Book VII, chapters 26–42: The wonders of the loadstone

CHAP. XXVI.

The Loadstone within the sphere of its vertue, sends it forth without touching.

ANd the Loadstone doth not onely impart its vertue to the iron, by touching it, but, which is wonderful, within the compass of its vertue, it will impart vertue to the iron, if it be but present, to draw another iron. For if you put your Loadstone so neer to the iron, that it may have it onely within the circumference of its vertue, and you put another iron neer to that iron, it will draw it to it; and if another touch that which is drawn, it will draw that also: that you shall see a long chain of rings or needles, hanging in the air. But when they hang thus together, if you […]emove the Loadstone a little farther off, the last ring will fall; and if yet you remove […] farther, the next will fall, until they all fall off: whence it is clear, that without touching, it can impart its vertue to the iron.

CHAP. XXVII.

How the Loadstone can hang up iron in the air.

I Have a long time endeavoured much to make iron hang in the air, and not touch the Loadstone, nor yet tied beneath: and now I think it almost impossible to be done. Pliny saith it: Dinocrates the Architect began to vault the Temple of Arsinoe with Loadstone, that therein her Image of iron might seem to hang in the air: both he and Ptolomy died, who commanded this to be made for his sister; so that what he began, he did not finish. The Greeks say, that in the Temple of Serapis, that is vaulted at Alexandria, there was a Load-stone set, that held a statue of brass in the air; for it had a piece of iron in the head of it. But that is false, that Mahomets chest hangs by the roof of the Temple. Petrus Pellegrinus saith, he shewed in another work how that might be done: but that work is not to be found. Why I think it extream hard, I shall say afterwards. But I say it may be done, because I have now done it, to hold it fast by an invisible band, to hang in the air; onely so, that it be bound with a small thread beneath, that it may not rise higher: and then striving to catch hold of the stone above, it will hang in the air, and tremble and wag it self.

CHAP. XXVIII.

The forces of the Loadstone cannot be hindred, by a wall or table coming between.

AS I said before of the Loadstone, the vertue of that and iron, can be hindred by no body coming between; but it will do its office. For whilst the Loadstone is moved under a Table of wood, stone, or any metal, except iron; the needle in the Mariners Compass will move above, as if there were no body between them. St. Augustine Lib. de civitate Dei, knew this experiment. But that is much more wonderful that I have heard: that if one hold a Loadstone under a piece of silver, and put a piece of iron above the silver, as he moves his hand underneath that holds the stone, so will the iron move above; and the silver being in the middle, and suffering nothing, running so swiftly up and down, that the stone was pull'd from the hand of the man, and took hold of the iron.

CHAP. XXIX.

How a man of wood may row a little Boat; and some other merry conceits.

THe fraud here is notable; for women shall see a man of wood rowing a little boat well waxed, in a large vessel full of water, and they can counterfeit hereby, as impostors do divination by water. The fraud is thus began: the vessel is filled with water, a little ship of Wax is put into it, or else of wood; in the middle sits a little man of wood, fastned through the middle with a hogs-bristle, so equall balanced, that with every light motion he may easily stir himself: let him have oars in his hands, and under his feet a piece of iron. Let the Alphabet be made on the brim of the vessel, round about: wherefore a woman coming to enquire of some doubtful matter, the little man of wood, as if he would give a true answer, will row to those letters that may signifie the answer: for he that holds the Loadstone in his hand, under the Table, can draw the boat which way he will, and so will answer by joyning these letters together. Or put a boy of cork into a glass viol, with a broad mouth, that turns himself about the needle equally balanced; and about the glass vessel, make the Alphabet, that the man turning round about may give answers. But I made my friends wonder exceedingly to see

A paper go up a wall, and come down of it self.

For I glew'd a piece of iron on the backside of the paper, and I gave it my friends to hold to the wall; but behinde stood a boy with a Loadstone, and the paper that was left there, stood still: my friend commanded it to go up two foot: the boy that heard what was commanded, moved the Loadstone against it, to that place: and the paper moved thither also, and so downwards, or side-ways: they that knew not the reason were astonished at it. But, which exceeds all, when he moved the Loadstone over his head by an arch of wood, it drew the paper after it whereupon the paper hung over our heads and moved: but all that saw it, believed the Divel was the cause of it.

CHAP. XXX.

A Loadstone on a plate of iron, will not stir iron.

WE said that there is nothing coming between, can hinder the force of iron, but iron onely: so that if you lay a needle on a plate of iron, and shall bring your Loadstone to it, above or beneath, it hath no vertue to attract it, or do its office: and the reason is easie. For it stands by reason, that if iron lye upon iron, they are the same body, as a part is of the whole: and when the plate of iron, or piece, is bigger, and too heavy for the Loadstone to draw, it moves not. So that if you put the filings of iron upon a plate of iron, and with your hand underneath, you carry the Loadstone, the filings will not stir, but stand still upon the plate. Nor if iron or a Loadstone be upon a Table of iron, will they come to the stone that is put to them, but will lye as if they were asleep, and void of all vertue, or changed in their Natures. Also, if you put flat iron to a Load stone, if on the other side iron be equally balanced, it will not stir, nor move to meet it; as if all the force of the Loadstone were hindred by it. Lucretius saith, that it will happen so, not when iron, but brass is between them: but I rather think he writ so by hear-say, then by his sight, if we understand his meaning.

Pieces of iron I have seen,
When onely brass was put between
Them and the Loadstone, to recoil:
Brass in the middle made this broil.

CHAP. XXXI.

The position of the Iron, will change the forces.

VVHat the Loadstone can do, the iron touched by the Loadstone, will do the same. I said, that the Loadstone equally balanced, by putting the south part of the Loadstone above, it will draw the north part, and the north part will drive off the north part; but on the lower part, the Nature being changed, that which drew before, drives off now; and that which drove off, draws to it. The same I judge of iron touched with the Loadstone. For iron in the Mariners Compass touched with the Loadstone, that part of the Loadstone that draws and drives off in the upper part, being put under, expels what it drew before, and draws what it expelled. I would not omit, that amongst its admirable properties, the position should cause such alteration. Whence we may conjecture, that as the stone hath a pole-arctick and antarctick; so it hath an east and west part, and its upper and nether part, as the heavens have: and therefore it is reasonable, that whereas the north and inferiour part from above, drew the south and inferiour part of the iron; now the position being changed, the upper part of the stone will draw the nether part of the iron.

CHAP. XXXII.

That the iron rubbed with the northern point of the Loadstone, will turn to the south, and with the south point to the north.

I Come to the third part, that is, to the iron touched with the Loadstone, and they are all wonderful, I say then, that when we know the north point of the stone, and we have rubbed one end of the iron with it, if it be equally balanced, or hung by a thread, or lie freely in a boat, it will turn of it self to the south. And that stands with reason: for the Loadstone imparts its force to the iron. For it is the natural force of the Loadstone, that being balanced equally, it should turn its north point to the north, and his south point to the south. But when it is rubbed on the iron, the upper part of the Loadstone is fastned to the iron; but the lower part that is neer to it, is free'd: wherefore, if you rub the iron with the north part, which fastneth to the iron, and toucheth its external superficies, it will be northern that seems to to be southern, and this south part will turn freely to the north. But contrarily, if you rub the south point against the iron, the south point is fastned to the iron, and the north point is let loose that turns to the north. Wherefore Cardanus speaks false, that the iron touched by the north point, will turn to the north, and that which was touched by the south point, will turn south; for we see the contrary. Yet the iron must be touched with one point, either the north or south point: for if one part bend northward, the other will tend southward; by the use whereof, so large seas are sail'd over, that being the conductor. Our Ancestors sailed, by seeing the sun by day, and the stars by night. For in the middle of the sea, as they wandred, they could no otherwise see the coasts of the world. But we cannot onely discover what coast we are in, but we can avoid the rocks under the waters; and in cloudy days and dark nights, we can at all times know the poles of the world. Flav[…]us saith, an Italian found it out first, whose name was Amalphus, born in our Campania. But he knew not the Mariners Card, but stuck the needle in a reed, or a piece of wood, cross over; and he put the needles into a vessel full of water, that they might flote freely: then carrying about the Loadstone, the needles would follow it; which being taken away, as by a certain natural motion, the points of the needles would turn to the north pole; and having found that, stand still. Wherefore, knowing the place before they steer'd their course thither. Now the Mariners Compass is made, and a needle touched with the Loadstone, is so fitted to it, that by discovering the pole by it, all other parts of the heavens are known. There is made a rundle, with a Latin-navel upon a point of the same metal, that it may run roundly freely. Whereupon, by the touching onely of one end, the needle not alone partakes of the vertues of it, but of the other end also, whether it will or not: For if you rub the needle with the north point of the stone presently that part will turn to the south, and the opposite part to the north; and one vertue cannot be imparted without the other. So the needle touched by the south point of the stone, will turn to the north, and the other part to the south; so that the part of the needle that is touch'd, receives a contrary force, from that the stone hath.

CHAP. XXXIII.

That iron touched by the Loadstone, will impart that force to other iron.

IRon touched by the Loadstone, by that touch receiveth the vertue of the Loadstone, that it will do almost as much by attracting, and effecting, and turning it self to the pole. So the iron hanging freely, touched with the south point of the Loadstone, will turn freely to the north: if you apply the south part of the stone to the same, it will turn to the south presently. But if you touch another iron with the iron that was touched, that will turn to the south; and do but point at it with the said point of the iron, it will turn to the north. And this force is not onely sent into the second iron, but to a third and fourth, as the force of the Loadstone is. For if it be a strong stone, it will send its vertue through eight or ten needles.

CHAP. XXXIV.

The vertue received in the iron, is weakned by one that is stronger.

YEt this I must tell you, that the vertue received by the iron, is not fixt and certain, but is taken off by a stronger that takes it from it. As an iron touched by a weak northern point of the Loadstone; if you rub the same part of the iron with a south point of a stronger Loadstone, it will vanish, and that former force of turning it self to the south, is taken away, and it takes a southern vertue, and will turn to the north without resistance. But if the Loadstones be of equal force, they are so astonished and blunted, that they will neither receive both, nor either.

CHAP. XXXV.

How in a stone the south or north point is discerned.

AMongst those ways I shewed before, I shall set down this also; and perchance this is the best, how to know the true northern and southern points. Let the Loadstone be turned round, by the wheel of the Jewellers, and polished. Then make a slender iron, as long as the axeltre of that round ball, and lay that upon the stone: for it will turn it self upon that line, that points just north and south. Mark the line upon the stone, with some delible paint: do the same on the otherside of the stone; and where it rests upon the ball, draw the same line: do the same the third and fourth time, upon the middle of it: and where those lines cross one the other and meet, those are the polar points. We may also find it out thus: Break a small needle, and put the smallest piece upon the same ball, and stir it; for when it comes to the just northern point, the needle will stand upright, that will make standers by admire, and will stand perpendicularly upon it: and till it do rise thus, be not weary of moving it up and down; for when you have found it, you will be glad of it.

CHAP. XXXVI.

How to rub the iron needle of the Mariners Compass.

I Know that some are troubled how to rub the needle in the Compass with the Loadstone, that it may get force to turn it self to the north Pole. It must be done thus: When you have found the points in the stone, as I said before; strike the points lightly with a hammer, and the plates will be full of stiff hairs: upon which if you rub an iron needle, it will presently get vertue to turn it self to the Poles. Yet observe this, that if you would have your needle turn to the north, you must rub it on the south point; but if to the south, rub it with the north part: For when it is equally balanced, it will turn to these points in the heavens. But that it may do it more forcibly, and do its office more exactly, I shall lay down some rules fit to instruct you. If you strike both ends of the stone with the hammer, that hairs may appear on both parts, that you touch the needle at both ends, for so the needle will sooner do its office. Moreover, you must observe very carefully, that when the iron rub'd against the Loadstone, hath received these hairs, that you touch it with no other iron or Loadstone, but keep it far distant from them, and lock it up in a box; for by touching of others the iron will grow dull, and lose its vertue, that it will never point out the parts of heaven perfectly. For the iron coming within the Compass of the vertue of another Loadstone, will receive that, as we said. So the needle must be proportionable to the stone. For from a little Loadstone, a great iron will not receive much vertue, nor shew the pole: also, a little piece of iron cannot receive much vertue; for it consumes by the great force of the Loadstone. Moreover, the point that shews the pole, must not be sharp, but f[…]at a little, that it may receive those vertues of the Loadstone exactly, and hold them; for in a very sharp point, scarce any vertue will abide. Iron, the purer it is, the better will it hold the vertue. For it will hardly take upon foul and rusty iron: wherefore Mariners make it of pure steel; for steel is made of the best iron. If you observe this, iron once rubbed, will hold the vertue a hundred years; and will certainly, without failing, point exactly at the poles in the heavens, for so long time.

CHAP. XXXVII.

Of the divers uses of Mariners Compasses.

ANd the needle touched, doth not onely shew the poles for the Mariners use, but almost it serves for infinite uses; as all men know that it is dayly spoken of every where. I shall speak of some of the chief. The use of the Loadstone upon the needle, is well known in Sun-dials: for when the needle stands still over the line that is made from north to south, we are so directed by it, to know the hours by the shadow falling from the Gnomon. Also, those that work in Mines use the needle, to find the veins of the metals, which way they run: for in caves under ground, in that posture the needle stands that is touched with the Loadstone, they know the veins of the metals run on that side of the heavens. Also, it doth serve very much for those that describe platforms of buildings, cities, countries, whilst the situation of the corners are taken and described upon the paper. We use it also in making passages, for to bring water under ground, in digging pits, in making Mines and Trenches, wherewith they use, with great skill, to blow up Forts, Castles, Rocks and Walls, by putting Gunpowder into them, and stopping all places of vent: the Compass guides them how to go on. Lastly, how to level the discharging of Canon, both by night and day, it is of singular vertue, and for many other uses, too tedicus to relate here.

CHAP. XXXVIII.

How the Longitude of the world, may be found out by help of the Loadstone.

I Will not omit, that amongst the principal uses of the Loadstone, by the help of it the Longitude of the world may be found out. Which notable work hath employed the wits of the most knowing men. It hath been observed a long time by our men, that the needle touched with the Loadstone, will not always rest upon the Meridian line, but sometimes will decline nine degrees from it to the east; nor will it hold the same posture in all places; but in divers places, it hath divers declinations. But this errour seems to follow this order, that the neerer it is to the east, the more it will decline from the Meridian line, toward the east; and the neerer it comes to the west, the point of the needle will decline the more to the west. For finding the Meridian line, as Ptolomy and other Geometricians teach how, and setting up a point thereon, that the steel needle may turn freely upon the top of it, in Italy it declines toward the east nine degrees, of which there is ninety in a quadrant of a circle, as it is observed in Sun-dials that are brought out of Germany, and it is so described. Moreover, many famous travellers report, that amongst the Fortunate Islands, one is called the Azores, where the needle set in the Compass, will rest directly upon the Meridian line, without any variation at all. Also, they that sail to the west-Indies observe, that the point of the needle will decline to the west. Therefore, laying down these for true Maxims, we may easily know the longitude of the world: for if we make a very great Compass, about five foot diameter, and divide the degrees and minutes, into seconds and thirds, &c. and sailing under the Equator, we do observe the chief motions of the Needle, and the declinations of it, and shall accommodate the same to the proportion of our Voyages; we shall easily know the Longitude of the World, beginning from the Fortunate Islands. Whence both Longitude and Latitude in dark nights, and the greatest Tempests may be certainly discovered Wherefore it is false that Cardanus saith, That the Needle in the Compass declines from the Meridian Line, because it inclines to the Pole Star in the little Bears Tail: whereas, the Needle declines nine Degrees, and the Polar Inclination is not so much.

CHAP. XXXIX.

If the Mariners Needle stand still, and the Loadstone move, or contralily, they will move contrary ways.

IF the Loadstone lie on the Table, and you put the North point of the Mariners Needle to the South point of the stone, and shall carry it round about by the right hand, the Needle will draw to the left: but moving the Box to the left hand, the Needle will run to the right; and it will go so far, until it stand in the middle between those two opposite points. The same will be seen in a Sun-Dial, if that stand, and the Loadstone be carried about: for if you decline to the right hand, the Needle will follow the same part; and likewise, if you turn to the left. Hence it is apparent, That the Needle in the Compass is drawn by the North-Pole: for those that sail toward the East, have it turned toward the East; and so contrarily to the West, it will move to the same point of the Heaven: and if the Loadstone be turned about, the Iron will turn about also, as a pair of Compasses about the Centre.

CHAP. XL.

The Loadstone imparts a contrary force to the Needle.

NOw I will speak of the Needle touched with the Loadstone, and of the wonderful operations of it. The first is; That when the Iron is touched by the Northern point of the Loadstone, and equally balanced; if you put that part to it from which it received its force, it will not endure it, but drives it from it, and draws to it the contrary and opposite part; namely, the Southern part: the reason whereof, I set down before. The same falls out if you touch the Needle with the South part of the Loadstone: for if you presently put the same to it, it will resist it, and draw to it the North point. Hence the parts that are alike, are at enmity, and rejected as Adversaries; and the parts that are unlike do agree as Friends. Whence it is apparent, That the Loadstone imparts to the Iron a contrary force from what the end it self is, and the Steel receives the force of that point of the Loadstone which it toucheth not. And I prove it thus: Take two Needles, and put them in Boats, or hang them by Threeds; that being touched with the Loadstone, they may move freely: they are contrary one to the other, and they will joyn in the parts that were touched with contrary ends of the Loadstone, and will not endure the ends that are alike.

CHAP. XLI.

Two Needles touched by the Loadstone, obtain contrary Forces.

I Will relate a strange thing, yet not far from Reason. If you touch two Needles with a Loadstone together, and set them on the same point of it; the other parts that hang on the Loadstone, will abhor and flie one from the other: and if you force them together with your hands, so soon as you let them alone, they will presently return to their postures, and depart as far as they can from one another. The reason is this: That if two Needles stick fast to one Northern point of the Loadstone, with their points: you must imagine, that they did receive a Southern vertue; and because they are of the same similitude, they will not endure one the other; and because they are fastened to the Loadstone, they cannot get off being compelled by a greater force: but the opposite points of the Needle, because they are both alike Northerly, they must needs abhor one the other: and when they are free, one will part from the other. And when they are so hanging on, if you put to them the Southern part of another Loadstone, they will presently let go their hold, and go as far off as they can, that sometimes they are pulled off from the Loadstone, being forced by an invisible vapor.

CHAP. XLII.

That the force of the Iron that draws, will drive off Iron by diversity of Situation,

THat, as I said of the Loadstone alone, is true of the Iron that is touched with it: for if you put a Needle touched with a Loadstone by a Boat, swimming in the Water, or hanged by a Threed, or turning on a point equally balanced: if you put upon this a Needle touched with a Loadstone, it will draw it: and that part that attracted the Iron above, will put underneath, drive it away; and the part that drives off above, will draw to it, put underneath: where you may observe, that the position will work contrary operations.