A SHORT TREATISE of Magneticall Bodies and Motions By J Parke â—â—dâ—ey Dr in phisicke and Philosoph◠〈◊〉 Physition to the Emperour of Russia and one of the eight principals or Elects of the Colledge of Physitions in London LONDON Printed by Nicholis Okes. 1613. A Preface Magneticall PVrposing to deliuer a briefe and easie doctrine as concerning this new Art of Magneticall Bodies and Motions I thought good here to free the same from the lustre and glosse of disputable points and other conceits onely purposing to handle nothing in the same but the plaine matter and demonstrations Magneticall themselues thinking it more fitting to place these flowers in the Preface if any delight rather in them then in the matter it selfe to the end they may in some sort be prouided of both As concerning the first finding out of the Magnet-stone whereof I am to treate Plinie and Nicander haue fained that a certaine Heardman being in the fields hauing his shoes shod with iron and his staffe armed with an iron pike and resting himselfe vpon a quantity of this stone could not easily remoue his feete or lift vp his staffe whereupon he perceiued the attractiue vertue of this stone that it did attract and hold iron Other thinke that the pioners and diggers of mettals by their diligence and obseruances first found out the Load-stone and his vertue of attracting iron by which property it was well knowne to the auntient Egyptians and Graetians in times past Some haue thought that the Magnet would leese this quality attractiue if he were annointed with garlicke or touched with a Diamond and of this opinion were Ptolomie Plutarcke Plinie and Baptista Porta for this mallady Ruelius hath found a remedy to annoint the Load-stone with Goates bloud and Paracelsus with his oyle of Crocus Martis will not onely cure him of this euill but can make him ten times stronger then he was before likewise Cardanus and Alexander Amphrodiseus haue laboured to nourisâ— the Magnet with fitings of iron and steele Many haue striued much to inquire out the cause how the Magnet should attract iron vnto it Epicurus Aphrodiseus Carus Iohannes Costaeus Plutarke and Thomas Aquinas do suppose this attractiue vertue to proceed from certaine motes vnsensible parts or vapors issuing forth of the Magnet and entring into the iron by conuenient figures and in their retiring backe againe do attract the iron to the Load-stone Plato and Fernelius haue thought the cause of this attraction to be Diuine and from aboue Thales and Anaxagoras say that the Magnet hath life in it whereby it attracteth the like substance as liuing things do Some thinke that there is a certaine sympathie betweene the Magnet and iron as betweene the male and female as Orpheus and Lucretius haue sung Auaroes Scaliger and Cardinall Cusanus would haue iron to moue vnto the Magnet as to his beginning and matrixe from whence he came Gulielmus Puteanus Galen and others do iudge that by his substantiall forme he draweth iron vnto it but Doctor Gilbert whose labours are the greatest and best in Magneticall Philosophie doth conceiue that the Magnet and iron do moue one vnto the other not by any specificall forme but from the essentiall forme of the Magneticall globe of the earth being an essentiall part of the same which is not so as it shall be demonstrated in the last Chapter of this Treatise To illustrate this vertue of attraction in the Loadstone Serapio and the Moores like farre trauellers haue reported that in the Indies there be mighty craggie rockes all of Magnet-stone that will stay the ships as they saile by them and pull the iron nailes out of them this story Olaus Magnus also confirmeth to be so in the North and that there least the rockes of Load-stone should pull the iron workes and nailes from the vessels and boates they build them with wodden pins and sowe the boords together with lines of the barkes of trees which indeed they do both for want of our skill in building ships and barges and for want of iron workes whereof they haue little store And because this stone hath vertue to attract therefore Marbodeus a French-man Petrus Bairus Pictorius and Arnoldus de villa noua do faine that this stone will procure the loue of Princes and of women and maintaine loue betweene husband and wife Haly-abbas will haue the Load-stone to cure the goute if it be held in the hand and the East Indians say that it preserueth youth Caelius Calcaginus saith that if the Magnet be preserued in the salt of the sea-Lampron or Remora that is thought to stay a ship vnder saile that then the Magnet will draw vp gold that is fallen into the deepest well And Fracastorius testifieth that he hath seene a Magnet that would draw siluer vnto it and chase iron from it Cardanus Antonius de Fantis Petrus Perigrinus and Iohn Taisner do deliuer that there might be made a perpetuall motion by the vertue of the Load-stone but by the experience of many ingenious practises I find it vnpossible to be done Since the finding out of the Sea-compasse which was about 300 yeares ago by one Thomas Goa borne neere Naples or by Marcus Paulus Venetus who learned that skill in China as is thought and first brought it into Italy there haue growne many opinions how this Compasse should be directed into the North and South Marcilius Ficinus Paracelsus and Cardan thinke that the vertue of the constellation of the Beare doth gouerne the Magnet and iron and therefore both these are directed into the North. Petrus Peregrinus Frier Bacon Iohn Taisner and many other would haue the Compasse to obserue the North pole But since that Sebastianus Cabotta did find out that the Compasse did vary from the true meridian it hath bene imagined that there is some place in the heauens that the Compasse should respect as Cardan would haue it to obserue the starre in the taile of Vrsa major Bessardus a Frenchman saith that it doth behold the pole of the Zodiacke Martin Cortesius would haue an attractiue point aboue the heauens and Robert Norman an Englishman denieth that there is an attractiue point but affirmeth that there is a respectiue point to the which the Compasse doth moue especially the Inclinatory-needle whereof he was the first inuent or Liuius Sanulus supposeth that there is a certaine Magneticall meridian and Francis Maurolicus that there is a Magneticall Iland and Fracastorius holdeth that there be certaine Magneticall mountaines which be set out in Plancius his Card that the Compasse doth respect But Doctor Gilbert our friend and Collegiat hath discouered these errors and set forth the causes of the variation of the Compasse in his booke De Magnete Yet lately Gulielmus Nautonerius a Frenchman and Anthony Linton an Englishman haue supposed that the Magneticall-needle and Compasse do moue and turne themselues vpon the Magneticall meridian alwayes vnto their owne Magneticall poles placed vpon the superficies of the earth that
South or North may be termed by that part which it respecteth some haue laboured much to cleare If you chance to find out the rocke where the Loadstone doth grow where you purpose to take out a part of the same marke your part with notes for the North and South then cut out your peece out of the rocke and put it into a bole to swimme on the water and your markes will be turned to a contrary situation to that they had in the rocke and the North note will be turned South and the South North and so would the rocke of the great Magnet it selfe if it were so placed make the like alteration in his situation by the generall conformation and direction of the mighty Magnet the globe of the Earth Therefore the reason why that the Loadstone in the boat vpon the water turneth bendeth and seateth it selfe to a contrary situation to that he receiued and had primarily whilest he was in the bowels of the Earth and vnited with the body of the great Magnet is because that euery peece and part of a Load-stone being seperated from the whole whereof he was a part is now become a perfect complete and sole Magneticall body and is as it were a little earth of it selfe hauing all the proprieties Magneticall that the great Earth hath as his two poles meridians aequator and such like and therefore according vnto the nature of Magneticall vnion hereafter spoken of in the XXII chapter will in no wise indure and cannot be suffered to match and seate it selfe as he did before but thinketh it more naturall and a thing of more perfection and conueniency to turne his aspect a contrary way to that he had primarily at his first making and endowement with Magneticall vertue This alteration of polity is to be obserued likewise in Magneticall needles and long peeces of iron that be touched and animated and adhere to that part of the Load-stone which seateth it selfe North which being at liberty and seperated from the Loadstone will turne that part and end that was touched at the North pole and seate it alwayes in the South and it shall be sufficient for vse to know and marke with a note which is the North-pole of your Magnet and which is the South-pole There is another vertue in the Poles of the Loadstone and that is that the South-pole turned downeward will take vp more then the North-pole will and the North pole will erect a greater waight thâ—n the South part or pole will as some say Tab. III. Fig. 2. a b. But I haue alwayes obserued that the Pole of the Magnet that seateth it selfe North is alwayes the most vigorous and strong Pole to all intents and purposes vnlesse he lacke the quantity and like substance the South part hath These Poles which be in the great Magnet of the globe of the Earth haue a maruelous strong Magneticall power imparted vnto them that they cannot be turned either higher or lower or moued to the right hand or to the left but hold the Earth continually in a true and certaine position and place and would if any force or power should moue their great strength awry from the true syte and meridian latitude returne to their right syte and place againe and this is the true vertue of the Poles of globes which the Sunne and Iupiter haue as well as the Earth These Poles be most certaine and sure markes for all Magneticall bodies conueniently caried to direct themselues vnto Tab. III. Fig. 9. as appeareth by our Compasses which in all places of the world turne their Lilly into the North whereby the Marriner knoweth what course to take And the Magneticall Pole Poles of the world both articke antarticke are all one and not diuerse as some haue imagined which haue lost both their oyle and their paines and this is true by the demonstrations and motions of the Inclinatory-needle although there be many momentary causes of variation These Poles hold the Earth certainely in her polar position while she turneth her selfe about to receiue the Sun-beames and influences of the starres and planets for the generation and maintenance of all inferior bodies vpon her in her proceeding out of her Lastly these Poles of the Earth in certaine great number of yeares haue naturally a little inclination in the polar circles of the Zodiacke for the receiuing and moderation of the beames lights and influences of the starres whereby the progressions and anticipations of the aequinoctiall and the mutations of the greatest declination of the Sunne are perfectly vnderstood to preuent the faining of many Spheres aboue the starres as the ninth tenth and eleuenth and their impossible motions In fashioning the Loadstone it is conuenient to make flat or roundish the ends of the Magnet where the Poles are the better to cap and arme them with iron or steele to lift vp their conuenient waights Tab. III. Fig. 2. 12. and as the most are Tab. I. At the Pole the Inclinatory-needle doth not incline obliquely to the axis Tab. III. Fig. 6. as the needle c c to a b the axis as in other places but aspecteth the Pole directly and perpendicularly as Tab. III. Fig. 1. the needle c respecteth the axis b a directly maketh one line with it Also at the North-pole that point of the directory-needle and compas that did behold the South of himselfe being applied to the North-pole doth turne as some thinke but this is true only at the aequator in the spaces between the aequator the 34 degree as is demonstrated in the XII chap. not at the Pole it selfe and the places neere adioyning for at the North-pole if the Magnet be truely placed that point that pointeth towards the South doth point to the South directly and in the places neere adioyning doth it obliquely A wier touched Magnetically hath two Poles as Tab. III. Fig. 5. the one end a is North and b of the nature of the South CHAP. VII Of the Axis THe Axis or axeltree of the Magnet is a line that passeth from the one Pole to the other by the center of the body of the Loadstone and after this order there is an Axis vnderstood to be in the Earth Tab. III. Fig. 1. 2. 3. 9. 10. In fashioning of Magnets if a peece be taken away paralell from the Axis then in these two Loadstones the Axis with his poles will be remoued into the middest of the stone as Tab. III. Fig 3. a b the Axis in either peece is in the middest of the stone so whether that bunches be taken away from the Loadstone or any cauities filled the Axis will alwayes be placed in the middest of the most vigorous bulke of the Load-stone as a b in euery figure It is said in the latter end of the V. chapter that if a Loadstone be sawen in two parts from one pole to the other vpon the Axis that the poles and Axis will be found in the
that can easily be perceiued vpon a Loadstone of good strength and vigor especially vpon his poles and he will shew a vigor as if he were as strong as the Loadstone is whereunto he is vnited but after that he is taken away he will be as weake as before vnlesse it be often done CHAP. XVII Of contributing the vertue Magneticall to Iron or Steele THe iron barres in windowes being there placed North and South do receiue a polar vertue and directory faculty in time from the vigour of the orbe of the Magneticall globe of the earth and hauing marked them with notes to know which end was South which North in the window take them out and tye a thrid about the middest of them that they may hang leuelly in the aire and the end with the South note will turne it selfe into the North and the other note will behold the South contrary to their place in the window where they were first animated Magnetically Likewise if a long peece of iron be forged North and South and laide by to coole in the same situation he will be animated and indewed with a polar vertue and moue in the aire being hung in a thrid or put in a boate on the water and turne to the contrary pole to that from which he first receiued the Magneticall vigour If a rod of iron a wier or directory-needle be ouer-heat in the fire so that they haue lost all Magneticall vigor to direct them North or South yet let them be touched with the Loadstone at one end only and they will be excited with a directory and polar vigour at both ends and the one end of the semidiamiter will be of the North and the other of the South prouince and nature and being placed according to Magneticall orders will direct their points to the North South contrary to the pole that animated them with this vertue polar Also take rods of iron wiers and Magneticall needles that haue neuer bin touched with the Load-stone and rub them vpon the poles caps or teeth of the Loadstone at the ends and they will be much refreshed vigorated and animated with the polar and directory vertue at both ends both of the North and South-poles as though they had a new life of quicknesse infused into them and these shall refresh other needles that shall be touched with them and apprehend and draw them away like captiues and will not let them loose from them vnlesse by force you seuer them The best way to touch incite and giue the polar directory and Magneticall vigour and faculty vnto needles Marriners compasses is to rub them from the middest of the needle where the aequator of their axis is vnto their points vpon the pole cap or tooth of the Loadstone drawing them thus from their middle to the ends vpon the cap pole or paralell neere the same vnto the axis or at right angles to it thē after draw the other end vpon the other pole cap or tooth diuerse times as afore and these needles wiers and plates for compasses shall be perfectly touched and vigorated In long Loadstones that haue the poles in the ends if a wier be drawne paralell to the axis from the poles end to the aequator it will be incited with that pole It is doubted whether the touch and polar vertue wil be giuen as wel from a paralell some distance from the pole as from the pole it selfe it is plaine that from those paralels and parts neere adioyning to the pole the greatest vigour of politie Magneticall doth proceed yet in paralels neerer the aequator it will be giuē likewise the vertue directory will be very sufficient If you touch the needle amongst the paralels it is the best way to rub the needles alongst the meridians towards the pole rather then to rub the crosse the meridians in a paralell manner yet this way will giue the polar and Magneticall vertue also Some haue thought it better to touch compasses and Magneticall needles rather on the Loadstone then vpon their caps thinking that the vigor and faculty Magneticall will continue longest that is giuen from the bare Magnet stone the truth is to be obserued in time Yet the cap and tooth giueth and imparteth a stronger vigour to the needles then the bare stone doth because the vertue of the Loadstone is increased as much by the armor and cap as if his bulke simply were tripled Needles and wiers of steele heated to an height and reduced backe to a blewish colour will receiue a stronger touch and retaine it ten times longer then iron will howsoeuer he be hardned yet iron is best for caps placed neere the stone That end of the needle whether directory or inclinatory which is to be touched ought to be somewhat lighter then the other especially for the North and most vigorous touch end of the stone because that the touching will sway downe a little and the needle hath two motions one of direction the other of inclination and then the needles and compasses will play more leuell and aequidistant to the horizon for the sayd vses When any Magneticall needle or wier is touched from the North-pole or tooth of the Adamant that end of the needle will respect the North-pole of the Magnet but being seuered out of the orbe of the Adamant it will be directed into the South by the Magneticall vertue of the earth But if a round globe or ring of iron be touched with the North-pole of the stone the place touched will haue the vertue of the South-pole the North-pole will be in the opposit part and being seuered from the Magnet it will not turne to the contrary part as it falleth out in long Magneticall needles compasses as before If a ring of iron be touched the correspondent pole will be in the opposite part but if this ring be cut asunder and made a straight wier then both ends will haue the vigor of one pole onely Excite a directory needle at both ends from one pole and they will both be of one nature and looke what point was last touched and that will turne as if he onely were touched and direct more surely with lesse wauering too and fro then the other touchings will spoken of before Let a long peece of clay newly burnt coole North and South and it will receiue power Magneticall from the earth Set two Loadstones with their poles of one denomination at the ends of a peece of clay whilest it cooleth and both ends will be of one nature If a long wier be touched in the middest by the Loadstone and passed through a corke and set for to swim in the water it will wauer vp and downe vncertainely as though it were not touched but if it chance to rest it selfe towards the pole in time it will be indewed with his vertue Set a peece of iron vpon a Loadstone as you did a weake Magnet in the end of the former chapter and
but if a third Needle be brought neere vnto them as Tab. XI Fig. 8. then one of those Needles that did adhere that had his pole of the same nature with the pole of the needle that doth approach doth cast about for to offer his other end of the contrary quality vnto it and thus the first two Needles will aspect this third with their points of one denomination But this discord is not found betweene the Adamant and the Magneticall Needles that bee excited and animated from one of his poles for as long as the Needles bee within the view and orbe of the Adamants Magneticall orbe so long they will behold and aspect him with a certaine dutifull conformity application and respect vnto his axis as it hath beene demonstrated in Globous Angulous Magnets but being seuered out of the Adamantine Orbe of the Loadstone then they will flie as from a foe from that pole from whence they receiued their life and vigour Magneticall and by the vertue of the earth conforme themselues to the contrary pole Contrariwise take a large Globe or Ring of Iron and touch them with the North-pole of the stone and the animated place will haue the vertue of the South-pole and adhere to the North-pole of the Magnet and being seuered will keepe the same situation in the water contrary to all Needles that turne the touched part to the contrary pole as afore Set two short and slender wyars vpon the pole of a Magnet Tab. XI Fig. 3. and they will adhere at the lower end vnto the same but whereas they should erect their other ends perpendicularly those ends of the wyers will decline a great distance asunder vnlesse by force they be vnited and ioyned together Contrariwise it will fall out if these two short wyers bee fastened to two seuerall thirds with wyer and hanged ouer the pole then neither of their ends will behold the pole but for the hatred that the one beareth to the other they beare off asunder in a great distance desiring rather that their vpper ends farthest from the Loadstone should vnite then that they should doe it Hold a knife to the Needle of a Dyall that is touched Magnetically and the one point of the Needle will come to it and follow it and if that the knife bee offered to the other end of the Needle it will flie away from the knife so one end of any wyer though vntouched will attract the Needle at one of the ends and driue the other end away Hereof more hath bene written in the sixth Chapter Some thinke that this quality of the poles thus to flie off the one from the other that it is no enmity but proceedeth from a disponent vertue to cause these Magneticall bodies to moue and turne away to the end that they may better frame and dispose themselues to a conuenient and naturall vnition CHAP. XXII Of Magneticall Vnion MAgneticall union is when one Magneticall body naturally conformeth it selfe to vnite vnto any other Magneticall body by conuenient angles positions that is the South-pole of the one Magnet will apply and vnite vnto the North-pole of the other as may be seene in Loadstones carried in their boates vpon the water and in Magneticall Needles and Wyers of Steele and Iron If two Magnets or two Needles do vnite at conuenient points a third Magnet or Directory Needle will first separate one of them till hee turne his contrary part at the which hee will vnite with the third as Tab. XI Fig. 1. 8. There is a strong vnion of body to body and a weak the strong coniunction is three manner of waies The first is commonly obserued to bee at the Poles where one body Magneticall is conioyned and vnited vnto the other in a right line vpon the axis at the pole Tab. XI Fig. 10. The second strong vnion falleth out when the superficies where the pole is placed is made plaine where at the edges Magneticall bodies adhere at right angles vnto the axis as Tab. III. Fig. â—â— and Ta. VII Fi. 2. but more plainely this strong vnion appeareth when as the Adamant shall be capped with two teeth at either pole descending at right angles vnto the axis for here a tooth will lift vp as much perpendiculerly at right angles to the axis as it will at the pole in a right line Table XI Figure 10. 11. The third strong vnion and strongest is when at a Meridian in the Loadstone there is a superficies made flat and plaine paralell vnto the axis where the coition according to the conformity in the aequator inclining neither to one pole nor to the other is most strong for whereas wyers and weights at the pole hang and adhere vnto it but by one end onely heere they will adhere alongst their axis leaping more violently to adhere with their whole side and vnite then they will from their endes vnto the poles as Tab. III. Fig. 4. therefore the Adamant being armed artificially with two teeth at right angles vnto the axis will in this paralel-conformity vnto the axis apprehend and lift vp weights heauier by many times then the caps at the poles will Tab. XI Fig. 12. because these receiue their vigour from the forces sent out of both Prouinces of the Magnet The weaker vnition of Magneticall bodies together is in the other parts of the Meridians where the conformity and applications of their bodies is oblique to the axis though that neere the pole the oblique coition is stronger then it is by the aequator Notwistanding there is an oblique coition as strong as the strongest vnion and will take vp as great weights as the paralell vnition to the axis doth and this is as it were a paralell coition also betweene the teeth and the head of the weight yet oblique to the axis of the body of the Magnet as Tab. XI Fig. 13. hauing his supplies of strength from all the Magneticall body of the stone Vnition also is either naturall halfe violent or else depraued the naturall coition is when the vnion and conioyning of Magneticall bodies is by the contrary parts as in Adamants by the poles North to South and in needles by head and taile as Tab. XI Fig. 7. Tab. XII Fig. 5. 6. 9. so two wyers swimming on their corkes in the water being touched by contrary poles will march and hasten to salute one the other like two louers Tab. VI. Fig. 5. Likewise in Adamants that be armed with two teeth it falleth out that they will embrace the one the other onely with the teeth and parts that be of contrary prouinces and not with those of like nature and prouince Tab. III. Fig. 12. Tab. XII Figure 10. Tab XII Now that vnition which Magneticall needles touched and excited at the pole of the Adamant haue may bee thought to bee halfe violent and some-what strange Tab. III. Fig. 1. 6. 7. Tab. IIII. Fig. 1. because that heere there is an affinity of two Magneticall
make right angles with these two poles of one nature as Tab. VIII Fig. 1. Now take away one of these stones and after turne the North-pole A towards the needles that behold the South-pole B of the other stone and they will all of them situate themselues equidistant-wise and at right angles to the aequators of both stones as Table VIII Fig. 2. Tab VIII Moreouer take other two Magnets that are long with the poles in the ends like that Tab. VII Fig. 2. and lay it before you and place three needles before it two at the end one in the midst against the aequator which will apply paralell to the axis of the stone and those two at the ends will seate themselues at right angles to the axis as before then set the other long Magnet that hath his poles in the ends with the North pole A against the North-pole A of the first stone Tab. VIII Fig. 3. and all the three needles will apply themselues in a straight line paralell to the axis somewhat like the order of the first type yet contrariwise Now take away this second stone with the poles in the ends turne it and place the South end B against the North end A as Tab. VIII Fig. 4. and then the 3 needles will stand at right angles to the axis and paralell one vnto another and to the aequator This is to be obserued in these applications that the neerer the second Loadstone is placed to the needles in aspect with the first Magnet the better will they shape out these figures of applications in the approching they will vary by little and little from their first situation vntill the vertue of the two Loadstones be equall in their orbe It may be imagined that these applications for the most part should be found naturally vpon the earth in trauelling or nauigating betweene two great Ilands or high Magneticall continents but the first fourth figure of this eighth Table cannot be found naturally in any place Tab. VIII Fig. 1. and Fig. 4. There is also much variety of variation in one needle neere two Magnets or a Magnet and Magneticall body as place a needle on a little foote vpon the Terrella Semiterrella or Loadstone and it will direct it selfe rightly vpon the meridian of the stone as hath bene proued before Tab. III. Fig. 9. but if you hold a little peece of iron toward the point of the needle the point will flie from the iron and deflect from his meridian a little Yet let this peece of iron touch the Load-stone and be vnited vnto it and put it towards the needle a farre off and the needle will turne from his meridian and decline and vary towards it the contrary is to be sayd if this iron be put towards the taile of the needle Now take two long Magnets that haue their poles in the end and place a needle before the aequator of one of them and it will apply paralell to the axis then bring the other Loadstone and place the end where the pole is against the aequator of the first Loadstone as Ta. VIII Fig. 5. and then the needle will vary his position and seate it selfe at right angles to the axis of both Magnets So also take two Loadstones and let one of them haue the poles in the middest and the other in the ends and you shall behold much artificiall variety of the application of one needle vnto them Place a needle before the middest of the Loadstone that hath his poles in the middest and it will behold the pole after lay downe the other Magnet that hath his poles in the ends and set his aequator against the needle and it will vary his position and stand paralell to the aequator of the former Magnet whose pole he beheld before as Table VIII Fig. 6. Tab. IX Set a needle against the end of the Load-stone that hath his poles in the ends and it will rest it selfe at right angles to the axis then apply the second Magnet to the needle that hath his poles in the middest Tab. IX Fig. 2. and the situation of the needle will be altered to be paralell to the axis he beheld at right angles at first Place at the corner of that stone that hath the pole B in the middest a needle and it will apply obliquely then lay the end of the other Loadstone that hath the pole A in the end and the needle will apply at right angles to the axis of both the stones as it is Table IX Figure 3. But set a needle afore the end of the stone that hath his pole B in the middest and set the end of the other Magnet that hath in the end the pole B of the same denomination as Tab. X. Fi. 1. and the needle will apply as is to be seene in the type in a straight line to the last and paralell to the axis of the first Also apply the aequator of this second stone that hath the poles in the endes vnto the needle placed as afore vnto the first stone Table X. Figure 2. and the needle will be paralell to both axis let the needle stand against the corner of the first stone obliquely and apply the end of the second stone with the pole in it Tab. X. Fig. 3. and the needle will apply as in the Tab. IX Fig. 3. Tab X CHAP. XVI Of preseruing the vertue of Magnets HAuing treated of the parts of the Magneticall bodies of their motions and applications now we will speake of his other naturall vertues and properties Some haue thought it very conuenient to keepe the Loadstones in filings of steele and iron to preserue their vertue and vigor thinking that the Magnet is fed or at least very much refreshed with them because they will cleaue so fast to the sides neere the pole But I do not allow this way so good to preserue them rather I like the keeping of them in a bag or cloute of woollin-cloth close from the iniury of the heate and cold of the weather or in a case or boxe fit for them and it is very necessary to wipe them often from dust and grease and to haue a care that they do not rust Also it is very commodious and naturall for them that they be layde vp and placed according to that naturall situation the which they would affect and respect if they were caried in a place and fashion free from renitency and resistance in the aire or water therefore they would be laide vp or hung accordingly as their poles and pointes do particularly respect to the North and South which will comfort them exceedingly Besides if the Loadstone be sometimes polished it will strengthen and releeue the body of the Magnet very much If a weake Magnet be rubbed at one of his poles with a stronger Loadstone he will be bettered by it in his vigor and vertue if not augmented therein Set a Magnet of no force or strength
it wil haue a great force but take it away from the stone and almost all the vigor will be departed CHAP. XVIII Of augmenting the vertue of the Magnet THere is a meanes found out whereby the Load-stones that will take and lift vp a very small waight may by being armed with a corselet and teeth be enabled to take vp more ounces with his armor then he could being naked and vnarmed lift vp scruples and graines The first way is by fashioning caps of iron or steele to either pole as hath bene described Tab. I. in the second Chapter whereby the Magnet will lift vp a great weight of Iron at one end perpendicularly to the axis and after if you turne the other end to the weight it will by his force lift vp the same weight also if the stone be good and of equall substance and fashion This way or arming is most vsuall for those Loadstones that be of a long ouall forme where at the poles there is fitted and placed two concaue peeces of steele which are fastned and held close to the same by three or foure long narrow plates of siluer or brasse not vnlike to that order which is vsed in tipping of cuppes with siluer that be of Ostridge-egges Indian-Nuts Mace-wood and Stone which from the bottome to the verges and edging haue siluer plates for to hold the edging and bottome together some trimme their Load-stones all ouer with siluer and guild both the siluer and the armour ioyning altogether with pretty ioynts as in a case to open and shut There is another way of capping and arming of Load-stones when they haue a side parallell to the axis made straight plaine and flat and the pole rounded or flatted in the end such as are the Semiterrella or halfe ouall forme Tab. I. Fig. 2. 4. and of many angles as in the types of the first Table all these formes may haue their armour on the ends where the poles are of such breadth as shall be comely but the larger they are the better it is and from these cappes to haue two square formes of Steele or Iron like vnto teeth a little descending lower then the bottome of the stone of bignsse and length as the bulke of the Magnet shall permit these teeth because that they do descend at right angles from the poles will iointly take vp great weights Tab. XI Fi. 12. 13. parrally to the axis of the Magnet and yet at one of the teeth Tab. XI Fig. 11. will lift vp as much as any cap doth directly and in one axis from the pole the weights for this forme ought to haue the heads of their weightes like an headlesse crosse as is described Tab. II. Fig. 2. 3. 4. Heere obserue what weight one of these teeth will eleuate â—n the aire for both teeth ioyntly lifting and holding one weight together will take vp from the ground foure times as much in weight There be some Magnets that will take vp with two teeth sixe times as much as one tooth shall and one I haue seene that will take vp twelue times as much with both teeth as hee will do with one tooth these teeth are to be fastened to the stone with plates of siluer or brasse by the skilfull workeman Such Magnets as be made plaine at both ends hauing the axis in the middest of the stone Tab. I. Fig. 5. 6. 12. may haue their armour with teeth on both sides two teeth on the one side and two on the other these will take and lift vp with like strength on both sides More-ouer the vertue of the Load-stone may be further augmented by increasing the number of teeth and shaping them so as that they may take hold with foure or fiue teeth as Tab. I. Fig. 7. and Tab. XII Fig. 11. where the poles being in the ends of the stone and haue had two teeth descending on either side now the sides be turned and these are also turned in forme of a Greeke 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 and the stone hath his force multiplied and is made to take vp with foure teeth hauing two teeth descending from either end where the poles are which two teeth are of one nature and the other two of another The other fashion for to take vp with fiue teeth as it were a hand with fiue fingers must haue the pole in the midst of the stone which being made the bottome must haue his cap for this part to haue three teeth like a Slauonian 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 as Ta. XII Fi. 12. and the other cap from the top must descend with two teeth like a Greeke 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 as in the type There is a way to cap the Loadstone so that it shall take vp with eight teeth vsing foure at one time and foure at another the stone would haue two broad sides where the poles are and the teeth would bee in forme like a Romane X. or S. Andrewes crosse the center hereof would be placed on the pole and the teeth artificially fastned If there bee two Load-stones that bee capped with their teeth descending from either end of like Diameter and length then place those teeth together that be of a contrary nature Tab. III. Fig. 12. and Tab. XII Fig. 10. and they will vnite and adheare together and if they continue thus some time the weaker will lift vp a better weight CHAP. XIX Of the decay and decreasing of the Magnets vertue THe vigour of the Load-stone is much diminished by the euill keeping of it as when it is laid in the open aire against the heat of the Sun and subiected to cold and all change of weather or laid vp as some do in a boxe with rusty fylings of steele and yron in a place neere a pan of char-cole to keepe it warme in winter There is nothing that hurteth the Load-stone more then the fire doth for if the Load-stone be burnt in the fire it will leese all his Magnetical vertue and strength the which may be a little restored by touching a good Magnet and how weake so euer he be he will be a conuenient Magneticall medium to carry the extent of the Magneticall vigour to a farther orbe Aqua fortis will eate the Load-stone and burne and mortefie him as he doth eate into Iron The Magneticall Needle being touched and excited by the Load-stone will not pursue and point out the vaines of such Iron as be very stony and full of drosse as not worthy the labour to be digged because they haue little Magneticall matter and Iron in them and if that part of the Myne of Iron be beate and stamped into powder the Magnet will take vp very little of this dust declaring the Myne to be nought vnlesse the Myne be heat Crocus Martis wil not be attracted by the Load-stone because his Magneticall vigour is cleane defaced and euaporated by the fire If a Magneticall Needle lately touched and inuigorated by the Magnet bee heated red hot in the fire
he will leese all his potency polare and directiue faculty It is also conueient to vnderstand that hauing touched and animated a Needle Magnetically if contrary to this excited the Needle be rubbed from the point to the middest vpon the pole of a Magnet cap or tooth so any long peece of Iron or Steele else as knife dagger or sword which before would haue attracted and lifted vp Magnetically other Irons of some weight by being thus rubbed backe againe from the point to the middest haue that vertue taken away which they receiued before from the Load-stone and are as void of all vertue attractiue as they were before they touched the Magnet so that they neither will adhere or lift vp the least weight which was nothing to that they would haue done being excited If two Magneticall bodies be ioyned together at their poles these two poles that touch together haue the nature of the aequator and will not then excite or hold a needle thus touching An Adamant doth loose much of his strength if hee bee diminished and haue any part of his body taken from him especially if his figure was good before Some haue thought that certaine formes of the Magnet which may be allowed for conuenient figures do lessen the Magneticall vigour chiefly in their attraction as a sphericall or plaine superficies in the poles of globes and of square and angulous figures but these full and obtuse superficies and flat formes at the poles do attract best with their cappes and lift vp most as hath bene declared in the eighteene chapter before for this vigour proceedeth from the substance of the Adamant better then in long and piked formes which haue very little substance left about the poles yet this assertion is partly true in such like formes of Iron for in this mettle the long fashion is best A round plate of Iron to the pole cap or tooth of the Magnet disperseth and diminisheth the direct extent of his vigour like-wise a long plate or square peece of Iron or Steele Tab. II. Fig. 9. 17. applied to the two teeth of the Load-stone doth deforme the figure of the body and depraue his vertue CHAP. XX. Of the Commutation of the vertue Polar THe Polar vertue is said to be changed when as the North-pole is made the South-pole and the South-pole altered into the nature of the North-pole in Magneticall bodies this thing is effected in a weake Magnet by placing him a long time by a Magnet that is stronger vnnaturally which is done by adioyning the two North-poles or the two South-poles of the two Load-stones together a long time where the strong Magnet will by his neighbour-hood take away that contrary nature of pollity that was in the weake Load-stone and will make and infuse into him that polar vertue which doth naturally vnite vnto the pole of the strong Adamant making that point and pole to be South which was North. This thing is not onely experienced in two seuerall Magnets lodging together in one chamber and boxe but also if you shall agglutinate and cement diuers Magnets of diuers strengths together they will all of them be conioyned and vnited together as if it were one stone and body and may bee made and fashioned into a conuenient figure and will be endued with one vigour Magneticall of one prouince though separated they were of diuers polities and iurisdictions Magneticall needles and long formes of iron as kniues daggers wiers and such like if at one time they be touched and excited with the North-pole and made of his nature in all operations Magneticall then another time let these North points be touched as is vsed to be done with the South-pole of the Loadstone this end now hath lost his former nature and is made of affinitie and allegeance vnto the South-pole and after if you shall bestow vpon him by touching him againe at the other pole the vertue of the North-pole againe and then he will march vnder his banner and looke by which pole he is last touched and relieued he will remaine at his seruice alwayes after and beare his badge Put clay of a long forme in the fire after let him coole North and South and it will receiue a polar vertue after burne it againe in the fire and let that end which cooled first North now coole South and it will be commutated into the nature of the South and the other North. Furthermore if a strong Loadstone be held somewhat neere such compasses and needles as haue bene excited and touched with the vertue directory from the north by the Magnet although they be in their boxes yet the other end of the Loadstone will alter their situation and the Lilly of the Compasses will be cleane turned that that part and Lilly that should alwaies turne North will either stand South or else moue vp and downe vnperfectly and weakly hauing his first polar vertue changed for another or else taken away This conclusion maketh many affraide to let two Magnets come too neere together lest the one should rob the other but this will not be effected presently in the Loadstones themselues though that it be proued soone to come to passe in the Magneticall bodies of steele and iron If a directory-needle be excited at both ends from one pole it will haue the vertue of that pole at both ends but if both ends be rubbed backe from the points to the middest on the same pole both ends will haue the nature of the contrary pole and if one end be passed from the point to the middest that end will haue the nature of the contrary pole and the other end will keepe his nature still CHAP. XXI Of the discord of the two Points of the Adamant THis Proposition is demonstrated by two Magnets swimming in their boates in a bason of water as Tab. XI Fig. 5. 6. for if by force their two North-poles or South-poles be placed together they will abhorre the one the other and part asunder by speedy flight Tab XI When two Adamants shall confort and keepe together at their contrary poles at the approching of a third Magnet they will be separated and flie asunder Tab. XI Fig. 1. because that the pole of their Adamant that is offered vnto them is of the nature of the pole of one of the two Loadstones which the stone of that denomination perceiuing flyeth away from the company of the other because two South-poles and two North-poles in diuers Magnets be at discord and war together and cannot abide to dwell as neighbours together but each of them placed out of the others Orbe will both aspect the North with their North-poles and the South with their South-poles and thus two needles excited as Tab. XI Fig. 2. will each of them out of the others Orbe haue respect to their propper pole but if the needles bee within the Orbe one of the other as Tab. XI Fig. 7. then they will moue and adhere together at their contrary poles
or of steele these formes are sooner vnited and faster tied as it were with strong ligaments and cords both vnto the Load-stone or one vnto the other Tab XII Fig. 3. therefore if sand or other matter that is not Magneticall be fastened and bound vnto a smal peece of iron or this small peece of iron be fastned to a paire of seales that haue strings to the scales though iron be the waights of the scales yet the Magnet will lift vp and hold a greater waight that is all continued iron then he will do of these mixture and intermission of Magneticall medium of diuerse and different substances not Magneticall If a Magnet be fastened to the pole of another Loadstone by his conuenient vpper pole then a greater waight then before will be apprehended by the Loadstone and taken vp because that the Load-stones vertue is increased and augmented by the addition and adioyning of the other Magnet Ta. XII Fi. 6. 9. Euen so for the same cause if a wedge of iron be placed on the vpper pole of a Load-stone the other pole that is downward will take vp a greater waight Tab. III. Fig. 2. If there be a thin plate of steele or iron held or fastened vnto the nether pole of the Adamant betweene the Loadstone and the waight then the Magnet will lift double and sometimes decuple or ten times as much againe from this practise begun and grew the arming and capping of Adamants with steele and iron after diuerse manners Tab. II. and as hath bene declared in XVIII Chapter Of the augmenting the vertue of the Load-stone by this arming of the Loadstones with steele and iron in conuenient places their vertue and potency is greatly multiplied both to vnite attract apprehend and lift vp greater waights and also to moue turne and conforme Magneticall needles a far off and the needles by hauing a strong vigour infused into them direct and retaine themselues more firmely in their conformitie and direction Magneticall If a plate or cap of iron be held to any paralell betweene the aequator and the pole crossing in any meridian there will be an apprehension and retention of iron wiers and waights much heauier then the bare vnarmed stone wil hold without this cap Ta. XII F. 7. Where the superficies of the Magnet about the pole is flatted and made plaine hauing armour applied to it and a tooth descending from the point at right angles to the axis here this tooth will take vp and lift as much as the cap at the pole will Tab. XI Fig. 10. 11. Those Adamants that be capped to take apprehend and lift vp at the pole onely if there be three of them readily prouided put the second to the nether pole of the first and he will retaine him firmely then adde the third to the nether pole of the second and the first by vertue infused into the second and the third will strongly hold them both in the aire Tab. XII Fig. 9. all of them being armed and communicating their vigors together firmely to vnite So a dagger or sword excited will lift vp one waight at the end of another and if the vpper that touched the sword or Load-stone be held an inch off yet by the vertue that is extended within the orbe Magneticall the waights will cleaue together still Set a short and small wier at the pole of a Magnet and it will be erected set another on this and it also will be caried vpright set on the third and all three will be apprehended and borne vp Tab. XII Fig. 7. Also set a short wier on the pole and another on a meridian not farre off the pole or set them vpon two seuerall meridians vpon a strong Magnet then lay another short wier on their heads they will hold and carry it and this also will carry another wier vpon his backe Tab. XII Fig. 8. There be certaine formes of Magnets as the Semiterrella in fashion of an halfe boule the long ouall made plaine at the bottome the long square formes described Tab. II. all these may be armed and capped with two teeth at right or oblique angles to the axis which being thus prepared will apprehend great waights and retaine them most firmely in the aire Tab. XI 12. 13. If two Magnets armed with two teeth apeece be set before vs the one being strong the other weake or much lesse whose axis or diamiter betweene the teeth is equall of like length then set the teeth of these together that come from contrary poles and parts and the stronger will apprehend and lift vp the weaker and the weaker being vnited and incorporated with the stronger by the vertue that he receiueth frō the stronger will lift vp from the ground and retaine the stronger and greater very firmely although he be much heuier then the waight the small stone doth ordinarily lift vp Tab. III. Fig. 12. Tab. XII Fig. 10. Let a Magnet be armed with two teeth descending and two ascending as Tab. I. Fig. 5. 6. the vpper teeth will cleaue fast to a great waight of iron and hold by the same firmely apply a waight to the nether two teeth and all will be retained and held together most firmely by paralell vertue of the meridians from the axis Such Magnets as be armed to one superficies with foure or fiue teeth or more Tab. XII Fig. 11. 12. must needs apprehend more and greater waights retaine and lift them vp most easily A peece of steele well tempered being excited will lift vp a greater waight then the like forme and bulke of iron will also this tempered mettall in a kinde of forme might be capped like a Magnet It hath bene proued that the apprehension is better betweene the bare stone and iron as also the armed Adamant with the armed Adamant is most strongly retained and farre more firmely then the retention of one Loadstone is with another small and bare stone Now it is to be obserued that steele by reason of his drinesse 〈…〉 his vigor Magneticall bestowed vpon him better then the iron doth that is softer which entertaineth the vertue Magneticall sooner and retaineth it the lesse time where his substance is lesse extensible and glutinous so steele being very often excocted and euaporated in the fire becometh very brittle and will not receiue the Magneticall vigour yet being reduced from that hardnesse and easily tempered not to be ouer hard will retaine the vigour Magneticall better then iron Those Adamants are the best which are bare and naked without their furniture and armor to take vp their owne waights or more at one of their points and poles and retaine the same firmely Such Adamants will cleaue vnto a peece of iron by their meridian and hang vnto it and will retaine a great iron waight also adhering to the meridian paralell to the Axis CHAP. XXV Of Magneticall direction from the earth HItherto I haue discoursed of the Magnet and other Magneticall bodies parts motions applications
be neere and within the circles polar not varying at all from their owne meridian but deuidte only and decline from the meridians of the pole of the world and with this conceit these two with many curious calculations and proiects will presently find the longitude of all Cities and Countries but this their strong imagination hath failed them being grounded vpon obseruations from the variations of the needle from which these two men haue set forth different Magneticall poles and if they should worke from 500 obseruations they might gesse at neere halfe as many varietie of poles for variations are not regular but irregular because their scattered causes be irregular so that these men haue found insteed of the longitude of places a longitude of vnprofitable labors Therefore not purposing to dazell any ones conceit with the repetition and confutation of any opinions termes of Art or words whatsoeuer I will come to the Tractate it selfe thinking that the quiuering Magneticall-needle will be trouble inough to handle for the better knowledge and delight in Magneticall experiments M. R. A TABLE OF ALL THE CHAPTERS contained in this Treatise CHAPTER I. OF Bodies Magnetical CHAP. II. Of the Magnet-stone his forme and caps CHAP. III. Of Iron CHAP. IV. Of the Earth CHAP. V. Of the two poles and how those points are found out CHAP. VI. Of the vertue of the poles CHAP. VII Of the Axis CHAP. VIII Of the aequator CHAP. IX Of the meridians CHAP. X. Of the Paralels CHAP. XI Of the HorizoÌ„ CHAP. XII Of the 2 circles that the needle maketh about the Magnet CHAP. XIII Of noe circle the needle maketh round about the Magnet CHAP. XIIII Of the distance and orbe of the Magnets vertue CHA. XV. Of applicatioÌ„s CHAP. XVI Of preseruing the vertue of the Magnets CHAP. XVII Of contributing the vertue Magnetical to iron or steele CHAP. XVIII Of augmenting the vertue of the Magnet CHAP. XIX Of the decay and decreasing of the Magnets vertue CHAP. XX. Of the coÌ„mutatioÌ„ of the vertue Polar CHAP. XXI Of the discord of the two points of the Adamant CHAP. XXII Of the Magneticall vnion CHAP. XXIII Of attraction Magneticall CHAP. XXIIII Of the strong apprehension of the Magnet CHAP. XXV Of Magnetical direction from the earth CHAP. XXVI Of the variation of the Compas from the true meridian CHAP. XXVII Of finding the variatioÌ„ of the coÌ„pas by 1 obseruation CHAP. XXVIII Of finding the variatioÌ„ of the Compas by the circles of the Astrolobe CHA. XXIX Of finding the variation of the Analemma CHAP. XXX Of finding the variation of the Compasse by an Equinoctiall Dyall CHAP. XXXI Of finding the variation of the Compasse by rings CHAP. XXXII Of finding the variation of the Compasse by an Horizontall Dyall CHAP. XXXIII Of finding the variatioÌ„ in degrees minutes by the doctrine of Triangles CHAP. XXXIIII Of the Application of the Inclinatory-needle to the Axis of the earth CHA. XXXV Of the Inclinatory-ring needle CHAP. XXXVI A Diagram of the needles inclination to the axis of the earth and horizon in any latitude CHAP. XXXVII Another Diagram of finding the angles of the Inclinatory-needle in any paralell CHAP. XXXVIII Of finding by the needles inclinatioÌ„ vnto the horizoÌ„ the altitude of the pole by an instrument CAAP. XXXIX Of finding the needles inclinatioÌ„ in euery latitude by table CHAP. XL. Of finding the angles of inclinatioÌ„ the Magnetical meridian the Azimuth together CHAP. XLI Of the variatioÌ„ of the Inclinatory-needle CHAP. XLII Of finding the variation of the Inclinatory-needle CHAP. XLIII Of finding the longitude CHAP. XLIIII Of the matter of the Magneticall globe of the earth by the needle MARCVS RIDLEVS CANTABRIGIENSIS IMPERATORIS RVSSIAE ARCHIATRVS Eta â—4 〈◊〉 1594. Misâ—us ab Elisa Ruthenâ—s qumque per annos Anglis 〈◊〉 desis tâ—Vocat 〈◊〉 domum Tuâ—e mathematicis clarus magnetica calles Pâ—oâ—ias laudes doctus Vbi que capis To the Courteous Reader COurteous Reader I haue written thee a small Discourse as concerning Magneticall Bodies and Motions the which I hope will not be obscure vnto thee through his breuitie because of his plaine method and easie demonstrations which with their pleasantnesse will proue very ready and apparant vnto thee especially being animated from the Magnet stone it selfe as from a most liuely and perfect teacher Therefore I would aduise thee that when thou readest this booke that thou wouldest prouide thy selfe of such like formes of Magnets as I haue described in the first Table and figures of the second chapter as also of needles wiers and waights of iron and steele set forth in the second Table of the third chapter of this booke which thou mayest haue made and prouided for thee by the helpe of some skilfull workemen when thou shalt be furnished with these kinds of prouisions then thou mayest reade and practise the operations and demonstrations of this booke which will be both easie and very pleasant vnto thee and though that there be many precepts and practises in this Booke which be not for example sake set downe in tables and figures vnto thy sight because I desired to be very briefe yet if thou shalt not be altogether vnskilfull in these demonstrations that be delineated in the Tables of this booke and their often practise thou wilt be able inough to vnderstand and put them in vre with these forenamed prouisions But if thou shalt desire besides thy instruction in this kind of learning to put in vse and make benefit of these matters Magneticall either in trauelling or sailing vpon the Magneticall globe of the earth then it will be very necessary for thee to be stored with the Marriners Compasse for the sea perfectly drawne and framed to know the way and of what hand and point to saile and trauell and also to haue the Inclinatory-needle truly placed in his ring and a Directory-needle or a little flie Magneticall in the boxe fastened at the bottome in his conuenient distance for to know vnder what latitude thou art euery day of thy voyage Likewise if I should declare vnto thee how beneficiall the Directory-Magneticall-needle is for the description of Ports Hauens Forlands Capes Bayes and Riuers for the more perfect making of Sea-cards how necessary for the positure of buildings directing of dials and all Mathematicall instruments for measuring and surueying for pioners and vnderminers of forts for searchers of minerals mettals sea-coles and other subterestriall bodies I should be too tedious vnto thee and will rather referre thee for these matters to that which is set downe by others because I meddle here in this booke onely with those things that be Magneticall In this place I thinke good to aduertise thee as concerning the magnitude of the seuen Planets with their respect vnto the earth out of Ticho Brabe described in the top of the Title Page that whereas their proportion cannot be set forth truly in any types being at too great oddes therefore I haue deciphered that in
8. The foure angles Tab. I. Fig. 10. and of many other fashions as Tab. I. Fig. 9. 11. 12. which may be described all which being flatted or rounded at their poles Tab. I. a b hauing their caps with one or two teeth will take vp by them both or seuerally and are good to touch needles wiers kniues daggers and such like long formes to giue them vertue to take vp smaller wiers sowing-needles and such like small waights or to giue the vertue polar You may cap and arme some kinde of formes of Magnets with foure teeth two teeth from the side flatted at either pole as we haue described Tab. I. Fig. 7. which hath foure square iron teeth like a foure footed stoole to raise vp waights with foure teeth together If you had a Magnet stone of a flat forme that had his poles in the center of the stone as these I haue described haue their poles in the ends then you might place one side with his pole downeward and the other side vpward and prouide you a cap for the vppermost side like a Greeke 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 and a cap for the nethermost side like a Slauonian 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 and these being artificially and discussiuely fastened to this Loadstone would take vp waights with fiue teeth as it were an hand with fiue fingers I haue drawne a line a b in all these formes paralell to the axis of the Loadstone to the end that the caps of iron crossing the poles and axis a b at right angles may be the better perceiued Neuerthelesse in fashioning of some Load-stones the axis cannot so aptly be alwayes placed in the midst of the ends of the Load-stones being flatted vnlesse there be a greater part of the Load stone taken away the bulke very much deminished which will lessen much the strength of the stone for the greater that the bulke is the more is the strength of the Magnet Therefore I haue set downe a type in the last place Tab. I. Fig. 12. where the diamiter a b lieth awry and the poles be situated higher and lower at the ends and yet the Loadstone shall take vp as much in waight as if his diamiter lay not obliquely The hilly knobs and angulous parts of the Loadstone may be sawen away with sand or emer◠without any hurt to the vertue of the stone and sometimes many ounces may be cut away without any losse of Magneticall vigor especially if any substances of other nature be intermingled and agglutinated to the Magnet which may be knowne by their colour and hardnesse very easily Also if there be any cauities and hollow places or broken parts of the Loadstone that do diminish his vertue or disfigure his forme this may be supplied mended and filled either with a peece of another Loadstone or with a cement of the powder of the Loadstone and the filings of steele or of iron brayed and grinded very small vpon a painters stone mixed with rozen and waxe melted and coloured to the colour of the Magnet that is mended putting into this cement more or lesse of the filings according to the strength of the Loadstone Some with this cement and such like glutinous matter make diuerse formes of Magneticall bodies artificiall It is very conuenient for makers of sea-compasses and maisters of ships to haue a Magnet well capped that taketh vp at one end halfe a pound waight at lest for it is not wholly necessary that the same should be of the best vigour and strongest rocke for all Loadstones both of great and lesse vigour haue the same facultie Magneticall to all intents and purposes The greater stones of the same rocke haue a larger vertue then the lesse and euery part and small peeces of Magnet stones haue euery one of them the same vertue and vigour Magneticall the great ones haue sauing that they be more weake and not alwayes proportionable in strength vnto them CHAP. III. Of Jron IRon is a mettall decocted out of the Loadstone or out of a mine of that kind The best iron-mine and Loadstone is all one thing and body Magneticall for it being placed artificially either in the aire or vpon the water moueth North and South attracteth other iron vnto it and performeth the same conclusions that the Magnet stone doth This mettall is heauie and of a blewish blacke colour after that it is tried from the drosse and is made of certaine iuces and vapours in the conuenient bowels of the earth by a specificall vertue working him Besides the mine this mettall is excocted out of diuerse stones sands earths and clayes of diuerse colors which haue much Iron like matter in them If some clay 〈◊〉 burnt in the fire being of a long forme cooling North and South after being hung on 〈…〉 in the aire or put into a dish in the water it will turne and moue it selfe too and froe till it rest North and South and some clay being burnt will shew a little iron vpon his sides that was melted out of him so that this Magneticall substance of iron is not very scant to be found for in all countries and regions there is great store of this mettall being the principall matter of the externall barke of the globe of the earth Steele and iron are the best Magneticall materials for Magneticall vses because by the Smithes skill they will be extended and fashioned into diuerse formes fit for the practise and vse of Magneticall demonstrations Of this mettall are made caps for Loadstones of diuerse formes with teeth to take hold of and lift vp great and small fashions of waights of iron and diuerse other Magneticall needles and formes Tab II It is good to haue long plates of iron reasonable thicke Tab. II. Fig. 7. round plates of iron Tab. II. Fi. 9. and round rings of iron of diuerse weights and bignes Figure 8. It is conuenient to haue diuerse directory Magneticall needles great and small Tab. II. Fig. 10. 11. for dyals and instruments and needles for Compasses Tab. II. Fig. 12. 13. to fasten to the Cardes or to take off at pleasure we vse short wiers fastened to thrids and a little Loadstone in a thrid to take vp a waight Also it is necessary to haue Inclinatory-needles Tab. II. Fig. 16. to put into his ring and a short one with a Lute-string in the middest Tab. II. Fig. 17. or else put in a frame of brasse or siluer as Tab. II. Fig. 18. to find the pole of the Loadstone and to demonstrate his oblique inclination to the Loadstone as he is caried about him or else to haue a little round Loadstone put into a frame with an axletree hauing his poles marked Fig. 19. which applied about the Loadstone turneth and conucrteth it selfe diuersly also it is fit to haue a short and thicke needle Tab. II. Fig. 20. into the end of it there is to be put a wier of filuer brasse or of a peece of a Whale-bone for vses hereafter
bodies of the same nature and denomination and not of the contrary that it seemeth that the Magneticall nature betweene the Adamant and the Iron is both very different from all other Magneticall bodies and some-what imperiall for it is not to be seene either in Magnets one towards the other though they be of the same rocke and peece or in any wyers of yron or steele of one towards the other or in the earth it selfe with those that she doth Magnetically animate that that pole which is excited or animated with a pole of the same nature should respect and conforme it selfe being artificially without renitency carried vnto a pole of the same nature and denomination from whence he receiued his first vigour Here therefore no doubt the Adamant is Masculine vnto his beloued the Iron and Steele and these are Femenine as more apt to obey respect and follow the Masculine subiect to be attracted by him whose presence quickeneth reuiueth and animateth them in all kind of vigor and commutation Thirdly when yron is vntouched and vnexcited the coition is the weaker but when a small peece of Iron shall be in a boate with materials of other lading to be vnited to a Magnet in his vessell heere the coition is depraued and weake because the Magnet affecteth and draweth his owne beloued best when she is not laden or mixed with materials that be of different nature not Magneticall and for this cause the Adamant will take vp a greater weight all of Iron or steele then when a great weight of other subance is fashioned to a small weight of iron or steele The greatnesse of the bulke of the Adamant helpeth vnition so doth the length of the axis and vertue disponent to set the Magneticall bodies in conuenient situation Besides there is a vertue attractiue besides the disponent vertue and a directiue and inclinatory faculty in the Adamants that bring Magneticall bodies to vnition and apprehension the two first retaine them in vnion and coniunction proceeding especially from the goodnesse of the stone the latter two helpe the disponent vertue and are to be found in all Loadstones and in the earth it selfe CHAP. XXIII Of attraction Magneticall MAgneticall attraction is a naturall incitation and disposition conforming to contiguity and vnion of one Magneticall body vnto another and no violent haling of the weaker to the stronger being an appetite of vnity proceeding from both bodies that are separated as two Magnets floating in their boates do not at first run together as it were from center to center of the bulke vpon a violent disposition or attraction but the disponent vertue first worketh then the allicient and Adamantiue vertue in them both for vnition doth shew his vigor to ioyne them by conuenient termes the one body vnto the other Tab. XI Fig. 5. 6. Also the Adamant doth more strongly attract iron hauing a more Masculine nature to attract her and inableth her bestowing vpon the iron that he toucheth a great quantity of his strength without any losse vnto himselfe so that shee hath power to attract other iron strongly which before the excitation from the Magnet shee could not doe and therefore excited formes of iron and steele are quicklier attracted then such as are not touched because they haue more Magneticall vigour in them Such Magnets as be armed with iron attract more strongly then the bare stones doe because that hereby their vigour is increased being more strong and extendeth it selfe further as if a long iron wyer bee conioyned to the pole or tooth of a Loadstone and to the end of this lay to another and at the end of that a third and so forward the Adamant will hold them all or most of them according to his vigour and strength Tab. XII Fig. 1. all touching one the other and cleauing together as linked in a chaine Place a wyer some-what short vpon a Load-stone neere the pole or further off and hold an iron or Magneticall body towards it and the wyer will rather bee attracted away by this weaker body and leaue this strong Magnet Tab. VI. Fig. 6. and before the yron touch it it will decline and bend towards the yron that approcheth so will needles directory deflect awry being placed vpon the Magnet from their conformity to any vntouched wyer and be attracted by them and this proueth that the eminent parts of the earth being Magneticall may attract the Compasse to vary from the true Meridian of the earth The naturall attraction of Magneticall bodies is that the North-pole do attract the South-pole and the South-pole the North although betweene the Adamant and the iron there is that sociability that the North-poles loue one and the same pole CHAP. XXIIII Of the strong apprehension of Magnets THe apprehension of Magneticall bodies is a strong vnion cleauing and sticking of them together that they will hardly be seuered being strongly retained by the vertue and loue Magneticall as though they were tied glued and soudred together this coniunction and agglutination is performed by certaine conuenient positions whereof I haue spoken in the XXII chapter of vnion according hereunto if two Magnets be swimming in their boates vpon the water within the orbe and vigor Magneticall one of the other they will moue to conioyne and be grappled together like two ships and if one of the vessels be halled the other will follow Tab. XI Fig. 5. 6. A strong Magnet will hold but a very small Magnet at the poles hauing the North-pole applied to the South-pole for to lift the small Magnet in the aire but offer a wier of pollished iron or steele that is a good deale heauier then the fragment of the Magnet was and the Loadstone will lift this up from the ground and retaine it firmely Tab. XII Fig. 5. If Magnets be of one mine the biggest will lift vp and hold the greater waight for this purpose the longer forme from pole to pole is best and bulke being compared with bulke this forme will take vp the greater waight because his diamiter is longest Take a long peece of iron or steele as a knife or dagger or sword that is finely polished and touch and excite them Magnetically and these shall take vp a greater waight of iron then the Adamant it selfe so it be very good and little shall that gaue them their vigor Magneticall to lift vp and retaine firmely Table XII Fig. 2. I haue a Loadstone that will vigorate a sword to take vp and hold a pound waight Likewise Magneticall needles and excited wiers will strongly retaine and adhere one vnto the other at their conuenient poles hale one the other and lift them vp and retaine them firmely for such Magneticall formes of iron and steele as be touched and animated Magnetically are sooner apprehended held fast and lift vp in the ayre then those that be vntouched and vnexcited because that when the Magneticall vigour is infused dispersed and spread through all the parts of the iron-waights
vertues and effects as they haue one vnto the other which haue bene of that qualitie that they might be almost all of them experienced and obserued at home and in our houses handling the Load-stones as little earthes and globes and turning them about with our hands to see obserue and vnderstand all the qualities vertues and effects of the same whatsoeuer comparing these Magnets as diuerse earths and Magneticall globes together with the motions compassions and conclusions proceeding from a present perticular and vnnaturall cause and potency in the stone before our eyes And hauing before partly discouered the motions that Magnets haue with the earth being taken out of the same and bred and animated therein as also the motions of such irons as haue bene excocted out of the mines and such like veines or rather bones of the Earth that haue bene also endued and excited with the directory and Magneticall vigour from the Earth both at their first forging and forming as also by their placing vpon the ground whilest they coole and become tractable with our hands and their position in houses windowes and other places Also I haue shewed how this vertue directorie polar vigour and politie is to be giuen to compasses for the sea to directory needles that direct our moueable dials into the meridian line and to the Inclinatory-needle or any other needle or Mathematicall instrument whatsoeuer Now I am to declare how such demonstrations as haue bene learned at home out of the Terrella and Semiterrella magneticall may be put in practise and vse by such as saile to farre countries by sea or trauell by land for their great benefit both to teach them how to direct their course and to tell them in what place and climate they are in which thing they may performe and learne very perfectly hauing the directory in their compasses and the Inclinatory-needle in the meridian ring artificially made about them In comparing the two Magneticall bodies of iron and the Magnet with the earth the great and mother Magnet of all Magneticall bodies we shall see and behold that not onely in the Load-stone the Terrella and Semiterrella but principally in the great Terra and Magneticall globe of the Earth there is naturally found the two poles the North and South the aequator the meridians paralels axis and horizon whereupon all the motions and conclusions that haue bene made vpon the meridians of the sayd formes in the Magnet are proportionably and agreeably to be found in the Magneticall globe of the earth in passing about her meridians for all Magneticall motions are performed vpon the meridians principally as hath bene said Therefore place any Magneticall body as is vsed to be done free from all obstacles Tab. XI Fig. 5. 6. that may hinder their motion and conformity and they will be situated conformably vnto the meridian of the earth because that the earth hath primarily naturally frō her first creation all Magneticall faculty vigour vertue power and potency in her selfe And first if a Magnet whose poles are knowne by the Art before taught be placed in a boate or boule of wood and put into a great bason or boule of water it will conforme direct and seate it selfe North and South according to the same position and meridian that passeth directly vnto the poles of the earth Likewise take a Magneticall needle that hath bene excited with the Adamant such as be in moueable dyals or else take the Marriners compasse and place them in quiet situation and they will be directed by the disponent vertue and Magneticall vigour of the earth towards the North and Southpoles vpon the true meridian circle and line if there be no obstacle All direction is obserued by Magnetical bodies especially by the directory-needle and compasse vpon one certaine horizon whose center is in a meridian cut by some of the paralels and on this center the needle and compasse is supposed to be placed being truly peased and composed that they may play turne too and fro and rest leuell and paralell vnto the horizon fitly placed vpon a pin of brasse or siluer and be well touched and excited to the end they may be directed more certainely towards the poles vpon the meridian Tab. XII Fig. 13. All Magneticall needles would be touched with a good vigorous and bigge Load-stone that being capped lifteth vp at least halfe a pound weight of iron to the end it may carry the flie and card of the compasse more strongly to his true direction and situation all needles and compasses that are to be animated and excited with that part of the Magnet that seateth it selfe North swimming in a dish vpon the water by the disponent power of the earth and being freed from out of the orbe and vertue of other Magneticall bodies these are turned and directed by the vigor of the earth into the South vpon the meridian line Euen so a rod of iron that stath bene placed North and South in a window a long time whereby he hath receiued a true touch of polar vertue from the Earth being within the orbe of his vigour and being remoued from this position which would be noted with chalke and hanging leuelly in a string in the aire will moue his North part and seate it in the South quietly Therefore all Magneticall bodies whether it be the Magnet that is taken out of the Earth or a part of a Magnet taken out from this stone that was cut immediatly out of the earth or any iron or steele that is excited either from the earth from an Adamant or from another excited needle iron or knife or long forme of burnt clay all these whatsoeuer receiuing their directiue and polar faculty from another Magneticall body being set at liberty artificially in the aire or water to moue and turne will seate and be directed to the contrary pole they were first reuiued by Euery part from the aequator to the pole doth giue a polar and Magneticall vertue vnto diuerse formes of iron and steele to moue vnto a contrary position by the directiue faculty of the earth This faculty directiue is as strong vpon the aequator as elsewhere though it do not bestow it to others being fortified from both prouinces on either side and when the needle and compasse shall be in the aequator of the earth because their libration and leuelnesse is all one with the horizon therefore here the direction is conformable and strong but in other places and neere the pole especially the leuelling of the needles is more violent because they would incline and make an angle with the axis and therefore the direction here is thought by some to be very weake yet in this place neere the pole in the Terrella and Semiterrella the little needle on his foote beareth himselfe most strongly and stiffely that being with a finger turned awry it will turne againe to his direction very violently though inclining to the stone and rest it selfe very speedily
true angle and that is the variation of the Inclinatory-needle for that place CHAP. XXXXIII Of finding the Longitude HEre I purposed to haue ended this short Treatise of Magneticall matters but because that this thing is not altogether impertinent thereunto I thought it not superfluous to annex this little chapter of finding the longitude for although that the Magneticall needles before treated of do not shew the longitude yet because the true meridian and altitude of the pole is knowne by them there is much helpe brought thereby for the knowledge of the longitude which by a few easie obseruations more from the body of the Moone will be obtained whose motion if it should be set downe and ordered in an exact manner would require a large discourse with many rules and obseruations of the Moones inequality of motion anomaly and prostapherisis of his excentricity paralaxis with the varietie of his latitude and nodes which thing being very laborious and curious shall be here omitted referring you herein to Tycho Brahe and his rules and onely I shall here set downe rules to know the place of the Moone at a larger scantling yet very neere the truth though not the truth it selfe which peraduenture the best Studied in this kind can very hardly do only borrowing halfe a dayes motion at the Moone wherein the matters before mentioned will not alter many minutes Prouide an Almanake or Ephemerides for any place or port wherein the apparent place of the Moone in the Zodiacke is exactly set downe in degrees and minutes for the noone of euery day especially of the day of obseruing then take the difference of the Moones motion from the day before and reduce it into minutes deuiding them by 24 houres the quotient will shew what minutes the Moone moueth in an howre Now take the altitude of the Moone at any time of the day or night by the Iacobs staffe or a quadrant then obserue the Azimuth of the Moone by shadow as before for the Sunne or by a ruler with sights which if it do differ any howers from the meridian alow the parts due of the Moones motion Then seeke in the Râ—te of the Mathematicall Iewell or Vniuersall Astrolabe where the Azimuth and Almicantaraph of the Moone newly obserued cut each other setting the horizon to the altitude of the pole and looke what paralell doth cut these two and follow the same vnto the Eclipticke line or do 〈◊〉 like of the Moones latitude in that signe degree and minute of the Zodiacke the Moone is in at that instant These degrees fewer or more then those of the radicall and fixt meridian for which the Ephimerides was made do shew what howres and parts are to be added if the obseruation be towards the West or substracted if in the East to this meridian it is to be noted that euery hower coÌ„taineth 15 degrees of the Equinoctiall and thus the longitude of that place you are in will be attained which you desire But to find the longitude of any place you go to from the place you passe from by these Magneticall-needles onely it will be necessary to pricke your Card as well by the degrees of latitude of the pole correspondent to the angles of the Inclinatory-needle as by the way the ship maketh vpon the points of the Directory compasse and therefore it will be fit to haue both these needles placed together as in the type of the XL. Chapter and pendant before the Mariner at the helme with the Compasse and Trauers-boords for them both Now for this purpose I would haue another Trauers ruler or limbe for the quadrant of the Inclinatory-ring placed before him as it is described in the Page following where there is only 30 degrees deuided vpon the same which being twice more repeated will make vp 90 degrees euery degree hath 6 holâ—â— for pegs to be put into them for the number of 10 minutes apeece and on the first columne on the left hand there are 4 holes made to receiue pegges according to the number of howers you saile on such a degree and minute pointed in the Inclinatory-ring If any errors should chance to fall out by any variations of either needle then at any time when the Sun doth shine they may be amended by the precepts already largely deliuered in that case of either both in many Chapters of this booke and in the last precedent Chapter CHAP. XXXXIIII Of the matter of the Magneticall globe of the earth by the Needle AT length we haue brought our short Treatise Magneticall principally most profitably to declare the nature of the Directory and Inclinatory-needle both towards the Terrella and Semiterrella and towards the Magneticall globe of the earth and how the proportions and similitude of their applications and conformities to both are alike and the same Onely the Magneticall-needle being of a saeminine and sequent substance as hath bene demonstrated in the VIII XXI and XXII Chapters doth behold the round Magnet and the round Iron with that point that is of the same nature and demonstration that the pole is which he followeth and affecteth contrary to the nature Magneticall that is in the Adamants themselues one towards the other or of the needles one towards the other But this Magneticall-needle being freed from the Magneticall orbe of the Loadstone and Iron will haue that point of the needle that followed them directed by the vertue Magneticall of the earth into a contrary prouince of polar preheminence For the Magneticall-needle doth conforme it selfe vnto the Earth in the same fashion that the Adamant and Loadstone it selfe doth neither is it so seruiceable vnto the Magneticall globe of the earth as he is vnto the Magnet and Iron but is of a fellow-like species with the earth as well as the Adamants themselues are Whereby I do gather that the matter of the interior parts of the Magneticall globe of the earth is not the same with these we know of the Loadstone and iron into whose bowels neuer any maÌ„ by the deepest mines or other passages of fissurs and cauities made by great Earth-quakes euer yet descended to shew vnto vs any part of the earths interior substance Magneticall and though I take the matter of the bowels of the earth to be Magnetical yet the application of this Magneticall-needle demonstrateth that the Magnetical globe of the earths inward substance coÌ„sisteth neither of sollid Load stone nor of iron-like mine or clay or such like materials as they which haue thought themselues most skilfull in Magneticall Philosophy haue imagined For if the Magneticall globe of the earth were of any Iron-like substance then that point of the needle that affecteth a polar iurisdiction placed neere the Loadstone and the iron would also being applied vnto the earth behold the same prouince and iurisdiction polar being directed by the vigor of the earths Magneticall orbe of like nature but this is not so as all confesse and may proue Therefore I hold that the great Magnetical globe of the earth consisteth of a Magneticall substance vnknowne vnto vs as also the bodies of the Magneticall globe of the Moone and of the rest do and so conclude that the workes of God are most wonderfull and altogether past finding out But here before I end I am to satisfie that I made promise of in the XII Chapter that I would shew my conceipt of the reason why the needle in his passage from the aequator of the Magnet by the pole to the aequator againe should make the circumuolution of an whole circle in turning about his foote hauing passed a semicircle of the Terrella or Semiterrella and would make another whole circle about the other semicircle of contrary nature with his other point For to cleere this with the nature of the two prouinces which is aduerse one vnto the other I would wish that you would conceiue and propound two globes of Magneticall nature and substance as tender as clay the one of them to be animated with the North and articke vertue at both poles as Tab. XX. Fig. 3. aa to turne to the North onely and the other globe with his poles Tab. XX. Fig. 3. bb to be endowed with the antarticke power to moue to the South onely Now if the globe of the earth or of the Magnet-stone were made onely of one of these globes then there would be a strife betweene the poles of one of the globes which should behold his peculiar point as if the pole a of the North vertue should behold the North the other pole a of the same globe being of articke nature would also striue to behold the North or at least in their equality of power would rather respect East and West so that there would be no stability by the poles of such kind of globes Therefore the skilfull Potter who made the earth TAM ROBVR TAM ROBOR NI-COLIS ARBOR IOVIS 1610 N O LONDON Printed by Nicholas Okes dwelling neere Holborne-bridge at the signe of the Hand 1613.