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WILLIAM GILBERT
OF COLCHESTER,
PHYSICIAN OF LONDON,
ON THE
LOADSTONE AND MAGNETIC BODIES,
AND ON
THE GREAT MAGNET THE EARTH.
% NEW P)iYSIOLOGY.
DEMONSTRATED WITH MANY ARGUMENTS AND EXPERIMENTS.
" Elecirica, quae attrahunt eadem ratione ut electricum."
A TRANSLATION BY
P. FLEURY MOTTELAY,
AUTHOR OF "the CHRONOLOGICAL HISTORY OF ELECTRICITY, MAGNETISM, ETC.'
NEW YORK : JOHN WILEY & SONS,
53 East Tenth Street. 1893.
Copyright, 1893,
BY
P. F. MOTTELAY.
ESOl
Robert Druhmond, Febbis Bbos.,
Electrotyper, Printers,
444 & 446 Pearl Street, 326 Pearl Street, New York. New York.
GVILIELMI GIL'
B E R T I C O L C E ST R E N-
SIS,^MEDICI LONDI- N E N S I S,
D E M A G R1E T E> M A G N E T P
<:lSCiVE CC>RPbRIBVS,ET DE I^AG.
no magnete teJlure j Phyfiologia noua^
Ip/mmis ^ jirgumentiSy &^p^^
rimentis dcraonflrata*
L O H D 1 N I
XCVDEBAT PetrvLShortiANNO MDC.
TRANSLATOR'S PREFACE.
I FIRST entered upon the translation of this, the earliest known published work treating of both magnetism and elec- tricity, in the beginning of 1889. It was then my intention to place it before the public during the year following, appreciat- ing as I did the demand for an English version which had been frequently reiterated by scientists generally in this country, in England, and upon the Continent of Europe. But the atten- tion I was compelled to give, both here and abroad, to the preparation of my " Chronological History of Electricity and Magnetism" has unavoidably delayed the publication of the present volume.
The translation of De Magnete has been a task of no or- dinary difficulty ; it has brought up problems innumerable, the solution gf which has involved much laborious research — as the result was meant to be a clear and competent presentation of the author in idiomatic English and not simply a substitution of English words for Latin. Nor would I have ventured to appear as the English interpreter of the great Gilbert, " father of the magnetic philosophy," but for the hearty encouragement and very material aid, in translating and otherwise, extended by many literary and scientific friends, amongst whom must be especially mentioned Mr. Joseph Fitzgerald, Mr. E. McMillan,
VI TRANSLATOR'S PREFACE.
Mr. Joseph Wetzler, Dr. Joseph V. Livingston, Hon. Park Ben- jamin, and Prof. Alfred M. Mayer. I am hkevvise indebted to Prof. Charles Sanders Peirce, to Mr. Latimer Clark, F.R.S., to Dr. Isaac H. Hall, and to Dr. Charlton T. Lewis for valuable suggestions as to the general treatment of the work, and, in the words of the celebrated English mathematician, Edward Wrip-ht, I doubt not that our united efforts "will find the heartiest approval among all intelligent men and children of magnetic science."
Not only does Gilbert frequently make use of what he terms " words new and unheard-of," besides attaching to many others a signification far different from that generally recog- nized at this day, but, what is worse, he retains to a great extent the terminology of the mediaeval scholastic philoso- phers. That terminology the translator must perforce retain ; no substitute is possible. Hence is found a multitude of un- couth words which, for the modern reader, require explanation. Of such it is unnecessary here to make any especial mention, since the copious general index to the present work will indicate very readily where they are to be found. It is known that in the philosophy of the schoolmen (as in that of Aristotle) form —forma — means that which added to matter — inateria — con- stitutes the true nature of the thing. Matter /^r se is indiffer- ent, indefinite; form gives it definiteness. The earth is informed With, verticity — that is its prime distinction. When any portion of the earth loses verticity it loses its forma — is deformate. To restore to it verticity, is to reformate it, or to informate it. Portions of the earth that are deformate are, as it were, effete, excrementitious, waste matter. Gilbert states (Book II, Chapters II and IV) that the natural magnetic force (movement) comes from the prime forma of the earth, or rather the primary native strength {vigor). Elsewhere he tells
TRANSLATOR'S PREFACE. Vll
US that the earth and the loadstone conform — conformant — magnetic movements (Book II, Chapter VI); and he speaks of substances conformated — confonnatmn — by the earth (Book III, Chapter IV), and of the globe of earth as of small account and deformate — deformatum (Book V, Chapter XII). He speaks besides of the formate soul — formata anima (Book V Chapter XII) ; of air or water being informated — informaren- tur — by magnetic forms or spheres (Book V, Chapter XI); of iron being transformated — transformatur (Book III, Chapter XII) ; and he adds that iron will attract more properly if it is a&ormed—aj^orjnattiin (Book II, Chapter IV) ; also that if will be better if the iron's "acquired verticity be, by some process, rather weakened or deformated '.' — deformata (Book III, Chapter XI).
England's great poet, John Dryden, tells us : " It is almost impossible to translate verbally and well at the same time ; for the Latin (a most severe and compendious language) often expresses that in one word which either the barbarity or the narrowness of modern tongues cannot supply in more. . . . But since every language is so full of its own proprieties that what is beautiful in one is often barbarous, nay, sometimes nonsense, in another, it would be unreasonable to limit a translator to the narrow compass of his author's words ; it is enough if he choose out some expression which does not vitiate the sense." While, in order to do this acceptably in the present instance, it has often been found necessary to adhere very closely (even literally) to the original lines, the "candid reader" will naturally observe that greater satisfaction has been vouchsafed where paraphrasing has been resorted to for the better comprehension, more particularly, of words of Gilbert's own coinage.
Following Dryden, I have translated with latitude, keeping
vm TRANSLATOR'S PREFACE.
in view the author's sense more particularly than his words^ and amplifying without altering the former. Nor have I, in so doing, attempted, any more than did Gilbert, to impart " into the work any graces of rhetoric, any verbal ornateness." Like him, I have simply endeavored to treat "knotty ques- tions about which little is known in such style and in such terms as are needed to make what is said clearly intelligible."
Such few passages of De Magnete as I have seen inde- pendently translated elsewhere will be found reproduced in their proper places, and wherever practicable I have followed the approved plan adopted in my " Chronological History," of quoting numerous authorities and inserting many extracts from the writings of different authors in support of the original matter. The extent to which this has been done is shown in the general index accompanying the present work.
I may add that I shall be under obligations to those calling attention to any errors, typographical or otherwise, that may be found herein, as well as to those whose helpful advice may make improvement possible in future editions.
P. Fleury Mottelay.
New York, March lo, 1892.
BIOGRAPHICAL MEMOIR.
William Gilbert — or Gilberd/ as he wrote it — was born in 1540 at Colchester, County Essex, England,'' of which borough his father, Jerome (Hieron) Gilberd, was recorder — "a coun- cillor of great esteem in his profession." ^ Very little that is reliable appears concerning his early years, but it is known that he passed through the Grammar School of his native place and immediately afterward (May 1558) entered St. John's College, Cambridge (whence, some say, he went to Oxford),' proceeding B.A. 1560, Fellow 1 560-1 561, M.A. 1564, mathematical examiner 1 565-1 566, M.D. 1569, and
' "Gilbert or Gilberd. . . . The latter is used both in his own epitaph and his father's; and in the records of the town of Colchester : and, therefore, seems the truest." {BiograpMa Britannica, London 1757, Vol. IV, page 2202.)
- See the Map of Colchester at page 4, Vol. I, Book I, of Philip Morant's " Hist, and Antiq. of Essex," London 1768; also, a full description of the town at pages 266-361, Vol. I, of Thos. Wright's " Hist, and Top. of the County of Essex," London 1836, as well as at pages 286-322, Vol. V, of "The Beauties of England and Wales," by E. W. Brayley and John Britton, London 1810.
2 Dr. Thomas Fuller, " Hist, of the Worthies of England," London 1840, page 515.
* Antony A. Wood, at pages 737-738, Vol. I, Athena Oxonienses, London 1813, says he was "educated at both the Universities but whether in Oxon. first or in Cambridge, I cannot justly tell "; and Thomas Wright (" Hist, and Top. of County of Essex," 1836, Vol. I, page 311) states that "he studied some time in the Universities of Oxford and Cambridge."
ix
lOGRAPHICAL MEMOIR.
being elected a Senior Fellow of St. John's during the last- named year.
Immediately upon leaving college he travelled on the Con- tinent, " where probably he had the degree of Doctor of Physic conferred upon him, for he doth not appear to have taken it either at Oxford or Cambridge," ' and where, as well as in England, he is said to have "practised as a physician with great success and applause." In 1573, he was elected a Fellow of the Royal College of Physicians, and filled therein many important offices, becoming, in turn. Censor (i 581-1582, 1584-1587, 1589-1590), Treasurer (i 587-1 591, 1 597-1 599), Con- siliarius (i 597-1 599), and President (1600). His skill had already attracted the attention of Queen Elizabeth, by whom he was appointed her physician-in-ordinary, and who showed him many marks of her favor, besides settling upon him an annual pension (said to be the only legacy left by her to any one) for the purpose of aiding him in the prosecution of his philosophical studies.
Gilbert's removal to court led to the dispersion of the members of a society or college which, it appears, frequently met at his residence at Colchester (see illustration). This house, anciently known as " Lanseles," " Timperley's," " Tym- pornell's " (Old Taxation),' was located " on St. Peter's Hill, between Upper Thames Street and Little Knight-Rider Street."
The early investigations of Gilbert were centred almost exclusively upon chemistry, he " attaining to great exactness therein," but this branch was ere long made to yield to the study of the phenomena of electricity and of magnetism, the
1 Philip Morant, loc. cit.. Vol. I, Book II, page 117. See, likewise, Ree's Cyclopzedia, 1819, Vol. XVI, article "Gilbert."
BIOGRAPHICAL MEMOIR. XI
latter of which had practically lain dormant for two thousand years — since the days of Thales and Theophrastus. How well he succeeded in generalizing and classifying these phenomena, after a patient and exhaustive line of experiments, is best evidenced by the great work which he published during 1600 under the title of De Magnete magneticisque corporibus, et de
gilbert's house at COLCHESTER.
magno magnete tellure ; Physiologia nova, plurimis et argu- mentis et experimentis demonstrata. This book, " full of valu- able facts and experiments ingeniously reasoned on " (J. F. W. Herschel), upon which Gilbert was actively engaged during eigh- teen years, is his best claim to recognition as the most distin-
Xll BIOGRAPHICAL MEMOIR.
guished man of science in England during the reign of the Virgin Queen.
" The year 1600," observes the EngHsh historian Henry Hallam/ "was the first in which England produced a remark- able work in Physical Science ; but this was one sufficient to raise a lasting reputation for its author. Gilbert, a physician, in his Latin treatise on the Magnet not only collected all the knowledge which others had possessed on the subject, but became at once the father of experimental philosophy in this island, and, by a singular felicity and acuteness of genius, the founder of theories v/hich have been revived after a lapse of ages, and are almost universally received into the creed of science. . . . Gilbert was one of the earliest Copernicans, at least as to the rotation of the earth, and, with his usual sagacity, inferred, before the invention of the telescope, that there are a multitude of fixed stars beyond the reach of our vision."
Gilbert's book created a powerful impression at the time, especially among the learned in other parts of Europe. Galileo expressed the highest admiration of the work and of its author, and, it is said, pronounced Gilbert "great to a degree that is enviable." It was, indeed, by the perusal of De Magnete that Galileo was induced to turn his mind to magnetism.'' In his own country, Gilbert was scarcely so highly appreciated ; even Bacon, though he praises Gilbert as a philosopher, speaks with little respect of his theory. After awhile his speculations came to be more esteemed, though perhaps not fully understood; but the great superiority of Gilbert over all who had previously treated of magnetism, and
1 " Introd. to the Litt. of Europe in the 15th, i6th, and 17th Centuries," London 1839, Vol. 11, page 463.
2 Dr. Munk, " Roll of the Roy. Col. of Phys.," 1878, page 78.
BIOGRAPHICAL MEMOIR. Xlll
"the extent to which he had anticipated by his conjectures much of our present knowledge " has only been perceived since the study of magnetism has assumed something like its present systematic and comprehensive character.^
While Dr. Whewell observes^ that " Gilbert's work contains all the fundamental facts of the science, so fully examined, indeed, that even at this day we have little to add to them," Dr. Thomas Thomson says^ that De Magnete " is one of the finest examples of inductive philosophy that has ever been pre- sented to the world. It is the more remarkable because it preceded the Novum Organiim of Bacon, in which the in- ductive method of philosophizing was first explained." How far Gilbert was ahead of his time is best proved by the works of those who wrote on magnetism during the first few decades after his death. They contributed in reality nothing to the extension of this branch of physical science. Poggendorff, from whose '* Geschichte der Physik " (page 286) this is ex- tracted, calls Gilbert " the Galileo of Magnetism." By Dr. Priestley he was named " the father of modern electricity."
In an article written not long since, Mr. Conrad W. Cooke, of London, notes the high opinion of Gilbert's work entertained, more particularly, by Nathaniel Carpenter, William Barlowe, Francis Bacon, Galileo, and Humboldt, and he adds : " There is abundant testimony extant that this * De Magnete' of Gilbert's produced a profound sensation, not only in this country but throughout the then civilized world, and it is a singularly curious fact that the brilliancy of a reputation so great and so original should have been allowed in subsequent generations to have been lost sight of in the
' Engl. Cycl., Section " Biography," Vol. Ill, page 102.
* " Hist, of the Inductive Sciences," 1859, Vol. II, page 217.
^ " History of the Royal Society," London 1812.
XIV BIOGRAPHICAL MEMOIR.
more blinding light of more recent knowledge and discoveries, and it is equally remarkable that a book so classical in its nature, so remarkable in its originality and prescience, and which was thought so much of during the periods which immediately followed its publication, should never have been translated into English, or indeed into any other language ; and this is rendered still more curious by the fact that such a translation was actually called for at the time, and the want of it was considered remarkable as far back as the year 1618 ; and here it will be interesting to quote from the preface to a scarce old book, ' Magneticall Advertisements^ written at that date by the Ven. William Barlowe,' Archdeacon of SaHsbury, and a very intimate friend of Dr. Gilbert. ' Many of our nation,' he says, 'both Gentlemen and others of excellent witts and louers of these knowledges, not able to read Doctor Gilbert's booke in Latin haue bin (euer since the first publish- ing thereof) exceeding desirous to haue it translated into English, but hitherto no man hath done it, neither (to my knowledge) as yet goeth about any such matter, whereof one principall cause is that there are very few that understande his booke, because they haue not Load-stones of diuers formes, but especially round ones ; ' and the author gives a further supposi- tion that * a second cause may be for that there are diuers wordes of art in the whole course of this booke proper to this subject and fitt to the explication of his figures and diagrammes
' Speaking of Wm. Barlowe, Anthony A. Wood says : " This was the person who had knowledge in the magnet 20 years before Dr. Will. Gilbert published his book of that subject, and therefore by those that knew him, he was accounted superior, or at least equal to that doctor for an industrious and happy searcher and finder out of many rare and magnetical secrets." {Athena Oxonienses, London 1S13, Vol. II, page 375.) Under heading of Gilbert, the "British Museum Catalogue of Printed Books," 1888, has it that "Mag. Adv." was compiled partly from De Magnete.
BIOGRAPHICAL MEMOIR. XV
which cannot be understood but by the helpe of the Mathe- maticks, and good trauelling in the Magneticall practice.' "
Dr. John Davy says^ Gilbert's '* work is worthy being studied, and I am surprised that an English edition (transla- tion) of it has never been published." He also alludes to the well-known reproach thrown upon Gilbert's philosophy by Francis Bacon, who, in his De Augmentis Scientiarum, remarks that " Gilbert has attempted to raise a general system upon the magnet, endeavoring to build a ship out of materials not sufficient to make the rowing-pins of a boat."
On the other hand, Digby and Barlowe place Gilbert upon a level with Harvey, Galileo, Gassendi, and Descartes," while the celebrated historian of the Council of Trent, Father Paul — Fra Paolo Sarpi,— who will not be thought an incompetent judge, names Gilbert, with Francis Vieta (the greatest French mathematician of the sixteenth century), as the only original writer among his contemporaries.^
It is deserving of notice that Gilbert was the first to use the terms ** electric force," " electric emanations," and " electric attraction." He it was, also, who gave the name of "pole" to the extremities of the magnetic needle pointing to the poles of the earth, calling south pole the extremity that pointed toward the north, and north pole the extremity point- ing toward the south. In the words of Sir David Brewster, Gilbert applies the term magnetic to all bodies which are acted upon by loadstones and magnets, in the same manner as they act upon each other, and he finds that all such bodies contain iron in some state or other. He considers the phenomena of
^ "Memoirs of the Life of Sir H. Davy," London 1836, Vol. \, page 309. ^ "Nouvelle Biog. G6n6rale," 1858, Tome VIII, page 494. ' Lettere di Fra Paolo, page 31; Hallam, " Introd. to Lit. . . . ", 1839, Vol. II, page 464.
XVI BIOGRAPHICAL MEMOIR.
electricity as having a considerable resemblance to those of magnetism, though he points out the differences by which the two classes of phenomena are marked.
To give here such an analysis as Gilbert's admirable work merits would be impracticable, but the short review of it made by Dr. John Robison^ deserves full reproduction as follows : " In the introduction, he recounts all the knowledge of the ancients on the subject, and their supine inattention to what was so entirely in their hands, and the impossibility of ever adding to the stock of useful knowledge, so long as men imagined themselves to be philosophising, while they were only repeating a few cant words and the unmeaning phrases of the Aristotelian school. It is curious to mark the almost perfect sameness of Dr. Gilbert's sentiments and language with those of Lord Bacon. They both charge, in a peremptory manner, all those who pretend to inform others, to give over their dialectic labours, which are nothing but ringing changes on a few trite truths, and many unfounded conjectures, and im- mediately to betake themselves to experiment. He has pursued this method on the subject of magnetism, with wonderful ardour, and with equal genius and success ; for Dr. Gilbert was possessed both of great ingenuity, and a mind fitted for general views of things. The work contains a pro- digious number and variety of observations and experiments, collected with sagacity from the writings of others, and insti- tuted by himself with considerable expense and labour. It would indeed be a miracle if all Dr. Gilbert's general infer- ences were just, or all his experiments accurate. It was un- trodden ground. But, on the whole, this performance con- tains more real information than any writing of the age in
* " System of Mechanical Philosophy," London 1822, page 209.
BIOGRAPHICAL MEMOIR. XVll
which he lived, and is scarcely exceeded by any that has ap- peared since. We may hold it with justice as the first-fruits of the Baconian or experimental philosophy.
"This work of Dr. Gilbert's relates chiefly to the load- stone, and what we call magnets ; that is, pieces of steel which have acquired properties similar to those of the loadstone. But he extends the term magnetism ^ and the epithet magnetic, to all bodies which are affected by loadstones and magnets, in a manner similar to that in which they affect each other. In the course of his investigations, indeed, he finds that these bodies are only such as contain iron in some state or other ; and in proving this Hmitation he mentions a great variety of phenomena which have a considerable resemblance to those which he allows to be magnetical, namely, those which he called electrical, because they were produced in the same way that amber is made to attract and repel light bodies. He marks, with care, the distinctions between these and the characteristic phenomena of magnets. He seems to have known, that all bodies may be made electrical, while fer- ruginous substances alone can be made magnetical. It is not saying too much of this work of Dr. Gilbert's to affirm, that it contains almost everything that we know about magnetism. His unwearied diligence in searching every writing on the subject, and in getting information from navigators, and his incessant occupation in experiments, have left very few facts unknown to him. We meet with many things in the writings of posterior enquirers, some of them of high reputation, and of the present day, which are published and received as notable
* Humboldt states that in Gilbert " we do not find either the abstract ex- pression electricitas, or the barbarous word magnetismus introduced in the eighteenth century." (" Cosmos," 1849, Vol. II, page 726, note.)
XVni BIOGRAPHICAL MEMOIR.
discoveries, but are contained in the rich collection of Dr. Gilbert. We by no means ascribe all this to mean plagiarism, although we know traders in experimental knowledge who are not free from this charge. We ascribe it to the general in- dolence of mankind, who do not take the trouble of consulting originals, where things are mixed with others which they do not want, or treated in a way, and with a painful minuteness, which are no longer in fashion. We earnestly recommend it to the perusal of the curious reader. He will (besides the phi- losophy) find more facts in it than in the two large folios of Scarella."
The manner in which " this great man arrived to discover so much of magnetical philosophy " and " all the knowledge he got on this subject," we are told by Sir Kenelm Digby,' "was by forming a little load-stone into the shape of the earth. By which means he compassed a wonderful designe, which was, to make the whole globe of the earth maniable ; for he found the properties of the whole earth, in that little body ; which he therefore called a terrella, or little earth f and which he could manage and try experiences upon, at his will. And in like manner, any man that hath an aim to advance much in natural sciences, must endeavour to draw the matter he en- quireth of, into some small modell, or into some kinde of manageable method ; which he may turn and wind as he pleaseth. And then let him be sure, if he hath a competent understanding, that he will not misse his mark."
Amongst the many other ingenious contrivances frequently alluded to in his book, Gilbert mentions the versorium, an iron needle moving freely upon a point, with which he was enabled
1 " Treatise of Bodies," 1645, Chap. XX, page 225.
2 See De Magnete, Book I, Chap. III.
BIOGRAPHICAL MEMOIR. XIX
to measure excited electricity. He is, besides, the inventor of " two most ingenious and necessarie Instruments for Sea men to find out thereby the latitude of any place upon sea or land, in the darkest night, that is without the helpe of Sunne, Moone or Starre." These instruments are described in Thomas Blun- derville's quarto work entitled " The Theoriques of the seuen Planets, shewing their diuerse motions* . . . printed at London 1602."
Of the monumental De Magnete, Prof. Robison states'' that he knew of but two British editions and that he had " seen five editions published in Germany and Holland before 1628." This would make seven editions in all, if the 1600 Amsterdam edition — which Kuhn alludes to — be included. Sir John Leslie, however, says' that " Gilbert's original work was republished at Ferrara in 1629, with a commentary by Cabaeus." Thus are eight distinct editions referred to. Yet, but
Two editions (1600, 1633) are named by: J. C. Brunet (Londini, Sedini) ; J. C. Poggendorff^ and " Inter- national Encycl."* (London, Stettin); " AUgemeine Ency." ^ and " Biographic Universelle " ^ (London, Sedan) ; Three editions (1600, 1628, 1633) are given by W. T. Lowndas,' S. A. Allibone," J. G. T. Graesse," S. P.
' " Bibliotheca Britannica," Edinburgh 1824, Vol. I, Authors, by R. Watt, pages 124 and 414.
2 " Edinb. Cyclop.," article Gilbert. See J. C. Poggendorff, " Geschichte der Physik," Leipsig 1879, page 279.
3 Fifth Dissert. " Encycl. Brit.", page 741.
^ "Manuel du Libraire," Paris 1861, Vol. II, page 1592.
* " Biog. -Liter. Handw.", Leipsig 1863, Vol. I, page 895.
^ Vol. VI, page 679, 1892 ed. ' Leipzig 1858, Sec. I, page 229.
8 Bruxelles 1843-1847, Vol. VII, page 253.
» "The Bibliog. Manual," 1859, Part IV, page 890.
1" "Critical Diet, of Engl. Lit.", 1859, Vol. I, page 668.
" "Tresor de Livres Rares et Precieux," 1862.
XX BIOGRAPHICAL MEMOIR.
Thompson' (Londini, Sedini) ; Dr. J. Lamont* (Londini, Stettin); British Museum Catalogue of Printed Books, London 1888 (Londini, Sedani); Four editions are alluded to at page 201 of the (1880) Catalogue of the Ronalds Library, edited by Alfred J. Frost, viz., Londini 1600, Amsterdam 1600, Sedini 1628, 1633 ; and Five editions appear in Mr. C. W. Cooke's article' as fol- lows : London 1600, Stettin 1628, 1633, Franckfort 1629, 1638, the same being specified in the " Ninth Britannica,"* with the difference that Sedan takes the place of Stettin. The other editions cannot be traced through any of the numerous catalogues of public and private libraries, or in the records of prominent sales at auction, which have been consulted. The above has brought about the question as to the true significance of Sedini, with the result following :
Sedan, on the Meuse, in France, is given the Latin name Sidanum by Mr. Bescherelle,* also Sedanum in the " Diet. G6og. Port.", 1809, page 617, as well as by Em. Bowen,^ Henry Cotton,^ and M. Des- champs.* Stettin, on the Oder, in Prussia, is called in Latin Stetinum ("Diet. G^og. Port", 1809, page 652; Em. Bowen, loc. cit. Vol. I, page 701). See
* " Gilbert of Colchester, an Eliz. Magn.", 1891, pages 43-44.
2 " Handb. des Magnetismus," Leipzig 1867, page 434.
3 London "Engineering" for the month of December, 1889.
* Volume X, page 592.
5 "Grand Diet, de G6og. Univ.", 1857, Tome IV, page 560. fi "Compl. Syst. of Geog.", 1747, Vol. I, page 401. ' " Typog. Gazetteer," 1825, page 146. 8 "Diet, de Geog.", 1870, page 1158.
BIOGRAPHICAL MEMOIR. XXI
Sedmum — likewise Sideni, Sidini, Sudeni, in " Lexi- con Geog.", 1657, page 361; " Diet. Geog.", Nice 1 79 1, page 308, "Diet. Geog. Univ.", 1832, pages 453-454 ; as well as by Larousse/ Cotton,* Des- champs/ and W. Smith.* Gilbert alludes to the Sudini of Prussia, Book 2, Chap. 2. Sedini, Sedinu, Seduni, Sedunum (French Sion, Ger- man Sitten), were names attaching to place and people along the banks of the Rhone in Switzer- land (Phil. Brietio, " Parallela Geographiae," 1648, Vol. I, page 347 ; Geo. Long, " Atlas of Class. Geog.'^ 1874, Map VII ; A. G. Findlay, "Classical Atlas,'' 1853, Map XIII ; Alex. Maclean, "Diet, of Am. Geog.", 1773 ; Deschamps, loc.cit. page 1161).
As the French would say, il y en a un peu pour tous les goUts, but since Wolfgang Lochman(n), the publisher of the editions imprinted Sedini 1628 and 1633, was a resident of Stettin (J. C. Poggendorff, " Biogr.-Liter. Handw.," 1863, Vol. I, page 1484), the natural inference to be drawn is that the imprint Sedini stands for Stettin, and not for Sedan as many have it.
In the present volume will be found photo-lithographic reproductions of three of the above-named title-pages. That of the 1600 Londini is taken from the copy of Mr. Charles L. Clarke, whereto allusion is made hereafter, while the 1628 Sedini is reproduced from the copy in the library of the English Institute of Electrical Engineers, and the 1633 Sedini from the copy belonging to Dr. Park Benja- min of New York City. The 1628 is the most elaborate
' "Grand Diet. Univ.", 1875, Tome XIV, pages 477, 1099.
' H. Cotton, loc. cit. page 152.
^ Deschamps, loc. cit. pages 1161, 1175.
* "Diet, of Gr. and Rom. Geog.", 1857, Vol. II, pages 995, 1042.
XXU BIOGRAPHICAL MEMOIR.
of all known Gilbert title-pages. As described by Prof. Sir Wm. Thomson (Lord Kelvin), it is " in the form of a monu- ment, ornamented with commemorative illustrations of Gil- bert's theory and experiments, and a fantastic indication of the earliest European mariner's compass, a floated loadstone, but floating in a bowl on the sea and left behind by the ship sailing away from it ! In the upper left-hand corner is to be seen Gilbert's terrella and orbis virtutis^ The terrella is a lit- tle globe of loadstone, which he made to illustrate his idea that the earth is a great globular magnet. . . . The orbis virtutis is simply Gilbert's expression for what Faraday called the field of force, that is to say, the space round a magnet, in which magnetic force is sensibly exerted on another magnet, as, for instance, a small needle, properly placed for the test. Gil- bert's word virtue expresses even more clearly than Faraday's word force the idea urged so finely by Faraday, and proved so validly by his magneto-optic experiment, that there is a real physical action of a magnet through all the space round it tho' no other magnet be there to experience force and show its effects." The meaning of the Httle bars bordering the terrella is explained in Gilbert's book (Lib. I, cap. iii, and Lib. V, cap. ii), where he alludes to the application of bits of fine iron wire as long as a barley-corn, etc., etc.
After the death of Queen Elizabeth, March 24, 1603, Gil- bert was continued in his position as royal physician by King James I., but he survived his benefactress only a few months; he died, some say at Colchester, others at London, on the 30th November of the same year. He was buried in the chancel of the Church of the Holy Trinity in Colchester, where a monu-
> See cuts of Orbis Virtutis in De Magnete, Book II, Chapters VI and XXVII, also Book V, Chap, II.
BIOGRAPHICAL MEMOIR. XXlll
ment ' was erected to him by his brothers, who placed upon it a Latin inscription ^ which appears at page 79 of Doctor Munk's " Roll of the Royal College of Physicians," London 1878. Dr. B. W. Richardson has translated the inscription as follows :
Ambrose and William Gilberd have placed this tomb In memory of brotherly piety. To William Gilberd, Senior, Gentleman, and doctor of medicine. This, the eldest son of Jerome Gilberd, Gentleman, was born in the town of Colchester, studied the art of medicine at Cambridge, practiced the same for more than thirty years ai London, with singular credit and success. Hence called to Court, he was received with highest favor by Queen Elizabeth, to whom, and to her successor James, he served as chief physician. He composed a book celebrated among for- eigners concerning the magnet for nautical science. He died in the year of the Human Redemption 1603, the last day of November, in the 63d year of his age.
The inscription is thus rendered by Thos. Wright, at pages 310-31 1, Vol. I, of his (London 1836) '■'■ Hist, and Topog. of the County of Essex:"
Ambrose and William Gilberd erected this monument to William Gilberd, senior, esq., and doctor of physic, in memory of his fraternal affection. He was the eldest son of Jerom Gilberd, Esq., born in the town of Colchester, studied physic at Cambridge, and practised at Lon- don more than thirty years with the greatest applause, and equal suc- cess. And being sent for to Court, he was received into the highest favor by Queen Elizabeth, to whom as also to her successor, James, he was principal physician. He wrote a book concerning the magnet, much celebrated by those engaged in nautical affairs. He died in the year of Human Redemption 1603 on the last day of November, in the 63d year of his age.
' An engraving of this monument is given in Philip Morant's "History of Colchester," and it is described (" Diet, of Nat. Biog.", London 1890, Vol. XXI, page 338) as being "a panel surrounded by a frame of Jacobean pattern, surmounted by pinnacles bearing globes and 14 shields of armorial achieve- ments."
' "The epitaph thereon is very unelegant and hardly latin. . . ." {Biog. Brit., London 1757, Vol. IV, page 2203.)
XXIV BIOGRAPHICAL MEMOIR.
Gilbert was never married. He bequeathed to the College of Physicians " all the books in his library, his globes, instru- ments and cabinets of minerals." These were, unfortunately, consumed in the great London fire of 1666. To the University of Oxford he left a portrait which he is said to have ordered made of himself for the purpose and which was " placed in the Gallery over the Schools."' In this portrait, which is be- lieved to have been destroyed," he appears standing in his doctor's robes " holding in his hand a globe inscribed terrella, whilst over his head is the inscription ' 1591, aetatis 48,' and, a little below his left shoulder, the words ' Magneticarum virtu- tum, primus indagator Gilbertus.' " '
The reader is shown in the frontispiece a copy of the only portrait of Gilbert known at this day. It was taken from Vol. II, page 33, of S. and E. Harding's " Biographical Mirrour," and is said to have been engraved by Clamp " from an original picture in the Bodleian Library, Oxford." " As will be seen, it lacks the inscriptions before spoken of and represents Gilbert holding his hand upon an ordinary globe. It was the central portion of this picture which was utilized by Mr. Arthur Ack- land Hunt for his well-known historical painting, representing Gilbert making an experimental demonstration in electricity before Queen Elizabeth.
Speaking of Gilbert, Dr. Fuller writes : " One saith of him that he was Stoicall, but not Cynicall, which I understand
1 " The picture of this famous doctor, drawn to the life, is hanging in the school-gallery at Oyian^' (AthencB Oxonienses, by Anthony a Wood [1st edi- tion, 1691-2], London 1813, Vol, I, page 738).
^ Wood says "decayed and removed." at page 96, Vol. II, of the 1796 " Hist, and Antiq. of the Univ. of Oxford."
3 Ninth "Encycl. Brit.", article Gilbert.
4 Dr. Munk's " Roll of the Roy. Col. of Physicians," 1878, page 79; " Diet. of Nat. Biog.", London 1890, Vol. XXI, page 338.
BIOGRAPHICAL MEMOIR. XXV
Reserved, but not Morose, never married, purposely to be more beneficial to his brethren. Such his Loyalty to the Queen that, as if unwilling to survive, he dyed in the same year with her, 1603. His Stature was Tall, Complexion Chearful, an Happi- ness not ordinary in so hard a student anjd retired a person."
Besides Gilbert's folio De Magnete, there appeared at Am- sterdam, in 165 1, a quarto volume of 316 pages entitled De Mundo Nostro Sublunari Philosophia Nova, which was edited, some say by his brother William Gilbert Junior — ^according to others, by the eminent English scholar and critic John Gruter — from two MSS. found in the library of Sir Wm. Boswell, Knight. According to Dr. John Davy, " this work of Gil- bert's, which is so little known, is a very remarkable one, both in style and matter ; and there is a vigour and energy of ex- pression belonging to it very suitable to its originality. Pos- sessed of a more minute and practical knowledge of natural philosophy than Bacon, his opposition to the philosophy of the schools was more searching and particular, and at the same time probably little less efficient." ^ In the opinion of Prof. John Robison, De Mundo consists of an attempt to establish a new system of natural philosophy upon the ruins of the Aris- totelian doctrine. We give an extract from the work, in a footnote to the present translation of Gilbert's De Magnete, Book VI, Chap. VII, and are also enabled to give a reproduc- tion of the 165 1 title-page made through the courtesy of Dr. Park Benjamin.
The only known writing of Gilbert in English is in the form of a letter dated 14th Februrary (? 1602) which appears at the end of William Barlowe's " Magneticall Advertisements or
1 "Memoirs of the Life of Sir Humphry Davy," London 1836, Vol. I, page 311.
xxvi BIOGRAPHICAL MEMOIR.
divers observations concerning the loadstone," quarto, Lon- don 1616, and reads as follows :
To the Worshipfull my good friend, Mr. William Barlowe at Easton by Winchester. Recommendations with many thanks for your paines and courtesies, for your diligence and enquiring, and finding dinars good secrets, I pray proceede with double capping your load-stone you speake of, I shall bee glad to see you, as you write, as any man, I will haue any leisure, if it were a moneth, to conferre with you, you have shewed mee more — and brought more light than any man hath done. Sir, I will commend you to my L. of Effingham, there is heere a wise learned man, a Secretary of Venice, he came sent by that State, and was honourably received by her Majesty, he brought me a lattin letter from a Gentle-man of Venice that is very v/ell learned, whose name is Johannes Franciscus Sagredus, he is a great Magneticall man, and writeth that hee hath conferred with diners learned men of Venice and with the Readers of Padua, and re- porteth wonderfuU liking of my booke, you shall haue a coppy of the letter : Sir, I propose 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 in- uentions, 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 art. So for this time in haste I take my leaue the xiiyth of February.
Your very louing friend,
W. Gilbert.
His intention to print the short appendix was never car- ried into effect.
Professor Silvanus P. Thompson states (" Gilbert of Col- chester . . . ", London 1891, page 40) that "with the exception of a single doubtful inscription, ' ex dono auctoris,' in a single copy of De Magnete, not a line of his [Gilbert's] handwrit- ing is known to exist, unless his hand wrote the signature ' Ye President and Societie ' at the end of a Petition, preserved amongst the manuscripts in the British Museum, addressed by the Royal College of Physicians in 1596 to the Lords of the Privy Council, complaining of the exactions of the Lord Mayor and Aldermen of London. It is pretty certain that
BIOGRAPHICAL MEMOIR. XXVll
the MS. copy of De Mundo in the British Museum is not in the author's handwriting ; for in the Elzevir Print there is a note stating that the author's original manuscript was partly in English." * It is unfortunate that Prof. Thompson's atten- tion should not at the time have been called to the fact that Mr. Bernard Quaritch's Rough List No. 99, for September 1889, offered at page 80 — No. 747 — a 1600 De Magnete ** Pres- entation copy from the author, with inscription on title Dedit Guil. Gilbertiis Jo. Sherwood propriis inanibus." This copy, which formerly belonged to Mr. Wm. Constable, F.R.S. and F.A.S., is now the property of Mr. Chas. L. Clarke, C.E., New York City, through whose courtesy the reproduction of the title bearing the inscription appears at page iii. A comparison of the writing in both inscriptions would prove interesting.
" Mahomet's Tombe at Mecha is said strangely to hang up, attracted by some invisible Load-stone, but the memory of the Doctor will never fall to the ground, which his incompar- able Book De Magnete will support to Eternity." ^
In his epistle ' to Dr. Walter Charleton (physician in ordi- nary to King Charles I.), the celebrated EngHsh poet, John Dryden, predicts that
" Gilbert shall live till loadstones cease to draw, Or British fleets the boundless ocean awe."
' " A copy in MS, among the Royal collection in the British Museum. . , . It consists of five books and is written on paper." (Casley's Catalogue, page 212.) The work is alluded to at page 283 "Les Elzevier," Alph. Willems, Bruxelles 1880, also at page 203 of Ann. de Impr. Elsevirienne, Chas. Pieters, Gand 1851.
^ Dr. Thomas Fuller, " The History of the Worthies of England," London 1840, page 515. See references to Mahomet's Shrine: in Gilbert's De Magnete, 1600, Book I, Chap. I ; in Porta 's "Natural Magick," 1658, Book VII, Chap. XXVII; in Sir Thomas Brown's Pseudoloxia, Epidemica, 1658, Book II, pages 78-79; in Cabaeus, Philosophia Magneiica, 1629, Lib. IV, Chap. XVIII, page 335.
* Epistle the Third, at page 15, Vol. XI, of the Works of John Dryden, London 1803.
CONTENTS.
PAGE
Translator's Preface • •, v
Biographical Memoir ix
Address by Edward Wright xxxviii
Author's Preface , . . xlvii
Explanation of some Terms used in this Work liii
BOOK I.
Chapter I. Writings of ancient and modern authors concerning the load- stone : various opinions and delusions i •
IL The loadstone: what it is: its discovery 15
III. The loadstone possesses parts differing in their natural powers,
and has poles conspicuous for their properties 22
IV. Which pole is the north: how the north pole is distinguished
from the south pole 26
V. One loadstone appears to attract another in the natural posi- tion; but in the opposite position repels it and brings it to
rights 28
VI. The loadstone attracts iron ore as well as the smelted metal. . . 31
VII. What iron is; what its matter; its use 33
VIII. In what countries and regions iron is produced 43
IX. Iron ore attracts iron ore 46
X. Iron ore has and acquires poles, and arranges itself with refer- ence to the earth's poles , ,, 47
XL Wrought-iron, not magnetized by the loadstone, attracts iron. 48 XII. A long piece of iron, even not magnetized, assumes a north
and south direction 50
XIII. Smelted iron has in itself fixed north and south parts, magnetic
activity, verticity, and fixed vertices or poles 51
XIV. Of other properties of the loadstone and of its medicinal virtue 52 XV. The medicinal power of the iron 55
XVI. That loadstone and iron ore are the same, and that iron is ob- tained from both, like other metals from their ores; and that all magnetic properties exist, though weaker, both in
smelted iron and in iron ore 59
xxxi
XXXll CONTENTS.
PAGE
XVII. That the terrestrial globe is magnetic and is a loadstone; and, just as in our hands the loadstone possesses all the prim- ary powers (forces) of the earth, so the earth by reason of the same potencies lies ever in the same direction in the universe 64
BOOK II.
Chapter I. Of magnetic movements 72
II. Of magnetic coition, and, first, of the attraction exerted by amber, or, more properly, the attachment of bodies to amber 74
III. Opinions of others concerning magnetic coition, which they call
attraction 97
IV. Of the strength of a loadstone and its form: the cause of coition 105 V. In what manner the energy inheres in the loadstone 115
VI. How magnetized iron and smaller loadstones conform to the
terrella, and to the earth itself, and are governed thereby. 121 VII. Of the potency of the magnetic force, and of its spherical ex- tension 123
VIII. Of the geography of the earth and the terrella 124
IX. Of the equinoctial circle of earth and terrella 126
X. The earth's magnetic meridians 126
XI. Parallels 127
XII. The magnetic horizon 128
XIII. Of the magnetic axis and poles 125
XIV. Why the coition is stronger at the poles than in the parts be-
tween equator and pole; and the relative power of coition
in different parts of the earth and the terrella 129'
XV. The magnetic force imparted to iron is more apparent in an iron rod, than in an iron sphere, or cube, or iron of any
other shape 131
XVI. That motion is produced by the magnetic force through solid
bodies interposed: of the interposition of a plate of iron. 132 XVII. Of the iron helmet (cap) of the loadstone, wherewith it is armed at the pole to increase its energy; efficiency of the
same 137
XVIII. An armed loadstone does not endow with greater force mag- netized iron than does an unarmed one , 138
XIX. That unition is stronger with an armed loadstone: heavier weights are thus lifted: the coition is not stronger, but
commonly weaker 139
XX. That an armed magnet lifts another, and that one a third: this
holds good though there be less energy in the first 139
XXI. That when paper or other medium is interposed, an armed load- stone does not lift more than one unarmed 140
CONTENTS. XXXlll
PAGE
XXII. That an armed loadstone does not attract more than an un- armed one; and that the armed stone is more strongly united to the iron, is shown by means of an armed load- stone and a cylinder of polished iron 140
XXIII. The magnetic force makes motion toward union, and when
united connects firmly 142
XXIV. That iron within the field of a loadstone hangs suspended in air,
if on account of an obstacle it cannot come near 143
XXV. Intensifying the loadstone's forces 145
XXVI. Why the love of iron and loadstone appears greater than that of loadstone and loadstone, or iron and iron when nigh a
loadstone and within its field 148
XXVII. That the centre of the magnetic forces in the earth is the centre
of the earth; and in the terrella the terrella's centre 150
XXVIII. That a loadstone does not attract to a fixed point or pole only, but to every part of a terrella, except the equinoctial
circle 151
XXIX. Of difference of forces dependent on quantity or mass 152
XXX. The shape and the mass of an iron object are important in
magnetic coitions 152
XXXI. Of oblong and round stones 154
XXXII. Some problems and magnetic experiments on the coition, and
repulsion, and regular movement of magnetic bodies .... 155
XXXIII. Of the difference in the ratio of strength and movement of
coition within the sphere of influence 161
XXXIV. Why a loadstone is of different power in its poles as well in the
north as in the south regions 164
XXXV. Of a perpetual-motion engine actuated by the attraction of a
loadstone, mentioned by authors 166
XXXVI. How a strong loadstone may be recognized 167
XXXVII. Uses of the loadstone as it affects iron 169
XXXVIII. Of the attractions of other bodies 170
XXXIX. Of mutually repellent bodies 175
BOOK III.
Chapter I. Of direction 177
II. Directive (or versorial) force, which we call verticity: what it is; how it resides in the loadstone; and how it is acquired
when not naturally produced 183
III. How iron acquires verticity from the loadstone, and how this
verticity is lost or altered 189
IV. Why magnetized iron takes opposite verticity: and why iron touched by the true north side of the stone moves to the earth's north, and when touched by the true south side to
XXXI V CONTENTS.
PAGE
the earth's south: iron rubbed with the north point of the stone does not turn to the south, nor vice versa, as all
writers on the loadstone have erroneously thought 192
V. Of magnetizing stones of different shapes 197
VI. What seems to be a contrary movement of magnetic bodies is
the regular tendence to union 198
VI I. A determinate verticity and a directive power make magnetic bodies accord, and not an attractional or a repulsive force,
nor strong coition alone, or unition 200
VIII. Of disagreements between pieces of iron on the same pole of a loadstone; how they may come together and be con- joined 201
IX. Directional figures showing the varieties of rotation 204
X. Of the mutation of verticity and magnetic properties, or of the
alteration of the force awakened by the loadstone 208
XI. Of friction of iron with the mid parts of a loadstone between
the poles, and at the equinoctial circle of a terrella 210
XII. How verticity exists in all smelted iron not excited by the load- stone 211
XIII. Why no other bodies save the magnetic are imbued with ver-
ticity by friction with a loadstone; and why no body not magnetic can impart and awaken that force 217
XIV. The position of a loadstone, now above, anon beneath, a mag-
netic body suspended in equilibrium, alters neither the
force nor the verticity of the magnetic body 219
XV. The poles, equator, centre, are permanent and stable in the un- broken loadstone, when it is reduced in size and a part
taken away, they vary and occupy other positions 220
XVI. If the south part of a loadstone have a part broken off, some- what of power is taken away from the north part also.. . . 222 XVII. Of the use of rotary needles and their advantages; how the di- rective iron rotary needles of sun-dials and the needles of the mariner's compass are to be rubbed with loadstone in order to acquire stronger verticity 223
BOOK IV.
Chapter I. Of variation 229
II. That variation is due to inequality among the earth's eleva- tions 235
III. Variation is constant at a given place 240
IV. The arc of variation does not differ according to distance be- tween places 242
V. An island in ocean does not alter in variation; neither do
mines of loadstone 243
CONTENTS. XXXV
PAGE
VI. That variation and direction are due to the controlling force of the earth and the rotatory magnetic nature, not by an at- traction or a coition or by other occult cause 244
VII. Why the variation due to this lateral cause is not greater than hitherto it has been observed to be, seldom appearing to amount to two points of the compass, except near the
poles , 246
VIII. Of the construction of the common mariner's compass, and of
the different compasses of various nations 248
IX. Whether terrestrial longitude can be found from variation .... 251 X. Why in various places near the pole the variations are much
ampler than in lower latitudes 254
XI. Cardan's error in seeking to determine the distance of the earth's centre from the centre of the world by means of the
loadstone (in his De Proportionibus,Y) 255
XII. Of finding the amount of the variation; what the quantity is of the arc of the horizon from its arctic or antarctic intersec- tion by a meridian to the point toward which the needle turns 256
XIII. Observations made by seamen commonly vary and are untrust-
worthy, partly though mistakes and want of knowledge and the imperfectness of the instruments, and partly be- cause the sea is seldom so calm but shadows or lights may rest on the instruments 265
XIV. Of the variation under the equinoctial line and nearby 267
XV. The variation of the magnetized needle in the great sea,
Ethiopic and American, below the equator 267
XVI. Of the variation in Nova Zembla 269
XVII. Variation in the South Sea 270
XVIII. Of the variation in the Mediterranean Sea 270
XIX. The variation in the interior of the great continents 271
XX. The variation in the Eastern Ocean 272
XXI. How the deviation of the needle is greater or less according to
the distance oif places 273
BOOK V.
Chapter I. Of the dip of the magnetic needle - . , 275
II. Diagram showing dip of the magnetic needle in different posi- tions of a sphere and horizons of the earth in which
there is a variation of dip 282
III. An instrument for showing by the action of a loadstone the degree of dip below the horizon in any latitude. Descrip-
tioM of the instrument; its uses 285
IV. Of a suitable length of needle on the terrella for showing the
dip 288
XXXVl CONTENTS.
TAGS
V, That dip is not caused by the attraction of a loadstone but by
its power of giving direction and rotation 289
VI. Of the ratio of the dip to latitude and the causes thereof 292
VII. Explanation of the diagram of the rotation of magnetized iron. 295 VIII. Diagram of the rotation of magnetized iron showing the mag- netic dip in all latitudes, and showing the latitude from
the rotation and dip 297
IX, Demonstration of direction, or of variation from the true di- rection, together with dip, simply by the movement in
water, due to the power of controlling and rotating 301
X. Of variation of dip 303
XI. Of the formal magnetic act spherically effused 304
XII. The magnetic force is animate, or imitates a soul; in many re- spects it surpasses the human soul while that is united to an organic body 308
BOOK VI.
Chapter I. Of the globe of earth as a great loadstone. 313
II. The magnetic axis of the earth remains invariable 315
III. Of the daily magnetic revolution of the globes, as against the time-honored opinion of a primum mobile: a probable
hypothesis 3^7
IV. That the earth hath a circular motion 327
V. Arguments of those who deny the earth's motion, and refuta- tion thereof 335
VI. Of the cause of the definite time of the total revolution of the
earth 343
VII. Of the earth's primary magnetic nature whereby her poles are
made different from the poles of the ecliptic 347
VIII. Of the precession of the equinoxes by reason of the magnetic
movement of the earth's poles in the arctic and antarctic
circle of the zodiac. 348
IX. Of the anomaly of the precession of the equinoxes and of the
obliquity of the zodiac 35^
To the most learned Mr. William Gilbert, the distinguished Lon- don physician and father of the magnetic philosophy : a laudatory address concerning these books on magnetism, by Edward Wright.
Should there be any one, most worthy sir, who shall dis- parage these books and researches of yours, and who shall deem these studies trifling and in no wise sufficiently worthy of a man consecrated to the graver study of medicine, of a surety he will be esteemed no common simpleton. For that the uses of the loadstone are very considerable, yea admirable, is too well known even among men of the lowest class to call for many words from me at this time or for any commenda- tion. In truth, in my opinion, there is no subject-matter of higher importance or of greater utility to the human race upon which you could have brought your philosophical talents to bear. For by the God-given favor of this stone has it come about that the things which for so many centuries lay hid — such vast continents of the globe, so infinite a number of countries, islands, nations and peoples — have been, almost within our own memory, easily discovered and oft explored, and that the whole circle of the globe has been circumnavi- gated more than once by our own Drake and Cavendish: which fact I wish to record for the undying remembrance of those men. For, by the showing of the magnetized needle, the points North, South, East and West and the other points of the compass are known to navigators, even while the sky is
XXXVIU ADDRESS BY EDWARD WRIGHT.
murky and in the deepest night ; by this means seamen have understood toward what point they must steer their course, a thing that was quite impossible before the wondrous discovery of the north-pointing power of the loadstone. Hence sailors of old were often beset, as we learn from the histories, by an incredible anxiety and by great peril, for, when storms raged and the sight of sun and stars was cut off, they knew not whither they were sailing, neither could they by any means or by any device find out. Hence what must have been the gladness, what the joy of all mariners when first this magnetic pointer offered itself as a most sure guide on the route and as a God Mercury ! But it was not enough for this magnetic Mercury simply to point out the way and, as it were, to show by the extended finger whither the course must be: it soon began even to indicate the distance of the place whither the voyage is made. For, since the magnetic pointer does not always regard the same northern spot in every locality, but usually varies therefrom, either to the east or to the west, tho' it nevertheless hath and holds ever the same variation in the same place, wherever that may be ; it has come about that by means of this variation (as it is called) closely observed and noted in certain maritime regions, together with an observa- tion of the latitude, the same places can afterward be found by navigators when they approach and come near to the same variation. Herein the Portuguese in their voyages to the East Indies have the surest tokens of their approaching the Cape of Good Hope, as is shown in the narrations of Hugo Lynschetensis ^ and our very learned fellow-countryman Richard Hakluyt ; hereby, too, many of our skilled British navi- gators when voyaging from the Gulf of Mexico to the Azores,
* Jan Hugo van Linscho(o)ten, Dutch voyager, 1563-1633,
ADDRESS BY EDWARD WRIGHT. XXXIX
can tell when they are come near to these islands, though, according to their marine charts, they may appear to be 600 Eng- lish miles away. And thus, thanks to this magnetic indication, that ancient geographical problem, how to discover the longi- tude, would seem to be on the way to a solution ; for, the variation of a seaboard place being known, that place can there- after be very easily found as often as occasion may require, provided its latitude is not unknown.
Yet somewhat of inconvenience and difficulty seems to at- tach to this observation of the variation, for it cannot be made except when the sun or the stars are shining. Accordingly this magnetic Mercury of the sea, better far than Neptune himself or any of the sea gods or goddesses, proceeds still further to bestow blessings on all mariners ; and not alone in the darkness of night and when the sky is murky does he show the true direction, but he seems even to give the surest indica- tions of the latitude. For the iron pointer suspended freely and with the utmost precision in equilibrium on its axis, and then touched and excited with a loadstone, dips down to a fixed and definite point below the horizon (e.g. in the latitude of London it dips nearly 72 degrees) and there stands. But because of the wonderful agreement and congruency mani- fested in nearly all and singular magnetic experiments, equally in the earth itself and in a terrella (i.e. a spherical loadstone), it seems (to say the least) highly probable and more than prob- able that the same pointer (similarly stroked with a loadstone) will, at the equator, stand in equilibrium on the plane of the horizon. Hence, too, it is highly probable that in proceeding a very short distance from south to north (or vice versa) there will be a pretty sensible change in the dip ; and thus the dip being carefully noted once and the latitude observed, the same place and the same latitude may thereafter be very readily
xl ADDRESS BY ED WARD WRIGHT.
found by means of a dip instrument even in the darkest night and in the thickest weather.
Thus then, to bring our discourse back again to you, most worthy and learned Mr. Gilbert (whom I gladly acknowledge as my master iii this magnetical philosophy), if these books of yours on the Loadstone contained nought save this one method of finding the latitude from the magnetic dip, now first pub- lished by you, even so our British mariners as well as the French, the Dutch, the Danes, whenever they have to enter the British sea or the strait of Gibraltar from the Atlantic Ocean, will justly hold them worth no small sum of gold.* And that discovery of yours, that the entire globe is magnetical, albeit to many it will seem to the last degree paradoxical, never- theless is buttressed and confirmed by so many and so apposite experiments in Book II, Chapter XXXIV; Book III, Chap- ters IV and XII ; and throughout nearly the whole of Book V, that no room is left for doubt or contradiction. I come therefore to the cause of magnetic variation — a problem that till now has perplexed the minds of the learned ; but no one ever set forth a cause more probable than the one proposed now for the first time in these your books on the Loadstone. The fact that the magnetic needle points due north in the middle of the ocean and in the heart of continents — or at least
1 Hardly twenty years after the English artificer, Robert Norman, had, in 1576, devised the inclinatorium, which enabled him to determine the dip or inclination of the magnetic needle, Gilbert boasted that, by means of this in- strument, he could ascertain a ship's place in dark starless nights, Gilbert commends the method as applicable aere caliginoso; and Edward Knight, the English mathematician, in the introduction which he added to his master's great work, describes this proposal as "worth much gold." Having fallen into the same error with Gilbert of presuming that the isoclinal lines coincided with the geographical parallel circles, and that the magnetic and geographical equa- tors were identical, he did not perceive that the proposed method had only a local and very limited application (Humboldt, Cosmos, 1849, Vol. I, page 172, and Vol. H, page 658).
ADDRESS BY EDWARD WRIGHT. xH
in the heart of their more massive and more elevated parts — while near the coasts there is, afloat and ashore, an inclination of the needle toward those more massive parts, just as happens in a terrella that is made to resemble the earth globe in its greater elevation at some parts and shows that it is weak or decayed or otherwise imperfect elsewhere : all this makes ex- ceedingly probable the theory that the variation is nothing but a deviation of the magnetic needle to those more powerful and more elevated regions of the globe. Hence the reason of the irregularity that is seen in the variations of the compass is easily found in the inequality and anomaly of those more elevated parts. Nor do I doubt that all those who have imagined or accepted certain " respective points " as well as they who speak of magnetic mountains or rocks or poles, will begin to waver as soon as they read these your books on the Loadstone and will of their own accord come over to your opinion.
As for what you have finally to say of the circular motion of the earth and the terrestrial poles, though many will deem it the merest theorizing, still I do not see why it should not meet with indulgence even among those who do not acknowl- edge the earth's motion to be spherical, seeing that even they cannot readily extricate themselves from the many difficulties that result from a diurnal motion of the whole heavens. For, first, it is not reasonable to have that done by many agents which can be done by fewer, or to have the whole heavens and all the spheres (if spheres there be) of the planets and fixed stars made to revolve for the sake of the diurnal motion, which may be accounted for by a daily rotation of the earth. Then, which theory is the more probable, that the equinoctial circle of the earth may make a rotatary movement of one quarter of an EngHsh mile (60 miles being equal to one degree on the
Xlii ADDRESS BY EDWARD WRIGHT.
earth's equator) in one second of time, i.e., in about as much time as it takes to make only one step when one is walking rapidly; or that the equator of the primum mobile in the same time, with inexpressible celerity, makes 5000 miles and that in the twinkling of an eye it makes about 50 English miles, sur- passing the velocity of a flash of lightning, if they are in the right who most strenuously deny the earth's motion ? Finally, which is the more probable, to suppose that this little globe of the earth has some motion, or with mad license of conjec- ture to superpose three mighty starless spheres, a ninth, a tenth, and an eleventh/ upon the eighth sphere of the fixed stars, particularly when from these books on the Loadstone and the comparison of the earth with the terrella it is plain that spherical motion is not so contrary to the nature of the earth as it is commonly supposed to be ?
Nor do the passages quoted from Holy Writ appear to con- tradict very strongly the doctrine of the earth's mobility. It does not seem to have been the intention of Moses or the prophets to promulgate nice mathematical or physical distinc- tions : they rather adapt themselves to the understanding of the common people and to the current fashion of speech, as nurses do in dealing with babes; they do not attend to unessen- tial minutiae. Thus, Genesis i. 16 and Psalm cxxxvi. 7, 9, the moon is called a great luminary, because it so appears to us, though, to those versed in astronomy, it is known that very many stars, fixed and planetary, are far larger. So, too, from Ps. civ. 5,^^ no argument of any weight can, I think, be drawn to contradict the earth's mobility, albeit it is said that God es- tablished the earth on her foundations to the end it should never
1 See note, Book VI, Chap. III.
* Psalm civ. 5, " Who laid the foundations of the earth, that it should not be removed forever."
ADDRESS BY EDWARD WRIGHT. xliii
be moved ; for the earth may remain forevermore in its own place and in the selfsame place, in such manner that it shall not be moved away by any stray force of transference, nor carried beyond its abiding place wherein it was established in the beginning by the divine architect. We, therefore, while we devoutly acknowledge and adore the inscrutable wisdom of the triune Godhead, having with all diligence investigated and dis- cerned the wondrous work of his hands in the magnetic move- ments, do hold it to be entirely probable, on the ground of experiments and philosophical reasons not few, that the earth while it rests on its centre as its basis and foundation, hath a spherical motion nevertheless.
But, apart from these matters (touching which no one, I do believe, ever gave more certain demonstrations), no doubt your discussion if the causes of variation and of the dip of the needle beneath the horizon (to say nothing of sundry other points which 'twould take too long to mention) will find the heartiest approval among all intelligent men and " children of magnetic science " (to use the language of the chemists). Nor have I any doubt that, by publishing these your books on the Loadstone, you will stimulate all wide-awake navigators to give not less study to observation of dip than of variation. For it is highly probable, if not certain, that latitude, or rather the effect of lati- tude, can be determined much more accurately (even when the sky is darkest) from the dip alone, than longitude or the effect of longitude can be found from the variation even in the full light of day or while all the stars are shining, and with the help of the most skilfully and ingeniously contrived instrument. Nor is there any doubt that those most learned men, Petrus Plantius' (a most diligent student not so much of geography as
^ Peter Plancius, Dutch theologian and astronomer, 1 552-1622.
xliv ADDRESS BY EDWARD WRIGHT,
of magnetic observations) and Simon Stevinius/ a most eminent mathematician, will be not a little rejoiced when first they set eyes on these your books and therein see their own \i}xvev- periKTiv or method of finding ports so greatly and unexpect- edly enlarged and developed ; and of course they will, as far as they may be able, induce all navigators among their own coun- trymen to note the dip no less than the variation of the needle.
Let your magnetic Philosophy, most learned Mr. Gilbert, go forth then under the best auspices — that work held back not for nine years only, according to Horace's Counsel, but for almost other nine ; that Philosophy which by your multitudi- nous labors, studies, vigils, and by your skill and at your no inconsiderable expense has been after long years at last, by means of countless ingenious experiments, taken bodily out of the darkness and dense murkiness with which it was surrounded by the speculations of incompetent and shallow philosophizers ; nor did you in the mean time overlook, but did diligently read and digest whatever had been published in the writings whether of the ancients or the moderns. Let it not be afraid to face the prejudiced censure of any supercilious and dastardly phi- losophaster who, by enviously faulting another's work or by fraudulently taking the credit to himself, strives to win a most unsubstantial renown ; for
Ingenium magni livor detrectat Homeri,
(Envy detracts from the genius of mighty Homer;
2 Simon Stevin — Stevinus — celebrated Flemish mathematician (1548-1628), published in 1586 his well-known work on statics and hydrostatics, in the pref- ace of which he endeavors to prove that the Dutch language is more ancient than any other. This work was soon followed by others, including his De Motu Cceli, and, in 1599, by his Dutch treatise on navigation, translated in Latin by Grotius and published in Leyden. See references made at page 486 of the Ronalds Library Catalogue, likewise note Book Iv, Chap. IX, of the present work.
ADDRESS BY EDWARD WRIGHT. xlv
but
Quisquis es, ex illo, Zoile, nomen habes. whoever thou art, from him, Zoilus, dost thou derive thy fame.)*
Your work, I say, that has been kept back for so many
years, your New Physiology of the Loadstone and of the Great
Magnet (i.e. the Earth) — a philosophy never to be sufficiently
admired ; let it go forth into the light of publicity ; for, believe
me,
Siquid Jiabent veri vatum prcesagia,
(If the presages of poets have aught of truth)*
these your books on the Loadstone {De Magnete) will do more to perpetuate your memory than would the monument of any Magnate {Magnatis cujusvis) erected over your grave.
* Ovid's Remedia Amoris, Bohn, London 1852, page 475, tr. of Mr. Henry T. Riley, who adds: It was unknown of what parentage and country Zoilus was. He compiled a work in dispraise of Homer, and was called by the ancients ' Homeromastix,' 'the scourge of Homer.
2 "The Metamorphoses of Ovid," XV, 878 (tr, by Mr. Henry T. Riley), Bohn, London 1851, page 553.
AUTHOR'S PREFACE.
TO THE CANDID READER, STUDIOUS OF THE MAGNETIC PHILOSOPHY.
Since in the discovery of secret things and in the investi- gation of hidden causes, stronger reasons are obtained from sure experiments and demonstrated arguments than from probable conjectures and the opinions of philosophical speculators of the common sort ; therefore to the end that the noble sub- stance of that great loadstone, our common mother (the earth), still quite unknown, and also the forces extraordinary and ex- alted of this globe may the better be understood, we have decided first to begin with the common stony and ferruginous matter, and magnetic bodies, and the parts of the earth that we may handle and may perceive with the senses ; then to pro- ceed with plain magnetic experiments, and to penetrate to the inner parts of the earth. For after we had, in order to dis- cover the true substance of the earth, seen and examined very many rriatters taken out of lofty mountains, or the depths of seas, or deepest caverns, or hidden mines, we gave much atten-
xlvii
xlviii AUTHOR'S PREFACE.
tion for a long time to the study of magnetic forces — won- drous forces they, surpassing the powers of all other bodies around us, though the virtues of all things dug out of the earth were to be brought together. Nor did we find this our labor vain or fruitless, for every day, in our experiments, novel, unheard-of properties came to light : and our Philosophy be- came so widened, as a result of diligent research, that we have attempted to set forth, according to magnetic principles, the inner constitution of the globe and its genuine substance, and in true demonstrations and in experiments that appeal plainly to the senses, as though we were pointing with the finger, to exhibit to mankind Earth, mother of all.
And even as geometry rises from certain slight and readily understood foundations to the highest and most difficult demonstrations, whereby the ingenious mind ascends above the aether : so does our magnetic doctrine and science in due order first show forth certain facts of less rare occurrence ; from these proceed facts of a more extraordinary kind ; at length, in a sort of series, are revealed things most secret and privy in the earth, and the causes are recognized of things that, in the ignorance of those of old or through the heedlessness of the moderns, were unnoticed or disregarded. But why should I, in so vast an ocean of books whereby the minds of the studious are bemuddled and vexed ; of books of the more stupid sort whereby the common herd and fellows without a spark of talent are made intoxicated, crazy, puffed up ; are led to write numerous books and to profess themselves philosophers, phy- sicians, mathematicians, and astrologers, the while ignoring and contemning men of learning : why, I say, should I add aught further to this confused world of writings, or why should I sub- mit this noble and (as comprising many things before unheard of) this new and inadmissible philosophy to the judgment of
AUTHOR'S PREFACE. xHx
men who have taken oath to follow the opinions of others, to the most senseless corrupters of the arts, to lettered clowns, grammatists, sophists, spouters, and the wrong-headed rabble, to be denounced, torn to tatters and heaped with contumely. To you alone, true philosophers, ingenuous minds, who not only in books but in things themselves look for knowledge, have I dedicated these foundations of magnetic science — a new style of philosophizing. But if any see fit not to agree with the opinions here expressed and not to accept certain of my paradoxes ; still let them note the great multitude of experi- ments and discoveries — these it is chiefly that cause all philoso- phy to flourish ; and we have dug them up and demonstrated them with much pains and sleepless nights and great money ex- pense. Enjoy them you, and, if ye can, employ them for better purposes. I know how hard it is to impart the air of newness to what is old, trimness to what is gone out of fashion ; to lighten what is dark ; to make that grateful which excites disgust ; to win belief for things doubtful ; but far more difificult is it to win any standing for or to establish doctrines that are novel, unheard-of, and opposed to everybody's opinions. We care naught, for that, as we have held that philosophy is for the few.
We have set over against our discoveries and experiments larger and smaller asterisks according to their importance and their subtility. Let whosoever would make the same experi- ments, handle the bodies carefully, skilfully and deftly, not heedlessly and bunglingly ; when an experiment fails, let him not in his ignorance condemn our discoveries, for there is naught in these Books that has not been investigated and again and again done and repeated under our eyes. Many things in our reasonings and our hypotheses will perhaps seem hard to accept, being at variance with the general opinion ; but I have
1 AUTHOR'S PREFACE.
no doubt that hereafter they will win authoritativeness from the demonstrations themselves. Hence the more advanced one is in the science of the loadstone, the more trust he has in the hypotheses, and the greater the progress he makes ; nor will one reach anything like certitude in the magnetic philoso- phy, unless all or at all events most of its principles are known to him.
This natural philosophy {^physiologid) is almost a new thing, unheard-of before ; a very few writers have simply published some meagre accounts of certain magnetic forces. Therefore we do not at all quote the ancients and the Greeks as our supporters, for neither can paltry Greek argumentation demon- strate the truth more subtilly nor Greek terms more effectively, nor can both elucidate it better. Our doctrine of the loadstone is contradictory of most of the principles and axioms of the Greeks. Nor have we brought into this work any graces of rhetoric, any verbal ornateness, but have aimed simply at treating knotty questions about which little is known in such a style and in such terms as are needed to make what is said clearly intelligible. Therefore we sometimes employ words new and unheard-of, not (as alchemists are wont to do) in order to veil things with a pedantic terminology and to make them dark and obscure, but in order that hidden things which have no name and that have never come into notice, may be plainly and fully published.
After the magnetic experiments and the account of the homogenic parts of the earth, we proceed to a consideration of the general nature of the whole earth ; and here we decided to philosophize freely, as freely, as in the past, the Egyptians, Greeks, and Latins published their dogmas; for very many of their errors have been handed down from author to author till our own time ; and as our sciolists still take their stand on
AUTHOR'S PREFACE. H
these foundations, they continue to stray about, so to speak, in perpetual darkness. To those men of early times and, as it were, first parents of philosophy, to Aristotle, Theophrastus, Ptolemaeus, Hippocrates, Galen, be due honor rendered ever, for from them has knowledge descended to those that have come after them : but our age has discovered and brought to light very many things which they too, were they among the living, would cheerfully adopt. Wherefore we have had no hesitation in setting forth in hypotheses that are provable, the things that we have through a long experience discovered. Farewell.^
1 See the rendering of this Preface by Dr. B. W. Richardson and Mr. James Menzies, which appeared in " The Asclepiad " under the title of "The first electrician, William Gilbert, M.D."
EXPLANATION OF SOME TERMS USED IN THIS
WORK.
Terrella. A spherical loadstone or natural magnet.'
Verticity.'^ Polar strength — activity (or what in Gilbert's day was under- stood as energy) ; not gyrating, vertiginous, but turning power : nor is it polar revolution, but a directing virtue, an innate turning vigor {virtus convertens). ^' *
Electrics. Bodies that attract in the same way as amber.
Excited magnetic body. One (such as iron or steel) that acquires mag- netism from a loadstone or natural magnet.
Magnetized versorium. An iron bar or needle resting on a point (electroscope^) and put in motion — excited — by the loadstone or natural magnet.
Non-magnetized versorium (the electroscope itself). Made of any metal, for use in electrical experiments.
Armed loadstone. One that is furnished with an iron helmet or cap.*
Meridionally. In the direction of a meridian.
Paralleletically. In the direction of a parallel of latitude.
Cuspis (point). The end of a magnetized versorium.
' See Kenelm Digby's allusion to terrella in the Biographical Memoir, also De Magnete, Book I, Chap, III.
^ See De Magnete, Book I, Chap. X.
2 See De Magnete, Book II, Chap. VI, also Prof, Sir Wm. Thomson's allu- sion to the orbis virtutis in the Biographical Memoir.
* "Therefore true it is, and conformable by every experiment, that Steel and good Iron never excited by the Load-stone, discover in themselves a ver- ticity; that is, a directive or polary facultie whereby, conveniently placed, they do septentrionate at one extream, and Australize at another " (Thomas Brown, Pseudoloxia Efidemica, 1658, Book II, Chapter II, page 63).
^ Humboldt says ("Cosmos," 1849, Vol. II, page 726) that Gilbert meas- ured the strength of excited electricity by means of a small needle "not made of iron . . . ." De Magnete states that the versorium was made of any metal {ex quouis metallo) (Verborum, eighth line, and Book II, Chap. II, page 48), and alludes (Book III, Chap. I, page 115) to the construction of a versorium of two pieces of curved iron {ex duobus ctirvis ferramentis).
« See De Magnete, Book II, Chap. XVII.
liii
liv EXPLANATION OF SOME OF THE TERMS USED.
Crotch. Name sometimes given to the end not touched and excited, although in some instruments both ends are commonly so desig- nated, according as they are most convenient for excitation by the loadstone.^
Cork. Bark of the cork-tree,
Radius (of a loadstone's sphere). A right line drawn in the shortest way from the surface of a spherical loadstone to the surface of a body, and which when produced passes through the centre of the loadstone.
Sphere of iiifiuence. The entire space over which the force of a load- stone extends.'^
Sphere of coition. The entire space over which the smallest magnetic body moves toward a loadstone.
Ostensio. Physical demonstration (opposed to theory).
Magnetic coition.^ This phrase is used rather than attraction because magnetic movements do not result from attraction of one body alone but from the coming together of two bodies harmoniously (not the drawing of one by the other) — '^Ojj.odpourf, the coition is always vigorous, even though heavy substances make opposition.
Declinatorium. A bar or needle movable vertically on its axis and that is excited with a loadstone ; used in the dip instrument.
» See De Magnete, Book II, Chap. XXXII.
2 See note 3, page xxxi.
^ See De Magnete, Book II, Chap. I, et seq.
WILLIAM GILBERT.
BOOK FIRST.
CHAPTER I.
WRITINGS OF ANCIENT AND MODERN AUTHORS CONCERNING THE LOADSTONE : VARIOUS OPINIONS AND DELUSIONS.
In former times when philosophy, still rude and uncul- tured, was involved in the murkiness of errors and ignorances, a few of the virtues and properties of things were, it is true, known and understood : in the world of plants and herbs all was confusion, mining was undeveloped, and mineralogy neglected. But when, by the genius and labors of many workers, certain things needful for man's use and welfare were brought to light and made known to others (reason and experience meanwhile adding a larger hope), then did mankind begin to search the forests, the plains, the mountains and precipices, the seas and the depths of the waters, and the inmost bowels of earth, and to investigate all things. And by good luck at last the loadstone was found, as seems probable, by iron-smelters or by miners in veins of iron ore. On being treated by the metallurgists, it
2 WILLIAM GILBERT.
quickly exhibited that strong powerful attraction of iron — no la- tent nor obscure property, but one easily seen of all; one observed and commended with many praises. And after it had come forth as it were out of darkness and out of deep dungeons and been honored of men on account of its strong and marvellous attrac- tion of iron, then many ancient philosophers and physicians discoursed of it, and briefly (but briefly only) made it matter of record: as, for instance, Plato in the lo, Aristotle only in his first book De Anima; likewise Theophrastus the Lesbian, Dioscorides, Caius Plinius secundus, Julius Solinus. These record only that the loadstone attracts iron : its other proper- ties were all hid. But lest the story of the loadstone should be jejune and too brief, to this one sole property then known were appended certain figments and falsehoods which in the early time no less than nowadays were by precocious sciolists and copyists dealt out to mankind to be swallowed. For ex- ample, they asserted that a loadstone rubbed with garlic does not attract iron ; nor when it is in presence of a diamond.' The like of this is found in Pliny and in Ptolemy's Quadripar- titum; and errors have steadily been spread abroad and been
' " As to what some writers have related, that a load-stone will not attract iron if there be a diamond near (Pliny, Book XXXVII, Chap. IV) and that onions and garlic will make it lose its vertue; these are contradicted by a thousand ex- periments which I have tried. For I have shown that this stone will attract iron through the very thickest diamonds and through a great many thick skins which an onion is made up of (Rohault's ' Syst. Nat. Phil.,' 1728, Vol. II, page 186). That garlic does not hinder the action of the load-stone is likewise shown by Porta, ' Nat. Magick,' 1658, Book VII, Chap. XLVIII, and by Sir Thos. Brown, at page 74 of his Pseudoloxia Epidemica published in the same year, but the contrary is shown by Sir Hugh Plat in The Jewell House of Arte and Nature, originally published in 1594." Consult, also, Plutarch, Quasi. Conviv. Lib. II, Qusest 7) ; Barthol. de Glanvil, Zz^^. de Prop., Lyons 1480, folio, Lib. XVI; Pietro d'Abano {Conciliator Differentiarum, LI, Venice ed. 1526); Ibn Roschd's Comment, on Aristotle, 1550, T. 4, p. 143 t. ; Nic. de Cusa, Opera, Basilae 1565, p. 175 ; Cardan, De Subtil., Lib. VII, Op. T. Ill, Basilae ed. 1582 ; Porta, " Nat. Magick," 1658, Book VII, Chap. LV, page 215.
ANCIENT AND MODERN A UTHORS ON THE LOADSTONE. 3
accepted — even as evil and noxious plants ever have the most luxuriant growth — down to our day, being propagated in the writings of many authors who, to the end that their volumes might grow to the desired bulk, do write and copy all sorts about ever so many things of which they know naught for cer- tain in the light of experience. Such fables about the loadstone even Georgius Agricola, a man that has deserved well indeed of letters, has inserted as truthful history in his books De Natura Fossilium, putting his trust in others' writings.* Ga- len, in the ninth book of his De Simplicium Medicamentorum, Facultatibus, recognizes its medicinal virtue, and its natural power of attracting iron, in the first book of his De Naturalibus Facultatibus ; but he knew not the cause, any more than Dioscorides before him, nor did he seek further. But his translator Matthiolus furbishes again the garlic and diamond story, and further brings in the fable of Mahomet's shrine hav- ing an arched roof of magnets so that the people might be fooled by the trick of the cofifin suspended in air, as though 'twere some divine miracle. But this is shown to be false by the reports of travellers. Pliny, however, records that the architect Chinocrates began to put an arched roof of load- stone on the temple of Arsinoe at Alexandria, so that her effigy in iron might seem to be suspended in air: in the meantime the architect died, as also Ptolemy, who had or- dered the work to be done in honor of his sister.* But little
1 See account of the life and writings of George Agricola in the sixth chapter of "The History of Chemistry," by Dr. Thomas Thomson, who calls him one of the most extraordinary men as well as one of the greatest promoters of chemistry that have ever existed, and who pronounces Agricola's De Re Metallica as, beyond comparison, the most valuable chemical work which the sixteenth century produced.
'•^ " So it is reported by Ruffinus, that in the Temple of Serapis there was an iron chariot suspended by Loadstones in the ayr; which stones removed, the chariot fell and dashed into pieces. The like doth Beda report of Bellerophon's
4 WILLIAM GILBERT.
has been written by the ancients about the causes of the attraction of iron : some trifling remarks of Lucretius and others are extant ; other authors barely make slight mention of the attraction of iron : all these are berated by Cardan for being so heedless and indifferent about so notable a matter, $>o broad a field of philosophizing, and for not giving a fuller account or a more developed philosophy ; yet Cardan himself in his ponderous volumes has handed down to posterity, be- yond a few commonplaces and quotations from other writers and false discoveries, naught that is worthy of a philosopher.' Of later authors, some tell only of its efificacy in medicine, as Antonius Musa Brasevolus, Baptista Montanus, Amatus Lu- sitanus, as did before them Oribasius in book 13th of the De Facultate Metallicorum, Avicenna, Serapio Mauritanus, Abo- hali (Hali Abbas), Santes de Ardoniis, Petrus Apponensis, Marcellus, Arnaldus. Only a few points touching the load- stone are very briefly mentioned by Marbodeus Callus, Albertus, Matthseus Silvaticus, Hermolaus Barbatus, Camillus Leonhardus, Cornelius Agrippa, Fallopius, Joannes Langius, Cardinal de Cusa, Hannibal Roserius Calaber : by all these the subject is handled in the most careless way, while they repeat only the figments and ravings of others. Matthiolus compares the attractive virtues of the loadstone, which pass through iron, to the mischief of the torpedo, whose poison
horse, which, framed of iron, was placed between two Loadstones, with wings expansed, pendulous in the ayr " (Thom. Brown, Pseudoloxia Epidemica, 1658, Book II, page 79). Consult : Ath. Kircheri, Magnes; Sive dearte magnetica, 1643, Lib. II, Pars IV, Problema VI; Vincentii Burgundi Spec. Mai., T. i, L. VIII, C. 34, Douai ed. 1624 ; Alb. Magnus, De Mineralibus, LIT, Tr. Ill, c. vi, p. 243, Lione 165 1 ; Ausonio L. Ampelius, Lib, Memorialis, c. viii, Paris 1827 ; J. H. Martin, " Observ. et Theories . . .," Rome, 1865, pp. 5, 6, 7.
^ For a better list than Cardan's, of authors who have written on the load- stone, consult "Petri Peregrini . . . Achillem T. Gasserum . . . Augs- burg! . . . 1558." ■^■■'^
ANCIENT AND MODERN AUTHORS ON THE LOADSTONE. 5
passes through bodies and spreads in an occult way. Guliel- mus Puteanus in his Ratio Purgantiutn Medicamentorum dis- cusses the loadstone briefly and crudely. Thomas Erastus, knowing naught of the nature of the loadstone, draws from it weak; arguments against Paracelsus. Georgius Agricola, like Encelius and other writers on metals, simply describes it. Alexander Aphrodiseus, in his Problemata, judges the question of the loadstone to be incapable of explication. Lucretius Carus, the Epicurean poet, deems the attraction to be due to this, that as there is from all things an efflux of minutest bodies, so there is from iron efflux of atoms into the space betwixt the iron and the loadstone — a space emptied of air by the loadstone's atoms (seeds) ; and when these begin to return to the loadstone, the iron follows, the corpuscles being entangled with each other. Something similar is said by Joannes Costaeus, following Plutarch. Thomas Aquinas, in his Fhysica, Bk. 7, treating briefly of the loadstone, gets at the na- ture of it fairly well : with his godlike and perspicacious mind he would have developed many a point had he been acquainted with magnetic experiments. Plato holds the magnetic virtue to be divine. But when, some three or four hundred years ago, the magnetic movement to the north and the south was discov- ered or recognized anew, many learned men, each according to his own gifts, strove to honor with admiration and praise or to explain with feeble reasonings a property so curious and so necessary for the use of mankind. Of more recent authors, very many have striven to discover the cause of this direction and movement to north and south, and to understand this so great miracle of nature and lay it open to others : but they wasted oil and labor, because, not being practical in the re- search of objects in nature, being acquaint only with books, being led astray by certain erroneous physical systems, and
O WILLIAM GILBERT.
having made no magnetical experiments, they constructed certain raciocinations on a basis of mere opinions, and old- womanishly dreamt the things that were not. Marcilius Ficinus chews the cud of ancient opinions, and to give the reason of the magnetic direction seeks its cause in the constel- lation Ursa : in the loadstone, says he, the potency of Ursa prevails and hence it is transferred into the iron. Paracelsus declares that there are stars which, gifted with the loadstone's power, do attract to themselves iron. Levinus Lemnius de- scribes and praises the mariner's compass, and on certain grounds infers its antiquity; he does not divulge the hidden miracle which he makes profession to know. The people of Melfi, in the kingdom of Naples, first, 'tis said, constructed a mariner's compass ; and, as Flavius Blondus says, the towns- men do not without reason boast, they were so taught by one Joannes Goia, a fellow-citizen, in the year 1300.' This town is in the Kingdom of Naples, not far from Salerno, and near the promontory of Minerva. The sovereignty of the place was conferred by Charles V. on Andrea Doria, the great naval commander, in recognition of his splendid achievements. And that nothing ever has been contrived by the art of man nor anything been of greater advantage to the human race than the mariner's compass is certain : but many infer from ancient writings and from certain arguments and conjectures, that the compass was discovered earlier and received among the arts of navigation. Knowledge of the mariner's compass
* In his "Essay on Several Important Subjects," London 1676, Joseph Glanvill remarks (page 33): " I think there is more acknowledgement due to the name of this obscure fellow, that hath scarce any left, than to a thousand Alex- anders and Caesars, or to ten times the number of Aristotles and Aquinas. And he really did more for the increase of knowledge, and advantage of the world, by this one experiment, than the numerous subtile disputers that have lived ever since the Erection of the School of Wrangling."
ANCIENT AND MODERN A UTHORS ON THE LOADSTONE. 7
appears to have been brought into Italy by the Venetian Paolo [Paulum Veftetum — Marco Polo] who about the year 1260 learned the art of the compass in China/ still I do not want to strip the Melfitani of so great an honor, seeing that by them compasses were first commonly made in Mediterranean lands. Goropius ascribes the invention to the Cimbri or Teu- tons, on the ground that the thirty-two names of the winds inscribed on the compass are pronounced in German by all mariners, whether they be British or Spaniards, or French- men. But the Italians give them names in their own ver- nacular. Some think that Solomon, King of Judea, was acquaint with the compass and taught the use of it to his pilots for their long voyages when they brought from the Western Indies such a quantity of gold : hence Arias Monta- nus holds that the regions in Peru that abound in gold got their name from the Hebrew word Paruaim. But it is more probable that the gold came from the coast of lower Ethiopia, or, as others declare, from the region called Cephala. The story seems less true for the reason that the Phcenicians, next neighbors of Judea, most skilful navigators in early times
^ It appears to be a remarkable fact that Gilbert, the earliest classical writer on terrestrial magnetism, who cannot be supposed to have had the slightest knowledge of Chinese literature, should regard the mariner's compass as a Chinese invention, which had been brought to Europe by Marco Polo. The idea of the introduction of the compass by the last named, whose travels occurred in the interval between 1271 and 1295, and who, therefore, returned to Italy after the mariner's compass had been mentioned as a long-known in- strument by Guyot de Provins in his politico-satirical poem ("La Bible," 1190), as well as by Jacques de Vitry (" Historise Hierosolimitanae," Cap. 89), and Dante (" Paradiso," Cant. XII), is not supported by any evidence. Before Marco Polo set out on his travels in the middle of the thirteenth century, Catalans and Basques already made use of the compass (Humboldt, "Cosmos," Vol. II, pages 625, 656; Raymond Lully, in his " De Contemplatione," " Fenix de las maravillas del orbe," and " Arte de Naveguar;" Azuni, " Bous' sole," page 69; Miller, " History Philos. 111.", London 1849, Vol. I, pages 179- 180).
8 WILLIAM GILBERT.
(whose talents, labor, and counsels Solomon employed in building ships and in his expeditions as well as in other ways), were ignorant of magnetic aids, of the use of the mariner's compass : for were it used by them, doubtless the Greeks, the Italians, and all the Barbarians would have known of a thing so necessary and so celebrated through common use ; nor would things famous, most easily known, and of the highest necessity, ever perish in oblivion ; on the contrary, the knowl- edge would have been handed on to posterity, or some memo- rial in writing would survive.
Sebastian Cabot first discovered that the magnetized iron (needle) varied/ Gonzales Oviedo first made mention in his history that in the meridian of the Azores there is no varia- tion. [Jean Frangois] Fernel, in his book De Abditis Rerum CausiSf says that in the loadstone is a hidden and abstruse cause : elsewhere he says this cause is celestial ; and he does but explain the unknown by the more unknown. This search after hidden causes is something ignorant, beggarly, and re- sultless. The ingenious Fracastorio, a philosopher of no com- mon stamp,'' asks what gives direction to the loadstone
^ At page 150 of the 1869 London edition of Mr. J. F. Nicholls' Life of Seb. Cabot, it is said the latter represented' to the King of England that the variation of the compass was different in many places, and was not absolutely- regulated by distance from any particular meridian; also, that he could point to a spot of no variation, and that those whom he trained as seamen, as Chancel- lor and Stephen Burrough were particularly attentive to this problem, noting it at one time thrice within a short space (" Biddle," Memoir of Sebastian Cabot, 1831; Humboldt, in both his " Examen Critique" and his "Cosmos," treating of "Oceanic Discoveries").
'^ Hieronymus Fracastorio, the great cotemporary of Columbus, to whom Gilbert alludes so frequently, was one of the most learned men of his time (1483-1553). From his early youth, he devoted himself to the study of the sciences, medicine especially, and he is said to have been made professor of logic at the University of Padua when only nineteen years of age. The first edition of his complete works appeared at Venice in 1555. Edward Biot tells us that it was Fracastorio and Peter Appian, who first made generally known in
ANCIENT AND MODERN A UTHORS ON THE LOADSTONE. 9
[needle], and imagines the existence of hyperborean magnetic mountains, attracting objects of magnetic iron. This opinion, in some degree accepted by others also, many authors follow in their writings, their geographical maps, their marine charts, and their descriptions of the globe : dreaming [imagining to themselves the existence of] magnetic poles and mighty cliffs, apart from the earth's poles. Of date two hundred years or more earlier than Fracastorio, is a small work attributed to one Petrus Peregrinus, a pretty erudite book considering the time : many believe it owes its origin to the opinions of Roger Bacon, Englishman of Oxford.' In this work the arguments touching the magnetic direction are drawn from the celestial poles and from the heaven itself. From this book of Petrus Peregrinus, Joannes Taisner Hannonius" extracted the matter
Europe the peculiar fact, noticed by the Chinese astronomers as early as 837, that the tails of comets are always turned away from the sun, so that their line of prolongation passes through its centre (Humboldt, "Cosmos," 1849, Vol, I, page 86, and Vol. II, page 697).
1 Roger Bacon, sometimes called Friar Bacon, flourished after the dis- tinguished Albertus Magnus (who, strangely enough, is omitted by Olaus Bor- richius in his list of alchymistical writers), and was by far the most illustrious and best informed of all the alchymists. In one of his numerous works he dwells upon the mariner's compass as a miraculum in parte notum. Alexander von Humboldt remarked that Roger Bacon, Albertus Magnus, as well as the Arabian philosophers Avicenna and Averroes, passed for the representatives of all the knowledge of their time.
2 Joannes Taisner of Ath in Hainault (hence Hannonius) is mentioned (Ronald's Catalogue, page 493) as the author of "...De Natura Magnetis et ejus effectibus . . . ,"Coloniae 1562, an English translation of which, by Richarde Eden, was published in London about 1579. The first Gasser's printed edition of Petrus Peregrinus is dated Augsburg 1558. To Peregrinus is ascribed the first mention of the double polarity of the magnet (Nicolas Cabeo, T/ziL Magnetica, Ferrara 1629, Lib. II, C. 3, 8), as well as the designation of the word poles for points of greatest energy in the magnet (Bertelli Barnabita, " Sopra P. Pere- grino . . . ," Roma 1868, pp. 34, 62, 63, 70, 71). As is already known, the last claim has by others been made for Gilbert. Taisner's De Natura, again alluded to by Gilbert (Book Il.Chap.XXXV), is said by Bertelir and others to be a more manifest plagiarism upon Peregrinus than even that of Antonius Fantis of Treviso. (Nic. Cabeo, Phil. Magn., 1629, page 23.)
lO WILLIAM GILBERT.
of a little volume, which he published for new. Cardan makes much of the star in the tail of Ursa Major ; the cause of varia- tion he assigns to its rising, thinking that variation is always certain at the rising of the star. But the difference of varia- tion for change of locality, and the mutations in many places — mutations that even in the southern regions are irregular — preclude this exclusive dominance of one star at its northern rising. The College of Coimbra seeks the cause in some region of the heavens nigh to the pole ; Scaliger, in the 131st of his -Exercitationes on Cardan's work De Subtilitate, brings in a celestial cause to himself unknown, and terrestrial loadstones that have nowhere been discovered ; and seeks the cause not in the " siderite mountains " but in that force which formed them, to wit, in the part of the heavens which overhangs that northern point. This opinion the learned author dresses in abundant verbiage and crowns with many subtile observations in the margin : but his reasons are not so subtile. Martinus Cortesius holds that the seat of the attraction is beyond the poles, and that it is the heavens in motion. One Bessard, a Frenchman, studies the pole of the Zodiac, but to as little pur- pose. Jacobus Severtius, of Paris, after quoting a few obser- vations of others, fashions new errors about loadstones of dif- ferent regions being different in direction, as also about the eastern and western parts of a loadstone. Robert Norman, an Englishman, posits a point and place toward which the magnet looks (but whereto it is) not drawn : toward which magnetized iron, according to him, is collimated, but which does not attract it. Franciscus Maurolycus * discusses a few problems regarding the loadstone, adopting the current opinions of others ; he believes that the variation is caused by
' An account of Francis Maurolycus appears in a note, Book I, Chap. XVII, of present work.
ANCIENT AND MODERN AUTHORS ON THE LOADSTONE, II
a certain magnetic island mentioned by Olaus Magnus. Josephus Costa, knowing nothing whatever of the subject, nevertheless pours out empty words about the loadstone. Livio Sanuto in his Geography (written in Itahan) discourses at length of the prime magnetic meridian, of the magnetic poles, whether they are terrestrial or celestial ; treats also of an instrument for finding the longitude ; but as he does not understand the nature of the loadstone, he does but add errors and obscurities to his otherwise excellent treatise. Fortunius Affaitatus has some rather silly philosophizing about attraction of iron and the turning toward the poles. Very recently Baptista Porta, a philosopher of no ordinary note, makes the 7th book of his Magia Naturalis a very storehouse and repertory of magnetic wonders ; but he knows little about the movements of the loadstone, and never has seen much of them ; much of what he has learned about its obvious properties, either from Messer Paolo, the Venetian, or through his own studies, is not very accurately noted and ob- served ; the book is full of most erroneous experiments, as will appear in fitting place ; still I hold him worthy of praise for that he essayed so great a task (even as he has essayed many another task, and successfully too, and with no inconsiderable results), and that he has given occasion for further researches. All these philosophers, our predecessors, discoursing of attraction on the basis of a few vague and indecisive experi- ments and of reasonings from the recondite causes of things ; and reckoning among the causes of the direction of the magnet, a region of the sky, celestial poles, stars, asterisms ; or moun- tains, cliffs, vacant space, atoms, attractional or collimational regions beyond the heavens, and other like unproved para- doxes, are world-wide astray from the truth and are blindly wandering. But we do not propose just now to overturn with
12 WILLIAM GILBERT.
arguments either these their errors and impotent reasonings, or the other many fables about the loadstone, or the fairy-tales of mountebanks and story-tellers; as, for example, the ques- tions raised by Franciscus Rueus about the loadstone, whether it is an imposture of cacodaemons ; or the assertion that a loadstone placed unawares under the head of a sleeping woman drives her out of the bed if she be an adulteress ; or that by its fume and vapor the loadstone is of use to thieves, as though the stone were by nature given to promote thefts ; or that it withdraws bolts and opens locks, as Serapio insanely imagines ; or that iron held by a loadstone's attraction, being placed in a balance, adds nought to the weight of the loadstone, as though the weight of the iron were absorbed by the virtue of the loadstone ; or that, as Serapio and the Moors report, there are in Indian seas certain sharp-pointed rocks abounding in loadstone, the which draw every nail out of ships that land alongside them and hold the vessels : this story, Olaus Magnus does not fail to recite : he tells of mountains in the North possessing such power of attraction, that ships have to be con- structed with wooden pegs, so that as they sail by the magnetic cliffs there be no iron nails to draw out.' Nor will
' Olaus Magnus, Historia de Gentibus Septentrionalibus, Romae 1555, Book II, Chap. XXVI, page 8g. This is likewise alluded to by Porta in his Magia Naturalis, 1658 ed., Book VII, Chap. I, page 191, and 1664 ed.. Book VII, Chap. I, page 288.
"Of Rocks Magnetical there are likewise two relations; for some are delivered to be in the Indies and some in the extremity of the North and about the very Pole. The Northern account is commonly ascribed unto Olaus Magnus, Arch-Bishop of Upsale, who out of his Predecessor, Joannes, Saxo, and others compiled a history of some Northern Nations; but this assertion we have not discovered in that work of his which commonly passeth among us; and should believe his Geography herein no more then that in the first line of his book; when he affirmeth that Biarmia (which is not 70 degrees in latitude) hath the Pole for its Zenith, and Equinoctial for the Horizon" (Thomas Brown, Pseudoloxia Epidemica, 1658, Book II, page 78). Consult, also, Claudius Ptolo-
ANCIENT AND MODERN AUTHORS ON THE lOADSTONE- 1 3
we take the trouble to refute such stories as that a white load- stone may be used as a philter ; or that, as Abohali (Hali Abbas) rashly asserts, when held in the hand it cures pains of the feet and cramps ; or that, as Pictorius sings, it gives one favor and acceptance with princes or makes one eloquent ; that, as Albertus Magnus says, there are two species of load- stones, one pointing north, the other south ; or that iron is directed toward the northern stars by a force communicated from the polar stars, even as plants, like the sunflower, follow the sun ; or, as the astrologer Lucas Gauricus held, that beneath the tail of Ursa Major is a loadstone ; Lucas further assigns the loadstone (as the sardonyx and the onyx) to the planet Saturn, but also to Mars (with the diamond, jasper, and ruby), so that the loadstone, according to him, is ruled by two planets ; further, Lucas says that the loadstone belongs to the sign Virgo ; and with a veil of mathematical erudition does he cover many similar disgraceful stupidities. Gaudentius Merula advises that on a loadstone be graven the image of a bear, when the moon looks to the north, so that being suspended by an iron thread it may win the virtue of the celestial Bear ; Ficinus writes, and Merula copies, that the loadstone draws iron and makes it point north, because it is of higher order than iron in the Bear. Others tell that in daytime the load- stone possesses the power of attracting iron, but that at night this power is feeble or rather null ; Ruellius writes that the loadstone's force, when failing or dulled, is restored by the blood of a buck ; it has been said that a buck's blood frees the magnet from the diamond's sorcery, giving back its lost power
mseus, Geographia, Lib. vii, c. 2; Klaproth Boussole, Paris 1834, p. 116, etc.; Taisnier's Z>^ iVfls/^ra, 1562, Eden tr. p. 12; " Beati Alb. Magni, Ratisbonien- sis . . . ," Lib. viii, Lugduni 1651 ; J. H. Martin, " Observ, et Theories," Rome 1865, p, 304.
14 WILLIAM GILBERT.
when the magnet is bathed in the blood — this, because of the variance between that blood and the diamond ; * Arnoldus de Villanova fancies that the loadstone frees women from witch- craft and puts demons to flight ; Marbodaeus, a Frenchman, fugleman of vain imaginings, says that it can make husbands agreeable to wives and may restore wives to their husbands ; Caelius Calcagninius in his Relationes says that a magnet pickled with salt of the sucking-fish has the power of picking up a piece of gold from the bottom of the deepest well. In such-like follies and fables do philosophers of the vulgar sort take delight; with such-like do they cram readers a-hungered for things abstruse, and every ignorant gaper for nonsense. But when the nature of the loadstone shall have been in the discourse following disclosed, and shall have been by our labors and experiments tested, then will the hidden and recon- dite but real causes of this great effect be brought forward, proven, shown, demonstrated ; then, too, v/ill all darkness vanish ; every smallest root of error, being plucked up, will be cast away and will be neglected; and the foundations of a grand magnetic science being laid will appear anew, so that high intellects may no more be deluded by vain opinions.
There are other learned men who on long sea voyages have observed the differences of magnetic variation ; as that most accomplished scholar Thomas Hariot, Robert Hues, Edward Wright, Abraham Kendall, all Englishmen ; others have invented and published magnetic instruments and ready methods of observing, necessary for mariners and those who make long voyages : as William Borough in his little work the Variation of the Compass, Williani Barlo (Barlowe) in his
1 Consult: Simon, Clavis Sanationis, Padua 1474; C. G. Solino, Folykisior, p. 154, Lyons ed. 1538; Vincentii Burgundi, Spec. Mai. T. i. Lib. 8, c. 40, Douai ed. 1624.
THE LOADSTONE: WHAT IT IS: ITS DISCOVERY. 1 5
Supplement, Robert Norman in his New Attractive — the same Robert Norman, skilled navigator and ingenious artificer, who first discovered the dip of the magnetic needle/ Many others I pass by of purpose : Frenchmen, Germans, and Spaniards of recent time who in their writings, mostly composed in their vernacular languages, either misuse the teachings of others, and like furbishers send forth ancient things dressed with new names and tricked in an apparel of new words as in prosti- tutes' finery ; or who publish things not even worthy of record; who, pilfering some book, grasp for themselves from other authors, and go a-begging for some patron, or go a-fishing among the inexperienced and the young for a reputation ; who seem to transmit from hand to hand, as it were, erroneous teachings in every science and out of their own store now and again to add somewhat of error.
CHAPTER II.
THE LOADSTONE: WHAT IT IS: ITS DISCOVERY.
This stone is commonly called magnet, either after its finder {not Pliny's mythical herdsman — copied from Nicander — the hobnails of whose brogues and the point of whose staff
' Whewell thus renders the passage (" Hist. Ind. Sc", 1859, Vol. II, page 218): " Other learned men have, in long navigations, observed the differences of magnetic variations, as Thomas Hariot, Robert Hues, Edward Wright, Abraham Kendall, all Englishmen: others have invented magnetic instruments and convenient modes of observation, such as are requisite for those who take long voyages, as William Borough in his Book concerning the variation of the compass, William Barlo in his Supplement, Robert Norman in his 'New At- tractive.' This is that Robert Norman (a good seaman and an ingenious artificer) who first discovered the dip of magnetic iron." This important dis- covery was made in 1576 (" Enc. Met.", page 738). Read paragraph 366 of J. F. W. Herschel's "Prelim. Disc", 1855.
1 6 ■ WILLIAM GILBERT.
were held fast in a magnetic region while he was pasturing his cattle), or after the district Magnesia in Macedonia/ abound- ing in loadstones ; or after the City of Magnesia in Ionia of Asia Minor, on the river Maender ; hence Lucretius writes, Quern Magneta vacant patrio de nomine Graii, Magnetum quia sit patriis in montibus ortus^ It is called Heracleus from the City Heraclea,^ or after that unconquerable hero Hercules, because of its great strength and its power and dominion over iron which is thesubduer of all things; it is also called Sideritis, as though one should say Ferrarius {Ferrarius lapis — iron- stone). It was not unknown to the earliest writers, whether among the Greeks, as Hippocrates and others, or (as I believe) among the Jews and the Egyptians ; for in the most ancient iron mines, in particular the most famous mines of Asia, the loadstone, brother uterine of iron, was oft dug out in company with that ore. And if those things be true which are told
' Magnesia. Many authors erroneously allude to a city or town called Magnesia — in the country of Magnesia — in Thessaly, one of the number being the learned Dr. W. Smith, who further states (" Diet, of Greek and Roman Geogr.", 1857, Vol. II, page 1170) that the Thessalian Magnetes — Magnesians — are said to have founded both the Ionian and the Lydian Magnesias. The celebrated historian Barthold George Niebuhr, in his " Lectures on Ancient Ethnography and Geography," states (transl. of Dr. L. Schmitz, London 1853, Vol. I, page 168) that the "town of Magnesia never existed, it is a mere blun- der, . . . not mentioned by either Scylax, Herodotus, or Demosthenes," and, furthermore, that the province of Magnesia was governed by the Macedonians, and that it is not probable it was ever incorporated by the Romans with either Thessaly or Macedonia.
'^ Transl. — Which the Greeks call magnetes, from the name of its country, for it had its origin in the native hills of the Magnesians.
' Heraclea, a town of uncertain site in Lydia, perhaps not far from (the Lydian) Magnesia at the foot of Mount Sipylus {ad Sipylum) (Dr. W. Smith, "Diet, of Greek and Roman Geogr.", 1857, Vol. I, page 1049). Gilbert has alluded to the celebrated Magnesia in Ionia {ad Maendrum), but it is uncertain which of the two Magnesias is really meant (Ninth " Encycl. Brit.", Vol. XV, page 219, note). At page 470, Vol. VI, of the " Diet. Geogr. Univ.", Paris 1829, it is said that it was the Magnesia ad Sipylum — Manika-Mansa — which gave its name to the Magnes, and this view is taken by many authors.
THE LOADSTONE: WHAT IT IS: ITS DISCOVERY. 1 7
about the people of China, neither were they in primitive times ignorant of magnetic experiments, for even in their country are seen the most excellent magnets in the world. The Egyptians, as Manetho relates, give it the name of ' the bone of Horus,' calling the potency that presides over the revolution of the sun Horus, as the Greeks called it Apollo. But later, as Plato declares, Euripides gave to it the name magnet. It is mentioned and praised by Plato in the lo, by Nicander of Colophon, Theophrastus, Dioscorides, Pliny, Soli- nus, Ptolemy, Galen, and other investigators of nature. But considering tbe great differences of loadstones, their dissim- ilitude in hardness, softness, heaviness, lightness, density, firmness, friableness : in color and in all other qualities ; these writers have not handed down any sufiEicient account of it. The history of the magnet was overlooked by them, or, if written, was incompletely given, because in olden time objects of many kinds and foreign products never before seen were not brought in by traders and mariners as they are wont to be brought in now, when all manner of commodities — stones, woods, spices, herbs, metals, and metallic wares — are eagerly sought for all over the earth ; neither was mining carried on everywhere in early times as it is now.
The difference between loadstones rests on their respective power : hence one loadstone is male, another female : so the ancients were wont to distinguish many objects of the same species. Phny quotes from Sotacus five kinds, viz. : the load- stones of Ethiopia, Macedonia, Boeotia, Troas, and Asia, re- spectively, which were the chief sorts known to the ancients.'
> Porta has it: "The Ethiopian, the Magnesian from Magnesia near Macedonia, as the way lies to the Lake Boebis, on the right hand; the third in Echium of Boetia, the fourth about Alexandria at Troaderum; the fifth in Magnesia of Asia" ("Nat. Mag.," Book VII, Chap. I).
lo WILLIAM GILBERT.
But we recognize as many kinds as there are in the whole world regions differing in soil ; for in every clime, in every province, in all kinds of land, either the loadstone is found or lies un- known because of its deep site or its inaccessible situation ; or, because of its weaker and less potent virtues, it is not recog- nized by us the while we see it and touch it.'
For the ancients, the differences were based on the color : The magnets from Magnesia in Macedonia were red and black, those from Boeotia red rather than black, those from the Troad black without strength, those from Asian Magnesia white, without power of attracting iron, and resembling pumice. A strong loadstone and one that under experiment demonstrates its power, nowadays generally resembles unpolished iron and usually is found in iron mines : sometimes it is found also form- ing a continuous vein by itself; such loadstones are imported from the East Indies, China, and Bengal, and they are of the color of iron, or of a dark blood-red or liver color. These are the most excellent and often are of great size and weight, as if broken off a great rock ; or again they are as if complete in themselves. Some of these, though they may weigh but one pound, will lift 4 ounces, or half a pound, or even an entire pound of iron. In Arabia are found red loadstones shaped like tiles, not as heavy as those imported from China, yet strong and good. Rather black loadstones are found in Ilva, an island of the Etrurian sea ; with these occur also white loadstones like those from the mines of Caravaca in Spain : but they are of inferior strength. Black loadstones also are found, and these, too, are rather inferior in strength, for example, those met with in the iron mines of Norway and in the coast region
' Consult Johann S. T. Gehler's " Physikalisches Worterbuch," article " Magnetismus."
THE LOADSTONE: WHAT IT IS: ITS DISCOVERY. 1 9
along the Cattegat. Blue-black and dusky-blue loadstones are likewise powerful and highly prized.' But there are others of a lead color, fissile or not fissile, that can be split up like slate ; I have also loadstones resembling an ashy-gray marble, mottled like gray marble : these take a high polish. In Germany, are loadstones perforated like the honeycomb : these are lighter than the other sorts, yet they are powerful. The metallic load- stones are those which are smelted into the best of iron ; the rest are not easily smelted, but are burnt.
There are loadstones that are very heavy, as there are others very light ; some are very powerful and carry masses of iron ; others are weaker and less powerful ; some so faint and void of strength that they can hardly attract ever so small a piece of iron, nor do they repel an opposite magnetized body. Others are firm and tough, nor are they easy to work ; others are fri- able. Again, some are dense and hard Hke corundum, or light or soft like pumice; porous or solid ; smooth and uniform, or irregular and corroded. Now hard as iron, nay sometimes harder to cut or to file than iron ; again as soft as clay. Not all magnets can properly be called stones : some there are that represent rather rocks ; others are rather metallic ores ; others are like clods of earth. So do they vary and differ from one another, and some possess more, others less, of the peculiar magnetic virtue. For they differ according to the nature of the soil, and the different mixtures of clays and humors ; ac- cording to the lie of the land and the decay of this highest substance born to Earth : decay due to the concurrence of many
' "They are proved to be the best which are most of blewe or heavenly- colour " (Taisnier, Z>^ A^a^wrrt, 1562, Eden tr. p. ii). — "It is certain, that the bluer they are, the better they are " (Porta, "Natural Magick," 1658, Chap. VII, page 191). Consult Epistola P. Peregrini De Magnete, Cap. Ill, and Barthol. de Glanvil, Lib. de Prop., Lyons 1480, fol.. Lib. XVI, Cao. LXII.
20 WILLIAM GILBERT.
causes and the never-ceasing vicissitude of rise and decline and the mutations of bodies. Nor is this stone, endowed as it is with such power, a rarity : there is no country wherein it may not be found in one form or other. But were men to seek it more dihgently and at greater expense, and could they in the face of difficulties mine it, it might be obtained everywhere, as later we will prove. In many regions are found and are now opened mines of powerful loadstones unknown to ancient authors, in Germany, for example, where none of them ever said that loadstones were mined ; and yet since the time within the memory of our fathers when the business of mining began there to be developed, in many parts of Germany powerful loadstones of great virtues have been taken out of the earth, as in the Black Forest near Helceburg : in Mt. Misena not far from Schwarzberg ; some of considerable strength from the region betwixt Schneeberg and Annaberg in the Joachimsthal, as was observed by Cordus ; also near Pela in Franconia ; in Bohemia from the iron mines near Lesse ; and in other places, as we are informed by Georgius Agricola and other men learned in the art of mining. The like is to be said of other countries in our time ; for this stone, famous for its virtues, as to-day it is well known throughout the world, so is produced in every land ; it is, so to speak, a native of all countries. In East India, in China, in Bengal, along the banks of the Indus, it is plenti- ful, also in certain marine rocks ; in Persia, too, in Arabia and the isles of the Red Sea ; in many parts of Ethiopia, as was anciently Zimiri, mentioned by Pliny ; in Asia Minor around Alexandria, Boeotia, Italy, the island Elba, Barbary ; in Spain, still in many localities as of old ; in England quite recently a vast quantity was found in a mine owned by a gentleman, named Adrian Gilbert, as also in Devonshire and in the Forest of Dean ; in Ireland too, in Norway, Denmark, Sweden, Lapland.
THE LOADSTONE: WHAT IT IS: ITS DISCOVERY. 21
Livonia, Prussia, Poland, Hungary/ For albeit the terrestrial globe, various humors and diversities of soils being produced by the perpetual vicissitude of generation and decay, is ever to a greater and greater depth beneath the surface in the lapse of ages efflorescing, and is being clothed as it were with a diversi- fied and perishable covering and wrappage ; still from its in- terior arises in many places a progeny nigher to the more per- fect bbdy, and makes its way into the sunlit air. But the weak loadstones and those of less strength, which thus have been deprived of their virtue by being soaked v»^ith humors, are visible everywhere, in every country-side ; great masses of these are to be found in every quarter, without tunnelling mountains or sinking mines, and without any of the toils and difficulties of mining, as we will show in the sequel. These we will so manipulate according to a simple process, that their languid and dormant properties shall be made manifest.
The magnet is called by the Greeks 'HpocKXeioZ, as by Theo- phrastus, and Mayvf/ris and Mayvijs, as by Euripides, quoted by Plato in the lo; by Orpheus it is called also MayvT^ocra and 2idrjpitr)Z {quasi ironstone) ; by the Latins it is called Magnes Herculeus ; by the French Aimant, a corruption of adamas ; hy the SpsLniards Ptedramanf ; by the Italians Calamita ; by the English XoabStOne an& HC)amant stone; by the Germans Magness and Siegelstein. Among the English, French, and Spaniards, it has its common name from adamas, and this is probably because at some time those people were led astray by the term siderites, which was applied both to the diamond and the magnet.^ The magnet is called ^idrjpitij's because
' "The most powerful native magnets are found in Siberia, and in the Hartz; they are also obtainable on the Island of Elba " (Dana). See Gilbert, Book IV, Chap. V.
* Consult Vincentii Burgundi, Spec. Mai., Douai ed. 1624, T. I, LVIII, C. 34, 39-41; Alb. Magnus, De Mineral., Op. T. II, Lione 1651, Tr. II, C. I.
22 WILLIAM GILBERT.
of its property of attracting iron ; and the diamond is called 2i6rfpiTT/5 from the glistening of polished iron- Aristotle merely names the loadstone in his work De Anima, I. : "Eoiks 6e Kai ©aXfjS e^ d)v oc7iojj.vejxovevov(Tif Kivr/riKOv n rrfv ipvx^y iTtoXafx^aveiv, eirtep rov Xidov ipvx'ijy e(prf exeiv^ on tor cridr/pov Kivet. (Thales, too, seems, from what they relate, to regard the soul as somewhat producing motion, for he said that this stone has a soul, since it moves iron.) The name magnet is also given to another stone differing widely from the siderites, and having the look of silver: in its nature this stone resembles amianth (asbestus), and in form differs from that inasmuch as it consists, like mica, of laminae ; the Germans call it Katsensilber and Talk.
CHAPTER III.
THE LOADSTONE POSSESSES PARTS DIFFERING IN THEIR NAT- URAL POWERS, AND HAS POLES CONSPICUOUS FOR THEIR PROPERTIES.
The many qualities exhibited by the loadstone itself, qualities hitherto recognized yet not well investigated, are to be pointed out in the first place, to the end the student may understand the powers of the loadstone and of iron, and not be confused through want of knowledge at the threshold of the arguments and demonstrations. In the heavens, astrono- mers give to each moving sphere two poles ; thus do we find
page 227, and C. XI, page 233; C. G. Solino, Exercitationes Plin., Rhenuni 1689, page log. The Macedonian diamond, as well as the adamas cyprius and siderites, were obviously not dianaonds, but soft stones (Thomson, " Hist, of Chem.", 1830, Vol. I, page 98).
QUALITIES OF THE LOADSTONE. 2$
two natural poles of excelling importance even in our terres- trial globe, constant points related to the movement of its daily revolution, to wit, one pole pointing to Arctos (Ursa) and the north ; the other looking toward the opposite part of the heavens. In like manner the loadstone has from nature its two poles, a northern and a southern ; fixed, definite points in the stone, which are the primary termini of the movements and effects, and the limits and regulators of the several actions and properties. It is to be understood, however, that not from a mathematical point does the force of the stone emanate, but from the parts themselves ; and all these parts in the whole — while they belong to the whole — the nearer they are to the poles of the stone the stronger virtues do they acquire and pour out on other bodies. These poles look toward the poles of the earth, and move toward them, and are subject to them. The magnetic poles may be found in every loadstone, whether strong and powerful (male, as the term was in antiquity) or faint, weak, and female ; whether its shape is due to design or to chance, and whether it be long, or flat, or four-square, or three-cornered, or polished ; whether it be rough, broken-off, or unpolished : the loadstone ever has and ever shows its poles. * But inasmuch as the spherical form, which, too, is the most perfect, agrees best with the earth, which is a globe, and also is the form best suited for experimental uses, therefore we pur- pose to give our principal demonstrations with the aid of a globe-shaped loadstone, as being the best and the most fitting. Take then a strong loadstone, solid, of convenient size, uni- form, hard, without flaw ; on a lathe, such as is used in turning crystals and some precious stones, or on any like instrument (as the nature and toughness of the stone may require, for often it is worked only with difficulty), give the loadstone the form of a ball. The stone thus prepared is a true homogeneous ojff-
24 WILLIAM GILBERT.
spring of the earth and is of the same shape, having got from art the orbicular form that nature in the beginning gave to the earth, the common mother ; and it is a natural little body en- dowed with a multitude of properties whereby many abstruse and unheeded truths of philosophy, hid in deplorable dark- ness, may be more readily brought to the knowledge of man- kind. To this round stone we give the name MiKpoyr} (microge) or Terrella (earthkin, little earth).'
To find, then, poles answering to the earth's poles, take in your hand the round stone, and lay on it a needle or a piece of iron wire : the ends of the wire move round their middle point, and suddenly come to a standstill. Now, with ochre or with chalk, mark where the wire lies still and sticks. Then move the middle or centre of the wire to another spot, and so to a third and a fourth, always marking the stone along the length of the wire where it stands still : the lines so marked will ex- hibit meridian circles, or circles like meridians on the stone or terrella ; and manifestly they will all come together at the poles of the stone. The circles being continued in this way, the poles appear, both the north and the south, and betwixt these, midway, we may draw a large circle for an equator, as is done by the astronomer in the heavens and on his spheres and by the geographer on the terrestrial globe ; for the line so drawn on this our terrella is also of much utility in our demonstrations and our magnetic experiments. Poles are also found in the round stone, in a versorium, in a piece of iron touched with a loadstone and resting on a needle or point (attached at its base to the terrella), so that it can freely revolve, as in the figure.
1 Sir Kenelm Digby, "A Treatise of Bodies," London 1645, Chap. XX, page 225.
QUALITIES OF THE LOADSTONE.
25
On top of the stone AB is set the versorium in such a way that its pointer may remain in equihbrium : mark with chalk the direction of the pointer when at rest. Then move the instrument to another spot and again mark the direction in which the pointer looks ; repeat this many times at many different points and you will, from the convergence of the lines of direction, find one pole at the point A, the other at B, A pointer also indicates the true pole if brought near to
the stone, for it eagerly faces the stone at right angles, and seeks the pole itself direct and turns on its axis in a right line toward the centre of the stone. Thus the pointer D* regards A and F, the pole and the centre, but the pointer E looks not straight either toward the pole A or the centre F. A bit of fine iron wire as long as a barley-corn is laid on the stone and is moved over the zones and the surface of the stone till it stands perpendicularly erect ; for at the poles, whether N. or S., it stands erect ; but the farther it is from the poles (towards the equator) the more it inclines. The poles thus found, you are to mark with a sharp file or a gimlet.
^ WILLIAM GILBERT.
%
CHAPTER IV.
WHICH POLE IS THE NORTH : HOW THE NORTH POLE IS DISTINGUISHED FROM THE SOUTH POLE.
One of the earth's poles is turned toward Cynosura and steadily regards a fixed point in the heavens (save that it is unmoved by the precession of the fixed stars in longitude, which movement we recognize in the earth, as we shall later show) ; the other pole is turned toward the opposite aspect of the heavens, an aspect unknown to the ancients, but which is adorned with a multitude of stars, and is itself a striking spec- tacle for those who make long voyages. So, too, the loadstone possesses the virtue and power of directing itself toward the north and the south (the earth itself co-operating and giving to it that power) according to the conformation of nature, which adjusts the movements of the stone to its true locations. In this manner it is demonstrated : Put the magnetic stone (after you have found the poles) in a round wooden vessel — a bowl or a dish ; then put the vessel holding the magnet (like a boat with a sailor in it) in a tub of water or a cistern where it may float freely in the middle without touching the rim, and where the air is not stirred by winds (currents) which might interfere with the natural movement of the stone : there the stone, as if in a boat floating in the middle of an unruflfled surface of still water, will straightway set itself, and the vessel containing it in motion, and will turn in a circle till its south pole shall face north and its north pole, south. For, from a contrary position, it returns to the poles ; and though with its
WHICH POLE IS THE NORTH. ^7
first too strong impetus it passes beyond, still, as it comes back again and again, at last it rests at the poles or in the meridian (save that, according to the place, it diverges a very little from those points, or from the meridional line, the cause of which we will define later). As often as you move it out of its place, so often, by reason of the extraordinary power with which nature has endowed it, does it seek again its fixed and determinate points. Nor does this occur only when the poles of the loadstone in the float are made to lie evenly in the plane of the horizon ; it takes place also even though one pole, whether north or south, be raised or depressed lo, 20, 30, 40, or 80 degrees from the plane of the horizon ; you shall see the north part of the stone seek the south, and the south part the north ; so that if the pole of the stone be but one degree from the zenith and the centre of the heavens, the whole stone re- volves until the pole finds its own place ; and though the pole does not point exactly to its seat, yet it will incline toward it, and will come to rest in the meridian of its true direction. And it moves with the same impetus whether the north pole be directed toward the upper heavens, or whether the south pole be raised above the horizon. Yet it must always be borne in mind that though there are manifold differences be- tween stones, and one far surpasses another in virtue and effi- ciency, still all loadstones'have the same limits and turn to the same points. Further, it is to be remembered that all who hitherto have written about the poles of the loadstone, all in-* strument-makers, and navigators, are egregiously mistaken in taking for the north pole of the loadstone the part of the stone that inclines to the north, and for the south pole the part that looks to the south : this we will hereafter prove to be an error. So ill-cultivated is the whole philosophy of the magnet still, even as regards its elementary principles.
28 WILLIAM GILBERT.
CHAPTER V.
ONE LOADSTONE APPEARS TO ATTRACT ANOTHER IN THE NATURAL POSITION ; BUT IN THE OPPOSITE POSITION REPELS IT AND BRINGS IT TO RIGHTS.
First we have to describe in popular language the potent and familiar properties of the stone ; afterward, very many- subtile properties, as yet recondite and unknown, being in- volved in obscurities, are to be unfolded ; and the causes of all these (nature's secrets being unlocked) are in their place to be demonstrated in fitting words and with the aid of apparatus. The fact is trite and familiar, that the loadstone attracts iron ; in the same way, too, one loadstone attracts another. Take the stone on which you have designated the poles, N. and S., and put it in its vessel so that it may float ; let the poles he just in the plane of the horizon, or at least in a plane not very obhque to it ; take in your hand another stone the poles of which are also known, and hold it so that its south pole shall he toward the north pole of the floating stone, and near it alongside ; the floating loadstone wiU straightway follow the other (provided it be within the range and dominion of its powers), nor does it cease to move nor does it quit the other till it clings to it, unless, by moving your hand away, you man- age skilfully to prevent the conjunction. In like manner, if you oppose the north pole of the stone in your hand to the south pole of the floating one, they come together and follow each other. For opposite poles attract opposite poles. But, now, if in the same way you present N. to N. or S. to S., one
ONE LOADSTONE APPEARS TO ATTRACT ANOTHER.
29
stone repels the other ; and as though a helmsman were bear- ing on the rudder it is off like a vessel making all sail, nor stands nor stays as long as the other stone pursues. One stone also will range the other, turn the other around, bring it to right about and make it come to agreement with itself. But when the two come together and are conjoined in nature's order, they cohere firmly. For example, if you present the north pole of the stone in your hand to the Tropic of Capri-
corn (for so we may distinguish with mathematical circles the round stone or terrella, just as we do the globe itself) or to any point between the equator and the south pole : immedi- ately the floating stone turns round and so places itself that its south pole touches the north pole of the other and is most closely joined to it. In the same way you will get like effect at the other side of the equator by presenting pole to pole ; and thus by art and contrivance we exhibit attraction and re- pulsion, and motion in a circle toward the concordant position, and the same movements to avoid hostile meetings. Further- more, in one same stone we are thus able to demonstrate all
30 WILLIAM GILBERT.
this: but also we are able to show how the self-same part of one stone may by division become either north or south. Take the oblong stone ad in which a is the north pole and d the south. Cut the stone in two equal parts, and put part a in a. vessel and let it float in water.
You will find that a, the north point, will turn to the south as before ; and in like manner the point d will move to the north, in the divided stone, as before division. But 6 and c, before connected, now separated from each other, are not what they were before. 3 is now south while c is north. d attracts c, longing for union and for restoration of the original continuity. They are two stones made out of one, and on that account the c of one turning toward the d of the other, they are mutually attracted, and, being freed from all impediments and from their own weight, borne as they are on the surface of the water, they come together and into con- junction. But if you bring the part or point a up to c of the other, they repel one another and turn away ; for by such a position of the parts nature is crossed and the form of the stone is perverted : but nature observes strictly the laws it has imposed upon bodies: hence the flight of one part from the undue position of the other, and hence the discord un- less everything is arranged exactly according to nature. And nature will not suffer an unjust and inequitable peace, or an unju?^ and inequitable peace and agreement, but makes war and employs force to make bodies acquiesce fairly and justly. Hence, when rightly arranged, the parts attract each other, i.e., both stones, the weaker and the stronger, come together and with all their might tend to union : a fact manifest in all loadstones, and not, as Pliny supposed, only in those from Ethiopia. The Ethiopic stones if strong, and those brought from China, which are all powerful stones, show the effect
THE LOADSTONE ATTRACTS IRON ORE. 3 1
most quickly and most plainly, attract with most force in the parts nighest the pole, and keep turning till pole looks straight on pole. The pole of a stone has strongest attraction for that part of another stone which answers to it (the adverse as it is called) ; e.g., the north pole of one has strongest attrac- tion for, has the most vigorous pull on, the south part of another: so too it attracts iron more powerfully, and iron clings to it more firmly, whether previously magnetized or not. Thus it has been settled by nature, not without rea- son, that the parts nigher the pole shall have the greatest attractive force ; and that in the pole itself shall be the seat, the throne as it were, of a high and splendid power ; and that magnetic bodies brought near thereto shall be attracted most powerfully and relinquished with most reluctance. So, too, the poles are readiest to spurn and drive away what is pre- sented to them amiss, and what is inconformable and foreign.*
CHAPTER VI.
THE LOADSTONE ATTRACTS IRON ORE AS WELL AS THE SMELTED METAL.
The most potent virtue of the loadstone and the one^ valued by the ancients is the attraction for iron ; for Plato mentions that the magnet, so called by Euripides, draws to itself iron, and not only attracts iron rings but also endows them with the power of doing as the stone itself, to wit, of attracting other rings, and that thus sometimes a long chain of iron objects, as nails, or rings, is made, the several parts hang-
^ Dr. J. Lamont's " Handbuch des Magnetisniius," Leipzig 1867, page 15.
32 WILLIAM GILBERT.
ing from one another. The best iron (such as that which from its uses is called acies, and from the country of the Chalybes, chalybs) is most readily and strongly attracted by a good magnet ; ' but inferior iron, iron that is impure, rusty, not well purged of dross, and not worked over in the second furnace is attracted more weakly ; and any iron is more faintly attracted if covered and smeared with thick, greasy, tenacious fluids. The loadstone also attracts iron ores— rich ores and those of the color of iron ; poor ores and those without much pure metal it does not attract unless they receive special treatment. The loadstone loses some part of its attractive power, and, as it were, enters on the decline of old age, if it be too long exposed in open air and not kept in a case, with a covering of iron filings or iron scales : hence it must be packed in such material. Nothing withstands this unimpairable virtue, except what destroys the form of the body or corrodes it ; no, not a thousand adamants made into one. Nor do I believe in the theamedes, or that it has a power the opposite of the loadstone's,' albeit Pliny, that eminent author and best of compilers (for he has handed down to posterity the observa- tions and discoveries of others and not always or mainly his
1 See Aristotle's reference to the iron of the Chalybes at page 20. Dr. Thomson informs us the general opinion of the ancients was that the method of smelting iron ore had been brought to perfection by the Chalybes, a small nation located near the Black Sea (Xenophon's Anabasis, V. 5), and that the name chalybs, occasionally used for steel, was derived from that people. Porta, at Book XIII, Chap. I, of his " Natural Magick," says: " Justine, the historian, reports that in Gallicia of Spain, the chiefest matter for iron is found, .... and there is no weapon approved amongst them that is not made of the River Bib- ilis, or tempered with the water of Chalybes. And hence are those people that live neer this River called. Chalybes; and they are held to have the best iron. Yet Strabo saith that the Chalybes were people in Pontus near the River Ther- modon." See Gilbert, Book I, Chap. VIII.
'■" " Iron is attracted by the magnet and repelled by another stone, the the- avtddes" (Pliny, Hist. Nat., XX, i). See, likewise, Cardan, De Subtil., Norimb. 1600, folio, Lib. VII, page 386.
WHAT IRON- IS; WHAT ITS MATTER; ITS USE. 33
own), copies out of other writers the theamedes fable, now from repetition become a familiar story among the moderns. The story is that in India are two mountains near the river Indus, and that one of them — consisting of loadstone — pos- sesses the power of holding everything containing iron ; while the other, consisting of theamedes, repels the same. Hence if you should have iron nails in the soles of your shoes, it would be impossible to lift your foot if you were standing on one of the mountains, and impossible to stand on the other at all. Albertus Magnus writes that in his time a loadstone was found that on one side drew iron to itself and on the other side repelled it.' But Albertus's observation was faulty, for every loadstone attracts on one side magnetized iron, on the other repels, and attracts magnetized iron more powerfully than non-magnetized.
CHAPTER VII.
WHAT IRON IS; WHAT ITS MATTER; ITS USE.
Having declared the origin and nature of the loadstone, we hold it needful first to give the history of iron also, and to point out properties of iron as yet not known, before we come to the exphcation of difificulties connected with the loadstone,
' Somewhat in this connection, Gilbert has already (Book I, Chap. I) alluded to Albertus Magnus, of whom mention was inade in note i, page 9. In his De Miner alibus — Lyons ed. 1651, Treat. Ill, Lib. II, Cap. VI, p. 243 — Albertus says, " One angle ... is to the zoron (north), . . . but another angle of the magnet opposite to it attracts to the aphron (south)." Consult Cardan, De Subtil., Lugduni 1663; Salmanasar, Book II ("Of the Egyptian Hermitus, 19 stars, and 15 stones, and 15 herbs, and 15 figures"), " On one side (the magnet) attracts iron, on the other repels it;" Pietro d'Abano, Conciliator Differentia- rum Mantuse, 1472, Diff. 51, page 104, "Know that a magnet is discovered which attracts iron on one side and repels it on the other."
34 WILLIAM GILBERT.
and to the demonstrations ; before we come to the consider- ation of its uniting and according with iron. Iron is, by all, classed among metals ; it is of bluish color, very hard, grows red hot before fusion, is very hard to fuse, spreads under the hammer, and is resonant. Chemists say that, if fixed earthy sulphur be combined with fixed earthy mercury and these two bodies present not a pure white but a bluish-white color, if the sulphur prevail, iron results. For those hard masters of the metals, who in many various processes put them to the tor- ture, by crushing, calcining, smelting, subliming, precipitating, distinguish this, on account both of the earthy sulphur and the earthy mercury, as more truly the child of earth than any other metal ; for neither gold, nor silver, nor lead, nor tin, nor even copper do they hold to be so earthy ; and therefore it is treated only in the hottest furnaces with the help of bellows* and when thus smelted if it becomes hard again it cannot be smelted once more without great labor ; and its slag can be fused only with the utmost difificulty. It is the hardest of metals, subduing and breaking them all, because of the strong concretion of the more earthy substance. Hence we shall better understand what iron is when we shall have developed, in a way different from that of those who have gone before us, what are the causes and the matter of metals. Aristotle sup- poses their matter to be an exhalation. The chemists in chorus (unison) declare that sulphur and quicksilver are the prime elements. Gilgil, the Mauretanian, holds the prime ele- ment to be ash moistened with water ; Georgius Agricola, a mixture of water with earth ; and his opinion differs nought from Gilgil's thesis. But our opinion is that metals have their origin and do effloresce in the uppermost parts of the globe, each distinct by its form, as do many other minerals and all the bodies around us. The globe of the earth is not made of
WHAT IRON IS; WHAT ITS MATTER ; ITS USE. 35
ash or of inert dust. Nor is fresh water an element, but only a less complex consistence of the earth's evaporated fluids. Unctuous bodies {^pinguia corpora), fresh water void of proper- ties, quicksilver, sulphur : these are not the principles of the metals : they are results of another natural process ; nor have they a place now or have they had ever, in the process of producing metals. The earth gives forth sundry humors, not produced from water nor from dry earth, nor from mixtures of. these, but from the matter of the earth itself : these are not distinguished by opposite qualities or substances. Nor is the earth a simple substance, as the Peripatetics imagine. The humors come from sublimed vapors that have their origin in the bowels of the earth. And all waters are extractions from the earth and exudations, as it were. Therefore Aristotle is partly in the right when he says that the exhalation which condenses in the earth's veins is the prime matter of metals : for exhalations are condensed in situations less warm than the place of their origin, and owing to the structure of lands and mountains, they are in due time condensed, as it were, in wombs, and changed into metals. But they do not of them- selves alone constitute the veins of ore ; only they flow into and coalesce with solider matter and form metals. When, therefore, this concreted matter has settled in more temperate cavities, in these moderately warm spaces it takes shape, just as in the warm uterus the seed or the embryo grows. Some- times the exhalation coalesces only with matter homogene- ous throughout, and hence some metals are now and then but not often obtained pure and not needing to be smelted. But other exhalations, being mixed with foreign earths, must be smelted ; and thus are treated the ores of all metals, which are freed from all their dross by the action of fire ; when smelted into the metallic state they are fluid and then are freed from
36 WILLIAM GILBERT.
earthly impurities but not from the true substance of the earth. But that there is gold, or silver, or copper, or that any other metals exist, does not happen from any quantitas or propor- tion of matter nor by any specific virtues of matter, as the chemists fondly imagine ; but it happens when, earth cavities and the conformation of the ground concurring with the fit matter, those metals take from universal nature the forms by which they are perfected, just as in the case of all other min- erals, all plants and all animals : else the kinds of metals would be vague and undefined : in fact the varieties are very few^ hardly ten in number. But why nature should be so grudging in the number of metals, or why there should be even so many metals as are recognized by man, were not easy to explain, though simpletons and raving astrologers refer to the several planets their respective metals.' But neither do the planets agree with the metals nor the metals with the planets, either in number or in properties. For what is common be- tween Mars and iron, save that, like many other implements, swords and artillery are made of iron ? What has copper to do with Venus? Or how does tin, or zinc, relate to Jupiter? These were better dedicated to Venus. But a truce to old wives' talk. Thus exhalations are the remote cause of the generation of metals ; the proximate cause is the fluid from the exhalations : like the blood and the semen in the generation of animals. But these exhalations and the fluids produced from
' In his account of Geber (Abou-Moussah-Dschafar-Al-Soli), " the patri- arch of chemistry," Dr. Thos. Thomson says this Arabian philosopher was acquainted with the metals gold, silver, copper, iron, tin, and lead, and that they are usually distinguished by him under the respective names of Sol, Luna, Venus, Mars, Jupiter, and Saturn. He adds : "Whether these names of the planets were applied to the metals by Geber, or only by his translators, I can- not say; but they were always employed by the Alchy mists, who never desig- nated the metals by any other appellations" ("Hist, of Chem.", 1830, Vol. I, pages 117, 118).
WHAT IRON IS; WHAT ITS MATTER; ITS USE. 37
them enter bodies often and change them into marchasites' and they pass into veins (we find many instances of timber so transformed), into appropriate matrices within bodies, and these metals are formed ; oftenest they enter the more interior and more homogeneous matter of the globe, and in time there re- sults a vein of iron, or loadstone is produced, which is nothing but a noble iron ore ; and for this reason and also on account of its matter being quite pecuhar and distinct from that of all other metals, nature very seldom or never mingles with iron any other metal, though the other metals are very often commin- gled in some small proportion and are produced together. Now, when these exhalations or fluids happen to meet efflo- rescences altered from the homogeneous matter of the globe — sundry precipitates, and salts, in suitable matrices (operant forms) — the other metals are produced (a specificating nature operating in that place). For within the globe are hidden the principles of metals and stones, as at the earth's surface are hidden the principles of herbs and plants. And earth dug from the bottom of a deep pit, where there appears to be no chance of any seed being formed, produces, if strewn on the top of a very high tower, green herbage and unbidden grasses, the sun and the sky brooding over earth ; the earth regions produce those things which in each are spontaneous ; each region pro- duces its own peculiar herbs and plants, its own metals.
Do you not see how Tmolus sends fragrant saflfron, India its ivory, the Sabaens their frankincense, the naked Chalybes iron, Pontus the malodorous castor, Epirus the mares that have won at Olympia? (Virgil ius, Georgica, Book I, pages 56-59.)
' Marchasites, marcasites — the crystallized form of iron pyrites. What substance Geber designated by the name cf marchasite (fire-stone, as Porta calls it — " Nat. Magick," Book V, Chap. IV) is not known to Dr. Thomson, who suspects it to have been a sulphide of antimony long in common use through- out Asia.
38 WILLIAM GILBERT.
What the chemists (as Geber and others) call the fixed earthy sulphur in iron, is nothing else but the homogenic mat- ter of the globe held together by its own humor, hardened by a second humor : with a minute quantity of earth-substance not lacking humor is introduced the metallic humor. Hence it is said very incorrectly by many authors that in gold is pure earth, in iron impure ; as though natural earth and the globe itself were become in some incomprehensible sense impure. In iron, especially in best iron, is earth in its true and genuine nature. In the other metals is not so much earth as, instead of earth and precipitate, condensed and (so to speak) fixed salts, which are efiflorescences of the Earth, and which also dif- fer in firmness and consistence. In mines they ascend in great volume, with double humor from the exhalations ; in the sub- terranean spaces they are consolidated into metallic ores ; so too they are produced together, and in virtue of their place and of the surrounding bodies, they acquire, in natural matrices, their specific forms. Of the various bodily constitutions of loadstones, their different substances, colors, and properties, we have spoken before : but now after having declared the cause and origin of metals, the matter of iron, not in the smelted metal but in the ore from which that is obtained by smelting, has to be examined. Iron, that from its color appears pure, is found in the earth ; yet it is not exactly metallic iron, not quite suitable for the different uses of iron. Sometimes it is found covered with a white moss-like substance, or with a coat- ing of other stones. Such ore is often seen in the sands of rivers : such is the ore from Noricum (the region south of the Danube, watered by the Inn \CEnus\ and the Drave \Drau\ ; mostly comprised in the modern Austria). Iron ore, nearly pure, is often mined in Ireland : from this the smith, without the labor of the furnace, forges in his shop iron implements.
WHAT IRON IS; WHAT ITS MATTER; ITS USE. 39
From an ore of liver color is very often obtained in France an iron with bright scales {bractecs) ' ; such iron is made in England without the scales ; carpenters use it instead of chalk. In Sus- sex, in England, is a rich ore of dark, and one of pale ashy color ; both of these ores when made red hot for some time, or when kept in a moderate fire, take the color of liver : in Sussex also is a dark-colored ore in square masses, with a black rind of harder material. The liver-like ore is often mixed with other stones in various ways, as also with perfect loadstone, which yields the best iron. There is likewise rust-colored ore, ore of a lead color mixed with black, simply black, or black mixed with cobalt ; there is also an ore with admixture of pyrites or sterile plumbago. One kind of ore resembles jet, another the precious stone hcematites. The stone smiris (emery ; corundum) used by workers in glass for glass-cutting and called by the English emerelstone and by the Germans smear gel (schniergel), is of iron, albeit iron is smelted from it with difficulty ; it attracts an unmagnetized needle. It is often found in deep silver and iron mines. Thomas Erastus tells of having been informed by a certain learned man, of iron ores, in color resembling metallic iron, but quite soft and greasy, capable of being moulded with the fingers like butter ; we have seen ores of about the same kind that were found in England : they resemble Spanish soap. Besides the numberless forms of stony ores, there is a substance like iron rust deposited from ferriferous water : it is got from mud, loam, and from ochre. In England, a good deal of iron is obtained in the furnace from
1 At page 280, Vol. I, of Thomson's "Hist, of Chem.", London 1830, will be found an account of the difficulty experienced by Reaumur in removing the scales from the iron imported from Germany into France. Elsewhere, he tells us that the rust of iron and the scales of iron were used by the ancients as astringent medicines. See note at Book II, Chap. XXIII, of the present work.
40 WILLIAM GILBERT.
sand stones and clayey stones that appear to contain not so much iron as sand, marl, or other mud. In Aristotle's book De Adniirandis Narrationibus we read :
'Tis said the iron of the Chalybes and the Myseni has quite a peculiar origin, being carried in the gravel of the streams. Some say that, after being merely washed, it is smelted in the furnace ; others that is washed repeatedly, and as often the residue treated with fire in the furnace, together with the stone pyrimachus (a stone refractory to the action of fire), which occurs there in great abundance. Thus do many sorts of substances contain in themselves strikingly and most plentifully this ferric and telluric element. Many, too, and most plentiful in every soil are the stones and earths and the various bodies and compounds, which contain iron (though not in such abundance) and yield it in the furnace fire, but which are rejected by the metallurgist as not workable with profit ; and there are other earths that give evidence of the presence of iron in them ; these, being very poor in the metal, are not smelted at all, and not being esteemed they are not known.
The kinds of manufactured iron differ very much from one another. For one kind has great tenacity ; and that is the best. There is a medium kind. Another kind is brittle ; that is the worst. Sometimes the iron, on account of the ex- cellence of the ore, is made into steel ; as in Noricum at present. From the best iron also, worked over and over again, and purged of all impurities, or plunged red-hot into water, is produced what the Greeks call Gtojxwfxa^ and the Latins acies and aciarium (steel), and which is variously called Syrian, Parthian,
1 Stomoma was also the name given to an oxide of copper, which was gradually formed upon the surface of metal, when it was kept in a state of fusion. Such oxides of copper were used as external applications, seemingly as escharotics (Dr. Thomson's Chemistry, 1830, Vol. I, page 60).
WHAT IRON IS; WHAT ITS MATTER; ITS USE. 41
Norican, Comese and Spanish ; in other places it takes its name from the water in which it is repeatedly immersed, as at Como in Italy, and Bilbao and Tariassone in Spain. Steel sells at a far higher price than iron. And, on account of its superiority, it is in better accord with the magnet. It is often made from powerful loadstone, and it acquires the magnetic virtue readily, retains it a long time unimpaired and fit for all magnetic ex- periments.
The iron, after it has been smelted in the first furnace, is then treated with various processes in great forges or mills, the metal under mighty blows acquiring toughness, and dropping its impurities. When first smelted it is brittle and by no means perfect. Therefore, here in England, when great cannons are cast, in order that they may be able to withstand the explo- sive force of the ignited gunpowder, the metal is specially purged of impurities : while fluid it is made to pass a second time through a narrow opening, and thus is freed of recre- mental substances. Smiths, with the use of certain liquids and hammer-strokes, toughen the iron laminae from which are made shields and coats of mail not penetrable by any musket-ball. Iron is made harder by skill and tempering; but skill also makes it softer and as pliant as lead. It is made hard by cer- tain waters into which it is plunged at white heat, as in Spain. It is made soft again either by fire alone when, without ham- mering and without the use of water, it is allowed to grow cool ; or by being dipped in grease ; or it is variously tempered, to serve the purposes of the different arts, by being smeared with special preparations. This art is described by Baptista Porta in book 13 of the Magia Naturalis.
Thus is this ferric and telluric substance contained in and extracted from various kinds of stones, ores, and earths ; thus too does it differ in appearance, form, and efficiency ; and
42 WILLIAM GILBERT.
by various processes of art it is smelted and purified and made to serve man's uses in all sorts of trades and in all sorts of tools, as no other body can serve. One kind of iron is suitable for breastplates, another withstands cannon balls, another pro- tects against swords or the curved blades called cimetars ; one kind is used in making swords, another in forging horseshoes. Of iron are made nails, hinges, bolts, saws, keys, bars, doors, folding-doors, spades, rods, pitchforks, heckles, hooks, fish- spears, pots, tripods, anvils, hammers, wedges, chains, manacles fetters, hoes, mattocks, sickles, hooks for pruning vines and, for cutting rushes {scirpiculcE), shovels, hoes, weeding-hooks, ploughshares, forks, pans, ladles, spoons, roasting-spits, knives, daggers, swords, axes, Celtic and Gallic darts {gesscs), Mace- donian pikes {sarisscB)^ lances, spears, anchors and many nauti- cal implements ; furthermore, bullets, javelins, pikes, corselets, helmets, breastplates, horseshoes, greaves, wire, strings of mu- sical instruments, armchairs, portcullises, bows, catapults, and those pests of humanity, bombs, muskets, cannon-balls, and no end of implements unknown to the Latins. I have re- counted so many uses in order that the reader may know in how many ways this metal is employed. Its use exceeds that of all other metals a hundredfold ; it is smelted daily ; and there are in every village iron forges. For iron is foremost among metals and supplies many human needs, and they the most pressing : it is also far more abundant in the earth than the other metals, and it is predominant. Therefore it is a vain imagination of chemists to deem that nature's purpose is to change all metals to gold, that being brightest, heaviest, strong- est, as though she were invulnerable, would change all stones into diamonds because the diamond surpasses them all in brilliancy and in hardness. Iron ore, therefore, as also manu- factured iron, is a metal slightly different from the primordial
//V WHAT COUNTRIES IRON IS PRODUCED. 43
homogenic telluric body because of the metallic humor it has imbibed ; yet not so different but that in proportion as it is purified it takes in more and more of the magnetic virtues, and associates itself with that prepotent form and duly obeys the same.
CHAPTER VIII.
IN WHAT COUNTRIES AND REGIONS IRON IS PRODUCED.
Iron mines are very numerous everywhere — both the ancient mines mentioned by the earliest writers and the new and modern ones. The first and greatest were, I think, in Asia, for in the countries of Asia, which naturally abound in iron, government and the arts did most flourish ; and there were the things needful for man's use first discovered and sought for. It is related that iron existed in the neighborhood of Andria ; in the land of the Chalybes, on the banks of the river Thermodon in Pontus ; in the mountains of Palestine on the side toward Arabia ; in Carmania. In Africa, there was an iron mine in the island of Meroe. In Europe, iron was found in the hills of Britain, as Strabo writes ; in hither Spain, in Cantabria ; among the Petrocorii and the Cabi Bituriges in Gaul, were smithies in which iron was made. In Germany was a mine near Luna, mentioned by Ptolemy ; the Gothinian iron is spoken of by Cornelius Tacitus ; and the iron of Noricum is famed in poesy ; there was also iron in Crete and in Euboea. Many other mines, neither meagre nor scant, but of vast ex- tent, were overlooked by writers or were unknown to them. Pliny calls hither Spain and the whole region of the Pyrenees
44 WILLIAM GILBERT.
an iron country; and he says that, in the part of Cantabria washed by the ocean, there is a mountain steep and high which (wonderful to tell) is all iron. The earliest mines were iron mines, not mines of gold, silver, copper or lead : for iron is more sought after for the needs of man ; besides, iron mines are plainly visible in every country, in every soil, and they are less deep and less encompassed with difficulties than other mines. But were I simply to enumerate modern iron mines and those worked in our own time, a very 'large book would have to be written, and paper would fail me before iron : yet each one of these mines could supply looo forges. For among minerals there is no other substance so plentiful : all metals and all stones distinct from iron ore are surpassed by ferric and ferruginous substances. For you cannot easily find a district, hardly a township, throughout all Europe, if you search thoroughly, that has not a rich and plentiful vein of iron, or that does not yield an earth either saturated with iron-rust or at least slightly tinctured with it. That this is so, is easily shown by any one versed in metallurgy and chemistry.
Besides iron and its ore, there is another ferric substance, which, however, does not yield the metal, because the thin humor is burnt up by the fierce fires and is converted into dross like that separated from the metal when first smelted. Such is the white clay and argillaceous earth which is seen to make up great part of our British island ; this, if treated with strong heat, either exhibits a ferric and metallic body, or is trans- formed into a ferric vitrification : this fact can be verified in houses built of brick, for the bricks that in the kiln are laid nearest to the fires, and are there burnt, show ferric vitrifica- tion at their other end, which grows black. Furthermore, all those earths when prepared, are attracted by the magnet like iron. Lasting and plentiful is the earth's product of iron.
IN WHAT COUNTRIES IRON IS PRODUCED. 45
Georgius Agricola says that nearly all mountainous regions are full of its ores ; and we, ourselves, do know that a rich iron ore is often dug in the lowlands and plains throughout England and Ireland, as Agricola tells of iron being dug in the meadows near the town of Saga' out of ditches not more than two feet deep. Nor is iron lacking, as some say, in the West Indies ; but, there, the Spaniards, intent on gold, avoid the toilsome manufacture of iron and do not search for rich iron ores and mines. It is probable that nature and the terrestrial globe cannot repress, but is ever sending forth into the light a great quantity of its own native substance, and that this action is not entirely impeded by the pressure of the mingled substances and efflorescences at the circumference. But iron is produced not only in the common mother (the globe of Earth), but sometimes is also in the air, in the uppermost clouds from the earth's vapors. It rained iron in Lucania the year that Marcus Crassus met his death. They tell, too, of a mass of iron, re- sembling slag, having fallen out of the air in the Nethorian forest near Grina, which is said to have weighed several pounds ; and that it could not be carried to that village it was so heavy, and could not be taken on a wagon because there were no roads. This happened before the Civil War of the Saxons, waged by the Dukes. A similar occurrence is men- tioned by Avicenna. In the Torinese, it once rained iron at several points, some three years before that province was con- quered by the King. In the year 1510, as Cardan relates in
• "The like wee reade of at Saga in Ligys, where they digge over their iron mines every tenth yeare. . . . But whosoever readeth that which Francis Leandro hath written touching the iron mineralls in the He of Elba, will cleave perhaps to a third conceit, for he avoucheth that the trenches out of which the oare there is digged, within twenty or thirty yeares, become alike full a.^aine of the same mettall as at first " (Geo. Hakewill's " Apologie," 1635, Lib. II, Sec. 7, pages 164-165).
4^ WILLIAM GILBERT.
his book De Rerum Varietate, there fell from the sky, upon a field near the river Abdua, 1200 stones, one of which weighed 120, another 30 or 40, pounds, all of them the color of iron and exceedingly hard. These occurrences, because they happen seldom, seem to be portents, like the earth-rains and stone- showers mentioned in the annals of the Romans. But that it ever rained other metals is not mentioned ; for it does not ap- pear that gold, silver, lead, tin, or zinc ever fell from heaven. But copper has sometimes been observed to fall from the clouds — a metal differing not much from iron : and this cloud- gendered iron and copper are seen to be imperfect metals, ab- solutely infusible and unforgeable. For the earth, in its emi- nences, abounds in store of iron, and the globe contains great plenty of ferric and magnetic matter. Exhalations of such matter sent forth with some violence may, with the concur- rence of powerful agencies, become condensed in the upper regions, and so may be evolved a certain monstrous progeny of iron.
CHAPTER IX.
IRON ORE ATTRACTS IRON ORE.
Like the other metals, iron is obtained from various sub- stances— stones, earths, and such-like concretions, called by miners ores, or veins, because they are produced in fissures of the earth. Of the diversity of ores we have already spoken. A piece of crude iron ore of the color of iron and rich, as miners say, when floated in a bowl or other vessel in water (as in the case of the loadstone supra) is usually attracted by a
IRON ORE HAS AND ACQUIRES POLES. 4/
like piece of ore held in the hand and brought near to it, but it is not attracted strongly and with rapidity as a loadstone is drawn by a loadstone, but slowly and weakly. Stony ores, and those of an ashy, brown, ruddy, etc., color, neither attract one another nor are attracted even by a powerful loadstone, any more than so much wood or lead or silver or gold would be. Take some pieces of such ores and roast or rather heat them in a moderate fire so that they may not suddenly split or fly to pieces, and retain them ten or twelve hours in the fire, which is to be kept up and moderately increased ; then suffer them to cool, according to the method given in Book III, Of Direc- tion : these stones so manipulated, the loadstone now attracts ; they show mutual sympathy, and, when arranged according to artificial conditions, they come together through the action of their own forces.
CHAPTER X.
IRON ORE HAS AND ACQUIRES POLES, AND ARRANGES ITSELF WITH REFERENCE TO THE EARTH'S POLES.
Men are deplorably ignorant with respect to natural things, :?• and modern philosophers, as though dreaming in the darkness, must be aroused and taught the uses of things, the dealing with things ; they must be made to quit the sort of learning that comes only from books, and that rests only on vain argu- ments from probability and upon conjectures. For the science of iron (than which nought is more in use among us), as of many other bodies, remains unknown — iron, I say, whose rich ore, by an inborn force, when floated in a vessel on water, as-
48 WILLIAM GILBERT.
sumes, like the loadstone, a north and south direction, coming to a standstill at those points, whence if it be turned away, it goes back to them again in virtue of its inborn activity. But of less perfect ores which, however, under the guise of stone or earth contain a good deal of iron, few possess the power of movement ; yet when treated artificially with fire, as told in the foregoing chapter, these acquire polar activity,strength {verticity, as we call it) ; and not only such ores as miners seek, but even earths simply impregnated with ferruginous matter, and many kinds of rock, do in like manner (provided they be skilfully placed), tend and glide toward those positions of the heavens, or rather of the earth, until they reach the point they are seeking : there they eagerly rest.
CHAPTER XL
WROUGHT-IRON, NOT MAGNETIZED BY THE LOADSTONE, ATTRACTS IRON.
* Iron is extracted in the first furnace from the ore, which is converted or separated partly into metal, partly into dross, by the action of very great heat continued for eight, ten, or twelve hours. The metal flows out, leaving behind the dross and use- less substances, and forms a great long mass, which under the blows of a large hammer is cut into pieces : from these, after being reduced in another furnace and again put on the anvil, the workmen form cubical masses, or more usually bars, which are sold to merchants and blacksmiths : from these blocks or bars are everywhere made in smiths' shops various implements.
WROUGHT-IRON, NOT MAGNETIZED, ATTRACTS IRoN. 49
This we call wrought-iron, and, as every one knows, it is at- tracted by the loadstone. But we, steadily trying all sorts of experiments, have discovered that mere iron itself, magnetized by no loadstone, nor impregnated with any extraneous force, attracts other iron, though it does not seize the other iron as eagerly nor as suddenly pulls it to itself as would a strong loadstone. That this is so you may learn from the following experiment : A small piece of cork, round, and the size of a filbert, has an iron wire passed through it to the middle of the wire : float this in still water and approach (without contact) to one end of that wire, the end of another wire : wire attracts wire, and when the one is withdrawn slowly the other follov/s, yet this action takes place only within fit limits. In the figure, A is the cork holding the wire, B one end of the
wire rising a little out of the water, C the end of the second wire, which pulls B. You may demonstrate the same thing with a larger mass of iron. Suspend in equilibrium with a slender silken cord a long rod of polished iron, such as are used to support hangings and curtains ; bring within the distance of half a finger's length of one end of this as it rests still in the air, some oblong mass of polished iron with suitable end : the balanced rod returns to the mass : then quickly withdraw your hand with the mass in a circular track around the point of equilibrium of the suspended rod, and the cord holding the rod will travel in a circle.
so WILLIAM GILBERT.
CHAPTER XII.
A LONG PIECE OF IRON, EVEN NOT MAGNETIZED, ASSUMES A NORTH AND SOUTH DIRECTION.
I All good and perfect iron, if it be drawn out long, acts like a loadstone or like iron rubbed with loadstone : it takes the direction north and south — a thing not at all understood by our great philosophers who have labored in vain to demon- strate the properties of the loadstone and the causes of the friendship of iron for the loadstone. Experiment can be made either with large or small objects of iron, either in air or in water. A straight rod of iron six feet in length and as thick as one's finger is (as described in the foregoing chapter) sus- pended in exact equilibrium with a fine but strong silk thread. The thread, however, should be composed of several silk fila- ments, twisted differently and not all in one direction. Let the experiment be made in a small room with doors and windows all closed, to prevent currents of air in the room : hence it is not well to experiment on windy days or when a storm is brewing. The rod of iron freely acts according to its property and moves slowly until at last coming to a stop at its goals it points north and south, like magnetized iron in a sun-dial, a common mag- netic compass, and the mariner's compass. You may, if you are curious of such experiments, suspend at once from slender threads, iron rods, or wires, or knitting-needles : you shall find them all in accord unless there is some flaw in the conduct of this interesting experiment; for unless you make all the preparations precisely and exactly, your labor will be vain.
FIXED NORTH AND SOUTH PARTS OF IRON. $1
Test the thing in water also : here the result is more sure and more easily obtained. Pass through a round cork an iron wire two or three fingers long, more or less, so that it may just float in water: the moment you put it in the water it turns round on its centre, and one end of the wire travels to the north, the other to the south : the cause of this, you will find later, when we treat of the reasons of the loadstone's directions. And * it is well to know and to hold fast in memory, that as a strong loadstone and iron magnetized by the same, point not always toward the true, pole, but exactly to the point of variation ; likewise will a weaker loadstone and iron that directs itself by its own force, and not by force derived from the impress of any magnet ; so, too, all iron ores, and all substances imbued with any ferric matter and duly prepared, turn to the same point in the horizon — to the place of variation of the locality concerned (if variation exist there), and there they remain and rest.
CHAPTER XIII.
SMELTED IRON HAS IN ITSELF FIXED NORTH AND SOUTH PARTS, MAGNETIC ACTIVITY, VERTICITY, AND FIXED VERTICES OR POLES.
Iron takes a direction toward north and south, but not* with the same point directed toward either pole ; for one end of a piece of iron ore or of an iron wire steadily and constantly points to the north and the other to the south, whether it be suspended in air, or floating in water, and whether the speci- mens be iron bars or thin wires. Even an iron rod or wire ten,
52 WILLIAM GILBERT.
twenty, or more ells in length will point with one extremity to the north, with the other to the south. And if you cut off a part, if the farther end of that piece is boreal (northern), the farther end of the other piece, with which it was before joined, will be austral (southern). And so, if you divide the rod or wire into several pieces, you shall know the poles even before you make an experiment by floating the pieces in water. In all these fragments a boreal end attracts an austral, and repels a boreal, and vice versa, according to magnetic law. But, herein, manufactured iron so differs from loadstone and iron ore, that in a ball of iron of whatever size — e.g., bombs, cannon-balls, culverin balls, falcon balls — polarity (verticity) is less easily acquired and less readily manifested than in the loadstone itself, in ore, and in a round loadstone ; but in iron instruments of any length the force is at once seen : the cause of which, as also the modes of acquiring polarity and poles without a load- stone, together with the account of all other recondite facts touching verticity, we will set forth when we come to treat of the movement of direction.
CHAPTER XIV.
OF OTHER PROPERTIES OF THE LOADSTONE AND OF ITS MEDICINAL VIRTUE.
DiOSCORlDES tells that loadstone blended in water is ad- ministered in a dose of three oboli' to expel gross humors. Galen writes that it has virtues like those of bloodstone.
' Obolus, the sixth part of a drachm.
OTHER PROPERTIES OF THE LOADSTONE. 53
Others say that loadstone causes mental disturbance and makes people melancholic, and often is fatal. Gartias ab Horto does not think it injurious or unwholesome. The people of East India, he says, declare that loadstone taken in small quantity preserves youthfulness: for this reason the elder King Zeilam (Zeilan) is said to have ordered made of loadstone some pans for cooking his food ivictus). " The man who was ordered to do this thing told me," says Gartias.* Many are the varie- ties of loadstone, produced by different mixtures of earths, metals, and humors ; therefore are they totally different in their virtues and effects, according to the neighborhoods of places and the nearness of adhering bodies, and the pits them- selves— unclean matrices, as it were. Hence one loadstone is able to purge the bowels, and another loadstone to stay the purging ; with a sort of fumes, it can gravely affect the mind ; it may corrode the stomach and produce in it serious disease : for such disorders, quacks prescribe gold and emerald, prac- tising the vilest imposture for lucre's sake. Pure loadstone also may be harmless ; and not only that, but many correct ex- cessive humors of the bowels and putrescence of the same, and may bring about a better temperature : such loadstones are the Oriental ones from China, the more compact loadstones of
1 Garcia d'Orta, "Coloquios dos simples .... pello doutor Garcia Dorta" (sic) — Goa 1563. The name of the Portuguese author of this rare work — who was physician to the Spanish Viceroy (Brown's "Vulgar Errors," Book II, page 81) — appears as Garcia ab Horto in the abridged Latin translation made by Charles de I'Ecluse, Antwerp 1567, 1574, 1579, 1593, under title "Aromatumet Simplicium . . . ," and it is rendered in French Garcie du Jardin, by Antoine Colin in his " Histoire des Drogues," Lyon 1619, whilst in other versions it is given as Garcia del Huerto. For the passage above alluded to by Gilbert, see, more particularly, the last (1593) edition, article T>e Magneie, Lib. I, Cap. LVI, pages 178, 179. Hakewill observes (" Apologie," 1635, Lib. II, page 165), "Remarkable indeed that is which Garziasab Horto writes concerning the load-stone in Simpl Indice, Lib. I, Cap. XLVII."
54 WILLIAM GILBERT.
Bengal : these kinds of loadstone are not distasteful nor un- grateful to the senses. Plutarch and Caius Ptolemy, and all the copyists that came after them, believe that loadstone rubbed with garlic does not attract iron. Hence some writers conjecture that garlic is of service against the harmful action of loadstone : in this way does many an untrue and vain opinion in philosophy take its rise in fables and falsehoods.' Not a few physicians have thought that loadstone has power to ex- tract an iron arrow-head from a human body : but a loadstone attracts when it is whole, not when reduced to powder, de- formed, buried in a plaster ; for it does not with its matter at- tract in such case, but serves rather to heal the ruptured tissues by exsiccation, so causing the wound to close and dry up, whereby the arrow-head becomes fixed in the wound. Thus do pretenders to science vainly and preposterously seek for remedies, ignorant of the true causes of things. Headaches, despite the opinion of many, are no more cured by application of a loadstone, than by putting on the head an iron helmet or a steel hat. Administration of loadstone to dropsical persons is either an error of the ancients or a blundering quotation of their transcribers, albeit a loadstone may be found capable of purging the bowels, after the manner of sundry metallic sub- stances : but the effect would be due to some vice of the stone, not to its magnetic force. Nicolaus puts into his " divine plaster" a good deal of loadstone, as do the Augsburg doctors in their " black plaster" for fresh wounds and stabs ; because of the exsiccating effect of the loadstone without corrosion, it becomes an efficacious and useful remedy, Paracelsus, in like manner and for the same end, makes loadstone an ingredient of his plaster for stab-wounds.
* See note, Book I, Chap. I, of present work.
THE MEDICINAL POWER OF THE IRON. 55
CHAPTER XV.
THE MEDICINAL POWER OF THE IRON.
It will not be alien to our purpose to treat briefly of the medicinal power of iron ; for it is beneficial in many diseases of the human system, and by its virtues, both natural and acquired through fit and skilful preparation, it brings about won- derful changes in the human body ; so that we may more clearly describe its nature through its medicinal power and by means of a few well-known experiments ; to the end that even those prentices of medicine who abuse this most excellent medicinal agent may learn to prescribe it more judiciously, for the curing of patients, not as is too often the case, to their destruction. The best iron, i.e., stomoma, chalybs, acies, or aciarium (steel), is reduced by filing to a fine powder ; this powder has strongest vinegar poured on it, is dried in the sun, again treated with vinegar, and once more dried. Then it is washed in spring water or other water at hand, and dried. It is again pulverized and pounded fine on porphyry, sifted through a fine sieve, and kept for use. It is given chiefly in cases of lax and over- humid liver, and in cases of tumid spleen after suitable evacua- tions ; hence young women of pale, muddy, blotchy complexion are by it restored to soundness and comeliness, for it is highly exsiccative and harmlessly astringent. But some, who in every internal disorder always recognize obstructions of liver and spleen, think it beneficial in such cases, as removing obstruc- tions ; and herein they accept the opinions chiefly of certain Arabic writers. Hence in cases of dropsy, schirrus of the
$6 WILLIAM GILBERT.
liver, of chronic jaundice, and hypochondriac melancholia, or complaints of the oesophagus, they prescribe it, or add it to electuaries, often to the sure destruction of many a patient.' Fallopius recommends a preparation of iron of his own for schirrus of the spleen ; but he is much mistaken, for though loadstone is exceedingly beneficial where the spleen is lax and tumid on account of humors, so far is it from curing a spleen thickened to a schirrus, that it makes the mischief far worse ; for agents that are greatly siccative and that absorb humors, transform viscera that have been thickened by schirrus, into the hardness almost of a stone. Some there are who dry it at a high temperature in an oven, burning it till its color is changed to red : it is then called "saffron of Mars,"" and is a very powerful exsiccant and quickly penetrates the intestines. Further, they prescribe violent exercise so that the remedy may enter the heated intestines and reach the part affected. Hence it is reduced to a very fine powder; else it would re- main in the oesophagus and in the chyle and would not pene- trate to the intestines. Therefore this dry, earthly medicament is proved by the most conclusive tests to be, after due evacua- tions, a remedy in diseases arising from humor (when the intes- tines are running and overflowing with morbid fluids). A preparation of steel is indicated for tumid spleen ; chalybeate waters also reduce the spleen, albeit, as a rule, iron is of frigid efificiency and a constringent rather than a resolvent ; but it does this neither by heat nor by cold, but by its own dryness
' " The magnet .... gives comfort and grace, and is a cure for many com- plaints, it is of great value in disputes. When pulverized, it cures many burns. It is a remedy for dropsy " (J. Sermone di F. Sacchetti , § i8). Ac- cording to Dias, "the magnet reconciles husbands to their wives," and Platea remarks that "it is principally of use to the wounded," while Avicenna says it " is a remedy against spleen, the dropsy, and alopecian."
'■* See Book II, Chap. XXIII.
THE MEDICINAL POWER OF THE IRON. 5/
when mixed with a penetrant fluid ; in this way it dissipates humors, thickens the villi; strengthens the fibres and when they are lax makes them contract ; then the natural warmth in the organs thus strengthened becoming stronger does the rest ; but should the liver be indurated and impaired through age or chronic obstruction, or should the spleen be dried up and thickened into a schirrhus, under which complaints the flesh parts of the members become atrophied, and water collects all over the body under the skin — in such cases the preparation of steel does but hasten a fatal result and makes the mischief worse. Some recent authorities prescribe, as a highly com- mended and celebrated remedy for dried-up liver, an electuary of iron slag described by Razes (Rhazes — Abu Bekr Arrasi) in hoo\i mvA!i\. Ad Almansorem, or of prepared steel filings: bad and pernicious counsel. But now if they never will learn from our philosophy, at least daily experience and the decline and death of their patients will convince them, slow and sluggish as they are. Whether iron be warm or cold is a question over which many contend. Manardus, Curtius, Fallopius, and others bring many arguments for both sides : every one judges accord- ing to his own way of looking at it. Some will have it cold, saying that iron has the power of refrigeration, since Aristotle in the Meteorologica declares it to belong to the class of bodies that become concreted through cold by emission of all their warmth. Galen, too, says that iron gets its consistency from cold ; further, that it is an earthy body and dense. It is de- clared to be cold also because it is astringent, and ^ because chalybeate water stills thirst ; they mention also the sensation of coolness produced by thermic chalybeate waters. But others hold it to be warm, since Hippocrates says that chalybeate waters issuing from places where iron exists are warm. Galen says that in all metals there is much substance or essence of
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fire. Razes will have it that iron is warm and dry in the third degree. The Arabs hold that iron opens the spleen and the liver : hence it is warm. Montagnana recommends it for frigid complaints of uterus and oesophagus. And thus do sciolists wrangle with one another, and confuse the minds of learners with their questionable cogitations, and debate over the ques- tion of goat's wool, philosophizing about properties illogically inferred and accepted : but these things will appear more plainly when we come to treat of causes, the murky cloud being dispersed that has so long involved all philosophy. Iron filings, iron scales, iron dross, do not, says Avicenna, lack harmful quality (perhaps when they are not properly prepared, or are taken in too large doses), hence they produce violent intes- tinal pains, roughness in the mouth and on the tongue, marasmus, and drying up of the members. But mistakenly and old womanishly does Avicenna declare that the true anti- dote of this ferric poison is a drachm of loadstone taken in a draught of the juice of dog's mercury or of beet-root ; for load- stone too is of a twofold nature, and often is injurious and fatal in its effects ; neither does it withstand iron, for it attracts it ; nor is it able to attract when drunk as a powder in liquid ; rather does it cause the self-same mischiefs.
IDENTITY OF LOADSTONE AND IRON ORE. 59
CHAPTER XVI.
THAT LOADSTONE AND IRON ORE ARE THE SAME, AND THAT IRON IS OBTAINED FROM BOTH, LIKE OTHER METALS FROM THEIR ORES ; AND THAT ALL MAGNETIC PROPERTIES EX- IST, THOUGH WEAKER, BOTH IN SMELTED IRON AND IN IRON ORE.
So far we have been telling of the nature and properties of loadstone, as also of the properties and nature of iron ; it now remains that we point out their mutual affinities — their consan- guinity, so to speak — and that we show the two substances to be very nearly allied. In the uppermost part of the terrestrial globe or its superficies of detritus — its rind as it were — these two bodies come into being and are generated in the same matrix, in one bed, like twins. Strong loadstones are mined from separate deposits, and weaker loadstones also have their own beds. Both occur in iron mines. Iron ore occurs usually by itself, unaccompanied by strong loadstone (for the more perfect loadstones occur more rarely). A strong load- stone looks like iron : from it is often made the best iron, which the Greeks call stomoma, the Latins acies, and the Barbarians, not inappropriately, aciare or aciarium. This stone attracts and repels other loadstones, and governs their directions ; points to the earth's poles, attracts molten iron, and does many other wonderful things, some of which we have already mentioned, but many more remain yet to be pointed out. A weak load- stone will do the same, but less forcefully : and iron ore, and also smelted iron (if they be prepared), show their virtues
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*■ in all magnetic experiments, no less than do weak magnets ; and the inert iron ore, endowed with no magnetic powers, that is taken out of the mine, becomes awake when treated in the furnace and fittingly prepared, and then is a loadstone
* in power and properties. Sometimes ironstone or iron ore exerts attractive action the moment it comes from the mine, and without being prepared in any way ; native iron, also, or ore of iron color, attracts iron and makes it point to the poles. Thus the form, appearance, and essence are one. For to me there seems to be greater difference and unlikeness between a very strong loadstone and a weak one that is hardly able to attract a single particle of iron filings ; between a hard, firm, and metallic loadstone and one that is soft, friable, clayey, with so great a difference between them in color, substance, qualities and weight; than between the best ore, rich in iron, or iron that from the first is metallic, on the one hand, and the best loadstone on the other. Nay, the two are usually not to be distinguished by any signs, nor can miners tell one from the other, for they agree in all respects. Further, we see both the finest magnet and iron ore visited as it were by the same ills and diseases, aging in the same way and with the same in- dications, preserved by the same remedies and protective meas- ures, and so retaining their properties : so, too, the one adds to the other's power and intensifies and increases it, when the two are artificially connected. For they are both impaired by the action of acrid liquids as though by poisons ; the aqua fortis of the chemists does equal injury to both; exposed for a long time to the action of the atmosphere they both, in equal de- gree, age as it were and decline ; each is saved from impairment by being kept in the debris and scrapings of the other, and a suit- able piece of steel or iron being applied to its pole, the mag- netic power is intensified by the steadfast union. A loadstone
IDENTITY OF LOADSTONE AND IRON ORE. 6l
is kept in iron filings not as though it fed on iron, or as though it were a hving thing needing victual, as Cardan philosophizes ; neither because thus it is protected from the injurious action of the atmosphere (wherefore both the loadstone and iron are kept in bran by Scaliger; though Scaliger is mistaken here, for they are not best preserved so, and loadstone and iron in some of their forms last a long time) ; but because each is kept unim- paired in filings of the other and their extremities do not be- come weak, but are cherished and preserved. For as in their native sites and mines, similar bodies surrounded by other bodies of the same kind, e.g., the minor interior parts of some great mass, endure for ages whole and undecayed ; so load- stone, and iron ore, when buried in a like material, do not part with their native humor, and do not become weak, but retain their original properties. A loadstone packed in iron filings, as also iron ore in scrapings of loadstone, and manufactured iron in the same or in iron filings, lasts longer. Thus these two associated bodies possess the true, strict form of one species, though, because of their outwardly different aspect and the in- equality of the self-same innate potency, they have hitherto been by all held to be different, and by sciolists to be specifi- cally different, for sciolists have not understood that in both substances reside exactly the same potencies, differing however in strength. They are in fact true parts and intimate parts of the globe, retaining nature's primal powers of mutual attrac- tion, of mobility, and of ordering themselves according to the position of the globe itself : these powers they impart to eacli other, enhancing each other's powers, confirming them, taking them from each other, and holding them. The stronger invig- orates the weaker, not as if it imparted of its own substance or parted with aught of its own strength, neither by injecting into that other any physical substance ; but the dormant power of
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one is awakened by the other's without expenditure. For if with one loadstone you magnetize one thousand compass needles for mariners' use that loadstone not less powerfully attracts iron than it did before ; with one stone weighing a pound any one can suspend in air looo pounds of iron. For if one were to drive into a wall a number of iron nails weighing all together lOOO pounds, and were to apply to them an equal number of other nails properly magnetized by contact with a loadstone, the nails would plainly hang suspended in air through the power of one single stone. Hence this is not the action, work, or outlay of the loadstone solely, for the iron, which is something extracted from loadstone, a transformation of load- stone into metal, and which gains force from the loadstone and (whatever ore it may have been derived from) by its proximity strengthens the loadstone's magnetic power, at the same time enhances its own native force by the proximity of the load- stone and by contact therewith, even though solid bodies inter- vene between them. Iron touched by loadstone renovates other iron by contact and gives it magnetic direction ; and that does the same for a third piece of iron. But if you rub with loadstone any other metal, or wood, or bone, or glass, as they will not move toward a fixed and determinate quarter of the heavens, nor will be attracted by a magnetized body ; so they cannot impart by attrition or by infection any magnetic property either to other bodies or to iron itself. Loadstone differs from iron ore, as also from some weak loadstones, in that when reduced in the furnace to a ferric and metallic molten mass, it does not always assume readily the fluid condition and become changed to metal, but sometimes is burnt into ash in the large furnaces ; this, either because of a certain admixture of sulphurous matter, or because of its own excellence and more simple nature ; or because of the resemblance it bears
IDENTITY OF LOADSTONE AND IRON ORE. 63
to nature, and the form it has in common with that mother of all ; for earths, ferruginous stones, and loadstones rich in metal, are much loaded and disfigured with drossy metallic humors and with foreign earthy admixtures in their substance, like most weak magnets from the mines ; hence they are farther removed from the common mother and are degenerate, and in the furnace they are more easily melted and give a softer sort of iron and no good steel. Most loadstones, if they be not un- duly burnt, yield in the furnace the best of iron. But in all these prime quahties iron ore agrees with loadstone, for both, being more akin to the earth and more nearly associated to it than any other bodies around us, possess within themselves the magnetic, genuine, homogenic and true substance of the terres- trial globe, less tainted and impaired by foreign impurities, and less mixed with the efflorescences on the earth's surface and the debris of generations of organisms. And on this ground does Aristotle seem, in book fourth of his Meteora, to distinguish iron from all other metals. Gold, says he, silver, copper, tin, lead, pertain to water ; but iron is earthy. Galen, in the fourth book De Facultatibus Simplicium Medicament or um, says that iron is an earthy and dense body. So, according to our rea- soning, loadstone is chiefly earthy ; next after it comes iron ore or weak loadstone ; and thus loadstone is by origin and nature ferruginous, and iron magnetic, and the two are one in species. Iron ore in the furnace yields iron ; loadstone in the furnace yields iron also, but of far finer quality, which is called steel ; and the better sort of iron ore is weak loadstone, just as the best loadstone is the most excellent iron ore in which we will show that grand and noble primary properties inhere. It is only in weaker loadstone, or iron ore, that these properties are obscure, or faint, or scarcely perceptible to the senses.
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CHAPTER XVII.
THAT THE TERRESTRIAL GLOBE IS MAGNETIC AND IS A LOAD- STONE ; AND JUST AS IN OUR HANDS THE LOADSTONE POSSESSES ALL THE PRIMARY POWERS (FORCES) OF THE EARTH, SO THE EARTH BY REASON OF THE SAME POTEN- CIES LIES EVER IN THE SAME DIRECTION IN THE UNI- VERSE.
Before we expound the causes of the magnetic movements and bring forward our demonstrations and experiments touch- ing matters that for so many ages have lain hid — the real foundations of terrestrial philosophy — we must formulate our new and till now unheard-of view of the earth, and submit it to the judgment of scholars. When it shall have been sup- ported with a few arguments of prima facie cogency, and these shall have been confirmed by subsequent experiments and demonstrations, it will stand as firm as aught that ever was pro- posed in philosophy, backed by ingenious argumentation, or but- tressed by mathematical demonstrations. The terrestrial mass which together with the world of waters produces the spherical figure and our globe, inasmuch as it consists of firm durable matter, is not easily altered, does not wander nor fluctuate with indeterminate movements like the seas and the flowing streams ; but in certain hollows, within certain bounds, and in many veins and arteries, as it were, holds the entire volume of liquid matter, nor suffers it to spread abroad and be dissipated. But the solid mass of the earth has the greater volume and holds preeminence in the constitution of our globe. Yet the water is
THE TERRESTRIAL GLOBE A LOADSTONE. 65
associated with it, though only as something supplementary and as a flux emanating from it ; and from the beginning it is intimately mixed with the smallest particles of earth and is innate in its substance. The earth growing hot emits it as vapor, which is of the greatest service to the generation of things. But the strong foundation of the globe, its great mass, is that terrene body, far surpassing in quantity the whole aggregate of fluids and waters whether in combination with earth or free (whatever vulgar philosophers may dream about the magnitudes and proportions of their elements) ; and this mass makes up most of the globe, constituting nearly its whole interior framework, and of itself taking on the spherical form. For the seas do but fill certain not very deep hollows, having very rarely a depth of a mile, and often not exceeding 100 or 50 fathoms. This appears from the observations of navigators who have with line and sinker explored their bottoms. In view of the earth's dimension, such depressions cannot much impair the spheroidal shape of the globe. Still the portion of the earth that ever comes into view for man or that is brought to the surface seems small indeed, for we cannot penetrate deep into its bowels, beyond the debris of its outermost efflorescence, hindered either by the waters that flow as through veins into great mines ; or by the lack of wholesome air necessary to sup- port the life of the miners ; or by the enormous cost of exe- cuting such vast undertakings, and the many difficulties attend- ing the work. Thus we cannot reach the inner parts of the globe, and if one goes down, as in a few mines, 400 fathoms, or (a very rare thing) 500 fathoms, it is something to make every one wonder. But how small, how almost null, is the proportion of 500 fathoms to the earth's diameter, 6,872 miles, can be easily understood. So we do only see portions of the earth's circum- ference, of its prominences ; and everywhere these are either
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loamy, or argillaceous, or sandy ; or consist of organic soils or marls ; or it is all stones and gravel ; or we find rock-salt, or ores, or sundry other metallic substances. In the depths of the ocean and other waters are found by mariners, when they take soundings, ledges and great reefs, or bowlders, or sands, or ooze. The Aristotelian element, earth, nowhere is seen, and the Peripateties are misled by their vain dreams about elements. But the great bulk of the globe beneath the sur- face and its inmost parts do not consist of such matters ; for these things had not been were it not that the surface was in contact with and exposed to the atmosphere, the waters, and the radiations and influences of the heavenly bodies ; for by the action of these are they generated and made to assume many different forms of things, and to change perpetually. Still do they imitate the inner parts and resemble their source, because their matter