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 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 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 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 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
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 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 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 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 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 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 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
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 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 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 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 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
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 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 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 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 selfe-conceit but vpon good reason and firme demonstration auoucheth and prooueth the contrarie and clearely sheweth that the former vulgar assertion 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
cheifest points of this most necessary skill and the vse of them in this short Treatise Not meaning to translate Doctor Gilberts booke but to take those thing out of it which I shall thinke fit for this purpose which are onely the Magnetisme of the whole earth and some of the consequents thereof and to adde the rest of mine own industry Wherin I may be bold after asort to challenge a right as hauing endeuoured to get some insight in this argument a matter well knowne to diuers aboue the space of twenty yeares ere Doctor Gilberts book saw light And in very deed I communicated many of my obseruations with him aboue one whole yeare before he put it out in print To be short of all that I shall set downe in this Treatise my request is that the Reader will admit nothing but that which shall be confirmed by good reason or vndoubted experiments And I purpose God willing to tye my selfe as strictly vnto this rule as euer any man did that hath written of the like argument making it euen a matter of conscienae to deliuer any thing herein for certaintie that my selfe shall not know to be sound And so by this meanes shall I neither abuse the Reader with any vntrue assertion nor iniurie so certaine and so excellent a knowledge with any doubtfull or vnapproueable conclusions Contents of this Treatise CHAP. I. OF the Magneticall power of the whole Globe of the Earth CHAP. II. Of the ambiguitie of the North and Sooth ends of Magnets and Magneticall bodies explained and Doctor Gilbert therein defended CHAP. III. Certaine generall obseruations of the nature and properties of the Loadstone CHAP. IIII. By what meanes the chiefest points of any Magnet of what forme soeuer may easily be found out CHAP. V. The manner of Capping both with single and double Capps and the nature of them CHAP. VI. Of cementing and peicing of Loadstones CHAP. VII Of the variation of the Magneticall Needle with the Appurtenances therto belonging CHAP. VIII A discouery of Errors committed in the making and touching Magneticall Needes and Wiars of sayling Compasses with an aduise for the true and right making and touching of them CHAP. IX Of the touching with a Loadstone capped and without the Cappe CHAP. X. Of the fashioning of the Compasse Needle CHAP. XI A Sayling Compasse fitted for obseruing at Sea the variation amplitude of either Sunne or Starres Capes or trendings c. CHAP. XII A comparison of the seuerall vses of the Horizontall and Inclinatory Magneticall Needles A true copie of one of D. Gilberts letters written to the Author concerning his Magneticall Experiments MAGNETICALL Aduertisements 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 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 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 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
whether it be your North or South end the effect will soone declare The fourth way Hauing an ordinarie Diall with a magneticall needle or a sayling compasse or any magneticall needle standing on a sharpe pinne hold neere thereunto the stone turning it in your hand then will the north end of the needle I meane the end that pointeth to the North respect the true North point of the stone The fift way Also if you touch a common sowing needle the longer the better and put ti through a little peice of corke not bigger then may well beare it vp so that by the meanes thereof it may swimme in a bason of water the same if you offer the stone vnto it will shew the like effect And here it is to be remembred that none other way whatsoeuer will more readily or truely define the magneticall Meridian then this of the needle with corcke in the water And therefore as it is very requisite for many purposes that euery Traueller either by land or especially by sea should alwaies haue if he may an aequinoctiall Diall with him so would I not wish that any of them should be without some sowing needles touched with a good stone which wil both serue the proper vses of sowing without impairing their touch for it is open aire and rust that are the greatest enemies thereof And at any time with a peice of corcke or a drie sticke in the water will shew the magneticall meridian a matter though meane and triuiall in shew yet betweene whiles of so great importance that it may serue to saue very many mens liues A sixth way Also if you prepare a little round Loadstone of a quarter of an inch diameter or there about but it must be a very good one hauing his two poles marked and fitted in such manner that it easily turne about in a little frame according vnto this picture The like also in his sort will come to passe if you hang a small declinatorie Needle in a frame in this manner Then by mouing it in his frame all ouer the stone the North pole of this will finde the South of the other And likewise will the South the North of the great one For it is not in outward shew between one magnet and another as it is betweene a magnet and a magneticall needle the contrarie ends of the magnet will couet in their motion to meete together but the end of the needle which turneth North will come vnto the North of the stone For in very truth it is the South point of the needle euen as the magnet it selfe being placed in a woodden dish in water will turne with his North end vnto the South and with his South end dish and all towards the North as it is largely declared in the second Chapter of this booke The like effect will also follow if you hang as aforesaid a small magnet in the middle by a small silke thread that it may freely turne without impediment according vnto his owne nature But this property it will shew quicker or slower according vnto the goodnesse of the substance and fitnesse of the forme The best forme for this purpose is the extended ovall hauing his poles precisely in his ends If his poles be some pretty distance the one end towards the East of the stone and the other asmuch towards the West this stone in his length will not point vnto the magneticall North and South as otherwise he would but vnto some other point of the Horizon yea following this experiment in this sort you may make him stand vnto any point of the Compasse onely you ought to abridge the stone in his length that he may come somewhat neerer vnto a circuler forme that so his diameter of North and South being through the magnetisme of the earth the cause of this motion may be so much the longer in comparison of the Masse of the stone and consequently more effectuall After the like manner you may so touch the wiers of a Compasse that the Flower de luce of the flie shall stand vnto what point of the Horizon you please although the Diameter of the wiers doe still remaine fixed vnder the Flower de luce and the South point of the Carde Finally to conclude this point with a magneticall delight if you touch two sowing needles in a contrary sort that is the point of the one northerly and of the other Southerly and set them with their corckes the one at the one side of a bason of water and the other at the other you shall see them as quickned with vitall spirit euen so to moue the one end towards the other at the first faire and softly but when they draw neere they will rush together as it were with a kinde of violence the point of the one striking precisely at the point of the other you must place the needle whose point is touched for the North on the South side of of the bason and the other on the other side Otherwise the heads and not the points will runne together a thing farre more worthy of admiration then all the selfe moouers of any Daedalus or Architas Tarentinus and more strange to behold then the connexion of Iron rings combined by vertue magneticall whereat S. Augustine so much and that iustly did wonder 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 Now therefore in this position both ends of the Magnet being applied vnto the two ends of the iron 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
which is that which we call variation but yet the vastenesse of the Ocean doth not hinder the declination 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 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 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 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 and will giue his direction for a new respectiue Meridian and new respectiue Poles And in such
labour to cleare some thinke c. in his booke meaning mee being not contented onely to vsurpe that which was properly mine for his owne as aforesaid but also hee tooke vpon him although very ignorantly to confute some of mine vnder these termes and this onely out of a stolne Manuscript Whereas all men know that Manu-scripts ought to be vncontrould vntill the Author hath published them who may alter and change things in the meane space as he thinketh good He stileth himselfe principall Phisition vnto the Emperor of Russia the which many men wonder at being so yong as he than was and supposed that he went ouer only as Phisition vnto our Merchants there that he should in so short a time become that Emperors principall Phisition If he were he sped better then Bomelius did who is said to haue died there in that cold climat of the extreamest hot kinde of Calenture Out of all question somewhat it is more then ordinarie that maketh him of so hauty a spirit so to braue the world with such prodigious assertions of his Magneticals in and aboue the Moone the earths Magneticall circular Motions and his paltry abusing of the holy scriptures to support his lunaticke fictions vnder the name of Magneticall Philosophie There are yet two texts of Scripture which it is a wonder how they escaped him the one is in Iosuah 10. ver 12. and the other is in Esay 38. ver 8. In the one That the Sunne and the Moone stood still the space of a whole day The other that the shadow in Achas diall went backe 10 degrees and the Sunne in the skie returned 10 degrees by the which he was descended For it is his guise to make contrary conclusions vnto that which the Scriptures affirme and therefore blame him not if he doe so despise Aristotle who neuer taught any such Logicke Now therefore that yee may in few words vnderstand the vntruth of the earths Magneticall Motion that is so mainely emblazoned by him and the weaknes of my Animaduersors Magneticall skill you must know that the Magneticall Motion is a naturall inclination of two Magnets or Magneticall bodies that may freely moue respecting the one the other within the Orbe of their forces with their convenient ends that is to say the North end of the one alwaies respecting the South of the other If the two Magnets or Magneticall bodies be of like quantitie forme and goodnes their Motions will be of like quicknes of the one towards the other but if they differ in any of these their Motions will be so much the slower Now forasmuch as all Magneticall motions are alwaies respectiue of the one Magnet or Magneticall bodie towards another it followeth by necessarie consequent that no Magnet or Magneticall body can either moue or be moued of it selfe but is vtterly voide of all intrinsecall or selfe-Motion the true and onely cause of his Motion being euermore without it selfe And therfore mine Animaduersors selfe-motion of the Globe of the earth circularly by Magneticall vigour in the which hee doth so gallantly triumph is but an idle figment and a meere Chimaera but his definition of Magneticall bodies is very sutable vnto it viz. very monstrous namely That wee define to be a Magneticall body which doth remaine and place it selfe in one place or kinde of situation naturall not alterable as all starres doe and the great Regent globes of Saturne Mars Iupiter the Sunne and the Earth doe or such as with respect and attendance follow other globes as the two starres which support Saturne the foure attendants vpon Iupiter lately discouered by the truncke-spectacle the two trauersers about the Sunne called Venus and Mercury and the Moone which doth follow or goe about the earth and respecteth the same alwayes with one Pole and therefore hath a peculiar Magneticall vertue that guideth her in this kinde of situation Auditum admissi risum teneatis amici Any man that considereth this goodly definition being the foundation and ground of his Magneticall discourse and the very first sentence of his booke and many the like fancies in his Motions and and Animaduesions will easily discerne what his Magneticall skill is and what a vanity it were for me to spend any precious time to confute in particular such vnreasonable and senselesse opinions which haue more neede of Helleborus to purge them out of his head then Arguments to confute them in his booke And in his friuolous animaduersions seeking to maintaine his former errours and he being so snappish to haue them amended hee maketh them ten times worse then they were before and far more palpable But my tetricall Animaduersor must be ruled by reason and affoord all those his patience that do beleeue the holy Scriptures which flatly doe denie the Earths motion and affirme the motion of the Sunne Moone Stars in the whole current thereof as Psal. 19. 6. 104. 5. Iosua 10. 12. 13. 14. Esay 38. 8. c. Also that hee will giue men leaue to credit their senses in matters subiect vnto sense and not repugnant vnto reason and that he will not be offended with those who do pitifully laugh at his Magneticall Astronomy with those topsituruy motions like Voluitur lxion se sequiturque fugitque For although some great learned men in those Sciences haue vsed the supposed motion of the earth for an Hypothesis seruing their ready calculations as they haue done also their supposed Epicycles for the motions of the Planets and their courses yet that is no reason for to auouch them for to be in themselues true and reall things according vnto some mens vaine fancies who doe argue after this sort It is an easier matter and more as they say agreeable vnto nature for so small a body as the globe of the Earth is in comparison of the heauens to mooue circularly in the space of foure and twenty houres then it is for the huge Vniuerse so to doe and that which is done with lesse hazard is to bee preferred before the like which may not bee performed without feare of a greater danger with diuers other reasons like vnto these But although such as these are may goe current in a mechanicall Trades-man shop yet they are very insufficient to bee allowed for good by men of learning and Christians by profession who know right well that it is great folly for to oppose that which we call difficult vnto an omnipotent power Who stretcheth out the heauens like a curtaine and spreadeth them out as a tent to dwell in Esay 40. ve 22. He stretcheth out the North ouer the empty and hangeth the earth vpon nothing c. Iob 26. ver 7. And that which we call Nature it being nothing else but Gods ordinance there can bee nothing contrary but all things agreeable vnto nature which God hath ordained But God hath ordained the motion of the Sunne Moone and Stars as aforesayd and the vnmooueablenesse of the earth therfore this is more easie and more