^1 _Bîjâdah_ is classified by Muhammad B_On the magnet, magnetick bodies also, and on the great magnet the earth a new physiology, demonstrated by many arguments & experiments

al Mubârak (A.D. 1520) under "stones resembling ruby"; the Tansûk nâmah

describes it in a separate chapter. From the description it can be

identified with the almandine garnet, and the method of cutting this

stone _en cabochon_, with hollow back in order to display its colour

better is specially mentioned. The Tansûk nâmah only incidentally

refers to the electric property of the _bîjâdah_ in the chapter on

loadstone, but the other two treatises specially refer to it in their

description of the stone. The one has: "_Bîjâdah_ if rubbed until warm,

attracts straws and other light bodies just as amber does"; the other:

"_Bîjâdah_, if rubbed on the hair of the head, or on the beard,

attracts straws." Surûri, the lexicographer, who compiled a dictionary

in 1599, considers the _bîjâdah_ "a red ruby which possesses the

property of attraction." Other dictionaries do not mention the

attractive property, but some authors confound the stone with amber,

calling it _Kâbrubâ_, the straw-robber. The _bîjâdah_ is not rubellite

(red tourmaline) for it is described in the lapidaries as common,

whereas rubellite (from Ceylon) has always been rare, and was unknown

in Persia in the thirteenth century.

[111] PAGE 47, LINE 21. Page 47, line 25. _Succinum seu

succum._--Dioscorides regarded amber as the inspissated juice of the poplar

tree. From the Frankfurt edition of 1543 (_De Medicinali materia, etc._)

edited by Ruellius, we have, liber i., p. 53:

_Populus._ Cap. XCIII.

"... Lachrymam populorum commemorant quæ in Padum amnem defluat, durari, ac

coire in succinum, quod electrum vocant, alii chrysophorum. id attritu

jucundum odorem spirat, et aurum colore imitatur. tritum potumque stomachi

ventrisque fluxiones sistit."

To this Ruellius adds the commentary:

"Succinum seu succina gutta à succo dicta, Græcis [Greek: êlektrom] [sic],

esse {35} lachryma populi albæ, vel etiam nigræ quibusdam videtur, ab

ejusdem arboris resina. Dioscoridi et Galeno dicta differens et [Greek:

pterugophoros], id est paleas trahens, quoque vocatur, quantum ei quoque

Galenus tribuit li. 37, ca. 9. Succinum scribit à quibusdam pinei generis

arboribus, ut gummi à cerasis excidere autumno, et largum mitti ex Germania

septentrionali, et insulis maris Germanici. quod hodie nobis est

compertissimum: ad hæc liquata igni valentiore, quia à frigido intensiore

concrevit. pineam aperte olet, calidum primo gradu, siccum secundo,

stomachum roborat, vomitum, nauseam arcet. cordis palpitationi prodest.

pravorem humorum generationem prohibet.

"Germani weiss und gelbaugstein et bre[=n]stein.

"Galli ambra vocant: vulgo in corollis precariis frequens."

In the scholia of Johann Lonicer in his edition of Dioscorides, we find,

lib. i., cap. xcviii., _De nigra Populo_:

"[Greek: aigeiros], populus nigra ... idem electrum vel succinum [Greek:

haigeirou] lachrymam esse adseverat [Paulus], cui præter vires quæ ab

Dioscoride recensentur, tribuit etiam vim sistendi sanguinis, si tusum in

potu sumatur. Avicennæ Charabe, ut colligitur ex Joanne Jacobo Manlio, est

electrum hoc Dioscoridis, attestatur Brunfelsius. Lucianus planè nullum

electrum apud Eridanum seu Padum inveniri tradit, quandoquidem ne populus

quidem illa ab nautis ei demonstrari potuerit. Plinius rusticas

transpadanas ex electro monilia gestare adfirmat, quum à Venetis primum

agnoscere didicissent adversus nimirum vitia gutturis et tonsillarum. Num

sit purgamentum maris, vel lachryma populi, vel pinus, vel ex radiis

occidentis solis nascatur, vel ex montibus Sudinorum profluat, incertum

etiam Erasmus Stella relinquit. Sudinas tamen Borussiorum opes esse

constat."

Matthiolus (in _P. A. Mattioli ... Opera quæ extant omnia, hoc est

Commentarii in vi libros P. Dioscoridis de materia medica_, Frankfurt,

1596, p. 133) comments on the suggestion of Galen that amber came from the

_Populus alba_, and also comments on the Arabic, Greek, and Latin names of

amber.

The poplar-myth is commemorated by Addison (in _Italy_) in the lines:

No interwoven reeds a garland made,

To hide his brows within the vulgar shade;

But poplar wreathes around his temples spread,

And tears of amber trickled down his head.

Amber is, however, assuredly not derived from any poplar tree: it comes

from a species of pine long ago extinct, called by Göppert the _pinites

succinifer_.

Gilbert does not go into the medicinal uses, real or fancied, that have

been ascribed to amber in almost as great variety as to loadstone. Pliny

mentions some of these in his _Natural Historie_ (English version of 1601,

p. 609):

"He [Callistratus] saith of this yellow Amber, that if it be worne about

the necke in a collar, it cureth feavers, and healeth the diseases of the

mouth, throat, and jawes: reduced into pouder and tempered with honey and

oile of roses, it is soveraigne for the infirmities of the eares. Stamped

together with the best Atticke honey, it maketh a singular eyesalve for to

help a dim sight: pulverized, and the pouder thereof taken simply alone, or

else drunke in water with Masticke, is soveraigne for the maladies of the

stomacke."

Nicolaus Myrepsus (Recipe 951, _op. citat._) gives a prescription for {36}

dysentery and diabetes confiding chiefly of "Electri vel succi Nili (Nili

succum appellant Arabes Karabem)."

[112] PAGE 47, LINE 22. Page 47, line 26. _Sudauienses seu Sudini._--Cardan

in _De Rerum Varietate_, lib. iii., cap. xv. (Editio Basil., 1556, p. 152),

says of amber:

"Colligitur in quadam penè insula Sudinorum, qui nunc uoc[=a]tur Brusci, in

Prussia, nunc Borussia, juxta Veneticum sinum, & sunt orientaliores ostiis

Vistulæ fluuii: ubi triginta pagi huic muneri destinati sunt," etc. He

rejects the theory that it consists of hardened gum.

There exists an enormous literature concerning Amber and the Prussian amber

industry. Amongst the earliest works (after Theophrastus and Pliny) are

those of Aurifaber (_Bericht über Agtstein oder Börnstein_, Königsberg,

1551); Goebel (_De Succino, Libri duo, authore Severino Goebelio, Medico

Doctore_, Regiomont., 1558); and Wigand (_Vera historia de Succino

Borussico_, Jena, 1590). Later on Hartmann, P. J. (_Succini Prussici

Physica et civilis Historia_, Francofurti, 1677); and the splendid folio of

Nathaniel Sendel (_Historia Succinorum corpora aliena involventium_,

Lipsiæ, 1742), with its wealth of plates illustrating amber specimens, with

the various included fossil fauna and flora. Georgius Agricola (_De natura

Fossilium_, liber iv.), and Aldrovandi (_Musæeum Metallicum_, pp. 411-412)

must also be mentioned. Bibliographies of the earlier literature are to be

found in Hartmann (_op. citat._), and in Daniel Gralath, _Elektrische

Bibliothek_ (_Versuche und Abhandlungen der Naturforschenden Gesellschaft

in Danzig_, Zweiter Theil, pp. 537-539, Danzig and Leipzig, 1754). See also

Karl Müllenhoff, _Deutsche Altertumskunde_, vol. i., Zweites Buch, pp.

211-224, Zinn und Bernsteinhandel (Berlin, 1870), and Humboldt's _Cosmos_

(Bohn's edition, London, 1860, vol. ii., p. 493).

The ancient Greek myth according to which amber was the tears of the

Heliades, shed on the banks of the river Eridanus over Phaethon, is not

alluded to by Gilbert. It is narrated in well-known passages in Ovid and in

Hyginus. Those interested in the modern handling of the myth should refer

to Müllenhoff (_op. citat._, pp. 217-223, der Bernsteinmythus), or to that

delightful work _The Tears of the Heliades_, by W. Arnold Buffum (London,

1896).

[113] PAGE 47, LINE 30. Page 47, line 36. _quare & muscos ... in frustulis

quibusdam comprehensos retinet._--The occurrence of flies in amber was well

known to the ancients. Pliny thus speaks of it, book xxxvii., chap. iii.

(p. 608 of P. Holland's translation of 1601):

"That it doth destill and drop at the first very clear and liquid, it is

evident by this argument, for that a man may see diverse things within, to

wit, Pismires, Gnats, and Lizards, which no doubt were entangled and stucke

within it when it was greene and fresh, and so remain enclosed within as it

waxed harder."

A locust embedded in amber is mentioned in the _Musæum Septalianum_ of

Terzagus (Dertonæ, 1664).

Martial's epigram (_Epigrammata_, liber vi., 15) is well known:

Dum Phaethontea formica vagatur in umbra

Implicuit tenuem succina gutta feram.

See also Hermann (Daniel), _De rana et lacerta Succino Borussiaco insitis_

{37} (Cracov., 1580; a later edition, Rigæ, 1600). The great work on

_inclusa_ in amber is, however, that of Nathaniel Sendel. See the previous

note.

Sir Thomas Browne must not be forgotten in this connexion. The

_Pseudodoxia_ (p. 64 of the second edition, 1650) says:

"Lastly, we will not omit what Bellabonus upon his own experiment writ from

Dantzich unto Mellichius, as he hath left recorded in his chapter _De

Succino_, that the bodies of Flies, Pismires and the like, which are said

oft times to be included in Amber, are not reall but representative, as he

discovered in severall pieces broke for that purpose. If so, the two famous

Epigrams hereof in Martiall are but poeticall, the Pismire of Brassavolus

Imaginary, and Cardans Mousoleum for a flie, a meer phancy. But hereunto we

know not how to assent, as having met with some whose reals made good their

representments." See also Pope's _Epistle to Dr. Arbuthnot_, line 169.

[114] PAGE 47, LINE 34. Page 47, line 40. _Commemorant antiqui quod

succinum festucas et paleas attrahit._--Pliny (book xxxvii., chap. ii., p.

606 of the English edition of 1601) thus narrates the point:

"Hee [_Niceas_] writeth also, that in Aegypt it [amber] is engendered....

Semblably in Syria, the women (saith hee) make wherves of it for their

spindles, where they use to call it Harpax, because it will catch up

leaves, straws, and fringes hanging to cloaths."

p. 608. "To come to the properties that Amber hath, If it bee well rubbed

and chaufed betweene the fingers, the potentiall facultie that lieth

within, is set on work, and brought into actual operation, whereby you

shall see it to drawe chaffe strawes, drie leaves, yea, and thin rinds of

the Linden or Tillet tree, after the same sort as loadstone draweth yron."

[115] PAGE 47, LINE 36. Page 47, line 42. _Quod etiam facit Gagates

lapis._--The properties of Jet were well known to the mediæval writers.

_Julius Solinus_ writes in _De Mirabilibus_, chapter xxxiv., _Of Britaine_

(English version of 1587 by A. Golding):

"Moreover to the intent to passe the large aboundance of sundry mettals

(whereof Britaine hath many rich mynes on all sides), Here is store of the

stone called Geate, and y^e best kind of it. If ye demaund y^e beautie of

it, it is a black Jewell: if the qualitie, it is of no weight: if the

nature, it burneth in water, and goeth out in Oyle; if the power, rubbe it

till it be warme, and it holdeth such things as are laide to it; as Amber

doth. The Realme is partlie inhabited of barbarous people, who even frõ

theyr childhoode haue shapes of divers beastes cunninglye impressed and

incorporate in theyr bodyes, so that beeing engraued as it were in theyr

bowels, as the man groweth, so growe the marks painted vpon him...."

Pliny describes it as follows (p. 589, English edition of 1601):

"The Geat, which otherwise we call Gagates, carrieth the name of a toune

and river both in Lycia, called Gages: it is said also, that the sea

casteth it up at a full tide or high water into the Island Leucola, where

it is gathered within the space of twelve stadia, and no where else: blacke

it is, plaine and even, of a hollow substance in manner of the pumish

stone, not much differing from the nature of wood; light, brittle, and if

it bee rubbed or bruised, of a strong flavour." (Book xxxvi., chap. xviii.)

In the Commentary of Joannes Ruellius upon Dioscorides, _Pedanii

Dioscoridis Anazarbei de medicinali materia libri sex, Ioanne Ruellio

Suessionensi interprete_ ... (Frankfurt, 1543, fol., liber quintus, cap.

xcii.) is the following description:

{38} "In Gagatarum lapidum genere, præferendus qui celeriter accenditur, et

odorem bituminis reddit. niger est plerunque, et squalidus, crustosus, per

quam levis. Vis ei molliendi, et discutiendi. deprehendit sonticum morbum

suffitus, recreatque uuluæ strangulationes. fugat serpentes nidore.

podagricis medicaminibus, et a copis additur. In Cilicia nasci solet, qua

influens amnis in mare effunditur, proxime oppidum quod Plagiopolis

dicitur. vocatur autem et locus et amnis Gagas, in cujus faucibus ii

lapides inveniuntur.

"Gagates lapis colore atro, Germanis Schwartzer augstein, voce parum

depravata, dicitur. odore dum uritur bituminis, siccat, glutinat, digerit

admotus, in corollis precariis et salinis frequens."

And in the _Scholia_ upon Dioscorides of Joannes Lonicer (Marpurgi, 1643,

cap. xcvii., p. 80) is the following:

"_De Gagate Lapide._ Ab natali solo, urbe nimirum Gagae Lyciae nomen habet.

Galenus se flumen isthuc et lapidem non invenisse, etiamsi naui parua totam

Lyciam perlustravit: ait, se autem in caua Syria multos nigros lapides

invenisse glebosos, qui igni impositi, exiguam flammam gignerent. Meminit

hujus Nicander in Theriacis nempe suffitum hujus abigere venenata."

There is also a good account of _Gagates_ (and of Succinum) by Langius,

_Epistola_ LXXV., p. 454, of the work _Epistolarum medicinalium volumen

tripartitum_ (Francofurti, 1589).

[116] PAGE 47, LINE 39. Page 47, line 45. _Multi sunt authores

moderni._--The modern authors who raised Gilbert's wrath by ignorantly

copying out all the old tales about amber, jet, and loadstone, instead of

investigating the facts, were, as he says at the beginning of the chapter,

some theologians, and some physicians. He seems to have taken a special

dislike to Albertus Magnus, to Puteanus (Du Puys), and to Levinus Lemnius.

[117] PAGE 47, LINE 39. Page 47, line 46. _& gagate._--The editions of 1628

and 1633 both read _ex gagate_.

[118] PAGE 48, LINE 14. Page 48, line 16. _Nam non solum succinum, &

gagates (vt illi putant) allectant corpuscula._--The list of bodies known

to become electrical by friction was not quite so restricted as would

appear from this passage. Five, if not six, other minerals had been named

in addition to amber and jet.

(1.) _Lyncurium._ This stone, about which there has been more obscurity and

confusion than about any other gem, is supposed by some writers to be the

tourmaline, by others a jacinth, and by others a belemnite. The ancients

supposed it to be produced from the urine of the lynx. The following is the

account of Theophrastus, _Theophrastus's History of Stones. With an English

Version_ ..., by "Sir" John Hill, London, 1774, p. 123, ch. xlix.-l. "There

is some Workmanship required to bring the Emerald to its Lustre, for

originally it is not so bright. It is, however, excellent in its Virtues,

as is also the _Lapis Lyncurius_, which is likewise used for engraving

Seals on, and is of a very solid Texture, as Stones are; it has also an

attractive Power, like that of Amber, and is said to attract not only

Straws and small pieces of Sticks, but even Copper and Iron, if they are

beaten to thin pieces. This Diocles affirms. The _Lapis Lyncurius_ is

pellucid, and of a fire Colour." See also W. Watson in _Philos. Trans._,

1759, L. i., p. 394, _Observations concerning the Lyncurium of the

ancients_.

(2.) _Ruby._

(3.) _Garnet._ The authority for both these is Pliny, _Nat. Hist._, book

xxxvii., chap. vii. (p. 617 of English edition of 1601).

{39} "Over and besides, I find other sorts of Rubies different from those

above-named;... which being chaufed in the Sun, or otherwise set in a heat

by rubbing with the fingers, will draw unto them chaffe, strawes, shreads,

and leaves of paper. The common Grenat also of Carchedon or Carthage, is

said to doe as much, although it be inferiour in price to the former."

(4.) _Jasper._ Affaytatus is the authority, in _Fortunii Affaitati Physici

atque Theologi ... Physicæ & Astronomicæ c[=o]siderationes_ (Venet., 1549),

where, on p. 20, he speaks of the magnet turning to the pole, likening it

to the turning of a "palea ab Ambro vel Iaspide et hujuscemodi lapillis

lucidis."

(5.) _Lychnis._ Pliny and St. Isidore speak of a certain stone _lychnis_,

of a scarlet or flame colour, which, when warmed by the sun or between the

fingers, attracts straws or leaves of papyrus. Pliny puts this stone

amongst carbuncles, but it is much more probably _rubellite_, that is to

say, red tourmaline.

(6.) _Diamond._ In spite of the confusion already noted, _à propos_ of

_adamas_ (Note to p. 47), between loadstone and diamond, there seems to be

one distinct record of an attractive effect having been observed with a

rubbed diamond. This was recorded by Fracastorio, _De sympathia et

antipathia rerum_ (Giunta edition, Venice, MDLXXIIII, chap. v., p. 60

_verso_), "cujus rei & illud esse signum potest, cum confricata quædã vt

Succinum, & Adamas fortius furculos trahunt." And (on p. 62 _recto_); "nam

si per similitudine (vt supra diximus) fit hæc attractio, cur magnes non

potius magnetem trahit, [~q] ferrum, & ferrum non potius ad ferrum movetur,

quàm ad magnetem? quæ nam affinitas est pilorum, & furculorum cum Electro,

& Adamante? præsertim [~q] si cum Electro affines sunt, quomodo & cum

Adamante affinitatem habebunt, qui dissimilis Electro est?" An

incontestable case of the observation of the electrification of the diamond

occurs in Gartias ab Horto. The first edition of his _Historia dei Semplici

Aromati_ was publisht at Goa in India in 1563. In chapter xlviii. on the

Diamond, occur these words (p. 200 of the Venetian edition of 1616):

"Questo si bene ho sperimentato io più volte, che due Diamanti perfetti

fregati insieme, si vniscono di modo insieme, che non di leggiero li potrai

separare. Et ho parimente veduto il Diamante dopo di esser ben riscaldato,

tirare à se le festuche, non men, che si faccia l'elettro." See also

Aldrovandi, _Musæum Metallicum_ (Bonon., 1648, p. 947).

Levinus Lemnius also mentions the Diamond along with amber. See his

_Occulta naturæ miracula_ (English edition, London, 1658, p. 199).

[119] PAGE 48, LINE 16. Page 48, line 18. _Iris gemma._--The name _iris_

was given, there can be little doubt, to clear six sided prisms of

rock-crystal (quartz), which, when held in the sun's beams, cast a crude

spectrum of the colours of the rainbow. The following is the account of it

given in Pliny, book xxxvii., chap. vii. (p. 623 of the English version of

1601):

"... there is a stone in name called Iris: digged out of the ground it is

in a certaine Island of the red sea, distant from the city Berenice three

score miles. For the most part it resembleth Crystall: which is the reason

that some hath tearmed it the root of Crystall. But the cause why they call

it Iris, is, That if the beames of the Sunne strike upon it directly within

house, it doth send from it against the walls that bee neare, the very

resemblance both in forme and also in colour of a rainebow; and eftsoones

it will chaunge the same in much varietie, to the great admiration of them

that behold it. For certain it is knowne, that six angles it hath in manner

of the Crystall: but they say that some of them have their sides rugged,

and the same {40} unequally angled: which if they be laid abroad against

the Sunne in the open aire, do scatter the beames of the Sunne, which light

upon them too and fro: also that others doe yeeld a brightnes from

themselves, and thereby illuminat all that is about them. As for the

diverse colours which they cast forth, it never happeneth but in a darke or

shaddowie place: whereby a man may know, that the varietie of colours is

not in the stone Iris, but commeth by the reverberation of the wals. But

the best Iris is that which representeth the greatest circles upon the

wall, and those which bee likest unto rainebowes indeed."

In the English translation of Solinus's _De Mirabilibus_ (_The excellent

and pleasant worke of Julius Solinus containing the noble actions of

humaine creatures, the secretes and providence of nature, the descriptions

of countries ... tr. by A. Golding, gent._, Lond., 1587), chapter xv. on

Arabia has the following:

"Hee findeth likewise the Iris in the Red sea, sixe cornered as the

Crystall: which beeing touched with the Sunnebeames, casteth out of him a

bryght reflexion of the ayre like the Raynebowe."

Iris is also mentioned by Albertus Magnus (_De mineralibus_, Venet., 1542,

p. 189), by Marbodeus Gallus (_De lapidibus_, Par. 1531, p. 78), who

describes it as "crystallo simulem sexangulam," by Lomatius (_Artes of

curious Paintinge_, Haydocke's translation, Lond., 1598, p. 157), who says,

"... the Sunne, which casting his beames vpon the _stone Iris_, causeth the

_raine-bowe_ to appeare therein ...," and by "Sir" John Hill (_A General

Natural History_, Lond., 1748, p. 179).

Figures of the Iris given by Aldrovandi in the _Musæum Metallicum_ clearly

depict crystals of quartz.

[120] PAGE 48, LINE 16. Page 48, line 18. _Vincentina, & Bristolla (Anglica

gemma siue fluor)_. This is doubtless the same substance as the _Gemma

Vincentij rupis_ mentioned on p. 54, line 16 (p. 54, line 18, of English

Version), and is nothing else than the so-called "Bristol diamond," a

variety of dark quartz crystallized in small brilliant crystals upon a

basis of hæmatite. To the work by Dr. Thomas Venner (Lond., 1650), entitled

_Via Recta_ or the _Bathes of Bathe_, there is added an appendix, _A

Censure concerning the water of Saint Vincents Rocks neer Bristol (Urbs

pulchra et Emporium celebre)_, in which, at p. 376, occurs this passage:

"This Water of Saint _Vincents_ Rock is of a very pure, cleare, crystalline

substance, answering to those crystalline Diamonds and transparent stones

that are plentifully found in those Clifts."

In the _Fossils Arranged_ of "Sir" John Hill (Lond., 1771), p. 123, is the

following entry: "Black crystal. Small very hard heavy glossy. Perfectly

black, opake. Bristol (grottos, glass)" referring to its use.

The name _Vincentina_ is not known as occurring in any mineralogical book.

Prof. H. A. Miers, F.R.S., writes concerning the passage: "_Anglica gemma

sive fluor_ seems to be a synonym for _Bristolla_, or possibly for

_Vincentina et Bristolla_. Both quartz and fluor are found at Clifton. In

that case Vincentina and Bristolla refer to these two minerals, and if so

one would expect Bristolla to be the Bristol Diamond, and Vincentina to be

the comparatively rare Fluor spar from that locality."

At the end of the edition of 1653 of Sir Hugh Plat's _Jewel House of Art

and Nature_, is appended _A rare and excellent Discourse of Minerals,

Stones, Gums, and Rosins; with the vertues and use thereof_, By D. B.

_Gent_. Here, p. 218, we read:

"We have in England a stone or mineral called a Bristol stone (because {41}

many are found thereabouts) which much resembles the Adamant or Diamond,

which is brought out of Arabia and Cyprus; but as it is wanting of the same

hardnesse, so falls it short of the like vertues."

[121] PAGE 48, LINE 18. Page 48, line 19. _Crystallus._--Rock-crystal.

Quartz. Pliny's account of it (Philemon Holland's version of 1601, p. 604)

in book xxxvii., chap, ii., is:

"As touching Crystall, it proceedeth of a contrarie cause, namely of cold;

for a liquor it is congealed by extreame frost in manner of yce; and for

proofe hereof, you shall find crystall in no place els but where the winter

snow is frozen hard: so as we may boldly say, it is verie yce and nothing

else, whereupon the Greeks have give it the right name Crystallos, _i._

Yce.... Thus much I dare my selfe avouch, that crystall groweth within

certaine rockes upon the Alps, and these so steepe and inaccessible, that

for the most part they are constrained to hang by ropes that shall get it

forth."

[122] PAGE 48, LINE 18. Page 48, line 20. _Similes etiam attrahendi vires

habere videntur vitrum ... sulphur, mastix, & cera dura sigillaris._ If, as

shown above, the electric powers of diamond and ruby had already been

observed, yet Gilbert was the first beyond question to extend the list of

_electrics_ beyond the class of precious stones, and his discovery that

_glass_, _sulphur_, and _sealing-wax_ acted, when rubbed, like amber, was

of capital importance. Though he did not pursue the discovery into

mechanical contrivances, he left the means of that extension to his

followers. To Otto von Guericke we owe the application of sulphur to make

the first electrical machine out of a revolving globe; to Sir Isaac Newton

the suggestion of glass as affording a more mechanical construction.

Electrical attraction by natural products other than amber after they have

been rubbed must have been observed by the primitive races of mankind.

Indeed Humboldt in his _Cosmos_ (Lond., 1860, vol. i., p. 182) records a

striking instance:

"I observed with astonishment, on the woody banks of the Orinoco, in the

sports of the natives, that the excitement of electricity by friction was

known to these savage races, who occupy the very lowest place in the scale

of humanity. Children may be seen to rub the dry, flat and shining seeds or

husks of a trailing plant (probably a _Negretia_) until they are able to

attract threads of cotton and pieces of bamboo cane."

[123] PAGE 48, LINE 23. Page 48, line 25. _arsenicum_.--This is _orpiment_.

See the _Dictionary of metallick words_ at the end of Pettus's _Fleta

Minor_.

[124] PAGE 48, LINE 23. Page 48, line 26. _in convenienti coelo

sicco_.--The observation that only in a dry climate do rock-salt, mica, and

rock-alum act as electrics is also of capital importance. Compare page 56.

[125] PAGE 48, LINE 27. Page 48, line 31. _Alliciunt hæc omnia non festucas

modo & paleas._--Gilbert himself marks the importance of this discovery by

the large asterisk in the margin. The logical consequence was his invention

of the first _electroscope_, the _versorium non magneticum_, made of any

metal, figured on p. 49.

[126] PAGE 48, LINE 34. Page 48, line 36. _quod tantum siccas attrahat

paleas, nec folia ocimi._--This silly tale that basil leaves were not

attracted by amber arose in the _Quæstiones Convivales_ of Plutarch. It is

repeated by Marbodeus and was quoted by Levinus Lemnius as true. Gilbert

denounced it as nonsense. Cardan (_De Subtilitate_, Norimb., 1550, p. 132)

had already contradicted the fable. "Trahit enim," he says, "omnia levia,

paleas, festucas, ramenta {42} tenuia metallorum, & ocimi folia, perperam

contradicente Theophrasto." Sir Thomas Browne specifically refuted it. "For

if," he says, "the leaves thereof or dried stalks be stripped into small

strawes, they arise unto Amber, Wax, and other Electricks, no otherwise

then those of Wheat or Rye."

[127] PAGE 48, LINE 34. Page 48, line 38. _Sed vt poteris manifestè

experiri...._

Gilbert's experimental discoveries in electricity may be summarized as

follows:

1. The generalization of the class of _Electrics_.

2. The observation that damp weather hinders electrification.

3. The generalization that electrified bodies attract everything,

including even metals, water, and oil.

4. The invention of the non-magnetic _versorium_ or electroscope.

5. The observation that merely warming amber does not electrify it.

6. The recognition of a definite class of _non-electrics_.

7. The observation that certain electrics do not attract if roasted or

burnt.

8. That certain electrics when softened by heat lose their power.

9. That the electric effluvia are stopped by the interposition of a

sheet

of paper or a piece of linen, or by moist air blown from the mouth.

10. That glowing bodies, such as a live coal, brought near excited amber

discharge its power.

11. That the heat of the sun, even when concentrated by a burning mirror,

confers no vigour on the amber, but dissipates the effluvia.

12. That sulphur and shell-lac when aflame are not electric.

13. That polish is not essential for an electric.

14. That the electric attracts bodies themselves, not the intervening

air.

15. That flame is not attracted.

16. That flame destroys the electrical effluvia.

17. That during south winds and in damp weather, glass and crystal, which

collect moisture on their surface, are electrically more interfered

with than amber, jet and sulphur, which do not so easily take up

moisture on their surfaces.

18. That pure oil does not hinder production of electrification or

exercise

of attraction.

19. That smoke is electrically attracted, unless too rare.

20. That the attraction by an electric is in a straight line toward it.

[128] PAGE 48, LINE 35. Page 48, line 39. _quæ sunt illæ

materiæ._--Gilbert's list of electrics should be compared with those given

subsequently by Cabeus (1629), by Sir Thomas Browne (1646), and by Bacon.

The last-named list occurs in his _Physiological Remains_, published

posthumously in 1679; it contains nothing new. Sir Thomas Browne's list is

given in the following passage, which is interesting as using for the first

time in the English language the noun _Electricities_:

"Many stones also both precious and vulgar, although terse and smooth, have

not this power attractive; as Emeralds, Pearle, Jaspis, Corneleans, Agathe,

Heliotropes, Marble, Alablaster, Touchstone, Flint and Bezoar. Glasse

attracts but weakely though cleere, some slick stones and thick glasses

indifferently: Arsenic but weakely, so likewise glasse of Antimony, but

Crocus Metallorum not at all. Saltes generally but weakely, as Sal Gemma,

Alum, and also Talke, nor very discoverably by any frication: but if gently

warmed at the fire, and wiped with a dry cloth, they will better discover

their Electricities." _(Pseudodoxia Epidemica_, p. 79.)

In the _Philosophical Transactions_, vol. xx., p. 384, is _A Catalogue of

Electrical Bodies_ by the late Dr. Rob. Plot. It begins "Non solum

succinum," and ends "alumen rupeum," being identical with Gilbert's list

except that he calls "Vincentina & Bristolla" by the name "Pseudoadamas

Bristoliensis."

[129] PAGE 49, LINE 25. Page 49, line 30. _non dissimili modo._--The

_modus_ {43} _operandi_ of the electrical attractions was a subject of much

discussion; see Cardan, _op. citat._

[130] PAGE 51, LINE 2. Page 51, line 1. _appellunt._--This appears to be a

misprint for _appelluntur_.

[131] PAGE 51, LINE 22. Page 51, line 23. _smyris._--Emery. This substance

is mentioned on p. 22 as a magnetic body.

[132] PAGE 52, LINE 1. Page 51, line 46. _gemmæ ... vt Crystallus, quæ ex

limpidâ concreuit._ See the note to p. 48.

[133] PAGE 52, LINE 30. Page 52, line 32. _ammoniacum._--Ammoniacum, or

Gutta Ammoniaca, is described by Dioscorides as being the juice of a ferula

grown in Africa, resembling galbanum, and used for incense.

"_Ammoniack_ is a kind of Gum like Frankincense; it grows in Lybia, where

_Ammon's_ Temple was." Sir Hugh Plat's _Jewel House of Art and Nature_ (Ed.

1653, p. 223).

[134] PAGE 52, LINE 38. Page 52, line 41. _duæ propositæ sunt causæ ...

materia & forma._--Gilbert had imbibed the schoolmen's ideas as to the

relations of matter and form. He had discovered and noted that in the

magnetic attractions there was always a verticity, and that in the

electrical attractions the rubbed electrical body had no verticity. To

account for these differences he drew the inference that since (as he had

satisfied himself) the magnetic actions were due to _form_, that is to say

to something immaterial--to an "imponderable" as in the subsequent age it

was called--the electrical actions must necessarily be due to _matter_. He

therefore put forward his idea that a substance to be an electric must

necessarily consist of a concreted humour which is partially resolved into

an effluvium by attrition. His discoveries that electric actions would not

pass through flame, whilst magnetic actions would, and that electric

actions could be screened off by interposing the thinnest layer of fabric

such as sarcenet, whilst magnetic actions would penetrate thick slabs of

every material except iron only, doubtless confirmed him in attributing the

electric forces to the presence of these effluvia. See also p. 65. There

arose a fashion, which lasted over a century, for ascribing to "humours,"

or "fluids," or "effluvia," physical effects which could not otherwise be

accounted for. Boyle's tracts of the years 1673 and 1674 on "effluviums,"

their "determinate nature," their "strange subtilty," and their "great

efficacy," are examples.

[135] PAGE 53, LINE 9. Page 53, line 11. _Magnes vero...._--This passage

from line 9 to line 24 states very clearly the differences to be observed

between the magnetical and the electrical attractions.

[136] PAGE 53, LINE 36. Page 53, line 41. _succino calefacto._--Ed. 1633

reads _succinum_ in error.

[137] PAGE 54, LINE 9. Page 54, line 11. _Plutarchus ... in quæstionibus

Platonicis._--The following Latin version of the paragraph in _Quæstio

sexta_ is taken from the bilingual edition publisht at Venice in 1552, p.

17 _verso_, liber vii., cap. 7 (or, _Quæstio Septima_ in Ed. Didot, p.

1230).

"Electrum uero quæ apposita sunt, nequaquàm trahit, quem admodum nec lapis

ille, qui sideritis nuncupatur, nec quicqu[=a] à seipso ad ea quæ in

propinquo sunt, extrinsecus assilit. Verum lapis magnes effluxiones quasdam

tum graves, tum etiam spiritales emittit, quibus aer continuatus & iunctus

repellitur. Is deinceps alium sibi proximum impellit, qui in orbem circum

actus, atque ad inanem locum rediens, ui ferrum fecum rapit & trahit. At

Electrum uim quandam flammæ similem & spiritalem continet, quam quidem {44}

tritu summæ partis, quo aperiuntur meatus, foras eijcit. Nam leuissima

corpuscula & aridissima quæ propè sunt, sua tenuitate atque imbecillitate

ad seipsum ducit & rapit, cum non sit adeo ualens, nec tantum habeat

ponderis & momenti ad expellendam aeris copiam, ut maiora corpora more

Magnetis superare possit & uincere."

[138] PAGE 54, LINE 16. Page 54, line 18. _Gemma Vincentij rupis._--See the

note to p. 48 _supra_, where the name _Vincentina_ occurs.

[139] PAGE 54, LINE 30. Page 54, line 35. _orobi._--The editions of 1628

and 1633 read _oribi_.

[140] PAGE 55, LINE 34. Page 55, line 42. _in euacuati._--The editions of

1628 and 1633 read _inevacuati_.

[141] PAGE 58, LINE 21. Page 58, line 25. _assurgentem vndam ... declinat

ab F._--These words are wanting in the Stettin editions.

[142] PAGE 59, LINE 9. Page 59, line 9. _fluore._--This word is conjectured

to be a misprint for _fluxu_ but it stands in all editions.

[143] PAGE 59, LINE 22. Page 59, line 25. _Ruunt ad electria._--This

appears to be a slip for _electrica_, which is the reading of the editions

of 1628 and 1633.

[144] PAGE 60, LINE 7. Page 60, line 9. _tan[=q] materiales radij._--The

suggestion here of material _rays_ as the _modus operandi_ of electric

forces seems to foreshadow the notion of electric lines of force.

[145] PAGE 60, LINE 10. Page 60, line 12. _Differentia inter magnetica &

electrica._--Though Gilbert was the first systematically to explore the

differences that exist between the magnetic attraction of iron and the

electric attraction of all light substances, the point had not passed

unheeded, for we find St. Augustine, in the _De Civitate Dei_, liber xxi.,

cap. 6, raising the question why the loadstone which attracts iron should

refuse to move straws. The many analogies between electric and magnetic

phenomena had led many experimenters to speculate on the possibility of

some connexion between electricity and magnetism. See, for example,

Tiberius Cavallo, _A Treatise on Magnetism_, London, 1787, p. 126. Also the

three volumes of J. H. van Swinden, _Receuil de Mémoires sur l'Analogie de

Electricité et du Magnétisme_, La Haye, 1784. Aepinus wrote a treatise on

the subject, entitled _De Similitudine vis electricæ et magneticæ_

(Petropolis, 1758). This was, of course, long prior to the discovery, by

Oersted, in 1820, of the real connexion between magnetism and the electric

current.

[146] PAGE 60, LINE 25. Page 60, line 31. _Coitionem dicimus, non

attractionem._--See the remarks, at the outset of these Notes, on Gilbert's

definitions of words.

[147] PAGE 60, LINE 33. Page 61, line 1. _Orpheus in suis

carminibus._--This passage is in the chapter [Greek: Lithika] of Orpheus,

verses 301 to 327. See Note to p. 11, line 19.

[148] PAGE 61, LINE 15. Page 61, line 19. _Platonis in Timæo opinio_.--The

passage runs (edition Didot, vol. ii., p. 240, or Stephanus, p. 80, C.):

[Greek: Kai dê kai ta tôn hudatôn panta rheumata eti de ta tôn keraunôn

ptômata kai ta thaumazomena êlektrôn peri tês helxeôs kai tôn Hêrakleiôn

lithôn, pantôn toutôn holkê men ouk estin oudeni pote, to de kenon einai

mêden periôthein te hauta tauta eis allêla, to te diakrinomena kai

sunkrinomena pros tên hautôn diameibomena hedran hekasta ienai panta,

toutois tois pathêmasi pros allêla sumplechtheisi tethaumatourgêmena tôi

kata tropon zêtounti phanêsetai.]

[149] PAGE 61, LINE 30. Page 61, line 38. The English version of the lines

of Lucretius is from Busby's translation.

[150] PAGE 62, LINE 5. {45} Page 62, line 7. _Iohannes Costæus

Laudensis._--Joannes Costa, of Lodi, edited Galen and Avicenna. He also

wrote a _De universali stirpium Natura_ (Aug. Taurin., 1578).

[151] PAGE 63, LINE 3. Page 63, line 4. _Cornelius Gemma 10.

Cosmocrit._--This refers to the work _De Naturæ Divinis Characterismis ...

Libri ii. Avctore D. Corn. Gemma_ (Antv., 1575, lib. i., cap. vii., p.

123).

"Certè vt à magnete insensiles radij ferrum ad se attrahunt, ab echineide

paruo pisciculo sistuntur plena nauigia, à catoblepa spiritu non homines

solùm, sed & alta serpentum genera interimuntur, & saxa dehiscunt."

See also Kircher's _Magneticum Naturæ Regnum_ (Amsterodami, 1667, p. 172),

Sectio iv., cap. iii., De Magnete Navium, quæ Remora seu Echeneis dicitur.

See the note to p. 7, line 21.

[152] PAGE 63, LINE 6. Page 63, line 7. _Guilielmus Puteanus._--Puteanus

(Du Puys) wrote a work _De Medicamentorum quomodocunque Purgantium

Facultatibus_, Libri ii. (Lugd., 1552), in which he talks vaguely about the

substantial "form" of the magnet, and quotes Aristotle and Galen.

[153] PAGE 63, LINE 21. Page 63, line 25. _Baptistæ Portæ._--The passage in

the translation is quoted from the English version of 1658, pp. 191, 192.

[154] PAGE 64, LINE 4. Page 64, line 9. _Eruditè magis Scaliger._--Gilbert

pokes fun at Scaliger, whose "erudite" guess (that the motion of iron to

the magnet was that of the offspring toward the parent) is to be found in

his book _De Subtilitate, ad Cardanum_, Exercitatio CII. (Lutetiæ, 1557, p.

156 _bis_).

[155] PAGE 64, LINE 7. Page 64, line 11. _Diuus Thomas._--On p. 3 Gilbert

had already spoken of St. Thomas Aquinas as a man of intellect who would

have added more about the magnet had he been more conversant with

experiments. The passage here quoted is from the middle of Liber vii. of

his commentaries on the _de Physica_ of Aristotle, _Expositio Diui Thome

Aquinatis Doctoris Angelici super octo libros Physicorum Aristotelis_, etc.

(Venice, Giunta edition, 1539, p. 96 _verso_, col. 2).

[156] PAGE 64, LINE 16. Page 64, line 24. _Cardinalis etiam

Cusanus._--Cardinal de Cusa (Nicolas Khrypffs) wrote a set of dialogues on

Statics, _Nicolai Cusani de staticis experimentis dialogus_ (1550), of

which an English version appeared in London in 1650 with the title, _The

Idiot in four books; the first and second of wisdom, the third of the

minde, the fourth of statick experiments. By the famous and learned C.

Cusanus._ In the fourth book _of statick Experiments, Or experiments of the

Ballance_, occurs (p. 186) the following:

"_Orat._ Tell me, if thou hast any device whereby the vertues of stones

may be weighed.

"_Id._ I thinke the vertue of the Load-stone might be weighed, if

putting some Iron in one scale, and a Load-stone in the other, untill

the ballance were even, then taking away the Load-stone, and some other

thing of the same weight being put into the scale, the Load-stone were

holden over the Iron, so that that scale wou'd begin to rise; by reason

of the Load-stones attraction of the Iron, then take out some of the

weight of the other scale, untill the scale wherein the iron is, doe

sinke againe to the æquilibrium, or equality still holding the

Load-stone unmovable as it was; I beleeve that by weight of what was

taken out of the contrary scale, one might come proportionably to the

weight of the vertue or power of the Load-stone. And in like manner,

the vertue of a Diamond, might be found hereby, because {46} they say

it hinders the Load-stone from drawing of Iron; and so other vertues of

other stones, consideration, being alwayes had of the greatnesse of the

bodyes, because in a greater body, there is a greater power and

vertue."

In the 1588 edition of Baptista Porta's _Magiæ Naturalis Libri xx._, in

lib. vii., cap. xviii., occurs the description of the use of the balance to

which Gilbert refers.

[157] PAGE 67, LINE 21. Page 67, line 22. _aëris rigore._--All editions

read thus, but the sense seems to require _frigore_.

[158] PAGE 67, LINE 27. Page 67, line 31. _Fracastorius._--See his _De

Sympathia_, lib. i., cap. 5 (Giunta edition, 1574, p. 60).

[159] PAGE 68, LINE 5. Page 68, line 6. _Thaletis Milesij._--See the note

to p. 11, line 26.

[160] PAGE 68, LINE 30. Page 68, line 35. _Ità coitio magnetica actus est

magnetis, & ferri, non actio vnius._--See the introductory remarks to these

notes. There is a passage in Scaliger's _De Subtilitate ad Cardanum_

(Exercitat. CII., cap. 5, p. 156 _op. citat._) which may be compared with

Gilbert's for its use of Greek terms: "Nã cùm uita dicatur actus animæ,

acceptus est abs te actus pro actione. Sed actus ille est [Greek:

entelecheia], nõ autem [Greek: ergon]. At Magnetis attractio est [Greek:

ergon], non aut[~e] [Greek: entelecheia]." To which Gilbert retorts: "non

actio unius, utriusque [Greek: entelecheia]; non [Greek: ergon], [Greek:

sunentelecheia] et conactus potius quam sympathia." He returns on p. 70 to

the attack on Scaliger's metaphysical notions. There is a parallel passage

in the _Epitome Naturalis Scientiæ_ of Daniel Sennert (Oxoniæ, 1664), in

the chapter _De Motu_.

[161] PAGE 71, LINE 4. Page 71, line 8. _vt in 8. physicorum Themistius

existimat._--See _Omnia Themistii Opera_ (Aldine edition, 1533, p. 63),

Book 8 of his Paraphrase on Aristotle's _Physica_.

[162] PAGE 71, LINE 9. Page 71, line 14. _Quod verò Fracastorius._--_Op.

citat._, lib. i., cap. 7, p. 62 _verso_.

[163] PAGE 73, LINE 2. Page 73, line 2. _si A borealis._--The editions of

1628 and 1633 omit the twelve words next following.

[164] PAGE 73, LINE 9. Page 73, line 11. _ex minera._--_Minera_ is not a

recognized word, even in late Latin. It occurs again, p. 97, line 12.

[165] PAGE 77, LINE 2. Page 77, line 2. _multo magis._--This is an _à

fortiori_ argument. It is interesting to find Gilbert comparing the

velocity of propagation of magnetic forces in space with the velocity of

light. The parallel is completed in line 13 by the consideration that as

the rays of light require to fall upon an object in order that they may

become visible, so the magnetic forces require a magnetic object in order

to render their presence sensible.

[166] PAGE 78, LINE 14. Page 78, line 16. _Orbem terrarum

distinguunt._--The editions of 1628 and 1633 here add a figure of a globe

marked with meridians and parallels of latitude, but with an erroneous

versorium pointing to the south. These editions also both read

_existentiam_ for the word _existentium_ in line 20.

[167] PAGE 83, LINE 5. Page 83, line 5. _magnes longior maiora pondera

ferri attollit._--Gilbert discovered the advantage, for an equal mass of

loadstone, of an elongated shape. It is now well known that the specific

amount of magnetism retained by elongated forms exceeds that in a short

piece of the same material subjected to equal magnetizing forces.

[168] PAGE 83, LINE 24. Page 83, line 28. _Non obstant crassa

tabulata._--Gilbert has several times referred (_e.g._, on p. 77) to the

way in which magnetic forces penetrate solid bodies. The experimental

investigation in this chapter {47} is the more interesting because it shows

that Gilbert clearly perceived the shielding action of iron to be due to

iron conducting aside or diverting the magnetic forces.

[169] PAGE 85, LINE 26. Page 85, line 31. _non conveniant._--The editions

of 1628 and 1633 both read _et conveniant_.

[170] PAGE 86, LINE 3. Page 86, line 3. _illud quod exhalat._--Literally,

_that which exhales_, in the sense of that which escapes: but in modern

English the verb exhale in the active voice is now not used of the

substance that escapes, but is used of the thing which emits it. It must

therefore be rendered _that which is exhaled_ (_i.e._, breathed out).

[171] PAGE 86, LINE 13. Page 86, line 15. _Ita tota interposita moles

terrestris._--Gilbert's notion that the gravitational force of the moon in

producing the tides acts _through_ the substance of the earth may seem

curiously expressed. But the underlying contention is essentially true

to-day. The force of gravity is not cut off or screened off by the

interposition of other masses. A recent investigation by Professor

Poynting, F.R.S., has shown that so far as all evidence goes all bodies,

even the densest, are transparent with respect to gravitational forces.

[172] PAGE 86, LINE 18. Page 86, line 20. _Sed de æstus ratione

aliàs._--There is no further discussion of the tides in _De Magnete_. But a

short account is to be found in Gilbert's posthumous work _De Mundo nostro

Sublunari Philosophia nova_ (Amsterdam, Elzevir, 1651), in Lib. v., the

part which in the manuscript was left in English, and was turned into Latin

by his brother. It comprises about fifteen quarto pages, from Cap. X. to

Cap. XIX. inclusive, beginning with a characteristic diatribe against

Taisnier, Levinus Lemnius, and Scaliger. But in assigning causes he himself

goes wide of the mark. Proceeding by a process of elimination he first

shows that the moon's light cannot be the cause that impels the tides.

"Luna," he says, "non radio, non lumine, maria impellit. quomodo igitur?

Sane corporum conspiratione, acque (ut similitudine rem exponam) Magnetica

attractione." This cryptic utterance he proceeds to explain by a diagram,

and adds: "Quare Luna non tam attrahit mare, quàm humorem & spiritum

subterraneum; nec plus resistit interposita terra, quàm mensa, aut quicquam

aliud densum, aut crassum, magnetis viribus."

[173] PAGE 87, LINE 7. Page 87, line 9. _armatura._--Here this means the

cap or snout of iron with which the loadstone was armed. This is apparently

the first use of the term in this sense.

In the _Dialogues of Galileo_ (p. 369 of Salusbury's _Mathematical

Collections_, Dialogue iii.), Sagredus and Salviatus discuss the arming of

the loadstone, and the increased lifting power conferred by adding an iron

cap. Salviatus mentions a loadstone in the Florentine Academy which,

unarmed, weighed six ounces, lifting only two ounces, but which when armed

took up 160 ounces. Whereupon Galileo makes Salviatus say: "I extreamly

praise, admire, and envy this Authour, for that a conceit so stupendious

should come into his minde. ... I think him [_i.e._, Gilbert] moreover

worthy of extraordinary applause for the many new and true Observations

that he made, to the disgrace of so many fabulous Authours, that write not

only what they do not know, but whatever they hear spoken by the foolish

vulgar, never seeking to assure themselves of the same by experience,

perhaps, because they are unwilling to diminish the bulk of their Books."

[174] PAGE 87, LINE 12. Page 87, line 15. The reference to _lib._ 3 is {48}

a misprint for _lib._ 2. It is corrected in the edition of 1633, but not in

that of 1628.

[175] PAGE 87, LINE 17. Page 87, line 21. _conactu._--The editions of 1628

and 1633 read _conatu_.

[176] PAGE 88, LINE 2. Page 88, line 3. _Coitio verò non fortior._--This

heading to chap. xix., taken with the seven lines that follow, and the

contrast drawn between _unitio_ and _coitio_, throw much light on the

fundamental sense attached by Gilbert to the term _coitio_. It is here

clearly used in the sense of _mutual tendency toward union_. Note also the

contrasted use in chap. xx. of the verbs _cohære_ and _adhære_. Adhærence

connotes a one-sided force (an impossibility in physics), cohærence a

mutual force.

[177] PAGE 90, LINE 9. Page 90, line 9. _nempè vt alter polus maius pondus

arripiat._--This acute observation is even now not as well known as it

ought to be. Only so recently as 1861 Siemens patented the device of

fastening a mass of iron to one end of an electromagnet in order to

increase the power of the other end. The fact, so far as it relates to

permanent magnets was known to Servington Savery. See _Philos.

Transactions_, 1729, p. 295.

[178] PAGE 92, LINE 3. Page 92, line 4. _Suspendit in aëre ferrum Baptista

Porta._--Porta's experiment is thus described (_Natural Magick_, London,

1658, p. 204): "_Petrus Pellegrinus_ saith, he shewed in another work how

that might be done: but that work is not to be found. Why I think it

extream hard, I shall say afterwards. But I say it may be done, because I

have now done it, to hold it fast by an invisible band, to hang in the air;

onely so, that it be bound with a small thread beneath, that it may not

rise higher: and then striving to catch hold of the stone above, it will

hang in the air, and tremble and wag itself."

[179] PAGE 97, LINE 29. Page 97, line 33. _Sed quæri potest ..._--The

question here raised by Gilbert is whether the lifting-power of magnets of

equal quality is proportional to their weight. If a stone weighing a drachm

will lift a drachm, would a stone that weighs an ounce lift an ounce?

Gilbert erroneously answers that this is so, and that the lifting-power of

a loadstone, whether armed or unarmed, is proportional to its mass.

The true law of the tractive force or lifting-power of magnets was first

given in 1729 by James Hamilton (afterwards Earl of Abercorn) in a work

entitled _Calculations and Tables Relating to the Attractive Virtue of

Loadstones ... Printed_ [at London?] _in the Year_ 1729. (See also a paper

in the _Philos. Transactions_, 1729-30, vol. xxxvi., p. 245). This work

begins thus:

"The Principle upon which these Tables are formed, is this: That if Two

_Loadstones_ are perfectly Homogeneous, that is, if their Matter be of the

same Specifick Gravity, and of the same Virtue in all Parts of one Stone,

as in the other; and that Like Parts of their Surfaces are Cap'd or Arm'd

with Iron; then the Weights they sustain will be as the Squares of the Cube

Roots of the Weights of the _Loadstones_; that is, as their Surfaces."

Upon lifting-power see also D. Bernoulli, _Acta Helvetica_, iii., p. 223,

1758; P. W. Haecker, _Zur Theorie des Magnetismus_, Nürnberg, 1856; Van der

Willigen, _Arch. du Musée Teyler_, vol. iv., Haarlem, 1878 ; S. P.

Thompson, _Philos. Magazine_, July, 1888.

In the book of James Hamilton, p. 5, he mentions a small terrella weighing

139 English grains, which would sustain no less than 23,760 grains, and was

valued at £21 13s. 10¾d.

{49} In the _Musæum Septalianum_ of Terzagus (Dertonæ, 1664, p. 42) is

mentioned a loadstone weighing twelve ounces which would lift sixty pounds

of iron.

Sir Isaac Newton had a loadstone weighing 3 grains, which he wore in a

ring. It would lift 746 grains.

Thomson's _British Annual_, 1837, p. 354, gives the following reference:

"In the _Records of General Science_, vol. iii., p. 272, there is an

interesting description of a very powerful magnet which was sent from

Virginia in 1776 by the celebrated Dr. Franklin to Professor Anderson, of

Glasgow. It is now in the possession of Mr. Crichton. It weighs 2½ grains,

and is capable of supporting a load of 783 grains, which is equivalent to

313 times its own weight."

[180] PAGE 99, LINE 10. Page 99, line 11. _Manifestum est._--In this, as in

many other passages, Gilbert uses this expression in the sense that _it is

demonstrable_ rather than meaning that _it is obvious_: for the fact here

described is one that is not at all self-evident, but one which would

become plain when the experiment had been tried. For other instances of

this use of _manifestum_ see pages 144, line 20; 158, line 19; 162, line

10.

[181] PAGE 100, LINE 20. Page 100, line 24. _si per impedim[=e]ta ...

pervenire possunt._--All editions agree in this reading, but the sense

undoubtedly requires _non possint_. Compare p. 91, line 21.

[182] PAGE 102, LINE 4. Page 102, line 4. _capite_ 4.--This is a misprint

for _capite_ 40, and is retained in the later editions. In the quotation

from Baptista Porta, where the English version of 1658 is adhæred to, the

words "& deturbat eam" have been omitted by the translator.

[183] PAGE 107, LINE 16. Page 107, line 18. _Cardanus scribit._--The

alleged perpetual motion machine is mentioned in _De rerum varietate_,

_lib._ 9, cap. xlviii. (Basil., 1581, p. 641). See also the Note to p. 223.

For Peregrinus and for Taisnier, see the note to p. 5, lines 8 and 12.

[184] PAGE 107, LINE 19. Page 107, line 21. _Antonij de Fantis._--His work

is: _Tabula generalis scotice subtilitatis octo Sectionibus vniuersam

Doctoris Subtilis Periti[=a] c[=o]plect[=e]s: ab excellentissimo doctore

Antonio de F[=a]tis taruisino edita ..._ Lugd., 1530.

[185] PAGE 108, LINE 26. Page 108, line 31. _Cusani in staticis._--See the

note to p. 64, line 16.

[186] PAGE 108, LINE 33. Page 108, line 41. _Languidi ... tardiùs

acquiescunt._--The editions of 1628 and 1633 omit these seven words.

[187] PAGE 109, LINE 11. Page 109, line 13. _halinitro._--Either native

carbonate of soda or native carbonate of potash might be meant, but not

saltpetre. Scaliger, in his _De Subtilitate ad Cardanum_ (Lutet., 1557, p.

164), _Exercitatio_ CIII., 15, under the title, _Nitrum non est Salpetræ_,

says: "More tuo te, tuaque confundis. Salpetræ inter salis fossilis ponis

hîc. Mox Halinitrum inter salis, & nitri naturam, speciem obtinere."

"_Sal nitrum_ is salt which is boiled out of the earth, especially fat

earth, as in stables, or any place of excrements." (_A Chymicall Dictionary

explaining Hard Places and Words met withall in the Writings of Paracelsus

..._, Lond., 1650.)

[188] PAGE 109, LINE 20. Page 109, line 23. _arte ioculatoriâ._--Edition

1628, _joculatoriâ_; edition 1633, _jaculatoriâ_.

[189] PAGE 110, LINE 11. Page 110, line 12. _qualis fuit Antonij

denarius._--The Elizabethan version of Pliny (book xxxiii., ch. ix., p.

479) runs thus: {50} "To come now unto those that counterfeit money.

_Antonius_ whiles hee was one of the three usurping Triumvirs, mixed yron

with the Romane silver denier. He tempered it also with the brasen coine,

and so sent abroad false and counterfeit money."

Georgius Agricola (_De Natura Fossilium_, p. 646) says:

"Sed ea fraus capitalis est, non aliter ac eorum qui adulterinas monetas

cudunt, argento miscentes multam plumbi candidi portionem, aut etiam ferri,

qualis fuit Antonii denarius, ut Plinius memoriæ tradidit. Nunc dicam de

candido plumbo, nam majoris pretii est quàm aes. In quod plumbum album,

inquit Plinius, addita aeris tertia portione candidi adulteratur stannum."

[190] PAGE 111, LINE 3. Page 111, line 3. _Meminerunt Chatochitis lapis

Plinius, atque Iulius Solinus._--The passage in Pliny (English version of

1601, book xxxvii., ch. x., p. 625) runs:

"Catochitis is a stone proper unto the Island Corsica: in bignesse it

exceedeth ordinarie pretious stones: a wonderfull stone, if all be true

that is reported thereof, and namely, That if a man lay his hand thereon,

it will hold it fast in manner of a glewie gum."

[191] PAGE 111, LINE 7. Page 111, line 7. _Sagda vel Sagdo._--Albertus

Magnus in _De Mineralibus_ (Venet., 1542, p. 202) says:

"Sarda quem alij dicunt Sardo lapis est qui se habet ad tabulas ligni sicut

magnes ad ferr[=u], et ideo adhæret ita fortiter tabulis nauium quòd euelli

n[=o] possit, nisi abscindatur cum ipso ea pars tabulæ cui inhæserit, est

aut[=e] in colore purissimus nitens."

And Pliny (_op. citat._, p. 629):

"Sagda is a stone, which the Chaldeans find sticking to ships, and they say

it is greene as Porrets or Leekes."

[192] PAGE 111, LINE 8. Page 111, line 8. _Euace._--Evax, king of the

Arabs, is said to have written to Nero a treatise on the names, colours,

and properties of stones. See the note on Marbodæus, p. 7, line 20.

[193] PAGE 113, LINE 14. Page 113, line 19. _repulsus sit._ The words read

thus in all editions, but the sense requires _repulsa sint._

[194] PAGE 113, LINE 23. Page 113, line 29. _Electrica omnia alliciunt

cuncta, nihil omninò fugant vnquam, aut propellunt._ This denial of

electrical repulsion probably arose from the smallness of the pieces of

electric material with which Gilbert worked. He could hardly have failed to

notice it had he used large pieces of amber or of sealing-wax. Electrical

repulsion was first observed by Nicolas Cabeus, _Philosophia Magnetica_,

Ferrara, 1629; but first systematically announced by Otto von Guericke in

his treatise _Experimenta Nova (ut vocantur) Magdeburgica, de Vacuo Spatio_

(Amstel., 1672).

[195] PAGE 113, LINE 29. Page 113, line 37. _cùm de calore quid sit

disputabimus._--The discussion of the nature of heat is to be found in

Gilbert's _De Mundo nostro Sublunari_ (Amstel., 1651), lib. i., cap. xxvi.,

pp. 77-88.

[196] PAGE 115, LINE 23. Page 115, line 23. _trium vel quatuor

digitorum._--Here as in all other places in Gilbert, _digitus_ means a

finger's breadth, so that three or four digits means a length of two or

three inches, or from six to eight centimetres.

[197] PAGE 117, LINE 26. Page 117, line 25. _ille Thebit Bencoræ

trepidationis motus._

"Trepidation in the ancient Astronomy denotes a motion which in the

Ptolemaic system was attributed to the firmament, in order to account for

{51} several changes and motions observed in the axis of the world, and for

which they could not account on any other principle." (Barlow's

_Mathematical Dictionary_.)

[198] PAGE 118, LINE 10. Page 118, line 8. _cuspis is aut lilium._--Gilbert

uses _cuspis_ or _lilium_ always of the North-pointing end of the needle.

Sir Thomas Browne speaks of "the lilly or northern point"; but he differs

from Gilbert in saying "the _cuspis_ or Southern point" (_Pseudodoxia

Epidemica_, 1650, p. 46). Only in one place (p. 101, line 5) does Gilbert

speak of _cuspis meridionalis_. Everywhere else the south-pointing end is

called the _crux_.

[199] PAGE 118, LINE 15. Page 118, line 13. _nam æquè potens est._--Later

observation showed this view to be incorrect. The horizontal component of

the earth's magnetic field is not equally strong all over the globe, and

the sluggishness of the needle's return to its position of rest is not due

to the supporting pin becoming blunt with wear. The value of the horizontal

component is zero at the north magnetic pole, and increases toward the

magnetic equator. It is greatest near Singapore and in Borneo, being there

more than twice as great as it is at London. (See Captain Creak in _Report

of Voyage of H.M.S. Challenger, Physics and Chemistry_, vol. ii., part vi.,

1889.)

[200] PAGE 119, LINE 5. Page 119, line 2. _lapis._--Both Stettin editions

read _lapidis._

[201] PAGE 119, LINES 9-11. Page 119, lines 7-9. The gist of the whole book

is summarized in these lines. They furnish a cardinal example of that

inductive reasoning which was practist by Gilbert, and of which Bacon

subsequently posed as the apostle. Compare pages 41 and 211.

[202] PAGE 120, LINE 8. Page 120, line 5. _dicturi sumus_.--Change of

verticity is treated of in book iii., chap. x., pp. 137 to 140.

[203] PAGE 125, LINE 24. Page 125, line 29. _appositam._--All editions give

this word, though the sense requires _appositum._

[204] PAGE 128, LINE 9. Page 128, line 11. _non nimis longum._--The

editions of 1628 and 1633 read (wrongly) _minus_ instead of _nimis_.

[205] PAGE 130, LINE 12. Page 130, line 14. The word _hunc_ in the folio of

1600 is corrected in ink to _tunc_, and the Stettin editions both read

_tunc_.

[206] PAGE 132, LINE 9. Page 132, line 10. _minimus & nullius

ponderis._--The editions of 1628 and 1633 both wrongly read _est_ for _&_.

[207] PAGE 132, LINE 28. Page 133, line 1. _nutat._--The editions of 1628

and 1633 both wrongly read _mutat_.

[208] PAGE 134, LINE 22. Page 134, line 25. _in rectâ sphærâ._--The meaning

of the terms a _right_ or _direct sphere_, an _oblique sphere_ and a

_parallel sphere_ are explained by Moxon on pages 29 to 31 of his book _A

Tutor to Astronomy and Geography_ (Lond., 1686):

"A _Direct Sphere_ hath both the _Poles_ of the _World_ in the Horizon ...

It is called a _Direct Sphere_, because all the _Celestial_ Bodies, as

_Sun_, _Moon_, and _Stars_, &c. By the _Diurnal_ Motion of the _Primum

Mobile_, ascend directly Above, and descend directly Below the _Horizon_.

They that Inhabit under the _Equator_ have the _Sphere_ thus posited."

"An _Oblique Sphere_ hath the _Axis_ of the _World_ neither _Direct_ nor

_Parallel_ to the _Horizon_, but lies aslope from it."

"A _Parallel Sphere_ hath one _Pole_ of the _World_ in the _Zenith_, the

other in the _Nadir_, and the _Equinoctial_ Line in the _Horizon_."

[209] PAGE 136, LINE 1. Page 136, line 1. _præsenti._--The editions of 1628

and 1633 read _sequenti_, to suit the altered position of the figure.

[210] PAGE 137, LINE 24. {52} Page 137, line 28. _atque ille statim._--The

Stettin editions both wrongly read illi.

[211] PAGE 139. There is a curious history to this picture of the

blacksmith in his smithy striking the iron while it lies north and south,

and so magnetizing it under the influence of the earth's magnetism.

Woodcuts containing human figures are comparatively rare in English art of

the sixteenth century; a notable exception being Foxe's _Acts and

Monuments_ with its many crude cuts of martyrdoms. The artist who prepared

this cut of the smith took the design from an illustrated book of Fables by

one Cornelius Kiliani or Cornelius van Kiel entitled _Viridarium Moralis

Philosophiæ, per Fabulas Animalibus brutis attributas traditæ, etc._

(Coloniæ, 1594). This rare work, of which there is no copy in the British

Museum, is illustrated by some 120 fine copper-plate etchings printed in

the text. On p. 133 of this work is an etching to illustrate the fable

_Ferrarii fabri et canis_, representing the smith smiting iron on the

anvil, whilst his lazy dog sleeps beneath the bellows. The cut on p. 139 of

Gilbert gives, as will be seen by a comparison of the pictures just the

same general detail of forge and tools; but the position of the smith is

reversed right for left, the dog is omitted, and the words _Septrenio_ and

_Auster_ have been added.

[Illustration]

In the Stettin edition of 1628 the picture has again been turned into a

copper-plate etching separately printed, is reversed back again left for

right, while a compass-card is introduced in the corner to mark the

north-south direction.

In the Stettin edition of 1633 the artist has gone back to Kiliani's

original {53} plate, and has re-etched the design very carefully, but

reversing it all right for left. As in the London version of 1600, the dog

is omitted, and the words _Septentrio_ and _Auster_ are added. Some of the

original details--for example, the vice and one pair of pincers--are left

out, but other details, for instance, the cracks in the blocks that support

the water-tub, and the dress of the blacksmith, are rendered with slavish

fidelity.

It is perhaps needless to remark that the twelve copper-plate etchings in

the edition of 1628, and the twelve completely different ones in that of

1633, replace certain of the woodcuts of the folio of 1600. For example,

take the woodcut on p. 203 of the 1600 edition, which represents a simple

dipping-needle made by thrusting a versorium through a bit of cork and

floating it, immersed, in a goblet of water. In the 1633 edition this

appears, slightly reduced, as a small inserted copper-plate, with nothing

added; but in the 1628 edition it is elaborated into a full-page plate (No.

xi.) representing the interior, with shelves of books, of a library on the

floor of which stands the goblet--apparently three feet high--with a globe

and an armillary sphere; while beside the goblet, with his back to the

spectator, is seated an aged man, reading, in a carved armchair. This

figure and the view of the library are unquestionably

copied--reversed--from a well-known plate in the work _Le Diverse &

Artificiose Machine_ of Agostino Ramelli (Paris, 1558).

In the Emblems of Jacob Cats (_Alle de Wercken_, Amsterdam, 1665, p. 65) is

given an engraved plate of a smith's forge, which is also copied--omitting

the smith--from Kiliani's _Viridarium_.

[212] PAGE 140, LINE 2.. Page 140, line 2. _præcedenti._--This is so

spelled in all editions, though the sense requires _præcedente_.

[213] PAGE 141, LINE 21. Page 141, line 24. _quod in epistolâ quâdam

Italicâ scribitur._--The tale told by Filippo Costa of Mantua about the

magnetism acquired by the iron rod on the tower of the church of St.

Augustine in Rimini is historical. The church was dedicated to St. John,

but in the custody of the Augustinian monks. The following is the account

of it given by Aldrovandi, _Musæum Metallicum_ (1648, p. 134), on which

page also two figures of it are given:

"Aliquando etiam ferrum suam mutat substantiam, dum in magnetem

conuertitur, & hoc experientia constat, nam Arimini supra turrim templi S.

Ioannis erat Crux a baculo ferreo ponderis centum librarum sustentata, quod

tractu temporis adeò naturam Magnetis est adeptum, vt, illivs instar,

ferrum traheret: hinc magna admiratione multi tenentur, qua ratione ferrum,

quod est metallum in Magnetem, qui est lapis transmutari possit;

Animaduertendum est id à maxima familiaritate & sympathia ferri, & magnetis

dimanare cum Aristoteles in habentibus symbolum facilem transitum semper

admiserit. Hoc in loco damus imaginem frusti ferri in Magnetem transmutati,

quod clarissimo viro Vlyssi Aldrouando Iulius Caesar Moderatus diligens

rerum naturalium inquisitor communicauit; erat hoc frustum ferri colore

nigro, & ferrugineo, crusta exteriori quodammodo albicante." And further on

p. 557.

"Preterea id manifestissimum est; quoniam Arimini, in templo Sancti

Ioannis, fuit Crux ferrea, quæ tractu temporis in magnetem conuersa est, &

ab vno latere ferrum trahebat, & ab altero respuebat." See also Sir T.

Browne's _Pseudodoxia Epidemica_ (edition of 1650, p. 48), and Boyle's

tract, _Experiments and Notes about the Mechanical Production of Magnetism_

(London, 1676, p. 12).

{54} Another case is mentioned in Dr. Martin Lister's _A Journey to Paris_

(Lond., 1699, p. 83). "He [Mr. Butterfield] shewed us a Loadstone sawed off

that piece of the Iron Bar which held the Stones together at the very top

of the Steeple of _Chartres_. This was a thick Crust of Rust, part of which

was turned into a strong Loadstone, and had all the properties of a Stone

dug out of the Mine. _Mons. de la Hire_ has Printed a Memoir of it; also

Mons. _de Vallemont_ a Treatise. The very outward Rust had no Magnetic

Virtue, but the inward had a strong one, as to take up a third part more

than its weight unshod." Gassendi and Grimaldi have given other cases.

Other examples of iron acquiring strong permanent magnetism from the earth

are not wanting. The following is from Sir W. Snow Harris's _Rudimentary

Magnetism_ (London, 1872, p. 10).

"In the _Memoirs of the Academy of Sciences_ for 1731, we find an account

of a large bell at Marseilles having an axis of iron: this axis rested on

stone blocks, and threw off from time to time great quantities of rust,

which, mixing with the particles of stone and the oil used to facilitate

the motion, became conglomerated into a hardened mass: this mass had all

the properties of the native magnet. The bell is supposed to have been in

the same position for 400 years."

[214] PAGE 142, LINE 13. Page 142, line 15. _tunc planetæ & corpora

coelestia._--Gilbert's extraordinary detachment from all metaphysical and

ultra-physical explanations of physical facts, and his continual appeal to

the test of experimental evidence, enabled him to lift the science of the

magnet out of the slough of the dark ages. This passage, however, reveals

that he still gave credence to the _nativities_ of judicial Astrology, and

to the supposed influence of the planets on human destiny.

[215] PAGE 144, LINE 14. Page 144, line 14. _ijdem._--The editions of 1628

and 1633 erroneously read _iisdem_.

[216] PAGE 147, LINE 27. Page 147, line 29. _ex optimo aciario._--Gilbert

recommended that the compass-needle should be of the best steel. Though the

distinction between iron and steel was not at this time well established,

there is no reason to doubt that by _aciarium_ was meant edge-steel as used

for blades. Barlowe, in his _Magneticall Advertisements_ (Lond., 1616), p.

66, gives minute instructions for the fashioning of the compass-needle. He

gives the preference to a pointed oval form, and describes how the steel

must be hardened by heating to whiteness and quenching in water, so that it

is "brickle in a manner as glass it selfe," and then be tempered by

reheating it over a bar of red hot iron until it is let down to a blue

tint. Savery (_Philos. Trans._, 1729) appears to have been the first to

make a systematic examination of the magnetic differences between hard

steel and soft iron.

Instructions for touching the needle are given in the _Arte de Nauegar_ of

Pedro de Medina (Valladolid, 1545, lib. vi., cap. 1).

[217] PAGE 149, LINE 8. Page 149, line 9. _per multa sæcula._--Compare

Porta's assertion (p. 208, English edition) "iron once rubbed will hold the

vertue a hundred years." Clearly not a matter within the actual experience

of either Porta or Gilbert.

[218] PAGE 153, LINE 2. Page 153, line 2. _Cardani ab ortu stellæ in cauda

vrsæ._--What Cardan said (_De Subtilitate_, _Edit. citat._, p. 187) was:

"ortum stellæ in cauda ursæ minoris, quæ quinque partibus orientalior est

polo mundi, respicit."

[219] PAGE 153, LINE 21. Page 153, line 26. _sequitur quod versus terram

magnam, siue continentem ... à vero polo inclinatio magnetica

fiat._--Gilbert {55} goes on to point out how, at that date, all the way up

the west European coast from Morocco to Norway, the compass is deflected

eastward, or toward the elevated land. He argued that this was a universal

law.

In _Purchas his Pilgrimes_ (Lond., 1625), in the Narrative, in vol. iii.,

of Bylot and Baffin's Voyage of 1616, there is mentioned an island between

Whale-Sound and Smith's Sound, where there had been observed a larger

variation than in any other part of the world. Purchas, in a marginal note,

comments on this as follows: "Variation of the Compass 56° to the West,

which may make questionable D. Gilbert's rule, tom. 1., l. 2, c. 1, that

where more Earth is more attraction of the Compass happeneth by variation

towards it. Now the known Continents of Asia, &c., must be unspeakably more

than here there can be, & yet here is more variation then about Jepan,

Brasil, or Peru, &c."

Gilbert's view was in truth founded on an incomplete set of facts. At that

time, as he tells us, the variation of the compass at London was 11-1/3

degrees eastward. But he did not know of the secular change which would in

about fifty-seven years reduce that variation to zero. Still less did he

imagine that there would then begin a westward variation which in the year

1816 should reach 24° 30', and which should then steadily diminish so that

in the year 1900 it should stand at 16° 16' westward. For an early

discussion of the changes of the variation see vol. i. of the

_Philosophical Transactions_ (Abridged), p. 188. Still earlier is the

classical volume of Henry Gellibrand, _A Discovrse Mathematical on the

Variation of the Magneticall Needle_ (Lond., 1635). Gilbert heads chapter

iii. of book iiii. (p. 159) with the assertion _Variatio uniuscuiusque loci

constans est_, declaring that to change it would require the upheaval of a

continent. Gellibrand combats this on p. 7 of the work mentioned. He says:

"Thus hitherto (according to the Tenents of all our _Magneticall_

Philosophers) we have supposed the variations of all particular places

to continue one and the same. So that when a Seaman shall happly

returne to a place where formerly he found the same variation, he may

hence conclude he is in the same former _Longitude_. For it is the

Assertion of _Mr. Dr. Gilberts_. _Variatio vnicuiusq; Loci constans

est_, that is to say, the same place doth alwayes retaine the same

variation. Neither hath this Assertion (for ought I ever heard) been

questioned by any man. But most diligent magneticall observations have

plainely offred violence to the same, and proved the contrary, namely

that the variation is accompanied with a variation."

In 1637 Henry Bond wrote in the _Sea-Mans Kalendar_ that in the year 1657

the variation would be zero at London. Compare Bond's _Longitude Found_

(Lond., 1676, p. 3).

As to inconstancy of the variation in one place see further Fournier's

_Hydrographie_ (Paris, 1667, liv. xi., ch. 12, p. 413), and Kircher,

_Magnes_ (Colon. Agripp., 1643, p. 418).

[220] PAGE 157, LINE 4. Page 157, line 5. _perfecto._--Though this word is

thus in all editions, it ought to stand _perfectâ_, as in line 10 below.

[221] PAGE 157, LINE 11. Page 157, line 13. _varietas_, for _variatio_.

[222] PAGE 160, LINE 20. Page 160, line 23. _in Borrholybicum._--This name

for the North-west, or North-North-West, is rarely used. It is found on the

chart or windrose of the names of the winds on pp. 151 and 152 of the

_Mécometrie de l'Eyman_ of G. Nautonier (1602). Here the name

_Borrolybicus_ is given as a synonym for _Nortouest Galerne_, or [Greek:

Olumpias], while the two winds on the points next on the western and

northern sides respectively are called _Upocorus_ and _Upocircius_.

{56} In Swan's _Specvlvm Mundi_ (Camb., 1643, p. 174) is this explanation:

"Borrholybicus is the North-west wind."

In Kircher's _Magnes_ (Colon. Agripp., 1643, p. 434) is a table of the

names of the thirty-two winds in six languages, where _Borrolybicus_ is

given as the equivalent of _Maestro_ or _North-West_.

[223] PAGE 161, LINE 2. Page 161, line 2. _Insula in Oceano variationem non

mutat._--The conclusions derived from the magnetic explorations of the

Challenger expedition, 1873-1876, are briefly these: That in islands north

of the magnetic equator there is a tendency to produce a local

perturbation, attracting the north-seeking end of the needle downwards, and

horizontally towards the higher parts of the land; while south of the

magnetic equator, the opposite effects are observed. (See _Challenger

Reports, Physics and Chemistry_, vol. ii., part vi., _Report on the

Magnetical Results_ by Staff-Commander Creak, F.R.S.)

[224] PAGE 162, LINE 2. Page 162, line 3. _quarè & respectiuum punctum ...

excogitauit._--The passage referred to is in _The newe Attractiue_ of

Robert Norman (Lond., 1581), chap. vi.

"Your reason towards the earth carrieth some probabilitie, but I prove that

there be no _Attractive_, or drawing propertie in neyther of these two

partes, then is the _Attractive_ poynt lost, and falsly called the poynt

_Attractive_, as shall be proved. But because there is a certayne point

that the Needle alwayes respecteth or sheweth, being voide and without any

_Attractive_ propertie: in my judgment this poynt ought rather to bee

called the point Respective ... This Poynt _Respective_, is a certayne

poynt, which the touched Needle doth alwayes _Respect_ or shew ..."

[225] PAGE 165, LINE 2. Page 165, line 2. _De pyxidis nauticæ vsitatæ

compositione._--Gilbert's description of the usual construction of the

mariner's compass should be compared with those given by Levinus Lemnius in

_The Secret Miracles of Nature_ (London, 1658); by Lipenius in _Navigatio

Salomonis Ophiritica_ (Witteb., 1660, p. 333); and with that given in

Barlowe's _Navigators Supply_ (London, 1597). See also Robert Dudley's

_Dell' Arcano del Mare_ (Firenze, 1646).

[226] PAGE 165 deals with the construction; the process of magnetizing by

the loadstone had already been discussed in pp. 147 to 149. It is

interesting to see that already the magnetized part attached below the

compass-card was being specialized in form, being made either of two pieces

bent to meet at their ends, or of a single oval piece with elongated ends.

The marking of the compass-card is particularly described. It was divided

into thirty-two points or "winds," precisely as the earlier "wind-rose" of

the geographers, distinguisht by certain marks, and by a lily--or

fleur-de-lys--indicating the North. Stevin in the _Havenfinding Art_

(London, 1599), from which work the passage on p. 167 is quoted, speaking

on p. 20 of "the Instrument which we call the Sea-directorie, some the

nautical box, ... or the sea compasse," mentions the "Floure de luce"

marking the North.

The legend which assigns the invention of the compass to one Goia or Gioja

of Amalfi in 1302 has been already discussed in the Note to page 4. Gilbert

generously says that in spite of the adverse evidence he does not wish to

deprive the Amalfians of the honour of the construction adopted in the

compasses used in the Mediterranean. But Baptista Porta the Neapolitan, who

wrote forty years before Gilbert, discredited the legend. "_Flavius_ saith,

an Italian found it out first, whose name was _Amalphus_, born in our {57}

Campania. But he knew not the Mariners Card, but stuck the needle in a

reed, or a piece of wood, cross over; and he put the needles into a vessel

full of water that they might flote freely." (Porta's _Natural Magick_,

English translation, London, 1658, p. 206.) See also Lipenius (_op. citat._

p. 390).

The pivotting of the needle is expressly described in the famous _Epistle_

on the Magnet of Peter Peregrinus, which was written in 1269. Gasser's

edition, _Epistola Petri Peregrini ... de magnete_, was printed in Augsburg

in 1558. In Part II., cap. 2, of this letter, a form of instrument is

described for directing one's course to towns and islands, and any places

in fact on land or sea. This instrument consists of a vessel like a turned

box (or _pyxis_) of wood, brass, or any solid material, not deep, but

sufficiently wide, provided with a cover of glass or crystal. In its middle

is arranged a slender axis of brass or silver, pivotted at its two ends

into the top and the bottom of the box. This axis is pierced orthogonally

with two holes, through one of which is passed the steel needle, while

through the other is fixed square across the needle another stylus of

silver or brass. The glass cover was to be marked with two cross lines

north-south and east-west; and each quadrant was to be divided into ninety

degrees. This the earliest described pivotted compass was therefore of the

cross-needle type, a form claimed as a new invention by Barlowe in 1597.

The first suggestion of suspending a magnetic needle by a thread appears to

be in the _Speculum Lapidum_ of Camillus Leonardus (Venet., 1502, fig. k

ij, lines 25-31): "Nã tacto ferro ex una [=p]te magnetis ex opposita eius

[=p]te appropinquato fugat: ut ex[=p]i[~e]tia docet de acu appenso filo."

The earliest known examples of the "wind-rose" are those in certain

parchment charts preserved in the Biblioteca Marciana in Venice. These go

back to 1426 or 1436, the best being ascribed to Andrea Bianco. They have

the North indicated by a fleur-de-lys, a trident, a simple triangle, or a

letter T; while the East is distinguisht by a cross. The West is marked

with a P. (see Fincati, _op. citat._). The eight marks in order, clock

wise, run thus,

[Lily] (or T). G. [Cross] (or L) S. O. A (or L). P. M.

The letters correspond to the Italian names of the principal winds:

Tramontano North.

Greco North-East.

Levante East.

Sirocco South-East.

Ostro South.

Africo or Libeccio South-West.

Ponente West.

Maestro North-West.

Wind-roses marked with the names of the minor winds are found in

Nautonier's _Mécometrie de l'Eyman_ (Vennes, 1602-1604, pp. 151-152), and

Kircher's _Magnes Siue de Arte Magnetica_ (Colon. Agripp., 1643, p. 432).

The description above given of the early Venetian wind-roses _exactly_

describes the compass-card as depicted by Pedro de Medina in his _Arte de

Nauegar_ (Valladolid, 1545, folio lxxx.), in the sixth book entitled "las

aguias de navegar"; while in the _Breve compendio de la sphera_ of Martin

Cortes (Sevilla, 1551, cap. iii., _de la piedrayman_) a similar wind-rose,

without the letters, is found.

{58} In the _De Ventis et navigatione_ of Michaele Angelo Blondo (Venet.,

1546, p. 15) is given a wind-rose, described as "Pixis uel Buxolus

instrumentum et dux nauigantium," having twenty-six points inscribed with

the names of the winds, there being six between north and east, and six

between south and west, and only five in each of the other quadrants. In

the middle is a smaller wind-rose exactly like the early Italian ones just

mentioned.

In the _Della Guerra di Rhodi_ of Jacobo Fontano (Venet., 1545, pages

71-74) is a chapter _Dei Venti, e della Bvssola di nauicare di Giovanni

Quintino_, giving a wind-rose, and a table of the names of the winds, the

north being indicated by a pointer, at the cusp of which are seven stars,

and the west by an image of the sun. The other cardinal points are marked

with letters.

Barlowe, in _The Navigators Supply_ (Lond., 1597), speaks thus:

"The merueilous and diuine Instrument, called the _Sayling Compasse_

(being one of the greatest wonders that this World hath) is a Circle

diuided commonly into 32. partes, tearmed by our Seamen Windes,

_Rumbes_, or Points of Compasse."

It is a disputed point with whom the method of naming the winds originated.

Some ascribe it to Charlemagne. Michiel Coignet (_Instruction novvelle ...

touchant l'art de naviguer_, Anvers, 1581, p. 7) ascribes it to Andronicus

Cyrrhestes. See Varro, _De Re Rustica_, iii., 5, 17, and Vitruvius, i., 6,

Gilbert's complaint of the evil practice of setting the needles obliquely

beneath the card, with the intention of allowing for the variation, is an

echo of a similar complaint in Norman's _Newe Attractiue_. In chapter x. of

this work Norman thus enumerates the different kinds of compasses:

"Of these common Sayling Compasses, I find heere (in _Europa_) five

sundry sortes or sets. The first is of _Levant_, made in _Scicile_,

_Genoüa_, and _Venice_: And these are all (for the most parte) made

Meridionally, with the Wyers directlye sette under the South, and North

of the Compasse: And therefore, duely shewing the poynt _Respective_,

in all places, as the bare Needle. And by this Compasse are the Plats

made, for the most part of all the _Levants_ Seas.

"Secondly, there are made in _Danske_, in the Sound of _Denmarke_, and

in _Flanders_, that have the Wyers set at 3 quarters of a point to the

Eastwards of the North of the compasse, and also some at a whole point:

and by these Compasses they make both the Plats and Rutters for the

Sound.

"Thirdly, there hath beene made in this Countrey particulary, for Saint

_Nicholas_ and _Ruscia_, Compasses set at 3 seconds of a point, and the

first Plats of that Discoverie were made by this Compasse.

"Fourthly the Compasse made at _Sevill_, _Lisbone_, _Rochell_,

_Bourdeaux_, _Roan_, and heere in _England_, are moste commonly set at

halfe a point: And by this Compasse are the Plats of the East and West

_Indies_ made for their Pylotes, and also for our Coastes neere hereby,

as _France_, _Spayne_, _Portugall_, and _England_: and therefore best

of these Nations to bee used, because it is the most common sorte that

is generally used in these Coastes."

Bessard (_op. citat._, pages 22 and 48) gives cuts of compasses showing the

needle displaced one rumbe to the East.

Gallucci, in his _Ratio fabricandi horaria mobilia et permanentia cum

magnetica acu_ (Venet., 1596), describes the needle as inclined 10 degrees

from the south toward the south-west.

The frontispiece of the work of Pedro Nuñez, _Instrumenta Artis Navigandi_,

Basil., 1592, depicts a compass with the lily set one point to the east.

Reibelt, _De Physicis et Pragmaticis Magnetis Mysteriis_ (Herbipolis,

1731), depicts the compass with the needle set about 12 degrees to the East

of North. See also Fournier, _Hydrographie_ (Paris 1667); De Lanis,

_Magisterium Natvræ et Artis_ (Brixiæ, 1684); Milliet Deschales, _Cursus

seu Mundus {59} Mathematicus_ (Lugd., 1674). Both the latter works give

pictures of the compass-cards as used in South Europe, and in North Europe,

and of the various known shapes of needles.

[227] PAGE 168, LINE 29. Page 168, line 33. _Directio igitur inualidior est

propè polos._ Here as in many passages _direction_ means _the force which

directs_. A similar usage prevails with the nouns _variation_ and

_declination_, meaning frequently the force causing variation or

declination respectively.

PAGE 172, LINE 13. _perquirere._ The edition of 1633 reads _perquirero_, in

error.

[228] PAGE 172, LINE 29. Page 172, line 33. _Ad pyxidis nauticæ veræ &

meridionalis formam ... fiat instrumentum._--An excellent form of portable

meridian compass, provided with sights for taking astronomical

observations, is described by Barlowe (_The Navigators Supply_, London,

1597), and is depicted in an etched engraving. An identical engraving is

repeated in Dudley's _Arcano del Mare_ (Firenze, 1646). Gilbert's new

instrument was considerably larger.

[229] PAGE 174, LINE 19. Page 174, line 21. _addendo vel detrahendo

prostaphæresin._--"Prosthaphæresis, conflata dictione, ex additione et

subtractione speciebus logistices, nomen habet ab officio, quia vt in

semicirculo altero ad æquabilem motum adijcitur, ita in altero subtrahitur,

vt adparens motus ex æquabili taxetur: atque hinc fit, quòd quæ

Prosthaphæresis dicitur Ptolemæo, ea vulgò æquatio vocetur." (Stadius,

_Tabulæ Bergenses_, Colon. Agripp., 1560, p. 37.)

[230] PAGE 174, LINE 28. Page 174, line 31. _Stellæ Lucidæ._--According to

Dr. Marke Ridley (_Magneticall Animadversions_, London, 1617, p. 9), this

chapter xii. of book iv., with the Table of Stars, was written by Edward

Wright, the author of the Prefatory Epistle of _De Magnete_. Wright was

Lecturer on Navigation to the East India Company, and author of sundry

treatises on Navigation.

[231] PAGE 187, LINE 14. Page 187, line 16. _hic qui versus boream

constitit ... meridionalis est, non borealis, quem antè nos omnes

existimabant esse borealem._--Earlier on, on pages 15 and 125, Gilbert had

mentioned this point. His insistence caused Barlowe (_Magneticall

Aduertisements_, 1616, p. 4) to speak of the south-pointing end of the

needle as the "true North," and thereby drew on himself the animadversions

of Marke Ridley.

[232] PAGE 188, LINE 15. Page 188, line 16. _in rectâ sphærâ._--See note to

p. 134.

[233] PAGE 190, LINE 14. Page 190, line 19. _declinans in

Borealibus._--Dipping as it does in northern regions; that is, with the

north-seeking or true-south pole downward.

[234] PAGE 195, LINE 20. Page 195, line 24. _multa maiora pondera._--Many

greater weights. All editions read _multa_, but the sense requires _multo_:

"much greater weights."

[235] PAGE 196, LINE 10. Page 196, line 12. _constans est._--This must not

be read "is constant," for it is constant only in any given latitude.

[236] PAGE 196, LINE 15. Page 196, line 18. _De proportione declinationis

pro latitudinis ratione._--Gilbert here announces, and proceeds in the next

seven pages to develop, the proposition that to each latitude there

corresponds a constant dip to a particular number of degrees. If this were

accurately so, then a traveller by merely measuring the dip would be able

to ascertain, by calculation, by reference to tables, or by aid of some

geometrical appliance, {60} the latitude of the place. In this hope Gilbert

fought to perfect the dipping-needle; and he also worked out, on pages 199

and 200, an empirical theory, and a diagram. This theory was still further

developed by him, and given to Thomas Blundevile (see the Note to p. 240).

Briggs of Gresham College, on Gilbert's suggestion, calculated a table of

Dip and Latitude on this theory. It was found, however, that the observed

facts deviated more or less widely from the theory. Kircher (_Magnes_,

1643, p. 368) gives a comparative table of the computed and observed

values. Further discovery showed the method to be impracticable, and

Gilbert's hope remained unfulfilled.

[237] PAGE 197, LINE 18. Page 197, line 21. _progressionis centri._--Note

Gilbert's precision of phrase.

[238] PAGE 200, LINE 12. Page 200, line 11. _subintellig[=u]tur._--This is

printed _subintelligitur_, and is altered in ink in all copies of the folio

edition. The editions of 1628 and 1633 read _subintelliguntur_. Similarly

in line 14 the word _ducit_ has had a small _r_ added in ink, making it

read _ducitur_, as also the other editions.

[239] PAGE 203. This figure of the experiment with the simple dipping

needle suspended in water in a goblet is due to Robert Norman. In his _Newe

Attractiue_ (London, 1581, chap. vi.) he thus describes it:

"Then you shall take a deepe Glasse, Bowle, Cuppe, or other vessell,

and fill it with fayre water, setting it in some place where it may

rest quiet, and out of the winde. This done, cut the Corke

circumspectly, by little and little, untill the wyre with the Corke be

so fitted, that it may remain under the superficies of the water two or

three inches, both ends of the wyer lying levell with the superficies

of the water, without ascending or descending, like to the beame of a

payre of ballance beeing equalie poysed at both ends.

"Then take out of the same the wyer without mooving the Corke, and

touch it with the _Stone_, the one end with the South of the _Stone_,

and the other end with the North, and then set it againe in the water,

and you shall see it presentlie turne it selfe upon his owne Center,

shewing the aforesay'd _Declining_ propertie, without descending to the

bottome, as by reason it should, if there were any _Attraction_

downewards, the lower part of the water being neerer that point, then

the superficies thereof."

[240] PAGE 212, LINE 7. Page 212, line 8. _ex altera parte._--The sense

seems to require _et altera parte_, but all editions read _ex_.

[241] PAGE 213, LINE 1. Page 213, line 2. The passage here quoted from

Dominicus Maria Ferrariensis, otherwise known as the astronomer Novara,

does not occur in any known writing of that famous man. It is, however,

quoted as being by Novara in at least three other writings of the same

epoch. See the _Tabulæ secvndorum mobilium coelestium_ of Maginus (Venet.,

1585, p. 29, line 19 to p. 30, line 11); the _Eratosthenes Batavvs_ of

Willebrord Snell (Lugd. Batav., 1617, pp. 40-42); and the _Almagesti novi

(Pars Posterior)_ of Riccioli (Bonon., 1651, p. 348). The original document

appears to have perisht. See a notice by M. Curtze in Boncompagni's

_Bullettino di Bibliografia_, T. iv., April, 1871.

[242] PAGE 214, LINE 26. Page 214, line 31. _Philolaus Pythagoricus._

"Philolaüs a le premier dit que la terre se meut en cercle; d'autres

disent que c'est Nicétas de Syracuse."

"Les uns prétendent que le terre est immobile; mais Philolaüs le

pythagoricien dit qu'elle se meut circulairement autour du feu

(central) et suivant un cercle oblique, comme le soleil et la

lune."--(Chaignet, _Pythagore et la Philosophie pythagoricienne_,

Paris, 1873.)

It appears that the first of these _dicta_ is taken from Diogenes Laërt.,

viii. 85; and the second from Plutarch, _Placit. Philos._, III. 7. The

latter {61} passage may be compared with Aristotle, _De Coelo_, II. 13,

who, referring to the followers of Pythagoras, says: "They say that the

middle is fire, that the earth is a star, and that it is moved circularly

about this centre; and that by this movement it produces day and night."

[243] PAGE 214, LINE 34. Page 214, line 42. _Copernicus._--His work is _De

revolutionibus orbium coelestium, libri vi._ (Basil., 1566).

[244] PAGE 215, LINE 27. Page 215, line 24. _quæ ... in cælo varijs

distantijs collocata sunt._--This remark appears to be Gilbert's one

contribution to the science of Astronomy; the stars having previously been

regarded as fixed in the eighth sphere all at the same distance from the

central earth, around which it revolved.

[245] PAGE 220, LINE 6. Page 220, line 6. _quem nycthemeron vocamus._--The

1628 and 1633 editions read _nyctemoron_.

[246] PAGE 221, LINE 10. Page 221, line 11. _poli verè oppositi sint._--For

_verè_, the 1628 and 1633 editions read _rectæ_. All editions read _sint_,

though _sunt_ seems to make better sense.

[247] PAGE 223, LINE 7. Page 223, line 8. _ad telluris conformitatem._--The

word _conformitas_ is unknown in classical Latin.

[248] PAGE 223, LINE 16. Page 223, line 17. _Omitto quod Petrus Peregrinus

constanter affirmat, terrellam super polos suos in meridiano suspensam,

moveri circulariter integrâ revolutione 24 horis: Quod tamen nobis adhuc

videre non contingit; de quo motu etiam dubitamus._

This statement that a spherical loadstone pivotted freely with its axis

parallel to the earth's axis will of itself revolve on its axis once a day

under the control of the heavens, thus superseding clocks, is to be found

at the end of chap. x. of Peregrinus's _Epistola De Magnete_ (Augsb.,

1537).

Gilbert, who doubted this experiment because of the stone's own weight is

taken to task by Galileo, in the third of his Dialogues, for his qualified

admission.

"I will speak of one particular, to which I could have wished that

_Gilbert_ had not lent an ear; I mean that of admitting, that in case a

little Sphere of Loadstone might be exactly librated, it would revolve in

it self; because there is no reason why it should do so" (p. 376 of

Salusbury's _Mathematical Collections_, London, 1661). The Jesuit Fathers

who followed Gilbert, but rejected his Copernican ideas, pounced upon this

pseudo-experiment, as though by disproving it they had upset the Copernican

theory.

[249] PAGE 227, LINE 6. Page 227, line 7. This line is left out in the 1628

edition. In the 1633 edition it was also left out by the printer, and

subsequently printed in in the margin, being page 219 of that edition.

[250] PAGE 234, LINE 35. Page 234, line 40. _vt poli telluris respectus à

polis._--If it may be permitted to read _respectu_ for _respectus_ the

sense is improved, and the passage may then be translated thus: "that just

as it was needful ... that the poles of the Earth as to direction should be

23 degrees and more from the poles of the Ecliptick; so now, &c."

[251] PAGE 237, LINE 19. Page 237, line 22. _vt motus quidem obscuri

saluarentur._--It has been conjectured that _quidem_ is here a misprint for

_quidam_, but the adverb _quidem_ adds a satirical flavour to his argument

against the folly of those who held the doctrine of the moving spheres. The

verb _salvare_ does not occur in classical Latin.

[252] PAGE 240, LINE 13. Page 240, line 17. _à Copernico (Astronomiæ

instauratore)._--Gilbert was the first in England to uphold the doctrines

of {62} Copernicus as to the motion of the earth on its axis and its

revolution around the sun. He considered that his magnetic observations

brought new support to that theory, and his views are quoted with

approbation by Kepler, _Epitome Astronomiæ Copernicanæ_ ... Authore Ioanne

Keplero ... (Francofurti, 1635); and by Galileo, _Dialogus de Systemate

Mundi_ (Augustæ Treboc., 1635), an English translation of which appeared in

Salusbury's _Mathematical Collections and Translations_ (London, 1661, pp.

364 to 377).

For this the book _De Magnete_ was considered by many as heretical. Many of

the copies existing in Italy are found to be either mutilated or else

branded with a cross. For example, the copy in the library of the Collegio

Romano in Rome has book VI. torn out. Galileo states that the Book of

Gilbert would possibly never have come into his hands "if a Peripatetick

Philosopher, of great fame, as I believe to free his Library from its

contagion, had not given it me." In England Barlowe, in his _Magneticall

Aduertisements_ (1616), expressly repudiated Gilbert's Copernican notions,

while praising his discoveries in magnetism. Marke Ridley, while upholding

Gilbert's views, in his _Magneticall Animadversions_ (1617) did not

consider him "skilfull in Copernicus." The Jesuit writers, Cabeus, Kircher,

Fonseca, Grandamicus, Schott, Leotaudus, Millietus, and De Lanis, one and

all, who followed Gilbert in their magnetic writings, repudiated the idea

that the magnetism of the globe gave support to the heretical modern

Astronomy.

The works referred to are:

Cabeus, _Philosophia Magnetica, in qua Magnetis natura penitus explicatur

... auctore Nicolao Cabeo Ferrarensi Soc. Jesv._ (Ferrariæ, 1629).

Kircher, _Magnes, Siue de Arte Magnetica, Libri tres, Authore Athanasio

Kirchero ... e Soc. Iesv._ (Romæ, 1641).

Grandamicus, _Nova Demonstratio immobilitatis terræ petita ex virtute

magnetica_ (Flexiæ, 1645). This work is most beautifully illustrated with

copper-plate etchings of cupids making experiments with terrellas.

Schott, Gaspar, _Thaumaturgus Physicus_ (Herbipolis, 1659).

Leotaudus, _R. P. Vincentinii Leotavdi Delphinatis, Societ. Iesv.,

Magnetologia; in qva exponitvr Nova de Magneticis Philosophia_, (Lvgdvni,

1668).

Millietus (Milliet Deschales), _Cursus seu Mundus Mathematicus_ (Lugd.,

1674), _Tomus Primus, Tractatus de Magnete_.

De Lanis, _Magisterium Natvræ et Artis. Opus Physico-Mathematicvm P.

Francisci Tertii de Lanis, Soc. Jesv._ (Brixiæ, 1684).

[253] PAGE 240, LINE 24. Page 240, line 31. _hic finem & periodum

imponimus._

On February 13 [1601] Gilbert wrote to Barlowe (see _Magneticall

Aduertisements_, p. 88):

"I purpose to adioyne an appendix of six or eight sheets of paper to my

booke after a while, I am in hand with it of some new inventions, and I

would haue some of your experiments, in your name and inuention put into

it, if you please, that you may be knowen for an augmenter of that arte."

This he never did. Perhaps his appointment (in February, 1601) as chief

physician in personal attendance on the Queen interfered with the project;

or his death, of the plague, in 1603, intervened before his intention had

been carried into effect. But it is probable that the substance of the

proposed additions is to be found in the chapter, publisht in Gilbert's

lifetime, in Blundevile's _Theoriques of the seuen Planets_ (London, 1602),

thus described in the title-page of the work: "There is also hereto added,

{63} The making, description, and vse, of two most ingenious and necessarie

Instruments for Sea-men, to find out thereby the latitude of any Place vpon

the Sea or Land, in the darkest night that is, without the helpe of Sunne,

Moone, or Starre. First inuented by M. Doctor Gilbert, a most excellent

Philosopher, and one of the ordinarie Physicians to her Maiestie: and now

here plainely set downe in our mother tongue by Master Blundeuile."

Of these two instruments the first consists of a mechanical device, with

movable quadrants, to be cut out in cardboard, to be used in connection

with the diagram of spiral lines which Gilbert had given as a folding plate

between pages 200 and 201 of _De Magnete_. The intention was that the

Sea-man having found by experiment with a dipping-needle the amount of the

dip at any place, should by applying this diagram and its moving quadrants,

ascertain the latitude, according to the theory expounded in book V., chap.

VII.

The second instrument is a simplified portable dipping-needle, having the

degrees engraved on the inner face of a cylindrical brass ring.

Blundevile adds a Table, calculated by Briggs, and "annexed to the former

Treatise by _Edward Wright_, at the motion of the right Worshipful M.

Doctor _Gilbert_." This gives the values of the dip for different

latitudes, as calculated from Gilbert's empirical theory.

The other work, _De Mundo nostro Sublunari Philosophia Nova_, which Gilbert

left in manuscript at his death, does not contain any additional matter on

the magnetical investigations. Though it contains several direct references

to the _de Magnete_, and particularly to Book VI. on the rotation of the

earth, it is doubtful whether it was written after or before the

publication of _de Magnete_. On pages 137 to 144 of the posthumous edition

(Amsterdam, 1651) Gilbert refers to Peregrinus's alleged perpetually

revolving sphere, and denies its possibility. The greater part of the work

is an anti-Aristotelian discussion on Air, Meteorology, Astronomy, the

Winds, Tides, and Springs.

[Illustration]

* * * * *

{65} INDEX TO AUTHORITIES

Abano, Pietro di, 6.

Acosta, Josephus, 16.

Addison, Joseph, 35.

Aepinus, 44.

Aetius Amidenus, 6.

Affaytatus, 16, 39.

Agricola, Georgius, 25, 31, 36, 50.

Agrippa, H. Cornelius, 7.

Albategnius, 29.

Albertus Magnus, 6, 17, 38, 39, 40, 50.

Aldrovandi, Ulisse, 13, 36, 53.

Alexander Aphrodiseus, 3, 21.

Amatus Lusitanus, 6, 31.

Apponensis, Petrus, 6. _See_ Abano.

Aquinas, St. Thomas, 8, 45.

Ardoynis, Santes de, 6.

Aristotle, 4, 19, 25, 61.

Arnaldus de Villa nova, 6.

Augustani, 29.

Augustine, St., 4, 21, 43.

Aurifaber, 36.

Averroes, 29.

Avicenna, 6, 29, 30, 34.

Azuni, 8.

Bacon, Lord, 17, 42.

Barlow, Peter, 51.

Barlowe, William, 1, 2, 5, 9, 20, 28, 54, 56, 57, 58, 59, 62.

Beckmann, Johann, 19, 21, 32.

Bencora, or Ben Korrah (Thebitius), 30.

Benjamin, Park, 9, 11, 17.

Bernoulli, D., 48.

Bertelli, Timoteo, 11.

Bessard, Toussaincte de, 11, 58.

Bianco, Andrea, 57.

Blackmore, R. D., 24.

Blondo, Michaele Angelo, 1, 58.

Blondus, Flavius, 9.

Blundevile, Thomas, 8, 14, 60, 62, 63.

Bond, Henry, 55.

Borough, William, 2, 19.

Boyle, Robert, 43, 53.

Brasavolus, Antonius Musa, 6, 37.

Briggs, Henry, 60, 62.

Brough, R. B., 15.

Browne, Sir Thomas, 3, 37, 42, 51, 53.

Brunfels, Otho, 17, 30.

Buffum, W. A., 36.

Burton, Sir Richard F., 5.

Buttmann, 20, 32.

Buxtorf, 21.

Cabeus, Nicolas, 2, 42, 50, 62.

Cabot, Sebastian, 10, 16.

Caesar (or Cesare, Giulio), 53.

Calaber, Hannibal Rosetius, 6.

Calcagninus, Cælius, 8, 9.

Camden, William, 25.

Camera, Matteo, 8.

Cardan, Hieronymo, 23, 24, 26, 31, 36, 37, 41, 43, 49, 54.

Casaubon, 17.

Cats, Jacob, 53.

Cavallo, Tiberius, 44.

Chaignet, 60.

Charlemagne, 58.

Charles II., 23.

Charleton, Dr. W., 19.

Chladni, 26.

Coignet, Michiel, 58.

Collenuccio, Pandolfo, 9.

Conimbricenses, 11.

Cordus, Valerius, 20.

Cortes, Martin, 11, 24, 57.

Costa, Filippo, 16, 53.

Costa, Joseph. _See_ Acosta.

Costaeus, Joannes, of Lodi, 16, 45.

Creak, Captain, 51, 56.

Creech, T., 3.

Crescentius, 8.

Crollius, O., 29.

Curtius, 32.

Curtius, N., 29.

Curtze, M., 60.

Cusan (Cardinal de Cusa), 7, 45, 49.

Cyrrhestes, Andronicus, 58.

Davies, T. S., 20.

De la Hire, 54.

De Lanis, 58, 62.

Delaunay, 32.

Diogenes Laertius, 60.

Dioscorides, 30, 34, 35, 37, 38, 43.

Dominicus Maria Ferrariensis (Novara), 60.

Drake, Sir Francis, 19.

Dudley, Sir Robert, 19, 56, 59.

Du Puys (Puteanus), 38, 45.

{66}

Encelius, _or_ Entzelt, 7, 24, 26.

Erastus, Thomas, 7.

Euripides, 4.

Evax, 18, 50.

Evelyn, John, 23.

Fallopius, Gabriellus, 7, 29.

Fantis, Antonius de, 49.

Ficino, Marsiglio, 18.

Fincati, Admiral, 8.

Fletcher, L., 26.

Fonseca, 62.

Fontano, Jacopo, 58.

Forcellini, 2.

Fournier, G., 10, 20, 22, 55, 58.

Foxe, 52.

Fracastorio, Hieronymo, 12, 19, 29, 51.

Galen, 29, 30, 31, 35.

Galileo, 47, 62.

Gallucci, 58.

Gartias ab Horto, 13, 27, 39.

Gassendi, 54.

Gasser, Achilles P., 17, 57.

Geber, 29.

Gellibrand, Henry, 55.

Gemma, Cornelius, 45.

Gessner, 32.

Gilbert, Adrian, 20.

Gilbert, William, _de Mundo nostro Sublunari_, 47, 50, 63.

Gioia, _or_ Goia, 8, 56.

Glanvill, Joseph, 27.

Goebel, 36.

Goethe, 23.

Gonzalus Oviedus, 10.

Goppert, 35.

Goropius, Henricus Becanus, 10.

Gralath, D., 36.

Grandamicus, 62.

Grew, N., 23.

Grimaldi, 54.

Grotius, Hugo, 17.

Guericke, Otto von, 41, 50.

Haecker, P. W., 48.

Hakewill, G., 10.

Hakluyt, 13, 20.

Hali Abbas, 6, 17, 29.

Hamilton, James (Earl of Abercorn), 48.

Hariot, Thomas, 19.

Harris, Sir W. Snow, 21, 54.

Hartmann, P. J., 36.

Hellmann, G., 11.

Hermann, D., 36.

Hermolaus Barbarus, 7.

Hill, "Sir" John, 24, 38, 40.

Hood, T., 3.

Hues, Robert, 19.

Humboldt, 26, 31, 36, 41.

Hyginus, 36.

Isidore, St., 20, 21, 39.

Kendall, Abraham, 19.

Kepler, 62.

Kiel, Cornelius van (_or_ Kiliani), 52.

King, Edward, 26.

Kircher, Athanasius, 2, 21, 45, 55, 56, 57, 62.

Klaproth, 7, 8, 10, 20, 21, 22.

Kudrun, 15.

Langius, Joannes, 7.

Lanis, F. de, 58, 62.

Leonardus, Camillus, 7, 57.

Leotaudus, 62.

Levinus Lemnius, 38, 39, 41, 56.

Libri, 11.

Linna, Nicolas de, 14.

Lipenius, 13, 56.

Lister, Martin, 53.

Livio Sanuto, 10, 16.

Livy, 26.

Lonicer, Joannes, 30, 35, 38.

Löwy, 21.

Lucretius, 3, 44.

Maginus, 60.

Magnus, Sir Philip, 10.

Manardus, Joannes, 29.

Marbodeus, 6, 18, 21, 40, 41, 50.

Marcellus Empiricus, 6, 7.

Marco Polo, 10.

Martial, 36, 37.

Martin, Th. Henri, 20, 21, 32, 33.

Maskelyne, N. Story, 26.

Matthæus Silvaticus, 7.

Matthiolus, P., 5, 30, 35.

Maurolycus, Franciscus, 11.

Medina, Pedro de, 54, 57.

Mercator, 11, 14.

Merula, Gaudentius, 18, 19.

Merula, P., 15.

Miers, H. A., 40.

Migne, 19.

Milliet Deschales, 58, 62.

Monardus, Nicolas, 29.

Montanus, Joannes Baptista, 6.

Morris, William, 15.

Moxon, Joseph, 51.

Muellenhoff, K., 36.

Nautonier, G., 55, 57.

Neckham, Alexander of, 10.

Newton, Sir Isaac, 41.

Nicander, 38.

Nicolaus Myrepsius (_or_ Præpositas), 28, 35.

{67}

Nonius Petrus (_or_ Nuñez), 58.

Nordenskjold, 13.

Norman, Robert, 1, 11, 14, 28, 56, 58, 60.

Novara, Dominicus Maria, 60.

Offusius, Joannes Franciscus, 31.

Olaus Magnus, 12, 17.

Oribasius, 6.

Orpheus, 22, 44.

Ovid, 36.

Oviedo, Luis de, 28.

Oviedus, Gonzalus, 10.

Paley, F. A., 32.

Palm, G. A., 20.

Paracelsus (Bombast von Hohenheim), 7, 29.

Paulus Aeginæ, 30.

Paulus Jovius, 9.

Paulus Venetus (Fra Paolo Sarpi), 17.

Pepys, Samuel, 23.

Peregrinus, Petrus, 1, 11, 23, 48, 57, 61.

Pettus, Sir John, 23, 41.

Philolaus, 60.

Photius, 21.

Pictorio, G., 18.

Plancius, 14.

Plat, Sir Hugh, 5, 40, 43.

Plato, 4, 44.

Plautus, 2.

Pliny (Caius Plinius Secundus), 5, 20, 21, 22, 24, 25, 26, 27, 35, 36,

37, 38, 39, 41, 49, 50.

Plot, Rob., 42.

Plutarch, 26, 28, 41, 60.

Polo, Marco, 10.

Porta, Joannes Baptista (Giambattista della Porta), 4, 9, 16, 23, 46, 48,

54, 56, 57.

Poynting, J. H., 47.

Præpositas (_or_ Nicolas Myrepsius), 28, 35.

Ptolemy, 12, 28.

Purchas, 55.

Puteanus, Gulielmus, 38, 45.

Quintino, Giovanni, 58.

Ramelli, Agostino, 53.

Rammelsberg, 26.

Reibelt, 58.

Rhazes, 28, 29, 30.

Riccioli, 60.

Ridley, Marke, 3, 31, 59, 62.

Robertson, Rev. Alexander, 17.

Rücker, Arthur W., 15.

Ruellius, Joannes, 18, 30, 34, 37.

Rueus, Franciscus, 17.

Ruysch, Johan, 13.

Salusbury, T., 61, 62.

Santes de Ardoynis, 6.

Sanuto, Livio, 10, 16.

Sarpi, Fra Paolo, 16, 17.

Savery, Servington, 48, 54.

Scaliger, J. C., 26, 33, 34, 45, 46, 49.

Scheins, M., 32.

Schindler, A. Houtum, 33.

Schott, G., 62.

Schweigger, J. C., 32.

Sendel, Nathaniel, 36, 37.

Sennert, Daniel, 46.

Serapio, 6, 17, 30.

Severt, Jacques, 11.

Shakespeare, William, 22.

Siemens, 48.

Signorelli, 8.

Silvaticus, Matthæus, 7.

Smith, Dr. William, 26.

Snell, Willebrord, 60.

Solinus, Julius, 4, 37, 40.

Stadius, 59.

Stephanus, 32.

Stevinus, Simon, 56.

Strabo, 26.

Swan, John, 56.

Swinden, J. H. van, 44.

Taisnier, Joannes, 11, 47.

Terzagus, 36, 49.

Thalèn, 15.

Thales, 46.

Thebit Ben Korrah, 30, 50.

Themistius, 46.

Theophrastus, 32, 36, 38.

Thompson, Silvanus P., 48.

Thomson, R. D., 49.

Thorpe, T. E., 15.

Vallemont, Abbé de, 54.

Van Swinden, 44.

Varro, 58.

Venanson, Flaminius, 8.

Venner, Dr. T., 40.

Vergil, 2, 24.

Virgil, Polydore, 9.

Vitruvius, 58.

Waring, E. J., 29.

Watson, William, 38.

Wigand, Johann, 36.

Wilde, Henry, 15.

Willigen, van der, 48.

Wren, Sir Christopher, 23.

Wright, Edward, 19, 59, 62.

[Illustration]

CHISWICK PRESS: CHARLES WHITTINGHAM AND CO.

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On the magnet, magnetick bodies also, and on the great magnet the earth a new physiology, demonstrated by many arguments & experiments · 第 110 / 110 题

^1 _Bîjâdah_ is classified by Muhammad B. Mansûr (A.D. 1470) and by Ibn