome] and from
+the confines of Sclavonia and Russia. On account of its bright colour and
+transparency it is made into beads, rings, belt-buckles, &c. ... &c.
+
+       *       *       *       *       *
+
+"The properties of attraction and repulsion are possessed by other
+substances than loadstone, for instance, by amber and bijadah,^1 which
+attract straws, feathers, etc., and of many other bodies, it can be said
+that they possess the power of attraction. There is also a stone which
+attracts gold; it has a pure yellow colour. There is also a stone which
+attracts silver from distances of three or two yards. There are also the
+stone which attracts tin, very hard, and smelling like asafoetida, the
+stone attracting hair, the stone attracting meat, etc., but, latterly, no
+one has seen these stones: no proof, however, that they do not exist."
+
+Avicenna (Ibn Sina) gives the following under the heading of _Karabe_ (see
+_Canona Medicinae_, Giunta edition, Venet., 1608, lib. ii., cap. 371, p.
+336):
+
+"Karabe quid est? Gumma sicut sandaraca, tendens ad citrinitatem, &
+albedinem, & peruietatem, & quandoque declinat ad rubedinem, quae attrahit
+paleas, & [fracturas] plantarum ad se, & propter hoc nominatur Karabe,
+scilicet rapiens paleas, persice.... Karabe confert tremori cordis, quum
+bibitur ex eo medietas aurei cum aqua frigida, & prohibet sputum sanguinis
+valde.... Retinet vomitum, & prohibet materias malas a stomacho, & cum
+mastiche confortat stomachum.... Retinet fluxum sanguinis ex matrice, &
+ano, & fluxum ventris, & confert tenasmoni."
+
+Scaliger in _De Subtilitate_, _Exercitatio_ ciii., s. 12, the passage
+referred to by Gilbert says: "Succinum apud Arabas uocatur, Carabe: quod
+princeps Aboali, rapiens paleas, interpretatur" (p. 163 _bis_, editio
+Lutetiae, 1557).
+
+    ^1 _Bijadah_ is classified by Muhammad B. Mansur (A.D. 1470) and by Ibn
+    al Mubarak (A.D. 1520) under "stones resembling ruby"; the Tansuk namah
+    describes it in a separate chapter. From the description it can be
+    identified with the almandine garnet, and the method of cutting this
+    stone _en cabochon_, with hollow back in order to display its colour
+    better is specially mentioned. The Tansuk namah only incidentally
+    refers to the electric property of the _bijadah_ in the chapter on
+    loadstone, but the other two treatises specially refer to it in their
+    description of the stone. The one has: "_Bijadah_ if rubbed until warm,
+    attracts straws and other light bodies just as amber does"; the other:
+    "_Bijadah_, if rubbed on the hair of the head, or on the beard,
+    attracts straws." Sururi, the lexicographer, who compiled a dictionary
+    in 1599, considers the _bijadah_ "a red ruby which possesses the
+    property of attraction." Other dictionaries do not mention the
+    attractive property, but some authors confound the stone with amber,
+    calling it _Kabruba_, the straw-robber. The _bijadah_ is not rubellite
+    (red tourmaline) for it is described in the lapidaries as common,
+    whereas rubellite (from Ceylon) has always been rare, and was unknown
+    in Persia in the thirteenth century.
+
+[111] PAGE 47, LINE 21. Page 47, line 25. _Succinum seu
+succum._--Dioscorides regarded amber as the inspissated juice of the poplar
+tree. From the Frankfurt edition of 1543 (_De Medicinali materia, etc._)
+edited by Ruellius, we have, liber i., p. 53:
+
+_Populus._ Cap. XCIII.
+
+"... Lachrymam populorum commemorant quae in Padum amnem defluat, durari,
+ac coire in succinum, quod electrum vocant, alii chrysophorum. id attritu
+jucundum odorem spirat, et aurum colore imitatur. tritum potumque stomachi
+ventrisque fluxiones sistit."
+
+To this Ruellius adds the commentary:
+
+"Succinum seu succina gutta a succo dicta, Graecis [Greek: elektrom] [sic],
+esse {35} lachryma populi albae, vel etiam nigrae quibusdam videtur, ab
+ejusdem arboris resina. Dioscoridi et Galeno dicta differens et [Greek:
+pterugophoros], id est paleas trahens, quoque vocatur, quantum ei quoque
+Galenus tribuit li. 37, ca. 9. Succinum scribit a quibusdam pinei generis
+arboribus, ut gummi a cerasis excidere autumno, et largum mitti ex Germania
+septentrionali, et insulis maris Germanici. quod hodie nobis est
+compertissimum: ad haec liquata igni valentiore, quia a frigido intensiore
+concrevit. pineam aperte olet, calidum primo gradu, siccum secundo,
+stomachum roborat, vomitum, nauseam arcet. cordis palpitationi prodest.
+pravorem humorum generationem prohibet.
+
+"Germani weiss und gelbaugstein et bre[=n]stein.
+
+"Galli ambra vocant: vulgo in corollis precariis frequens."
+
+In the scholia of Johann Lonicer in his edition of Dioscorides, we find,
+lib. i., cap. xcviii., _De nigra Populo_:
+
+"[Greek: aigeiros], populus nigra ... idem electrum vel succinum [Greek:
+haigeirou] lachrymam esse adseverat [Paulus], cui praeter vires quae ab
+Dioscoride recensentur, tribuit etiam vim sistendi sanguinis, si tusum in
+potu sumatur. Avicennae Charabe, ut colligitur ex Joanne Jacobo Manlio, est
+electrum hoc Dioscoridis, attestatur Brunfelsius. Lucianus plane nullum
+electrum apud Eridanum seu Padum inveniri tradit, quandoquidem ne populus
+quidem illa ab nautis ei demonstrari potuerit. Plinius rusticas
+transpadanas ex electro monilia gestare adfirmat, quum a Venetis primum
+agnoscere didicissent adversus nimirum vitia gutturis et tonsillarum. Num
+sit purgamentum maris, vel lachryma populi, vel pinus, vel ex radiis
+occidentis solis nascatur, vel ex montibus Sudinorum profluat, incertum
+etiam Erasmus Stella relinquit. Sudinas tamen Borussiorum opes esse
+constat."
+
+Matthiolus (in _P. A. Mattioli ... Opera quae extant omnia, hoc est
+Commentarii in vi libros P. Dioscoridis de materia medica_, Frankfurt,
+1596, p. 133) comments on the suggestion of Galen that amber came from the
+_Populus alba_, and also comments on the Arabic, Greek, and Latin names of
+amber.
+
+The poplar-myth is commemorated by Addison (in _Italy_) in the lines:
+
+  No interwoven reeds a garland made,
+  To hide his brows within the vulgar shade;
+  But poplar wreathes around his temples spread,
+  And tears of amber trickled down his head.
+
+Amber is, however, assuredly not derived from any poplar tree: it comes
+from a species of pine long ago extinct, called by Goeppert the _pinites
+succinifer_.
+
+Gilbert does not go into the medicinal uses, real or fancied, that have
+been ascribed to amber in almost as great variety as to loadstone. Pliny
+mentions some of these in his _Natural Historie_ (English version of 1601,
+p. 609):
+
+"He [Callistratus] saith of this yellow Amber, that if it be worne about
+the necke in a collar, it cureth feavers, and healeth the diseases of the
+mouth, throat, and jawes: reduced into pouder and tempered with honey and
+oile of roses, it is soveraigne for the infirmities of the eares. Stamped
+together with the best Atticke honey, it maketh a singular eyesalve for to
+help a dim sight: pulverized, and the pouder thereof taken simply alone, or
+else drunke in water with Masticke, is soveraigne for the maladies of the
+stomacke."
+
+Nicolaus Myrepsus (Recipe 951, _op. citat._) gives a prescription for {36}
+dysentery and diabetes confiding chiefly of "Electri vel succi Nili (Nili
+succum appellant Arabes Karabem)."
+
+[112] PAGE 47, LINE 22. Page 47, line 26. _Sudauienses seu Sudini._--Cardan
+in _De Rerum Varietate_, lib. iii., cap. xv. (Editio Basil., 1556, p. 152),
+says of amber:
+
+"Colligitur in quadam pene insula Sudinorum, qui nunc uoc[=a]tur Brusci, in
+Prussia, nunc Borussia, juxta Veneticum sinum, & sunt orientaliores ostiis
+Vistulae fluuii: ubi triginta pagi huic muneri destinati sunt," etc. He
+rejects the theory that it consists of hardened gum.
+
+There exists an enormous literature concerning Amber and the Prussian amber
+industry. Amongst the earliest works (after Theophrastus and Pliny) are
+those of Aurifaber (_Bericht ueber Agtstein oder Boernstein_, Koenigsberg,
+1551); Goebel (_De Succino, Libri duo, authore Severino Goebelio, Medico
+Doctore_, Regiomont., 1558); and Wigand (_Vera historia de Succino
+Borussico_, Jena, 1590). Later on Hartmann, P. J. (_Succini Prussici
+Physica et civilis Historia_, Francofurti, 1677); and the splendid folio of
+Nathaniel Sendel (_Historia Succinorum corpora aliena involventium_,
+Lipsiae, 1742), with its wealth of plates illustrating amber specimens,
+with the various included fossil fauna and flora. Georgius Agricola (_De
+natura Fossilium_, liber iv.), and Aldrovandi (_Musaeeum Metallicum_, pp.
+411-412) must also be mentioned. Bibliographies of the earlier literature
+are to be found in Hartmann (_op. citat._), and in Daniel Gralath,
+_Elektrische Bibliothek_ (_Versuche und Abhandlungen der Naturforschenden
+Gesellschaft in Danzig_, Zweiter Theil, pp. 537-539, Danzig and Leipzig,
+1754). See also Karl Muellenhoff, _Deutsche Altertumskunde_, vol. i.,
+Zweites Buch, pp. 211-224, Zinn und Bernsteinhandel (Berlin, 1870), and
+Humboldt's _Cosmos_ (Bohn's edition, London, 1860, vol. ii., p. 493).
+
+The ancient Greek myth according to which amber was the tears of the
+Heliades, shed on the banks of the river Eridanus over Phaethon, is not
+alluded to by Gilbert. It is narrated in well-known passages in Ovid and in
+Hyginus. Those interested in the modern handling of the myth should refer
+to Muellenhoff (_op. citat._, pp. 217-223, der Bernsteinmythus), or to that
+delightful work _The Tears of the Heliades_, by W. Arnold Buffum (London,
+1896).
+
+[113] PAGE 47, LINE 30. Page 47, line 36. _quare & muscos ... in frustulis
+quibusdam comprehensos retinet._--The occurrence of flies in amber was well
+known to the ancients. Pliny thus speaks of it, book xxxvii., chap. iii.
+(p. 608 of P. Holland's translation of 1601):
+
+"That it doth destill and drop at the first very clear and liquid, it is
+evident by this argument, for that a man may see diverse things within, to
+wit, Pismires, Gnats, and Lizards, which no doubt were entangled and stucke
+within it when it was greene and fresh, and so remain enclosed within as it
+waxed harder."
+
+A locust embedded in amber is mentioned in the _Musaeum Septalianum_ of
+Terzagus (Dertonae, 1664).
+
+Martial's epigram (_Epigrammata_, liber vi., 15) is well known:
+
+  Dum Phaethontea formica vagatur in umbra
+  Implicuit tenuem succina gutta feram.
+
+See also Hermann (Daniel), _De rana et lacerta Succino Borussiaco insitis_
+{37} (Cracov., 1580; a later edition, Rigae, 1600). The great work on
+_inclusa_ in amber is, however, that of Nathaniel Sendel. See the previous
+note.
+
+Sir Thomas Browne must not be forgotten in this connexion. The
+_Pseudodoxia_ (p. 64 of the second edition, 1650) says:
+
+"Lastly, we will not omit what Bellabonus upon his own experiment writ from
+Dantzich unto Mellichius, as he hath left recorded in his chapter _De
+Succino_, that the bodies of Flies, Pismires and the like, which are said
+oft times to be included in Amber, are not reall but representative, as he
+discovered in severall pieces broke for that purpose. If so, the two famous
+Epigrams hereof in Martiall are but poeticall, the Pismire of Brassavolus
+Imaginary, and Cardans Mousoleum for a flie, a meer phancy. But hereunto we
+know not how to assent, as having met with some whose reals made good their
+representments." See also Pope's _Epistle to Dr. Arbuthnot_, line 169.
+
+[114] PAGE 47, LINE 34. Page 47, line 40. _Commemorant antiqui quod
+succinum festucas et paleas attrahit._--Pliny (book xxxvii., chap. ii., p.
+606 of the English edition of 1601) thus narrates the point:
+
+"Hee [_Niceas_] writeth also, that in Aegypt it [amber] is engendered....
+Semblably in Syria, the women (saith hee) make wherves of it for their
+spindles, where they use to call it Harpax, because it will catch up
+leaves, straws, and fringes hanging to cloaths."
+
+p. 608. "To come to the properties that Amber hath, If it bee well rubbed
+and chaufed betweene the fingers, the potentiall facultie that lieth
+within, is set on work, and brought into actual operation, whereby you
+shall see it to drawe chaffe strawes, drie leaves, yea, and thin rinds of
+the Linden or Tillet tree, after the same sort as loadstone draweth yron."
+
+[115] PAGE 47, LINE 36. Page 47, line 42. _Quod etiam facit Gagates
+lapis._--The properties of Jet were well known to the mediaeval writers.
+_Julius Solinus_ writes in _De Mirabilibus_, chapter xxxiv., _Of Britaine_
+(English version of 1587 by A. Golding):
+
+"Moreover to the intent to passe the large aboundance of sundry mettals
+(whereof Britaine hath many rich mynes on all sides), Here is store of the
+stone called Geate, and y^e best kind of it. If ye demaund y^e beautie of
+it, it is a black Jewell: if the qualitie, it is of no weight: if the
+nature, it burneth in water, and goeth out in Oyle; if the power, rubbe it
+till it be warme, and it holdeth such things as are laide to it; as Amber
+doth. The Realme is partlie inhabited of barbarous people, who even fr[~o]
+theyr childhoode haue shapes of divers beastes cunninglye impressed and
+incorporate in theyr bodyes, so that beeing engraued as it were in theyr
+bowels, as the man groweth, so growe the marks painted vpon him...."
+
+Pliny describes it as follows (p. 589, English edition of 1601):
+
+"The Geat, which otherwise we call Gagates, carrieth the name of a toune
+and river both in Lycia, called Gages: it is said also, that the sea
+casteth it up at a full tide or high water into the Island Leucola, where
+it is gathered within the space of twelve stadia, and no where else: blacke
+it is, plaine and even, of a hollow substance in manner of the pumish
+stone, not much differing from the nature of wood; light, brittle, and if
+it bee rubbed or bruised, of a strong flavour." (Book xxxvi., chap. xviii.)
+
+In the Commentary of Joannes Ruellius upon Dioscorides, _Pedanii
+Dioscoridis Anazarbei de medicinali materia libri sex, Ioanne Ruellio
+Suessionensi interprete_ ... (Frankfurt, 1543, fol., liber quintus, cap.
+xcii.) is the following description:
+
+{38} "In Gagatarum lapidum genere, praeferendus qui celeriter accenditur,
+et odorem bituminis reddit. niger est plerunque, et squalidus, crustosus,
+per quam levis. Vis ei molliendi, et discutiendi. deprehendit sonticum
+morbum suffitus, recreatque uuluae strangulationes. fugat serpentes nidore.
+podagricis medicaminibus, et a copis additur. In Cilicia nasci solet, qua
+influens amnis in mare effunditur, proxime oppidum quod Plagiopolis
+dicitur. vocatur autem et locus et amnis Gagas, in cujus faucibus ii
+lapides inveniuntur.
+
+"Gagates lapis colore atro, Germanis Schwartzer augstein, voce parum
+depravata, dicitur. odore dum uritur bituminis, siccat, glutinat, digerit
+admotus, in corollis precariis et salinis frequens."
+
+And in the _Scholia_ upon Dioscorides of Joannes Lonicer (Marpurgi, 1643,
+cap. xcvii., p. 80) is the following:
+
+"_De Gagate Lapide._ Ab natali solo, urbe nimirum Gagae Lyciae nomen habet.
+Galenus se flumen isthuc et lapidem non invenisse, etiamsi naui parua totam
+Lyciam perlustravit: ait, se autem in caua Syria multos nigros lapides
+invenisse glebosos, qui igni impositi, exiguam flammam gignerent. Meminit
+hujus Nicander in Theriacis nempe suffitum hujus abigere venenata."
+
+There is also a good account of _Gagates_ (and of Succinum) by Langius,
+_Epistola_ LXXV., p. 454, of the work _Epistolarum medicinalium volumen
+tripartitum_ (Francofurti, 1589).
+
+[116] PAGE 47, LINE 39. Page 47, line 45. _Multi sunt authores
+moderni._--The modern authors who raised Gilbert's wrath by ignorantly
+copying out all the old tales about amber, jet, and loadstone, instead of
+investigating the facts, were, as he says at the beginning of the chapter,
+some theologians, and some physicians. He seems to have taken a special
+dislike to Albertus Magnus, to Puteanus (Du Puys), and to Levinus Lemnius.
+
+[117] PAGE 47, LINE 39. Page 47, line 46. _& gagate._--The editions of 1628
+and 1633 both read _ex gagate_.
+
+[118] PAGE 48, LINE 14. Page 48, line 16. _Nam non solum succinum, &
+gagates (vt illi putant) allectant corpuscula._--The list of bodies known
+to become electrical by friction was not quite so restricted as would
+appear from this passage. Five, if not six, other minerals had been named
+in addition to amber and jet.
+
+(1.) _Lyncurium._ This stone, about which there has been more obscurity and
+confusion than about any other gem, is supposed by some writers to be the
+tourmaline, by others a jacinth, and by others a belemnite. The ancients
+supposed it to be produced from the urine of the lynx. The following is the
+account of Theophrastus, _Theophrastus's History of Stones. With an English
+Version_ ..., by "Sir" John Hill, London, 1774, p. 123, ch. xlix.-l. "There
+is some Workmanship required to bring the Emerald to its Lustre, for
+originally it is not so bright. It is, however, excellent in its Virtues,
+as is also the _Lapis Lyncurius_, which is likewise used for engraving
+Seals on, and is of a very solid Texture, as Stones are; it has also an
+attractive Power, like that of Amber, and is said to attract not only
+Straws and small pieces of Sticks, but even Copper and Iron, if they are
+beaten to thin pieces. This Diocles affirms. The _Lapis Lyncurius_ is
+pellucid, and of a fire Colour." See also W. Watson in _Philos. Trans._,
+1759, L. i., p. 394, _Observations concerning the Lyncurium of the
+ancients_.
+
+(2.) _Ruby._
+
+(3.) _Garnet._ The authority for both these is Pliny, _Nat. Hist._, book
+xxxvii., chap. vii. (p. 617 of English edition of 1601).
+
+{39} "Over and besides, I find other sorts of Rubies different from those
+above-named;... which being chaufed in the Sun, or otherwise set in a heat
+by rubbing with the fingers, will draw unto them chaffe, strawes, shreads,
+and leaves of paper. The common Grenat also of Carchedon or Carthage, is
+said to doe as much, although it be inferiour in price to the former."
+
+(4.) _Jasper._ Affaytatus is the authority, in _Fortunii Affaitati Physici
+atque Theologi ... Physicae & Astronomicae c[=o]siderationes_ (Venet.,
+1549), where, on p. 20, he speaks of the magnet turning to the pole,
+likening it to the turning of a "palea ab Ambro vel Iaspide et hujuscemodi
+lapillis lucidis."
+
+(5.) _Lychnis._ Pliny and St. Isidore speak of a certain stone _lychnis_,
+of a scarlet or flame colour, which, when warmed by the sun or between the
+fingers, attracts straws or leaves of papyrus. Pliny puts this stone
+amongst carbuncles, but it is much more probably _rubellite_, that is to
+say, red tourmaline.
+
+(6.) _Diamond._ In spite of the confusion already noted, _a propos_ of
+_adamas_ (Note to p. 47), between loadstone and diamond, there seems to be
+one distinct record of an attractive effect having been observed with a
+rubbed diamond. This was recorded by Fracastorio, _De sympathia et
+antipathia rerum_ (Giunta edition, Venice, MDLXXIIII, chap. v., p. 60
+_verso_), "cujus rei & illud esse signum potest, cum confricata quaeda vt
+Succinum, & Adamas fortius furculos trahunt." And (on p. 62 _recto_); "nam
+si per similitudine (vt supra diximus) fit haec attractio, cur magnes non
+potius magnetem trahit, [~q] ferrum, & ferrum non potius ad ferrum movetur,
+quam ad magnetem? quae nam affinitas est pilorum, & furculorum cum Electro,
+& Adamante? praesertim [~q] si cum Electro affines sunt, quomodo & cum
+Adamante affinitatem habebunt, qui dissimilis Electro est?" An
+incontestable case of the observation of the electrification of the diamond
+occurs in Gartias ab Horto. The first edition of his _Historia dei Semplici
+Aromati_ was publisht at Goa in India in 1563. In chapter xlviii. on the
+Diamond, occur these words (p. 200 of the Venetian edition of 1616):
+"Questo si bene ho sperimentato io piu volte, che due Diamanti perfetti
+fregati insieme, si vniscono di modo insieme, che non di leggiero li potrai
+separare. Et ho parimente veduto il Diamante dopo di esser ben riscaldato,
+tirare a se le festuche, non men, che si faccia l'elettro." See also
+Aldrovandi, _Musaeum Metallicum_ (Bonon., 1648, p. 947).
+
+Levinus Lemnius also mentions the Diamond along with amber. See his
+_Occulta naturae miracula_ (English edition, London, 1658, p. 199).
+
+[119] PAGE 48, LINE 16. Page 48, line 18. _Iris gemma._--The name _iris_
+was given, there can be little doubt, to clear six sided prisms of
+rock-crystal (quartz), which, when held in the sun's beams, cast a crude
+spectrum of the colours of the rainbow. The following is the account of it
+given in Pliny, book xxxvii., chap. vii. (p. 623 of the English version of
+1601):
+
+"... there is a stone in name called Iris: digged out of the ground it is
+in a certaine Island of the red sea, distant from the city Berenice three
+score miles. For the most part it resembleth Crystall: which is the reason
+that some hath tearmed it the root of Crystall. But the cause why they call
+it Iris, is, That if the beames of the Sunne strike upon it directly within
+house, it doth send from it against the walls that bee neare, the very
+resemblance both in forme and also in colour of a rainebow; and eftsoones
+it will chaunge the same in much varietie, to the great admiration of them
+that behold it. For certain it is knowne, that six angles it hath in manner
+of the Crystall: but they say that some of them have their sides rugged,
+and the same {40} unequally angled: which if they be laid abroad against
+the Sunne in the open aire, do scatter the beames of the Sunne, which light
+upon them too and fro: also that others doe yeeld a brightnes from
+themselves, and thereby illuminat all that is about them. As for the
+diverse colours which they cast forth, it never happeneth but in a darke or
+shaddowie place: whereby a man may know, that the varietie of colours is
+not in the stone Iris, but commeth by the reverberation of the wals. But
+the best Iris is that which representeth the greatest circles upon the
+wall, and those which bee likest unto rainebowes indeed."
+
+In the English translation of Solinus's _De Mirabilibus_ (_The excellent
+and pleasant worke of Julius Solinus containing the noble actions of
+humaine creatures, the secretes and providence of nature, the descriptions
+of countries ... tr. by A. Golding, gent._, Lond., 1587), chapter xv. on
+Arabia has the following:
+
+"Hee findeth likewise the Iris in the Red sea, sixe cornered as the
+Crystall: which beeing touched with the Sunnebeames, casteth out of him a
+bryght reflexion of the ayre like the Raynebowe."
+
+Iris is also mentioned by Albertus Magnus (_De mineralibus_, Venet., 1542,
+p. 189), by Marbodeus Gallus (_De lapidibus_, Par. 1531, p. 78), who
+describes it as "crystallo simulem sexangulam," by Lomatius (_Artes of
+curious Paintinge_, Haydocke's translation, Lond., 1598, p. 157), who says,
+"... the Sunne, which casting his beames vpon the _stone Iris_, causeth the
+_raine-bowe_ to appeare therein ...," and by "Sir" John Hill (_A General
+Natural History_, Lond., 1748, p. 179).
+
+Figures of the Iris given by Aldrovandi in the _Musaeum Metallicum_ clearly
+depict crystals of quartz.
+
+[120] PAGE 48, LINE 16. Page 48, line 18. _Vincentina, & Bristolla (Anglica
+gemma siue fluor)_. This is doubtless the same substance as the _Gemma
+Vincentij rupis_ mentioned on p. 54, line 16 (p. 54, line 18, of English
+Version), and is nothing else than the so-called "Bristol diamond," a
+variety of dark quartz crystallized in small brilliant crystals upon a
+basis of haematite. To the work by Dr. Thomas Venner (Lond., 1650),
+entitled _Via Recta_ or the _Bathes of Bathe_, there is added an appendix,
+_A Censure concerning the water of Saint Vincents Rocks neer Bristol (Urbs
+pulchra et Emporium celebre)_, in which, at p. 376, occurs this passage:
+"This Water of Saint _Vincents_ Rock is of a very pure, cleare, crystalline
+substance, answering to those crystalline Diamonds and transparent stones
+that are plentifully found in those Clifts."
+
+In the _Fossils Arranged_ of "Sir" John Hill (Lond., 1771), p. 123, is the
+following entry: "Black crystal. Small very hard heavy glossy. Perfectly
+black, opake. Bristol (grottos, glass)" referring to its use.
+
+The name _Vincentina_ is not known as occurring in any mineralogical book.
+Prof. H. A. Miers, F.R.S., writes concerning the passage: "_Anglica gemma
+sive fluor_ seems to be a synonym for _Bristolla_, or possibly for
+_Vincentina et Bristolla_. Both quartz and fluor are found at Clifton. In
+that case Vincentina and Bristolla refer to these two minerals, and if so
+one would expect Bristolla to be the Bristol Diamond, and Vincentina to be
+the comparatively rare Fluor spar from that locality."
+
+At the end of the edition of 1653 of Sir Hugh Plat's _Jewel House of Art
+and Nature_, is appended _A rare and excellent Discourse of Minerals,
+Stones, Gums, and Rosins; with the vertues and use thereof_, By D. B.
+_Gent_. Here, p. 218, we read:
+
+"We have in England a stone or mineral called a Bristol stone (because {41}
+many are found thereabouts) which much resembles the Adamant or Diamond,
+which is brought out of Arabia and Cyprus; but as it is wanting of the same
+hardnesse, so falls it short of the like vertues."
+
+[121] PAGE 48, LINE 18. Page 48, line 19. _Crystallus._--Rock-crystal.
+Quartz. Pliny's account of it (Philemon Holland's version of 1601, p. 604)
+in book xxxvii., chap, ii., is:
+
+"As touching Crystall, it proceedeth of a contrarie cause, namely of cold;
+for a liquor it is congealed by extreame frost in manner of yce; and for
+proofe hereof, you shall find crystall in no place els but where the winter
+snow is frozen hard: so as we may boldly say, it is verie yce and nothing
+else, whereupon the Greeks have give it the right name Crystallos, _i._
+Yce.... Thus much I dare my selfe avouch, that crystall groweth within
+certaine rockes upon the Alps, and these so steepe and inaccessible, that
+for the most part they are constrained to hang by ropes that shall get it
+forth."
+
+[122] PAGE 48, LINE 18. Page 48, line 20. _Similes etiam attrahendi vires
+habere videntur vitrum ... sulphur, mastix, & cera dura sigillaris._ If, as
+shown above, the electric powers of diamond and ruby had already been
+observed, yet Gilbert was the first beyond question to extend the list of
+_electrics_ beyond the class of precious stones, and his discovery that
+_glass_, _sulphur_, and _sealing-wax_ acted, when rubbed, like amber, was
+of capital importance. Though he did not pursue the discovery into
+mechanical contrivances, he left the means of that extension to his
+followers. To Otto von Guericke we owe the application of sulphur to make
+the first electrical machine out of a revolving globe; to Sir Isaac Newton
+the suggestion of glass as affording a more mechanical construction.
+
+Electrical attraction by natural products other than amber after they have
+been rubbed must have been observed by the primitive races of mankind.
+Indeed Humboldt in his _Cosmos_ (Lond., 1860, vol. i., p. 182) records a
+striking instance:
+
+"I observed with astonishment, on the woody banks of the Orinoco, in the
+sports of the natives, that the excitement of electricity by friction was
+known to these savage races, who occupy the very lowest place in the scale
+of humanity. Children may be seen to rub the dry, flat and shining seeds or
+husks of a trailing plant (probably a _Negretia_) until they are able to
+attract threads of cotton and pieces of bamboo cane."
+
+[123] PAGE 48, LINE 23. Page 48, line 25. _arsenicum_.--This is _orpiment_.
+See the _Dictionary of metallick words_ at the end of Pettus's _Fleta
+Minor_.
+
+[124] PAGE 48, LINE 23. Page 48, line 26. _in convenienti coelo
+sicco_.--The observation that only in a dry climate do rock-salt, mica, and
+rock-alum act as electrics is also of capital importance. Compare page 56.
+
+[125] PAGE 48, LINE 27. Page 48, line 31. _Alliciunt haec omnia non
+festucas modo & paleas._--Gilbert himself marks the importance of this
+discovery by the large asterisk in the margin. The logical consequence was
+his invention of the first _electroscope_, the _versorium non magneticum_,
+made of any metal, figured on p. 49.
+
+[126] PAGE 48, LINE 34. Page 48, line 36. _quod tantum siccas attrahat
+paleas, nec folia ocimi._--This silly tale that basil leaves were not
+attracted by amber arose in the _Quaestiones Convivales_ of Plutarch. It is
+repeated by Marbodeus and was quoted by Levinus Lemnius as true. Gilbert
+denounced it as nonsense. Cardan (_De Subtilitate_, Norimb., 1550, p. 132)
+had already contradicted the fable. "Trahit enim," he says, "omnia levia,
+paleas, festucas, ramenta {42} tenuia metallorum, & ocimi folia, perperam
+contradicente Theophrasto." Sir Thomas Browne specifically refuted it. "For
+if," he says, "the leaves thereof or dried stalks be stripped into small
+strawes, they arise unto Amber, Wax, and other Electricks, no otherwise
+then those of Wheat or Rye."
+
+[127] PAGE 48, LINE 34. Page 48, line 38. _Sed vt poteris manifeste
+experiri...._
+
+Gilbert's experimental discoveries in electricity may be summarized as
+follows:
+
+  1.  The generalization of the class of _Electrics_.
+  2.  The observation that damp weather hinders electrification.
+  3.  The generalization that electrified bodies attract everything,
+      including even metals, water, and oil.
+  4.  The invention of the non-magnetic _versorium_ or electroscope.
+  5.  The observation that merely warming amber does not electrify it.
+  6.  The recognition of a definite class of _non-electrics_.
+  7.  The observation that certain electrics do not attract if roasted or
+      burnt.
+  8.  That certain electrics when softened by heat lose their power.
+  9.  That the electric effluvia are stopped by the interposition of a
+      sheet
+      of paper or a piece of linen, or by moist air blown from the mouth.
+  10. That glowing bodies, such as a live coal, brought near excited amber
+      discharge its power.
+  11. That the heat of the sun, even when concentrated by a burning mirror,
+      confers no vigour on the amber, but dissipates the effluvia.
+  12. That sulphur and shell-lac when aflame are not electric.
+  13. That polish is not essential for an electric.
+  14. That the electric attracts bodies themselves, not the intervening
+      air.
+  15. That flame is not attracted.
+  16. That flame destroys the electrical effluvia.
+  17. That during south winds and in damp weather, glass and crystal, which
+      collect moisture on their surface, are electrically more interfered
+      with than amber, jet and sulphur, which do not so easily take up
+      moisture on their surfaces.
+  18. That pure oil does not hinder production of electrification or
+      exercise
+      of attraction.
+  19. That smoke is electrically attracted, unless too rare.
+  20. That the attraction by an electric is in a straight line toward it.
+
+[128] PAGE 48, LINE 35. Page 48, line 39. _quae sunt illae
+materiae._--Gilbert's list of electrics should be compared with those given
+subsequently by Cabeus (1629), by Sir Thomas Browne (1646), and by Bacon.
+The last-named list occurs in his _Physiological Remains_, published
+posthumously in 1679; it contains nothing new. Sir Thomas Browne's list is
+given in the following passage, which is interesting as using for the first
+time in the English language the noun _Electricities_:
+
+"Many stones also both precious and vulgar, although terse and smooth, have
+not this power attractive; as Emeralds, Pearle, Jaspis, Corneleans, Agathe,
+Heliotropes, Marble, Alablaster, Touchstone, Flint and Bezoar. Glasse
+attracts but weakely though cleere, some slick stones and thick glasses
+indifferently: Arsenic but weakely, so likewise glasse of Antimony, but
+Crocus Metallorum not at all. Saltes generally but weakely, as Sal Gemma,
+Alum, and also Talke, nor very discoverably by any frication: but if gently
+warmed at the fire, and wiped with a dry cloth, they will better discover
+their Electricities." _(Pseudodoxia Epidemica_, p. 79.)
+
+In the _Philosophical Transactions_, vol. xx., p. 384, is _A Catalogue of
+Electrical Bodies_ by the late Dr. Rob. Plot. It begins "Non solum
+succinum," and ends "alumen rupeum," being identical with Gilbert's list
+except that he calls "Vincentina & Bristolla" by the name "Pseudoadamas
+Bristoliensis."
+
+[129] PAGE 49, LINE 25. Page 49, line 30. _non dissimili modo._--The
+_modus_ {43} _operandi_ of the electrical attractions was a subject of much
+discussion; see Cardan, _op. citat._
+
+[130] PAGE 51, LINE 2. Page 51, line 1. _appellunt._--This appears to be a
+misprint for _appelluntur_.
+
+[131] PAGE 51, LINE 22. Page 51, line 23. _smyris._--Emery. This substance
+is mentioned on p. 22 as a magnetic body.
+
+[132] PAGE 52, LINE 1. Page 51, line 46. _gemmae ... vt Crystallus, quae ex
+limpida concreuit._ See the note to p. 48.
+
+[133] PAGE 52, LINE 30. Page 52, line 32. _ammoniacum._--Ammoniacum, or
+Gutta Ammoniaca, is described by Dioscorides as being the juice of a ferula
+grown in Africa, resembling galbanum, and used for incense.
+
+"_Ammoniack_ is a kind of Gum like Frankincense; it grows in Lybia, where
+_Ammon's_ Temple was." Sir Hugh Plat's _Jewel House of Art and Nature_ (Ed.
+1653, p. 223).
+
+[134] PAGE 52, LINE 38. Page 52, line 41. _duae propositae sunt causae ...
+materia & forma._--Gilbert had imbibed the schoolmen's ideas as to the
+relations of matter and form. He had discovered and noted that in the
+magnetic attractions there was always a verticity, and that in the
+electrical attractions the rubbed electrical body had no verticity. To
+account for these differences he drew the inference that since (as he had
+satisfied himself) the magnetic actions were due to _form_, that is to say
+to something immaterial--to an "imponderable" as in the subsequent age it
+was called--the electrical actions must necessarily be due to _matter_. He
+therefore put forward his idea that a substance to be an electric must
+necessarily consist of a concreted humour which is partially resolved into
+an effluvium by attrition. His discoveries that electric actions would not
+pass through flame, whilst magnetic actions would, and that electric
+actions could be screened off by interposing the thinnest layer of fabric
+such as sarcenet, whilst magnetic actions would penetrate thick slabs of
+every material except iron only, doubtless confirmed him in attributing the
+electric forces to the presence of these effluvia. See also p. 65. There
+arose a fashion, which lasted over a century, for ascribing to "humours,"
+or "fluids," or "effluvia," physical effects which could not otherwise be
+accounted for. Boyle's tracts of the years 1673 and 1674 on "effluviums,"
+their "determinate nature," their "strange subtilty," and their "great
+efficacy," are examples.
+
+[135] PAGE 53, LINE 9. Page 53, line 11. _Magnes vero...._--This passage
+from line 9 to line 24 states very clearly the differences to be observed
+between the magnetical and the electrical attractions.
+
+[136] PAGE 53, LINE 36. Page 53, line 41. _succino calefacto._--Ed. 1633
+reads _succinum_ in error.
+
+[137] PAGE 54, LINE 9. Page 54, line 11. _Plutarchus ... in quaestionibus
+Platonicis._--The following Latin version of the paragraph in _Quaestio
+sexta_ is taken from the bilingual edition publisht at Venice in 1552, p.
+17 _verso_, liber vii., cap. 7 (or, _Quaestio Septima_ in Ed. Didot, p.
+1230).
+
+"Electrum uero quae apposita sunt, nequaquam trahit, quem admodum nec lapis
+ille, qui sideritis nuncupatur, nec quicqu[=a] a seipso ad ea quae in
+propinquo sunt, extrinsecus assilit. Verum lapis magnes effluxiones quasdam
+tum graves, tum etiam spiritales emittit, quibus aer continuatus & iunctus
+repellitur. Is deinceps alium sibi proximum impellit, qui in orbem circum
+actus, atque ad inanem locum rediens, ui ferrum fecum rapit & trahit. At
+Electrum uim quandam flammae similem & spiritalem continet, quam quidem
+{44} tritu summae partis, quo aperiuntur meatus, foras eijcit. Nam
+leuissima corpuscula & aridissima quae prope sunt, sua tenuitate atque
+imbecillitate ad seipsum ducit & rapit, cum non sit adeo ualens, nec tantum
+habeat ponderis & momenti ad expellendam aeris copiam, ut maiora corpora
+more Magnetis superare possit & uincere."
+
+[138] PAGE 54, LINE 16. Page 54, line 18. _Gemma Vincentij rupis._--See the
+note to p. 48 _supra_, where the name _Vincentina_ occurs.
+
+[139] PAGE 54, LINE 30. Page 54, line 35. _orobi._--The editions of 1628
+and 1633 read _oribi_.
+
+[140] PAGE 55, LINE 34. Page 55, line 42. _in euacuati._--The editions of
+1628 and 1633 read _inevacuati_.
+
+[141] PAGE 58, LINE 21. Page 58, line 25. _assurgentem vndam ... declinat
+ab F._--These words are wanting in the Stettin editions.
+
+[142] PAGE 59, LINE 9. Page 59, line 9. _fluore._--This word is conjectured
+to be a misprint for _fluxu_ but it stands in all editions.
+
+[143] PAGE 59, LINE 22. Page 59, line 25. _Ruunt ad electria._--This
+appears to be a slip for _electrica_, which is the reading of the editions
+of 1628 and 1633.
+
+[144] PAGE 60, LINE 7. Page 60, line 9. _tan[=q] materiales radij._--The
+suggestion here of material _rays_ as the _modus operandi_ of electric
+forces seems to foreshadow the notion of electric lines of force.
+
+[145] PAGE 60, LINE 10. Page 60, line 12. _Differentia inter magnetica &
+electrica._--Though Gilbert was the first systematically to explore the
+differences that exist between the magnetic attraction of iron and the
+electric attraction of all light substances, the point had not passed
+unheeded, for we find St. Augustine, in the _De Civitate Dei_, liber xxi.,
+cap. 6, raising the question why the loadstone which attracts iron should
+refuse to move straws. The many analogies between electric and magnetic
+phenomena had led many experimenters to speculate on the possibility of
+some connexion between electricity and magnetism. See, for example,
+Tiberius Cavallo, _A Treatise on Magnetism_, London, 1787, p. 126. Also the
+three volumes of J. H. van Swinden, _Receuil de Memoires sur l'Analogie de
+Electricite et du Magnetisme_, La Haye, 1784. Aepinus wrote a treatise on
+the subject, entitled _De Similitudine vis electricae et magneticae_
+(Petropolis, 1758). This was, of course, long prior to the discovery, by
+Oersted, in 1820, of the real connexion between magnetism and the electric
+current.
+
+[146] PAGE 60, LINE 25. Page 60, line 31. _Coitionem dicimus, non
+attractionem._--See the remarks, at the outset of these Notes, on Gilbert's
+definitions of words.
+
+[147] PAGE 60, LINE 33. Page 61, line 1. _Orpheus in suis
+carminibus._--This passage is in the chapter [Greek: Lithika] of Orpheus,
+verses 301 to 327. See Note to p. 11, line 19.
+
+[148] PAGE 61, LINE 15. Page 61, line 19. _Platonis in Timaeo opinio_.--The
+passage runs (edition Didot, vol. ii., p. 240, or Stephanus, p. 80, C.):
+
+[Greek: Kai de kai ta ton hudaton panta rheumata eti de ta ton keraunon
+ptomata kai ta thaumazomena elektron peri tes helxeos kai ton Herakleion
+lithon, panton touton holke men ouk estin oudeni pote, to de kenon einai
+meden periothein te hauta tauta eis allela, to te diakrinomena kai
+sunkrinomena pros ten hauton diameibomena hedran hekasta ienai panta,
+toutois tois pathemasi pros allela sumplechtheisi tethaumatourgemena toi
+kata tropon zetounti phanesetai.]
+
+[149] PAGE 61, LINE 30. Page 61, line 38. The English version of the lines
+of Lucretius is from Busby's translation.
+
+[150] PAGE 62, LINE 5. {45} Page 62, line 7. _Iohannes Costaeus
+Laudensis._--Joannes Costa, of Lodi, edited Galen and Avicenna. He also
+wrote a _De universali stirpium Natura_ (Aug. Taurin., 1578).
+
+[151] PAGE 63, LINE 3. Page 63, line 4. _Cornelius Gemma 10.
+Cosmocrit._--This refers to the work _De Naturae Divinis Characterismis ...
+Libri ii. Avctore D. Corn. Gemma_ (Antv., 1575, lib. i., cap. vii., p.
+123).
+
+"Certe vt a magnete insensiles radij ferrum ad se attrahunt, ab echineide
+paruo pisciculo sistuntur plena nauigia, a catoblepa spiritu non homines
+solum, sed & alta serpentum genera interimuntur, & saxa dehiscunt."
+
+See also Kircher's _Magneticum Naturae Regnum_ (Amsterodami, 1667, p. 172),
+Sectio iv., cap. iii., De Magnete Navium, quae Remora seu Echeneis dicitur.
+See the note to p. 7, line 21.
+
+[152] PAGE 63, LINE 6. Page 63, line 7. _Guilielmus Puteanus._--Puteanus
+(Du Puys) wrote a work _De Medicamentorum quomodocunque Purgantium
+Facultatibus_, Libri ii. (Lugd., 1552), in which he talks vaguely about the
+substantial "form" of the magnet, and quotes Aristotle and Galen.
+
+[153] PAGE 63, LINE 21. Page 63, line 25. _Baptistae Portae._--The passage
+in the translation is quoted from the English version of 1658, pp. 191,
+192.
+
+[154] PAGE 64, LINE 4. Page 64, line 9. _Erudite magis Scaliger._--Gilbert
+pokes fun at Scaliger, whose "erudite" guess (that the motion of iron to
+the magnet was that of the offspring toward the parent) is to be found in
+his book _De Subtilitate, ad Cardanum_, Exercitatio CII. (Lutetiae, 1557,
+p. 156 _bis_).
+
+[155] PAGE 64, LINE 7. Page 64, line 11. _Diuus Thomas._--On p. 3 Gilbert
+had already spoken of St. Thomas Aquinas as a man of intellect who would
+have added more about the magnet had he been more conversant with
+experiments. The passage here quoted is from the middle of Liber vii. of
+his commentaries on the _de Physica_ of Aristotle, _Expositio Diui Thome
+Aquinatis Doctoris Angelici super octo libros Physicorum Aristotelis_, etc.
+(Venice, Giunta edition, 1539, p. 96 _verso_, col. 2).
+
+[156] PAGE 64, LINE 16. Page 64, line 24. _Cardinalis etiam
+Cusanus._--Cardinal de Cusa (Nicolas Khrypffs) wrote a set of dialogues on
+Statics, _Nicolai Cusani de staticis experimentis dialogus_ (1550), of
+which an English version appeared in London in 1650 with the title, _The
+Idiot in four books; the first and second of wisdom, the third of the
+minde, the fourth of statick experiments. By the famous and learned C.
+Cusanus._ In the fourth book _of statick Experiments, Or experiments of the
+Ballance_, occurs (p. 186) the following:
+
+    "_Orat._ Tell me, if thou hast any device whereby the vertues of stones
+    may be weighed.
+
+    "_Id._ I thinke the vertue of the Load-stone might be weighed, if
+    putting some Iron in one scale, and a Load-stone in the other, untill
+    the ballance were even, then taking away the Load-stone, and some other
+    thing of the same weight being put into the scale, the Load-stone were
+    holden over the Iron, so that that scale wou'd begin to rise; by reason
+    of the Load-stones attraction of the Iron, then take out some of the
+    weight of the other scale, untill the scale wherein the iron is, doe
+    sinke againe to the aequilibrium, or equality still holding the
+    Load-stone unmovable as it was; I beleeve that by weight of what was
+    taken out of the contrary scale, one might come proportionably to the
+    weight of the vertue or power of the Load-stone. And in like manner,
+    the vertue of a Diamond, might be found hereby, because {46} they say
+    it hinders the Load-stone from drawing of Iron; and so other vertues of
+    other stones, consideration, being alwayes had of the greatnesse of the
+    bodyes, because in a greater body, there is a greater power and
+    vertue."
+
+In the 1588 edition of Baptista Porta's _Magiae Naturalis Libri xx._, in
+lib. vii., cap. xviii., occurs the description of the use of the balance to
+which Gilbert refers.
+
+[157] PAGE 67, LINE 21. Page 67, line 22. _aeris rigore._--All editions
+read thus, but the sense seems to require _frigore_.
+
+[158] PAGE 67, LINE 27. Page 67, line 31. _Fracastorius._--See his _De
+Sympathia_, lib. i., cap. 5 (Giunta edition, 1574, p. 60).
+
+[159] PAGE 68, LINE 5. Page 68, line 6. _Thaletis Milesij._--See the note
+to p. 11, line 26.
+
+[160] PAGE 68, LINE 30. Page 68, line 35. _Ita coitio magnetica actus est
+magnetis, & ferri, non actio vnius._--See the introductory remarks to these
+notes. There is a passage in Scaliger's _De Subtilitate ad Cardanum_
+(Exercitat. CII., cap. 5, p. 156 _op. citat._) which may be compared with
+Gilbert's for its use of Greek terms: "Na cum uita dicatur actus animae,
+acceptus est abs te actus pro actione. Sed actus ille est [Greek:
+entelecheia], n[~o] autem [Greek: ergon]. At Magnetis attractio est [Greek:
+ergon], non aut[~e] [Greek: entelecheia]." To which Gilbert retorts: "non
+actio unius, utriusque [Greek: entelecheia]; non [Greek: ergon], [Greek:
+sunentelecheia] et conactus potius quam sympathia." He returns on p. 70 to
+the attack on Scaliger's metaphysical notions. There is a parallel passage
+in the _Epitome Naturalis Scientiae_ of Daniel Sennert (Oxoniae, 1664), in
+the chapter _De Motu_.
+
+[161] PAGE 71, LINE 4. Page 71, line 8. _vt in 8. physicorum Themistius
+existimat._--See _Omnia Themistii Opera_ (Aldine edition, 1533, p. 63),
+Book 8 of his Paraphrase on Aristotle's _Physica_.
+
+[162] PAGE 71, LINE 9. Page 71, line 14. _Quod vero Fracastorius._--_Op.
+citat._, lib. i., cap. 7, p. 62 _verso_.
+
+[163] PAGE 73, LINE 2. Page 73, line 2. _si A borealis._--The editions of
+1628 and 1633 omit the twelve words next following.
+
+[164] PAGE 73, LINE 9. Page 73, line 11. _ex minera._--_Minera_ is not a
+recognized word, even in late Latin. It occurs again, p. 97, line 12.
+
+[165] PAGE 77, LINE 2. Page 77, line 2. _multo magis._--This is an _a
+fortiori_ argument. It is interesting to find Gilbert comparing the
+velocity of propagation of magnetic forces in space with the velocity of
+light. The parallel is completed in line 13 by the consideration that as
+the rays of light require to fall upon an object in order that they may
+become visible, so the magnetic forces require a magnetic object in order
+to render their presence sensible.
+
+[166] PAGE 78, LINE 14. Page 78, line 16. _Orbem terrarum
+distinguunt._--The editions of 1628 and 1633 here add a figure of a globe
+marked with meridians and parallels of latitude, but with an erroneous
+versorium pointing to the south. These editions also both read
+_existentiam_ for the word _existentium_ in line 20.
+
+[167] PAGE 83, LINE 5. Page 83, line 5. _magnes longior maiora pondera
+ferri attollit._--Gilbert discovered the advantage, for an equal mass of
+loadstone, of an elongated shape. It is now well known that the specific
+amount of magnetism retained by elongated forms exceeds that in a short
+piece of the same material subjected to equal magnetizing forces.
+
+[168] PAGE 83, LINE 24. Page 83, line 28. _Non obstant crassa
+tabulata._--Gilbert has several times referred (_e.g._, on p. 77) to the
+way in which magnetic forces penetrate solid bodies. The experimental
+investigation in this chapter {47} is the more interesting because it shows
+that Gilbert clearly perceived the shielding action of iron to be due to
+iron conducting aside or diverting the magnetic forces.
+
+[169] PAGE 85, LINE 26. Page 85, line 31. _non conveniant._--The editions
+of 1628 and 1633 both read _et conveniant_.
+
+[170] PAGE 86, LINE 3. Page 86, line 3. _illud quod exhalat._--Literally,
+_that which exhales_, in the sense of that which escapes: but in modern
+English the verb exhale in the active voice is now not used of the
+substance that escapes, but is used of the thing which emits it. It must
+therefore be rendered _that which is exhaled_ (_i.e._, breathed out).
+
+[171] PAGE 86, LINE 13. Page 86, line 15. _Ita tota interposita moles
+terrestris._--Gilbert's notion that the gravitational force of the moon in
+producing the tides acts _through_ the substance of the earth may seem
+curiously expressed. But the underlying contention is essentially true
+to-day. The force of gravity is not cut off or screened off by the
+interposition of other masses. A recent investigation by Professor
+Poynting, F.R.S., has shown that so far as all evidence goes all bodies,
+even the densest, are transparent with respect to gravitational forces.
+
+[172] PAGE 86, LINE 18. Page 86, line 20. _Sed de aestus ratione
+alias._--There is no further discussion of the tides in _De Magnete_. But a
+short account is to be found in Gilbert's posthumous work _De Mundo nostro
+Sublunari Philosophia nova_ (Amsterdam, Elzevir, 1651), in Lib. v., the
+part which in the manuscript was left in English, and was turned into Latin
+by his brother. It comprises about fifteen quarto pages, from Cap. X. to
+Cap. XIX. inclusive, beginning with a characteristic diatribe against
+Taisnier, Levinus Lemnius, and Scaliger. But in assigning causes he himself
+goes wide of the mark. Proceeding by a process of elimination he first
+shows that the moon's light cannot be the cause that impels the tides.
+"Luna," he says, "non radio, non lumine, maria impellit. quomodo igitur?
+Sane corporum conspiratione, acque (ut similitudine rem exponam) Magnetica
+attractione." This cryptic utterance he proceeds to explain by a diagram,
+and adds: "Quare Luna non tam attrahit mare, quam humorem & spiritum
+subterraneum; nec plus resistit interposita terra, quam mensa, aut quicquam
+aliud densum, aut crassum, magnetis viribus."
+
+[173] PAGE 87, LINE 7. Page 87, line 9. _armatura._--Here this means the
+cap or snout of iron with which the loadstone was armed. This is apparently
+the first use of the term in this sense.
+
+In the _Dialogues of Galileo_ (p. 369 of Salusbury's _Mathematical
+Collections_, Dialogue iii.), Sagredus and Salviatus discuss the arming of
+the loadstone, and the increased lifting power conferred by adding an iron
+cap. Salviatus mentions a loadstone in the Florentine Academy which,
+unarmed, weighed six ounces, lifting only two ounces, but which when armed
+took up 160 ounces. Whereupon Galileo makes Salviatus say: "I extreamly
+praise, admire, and envy this Authour, for that a conceit so stupendious
+should come into his minde. ... I think him [_i.e._, Gilbert] moreover
+worthy of extraordinary applause for the many new and true Observations
+that he made, to the disgrace of so many fabulous Authours, that write not
+only what they do not know, but whatever they hear spoken by the foolish
+vulgar, never seeking to assure themselves of the same by experience,
+perhaps, because they are unwilling to diminish the bulk of their Books."
+
+[174] PAGE 87, LINE 12. Page 87, line 15. The reference to _lib._ 3 is {48}
+a misprint for _lib._ 2. It is corrected in the edition of 1633, but not in
+that of 1628.
+
+[175] PAGE 87, LINE 17. Page 87, line 21. _conactu._--The editions of 1628
+and 1633 read _conatu_.
+
+[176] PAGE 88, LINE 2. Page 88, line 3. _Coitio vero non fortior._--This
+heading to chap. xix., taken with the seven lines that follow, and the
+contrast drawn between _unitio_ and _coitio_, throw much light on the
+fundamental sense attached by Gilbert to the term _coitio_. It is here
+clearly used in the sense of _mutual tendency toward union_. Note also the
+contrasted use in chap. xx. of the verbs _cohaere_ and _adhaere_.
+Adhaerence connotes a one-sided force (an impossibility in physics),
+cohaerence a mutual force.
+
+[177] PAGE 90, LINE 9. Page 90, line 9. _nempe vt alter polus maius pondus
+arripiat._--This acute observation is even now not as well known as it
+ought to be. Only so recently as 1861 Siemens patented the device of
+fastening a mass of iron to one end of an electromagnet in order to
+increase the power of the other end. The fact, so far as it relates to
+permanent magnets was known to Servington Savery. See _Philos.
+Transactions_, 1729, p. 295.
+
+[178] PAGE 92, LINE 3. Page 92, line 4. _Suspendit in aere ferrum Baptista
+Porta._--Porta's experiment is thus described (_Natural Magick_, London,
+1658, p. 204): "_Petrus Pellegrinus_ saith, he shewed in another work how
+that might be done: but that work is not to be found. Why I think it
+extream hard, I shall say afterwards. But I say it may be done, because I
+have now done it, to hold it fast by an invisible band, to hang in the air;
+onely so, that it be bound with a small thread beneath, that it may not
+rise higher: and then striving to catch hold of the stone above, it will
+hang in the air, and tremble and wag itself."
+
+[179] PAGE 97, LINE 29. Page 97, line 33. _Sed quaeri potest ..._--The
+question here raised by Gilbert is whether the lifting-power of magnets of
+equal quality is proportional to their weight. If a stone weighing a drachm
+will lift a drachm, would a stone that weighs an ounce lift an ounce?
+Gilbert erroneously answers that this is so, and that the lifting-power of
+a loadstone, whether armed or unarmed, is proportional to its mass.
+
+The true law of the tractive force or lifting-power of magnets was first
+given in 1729 by James Hamilton (afterwards Earl of Abercorn) in a work
+entitled _Calculations and Tables Relating to the Attractive Virtue of
+Loadstones ... Printed_ [at London?] _in the Year_ 1729. (See also a paper
+in the _Philos. Transactions_, 1729-30, vol. xxxvi., p. 245). This work
+begins thus:
+
+"The Principle upon which these Tables are formed, is this: That if Two
+_Loadstones_ are perfectly Homogeneous, that is, if their Matter be of the
+same Specifick Gravity, and of the same Virtue in all Parts of one Stone,
+as in the other; and that Like Parts of their Surfaces are Cap'd or Arm'd
+with Iron; then the Weights they sustain will be as the Squares of the Cube
+Roots of the Weights of the _Loadstones_; that is, as their Surfaces."
+
+Upon lifting-power see also D. Bernoulli, _Acta Helvetica_, iii., p. 223,
+1758; P. W. Haecker, _Zur Theorie des Magnetismus_, Nuernberg, 1856; Van
+der Willigen, _Arch. du Musee Teyler_, vol. iv., Haarlem, 1878 ; S. P.
+Thompson, _Philos. Magazine_, July, 1888.
+
+In the book of James Hamilton, p. 5, he mentions a small terrella weighing
+139 English grains, which would sustain no less than 23,760 grains, and was
+valued at L21 13s. 10-3/4d.
+
+{49} In the _Musaeum Septalianum_ of Terzagus (Dertonae, 1664, p. 42) is
+mentioned a loadstone weighing twelve ounces which would lift sixty pounds
+of iron.
+
+Sir Isaac Newton had a loadstone weighing 3 grains, which he wore in a
+ring. It would lift 746 grains.
+
+Thomson's _British Annual_, 1837, p. 354, gives the following reference:
+"In the _Records of General Science_, vol. iii., p. 272, there is an
+interesting description of a very powerful magnet which was sent from
+Virginia in 1776 by the celebrated Dr. Franklin to Professor Anderson, of
+Glasgow. It is now in the possession of Mr. Crichton. It weighs 2-1/2
+grains, and is capable of supporting a load of 783 grains, which is
+equivalent to 313 times its own weight."
+
+[180] PAGE 99, LINE 10. Page 99, line 11. _Manifestum est._--In this, as in
+many other passages, Gilbert uses this expression in the sense that _it is
+demonstrable_ rather than meaning that _it is obvious_: for the fact here
+described is one that is not at all self-evident, but one which would
+become plain when the experiment had been tried. For other instances of
+this use of _manifestum_ see pages 144, line 20; 158, line 19; 162, line
+10.
+
+[181] PAGE 100, LINE 20. Page 100, line 24. _si per impedim[=e]ta ...
+pervenire possunt._--All editions agree in this reading, but the sense
+undoubtedly requires _non possint_. Compare p. 91, line 21.
+
+[182] PAGE 102, LINE 4. Page 102, line 4. _capite_ 4.--This is a misprint
+for _capite_ 40, and is retained in the later editions. In the quotation
+from Baptista Porta, where the English version of 1658 is adhaered to, the
+words "& deturbat eam" have been omitted by the translator.
+
+[183] PAGE 107, LINE 16. Page 107, line 18. _Cardanus scribit._--The
+alleged perpetual motion machine is mentioned in _De rerum varietate_,
+_lib._ 9, cap. xlviii. (Basil., 1581, p. 641). See also the Note to p. 223.
+For Peregrinus and for Taisnier, see the note to p. 5, lines 8 and 12.
+
+[184] PAGE 107, LINE 19. Page 107, line 21. _Antonij de Fantis._--His work
+is: _Tabula generalis scotice subtilitatis octo Sectionibus vniuersam
+Doctoris Subtilis Periti[=a] c[=o]plect[=e]s: ab excellentissimo doctore
+Antonio de F[=a]tis taruisino edita ..._ Lugd., 1530.
+
+[185] PAGE 108, LINE 26. Page 108, line 31. _Cusani in staticis._--See the
+note to p. 64, line 16.
+
+[186] PAGE 108, LINE 33. Page 108, line 41. _Languidi ... tardius
+acquiescunt._--The editions of 1628 and 1633 omit these seven words.
+
+[187] PAGE 109, LINE 11. Page 109, line 13. _halinitro._--Either native
+carbonate of soda or native carbonate of potash might be meant, but not
+saltpetre. Scaliger, in his _De Subtilitate ad Cardanum_ (Lutet., 1557, p.
+164), _Exercitatio_ CIII., 15, under the title, _Nitrum non est Salpetrae_,
+says: "More tuo te, tuaque confundis. Salpetrae inter salis fossilis ponis
+hic. Mox Halinitrum inter salis, & nitri naturam, speciem obtinere."
+
+"_Sal nitrum_ is salt which is boiled out of the earth, especially fat
+earth, as in stables, or any place of excrements." (_A Chymicall Dictionary
+explaining Hard Places and Words met withall in the Writings of Paracelsus
+..._, Lond., 1650.)
+
+[188] PAGE 109, LINE 20. Page 109, line 23. _arte ioculatoria._--Edition
+1628, _joculatoria_; edition 1633, _jaculatoria_.
+
+[189] PAGE 110, LINE 11. Page 110, line 12. _qualis fuit Antonij
+denarius._--The Elizabethan version of Pliny (book xxxiii., ch. ix., p.
+479) runs thus: {50} "To come now unto those that counterfeit money.
+_Antonius_ whiles hee was one of the three usurping Triumvirs, mixed yron
+with the Romane silver denier. He tempered it also with the brasen coine,
+and so sent abroad false and counterfeit money."
+
+Georgius Agricola (_De Natura Fossilium_, p. 646) says:
+
+"Sed ea fraus capitalis est, non aliter ac eorum qui adulterinas monetas
+cudunt, argento miscentes multam plumbi candidi portionem, aut etiam ferri,
+qualis fuit Antonii denarius, ut Plinius memoriae tradidit. Nunc dicam de
+candido plumbo, nam majoris pretii est quam aes. In quod plumbum album,
+inquit Plinius, addita aeris tertia portione candidi adulteratur stannum."
+
+[190] PAGE 111, LINE 3. Page 111, line 3. _Meminerunt Chatochitis lapis
+Plinius, atque Iulius Solinus._--The passage in Pliny (English version of
+1601, book xxxvii., ch. x., p. 625) runs:
+
+"Catochitis is a stone proper unto the Island Corsica: in bignesse it
+exceedeth ordinarie pretious stones: a wonderfull stone, if all be true
+that is reported thereof, and namely, That if a man lay his hand thereon,
+it will hold it fast in manner of a glewie gum."
+
+[191] PAGE 111, LINE 7. Page 111, line 7. _Sagda vel Sagdo._--Albertus
+Magnus in _De Mineralibus_ (Venet., 1542, p. 202) says:
+
+"Sarda quem alij dicunt Sardo lapis est qui se habet ad tabulas ligni sicut
+magnes ad ferr[=u], et ideo adhaeret ita fortiter tabulis nauium quod
+euelli n[=o] possit, nisi abscindatur cum ipso ea pars tabulae cui
+inhaeserit, est aut[=e] in colore purissimus nitens."
+
+And Pliny (_op. citat._, p. 629):
+
+"Sagda is a stone, which the Chaldeans find sticking to ships, and they say
+it is greene as Porrets or Leekes."
+
+[192] PAGE 111, LINE 8. Page 111, line 8. _Euace._--Evax, king of the
+Arabs, is said to have written to Nero a treatise on the names, colours,
+and properties of stones. See the note on Marbodaeus, p. 7, line 20.
+
+[193] PAGE 113, LINE 14. Page 113, line 19. _repulsus sit._ The words read
+thus in all editions, but the sense requires _repulsa sint._
+
+[194] PAGE 113, LINE 23. Page 113, line 29. _Electrica omnia alliciunt
+cuncta, nihil omnino fugant vnquam, aut propellunt._ This denial of
+electrical repulsion probably arose from the smallness of the pieces of
+electric material with which Gilbert worked. He could hardly have failed to
+notice it had he used large pieces of amber or of sealing-wax. Electrical
+repulsion was first observed by Nicolas Cabeus, _Philosophia Magnetica_,
+Ferrara, 1629; but first systematically announced by Otto von Guericke in
+his treatise _Experimenta Nova (ut vocantur) Magdeburgica, de Vacuo Spatio_
+(Amstel., 1672).
+
+[195] PAGE 113, LINE 29. Page 113, line 37. _cum de calore quid sit
+disputabimus._--The discussion of the nature of heat is to be found in
+Gilbert's _De Mundo nostro Sublunari_ (Amstel., 1651), lib. i., cap. xxvi.,
+pp. 77-88.
+
+[196] PAGE 115, LINE 23. Page 115, line 23. _trium vel quatuor
+digitorum._--Here as in all other places in Gilbert, _digitus_ means a
+finger's breadth, so that three or four digits means a length of two or
+three inches, or from six to eight centimetres.
+
+[197] PAGE 117, LINE 26. Page 117, line 25. _ille Thebit Bencorae
+trepidationis motus._
+
+"Trepidation in the ancient Astronomy denotes a motion which in the
+Ptolemaic system was attributed to the firmament, in order to account for
+{51} several changes and motions observed in the axis of the world, and for
+which they could not account on any other principle." (Barlow's
+_Mathematical Dictionary_.)
+
+[198] PAGE 118, LINE 10. Page 118, line 8. _cuspis is aut lilium._--Gilbert
+uses _cuspis_ or _lilium_ always of the North-pointing end of the needle.
+Sir Thomas Browne speaks of "the lilly or northern point"; but he differs
+from Gilbert in saying "the _cuspis_ or Southern point" (_Pseudodoxia
+Epidemica_, 1650, p. 46). Only in one place (p. 101, line 5) does Gilbert
+speak of _cuspis meridionalis_. Everywhere else the south-pointing end is
+called the _crux_.
+
+[199] PAGE 118, LINE 15. Page 118, line 13. _nam aeque potens est._--Later
+observation showed this view to be incorrect. The horizontal component of
+the earth's magnetic field is not equally strong all over the globe, and
+the sluggishness of the needle's return to its position of rest is not due
+to the supporting pin becoming blunt with wear. The value of the horizontal
+component is zero at the north magnetic pole, and increases toward the
+magnetic equator. It is greatest near Singapore and in Borneo, being there
+more than twice as great as it is at London. (See Captain Creak in _Report
+of Voyage of H.M.S. Challenger, Physics and Chemistry_, vol. ii., part vi.,
+1889.)
+
+[200] PAGE 119, LINE 5. Page 119, line 2. _lapis._--Both Stettin editions
+read _lapidis._
+
+[201] PAGE 119, LINES 9-11. Page 119, lines 7-9. The gist of the whole book
+is summarized in these lines. They furnish a cardinal example of that
+inductive reasoning which was practist by Gilbert, and of which Bacon
+subsequently posed as the apostle. Compare pages 41 and 211.
+
+[202] PAGE 120, LINE 8. Page 120, line 5. _dicturi sumus_.--Change of
+verticity is treated of in book iii., chap. x., pp. 137 to 140.
+
+[203] PAGE 125, LINE 24. Page 125, line 29. _appositam._--All editions give
+this word, though the sense requires _appositum._
+
+[204] PAGE 128, LINE 9. Page 128, line 11. _non nimis longum._--The
+editions of 1628 and 1633 read (wrongly) _minus_ instead of _nimis_.
+
+[205] PAGE 130, LINE 12. Page 130, line 14. The word _hunc_ in the folio of
+1600 is corrected in ink to _tunc_, and the Stettin editions both read
+_tunc_.
+
+[206] PAGE 132, LINE 9. Page 132, line 10. _minimus & nullius
+ponderis._--The editions of 1628 and 1633 both wrongly read _est_ for _&_.
+
+[207] PAGE 132, LINE 28. Page 133, line 1. _nutat._--The editions of 1628
+and 1633 both wrongly read _mutat_.
+
+[208] PAGE 134, LINE 22. Page 134, line 25. _in recta sphaera._--The
+meaning of the terms a _right_ or _direct sphere_, an _oblique sphere_ and
+a _parallel sphere_ are explained by Moxon on pages 29 to 31 of his book _A
+Tutor to Astronomy and Geography_ (Lond., 1686):
+
+"A _Direct Sphere_ hath both the _Poles_ of the _World_ in the Horizon ...
+It is called a _Direct Sphere_, because all the _Celestial_ Bodies, as
+_Sun_, _Moon_, and _Stars_, &c. By the _Diurnal_ Motion of the _Primum
+Mobile_, ascend directly Above, and descend directly Below the _Horizon_.
+They that Inhabit under the _Equator_ have the _Sphere_ thus posited."
+
+"An _Oblique Sphere_ hath the _Axis_ of the _World_ neither _Direct_ nor
+_Parallel_ to the _Horizon_, but lies aslope from it."
+
+"A _Parallel Sphere_ hath one _Pole_ of the _World_ in the _Zenith_, the
+other in the _Nadir_, and the _Equinoctial_ Line in the _Horizon_."
+
+[209] PAGE 136, LINE 1. Page 136, line 1. _praesenti._--The editions of
+1628 and 1633 read _sequenti_, to suit the altered position of the figure.
+
+[210] PAGE 137, LINE 24. {52} Page 137, line 28. _atque ille statim._--The
+Stettin editions both wrongly read illi.
+
+[211] PAGE 139. There is a curious history to this picture of the
+blacksmith in his smithy striking the iron while it lies north and south,
+and so magnetizing it under the influence of the earth's magnetism.
+Woodcuts containing human figures are comparatively rare in English art of
+the sixteenth century; a notable exception being Foxe's _Acts and
+Monuments_ with its many crude cuts of martyrdoms. The artist who prepared
+this cut of the smith took the design from an illustrated book of Fables by
+one Cornelius Kiliani or Cornelius van Kiel entitled _Viridarium Moralis
+Philosophiae, per Fabulas Animalibus brutis attributas traditae, etc._
+(Coloniae, 1594). This rare work, of which there is no copy in the British
+Museum, is illustrated by some 120 fine copper-plate etchings printed in
+the text. On p. 133 of this work is an etching to illustrate the fable
+_Ferrarii fabri et canis_, representing the smith smiting iron on the
+anvil, whilst his lazy dog sleeps beneath the bellows. The cut on p. 139 of
+Gilbert gives, as will be seen by a comparison of the pictures just the
+same general detail of forge and tools; but the position of the smith is
+reversed right for left, the dog is omitted, and the words _Septrenio_ and
+_Auster_ have been added.
+
+[Illustration]
+
+In the Stettin edition of 1628 the picture has again been turned into a
+copper-plate etching separately printed, is reversed back again left for
+right, while a compass-card is introduced in the corner to mark the
+north-south direction.
+
+In the Stettin edition of 1633 the artist has gone back to Kiliani's
+original {53} plate, and has re-etched the design very carefully, but
+reversing it all right for left. As in the London version of 1600, the dog
+is omitted, and the words _Septentrio_ and _Auster_ are added. Some of the
+original details--for example, the vice and one pair of pincers--are left
+out, but other details, for instance, the cracks in the blocks that support
+the water-tub, and the dress of the blacksmith, are rendered with slavish
+fidelity.
+
+It is perhaps needless to remark that the twelve copper-plate etchings in
+the edition of 1628, and the twelve completely different ones in that of
+1633, replace certain of the woodcuts of the folio of 1600. For example,
+take the woodcut on p. 203 of the 1600 edition, which represents a simple
+dipping-needle made by thrusting a versorium through a bit of cork and
+floating it, immersed, in a goblet of water. In the 1633 edition this
+appears, slightly reduced, as a small inserted copper-plate, with nothing
+added; but in the 1628 edition it is elaborated into a full-page plate (No.
+xi.) representing the interior, with shelves of books, of a library on the
+floor of which stands the goblet--apparently three feet high--with a globe
+and an armillary sphere; while beside the goblet, with his back to the
+spectator, is seated an aged man, reading, in a carved armchair. This
+figure and the view of the library are unquestionably
+copied--reversed--from a well-known plate in the work _Le Diverse &
+Artificiose Machine_ of Agostino Ramelli (Paris, 1558).
+
+In the Emblems of Jacob Cats (_Alle de Wercken_, Amsterdam, 1665, p. 65) is
+given an engraved plate of a smith's forge, which is also copied--omitting
+the smith--from Kiliani's _Viridarium_.
+
+[212] PAGE 140, LINE 2.. Page 140, line 2. _praecedenti._--This is so
+spelled in all editions, though the sense requires _praecedente_.
+
+[213] PAGE 141, LINE 21. Page 141, line 24. _quod in epistola quadam
+Italica scribitur._--The tale told by Filippo Costa of Mantua about the
+magnetism acquired by the iron rod on the tower of the church of St.
+Augustine in Rimini is historical. The church was dedicated to St. John,
+but in the custody of the Augustinian monks. The following is the account
+of it given by Aldrovandi, _Musaeum Metallicum_ (1648, p. 134), on which
+page also two figures of it are given:
+
+"Aliquando etiam ferrum suam mutat substantiam, dum in magnetem
+conuertitur, & hoc experientia constat, nam Arimini supra turrim templi S.
+Ioannis erat Crux a baculo ferreo ponderis centum librarum sustentata, quod
+tractu temporis adeo naturam Magnetis est adeptum, vt, illivs instar,
+ferrum traheret: hinc magna admiratione multi tenentur, qua ratione ferrum,
+quod est metallum in Magnetem, qui est lapis transmutari possit;
+Animaduertendum est id a maxima familiaritate & sympathia ferri, & magnetis
+dimanare cum Aristoteles in habentibus symbolum facilem transitum semper
+admiserit. Hoc in loco damus imaginem frusti ferri in Magnetem transmutati,
+quod clarissimo viro Vlyssi Aldrouando Iulius Caesar Moderatus diligens
+rerum naturalium inquisitor communicauit; erat hoc frustum ferri colore
+nigro, & ferrugineo, crusta exteriori quodammodo albicante." And further on
+p. 557.
+
+"Preterea id manifestissimum est; quoniam Arimini, in templo Sancti
+Ioannis, fuit Crux ferrea, quae tractu temporis in magnetem conuersa est, &
+ab vno latere ferrum trahebat, & ab altero respuebat." See also Sir T.
+Browne's _Pseudodoxia Epidemica_ (edition of 1650, p. 48), and Boyle's
+tract, _Experiments and Notes about the Mechanical Production of Magnetism_
+(London, 1676, p. 12).
+
+{54} Another case is mentioned in Dr. Martin Lister's _A Journey to Paris_
+(Lond., 1699, p. 83). "He [Mr. Butterfield] shewed us a Loadstone sawed off
+that piece of the Iron Bar which held the Stones together at the very top
+of the Steeple of _Chartres_. This was a thick Crust of Rust, part of which
+was turned into a strong Loadstone, and had all the properties of a Stone
+dug out of the Mine. _Mons. de la Hire_ has Printed a Memoir of it; also
+Mons. _de Vallemont_ a Treatise. The very outward Rust had no Magnetic
+Virtue, but the inward had a strong one, as to take up a third part more
+than its weight unshod." Gassendi and Grimaldi have given other cases.
+
+Other examples of iron acquiring strong permanent magnetism from the earth
+are not wanting. The following is from Sir W. Snow Harris's _Rudimentary
+Magnetism_ (London, 1872, p. 10).
+
+"In the _Memoirs of the Academy of Sciences_ for 1731, we find an account
+of a large bell at Marseilles having an axis of iron: this axis rested on
+stone blocks, and threw off from time to time great quantities of rust,
+which, mixing with the particles of stone and the oil used to facilitate
+the motion, became conglomerated into a hardened mass: this mass had all
+the properties of the native magnet. The bell is supposed to have been in
+the same position for 400 years."
+
+[214] PAGE 142, LINE 13. Page 142, line 15. _tunc planetae & corpora
+coelestia._--Gilbert's extraordinary detachment from all metaphysical and
+ultra-physical explanations of physical facts, and his continual appeal to
+the test of experimental evidence, enabled him to lift the science of the
+magnet out of the slough of the dark ages. This passage, however, reveals
+that he still gave credence to the _nativities_ of judicial Astrology, and
+to the supposed influence of the planets on human destiny.
+
+[215] PAGE 144, LINE 14. Page 144, line 14. _ijdem._--The editions of 1628
+and 1633 erroneously read _iisdem_.
+
+[216] PAGE 147, LINE 27. Page 147, line 29. _ex optimo aciario._--Gilbert
+recommended that the compass-needle should be of the best steel. Though the
+distinction between iron and steel was not at this time well established,
+there is no reason to doubt that by _aciarium_ was meant edge-steel as used
+for blades. Barlowe, in his _Magneticall Advertisements_ (Lond., 1616), p.
+66, gives minute instructions for the fashioning of the compass-needle. He
+gives the preference to a pointed oval form, and describes how the steel
+must be hardened by heating to whiteness and quenching in water, so that it
+is "brickle in a manner as glass it selfe," and then be tempered by
+reheating it over a bar of red hot iron until it is let down to a blue
+tint. Savery (_Philos. Trans._, 1729) appears to have been the first to
+make a systematic examination of the magnetic differences between hard
+steel and soft iron.
+
+Instructions for touching the needle are given in the _Arte de Nauegar_ of
+Pedro de Medina (Valladolid, 1545, lib. vi., cap. 1).
+
+[217] PAGE 149, LINE 8. Page 149, line 9. _per multa saecula._--Compare
+Porta's assertion (p. 208, English edition) "iron once rubbed will hold the
+vertue a hundred years." Clearly not a matter within the actual experience
+of either Porta or Gilbert.
+
+[218] PAGE 153, LINE 2. Page 153, line 2. _Cardani ab ortu stellae in cauda
+vrsae._--What Cardan said (_De Subtilitate_, _Edit. citat._, p. 187) was:
+"ortum stellae in cauda ursae minoris, quae quinque partibus orientalior
+est polo mundi, respicit."
+
+[219] PAGE 153, LINE 21. Page 153, line 26. _sequitur quod versus terram
+magnam, siue continentem ... a vero polo inclinatio magnetica
+fiat._--Gilbert {55} goes on to point out how, at that date, all the way up
+the west European coast from Morocco to Norway, the compass is deflected
+eastward, or toward the elevated land. He argued that this was a universal
+law.
+
+In _Purchas his Pilgrimes_ (Lond., 1625), in the Narrative, in vol. iii.,
+of Bylot and Baffin's Voyage of 1616, there is mentioned an island between
+Whale-Sound and Smith's Sound, where there had been observed a larger
+variation than in any other part of the world. Purchas, in a marginal note,
+comments on this as follows: "Variation of the Compass 56deg to the West,
+which may make questionable D. Gilbert's rule, tom. 1., l. 2, c. 1, that
+where more Earth is more attraction of the Compass happeneth by variation
+towards it. Now the known Continents of Asia, &c., must be unspeakably more
+than here there can be, & yet here is more variation then about Jepan,
+Brasil, or Peru, &c."
+
+Gilbert's view was in truth founded on an incomplete set of facts. At that
+time, as he tells us, the variation of the compass at London was 11-1/3
+degrees eastward. But he did not know of the secular change which would in
+about fifty-seven years reduce that variation to zero. Still less did he
+imagine that there would then begin a westward variation which in the year
+1816 should reach 24deg 30', and which should then steadily diminish so
+that in the year 1900 it should stand at 16deg 16' westward. For an early
+discussion of the changes of the variation see vol. i. of the
+_Philosophical Transactions_ (Abridged), p. 188. Still earlier is the
+classical volume of Henry Gellibrand, _A Discovrse Mathematical on the
+Variation of the Magneticall Needle_ (Lond., 1635). Gilbert heads chapter
+iii. of book iiii. (p. 159) with the assertion _Variatio uniuscuiusque loci
+constans est_, declaring that to change it would require the upheaval of a
+continent. Gellibrand combats this on p. 7 of the work mentioned. He says:
+
+    "Thus hitherto (according to the Tenents of all our _Magneticall_
+    Philosophers) we have supposed the variations of all particular places
+    to continue one and the same. So that when a Seaman shall happly
+    returne to a place where formerly he found the same variation, he may
+    hence conclude he is in the same former _Longitude_. For it is the
+    Assertion of _Mr. Dr. Gilberts_. _Variatio vnicuiusq; Loci constans
+    est_, that is to say, the same place doth alwayes retaine the same
+    variation. Neither hath this Assertion (for ought I ever heard) been
+    questioned by any man. But most diligent magneticall observations have
+    plainely offred violence to the same, and proved the contrary, namely
+    that the variation is accompanied with a variation."
+
+In 1637 Henry Bond wrote in the _Sea-Mans Kalendar_ that in the year 1657
+the variation would be zero at London. Compare Bond's _Longitude Found_
+(Lond., 1676, p. 3).
+
+As to inconstancy of the variation in one place see further Fournier's
+_Hydrographie_ (Paris, 1667, liv. xi., ch. 12, p. 413), and Kircher,
+_Magnes_ (Colon. Agripp., 1643, p. 418).
+
+[220] PAGE 157, LINE 4. Page 157, line 5. _perfecto._--Though this word is
+thus in all editions, it ought to stand _perfecta_, as in line 10 below.
+
+[221] PAGE 157, LINE 11. Page 157, line 13. _varietas_, for _variatio_.
+
+[222] PAGE 160, LINE 20. Page 160, line 23. _in Borrholybicum._--This name
+for the North-west, or North-North-West, is rarely used. It is found on the
+chart or windrose of the names of the winds on pp. 151 and 152 of the
+_Mecometrie de l'Eyman_ of G. Nautonier (1602). Here the name
+_Borrolybicus_ is given as a synonym for _Nortouest Galerne_, or [Greek:
+Olumpias], while the two winds on the points next on the western and
+northern sides respectively are called _Upocorus_ and _Upocircius_.
+
+{56} In Swan's _Specvlvm Mundi_ (Camb., 1643, p. 174) is this explanation:
+"Borrholybicus is the North-west wind."
+
+In Kircher's _Magnes_ (Colon. Agripp., 1643, p. 434) is a table of the
+names of the thirty-two winds in six languages, where _Borrolybicus_ is
+given as the equivalent of _Maestro_ or _North-West_.
+
+[223] PAGE 161, LINE 2. Page 161, line 2. _Insula in Oceano variationem non
+mutat._--The conclusions derived from the magnetic explorations of the
+Challenger expedition, 1873-1876, are briefly these: That in islands north
+of the magnetic equator there is a tendency to produce a local
+perturbation, attracting the north-seeking end of the needle downwards, and
+horizontally towards the higher parts of the land; while south of the
+magnetic equator, the opposite effects are observed. (See _Challenger
+Reports, Physics and Chemistry_, vol. ii., part vi., _Report on the
+Magnetical Results_ by Staff-Commander Creak, F.R.S.)
+
+[224] PAGE 162, LINE 2. Page 162, line 3. _quare & respectiuum punctum ...
+excogitauit._--The passage referred to is in _The newe Attractiue_ of
+Robert Norman (Lond., 1581), chap. vi.
+
+"Your reason towards the earth carrieth some probabilitie, but I prove that
+there be no _Attractive_, or drawing propertie in neyther of these two
+partes, then is the _Attractive_ poynt lost, and falsly called the poynt
+_Attractive_, as shall be proved. But because there is a certayne point
+that the Needle alwayes respecteth or sheweth, being voide and without any
+_Attractive_ propertie: in my judgment this poynt ought rather to bee
+called the point Respective ... This Poynt _Respective_, is a certayne
+poynt, which the touched Needle doth alwayes _Respect_ or shew ..."
+
+[225] PAGE 165, LINE 2. Page 165, line 2. _De pyxidis nauticae vsitatae
+compositione._--Gilbert's description of the usual construction of the
+mariner's compass should be compared with those given by Levinus Lemnius in
+_The Secret Miracles of Nature_ (London, 1658); by Lipenius in _Navigatio
+Salomonis Ophiritica_ (Witteb., 1660, p. 333); and with that given in
+Barlowe's _Navigators Supply_ (London, 1597). See also Robert Dudley's
+_Dell' Arcano del Mare_ (Firenze, 1646).
+
+[226] PAGE 165 deals with the construction; the process of magnetizing by
+the loadstone had already been discussed in pp. 147 to 149. It is
+interesting to see that already the magnetized part attached below the
+compass-card was being specialized in form, being made either of two pieces
+bent to meet at their ends, or of a single oval piece with elongated ends.
+The marking of the compass-card is particularly described. It was divided
+into thirty-two points or "winds," precisely as the earlier "wind-rose" of
+the geographers, distinguisht by certain marks, and by a lily--or
+fleur-de-lys--indicating the North. Stevin in the _Havenfinding Art_
+(London, 1599), from which work the passage on p. 167 is quoted, speaking
+on p. 20 of "the Instrument which we call the Sea-directorie, some the
+nautical box, ... or the sea compasse," mentions the "Floure de luce"
+marking the North.
+
+The legend which assigns the invention of the compass to one Goia or Gioja
+of Amalfi in 1302 has been already discussed in the Note to page 4. Gilbert
+generously says that in spite of the adverse evidence he does not wish to
+deprive the Amalfians of the honour of the construction adopted in the
+compasses used in the Mediterranean. But Baptista Porta the Neapolitan, who
+wrote forty years before Gilbert, discredited the legend. "_Flavius_ saith,
+an Italian found it out first, whose name was _Amalphus_, born in our {57}
+Campania. But he knew not the Mariners Card, but stuck the needle in a
+reed, or a piece of wood, cross over; and he put the needles into a vessel
+full of water that they might flote freely." (Porta's _Natural Magick_,
+English translation, London, 1658, p. 206.) See also Lipenius (_op. citat._
+p. 390).
+
+The pivotting of the needle is expressly described in the famous _Epistle_
+on the Magnet of Peter Peregrinus, which was written in 1269. Gasser's
+edition, _Epistola Petri Peregrini ... de magnete_, was printed in Augsburg
+in 1558. In Part II., cap. 2, of this letter, a form of instrument is
+described for directing one's course to towns and islands, and any places
+in fact on land or sea. This instrument consists of a vessel like a turned
+box (or _pyxis_) of wood, brass, or any solid material, not deep, but
+sufficiently wide, provided with a cover of glass or crystal. In its middle
+is arranged a slender axis of brass or silver, pivotted at its two ends
+into the top and the bottom of the box. This axis is pierced orthogonally
+with two holes, through one of which is passed the steel needle, while
+through the other is fixed square across the needle another stylus of
+silver or brass. The glass cover was to be marked with two cross lines
+north-south and east-west; and each quadrant was to be divided into ninety
+degrees. This the earliest described pivotted compass was therefore of the
+cross-needle type, a form claimed as a new invention by Barlowe in 1597.
+The first suggestion of suspending a magnetic needle by a thread appears to
+be in the _Speculum Lapidum_ of Camillus Leonardus (Venet., 1502, fig. k
+ij, lines 25-31): "Na tacto ferro ex una [=p]te magnetis ex opposita eius
+[=p]te appropinquato fugat: ut ex[=p]i[~e]tia docet de acu appenso filo."
+
+The earliest known examples of the "wind-rose" are those in certain
+parchment charts preserved in the Biblioteca Marciana in Venice. These go
+back to 1426 or 1436, the best being ascribed to Andrea Bianco. They have
+the North indicated by a fleur-de-lys, a trident, a simple triangle, or a
+letter T; while the East is distinguisht by a cross. The West is marked
+with a P. (see Fincati, _op. citat._). The eight marks in order, clock
+wise, run thus,
+
+  [Lily] (or T).  G.   [Cross] (or L)   S.   O.   A (or L).   P.   M.
+
+The letters correspond to the Italian names of the principal winds:
+
+  Tramontano                  North.
+  Greco                       North-East.
+  Levante                     East.
+  Sirocco                     South-East.
+  Ostro                       South.
+  Africo or Libeccio          South-West.
+  Ponente                     West.
+  Maestro                     North-West.
+
+Wind-roses marked with the names of the minor winds are found in
+Nautonier's _Mecometrie de l'Eyman_ (Vennes, 1602-1604, pp. 151-152), and
+Kircher's _Magnes Siue de Arte Magnetica_ (Colon. Agripp., 1643, p. 432).
+The description above given of the early Venetian wind-roses _exactly_
+describes the compass-card as depicted by Pedro de Medina in his _Arte de
+Nauegar_ (Valladolid, 1545, folio lxxx.), in the sixth book entitled "las
+aguias de navegar"; while in the _Breve compendio de la sphera_ of Martin
+Cortes (Sevilla, 1551, cap. iii., _de la piedrayman_) a similar wind-rose,
+without the letters, is found.
+
+{58} In the _De Ventis et navigatione_ of Michaele Angelo Blondo (Venet.,
+1546, p. 15) is given a wind-rose, described as "Pixis uel Buxolus
+instrumentum et dux nauigantium," having twenty-six points inscribed with
+the names of the winds, there being six between north and east, and six
+between south and west, and only five in each of the other quadrants. In
+the middle is a smaller wind-rose exactly like the early Italian ones just
+mentioned.
+
+In the _Della Guerra di Rhodi_ of Jacobo Fontano (Venet., 1545, pages
+71-74) is a chapter _Dei Venti, e della Bvssola di nauicare di Giovanni
+Quintino_, giving a wind-rose, and a table of the names of the winds, the
+north being indicated by a pointer, at the cusp of which are seven stars,
+and the west by an image of the sun. The other cardinal points are marked
+with letters.
+
+Barlowe, in _The Navigators Supply_ (Lond., 1597), speaks thus:
+
+    "The merueilous and diuine Instrument, called the _Sayling Compasse_
+    (being one of the greatest wonders that this World hath) is a Circle
+    diuided commonly into 32. partes, tearmed by our Seamen Windes,
+    _Rumbes_, or Points of Compasse."
+
+It is a disputed point with whom the method of naming the winds originated.
+Some ascribe it to Charlemagne. Michiel Coignet (_Instruction novvelle ...
+touchant l'art de naviguer_, Anvers, 1581, p. 7) ascribes it to Andronicus
+Cyrrhestes. See Varro, _De Re Rustica_, iii., 5, 17, and Vitruvius, i., 6,
+4.
+
+Gilbert's complaint of the evil practice of setting the needles obliquely
+beneath the card, with the intention of allowing for the variation, is an
+echo of a similar complaint in Norman's _Newe Attractiue_. In chapter x. of
+this work Norman thus enumerates the different kinds of compasses:
+
+    "Of these common Sayling Compasses, I find heere (in _Europa_) five
+    sundry sortes or sets. The first is of _Levant_, made in _Scicile_,
+    _Genouea_, and _Venice_: And these are all (for the most parte) made
+    Meridionally, with the Wyers directlye sette under the South, and North
+    of the Compasse: And therefore, duely shewing the poynt _Respective_,
+    in all places, as the bare Needle. And by this Compasse are the Plats
+    made, for the most part of all the _Levants_ Seas.
+
+    "Secondly, there are made in _Danske_, in the Sound of _Denmarke_, and
+    in _Flanders_, that have the Wyers set at 3 quarters of a point to the
+    Eastwards of the North of the compasse, and also some at a whole point:
+    and by these Compasses they make both the Plats and Rutters for the
+    Sound.
+
+    "Thirdly, there hath beene made in this Countrey particulary, for Saint
+    _Nicholas_ and _Ruscia_, Compasses set at 3 seconds of a point, and the
+    first Plats of that Discoverie were made by this Compasse.
+
+    "Fourthly the Compasse made at _Sevill_, _Lisbone_, _Rochell_,
+    _Bourdeaux_, _Roan_, and heere in _England_, are moste commonly set at
+    halfe a point: And by this Compasse are the Plats of the East and West
+    _Indies_ made for their Pylotes, and also for our Coastes neere hereby,
+    as _France_, _Spayne_, _Portugall_, and _England_: and therefore best
+    of these Nations to bee used, because it is the most common sorte that
+    is generally used in these Coastes."
+
+Bessard (_op. citat._, pages 22 and 48) gives cuts of compasses showing the
+needle displaced one rumbe to the East.
+
+Gallucci, in his _Ratio fabricandi horaria mobilia et permanentia cum
+magnetica acu_ (Venet., 1596), describes the needle as inclined 10 degrees
+from the south toward the south-west.
+
+The frontispiece of the work of Pedro Nunez, _Instrumenta Artis Navigandi_,
+Basil., 1592, depicts a compass with the lily set one point to the east.
+
+Reibelt, _De Physicis et Pragmaticis Magnetis Mysteriis_ (Herbipolis,
+1731), depicts the compass with the needle set about 12 degrees to the East
+of North. See also Fournier, _Hydrographie_ (Paris 1667); De Lanis,
+_Magisterium Natvrae et Artis_ (Brixiae, 1684); Milliet Deschales, _Cursus
+seu Mundus {59} Mathematicus_ (Lugd., 1674). Both the latter works give
+pictures of the compass-cards as used in South Europe, and in North Europe,
+and of the various known shapes of needles.
+
+[227] PAGE 168, LINE 29. Page 168, line 33. _Directio igitur inualidior est
+prope polos._ Here as in many passages _direction_ means _the force which
+directs_. A similar usage prevails with the nouns _variation_ and
+_declination_, meaning frequently the force causing variation or
+declination respectively.
+
+PAGE 172, LINE 13. _perquirere._ The edition of 1633 reads _perquirero_, in
+error.
+
+[228] PAGE 172, LINE 29. Page 172, line 33. _Ad pyxidis nauticae verae &
+meridionalis formam ... fiat instrumentum._--An excellent form of portable
+meridian compass, provided with sights for taking astronomical
+observations, is described by Barlowe (_The Navigators Supply_, London,
+1597), and is depicted in an etched engraving. An identical engraving is
+repeated in Dudley's _Arcano del Mare_ (Firenze, 1646). Gilbert's new
+instrument was considerably larger.
+
+[229] PAGE 174, LINE 19. Page 174, line 21. _addendo vel detrahendo
+prostaphaeresin._--"Prosthaphaeresis, conflata dictione, ex additione et
+subtractione speciebus logistices, nomen habet ab officio, quia vt in
+semicirculo altero ad aequabilem motum adijcitur, ita in altero
+subtrahitur, vt adparens motus ex aequabili taxetur: atque hinc fit, quod
+quae Prosthaphaeresis dicitur Ptolemaeo, ea vulgo aequatio vocetur."
+(Stadius, _Tabulae Bergenses_, Colon. Agripp., 1560, p. 37.)
+
+[230] PAGE 174, LINE 28. Page 174, line 31. _Stellae Lucidae._--According
+to Dr. Marke Ridley (_Magneticall Animadversions_, London, 1617, p. 9),
+this chapter xii. of book iv., with the Table of Stars, was written by
+Edward Wright, the author of the Prefatory Epistle of _De Magnete_. Wright
+was Lecturer on Navigation to the East India Company, and author of sundry
+treatises on Navigation.
+
+[231] PAGE 187, LINE 14. Page 187, line 16. _hic qui versus boream
+constitit ... meridionalis est, non borealis, quem ante nos omnes
+existimabant esse borealem._--Earlier on, on pages 15 and 125, Gilbert had
+mentioned this point. His insistence caused Barlowe (_Magneticall
+Aduertisements_, 1616, p. 4) to speak of the south-pointing end of the
+needle as the "true North," and thereby drew on himself the animadversions
+of Marke Ridley.
+
+[232] PAGE 188, LINE 15. Page 188, line 16. _in recta sphaera._--See note
+to p. 134.
+
+[233] PAGE 190, LINE 14. Page 190, line 19. _declinans in
+Borealibus._--Dipping as it does in northern regions; that is, with the
+north-seeking or true-south pole downward.
+
+[234] PAGE 195, LINE 20. Page 195, line 24. _multa maiora pondera._--Many
+greater weights. All editions read _multa_, but the sense requires _multo_:
+"much greater weights."
+
+[235] PAGE 196, LINE 10. Page 196, line 12. _constans est._--This must not
+be read "is constant," for it is constant only in any given latitude.
+
+[236] PAGE 196, LINE 15. Page 196, line 18. _De proportione declinationis
+pro latitudinis ratione._--Gilbert here announces, and proceeds in the next
+seven pages to develop, the proposition that to each latitude there
+corresponds a constant dip to a particular number of degrees. If this were
+accurately so, then a traveller by merely measuring the dip would be able
+to ascertain, by calculation, by reference to tables, or by aid of some
+geometrical appliance, {60} the latitude of the place. In this hope Gilbert
+fought to perfect the dipping-needle; and he also worked out, on pages 199
+and 200, an empirical theory, and a diagram. This theory was still further
+developed by him, and given to Thomas Blundevile (see the Note to p. 240).
+Briggs of Gresham College, on Gilbert's suggestion, calculated a table of
+Dip and Latitude on this theory. It was found, however, that the observed
+facts deviated more or less widely from the theory. Kircher (_Magnes_,
+1643, p. 368) gives a comparative table of the computed and observed
+values. Further discovery showed the method to be impracticable, and
+Gilbert's hope remained unfulfilled.
+
+[237] PAGE 197, LINE 18. Page 197, line 21. _progressionis centri._--Note
+Gilbert's precision of phrase.
+
+[238] PAGE 200, LINE 12. Page 200, line 11. _subintellig[=u]tur._--This is
+printed _subintelligitur_, and is altered in ink in all copies of the folio
+edition. The editions of 1628 and 1633 read _subintelliguntur_. Similarly
+in line 14 the word _ducit_ has had a small _r_ added in ink, making it
+read _ducitur_, as also the other editions.
+
+[239] PAGE 203. This figure of the experiment with the simple dipping
+needle suspended in water in a goblet is due to Robert Norman. In his _Newe
+Attractiue_ (London, 1581, chap. vi.) he thus describes it:
+
+    "Then you shall take a deepe Glasse, Bowle, Cuppe, or other vessell,
+    and fill it with fayre water, setting it in some place where it may
+    rest quiet, and out of the winde. This done, cut the Corke
+    circumspectly, by little and little, untill the wyre with the Corke be
+    so fitted, that it may remain under the superficies of the water two or
+    three inches, both ends of the wyer lying levell with the superficies
+    of the water, without ascending or descending, like to the beame of a
+    payre of ballance beeing equalie poysed at both ends.
+
+    "Then take out of the same the wyer without mooving the Corke, and
+    touch it with the _Stone_, the one end with the South of the _Stone_,
+    and the other end with the North, and then set it againe in the water,
+    and you shall see it presentlie turne it selfe upon his owne Center,
+    shewing the aforesay'd _Declining_ propertie, without descending to the
+    bottome, as by reason it should, if there were any _Attraction_
+    downewards, the lower part of the water being neerer that point, then
+    the superficies thereof."
+
+[240] PAGE 212, LINE 7. Page 212, line 8. _ex altera parte._--The sense
+seems to require _et altera parte_, but all editions read _ex_.
+
+[241] PAGE 213, LINE 1. Page 213, line 2. The passage here quoted from
+Dominicus Maria Ferrariensis, otherwise known as the astronomer Novara,
+does not occur in any known writing of that famous man. It is, however,
+quoted as being by Novara in at least three other writings of the same
+epoch. See the _Tabulae secvndorum mobilium coelestium_ of Maginus (Venet.,
+1585, p. 29, line 19 to p. 30, line 11); the _Eratosthenes Batavvs_ of
+Willebrord Snell (Lugd. Batav., 1617, pp. 40-42); and the _Almagesti novi
+(Pars Posterior)_ of Riccioli (Bonon., 1651, p. 348). The original document
+appears to have perisht. See a notice by M. Curtze in Boncompagni's
+_Bullettino di Bibliografia_, T. iv., April, 1871.
+
+[242] PAGE 214, LINE 26. Page 214, line 31. _Philolaus Pythagoricus._
+
+    "Philolaues a le premier dit que la terre se meut en cercle; d'autres
+    disent que c'est Nicetas de Syracuse."
+
+    "Les uns pretendent que le terre est immobile; mais Philolaues le
+    pythagoricien dit qu'elle se meut circulairement autour du feu
+    (central) et suivant un cercle oblique, comme le soleil et la
+    lune."--(Chaignet, _Pythagore et la Philosophie pythagoricienne_,
+    Paris, 1873.)
+
+It appears that the first of these _dicta_ is taken from Diogenes Laert.,
+viii. 85; and the second from Plutarch, _Placit. Philos._, III. 7. The
+latter {61} passage may be compared with Aristotle, _De Coelo_, II. 13,
+who, referring to the followers of Pythagoras, says: "They say that the
+middle is fire, that the earth is a star, and that it is moved circularly
+about this centre; and that by this movement it produces day and night."
+
+[243] PAGE 214, LINE 34. Page 214, line 42. _Copernicus._--His work is _De
+revolutionibus orbium coelestium, libri vi._ (Basil., 1566).
+
+[244] PAGE 215, LINE 27. Page 215, line 24. _quae ... in caelo varijs
+distantijs collocata sunt._--This remark appears to be Gilbert's one
+contribution to the science of Astronomy; the stars having previously been
+regarded as fixed in the eighth sphere all at the same distance from the
+central earth, around which it revolved.
+
+[245] PAGE 220, LINE 6. Page 220, line 6. _quem nycthemeron vocamus._--The
+1628 and 1633 editions read _nyctemoron_.
+
+[246] PAGE 221, LINE 10. Page 221, line 11. _poli vere oppositi sint._--For
+_vere_, the 1628 and 1633 editions read _rectae_. All editions read _sint_,
+though _sunt_ seems to make better sense.
+
+[247] PAGE 223, LINE 7. Page 223, line 8. _ad telluris conformitatem._--The
+word _conformitas_ is unknown in classical Latin.
+
+[248] PAGE 223, LINE 16. Page 223, line 17. _Omitto quod Petrus Peregrinus
+constanter affirmat, terrellam super polos suos in meridiano suspensam,
+moveri circulariter integra revolutione 24 horis: Quod tamen nobis adhuc
+videre non contingit; de quo motu etiam dubitamus._
+
+This statement that a spherical loadstone pivotted freely with its axis
+parallel to the earth's axis will of itself revolve on its axis once a day
+under the control of the heavens, thus superseding clocks, is to be found
+at the end of chap. x. of Peregrinus's _Epistola De Magnete_ (Augsb.,
+1537).
+
+Gilbert, who doubted this experiment because of the stone's own weight is
+taken to task by Galileo, in the third of his Dialogues, for his qualified
+admission.
+
+"I will speak of one particular, to which I could have wished that
+_Gilbert_ had not lent an ear; I mean that of admitting, that in case a
+little Sphere of Loadstone might be exactly librated, it would revolve in
+it self; because there is no reason why it should do so" (p. 376 of
+Salusbury's _Mathematical Collections_, London, 1661). The Jesuit Fathers
+who followed Gilbert, but rejected his Copernican ideas, pounced upon this
+pseudo-experiment, as though by disproving it they had upset the Copernican
+theory.
+
+[249] PAGE 227, LINE 6. Page 227, line 7. This line is left out in the 1628
+edition. In the 1633 edition it was also left out by the printer, and
+subsequently printed in in the margin, being page 219 of that edition.
+
+[250] PAGE 234, LINE 35. Page 234, line 40. _vt poli telluris respectus a
+polis._--If it may be permitted to read _respectu_ for _respectus_ the
+sense is improved, and the passage may then be translated thus: "that just
+as it was needful ... that the poles of the Earth as to direction should be
+23 degrees and more from the poles of the Ecliptick; so now, &c."
+
+[251] PAGE 237, LINE 19. Page 237, line 22. _vt motus quidem obscuri
+saluarentur._--It has been conjectured that _quidem_ is here a misprint for
+_quidam_, but the adverb _quidem_ adds a satirical flavour to his argument
+against the folly of those who held the doctrine of the moving spheres. The
+verb _salvare_ does not occur in classical Latin.
+
+[252] PAGE 240, LINE 13. Page 240, line 17. _a Copernico (Astronomiae
+instauratore)._--Gilbert was the first in England to uphold the doctrines
+of {62} Copernicus as to the motion of the earth on its axis and its
+revolution around the sun. He considered that his magnetic observations
+brought new support to that theory, and his views are quoted with
+approbation by Kepler, _Epitome Astronomiae Copernicanae_ ... Authore
+Ioanne Keplero ... (Francofurti, 1635); and by Galileo, _Dialogus de
+Systemate Mundi_ (Augustae Treboc., 1635), an English translation of which
+appeared in Salusbury's _Mathematical Collections and Translations_
+(London, 1661, pp. 364 to 377).
+
+For this the book _De Magnete_ was considered by many as heretical. Many of
+the copies existing in Italy are found to be either mutilated or else
+branded with a cross. For example, the copy in the library of the Collegio
+Romano in Rome has book VI. torn out. Galileo states that the Book of
+Gilbert would possibly never have come into his hands "if a Peripatetick
+Philosopher, of great fame, as I believe to free his Library from its
+contagion, had not given it me." In England Barlowe, in his _Magneticall
+Aduertisements_ (1616), expressly repudiated Gilbert's Copernican notions,
+while praising his discoveries in magnetism. Marke Ridley, while upholding
+Gilbert's views, in his _Magneticall Animadversions_ (1617) did not
+consider him "skilfull in Copernicus." The Jesuit writers, Cabeus, Kircher,
+Fonseca, Grandamicus, Schott, Leotaudus, Millietus, and De Lanis, one and
+all, who followed Gilbert in their magnetic writings, repudiated the idea
+that the magnetism of the globe gave support to the heretical modern
+Astronomy.
+
+The works referred to are:
+
+Cabeus, _Philosophia Magnetica, in qua Magnetis natura penitus explicatur
+... auctore Nicolao Cabeo Ferrarensi Soc. Jesv._ (Ferrariae, 1629).
+
+Kircher, _Magnes, Siue de Arte Magnetica, Libri tres, Authore Athanasio
+Kirchero ... e Soc. Iesv._ (Romae, 1641).
+
+Grandamicus, _Nova Demonstratio immobilitatis terrae petita ex virtute
+magnetica_ (Flexiae, 1645). This work is most beautifully illustrated with
+copper-plate etchings of cupids making experiments with terrellas.
+
+Schott, Gaspar, _Thaumaturgus Physicus_ (Herbipolis, 1659).
+
+Leotaudus, _R. P. Vincentinii Leotavdi Delphinatis, Societ. Iesv.,
+Magnetologia; in qva exponitvr Nova de Magneticis Philosophia_, (Lvgdvni,
+1668).
+
+Millietus (Milliet Deschales), _Cursus seu Mundus Mathematicus_ (Lugd.,
+1674), _Tomus Primus, Tractatus de Magnete_.
+
+De Lanis, _Magisterium Natvrae et Artis. Opus Physico-Mathematicvm P.
+Francisci Tertii de Lanis, Soc. Jesv._ (Brixiae, 1684).
+
+[253] PAGE 240, LINE 24. Page 240, line 31. _hic finem & periodum
+imponimus._
+
+On February 13 [1601] Gilbert wrote to Barlowe (see _Magneticall
+Aduertisements_, p. 88):
+
+"I purpose to adioyne an appendix of six or eight sheets of paper to my
+booke after a while, I am in hand with it of some new inventions, and I
+would haue some of your experiments, in your name and inuention put into
+it, if you please, that you may be knowen for an augmenter of that arte."
+
+This he never did. Perhaps his appointment (in February, 1601) as chief
+physician in personal attendance on the Queen interfered with the project;
+or his death, of the plague, in 1603, intervened before his intention had
+been carried into effect. But it is probable that the substance of the
+proposed additions is to be found in the chapter, publisht in Gilbert's
+lifetime, in Blundevile's _Theoriques of the seuen Planets_ (London, 1602),
+thus described in the title-page of the work: "There is also hereto added,
+{63} The making, description, and vse, of two most ingenious and necessarie
+Instruments for Sea-men, to find out thereby the latitude of any Place vpon
+the Sea or Land, in the darkest night that is, without the helpe of Sunne,
+Moone, or Starre. First inuented by M. Doctor Gilbert, a most excellent
+Philosopher, and one of the ordinarie Physicians to her Maiestie: and now
+here plainely set downe in our mother tongue by Master Blundeuile."
+
+Of these two instruments the first consists of a mechanical device, with
+movable quadrants, to be cut out in cardboard, to be used in connection
+with the diagram of spiral lines which Gilbert had given as a folding plate
+between pages 200 and 201 of _De Magnete_. The intention was that the
+Sea-man having found by experiment with a dipping-needle the amount of the
+dip at any place, should by applying this diagram and its moving quadrants,
+ascertain the latitude, according to the theory expounded in book V., chap.
+VII.
+
+The second instrument is a simplified portable dipping-needle, having the
+degrees engraved on the inner face of a cylindrical brass ring.
+
+Blundevile adds a Table, calculated by Briggs, and "annexed to the former
+Treatise by _Edward Wright_, at the motion of the right Worshipful M.
+Doctor _Gilbert_." This gives the values of the dip for different
+latitudes, as calculated from Gilbert's empirical theory.
+
+The other work, _De Mundo nostro Sublunari Philosophia Nova_, which Gilbert
+left in manuscript at his death, does not contain any additional matter on
+the magnetical investigations. Though it contains several direct references
+to the _de Magnete_, and particularly to Book VI. on the rotation of the
+earth, it is doubtful whether it was written after or before the
+publication of _de Magnete_. On pages 137 to 144 of the posthumous edition
+(Amsterdam, 1651) Gilbert refers to Peregrinus's alleged perpetually
+revolving sphere, and denies its possibility. The greater part of the work
+is an anti-Aristotelian discussion on Air, Meteorology, Astronomy, the
+Winds, Tides, and Springs.
+
+[Illustration]
+
+       *       *       *       *       *
+
+
+{65} INDEX TO AUTHORITIES
+
+  Abano, Pietro di, 6.
+  Acosta, Josephus, 16.
+  Addison, Joseph, 35.
+  Aepinus, 44.
+  Aetius Amidenus, 6.
+  Affaytatus, 16, 39.
+  Agricola, Georgius, 25, 31, 36, 50.
+  Agrippa, H. Cornelius, 7.
+  Albategnius, 29.
+  Albertus Magnus, 6, 17, 38, 39, 40, 50.
+  Aldrovandi, Ulisse, 13, 36, 53.
+  Alexander Aphrodiseus, 3, 21.
+  Amatus Lusitanus, 6, 31.
+  Apponensis, Petrus, 6. _See_ Abano.
+  Aquinas, St. Thomas, 8, 45.
+  Ardoynis, Santes de, 6.
+  Aristotle, 4, 19, 25, 61.
+  Arnaldus de Villa nova, 6.
+  Augustani, 29.
+  Augustine, St., 4, 21, 43.
+  Aurifaber, 36.
+  Averroes, 29.
+  Avicenna, 6, 29, 30, 34.
+  Azuni, 8.
+
+  Bacon, Lord, 17, 42.
+  Barlow, Peter, 51.
+  Barlowe, William, 1, 2, 5, 9, 20, 28, 54, 56, 57, 58, 59, 62.
+  Beckmann, Johann, 19, 21, 32.
+  Bencora, or Ben Korrah (Thebitius), 30.
+  Benjamin, Park, 9, 11, 17.
+  Bernoulli, D., 48.
+  Bertelli, Timoteo, 11.
+  Bessard, Toussaincte de, 11, 58.
+  Bianco, Andrea, 57.
+  Blackmore, R. D., 24.
+  Blondo, Michaele Angelo, 1, 58.
+  Blondus, Flavius, 9.
+  Blundevile, Thomas, 8, 14, 60, 62, 63.
+  Bond, Henry, 55.
+  Borough, William, 2, 19.
+  Boyle, Robert, 43, 53.
+  Brasavolus, Antonius Musa, 6, 37.
+  Briggs, Henry, 60, 62.
+  Brough, R. B., 15.
+  Browne, Sir Thomas, 3, 37, 42, 51, 53.
+  Brunfels, Otho, 17, 30.
+  Buffum, W. A., 36.
+  Burton, Sir Richard F., 5.
+  Buttmann, 20, 32.
+  Buxtorf, 21.
+
+  Cabeus, Nicolas, 2, 42, 50, 62.
+  Cabot, Sebastian, 10, 16.
+  Caesar (or Cesare, Giulio), 53.
+  Calaber, Hannibal Rosetius, 6.
+  Calcagninus, Caelius, 8, 9.
+  Camden, William, 25.
+  Camera, Matteo, 8.
+  Cardan, Hieronymo, 23, 24, 26, 31, 36, 37, 41, 43, 49, 54.
+  Casaubon, 17.
+  Cats, Jacob, 53.
+  Cavallo, Tiberius, 44.
+  Chaignet, 60.
+  Charlemagne, 58.
+  Charles II., 23.
+  Charleton, Dr. W., 19.
+  Chladni, 26.
+  Coignet, Michiel, 58.
+  Collenuccio, Pandolfo, 9.
+  Conimbricenses, 11.
+  Cordus, Valerius, 20.
+  Cortes, Martin, 11, 24, 57.
+  Costa, Filippo, 16, 53.
+  Costa, Joseph. _See_ Acosta.
+  Costaeus, Joannes, of Lodi, 16, 45.
+  Creak, Captain, 51, 56.
+  Creech, T., 3.
+  Crescentius, 8.
+  Crollius, O., 29.
+  Curtius, 32.
+  Curtius, N., 29.
+  Curtze, M., 60.
+  Cusan (Cardinal de Cusa), 7, 45, 49.
+  Cyrrhestes, Andronicus, 58.
+
+  Davies, T. S., 20.
+  De la Hire, 54.
+  De Lanis, 58, 62.
+  Delaunay, 32.
+  Diogenes Laertius, 60.
+  Dioscorides, 30, 34, 35, 37, 38, 43.
+  Dominicus Maria Ferrariensis (Novara), 60.
+  Drake, Sir Francis, 19.
+  Dudley, Sir Robert, 19, 56, 59.
+  Du Puys (Puteanus), 38, 45.
+
+  {66}
+  Encelius, _or_ Entzelt, 7, 24, 26.
+  Erastus, Thomas, 7.
+  Euripides, 4.
+  Evax, 18, 50.
+  Evelyn, John, 23.
+
+  Fallopius, Gabriellus, 7, 29.
+  Fantis, Antonius de, 49.
+  Ficino, Marsiglio, 18.
+  Fincati, Admiral, 8.
+  Fletcher, L., 26.
+  Fonseca, 62.
+  Fontano, Jacopo, 58.
+  Forcellini, 2.
+  Fournier, G., 10, 20, 22, 55, 58.
+  Foxe, 52.
+  Fracastorio, Hieronymo, 12, 19, 29, 51.
+
+  Galen, 29, 30, 31, 35.
+  Galileo, 47, 62.
+  Gallucci, 58.
+  Gartias ab Horto, 13, 27, 39.
+  Gassendi, 54.
+  Gasser, Achilles P., 17, 57.
+  Geber, 29.
+  Gellibrand, Henry, 55.
+  Gemma, Cornelius, 45.
+  Gessner, 32.
+  Gilbert, Adrian, 20.
+  Gilbert, William, _de Mundo nostro Sublunari_, 47, 50, 63.
+  Gioia, _or_ Goia, 8, 56.
+  Glanvill, Joseph, 27.
+  Goebel, 36.
+  Goethe, 23.
+  Gonzalus Oviedus, 10.
+  Goppert, 35.
+  Goropius, Henricus Becanus, 10.
+  Gralath, D., 36.
+  Grandamicus, 62.
+  Grew, N., 23.
+  Grimaldi, 54.
+  Grotius, Hugo, 17.
+  Guericke, Otto von, 41, 50.
+
+  Haecker, P. W., 48.
+  Hakewill, G., 10.
+  Hakluyt, 13, 20.
+  Hali Abbas, 6, 17, 29.
+  Hamilton, James (Earl of Abercorn), 48.
+  Hariot, Thomas, 19.
+  Harris, Sir W. Snow, 21, 54.
+  Hartmann, P. J., 36.
+  Hellmann, G., 11.
+  Hermann, D., 36.
+  Hermolaus Barbarus, 7.
+  Hill, "Sir" John, 24, 38, 40.
+  Hood, T., 3.
+  Hues, Robert, 19.
+  Humboldt, 26, 31, 36, 41.
+  Hyginus, 36.
+
+  Isidore, St., 20, 21, 39.
+
+  Kendall, Abraham, 19.
+  Kepler, 62.
+  Kiel, Cornelius van (_or_ Kiliani), 52.
+  King, Edward, 26.
+  Kircher, Athanasius, 2, 21, 45, 55, 56, 57, 62.
+  Klaproth, 7, 8, 10, 20, 21, 22.
+  Kudrun, 15.
+
+  Langius, Joannes, 7.
+  Lanis, F. de, 58, 62.
+  Leonardus, Camillus, 7, 57.
+  Leotaudus, 62.
+  Levinus Lemnius, 38, 39, 41, 56.
+  Libri, 11.
+  Linna, Nicolas de, 14.
+  Lipenius, 13, 56.
+  Lister, Martin, 53.
+  Livio Sanuto, 10, 16.
+  Livy, 26.
+  Lonicer, Joannes, 30, 35, 38.
+  Loewy, 21.
+  Lucretius, 3, 44.
+
+  Maginus, 60.
+  Magnus, Sir Philip, 10.
+  Manardus, Joannes, 29.
+  Marbodeus, 6, 18, 21, 40, 41, 50.
+  Marcellus Empiricus, 6, 7.
+  Marco Polo, 10.
+  Martial, 36, 37.
+  Martin, Th. Henri, 20, 21, 32, 33.
+  Maskelyne, N. Story, 26.
+  Matthaeus Silvaticus, 7.
+  Matthiolus, P., 5, 30, 35.
+  Maurolycus, Franciscus, 11.
+  Medina, Pedro de, 54, 57.
+  Mercator, 11, 14.
+  Merula, Gaudentius, 18, 19.
+  Merula, P., 15.
+  Miers, H. A., 40.
+  Migne, 19.
+  Milliet Deschales, 58, 62.
+  Monardus, Nicolas, 29.
+  Montanus, Joannes Baptista, 6.
+  Morris, William, 15.
+  Moxon, Joseph, 51.
+  Muellenhoff, K., 36.
+
+  Nautonier, G., 55, 57.
+  Neckham, Alexander of, 10.
+  Newton, Sir Isaac, 41.
+  Nicander, 38.
+  Nicolaus Myrepsius (_or_ Praepositas), 28, 35.
+  {67}
+  Nonius Petrus (_or_ Nunez), 58.
+  Nordenskjold, 13.
+  Norman, Robert, 1, 11, 14, 28, 56, 58, 60.
+  Novara, Dominicus Maria, 60.
+
+  Offusius, Joannes Franciscus, 31.
+  Olaus Magnus, 12, 17.
+  Oribasius, 6.
+  Orpheus, 22, 44.
+  Ovid, 36.
+  Oviedo, Luis de, 28.
+  Oviedus, Gonzalus, 10.
+
+  Paley, F. A., 32.
+  Palm, G. A., 20.
+  Paracelsus (Bombast von Hohenheim), 7, 29.
+  Paulus Aeginae, 30.
+  Paulus Jovius, 9.
+  Paulus Venetus (Fra Paolo Sarpi), 17.
+  Pepys, Samuel, 23.
+  Peregrinus, Petrus, 1, 11, 23, 48, 57, 61.
+  Pettus, Sir John, 23, 41.
+  Philolaus, 60.
+  Photius, 21.
+  Pictorio, G., 18.
+  Plancius, 14.
+  Plat, Sir Hugh, 5, 40, 43.
+  Plato, 4, 44.
+  Plautus, 2.
+  Pliny (Caius Plinius Secundus), 5, 20, 21, 22, 24, 25, 26, 27, 35, 36,
+      37, 38, 39, 41, 49, 50.
+  Plot, Rob., 42.
+  Plutarch, 26, 28, 41, 60.
+  Polo, Marco, 10.
+  Porta, Joannes Baptista (Giambattista della Porta), 4, 9, 16, 23, 46, 48,
+      54, 56, 57.
+  Poynting, J. H., 47.
+  Praepositas (_or_ Nicolas Myrepsius), 28, 35.
+  Ptolemy, 12, 28.
+  Purchas, 55.
+  Puteanus, Gulielmus, 38, 45.
+
+  Quintino, Giovanni, 58.
+
+  Ramelli, Agostino, 53.
+  Rammelsberg, 26.
+  Reibelt, 58.
+  Rhazes, 28, 29, 30.
+  Riccioli, 60.
+  Ridley, Marke, 3, 31, 59, 62.
+  Robertson, Rev. Alexander, 17.
+  Ruecker, Arthur W., 15.
+  Ruellius, Joannes, 18, 30, 34, 37.
+  Rueus, Franciscus, 17.
+  Ruysch, Johan, 13.
+
+  Salusbury, T., 61, 62.
+  Santes de Ardoynis, 6.
+  Sanuto, Livio, 10, 16.
+  Sarpi, Fra Paolo, 16, 17.
+  Savery, Servington, 48, 54.
+  Scaliger, J. C., 26, 33, 34, 45, 46, 49.
+  Scheins, M., 32.
+  Schindler, A. Houtum, 33.
+  Schott, G., 62.
+  Schweigger, J. C., 32.
+  Sendel, Nathaniel, 36, 37.
+  Sennert, Daniel, 46.
+  Serapio, 6, 17, 30.
+  Severt, Jacques, 11.
+  Shakespeare, William, 22.
+  Siemens, 48.
+  Signorelli, 8.
+  Silvaticus, Matthaeus, 7.
+  Smith, Dr. William, 26.
+  Snell, Willebrord, 60.
+  Solinus, Julius, 4, 37, 40.
+  Stadius, 59.
+  Stephanus, 32.
+  Stevinus, Simon, 56.
+  Strabo, 26.
+  Swan, John, 56.
+  Swinden, J. H. van, 44.
+
+  Taisnier, Joannes, 11, 47.
+  Terzagus, 36, 49.
+  Thalen, 15.
+  Thales, 46.
+  Thebit Ben Korrah, 30, 50.
+  Themistius, 46.
+  Theophrastus, 32, 36, 38.
+  Thompson, Silvanus P., 48.
+  Thomson, R. D., 49.
+  Thorpe, T. E., 15.
+
+  Vallemont, Abbe de, 54.
+  Van Swinden, 44.
+  Varro, 58.
+  Venanson, Flaminius, 8.
+  Venner, Dr. T., 40.
+  Vergil, 2, 24.
+  Virgil, Polydore, 9.
+  Vitruvius, 58.
+
+  Waring, E. J., 29.
+  Watson, William, 38.
+  Wigand, Johann, 36.
+  Wilde, Henry, 15.
+  Willigen, van der, 48.
+  Wren, Sir Christopher, 23.
+  Wright, Edward, 19, 59, 62.
+
+[Illustration]
+
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