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
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
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 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 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 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 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 The second way Thread a common sowing needle and touch the point of it with the North end of any loadstone then offer it vnto that stone whose points you would find out holding the needle by the thread about an inch there-from and in turning the stone about you shall presently see the needle point vnto the North end of this stone and flie from the other end when by your turning it commeth neere The contrary effect ensueth if you touch the point of the Needle with the other end of the stone wherein you may behold that ancient conceiued and of late yeeres maintained errour of the contrarietie of Magnes and Theamedes to be nothing else but a contrarie property of one and the selfe same Magnes The third way Breake off the point of a sowing needle halfe an inch long or longer if the stone be good but not aboue a quarter of an inch if it be a base stone lay it vpon the stone and moue it to and fro vpon the Superficies thereof being smooth with the needles point forwards and as it commeth neere any of the two points of force it will raise it selfe more and more but being brought vnto the point it selfe it will stand there straight vpright If the stone be ragged this cannot well be practised otherwise of all other it is the most certaine way Now
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 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. 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. 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 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 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 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 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 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 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 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
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 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 Compasse-needle 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 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 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 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 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
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
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
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 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 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 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 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 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 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
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
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 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 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 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 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 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
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
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
and finding diuers good secrets I pray proceede with double capping your Loadstone you speake of I shall bee glad to see you as you write as any man I will haue any leisure if it were a moneth to conferre with you you haue shewed mee more and brought more light than any man hath done Sir I will commend you to my L. of Effingham there is heere a wise learned man a Secretary of Venice he came sent by that State and was honourably receiued by her Maiesty he brought me a lattin letter from a Gentle-man of Venice that is very well learned whose name is Iohannes Franciscus Sagredus he is a great Magneticall man and writeth that hee hath conserred with diuers learned men of Venice and with the Readers of Padua and reporteth wonderfull liking of my booke you shall haue a coppy of he letter Sir I purpose to adioyne an appeudix of tx or eight sheets of paper tu my booke after a while I am in hand with it of some new inuentions and I would haue some of your experiments in your name and inuention put into it if you please that you may be knowen for an augmenter of that act So for this time in haste I take my leaue the xiiijth of February Your very louing friend W. Cilbert Faults escaped IN the Preface speaking of Claudianus serediticall for sideriticall fol. 12. lin 22. reciprocated for riciprocally fol. 50. lin 21. hangings for hugenes fol. 53. lin 16. as may be for as many be fol. 57. lin 10. but this is not for this is not fol. 68. lin 19. supposeth the fly for supporteth the fly fol 79. lin 11. set the same for set the Sunne item lin 27. the difference is then for the difference is ten fol. 82. lin 8. higher for heuier fol. 84. lin 26. three in Diameter for three inches in Diameter fol. 85. lin 10. littles circles for little circles The last line saue one of D. Gilberts letter act for arte A BREIFE DISCOVERY OF THE IDLE ANIMADVERSIONS OF MARKE RIDLEY Doctor in PHISICKE vpon a Treatise entituled Magneticall Aduertisements moueat Cornicula risum Furtiuis nudata coloribus LONDON Printed by Edward Griffin for Timothy Barlow at the signe of Time in Paules Church-yard 1618. TO THE RIGHT NOBLE AND WORthy minded industrious Gentlemen and others who are any way addicted vnto MAGNETICALL Knowledge SO it is that for a long time I haue bin greatly delighted in the contemplation of the properties and vertues of this admirable creature of God which we call the Magnet or Loadstone And as my leisure and occasions haue serued by conference from time to time with the skilfullest Nauigators of our age by reading all the Treatises as came vnto my knowledge of such as had written thereof and therewithall trying by practise the truth of those things which I doubted of and lastly finding some things by my owne experience of good importance by others not at all mentioned The chiefe of these which I iudged profitable for common vse I did set forth in a small Treatise intituled Magneticall Aduertisements And although of mine owne louing affection towards such as yee are I haue bin alwaies ready to further you in these knowledges the best I could yet I doe assure you faithfully that diuers of good iudgment learning and eminent place vnto whom I communicated my experiments very vehemently vrged my publishing of them A copie of this Treatise being by stealth written out of my Manuscript by one that vnderstood it not and by that meanes committed diuers errors this Doctor Ridley deuoured some of them and by his endeuouring to square my propositions according to his owne conceipts and so superciliously to controll and censure the things which he vnderstood not he hath missed of the truth very farre and wide and hath herein wronged both himselfe and mee and his readers but most of all his beleeuers and yet such is his kinde disposition that he hath purloyned out of the scambled copie of my Treatise for to adorne his owne Treatise of Magneticall bodies and Motions all these that follow as in his Treatise Fol. 7. The hilly knobbes and angulous parts c. for 17 lines Fol. 8. The greater stones c. 5 lines Fol. 9. Steele and yron c. 4 lines Fol. 10. The 14. 17. 18. 19. figures are mine Fol. 18. 19. The 1. 2. 3. 7. waies are mine the 4. Doctor Gilberts Fol. 22. Euery part and peece of a Loadstone c. 7 lines Fol. 27. If a wyer be touched c. 5 lines Fol. 30. 31. It is to be obserued in the fashion of a Magnet c. 16 lines Fol. 36. For although that naturally c. 9 lines Fol. 51. 52. Also if a Magnet be fastened c. 4 lines This practise is profitable for Trauellers c. 14 lines moe Fol. 63. 64. The best way to touch c. 11 lines And some haue thought it better c. 14 lines Fol. 66. Set two Loadstones c. 3 lines Fol. 71. An Adamant doth loose much of his vertue c. 3 lines Fol. 72. That 20. Chapter onely a few words chopped and changed is whole mine Fol. 83. And for this cause the Adamant c. 3 lines Fol. 89. A peece of Steele well tempered c. 2 lines The two next are his owne and very absurd Fol. 90. Now it is to be obserued c. 10 lines Fol. 95. The needles and compasses c. 14. lines So that it cannot but seeme to any indifferent person very strange that Doctor Ridley would publikely so traduce mee and that by name and so contemptuously in his friuolous Animaduersions and could neuer hit vpon my name no not so much as once to acknowledge it in all these things which he hath by stealth learned of mee and inserted into his Magneticall Motions for his owne the which with their consequents if you withdraw from his Treatise you will leaue his motions very dull For except this Ridley had ploughed with my Heifor hee had not knowne my Riddle Sic vos non vobis In my aduertisements indeed I made mention that some body had in this manner dealt euilly with mee and I reproued certaine faults that some body had committed especially in the fundamentall Magneticall heare-sayes of misnaming of the true North and South in Magnets and Magneticall bodies and in making the Inclinatory needle with the one end heauier than the other and some others But these two especially for because they doe draw on many others as they doe both in his Booke and wheresoeuer they shall be admitted they will increase like a snow-ball waxing still greater as they goe and all his dawbing of them with his vntempered morter in his silly Animaduersions do amend the matter nothing at all but make it farre worse than before For the common good I might not let them passe vnreproued and yet I would not publikely name him but vsed this word somebody The like himselfe hath viz. Some say some