CHAP. I. Of the magneticall power and force of the whole Globe of the Earth.

COncerning the Magneti­call force of the whole body of the Earth, I haue selected these expe­riments to proue it.

Take any peece of so­lid earth that hath some toughnesse to hold toge­ther, and will abide the fire, as any sort of clay, or bricke (which somtimes was clay) fashion it in such manner that it bee vniformely extended towards both ends (the Ouall or long figure is fittest for our purpose) put it into a fire of charcoles, increasing the heat by little and little, and at the length with often blowing, make it throughly as red hot as you can: let [Page 2] it remaine so for the space of halfe an houre, or more, that thereby all superfluous moisture may be consumed, and aduerse qualities separated from it, then take it forth, and let it coole of it selfe, being first set North and South, with either end answerable to the variation of the place, not paralell vnto the Ho­rizon, but eleuated answerable to the Latitude as nere as you can. Certaine it is that this peece of earth thus ordered, will sensibly shew you that it hath true Magneticall vertue. But here before I proceed any farther I must deliuer vnto you a necessary obserua­tion: There are two kindes of Attractions (as they are commonly called) the one Magneticall, the other Electricall. The Magneticall hath alwaies speciall re­spect vnto the North & South points of the Magnete or Magneticall body. The Electricall body hath no manner of respect vnto any one point of the Electri­call body, more than another: And by this diffe­rence these two kinds of Attractions are easily discer­ned; As also by this, looke what end of the Magne­ticall needle the one end of the Magnet doth draw, the other will chase away; but the Electricall body draweth alike at all ends. And thirdly after this sort, lapp this Electricall body in a paper and it will draw nothing at all, but interposition of brasse or of a stone wall within the orbe of the Magnets vertue, doth nothing weaken the same, or hinder his effect towards his peculiar obiect. Notwithstanding (to speake properly) Attraction pertaineth onely to Ele­ctricall bodies, because the whole attractiue vertue is onely in the Electricall body it selfe, and nothing at all in the thing that is attracted. The Attraction [Page 3] (commonly so called) of the Loadstone is rightly to be termed, Concursion, Confluence, or Coition, because it is the running or vigorous meeting together of two Magneticall bodies hauing a mutuall inclination the one to ioyne with the other, or by any other name, bearing like sense. For the true knowledge thereof, being but lately as a stranger arriued a­mongst vs, common vse

(Quempenes arbitrium est, & ius & normal loquendi.) hath as yet scant suted it, with a conuenient name to expresse this property; So that Magneticall Concur­sion is neuer but betweene two bodies, such as both of them are Magneticall; As of one Loadstone with another, or of a Loadstone with yron or steele, or yron oare if it be prepared, or betweene two peeces of yron or steele that are reuiued with a Loadstone; for indeed the Loadstone can but reuiue, and multiply Magneticall force in a body that naturally hath it in some measure before: but cannot infuse it into any thing, that before is vtterly voide of it, as of mettals, in yron or steele, and not in gold, siluer, brasse, &c. Electrum in this argument is named that which is ei­ther Amber in substance, or at the least of the quality, and that Amber, being rubbed, hath, to take vp moats, feathers, strawes, sticks, and other small things. The which property is also in ieate, brim­stome, hard waxe, (if it be smooth) and in infinite other things both naturall and compound; all which because of that qualitie in this argument are termed Electricall bodies, and their taking vp of things is cal­led Electricall attraction, hauing onely a slender re­semblance, and no truth of the Magneticall qualitie. [Page 4] But that aboue-mentioned peece of earth, prepared in such sort as is before prescribed, will by Magneti­call concursion shew it selfe to be a true Magneticall body. For the one end of the Magneticall needle will couet towards the one of the prepared masle, and flie from the other. And contrariwise also, though it will do both but weakely, not with power comparable to a naturall Loadstone, yet as truely as that. That end which cooled toward the South, will draw the true North end of the needle, and that end which cooled toward the North will draw the true South end of the needle. If so be as yet you will haue another infallible argument, doe thus: Marke what end draweth the North end of the needle, after­ward put the new made Magnet into the fire againe, and when it hath been glowing for the space of halfe a quarter of an houre, take it out and coole it being placed with that marked end toward the North, most assuredly that end now will draw the South end of the needle, & the North end of the needle will shun it, which before approached vnto it. The reason here of is, because the fire hauing abolished all the for­mer Magneticall qualitie of that masse wherewith it was in a contrary position affected in the former cooling, now leaueth it apt and fit to receiue any o­ther new impression: which presently it taketh a­gaine either regularly, if in the cooling it be placed with the ends to the North and South, or (if it be pla­ced otherwise) confusedly, by the Magneticall force and vertue of the whole body of the earth, by regu­lar and confused, this is the meaning. Take any lump of earth, or any brick-bat ordered in this sort, cer­taine [Page 5] it is that this lumpe of earth or bricke-bat hath some magneticall vertue therein, yet so feeble and weake, that our sence cannot discerne it, because of the vnfitnesse of the forme, and the confused disper­sion of that weake force, through the whole body thereof. Then suppose you will bring either of these into an extended ovall forme, which is most apt (as before I said) for any body magneticall to shew his force, yet this will helpe it nothing at all of it selfe, as you may easily make experience in euery Load­stone. For if you take a loadstone of a confused forme, it is not inough to bring it into a conuenient ovall, except with diligence you reserue the points of the North and South in the two ends thereof, for if you leaue the points in the sides you marre it with this ovall forme. For the stone will not lightly be of one quarter of the force, it was ofbefore; For the ovall forme giueth it no vertue, but is the fittest for it to shew the vttermost of that strength, which of it selfe it had before, if you obserue the due points, and not otherwise. But in this earth and bricke it is not possible to finde the due points in such sort as you may in a Loadstone, because of the weak­nesse of the magneticall force therein contained. And therefore you cannot bring that into a regular ovall forme, to haue the due points in the very ends. But if you first make it into an ovall forme, and by the fire take away the confused magneticall force, and all other peruerse qualities thereof, that being by nature a magneticall body in his cooling before specified, receiueth presently by that vnresistable power of the earth, his magneticall vertue, according [Page 6] vnto that forme, and will regularly haue his due points precisely in the ends, without any confusion. Iohannes Baptista-Porta Neapolitanus, writeth that hee did make triall of the way that Paracelsus hath set downe for to increase the vertue of a magnet, name­ly to heate him red hot in the fire, and to quench him in the oyle of Crocus Martis: And Baptista Porta saith, that hee found it a detestable falshood. For saith hee, he is so farre from increasing his vertue, as that (being once red hot) he looseth all his own, past all recouery. But for all this that hee saith, I doubt whether Paracelsus be iustly reprooued or not, for by mine owne experience I know that the heating of a Loadstone vntill he be red hotte doth weaken a load­stone, but taketh not away all his force, and in my triall here of I found a very manifest proofe of the magnetisme of the earth, which I thought necessary for to insert in this place. I haue made this triall of Fragments of magnets of diuers kindes, and also of di­uers kindes of Iron Mines which are next in degree vnto magnets, namely after this sort. Heate him in the fire by little and little (for feare of breaking) vntill he be red hotte, then take him out and let him coole, then marke (with chalke or what you please) those parts that respect the North and South and you shall finde those marked places, the North, and South Poles of the Magnet: put him into the fire a­gaine, vntill he be red hotte, and coole him contra­rily, and you shall haue the contrary effect. There­fore if Baptista Porta did make his triall with a Load­stone very long in forme, and chaunced (for Master D. Gilberts mistery of the Earths magnetisme, was not [Page 7] then reuealed) for to coole him in his oyle of Crocus Martis with his ends East and West, the axis of the stone being then ouerth wart in the middle, it were no maruell if he found no force in the ends. And I do not thinke it improbable, but that Paracelsus way may doe some good rightly vsed. Doctour Gilbert writech that some Iron mine, will affect a magneticall needle, as it is of it selfe, being vnprepared by fire: but as yet I neuer could finde any such, but this I haue often tried, that it being of no manner of mag­neticall vertue of it selfe no more then a flintstone vnprepared by fire, being made red hott, and cooled, is presently impregnated with very appa­rant magneticall vertue, according to the scituation that hee is cooled in, and although you heate and coole him often, and diuers waies, he will still keepe his vertue, according to the scituations, of his cool­ing. And some Iron Mines I haue found, which being but in this sort prepared haue had as strong force as some naturall magnets haue had. It is the goodnesse of the Loadstone ioyned with a fit forme that will shew great force. For as a very good forme with base substance can doe but very litle, so the substance of the Loadstone bee it neuer so excellent, except it haue some conuenient forme, is not auaile­able. For example, an excellent loadstone of a pound waight and of a good fashion, being vsed artificially, may take vp foure pounds of Iron; beate it into small pouder, and it shall bee of no force to take vp one ounce of Iron; yea I am very well assured that halfe an ounce of a Loadstone of good fashion, and of like vertue will take vp more then that pound will doe [Page 8] being beaten into powder. Whence, (to adde this by the way) it appeareth manifestly, that it is a great error of those Phisitions and Surgeons, which to remedy ruptures, doe prescribe vnto their Pati­ents to take the pouder of a Loadstone inwardly, and the small filing of iron mingled in some plaister out­wardly: supposing that herein the magneticall draw­ing should doe great wonders. Whereas they con­sider not that the stone being dissolued into pow­der, euery little particle of the dust hath two points contrarie, the one drawing to, the other repelling and putting from: and so being thus confounded by a contrarie working doth much more harme, then good with his magneticall quality. As for the astringent, and drying properties of the Loadstone I leaue them to the diligent obseruation and iudg­ment of the skilfull in phisicke. But to returne to our purpose, and to alledge this also, besides the former manifest proofe, if the earth were not by nature a magneticall body, the afore mentioned peice of earth could not receiue from a Loadstone any magneticall power: But most certaine it is, and by many vn­doubted experiments confirmed, that it will eui­dently receiue magneticall power, from a Loadstone: therefore it is manifest that the earth is by nature a magneticall body. Furthermore, as among all the mettals iron doth incomparably more resemble the earth in substance then any other doth, it likewise doth more participate with the earth in quality, and principally in the magneticall peculiar property hereof, as notorious experience declareth, yea eue­ry peice of iron Oare, being naturally (as D. Gilbert [Page 9] sheweth) a magnet, although of feeble force, and all magnets being a kinde of iron Oare, is the very cause, that onely iron or steele, and no other mettall is capable of that vertue, namely to haue that reuiued, and multiplied by the vicinity of a magnet, which at the first in some measure, was originall in it selfe, as it is aforesaid; It is also well knowne, that the magnet is a Stone most commonly of inuincible hardnesse, nothing inferiour to any iron or steele of the excel­lentest sort, notwithstanding sometimes wee see of them that are nothing, but a dry lumpe of earth, and yet of those also some stronger in vertue, then diuers of the hard stony ones are: Which earthly magnets if a man assay to bring it into a fashion by grinding on a grinding stone (according to the com­mon vse) they will consume into very mudde in the water. Now (to drawe towards an end of this mat­ter) albeit the magneticall vertue be most eminent in the magnet, as in the precise and perfect subiect there­of: yet is the selfe same quality, in a meaner degree, euidently to be discerned in euery peice of earth, prepared and ordered (as is aforesaid) yea although it be not cooled with his ends North and South, that it may take his magneticall force from the vertue of the earth, for if you coole it with his ends but East and West and set two Loadstones in the cooling, the one at one end and the other at the other end, it will receiue a sensible and apparant magneticall vertue ac­cording to those points of the Loadstone that were applied vnto it, namely that end which was next the South point of the Loadstone will haue a North properly, and that end that was next the North [Page 10] point, will haue a South property: yea if you set the North part of two loadstones vnto each end, both ends of this new made magnet will haue a South pro­perty; And contrariwise if you apply the South ends of two magnets, both his ends will haue a North pro­perty; And those properties before mentioned will shew themselues to be magneticall, because whether end of this new magnet draweth any one end of a magneticall needle, the same will chase away the o­ther: which is proper only vnto magnets, and magne­tical bodies. After the like sort, only by application of two strong loadstones by the space of 24. houres you may alter the points of any base loadstone, which you would, and make them both North or South as you please: so that the loadstone which you would alter be but base in qualitie, and not great in sub­stance, and that the other be of a reasonable bignes, and good strength. And this vertue by such appli­cation of two loadstones I haue often found effectuall in new bricke lately taken from the kill without any farther putting into the fire at all; And although it be against the nature of a loadstone to haue both his ends naturally of one vertue, that is to say, both of them of a North property, or both of them of a South property: yet here it is to be vnderstood, that it is the forcible violence of the strong ones, being applied iointly vnto each end of the weake, that doe chase the contrarie property of the weake one into the middle thereof: And therefore if you diuide this weak one in the middle, then both those ends, which being ioyned together were the middle, (where no loadstone can shew any vertue) being now disioyn­ed, [Page 11] and become ends, will presently shew a contrary property (according vnto magneticall nature) vnto the other two ends.

CHAP. II. The ambiguity of the North and South ends of Magnets and Magneticall bodies explained, and Doctor Gil­bert therein defended.

THere is not any one errour that breedeth a greater confusion in magneticall knowledge, then the mistaking of the right vnderstanding of the true North and South ends, aswell in magnets them­selues, as also in magneticall bodies, who soeuer there­fore that will take a little paines in the beginning for to vnderstand this well, shall free himselfe from ma­ny intricate difficulties in this argument, which o­therwise must needes befall him; wherein some hau­ing limed themselues, haue fallen into many errors, euery one still begetting another worse then him­selfe. All those which did write before Doctor Gil­bert did name that end of a magnet which being pla­ced in a wooden dish, and set to swimme in water, would turne and settle it selfe towards the North, the North end of the magnet; and the other the South end. And euen so did they of all Dial-needles, Compasses and magneticall bodies. But Doctour Gilbert, not for any new-fangled innouation, or selfe­conceit, but vpon good reason and firme demonstra­tion auoucheth and prooueth the contrarie, and clearely sheweth, that the former vulgar assertion [Page 12] seriously defended, tendeth vnto the ouerthrow of all magneticall Philosophie, by vndermining (as it were) the whole frame thereof; and yet in common speech the old rule may hold, Loquendum cum vulgo sentiendum cum sapientibus. For it would seeme a strange speech vnto a Marriner to tell him that his Flower de luce were become the South point of his compasse, and yet this assertion is most true, and cer­taine that it is the North end of euery magnet and magneticall body, that being placed in a thinne wod­den dish in water, or any magneticall needle vpon his pinne, which setteth it selfe and pointeth vnto the South, and it is the South end which pointeth vnto the North. For proofe hereof, take these wordes of North and South in whether of the two former sig­nifications you please, and make triall thereof in any two magnets, or any two magneticall bodies, so placed that they may freely turne according vnto their natures, and you shall alwaies see a naturall inclinati­on of the contrary ends of the one vnto the contra­ry ends of the other, as of the North end of the one vnto the South end of the other, and reciprocated of the South of the one to the North of the other; But the ends in the one and the other will alwaies flie from those of like denomination, as the North end of the one from the North end of the other, and the South end of the one from the South end of the other.

For as much then as all magnets themselues, and all magneticall bodies (being so placed as they may haue their free motion) compose themselues magnetically towards the Poles of the earth, it must needs be that [Page 13] it is the true naturall South end of the Magnet or Mag­neticall needle, that pointeth towards the North of the Earth: and it is the true naturall North end of the Magnet or Magneticall needle that pointeth to­wards the South of the Earth, because the contrary ends doe affect one an other, and each of them doe naturally flie, the one end of the one, from that end of the other, which is of like denomination vnto it selfe: for example, In this following Diagram of the whole Magnet, E. A, is supposed to note the true na­turall North end thereof, and B. the South end.

This Magnet being placed in a woodden dish, swim­ming in water, freely must, and will, of Magneticall necessitie, with his true North end, A. settle himself so, that A. must point towards the South of the Earth. And the South end, B. towards the North [Page 14] of the Earth: Because all Magnets and all Magneti­call bodies, do naturally affect, the one the contrary end of the other, and doe auoide and flie from their ends of like denomination.

Now for a further consideration of these proper­ties suppose that you will cut of a peece of this Mag­net meridionally, viz. C. D: manifest experience will shew, that C, which did in nature participate with A. in the entire Magnet, E: (as being both of the true North part thereof) now being separated, will not abide it. In like manner D, of the other end of the little one, will not abide, B: of the great one, with whom being entire in nature he did participate, as being both true Southerly parts of the entire Magnet, E: And that because the ends of like deno­mination of any two Magnets, doe naturally flie the one from the other.

But here you must beware of an errour, which some vnhappily haue entangled themselues withall: who beholding the afore-mentioned discord (as be­tweene A: and C:) wrongfully supposed, that, if both these Magnets the greater and the lesse, were conueniently placed to swim in water the little one would not with his end C, point vnto the South of the earth, as it did in the Magnet being entire; where it was a part of the true North end, but would point quite contrarily. There is no manner of any such al­teration, but that both the great one and the little one (and all the like, that are cut meridionally one from another) will absolutely point the very same way which the entire one did, only you must know, that the meridian Line will somewhat be remoued [Page 15] in each of them from the diuision, as you may gesse by the two prieked lines, parallel vnto the meridian (or axis) A: B: of E. the entire one, and the disagre­ing of their ends is onely within the Orbe of their for­ces, both their generall dispositions towards the Earth euer continuing one and the selfe-same that it was at the first. Yea moreouer, place them so that they may freely swim within the orbe of their owne force, and they will (with very little helpe or none at all) conforme themselues in such sort that the one of them will ioyne it selfe endlong vnto the other, at their contrary ends, and point the same way both of them, the which they did at the first in the entire one. If you touch the end of any Magneticall needle vpon A, being the true North end of that Magnet, that end of the needle will become a true South end, and will point vnto the North of the Horizon: if you touch it vpon B, that will become a true North end, and will point vnto the South of the Horizon. And the like will it doe, if you touch it vpon, C: as when you touched it vpon, A, and vpon, D, as when you touched it vpon B, although in both these not so strongly; so that Doct: Gilberts assertion doth not gaine-say the Marriners opinion, that his Flower de Luce should not still remaine the North point of his Compasse, onely hee sheweth which end of the Magnet it is, which doth giue him that vertue, name­ly, that it is the true North end; so that if you hold the true North end of the Magnet neere vnto the Flower de Luce it will come vnto him: if you take away the Magnet, it will come vnto the North of the [Page 16] Horizon. If you will diuide a Magnet not meridio­nally as in the former example, but

aequinoctially, as in this by the pricked line, C: D. A. being still the true North end, and B: the true South end, and A: B: being the Meridian line, or axis of the stone: if you set these diuided seuerall peeces a sunder, that they may swim within the Orbe of their forces, they will affect to ioyne themselues in the very place where they were diuided, as also in the ends, A: vnto B: by the former reasons of contrary denomination. And if you place them a swimming without the Orbe of their forces, A: and B: will still yet retaine their former natures, and euen so will it fall out, if you make your diuision in any other place of the Magnet towards either end parallell vnto aequinoctiall of the Magnet.

CHAP. III. Certaine generall obseruations of the nature and properties of the Loadstone.

LOadstones of diuers and sundry parts of the world as of Norway, Elva, Bengala, &c. haue one and the selfe-same property directiue, I meane of shew­ing [Page 17] the North and South, and also the selfe-same points respectiue declining or dipping vnder the Ho­rizon. They doe likewise agree in their variations, and each one will draw yron, and likewise one an­other. Euery Loadstone, of what forme soeuer he be, hath either actually or potentially two points, the one Northern, the other Southerne. Actually, if either by casualty (if it so fall out) or by industry the stone be so fashioned, that those two opposite points be eminent or perspicuous therein: Potentially, if that either the stone be flat and but thin in the di­mension of North and South though broad other­wise, for so shall the vertue of the stone be dispersed to the extreame parts thereof, in the edges round about; or if it haue the two opposite points in any concauitie, then will the stone shew in the eminent border or edge of that concauitie onely a confused dull force, and in the concauitie it selfe very little or nothing at all. That stone is well proportioned for touching which resembleth an Ouall forme, and hath his due points in his ends, and is voide of any bunch or concauitie. For the generall forme of a stone be­ing good, euery concauitie is a diminishing of his force, and euery bunch is but a superfluous burden; Insomuch that my selfe haue made experience of a stone that of substance was very good, and of weight was vpon a three and twenty ounces, but of a disor­dered forme, I therefore tooke away twelue ounces from him, and yet diminished not one iote of his force. And this did I in a stone that was all of like substance. But if it be one that is intermingled of di­uers substances (as many such there are and those [Page 18] easily discerned by their colour) you may somtimes take away three quarters and more of his substance without diminishing any thing at all of his vertue. For colours, most commonly the Iron-like is best: very blacke or whitish seldome proues good; gray, indifferent; the more white in any stone, so much the worse. There are certaine that are of an yron colour, mingled with red, of which some bee very good, some but indifferent. By three waies you may proue whether a Magnet be good or not; the one is, by taking vp yron with the bare stone: The other by giuing more or lesse vertue vnto a knife, or any such thing to lift yron: The third if it will with good strength moue a Magneticall needle a pretty good distance of, and readily alter the ends of the needle without touching of them, making the North South, and the South North: The two latter of these doe neuer faile, but the first doth diuers times. And very certaine it is, that whatsoeuer stone doth most strongly impart his force vnto a knife, or moue a needle with quicknes, the power of lifting vp yron in such a one, will mightily be increased with a Cap. For this is generally the nature of all Magnets, that if there be 2. of different quantities, and equall strength in lifting vp yron, the greater will giue the stronger touch, and moue a Magneticall needle farther of, al­though the lesser will take vp as much yron, or some­what more, than the greater. And againe suppose there be a Magnet of a pound weight, that being fitly armed, will take vp foure pounds of yron, and not a­boue, if you diuide him into very small peeces, you shall finde of them being orderly vsed that will lift [Page 19] vp 20 times, yea 40 times his owne weight and a great deale more, if they be made very small, as of three or foure graines weight; And yet where the great one will giue a touch vnto a knife for to take vp foure ounces of yron, and will moue a Magneticall needle three foote of; this little one will not giue a touch vnto a knife to take vp a needle, nor moue a Magneticall needle foure inches of; that as a Magnet is diminished in substance (I meane a Magnet of a re­gular forme) so doth he loose in his vertue of touch­ing, and increaseth for his small quantitie in lifting of yron, whereby it is manifest that these two proper­ties goe not alwaies ioyntly together in the same proportion and degree. And here hence it is, that many seeing little Magnets artificially set in rings for to take vp (for their quantitie) a great peece of yron, doe wrongfully imagine that the great one (whose particles they are) or any other great one, should doe the like, namely to take vp so many times their owne weights. Also very often it is seene, that Magnets being of like forme and weight, but of diuers kinds, the one will take vp more yron of himselfe without the capp, and yet the other giue a farre stronger touch; but then, if you doe fit both of them accor­dingly with caps, he which gaue the stronger touch, will take vp more yron than the other. The princi­pall force of the Loadstone well proportioned, passeth in a direct line, from the middle of his substance, be­ing (as it were) a Center, through his two ends or points, which are the imaginarie lines of his chiefest force, from which Center, there issue infinite others also through all parts of the Superficies of the stone, [Page 20] on either side, betweene the two extreame points and the middle, all which on either side of the mid­dle, being of one nature and property in respect of their touch are exceedingly different in strength. For that still waxeth lesse and lesse, as it approacheth continually nearer and nearer the middle, where at length in the middle, betweene the two ends, it vtterly fainteth and commeth to nothing. The Loadstone communicateth his property to the yron or steele that is touched with it, so farre forth, as the yron, or steele, which is touched, hath habilitie to re­ceiue, and so that good skill in the touching be ob­serued, steele is farre better than yron, and receiueth a farre stronger touch, and much more effectuall. The purer steele, so much the better; and if it bee yron, the purer likewise, the better, alwaies regar­ding that both of them be very smooth, and cleane, and haue their due temper. The principall property in common vse is the shewing of North and South in the Horizon, with the appendants therevnto belon­ging, which is much more apparant, more strong, and more commodious in the iron and steele, that is touched, than it is in the stone it selfe, because the substance of them may be filed and cut away, and drawne into any forme, that we like or list our selues, which the substance of the stone will not permit. The Magnet is of such nature, that euery peece bro­ken of and separated from the whole, hath all the properties of the whole, the same seuerall points of North and South, and habilitie also for the touch, like in kinde, though not of equall power, according to the quantitie and proportion of the peece, and the [Page 21] part of the stone that it is taken from, and this pro­pertie in a meaner sort hath the touched needle and wyar of a Compasse also.

CHAP. IIII. By what meanes the chiefe points of any Magnet of what forme soeuer may easily be found out.

MAke a respectiue or declinatorie needle, of an inch or thereabouts in length and giuing him his touch, fasten him by his Axis vpon a little forked sticke, or any such thing, that the needle may haue free scope, then offer the stone neere the needle, tur­ning it round about, and immediately you shall see the North of the needle (as it is as yet commonly called, because it pointeth vnto the North) point directly vnto the true North end of the stone as soon as it commeth neere vnto it, and as you turne away the end of the stone the needle will point still some­what towards it, till the South end of the stone ap­proacheth, for then will the needle wheele about vp­on his Axis, and point directly with his South, and to the true South of the stone. But if you hold the needle neere the stone, in such sort that it cannot turne about at liberty then the force of the stone may soone change the properties of the ends of the needle, that the one point which was North shall become South, and that the other which was South shall become North, yet the thing it selfe is easily discerned: For the Northerly end will alwaies hang lower.

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And wheresoeuer the needle, being held neerer vnto the stone doth stand parrallell vnto it not incli­ning with either end, towards the stone there direct­ly, vnder the middle of the needle, the North and South properties of the stone doe diuide and part themselues. This matter is much better performed, with a smal narrow loadstone of halfe an inch (more or lesse) in length, hauing in the ends his due points of North and South and wrought ouer with silke of two colours from the midle to each end; as for exam­ple yellow and white; That part which pointeth to the North let it be wrought ouer with white, and the other with yellow. Then if you hang that in the midle by a fine silke thread, and apply it vnto a­ny other loadstone, the South end of the one will rea­dily finde out the North end of the other; and con­trariwise. In like manner, with this magneticall in­strument you may see two pretty conclusions. The one if you touch a knife with the end of a forcible loadstone, whether it be North or South, and hang this wrought one by a silke thread in the midle, that [Page 23] it may hang freely, the one end will craue towardes the point of the knife, and the other will not abide it. The other is, if you hang it end-long, with the true North end right ouer the North end of a forci­ble loadstone or with the South end ouer the South end of the other, you shall see that it will in no wise (being let downe) come vnto the North point of that loadstone, but will (contrary to philosophicall principles that heauie things should tend directly downewards) by the meanes of the silke thread, swimme or wheele about the end of the loadstone in the aire: yea and lift it selfe somewhat vpward, ra­ther then perpendicularly light downe vpon it, yea this it will do although you place a plate of siluer, lattin, or any such thing, betweene the stone and it selfe.

CHAP. V. The manner of capping both with single and double cappes and the nature of them.

THe stone being brought vnto his perfect forme you must haue a mould made of Iron of the ve­ry same proportion in euery respect and equall in all his dimensions, then setting the stone aside, let your workeman frame & fashion his cappes and fit them vpon this mould as if it were the stone, thus shall you be sure to preserue your magnet from many dangers, very incident vnto rude handling: And hauing so done you may set them on the stone it selfe, amen­ding any small faults, without endangering the stone, either with bruisings, or knocks; For the thick­nesse and largenesse of the cappes, there can bee no generall rule prescribed, but it must be left vnto the triall and ingenious dexterity of the workeman: as also for the handsome fastening either by soadering, or riuetting of them with lattin plates to the Caps to keepe them in their places firme and steddy, ac­cording as you see in this picture of a stone, armed with single Cappes.

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The double Cappes are nothing but two square or round knobs prominent and issuing out of the sin­gle Cappes (as neere as may be) at right angles with the Axis of the stone, agreeable to this forme, which was fashioned by a very skilfull workman

of Winchester, one that for all manner fashioning, cut­ting, soadering, peecing, and capping of Loadstones, is the most exquisite that I haue knowne, as Doctor Gilbert would also confesse, who had his best fashio­ned and capped by him; and so some Noblemen and diuers Gentlemen, to their great contentment, haue had the like. I finde not as yet any profitable vse of the double capping, but only for admiration, in taking vp a greater quantitie, more by the one [Page 30] halfe, then the two seuerall ends could doe each by it selfe: as if each end will take vp halfe a pound, be­ing capped in this sort, that each prominent end may lay hold vpon the iron fitted for it in this maner,

it ought to take vp a pound and a halfe and more: The reason whereof is this, because the Magnet, in touching any one end of a fitting peece of iron or steele, doth not onely infuse the vertue of that end, which toucheth the iron, into that touched end, but also the contrary vertue into the other end.

Now therefore in this position, both ends of the Magnet being applied vnto the two ends of the iron, [Page 31] these two contrary forces striue in this peece of iron, the North to repell the South, and the South the North: so that each force is driuen neerer his owne end, and becommeth there so much the stronger then otherwise it would be. For proofe whereof, take a little narrow square peece of iron, of the length of the capped stone, and ioyned in the middest with Copper after this sort:

A. is supposed to be a long square, or a square-like peece of iron, in length fitting the two double caps of a Loadstone.

B. a long square peece, the ends iron, the middle copper. C. hath a lesse space of copper, and D. least of all.

If you apply the Loadstone vnto A, he will hold A very strongly; but if you put any of the other three peeces vnder A, that it may touch any of them, hee will not by any meanes lift it vp. If you apply the Loadstone vnto B, he will take it vp very weakly, and C somewhat more strongly, but D strongest of all these three, yet not comparable to the strength [Page 32] wherewith hee taketh vp A. Againe, although the Loadstone taketh vp B but weakly, yet if you place B vpon A, he will take them both very strongly; yea more, place B vpon C, these two vpon D, all three vpon A, apply the Loadstone vnto B, being the vp­permost, and he will lift them all vp very easily.

The cause hereof is, when a Loadstone with his double cappe is placed vpon A, the force of both ends striuing in that peece of iron paralel-wise vnto the Axis of the stone, the North and South forces are driuen more closely vnto their proper ends. But in B, (because of the intermediate copper) there can be no such close driuing of his forces into their pro­per ends, as was in A: and therefore the Loadstone lifteth vp B, but only as if his two ends were two lit­tle loose peeces of iron, hanging in the aire, and the intermediate copper a burthen vpon them. But pla­cing B vpon A, A in the manner (as it were) of a bridge, ioyneth the two ends together into their for­mer combats, and the two ends of B, forasmuch as they are but (as it were) two loose peeces of iron han­ging in the aire, the two forces of the Loadstone North and South, distinctly and seuerally passe thorow them downwards into A, which it could not doe, if it had beene one entire peece of iron: and so all those foure peeces, being placed one vpon ano­ther, so that A be vndermost, whether directly or sidewise, the Loadstone will easily lift them all vp, and not otherwise.

When a Loadstone lifteth vp iron at one end onely, the vertue of the stone is infused into the whole body downward of that iron, if it be not very long.

[Page 33]But when by the meanes of the double cappes, both ends doe lift iron ioyntly together, he infuseth very small force downeward into the body of the iron that it lifteth vp for the forces of the both ends are so striuing in a collaterall line of the iron, paralell vnto the Axis of the stone, that whereas a good Magnet lifting vp at one end, will extend his vertue downewards twelue or fourteene inches, in apply­ing both ends vnto the iron, by the meanes of the double caps, hee will not extend his force downe­ward the distance of one inch, nor with any strength the distance of halfe an inch, as in this former ex­ample.

If a Magnet will lift at one end a pound of iron, fasten you halfe an ounce of iron vnto foure ounces of wood, or any other substance sauing iron, and he will neuer take it vp, because his vertue can pierce but onely that halfe ounce, and hath no power to enter into the other substance; and that small por­tion of vertue, contained in the halfe ounce, cannot hold vp the other strange substance. But this very same Magnet, by the meanes of double caps laying hold of a peece of iron fitted for the purpose, and of this fashion, being but halfe an ounce, may very well and [Page 34]

readily take vp three pounds of any other substance whatsoeuer that is fastened vnto it, because that the whole force of the stone being imployed in the strife of the contrary ends, in the iron paralell-wise, vnto the Axis of the stone, each end apprehendeth and lifteth vp this peece of iron and a great portion of any other substance that is fastened vnto it, and his whole force being imployed herein, all his former vigour, vpward, downeward, or endlong, is as it were fettered and imprisoned, that vntill you loose him of these fetters, hee is not able at either end to take vp one quarter of that which he did before.

Pliny in his naturall historie writeth, that Dino­crates that famous Architect builder of Alexandria, at Ptolemies commandement began to vault a Tem­ple with Magnets, that there might seeme to hang in the aire the image of his sister Arsinoe, made of iron [Page 35] for that purpose: but both Dinocrates and Ptolemie dying in the meane space, that enterprise ceased. Neither indeed (if they both had liued) could it euer haue come to passe by that means, by reason of two impossibilities: The one is, that by the force of the Loadstones, nothing can so hang in the aire, but that it either must touch the stone it selfe, or some other intermediate substance betweene it and the stone, that barreth it from comming to the stone it selfe. For example, lay two or three needles vpon a smooth table, put a siluer or pewter plate vpon them, and vpon the plate a Loadstone, then lift vp the plate aloft with the Loadstone lying still vpon it, and you shall see the needles hanging indeed in the aire endlong, and if you moue the stone about the plate, following still vnderneath, but euermore touching the plate, which is the intermediate body, that kee­peth them from comming to touch the stone, which otherwise by their naturall inclination very speedily they would doe. But as for that image of Arsinoe; how had it beene possible for it to haue touched at once, mediately or immediately, so great a number of Magnets, whereof the pretended vault must needs haue consisted? The other is, that such a multitude of Magnets would nothing but confound the one the others forces, so that one of them alone being soli­tarie and seuered from his company, might shew more force then al that insociable societie could doe, each one hindering the efficacie of the other. Much like a teeme of many horses, where euery one draw­ing his sundry way, might soone with disordered stretching tire himselfe and his fellowes, but neuer [Page 36] moue the loade one iot from the place. Insomuch as one (and possibly the worst) would doe more good alone, where hee might orderly and freely vse his owne strength, then hee and all the many of them could doe being ioyned together in vicinitie of bo­dies, but extremely distracted through contrarietie of courses.

The only way to performe such a matter (if it were worth a doing) would be to prepare one migh­tie great Loadstone of excellent goodnesse: which hauing his due proportion, after an extended ouall forme, should be sitted with double cappes, and so placed in the roofe of a building, that his Axis be paralell to the Horizon: in this sort (out of all doubt) a faire large image might bee held vp very strongly by such a Magnet, let the stuffe or substance thereof be whatsoeuer, (howbeit the lighter the better) so that there be fastened vnto the vppermost part of the Image a small peece of iron accordingly prepa­red and placed for the two prominent ends of the double cappes of the stone, to lay hold thereon. But enough hereof.

In the capping of Magnets, this generall rule is to be obserued, that they ought to be made of the fi­nest and softest iron, and not of steele: the waight also, which the Magnet taketh vp, should be of the like iron, and not of steele, as aforesaid. For although steele retaineth at the least ten times as much vertue as iron, when it is once separated from the stone, can doe; yet as long as there is any contiguitie betweene the stone and them, hee holdeth iron more strongly then steele. Both which differences in either of them [Page 37] by manifest experience are certaine, and seeme to proceede of notable fastnesse or closenesse in the steele aboue the iron; by meanes whereof the mag­neticall vertue doth longer and more forcibly conti­nue in that then in this: euen as fire more mightily possesseth, and for a greater space abideth in stone, or any such firme or solid matter, then in wood, or straw, or the like thinne and hollow substances: and therefore those compasse-makers, that make the wiers of their flies for sailing compasses of meere iron, ought not by any meanes to be suffered: for to gaine two pence in a compasse (and scarcely that) they intollerably abuse those that trauell by sea, to their great danger and mischiefe.

CHAP. VI. Of cementing and peecing of Loadstones.

FOr your Simmon, doe thus: Take the fine powder of a Loadstone, halfe so much powder of new bricke made very small and subtill, one part of Burgundie pitch, halfe so much Rossen, a small por­tion of vnwrought waxe: mingle all these together very well vpon a soft fire, and make the whole masse in little roules. Now when you will cement a stone, doe thus: heat the two peeces of the stone very hot, and likewise the simmon, then strake the places that you will soder, ouer with the simmon very thinly, and ioyne them somewhat hard together, letting them so stand vntill they be cold, and you [Page 38] shall haue it fully as strong, as if it were an entire stone of it selfe, and not to be seuered but by great heat of fire. In peecing of the Loadstones, there must diligent heede be taken to the nature of the Load­stone in generall, and also to those particular peeces which you would ioyne together. The Loadstone in generall (as it is shewed before) that his force issu­eth (as it were) from a center in the middle of the stone, to all the superficies thereof vniuersally, but most strongly vnto the Poles from the middle, one way the stone is all of a Northerly nature, and all of it Southerly the other way. For example.

A. is the North end, B. the South end of a Loadstone, D. the middle. Suppose you cut off a peece at C, then shall D. be no more the middle, but it shall be a part of the North of the stone, and the middle is re­moued neerer B, and the vertue of North and South doth not now diuide it selfe at D (as it did before) but D. is now become a part of the North end of the stone, which it was not before. In this example fol­lowing let there [Page 39]

be two Loadstones, the one longer then the other, the North of both noted with A, the South with B, the middle of the shorter, where the North and South properties doe part, is C. Suppose you will fasten these two with simmon, the end B. of the shorter vnto the end A. of the longer, so shall these two be­come one Loadstone, and not onely C, which was the middle (where

the North and South properties did part) in the lit­tle one, is now become a part of the North end in this conioyned Loadstone, but also euen B. it selfe, which was in the short one the very South Pole, is now in this become part of the North portion, the middle of this (where the North and South proper­ties [Page 40] doe part) being in E, and these two Magnets, which had each of them two points, the one North and the other South, being ioyned together, haue but only two points in all, the one North, the other South. Moreouer, if you haue two Loadstones (for example) of like goodnesse, about foure inches a peece in length, hauing their North and South points duly at their ends, if you cut off at either of their ends halfe an inch, and conioyne them with the contrary of the great ones, they will presently haue contrary properties vnto that which they had before; so that a needle touched before that would turne North, being now touched in the selfe same place will turne South, shewing that the vertue of the two ends doth alwayes proceed and extend it selfe from the body of the whole Loadstone, and from the whole, sheweth it selfe most forcible (as afore­said) in the ends; and either of the Loadstones will be in his perfect goodnesse, as at the first. If you thinke good to set two Loadstones together in such sort, that you would haue the augmentation onely in thick­nesse, and not in length, then doe thus: If they be both of one length, grinde them so that they may ioyne close, the broad side of the one agreeing with the broad side of the other, hauing North vpon North, and South vpon South, as in this example.

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A. must be ioyned vpon A, and B. vpon B: but if you ioyne the two so, that A. lighteth vpon B, you marre the new Magnet, by confounding his forces. Notwithstanding if you like to ioyne them in length onely, not in thicknesse, then indeed must you com­bine B. and A, and not A. and A, nor B. and B, lest here also you incurre the former inconuenience, of confusion of forces. Take another example: Sup­pose a Loadstone to bee long and somewhat round, smaller at one end then at the other, the smaller end to be North signed with A, the other South signed with B: let this Magnet bee diuided long-wayes into two equall parts, thorow both the Poles, A. and B.

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And let one of these halfes be placed vpon a peece of glasse or a smooth Table; certaine it is, that if you do offer to touch A, of this, with A, of the other, this A will turne away from that, which (the stone being entire) it did ioyne with before: Or if you offer B, vnto B, it will doe the like. And no maruaile, for in this case of touching A, with A, or B, with B: what else in effect doe you, but attempt to ioyne the two halfes in length and that at like ends? A thing dire­ctly repugnant to the principles of Magneticall Philo­sophie. But let me admonish you, to put the rounder side of the stone downewards, next vnto the glasse, that it may turne the quicker: yet if the stone be ex­cellent it will doe the same also vpon the flat side. Moreouer if you place this two halfes, the one vpon the other precisely as they were at the first, they will [Page 43] agree very well: because they are as one, and the selfe-same Magnet. But if you place them the one swaruing from the other, at either end, then will A, of the one, turne about vnto B, of the other; be­cause they are now as two seuerall and diuers Mag­nets. For the better conceiuing hereof, you are to re­member, that euery part of a Loadstone (be it an half or any other) being once diuided from the whole, is (as Schoole-men call it) Totum integrale, a whole Loadstone by it selfe, vtterly diuerse and estranged from that whole, whose part before it was, and therefore reteineth distinctly in it selfe, all the pro­perties of a Loadstone, though not so strong, as the whole had when this was ioyned therevnto.

In Loadstones there is a part truely said to be diui­ded from the whole, when the points of that part, or ends, or Poles (and so, by necessary consequence, the Axis and Aequator, in which the vniuersall frame of Magneticall power consisteth, haue a position di­uers from the Poles or points of the whole. For this cause, in the last example the one halfe A: B: being supposed to swarue from the other halfe B: A: at ei­ther end, must needs presently be diuided from it, and now cannot be pars integri, but is of necessitie Totum integrale, a seuerall and absolute Magnet of it selfe, and so by an essentiall property common to all Magnets, coueteth with his point A, the contrary B: of that which is vnder it. Wherefore like as exact agreement is betweene two Mathematicall figures when being applied together, the extreames of the one, doe precisely fall vpon the extreames of the other, each vpon his correspondent extreame, and [Page 44] is made one therewith: euen such is the perfect composition or setting together of the parts of a Magneticall body, and namely of those two equall parts before exemplified, you must so ioyne one vp­on another, that the two extreames, or ends, be al­waies of the same nature Northerly, or Southerly, in both parts: And that by due application of the parts, the two Northerly ends be vnited, and be­come one, as also the two Southerly ends after the same manner. But if these parts, being of equall length be ioyned longwise, the North of the one, vnto the South of the other; those two ends that were (being now no ends but the iust middle of one Magnet) haue lost their properties which they had, when they were ends. For those properties, by this vnition, are abolished: but their other ends still re­serue their former and stronger vertues of North and South: And so, according vnto Magneticall nature, one Magnet shall haue but two Poles, the one North, the other South. Againe, if you will peece two Loadstones together in thicknes, the one of thē being longer, than the other; then you must either cut the longer, that it may be fit in length, vnto the shorter; or else peece the shorter in such sort as is afore descri­bed that he be equall in length to the longer, & what soeuer disorderly parts perhaps shall bee in any of them, they may, euen after they are cemented, very well be ground away. Also if there bee holes or dents, with little peeces of Loadstones cemented (their points being obserued) they may be filled vp, without any manner of dammage or deformitie, no more than there had not been any such at all. And [Page 45] after this method you may (with labour and indu­stry) of many Magnets, make one as huge, and of what forme you please. And although the Magnets of this body, magnetically compact (as I haue here shewed) were neuer so many in number, yet the whole will haue but two principall points, the one North, the other South, euen as if it were one natu­rall Loadstone: and all of them will contribute their forces, vnto those two points; So that if there were twenty of them, being after this order cemented to­gether into one body, the whole would haue but two points, but if you will place them in a vault, ac­cording to a Masons trade they will haue 40 points, twenty North, and as many South, and will worke the like effect in drawing yron, as (to vse the former grosse similitude) if a teeme of horses were set in their traces contrary the one to the other, the one to pull one way, the other another. As for the Turkes Mahomet, hanging in the ayer with his yron chest it is a most grosse vntruth, and vtterly impossible is it for any thing so to hange in the ayer by any Magneti­call power, but that either it must touch the stone it selfe, or else some intermediate body, that hindreth it from comming to the stone (like as before I haue shewed) or else some stay below to keepe it from as­cending, as some small wier that may scantly bee seene or perceiued.

CHAP. VII. Of the variation of the Magneticall Needle with the Appurtenances therevnto belonging.

THE variation of the Magneticall Needle, be­ing aptly fitted and placed vpon his pinne, is nothing else, but the swaruing of the pointing thereof in the Horizon, from the meridian line there, the portion of the Horizon intercepted betweene the true Meridian line and this pointing, sheweth of what quantitie the variation is, and giueth it his name, to wit, which way it lyeth, either Easterly, or Westerly, and it is obserued by either end of the nee­dle as you please.

In times past men obserued onely by the North end of the needle, because they vnderstood not that the Loadstone hath a South vertue, as well as a North; And therefore did touch their needles and wyars of their compasses alwaies for the North onely, leauing those ends of the wyars bare, that they might be re­freshed with a new touch at any time afterwards: but the other ends they couered, not knowing that they were also apt to receiue as forcible a vertue from the Loadstone for the South, as the other for the North. For the right vnderstanding of the variation, with his necessary dependants, wee must vse the meanes of two circles: The one of them I will call the Magneticall Almicanter; The other is already knowne by the name of the Magneticall Meridian.

This Magneticall Almicanter is a circle paralell vnto [Page 47] the Horizon, whose center is the verticall point, and is described by the distance betweene the verticall point, and the neerer Pole of the earth. The true Magneticall Pole is the pole of the earth; The magne­ticall respectiue Pole, or (which is all one) the Pole of the Magneticall Meridian, is a point in the Magne­ticall almicanter, distant Easterly or Westerly from the true pole as many degrees in that almicanter, as the variation of that place containeth in the Hori­zon, but alwaies it is in the contrary part of the true Meridian, that is, if the variation of the South point of the needle be Easterly the respectiue pole is We­sterly: but if you obserue with the North end of the needle, the respectiue pole and the variation are both one way in all our Northerne Climates. If the variation of the South point of the needle bee We­sterly, then is the respectiue pole so many degrees in the said almicanter Easterly, and therefore alwaies of the same height with the true pole aboue the Hori­zon. For since all great Circles of the globe doe ne­cessarily cut one another in two points into two e­quall parts: these two therefore must needes doe e­uen so in the Zenith and Nadir, by their very defini­tions; So that these two points (the Zenith and Na­dir) are alwaies alike common vnto them both, aswell vnto the true, as vnto the Magneticall Me­ridian.

Where-hence it followeth necessarily, that al­waies the one halfe of the magneticall meridian is on the East-side, and the other on the West side of the true meridian, the common Zenith and Nadir euer­more keeping their equall distances from the Poles▪ [Page 48] of the one of them, as they doe from the other. For example: Suppose the common Zenith to be in the Aequator, you sayling East or West, as long as there is no variation, there is no magneticall meridian, there are no magneticall Poles, but those of the world. But as soone as, sayling still vnder the line you doe finde a variation it is the magneticall meridian, that by his swaruing from the true meridian of the world in the Horizon sheweth the quantity of the variation, and giueth it also the denomination of Easterly or We­sterly, and his axis is the line of variation. But sup­posing the common Zenith, to be in any paralel, be­tweene the Aequator and the Pole, then is it not the axis, but some other Diameter of the magneticall me­ridian, which sheweth the variation in the Horizon; And the magneticall meridian euermore cutteth iust so many degrees of the magneticall almicanter on the one side of the true meridian, as the same Magneticall Pole is distant in the same almicanter, on the other side of the true Meridian from the Pole of the World. And this is to be vnderstood in correspondent man­ner, as well of the South Hemisphere, as of the North.

The respectiue Magneticall meridian (where any variation is) is a circle that passeth by the verticall point and the Nadir, and both the respectiue Poles, crossing the Horizon at right angles in the points of variation, of which circle the line of variation is a Di­ameter, but where there is no variation the true and Magneticall meridian are both one & the selfe same, and so in like manner are their Diameters. Those cir­cles and poles are tearmed respectiue because that in [Page 49] euery place where any variation is, the Magneticall needle doth respect them, as well in the property of direction, as in that of declination, or inclination. For thus also very well it may bee tearmed. By the property of direction, I doe meane, with Doctour Gilbert, the Horizontall motion of the Magneticall needle: By the declination, or inclination, I meane the descending, and (as it were) the sinking motion of the neede vnder the Horizon, in his proper Azi­math, or Magneticall meridian; But if there be no va­riation, the needle alwaies pointeth vnto the true Meridian of the earth, and towards the Poles therof, in both those properties. The true Poles of the earth (which are those two points equally distant from each part of the Aequinoctiall of the earth are alwaies the selfe same. The respectiue Poles alter with euery Horizon, where there is any variation, but neuer out of the aforenamed almicanter of that place. The causes of the differences of the respe­ctiue Poles and Meridians from the true Poles and me­ridians, and so of all variations, are onely two; The chiefe and most generall is the vastenesse of the O­cean sea, by moistnesse whereof the Magneticall col­laterall force of so much earth as it couereth, is much hindered and dulled. And by that meanes the next great Continent hath more power ouer the corre­spondent end of the Magneticall needle, then other­wise it could haue if all were alike one entire Conti­nent: and therefore causeth the directiue property of the needle somewhat to swarue towards that way, which is that, which we call variation; but yet the vastenesse of the Ocean doth not hinder the decli­nation [Page 50] of the Magneticall needle; Because his hang­ings consisteth but in length and breadth, and not in depth. For although in comparison of a pond or ri­uer, the sea is said to be of a wonderfull depth, yet if this depth be compared with a Semidiameter of the earth, it beareth a very exceeding small proportion, nothing at all to hinder the mightie magneticall de­clinatory force of the whole earth; For the greatest depth that euer any man of skill esteemed it at, was not aboue two English mile, at the vttermost, when as daily experience maketh it manifest, that a great Continent wil shew his Magneticall collaterall force, by causing a variation, aboue two hundred miles of from the place, and therefore Doctor Gilberts feare in that point I take to be needlesse, supposing a va­riation of declination. The second cause of variati­on, is any great mountainous region not farre of, when a man is in some great Latitude towards either of the Poles: if that mountainous region lie Easterly or Westerly from you, it will cause the needle some­what to swarue that way. But variations of this sort are of small continuance, and in sayling subiect vnto sudaine alterations, yea many times quite con­trary from Westerly to Easterly & afterwards backe againe within short space: as our first famous Pilote Steuen Burrough found by his experience in the dis­couery of the Scythian sea-coast between the north Cape of Finmarke and Vaygates. The reason where­of ought heedfully to be regarded which is that the Magneticall force of the whole earth, doth (as in all Magnets) shew it selfe most strongely in the two Poles thereof, and in those places which are neere vn­to [Page 51] them: but alwayes it must be remembred, that all the force they haue doth issue out of the whole terrestriall body, as it doth likewise in all Magnets out of the body of the Magnet: and therefore in any part of the superficies of the whole terrestriall body, it is impossible that any variation be aboue 90. de­grees, because the vertue of the whole can neuer bee ouerswaied by the imperfection of a part, and espe­cially of so small a part as any one portion of the Ocean is in his very superficies, in respect of the bo­dy of the whole earth: yea I am thorowly perswa­ded, that there neuer was nor euer will bee any variation, by any good obseruation found for to bee so much as ninety; neither any shew of so great variation any where, except it bee very neere vnto either of the Poles, where there is small credit to be giuen to the obseruing of any variation: for the variation being (as aforesaid) the difference of the pointing of the magneticall Needle in the Horizon from the true Meridian, for asmuch as in places neere the Pole, there is no manner of cer­taintie of either of these, it is not possible to finde the variation, if there be any. The reason whereof is this, no man may trauell those Seas, but whiles the Sunne abideth on that side of the Aequator, where­by they haue continuall day, and by that meanes are secluded from any helpe of the starres, neither if they might bee seene, would they bring any great helpe. For the difference of heighth in many houres is so small, that by a very large instrument a diligent obseruer with great paines will hardly finde the Me­ridian Line, all the Meridians themselues comming [Page 52] so neere one to another, and meeting in the Pole, and their Horizon being in a manner paralell vnto the Aequinoctiall. And as for the horizontall mag­neticall Needles, to shew their pointing in the Hori­zon as they were wont to doe, they comming into this climate may say, Fuimus Troes. Their direction is as it were giddy and vncertaine, and when their center commeth vnto the Pole it selfe, it is quite va­nished away; for from thence all the points of the Horizon are onely South, if it be at the North Pole, and North from the South Pole, and therefore in that place the instrument of declination is farre more sure then the Horizontall Compasse. And as in the Poles themselues there is no direction at all, so of necessitie neere vnto them it must bee a very confused direction. Those two places, that are cal­led the Poles, haue no strength of themselues (as aforesaid) but as it is contributed vnto them of the whole. As in a Magnet, if you breake off a peece of the contrary end, the end that is left will bee accor­ding vnto that proportion diminished in his strength, and the polar peece, that was broken off (be it neuer so little) will haue two poles as well as the great: so that the two parts will haue foure Poles, two of them North, and two South. Put this little peece that was broken off, in his place againe, and then each peece will lose one of his Poles in the same very instant, and the whole will haue but two Poles, the one North, the other South, as at the first. Againe, if you cut off a peece of one side of a Loadstone, that is brought into a round or an ovall forme, hauing his Poles marked in their due places [Page 53] at each end, presently both end will be abridged of part of the force they had, and the Poles themselues will be remoued vnto the other side, from the places that were marked, and those markes will stand but for idle ciphers in comparison of that they were be­fore. Againe, take a Magnet of a round or an exten­ded ovall forme, (I doe still exemplifie in these, be­cause they are of all others, as I haue often admo­nished, for all magneticall proofes the most excellent formes) and set markes on the two Poles, take a fine needle, or any straight small wier, and set it on the aequinoctiall, (I meane thereby the middle be­tweene the two ends of the stone) then will it point directly towards each Pole, if the stone bee sound without any flawes, or any other grosse substance (as may bee) intermingled with it: and if you thrust this needle towards either end, according vnto his owne direction he will trace you a circle right ouer both of these marked Poles, which is the true Meri­dian of the stone. But if this stone hath in either of the sides any imperfection, when the needle com­meth vnto the edge or brinke thereof, it will swarue somewhat towards the sounder side, and will point to neither of the true Poles. And if a circle bee drawne according to his pointing, as hee standeth still in that place, this shall be a respectiue Meridian of that stone, proper vnto that place: and the Poles. the respectiue Poles, differing from the true Meridi­an of the stone and his Poles. Now if you thrust the needle further towards the end, vpon the brinke of this imperfection, it will not point (as before) but either further off, or neerer towards the true Poles▪ [Page 54] and will giue his direction for a new respectiue Me­ridian; and new respectiue Poles, And in such man­ner infinitely, if you place the needle in the middle of this imperfection, equally distant from the sound parts, then will it indeede poynt towards the true Poles of the stone, And the Consequence heereof is the maine reason, that towards the midst of the O­cean; and likewise of any great continent there is no variation. Thus may you especially in a round Load­stone (as in a liuely example) see the true causes of all the variations that are in the whole world, reckoning as much space as the Ocean couereth, to bee some imperfection in the body of the whole, in respect of the Horizontall motion of the Compasse. For the euidence of the truth heereof, let a man examine ge­nerally the variations of our most expert Nauiga­tors (Although by reason of their diuersities of the sets of their Compasses, and vnfitnesse and vnapt handling of their instruments, they very seldome times agree among themselues) obserued in the At­lanticke Ocean, from the Aequator vnto the parts of Norway, all along the East coast from the Meridian of the Azores: And in like manner from the Aequa­tor to the parts of New-found-land and vpwards, all along the Westerne Coast from the Azores, as farre North, as heereunto hath beene discouered, and he shall finde the ordinary practise to testifie the truth heereof, as also after the same sort from the Aequator Southward vnto the straights of Magellan, and all a­long the backeside of America in the South Sea: and on the East Coast vnto the Cape of Bona speran­za, and he shall perceiue the like agreement: But in [Page 55] sailing from the Cape of Bona speranza, farther East­ward, that sometime they doe finde it otherwise, the cause is the different manner of the scituation of the South, as yet vndiscouered Continent. And wheras in the middest of the Atlanticke Ocean, about 30. leagues Westwards from the Azores, they find no variation at all, no maruell thereof: For it is about the middle distance betweene the two great Conti­nents of America and ours.

Wherefore the round Loadstone is significantly termed by Doct. Gilbert Terrella, that is, a little, or rather a very little Earth: For it representeth in an exceeding small modell (as it were) the admirable properties magneticall of the huge Globe of the earth. Heerein also wee may beholde the reason why, the magneticall needle varieth least in the Ae­quinoctiall, and most towards the Pole, and in the Poles themselues giueth no direction at all: For proofe heereof, take a needle and place it vpon the Aequinoctial of the stone, there you shal see him stand equally ballanced and very strongly, so that if you turne him from his direction, as soon as you let him goe, hee will presently turne vnto it againe. The reason is, because each Pole doth equally strengthen his correspondent end of the needle. Mooue this needle toward either of the Poles, then doth the neerer Pole strengthen his end of the needle; but the farther (because of the distance) cannot doe the like vnto his, but very weakly, and this needle will not stand any more equally ballanced (as it did in the Ae­quinoctiall) but that end next the Pole will couch downe, and the other will rise vp. For on the North [Page 56] side of the Aequator, the true South end is predo­minant, and on the other the North end hath the mastery. And that this is also in the earth it selfe, all our late Trauellers confirme vnto vs by their daily experience, and all the very Artizans and needle­diall-makers in the world must needes be daily wit­nesses of it. As for example: Let any workman in our Climate make a needle for a diall, when he hath fitted it and placed it on the pinne, that it may stand thereon equally ballanced and paralell to the Hori­zon touch it with the Magnet, then presently that which pointeth towards the North will hang downe (yea, although you touch onely with the South end) and will not stand, as before the touch e­qually ballanced and paralell to the Horizon: ex­cept you cut or file somewhat from that end, that hangeth downe; or else adde a peece of waxe or some other thing vnto the other end of the needle to counterpoise it, and make it stand equidistant as it did at the first setting on: and this is a thing very cer­taine, that this Northerly descent of the needle, will be more or lesse in all places of Northerly Latitude: In the greater Latitude the more, and in the lesser Latitude the lesse. But if any traueller carry this needle beyond the Aequator in the like Latitude Southerly, that end which tendeth downewards in the Northerly, will rise vp in the Southerly, and the other sincke downe, euen as much: and the neerer you trauaile towards either Pole, the more, that end which pointeth towards the Pole, will tend downe­wards: This is most certaine in euery Diall-needle: but a great deale more apparant it is in a long one, [Page 57] then it is in a short one. Wee cannot find that the property of direction by the Magnetical needle hath beene vulgarly practized (for sailing) much aboue 200. yeeres. And as for the property of declination vnder the Horizon, thereby to shew the Latitude by the Instrument thereunto belonging, it is as yet a very new-come guest into the world, borne and bred with vs in England, and (except it bee in excee­ding few mens hands) not yet in vse, much lesse come vnto his perfection. But this it not to be mar­uelled at: because it is scantly sixteene yeeres olde; neither is it to bee wondred if any Criticall fellowes doe contemne and deride it. Forasmuch as either their want of knowledge, or of patience, will not giue them leaue truely to consider of it. But what Nauigator, or rather Nugator soeuer contemneth it, shall bee sure to repent it if euer hee come to his right wits to consider what it is that he hath contem­ned. And although the needles for direction and de­clination doe differ much in their shapes, each from other; yet the properties are both one and the selfe same. For the needles for direction doe decline (as aforesayd) as farre as the vnfitnesse of their forme and placing will permit them: and the declining nee­dle will not worke, but onely in his Magneticall Me­ridian, which himselfe will finde out, if you turne the Instrument about, vntill the needle shew his least de­clination vnder the Horizon, and there doe play vp and downe & stop in the end in the same place again. But if you would haue a needle fitted to shew both properties, doe thus, cause a needle to bee made a bout sixe inches long, euen and smooth, sauing that [Page 58] he must be a little bigger in the middle, then insteed of an Axis (which declinatory needles haue) let him haue a small hole drilled precisely in the middest, and this hole being very small, let it bee somewhat wider outwards on each side then in the middest, (which our workmen call sinckboared) where it must bee left very sharpe, euen almost as the edge of a knife: put through this hole a small verginall lattine wiar, and fit the needle so that it hang precisely euen vpon this wiar, insteed of an Axletree: then touch him with the Loadstone, and you shall presently see the end that should point towards the North, de­cline or bend downe to his due place of declination, if he be placed in the Magneticall Meridian; set a little peece of waxe or any other thing vpon the contrary part for a counterpoyse that the needle may stand paralell with the Horizon, then if it stand at right angles with that verginall wiar, it is certain­ly in the Magneticall Meridian: otherwise it will ne­uer stand at right angles, but will make his sharper angle alwayes towards the Magneticall Meridian. So that hanging in this counterpoise if you turne a­bout the wiar vntill the needle doe make right An­gles with it, then doth the needle by his directiue vertue poynt vnto the Magneticall Meridian line. Take off the counterpoise, then it sheweth the declination for that place, and by consequent the Latitude, if you in that manner place him in the Instrument of declination; so that one and the selfe same needle in the same place onely, by taking off, and putting on a little peece of wax, sheweth plainely both those pro­perties of directions and declinations, as in like man­ner [Page 59] euery inclinatory needle will doe, if the poynts of his Axis be sharpe, and held in his boxe paralell vnto the Horizon, he will shew both those proper­ties of direction and declination: A fine peece of corcke or leather, or any tough snbstance may serue this needle for a counterpoyse in all Latitudes by thrusting it towards the center in lesse Latitudes, and towards the end in the greater, and I thinke it not impossible, but that a skilfull Geometrician may so graduate the one halfe of such a needle, that it alone with his counterpoyse, may bee a meanes to giue a probable coniecture for the Latitude of any place whatsoeuer.

CHAP. VIII. A discouery of errours committed in making and touch­ing Magneticall Needles and Wyars of sayling Compas­ses, with an aduise for the true and right making and touching of them.

FIrst the wyars that are commonly made both with vs, and in forraine countries, are of so base and drossie iron, not apt nor sufficient to receiue the tenth part of the vertue that fine steele wyar could doe.

Secondly, the ends of the wiars bee for the most part not filed smooth nor fitted euen together vpon the Axis of the flie; By meanes whereof the touch of the stone is more dully receiued, and the standing [Page 60] of the flie, the more vncertain, the magneticall force not being in the true axis thereof.

Thirdly, their manner of touching the wiars is al­together pittifull and ridiculous. For with a Mag­net hauing a point (for seldome times they haue a stone so well fashioned, that both poynts are emi­nent) that toucheth to the North (And such an one, though hee bee but weake is preferred among them before another, thogh much stronger that toucheth to the South) they rub to and fro those ends of the wiars, which they would haue stand Northerly. Wherein what doe they else, but play (as it were) fast and loose, not considering (as the truth is indeed) that euery touch from the ends of the wairs to­wards the Center of the flie with-draweth backe­again that force, which the contrary touch did giue them, and therefore seldome giue they aboue one quarter of that strength, and somtimes not so much, which otherwise with the very same stone they might doe, if they ordered all things as they should: yea, I am infallibly assured (for I haue had certaine experience of it) that with the selfe same stone, you may giue fully as much, and rather more force, tou­ching in such sort, as immediately shall bee declared on the vpper face of the flie: ouer against the wiars (the card being betweene) then they doe by touch­ing the very end of the wiars themselues after their wonted fashion: whensoeuer therefore a needle is to be touched, besides the goodnesse and quantity, you must haue a regard to the forme of your stone, name­ly, whether it hath both the North and South points eminent and forcible, or onely the one. For if it hath [Page 61] both, beginne your touching neere vnto the middle pressing the true North point, before specified of the stone all along from thence, vnto the North pointing end of the needle; iterating those touches foure or fiue times, alwayes making some stay with the stone at the end of the needle. The like also must you doe from the middle with the other end of the stone vnto the other end of the needle. But if the stone haue but one forcible point, then if it bee the true North, begin your touching at the South pointing end of the needle, pressing it all along to the North, end, itterating this foure or fiue trmes, and then once or twise onely from the middle vnto that end, If the stone hath but the South point, touch the needle ac­cordingly from the other end; For euen as the vertue of the stone it selfe is a Semidiameter (hauing his be­ginnning (as before is mentioned) in the center of the stone, euen so the force which he imparteth vnto the needle, is in the nature of a Semidiameter from the middle of the needle. Insomuch that a needle being touched from the middle, but to one end with the North of a stone, it doth not onely cause that end to turne North, but it transmitteth also a contrary force from the middle into the other end of the nee­dle, so that the stone be good, and the needle but of a reasonable conuenient size, as you may euidently trie in euery knife of ordinary goodnesse and length. But a plate of steele made at both ends alike, accor­ding vnto the forme heere aboue described, is much better to shew this effect. For when the blade of a knife is of fine mettall, the haft being of course iron, and also of a diuers forme and temper, it is not any [Page 62]

way capable of the like force as the blade is, which is the reason that if you touch the blade of an iron-hafted knife from the haft vnto the poynt with a Magnet, it will at the poynt take vp his competent waight, touch it backe againe vnto the vttermost end of the haft it wil take vp little or no­thing: Try the like with such a plate or steele, and you shall finde it take vp fully as much at the one end as it did at the other: but if you will bring his touch vnto the middle, it will take vp little or no­thing at any end, and nothing at all in the middle it selfe:

[Page 63]

The reason heere of is this, the Magnet giueth his force (Secundum mensuram recipientis) according to the capacity of that which receiueth it, and that e­uer more after his owne nature, which is to haue his force strong in his ends, and none at all in the middle, if you touch the blade from the middle, with either end of the stone, the other end of the haft will immediate receiue and shew the contrary quality: euen so al­so will it come to passe, if you make proofe with any Magneticall needle, although that his force will bee faint and weake in comparison of the other. And in your touching you must ob­serue, that in pressing with the stone from the middle of the needle vnto the end, as you bring your hand backward to iterate the touch, you must lift your hand somewhat high, and not bring it backeward, close to the needle. For that would diminish the strength of the touch. But if that end of the needle be also touched with the other end of the stone, in manner as aboue I haue rehearsed, then shall hee at each end be a great deale the more strong, and the contrary fainter forces shall recoile and settle in the middle of the needle, where they can nothing at all disturbe the motion thereof.

CHAP. IX. Of the touching with a Laadstone capped and without the cappe.

BY capping, is meant the placing of two peeces of iron handsomely fitted and fastened vpon the two points of the stone, for iron for this purpose is better then steele. And likewise concerning the the waight that is to bee lifted vp, it is better to bee made of soft iron then of steele, and the stone will lift more therof, as long as there is contiguity: but if if the iron and steele be separated from the contigui­ty of the stone, the steele will alwayes carry at the least tenne times more vertue then the iron, as is be­fore mentioned. Now whether it were best to touch the wiers with a Magnet being thus capped, or with the bare stone it selfe, some there be that make a que­stion. I haue beene tolde by one of great skill and practise, that he found by experience, the Compasse touched with a capped stone, not to receiue his force so well, as the other, and the party comming vnto me, when he was to vndertake a long voyage, to haue his compasse touched, requested mee in any wise to doe it with the bare stone: But yet I thinke it were good, that this bee confirmed by more then one mans experience, before it be beleeued, because by some error he might possibly mistake the matter. Sure I am that the capped stone giueth somewhat more vertue in his touch, and by all experience that I haue made, I finde it to continue as firmely and as [Page 65] long. Howbeit I referre mee heerein to the ttiall of others also. A man may therefore touch the wiars first with the bare stone, & then with the same being capped, or contrariwise to bee surer of the greater force, and yet if any shall imagine the difference of the strength of the touch, to be according to the ta­king vp of iron with the cap or without it, he is very greatly deceiued. For I haue osten tried them both, but neuer could see the touching strength in the nee­dle to be increased halfe a quarter more with the cap then without it; whereas I haue alwayes (especially if the stone were very good) found that the stone wil lift at the least ten times as much iron: yea, a great deale more, (and sometimes twenty times) with the cap (if it be artificially fitted) then he is able to doe without it.

Some, who would seeme to be of great skill, haue imagined, that the best way to adde strength to a needle, is with a hammer to giue some forcible strokes to one point of the stone, thereby causing lit­ragges (as it were) or beard, to hang downe from it, & that the needle in his touching, taking some part of that with him, should haue the stronger touch. But they that so suppose deceiue themselues therin: for that beard is nothing else, but the fine dust of the stone, hanging together by vertue thereof: which being separated from the stone (although it were a right good one) is not able any whit at all to turne a needle of it selfe. The triall is soone made by this meanes, let them take of that beard from the stone with a sticke, and lay it vpon the end of a needle not touched, and they shall finde in it no force at all, nay [Page 66] it is a hurt vnto the needle. For it giueth a superflu­ous burthen for a small time, and cannot but incum­ber his action, by reason that euery one of those lit­tle parcels of dust (though beaten out at one end) hath also for his small quantity both a North and South vertue. And therefore marreth as much as it maketh at either end of the needle. The proofe heereof is manifest, if you put off that dust or beard vpon a paper, and hold a Magnet therunder, for as you turne towards the paper the North or South of the stone, so will euery one of those particles in like sort turne it selfe, shewing thereby a double nature.

CHAP. X. Of the fashioning of the compasse needle.

THe Compasse needle, being the most admira­ble and vsefull instrument of the whole world, is both amongst ours and other nations for the most part, so bungerly and absurdly contriued, as nothing more. And therefore entreating now of the nature and vse of the Magnet. I haue thought good, also, to employ my best endeauour, to aduance this noblle instrument towards his highest perfection, being the principall thing, by which the worthy effect of the Magnet, is made most profitable vnto mankinde. Heerein fiue things are to be considered, the sub­stance that it is made of, the forme, the waight, the capitell, and the pin it standeth vpon: The substance [Page 67] in any wise ought to bee pure steele, and not iron. For most assuredly steele will take at the least tenne times more vertue then iron can doe, but especially if it hath his right temper. And that is this: Heat it in the fire vntill it be past red hot, that it be whitish hot and qnench it in cold water suddenly: So is it brickle in a manner as glasse it selfe, and is at that time incapable of the vertue of the Loadstone. Then must you, laying it vpon a plaine table, warily rubbe with fine sand all the blacke cullour from it, if before you put it into the fire, you annoynt it with soape, it will scale white of it selfe, then heat a barre of iron well neere red hot, and holding one end of the nee­dle with a small paire of tongs, lay the other end vp­on the hot barre, and presently you shall see that end turne from white to a yellowish, and after to a blew­ish cullour, then take that end with your tongs, and doe thlike vnto the other, thrusting it forward vpon the barre vntill the cullour of the whole needle be­come blewish: then throw it on a table, and let coole of it selfe: and so is he of the excellentest temper, and most capable to receiue the greatest power from the Magnet. If this seeme too curious especially for some fashions of needles, then vse but the hammer harde­ning (as workmen call it) which is well neere as good. As concerning the forme, diuers men are of diuers mindes, some vse a kind of square one, others a loop (I meane an extended ouall forme) and this is most common. But now a dayes, a narrow straight place (being somewhat broader in the middle) is in great request: Of these three I holde the loope or ouall forme (if it bee well made) to bee the best, which is, [Page 68] that if it be of steele, his ends be welded together, ha­uing a lattin narrow plate, issuing from the capitell vnto the middle of the two sides of the Loope, and there riuetted, and riuetting, if it bee handsomely shouldered in by the workman, is better then soade­ring: because, hauing fitted the lattin plate bearing the capitell vnto the Loope, you may first put your Loope into his temper, and then riuet this vnto him afterwards, which otherwise would bee marred in the fire, and the wide Loope is better then the nar­row or the straight plate, and that for two reasons. The one is, hecause, as in a Magnet it selfe, the force that is in the whole body, sheweth it selfe most strongly in his two poles, euen so this being a Mag­neticall body, doth the like in his ends which are his poles: and the sides of a wide compassed Loope (be­ing longer, then of a narrower) of the same length, in the Axis, must needes containe so much the more vertue; the other reason is, because it supposeth the flie in his circular motion more equally ballanced then the other: and therefore were it not for some o­ther inconueniences, a true circle were best of all, which is that except you marke the two places, that you would haue for the North and Souch, very curi­ously, you shall neuer giue him the right touch: yea, very exceeding hardly, although you doe marke them; and also the lattin stay, that holdeth the ca­pitell, would bee exceding long and a superfluous burden: but the very best forme of all (as I take it) in all respects is this, a true circle, hauing his Axis going out beyond the circle, at each end narrow and nar­rower, vnto a reasonable sharpe point, and being [Page 69] pure steele as the circle it selfe is, haning in the middest, a conuenient receptacle to place the capi­tell in.

This circle must haue foure very small holes drilled through it, equally distant each from other, for the foure cardinall points, and in both the two poynts, that issue without the circle, being for North and South of equall distance betweene the circle and the end of the poynt two moe, if it be a large one, other­wise one is enough, according vnto this picture fol­lowing. And this needle is most fit to be vsed for the obseruation of the variation alone without any flie, as I will shew at the latter end of this Treatise.

[Page 70]

[Page 71]Whensoeuer you wil set this needle vnto the fly, you must put the capitell through the center of the flie very precisely, and placing the points of the Diame­ter where you will haue them, thrust little small pins through the vpper face of the flie, and those small holes in the needle, the heads of the pinnes will shew you (if the flie bee larger then your needle) at what poynt your needle standeth, and bowing the body of your pinnes (being thrust through those little holes) close to the card below, will keep it steddy at that place, and from warping also. And so foure pins at the foure cardinall points will serue the turne.

Againe, if you please for to place this needle vpon the vpper face of the Card according vnto Steuinius. it is no more but to haue the capitell loose, thrust thorough the center in the bottome of the flie, and the needle placed and fastened on the top, or vpper face of the carde.

But if you will haue a Magneticall needle to serue onely for one size of a flie, the best way is, insteed of the two pinnes in the ends of the Axis, to haue a couple of little halfe staples and a Flower de luce on one of them, as you see in the Loope, riuetted there. That in turning about the needle, they may still keep the flie close vnto it, and so fasten it with a skrew vpon the capitell wheresoeuer you please.

As for his waight it must bee according vnto his largenesse, and the waight is one principall cause, that very large compasses are vnprofitable. For the waight of the large carde, and heauy needle, pressing vpon the pinne, will cause the motion of the flie to be dull and vncertaine, and therefore let the past­board [Page 72] be no heauier then you must needes; and for the size of sixe inches Diameter of your past-board, and a needle of that length. I know that a needle of halfe an ounce waight, and halfe a quarterne at the vttermost (if a good workman haue it in hand) will be very fully sufficient, of what forme soeuer.

The capitell ought to be lattin, and hammer hard­ned, well and truely boared, not too shallow, but of a good conuenient depth and widenesse at the bot­tome, fitting the pinne it standeth vpon at the top. The pinne ought to be either of lattin, or copper, and not of iron or steele, as some vse; for they are very subiect to rust: and the steele, especially by long vse, will weare a little hole in the top of the capitell, and by that meanes the Compasse becommeth dull, and they hardly (if euer) will find the reason of it; for the hole will bee passing small, and entring an exceeding little way in, and yet disturbeth all. Moreouer, in any wise there must bee alway an especiall diligent care had of fitnesse betweene the capitell and the pinne. Oteerwise, all things else appertaining vnto the com­passe are nothing worth. This pinne must bee very firmely fixed in the iust center of the boxe, and the bottome marked, that whensoeuer you take it off to sharpen the pin (which vse will make blunt) you may set him in the same place againe.

As I haue sayd that in a Magnet it selfe, the vertue is in the whole body, and sheweth it selfe most for­cible in his poles; euen so likewise our Compasse­needle, being a Magneticall body, sheweth his force in his ends, which are his poles, although that force doth proceede out of the whole body of the Needle. [Page 73] Which now I thought good to make apparant by an euident demonstration: I caused my workeman to make a needle of a Loop fashion, 8. inches long, or ouall forme in all respects fitted to be set vnto a flie, sauing that there was but one inch or a little more at each end of steele, all the intermediate part between the two ends, being of brasse: These two ends I did touch with the North and South ends of a very good Magnet: And whereas in a true Magneticall Needle, I should haue had but two points, the one North and the other South, this Mongrell yeel­ded me six, the two ends adioyning vnto the brasse of contrary natures vnto the sharpe points, & would no more doe the office of a Magneticall needle then a woodden sticke, because the vertue was not in the whole, and so communicated vnto the two ends, but each end was a totall of himselfe, being separated, and (as it were) diuorced, the one from all commu­nity with the other by that intermediate brasse: the which being taken away, and the two forkes ioyned together for that length, presently they became one perfect true Magneticall Needle, and the vertue of those foure confused points, which ere while was was lost in the forkes, will presently bee found in the two sharpe ends, and now his naturall seats: [Page 74] Both these ends of steele were fastened vnto the brasse, and then that nee­dle had no Magneticall motion; but being taken off, and ioyned together, they presently (with­out any further touching of them) became a true Magneticall Needle.

To conclude this chapter of the Compasse-needle, The needle that is still working vpon his pinne conti­nually will keepe his force better, then that which is otherwise layd vp, although there bee no doubt of the other, for a mans whole age, or longer, if it be of good mettall, and kept from open aire and rust, and from too neere vicinity of iron, but especially of any [Page 75] Loadstone. No better keeping from rust, then by var­nishing him, although it be but with a drop or two of Linseed oyle alone; the needle that is continually vpon his pinne, is still strengthened by the Magneti­call power of the earth, setting himselfe alwayes to­wards the Poles thereof (which the other cannot doe) and needeth onely to haue his pinne sharpned now and then: The which of all the faults incident vnto the Compasse, is most easily and safely amen­ded. And yet, if it bee not very well looked vnto, it disturbeth all the operation of the Compasse more then any other. And diuers wrong themselues in be­ing too busie in often touching of their Compasses, the fault being in this which no touching can a­mend.

CHAP. XI. A Sayling Compasse fitted for obseruing at Sea the varia­tion, amplitude of either sunne or starres, capes or trendings, &c.

I Haue thought good to conclude this short Trea­tise of Magneticall aduertisements, with a little additament vnto the ordinary sayling Compasse, fit­ting him thereby to bee answerable vnto the title heere prefixed, as also with a comparison of the se­uerall vses, of the Horizontall and inclinatory nee­dles: Let the glasse of the inner boxe of the Com­passe bee of good thicknesse and strength (but yet [Page 76] cleere) and euen, those that come from Venice for looking glasses before the foile be set on are the best, if a man may haue them large enough. Let this glasse be very well fitted vnto the boxe, and simmond vn­derneath vpon the shouldring that beareth vp the glasse, with a mixture of waxe, turpentine, sallet oile and rosin mingled together: or with any other sim­mon as you shall thinke good, aboue vpon the glasse let there be a ring of thin pastboard, of the bredth of the shouldring vnderneath, in like manner simmo­ned on: then must you haue a circle of lattin about the bredth of the pastboard ring, of conuenient thick nesse for strength: which must bee diuided into de­grees: This circle must haue a plate of latten, of halfe an inch broad or broader, according vnto the largenesse of the circle for strength, that must crosse ouer the middest of the circle, cut out of the same place with the circle, or else so adered with siluer so a­der: this must haue a line all along the middest of it, and a little loope at each end cut through the two ends of the loopes being precisely in that line. Last of all, you must haue a moueable ruler with two long folding sights, of about the length of the Semi­diameter of the circle in bredth about halfe an inch: the one of them must haue a slit through the length thereof, of about a quarter of an inch broad, as you shall thinke conuenient, and two little holes, the one in the top, and the orher in the bottome, iust in the middle of it, to fasten a string, hauing a very little bead to slide vp and downe vpon it. And this sight must be of the thicker stuffe then the other. For o­therwise, because of that which is cut out, it would [Page 77] be ouerpaised by the other, and so the boxe would swarue towards the other; and the sights must each of them haue a little notch in the middest of the top of them: this ruler must be fastened (but yet so that he may turne about) in the middle of the crosse plate most precisely in the center of the circle, his ends cut, that he may shew the Fiduciall line in the diuisions of the circle, the other sight needeth to bee but a a plaine plate, hauing a line in the middle, from the top to the bottome. The description followeth, be­ing the very same in substance with that, which in the Nauigators Supply, I call the Compasse of variati­on; although all things easier performed with this, then with that,

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CHAP. XII. A comparison of the seuerall vses of the Horizontall and inclinatory Magneticall Needles.

THe Horizontall and inclinatory motions of Magneticall needles are both of them but one [Page 81] and the selfe same effect of the Magnet or Loadstone, the making of the Horizontall or Diall-needle, is a­mong our artificers very well known and triuiall, on­ly they are to be put in minde that they doe alwaies make them of pure steele and not of iron. But as for the making of the inclinatory needles, it is a very curious peece of worke: It must be of pure steele, and in his right temper, the needle and his axis must bee at right angles the one with the other, and must bee so hanged on the two ends of his axis that hee bee very pliant for his motion, and that (before he haue his touch) he bee so equally ballanced, that the one end be not one iot heauier then the other, for if it be, all the rest is in vaine.

When you will vse the inclinatory instrument, thus you must doe, hanging him by his little ring, turne him about vntill hee make his least declination (or inclination) vnder the Horizon of the instru­ment: for then is hee iust in his Magneticall Meridi­an, and there sheweth his due poynt, the which o­therwise he can neuer do. But here I must admonish you of two very great errors published in the con­triuing of this noble instrument. The one is, that he would haue a little box with an Horizontall Needle fastened vnto the bottome of the inclinatory instru­ment: for to direct the instrument vnto the Magne­ticall Meridian: and by his picture of the Instrument, the distance should be but a little more then an inch, where it is impossible but that the one needle must needes disturbe the other, so that neither of them can shew aright, yea, although they were six inches a­sunder, and more, where the little box will giue little [Page 82] direction for that purpose? and besides that, it is al­together vnnecessary, because the instrument will finde the Magneticall Meridian, by the least decli­nation of the needle (as is shewed before) vnder the Horizon, without the helpe of any other. The other error is this, that he would haue that end of the nee­dle prepared to hang towards the North, to bee fra­med somewhat higher then the other, as is vsuall in Horizontall needles: what workman soeuer obser­ueth this direction, I will assure him, that hee shall lose his labour, and assoone hee may wash a Blacke­moore white, as to make such a needle serue that turne. The reason is, because it is onely the magne­ticall vertue that worketh this effect, the which ouer­waight, in either end of the needle (in this motion) doth vtterly ouerthrow.

For Horizontall needles in our Northerne Cli­mates, it is necessary: but for inclinatory needles, it is vtterly vntrue in all Climates of the whole world wheresoeuer. The motion of the Horizontall nee­dle, is naturally stronger then the inclinatory for two causes, The one is because his motion is onely side­waies, the which is easier for the Magneticall moti­on to worke in, then that which is vp and downe, and that there is no difference which way you place the boxe wherein he standeth, so that it bee paralell vnto the Horizon; whereas the inclinatory motion is in a verticall circle vp and downe, and must stand onely in his Magneticall Meridian to performe his office. The other cause is because of the diuersity of their placing in their boxes: for the Horizontal nee­dle standeth more fitter for his motion, being placed [Page 83] with his capitell vpon the poynt of his sharpe pinne, than the inclinatory can doe, being placed vpon the two ends of his axis, although neuer so neere the poynts: But yet he will doe very well, if he be rightly fitted: And for Nauigation vnder either Pole (if there be any passage that way) it is the onely Instru­ment of the world. For where the Horizontall nee­dle (or compasse) faileth, he is strongest, for the nee­rer the Pole, the stronger he is in his Motion, contra­riwise, it is with the Horizontall needle or compasse, for he is strongest at the Aequinoctial, and of no force vnder the Pole.

The reason whereof is this, vnder the Aequinoctiall the Horizontall needle standeth paralell vnto the Axis of the earth, and is equally strengthened for his motion with the two poles of the earth: but vnder the poles, hee standeth crosse-wise, at right angles with the Axis, his center representing the very pole of the earth it selfe; so that the Aequinoctiall, and the Horizon being there all one, if the needle should haue any Horizontall motion there, it must needes be an East or West motion paralell vnto the Aequi­noctiall, directly contrary vnto nature, and to all Mag­neticall doctrine.

Yet at the pole, the inclinatory needle is in his cheefest strength, framing himselfe to bee in the same direct line with the Axis of the earth it selfe: so that the vicinity of the neerest pole of the earth, hol­deth his conuenient end of the needle most strongly, being nothing at all hindered by the aduerse pole, to affect the vpper (or other) end of the needle. The which in all other scituations either more or lesse it [Page 84] doth, and especially vnder the Aequinoctiall, where each pole affecting his conuenient end of the incli­natory needle, it must stand very goglingly and vn­steddily for that motion: although most strongly for the Horizontall, if you place him accordingly.

Where hence it followeth, that neere the Aequi­noctiall large compasses, and small inclinatories are fittest; and neere the poles large inclinatories, and small compasses are best, for looke vnto what motion the Magneticall force is weakest, the smaller instru­ments ought for to be applied.

And moreouer, for as much as the Magneticall re­uolution of the inclinatory needle, about the globe of the earth maketh his motion for the difference of euery alteration of Latitude neere vnto the Aequino­ctiall, farre more large & easier to be discerned, then it can be neere the poles, therefore a lesse Instrument will serue the turne there: And because that neere the pole, his motion for differences of Latitudes are ex­ceeding small, and hard to be discerned. Therefore very large instruments inclinatory are there to bee v­sed, especially because the Magneticall strength of the needle for that motion, is there so strong and steddy, that it maketh som recompence for the slow­uesse of his moouing. And therefore I suppose that three in Diameter, will serue neere the Aequinoctiall, and fifteene neere the Pole.

And because this great one may be the lesse cum­bersome, you may cut off the circle at forty and fiue degrees of each side of the Zenith and Nadir of the Instruments, and yet leaue the needle scope enough, for all Latitudes between sixty Degrees and the Pole: [Page 85] and for the the steddy standing of the inclinatory in­strument at the sea, you may doe thus: about the middle of the instrument (or rather somwhat aboue the middle) let there be two round pins of brasse, a­bout three quarters of an inch long, issue out; and in a box of a sayling Compasse, the inner circle being taken away, make of each side two halfe round not­ches in the outer circle, there place the Instrument vpon those two pins, the which must haue towards their ends, littles circles cut in, that they slip not out of their rings that they are placed in: then will this Instrument stand as steddy, euen at sea, as the sayling compasse will doe: for the motion of the inner circle is performed by the turning of those two pins in their notches, and the outer circle is common vnto them both, alwaies remembring that you hang some pret­ty waight in the bottome of the instrument, to make his motion more certaine: If the shaddowing of the box hinder your sight from discerning the point, that the needle standeth at, it is soon holpen with the light of a little waxe candle put downe vnto it: and yet this you ought to vnderstand as aforesayd, that the Horizontal and inclinatory motions are but one and the selfe same effect of the touch of the Loadstone, and one and the selfe same needle will very well per­forme both motions, namely, the inclinatory nee­dle, not the Horizontall, because his placing vpon the pinne maketh him very vnfit for the inclining motion. But the inclinatory needle resting with one poynt of his Axis (the poynts of his Axis being very sharpe) in his little hole, his boxe being placed para­lell vnto the Horizon, will performe the Horizontall motion very well. For being placed with the sharp [Page 86] point of his axis in that hole, it is all one in effect, as the Horizontal is with his capitel on the sharp point of his pin, but that the one is vpward and the other downward, & yet either of them being as fit for that motion, as the other. Vpon the consideration here­of, my workman of Winchester minding to present Prince Henry with a rare Instrument, contriued an Aequinoctiall Diall & an Inclinatory Instrument both in one, and one needle to serue very well both those turnes. Heerein now appeareth the wonderfull wis­dome of our God, in limitting his times and seasons for the reuealing of these wonderfull properties for the vse of men, in this poore stone; namely that aboue 2000. yeeres after that it was knowen and wondred at in the world, for lifting vp of iron (for it was an antiquity in Platoes time) the vse of the Horizontall needle was known, in common vse, scant 200. yeeres agone; and very few yeeres since (yea scant as yet) the inclinatory is in any common vse: and who is there that can behold and consider both these vses, viz. both to shew the quarters of the world (as East, West, North and South, &c.) and also the Latitude of the place: to know both these in any place of the world, bee the heauens neuer so much ouercast with clowds, who is he, I say, that can beholde these two admirable and precious vses performed, euen with the turning of an hand, the which neither the Gre­cian Philosophers, nor the fine-witted Romans, nor the Persian Magi, nor the Indian Gymnosophists could finde out with all their skill and cunning, but he must needs say with that Kingly Prophet, O Lord, our Lord, how great is thy name through all the Earth, who hast set thy glory aboue the Heauens?