A SHORT TREATISE of Magnetical Bodies and Motions. By I Park ●●d●ey Dr in physic and Philosoph● 〈◊〉 Physician to the Emperor of Russia, and one of the eight principals or Elects of the College of Physicians in London. LONDON. Printed by Nicholis Okes. 1613. engraved title page A Preface Magnetical. PVrposing to deliver a brief and easy doctrine as concerning this new Art of Magnetical Bodies and Motions: I thought good here to free the same from the lustre and gloss of disputable points and other conceits, only purposing to handle nothing in the same but the plain matter and demonstrations. Magnetical themselves, thinking it more fitting to place these flowers in the Preface, if any delight rather in them, then in the matter itself, to the end they may in some sort be provided of both. As concerning the first finding out of the Magnet-stone, whereof I am to treat, Pliny and Nicander have feigned that a certain herdman being in the fields, having his shoes shod with iron, and his staff armed with an iron pike, and resting himself upon a quantity of this stone, could not easily remove his feet, or lift up his staff, whereupon he perceived the attractive virtue of this stone, that it did attract and hold iron. Other think that the pioneers and diggers of metals, by their diligence and observances first found out the Loadstone, and his virtue of attracting iron, by which property it was well known to the ancient Egyptians and Graetians in times past. Some have thought that the Magnet would lose this quality attractive, if he were anointed with garlic, or touched with a Diamond, and of this opinion were Ptolemy, Plutarcke, Pliny, and Baptista Porta; for this malady Ruelius hath found a remedy to anoint the Loadstone with goats blood, and Paracelsus with his oil of Crocus Martis, will not only cure him of this evil, but can make him ten times stronger than he was before, likewise Cardanus and Alexander Amphrodiseus have laboured to nourish the Magnet with fitings of iron and steel. Many have strived much to inquire out the cause how the Magnet should attract iron unto it, Epicurus, Aphrodiseus, Carus, johannes Costaeus, Plutarch, and Thomas Aquinas do suppose this attractive virtue to proceed from certain motes, unsensible parts or vapours issuing forth of the Magnet, and entering into the iron by convenient figures, and in their retiring back again do attract the iron to the Loadstone. Plato and Fernelius have thought the cause of this attraction to be Divine and from above. Thales and Anaxagoras say that the Magnet hath life in it, whereby it attracteth the like substance as living things do. Some think that there is a certain sympathy between the Magnet and iron, as between the male and female, as Orpheus and Lucretius have sung. Auaroes', Scaliger, and Cardinal Cusanus would have iron to move unto the Magnet, as to his beginning and matrix, from whence he came. Gulielmus Puteanus, Galen, and others, do judge that by his substantial form he draweth iron unto it, but Doctor Gilbert, whose labours are the greatest, and best in Magnetical Philosophy, doth conceive that the Magnet and iron do move one unto the other, not by any specifical form, but from the essential form of the Magnetical globe of the earth, being an essential part of the same, which is not so, as it shall be demonstrated in the last Chapter of this Treatise. To illustrate this virtue of attraction in the Loadstone, Serapio and the Moors, like far travelers, have reported that in the Indies there be mighty craggy rocks, all of Magnet-stone, that will stay the ships as they sail by them, and pull the iron nails out of them; this story Olaus Magnus also confirmeth to be so in the North, and that there, lest the rocks of Loadstone should pull the iron works and nails from the vessels and boats, they build them with wooden pins, and sow the boards together with lines of the barks of trees; which indeed they do both for want of our skill in building ships and barges, and for want of iron works, whereof they have little store. And because this stone hath virtue to attract, therefore Marbodeus a Frenchman, Petrus Bairus, Pictorius and Arnoldus de villa nova do feign that this stone will procure the love of Princes and of women, and maintain love between husband and wife. Halyabbas will have the Loadstone to cure the gout, if it be held in the hand, and the East Indians say that it preserveth youth. Caelius Calcaginus saith, that if the Magnet be preserved in the salt of the sea-Lampron or Remora, that is thought to stay a ship under sail, that then the Magnet will draw up gold that is fallen into the deepest well. And Fracastorius testifieth that he hath seen a Magnet that would draw silver unto it, and chase iron from it. Cardanus, Antonius de Fantis, Petrus Perigrinus, and john Taisner do deliver that there might be made a perpetual motion by the virtue of the Loadstone, but by the experience of many ingenious practices I find it unpossible to be done. Since the finding out of the Sea-compasse, which was about 300 years ago, by one Thomas Goa, borne near Naples, or by Marcus Paulus Venetus, who learned that skill in China, as is thought, and first brought it into Italy, there have grown many opinions how this Compass should be directed into the North and South. Marcilius Ficinus, Paracelsus, and Cardan think that the virtue of the constellation of the Bear doth govern the Magnet and iron, and therefore both these are directed into the North. Petrus Peregrinus, Friar Bacon, john Taisner, and many other would have the Compass to observe the North pole: But since that Sebastianus Cabotta, did find out that the Compass did vary from the true meridian, it hath been imagined that there is some place in the heavens that the Compass should respect, as Cardan would have it, to observe the star in the tail of Vrsa major. Bessardus, a Frenchman saith that it doth behold the pole of the Zodiac, Martin Cortesius would have an attractive point above the heavens, and Robert Norman an Englishman, denieth that there is an attractive point, but affirmeth that there is a respective point, to the which the Compass doth move, especially the Inclinatory-needle, whereof he was the first invent or. Livius Sanulus supposeth that there is a certain Magnetical meridian, and Francis Maurolicus, that there is a Magnetical Island, and Fracastorius holdeth that there be certain Magnetical mountains, which be set out in Plancius his Card, that the Compass doth respect. But Doctor Gilbert, our friend and Collegiate, hath discovered these errors, and set forth the causes of the variation of the Compass in his book De magnet. Yet lately Gulielmus Nautonerius, a Frenchman, and Anthony Linton an Englishman have supposed that the Magneticall-needle and Compass do move and turn themselves upon the Magnetical meridian always unto their own Magnetical poles, placed upon the superficies of the earth that be near, and within the circles polar, not varying at all from their own meridian, but devidte only and decline from the meridians of the pole of the world, and with this conceit, these two, with many curious calculations and projects, will presently find the longitude of all Cities and Countries; but this their strong imagination hath failed them, being grounded upon observations from the variations of the needle, from which these two men have set forth different Magnetical poles; and if they should work from 500 observations, they might guess at near half as many variety of poles (for variations are not regular, but irregular, because their scattered causes be irregular) so that these men have found instead of the longitude of places, a longitude of unprofitable labours. Therefore, not purposing to dazzle any one's conceit with the repetition and confutation of any opinions, terms of Art, or words whatsoever, I will come to the Tractate itself, thinking that the quivering Magneticall-needle will be trouble enough to handle for the better knowledge and delight in Magnetical 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 form and caps. CHAP. III. Of Iron. CHAP. IU. Of the Earth. CHAP. V Of the two poles, and how those points are found out. CHAP. VI Of the virtue of the poles. CHAP. VII. Of the Axis. CHAP. VIII. Of the aequator. CHAP. IX. Of the meridians. CHAP. X. Of the Parallels. CHAP. XI. Of the Horizon. CHAP. XII. Of the 2 circles that the needle maketh about the Magnet. CHAP. XIII. Of no circle the needle maketh round about the Magnet. CHAP. XIIII. Of the distance and orb of the Magnets virtue. CHAM XV. Of applications. CHAP. XVI. Of preserving the virtue of the Magnets. CHAP. XVII. Of contributing the virtue Magnetical to iron or steel. CHAP. XVIII. Of augmenting the virtue of the Magnet. CHAP. XIX. Of the decay and decreasing of the Magnets virtue. CHAP. XX. Of the commutation of the virtue Polar. CHAP. XXI. Of the discord of the two points of the Adamant. CHAP. XXII. Of the Magnetical union. CHAP. XXIII. Of attraction Magnetical. CHAP. XXIIII. Of the strong apprehension of the Magnet. CHAP. XXV. Of Magnetical direction from the earth. CHAP. XXVI. Of the variation of the Compass from the true meridian. CHAP. XXVII. Of finding the variation of the compass by 1 observation. CHAP. XXVIII. Of finding the variation of the Compass by the circles of the Astrolabe. CHAM XXIX. Of finding the variation of the Analemma. CHAP. XXX. Of finding the variation of the Compass by an Equinoctial Dial. CHAP. XXXI. Of finding the variation of the Compass by rings. CHAP. XXXII. Of finding the variation of the Compass by an horizontal Dial. CHAP. XXXIII. Of finding the variation in degrees & minutes, by the doctrine of Triangles. CHAP. XXXIIII. Of the Application of the Inclinatory-needle to the Axis of the earth. CHAM XXXV. Of the Inclinatoryring & needle. CHAP. XXXVI. A Diagram of the needle's 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 parallel. CHAP. XXXVIII. Of finding by the needle's inclination unto the horizon, the altitude of the pole by an instrument. CAAP. XXXIX. Of finding the needle's inclination in every latitude by table. CHAP. XL. Of finding the angles of inclination the Magnetical meridian & the Azimuth together. CHAP. XLI. Of the variation 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 Magnetical globe of the earth by the needle. MARCUS RIDLEUS CANTABRIGIENSIS IMPERATORIS RUSSIAE ARCHIATRUS etam ●4. 〈◊〉 1594. Mis●us ab Elisa Ruthen●s qumque per annos Anglis 〈◊〉 deses t●Vocat 〈◊〉 domum Tu●e mathematicis clarus magnetica calls P●o●ias laudes doctus Vbi que capis portrait of Marcus Ridleus To the Courteous Reader. COurteous Reader, I have written thee a small Discourse as concerning Magnetical Bodies and Motions, the which I hope will not be obscure unto thee through his brevity, because of his plain method, and easy demonstrations, which with their pleasantness will prove very ready and apparent unto thee, especially being animated from the Magnet stone itself, as from a most lively and perfect teacher: Therefore I would advise thee, that when thou readest this book, that thou wouldst provide thyself of such like forms of Magnets as I have described in the first Table and figures of the second chapter, as also of needles, wires, and weights of iron and steel, set forth in the second Table of the third chapter of this book, which thou mayest have made and provided for thee by the help of some skilful workmen: when thou shalt be furnished with these kinds of provisions, than thou mayest read and practise the operations and demonstrations of this book, which will be both easy and very pleasant unto thee; and though that there be many precepts and practices in this Book, which be not for example sake set down in tables and figures unto thy sight, because I desired to be very brief, yet if thou shalt not be altogether unskilful in these demonstrations that be delineated in the Tables of this book and their often practice, thou wilt be able enough to understand and put them in ure, with these forenamed provisions. But if thou shalt desire, besides thy instruction in this kind of learning, to put in use and make benefit of these matters Magnetical, either in traveling or sailing upon the Magnetical globe of the earth, than it will be very necessary for thee to be stored with the Mariners Compass for the sea, perfectly drawn and framed, to know the way, and of what hand and point to sail and travel, and also to have the Inclinatory-needle truly placed in his ring, and a Directory-needle, or a little fly Magnetical in the box, fastened at the bottom in his convenient distance, for to know under what latitude thou art every day of thy voyage: Likewise if I should declare unto thee how beneficial the Directory-Magneticall-needle is for the description of Ports, Havens, Forlands, Capes, Bays and Rivers, for the more perfect making of Sea-cards, how necessary for the positure of buildings, directing of dials, and all Mathematical instruments for measuring and surveying, for pioneers and underminers of forts, for searchers of minerals, metals, sea-coals, and other subterestriall bodies, I should be too tedious unto thee, and will rather refer thee for these matters to that which is set down by others, because I meddle here in this book only with those things that be Magnetical. In this place I think good to advertise thee as concerning the magnitude of the seven Planets, with their respect unto the earth, out of Tycho 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 odds: therefore I have deciphered that in figures; as let the Earth ♁ be but one part, the Suns ☉ greatness will be 140 times so much; Saturn's ♄ 22, jupiters' ♃ 14. And if that Venus ♀ have 6 parts, the Earth will have 37 parts, if Mars ♂ be one part, the Earth is 13, if Mercury ☿ be one part, the Earth is 18, if the Moon ☽ be one part, the Earth will continue her 42 times. Besides, I have drawn the Axis in the greater Planets, as being bodies Magnetical: for I trust that these following times will discover whether they be parallel one to the other, or no, as also what natural motions else they have, because that Astra natant, avis instar in aëre, aut piscis in unda, and here it might be said that we hope that many new points in Philosophy and Astronomy will blossom and spring out of this kind of learning hereafter, Thine in all affection, M. R. A SHORT TREATISE OF MAGNETICAL BODIES AND Motions. CHAPTER I. Of Bodies Magnetical. THAT we define to be a Magnetical body, which seated in the aether or air, doth remain and place itself in one place or kind of situation natural, not alterable; as all stars do, and the great regent Globes of Saturn, Mars, jupiter, the Sun and the Earth do; or such as with respect and attendance follow other Globes, as the two stars which support Saturn, the four attenders upon jupiter, lately discovered by the trunk spectacle, the two travesers about the Sun, called Venus and Mercury, and lastly the Moon, which doth follow, or go about the Earth, and respecteth the same always with one pole: and therefore hath a peculiar Magnetical virtue that guideth her in this kind of situation. All Magnetical Globes have some parts of their bodies which be also Magnetical, which being separated from their proper globes, and no way hindered, will seat themselves or be seated unto the natural situation of their particular Globes. The Earth, whereon we live and move, hath two minerals that be Magnetical, the one is the Magnet or Loadstone, which draweth iron unto it, and this iron or steel is the other. Either of these two being conveniently, and artificially placed in the air, or in a boat on the water, freed from all obstacle and renitency, will place and rest certain parts of themselves, which be called the poles of their body, respondent unto the poles of the Earth, which situation we call North and South, because they be parts of the Magnetical globe of the Earth, who by her attractive and disponent virtue, doth thus direct and situate them. CHAP. TWO Of the Magnet stone, his form and caps. THe Magnet stone is heavy and massy, like unto iron, having much steel and iron in it, this stone will attract, hold, disperse, and compone like a little earth other less Magnets and Magnetical forms of iron and steel to his conformity of axis and poles. This stone is called the Magnet, of a country in MACEDONIA so termed, where plenty of them are found, it is called Hercules' stone, of a City of that name, and it is called the Iron stone of drawing it, we call it the Loadstone, the Adamant stone, and the Osmound stone in our Ironmongers shops; because of his leading directive and attractive quality, and it is well termed the Osmound stone, because he is as it were Os mundi, the bone of the world: for by his virtue Magnetical he is like a bone and pillar whereby this world and globe of the Earth is sustained and supported in his just situation, as the little world of the body of man is supported by his bones. The colour of the Magnet is like to duskish iron, of a sad brown and sanguine colour like a liver, some of them are coal-black, bluish, ashey, or of a whitish colour. Some are as heavy as iron, firm and solid, other rare porous as a sponge, some very hard not to be cut with axe or chisel, but must be ground and fashioned on the grindstone, other are very soft. The best and strongest are commonly found of one entire piece, such as be of one mine and broken from the rock are of one strength, if they be suddenly severed; some Magnet stones be very weak and of little force to take up, only good to move the Needle. The stone is not so scarce, but that in all country's one sort or other of them are to be found. Tab: I diagrams The first form of the Magnet, which I offer unto your eyes, Table I. Fig. 1. is a large one, in fashion of a round ball, bowl or globe, and we do call it a Terrella, or little earth, because that upon this figure of the body of the Magnet stone, we shall hereafter show how to find naturally the poles and the rest of the circles of the Sphere, proving unto your eyes all kinds of Magnetical demonstrations on it, and shall after, most fitly and naturally, declare how to observe them in traveling or sailing upon the great Magnetical globe of the earth. This form may be artificially capped and armed with steel, or iron, at his two poles, Tab. I. Fig. 1. a. b, for to take up iron weights, or to touch Magnetical needles withal. The next fashion is a round and flatforme, of a reasonable thickness like a coite, cake, half bowl, Holland-cheese, or part of a column, Table I. Fig. 2. and may be called a Semiterrella his poles, Tab. I. Fig. 2. a b must be situated in the midst of the sides of the roundel. This form may be capped artificially at either pole, Tab. I. Fig. 2. a b with two square teeth of iron, Tab. I. Fig. 2. a b, descending at right angles to the line of the axis, Tab. I. Fig. 2. a b, and this is almost as convenient as the former in the first figure of this first Table for all Magnetical demonstrations, which are performed only upon a Meridian circle that passeth by the two poles, which this form hath. And the stone for this form is more readily procured then that is of the first and globous fashion. The oval and long form like an egg, Tab. I. Fig. 3. is thought to be the best fashion, by some, for to touch the needles of the sea Compas withal, and to take up weights at one end, Tab. I. Fig. 3. a b, because he hath a long diameter line, Tab. I. Fig. 3. a b. The long egg form flatted at the bottom with two iron teeth from the two poles, Tab. I. Fig. 4. a b, as the Semiterrella hath, Tab. I. Fig. 2. a b, the square forms with four teeth from the two poles, Tab. I. Fig. 5 & 6. a b, two teeth at one end, all these are very fit fashions to take up great weights, and to touch Magnetical bodies and instruments withal, as shall be hereafter set forth. There be many other fashions that may be invented and wrought at pleasure of the Cutter, or as the Loadstone will be fittest for, as the sixth square, Tab. I. Fig. 7. the six angles unequal, Tab. I. Fig. 8. The four 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, having their caps with one or two teeth, will take up by them both, or severally, and are good to touch needles, wires, knives, daggers, and such like long forms, to give them virtue to take up smaller wires, sowing-needles and such like small weights, or to give the virtue polar. You may cap and arm some kind of forms of Magnets with four teeth, two teeth from the side flatted at either pole, as we have described Tab. I. Fig. 7. which hath four square iron teeth, like a four footed stool, to raise up weights with four teeth together. If you had a Magnet stone of a flat form, that had his poles in the centre of the stone, as these I have described have their poles in the ends, than you might place one side with his pole downward, and the other side upward, and provide you a cap for the uppermost side, like a Greek 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉, and a cap for the nethermost side like a Slavonian 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉, and these being artificially and discussively fastened to this Loadstone, would take up weights with five teeth, as it were an hand with five fingers. I have drawn a line a b in all these forms, parallel 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 perceived. Nevertheless, in fashioning of some Loadstones, the axis cannot so aptly be always placed in the midst of the ends of the Loadstones being flatted, unless there be a greater part of the Load stone taken away, & the bulk very much diminished, which will lessen much the strength of the stone: for the greater that the bulk is, the more is the strength of the Magnet. Therefore I have set down a type in the last place, Tab. I. Fig. 12. where the diameter a b lieth awry, and the poles be situated higher and lower at the ends, and yet the Loadstone shall take up as much in weight as if his diameter 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 virtue of the stone, and sometimes many ounces may be cut away without any loss of Magnetical vigour, especially if any substances of other nature be intermingled and agglutinated to the Magnet, which may be known by their colour and hardness very easily. Also, if there be any cavities and hollow places, or broken parts of the Loadstone that do diminish his virtue, or disfigure his form, this may be supplied, mended and filled, either with a piece of another Loadstone, or with a cement of the powder of the Loadstone, and the filings of steel or of iron brayed and grinded very small upon a painter's stone, mixed with resin and wax, melted and coloured to the colour of the Magnet that is mended, putting into this cement more or less of the filings, according to the strength of the Loadstone. Some with this cement, and such like glutinous matter, make diverse forms of Magnetical bodies artificial. It is very convenient for makers of sea-compasses, and masters of ships to have a Magnet well capped, that taketh up at one end half a pound weight at jest, for it is not wholly necessary that the same should be of the best vigour and strongest rock: for all Lodestones, both of great and less vigour, have the same faculty Magnetical to all intents and purposes. The greater stones of the same rock have a larger virtue than the less, and every part and small pieces of Magnet stones have every one of them the same virtue and vigour Magnetical the great ones have, saving that they be more weak, and not always proportionable in strength unto them. CHAP. III. Of Jron. IRon is a metal 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 Magnetical, for it being placed artificially, either in the air or upon the water, moveth North and South, attracteth other iron unto it, and performeth the same conclusions that the Magnet stone doth. This metal is heavy and of a bluish black colour after that it is tried from the dross, and is made of certain juices and vapours in the convenient bowels of the earth by a specifical virtue working him. Besides the mine this metal is excocted out of diverse stones, sands, earths and clays of diverse colours, which have much Iron like matter in them. If some clay 〈◊〉 burnt in the fire, being of a long form, cooling North and South, after being hung on 〈…〉 in the air, or put into a dish in the water, it will turn and move itself too and fro, till it rest North and South, and some clay being burnt, will show a little iron upon his sides that was melted out of him, so that this Magnetical substance of iron is not very scant to be found: for in all countries and regions there is great store of this metal, being the principal matter of the external bark of the globe of the earth. Steel and iron are the best Magnetical materials for Magnetical uses; because by the Smiths skill they will be extended and fashioned into diverse forms, fit for the practice and use of Magnetical demonstrations. Of this metal are made caps for Lodestones of diverse forms with teeth, to take hold of, and lift up great and small fashions of weights of iron, and diverse other Magnetical needles and forms. Tab TWO diagrams It is good to have long plates of iron reasonable thick, Tab. II. Fig. 7. round plates of iron, Tab. II. Fi. 9 and round rings of iron of diverse weights and bigness, Figure 8. It is convenient to have diverse directory Magnetical needles, great and small, Tab. II. Fig. 10. 11. for dials and instruments, and needles for Compasses, Tab. II. Fig. 12. & 13. to fasten to the Cards, or to take off at pleasure: we use short wires fastened to thirds; and a little Loadstone in a third to take up a weight. Also it is necessary to have Inclinatory-needles, Tab. II. Fig. 16. to put into his ring, and a short one with a Lutestring in the midst, Tab. II. Fig. 17. or else put in a frame of brass or silver, as Tab. II. Fig. 18. to find the pole of the Loadstone, and to demonstrate his obliqne inclination to the Loadstone, as he is carried about him, or else to have a little round Loadstone put into a frame with an axle-tree, having his poles marked Fig. 19 which applied about the Loadstone, turneth and conucrteth itself diversly, also it is fit to have a short and thick needle, Tab. II. Fig. 20. into the end of it, there is to be put a wire of silver, brass, or of a piece of a Whale-bone, for uses hereafter to be declared. Also a long wire thrust through a cork, Fig. 21. serveth for Magnetical uses in the water. These forms of iron, with others that the ingenious will easily invent and make, are very fit for Magnetical demonstrations, as well as the variety of Magnet stones are. CHAP. FOUR Of the Earth. THis great Globe of the Earth whereon we move and travel, is found to be a Magnetical body, by such as have traveled and sailed round about her, as Sir Francis Drake did, and M. Candish, whose Magnetical Compasses were always directed Magnetically, that is, the Lily of their Compasses was turned always towards the North-pole in all places wheresoever they sailed, by the virtue Magnetical, and disponent faeulty of the Magnetical Globe of the Earth, as it is demonstrated in the XXV. Chapter of this Book. Also by such as have made their course northerly and southerly, it hath been observed that the Magnetical Inclinatory-needle doth in every elevation of the pole conform and apply itself, or rather is conformed and disponed unto the axis of the Earth, according unto certain correspondent angles to the Latitude, as it is demonstrated in the XII. XIII. XXXV. & XXXVI. Chapters of this Book, whereby it is demonstratively to be concluded, that the Earth is a Magnetical body, directing both herself and the other two Magnetical bodies into the North and South, by the virtue of her Meridian circles and parts, as is demonstrated in the IX. chap. and others. Moreover, the Earth hath naturally two Magnetical poles, unto the which these meridional parts do direct, bend & force, not only Magnetical bodies near the Earth; but also her own mighty and massy situation, stability and firmness, and seateth herself so strongly upon her two poles, by her natural and Magnetical vigour, passing from her meridional parts to the poles, as if she were tied by many mighty strong cables unto two most firm pillars, far stronger than any Hercules pillars, not to be removed by any force from her natural position; which thing, if it might chance that it should come to pass, yet certainly she would return again unto her former firm seat and place, as all Magnetical bodies and directory needles do, as is demonstrated hereafter. Thus we prove that the Earth is placed and firmed by her Magnetical virtue, and not by her gravity and weight, though that the parts of the Earth do conjoin and adhere together by their gravity moving to their Centre. But the Magnetical nature moveth, conformeth, and firmly seateth itself to the poles and Axis. Now for that the poles of the Earth do always, by their natural virtues hold the Earth North and South in one certain and uniform situation, elevation and place, there is no doubt but that the whole globe of the Earth, inwardly stored with many materials and rich minerals, & outwardly adomed with many trees and excrescences, all for the use of man, with living creatures innumerable, as also in reason it is an unfallible certainty, that the Earth hath, at her first creation, bestowed upon her a globous and starlike vigour, or intelligence, whereby she may, having her whole parts united together, by the virtue of gravity unto the centre, and her place made sure Magnetically by her poles unmovable; yet move naturally, keeping her place circularly & diurnally out of the West into the East, to the end that all creatures should receive the comfortable and lively beams of the Sun, and the influences of the rest of the Planets and Stars. This motion many learned men have attributed unto the Earth, for the benefit of calculating the motion of the Planets the better, which naturally she hath in herself; for even as it were needless for a wheel to have her nave, spokes and rimme about her, if it should not be used to turn about; so it were to no purpose that the Earth should naturally have a globous body, two poles, an axis, meridians and aequator, as shall be demonstrated hereafter, parts fit for circular motion, and not for to turn her aequator and parallels about, as the wheel doth. Although these arguments will hardly persuade us to believe the earth's motion; yet because that it is lately observed unto our senses by help of the trunckespectakle, both by Galileus and Kepler, famous Mathematicians, that the great body of the globe of jupiter, being twelve times greater than the Earth, doth turn about in less time than a day upon his axis and poles, who also have observed four Moons, attendant on jupiter, which move round about him, the slowest in 14 days, the next in seven days, and the rest in shorter time. So likewise john Fabricius hath observed, that the great globe of the Sun, having three great spots, like continents in him, and being sixty times greater than the Earth to move about his axis and poles near the time of ten days, or there about, so Galileus and Kepler have seen the Planet of Venus to move about the Sun in ten months, and to have her light from the Sun in this time increased and diminished upon her body, as we see the Moon here nearer unto us to have; therefore it being certain by observation, that the globe of jupiter and the Sun do turn about their axis and poles, whose materials we know not, we need not doubt that the Earth should have a circular motion for her great good. But how the Earth doth turn circularly we cannot well see it, with the sense of our eyes, unless we had them placed in another globous body and star, as if they were in the Moon, where we might see the spots of the Earth to turn about, as well as now we see the spots in the Sun, and jupiter to move circularly in their place. And as contrariwise our eyes here on the Earth do see that the Moon doth not turn about, by the placing of her spots, always in one fashion unto us: for we may observe with our eyes, that the Moon hath poles of a kind of Magnetical nature, which do always hold her to behold the centre of the Earth, and so stayeth and conformeth her, that howsoever she move, higher or lower, or wheresoever she be, yet always the spots of half her globe be alike apparent unto our eyes, and conform her to behold the centre of the Earth with one pole: neither doth the Moon turn about her body upon two poles, as the Earth doth upon hers, but is kept firm and unmovable from circular motion, about her axis, by other two poles that be upon the edges and aequator of her body, because her spots be always alike on her East and West side, that hold her firmly & stiffly that she can by no means turn about upon her first two poles: For it is the virtue polar and Magnetical that holdeth all globes in their position whatsoever. Besides, the Moon hath another virtue given her at her first creation, whereby beholding always the centre of the Earth, and moving nearer and further from the Earth, as tied with an axle-tree, she moveth, slideth, and passeth monthly about the Zodiac, that all the parts of her globe may be illuminated and refreshed with the beams of the Sun, and influences of the Stars: for as a ship upon the water is directed even forward by the stern and rudder, which hath not only a right line to direct forward, but also a right angle descending downwards, that she wave not sidelings or turn about; yet having this position, if anchors be laid out, either forward, or backward, or sidelings, with their cables on board, if there be force or virtue on board to hale forward, she moveth forward, if drawn backward, she goeth backward, if pulled by the cable on the left hand, yet keeping her position, she betaketh to that hand, and so to other parts. Even so the Moon being seated, as afore is said, doth move on her axis, higher or lower, on this side or on that, according to the virtue & strength of the multiplicity of her axletrees, being her limbs to stay and move withal, as the body hath arms and legs, with variety of muscles to move on all hands. But the Earth, whereon we live and travel, hath never been found by any to have any poles in the aequator of her body, or near the same: for if we were so happy to find any in the East or West of the earth, than the matter of longitude would be perfectly attained unto, which hath so greatly busied all the ingenious wits of the world: and therefore we affirm that the Earth doth turn about, because there are no poles in the aequator to hinder her, as there is in the Moon from circular motion. But leaving these motions to others that do labour more therein, here in this book I purpose only to entreat of the great globe of the Earth, as she is a Magnetical body, which shall be first performed, by way of imitation, in a little Magnetical earth, or Terrella and Semiterrella, made of a round Loadstone and Adamant, whereby we shall plainly and sensibly demonstrate, that there be two poles, an axis, meridians, parallels, and an aequator in every Loadstone and Magnet, and we shall produce many other pleasant demonstrations, manifest Theorems, and sensible practices unto your eyes and understanding, which we shall after illustrate to be in the globe of the Earth, to prove it to be a third Magnetical body, different in substance from the other two Magnetical bodies, spoken of in the two former Chapters. CHAP. V. Of the two Poles, and how these points are found out. THe ancient Mathematicians and Astronomers of forms times, observing the diurnal motions and apparences of the Planets and Stars, feigned certain fixed poles, and other circles in the heavens, by which they discoursed of the rise, settings, motions, and of the places of the planets and stars; never imagining that these feigned matters were naturally and sensibly to be found in the globe of the Earth, much less to be seen naturally, and in a round Loadstone, and in all other forms of the Magnet stone, being long severed and kept from touching and couching in the bowels of the Earth. I will first prove how the two poles are found out in the Magnet stone, which are very necessary to be known, before that the Loadstone be fashioned into any form, for the better proportioning of the same; and this matter may be accomplished six or seven manner of ways. The first way is to role the Loadstone in small and clean filings of iron, and about those parts where the points and poles be, there the filings will clean fast in great multitudes, and at the pole will stand and be erected upright, mark these places with Chalk, Tripoli, Red-ochre, or with an hard file for the poles. The second way is to hang a sowing-needle by a third, or a small wire, Tab. II. Fig. 3 14. or as in Table III. Fig. 1. over those places of the Loadstone whereabout the poles are likely to be, and the needle and wire will move from his perpendicularity, and hang directly over the point, and desire to touch the pole. So likewise, if there be a small piece of a Loadstone, Tab. II. Fig. 15. cemented to a third, and held so that one of his poles bend downwards, and it will affect to touch and to unite itself to to the contrary pole in the stone. Thirdly, take the needle of a dial, or some of the directory needles, before described, Tab. II. Fig. 10. & 11. place the same, being touched Magnetically upon his pin or stake, Tab. III. Fig. 1. then turn the Loadstone round about, holding it somewhat near unto the needle, and it will point at the pole of the Magnet, desiring to touch it. Fourthly, take a piece of small wire, of iron or steel, such as is made for Virginall-strings, Tab. II. Fig. 6. and cut off a part as long as a barley corn, and set it upon the Loadstone, and it will stick fast at one end unto it, but erect itself▪ at the other end, and being put forward, will stand upright only there, where the pole of the Magnet is, Tab. III. Fig. 2. Fifthly, take a little Inclinatory-needle, before described, Tab. II. Fig. 17. that hath a Lutestring put through him, or take that Inclinatory-needle which is placed on a frame, and borne upon an axis, Tab. II. Fig. 18. and carry either of these round about the Loadstone, and they will conform themselves obliquely unto the stone, and only at the poles will direct the points of their ends perpendicularly over the same. Also take the little round Magnet, before placed upon his axle-tree and frame, Tab. II. Fig. 19 having his two poles marked, and this stone will turn and conform itself to the Loadstone, and apply his contrary pole directly over one of the poles of the Loadstone. Sixthly, place a small wire under the Loadstone, and it will follow to the pole thereof, and cleave and hang to the pole itself, which is to be marked. Seventhly and lastly, take that wire that is thrust through a cork, Tab. II. Fig. 21. and put it in water, holding a Loadstone unto it, and it will draw near, and bend itself to join to the pole of the Magnet. If a stone be divided and sawen in two parts from one pole to the other, or by a parallel, Tab. III. Fig. 3. the poles will be in their parallel place, Tab. III. Fig. 3. a b, and are to be found in the midst of the substance of the Loadstone, unless they be drawn aside by excrescenses and levities'. CHAP. VI Of the virtue of the Poles. Tab: III diagrams Magnetical bodies have two poles or points, the one is North, and the other is South, which be known either by hanging a Loadstone levelly in a third, or putting it in a wooden dish to swim in a basin of water, and then the one Pole will always turn to the North, and the other to the South, which are to be marked accordingly. But whether that Pole that seateth itself South or North may be termed by that part which it respecteth, some have laboured much to clear. If you chance to find out the rock where the Loadstone doth grow, where you purpose to take out a part of the same, mark your part with notes for the North and South, then cut out your piece out of the rock, and put it into a bowl to swim on the water, and your marks will be turned to a contrary situation, to that they had in the rock, and the North note will be turned South, and the South North, and so would the rock of the great Magnet itself, if it were so placed, make the like alteration in his situation, by the general conformation and direction of the mighty Magnet, the globe of the Earth. Therefore the reason why that the Loadstone in the boat upon the water, turneth, bendeth, and seateth itself to a contrary situation, to that he received and had primarily, whilst he was in the bowels of the Earth, and united with the body of the great Magnet, is because that every piece and part of a Loadstone, being separated from the whole whereof he was a part, is now become a perfect, complete, and sole Magnetical body, and is as it were, a little earth of itself, having all the proprieties Magnetical that the great Earth hath, as his two poles, meridians, aequator, and such like: and therefore according unto the nature of Magnetical union, hereafter spoken of in the XXII. chapter, will in no wise endure, and cannot be suffered to match and seat itself as he did before, but thinketh it more natural, and a thing of more perfection and conveniency to turn his aspect a contrary way, to that he had primarily at his first making and endowment with Magnetical virtue. This alteration of polity is to be observed likewise in Magnetical needles, and long pieces of iron that be touched, and animated, and adhere to that part of the Loadstone, which seateth itself North, which being at liberty and separated from the Loadstone, will turn that part and end that was touched at the North pole, and seat it always in the South, and it shall be sufficient for use to know and mark with a note which is the North-pole of your Magnet, and which is the South-pole. There is another virtue in the Poles of the Loadstone, and that is, that the South-pole turned downward, will take up more than the North-pole will, and the North pole will erect a greater weight th●n the South part or pole will, as some say, Tab. III. Fig. 2. a b. But I have always observed, that the Pole of the Magnet that seateth itself North, is always the most vigorous and strong Pole to all intents and purposes: unless he lack the quantity and like substance the South part hath. These Poles which be in the great Magnet of the globe of the Earth, have a marvelous strong Magnetical power imparted unto them, that they cannot be turned either higher or lower, or moved to the right hand or to the left, but hold the Earth continually in a true and certain position and place, and would if any force or power should move their great strength awry from the true site and meridian latitude, return to their right site and place again, and this is the true virtue of the Poles of globes, which the Sun and jupiter have as well as the Earth. These Poles be most certain and sure marks for all Magnetical bodies, conveniently carried to direct themselves unto, Tab. III. Fig. 9 as appeareth by our Compasses, which in all places of the world turn their Lily into the North, whereby the Mariner knoweth what course to take. And the Magnetical Pole, & Poles of the world, both arctic & antarctic, are all one and not diverse, as some have imagined, which have lost both their oil and their pains; 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 certainly in her polar position, while she turneth herself about to receive the Sunbeams, and influences of the stars and planets, for the generation and maintenance of all inferior bodies, upon her, in her, & proceeding out of her. Lastly, these Poles of the Earth, in certain great number of years, have naturally a little inclination in the polar circles of the Zodiac, for the receiving and moderation of the beams, lights, and influences of the stars, whereby the progressions and anticipations of the equinoctial, and the mutations of the greatest declination of the Sun are perfectly understood, to prevent the feigning of many Spheres above the stars, as the ninth, tenth and eleventh, and their impossible motions. In fashioning the Loadstone, it is convenient to make flat or roundish the ends of the Magnet, where the Poles are the better to cap and arm them with iron or steel, to lift up their convenient weights, 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 compass, that did behold the South of himself, being applied to the North-pole, doth turn, as some think, 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 itself, and the places near adjoining: for at the North-pole, if the Magnet be truly placed, that point that pointeth towards the South, doth point to the South directly, and in the places near adjoining doth it obliquely. A wire 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 axle-tree of the Magnet, is a line that passeth from the one Pole to the other, by the centre of the body of the Loadstone, and after this order there is an Axis▪ understood to be in the Earth, Tab. III. Fig. 1. 2. 3. & 9 10. In fashioning of Magnets, if a piece be taken away parallel from the Axis, then in these two Lodestones the Axis with his poles will be removed into the midst of the stone, as Tab. III. Fig 3. a b, the Axis in either piece is in the midst of the stone, so whether that bunches be taken away from the Loadstone, or any cavities filled, the Axis will always be placed in the midst of the most vigorous bulk of the Loadstone, as a b in every 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, upon the Axis, that the poles and Axis will be found in the midst of the bulks of the two pieces parallel to the old Axis, Tab. III. Fig. 3. and the poles of the lesser piece will be altered. Also when as a side of the Loadstone shall be made flat and parallel to his Axis, that side will attract, hold and unite unto him long pieces of iron sidelings and paralelly, Tab. III. as Fig. 4. c the piece of iron is adjoined paralelly to a b the Axis, as the pole erecteth perpendicularly to it, Tab. III. Fig. ●. the weight c is attracted plim-wise to the Axis a b. And also two Magnets somewhat long, in form swimming in their vessels upon the water, will adhere and unite in a meridian parallel to their Axis, Tab. XI. Fig. 5. that if one of their vessels be haled, the other vessel with the other Magnet his loading will follow, both being fast grappled together, so that they cannot part asunder. Likewise, take two Magnets, that be armed with their teeth of iron or steel, descending from these poles at right angles to the Axis, to take up, with both teeth together, & have their Axis both of one length, as Tab. III. Fig. 12. place the teeth descending from the South-pole, unto the teeth that have the vigour from the North-pole, and they will cleave and unite together as one body and Loadstone paralell-wise to the Axis, and the one, though he be the weaker, will lift up the heavier perpendicularly. Also all Magnetical bodies, whether it be at the aequator, at the poles, or at any intermedial part, between these two, do all of them apply, conform, and unite their bodies together, according to a correspondency of their Axis, as shall be declared hereafter, and not with their centre to the centre of the others body. If a wire be touched Magnetically at one end, the vigour will run through all the wire, or Axis, and have a contrary virtue in the other end, the one North, the other South, and half the Axis will be of one nature, and half on another, Tab. III. Fig. 5. the end of the wire at a is of the nature of the North-pole, and the end at b is of the South-pole. We said in the FOUR chapter, that the Moon doth always turn one Pole of her body toward the centre of the Earth, and moveth nearer & further from the same, as if that a long axle-tree were passed through her body, & fastened in a joint to the centre of the earth, on which she should make her Epigeum and Peregeum; in like manner, it is to be probably gathered, that the earth may naturally have a helical & spiral virtue to move on the cylinder of her Axis in spiral lines, not unlike the arches of the longitude of the day, to perform the zodiacal motion, partly illustrated in the XXII. chapter by the bead, in an instrument of rings for the finding of the variation, where the bead, as an earth, is placed in the Axis, higher and lower, according to zodiacal direction, and Magnetical virtue will permit this spiral motion, like as the sap passeth in the earth from the North hemisphere, to the South province. It is a thing worthy of better observation from the Truncke-glasse, to know whether the Axis of jupiter and the Sun be parallel one to the other, and with the Axis of the Earth, which is to be examined by the turning of the spots about. CHAP. VIII. Of the Aequator. IN all Magnetical bodies there is an Aequator, or middle fence, that divideth the whole body in the midst between the two Poles, like a middrift, into two equal parts, hemispheres, and provinces: outwardly in the middle part in the greatest circumference from the poles, there is an Aequator, circle, or line, that divideth the North-part of the stone from the South part, as by a border-marke, so that if a directory-needle touched Magnetically, be conveyed to any part between this Aequator and the poles, presently the end of the needle that is of the nature of the other province beyond the line of the Aequator, will turn about from that part, and the other end of the needle that hath affinity and natural conformity with the pole of that province, will offer itself, as Tab. III. Fig. 6. 7. 9 10. in the province of the North-pole a above the Aequator and pricked line, the bearded end of the needle doth only offer itself, and desire to apply and unite to that part, but the cross end of the needle will fly from it; so this cross end of the needle will only affect to behold the south province under the Aequators pricked line to the pole b, and the bearded end of the needle will shift away. This assertion is not only found to be true in the Loadstone, but also in other forms of iron and steel, and in the great Earth itself. As take a round plate of iron that hath lain some time quietly without stirring, as Tab. III. Fig. 6. or a ring of iron, Tab. III. Fig. 7. and offer the sides of this plate, or ring, unto the needle, turning them about, and the bearded point of the needle will respect the one half of these iron circles, and the cross part of the needle, being of the nature of the other semicircle, will apply and have respect thereto. Here in these iron forms the Aequator and limit of the two semicircles, is better perceived where it should be marked, than the poles are: for when the Magnetical needle is once past the bounds of the Aequator, presently he turneth about his other point that respecteth the contrary semicircle, or rather hemisphere, the which for distinction sake might be painted of a red colour. Moreover, if a directory-needle, or Mariners compass be placed near the Aequator of a Loadstone, of these iron forms, or of the earth, they will situate themselves parallel to the axis of the poles, as Tab. III. Fig. 6. 7. and Tab. VI Fig. 1. Tab. VII. Fig. 1. 2. and incline neither to one pole, or the other, being placed in a right sphere, where the poles lie in the Horizon, the needles standing in equal balance with the Horizon, looking North and South, parallel to the axis. Whereas it hath been declared in the VI Chapters before of the vigour of the poles, that the vigour and strength Magnetical proceedeth by little and little from the Aequator to the poles, increasing in their passage by the meridians unto the poles, to the end to augment their virtue of retaining, & consisting most firmly and constantly in the North and South, whereby the Aequator of the earth is left void of all virtue of consistence, and left free, or rather deprived of constancy and retaining of any firm situation, and remaining naturally, by reason of his great circumference and weak renitency, most apt and prone for circular motion, which by her star like vigour and intelligence, having this her globous body so firmly fastened naturally in her poles, as it were in two strong pillars, and fitted in the Aequator and parallels, as in Chariot-wheels: for circumvolution turneth herself daily about from the West into the East, to meet with, and receive the pleasant beams and influences of the Sun, Stars, and Planets, for to cherish, comfort, and invigor all those goodly creatures that be placed upon her, grow out of her, or be bred and conceived in her, as also for the continual change and vicissitude of seasons, being a thing more natural and fit that the earth should thus move for her own good, then that all the heavens should furiously move to serve her. It is to be observed in fashioning of the Magnet stone, that when the axis of the same shall be cut shorter, that then the Aequator removeth necessarily to the midst of the body of the Loadstone, as if a long Magnet should be sawn and divided into two pieces, as Tab III. Fig. 8. upon, or parallel to the Aequator, the poles will be in the midst of the stones, and the Aequator will also be in the midst of either stone, as a b, and the pricked lines be. For every piece and part of a Loadstone hath his poles and Aequator, with the rest of the circles, as well, and as naturally as the earth, or any great Magnet hath, and will be divided into two jurisdictions by his Aequator though before all his part was but of one province and nature. Even so if you part a needle, or long, wire Magnetically touched, in two pieces, the parts will have their several poles, as Tab. III. Fig. 5. the poles a b are in either part of the wire. CHAP. IX. Of the Meridian's. THe Meridian's be great circles drawn by the aequator upon the Loadstone, or as may be observed by the needle upon the face of the Earth, from the one pole to the other, where they do all touch, as in the centres, Tab. III. Fig. 9 they be naturally in every Loadstone, and in the earth, and are thus found out: for they be the paths whereon all Magnetical motions are traversed and directed. Lay a wire of a reasonable length upon the Magnet, as Fig. 9 a b, and it will turn and seat itself upon a Meridian, and point to the poles, and if he be moved from the Meridian by any force, he will soon return to the same again, and by this wire you may mark out a Meridian; Likewise take a little directory-needle of a small dial, and set it upon a small pin with a foot, setting them upon the Terrella, Semiterrella, or any Magnet, Tab. III. Fig. 9 and the needle will point towards the pole, make a mark, removing the needle forward, and make more, then join all the points together, which make a part of a Meridian, and being continued forward run to the pole, so a small and short wire placed upon the Magnet from place to place between the aequator, and the pole, will stick fast at one end, and erect the other obliquely, and the several places, being noted with chalk or emery, will set out a Meridian to the pole, at the aequator, being no longer than a barley corn, will lie flat to the stone, put him forwards toward the pole, and then he will erect himself a little, sticking at the other end upon your Terrella, Semiterrella, or Magnet, put him more forward, and he will be erected less acutely, and about 34 degrees from the aequator, he will make a right angle with the axis of the Magnet, and being brought and placed upon the pole, standeth upright in one continued axis, with the axis of the Loadstone, Tab. III. Fig. 9 This variety of application to the Magnet, doth produce a certain kind of motion Magnetical, which may be called the motion of inclination, conversion, or conformity of one Magnetical body unto another; but the little directory-needle demonstrateth this motion best, being carried about the Terrella and Semiterrella, as shall be demonstrated in the XII. Chapter following. I have, spoken before somewhat as concerning the making flat of a side of the Loadstone, parallel to the axis, which is a Meridian line parallel thereto, whereby weight may be apprehended, Tab. III. Fig. 4. Therefore having a Magnet stone first made flat at the ends, where the poles are, and after a side made plain and strait, parallel to the axis for a Meridian, than you may form the stone into what fashion you please, as into a foursquare, into a figure of 5, 6, or 8 equal angles or sides, or into unequal sides, as hath been thewed in the first Table in many types. Cut a part from a Magnet stone meridionally, and that end which was placed South when it was whole, being severed, will turn North, though naturally at first it was the South point, as in Tab. III. Fig. 3. the poles a b in the little piece are turned contrary to the poles a b in the greater Magnet. CHAP. X. Of the Parallels. THe Parallels be circles and parts equidistant from the pole, and Parallel to the aequator, and do possess the whole space between the aequator and the pole, as Tab. III. Fig. 10. these circles are pricked out, as the aequator is, and are found by the Inclinatory-needle, being carried at one angle about the Terrella, and in all these places the small wires, Tab. III. Fig. 9 and directory-needles, Tab. III. Fig. 10 do apply their axis or line of length obliquely to the axis of the body of the Magnet a b, or of the earth. For to find out these obliqne angles in every Parallel, and what correspondency they have unto them, there be diverse operations, diagrams, instruments, and calculations found out to demonstrate, and to know what angle of inclination will answer to every Parallel: for in every Parallel of the earth the Inclinatory-needle maketh a diverse angle of inclination to the axis, but one angle, and of one sort, in one and the same elevation of the pole or Parallel, and by this means of the Inclinatory-needle in a ring, the latitude of the pole is known on both sides of the equinoctial, without any sight of the Sun and stars, by the Magnetical disposition from the earth. If in forming of the Loadstone, some Parallels be cut away, as it should seem in the Terrella, by cutting and flatting the end where the pole is, Tab. III. Fig. 11. yet in truth they remain still upon the Magnet, though the Meridian lines be changed from crooked lines to strait lines, and this is to be observed, that always the Parallel near 34 degrees in the perfect Terrella, Semiterrella, and round Meridian, or strait Meridian, where the directory-needle aspecteth, that edge, or angle, at right angles, unto the axis, Tab. III. Fig. 11. and Tab. VII. Fig. 2. as the most protuberant and middle place between the pole and the aequator, as in this Loadstone truncated and flatted at the pole. In the Parallels of like distance from the pole, all Magnetical bodies do apply and conform alike, and have the like inclinations of their axis, that denotate like elevations of the pole, and do attract and retain with like forces and virtue, Tab. III. Fig. 11. Place two wires upon a Parallel of the stone, as you would say East and West, and they will not conjoin or unite together, Tab. III. Fig. 11. Rub the needle of a dial Paralell-wise on the Loadstone, and it will hardly be excited and animated, unless the touching be nearer unto the pole. CHAP. XI. Of the Horizon. THe Aequator, the Meridian's, the Parallels, the Poles and Axis, are all naturally in the Globe of the Earth, and in every Magnetical body, and not imaginary in the heavens, as Astronomers heretofore have thought, not knowing in what body to find them naturally. Now it remaineth to write of the Horizon, which is a great circle that divideth the Globe of the Earth into two hemispheres, or into two equal parts, like as the aequator doth divide the Magnet into two provinces, and though that the Horizon be of great use in Magnetical practices; yet I cannot affirm that the Horizon is naturally in the Earth, or any other Magnetical body, as the aequator is, only every point and place upon any meridian and parallel may be the centre of the horizontal circle, which centre is Magnetical, and of many uses in Magnetical demonstrations, both to know on what parallel and elevation of the pole, above the Horizon the inclination and conformation of the Inclinatory-needle is observed, whereby we come to the knowledge of the angle that inclinatory maketh with the Horizon, in every parallel of the earth, and by a respondency that it hath with the axis of the elevation of the pole we come to know, as hath been said, the latitude of the pole in all places of the world, without the usual help of the celestial bodies, having as certain an help from the materials of the Globe of the Earth, and their vigour for this conclusion, as from any other globe whatsoever. This centre of the Horizon also is the place whereon the Pilot placeth his Compass, and composeth the same levelly and parallelly to the circle of the Horizon, so that by the firm direction of the Lily of the Compass to the North, he knoweth which way to steer his ship to the desired port. The Horizon therefore of use is a plain and parallel superficies unto the horizontal circle itself, and is to be divided into 360 parts, from which lines are to be drawn to the centre of this horizontal circle, and may be called the lines of position, verticals, and Azimuth, whereof one of them is of principal note, and is called the Magnetical meridian line, from whence the rest are to be numbered, and by which we are helped to know the declination of the Mariners Compass from the true meridian of the world, which thing is commonly called the variation of the Compass. For although that naturally the directory and Magnetical needle, or Compass, should place itself upon the true meridian, by the disponent virtue of the Magnetical globe of the Earth, yet by reason of the neighbourhood and approaching of other eminent, forcible, and great Magnetical continents, this needle is turned awry from the true meridian and varieth, and declineth to the one side or the other, certain parts and degrees to be reckoned upon the horizontal circle. Whereas it is said by some, that the horizontal circles make always right angles with the axis of the earth, this assertion cannot always be true, but this circle of the Horizon maketh always a right angle with the meridian, whereon he standeth. CHAP. XII Of the two circles that the Needle maketh about the Magnet. Having explained before the nature of the poles, the axis, and the circles, and parts of the Magnet to be naturally in the same, and in the globe of the earth; Now it followeth that we demonstrate how the Magnetical needles and wires do conform themselves to the meridian of the round Magnet, whether it be a Terrella or Semiterrella. For this purpose it is very necessary to have these forms truly rounded, to be carried artificially upon a foot, and fitted within the head of the same, in a circular and hollow cavity, that may receive the stone, so that the two poles of the Magnet do lie level with the Horizon, leaving a thin ring of the foot about the stone, under which there is a shoulder, a quarter of an inch thick, left of the abatement of the height of the foot round about, to bear a round verge or limb of past-boord, brass, or silver, for a meridian or right circle, as is used to be done in the placing of all globes in their frame or foot, whereon may be made diverse situations of needles, and descriptions Magnetical, as Tab. FOUR Fig. 1. Tab: IIII diagrams The better to understand this foresaid demonstration, I would wish you to have in readiness a little directory-needle, with a foot flat and round, and a pin in the centre of it, to carry the needle, as in the third type of this FOUR Table. Let this circular foot be divided into four parts and quadrants, with lines crossing each other at right angles in the centre ●, where the pin that carrieth the needles, and at the beginning of every quadrant set these figures, at the first 1, at the second 2, the third 3, and the fourth 4, now in the limb, free from all needles, set down this needle with his foot at the aequator d, and the needle will seat itself parallel to the axis of the Magnet a b, then turn the foot of the needle about, that the diameter of the figures 1, 3, may be directly under the needle, thus in this site carry the foot and this diameter of the needle always parallel to the axis of the Magnet, and place it in m, where it will point over the figure 2, the beginning of the second quadrant having finished one quadrant of circumvolution about the foot or epicycle, then carry this foot with the needle with this diameter parallel to the axis, as before, and place it against a the pole, and the needle will point to 3 the figure of the foot: having finished half the epicycle of his foot, then remove the foot with the diameter 1, 3, parallel to the axis of the Magnet, and rest it at o in the rimme, and the needle will point at 4, having perambulated three quadrants, and then rest him at the aequator c, where he will point to the figure of 1, again, having finished a whole epicycle about his foot, in this journey about half the Magnet: so likewise if the needle be transported beyond the aequator to travel by the other pole b, to finish another epicycle, the point of the needle, that is of affinity with this jurisdiction, will offer his service, whereto place the figure of 1, to stand just under him at the aequator e, which here likewise will be situated parallel to the axis of the Magnet, and the foot being in this sort aequidistant-wise to the axis conveyed in the limb to p, the pole b to n, and lastly to the aequator d, again the needle in this hemispherical part of the body of the Magnet will describe another epicycle about the foot that carrieth him, so that it is most apparent that the needle in his circumambulation about the Magnet, doth turn himself twice about, and make two whole circles, or epicycles in this voyage, as hath been demonstrated. Whereas the needle in his progress from d the aequator to m is but almost 34 degrees from the same, in which space he maketh his first quadrant, but the way from m to the pole a, is almost twice as large, in which he maketh another quadrant, it is necessary that this circumvolution of the needle from the aequator d to m not 34 degrees, should be much more sudden and swift, being in so little a space of the quadrant d a, then that forming of a quadrant by the needle upon the epicycle of his foot when he passeth from m to the pole a, being a space almost as large again, and therefore the moving of the needle in making the second quadrant of his foot, should be almost twice as slow as the finishing of the first quadrant, if like time be allotted to both their passages. I thought good to set this needle and foot in the III. figure, upon the limb in the next Tab. V which will serve also for the demonstration in the chapter following. Yet it may be noted to the contrary hereof, the case being altered, that if there were a cutting away made of part of the parallels about the pole, and that the pole were made flat and plain, as it hath been showed Tab. III. Fig. 11. that then the application of the needle at right angles, to the axis, at the angle and edge of the Magnet, being the most protuberant place, and the needle would describe but one quadrant from the aequator to this angle, and the other quadrant of the needle's conversion, between this angle and the pole, would be on the flatted end; and then in this truncated body, the motion from the aequator to the angle, for the first quadrant would be very slow, and the motion for the second quadrant would prove far swifter. Now for Magnetical attraction and apprehension, it is to be observed, that at the poles the Loadstone doth attract and retain Magnetical bodies perpendicularly and most strongly, and at other places most weakly and obliquely, and nearer the pole more strongly. But where the poles be flatted, as is said, and the application at right angles, there the erection of weights is altogether as strong as at the poles, taking up in paralell-sort unto the axis of the Loadstone by two teeth, and at right angles by one tooth. Lastly, for the use of the application of the Inclinatory-needle, I have set down a second figure, and in the margin have delineated out in pricked lines, what application the needle hath, and maketh in every tenth degree of the quadrant, from the aequator to the pole in the limb of the quadrant C B, as likewise in the quadrant D A, there is set forth how the small wire and short erecteth itself in every tenth degree in that quadrant, a thing hereafter more plainly demonstrated by a diagramme in the XXXVI. chapter, by calculation, and by ring, but indeed the matter will be more naturally and truly demonstrated in the chapter following. CHAP. XIII. Of one circle the Needle maketh round about the Magnet. EVen as in a semicircle if sights be applied Euc. 3. Prop. 2 ● to the diameter, and a plim line fastened to one end of the diameter, this semicircle will serve only for the use of one quadrant, though it have two quadrants contained in it, so this Chapter will abbreviate the motion of the needle in the former Chapter, as the quadrant doth the semicircle that in the former Chapter described two circles about the Magnet, and show a way and device how the needle, being always carried about the Magnet, shall make but one circomuolution about the circle of his foot, although before he made two circles about it, and this demonstration is of most necessary use for to find out the angles of the Inclinatory-needle, with the axis of the Earth in every elevation of the pole, and what they are from the Horizon, and knowing what number of degrees they include in any place, the altitude of the pole in the same place shall be accordingly known. Tab●. ● diagram In the Terrella or Semiterrella let the poles be A for the North, and B for the South, and the aequator C D, part the semicircle A D B into two quadrants at D, then make other semicircles in the verge without A D B for the degrees and figures in each quadrant, as is used to be done in other quadrants, then divide each quadrant, and every one of these into three other parts, then divide these parts into smaller parts, and if the circle be big enough, divide these last into five parts a piece, and thus have you either quadrant divided into ninety parts, than set the usual numbers of ten at every tenth part to ninety, ending at D, as in this type, Tab. V Fig. I. Then about a quarter of an inch above c in the verge, draw a line at I, at right angles to C D, and from I as a centre describe upward a semicircle to touch that line F I G, divide this semicircle into two parts and quadrants at H, joining I H together in one line, after draw other semicircles within the semicircle F H G for the degrees and other numbers, as you did in the former quadrants, then divide each of these quadrants into 90 parts, beginning the divisions at F G, and ending at 90 in H, then set the figures at every tenth degree, as is used to be done. Lastly, upon this centre I, place the Magnetical needle upon his pin, Tab. II. Fig. 20, that is, the needle that is thick and short, having at the one end an hole drilled, for to receive a wire of brass or silver, to counterpoise the thick head of the needle, and to reach unto the farthest circle of the divisions of the two quadrants of this semicircle: this needle and semicircle would be covered with some glass and slude, as dials use to be covered, for a little air and the breath of your mouth, when you look near to see what divisions the tail of the needle cutteth, will move the needle and drive it away. This limb and verge thus furnished with these two semicircles, and this needle being placed about the Terrella or Semiterrella, so as it may very easily without any great force be turned about; in this situation of the needle, as it is in the type, the needle seethe itself at the aequator C, parallel to the axis of the stone A B; we will call the inner semicircle of the limb A D B, that is next to the Terrella or Semiterrella, the meridian circle of the altitude of the pole; the outward external semicircle F H G, we will term the meridian Inclinatory semicircle, because the needle Inclinatory doth show in these quadrants certain parts and degrees, answerable to every degree of the elevation of the pole, of the Terrella, or Semiterrella, declared in the inner quadrants of altitudes of the pole. For practise hereof, if it be desired to know where the pole is elevated ten degrees above the Horizon, what degrees the Inclinatory-needle will point at in the Inclinatory meridian semicircle answerable thereunto. Here turn about the limb and verge, until ten degrees of the semicircle of altitude be placed just with the pole A, the pole being elevated so many degrees above the Horizon, then look in the quadrant of the meridian inclinatory semicircle, and his needle will point to 20 degrees, the very true parts, the Inclinatory-needle being placed in his ring and meridian circle, hereafter to be described, will point at in traveling where the pole is elevated ten degrees, after this manner seek out what will be correspondent where the latitude of the pole shall be 20 or 30 degrees, and this needle will point out the correspondent degrees of the angle of inclination in the meridian-inclinatory semicircle, to these or any elevation that shallbe desired. Therefore here you see how profitable, and of what great use this demonstration is, in helping to attain to the reason & true knowledge of the Inclinatory-needle, which placed in his ring, and carried about the earth in the meridian, doth only show his angle and inclination to the axis, but this demonstration directeth from the stone itself what will be the number of degrees that the angle of the inclination maketh above the horizon, and what degree of the elevation of the pole will be answerable thereto, and from hence Tables may be made and collected what degrees of the Inclinatory-needle willbe answerable to every elevation of the pole. CHAP. XIIII. Of the distance and Orb of the Magnets virtue. Tab. VI diagram Place wires, about an inch in length, within their length in the orb of a good Magnet, and they will skip unto the Magnet, as though they were quick, and will unite and adhere fast unto it, until they be taken off. The celerity of motions, attractions, and conformities within the Magnetical orb is according to the goodness of the Loadstone, the greatness of his bulk, conveniency of his figure and smoothness, and in the shortness of the distance in the air, or in water; yet further than in these the Loadstone extendeth his virtue by contaction and continuation in a long wire set unto his pole, which wire will move a needle, or adhere to another wire at the end of his length; but this is done by augmentation of the Lodestones vigour, as shall be declared. Although that such substances, which be not Magnetical, be placed between the needle and Loadstone, yet they cannot hinder the orb and proceeding of the Magnetical vigour, as if a Loadstone should be enclosed in a box of wood, stone, tin, silver, or brass, yet the Loadstone will extend his Magnetical orb, wherein many pretty and ingenious Magnetical practices may be wrought admirable to behold, as having the forms and protractors of creeping things, beasts, footmen, horsemen, and flies drawn in past-boord, having but a short wire closely conveyed into them, and placed upon a trencher, paper, or plate, shall be caused to move, stir, pass on, and flicker, as though they were alive, only by moving the pole of a good Magnet directly under them. Also if a Magnet be fastened in the roof, or over a door, it will hold an iron weight in the air, Tab. VI Fig. 2. that hath a thread fastened to it to hold it short that it be not drawn close for to be united unto the Loadstone. Likewise if a short piece of iron, or cap, be held within an inch of a strong Magnet stone, Tab. VI Fi. 3. it will take up great weights in this orb, though not so much, as if it touched the stone and pole: but if the cap be held over the pole, it will hold a weight up rather then the pole, Tab. VI Fig. 6. I hold it needless to demonstrate how all the needles of dials, Magnetical instruments, the Mariners compass, and inclinatoryring do all of them move within the orb of the Magnetical vigour of the earth, only I will show you a pretty practice or two for delight. Get a wire of four or five inches in length, and thrust it through a cork, than it being touched with the Loadstone, place it in a basin of water, and it will move and direct itself North and South, by the vigorous orb of the earth, Tab. VI Fig. 4. and also incline and conform a convenient angle with the Horizon and axis of the earth. This practice is profitable for travelers, who having sowing needles touched, may prick them upon any piece of wood, and place them in the water, and it will set out the North and South instead of a compass: but if for pleasure-sake you take another wire, thrust through a round cork, and let his upper end be touched at the contrary pole, and placed in the basin of water, these two after some time will take knowledge of each other, and will begin to move and stir, and draw nearer and nearer together, Tab. VI Fig. 5. and coming near, will move the faster, and suddenly join together at the upper ends, on these wires paper-tilters on horsbacke might be fastened, and they would run their course together upon corks in the water, etc. CHAP. XV. Of Applications. Tab VII diagram Take a long Magnet that hath the poles in the midst, Tab. VII. Fig. 1. as A B and the aequator C D, the needles placed in the midst, apply directly upon the axis, and at the ends, and at the other places obliquely. The second stone is a long Magnet, that hath his poles A B in the ends, and the aequator C D in the midst, Tab. VII. Fig. 2. here the needle against the aequator standeth at right angles unto it, and parallel unto the axis, but at the either end of the Loadstone the needles apply themselves at right angles to the axis, and parallel to the aequator, and in the intermiddle spaces the needles apply obliquely to the Magnet. Now I would have you to provide two long Lodestones, that have the poles in the midst, like that Tab. VII. Fi. 1. and before him place three Magnetical needles, two at the ends, and one against the midst, or pole, as in Tab. VIII. Fig. 1. the middle needle will behold the pole, and the other will apply obliquely, as before in Table VII. Fig. 1. now bring near the second Loadstone, that hath his poles in the midst, and place B the South-pole toward the needles that behold the South-pole B of the first stone, and these needles will, between these two Southpoles, respect neither pole of these two stones, but seat themselves parallel to both stones, and make right angles with these two poles of one nature, as Tab. VIII. Fig. 1. Now take away one of these stones, and after turn the North-pole A, towards the needles that behold the South-pole B of the other stone, and they will all of them situate themselves equidistant-wise, and at right angles to the aequators of both stones, as Table VIII. Fig. 2. Tab: VIII diagram Moreover, 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 parallel to the axis of the stone, and those two at the ends will seat themselves 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 themselves in a strait line parallel 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, & turn 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 parallel one unto another, and to the aequator. This is to be observed in these applications, that the nearer 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 approaching they will vary, by little and little, from their first situation, until the virtue of the two Lodestones be equal in their orb. It may be imagined that these applications, for the most part, should be found naturally upon the earth in traveling or navigating between two great islands or high Magnetical 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 near two Magnets, or a Magnet and Magnetical body, as place a needle on a little foot upon the Terrella, Semiterrella, or Loadstone, and it will direct itself rightly upon the meridian of the stone, as hath been proved before, Tab. III. Fig. 9 but if you hold a little piece of iron toward the point of the needle, the point will fly from the iron, and deflect from his meridian a little. Yet let this piece of iron touch the Loadstone and be united unto it, and put it towards the needle a far off, and the needle will turn from his meridian, and decline and vary towards it, the contrary is to be said, if this iron be put towards the tail of the needle. Now take two long Magnets, that have their poles in the end, and place a needle before the aequator of one of them, and it will apply parallel 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 seat itself at right angles, to the axis of both Magnets. So also take two Lodestones, and let one of them have the poles in the midst, and the other in the ends, and you shall behold much artificial variety of the application of one needle unto them. Place a needle before the midst of the Loadstone, that hath his poles in the midst, and it will behold the pole: after lay down 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 parallel to the aequator of the former Magnet, whose pole he beheld before, as Table VIII. Fig. 6. Tab. IX diagram Set a needle against the end of the Loadstone, that hath his poles in the ends, and it will rest itself at right angles to the axis, then apply the second Magnet to the needle that hath his poles in the midst, Tab. IX. Fig. 2. and the situation of the needle will be altered to be parallel to the axis he beheld at right angles at first. Place at the corner of that stone that hath the pole B in the midst, 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 midst, 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 seen in the type in a strait line to the last, and parallel to the axis of the first. Also apply the aequator of this second stone, that hath the poles in the ends unto the needle, placed as afore, unto the first stone, Table X. Figure 2. and the needle will be parallel 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 diagram CHAP. XVI. Of preserving the virtue of Magnets. Having treated of the parts of the Magnetical bodies, of their motions, and applications, now we will speak of his other natural virtues and properties. Some have thought it very convenient to keep the Lodestones in filings of steel and iron, to preserve their virtue and vigour, thinking that the Magnet is fed, or, at least, very much refreshed with them, because they will cleave so fast to the sides near the pole; But I do not allow this way so good to preserve them, rather I like the keeping of them in a bag, or clout of woollin-cloth, close from the injury of the heat and cold of the weather, or in a case or box fit for them, and it is very necessary to wipe them often from dust and grease, and to have a care that they do not rust. Also it is very commodious and natural for them that they be laid up, and placed according to that natural situation the which they would affect and respect, if they were carried in a place and fashion free from renitency and resistance in the air or water; therefore they would be laid up, or hung accordingly as their poles and points do particularly respect, to the North and South, which will comfort them exceedingly. Besides, if the Loadstone be sometimes polished, it will strengthen and relieve the body of the Magnet very much. If a weak Magnet be rubbed at one of his poles with a stronger Loadstone, he will be bettered by it in his vigour and virtue, if not augmented therein. Set a Magnet of no force or strength, that can easily be perceived, upon a Loadstone of good strength and vigour, especially upon his poles, and he will show a vigour, as if he were as strong as the Loadstone is, whereunto he is united, but after that he is taken away, he will be as weak as before, unless it be often done. CHAP. XVII Of contributing the virtue Magnetical to Iron or Steel. THe iron bars in windows, being there placed North and South, do receive a polar virtue, and directory faculty in time from the vigour of the orb of the Magnetical globe of the earth, and having marked them with notes to know which end was South, & which North in the window, take them out and tie a third about the midst of them, that they may hang levelly in the air, and the end with the South note will turn itself 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 piece of iron be forged North and South, and laid by to cool in the same situation, he will be animated and endued with a polar virtue, and move in the air, being hung in a third, or put in a boat on the water, and turn to the contrary pole to that from which he first received the Magnetical vigour. If a rod of iron, a wire, or directory-needle, be overheat in the fire, so that they have lost all Magnetical vigour 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 province and nature, and being placed according to Magnetical orders, will direct their points to the North & South, contrary to the pole that animated them with this virtue polar. Also take rods of iron, wires, and Magnetical needles, that have never been touched with the Loadstone, and rub them upon 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 virtue at both ends, both of the North and Southpoles, as though they had a new life of quickness infused into them, and these shall refresh other needles that shall be touched with them, and apprehend and draw them away like captives, and will not let them loose from them, unless by force you sever them. The best way to touch, incite, and give the polar directory and Magnetical vigour and faculty unto needles & Mariners compasses, is to rub them from the midst of the needle where the aequator of their axis is unto their points upon the pole, cap, or tooth of the Loadstone, drawing them thus from their middle to the ends, upon the cap, pole, or parallel near the same, unto the axis, or at right angles to it, them after draw the other end upon the other pole, cap, or tooth, diverse times, as afore, and these needles, wires, and plates for compasses, shall be perfectly touched and vigorated. In long Lodestones that have the poles in the ends, if a wire be drawn parallel 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 virtue will be given as well from a parallel some distance from the pole, as from the pole itself, it is plain, that from those parallels and parts, near adjoining to the pole, the greatest vigour of polity Magnetical doth proceed, yet in parallels, nearer the aequator, it will be given likewise, & the virtue directory will be very sufficient. If you touch the needle amongst the parallels, it is the best way to rub the needles alongst the meridians towards the pole, rather than to rub the cross the meridians, in a parallel manner, yet this way will give the polar and Magnetical virtue also. Some have thought it better to touch compasses, and Magnetical needles, rather on the Loadstone then upon their caps, thinking that the vigour and faculty Magnetical will continue longest that is given from the bare Magnet stone, the truth is to be observed in time. Yet the cap and tooth giveth and imparteth a stronger vigour to the needles than the bare stone doth, because the virtue of the Loadstone is increased as much by the armour and cap as if his bulk simply were tripled. Needles and wires of steel, heated to an height, and reduced back to a bluish colour, will receive a stronger touch, and retain it ten times longer than iron will, howsoever he be hardened, yet iron is best for caps placed near the stone. That end of the needle, whether directory or inclinatory, which is to be touched, aught to be somewhat lighter than the other, especially for the North, and most vigorous touch end of the stone, because that the touching will sway down a little, and the needle hath two motions, one of direction, the other of inclination, and then the needles and compasses will play more level and aequidistant to the horizon for the said uses. When any Magnetical needle or wire 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 severed out of the orb of the Adamant, it will be directed into the South by the Magnetical virtue 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 have the virtue of the South-pole, & the North-pole will be in the opposite part, and being severed from the Magnet, it will not turn to the contrary part, as it falleth out in long Magnetical 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 strait wire, than both ends will have the vigour of one pole only. Excite a directory needle at both ends from one pole, and they will both be of one nature, and look what point was last touched, and that will turn, as if he only were touched, and direct more surely, with less wavering too and fro, than the other touchings will, spoken of before. Let a long piece of clay newly burnt, cool North and South, and it will receive power Magnetical from the earth. Set two Lodestones with their poles of one denomination, at the ends of a piece of clay whilst it cooleth, and both ends will be of one nature. If a long wire be touched in the midst by the Loadstone, and passed through a cork, and set for to swim in the water, it will waver up and down uncertainly, as though it were not touched: but if it chance to rest itself towards the pole, in time it will be endued with his virtue. Set a piece of iron upon a Loadstone, as you did a weak Magnet in the end of the former chapter, and it will have a great force, but take it away from the stone, and almost all the vigour will be departed. CHAP. XVIII. Of augmenting the virtue of the Magnet. THere is a means found out whereby the Loadstones that will take and lift up a very small weight, may by being armed with a corselet and teeth, be enabled to take up more ounces with his armour, than he could, being naked and unarmed, lift up scruples and grains. The first way is by fashioning caps of iron or steel to either pole, as hath been described, Tab. I. in the second Chapter, whereby the Magnet will lift up a great weight of Iron at one end perpendicularly to the axis, and after, if you turn the other end to the weight, it will by his force lift up the same weight also, if the stone be good and of equal substance and fashion. This way or arming is most usual, for those Lodestones that be of a long oval form where at the poles there is fitted and placed two concave pieces of steel, which are fastened and held close to the same by three or four long narrow plates of silver or brass, not unlike to that order which is used in tipping of cups with silver, that be of Ostridge-egges, Indian-Nuts, Mace-wood, and Stone, which from the bottom to the verges and edging, have silver plates for to hold the edging and bottom together: some trim their Loadstones all over with silver, and gild both the silver and the armour, joining altogether with pretty joints, as in a case to open and shut. There is another way of capping and arming of Loadstones when they have a side parallel to the axis, made strait, plain, and flat, and the pole rounded or flatted in the end, such as are the Semiterrella, or half oval form. Tab. I. Fig. 2. 4. and of many angles, as in the types of the first Table, all these forms may have 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 caps to have two square forms of Steel or Iron, like unto teeth, a little descending lower then the bottom of the stone, of bignsse and length, as the bulk of the Magnet shall permit, these teeth because that they do descend at right angles from the poles, will jointly take up 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 up as much as any cap doth directly, and in one axis from the pole, the weights for this form, aught to have the heads of their weights, like an headless cross, as is described, Tab. II. Fig. 2. 3. 4. Hear observe what weight one of these teeth will elevate ●n the air, for both teeth jointly lifting and holding one weight together, will take up from the ground four times as much in weight. There be some Magnets that will take up with two teeth, six times as much as one tooth shall, and one I have seen that will take up twelve times as much with both teeth, as he will do with one tooth, these teeth are to be fastened to the stone, with plates of silver or brass, by the skilful workman. Such Magnets as be made plain at both ends, having the axis in the midst of the stone, Tab. I. Fig. 5. 6. 12. may have their armour with teeth on both sides, two teeth on the one side and two on the other, these will take and lift up with like strength on both sides. Moreover, the virtue of the Loadstone may be further augmented, by increasing the number of teeth and shaping them so, as that they may take hold with four or five teeth, as Tab. I. Fig. 7. and Tab. XII. Fig. 11. where the poles being in the ends of the stone, and have had two teeth descending on either side, now the sides be turned, and these are also turned, in form of a Greek 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉, and the stone hath his force multiplied and is made to take up with four teeth, having 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 up with five teeth, as it were a hand with five fingers, must have the pole in the midst of the stone, which being made, the bottom must have his cap, for this part, to have three teeth, like a Slavonian 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉, as Ta. XII. Fi. 12. and the other cap from the top must descend with two teeth like a Greek 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉, as in the type. There is a way to cap the Loadstone, so that it shall take up with eight teeth, using four at one time, and four at another, the stone would have two broad sides where the poles are, and the teeth would be in form like a Roman X. or S. Andrew's cross the centre hereof would be placed on the pole, and the teeth artificially fastened. If there be two Loadstones that be 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 unite and adhere together, and if they continue thus some time, the weaker will lift up a better weight. CHAP. XIX. Of the decay and decreasing of the Magnets virtue. THe vigour of the Loadstone is much diminished by the evil keeping of it, as when it is laid in the open air against the heat of the Sun, and subjecteth to cold, and all change of weather, or laid up, as some do, in a box with rusty filings of steel and iron, in a place near a pan of charcoal to keep it warm in winter. There is nothing that hurteth the Loadstone more than the fire doth, for if the Loadstone be burnt in the fire it will lose all his Magnetical virtue and strength, the which may be a little restored by touching a good Magnet, and how weak so ever he be, he will be a convenient Magnetical medium, to carry the extent of the Magnetical vigour to a farther orb. Aqua fortis will eat the Loadstone, and burn and mortify him, as he doth eat into Iron. The Magnetical Needle being touched and excited by the Loadstone will not pursue and point out the veins of such Iron as be very stony and full of dross, as not worthy the labour to be digged, because they have little Magnetical matter and Iron in them, and if that part of the Mine of Iron be beat and stamped into powder, the Magnet will take up very little of this dust, declaring the Mine to be nought, unless the Mine be heat. Crocus Martis will not be attracted by the Loadstone, because his Magnetical vigour is clean defaced and evaporated by the fire. If a Magnetical Needle, lately touched and invigorated by the Magnet, be heated red hot in the fire, he will lose all his potency polare, and directive faculty. It is also conveient to understand, that having touched and animated a Needle Magnetically, if contrary to this excited, the Needle be rubbed from the point to the midst upon the pole of a Magnet, cap, or tooth; so any long piece of Iron, or Steel else, as knife dagger, or sword, which before would have attracted and lifted up Magnetically, other Irons of some weight by being thus rubbed back again from the point to the midst, have that virtue taken away, which they received before from the Loadstone, and are as void of all virtue attractive, as they were before they touched the Magnet, so that they neither will adhere or lift up the least weight, which was nothing to that they would have done being excited. If two Magnetical bodies be joined together at their poles, these two poles that touch together, have the nature of the aequator, and will not then excite or hold a needle thus touching. An Adamant doth lose much of his strength, if he be diminished, and have any part of his body taken from him, especially if his figure was good before. Some have thought that certain forms of the Magnet, which may be allowed for convenient figures, do lessen the Magnetical vigour, chief in their attraction, as a spherical or plain superficies in the poles, of globes, and of square and angulous figures, but these full and obtuse superficies and flat forms at the poles do attract best with their caps, and lift up most, as hath been declared in the eighteen chapter before, for this vigour proceedeth from the substance of the Adamant, better than in long and piked forms, which have very little substance left about the poles, yet this assertion is partly true in such like forms 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, likewise a long plate, or square piece of Iron or Steel, Tab. II. Fig. 9 17. applied to the two teeth of the Loadstone, doth deform the figure of the body and deprave his virtue. CHAP. XX. Of the Commutation of the virtue Polar. THe Polar virtue 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 Magnetical bodies; this thing is effected, in a weak Magnet, by placing him a long time by a Magnet that is stronger, unnaturally, which is done by adjoining the two North-poles, or the two Southpoles of the two Loadstones together a long time, where the strong Magnet, will by his neighbourhood take away that contrary nature of pollity that was in the weak Loadstone, and will make, and infuse into him that polar virtue, which doth naturally unite unto the pole of the strong Adamant, making that point and pole to be South which was North. This thing is not only experienced in two several Magnets lodging together in one chamber and box, but also if you shall agglutinate and cement divers Magnets of divers strengths together, they will all of them be conjoined and united together, as if it were one stone and body, and may be made and fashioned into a convenient figure, and will be endued with one vigour Magnetical of one province, though separated they were of divers polities and jurisdictions. Magnetical needles and long forms of iron, as knives, daggers, wires, and such like, if at one time they be touched and excited with the North-pole, and made of his nature in all operations Magnetical, than another time let these North points be touched, as is used to be done with the South-pole of the Loadstone, this end now hath lost his former nature, and is made of affinity and allegiance unto the South-pole, and after if you shall bestow upon him, by touching him again at the other pole, the virtue of the North-pole again, and then he will march under his banner, and look by which pole he is last touched and relieved, he will remain at his service always after and bear his badge. Put clay of a long form in the fire, after let him cool North and South, and it will receive a polar virtue: after burn it again in the fire, and let that end which cooled first North now cool South, and it will be commutated into the nature of the South, and the other North. Furthermore if a strong Loadstone be held somewhat near such compasses and needles, as have been excited and touched with the virtue 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 Lily of the Compasses will be clean turned, that that part and Lily that should always turn North, will either stand South, or else move up and down unperfectly, and weakly, having his first polar virtue changed for another, or else taken away. This conclusion maketh many afraid to let two Magnets come too near together, lest the one should rob the other, but this will not be effected presently in the Lodestones themselves, though that it be proved soon to come to pass in the Magnetical bodies of steel and iron. If a directory-needle be excited at both ends from one pole, it will have the virtue of that pole at both ends, but if both ends be rubbed back from the points to the midst, on the same pole, both ends will have the nature of the contrary pole, and if one end be passed from the point to the midst, that end will have the nature of the contrary pole, and the other end will keep 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 boats, in a basin of water, as Tab. XI. Fig. 5. 6. for if by force, their two North-poles or Southpoles be placed together, they will abhor the one the other, and part asunder by speedy flight. Tab XI diagrams When two Adamants shall comfort, and keep together, at their contrary poles, at the approaching of a third Magnet they will be separated and fly asunder Tab. XI. Fig. 1. because that the pole of their Adamant, that is offered unto them, is of the nature of the pole of one of the two Lodestones, which the stone of that denomination perceiving, flieth away from the company of the other, because two Southpoles and two North-poles, in divers Magnets, be at discord and war together, and cannot abide to dwell as neighbours together, but each of them, placed out of the others Orb, will both aspect the North, with their North-poles, and the South with their Southpoles, and thus two needles excited as Tab. XI. Fig. 2. will each of them, out of the others Orb, have respect to their proper pole, but if the needles be within the Orb one of the other as Tab. XI. Fig. 7. then they will move and adhere together at their contrary poles, but if a third Needle be brought near unto 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 unto it, and thus the first two Needles will aspect this third with their points of one denomination. But this discord is not found between the Adamant, and the Magnetical Needles that be excited and animated from one of his poles, for as long as the Needles be within the view and orb of the Adamants Magnetical orb, so long they will behold and aspect him with a certain dutiful conformity, application and respect unto his axis, as it hath been demonstrated in Globous & Angulous Magnets, but being severed out of the Adamantine Orb of the Loadstone, than they will fly, as from a foe, from that pole from whence they received their life and vigour Magnetical, and by the virtue of the earth conform themselves 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 have the virtue of the South-pole, and adhere to the North-pole of the Magnet, and being severed will keep the same situation in the water, contrary to all Needles that turn the touched part to the contrary pole, as afore. Set two short and slender wyars upon the pole of a Magnet, Tab. XI. Fig. 3. and they will adhere at the lower end unto the same, but whereas they should erect their other ends perpendicularly, those ends of the wires will decline a great distance asunder, unless by force they be united and joined together. Contrariwise it will fall out if these two short wires be fastened to two several thirds with wire, and hanged over the pole, then neither of their ends will behold the pole, but for the hatred that the one beareth to the other, they bear off asunder in a great distance, desiring rather that their upper ends, farthest from the, Loadstone should unite, then that they should do it. Hold a knife to the Needle of a Dial that is touched Magnetically, and the one point of the Needle will come to it and follow it, and if that the knife be offered to the other end of the Needle it will fly away from the knife, so one end of any wire, though untouched, will attract the Needle at one of the ends, and drive the other end away, Hereof more hath been written in the sixth Chapter. Some think that this quality of the poles, thus to fly off the one from the other, that it is no enmity, but proceedeth from a disponent virtue, to cause these Magnetical bodies to move and turn away, to the end that they may better frame and dispose themselves to a convenient and natural unition. CHAP. XXII. Of Magnetical Union. Magnetical union is when one Magnetical body naturally conformeth itself to unite unto any other Magnetical body, by convenient angles & positions, that is, the South-pole of the one Magnet will apply and unite unto the North-pole of the other, as may be seen in Lodestones, carried in their boats upon the water, and in Magnetical Needles and Wires of Steel and Iron. If two Magnets, or two Needles do unite at convenient points, a third Magnet or Directory Needle will first separate one of them till he turn his contrary part, at the which he will unite with the third as Tab. XI. Fig. 1. 8. There is a strong union, of body to body, and a weak, the strong conjunction is three manner of ways. The first is commonly observed to be at the Poles, where one body Magnetical is conjoined and united unto the other in a right line, upon the axis at the pole Tab. XI. Fig. 10. The second strong union falleth out when the superficies where the pole is placed is made plain, where at the edges, Magnetical bodies adhere at right angles unto the axis, as Tab. III. Fig. ●●. and Ta. VII. Fi. 2. but more plainly, this strong union appeareth when as the Adamant shall be capped with two teeth at either pole, descending at right angles unto the axis, for here a tooth will lift up as much perpendicularly at right angles to the axis, as it will at the pole in a right line. Table XI. Figure 10. 11. The third strong union, and strongest, is when at a Meridian in the Loadstone there is a superficies made flat and plain, parallel unto 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 wires and weights, at the pole, hang and adhere unto it, but by one end only, here they will adhere alongst their axis, leaping more violently to adhere with their whole side and unite, than they will from their ends unto the poles, as Tab. III. Fig. 4. therefore the Adamant being armed artificially with two teeth, at right angles unto the axis, will in this paralel-conformity unto the axis, apprehend and lift up weights heavier by many times, than the caps at the poles will, Tab. XI. Fig. 12. because these receive their vigour from the forces sent out of both Provinces of the Magnet. The weaker unition of Magnetical bodies together is in the other parts of the Meridian's, where the conformity and applications of their bodies is obliqne to the axis, though that near the pole, the obliqne coition is stronger than it is by the aequator, notwithstanding, there is an obliqne coition, as strong as the strongest union, and will take up as great weights, as the parallel unition to the axis doth, and this is, as it were, a parallel coition also between the teeth and the head of the weight, yet obliqne to the axis of the body of the Magnet, as Tab. XI. Fig. 13. having his supplies of strength from all the Magnetical body of the stone. unition also, is either natural, half violent, or else depraved; the natural coition is when the union and conjoining of Magnetical bodies is by the contrary parts, as in Adamants, by the poles North to South, and in needles by head and tail, as Tab. XI. Fig. 7. Tab. XII. Fig. 5. 6. 9 so two wires swimming on their corks in the water, being touched by contrary poles, will march and hasten to salute one the other, like two lovers, Tab. VI Fig. 5. Likewise in Adamants that be armed with two teeth, it falleth out that they will embrace the one the other, only with the teeth and parts that be of contrary provinces, and not with those of like nature and province. Tab. III. Fig. 12. Tab. XII. Figure 10. Tab▪ XII diagrams Now that unition, which Magnetical needles touched and excited at the pole of the Adamant have, may be thought to be half violent and somewhat strange, Tab. III. Fig. 1. 6. 7. Tab. FOUR Fig. 1. because that here there is an affinity of two Magnetical bodies of the same nature and denomination, and not of the contrary, that it seemeth that the Magnetical nature, between the Adamant and the Iron, is both very different from all other Magnetical bodies and somewhat imperial; for it is not to be seen either in Magnets one towards the other, though they be of the same rock and piece, or in any wires of iron or steel of one towards the other, or in the earth itself, 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 conform itself, being artificially, without renitency, carried unto a pole of the same nature and denomination, from whence he received his first vigour. Here therefore, no doubt, the Adamant is Masculine unto his beloved the Iron and Steel, and these are Feminine, as more apt to obey, respect, and follow the Masculine, subject to be attracted by him, whose presence quickeneth, reviveth, and animateth them in all kind of vigour and commutation. Thirdly, when iron is untouched, and unexcited, the coition is the weaker, but when a small piece of Iron shall be in a boat, with materials of other lading to be united to a Magnet in his vessel, here the coition is depraved and weak, because the Magnet affecteth and draweth his own beloved best, when she is not laden or mixed with materials that be of different nature not Magnetical, and for this cause the Adamant will take up a greater weight, all of Iron or steel, then when a great weight of other subance, is fashioned to a small weight of iron or steel. The greatness of the bulk of the Adamant helpeth unition, so doth the length of the axis, and virtue disponent to set the Magnetical bodies in convenient situation. Besides, there is a virtue attractive, besides the disponent virtue, and a directive and inclinatory faculty in the Adamants, that bring Magnetical bodies to unition and apprehension, the two first retain them in union and conjunction, proceeding especially from the goodness of the stone, the latter two help the disponent virtue, and are to be found in all Lodestones, and in the earth itself. CHAP. XXIII. Of attraction Magnetical. Magnetical attraction is a natural incitation and disposition conforming to contiguity and union of one Magnetical body unto another, and no violent haling of the weaker to the stronger, being an appetite of unity proceeding from both bodies that are separated, as two Magnets floating in their boats do not at first run together, as it were, from centre to centre of the bulk upon a violent disposition or attraction, but the disponent virtue first worketh, than the allicient and Adamantive virtue in them, both for unition, doth show his vigour to join them by convenient terms the one body unto the other, Tab. XI. Fig. 5. 6. Also the Adamant doth more strongly attract iron, having a more Masculine nature to attract her, and enableth her, bestowing upon the iron, that he toucheth, a great quantity of his strength without any loss unto himself, so that she hath power to attract other iron strongly, which before the excitation from the Magnet she could not do, and therefore excited forms of iron and steel, are quicklier attracted, than such as are not touched, because they have more Magnetical vigour in them. Such Magnets as be armed with iron, attract more strongly than the bare stones do, because that hereby their vigour is increased, being more strong, and extendeth itself further, as if a long iron wire be conjoined 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 cleaving together, as linked in a chain. Place a wire somewhat short upon a Loadstone near the pole, or further off, and hold an iron or Magnetical body towards it, and the wire will rather be attracted away by this weaker body, and leave this strong Magnet, Tab. VI Fig. 6. and before the iron touch it, it will decline and bend towards the iron that approacheth, so will needle's directory deflect awry, being placed upon the Magnet, from their conformity to any untouched wire, and be attracted by them, and this proveth, that the eminent parts of the earth being Magnetical, may attract the Compass to vary from the true Meridian of the earth. The natural attraction of Magnetical bodies, is that the North-pole do attract the South-pole, and the South-pole the North, although between the Adamant and the iron there is that sociability, that the North-poles love one and the same pole. CHAP. XXIIII. Of the strong apprehension of Magnets THe apprehension of Magnetical bodies is a strong union, cleaving and sticking of them together, that they will hardly be severed, being strongly retained by the virtue and love Magnetical, as though they were tied, glued, and soudred together, this conjunction and agglutination is performed by certain convenient positions, whereof I have spoken in the XXII. chapter of union; according hereunto if two Magnets be swimming in their boats upon the water, within the orb and vigour Magnetical one of the other, they will move to conjoin 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, having the North-pole applied to the South-pole, for to lift the small Magnet in the air, but offer a wire of polished iron or steel, that is a good deal heavier than the fragment of the Magnet was, and the Loadstone will lift this up from the ground and retain it firmly, Tab. XII. Fig. 5. If Magnets be of one mine, the biggest will lift up and hold the greater weight, for this purpose the longer form from pole to pole is best, and bulk being compared with bulk, this form will take up the greater weight, because his diameter is longest. Take a long piece of iron or steel, as a knife, or dagger, or sword, that is finely polished, and touch and excite them Magnetically, and these shall take up a greater weight of iron than the Adamant itself, so it be very good and little shall, that gave them their vigour Magnetical to lift up, and retain firmly, Table XII. Fig. 2. I have a Loadstone that will vigorate a sword to take up and hold a pound weight. Likewise Magnetical needles and excited wires will strongly retain and adhere one unto the other at their convenient poles, hale one the other, and lift them up, and retain them firmly, for such Magnetical forms of iron and steel as be touched and animated Magnetically, are sooner apprehended, held fast, and lift up in the air than those that be untouched and unexcited, because that when the Magnetical vigour is infused, dispersed and spread through all the parts of the iron-waights, or of steel, these forms are sooner united and faster tied, as it were, with strong ligaments and cords, both unto the Loadstone, or one unto the other, Tab, XII. Fig. 3. therefore if sand or other matter that is not Magnetical be fastened and bound unto a small piece of iron, or this small piece of iron be fastened to a pair of seals, that have strings to the scales, though iron be the weights of the scales: yet the Magnet will lift up and hold a greater weight that is all continued iron, than he will do of these mixture and intermission of Magnetical medium, of diverse and different substances, not Magnetical. If a Magnet be fastened to the pole of another Loadstone by his convenient upper pole than a greater weight than before will be apprehended by the Loadstone and taken up, because that the Loadstones, virtue is increased and augmented by the addition and adjoining of the other Magnet, Ta. XII. Fi. 6. 9 Even so, for the same cause, if a wedge of iron be placed on the upper pole of a Loadstone, the other pole that is downward will take up a greater weight, Tab. III. Fig. 2. If there be a thin plate of steel or iron held or fastened unto the neither pole of the Adamant, between the Loadstone and the weight, than the Magnet will lift double, and sometimes decuple, or ten times as much again, from this practice begun and grew the arming and capping of Adamants with steel and iron, after diverse manners, Tab. II. and as hath been declared in XVIII. Chapter, Of the augmenting the virtue of the Loadstone; by this arming of the Lodestones with steel and iron in convenient places, their virtue and potency is greatly multiplied, both to unite, attract, apprehend, and lift up greater weights, and also to move, turn, and conform Magnetical needles a far off, and the needles by having a strong vigour infused into them direct and retain themselves more firmly in their conformity and direction Magnetical. If a plate or cap of iron be held to any parallel between the aequator and the pole, crossing in any meridian, there will be an apprehension and retention of iron, wires, and weights, much heavier than the bare unarmed stone will hold without this cap, Ta. XII. F. 7. Where the superficies of the Magnet about the pole is flatted and made plain, having armour applied to it, and a tooth descending from the point at right angles to the axis, here this tooth will take up 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 up at the pole only, if there be three of them readily provided, put the second to the neither pole of the first, and he will retain him firmly, then add the third to the neither pole of the second and the first, by virtue infused into the second, and the third, will strongly hold them both in the air, Tab. XII. Fig. 9 all of them being armed and communicating their vigours together firmly to unite. So a dagger or sword excited, will lift up one weight at the end of another, and if the upper that touched the sword or Loadstone, be held an inch off, yet by the virtue that is extended within the orb Magnetical, the weights will cleave together still. Set a short and small wire at the pole of a Magnet, and it will be erected, set another on this, and it also will be carried upright, set on the third, and all three will be apprehended and borne up, Tab. XII. Fig. 7. Also set a short wire on the pole, and another on a meridian, not far off the pole, or set them upon two several meridians, upon a strong Magnet, then lay another short wire on their heads, & they will hold and carry it, and this also will carry another wire upon his back, Tab. XII. Fig. 8. There be certain forms of Magnets, as the Semiterrella, in fashion of an half bowl, the long oval made plain at the bottom, the long square forms, described, Tab. II. all these may be armed and capped with two teeth, at right or obliqne angles to the axis, which being thus prepared, will apprehend great weights, and retain them most firmly in the air, Tab. XI. 12. 13. If two Magnets, armed with two teeth apiece, be set before us, the one being strong, the other weak, or much less, whose axis or diameter between the teeth is equal of like length, than set the teeth of these together that come from contrary poles and parts, and the stronger will apprehend and lift up the weaker, and the weaker being united and incorporated with the stronger, by the virtue that he receiveth from the stronger, will lift up from the ground, and retain the stronger and greater very firmly, although he be much heavier than the weight, the small stone doth ordinarily lift up, 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 upper teeth will cleave fast to a great weight of iron, and hold by the same firmly, apply a weight to the: neither two teeth, and all will be retained and held together most firmly by parallel virtue of the meridians from the axis. Such Magnets as be armed to one superficies, with four or five teeth, or more, Tab. XII. Fig. 11. 12. must needs apprehend more and greater weights, retain and lift them up most easily. A piece of steel well tempered, being excited, will lift up a greater weight than the like form and bulk of iron will, also this tempered metal in a kind of form might be capped like a Magnet. It hath been proved that the apprehension is better between the bare stone and iron, as also the armed Adamant, with the armed Adamant, is most strongly retained, and far more firmly than the retention of one Loadstone is with another small and bare stone. Now it is to be observed that steel, by reason of his dryness, 〈…〉 his vigour Magnetical, bestowed upon him, better than the iron doth that is softer, which entertaineth the virtue Magnetical sooner, and retaineth it the less time where his substance is less extensible and glutinous; so steel being very often excocted and evaporated in the fire, becometh very brittle, and will not receive the Magnetical vigour, yet being reduced from that hardness, and easily tempered, not to be over hard, will retain the vigour Magnetical better than iron. Those Adamants are the best which are bare and naked without their furniture and armour to take up their own weights, or more, at one of their points and poles, and retain the same firmly. Such Adamants will cleave unto a piece of iron by their meridian, and hang unto it, and will retain a great iron weight also adhering to the meridian parallel to the Axis. CHAP. XXV. Of Magnetical direction from the earth. HItherto I have discoursed of the Magnet, and other Magnetical bodies, parts, motions, applications, virtues and effects, as they have one unto the other, which have been of that quality, that they might be almost all of them experienced and observed at home and in our houses, handling the Loadstones as little earths and globes, and turning them about with our hands, to see, observe, and understand all the qualities, virtues and effects of the same whatsoever, comparing these Magnets, as diverse earths and Magnetical globes together, with the motions, compassions, and conclusions, proceeding from a present, particular, and unnatural cause and potency in the stone before our eyes. And having before partly discovered the motions that Magnets have with the earth, being taken out of the same, and bred, and animated therein, as also the motions of such irons as have been excocted out of the mines, and such like veins, or rather bones of the Earth, that have been also endued and excited with the directory and Magnetical vigour from the Earth, both at their first forging and forming, as also by their placing upon the ground whilst they cool, and become tractable with our hands, and their position in houses, windows and other places. Also I have showed how this virtue directory, polar, vigour, and polity is to be given to compasses for the sea, & to directory needles, that direct our movable dials into the meridian line, and to the Inclinatory-needle, or any other needle or Mathematical instrument whatsoever. Now I am to declare how such demonstrations as have been learned at home out of the Terrella and Semiterrella magnetical may be put in practice and use by such as sail to far countries by sea, or travel 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 perform and learn very perfectly, having the directory in their compasses, and the Inclinatory-needle in the meridian ring artificially made about them. In comparing the two Magnetical bodies of iron, and the Magnet with the earth, the great and mother Magnet of all Magnetical bodies, we shall see and behold, that not only in the Loadstone the Terrella and Semiterrella, but principally in the great Terra and Magnetical globe of the Earth, there is naturally found the two poles, the North and South, the aequator, the meridians, parallels, axis, and horizon, whereupon all the motions and conclusions that have been made upon the meridians of the said forms in the Magnet, are proportionably and agreeably to be found in the Magnetical globe of the earth, in passing about her meridians, for all Magnetical motions are performed upon the meridians principally, as hath been said. Therefore place any Magnetical body, as is used 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 unto the meridian of the earth, because that the earth hath primarily, naturally, & from her first creation, all Magnetical faculty, vigour, virtue, power, and potency in herself. And first if a Magnet whose poles are known by the Art before taught, be placed in a boat, or bowl of wood, and put into a great basin or bowl of water, it will conform, direct, and seat itself North and South, according to the same position and meridian that passeth directly unto the poles of the earth; Likewise take a Magnetical needle that hath been excited with the Adamant, such as be in movable dials, or else take the Mariners compass, and place them in quiet situation, and they will be directed by the disponent virtue and Magnetical vigour of the earth towards the North, and Southpoles upon the true meridian circle and line, if there be no obstacle. All direction is observed by Magnetical bodies, especially by the directory-needle and compass upon one certain horizon, whose centre is in a meridian cut by some of the parallels, and on this centre the needle and compass is supposed to be placed, being truly peased and composed, that they may play, turn too and fro, and rest level and parallel unto the horizon, fitly placed upon a pin of brass or silver, and be well touched and excited, to the end they may be directed more certainly towards the poles upon the meridian, Tab. XII. Fig. 13. All Magnetical needles would be touched with a good vigorous and big Loadstone, that being capped lifteth up at least half a pound weight of iron, to the end it may carry the fly and card of the compass 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 itself North, swimming in a dish upon the water, by the disponent power of the earth, and being freed from out of the orb and virtue of other Magnetical bodies, these are turned and directed by the vigour of the earth into the South upon the meridian line. Even so a rod of iron that stath been placed North and South in a window a long time, whereby he hath received a true touch of polar virtue from the Earth, being within the orb of his vigour, and being removed from this position, which would be noted with chalk, and hanging levelly in a string in the air, will move his North part, and seat it in the South quietly. Therefore all Magnetical 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 immediately out of the earth, or any iron or steel that is excited, either from the earth, from an Adamant, or from another excited needle, iron, or knife, or long form of clay, all these whatsoever receiving their directive and polar faculty from another Magnetical body, being set at liberty artificially in the air or water, to move and turn, will seat and be directed to the contrary pole they were first revived by. Every part from the aequator to the pole doth give a polar and Magnetical virtue unto diverse forms of iron and steel to move unto a contrary position, by the directive faculty of the earth. This faculty directive is as strong upon the aequator as elsewhere, though it do not bestow it to others, being fortified from both provinces on either side, and when the needle and compass shall be in the aequator of the earth, because their libration and levelnesse is all one with the horizon: therefore here the direction is conformable and strong: but in other places, and near the pole especially, the leveling 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 weak: yet in this place near the pole in the Terrella and Semiterrella, the little needle on his foot beareth himself most strongly and stiffly, that being with a finger turned awry, it will turn again to his direction very violently, though inclining to the stone, and rest itself very speedily, without many turnings to and fro, so that near the pole the direction is very strong, neither by leveling hindered. Always and in all places the Lily of the compass or cross of the directory-needle standeth and is seated into the North, both in this North side, and on the other South side of the equinoctial line or circle of the earth, Tab. III. Fig. 9 Tab. XII. Fig. 13. contrary to the site of the needle near the Terrella or Semiterrella, because they are touched and excited at that point of the Load stone that in his boat resteth South, and being set at liberty from the Loadstone by the earth is turned North, as the point touched at the North-pole of the Adamant is turned South, neither needeth there here any conversion of the compasses in sailing and going from one province of the aequator to the other, as the needle idoth towards the Magnet being masculine, and the needles of iron or steel feminine, but the needles to the earth are perfect Magnetical bodies, and do keep their correspondency with the earth, as if they were Magnet stones, or diameters of little earths: therefore the needles and compasses passing from one side of the aequator to the other, in a meridian and great circle, proceedeth on still in a right line uniformly, only the points of the needles and compasses do take their turns to be predominant in their direction in their own provinces, especially if their level would suffer the virtue Inclinatory to prevail, which thing is most apparent by the Inclinatory-needle in his ring, that being on this side of the aequator erecteth his lily above the horizon towards the pole, but on the further South side of the aequator dippeth his Lily under the horizon, and suffereth the Point to respect his own pole with convenient angles to the axis. But this thing cannot be done by the compass and directory-needle, which lie always parallel to the horizon, but only is demonstrable by the stone in the 4 and 5 tables before. This were a fit place, to speak of the order of making Sea-Compasses, the instruments for Magnetical direction, the making whereof is very well known unto Artificers, yet I could wish, that they were more artificially made than they are, though the price were somewhat more, with some additions, which we do partly touch in the Chapter following, and wish also that the points were 48. in use, that every point might be half an hour. All direction is performed upon the true Meridian respecting directly with the Needle the poles of the earth, as the Needle doth in the good and polished Loadstone and Terrella, unless it be weakened, depraved, and forced to decline from the true Meridian of the earth, by the causes of variation. CHAP. XXVI. Of the variation of the Compass from the true Meridian. Tab: XIII diagram But because the Globe of the earth is known unto us, to be very un-even and un-equally mixed, with many materials, differing from Magnetical substance, having great and stony Mountains, large Valleys, deep Seas, long and high Continents and forelands, some with mighty scattered rocks of Loadstone, of Iron-Mines, and other Magnetical matter, and some without, as also the entrails, and interior substance, bark or scarf of the earth, consisting of a great quantity of substance not Magnetical, whereupon it cometh to pass, that when the Magnetical faculty of the earth shall direct these Magnetical instruments of the Needle and Compass, they are not composed or set directly upon the true Meridian that passeth right on to the poles of the earth, but are drawn and forced awry towards some vigorous and Magnetical eminency of the earth, whereby the Meridian which the Needle and Compass maketh doth decline and vary from the true Meridian of the earth, certain parts & degrees in the Horizontal circle, which is called the variation of the Compass; the Meridian that this declination of the compass & needle maketh, may be termed the Magnetical Meridian, to distinguish it from the true Meridian, and the space between the Magnetical Meridian, and the true Meridian is the difference of variation; So that here the needle & Compass do dispose themselves into the North and South obliquely, and not truly and exactly, and according to the diversity and strength of the scattered Magnetical bodies, being the causes of variation, the arch of the declination is greater and lesser, as in sailing by great Continents, and Highlands Magnetical, either the point or tail of the Needle, and Compass, is forced awry towards the East or West, as is demonstrated in the chapter of Applications, & in the XXIII. Chapter. For if the Magnetical eminency, whether it be iron like clay, mine of iron, or rockeof Loadstone, be contiguous unto the Magnetical Globe of the earth and fastened in the same substance unto it, than the Compass and Needle will leave the direction of the Magnetical Globe of the earth, and deflect towards this eminency, but if this Mountain Magnetical be not continued with the Globe, and have other Materials under and about him, than the Needle and Compass will be thrust awry, and fly from it, declining as much, in a manner, the other way, leaning unto it by the other point or tail, as it is demonstrated in the rule of Application of one Needle, in his varrying upon the Loadstone, unto a piece of Iron, touching and not touching the stone. And no less doth the Needle and Compass upon the continent and inner-land, decline Easterly or Westerly, when as a great part of the earth shall be of a substance no way Magnetical, and the other part shall be of a vigorous and Adamantine quality to attract unto it. For although all direction to the North and South by the Needle and Compass, be from the virtue of the whole Magnetical Globe of the earth, yet a strong effectual, and near particular cause, though weaker, as it is proved in the end of the XXIII. Chapter, varieth their direction diversly, and erratically, by that Land especially which lieth and treateth North and South. Where as the vigour and potency Magnetical increaseth from the Equinoctial to the poles of the Magnetical Globe of the earth, as it doth in the Terrella, whereby the like eminency Magnetical, in the parts near the poles, be of more allicient and Adamantine property, than they are about the Equinoctial, therefore it may be thought, that in sailing upon one Meridian, in like distance, from this eminency, enriched with this vigour, it will make a greater variation of the Compass near the pole, than it doth near the Equinoctial, but this matter may be helped and lessened by the great vigour that the needle is directed withal from the Adamantine. Globe of the earth, especially if the Seas be shallow, and the Needle in a near Orb unto the same, for thus the Needle will very hardly be removed, because the force of the earth is great that directeth it, but mark that in the XXIII. chapter, where a smaller strength Magnetical altereth quickly the retention of the whole more vigorous Magnet. Also it is thought, that the variation of the compass is much furthered by the natural inclination of the needle and his conformity to an highland, along the Meridian, between the aequator and the pole, like the demonstration of the Tab. VII. Fig. 2. where the long Loadstone varieth the Needle from the Meridian by little and little to a right angle, so if it could be found out, that a near particular cause were so potent to vary the needle, as the longstone, there is the side of the land would vary much, but the cap far more, also at the aequator, as in the Tab. VIII. Fi. 5. an eminent part of land, ending at the aequator, might vary the needle much, as is there demonstrated. Although these applications be great inducements that there should be such positions of the Compass, in some places between vigorous lands, to be observed, yet because that these eminences from land, are not any particular and complete Magnets of themselves, but adherences and protuberances of some part of the Magnetical Globe, and have their nature according to the vigour of that parallel where they stand, and have not every one of them a pole near their caps and angles, as these Magnets have, in their demonstrations set down. I cannot wholly approve them for sufficient demonstrations of variation, though they may help very much for the understanding of the same. Therefore, for the better knowledge of the variation of the Compass by the Terrella, it is very convenient to apply a strong Magnetical body upon the Terrella, alongst the Meridian, or a little obliquely, then carrying a little needle upon the Terrella, the needle will vary more from the true meridian near the aequator, than it will do near the pole, because the Needle near the pole is directed very strongly and stiffly by those parts, and will hardly be forced from his direction. But let the eminency be very vigorous thick, and about twenty degrees high, then hold the Needle so high from the Terrella in that Orb, than the Needle is to be conveyed from the aequator to the pole, and first bring this eminence towards the Needle, and it will begin to vary from his direction, being within twenty degrees or parts of the eminency, and so increase his declination continually till he be varied towards sixty degrees, in the parts near the aequator, and about fifty degrees, at the most, in the parts nearer the pole in the same Orb, therefore the deeper that the Seas are, the greater is the Magnetical Orb, and the more subject to suffer the Needle to be attracted by a near eminency, and the shallower that the Sea is, the less is the Magnetical orb of the earth, which more hardly suffereth the Compass to vary. This is to be noted that high-eminences and lands near the poles, being before the Compass do not cause the same to decline, but only such eminences as are placed according to the Meridian's, and trent North and South, or obliquely a little on either side, to these the Compass will be attracted awry from his true direction. But if there be a narrow passage between two highlands, than the Compass and Needle will respect neither eminency, but carry and direct itself paralelly between them both, when the strength of two highlands is of equal force; as it is demonstrated upon the Terrella, and not unlike to the figure, Tab. VIII. Fig. 3. This is to be observed also, that the midst of an highland, by demonstration upon the Terrella, doth attract most, and make the greatest variation, and towards the ends it decreaseth by little and little, and once passing by the eminency it varieth the compass no more, and it is likely so to do upon the earth. If there be a Magnetical rock lying sidelings under the water, it will make the needle vary a little from the true Meridian. Therefore the farther that the Compass is distant from an highland, that attracteth, the less is the variation, and passing further out of the orb of his virtue there will be no variation at all, unless the deeps and substance of the earth be partly Magnetical, and partly of different substance, For these causes it is observed, that places of a small distance asunder do differ much in their variation, holding one proportion, neither in passing upon a meridian, or on a parallel, yet in one and the self-same place variations never differ, but remain certain and constant. The West-shore of a magnetical continent doth make the variation of the compass Easterly, and the East-shore of a maine-land beholding the Sun rising attracteth on the northside of the aequator, the Lily of the Compass that it decline West from the true Meridian, on the Southside of the Equinoctial the point of the Needle is attracted, Table XIII. Fig. 1. 2. About the islands of Azores the Compass hath little variation, as at Fayall the Compass varieth to the East three degrees, and at Coruo the variation of the Compass four degrees to the West. Some think that islands, though Magnetical, make no variation, being too weak and feeble in regard of the great strength of the directive globe of the earth, which directeth the needle and compass, because that the Island of Elba, near Florence, being full of Lodestones, causeth no variation of the compass more than other places near adjoining do, but if upon the Terrella, as in the XXIII. chapter there be never so little wires applied near a needle, it will deflect towards them, so that here perfect observation may be desired, which by the common rules is long and tedious to perform: therefore I will set down ready and easy ways to observe the true meridian by the Sun, that the variation of the compass may be plainly perceived, and that in a moment, by one observation only, to the end that industrious and skilful pilots will in time furnish themselves and the world with the true observation of variations in all parts of the world. CHAP. XXVII. Of finding the variation of the Compass by one observation. FOr this purpose there are certain things to be known, and observations to be had in a readiness before this conclusion be found out, first the place is to be set down by name or note, where this observation is made; then the altitude of the pole in that place is to be known and set down, after the day of the month; and the declination of the Sun are to be set down, all these things skilful pilots know very well to perform. Then having a good sea-compasse for the water, and a large directory-needle for the land, it is necessary upon the outmost part and circle of these to have a limb or verge a quarter of an inch broad for the horizontal circle, and to have the one half of it divided into two ninties of degrees, with his convenient parts and figures, as is usual in all quadrants, beginning the numbers from the meridianline, and ending them at East and West. Next provide a diameter somewhat longer, then that of the circle, of brass, wire, or silver, having in the midst or centre of it a small wire of the same metal, fastened and soudred unto it at right angles, as a Semidiamiter, all this being framed will be like in fashion to the beam and tongue of the balance of a pair of scales, Tab. XIII. Fig. 3. and just at the East and West put this diameter through two holes of the sides of the compass, or fasten it there with two loops of brass, that you may turn the semidiamiter up and down just over the centre of the compass and needle, and this may be set upright at either end, with two little shoulders of brass to keep the semidiamiter upright and perpendicular unto the horizon. Having the compass and needle thus furnished, place the needle and Lily of the compass just against the beginning of the divisions, than set the compass before the Sun, with this semidiamiter erected where the compass and needle standing in their Magnetical meridian, the shadow of the Sun from this semidiamiter will show upon the degrees of the limb the Magnetical position, and azimuth of the Sun, which is presently to be noted down, as it is East or West. Note that at sea if the ship turn any thing about, the box of the compass must also be turned, that the meridian of the fly may be always against the beginning of the divisions. Likewise, because of the ships unsteadinesse at sea, it is fit to have a wire erected from the centre of the fly, whose shadow among the divisions, upon the fly of the compass, will show the Magnetical azimuth. Then instantly having a jacobs' staff at sea, and a quadrant at land, take the altitude of the Sun, which is to be noted down, and after at pleasure and leisure, having these petitions, the variation of the compass for that place may thus be had. Take M. Blagraves' Mathematical jewel, or the Astrolabium Catholicum, set out first by Gemma Frigius, which is not so ready as this, because it lacketh the rete which this hath; place the horizon of the rete to the altitude of the pole for that place, and look where the suns altitude that was observed and almicantareth crosseth and meeteth with the parallel of the Sun's declination for that day before set down, and the azimuth or vertical circle that crosseth these two in that point where they touch, and this is the true azimuth of the Sun from the true meridian, which differing from the Magnetical azimuth as first observed upon the compass, the difference of these two azimuths is the arch of the variation of the compass, and of the Magnetical meridian from the true meridian, which is to be set down, that this is the variation of the compass towards the East or West for that place. CHAP. XXVIII. Of finding the variation of the Compass, by the circles of the Astrolabe. FOr this purpose the petitions required in the former chapter, are to be writ down, and in a readiness, as the place of the observation, with the altitude of the pole in that place, the day of the month, with the declination of the Sun for that day, the Tab: XIIII diagram Magnetical azimuth, and the altitude of the Sun for that one instant of observation. Now in describing the circles of the Astrolabe for this purpose, first upon a line B E D at the centre E make a circle a B C D, and by the centre E draw the line A C at right angles to B D from A towards B, number the altitude of the pole, to which point apply a ruler from D, cutting the line A C into the zenith point F, set one foot of the compasses in F, and describe an arch towards B at any distance above and below, after the compasses unremoved set the foot of the compass in B, and cut the former arches into points, unto which applying a ruler, draw an obscure line to divide the line A C produced into K, from the centre K, according to the distance to F, describe the vertical circle F G H I, making the line K G I at right angles to F H, now from A towards B number the declination of the Sun for the day proposed for the North signs, and towards D for the South signs, place a ruler to this point and to D, cutting the line A E into L from the centre E, as is the distance E L, describe a circle for the parallel of the Sun, next from D towards A, number the altitude of the pole to M and by the centre E draw an obscure diameter M, E, N from M N towards A B number the altitude of the Sun before observed, applying a ruler from D to each division, to cut the line A C in two points from the midst, as a centre between these two, and by them describe a circle for the almicantarath of the Sun, dividing the parallel of the Sun at O, from O and F make obscure arches to cut one the other, from whose centre P to O F, describe an arch of a circle for the true azimuth. Which to know what it is, draw an obscure line from F by P, to the circle F G H I unto q, then divide the arch q h in the midst at r, and the arch g r resolved into degrees, shall be the distance of the true azimuth from the meridian. The difference of the Magnetical azimuth from this azimuth, showeth the distance of the meridian of the compass from the true meridian, which distance is the variation of the compass for the place observed. A short way upon land to draw the meridian line upon a plain superficies leveled to the horizon; immediately before the observing of the altitude of the Sun, hold a plummet by a thread, that the shadow light on this superficies, in this shadow make two pricks to be joined together in a strait line, after out of this type set the angle g k r, which shall be the meridian from the line of the azimuth mad●●y the shadow. CHAP. XXIX. Of finding the variation by the Analemma. Being furnished with the petitions, before recited in the former chapters, make this Analemma, about the horizontal line A E C, describe a meridian circle, and make the vertical diameter B D by E, at right angles to A C, then from A to F in the quadrant A B, number the complement of the altitude of the pole, and by E draw a line F G for the intersection of the aequator & meridian, them number from this aequator on both sides the declination of the Sun for the day of observing, being 10 degrees, and from the points draw the line H I for the parallel of the Sun, next in either quadrant above the line A C, number the altitude of the Sun before observed to be 30, to k and l join these two Ta: XV diagrams together in a line parallel to A C the horizon, passing through the centre of the Sun, and cutting the vertical line B D into M, and the parallel of the declination of the Sun H I into N from M a centre, describe a semicircle to k l, and from n draw a perpendicular line with k l unto this semicircle, dividing the same in O, and join m O by a line together for the distance of the azimuth from the true meridian, which being resolved into degrees, and compared with the Magnetical azimuth, the difference between these azimuths showeth the degrees of the variation of the compass. CHAP. XXX. Of finding the variation of the Compass by an Equinoctial Dial. Provide in a readiness, an universal Equinoctial Dial upon a plain, that may artificially be erected to the height of the complement of the Latitude of the pole, for the place of observation, and upon the centre of the Equinoctiall-circle place a ruler, and at either end of the ruler erect a plate of brass, little more than a quarter of an inch broad, that may with joints conveniently be raised at right angles, to the ruler and superficies of the Dial, and upon these plates place the divisions of the Trigon of the twelve signs, after this manner. Tab. XV. Fig. 2. Draw a strait line a b, and from a centre, describe a quadrant of a circle to c, and let c a cut a b at right angles, then divide the quadrant c b into ninety degrees, then from b towards c number the greatest declination of the Sun, which is 23 degrees and an half, ending in d, and at d draw a line at right angles, to a b, which is d b, and set the length of the line d b from a to h in the line a c, then produce the line a b, obscurely to e, and from b as a centre according unto the distance b d, make an obscure semicircle over the line a b e, divide this semicircle into six parts, for six signs, every division containing 30 degrees, when it shall be subdivided then join these divisions together in parallel lines to a b e, for the beginning of the six South-signes, then from d b draw a parallel line f g, according to the breadth of the plate, and from d to f make a parallel to a b e in d f, the plate being somewhat higher, make an hole, as in a Diopter, that the Sun may shine in at it in Summer time, upon the other plate at a h for the North-signes, which plate a h i k, would be of the same breadth and height that b d, f g is, then let the obscure parallel lines of the beginning of the South signs be drawn upon this plate, place ♎ Libra above the line b g, ♏ Scorpio above next line, ♐ Sagitary above the next line, and under the line d f place ♑ Capricornus, under the next ♒ Aquarius, and under the next ♓ Piscis, the other plate for the North-signes, mnst have the same parallel lines in it that this hath, for the beginning of the North-signes, and an hole in it for the Diopter, that the Sun may pass through it to the first plate of the winter-signes to show them that part of the plate or end that hath the Diopter in it is to be placed in the line b a k, contrary to the situation of the parallels in the first plate, & under the upper-most line h i, place ♈ Aries, under the next ♉ Taurus, under the next ♊ Gemeni, then above that line that hath the Diopter, in it place ♋ Cancer, above the next ♌ Leo, and above the next ♍ Virgo, so is all the characters of the signs placed in their plates, let the ruler be of the breadth of the plates, and in the midst of it draw a line, and in the middle of it make a hole of the centre L, the better to be fastened to the centre of the Equinoctial: k and m must be artificially joined with joints together and g n, at which the ruler from l is produced to make an Index upon the Equinoctialldyall to show his hour as it is Tab. XV. Fig. 2. Moreover, there is to be placed in the foot of this Equiquinoctiall Dial, a large directory-needle, having his outer-most circle divided into four ninties, beginning to number the parts from the Meridian to the East or West. This Equinoctial Dial being thus furnished with the ruler and plates for the Zodiac and the directory-needle, and erected to the Equinoctial of the place, where the observation is made, turn the whole frame of the Dial and ruler about with his plates, until the Suune-shine directly upon the sign and parts that he is in for that day, than his whole frame will stand in the true meridian, and the directory-needle will stand in his Magnetical meridian, and point out so many parts in his horizontal circle, as his variation in that place is to the East or West, which is to be noted down, and the ruler in the Equinoctial circle showeth the true hour and part of the Sun, for that day and instant. Tab: XVI. diagram CHAP. XXXI. Of finding the variation of the Compass by Rings. THere is an other instrument consisting of four rings of Brass, one to be placed within the other, which is an universal Dial, having a directory-needle in a box, fastened at the bottom of the same, which doth show likewise presently the variation of the compass hanging perpendicularly, Tab. XVI. The first two rings of this instrument are two meridians, the outer-most is broad, and hath a ring to hold it by, fastening it to the upper end or top, and the North-quadrant towards the ring or handle is divided into ninety degrees for the numbers of the altitude of the pole, also this ring hath fastened unto it at the bottom a directory-needle in his box, the limb whereof is divided into two ninties from the meridian to the East and West. Within the ring of this broad meridian, there is an other meridian-ring placed, so kept on the sides, that it may be moved higher or lower, so that his broad Index, fastened unto one of the four quadrants, may be set to point out the degrees of the altitude of the pole, this Index hath a lower end for to stay the fourth ring that carrieth the Trigon of the signs, and a thread like an axis with a movable bead thereon. The third ring within the second is for the Equinoctial circle, and it is fastened to the movable Meridian-ring at right angles to the elevation of the pole by two pings, whereon it may be moved at right angles to the meridian, though it will be laid within the said meridian, in the inner part of this ring there is a circle to be drawn for the Equinoctial circle, and to be divided into 24 parts, for the hours of the day, from the meridian; and subdivided with convenient lines and figures. The fourth ring is fitted within this Equinoctial ring, and at six of the clock, or at the East and West is fastened to it with two pings, to move at right angles unto the same, this carrieth an axis which being moved about is stayed by the neither end of the movable meridians index, descending into a nick in it to hold it at right angles with the aequinoctiall-circle in manner of a sphere, and holdeth the said circle at right angles with the meridian, within this fourth ring, whose axis is stayed by the Index from either side of the equinoctial, having the centre in the equinoctial at the side of the ring, there is described above it, and below it, the greatest declination of the Sun, and the arch between the same and the equinoctial is divided into such parts for the beginning of the twelve signs as the plates before were in the former chapter, adding the characters of the twelve signs, as it was there done; then at the sides of this ring in the equinoctial where the centre of the foresaid declination was taken, fasten the head of a pin of brass, and from it beholding the sign & place on the other side that the Sun is in that day, and between the eye and that place in this line place the bead upon the axis and so fix it. Now having this instrument thus prepared, set the Index of the movable meridian unto the altitude of the pole, and moving the Equinoctial circle, and the colure-circle or different of the signs, and fasten it firm at the lower end of the Index, hold the instrument by the ring, or handle, like a sphere perpendicularly, and turn it too and fro till the shadow of the bead light upon the middle line of the aequinoctiallring, thus the meridian of this instrument standeth upon the true meridian, the shadow of the bead showeth the hour and his part of the day, & the needle in the box pointeth out the variation of the compass in the limb of the horizontal circle. These rings, at pleasure, may be folded one with in the other for conveniency of carriage, and in time of use set abroad like a sphere. Any universal, or Astronomers ring, would be of especial use for the finding of the true meridian, as well as these, and having the needle added unto them, the variation of the compass would be found. CHAP. XXXII. Of finding the variation of the Compass by an horizontal Dial. WHen I was a young student in the University and delighted in making of dials, I was always wont to place the lines of the twelve signs in them, that when I set any bodies of dials in the Sun, upon a level foot, I always directed them by the shadow of the Sun upon his sign and part into the true meridian and South, and having a large horizontal Dial for any Region, with the lines of the twelve signs described in it, placing the same upon a level platform, and turning it until the nick of the shadow of the style light upon the place and sign that the Sun was in for that day, then fixing a compass or needle with his meridan parallel to the meridian of the Dial, the needle will show in the limb of the horizontal circle the variation of the compass, and the Dial showeth the hour and his part of the day. This Dial might be made universal as well as the equinoctial, if that in traveling North the North side were elevated by means of a quadrant, that the plain of the Dial might always have the pole of the Dial erected above him to that latitude for which it was described, and in passing Southerly the Southside of the Dial would be situated by the quadrant to his proper elevation. And if that the Azimuths and Almicantars' were put into this Dial, than the Azimuth and altitude of the Sun, with the place of the Sun and hour, would be presently showed by the shadow of the style, so that for these purposes, this horizontal Dial would be made universal, as a general Astrolabe or Astronomical ring. CHAP. XXXIII. Of finding the variation in degrees and minutes by the doctrine of Triangles. WHereas many may be desirous to know precisely the degree & minutes of the variation of the compass, for to satisfy these men's appetite, it is very convenient to understand the doctrine of Triangles, for by the Tables of sins, Secants, and Tangents, with the Axioms and consequents, & the Golden rule this, matter will be attained unto. And therefore for this purpose, I would advise you to observe and mark the frame of the Analemmaset set down before in the XXVIII. chapter, Table XV. Fig. 1. with the obscure lines pricked therein. First in this Analemma let G C equal to A F be the elevation of the equinoctial line, consisting of 38 and an half, which being called to C L 30. the suns altitude at the instance of observation for that day, and the some of these will be 68 ½ whose Sine is the obscure pricked line L P, now take A K 30. degrees being the suns altitude, out of A F the equinoctial Altitude 38. ½ there resteth K f 8 1/●, whose sine is the obscure line pricked q K, which added to L P. produced make L P S, 77. Divide S L into two equal parts ending in t, and take from S t, being 38 ½ the sine of the suns altitude K q 8 ● and take also out h r being 10, the sign of the suns declination, and there will remain t V being 20, then join t and m together in an obscure pricked line, and make a line at right angles to this from m to x being 20, and is equal unto t V, so have you this demonstration, and if you look into the Table of sins for the numbers, you shall find them set down in their place. And as the sine of t l is unto the sine of l m, so is the fine of x m unto the sine m n. So that the angle M B K in the Analemma being the complement of the angle M B N, will be the Azimuth you sought for, and it is equal to the angle O m D in the said type, which compared with the Magnetical Azimuth, the difference between them showeth what the variation is from the true meridian. Secondly, it is to be noted, that if this observation, or taking of the suns altitude be before 6 a clock in the morning, or after at night, when the Sun is in the North parallels, that N the intersection of the suns altitude and parallel of the suns declination be on the same side of the Analemma that t is on, then take h r the sine of the Sun's declination out of l t, and there will rest t V, join t and m together, and make a small line at right angles from n to x, equal to t V, for as t l is to k m, so is x n unto n m, etc. Thirdly, and lastly, if observation be made when the Sun is in the equinoctial, then make the small line m x equal to P t, and look what proportion t l hath unto l m, the same hath x m to m n where n is on the equinoctial line, etc. CHAP. XXXIIII. Inclinatory-needle to the axis of the Earth. WE have showed how the compass and directory-needle do apply and order themselves in the Magnetical meridian towards the pole, and of the correcting of his erring from the true meridian and pole, being carried level and parallel to the horizon, and seated in any part of the terrestrial globe, whereby, and to the end the traveler by sea and land may take his course certainly, to any coast or part of the world. Now it remaineth that we treat of the use of another needle, called the Inclinatory-needle, which being artificially placed in his ring, is as profitable to all Navigators and travelers, as that formerly spoken of; for by this they may know the elevation of the pole in all parts of the world without the sight of the celestial globes and lights. This Inclinatory-needle fitted in his ring, and placed in the Magnetical meridian, doth apply & conform itself unto the axis of the Magnetical globe of the Earth (whereas the directory-needle doth apply unto the meridian and pole) and that diversly in diverse elevations of the pole, for sailing upon the equinoctial of the earth, this Inclinatory-needle maketh a paralellline with the axis of the earth, being upon the pole, this needle will make one continued line and axis with the axis of the earth: passing from the equinoctial to either pole, this Inclinatory-needle will conform itself unto certain acute angles with the axis of the earth, which increase from the equinoctial in largeness, and prove less acute in every parallel, so that the angle of the earth's axis, and the axis of the needle is at the greatest about 42 degrees of the poles elevation, and the difference between these two will be near 22 degrees and a half, being here at the largest, after it decreaseth continually towards the pole, where the needle will stand directly upon the axis of the earth. Now to know and find out this angle what it is, it is necessary to learn what angle this Inclinatory-needle maketh with the horizon in every latitude of the pole, because if the elevation of the pole be taken out of this angle with the horizon, which is always the larger, (unless it be at the equinoctial and the pole) and hath the axis of the earth always between him and the horizon, the remainder is the angle of this needle's conformity with the axis of the earth. Therefore we will leave to speak of the Inclinatory-needles most natural and true conformity with the axis of the earth, and hereafter shall deliver by what means the angle between the Inclinatory-needle and the horizon may be known, to the end that the elevation of the pole may thereby be found out. CHAP. XXXV. Of the Inclinatory Ring and Needle. WHereas the horizon is very easily found out by any massy substance, which naturally will hang perpendicular and plumb, by having a level line made at right angles unto the same, therefore it shall be convenient to place this Inclinatory-needle in a ring of brass or silver, so artificially, that this frame being carried about the meridian of the earth, this needle may make all kind of acute angles with the horizon in the varieties of his inclinations unto him, as at the equinoctial this needle lieth level with the horizon, so at the pole it standeth at right angles to the horizon, and directeth itself in one line with the axis of the earth, and passing from the equinoctial, it doth elevate itself above the horizon twice as fast as the pole doth, until the pole have about an 11 degrees of latitude about the horizon, but after the needle slacketh his pace by little and little, until he come to the pole where both join together without any angle at all in one line directly. Also this needle maketh always one kind of angle with the horizon in one parallel and altitude of the pole, and a diverse arch from the same, but one certain in one latitude, as by this instrument following shall appear, and every where be observed. Tab: XVII diagram After provide two narrow plates of brass or silver, to be fastened on either side of the ring paralelly to the horizon, and in the midst of these, as it were, against the centre of the ring, drill and make two little holes almost through the sides of the plates for the short axis of the Inclinatory-needle to play and move in, up and down, according unto this kind of Magnetical and Inclinatory conformity. Lastly, this instrument would be covered with two glasses for both sides to keep the Inclinatory-needle from wind and weather, and a care had that the instrument hang truly perpendicular. In time of use in traveling, hang this instrument South and North in the Magnetical meridian, and this Inclinatory-needle will fall with one end under the horizon in every elevation of the pole, and bear up his other end in every parallel and altitude of the pole to a certain angle with the horizon, which may be called the Inclinatory angle for that place, which being noted in the meridian of this ring, with the degrees he pointeth at, is to be reserved as proportionable to that elevation of the pole where the observation is made, this matter was demonstrated by the round Loadstone in every part in the XIII. chapter before, which being collected by the said demonstration and practice, are to be placed in their correspondency in a Table for the altitude of the pole, whereby in all places it may be had readily what will be the angle of the Inclinatory-needle, and what is the latitude of the pole, caused only by the disposition of the Magnetical globe of the earth, and also by the diagrams following it is showed. CHAP. XXXVI. A Diagram of the needle's inclinations to the axis of the earth, and horizon in any latitude. THis demonstration showeth most manifestly unto our eyes, both what angle the Inclinatory-needle maketh to the axis of the world, or earth, in all regions, and also what angle or arch he pointeth at above or under from the horizon in any latitude of the pole whatsoever, hereby most evidently setting out the meanings of the two former chapters, and of the XIII. chapter before them, where it is demonstrated from the stone itself, that this Inclinatory-needle will make but one circumvolution about the meridian of the earth, as it doth about the Loadstone, the Diagram is this. Tab● XVIII diagram In like manner from the other ten parts, or 90 degrees, in the quadrant B D draw paralell-lines to the 〈◊〉 A D produced, and from every part as a centre extending the compass from the same to C, describe arches from C to those lines, dividing them into 90. parts a piece, and take like number of parts answering to these parts in the quadrant C D for the axis of the latitude, then draw an obscure line from A to the same part, in these larger arches, and that will show the angle that the Inclinatory-needle maketh in his inclination to the axis and horizon in that latitude. We have only for example-sake delineated the inclination of this needle to the axis and horizon, in the latitudes of 10. 30. and 60. the like whereof might be performed in every one of the other degrees of latitude, which thing is omitted to avoid confusion of lines. What this angle of the inclination of the needle would be in every latitude of the pole, although by the Diagramme, already set down, it might be Mechanically taken out of the quadrant C D, as it is reduced into ninety parts. Yet I will set down, how out of the cannons of Triangles, the arch from I to C, may be exactly known in degrees and minutes. In the Diagram G, A, B 30; the elevation of the pole being set for an example, draw from G these obscure lines, as G F, G K, G C, G A, and A F, the line of inclination, the content of the angle A G C is 15, C G K is 15. K G F is 20, so that the angle of the Triangle F G is 18, 50, and the sum of the opposite angles, which marked upon the semicircle, will be 130 degrees, whose half is 65 degrees, the tangent whereof is 214459690, than we find that the line G F in the triangle is equal to G C, the Suhtenses of 150 degrees, the half or sinus hereof is 75 degrees, whose parts out of the Table of sins are 96592583, which being doubled make the side G F 193185166. The side G A hath for his parts the total sine 100000000, the sum of these two sides is 293185166, and the difference of them is 93185166. Now multiply the tangent of 65 degrees 214459690 by the difference of the sides 93185166, and divide the product 42891938 by the sum of the sides 293185166, the quotient will be the difference of the tangents 146296413, which taken from the parts of 65 the middle tangent 214459690, the tangent parts that remain 68163277 give by the Table 34 degrees 16′ 47. ″ Here take 3416′ 47″ out of 65 degrees, there resteth 3043′ 13, for the less angle A F G, so add 34 16′ 47″ unto 65 degrees, and it maketh 99 16′ 47″, for F A G the greater angle, hereto add 30 degrees the elevation of the pole there amounteth 129 16″ 47″ for the angle F A B, which taken from the semicircle 180, there remaineth 50 43′ 13″ for F A C the inclination of the needle unto the horizon where the pole is elevated 30 degrees. I have here set down a Table calculated out of this diagramme of the degrees and minutes of the angles of the Inclinatory-needle, with the horizon answerable to every elevation of the pole, by Mr. Brigges the Geometry reader in Gresham College, who hath far more ready and easy ways to make the foresaid Table, than I have set down unto thee, and I think that this Table will agree more truly with the motion from the stone itself then that which is made by the same man out of the diagramme in the Chapters following. TABLE. Elevat. poli Inclinat ad horiz. G. M 1 2 2 2 4 4 3 6 6 4 8 8 5 10 10 6 12 11 7 14 13 8 16 13 9 18 12 10 20 10 11 22 5 12 23 59 13 25 50 14 27 39 15 29 25 16 31 9 17 32 50 18 34 28 19 36 4 20 37 37 21 39 7 22 40 34 23 41 59 24 43 21 25 44 40 26 45 58 27 47 12 28 48 24 29 45 35 30 50 43 31 51 49 32 52 54 33 53 56 34 54 56 35 55 55 36 56 52 37 57 48 38 58 42 39 59 35 40 60 26 41 61 17 42 62 6 43 62 54 44 63 40 45 64 26 46 65 11 47 65 55 48 66 38 49 67 20 50 68 2 51 68 43 52 69 23 53 70 2 54 70 41 55 71 19 56 71 57 57 72 34 58 73 11 59 73 47 60 74 22 61 74 58 62 75 33 63 76 7 64 76 41 65 77 15 66 77 49 67 78 25 68 78 55 69 79 27 70 80 0 71 80 32 72 81 4 73 81 35 74 82 7 75 82 38 76 83 9 77 83 39 78 84 10 79 84 40 80 85 10 81 85 40 82 86 10 83 86 39 84 87 9 85 87 38 86 88 7 87 88 35 88 89 4 89 89 32 90 90 0 CHAP. XXXVII. Another Diagram of finding the angles of the Inclinatory-needle in any Parallel. Tab: XIX diagram But to make use of this motion for the inclination, we shall only set down what aspects or angles the needle maketh with the axis of the earth at every tenth degree from the aequator to the pole, where in this Diagram there be lines to the inside of the quadrant D B for the inclination of the needle, which may also be produced outward into the orb of Magnetical virtue upon the limb, as it is set out in the twelfth chapter, Tab. III. Fig. 2. both in pricked lines, and also in the erection of a short wire at every tenth degree of the quadrant: therefore for the better preserving of this matter, we shall set down the order of the making of this Diagram, as followeth. Describe upon the centre E a meridian circle, as it were of the round Magnet A B C D, which divide into four quadrants, joining A and B for the axis, and C and D for the aequator, together with strait lines, which cut the one the other at right angles in the centre E, divide the quadrant of the poles elevation D B into ninety parts, beginning from D, and ending the numbers in B, with the usual figures. At D draw an obscure parallel line D F for the horizon, and from D, as a centre according to the semidiamiter D A, describe an obscure arch of a circle A B F, dividing the line D F in F, next upon E, as a centre according unto the semidiamiter E F make an arch of a circle F G, and from B a centre, according to the semidiamiter A B make an arch of a circle that cutteth the arch F G into G. Then place the foot of the compass in every part of the quadrant D B, as in centre, extending the other foot to A, and describe arches to F G, and first place the foot of the compass in the division of 10 in the quadrant, and opening the compass to A, describe the arch of a circle from A to the arch F G, and divide this arch from H into ninety parts, first into 3 parts, then part every one of these into 3 parts, containing ten parts apiece, if they were subdivided into them, then from 10 in the quadrant, to 10 in the arch from F G draw a strait line 10 and 10 for the line of the inclination, now draw an obscure line from E to the degree of 10 in the quadrant, and from this line at 10 make an obscure line at right angles for the horizon to E to, then take the semidiamiter D E, and place one foot in this line from 10 to H, and from 10 as a centre describe an obscure arch H L to the line 10 and 10, and this arch shall be the angle that the Inclinatory-needle maketh with the horizon, where the pole is elevated ten degrees above the horizon, and the angle 10 E and 10 is the complement of the former angle. Next place the foot of the compass in the twentieth degree of the quadrant, and stretching it to A describe the arch of a circle from A to the arch F G, which being divided into ninety parts, first into three parts, and these into three parts, again draw a line from 20 in the quadrant to 20 from the arch F G, now make an obscure line from E to the 20 degree in the quadrant, and from this line at 20 make an obscure line for the horizon at right angles to E, 20, take the distance from E 20, and place it in the line 20 I, and from 20 as a centre, the compasses being unremoved, describe the arch I M, cutting the line 20 and 20 into M, which is the angle the Inclinatory-needle maketh with the horizon, and being set in the arch D B, the number of the degrees of this arch of inclination will appear. According to this order draw arches from A to F G, making the divisions in the quadrant the centres, and their distance from A the semidiamiters of them, dividing these arches as afore is done, and drawing right lines to the correspondent divisions in their several arches from the several degrees in the quadrant, whose respondent angel's of inclination is known by making at the same and describing arches according to their semidiamiter from E, as hath been declared in the two former examples, which being reduced into degrees, by placing the arch in the quadrant D B, from D towards B, will show the quantity of the needle's inclination unto the horizon and his angle with the same. CHAP. XXXVIII. Of finding by the Needle's inclination unto the horizon, the altitude of the Pole by an instrument. 〈◊〉 XX diagrams Moreover describe a movable quadrant of the same bigness and semidiamiter that E D B is of, to be moved upon it in a paper apart, past-boord, or some metal, whereon this instrument may be described, (the larger the instrument is, the better it will be for use) therefore, according to the semidiamiter E D, describe a quadrant A B C Tab. XX. Fig. 2. from A the centre, & divide it into ninety parts, first into nine parts, than every one of these into two parts, and every one of these divided into five several degrees, thus will the whole quadrant be divided into ninety degrees; and at 90 degrees make a centre at C, and from B to C set the figures on the outer space in the limb unto every tenth part, as is used to be done, after a little half inch distance; from the centre of the quadrant A, describe a little limb or stay, then cut out the inward part of the quadrant C B to this limb or stay, and from the limb to A cut out a part, that the semidiamiter A C may serve for an Index or ruler, Ta. XX. F. 2. Now bring this quadrant A B C thus cut out, & place, and fasten the degree of 90 where the centre is at C, upon the centre E, on the instrument where the spiral line is on the same, Tab. XX. Fig. 1. In the time of observation by the Inclinatoryring, before described, mark what degree in the ring the Inclinatory-needle pointeth at in the meridian circle of the same, then in this instrument here described, note the degree observed in the ring upon the movable quadrant from B to C, and turn this quadrant about till that this note or degree doth touch the spiral line; here stay the movable quadrant, & his index C A will show in the quadrant D B, the altitude of the pole in that place. So back ways set the index of the movable quadrant to any elevation of the pole, and where the spiral line cutteth the limb of the movable quadrant, the degrees and parts show what should be the number, due to the angle of the Inclinatory-needle, and what parts he would point out in that place. A Table of the inclination of the needle, answering to every elevation of the pole, might be made by this instrument. CHAP. XXXIX Of finding the needle's inclination in every latitude by Table. THe way to find the angle, which the Inclinatory-needle maketh with the horizon in any latitude, or the degrees correspondent, by a table, is most profitable and ready, because that knowing any one of these two, that is, either the altitude of the pole, or the angle of inclination to the horizon, the other is presently known by the table. Seek in this Table following the altitude of the pole in the left column, and in the next place towards the right hand you shall find the degrees and minutes of the needle's inclination, unto the horizon, answerable for that latitude; as for example. I would know what would be the arch of the angle of the Inclinatory-needle where the pole is elevated 60 degrees, I to R make the angle S R N to consist of 52 degrees and 12l, which being subducted from the angle of E R N, containing 63 deg. and 17l, the angle S R E will retain only 11 degrees and 5l, whose complement S R T consisteth of 78 deg. and 55l, declaring the inclination of the Magnetical needle unto the horizon R T, where the latitude of the place is 60 degrees. CHAP. XXXX. Of finding the angle of Inclination, the Magnetical meridian, and the Azimuth together. IT is very convenient at sea to have a large Inclinatoryring with his Magnetical needle of a foot diameter, that the divisions of the meridian circle being large, the degree of the moving needle will the better be perceived, and to have a weight of diverse pounds fastened at the bottom to hold this ring plumb and steady: moreover on this weight I would have a compass, or directory-needle placed in his bottom, and a beam for a diameter and semidiamiter of brass, before described, for the observing of the Magnetical azimuth, as was appointed in finding the variation of the Compass. diagrams A long wire that hath been excited Magnetically, being thrust through a cork, and placed in the water, will show the Inclination and Magnetical meridian, at one instant, in his quiet situation. CHAP. XXXXI. Inclinatory-Needle. THe Earth being a Magnetical body and globe, conformeth the Inclinatory-needle to certain angles of inclination in every latitude of the pole, which angles are always one and the same in every parallel, as hath been demonstrated in diverse Chapters. Both by the Loadstone itself, by the fundamental hypothesis, by instruments, and by tables; but because that the globe Magnetical of the Earth hath many cavities filled with other substances different from Magnetical nature, and many mountains Magnetical mounted above these substances higher and lower, so that some attract, being above the point of the Inclinatory-needle, some being under it; some placed before it, draw the point of the Inclinatory-needle up unto them, other behind it, being also adamantive forts will have this Inclinatory-needle strike sail to them also, by which means the natural conformity of the Inclinatory-needle to his natural angles is much disturbed and depraved, whereby it cometh to pass that this needle hath his variation also, as well as the directory needle hath, as is before demonstrated. Therefore the variation of the Inclinatory-needle is, when in one altitude of the pole this needle pointeth out another angle, different from the true and respondent angle of that latitude of the pole, being hindered by a mountain, or part Magnetical, that doth attract one of the points of the Inclinatory-needle, approaching near unto it, either near the poles or aequator, in so much that the angle of inclination is made less or more than it naturally would be. In sailing East or West upon a parallel, having high land on the side towards the pole, consisting of Magnetical substance, this will attract the Inclinatory-needle, and cause his natural position to be more perpendicular than it would be. If the shore about the pole be situated between the Inclinatory-needle and the aequator, this adamantine eminency will attract the needle unto it, making his inclination less plumb then naturally it is. In sailing East or West nearer the equinoctial, where the carriage of the Inclinatory-needle is less perpendicular, and more tending to the level with the horizon, the Magnetical eminency between the pole and the needle, will pull down the higher end of the same, and make him more parallel to the axis of the earth, then naturally he could endure. Even so an adamantine mountain, between the Inclinatory-needle and the equinoctial line, will lift up the lower end of this needle, being within the Magnetical vigour of that mountain, and make him more parallel with the horizon than his natural conformity requireth in that parallel. The variation of the Inclinatory-needle is greater in the parts nearer the equinoctial, than it is in the parts near the poles, where this needle is not attracted so many degrees from his natural angle, as usually he is near the equinoctial. If in the parts near the poles, the Inclinatory-needle be carried between two eminences Magnetical, in that space of the strait where both their vigours be of like validity, they will make the application of this needle perpendicular, crossing them both at all right angles, not much unlike, as it is in XV. Chapter of applications, Table VIII. Fig. 1. In sailing nearer the equinoctial in straits between two adamantine mountains, whose vigour attractive surpass the general virtue disponent of the Magnetical globe of the earth, these will lay the Inclinatory-needle in a parallel and level to the horizon, though they be many degrees from the equinoctial, as Chapter XV. Tab VIII. Fig. 2. Lastly, in passing or sailing near and over a vigorous Magnetical rock, in the sea, or earth, under us, in approaching nearer unto it, the same will attract the Inclinatory-needle from his right place, and coming nearer the rock, it will alter him much more, and passing over the same, it will attract the needle perpendicularly, and being passed, this needle will be freed by little and little from that disturbance of his natural inclination. These varieties are found upon the Magnetical globe or Terrella, by having a convenient piece, or pieces of iron placed thereon, as hath been said, and placing the Inclinatory-needles, before described in the II. chapter, the one of them put upon a Lutestring, the other in his frame, Tab. II. Fig. 17. 18 or 19 so that I hope I need not set down any types hereof, for the ingenious will better conceive how to gather this matter from the globe of the Loadstone, than I can possibly explain in many troublesome figures, or the workman deliniat by his skill unto you in printed tables and figures. CHAP. XXXXII. Inclinatory-needle. Having declared the manifold causes of the variation of the Inclinatory-needle from his true and natural angle of inclination with the horizon; it followeth that we deliver plainly how to discern these events when they shall fall out, which are known perfectly by having the true elevation of the pole, where these matters shall be required. The rules and ways how to know the elevation of the pole in all places, is so perfectly set out by most Astronomers and writers of Navigation, and so well known to all expert Pilots, that it is a thing needless here to repeat them. Besides the ingenious Pilot knowing the elevation of the pole in some places of his voyage that he hath passed, by keeping a true, not a dead reckoning of his course in pricking his Card aright, and observing the way with the logge-line, with other currants and occurrants, will give a very artificial conjecture of the elevation of the pole in that place where he is, though he see neither Sun nor Stars. Notwithstanding because the skilful Pilots may be hindered in this kind of observation, by the falling of the ship to Lee-wards, and by other extraordinary change of weather, and other disturbances that may many ways fall out at sea, therefore I will only remember one way out of the principals before delivered, whereby he may at any time of the day, the Sun shining, know the altitude of the pole. This thing is chief performed by knowing the true variation of the Compass, which showeth the true meridian for that place, presently seek out the true Azimuth also, which is perfectly known by the shadow of the Sun upon the limb of the Compass, by the furniture of the beam, before described, instantly take the altitude of the Sun by the jacobs' staff at sea, or a large quadrant at land. The true Azimuth and Almicanter thus known, seek the point where they cross the one the other in the Rete of the Mathematical jewel and Astrolabium Catholicum, then observing the parallel of the suns declination for that day, turn about the Rete of this instrument, until this parallel of the suns declination be touched by the point, where these two circles of altitude and position meet, and then the horizon of the Rete will show in the limb the latitude of that place. The latitude of the pole for any place being known, the true angle of the Inclinatory-needle is manifest and apparent, as it is set down and known by the XIII. chapter, in the chapter to know the angles of inclination by the instrument, and in the table of the degrees of the Inclinatory-needle, answerable to every elevation of the pole. Now observe the degrees that the Inclinatory-needle pointeth out in his ring in that place, and take the difference of these from the degrees of the true angle, and that is the variation of the Inclinatory-needle for that place. CHAP. XXXXIII. Of finding the Longitude. HEre I purposed to have ended this short Treatise of Magnetical 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 Magnetical needles, before treated of, do not show the longitude; yet because the true meridian and altitude of the pole is known by them, there is much help brought thereby for the knowledge of the longitude, which by a few easy observations more, from the body of the Moon, will be obtained, whose motion if it should be set down and ordered in an exact manner, would require a large discourse, with many rules and observations of the moons inequality of motion, anomaly and prosthaphaeresis, of his excentricity, paralaxis, with the variety 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 only I shall here set down rules to know the place of the Moon at a larger scantling, yet very near the truth (though not the truth itself, which peradventure the best Studied in this kind can very hardly do) only borrowing half a days motion at the Moon, wherein the matters before mentioned will not alter many minutes. Provide an Almanac or Ephemerideses for any place or port, wherein the apparent place of the Moon in the Zodiac is exactly set down in degrees and minutes for the noon of every day, especially of the day of observing, then take the difference of the moons motion from the day before, and reduce it into minutes, dividing them by 24 hours, the quotient will show what minutes the Moon moveth in an hour. Now take the altitude of the Moon at any time of the day or night by the jacobs' staff, or a quadrant, then observe the Azimuth of the Moon by shadow, (as before for the Sun) or by a ruler with sights, which if it do differ any hours from the meridian, allow the parts due of the moons motion. Then seek in the R●te of the Mathematical jewel, or Universal Astrolabe, where the Azimuth and Almicantaraph of the Moon, newly observed, cut each other, setting the horizon to the altitude of the pole, and look what parallel doth cut these two, and follow the same unto the Ecliptic line (or do 〈◊〉 like of the moons latitude) in that sign, degree, and minute of the Zodiac, the Moon is in at that instant. These degrees, fewer or more than those of the radical and fixed meridian, for which the Ephemerideses was made, do show what hours and parts are to be added, if the observation be towards the West, or substracted if in the East, to this meridian (it is to be noted that every hour containeth 15 degrees of the Equinoctial) 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 pass from, by these Magneticall-needles only, it will be necessary to prick 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 upon the points of the Directory compass, and therefore it will be fit to have both these needles placed together as in the type of the XL. Chapter, and pendant before the Mariner at the helm with the Compass and Travers-boords for them both. Now for this purpose I would have another Travers ruler or limb for the quadrant of the Inclinatoryring, placed before him, as it is described in the Page following, where there is only 30 degrees divided upon the same, which being twice more repeated, will make up 90 degrees, every degree hath 6 hol●●, for pegs to be put into them, for the number of 10 minutes apiece, and on the first column on the left hand there are 4 holes made to receive pegs according to the number of hours you sail on such a degree and minute, pointed in the Inclinatoryring. diagram 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 delivered in that case of either, both in many Chapters of this book, and in the last precedent Chapter. CHAP. XXXXIIII. Of the matter of the Magnetical globe of the earth by the Needle. AT length we have brought our short Treatise Magnetical principally & most profitably to declare the nature of the Directory and Inclinatory-needle, both towards the Terrella and Semiterrella, and towards the Magnetical globe of the earth, and how the proportions and similitude of their applications and conformities to both are alike and the same. Only the Magneticall-needle being of a saeminine and sequent substance, as hath been 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 Magnetical, that is in the Adamants themselves, one towards the other, or of the needles one towards the other. But this Magneticall-needle being freed from the Magnetical orb of the Loadstone and Iron, will have that point of the needle that followed them directed by the virtue Magnetical of the earth into a contrary province of polar pre-eminence. For the Magneticall-needle doth conform itself unto the Earth in the same fashion that the Adamant and Loadstone itself doth; neither is it so serviceable unto the Magnetical globe of the earth as he is unto the Magnet and Iron, but is of a fellowlike species with the earth, as well as the Adamants themselves are. Whereby I do gather that the matter of the interior parts of the Magnetical globe of the earth is not the same with these we know of the Loadstone and iron, into whose bowels never any man, by the deepest mines, or other passages of fissurs and cavities, made by great Earthquakes, ever yet descended to show unto us any part of the earth's interior substance Magnetical, 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 earth's inward substance consists neither of solid Load stone, nor of ironlike mine or clay or such like materials, as they which have thought themselves most skilful in Magnetical Philosophy have imagined. For if the Magnetical globe of the earth were of any Ironlike substance, than that point of the needle that affecteth a polar jurisdiction, placed near the Loadstone and the iron, would also, being applied unto the earth, behold the same province and jurisdiction polar, being directed by the vigour of the earth's Magnetical orb of like nature; but this is not so, as all confess and may prove. Therefore I hold that the great Magnetical globe of the earth consisteth of a Magnetical substance unknown unto us, as also the bodies of the Magnetical globe of the Moon and of the rest do; and so conclude that the works of God are most wonderful, and altogether past finding out. But here before I end, I am to satisfy that I made promise of in the XII. Chapter, that I would show my conceit of the reason why the needle in his passage from the aequator of the Magnet by the pole, to the aequator again, should make the circumvolution of an whole circle in turning about his foot, having 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 clear this with the nature of the two provinces, which is adverse one unto the other. I would wish that you would conceive and propound two globes of Magnetical nature and substance, as tender as clay, the one of them to be animated with the North and arctic virtue at both poles, as Tab. XX. Fig. 3. aa, to turn to the North only: and the other globe, with his poles Tab. XX. Fig. 3. bb to be endowed with the antarctic power to move to the South only. Now if the globe of the earth, or of the Magnet-stone were made only of one of these globes, than there would be a strife between the poles of one of the globes, which should behold his peculiar point, as if the pole a of the North virtue should behold the North; the other pole a of the same globe, being of arctic nature, would also strive 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 skilful Potter, who made the earth TAM ROBUR. TAM ROBOR. NI-COLIS ARBOR JOVIS. 1610 N O printer's device of Nicholas Okes LONDON, Printed by Nicholas Okes, dwelling near Holborne-bridge, at the sign of the Hand. 1613.