They are distinguished in substance of parts and the accidents thereof, that is, in colour and figure; for Ice is a similary body, and h.o.m.ogeneous concretion, whose material is properly water, and but accidentally exceeding the simplicity of that element. But the body of Crystal is mixed; its ingredients many, and sensibly containeth those principles into which mixt bodies are reduced. For beside the spirit and mercurial principle it containeth a sulphur or inflamable part, and that in no small quant.i.ty; for besides its Electrick attraction, which is made by a sulphureous effluvium, it will strike fire upon percussion like many other stones, and upon collision with Steel actively send forth its sparks, not much inferiourly unto a flint. Now such bodies as strike fire have sulphureous or ignitible parts within them, and those strike best, which abound most in them. For these scintillations are not the accension of the air, upon the collision of two hard bodies, but rather the inflamable effluencies or vitrified sparks discharged from the bodies collided. For Diamonds, Marbles, Heliotropes and Agaths, though hard bodies, will not readily strike fire with a steel, much less with one another: Nor a Flint so readily with a Steel, if they both be very wet, for then the sparks are sometimes quenched in their eruption.
[Sidenote: _The Physical causes of liquation or melting of Mettals, etc._]
It containeth also a salt, and that in some plenty, which may occasion its fragility, as is also observable in Coral. This by the Art of Chymistry is separable, unto the operations whereof it is liable, with other concretions, as calcination, reverberation, sublimation, distillation: And in the preparation of Crystal, _Paracelsus_ [SN: _de Praeparationibus._] hath made a rule for that of Gemms. Briefly, it consisteth of parts so far from an Icie dissolution, that powerful menstruums are made for its emollition; whereby it may receive the tincture of Minerals, and so resemble Gemms, as _Boetius_ hath declared in the distillation of Urine; spirits of Wine and Turpentine; and is not only triturable, and reducible into powder, by contrition, but will subsist in a violent fire, and endure a vitrification. Whereby are testified its earthly and fixed parts. For vitrification is the last work of fire, and a fusion of the Salt and Earth, which are the fixed elements of the composition, wherein the fusible Salt draws the Earth and infusible part into one continuum, and therefore ashes will not run from whence the Salt is drawn, as bone ashes prepared for the Test of Metals. Common fusion in Metals is also made by a violent heat, acting upon the volatile and fixed, the dry and humid parts of those bodies; which notwithstanding are so united, that upon attenuation from heat, the humid parts will not fly away, but draw the fixed ones into fluor with them. Ordinary liquation in wax and oily bodies is made by a gentler heat, where the oyl and salt, the fixed and fluid principles will not easily separate. All which, whether by vitrification, fusion or liquation, being forced into fluent consistencies, do naturally regress into their former solidities. Whereas the melting of Ice is a simple resolution, or return from solid to fluid parts, wherein it naturally resteth.
As for colour, although Crystal in his pellucid body seems to have none at all, yet in its reduction into powder, it hath a vail and shadow of blew; and in its courser pieces, is of a sadder hue then the powder of Venice gla.s.s; and this complexion it will maintain although it long endure the fire. Which notwithstanding needs not move us unto wonder; for vitrified and pellucid bodies, are of a clearer complexion in their continuities, then in their powders and Atomical divisions. So _Stibium_ or gla.s.s of _Antimony_, appears somewhat red in gla.s.s, but in its powder yellow; so painted gla.s.s of a sanguine red will not ascend in powder above a murrey.
[Sidenote: _In Stone-pits and chalk-mines. Which seemeth to be Echinites decima Aldrovandi._ Musaei Metallici, lib. 4. _Rather Echinometrites, as best resembling the Echinometra found commonly on our Sea-sh.o.r.e._]
As for the figure of Crystal (which is very strange, and forced _Pliny_ to despair of resolution) it is for the most part hexagonal or six cornered; being built upon a confused matter, from whence as it were from a root angular figures arise, even as in the Amethyst and Basaltes.
Which regular figuration hath made some opinion, it hath not its determination from circ.u.mscription, or as conforming unto contiguities, but rather from a seminal root, and formative principle of its own, even as we observe in several other concretions. So the stones which are sometime found in the gall of a man, are most triangular and pyramidal, although the figure of that part seems not to co-operate thereto. So the _Asteria_ or _lapis stellaris_; hath on it the figure of a Star, so _Lapis Judaicus_ hath circular lines in length all down its body, and equidistant, as though they had been turned by Art. So that we call a Fayrie stone, and is often found in _gravel pits_ amongst us, being of an hemispherical figure, hath five double lines rising from the center of its basis, which if no accretion distract them, do commonly concur, and meet in the pole thereof. The figures are regular in many other stones, as in the Belemnites, _Lapis Anguinus_, _Cornu Ammonis_, and many more; as by those which have not the experience hereof may be observed in their figures expressed by Mineralogists. But Ice receiveth its figure according unto the surface wherein it concreteth, or the circ.u.mambiency which conformeth it. So it is plain upon the surface of water, but round in Hayl (which is also a glaciation,) and figured in its guttulous descent from the air, and so growing greater or lesser according unto the accretion or pluvious aggelation about the mother and fundamental Atomes thereof; which seems to be some feathery particle of Snow; although Snow it self be s.e.xangular, or at least of a starry and many-pointed figure.
They are also differenced in the places of their generation; for though Crystal be found in cold countries, and where Ice remaineth long, and the air exceedeth in cold, yet is it also found in regions, where Ice is seldom seen or soon dissolved; as _Pliny_ and _Agricola_ relate of _Cyprus_, _Caramania_ and an Island in the Red sea; It hath been also found in the veins of Minerals, sometimes agglutinated unto lead, sometimes in Rocks, opacous stones, and the marble face of _Octavius_ Duke of _Parma_. [SN: _Wherein the Sculptor found a piece of pure Crystal._] It hath also constant veins; as beside others, that of mount _Salvino_ about the Territory of _Bergamo_; from whence if part be taken, in no long tract of time out of the same place, as from its mineral matrix, others are observed to arise. Which made the learned _Cerautus_ to conclude, _Videant hi an sit glacies, an vero corpus fossile_. [SN: _Mus. Calceolar._] It is also found in the veins of Minerals, in rocks, and sometime in common earth. But as for Ice, it will not readily concrete but in the approachment of the air, as we have made trial in gla.s.ses of water, covered an inch with oyl, which will not easily freeze in hard frosts of our climate. For water commonly concreteth first in its surface, and so conglaciates downward; and so will it do although it be exposed in the coldest metal of lead, which well accordeth with that expression of _Job_, _The waters are hid as with a stone, and the face of the deep is frozen_. [SN: _Chap. 38._] But whether water which hath been boiled or heated, doth sooner receive this congelation, as commonly is delivered, we rest in the experiment of _Cabeus_, who hath rejected the same in his excellent discourse of Meteors.
They have contrary qualities elemental, and uses medicinal; for Ice is cold and moist, of the quality of water; but Crystal is cold and dry, according to the condition of earth. The use of Ice is condemned by most Physicians, that of Crystal commended by many. For although _Dioscorides_ and _Galen_ have left no mention thereof, yet hath _Mathiolus_, _Agricola_, and many commended it in dysenteries and fluxes; all for the increase of milk, most Chymists for the Stone, and some, as _Bra.s.savolus_ and _Btius_, as an antidote against poyson.
Which occult and specifical operations are not expectable from Ice; for being but water congealed, it can never make good such qualities; nor will it reasonably admit of secret proprieties, which are the affections of forms, and compositions at distance from their elements.
[Sidenote: _What Crystal is._]
Having thus declared what Crystal is not, it may afford some satisfaction to manifest what it is. To deliver therefore what with the judgement of approved Authors, and best reason consisteth, It is a Mineral body in the difference of stones, and reduced by some unto that subdivision, which comprehendeth gemms, transparent and resembling Gla.s.s or Ice, made of a lentous percolation of earth, drawn from the most pure and limpid juice thereof, owing unto the coldness of the earth some concurrence or coadjuvancy, but not immediate determination and efficiency, which are wrought by the hand of its concretive spirit, the seeds of petrification and Gorgon of it self. As sensible Philosophers conceive of the generation of Diamonds, Iris, Berils. Not making them of frozen icecles, or from meer aqueous and glaciable substances, condensing them by frosts into solidities, vainly to be expected even from Polary congelations: but from thin and finest earths, so well contempered and resolved, that transparency is not hindred; and containing lapidifical spirits, able to make good their solidities against the opposition and activity of outward contraries, and so leave a sensible difference between the bonds of glaciation, which in the mountains of Ice about the Northern Seas, are easily dissolved by ordinary heat of the Sun, and between the finer ligatures of petrification, whereby not only the harder concretions of Diamonds and Saphirs, but the softer veins of Crystal remain indissolvable in scorching Territories, and the _Negro_ land of Congor.
And therefore I fear we commonly consider subterranities, not in contemplations sufficiently respective unto the Creation. For though _Moses_ have left no mention of Minerals, nor made any other description then sutes unto the apparent and visible Creation, yet is there unquestionably, a very large Cla.s.sis of Creatures in the Earth, far above the condition of elementarity. And although not in a distinct and indisputable way of vivency, or answering in all points the properties or affections of Plants, yet in inferiour and descending const.i.tutions, they do like these contain specifical distinctions, and are determined by seminalities, that is, created and defined seeds committed unto the Earth from the beginning. Wherein although they attain not the indubitable requisites of Animation, yet have they a near affinity thereto. And though we want a proper name and expressive appellation, yet are they not to be closed up in the general name of concretions; or lightly pa.s.sed over as only Elementary and Subterraneous mixtions.
[Sidenote: _Exact continuity of parts a cause of transparency in things, and why._]
The principle and most gemmary affection is its Tralucency: as for irradiancy or sparkling which is found in many gemms, it is not discoverable in this, for it cometh short of their compactness and durity: and therefore requireth not the Emery, as the Saphir, Granate, and Topaz, but will receive impression from Steel, in a manner like the Turchois. As for its diaphanity or perspicuity, it enjoyeth that most eminently; and the reason thereof is its continuity; as having its earthy and salinous parts so exactly resolved, that its body is left imporous and not discreted by atomical terminations. For, that continuity of parts is the cause of perspicuity, it is made perspicuous by two ways of experiment. That is, either in effecting transparency in those bodies which were not so before, or at least far short of the additional degree: So Snow becomes transparent upon liquation, so Horns and Bodies resolvable into continued parts or gelly. The like is observable in oyled paper, wherein the interst.i.tial divisions being continuated by the accession of oyl, it becometh more transparent, and admits the visible rayes with less umbrosity. Or else the same is effected by rendring those bodies opacous, which were before pellucid and perspicuous.
So Gla.s.s which was before diaphanous, being by powder reduced into multiplicity of superficies, becomes an opacous body, and will not transmit the light. So it is in Crystal powdered, and so it is also before; for if it be made hot in a crucible, and presently projected upon water, it will grow dim, and abate its diaphanity; for the water entering the body, begets a division of parts, and a termination of Atoms united before unto continuity.
The ground of this Opinion might be, first the conclusions of some men from experience; for as much as Crystal is found sometimes in rocks, and in some places not much unlike the stirious or stillicidious dependencies of Ice. Which notwithstanding may happen either in places which have been forsaken or left bare by the earth, or may be petrifications, or Mineral indurations, like other gemms, proceeding from percolations of the earth disposed unto such concretions.
The second and most common ground is from the name _Crystallus_, whereby in Greek both Ice and Crystal are expressed; which many not duly considering, have from their community of name, conceived a community of nature; and what was ascribed unto the one, not unfitly appliable unto the other. But this is a fallacy of aequivocation, from a society in name inferring an Ident.i.ty in nature. By this fallacy was he deceived that drank _Aqua fortis_ for strong water. By this are they deluded, who conceive _sperma Cti_ which is found about the head, to be the sp.a.w.n of the Whale: Or take _sanguis draconis_ (which is the gumme of a tree,) to be the blood of a Dragon. By the same Logick we may infer, the Crystalline humour of the eye, or rather the Crystalline heaven above, to be of the substance of Crystal here below; Or that G.o.d sendeth down Crystal, because it is delivered in the vulgar translation, Psal. 47.
_Mitt.i.t Crystallum suum sicut Buccellas_. [SN: _Agreement in name._]
Which translation although it literally express the Septuagint; yet is there no more meant thereby, than what our translation in plain English expresseth; that is, he casteth forth his Ice like morsels, or what _Tremellius_ and _Junius_ as clearly deliver, _Deficit gelu suum sicut frusta, coram frigore ejus quis consistet?_ which proper and latine expressions, had they been observed in ancient translations, elder Expositors had not been misguided by the Synonomy; nor had they afforded occasion unto _Austin_, the Gloss, _Lyra.n.u.s_, and many others, to have taken up the common conceit, and spoke of this Text conformably unto the opinion rejected.
CHAPTER II
Concerning the Loadstone.
Of things particularly spoken thereof, evidently or probably true.
Of things generally believed, or particularly delivered, manifestly or probably false. In the first of the Magnetical vertue of the Earth, of the four motions of the stone, that is, its Verticity or Direction, its Attraction or Coition, its Declination, its Variation, and also of its Antiquity. In the second a rejection of sundry opinions and relations thereof, Natural, Medical, Historical, Magical.
[Sidenote: _How the earth is a Magnetical body._]
And first we conceive the earth to be a Magnetical body. A Magnetical body, we term not onely that which hath a power attractive, but that which seated in a convenient medium, naturally disposeth it self to one invariable and fixed situation. And such a Magnetical vertue we conceive to be in the Globe of the Earth, whereby as unto its natural points and proper terms, it disposeth it self unto the poles; being so framed, const.i.tuted, and ordered unto these points, that those parts which are now at the poles, would not naturally abide under the aequator, nor _Greenland_ remain in the place of _Magellanica_. And if the whole earth were violently removed, yet would it not foregoe its primitive points, nor pitch in the East or West, but return unto its polary position again. For though by compactness or gravity it may acquire the lowest place, and become the center of the universe, yet that it makes good that point, not varying at all by the accession of bodies upon, or secession thereof from its surface, perturbing the equilibration of either Hemisphere (whereby the alt.i.tude of the stars might vary) or that it strictly maintains the North and Southern points; that neither upon the motions of the heavens, air, and winds without, large eruptions and division of parts within, its polary parts should never incline or veer unto the Equator (whereby the lat.i.tude of places should also vary) it cannot so well be salved from gravity as a Magnetical verticity. [SN: _The foundation of the Earths stability._] This is probably, that foundation the wisdom of the Creator hath laid unto the earth; in this sense we may more nearly apprehend, and sensibly make out the expressions of holy Scripture [SN: _Psal. 93._], as _Firmavit orbem terrae qui non commovebitur_, he hath made the round world so sure that it cannot be moved: as when it is said by _Job, Extendit Aquilonem super vacuo, &c._ [SN: _Job 38._] He stretcheth forth the North upon the empty place, and hangeth the earth upon nothing. And this is the most probable answer unto that great question. Whereupon are the foundations of the Earth fastened, or who laid the corner stone thereof? Had they been acquainted with this principle, _Anaxagoras_, _Socrates_, and _Democritus_, had better made out the ground of this stability; _Xenophanes_ had not been fain to say the Earth had no bottom; and _Thales Milesius_ to make it swim in water.
[Sidenote: _The magnetical vertue of the Earth diffused_ extra se _and communicated to bodies adjacent._]
Nor is the vigour of this great body included only in its self, or circ.u.mferenced by its surface, but diffused at indeterminate distances through the air, water, and all bodies circ.u.mjacent. Exciting and impregnating Magnetical bodies within its surface or without it, and performing in a secret and invisible way what we evidently behold effected by the Loadstone. For these effluxions penetrate all bodies, and like the species of visible objects are ever ready in the medium, and lay hold on all bodies proportionate or capable of their action, those bodies likewise being of a congenerous nature, do readily receive the impressions of their motor; and if not fettered by their gravity, conform themselves to situations, wherein they best unite unto their Animator. And this will sufficiently appear from the observations that are to follow, which can no better way be made out then by this we speak of, the Magnetical vigour of the Earth. Now whether these effluviums do flye by striated Atoms and winding particles as _Renatus des Cartes_ conceiveth; or glide by streams attracted from either Pole and Hemisphere of the Earth unto the Equator, as Sir _Kenelm Digby_ excellently declareth, it takes not away this vertue of the Earth, but more distinctly sets down the gests and progress thereof, and are conceits of eminent use to salve Magnetical Phenomena"s. [SN: _Apparencies observations._] And as in Astronomy those hypotheses though never so strange are best esteemed which best do salve apparencies; so surely in Philosophy those principles (though seeming monstrous) may with advantage be embraced, which best confirm experiment, and afford the readiest reason of observation.[SN: _The doctrine of effluxions acknowledged by the Author._] And truly the doctrine of effluxions, their penetrating natures, their invisible paths, and insuspected effects, are very considerable; for besides this Magnetical one of the Earth, several effusions there may be from divers other bodies, which invisibly act their parts at any time, and perhaps through any medium; a part of Philosophy but yet in discovery, and will, I fear, prove the last leaf to be turned over in the Book of Nature.
[Sidenote: _Point to the North._]
[Sidenote: _Point to the South._]
First, Therefore it is true, and confirmable by every experiment, that Steel and good Iron never excited by the Loadstone, discover in themselves a verticity; that is, a directive or polary faculty, whereby, conveniently placed, they do Septentrionate at one extream, and Australize at another. This is manifestable in long and thin plates of Steel perforated in the middle and equilibrated; or by an easier way in long wires equiponderate with untwisted Silk and soft Wax; for in this manner pendulous, they will conform themselves Meridionally, directing one extream unto the North, another to the South. The same is also manifest in Steel wires thrust through little sphears or globes of Cork and floated on the water, or in naked Needles gently let fall thereon; for so disposed they will not rest, until they have found out the Meridian, and as near as they can lye parallel unto the Axis of the Earth: Sometimes the eye, sometimes the point Northward in divers Needles, but the same point always in most: Conforming themselves unto the whole Earth, in the same manner as they do unto every Loadstone. For if a Needle untoucht he hanged above a Loadstone, it will convert into a parallel position thereto; for in this situation it can best receive its verticity and be excited proportionably at both extreams. Now this direction proceeds not primitively from themselves, but is derivative and contracted from the Magnetical effluxions of the Earth; which they have winded in their hammering and formation; or else by long continuance in one position, as we shall declare hereafter.
It is likewise true what is delivered of Irons heated in the fire, that they contract a verticity in their refrigeration; for heated red hot and cooled in the Meridian from North to South, they presently contract a polary power, and being poised in air or water, convert that part unto the North which respected that point in its refrigeration, so that if they had no sensible verticity before, it may be acquired by this way; or if they had any, it might be exchanged by contrary position in the cooling. For by the fire they omit not onely many drossie and scorious parts, but whatsoever they had received either from the Earth or Loadstone; and so being naked and despoiled of all verticity, the Magnetical Atomes invade their bodies with more effect and agility.
Neither is it only true what _Gilbertus_ first observed, that Irons refrigerated North and South acquire a Directive faculty; but if they be cooled upright and perpendicularly, they will also obtain the same. That part which is cooled toward the North on this side the Equator, converting it self unto the North, and attracting the South point of the Needle: the other and highest extream respecting the South, and attracting the Northern, according unto Laws Magnetical: For (what must be observed) contrary Poles or faces attract each other, as the North the South; and the like decline each other, as the North the North. Now on this side of the Equator, that extream which is next the Earth is animated unto the North, and the contrary unto the South; so that in coition it applies it self quite oppositely, the coition or attraction being contrary to the Verticity or Direction. Contrary, If we speak according unto common use, yet alike, if we conceive the vertue of the North Pole to diffuse it self and open at the South, and the South at the North again.
[Sidenote: _Some conceive that the figure of the Tree or Spread-eagle in the root of Brake or Fern stands North and South, but not truly._]
This polarity from refrigeration upon extremity and in defect of a Loadstone might serve to invigorate and touch a Needle any where; and this, allowing variation, is also the readiest way at any season to discover the North or South; and surely far more certain then what is affirmed of the grains and circles in trees, or the figure in the root of Fern. For if we erect a red hot wire until it cool, then hang it up with wax and untwisted Silk, where the lower end and that which cooled next the earth doth rest, that is the Northern point; and this we affirm will still be true whether it be cooled in the air or extinguished in water, oyl of Vitriol, _Aqua fortis_, or Quicksilver. And this is also evidenced in culinary utensils and Irons that often feel the force of fire, as Tongs, Fire-shovels, p.r.o.ngs, and Andirons; all which acquire a Magnetical and polary condition, and being suspended, convert their lower extreams unto the North; with the same attracting the Southern point of the Needle. For easier experiment, if we place a Needle touched at the foot of Tongs or Andirons, it will obvert or turn aside its lillie or North point, and conform its cuspis or South extream unto the Andiron. The like verticity though more obscurely is also contracted by Bricks and Tiles, as we have made trial in some taken out of the backs of chimneys. Now to contract this Direction, there needs not a total ignition, nor is it necessary the Irons should be red hot all over. For if a wire be heated only at one end, according as that end is cooled upward or downward, it respectively acquires a verticity, as we have declared in wires totally candent. Nor is it absolutely requisite they should be cooled perpendicularly, or strictly lie in the Meridian; for whether they be refrigerated inclinatorily or somewhat aequinoxially, that is toward the Eastern or Western points; though in a lesser degree, they discover some verticity.
Nor is this onely true in Irons, but in the Loadstone it self. For if a Loadstone be made red hot, it loseth the magnetical vigour it had before in it self, and acquires another from the Earth in its refrigeration; for that part which cooleth toward the Earth will acquire the respect of the North, and attract the Southern point or cuspis of the Needle. The experiment hereof we made in a Loadstone of a parallelogram or long square figure; wherein onely inverting the extreams, as it came out of the fire, we altered the poles or faces thereof at pleasure.
It is also true what is delivered of the Direction and coition of Irons, that they contract a verticity by long and continued position: that is, not onely being placed from North to South, and lying in the Meridian, but respecting the Zenith and perpendicular unto the Center of the Earth; as is manifest in bars of windows, cas.e.m.e.nts, hinges and the like. For if we present the Needle unto their lower extreams, it wheels about and turns its Southern point unto them. The same condition in long time do Bricks contract which are placed in walls, and therefore it may be a fallible way to find out the Meridian by placing the Needle on a wall; for some Bricks therein by a long and continued position, are often magnetically enabled to distract the polarity of the Needle. And therefore those Irons which are said to have been converted into Loadstones; whether they were real conversions, or onely attractive augmentations, might be much promoted by this position: as the Iron cross of an hundred weight upon the Church of St. _John_ in _Ariminum_, or that Loadston"d Iron of _Caesar Moderatus_, set down by _Aldrovandus_.
[SN: _De miner. l. 1._]
Lastly, Irons do manifest a verticity not only upon refrigeration and constant situation, but (what is wonderful and advanceth the magnetical Hypothesis) they evidence the same by meer position according as they are inverted, and their extreams disposed respectively unto the Earth.
For if an Iron or Steel not firmly excited, be held perpendicularly or inclinatorily unto the Needle, the lower end thereof will attract the _cuspis_ or Southern point; but if the same extream be inverted and held under the Needle, it will then attract the lilly or Northern point; for by inversion it changeth its direction acquired before, and receiveth a new and Southern polarity from the Earth, as being the upper extream.
Now if an Iron be touched before, it varieth not in this manner; for then it admits not this magnetical impression, as being already informed by the Loadstone, and polarily determined by its preaction.
And from these grounds may we best determine why the Northern Pole of the Loadstone attracteth a greater weight than the Southern on this side the aequator; why the stone is best preserved in a natural and polary situation; and why as _Gilbertus_ observeth, it respecteth that Pole out of the Earth, which it regarded in its Mineral bed and subterraneous position.
It is likewise true and wonderful what is delivered of the Inclination or Declination of the Loadstone; that is, the descent of the Needle below the plain of the Horizon. For long Needles which stood before upon their _axis_, _parallel_ unto the Horizon, being vigorously excited, incline and bend downward, depressing the North extream below the Horizon. That is the North on this, the South on the other side of the Equator; and at the very Line or middle circle stand without deflexion.
And this is evidenced not onely from observations of the Needle in several parts of the earth, but sundry experiments in any part thereof, as in a long Steel wire, equilibrated or evenly ballanced in the air; for excited by a vigorous Loadstone it will somewhat depress its animated extream, and intersect the horizontal circ.u.mference. It is also manifest in a Needle pierced through a Globe of Cork so cut away and pared by degrees, that it will swim under water, yet sink not unto the bottom, which may be well effected; for if the Cork be a thought too light to sink under the surface, the body of the water may be attenuated with spirits of wine; if too heavy, it may be incra.s.sated with salt; and if by chance too much be added, it may again be thinned by a proportionable addition of fresh water. If then the Needle be taken out, actively touched and put in again, it will depress and bow down its Northern head toward the bottom, and advance its Southern extremity toward the brim. This way invented by _Gilbertus_ may seem of difficulty; the same with less labour may be observed in a needled sphere of Cork equally contiguous unto the surface of the water; for if the Needle be not exactly equiponderant, that end which is a thought too light, if touched becometh even; that Needle also which will but just swim under the water, if forcibly touched will sink deeper, and sometime unto the bottom. If likewise that inclinatory vertue be destroyed by a touch from the contrary Pole, that end which before was elevated will then decline, and this perhaps might be observed in some scales exactly ballanced, and in such Needles which for their bulk can hardly be supported by the water. For if they be powerfully excited and equally let fall, they commonly sink down and break the water at that extream whereat they were septentrionally excited: and by this way it is conceived there may be some fraud in the weighing of precious commodities, and such as carry a value in quarter-grains; by placing a powerful Loadstone above or below, according as we intend to depress or elevate one extream.
Now if these Magnetical emissions be onely qualities, and the gravity of bodies incline them onely unto the earth; surely that which alone moveth other bodies to descent, carrieth not the stroak in this, but rather the Magnetical alliciency of the Earth; unto which with alacrity it applieth it self, and in the very same way unto the whole Earth, as it doth unto a single Loadstone. For if an untouched Needle be at a distance suspended over a Loadstone, it will not hang parallel, but decline at the North extream, and at that part will first salute its Director.
Again, what is also wonderful, this inclination is not invariable; for just under the line the Needle lieth parallel with the Horizon, but sailing North or South it beginneth to incline, and encreaseth according as it approacheth unto either Pole; and would at last endeavour to erect it self. And this is no more then what it doth upon the Loadstone, and that more plainly upon the Terrella or spherical magnet Cosmographically set out with circles of the Globe. For at the Equator thereof, the Needle will stand rectangularly; but approaching Northward toward the Tropick it will regard the stone obliquely, and when it attaineth the Pole, directly; and if its bulk be no impediment, erect it self and stand perpendicularly thereon. And therefore upon strict observation of this inclination in several lat.i.tudes and due records preserved, instruments are made whereby without the help of Sun or Star, the lat.i.tude of the place may be discovered; and yet it appears the observations of men have not as yet been so just and equal as is desirable; for of those Tables of declination which I have perused, there are not any two that punctually agree; though some have been thought exactly calculated, especially that which _Ridley_ received from Mr. _Brigs_, in our time Geometry Professor in _Oxford_.
[Sidenote: _What the variation of the Compa.s.s is._]
It is also probable what is delivered concerning the variation of the Compa.s.s that is the cause and ground thereof, for the manner as being confirmed by observation we shall not at all dispute. The variation of the Compa.s.s is an Arch of the Horizon intercepted between the true and Magnetical Meridian; or more plainly, a deflexion and siding East and West from the true Meridian. The true Meridian is a major Circle pa.s.sing through the Poles of the World, and the Zenith or Vertex of any place, exactly dividing the East from the West. Now on this line the Needle exactly lieth not, but diverts and varieth its point, that is, the North point on this side the Equator, the South on the other; sometimes on the East, sometime toward the West, and in some few places varieth not at all. First, therefore it is observed that betwixt the Sh.o.r.e of _Ireland_, _France_, _Spain_, _Guiny_, and the _Azores_, the North point varieth toward the East, and that in some variety; at _London_ it varieth eleven degrees, at _Antwerp_ nine, at _Rome_ but five: at some parts of the _Azores_ it deflecteth not, but lieth in the true Meridian; on the other side of the _Azores_, and this side of the Equator, the North point of the Needle wheeleth to the West; so that in the lat.i.tude of 36 near the sh.o.r.e, the variation is about eleven degrees; but on the other side the Equator, it is quite otherwise: for about _Capio Frio_ in _Brasilia_, the South point varieth twelve degrees unto the West, and about the mouth of the Straits of _Magellan_ five or six; but elongating from the coast of _Brasilia_ toward the sh.o.r.e of _Africa_ it varieth Eastward, and arriving at _Capo de las Agullas_, it resteth in the Meridian, and looketh neither way.
[Sidenote: _The cause of the variation of the Compa.s.s._]
Now the cause of this variation was thought by _Gilbertus_ to be the inequality of the Earth, variously disposed, and indifferently intermixed with the Sea: withal the different disposure of its Magnetical vigor in the eminencies and stronger parts thereof. For the Needle naturally endeavours to conform unto the Meridian, but being distracted, driveth that way where the greater and powerfuller part of the Earth is placed. Which may be ill.u.s.trated from what hath been delivered and may be conceived by any that understands the generalities of Geography. For whereas on this side the Meridian, or the Isles of _Azores_, where the first Meridian is placed, the Needle varieth Eastward; it may be occasioned by that vast Tract of Earth, that is, of _Europe_, _Asia_, and _Africa_, seated toward the East, and disposing the Needle that way. For arriving at some part of the _Azores_, or Islands of Saint _Michael_, which have a middle situation between these Continents, and that vast and almost answerable Tract of _America_, it seemeth equally distracted by both; and diverting unto neither, doth parallel and place it self upon the true Meridian. But sailing farther, it veers its Lilly to the West, and regardeth that quarter wherein the Land is nearer or greater; and in the same lat.i.tude as it approacheth the sh.o.r.e augmenteth its variation. And therefore as some observe, if _Columbus_ or whosoever first discovered _America_, had apprehended the cause of this variation, having pa.s.sed more then half the way, he might have been confirmed in the discovery, and a.s.suredly foretold there lay a vast and mighty continent toward the West. The reason I confess and inference is good, but the instance perhaps not so. For _Columbus_ knew not the variation of the compa.s.s, whereof _Sebastian Cabot_ first took notice, who after made discovery in the Northern part of that continent.
And it happened indeed that part of _America_ was first discovered, which was on this side farthest distant, that is, _Jamaica_, _Cuba_, and the Isles in the Bay of _Mexico_. And from this variation do some new discoverers deduce a probability in the attempts of the Northern pa.s.sage toward the _Indies_.
Now because where the greater continents are joyned, the action and effluence is also greater; therefore those Needles do suffer the greatest variation which are in Countries which most do feel that action. And therefore hath _Rome_ far less variation then _London_; for on the West side of _Rome_ are seated the great continents of _France_, _Spain_, _Germany_, which take off the exuperance, and in some way ballance the vigor of the Eastern parts. But unto _England_ there is almost no Earth West, but the whole extent of _Europe_ and _Asia_ lieth Eastward; and therefore at _London_ it varieth eleven degrees, that is almost one _Rhomb_. Thus also by reason of the great continent of _Brasilia_, _Peru_, and _Chili_, the Needle deflecteth toward the Land twelve degrees; but at the straits of _Magellan_ where the Land is narrowed, and the Sea on the other side, it varieth but five or six.
And so likewise, because the Cape _de las Agullas_ hath Sea on both sides near it, and other Land remote, and as it were aequidistant from it, therefore at that point the Needle conforms unto the true Meridian, and is not distracted by the vicinity of Adjacencies. This is the general and great cause of variation. But if in certain Creeks and Vallies the Needle prove irregular, and vary beyond expectation, it may be imputed unto some vigorous part of the Earth, or Magnetical eminence not far distant. And this was the invention of _D. Gilbert_, not many years past, a Physician in _London_. And therefore although some a.s.sume the invention of its direction, and other have had the glory of the Card; yet in the experiments, grounds, and causes thereof, _England_ produced the Father Philosopher, and discovered more in it then _Columbus_ or _Americus_ did ever by it.
Unto this in great part true the reason of _Kircherus_ may be added: That this variation proceedeth not only from terrestrious eminencies, and magnetical veins of the Earth, laterally respecting the Needle, but the different coagmentation of the Earth disposed unto the Poles, lying under the Sea and Waters, which affect the Needle with great or lesser variation, according to the vigour or imbecility of these subterraneous lines, or the entire or broken compagination of the magnetical fabrick under it. As is observable from several Loadstones placed at the bottom of any water, for a Loadstone or Needle upon the surface, will variously conform it self, according to the vigour or faintness of the Loadstones under it.