part 32 spaces (which are commonly called _points_) are assigned to the
same number of mathematical intervals in the horizon or winds which are distinguished by certain marks and by a lily indicating the north. The bowl is suspended in the plane of the horizon in æquilibrium in a brass ring which also is itself suspended transversely in another ring within a box sufficiently wide with a leaden weight attached; hence it conforms to the plane of the horizon even though the ship be tossed to and fro by the waves. The iron works are either a pair with their ends united, or else a single one of a nearly oval shape with projecting ends, which does its work more certainly and more quickly. This is to be fitted to the cardboard circle so that the centre of the circle may be in the middle of the magnetick iron. But inasmuch as variation arises horizontally from the point of the meridian which cuts the horizon at right angles, therefore on account of the variation the makers in different regions and cities mark out the mariners' compass in different ways, and also attach in different ways the magnetick needles to the cardboard circle on which are placed the 32 divisions or points. Hence there are commonly in Europe 4 different constructions and forms. First that of the States on the Mediterranean Sea, Sicily, Genoa, and the Republick of Venice. In all these the needles are attached under the rose or lily on the cardboard versorium, so that (where there is no variation) they are directed to the true north and south points. Wherefore the north part marked with the lily always shows exactly the point of variation when the apex itself of the lily on the movable circle, together with the ends of the magnetick wires attached below, rests at the point of variation. Yet another is that of Dantzig, and throughout the Baltic Sea, and the Belgian provinces; {166} in which the iron works fixed below the circle diverge from the lily ¼ of a rumbe to the east. For navigation to Russia the divergency is 2/3. But the compasses which are made at Seville, Lisbon, Rochelle, Bordeaux, Rouen, and throughout all England have an interval of ½ a rumbe. From those differences most serious errors have arisen in navigation, and in the marine science. For as soon as the bearings of maritime places (such as promontories, havens, islands) have been first found by the aid of the mariners' compass, and the times of sea-tide or high water determined from the position of the moon over this or that point (as they say) of the compass, it must be further inquired in what region or according to the custom of what region that compass was made by which the bearings of those places and the times of the sea-tides were first observed and discovered. For one who should use the British compass and should follow the directions of the marine charts of the Mediterranean Sea would necessarily wander very much out of the straight course. So also he that should use the Italian compass in the British, German, or Baltic Sea, together with marine charts that are made use of in those parts, will often stray from the right way. These different constructions have been made on account of the dissimilar variations, so that they might avoid somewhat serious errors in those parts of the world. But Pedro Nuñez seeks the meridian by the mariners' compass, or versorium (which the Spanish call the needle), without taking account of the variation: and he adduces many geometrical demonstrations which (because of his slight use and experience in matters magnetical) rest on utterly vicious foundations. In the same manner Pedro de Medina, since he did not admit variation, has disfigured his _Arte de Navegar_ with many errors.
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CHAP. IX.
Whether the terrestrial longitude can be found from _the variation_.
Grateful would be this work to seamen, and would bring the greatest advance to Geography. But B. Porta in chap. 38 of book 7 is mocked by a vain hope and fruitless opinion. For when he supposes that the magnetick needle would follow order and proportion in moving along meridians, so 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 {167} point of the needle will decline the more to the west" (which is totally untrue), he thinks that he has discovered a true index of longitude. But he is mistaken. Nevertheless, admitting and assuming these things (as though they were perfectly true), he makes a large compass indicating degrees and minutes, by which these proportional changes of the versorium might be observed. But those very principles are false, and ill conceived, and very ill considered; for the versorium does not turn more to the east because a journey is made toward the east: and although the variation in the more westerly parts of Europe and the adjoining ocean is to the east and beyond the Azores is changed a little to the west, yet the variation is, in various ways, always uncertain, both on account of longitude and of latitude, and because of the approach toward extensive tracts of land, and also because of the form of the dominant terrestrial eminences; nor does it, as we have before demonstrated, follow the rule of any particular meridian. It is with the same vanity also that Livio Sanuto so greatly torments himself and his readers. As for the fact that the crowd of philosophizers and sailors suppose that the meridian passing through the Azores marks the limits of variation, so that on the other and opposite side of that meridian a magnetick body necessarily respects the poles exactly, which is also the opinion of Joannes Baptista Benedictus and of many other writers on navigation, it is by no means true. Stevinus (on the authority of Hugo Grotius) in his _Havenfinding Art_ distinguishes the variation according to the meridians: "It may be seene in the Table of variations, that in _Coruo_ the Magneticall needle pointeth due North: but after that, the more a man shal goe towards the East, so much the more also shall he see the needle varie towards the East [[Greek: anatolizein]], till he come one mile to the Eastward from _Plimouth_, where the variation comming to the greatest is 13 degr. 24 min. From hence the Northeasting [Anatolismus] beginneth to decrease, til you come to _Helmshude_ (which place is Westward from the North Cape of Finmark) where againe the needle pointeth due North. Now the longitude from _Coruo_ to _Helmshude_ is 60 degr. Which things being well weighed, it appeareth that the greatest variation [Chalyboclysis] 13 degr. 24 minutes at _Plimmouth_ (the longitude whereof is 30 degr.) is in the midst betweene the places where the needle pointeth due North." But although this is in some part true in these places, yet it is by no means true that along the whole of the meridian of the island of Corvo the versorium looks truly to the north; nor on the meridian of Plymouth is the variation in other places 13 deg. 24 min.--nor again in other parts of the meridian of Helmshuda does it point to the true pole. For on the meridian passing through Plymouth in Latitude 60 degrees the North-easterly variation is greater: in Latitude 40 deg. much less; in Latitude 20 deg. very small indeed. On the meridian of Corvo, although there is no variation near the {168} island, yet in Latitude 55 degrees the variation is about ½ a rumbe to the North-west; in Latitude 20 deg. the versorium inclines ¼ of a rumbe toward the East. Consequently the limits of variation are not conveniently determined by means of great circles and meridians, and much less are the ratios of the increment or decrement toward any part of the heavens properly investigated by them. Wherefore the rules of the abatement or augmentation of Northeasting or Northwesting, or of increasing or decreasing the magnetick deviation, can by no means be discovered by such an artifice. The rules which follow later for variation in southern parts of the earth investigated by the same method are altogether vain and absurd. They were put forth by certain Portuguese mariners, but they do not agree with the observations, and the observations themselves are admitted to be bad. But the method of haven-finding in long and distant voyages by carefully observed variation (such as was invented by Stevinus, and mentioned by Grotius) is of great moment, if only proper instruments are in readiness, by which the magnetick deviation can be ascertained with certainty at sea.
* * * * *
CHAP. X.
Why in various places near the pole the variations are much more ample than in a _lower latitude_.
Variations are often slight, and generally null, when the versorium is at or near the earth's æquator. In a higher Latitude of 60, 70 or 80 deg. there are not seldom very wide variations. The cause of this is to be sought partly from the nature of the earth and partly from the disposition of the versorium. The earth turns magnetick bodies and at the æquator directs them strongly toward the pole: [227]at the poles there is no direction, but only a strong coition through the congruent poles. Direction is therefore weaker near the poles, because by reason of its own natural tendency to turn, the versorium dips very much, and is not strongly directed. But since the force of those elevated lands is more vigorous, for the virtue flows from the whole globe, and since also the causes of variation are nearer, therefore the versorium deflects the more from its true direction toward those eminences. It must also be known that the direction of the versorium on its pin along the plane of the Horizon is much stronger at the æquator than anywhere else by reason of the disposition of the {169} versorium; and this direction falls off with an increase of latitude. For on the æquator the versorium is, following its natural property, directed along the plane of the horizon; but in other places it is, contrary to its natural property, compelled into æquilibrium, and remains there, compelled by some external force: because it would, according to its natural property, dip below the horizon in proportion to the latitude, as we shall demonstrate in the book _On Declination_. Hence the direction falls off and at the pole is itself nothing: and for that reason a feebler direction is easily vanquished by the stronger causes of variation, and near the pole the versorium deflects the more from the meridian. It is demonstrated by means of a terrella: if an iron wire of two digits length be placed on its æquator, it will be strongly and rapidly directed toward the poles along the meridian, but more weakly so in the mid-intervals; while near the poles one may discern a precipitate variation.
* * * * *
CHAP. XI.
Cardan's error when he seeks the distance of the _centre of the earth from the centre of the cosmos by the_ motion of the stone of Hercules; in his _book 5, On Proportions_.
One may very easily fall into mistakes and errors when one is searching into the hidden causes of things, in the absence of real experiments, and this is easily apparent from the crass error of Cardan; who deems himself to have discovered the distances of the centres of the cosmos and of the earth through a variation of the magnetick iron of 9 degrees. For he reckoned that everywhere on the earth the point of variation on the Horizon is always distant nine degrees from the true north, toward the east: and from thence he forms, by a most foolish error, his demonstrative ratio of the separate centres.
* * * * *
{170} CHAP. XII.
On the finding of the amount of variation: how great _is the arc of the Horizon from its arctick or antarctick_ intersection of the meridian, to the point _respective of the magnetick needle_.
Virtually the true meridian is the chief foundation of the whole matter: when that is accurately known, it will be easy by a mariners' compass (if its construction and the mode of attachment of the magnetick iron works are known) or by some other larger horizontal versorium to exhibit the arc of variation on the Horizon. By means of a sufficiently large nautical variation compass (two equal altitudes of the sun being observed before and after midday), the variation becomes known from the shadow; the altitude of the sun is observed either by a staff or by a rather large quadrant.
On land the variation is found in another way which is easier, and because of the larger size of the instrument, more accurate. Let a thick squared board be made of some suitable wood, the surface of which is two feet in length and sixteen inches in width: describe upon it some semicircles as in the following figure, only more in number. In the centre let a brass style be reared perpendicularly: let there be also a movable pointer reaching from the centre to the outmost semicircle, and a magnetick versorium in a cavity covered over with glass: then let the board be exactly adjusted to the level of the Horizon by the plane instrument with its perpendicular; and turn the lily of the instrument toward the north, so that the versorium may rest truly over the middle line of the cavity, which looks toward the point of variation on on the Horizon. Then at some convenient hour in the morning (eight or nine for instance) observe the apex of the shadow thrown by the style when it reaches the nearest semicircle and mark the place of the apex of this shadow with chalk or ink: then bring round the movable index to that mark, and observe the degree on the Horizon numbered from the lily, which the index shows. In the afternoon see when the end of the shadow shall again reach the periphery of the same semicircle, and, bringing the index to the apex of the shadow, seek for the degree on the other side of the lily. From the difference of the degrees becomes known [Illustration] {172} the variation; the less being taken from the greater, half the remainder is the arc of variation. The variation is sought by many other instruments and methods in conjunction with a convenient mariners' compass; also by a globe, by numbers, and by the ratios of triangles and sines, when the latitude is known and one observation is made of the sun's altitude: but those ways and methods are of less use, for it is superfluous to try to find in winding and roundabout ways what can be more readily and as accurately found in a shorter one. For the whole art is in the proper use of the instruments by which the sun's place is expeditiously and quickly taken (since it does not remain stationary, but moves on): for either the hand trembles or the sight is dim, or the instrument makes an error. Besides, to observe the altitude on both sides of the meridian is just as expeditious as to observe on one side only and at the same time to find the elevation of the pole. And he who can take one altitude by the instrument can also take another; but if the one altitude be uncertain, then all the labour with the globe, numbers, sines and triangles is lost; nevertheless those exercises of ingenious mathematicians are to be commended. It is easy for anyone, if he stand on land, to learn the variation by accurate observations and suitable instruments, especially in a nearly upright sphere; but on the sea, on account of the motion and the restlessness of the waters, exact experiments in degrees and minutes cannot be made: and with the usual instruments scarcely within the third or even the halt of a rumbe, especially in a higher latitude; hence so many false and bad records of the observations of navigators. We have, however, taken care for the finding of the deviation by a sufficiently convenient and ready instrument, by means of the rising of certain stars, by the rising or setting of the sun, and in northern regions by the Pole Star: for the variation is learned with greater certainty even by the skilful with an instrument which is at once simple and less sensitive to the waves of the sea. Its construction is as follows.
[228]Let an instrument be made of the form of a true and meridional mariners' compass of at least one foot in diameter (with a versorium which is either nude or provided with a cardboard circle): let the limb be divided into four quadrants, and each quadrant into 90 degrees. The movable compass-box (as is usual in the nautical instrument) is to be balanced below by a heavy weight of sixteen pounds. On the margin of the suspended compass-box, where opposite quadrants begin, let a half-ring rising in an angular frame in the middle be raised (with the feet of the half-ring fixed on either side in holes in the margin) so that the top of the frame may be perpendicular to the plane of the compass; on its top let a rule sixteen digits in length be fastened at its middle on a joint like a balance beam, so that it may move, as it were, about a central axis. At the ends of the rule there are small plates with holes, {173} [Illustration] {174} through which we can observe the sun or stars. The variation is best observed and expeditiously by this instrument at the equinoxes by the rising or setting sun. But even when the sun is in other parts of the zodiack, the deviation becomes known when we have the altitude of the pole: that being known, one can learn the amplitude on the Horizon and the distance from the true east both of the sun and of the following fixed stars by means of a globe, or tables, or an instrument. Then the variation readily becomes known by counting from the true east the degrees and minutes of the amplitude at rising. Observe the preceding star of the three in the Belt of Orion as soon as it appears on the horizon; direct the instrument toward it and observe the versorium, for since the star has its rising in the true east about one degree toward the south, it can be seen how much the versorium is distant from the meridian, account being taken of that one degree. You will also be able to observe the arctick pole star when it is on the meridian, or at its greatest distance from the meridian of about three degrees (the pole star is distant 2 deg. 55 min. from the pole, according to the observations of Tycho Brahe), and by the instrument you will learn the variation (if the star be not on the meridian) by adding or subtracting, _secundum artem_, the proper reduction [_prostaphæresis_][229] of the star's distance from the meridian. You will find when the pole star is on the meridian by knowing the sun's place and the hour of the night: for this a practised observer will easily perceive without great error by the visible inclination of the constellation: for we do not take notice of a few minutes, as do some who, when they toil to track the minutes of degrees at sea, are in error by a nearly whole rumbe. A practised observer will, in the rising of sun or stars, allow something for refraction, so that he may be able to use a more exact calculation.
Bright and conspicuous stars[230] which are _not far distant from the equator which it will be useful to observe at their rising and setting: the amplitude at the Horizon on rising being known from the altitude of the pole and from the declination of the stars, by means of a globe, or tables, or an instrument whence the variation is perceived by technical calculation._
{175}
_Right Ascension_ _Declination_ |Oculus Tauri | 62° 55' | 15° 53' N | |Sinister humerus Orionis | 72° 24' | 4° 5' N | |Dexter humerus Orionis | 83° 30' | 6° 19' N | |Præcedens in cingulo Orionis | 77° 46' | 1° 16' S | |Canis major | 97° 10' | 15° 55' S | |Canis minor | 109° 41' | 5° 55' N | |Lucida Hydræ | 137° 10' | 5° 3' S | |Caput Geminorum australe | 110° 21' | 28° 30' N | |Caput boreale | 107° 4' | 32° 10' N | |Cor Leonis | 146° 8' | 13° 47' N | |Cauda Leonis | 171° 38' | 16° 30' N | |Spica Virginis | 195° 44' | 8° 34' S | |Arcturus | 29° 13' | 21° 54' N | |Cor Aquilæ | 291° 56' | 7° 35' N |
_An instrument for finding the amplitude at rising on the horizon._
Describe the circumference of a circle and let it be divided into quadrants by two diameters intersecting each other at right angles at its centre. One of these will represent the æquinoctial circle, the other the axis of the world. Let each of these quadrants be divided (in the accustomed way) into 90 degrees; on every fifth or tenth of which at each end of each diameter and on each side let marks (showing the numbers) be inscribed on the two limbs or margins made for that purpose outside the circumference. Then from each degree straight lines are drawn parallel to the æquator. You will then prepare a rule or alhidade equal to the diameter of that circle and divided throughout into the same parts into which the diameter of the circle representing the axis of the world is divided. Let there be left a small appendage attached to the middle of the rule, by which the middle of the fiducial line itself of the rule may be connected with the centre of the circle: but to every fifth or tenth part of that rule let numbers be attached proceeding from the centre toward each side. This circle represents the plane of the meridian; its centre the actual point of east or west, _i.e._, the common intersection of the horizon and æquator; all those lines æquidistant from the æquator denote the parallels of the sun and stars; the fiducial line of the rule or alhidade represents the horizon; and its parts signify the degrees of the horizon, beginning from the point of setting or of rising. {176}
Therefore if the fiducial line of the rule be applied to the given latitude of the place reckoned from either end of that diameter which represents the axis of the world; and if further the given declination of the sun or of some star from the æquator (less than the complement of the latitude of the place) be found on the limb of the instrument; then the intersection of the parallel drawn from that point of the declination with the horizon, or with the fiducial line of the rule or alhidade, will indicate for the given latitude of the place the amplitude at rising of the given star or the sun.
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{177} CHAP. XIII.
The observations of variation by seamen vary, for the _most part, and are uncertain: partly from error and inexperience_, and the imperfections of the instruments; and partly _from the sea being seldom so calm that the shadows or lights can remain quite steady on the instruments_.
After the variation of the compass had first been noticed, some more diligent navigators took pains to investigate in various ways the difference of aspect of the mariners' compass. Yet, to the great detriment of the nautical art, this has not been done so exactly as it ought to have been. For either being somewhat ignorant they have not understood any accurate method or they have used bad and absurd instruments, or else they merely follow some conjecture arising from an ill-formed opinion as to some prime meridian or magnetick pole; whilst others again transcribe from others, and parade these observations as their own; and they who, very unskilful themselves, first of all committed their observations to writing are, as by the prerogative of time, held in esteem by others, and their posterity does not think it safe to differ from them. Hence in long navigations, especially to the East Indies, the records by the Portuguese of the deviating compass are seen to be unskilful: for whoever reads their writings will easily understand that they are in error in very many things, and do not rightly understand the construction of the Portuguese compass (the lily of which diverges by half a rumbe from the needles toward the west), nor its use in taking the variation. Hence, while they show the variation of the compass in different places, it is uncertain whether they measure the deviation by a true meridional compass or by some other whose needles are displaced from the lily. The Portuguese (as is patent in their writings) make use of the Portuguese compass, whose magnetick needles are fixed aside from the lily by half of one rumbe toward the east. Moreover on the sea the observation of the variation is a matter of great difficulty, on account of the motion of the ship and the uncertainty of the deviation, even with the more skilful observers, if they use the best made instruments hitherto known and used. Hence there arise different opinions concerning the magnetick deviation: as, for instance, near the Island of St. Helena the Portuguese Rodriguez de {178} Lagos measures half a rumbe. The Dutch in their nautical log fix it at a whole rumbe. Kendall, the expert Englishman, with a true meridional compass admits only a sixth part of a rumbe. A little to the East of Cape Agullias Diego Alfonso makes no variation, and shows by an Astrolabe that the compass remains in the true meridian. Rodriguez shows that the compass at Cape Agulhas has no variation if it is of Portuguese construction, in which the needles are inclined half a rumbe to the East. And there is the same confusion, negligence, and vanity in very many other instances.
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CHAP. XIIII.
On the variation under the æquinoctial line, _and near it_.
In the North the magnetick needle varies because of the Boreal eminences of the continent; in the South because of the Austral; at the æquator, if the regions on both sides were equal, there would be no variation. But because this rarely happens some variation is often observed under the æquator; and even at some distance from the æquator of three or 4 degrees toward the North, there may be a variation arising from the south, if those very wide and influential southern continents be somewhat near on one side.
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CHAP. XV.
The variation of the magnetick needle in the great Æthiopick and American sea, beyond _the æquator_.
Discourse hath already been had of the mode and reason of the variation in the great Atlantick Ocean: but when one has advanced beyond the æquator off the east coast of Brazil the magnetick needle turns aside toward the mainland, namely, with that end of it which points to the south; so that with that end of the versorium it deviates from the true meridian toward the west; which navigators observe at the other end and suppose a variation to occur toward the east. But throughout the whole way from the first promontory on the east of Brazil, by {179} Cape St. Augustine and thence to Cape Frio, and further still to the mouth of the Strait of Magellan, the variation is always from the south toward the west with that end of the versorium which tends toward the antarctick pole. For it is always with the accordant end that it turns toward a continent. The variation, however, occurs not only on the coast itself, but at some distance from land, such as a space of fifty or sixty German miles or even more. But when at length one has progressed far from land, then the arc begins to diminish: for the magnetick needle turns aside the less toward what is too far off, and is turned aside the less from what is present and at hand, since it enjoys what is present. In the Island of St. Helena (the longitude of which is less than is commonly marked on charts and globes) the versorium varies by one degree or nearly two. The Portuguese and others taught by them, who navigate beyond the Cape of Good Hope to the Indies, set a course toward the Islands of Tristan d'Acunha, in order that they may enjoy more favourable winds; in the former part of their course the change of variation is not great; but after they have approached the islands the variation increases; and close to the islands it is greater than anywhere else in the whole course. For the end of the versorium tending to the south (in which lies the greatest source of the variation) is caught and allured toward the south-west by the great promontory of the southern land. But when they proceed onward toward the Cape of Good Hope the variation diminishes the more they approach it. But on the prime meridian in the latitude of 45 degrees, the versorium tends to the south-east: and one who navigates near the coast from Manicongo to the tropick, and a little beyond, will perceive that the versorium tends from the south to the east, although not much. At the promontory of Agulhas it preserves slightly the variation which it showed near the islands of d'Acunha, which nevertheless is very much diminished because of the greater remoteness from the cause of variation, and consequently there the southern end of the versorium does not yet face exactly to the pole.
* * * * *
CHAP. XVI.
On the variation in Nova Zembla.
Variations in parts near the pole are greater (as has been shown before) and also have sudden changes, as in former years the Dutch explorers observed not badly, even if those observations were not exact--which indeed is pardonable in them; for with the usual instruments it is with difficulty {180} that the truth becomes known in such a high latitude (of about 80 degrees). Now, however, from the deviation of the compass the reason for there being an open course to the east by the Arctick Ocean appears manifest; for since the versorium has so ample a variation toward the north-west, it is demonstrable that a continent does not extend any great distance in the whole of that course toward the east. Therefore with the greater hope can the sea be attempted and explored toward the east for a passage to the Moluccas by the north-east than by the north-west.
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CHAP. XVII.
Variation in the Pacifick Ocean.
Passing the Strait of Magellan the deviation on the shore of Peru is toward the south-east, _i.e._, from the south toward the east. And a similar deflection would be continued along the whole coast of Peru as far as the æquator. In a higher latitude up to 45 deg. the variation is greater than near the æquator; and the deflection toward the south-east is in nearly the same proportion as was the deviation from the south toward the west on the eastern shore of South America. From the æquator toward the North there is little or no variation until one comes to New Galicia; and thence along the whole shore as far as Quivira the inclination is from the north toward the east.
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CHAP. XVIII.
On the variation in the Mediterranean Sea.
Sicilian and Italian sailors think that in the Sicilian Sea and toward the east up to the meridian of the Peloponnesus (as Franciscus Maurolycus relates) the magnetick needle "græcizes," that is, turns from the pole toward what is called the greek wind or Boreas; that on the shore of the Peloponnesus it looks toward the true pole; but that when they have proceeded further east, then it "mistralizes," because it tends from the pole toward the mistral or north-west wind: which agrees with our rule for the variation. For as the Mediterranean Sea is extended toward the west from that meridian, so on the side {181} toward the east the Mediterranean Sea lies open as far as Palestine; as toward North and East lie open the whole Archipelago and the neighbouring Black Sea. From the Peloponnesus toward the north pole the meridian passes through the largest and most elevated regions of all Europe; through Achaia, Macedonia, Hungary, Transylvania, Lithuania, Novogardia, Corelia and Biarmia.
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CHAP. XIX.
The variation in the interior of large _Continents_.
Most of the great seas have great variations; in some parts, however, they have none, but the true directions are toward the pole. On continents, also, the magnetick needle often deviates from the meridian, as on the edge of the land and near the borders; but it is generally accustomed to deviate by a somewhat small arc. In the middle, however, of great regions there are no variations. Hence in the middle lands of Upper Europe, in the interior of Asia, and in the heart of Africa, of Peru, and in the regions of North or Mexican America, the versorium rests in the meridian.
* * * * *
CHAP. XX.
Variation in the Eastern Ocean.
Variation in the Eastern Ocean throughout the whole voyage to Goa and the Moluccas is observed by the Portuguese; but they err greatly in many things, following, as they do, the first observers who note down variations in certain places with ill-adapted instruments, and by no means accurate observations, or by some conjectures. As, for instance, in Brandöe Island, they make the versorium deviate by 22 degrees to the north-west. For in no region or place in the whole world, of not greater latitude, is there so great a deviation; and, in reality, there the deviation is slight. Also when they make out that at Mosambique the compass deviates by one rumbe to the north-west, it is false; even though they use (as they are accustomed to do) the Portuguese compass: for beyond all doubt on the shore of {182} Mosambique the versorium inclines ¼ rumbe or even more to the south-west. Very wrongly also beyond the æquator in the course to Goa they make the little compass incline by 1½ rumbe to the west: whereas they should rather have said that in the first part of the course the Portuguese compass inclines by 1 rumbe: but that the true meridional compass inclines by ½ rumbe only. In order that the amount of variation in the Eastern Ocean may be accurately settled in most places by our rules, there is needed a more exact and truer survey of the southern land, which spreads out from the south to the æquinoctial more than is commonly described on maps and globes.
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CHAP. XXI.
How the deviation of the versorium is augmented and _diminished by reason of the distance of places_.
In the middle of great and continent lands there is no variation. Nor, generally, in the middle of very great seas. On the margin of those lands and seas the variation is often ample, yet not so great as at a little further distance on the sea. As, for example, near Cape St. Augustine the compass varies; but at 50 miles from land toward the East it varies more; and 80 miles off it varies still more; and yet still more at a distance of 100 miles. But from a distance of 100 miles the diminutions of deviation are slower, when they are navigating toward the mainland, than at a distance of 80 miles, and at a distance of 80 miles than at 50: for the deviations change and are diminished rather more swiftly the more they approach and draw near land than when at a great distance off. As, for instance, navigating toward Newfoundland the change of variation is more rapid (that is, it decreases a degree in a smaller arc of the course on the parallel) when they are not far from land than when they are a hundred miles distant: but when travelling on land toward the interiors of regions the changes are slower in the first parts of the journey than when they come more into the interior.
The ratio of the arcs on a parallel circle, when a versorium is moved toward continents which extend to the pole, corresponds with the degrees of variation. Let A be the pole; B the eminences of the dominant lands; at C there is no variation caused by B, for it is too far away; at D the variation is very great because the versorium is allured or turned by the whole earth toward the eminent {183} land B; and moreover it is not hindered, or restrained or brought back to the pole by the verticity of the earth; but, tending of its own nature to the pole, it is nevertheless deflected from it by reason of the site, or position, and convenient distance of the dominant and high lands.
Now from C toward D the variation increases; the versorium, however, does not deviate so rapidly in the first spaces as near D: for more miles are traversed on the parallel circle C D, near C, in order that the versorium may deviate by one degree from the pole A, than near D. So also in order that the variation may be diminished from D toward E more miles are required near D than near E. Thus the deviations become equal in unequal courses, whether the variation be increasing or decreasing; and yet the variation decreases by lesser intervals than it increases. There intervene, however, many other causes which perturb this proportion.
* * * * *
{184} [Illustration]
BOOK FIFTH.
_CHAP. I._
ON DECLINATION.
In due course we have now come to that notable experiment, and remarkable motion of magnetick bodies dipping below the horizon by their own rotatory nature; by the knowledge of which is revealed a unity, a concordancy, and a mutual agreement between the terrestrial globe and the loadstone (or the magnetick iron), which is wonderful in itself, and is made manifest by our teaching. This motion we have made known in many striking experiments, and have established its rules; and in the following pages we shall demonstrate the causes of it, in such a way that no sound, logical mind can ever rightly set at nought or disprove our chief magnetick principles. Direction, as also variation, is demonstrated in a horizontal plane, when a balanced magnetick needle comes to rest at some definite point; but declination is seen to be the motion of a needle, starting from that point of the horizon, first balanced on its own axis, then excited by a loadstone, one end or pole of it tending toward the centre of the earth. And we have found that it takes place in proportion to the latitude of each region. But that motion arises in truth, not from any motion from the horizon toward the centre of the earth, but from the turning of the whole magnetick body toward the whole of the earth, as we shall show hereafter. Nor does the iron dip from the horizontal in some oblique sphere, according to the number of degrees of elevation of the pole in the given region, or by an equal arc in the quadrant, as will appear hereafter. {185}
Instrument of the Declination
{186} Now how much it dips at every horizon may be ascertained in the first place by a contrivance, which, however, is not so easily made as is that in dials for measuring time, in which the needle turns to the points of the horizon, or in the mariners' compass. From a plank of wood let a smooth and circular instrument be prepared, at least six digits in diameter, and affix this to the side of a square pillar, which stands upright on a wooden base. Divide the periphery of this instrument into 4 quadrants: then each quadrant into 90 degrees. At the centre of the instrument let there be placed a brass peg, at the centre of the end of which let there be a small hollow, well polished. To this wooden instrument let a brass circle or ring be fixed, about two digits in width, with a thin plate or flat rod of the same metal, representing the horizon, fixed across it, through the middle of the circle. In the middle of the horizontal rod let there be another hollow, which shall be exactly opposite the centre of the instrument, where the former hollow was made. Afterward let a needle be fashioned out of steel, as versoria are accustomed to be made. Divide this at right angles by a thin iron axis (like a cross) through the very middle and centre of the wire and the cross-piece. Let this dipping-needle be hung (with the ends of the cross resting in the aforesaid holes) so that it can move freely and evenly on its axis in the most perfect æquilibrium, so accurately that it turns away from no one point or degree marked on the circumference more than from another, but that it can rest quite easily at any. Let it be fixed upright to the front part of the pillar, whilst at the edge of the base is a small versorium to show direction. Afterward touch the iron, suspended by this ingenious method, on both ends with the opposite ends of a loadstone, according to the scientifick method, but rather carefully, lest the needle be twisted in any way; for unless you prepare everything very skilfully and cleverly, you will secure no result. Then let another brass ring be prepared, a little larger, so as to contain the former one; and let a glass or a very thin plate of mica be fitted to one side of it. When this is put over the former ring, the whole space within remains inclosed, and the versorium is not interfered with by dust or winds. Dispose the instrument, thus completed, perpendicularly on its base, and with the small versorium horizontal, in such a way that, while standing perpendicularly, it may be directed toward the exact magnetical point respective. Then the end of the needle which looks toward the north dips below the horizon in northern regions, whilst in southern regions the end of the needle which looks toward the south tends toward the centre of the earth, in a certain proportion (to be explained afterward) to the latitude of the district in question, from the æquator on either side. The needle, however, must be rubbed on {187} a powerful loadstone; otherwise it does not dip to the true point, or else it goes past it, and does not always rest in it. A larger instrument may also be used, whose diameter may be 10 or 12 digits; but in such an instrument more care is needed to balance the versorium truly. Care must be taken that the needle be of steel; also that it be straight; likewise that both ends of the cross-piece be sharp and fixed at right angles to the needle, and that the cross-piece pass through the centre of the needle. As in other magnetical motions there is an exact agreement between the earth and the stone, and a correspondence manifestly apparent to our senses by means of our experiments; so in this declination there is a clear and evident concordance of the terrestrial globe with the loadstone. Of this motion, so important and so long unknown to all men, the following is the sure and true cause. A magnet-stone is moved and turned round until one of its poles being impelled toward the north comes to rest toward a definite point of the horizon. [231]This pole, which settles toward the north (as appears from the preceding rules and demonstrations), is the southern, not the boreal; though all before us deemed it to be the boreal, on account of its turning to that point of the horizon. A wire or versorium touched on this pole of the stone turns to the south, and is made into a boreal pole, because it was touched by the southern terminal of the stone. So if the cusp of a versorium be excited in a similar manner, it will be directed toward the southern pole of the earth, and will adjust itself also to it; but the cross (the other end) will be southern, and will turn to the north of the earth (the earth itself being the cause of its motion); for so direction is produced from the disposition of the stone or of the excited iron, and from the verticity of the earth. But declination takes place when a magnetick is turned round toward the body of the earth, with its southern end toward the north, at some latitude away from the æquator. For this is certain and constant, that exactly under the coelestial æquator, or rather over the æquator of the terrestrial globe, there is no declination of a loadstone or of iron; but in whatever way the iron has been excited or rubbed, it settles in the declination instrument precisely along the plane of the horizon, if it were properly balanced before. Now this occurs thus because, when the magnetick body is at an equal distance from either pole, it dips toward neither by its own versatory nature, but remains evenly directed to the level of the horizon, as if it were resting on a pin or floating free and unhindered on water. But when the magnetick substance is at some latitude away from the æquator, or when either pole of the earth is raised (I do not say raised above the visible horizon, as the commonly imagined pole of the revolving universe in the sky, but above the horizon or its centre, or its proper diameter, æquidistant from the plane of the visible horizon, which is the true elevation of the terrestrial pole), {188} [Illustration] then declination is apparent, and the iron inclines toward the body of the earth in its own meridian. Let A B, for example, be the visible horizon of a place; C D the horizontal through the earth, dividing it into equal parts; E F the axis of the earth; G the position of the place. It is manifest that the boreal pole E is elevated above the point C by as much as G is distant from the æquator. Wherefore, since at E the magnetick needle stands perpendicularly in its proper turning (as we have often shown before), so now at G there is a certain tendency to turn in proportion to the latitude (the magnetick dipping below the plane of the horizon), and the magnetick body intersects the horizon at unequal angles, and exhibits a declination below the horizon. For the same reason, if the declinatory needle be placed at G, its southern end, the one namely which is directed toward the North, dips below the plane of the visible horizon A B. And so there is the greatest difference between a right sphere[232] and a polar or parallel sphere, in which the pole is at the very Zenith. For in a right sphere the needle is parallel to the plane of the horizon; but when the coelestial pole is vertically overhead, or when the pole of the earth is itself the place of the region, then the needle is perpendicular to the horizon. This is shown by a round stone. Let a small dipping-needle, of two digits length (rubbed with a magnet), be hung in the air like a balance, and let the stone be carefully placed under it; and first let the terrella be at right angles, as in a right sphere, and as in the first figure; for so the magnetick needle will remain in equilibrium. But in an oblique position of the terrella, as in an oblique sphere, and in the second figure, the needle dips obliquely at one end toward the near pole, but does not rest on the pole, nor is its dip ruled by the pole, but by the body and mass of the whole; for the {189} dip in higher latitudes passes beyond the pole. But in the third position of the terrella the needle is perpendicular; because the pole of the stone is placed at the top, and the needle tending straight toward the body reaches to the pole. The cross in the preceding figures always turns toward the boreal pole of the terrella, having been touched by the boreal pole of the terrella; the cusp of the needle, having been touched by the southern pole of the stone, turns to the south. Thus one may see on a terrella the level, oblique, and perpendicular positions of a magnetick needle. *
* * * * *
CHAP. II.
Diagram of declinations of the magnetick needle, when _excited, in the various portions of the sphere, and horizons_ of the earth, in which there is no variation _of the declination_.
{190} As æquator let A B be taken, C the north pole, D the south, E G dipping-needles in the northern, H F in the southern part of the earth or of a terrella. In the diagram before us all the cusps have been touched by the true Arctick pole of the terrella.
Here we have the level position of the magnetick needle on the æquator of the earth and the stone, at A and B, and its perpendicular position at C, D, the poles; whilst at the places midway between, at a distance of 45 degrees, the crosses of the needle dip toward the south, but the cusps just as much toward the north. Of which thing the reason will become clear from the demonstrations that follow.
_* Diagram of the rotation and declination of a terrella_ conforming to the globe of the earth, for a _latitude of 50 degrees north._
A is the boreal pole of the earth or of a rather large terrella, B the southern, C a smaller terrella, E the southern pole of the smaller terrella, dipping in the northern regions[233]. The centre C is placed on the surface of the larger terrella, because the smaller terrella shows some variation on account of the length of the axis; inappreciable, however, on the earth. Just as a magnetick needle dips in a regional latitude of 50 degrees, so also the axis of a stone (of a spherical stone, of course) is depressed below the horizon, and its natural austral pole falls, and its boreal pole is raised on the {191} south toward the Zenith. In the same way also a circular disc of iron behaves, which has been carefully touched at opposite parts on its circumference; but the magnetical experiments are less clear on account of the feebler forces in round pieces of iron.
_Variety in the declinations of iron spikes at various latitudes of a terrella._
The declination of a magnetick needle above a terrella is shown by means of several equal iron wires, of the length of a barleycorn, arranged along a meridian. The wires on the æquator are directed by the virtue of the stone toward the poles, and lie down upon its body along the plane of its horizon. The nearer they are brought to the poles, the more they are raised up by their versatory nature. At the poles themselves they point perpendicularly toward the very centre. But iron spikes, if they are of more than a due length, are not raised straight up except on a vigorous stone.
* * * * *
CHAP. III.
*
An indicatory instrument, showing by the virtue of a _stone the degrees of declination from the horizon_ of each several latitude.
{192} [Illustration] {193} _Description of the Instrument, and its use._
Take a terrella of the best strong loadstone, and homogeneous throughout, not weakened by decay or by a flaw in any parts; let it be of a fair size, so that its diameter is six or seven digits; and let it be made exactly spherical. Having found its poles according to the method already shown, mark them with an iron tool; then mark also the æquinoctial circle. Afterwards in a thick squared block of wood, one foot in size, make a hemispherical hollow, which shall hold half of the terrella, and such that exactly one half of the stone shall project above the face of the block. Divide the limb close to this cavity (a circle having been drawn round it for a meridian) into 4 quadrants, and each of these into 90 degrees. Let the terminus of the quadrants on the limb be near the centre of a quadrant described on the block, also divided into 90 degrees. At that centre let a short, slender versorium (its other end being rather sharp and elongated like a pointer) be placed in æquilibrio on a suitable pin. It is manifest that when the poles of the stone are at the starting points of the quadrants, then the versorium lies straight, as if in æquilibrio, over the terrella. But if you move the terrella, so that the pole on the left hand rises, then the versorium rises on the meridian in proportion to the latitude, and turns itself as a magnetick body; and on the quadrant described on the flat surface of the wood, the degree of its turning or of the declination is shown by the versorium. The rim of the cavity represents a meridional circle, to which corresponds some meridian circle of the terrella, since the poles on both sides are within the circumference of the rim itself. These things clearly always happen on the same plan on the earth itself when there is no variation; but when there is variation, either in the direction or in the declination (a disturbance, as it were, in the true turning, on account of causes to be explained later), then there is some difference. Let the quadrant be near the limb, or have its centre on the limb itself, and let the versorium be very short, so as not to touch the terrella, because with a versorium that is longer or more remote, there is some error; for it has a motion truly proportionate to the terrella only on the surface of the terrella. But if the quadrant, being far distant from the terrella, were moved within the orbe of virtue of the terrella toward the pole on some circle concentrick with the terrella, then the versorium would indicate the degrees of declination on the quadrant, in proportion to and symmetrically with that circle, not with the terrella.
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{194} CHAP. IIII.
Concerning the length of a versorium convenient _for declination on a terrella_.
Declination being investigated on the earth itself by means of a declination instrument, we may use either a short or a very long versorium, if only the magnetick virtue of the stone that touches it is able to permeate through the whole of its middle and through all its length. For the greatest length of a versorium has no moment or perceptible proportion to the earth's semi-diameter. On a terrella, however, or in a plane near a meridian of a terrella, a short versorium is desirable, of the length, say, of a barleycorn; for longer ones (because they reach further) dip and turn toward the body of the terrella suddenly and irregularly in the first degrees of declination. [Illustration] For example, as soon as the long versorium is moved forward from the aequator A to C, it catches on the stone with its cusp (as if with a long extended wing), when the cusp reaches to the parts about B, which produce a greater rotation than at C. And the extremities of longer wires also and rods turn irregularly, just as iron wires and balls of iron and other orbicular loadstones are likewise turned about irregularly by a long non-orbicular loadstone. Just so magneticks or iron bodies on the surface of a terrella ought not to have too long an axis, but a very short one; so that they may make a declination on the terrella truly and naturally proportionate to that on the earth. A long versorium also close to a terrella with difficulty stands steady in a horizontal direction on a right sphere, and, beginning to waver, it dips immediately to one side, especially the end that was touched, or (if both were touched) the one which felt the stone last.
* * * * *
{195} CHAP. V.
That declination does not arise from the attraction of the loadstone, but from a disposing and _rotating influence_.
In the universe of nature that marvellous provision of its Maker should be noticed, whereby the principal bodies are restrained within certain habitations and fenced in, as it were (nature controlling them). For this reason the stars, though they move and advance, are not thrown into confusion. Magnetical rotations also arise from a disposing influence, whether in greater and dominating quantity, or in a smaller, and compliant quantity, even though it be very small. For the work is not accomplished by attraction, but by an incitation of each substance, by a motion of agreement toward fixed bounds, beyond which no advance is made. For if the versorium dipped by reason of an attractive force, then a terrella made from a very strong magnetick stone would cause the versorium to turn toward itself more than one made out of an average stone, and a piece of iron touched with a vigorous loadstone would dip more. This, however, never happens. Moreover, an iron snout placed on a meridian in any latitude does not raise a spike more toward the perpendicular than the stone itself, alone and unarmed; although when thus equipped, it plucks up and raises many greater weights[234]. But if a loadstone be sharper toward one pole, toward the other blunter, the sharp end or pole allures a magnetick needle more strongly, the blunt, thick end makes it rotate more strongly; but an orbicular stone * makes it rotate strongly and truly, in accordance with magnetick rules and its globular form. A long stone, on the other hand, extended from pole to pole, moves a versorium toward it irregularly; for in this case the pole of the versorium always looks down on the pole itself. Similarly also, if the loadstone have been made in the shape of a circle, and its poles are on the circumference, whilst the body of it is plane, not globular, if the plane be brought near a versorium, the versorium does not move with the regular magnetick rotation, as on a terrella; but it turns looking always toward the pole of the loadstone, which has its seat on the circumference of the plane. Moreover, if the stone caused the versorium to rotate by attracting it, then in the first degrees of latitude, it would attract the end of a short versorium toward the body itself of the terrella; yet it does not so attract it that they are brought into contact and unite; but the versorium rotates just so far as nature demands, as is clear from this example. {196} [Illustration] * For the cusp of a versorium placed in a low latitude does not touch the stone or unite with it, but only inclines toward it. Moreover, when a magnetick body rotates in dipping, the pole of the versorium is not stayed or detained by the pole of the earth or terrella; but it rotates regularly, and does not stop at any point or bound, nor point straight to the pole toward which the centre of the versorium is advancing, unless on the pole itself, and once only between the pole and the æquator; but it dips as it advances, according as the change of position of its centre gives a reason for its inclination in accordance with rules magnetical. The declination of a magnetick needle in water also, as demonstrated in the following pages, is a fixed quantity[235]; the magnetick needle does not descend to the bottom of the vessel, but remains steady in the middle, rotated on its centre according to its due amount of declination. This would not happen, if the earth or its poles by their attraction drew down the end of the magnetick needle, so that it dipped in this way.
* * * * *
CHAP. VI.
On the proportion of declination to latitude[236], and _the cause of it_.
Concerning the making of an instrument for finding declination, the causes and manner of declination, and the different degrees of rotation in different places, the inclination of the stone, and concerning an instrument indicating by the influence of a stone the degree of declination from any horizon we have already spoken. Then we spoke about needles on the meridian of a stone, and their rotation shown for various latitudes by their rise toward the perpendicular. We must now, however, treat more fully of the causes of the degree of that inclination. Whilst a loadstone and a magnetick iron wire are moved along a meridian from the aequator toward the pole, they rotate toward a round loadstone, as also toward the earth with a circular movement. On a right horizon (just as also on the æquinoctial of {197} the stone) the axis of the iron, which is its centre line, is a line parallel to the axis of the earth. When that axis reaches the pole, which is the centre of the axis, it stands in the same straight line with the axis of the earth. The same end of the iron which at the æquator looks south turns to the north. For it is not a motion of centre to centre, but a natural turning of a magnetick body to a magnetick body, and of the axis of the body to the axis; it is not in consequence of the attraction of the pole itself that the iron points to the earth's polar point. Under the æquator the magnetick needle remains in æquilibrio horizontally; but toward the pole on either side, in every latitude from the beginning of the first degree right up to the ninetieth, it dips. The magnetick needle does not, however, in proportion to any number of degrees or any arc of latitude fall below the horizon just that number of degrees or a similar arc, but a very different one: because this motion is not really a motion of declination, but is in [Illustration] reality a motion of rotation, and it observes an arc of rotation according to the arc of latitude. Therefore a magnetick body A, while it is advancing over the earth itself, or a little earth or terrella, from the æquinoctial G toward the pole B, rotates on its own centre, and halfway on the progress of its centre[237] from the æquator to the pole B it is pointing toward the æquator at F, midway between the two poles. Much more quickly, therefore, must the versorium rotate than its centre advances, in order that by rotating it may face straight toward the point F. Wherefore the motion of this rotation is rapid in the first degrees from the æquator, namely, from A to L; but more tardy in the later degrees from L to B, when facing from the æquator at F to C. But if the declination were equal to the latitude (_i.e._, always just as many degrees from the horizon, as the centre of the versorium has receded from the æquator), then the magnetick needle would be following some potency and peculiar virtue of the centre, as if it {198} were a point operating by itself. But it pays regard to the whole, both its mass, and its outer limits; the forces of both uniting, as well of the magnetick versorium as of the earth. *
* * * * *
CHAP. VII.
Explanation of the diagram of the rotation of _a magnetick needle_.
Suppose A C D L to be the body of the earth or of a terrella, its centre M, Æquator A D, Axis C L, A B the Horizon, which changes according to the place. From the point F on a Horizon distant from the æquator A by the length of C M, the semi-diameter of the earth or terrella, an arc is described to H as the limit of the quadrants of declination; for {199} all the quadrants of declination serving the parts from A to C begin from that arc, and terminate at M, the centre of the earth. The semi-diameter of this arc is a chord drawn from the æquator A to the pole C; and a line produced along the horizon from A to B, equal to that chord, gives the beginning of the arc of the limits of arcs of rotation and revolution, which is continued as far as G. For just as a quadrant of a circle about the centre of the earth (whose beginning is on the horizon, at a distance from the æquator equal to the earth's semi-diameter) is the limit of all quadrants of declination drawn from each several horizon to the centre; so a circle about the centre from B, the beginning of the first arc of rotation, to G is the limit of the arcs of rotation. The arcs of rotation and revolution of the magnetick needle are intermediate between the arcs of rotation B L and G L. The centre of the arc is the region itself or place in which the observation is being made; the beginning of the arc is taken from the circle which is the limit of rotations, and it stops at the opposite pole; as, for example, from O to L, in a latitude of 45 degrees. Let any arc of rotation be divided into 90 equal parts from the limit of the arcs of rotation toward the pole; for whatever is the degree of latitude of the place, the part of the arc of rotation which the magnetick pole on or near the terrella or the earth faces in its rotation is to be numbered similarly to this. The straight lines in the following larger diagram show this. The magnetick rotation at the middle point in a latitude of 45 degrees is directed toward the æquator, in which case also that arc is a quadrant of a circle from the limit to the pole; but previous to this all the arcs of rotation are greater than a quadrant, whilst after it they are smaller; in the former the needle rotates more quickly, but in the succeeding positions gradually more slowly. For each several region there is a special arc of rotation, in which the limit to which the needle rotates is according to the number of degrees of latitude of the place in question; so that a straight line drawn from the place to the point on that arc marked with the number of degrees of latitude shows the magnetick direction, and indicates the degree of declination at the intersection of the quadrant of declination which serves the given place. Take away the arc of the quadrant of declination drawn from the centre to the line of direction; that which is left is the arc of declination below the horizon. As, for example, in the rotation of the versorium N, whose line respective proceeds to D, from the quadrant of declination, S M, take away its arc R M; that which is left is the arc of declination: how much, that is, the needle dips in the latitude of 45 degrees.
* * * * *
{200} CHAP. VIII.
Diagram of the rotation of a magnetick needle, _indicating magnetical declination in all latitudes, and_ from the rotation and declination, the _latitude itself_.
In the more elaborate diagram a circle of rotations and a circle of declinations are adjusted to the body of the earth or terrella, with a first, a last, and a middle arc of rotation and declination. Now from each fifth division of the arc which limits all the arcs of rotation (and which are understood[238] as divided into 90 equal parts) arcs are drawn to the pole, and from every fifth degree of the arc limiting the quadrants of declination, quadrants are drawn to the centre; and at the same time a spiral line is drawn, indicating (by the help of a movable quadrant) the declination in every latitude. Straight lines showing the direction of the needle are drawn from those degrees which are marked on the meridian of the earth or a terrella to their proper arcs and the corresponding points on those arcs.
To ascertain the elevation of the pole or the latitude of a place anywhere _in the world, by means of the following diagram, turned into a magnetick instrument, without the help of the coelestial bodies, sun, planets, or fixed stars, in fog and darkness_.
We may see how far from unproductive magnetick philosophy is, how agreeable, how helpful, how divine! Sailors when tossed about on the waves with continuous cloudy weather, and unable by means of the coelestial luminaries to learn anything about the place or the region in which they are, with a very slight effort and with a small instrument are comforted, and learn the latitude of the place. With a declination instrument the degree of declination of the magnetick needle below the horizon is observed; that degree is noted on the inner arc of the quadrant, and the quadrant is turned round about the centre of the instrument until that degree on the quadrant touches the spiral line; then in the open space B at the centre of the quadrant the latitude of the region on {201} the circumference of the globe is discerned by means of the fiducial line A B. Let the diagram be fixed on a suitable flat board, and let the centre of the corner A of the quadrant be fastened to the centre of it, so that the quadrant may rotate on that centre. But it must be understood that there is also in certain places a variation in the declination on account of causes already mentioned (though not a large one), which it will be an assistance also to allow for on a likely estimate; and it will be especially helpful to observe this variation in various places, as it seems to present greater difficulty than the variation in direction; but it is easily learnt with a declination instrument, when it dips more or less than the line in the diagram.
_To observe magnetick declination at sea_.
Set upon our variation instrument a declination instrument; a wooden disc being placed between the round movable {202} compass and the declination instrument: but first remove the versorium, lest the versorium should interfere with the dipping needle. In this way (though the sea be rough) the compass box will remain upright at the level of the horizon. The stand of the declination instrument must be directed by means of the small versorium at its base, which is set to the point respective of the variation, on the great circle of which (commonly called the magnetick meridian), the plane of the upright box is arranged; thus the declinatorium (by its versatory nature) indicates the degree of declination.
In a declination instrument the magnetick needle, which _in a meridional position dips, if turned along a parallel hangs perpendicularly._
In a proper position a magnetick needle, while by its rotatory nature conformed to the earth, dips to some certain degree below the horizon on an oblique sphere. But when the plane of the instrument is moved out of the plane of the meridian, the magnetick needle (which tends toward the pole) no longer remains at the degree of its own declination, but inclines more toward the centre; for the force of direction is stronger than that of declination, and all power of declination is taken away, if the plane of the instrument is on a parallel. For then the magnetick needle, because it cannot maintain its due position on account of the axis being placed transversely, faces down perpendicularly to the earth; and it remains only on its own meridian, or on that which is commonly called the magnetick meridian.
* * * * *
CHAP. IX.
Demonstration of direction, or of variation from the _true direction, at the same time with declination, by_ means of only a single motion in water, due _to the disposing and rotating virtue._
Fix a slender iron wire of three digits length through * a round cork, so that the cork may support the iron in water. Let this water be in a good-sized glass vase or bowl. Pare the round cork little by little with a very sharp knife (so that it may remain round), until it will stay motionless one or two digits below the face of the water; and let the wire be evenly balanced. {203} [239]Rub one end of the wire thus prepared on the boreal end of a loadstone and the other on the southern part of the stone (very skilfully, so that the cork may not be moved ever so little from its place) and again place it in the water; then the wire will dip with a circular motion on its own centre below the plane of the horizon, in proportion to the latitude of the region; and, even while dipping, will also show the point of variation (the true direction being perturbed). Let the loadstone (that with which the iron is rubbed) be a strong one, such as is needed in all experiments on magnetick declination. When the iron, thus put into the water and prepared by means of the loadstone, has settled in the dip, the lower end remains at the point of variation on the arc of a great circle or magnetick meridian passing through the Zenith or vertex, and the point of variation on the horizon, and the lowest point of the heavens, which they call the Nadir. This fact is shown by placing a rather long magnetick versorium on one side a little way from the vase. This is a demonstration of a more absolute conformity of a magnetick body with the earth's body as regards unity; in it is made {204} apparent, in a natural manner, the direction, with its variation, and the declination. But it must be understood that as it is a curious and difficult experiment, so it does not remain long in the middle of the water, but sinks at length to the bottom, when the cork has imbibed too much moisture.
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CHAP. X.
On the variation of the declination.
Direction has been spoken of previously, and also * variation, which is like a kind of dragging aside of the direction. Now in declination such irregular motion is also noticed, when the needle dips beyond the proper point or when sometimes it does not reach its mark. There is therefore a variation of declination, being the arc of a magnetick meridian between the true and apparent declination. For as, on account of terrestrial elevations, magnetick bodies are drawn away from the true meridian, so also the needle dips (its rotation being increased a little) beyond its genuine position. For as variation is a deviation of the direction, so also, owing to the same cause, there is some error of declination, though often very slight. Sometimes, also, when there is no variation of direction in the horizontal, there may nevertheless be variation of the declination; namely, either when more vigorous parts of the earth crop out exactly meridionally, _i.e._ under the very meridian; or when those parts are less powerful than nature in general requires; or when the virtue is too much intensified in one part, or weakened in another, just as one may observe in the vast ocean. And this discrepant nature and varying effect may be easily seen in certain parts of almost any round loadstone. Inæquality of power is recognized in any part of a terrella by trial of the demonstration in chap. 2 of this book. But the effect is clearly demonstrated by the instrument for showing declination in chap. 3 of this book.
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{205} CHAP. XI.
On the essential magnetick activity sphærically _effused._
Discourse hath often been held concerning the * poles of the earth and of the stone, and concerning the æquinoctial zone; whilst lately we have been speaking about the declining of magneticks toward the earth and toward the terrella, and the causes of it. But while by various and complicated devices we have laboured long and hard to arrive at the cause of this declination, we have by good fortune found out a new and admirable (beyond the marvels of all virtues magnetical) science of the orbes themselves. For such is the power of magnetick globes, that it is diffused and extended into orbes outside the body itself, the form being carried beyond the limits of the corporeal substance; and a mind diligently versed in this study of nature will find the definite causes of the motions and revolutions. The same powers of a terrella exist also within the whole orbe of its power; and these orbes at any distance from the body of the terrella have in themselves, in proportion to their diameter and the magnitude of their circumference, their own limits of influences, or points wherein magnetick bodies rotate; but they do not look toward the same part of the terrella or the same point at any distance from the same (unless they be on the axis of the orbes and of the terrella); but they always tend to those points of their own orbes, which are distant by similar arcs from the common axis of the orbes. As, for example, in the following diagram, we show the body of a terrella, with its poles and æquator; and also a versorium on three other concentrick orbes around the terrella at some distance from it. In these orbes (as in all those which we may imagine without end) the magnetick body or versorium conforms to its own orbe in which it is located, and to its diameter and poles and æquator, not to those of the terrella; and it is by them and according to the magnitude of their orbes that the magnetick body is governed, rotated, and directed, in any arc of that orbe, both while the centre of the magnetick body stands still, and also while it moves along. And yet we do not mean that the magnetick forms and orbes exist in air or water or in any medium that is not magnetical; as if the air or the water were susceptible of them, or were induced by them; for the forms are only effused and really subsist when magnetick substances are there; whence a magnetick body is laid hold of within the forces and limits of the orbes; and within the orbes magneticks {206} dispose magneticks and incite them, as if the orbes of virtue were solid and material loadstones. For the magnetick force does not pass through the whole medium or really exist as in a continuous body; so the orbes are magnetick, and yet not real orbes nor existent by themselves.
_Diagram of motions in magnetick orbes._
A B is the axis of the terrella and of the orbes, C D the æquator. On all the orbes, as on the terrella, at the equator the versorium arranges itself along the plane of the horizon; on the axis it everywhere looks perpendicularly toward the centre; in the intermediate spaces E looks toward D; and G looks toward H, not toward F, as the versorium L does on the surface of the terrella. But as is the relation of L to F on the surface of the terella, so is that of G to H on its orbe and of E to D on its orbe; also all the rotations on {207} the orbes toward the termini of the orbes are such as they are on the surface of the terrella, or toward the termini of its surface. But if in the more remote orbes this fails somewhat at times, it happens on account of the sluggishness of the stone, or on account of the feebler forces due to the too great distance of the orbes from the terrella.
_Demonstration._
Set upon the instrumental diagram described farther back [chap. 3] a plate or stiff circle of brass or tin, on which may be described the magnetick orbes, as in the diagram above; and in the middle let a hole be made according to the size of the terrella, so that the plate may lie evenly on the wood about the middle of the terrella on a meridional circle. Then let a small versorium of the length of a barley-corn be placed on any orbe; upon which, when it is moved to various positions on the same circle, it will always pay regard to the dimensions of that orbe, not to those of the stone; as is shown in the diagram of the effused magnetick forms.
While some assign occult and hidden virtues of substances, others a property of matter, as the causes of the wonderful magnetical effects; we have discovered the primary substantive form of globes, not from a conjectural shadow of the truth of reasons variously controverted; but we have laid hold of the true efficient cause, as from many other demonstrations, so also from this most certain diagram of magnetick forces effused by the form. Though this (the form) has not been brought under any of our senses, and on that account is the less perceived by the intellect, it now appears manifest and conspicuous even to the eyes through this essential activity which proceeds from it as light from a lamp. And here it must be noted that a magnetick needle, moved on the top of the earth or of a terrella or of the effused orbes, makes two complete rotations in one circuit of its centre, like some epicycle about its orbit.
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{208} CHAP. XII.
Magnetick force is animate, or imitates life; and in many things surpasses human life, while this is bound _up in the organick body_.
A loadstone is a wonderful thing in very many experiments, and like a living creature. And one of its remarkable virtues is that which the ancients considered to be a living soul in the sky, in the globes and in the stars, in the sun and in the moon. For they suspected that such various motions could not arise without a divine and animate nature, immense bodies turned about in fixed times, and wonderful powers infused into other bodies; whereby the whole universe flourishes in most beautiful variety, through this primary form of the globes themselves. The ancients, as Thales, Heraclitus, Anaxagoras, Archelaus, Pythagoras, Empedocles, Parmenides, Plato, and all the Platonists, and not only the older Greeks, but the Egyptians and Chaldæans, seek for some universal life in the universe, and affirm that the whole universe is endowed with life. Aristotle affirms that not the whole universe is animate, but only the sky; but he maintains that its elements are inanimate; whilst the stars themselves are animate. We, however, find this life in globes only and in their homogenic parts; and though it is not the same in all globes (for it is much more eminent in the sun and in certain stars than in others of less nobility) yet in very many the lives of the globes agree in their powers. For each several homogenic part draws to its own globe in a similar manner, and has an inclination to the common direction of the whole in the universe; and the effused forms extend outward in all, and are carried out into an orbe, and have bounds of their own; hence the order and regularity of the motions and rotations of all the planets, and their courses, not wandering away, but fixed and determined. Wherefore Aristotle concedes life to the sphæres themselves and to the orbes of the heavens (which he feigns), because they are suitable and fitted for a circular motion and actions, and are carried along in fixed and definite courses. It is surely wonderful, why the globe of the earth alone with its emanations is condemned by him and his followers and cast into exile (as senseless and lifeless), and driven out of all the perfection of the excellent universe. It is treated as a small corpuscle in comparison with the whole, and in the numerous concourse of many thousands it is obscure, disregarded, and unhonoured. {209} With it also they connect the kindred elements, in a like unhappiness, wretched and neglected. Let this therefore be looked upon as a monstrosity in the Aristotelian universe, in which everything is perfect, vigorous, animated; whilst the earth alone, an unhappy portion, is paltry, imperfect, dead, inanimate, and decadent. But on the other hand Hermes, Zoroaster, Orpheus, recognize a universal life. We, however, consider that the whole universe is animated, and that all the globes, all the stars, and also the noble earth have been governed since the beginning by their own appointed souls and have the motives of self-conservation. Nor are there wanting, either implanted in their homogenic nature or scattered through their homogenic substance, organs suitable for organic activity, although these are not fashioned of flesh and blood as animals, or composed of regular limbs, which are also hardly perceptible in certain plants and vegetables; since regular limbs are not necessary for all life. Nor can any organs be discerned or imagined by us in any of the stars, the sun, or the planets, which are specially operative in the universe; yet they live and imbue with life the small particles in the prominences on the earth. If there be anything of which men can boast, it is in fact life, intelligence; for the other animals are ennobled by life; God also (by whose nod all things are ruled) is a living soul. Who therefore will demand organs for the divine intelligences, which rise superior to every combination of organs and are not restrained by materialized organs? But in the several bodies of the stars the implanted force acts otherwise than in those divine existences which are supernaturally ordained; and in the stars, the sources of things, otherwise than in animals; in animals again otherwise than in plants. Miserable were the condition of the stars, abject the lot of the earth, if that wonderful dignity of life be denied to them, which is conceded to worms, ants, moths, plants, and toadstools; for thus worms, moths, grubs would be bodies more honoured and perfect in nature; for without life no body is excellent, valuable, or distinguished. But since living bodies arise and receive life from the earth and the sun, and grass grows on the earth apart from any seeds thrown down (as when soil is dug up from deep down in the earth, and put on some very high place or on a very high tower, in a sunny spot, not so long after various grasses spring up unbidden) it is not likely that they can produce what is not in them; but they awaken life, and therefore they are living. Therefore the bodies of the globes, as important parts of the universe, in order that they might be independent and that they might continue in that condition, had a need for souls to be united with them, without which there can be neither life, nor primary activity, nor motion, nor coalition, nor controlling power, nor harmony, nor endeavour, nor sympathy; and without which there would be no generation {210} of anything, no alternations of the seasons, no propagation; but all things would be carried this way and that, and the whole universe would fall into wretchedest Chaos, the earth in short would be vacant, dead, and useless. But it is only on the superficies of the globes that the concourse of living and animated beings is clearly perceived, in the great and pleasing variety of which the great master-workman is well pleased. But those souls which are restrained within a kind of barrier and in prison cells, as it were, do not emit immaterial effused forms outside the limits of their bodies; and bodies are not moved by them without labour and waste. They are brought and carried away by a breath; and when this has calmed down or been suppressed by some untoward influence, their bodies lie like the dregs of the universe and as the refuse of the globes. But the globes themselves remain and continue from year to year, move, and advance, and complete their courses, without waste or weariness. The human soul uses reason, sees many things, inquires about many more; but even the best instructed receives by his external senses (as through a lattice) light and the beginnings of knowledge. Hence come so many errors and follies, by which our judgments and the actions of our lives are perverted; so that few or none order their actions rightly and justly. But the magnetick force of the earth and the formate life or living form of the globes, without perception, without error, without injury from ills and diseases, so present with us, has an implanted activity, vigorous through the whole material mass, fixed, constant, directive, executive, governing, consentient; by which the generation and death of all things are carried on upon the surface. For, without that motion, by which the daily revolution is performed, all earthly things around us would ever remain savage and neglected, and more than deserted and absolutely idle. But those motions in the sources of nature are not caused by thinking, by petty syllogisms, and theories, as human actions, which are wavering, imperfect, and undecided; but along with them reason, instruction, knowledge, discrimination have their origin, from which definite and determined actions arise, from the very foundations that have been laid and the very beginnings of the universe; which we, on account of the infirmity of our minds, cannot comprehend. Wherefore Thales, not without cause (as Aristotle relates in his book _De Anima_), held that the loadstone was animate, being a part and a choice offspring of its animate mother the earth.
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{211} [Illustration]
BOOK SIXTH.
_CHAP. I._
ON THE GLOBE OF THE EARTH, THE _great magnet_.
Hitherto our subject hath been the loadstone and things magnetical: how they conspire together, and are acted upon, how they conform themselves to the terrella and to the earth. Now must we consider separately the globe itself of the earth. Those experiments which have been proved by means of the terrella, how magnetick things conform themselves to the terrella, are all or at least the principal and most important of them, displayed by means of the earth's Body: And to the earth things magnetical are in all respects associate. First, as in the terrella the æquator, meridians, parallels, axis, poles are natural boundaries, as numerous experiments make plain: So also in the earth these boundaries are natural, not mathematical only (as all before us used to suppose). These boundaries the same experiments display and establish in both cases alike, in the earth no less than in the terrella. Just as on the periphery of a terrella a loadstone or a magnetick piece of iron is directed to its proper pole: so on the earth's surface are there turnings-about, peculiar, manifest, and constant on either side of the æquator. Iron is indued with verticity by being extended toward a pole of the earth, just as toward a pole of the terrella: By its being placed down also, and cooling toward the earth's pole after the pristine verticity has {212} been annulled by fire, it acquires new verticity, conformable to its position earthward. Iron rods also, when placed some considerable time toward the poles, acquire verticity merely by regarding the earth; just as the same rods, if placed toward the pole of a loadstone, even without touching it, receive polar virtue. There is no magnetick body that in any way runs to the terrella which does not also wait upon the earth. As a loadstone is stronger at one end on one side or other[240] of its æquator: so is the same property displayed by a small terrella upon the surface of a larger terrella. According to the variety and artistick skill in the rubbing of the magnetick iron upon the terrella, so do the magnetick things perform their function more efficiently or more feebly. In motions toward the earth's body, as toward the terrella a variation is displayed due to the unlikeness, inequality, and imperfection of its eminences: So every variation of the versorium or mariners' compass, everywhere by land or by sea, which thing has so sorely disturbed men's minds, is discerned and recognized as due to the same causes. The magnetick dip (which is the wonderful turning of magnetick things to the body of the terrella) in systematick course, is seen in clearer light to be the same thing upon the earth. And that single experiment, by a wonderful indication, as with a finger, proclaims the grand magnetick nature of the earth to be innate and diffused through all her inward parts. A magnetick vigour exists then in the earth just as in the terrella, which is a part of the earth, homogenic in nature with it, but rounded by Art, so as to correspond with the earth's globous shape and in order that in the chief experiments it might accord with the globe of the earth.
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CHAP. II.
The Magnetick axis of the Earth _persists invariable_.
As in the very first beginnings of the moving world, the earth's magnetick axis passed through the midst of the earth: so now it tends through the centre to the same points of the superficies; the circle and plane of the æquinoctial line also persisting. For not without the vastest overthrow of the terrene mass can these natural boundaries be changed, as it is easy to gather from magnetick demonstrations. Wherfore the opinion of Dominicus Maria of Ferrara, a most talented man, who was the teacher of Nicolas Copernicus, must be cancelled; a view {213} which, according to certain observations of his own, is as follows.[241] "I," he says, "in former years while studying Ptolemy's _Geographia_ discovered that the elevations of the North pole placed by him in the several regions, fall short of what they are in our time by one degree and ten minutes: which divergence can by no means be ascribed to an error of the tables: For it is not credible that the whole series in the book is equally wrong in the figures of the tables: Hence it is necessary to allow that the North pole has been tilted toward the vertical point. Accordingly a lengthy observation has already begun to disclose to us things hidden from our forefathers; not indeed through any sloth of theirs, but because they lacked the prolonged observation of their predecessors: For before Ptolemy very few places were observed with regard to the elevations of the pole, as he himself also bears witness at the beginning of his _Cosmographia_: (For, says he) Hipparchus alone hath handed down to us the latitudes of a few places, but a good many have noted those of distances; especially those which lie toward sunrise or sunset were received by some general tradition, not owing to any sloth on the part of authors themselves, but to the fact that there was as yet no practice of more exact mathematicks. 'Tis accordingly no wonder, if our predecessors did not mark this very slow motion: For in one thousand and seventy years it shows itself to be displaced scarce one degree toward the apex of dwellers upon the earth. The strait of Gibraltar shows this, where in Ptolemy's time the North pole appears elevated 36 degrees and a quarter from the Horizon: whereas now it is 37 and two-fifths. The like divergence is also shown at Leucopetra in Calabria, and at particular spots in Italy, namely those which have not changed from Ptolemy's time to our own. And so by reason of this movement, places now inhabited will some day become deserted, while those regions which are now parched at the torrid zone will, though long hence, be reduced to our temper of climate. Thus, as in a course of three hundred and ninety five thousands of years, is that very slow movement completed." Thus, according to these observations of Dominicus Maria, the North pole is at a higher elevation, and the latitudes of places are greater than formerly; whence he argues a change of latitudes. Now, however, Stadius, taking just the contrary view, proves by observations that the latitudes have decreased. For he says: "The latitude of Rome in Ptolemy's _Geographia_ is 41 degrees 2/3: and that you may not suppose any error of reckoning to have crept in on the part of Ptolemy, on the day of the Æquinox in the city of Rome, the ninth part of the gnomon of the sun-dial is lacking in shadow, as Pliny relates and Vitruvius witnesseth in his ninth book." But the observation of moderns (according to Erasmus Rheinholdus) gives the same in our time as 41 degrees with a sixth: so that you are in doubt as to half of one degree in {214} the centre of the world, whether you show it to have decreased by the earth's obliquity of motion. One may see then how from inexact observations men rashly conceive new and contradictory opinions and imagine absurd motions of the mechanism of the earth. For since Ptolemy only received certain latitudes from Hipparchus, and did not in very many places make the observations himself; it is likely that he himself, knowing the position of the places, formed his estimate of the latitude of cities from probable conjecture only, and then placed it in the maps. Thus one may see, in the case of our own Britain, that the latitudes of cities are wrong by two or three degrees, as experience teaches. Wherefore all the less should we from those mistakes infer a new motion, or let the noble magnetick nature of the earth be debased for an opinion so lightly conceived. Moreover, those mistakes crept the more readily into geography, from the fact that the magnetick virtue was utterly unknown to those geographers. Besides, observations of latitudes cannot be made sufficiently exactly, except by experts, using also finer instruments, and taking into account the refraction of the lights.
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CHAP. III.
On the magnetick diurnal revolution of the Earth's globe, as a probable assertion against the time-honoured _opinion of a Primum Mobile_.
Among the ancients Heraclides of Pontus and Ecphantus, afterwards the Pythagoreans, as Nicetas of Syracuse and Aristarchus of Samos, and some others (as it seems), used to think that the earth moves, and that the stars set by the interposition of the earth and rose by her retirement. In fact they set the earth moving and make her revolve around her axis from west to east, like a wheel turning on its axle. Philolaus the Pythagorean[242] would have the earth to be one of the stars, and believed that it turned in an oblique circle around fire, just as the sun and moon have their own courses. He was a distinguished mathematician, and a most able investigator of nature. But after Philosophy became a subject treated of by very many and was popularized, theories adapted to the vulgar intelligence or based on sophistical subtility occupied the minds of most men, and prevailed like a torrent, the multitude consenting. Thereupon many valuable discoveries of the ancients were rejected, and were dismissed to perish in banishment; or at least by not being further cultivated and developed became obsolete. So that Copernicus[243] (among later discoverers, a man most deserving of literary honour) is the first who attempted to illustrate the [Greek: phainomena] of {215} moving bodies by new hypotheses: and these demonstrations of reasons others either follow or observe in order that they may more surely discover the phænomenal harmony of the movements; being men of the highest attainments in every kind of learning. Thus supposed and imaginary orbs of Ptolemy and others for finding the times and periods of the motions are not necessarily to be admitted to the physical inquiries of philosophers. It is then an ancient opinion and one that has come down from old times, but is now augmented by important considerations that the whole earth rotates with a daily revolution in the space of 24 hours. Well then, since we see the Sun and Moon and other planets and the glory of all the stars approach and retire within the space of one natural day, either the Earth herself must needs be set in motion with a diurnal movement from West to East, or the whole heaven and the rest of nature from East to West. But, in the first place, it is not likely that the highest heaven and all those visible splendours of the fixed stars are impelled along that most rapid and useless course. Besides, who is the Master who has ever made out that the stars which we call fixed are in one and the same sphere, or has established by reasoning that there are any real and, as it were, adamantine sphæres? No one has ever proved this as a fact; nor is there a doubt but that just as the planets are at unequal distances from the earth, [244]so are those vast and multitudinous lights separated from the Earth by varying and very remote altitudes; they are not set in any sphærick frame or firmament (as is feigned), nor in any vaulted body: accordingly the intervals of some are from their unfathomable distance matter of opinion rather than of verification; others do much exceed them and are very far remote, and these being located in the heaven at varying distances, either in the thinnest æther or in that most subtile quintessence, or in the void: how are they to remain in their position during such a mighty swirl of the vast orbe of such uncertain substance. There have been observed by astronomers 1022 stars; besides these, numberless others are visible, some indeed faint to our senses, in the case of others our sense is dim and they are hardly perceived and only by exceptionally keen eyes, and there is no one gifted with excellent sight who does not when the Moon is dark and the air at its rarest, discern numbers and numbers dim and wavering with minute lights on account of the great distance: hence it is credible both that these are many and that they are never all included in any range of vision. How immeasurable then must be the space which stretches to those remotest of fixed stars! How vast and immense the depth of that imaginary sphere! How far removed from the Earth must the most widely separated stars be and at a distance transcending all sight, all skill and thought! How monstrous then such a motion {216} would be! It is evident then that all the heavenly bodies set as if in destined places are there formed into sphæres, that they tend to their own centres, and that round them there is a confluence of all their parts. And if they have motion, that motion will rather be that of each round its own centre, as that of the Earth is; or a forward movement of the centre in an orbit, as that of the Moon: there would not be circular motion in the case of a too numerous and scattered flock. Of these stars some situate near the Æquator would seem to be borne around at a very rapid rate, others nearer the pole to have a somewhat gentler motion, others, apparently motionless, to have a slight rotation. Yet no differences in point of light, mass or colours are apparent to us: for they are as brilliant, clear, glittering and duskish toward the poles, as they are near the Æquator and the Zodiack: those which remain set in those positions do not hang, and are neither fixed, nor bound to anything of the nature of a vault. All the more insane were the circumvolution of that fictitious _Primum Mobile_, which is higher, deeper, and still more immeasurable. Moreover, this inconceivable _Primum Mobile_ ought to be material and of enormous depth, far surpassing all inferior nature in size: for nohow else could it conduct from East to West so many and such vast bodies of stars, and the universe even down to the Earth: and it requires us to accept in the government of the stars a universal power and a despotism perpetual and intensely irksome. That _Primum Mobile_ bears no visible body, is nohow recognizable, is a fiction believed in by those people, accepted by the weak-minded folk, who wonder more at our terrestrial mass than at bodies so vast, so inconceivable, and so far separated from us. But there can be no movement of infinity and of an infinite body, and therefore no diurnal revolution of that vastest _Primum Mobile_. The Moon being neighbour to the Earth revolves in 27 days; Mercury and Venus have their own moderately slow motions; Mars finishes a period in two years, Jupiter in twelve years, Saturn in thirty. And those also who ascribe a motion to the fixed stars make out that it is completed in 36,000 years, according to Ptolemy, in 25,816 years, according to Copernicus' observations; so that the motion and the completion of the journey always become slower in the case of the greater circles. And would there then be a diurnal motion of that _Primum Mobile_ which is so great and beyond them all immense and profound? 'Tis indeed a superstition and in the view of philosophy a fable now only to be believed by idiots, deserving more than ridicule from the learned: and yet in former ages, that motion, under the pressure of an importunate mob of philosophizers, was actually accepted as a basis of computations and of motions, by mathematicians. The motions of the bodies (namely planets) seem to take place eastward and following the order of the signs. {217} The common run of mathematicians and philosophers also suppose that the fixed stars in the same manner advance with a very slow motion: and from ignorance of the truth they are forced to join to them a ninth sphære. Whereas now this first and unthinkable _Primum Mobile_, a fiction not comprehended by any judgment, not evidenced by any visible constellation, but devised of imagination only and mathematical hypothesis, unfortunately accepted and believed by philosophers, extended into the heaven and beyond all the stars, must needs with a contrary impulse turn about from East to West, in opposition to the inclination of all the rest of the Universe. Whatsoever in nature is moved naturally, the same is set in motion both by its own forces and by the consentient compact of other bodies. Such is the motion of parts to their whole, of all interdependent sphæres and stars in the universe: such is the circular impulse in the bodies of the planets, when they affect and incite one another's courses. But with regard to the _Primum Mobile_ and its contrary and exceeding rapid movement, what are the bodies which incite it or propel it? What is the nature that conspires with it? Or what is that mad force beyond the _Primum Mobile_? Since it is in bodies themselves that acting force resides, not in spaces or intervals. But he who thinks that those bodies are at leisure and keeping holiday, while all the virtue of the universe appertains to the very orbits and sphæres, is on this point not less mad than he who, in some one else's house, thinks that the walls and floors and roof rule the family rather than the wife and thoughtful paterfamilias. Therefore not by the firmament are they borne along, or are moved, or have their position; much less are those confused crowds of stars whirled around by the _Primum Mobile_, nor are they torn away and huddled along by a contrary and extremely rapid movement. Ptolemy of Alexandria seems to be too timid and weak-minded in dreading the dissolution of this nether world, were the Earth to be moved round in a circle. Why does he not fear the ruin of the Universe, dissolution, confusion, conflagration, and infinite disasters celestial and super-celestial, from a motion transcending all thoughts, dreams, fables, and poetic licences, insurmountable, ineffable, and inconceivable? Wherefore we are carried along by a diurnal rotation of the earth (a motion for sure more congruous), and as a boat moves above the waters, so do we turn about with the earth, and yet seem to ourselves to be stationary, and at rest. Great and incredible it seems to some philosophers, by reason of inveterate prejudice, that the Earth's vast body should be swirled wholly round in the space of 24 hours. But it would be more incredible that the Moon should travel through her orbit, or complete an entire course in a space of 24 hours; more so the Sun or Mars; still more Jupiter and Saturn; more than marvellous would be the velocity in the case of the {218} fixed stars and the firmament; what in the world they would have to wonder at in the case of their ninth sphere, let them imagine as they like. But to feign a _Primum Mobile_ and to attribute to the thing thus feigned a motion to be completed in the space of 24 hours, and not to allow this motion to the Earth in the same interval of time, is absurd. For a great circle of the Earth is to the ambit of the _Primum Mobile_ less than a furlong to the whole Earth. If the diurnal rotation of the Earth seem headlong, and not admissible in nature by reason of its rapidity, worse than insane will be the movement of the _Primum Mobile_ both for itself and the whole universe, agreeing as it does with no other motion in any proportion or likeness. It seems to Ptolemy and the Peripateticks that nature must be disordered, and the framework and structure of this globe of ours be dissolved, by reason of so swift a terrestrial revolution. The Earth's diameter is 1718 German miles; the greatest elongation of the new Moon is 65, the least is 55 semi-diameters of the Earth: the greatest altitude of the half moon is 68, the least 52: yet it is probable that its sphære is still larger and deeper. The sun in its greatest eccentricity has a distance of 1142 semi-diameters of the Earth; Mars, Jupiter, Saturn, being slower in motion, are so proportionately further remote from the Earth. The distances of the firmament and of the fixed stars seem to the best mathematicians inconceivable. Leaving out the ninth sphære, if the convexity of the _Primum Mobile_ be duly estimated in proportion to the rest of the sphæres, the vault of the _Primum Mobile_ must in one hour run through as much space as is comprised in 3000 great circles of the Earth, for in the vault of the firmament it would complete more than 1800; but what iron solidity can be imagined so firm and tough as not to be disrupted and shattered to fragments by a fury so great and a velocity so ineffable. The Chaldæans indeed would have it that the heaven consists of light. In light, however, there is no so-great firmness, neither is there in Plotinus' fiery firmament, nor in the fluid or aqueous or supremely rare and transparent heaven of the divine Moses, which does not cut off from our sight the lights of the stars. We must accordingly reject the so deep-set error about this so mad and furious a celestial velocity, and the forced retardation of the rest of the heavens. Let theologians discard and wipe out with sponges those old women's tales of so rapid a spinning round of the heavens borrowed from certain inconsiderate philosophers. The sun is not propelled by the sphære of Mars (if a sphære there be) and by his motion, nor Mars by Jupiter, nor Jupiter by Saturn. The sphære, too, of the fixed stars, seems well enough regulated except so far as motions which are in the Earth are ascribed to the heavens, and bring about a certain change of phænomena. The superiors do not exercise a despotism over the inferiors; for the heaven of {219} philosophers, as of theologians, must be gentle, happy, and tranquil, and not at all subject to changes: nor shall the force, fury, swiftness, and hurry of a _Primum Mobile_ have dominion over it. That fury descends through all the celestial sphæres, and celestial bodies, invades the elements of our philosophers, sweeps fire along, rolls along the air, or at least draws the chief part of it, conducts the universal æther, and turns about fiery impressions (as if it were a solid and firm body, when in fact it is a most refined essence, neither resisting nor drawing), leads captive the superior. O marvellous constancy of the terrestrial globe, the only one unconquered; and yet one that is holden fast, or stationary, in its place by no bonds, no heaviness, by no contiguity with a grosser or firmer body, by no weights. The substance of the terrestrial globe withstands and sets itself against universal nature. Aristotle feigns for himself a system of philosophy founded on motions simple and compound, that the heavens revolve in a simple circle, its elements moving with a right motion, the parts of the earth seeking the earth in straight lines, falling on its surface at right angles, and tending together toward its centre, always, however, at rest therein; accordingly also the whole Earth remains immovable in its place, united and compacted together by its own weight. That cohæsion of parts and aggregation of matter exist in the Sun, in the Moon, in the planets, in the fixed stars, in fine in all those round bodies whose parts cohære together and tend each to their own centres; otherwise the heaven would fall, and that sublime ordering would be lost: yet these coelestial bodies have a circular motion. Whence the Earth too may equally have her own motion: and this motion is not (as some deem it) unsuitable for the assembling or adverse to the generation of things. For since it is innate in the terrestrial globe, and natural to it; and since there is nothing external that can shock it, or hinder it by adverse motions, it goes round without any ill or danger, it advances without being forced, there is nothing that resists, nothing that by retiring gives way, but all is open. For while it revolves in a space void of bodies, or in the incorporeal æther, all the air, the exhalations of land and water, the clouds and pendent meteors, are impelled along with the globe circularly: that which is above the exhalations is void of bodies: the finest bodies and those which are least cohærent almost void are not impeded, are not dissolved, while passing through it. Wherefore also the whole terrestrial globe, with all its adjuncts, moves bodily along, calmly, meeting no resistance. Wherefore empty and superstitious is the fear that some weak minds have of a shock of bodies (like Lucius Lactantius, who, in the fashion of the unlettered rabble and of the most unreasonable men scoffs at an Antipodes and at the sphærick ordering of the Earth all round). So for these reasons, not only probable but manifest, does the diurnal rotation of the earth seem, {220} since nature always acts through a few rather than through many; and it is more agreeable to reason that the Earth's one small body should make a diurnal rotation, than that the whole universe should be whirled around. I pass over the reasons of the Earth's remaining motions, for at present the only question is concerning its diurnal movement, according to which it moves round with respect to the Sun, and creates a natural day (which we call a nycthemeron[245]). And indeed Nature may be thought to have granted a motion very suitable to the Earth's shape, which (being sphærical) is revolved about the poles assigned it by Nature much more easily and fittingly than that the whole universe, whose limit is unknown and unknowable, should be whirled round; and than there could be imagined an orbit of the _Primum Mobile_, a thing not accepted by the ancients, which Aristotle even did not devise or accept as in any shape or form existing beyond the sphære of the fixed stars; which finally the sacred scriptures do not recognize any more than they do the revolution of the firmament.
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CHAP. IIII.
That the Earth moves circularly.
If then the philosophers of the common sort, with an unspeakable absurdity, imagine the whole heaven and the vast extent of the universe to rotate in a whirl, it yet remains that the earth performs a diurnal change. For in no third way can the apparent revolutions be explained. This day, then, which is called natural, is a revolution of some meridian of the Earth from Sun to Sun. It revolves indeed in an entire course, from a fixed star round to that star again. Those bodies which in nature are moved with a circular, æquable and constant motion, are furnished, in their parts, with various boundaries. But the Earth is not a Chaos nor disordered mass; but by reason of its astral virtue, it has boundaries which subserve the circular motion, poles not mathematical, an æquator not devised by imagination, meridians also and parallels; all of which we find permanent, certain and natural in the Earth: which by numerous experiments the whole magnetick philosophy sets forth. For in the earth there are poles set in fixed bounds, and at them the verticity mounts up on either side from the plane of the Earth's æquator, with forces which are mightier and præpotent from the common action of the whole; and with these poles the diurnal revolution is in agreement. But in no turnings-about of bodies, in none of the motions of the planets are there to be recognized, beheld, or assured to us by any reasoning any sensible or natural poles in the firmament, or in any _Primum_ {221} _Mobile_; but those are the conception of an unsettled imagination. Wherefore we, following an evident, sensible and tested cause, do know that the earth moves on its own poles, which are apparent to us by many magnetick demonstrations. For not only on the ground of its constancy, and its sure and permanent position, is the Earth endowed with poles and verticity: for it might be directed toward other parts of the universe, toward East or West or some other region. By the wondrous wisdom then of the Builder forces, primarily animate, have been implanted in the Earth, that with determinate constancy the Earth may take its direction, and the poles have been placed truly opposite[246], that about them as the termini, as it were, of some axis, the motion of diurnal turning might be performed. But the constancy of the poles is regulated by the primary soul. Wherefore, for the Earth's good, the collimations of her verticities do not continually regard a definite point of the firmament and of the visible heaven. For changes of the æquinoxes take place from a certain deflection of the Earth's axis; yet in regard to that deflection, the Earth has a constancy of motion [Illustration] derived from her own forces. The Earth, that she may turn herself about in a diurnal revolution, leans on her poles. For since at A and B there is constant verticity, and the axis is straight; at C and D (the æquinoctial line) the parts are free, the whole forces on either side being spread out from the plane of the æquator toward the poles, in æther which is free from renitency, or else in a void; and A and B remaining constant, C revolves toward D both from innate conformity and aptitude, and for necessary good, and the avoidance of evil; but being chiefly moved forward by the diffusion of the solar orbes of virtues, and by their lights. And 'tis borne around, not upon a new and strange course, but (with the {222} tendency common to the rest of the planets) it tends from West to East. For all planets have a like motion Eastward according to the succession of the signs, whether Mercury and Venus revolve beneath the Sun, or around the Sun. That the Earth is capable of and fitted for moving circularly its parts show, which when separated from the whole are not only borne along with the [Illustration] straight movement taught by the Peripateticks, but rotate also. A loadstone fixed in a wooden vessel is placed on water so as to swim freely, turn itself, and float about. If the pole B of the loadstone be set contrary to nature toward the South, F, the Terrella is turned about its own centre with a circular motion in the plane of the Horizon, toward the North, E, where it rests, not at C or D. So does a small stone if only of four ounces; it has the same motion also and just as quick, if it were a strong magnet of one hundred pounds. The largest magnetical mountain will possess the same turning-power also, if launched in a wide river or deep sea: and yet a magnetick body is much more hindered by water than the whole Earth is by the æther. The whole Earth would do the same, if the Boreal pole were to be diverted from its true direction; for the Boreal pole would run back with the circular motion of the whole around the centre toward the Cynosure. But this motion by which the parts naturally settle themselves in their own {223} resting-places is no other than circular. The whole Earth regards the Cynosure with her pole according to a steadfast law of her nature: and thus each true part of it seeks a like resting-place in the world, and is moved circularly toward that position. The natural movements of the whole and of the parts are alike: wherefore when the parts are moved in a circle, the whole also has the potency of [Illustration] moving circularly. A sphærical loadstone placed in a vessel on water moves circularly around its centre (as is manifest) in the plane of the Horizon, into conformity[247] with the earth.
So also it would move in any other great circle if it could be free; as in the declination instrument, a circular motion takes place in the meridian (if there were no variation), or, if there should be some variation, in a great circle drawn from the Zenith through the point of variation on the horizon. And that circular motion of the magnet to its own just and natural position shows that the whole Earth is fitted and adapted, and is sufficiently furnished with peculiar forces for diurnal circular motion. I omit what Peter Peregrinus[248] constantly affirms, that a terrella suspended above its poles on a meridian moves circularly, making an entire revolution in 24 hours: which, however, it has not happened to ourselves as yet to see; and we even doubt this motion on account of the weight of the stone itself, as well as because the whole Earth, as she is moved of herself, so also is she propelled by other stars: and this does not happen in proportion (as it does in the terrella) {224} in every part. The Earth is moved by her own primary form and natural desire, for the conservation, perfection, and ordering of its parts, toward things more excellent: and this is more likely than that the fixed stars, those luminous globes, as well as the Wanderers, and the most glorious and divine Sun, which are in no way aided by the Earth, or renewed, or urged by any virtue therein, should circulate aimlessly around the Earth, and that the whole heavenly host should repeat around the Earth courses never ending and of no profit whatever to the stars. The Earth, then, which by some great necessity, even by a virtue innate, evident, and conspicuous, is turned circularly about the Sun, revolves; and by this motion it rejoices in the solar virtues and influences, and is strengthened by its own sure verticity, that it should not rovingly revolve over every region of the heavens. The Sun (the chief agent in nature) as he forwards the courses of the Wanderers, so does he prompt this turning about of the Earth by the diffusion of the virtues of his orbes, and of light. And if the Earth were not made to spin with a diurnal revolution, the Sun would ever hang over some determinate part with constant beams, and by long tarriance would scorch it, and pulverize it, and dissipate it, and the Earth would sustain the deepest wounds; and nothing good would issue forth; it would not vegetate, it would not allow life to animals, and mankind would perish. In other parts, all things would verily be frightful and stark with extreme cold; whence all high places would be very rough, unfruitful, inaccessible, covered with a pall of perpetual shades and eternal night. Since the Earth herself would not choose to endure this so miserable and horrid appearance on both her faces, she, by her magnetick astral genius, revolves in an orbit, that by a perpetual change of light there may be a perpetual alternation of things, heat and cold, risings and settings, day and night, morn and eve, noon and midnight. Thus the Earth seeks and re-seeks the Sun, turns away from him and pursues him, by her own wondrous magnetick virtue. Besides, it is not only from the Sun that evil would impend, if the Earth were to stay still and be deprived of solar benefit; but from the Moon also serious dangers would threaten. For we see how the ocean rises and swells beneath certain known positions of the Moon: And if there were not through the daily rotation of Earth a speedy transit of the Moon, the flowing sea would be driven above its level into certain regions, and many shores would be overwhelmed with huge waves. In order then that Earth may not perish in various ways, and be brought to confusion, she turns herself about by magnetick and primary virtue: and the like motions exist also in the rest of the Wanderers, urged specially by the movement and light of other bodies. For the Moon also turns herself about in a monthly course, to receive in succession the Sun's beams in which she, like the Earth, {225} rejoices, and is refreshed: nor could she endure them for ever on one particular side without great harm and sure destruction. Thus each one of the moving globes is for its own safety borne in an orbit either in some wider circle, or only by a rotation of its body, or by both together. But it is ridiculous for a man a philosopher to suppose that all the fixed stars and the planets and the still higher heavens revolve to no other purpose, save the advantage of the Earth. It is the Earth, then, that revolves, not the whole heaven, and this motion gives opportunity for the growth and decrease of things, and for the generating of things animate, and awakens internal heat for the bringing of them to birth. Whence matter is quickened for receiving forms; and from the primary rotation of the Earth natural bodies have their primary impetus and original activity. The motion then of the whole Earth is primary, astral, circular, around its own poles, whose verticity arises on both sides from the plane of the æquator, and whose vigour is infused into opposite termini, in order that the Earth may be moved by a sure rotation for its good, the Sun also and the stars helping its motion. But the simple straight motion downwards of the Peripateticks is a motion of weight, a motion of the aggregation of disjoined parts, in the ratio of their matter, along straight lines toward the body of the Earth: which lines tend the shortest way toward the centre. The motions of disjoined magnetical parts of the Earth, besides the motion of aggregation, are coition, revolution, and the direction of the parts to the whole, for harmony of form, and concordancy.
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CHAP. V.
Arguments of those denying the Earth's motion, and _their confutation._
Now it will not be superfluous to weigh well the arguments of those who say the Earth does not move; that we may be better able to satisfy the crowd of philosophizers who assert that this constancy and stability of the Earth is confirmed by the most convincing arguments. Aristotle does not allow that the Earth moves circularly, on the ground that each several part of it would be affected by this particular motion; that whereas now all the separate parts of the Earth are borne toward the middle in straight lines, that circular motion would be violent, and strange to nature, and not enduring. But it has been before proved that all actual portions of the Earth move in a circle, and that all magnetick bodies (fitly disposed) are borne around in an orbe. They are borne, however, toward the centre of the Earth in a {226} straight line (if the way be open) by a motion of aggregation as though to their own origin: they move by various motions agreeably to the conformation of the whole: a terrella is moved circularly by its innate forces. "Besides" (says he), "all things which are borne in an orbe, afterwards would seem to be abandoned by the first motion, and to be borne by several motions besides the first. The Earth must also be borne on by two sorts of motion, whether it be situate around a mid-point, or in the middle site of the universe: and if this were so, there must needs be at one time an advance, at another time a retrogression of the fixed stars: This, however, does not seem to be the case, but they rise and set always the same in the same places." But it by no means follows that a double motion must be assigned to the Earth. But if there be but one diurnal motion of the Earth around its poles, who does not see that the stars must always in the same manner rise and set at the same points of the horizon, even although there be another motion about which we are not disputing: since the mutations in the smaller orbit cause no variation of aspect in the fixed stars owing to their great distance, unless the axis of the Earth have varied its position, concerning which we raise a question when speaking of the cause of the præcession of the æquinoxes. In this argument are many flaws. For if the Earth revolve, that we asserted must needs occur not by reason of the first sphære, but of its innate forces. But if it were set in motion by the first sphære, there would be no successions of days and nights, for it would continue its course along with the _Primum Mobile_. But that the Earth is affected by a double movement at the time when it rotates around its own centre, because the rest of the stars move with a double motion, does not follow. Besides, he does not well consider the argument, nor do his interpreters understand the same. [Greek: toutou de sumbainontos, anankaion gignesthai parodous kai tropas tôn endedemenôn astrôn.] (Arist. _de Coelo_, ii. chap. 14.) That is, "If this be so, there must needs be changes, and retrogressions of the fixed stars." What some interpret as retrogressions or regressions, and changes of the fixed stars, others explain as diversions: which terms can in no way be understood of axial motion, unless he meant that the Earth moved by the _Primum Mobile_ is borne and turned over other poles diverse even from those which correspond to the first sphære, which is altogether absurd. Other later theorists suppose that the eastern ocean ought to be impelled so into western regions by that motion, that those parts of the Earth which are dry and free from water would be daily flooded by the eastern ocean. But the ocean is not acted upon by that movement, since nothing opposes it; and even the whole atmosphere is carried round: And for that reason in the Earth's course all the things in the air are not left behind by us nor do they seem to move toward the West: Wherefore also the clouds {227} are at rest in the air, unless the force of the winds drive them; and objects which are projected into the air fall again into their own place. But those foolish folk who think that towers, temples, and buildings must necessarily be shaken and overthrown by the Earth's motion, may fear lest men at the Antipodes should slip off into an opposite orbe, or that ships when sailing round the entire [249]globe should (as soon as they have dipped under the plane of our horizon) fall into the opposite region of the sky. But those follies are old wives' gossip, and the rubbish of certain philosophizers, men who, when they essay to treat of the highest truths and the fabrick of the universe, and hazard anything, can scarce understand aught _ultra crepidam_. They would have the Earth to be the centre of a circle; and therefore to rest motionless amid the rotation. But neither the stars nor the wandering globes move about the Earth's centre: the high heaven also does not move circularly round the Earth's centre; nor if the Earth were in the centre, is it a centre itself, but a body around a centre. Nor is it confident with reason that the heavenly bodies of the Peripateticks should attend on a centre so decadent and perishable as that of the Earth. They think that Nature seeks rest for the generation of things, and for promoting their increase while growing; and that accordingly the whole Earth is at rest. And yet all generation takes place from motion, without which the universal nature of things would become torpid. The motion of the Sun, the motion of the Moon, cause changes; the motion of the Earth awakens the internal breath of the globe; animals themselves do not live without motion, and the ceaseless activity of the heart and arteries. For of no moment are the arguments for a simple straight motion toward the centre, that this is the only kind in the Earth, and that in a simple body there is one motion only and that a simple one. For that straight motion is only a tendency toward their own origin, not of the parts of the Earth only, but of those of the Sun also, of the Moon, and of the rest of the sphæres which also move in an orbit. Joannes Costæus, who raises doubts concerning the cause of the Earth's motion, looking for it externally and internally, understands magnetick vigour to be internal, active, and disponent; also that the Sun is an external promotive cause, and that the Earth is not so vile and abject a body as it is generally considered. Accordingly there is a diurnal movement on the part of the Earth for its own sake and for its advantage. Those who make out that that terrestrial motion (if such there be) takes place not only in longitude, but also in latitude, talk nonsense. For Nature has set in the Earth determinate poles, and definite unconfused revolutions. Thus the Moon revolves with respect to the Sun in a monthly course; yet having her own definite poles, facing determinate parts of the heaven. To suppose that the air moves the Earth would be {228} ridiculous. For air is only exhalation, and is an enveloping effluvium from the Earth itself; the winds also are only a rush of the exhalations in some part near the Earth's surface; the height of its motion is slight, and in all regions there are various winds unlike and contrary. Some writers, not finding in the matter of the Earth the cause (for they say that they find nothing except solidity and consistency), deny it to be in its form; and they only admit as qualities of the Earth cold and dryness, which are unable to move the Earth. The Stoicks attribute a soul to the Earth, whence they pronounce (amid the laughter of the learned) the Earth to be an animal. This magnetick form, whether vigour or soul, is astral. Let the learned lament and bewail the fact that none of those old Peripateticks, nor even those common philosophizers heretofore, nor Joannes Costæus, who mocks at such things, were able to apprehend this grand and important natural fact. But as to the notion that surface inequality of mountains and valleys would prevent the Earth's diurnal revolution, there is nothing in it: for they do not mar the Earth's roundness, being but slight excrescences compared with the whole Earth; nor does the Earth revolve alone without its emanations. Beyond the emanations, there is no renitency. There is no more labour exerted in the Earth's motion than in the march of the rest of the Stars: nor is it excelled in dignity by some stars. To say that it is frivolous to suppose that the Earth rather seeks a view of the Sun, than the Sun of the Earth, is a mark of great obstinacy and unwisdom. Of the theory of the rotation we have often spoken. If anyone seek the cause of the revolution, or of other tendency of the Earth, from the sea surrounding it, or from the motion of the air, or from the Earth's gravity, he would be no less silly as a theorist than those who stubbornly ground their opinions on the sentiments of the ancients. Ptolemy's reasonings are of no weight; for when our true principles are laid down, the truth comes to light, and it is superfluous to refute them. Let Costæus recognize and philosophers see how unfruitful and vain a thing it becomes then to take one's stand on the principles and unproved opinions of certain ancients. Some raise a doubt how it can be that, if the Earth move round its own axis, a globe of iron or of lead dropped from the highest point of a tower falls exactly perpendicularly to a spot of the Earth below itself. Also how it is that cannon balls from a large culverin, fired with the same quantity and strength of powder, in the same direction and at a like elevation through the same air, would be cast at a like distance from a given spot both Eastward and Westward, supposing the Earth to move Eastward. But those who bring forward this kind of argument are being misled: not attending to the nature of primary globes, and the combination of parts with their globes, even though they be not adjoined by solid parts. Whereas the motion of the Earth in the diurnal revolution does not involve the separation of her more {229} solid circumference from the surrounding bodies; but all her effluvia surround her, and in them heavy bodies projected in any way by force, move on uniformly along with the Earth in general coherence. And this also takes place in all primary bodies, the Sun, the Moon, the Earth, the parts betaking themselves to their first origins and sources, with which they connect themselves with the same appetence as terrene things, which we call heavy, with the Earth. So lunar things tend to the Moon, solar things to the Sun, within the orbes of their own effluvia. The emanations hold together by continuity of substance, and heavy bodies are also united with the Earth by their own gravity, and move on together in the general motion: especially when there is no renitency of bodies in the way. And for this cause, on account of the Earth's diurnal revolution, bodies are neither set in motion, nor retarded; they do not overtake it, nor do they fall short behind it when violently projected toward East or West.
Let E F G be the Earth's globe, A its centre, L E the ascending effluvia: Just as the orbe of the effluvia progresses with the Earth, so also does the unmoved part of the circle at the straight line L E progress along with the general revolution. At L and E, a heavy body, M, falls perpendicularly toward E, taking the shortest way to the centre, nor is that right movement of weight, or of aggregation compounded with a circular movement, but is a simple right motion, never leaving the line L E. But when thrown with an equal force from E toward F, and from E toward G, it completes an equal distance on either side, even though the daily rotation of the Earth is in process: just as twenty paces of a man mark an equal space whether toward East or West: so the Earth's diurnal motion {230} is by no means refuted by the illustrious Tycho Brahe, through arguments such as these.
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{236} CHAP. IX.
On the anomaly of the Præcession of the Equinoxes, _and of the obliquity of the Zodiack._
At one time the shifting of the æquinoxes is quicker, at another slower, being not always equal: because the poles of the earth travel unequally in the arctick and antarctick circle of the Zodiack; and decline on both sides from the middle path: whence the obliquity of the Zodiack to the Æquator seems to change. And as this has become known by means of long observations, so also has it been perceived, that the true æquinoctial points have been elongated from the mean æquinoctial points, on this side and on that, by 70 minutes (when the prostaphæresis is greatest): but that the solstices either approach the equator unequally 12 minutes nearer, or recede as far behind; so that the nearest approach is 23 degrees 28 minutes, and the greatest elongation 23 degrees 52 minutes. Astronomers have given various explanations to account for this inequality of the præcession and also of the obliquity of the tropicks. Thebit, with the view of {237} laying down a rule for such considerable inequalities in the motion of the stars, explained that the eighth sphære does not move with a continuous motion from west to east; but is shaken with a certain motion of trepidation, by which the first points of Aries and Libra in the eighth heaven describe certain small circles with diameters equal to about nine degrees, around the first points of Aries and Libra in the ninth sphære. But since many things absurd and impossible as to motion follow from this motion of trepidation, that theory of motion is therefore long since obsolete. Others therefore are compelled to attribute the motion to the eighth sphære, and to erect above it a ninth heaven also, yea, and to pile up yet a tenth and an eleventh: In the case of mathematicians, indeed, the fault may be condoned; for it is permissible for them, in the case of difficult motions, to lay down some rule and law of equality by any hypotheses. But by no means can such enormous and monstrous celestial structures be accepted by philosophers. And yet here one may see how hard to please are those who do not allow any motion to one very small body, the Earth; and notwithstanding they drive and rotate the heavens, which are huge and immense above all conception and imagination: I declare that they feign the heavens to be three (the most monstrous of all things in Nature) in order that some obscure motions forsooth[251] may be accounted for. Ptolemy, who compares with his own the observations of Timocharis and Hipparchus, one of whom flourished 260 years, the other 460 years before him, thought that there was this motion of the eighth sphære, and of the whole firmament; and proved by help of numerous phenomena that it took place over the poles of the Zodiack, and, supposing its motion to be so far æquable, that the non-planetary stars in the space of 100 years completed just one degree beneath the _Primum Mobile_. After him 750 years Albategnius discovered that one degree was completed in a space of 66 years, so that a whole period would be 23,760 years. Alphonsus made out that this motion was still slower, completing one degree and 28 minutes only in 200 years; and that thus the course of the fixed stars went on, though unequally. At length Copernicus, by means of the observations of Timocharis, Aristarchus of Samos, Hipparchus, Menelaus, Ptolemy, Mahometes Aractensis, Alphonsus, and of his own, detected the anomalies of the motion of the Earth's axis: though I doubt not that other anomalies also will come to light some ages hence. So difficult is it to observe motion so slow, unless extending over a period of many centuries; on which account we still fail to understand the intent of Nature, what she is driving after through such inequality of motion. Let A be the pole of the Ecliptick, B C the Ecliptick, D the Æquator; when the pole of the Earth near the arctick circle of the Zodiack faces the point M, then there is an anomaly of the præcession of the æquinox at F; {238} but when it faces N, there is an anomaly of the præcession at E. But when it faces I directly, then the maximum obliquity G is observed at the solstitial colure; but when it faces L, there is the minimum obliquity H at the solstitial colure.
_Copernicus' contorted circlet in the Arctick circle of the Zodiack._
Let F B G be the half of the Arctick circle described round the pole of the Zodiack: A B C the solstitial colure: A the pole of the Zodiack; D E the anomaly of longitude 140 minutes at either side on both ends: B C the anomaly of obliquity 24 minutes: B the greater obliquity of 23 degrees 52 minutes: D the mean obliquity of 23 degrees 40 minutes: C the minimum obliquity of 23 degrees 28 minutes.
{239} [Illustration]
{240} The period of motion of the præcession of the æquinoxes is 25,816 Ægyptian years; the period of the obliquity of the Zodiack is 3434 years, and a little more. The period of the anomaly of the præcession of the æquinoxes is 1717 years, and a little more. If the whole time of the motion AI were divided into eight equal parts: in the first eighth the pole is borne somewhat swiftly from A to B; in the second eighth, more slowly from B to C; in the third, with the same slowness from C to D; in the fourth, more swiftly again from D to E; in the fifth, with the same swiftness from E to F; again more slowly from F to G; and with the same slowness from G to H; in the last eighth, somewhat swiftly again from H to I. And this is the contorted circlet of Copernicus, fused with the mean motion into the curved line which is the path of the true motion. And thus the pole attains the period of the anomaly of the præcession of the æquinoxes twice; and that of the declination or obliquity once only. It is thus that by later astronomers, but especially by Copernicus (the Restorer of Astronomy)[252], the anomalies of the motion of the Earth's axis are described, so far as the observations of the ancients down to our own times admit; but there are still needed more and exact observations for anyone to establish aught certain about the anomaly of the motion of the præcessions, and at the same time that also of the obliquity of the Zodiack. For ever since the time at which, by means of various observations, this anomaly was first observed, we have only arrived at half a period of the obliquity. So that all the more all these matters about the unequal motion both of the præcession and of the obliquity are uncertain and not well known: wherefore neither can we ourselves assign any natural causes for it, and establish it for certain. Wherefore also do we to our reasonings and experiments magnetical here set an end and period.[253]
* * * * *
{241}
INDEX.
Abano, Pietro di (Apponensis or Apianus), 2. Abbas, Hali ('Alí ibn Al 'Abb[=a]s, _Al Majúsi_, 2, 6. Abohalis, 47. _See also_ Avicenna. _aciarium_ or _acies_, also _aciare_, 18, 23, 33, 36. Acosta, Josephus, 5. adamant, 11. æquator, the magnetick, 13, 79. Aetius Amidenus, 2. Affaytatus, Fortunius, 6. agate, non electrick, 51, 53. Agricola, Georgius, 2, 3, 10, 19, 26, 111, 112. Agrippa, H. Cornelius, 3. _aimant_, 11. Albategnius (Muhammad ibn J[=a]bir, _Al-Batt[=a]ni_, 237. Albertus Magnus, 2, 7, 18, 111. Alexander Aphrodiseus, 3, 48, 92. Alexandria, Hero of, 58. Alfonso, Diego, 178. Alfonsus the Wise (Alphonsus X.), 237. Amalfians said to have first constructed the compass, 4. Amatus Lusitanus, 2. amber, 47, 49-60, 85, 112, 116. amethyst, electrical properties of, 48. amianth, 11. Amidenus, Aetius, 2. amphitane, 111. Anatolismus, or Northeasting, 167. Anaxagoras, 61, 208. Andrea Doria (Admiral), 4. Antonius de Fantis, 107. Antonius Musa Brasavolus, 2. Antony, the denarius of, 110. Apianus. _See_ Abano. Apponensis. _See_ Abano. Aquinas, Thomas, 3, 64. Aractensis, Mahometes, 234, 237. Archelaus, 208. Ardoynis, Santes de, 2. Arias Montanus, 4. Aristarchus, 214, 237. Aristotle: _De Anima_, 1, 11, 61, 210. _De Coelo_, 226, 232. _De Mirabilibus Auscultationibus_, 22. _Meteorologica_, 35, 39. on material of the metals, 19, 20. on the element of earth, 43. on motions, 45, 219, 225. on primary form, 65. on the _Primum Mobile_, 220. on animate nature of planets, 208. armature, 87. armed loadstones, 86, 87, 88, 89. Arnaldus de Villa nova, 2, 7. Arsinoe, Temple of, 2. Attraction, 46, 60, 64, 68, 90, 98, 109. Avicenna (Abu 'Ali Husain ibn 'Abd Allah, _Ibn Síná_; also called Abohalis): writes on the magnet, 2. on falling masses of iron, 26. alleges loadstone an antidote to iron poison, 35. on the property of attraction, 49. Augsburgers (Augustani), the, prescribe loadstone in plaster, 33. axis, the magnetick, 13, 81, 212. Azores, variation of compass at the, 4, 154, 156, 167.
Bacon, Roger, 5. Bambola, or Bilbilis, 23. Baptista Montanus, 2. Baptista Porta. _See_ Porta. Barbarus, Hermolaus, 3. Barlowe, William (Rev. Archdeacon), his book, _The Navigators Supply_, 8. basil leaves alleged not to be attracted, 48. belemnites are electrical, 48. Bencora (Th[=a]bit ibn Kurrah, _Al Harrani_; also called Thebitius), 117, 236. Benedictus, Joannes Baptista (Giambattista Benedetti), 167. beryl, electrick properties of, 48. Bessardus (Toussaincte de Bessard), 5, 116, 153. Blondus, Flavius, the historian, 4. Borough, William, his book on the _Variation of the Compass_, 8. Borrholybicum (North-north-west), 160. Brahe, Tycho, 174, 229. Brandoe, the island of, 181. Brasavolus, Antonius Musa, 2. Bristolla, or Bristol gem, 48. burnt clay, magnetick properties of, 26, 43. {242}
Cabot, Sebastian, 4. Cælius Calcagninus, 7. Cæsare, or Cesare, Giulio, 141. Calaber, Hannibal Rosetius, 3, _calamita_ or _kalamita_, 11. Calcagninus, Cælius, 7. Camillus Leonhardus, 3. Candish, or Cavendish, Thomas, *iij, 117. cap of iron for a loadstone, 86, 89, 90, 95. _carabe_, or _karabe_, 47. carbuncle, electrick properties of, 48, 111. Cardan, Hieronymo, 2. _De Proportionibus_: on iron and earth, 43, 62, 67. on distance of centre of cosmos, 169. _De Rerum Varietate_: on fall of meteorick iron, 26. on attraction of amber, 49. on a perpetual motion engine, 107. _De Subtilitate_: alleges magnet to feed on iron, 37, 63, 92. on magnet that draws silver, 110. on magnetick influence of star in tail of _Ursa Minor_, 5, 116, 153. carnelian, the, 51, 55. _catoblepas_, the antelope called, 63. Cesare, Giulio, 141. _chalybs_, 18, 25, 33. chatochitis, 111. chemists, the, 19, 20, 21, 24, 37, 66. China, 4, 8, 9, 11, 17, 32, 119. Chinocrates, 2. circumpulsion, doctrine of, 3, 61. clamps (open kilns), 26. clay when burnt is magnetick, 26, 43, 97. clepsydra, 231. Coimbra, College of, 5. coition (mutual attraction), 45, 46, 60, 65, 67, 68, 81, 98, 99, 103, 109, 131. definition of, *vj, 68. orbe of, *vj. colours of loadstones, 9, 10, 27. Como, 23. compass, alleged invention of, by Amalfians, 4. origin of the compass-card, 4, 165. the mariners' (_pyxis_), 3, 115, 147, 165, 172. the little (_pyxidula_), 181, 202. different forms of, Italian, Baltic, Portuguese, English, 165, 166, 177, 181. conduction, magnetick, 85, 104, 125. consequent poles, 129, 142. Copernican system, 231. Copernicus, Nicolas, 212, 214, 216, 231, 237, 238, 240. Cordus, Valerius, 10. Cornelius Agrippa, 3. Cornelius Gemma, 63. Cornelius Tacitus, 25. _corolla insorta_, or contorted circlet, 238, 240. Cortes, Martin, 5, 116, 152. Corvo, Island of, 167. Costa, Filippo (of Mantua), 141. Costæus, Joannes, 3, 62, 227, 228. _creagus_, the, or flesh-magnet, 110. crystal, rock, 48, 52, 59, 111 Curtius, Nicolaus, 35. Cusan (Michael Khrypffs), Cardinal de Cusa, 3, 64, 108. Cynosure, the, or Pole-star, 14, 81, 117, 222, 235.
Dean, Forest of, loadstone found in the, 11. decay of the magnetick virtue, 18, 37, 124, 138, 149. declination, the, or dip, 184. denarius of Antony, 110. diamond, an electrick, 48, 50, 59, 111. alleged power to attract iron, 109, 112. alleged antipathy to magnet, 2, 7, 109, 143. experiments upon, 143. Diego Alfonso, 178. Differences between electricks and magneticks, 47, 60, 65. Dioscorides, 1, 2, 9, 32. dip, the, also called declination, 8, 46, 184-204. dipping-needle, or declination instrument, 185, 203. direction, or directive force, 41, 46, 115, 119. dividing a loadstone, 16, 72, 100, 121, 122, 127, 130, 136, 145, 146. Dominicus Maria Ferrariensis, 212, 213. Doria, Andrea (Admiral), 4. Drake, Sir Francis, *iij _bis_, 117. Du Puys (also called Puteanus), 3, 63.
Earth, the, a great magnet, 38, 39, 40, 41, 44, 119, 211. _echeneis_ (the sucking fish), 7, 63, 110. Ecphantus, 214. effluvia, electrical, 52, 53, 59, 66. magnetical, 61. electrical attraction, 50, 51, 111. electrick force, definition of, 52. electricks, *vj, 46-60. _electrum_ ([Greek: êlektron]), 47. emerald is non-electrick, 51. emery, 22, 51. Empedocles, 208. Encelius (or Entzelt, Christoph.), 3, 111. Epicurius, 61, 62. Erasmus Rheinholdus, 213. Erastus, Thomas, 3, 22. errors in navigation, 166, 177. Evax, King of Arabia, 111. Euripides, 9, 11, 18. {243}
Fallopius, Gabriellus, 3, 34, 35, 112. Fantis, Antonius de, 107. Fernelius, Joannes Franciscus, 4. Ficinus, Marsilius (or Marsiglio Ficino), 3, 7, 116 153. filings of iron, 37, 69, 90, 91, 92, 104. Filippo Costa. _See_ Costa. fire destroys magnetick properties, 66, 67, 91, 124. flame destroys electrification, 59. flame hinders not magnetick attractions, 66. Flavius Blondus. _See_ Blondus. flies in amber, 47. form _versus_ matter, 52, 65. Fra Paolo, 6. Fracastorio, Hieronymo, 5, 50, 67, 71, 91, 110, 113, 152. Franciscus Maurolycus. _See_ Maurolycus. Franciscus Rueus. _See_ Rueus.
Gagates. _See_ jet. Galen, 2, 9, 32, 35, 39, 46, 49, 61, 62, 63. Gallus, Marbodæus, 2, 7. garlick, its reputed antagonism to magnetism, 2, 32, 64. Gartias ab Horto, 32. Gaudentius Merula, 7. Gauricus, Lucas, 7. Geber (J[=a]bir ibn Háiyán, _Al-Tarsus[=i]_) 21. Gemma, Cornelius, 63. gems, electrick properties of, 48, 51. _geniter_, 47. Georgius Agricola. _See_ Agricola. Gilbert, Adrian, 11. Gilgil Mauritanus, 19. Gioia, or Goia, of Amalfi, 4. Giulio Cæsare, 141. glass, an electrick by friction, 48, 54, 59. use of loadstone in making, 111. goat's blood, 7. Gonzalus Oviedus, 4. Goropius, Henricus Becanus, 4. Grotius, Hugo, 167, 168.
Haematite, 22, 51. Hali Abbas ('Ali ibn Al 'Abbás, _Al Masúfí_), 2, 6. Hannibal Rosetius Calaber, 3. Hariot, Thomas, 7. Heat, effect of on loadstone, 66, 67, 93, 123, 124. Helmshuda, 167. Heraclea, the city of, 8. Heraclean stone, or stone of Hercules, 8, 43, 61, 169. Heraclides, 214. Heraclitus, 208. Hermes, 209. Hermolaus Barbarus, 3. Hero of Alexandria, 58. Hipparchus, 213, 214, 234, 235, 237. Hippocrates, 8, 35, 51, 61. horizon, the magnetick, defined, 80. Horto, Gartias ab, 32. Horus, the bone of, or _Os Ori_, 9. hot iron not magnetick, 66. Hues, Robert, 7. Hugo Grotius, 167, 168.
Inclination. _See_ dip. interposition of bodies, 53, 66, 83, 85, 89, 137. iris gem, the, 48. iron, its nature and occurrence, 19, 20, 22, 25. filings of, 37, 69, 90, 91, 92, 104. its various names and qualities, 23, 33, 36. its various uses, 23, 24, 39, 86, 90, 95. medical uses of, 33, 35. surpasses loadstone, 69, 95. verticity in, 85, 123, 139. iron ore is magnetick, 18, 27, 38, 43. has poles, 28. islands, magnetick influence of, 5, 153,161.
Jacobus Severtius, 5. jet, 47, 48, 53, 55, 86. Joannes Baptista Porta. _See_ Porta. Joannes Baptista Montanus, 2. Joannes Costæus. _See_ Costæus. Joannes Franciscus Offusius, 46. Joannes Goia. _See_ Gioia. Joannes Langius, 3. Joannes Taisner, or Taisnier. _See_ Taisnier. Jofrancus Offusius, 46. Josephus Acosta, 5. Julius Cæsar Moderatus, 141. Julius Cæsar Scaliger. _See_ Scaliger.
Kendall, Abraham, 7, 178. Korrah, Thebitius Ben. _See_ Bencora.
Lactantius, Lucius, 219. Lagos, Rodriguez de, 177. Langius, Joannes, 3. _lapis magnetis_, 8. _lapis specularis_, muscovy stone, or mica, 11, 48, 52. latitude in relation to dip, 196, 200. Leonardus (or Leonhardus), Camillus, 3. Levinus Lemnius, 3. {244} lifting power of loadstones, 86, 89, 97. lily of the compass, 117, 152, 165, 177. liquids, electrical attraction of, 55. attraction on surface of, 57. Livio Sanuto, 5, 153, 167. loadstone armed and unarmed, 86, 87, 88. as medicine, 32. in plasters, 33. rock, the, 5, 6, 18, 116, 152. various names of, 11. colours of, 9, 10, 27. various sources of, 8, 25, 32. London, magnetick variation at, 154, 163. longitude, magnetick finding at, 166. long magnets, advantage of, 82, 83, 99, 101 Lucania, fall of meteorick stones in, 26. Lucas Gauricus, 7. Lucretius, 2, 3, 8, 49, 61. Lusitanus, Amatus, 2. Lynschoten, Hugo van, *iiij.
Magnes, [Greek: magnês], [Greek: magnêtis], 11. Magnesia, 8. Magnetick axis of terrella, 81, 212. axis of earth, 13, 81, 212. horizon, 80. meridian, 79, 152. mountains or rocks, 5, 6, 18, 116, 152. islands, 5, 153, 161. motions, the five, 45. Magnus, Albertus. _See_ Albertus. Magnus, Olaus, 5, 6. Mahometes Aractensis, 234, 237. Mahomet's tomb, 2. Manardus, Joannes, 35. Marbodæus Gallus, 2, 7. Marcellus Empiricus, 2. Marco Polo (Paulus Venetus), 4. mariners' compass. _See_ compass. Mars, saffron of (_Crocus Martis_), 34, 91. Marsiglio Ficino. _See_ Ficinus. Martin Cortes, 5, 116, 152. matter and form, 52, 65. Matthæus Silvaticus, 3. Matthiolus, Petrus, 2, 3. Mauritanus, Gilgil, 19. Mauritanus, Serapio, 2, 6. Maurolycus, Franciscus, 5, 42, 153, 180. medicinal use of iron, 33. of loadstone, 32. Medina, Pedro de, 166. Menelaus, 234, 237. meridian, magnetick, 79, 152, 163. Merula, Gaudentius, 7. meteorick stones, falls of, 26, 27. mica (or muscovy stone), 11, 48, 52. [Greek: mikrogê]. _See_ terrella. moisture stops electrick action, 53, 56. Montagnana, B., 35. Montanus, Arias, 4. Montanus, Joannes Baptista, 2. Moors, Serapio and the, 6. mountains, magnetick, 5, 6, 18, 116, 152. movement of trepidation, 117. Musa Brasavolus, Antonius, 2. muscovy stone, 11, 48, 52. _See also_ mica. myths of the magnet, 2, 3, 5, 6, 7, 18, 32, 63, 107, 109, 110, 111, 116, 143, 153, 228 motions, the various magnetical, 46.
Names of amber, 47. names of the loadstone, 11. names given to the magnetick poles, 15, 115, 125, 129. Nicander of Colophon, 8, 9. Nicetas, 214. Nicolas Copernicus, 212, 214, 216, 231, 237, 238, 240 Nicolaus Myrepsus, or Præpositas, 33. non-electrick bodies, 51, 55. Nonius, Petrus (Pedro Nuñez), 166. Norman, Robert, 5, 8, 153, 161, 162. supposes a point respective, 5, 153, 161, 162. his _Newe Attractive_, 8. discoverer of the dip, 8. Norumbega, the city of, 154. Nova Zembla, 152, 179.
Offusius, Jofrancus, 46. Olaus Magnus, 5, 6. opal becomes electrical, 48. orbe of virtue, 76, 96, 191, 205 orbes of planets, 208, 215. Oribasius, 2. Orpheus, 11, 61, 209. Oviedus, Gonzalus (Gonzalo Fernandez de Oviedo y Valdès), 4.
Pantarbes, 111. Paolo (Paulus Æginæ), 35. Paolo, Rev. Maestro (Fra Paolo Sarpi), 6 Paolo the Venetian (Marco Polo), 4. Paracelsus (Bombast von Hohenheim). asserts the stars to attract iron, 3. his emplastrum of loadstone, 33. his method of strengthening loadstones, 93. Parmenides, 208. pearls are not electrick, 51, 55. Pedro de Medina, 166. percussion excites verticity, 139. Peregrinus, Peter, his book, 5. on cause of magnetick direction, 5, 116, 153. on perpetual motion engine, 107. affirms a terrella to revolve daily, 223. {245} Peripateticks, the, 20, 41, 43, 45, 65, 218, 222, 225, 227, 228. perpetual motion machine, 107. Peter Peregrinus. _See_ Peregrinus. Peter Plancius. _See_ Plancius. Petrus Apponensis. _See_ Abano, Pietro di. Petrus Nonius. _See_ Nonius or Nuñez. Philolaus, 214. Philostratus, 111. Pictorio, G., 6, 49. _piedramant_, 11. Plancius, Peter, *v _bis._ planets, influence of, 20, 137, 142. plasters, magnetick, 32, 33. Plato, 3. in the _Io_, discusses name and properties of the magnet, 1, 9, 11, 18. in the _Timæus_, suggests the theory of circumpulsion, 61. his Atlantis, 159. on life in the universe, 208. Pliny (C. Plinius Secundus). on loadstone fables, 1, 2, 9, 18. his mistake about Æthiopian loadstones, 17. on the five kinds of loadstones, 9. on the alleged discovery of the loadstones, 8. on the alleged magnetick mountains, 18. on a locality where loadstone was found, 11. on the occurrence of iron in Spain, 25. on the Sagda and the Catochites, 111. on the silver denarius of Antony, 110. on the use of loadstone by glass-makers, 111. on the shadow of a gnomon of a sun-dial at Rome, 213. Plotinus, 218. Plutarch, Claudius. on the garlick fable, 32. says something flammable exists in amber, 54. his theory of circumpulsion, 3, 62. polarity. _See_ verticity. pole, the, elevation of, 200, 213. poles, magnetick, of a loadstone, 13, 41, 72, 81, 144. poles are not points, 12, 41, 72, 96. Polo, Marco, 4. Porta, Joannes Baptista (Giambattista della Porta). his narration of marvels, 6. on various tempering of iron, 24. asserts loadstone a mixture of stone and iron, 63. on his assertion that loadstones have hairs, 66. asserts vapour to be cause of attraction, 67. his error as to change of verticity, 73. suspends iron upwards by a thread, 92. his error as to centre of the orbe of virtue, 95. his error as to the polarity which causes repulsion, 102. his error as to magnetick opposing forces, 103. experiment with a balance, 108. his error as to iron being intoxicated, 138. his error as to iron excited by a diamond, 143. his error as to the pointing of a magnet, 144. proportion between loadstone and iron, 149. his error as to variation and longitude, 166. præcession of the Æquinoxes, 234, 236. _primum mobile_, the, 79, 214, 216, 218, 220, 226, 232, 237. prostaphæresis, 174, 236. Prutenical Tables, the, 235. Ptolemæus, Claudius. on loadstone fables, 2, 32. on the occurrence of loadstone and of iron, 9,25. on the dissolution of the earth, 91, 217, 218. alleged relation of regions with the planets, 137. on the elevation of the pole at different latitudes, 213, 214. on the _Primum Mobile_, and the diurnal movement of the stars, 216, 228, 234. on the anomalies of the earth's motion, 237. Puteanus, Gulielmus (Du Puys), 3, 63. pyrimachus (_i.e._, pyrites), 23. Pythagoras, 57, 208. _pyxidula_, 4, 181. _pyxis_, 3, 115, 147, 165, 172.
Radius, the, of the earth's orbit, 218. Rasis. _See_ Rhazes. rays of magnetick virtue, 95. Reinoldus, Erasmus (or Rheinholdus), 213. _remora_, the (or sucking fish), 7, 63, 110. resin becomes electrical by friction, 48, 52. respective points, 5, 153, 161, 162. reversal of polarity, 101, 137. revolution of the globe, 46, 81, 91, 220. repulsion, electrical, denied to exist, 113. Rhazes (Muhammad ibn Zakar[=i]y[=a]), 34, 35. rings, on the verticity of, 129. Rodriguez de Lagos, 177. Rosetius Calaber, Hannibal, 3. Ruellius, Joannes, 7. Rueus, Franciscus (de la Rue), 6.
Saffron of Mars, 34, 91, 93. sagda, or sagdo, the, 111. Sanuto, Livio, 5, 153, 167. sapphire, the, 48. scales of iron, 22. Scaliger, Julius Cæsar. on cause of magnetick direction, 5, 64, 153. on a fall of meteorick iron, 26. on preservation of loadstones, 37. on amber, 47. on magnetick attraction, 70. admits the loadstone to have a soul, 68. on diamond attracting iron, 112. scoria or slag of iron, 34, 35. sealing wax is electrical, 48, 53. Sebastian Cabot. _See_ Cabot. Serapio, or Serapio Mauritania (Yuhanná ibn Sarapion), 2, 6. Severtius, Jacobus, 5. shielding, magnetick, by iron plate, 83, 85. {246} _siderites_ ([Greek: sideritês]) 8, 11, 143. _siegelstein_ 11. silk suspension for magnetick iron, 29, 30. Silvaticus, Matthæus, 3. silver, loadstone for, 109, 110. similars, doctrine of attraction of, 50, 62. Simon Stevinus, *v _bis_, 167, 168. slate, magnetick properties of, 43. smeargel (emery), 22. Solinus, Caius Julius, 1, 9, 111. Solomon the King, 4. Sotacus, 9. Stadius, 213. stars are at various distances, 215. steel, 23, 39, 69, 71, 93, 95, 147. Stevinus, Simon, *v _bis_, 167, 168. _stomoma_ ([Greek: stomôma]) 23, 33, 36. Strabo, 25. _succinum_. _See_ amber. Sudini, or Sudavienses, 47. sulphur, electrical by friction, 48, 53, 56, 59. [Greek: sundromê], *vj. [Greek: sunentelecheia], 68. Sussex, iron ore in, 22. sympathy and antipathy, 65, 68, 112.
Tacitus, Cornelius, 25. Taisner, or Taisnier, Joannes, 5, 107. Tariassiona or Tarazona, 23. terrella. definition of, *vj, 12, 13. poles and axis of, 13, 72, 81, 144. divided into two parts, 72. magnetick vigour, diagram of, 74, 75. how small pieces of iron behave toward, 75, 76. orbe of virtue of, 76, 77, 104. "geography" of, 78. æquinoctial circle of, 79, 144. parallels of, 80, 211. magnetick horizon of, 80. proportion of the forces in, 81, 82. experiment with iron sphere, 85. small iron sphere and rod, 94, 102. centre of magnetick virtue in, 95. irregular terrella to exhibit variation, 155, 157. to illustrate the dip of the needle, 190, 192. analogy of, with the earth, 41, 78, 119, 211. testing loadstones, methods of, 108. Thales of Miletus, 11, 61, 68, 208, 210. _theamedes_, the, 18. Thebitius, or Thebit ben Korrah, 117, 236. Themistius, 71. Theophrastus, 1, 9, 11. Thomas Aquinas, 3, 64. tides, the cause of, 86. Tycho Brahe, 174, 229.
Variation of the compass, 7, 46, 79, 116, 151-163, 166, 167, 180. variation at the Azores, 4, 154, 156, 167. versorium, magnetick, definition of, *vj. use of, 13, 115, 147. versorium, non-magnetick, use of, 48, 49, 50. verticity, 28, 115, 119-147. acquired, 67, 68, 84, 85, 104, 123, 125, 129, 138, 139, 141, 142, 211. in iron plates touched by loadstone, 84. in iron sphere, 85. how, in iron, 123, 139, 212. in bracket in tower of St. Augustine's Church, Rimini, 141. similar at ends of rod touched in middle, 84, 129. by percussion, 139. through interposed matter, 67. not in bodies other than magnetick, 142. æquator separates two kinds of, 79. possessed by the earth, as a "Cause," 117. change of, through change of mass, 72. definition of, *vj. described, 119, 120, 121. destroyed by heat, 66, 93, 124. earth produces it in loadstone and iron, 42, 140, 211, 212. excited through greater distances in iron than in air, 104. exists in all shapes of loadstone, 76. helps the earth to keep its orbit, 224. inhærent in wrought iron, 31, 115. as a magnetick motion, 46. mutation of, 120, 137. magnitude of earth prevents variation of, 163, 164. none acquired by iron rubbed on æquator of terrella, 148. not affected by position of loadstone, 144. of one loadstone as affected by another, 69, 138. opposite, acquired by iron touched by loadstone, 115, 125, 129. parts having same repel, 122, 133. pole of, where last contact is, 149. strengthened in versoria, 147-150. strength of, decreases at once in both poles, 146. Villa nova, Arnaldus de, 2, 7. vincentina, the, 48. Vincent's Rock, gem of, 54.
Weather affects electricks, 48, 53, 55, 56. weighing the magnetick force, 108. Wright, Edward, his prefatory address, *iij _bis_, 7. wrought iron is magnetick, 29, 139.
Youth preserved by loadstone, 32.
Zeilam, the king of, 32. Zimiri, 11. Zoroaster, 209.
{247} THIS TREATISE BY WILLIAM GILBERT, OF COLCHESTER, PHYSICIAN OF LONDON, ON THE MAGNET, WAS FIRST PUBLISHT IN THE LATIN TONGUE IN LONDON IN THE YEAR OF OUR LORD M.D.C.; THIS ENGLISH TRANSLATION, WHICH WAS COMPLETED IN THE YEAR M.C.M., IS PRINTED FOR THE GILBERT CLUB, TO THE NUMBER OF TWO HUNDRED AND FIFTY COPIES, BY CHARLES WHITTINGHAM AND COMPANY, AT THE CHISWICK PRESS, TOOKS COURT, CHANCERY LANE, LONDON.
* * * * *
NOTES
ON THE
DE MAGNETE
OF
DR. WILLIAM GILBERT
PRIVATELY PRINTED
LONDON MCMI
"For out of olde feldes, as men seith, Cometh al this newe corn fro yeer to yere; And out of olde bokes, in good feith, Cometh al this newe science that men lere." --_Chaucer._
"I finde that you have vsed in this your tr[=a]slation greate art, knowledge, and discretion. For walking as it were in golden fetters (as al Translators doe) you notwithstanding so warilie follow your Auctor, that where he trippeth you hold him vp, and where he goeth out of the way, you better direct his foote. You haue not only with the Bee sucked out the best iuyce from so sweete a flower, but with the Silke-worme as it were wouen out of your owne bowels, the finest silke; & that which is more, not rude & raw silke, but finely died with the fresh colour of your owne Art, Invention, and Practise. If these Adamantes draw you not to effect this which you haue so happilie begunne: then let these spurres driue you forward: viz. Your owne promise, the expectation of your friends, the losse of some credit if you should steppe backe, the profit which your labours may yeeld to many, the earnest desire which you yourselfe haue to reviue this Arte, and the vndoubted acceptation of your paines, if you performe the same."--(Prefatory epistle of John Case, D. of Physicke, printed in R. Haydocke's translation of _The Artes of Curious Painting_, of Lomatius, Oxford, 1598.)
"This booke is not for every rude and unconnynge man to see, but for clerkys and very gentylmen that understand gentylness and scyence."--_Caxton._
CHISWICK PRESS: CHARLES WHITTINGHAM AND CO. TOOKS COURT, CHANCERY LANE, LONDON.
* * * * *
{ij}
BIBLIOGRAPHY OF _DE MAGNETE_.
I. (THE LONDON FOLIO OF 1600.) _Fol. *j. title_ GVILIELMI GIL | berti colcestren | sis, medici londi- | nensis, | DE MAGNETE, MAGNETI- | cisqve corporibvs, et de mag- | no magnete tellure; Physiologia noua, | plurimis & argumentis, & expe- | rimentis demonstrata. | _Printer's Mark_ | Londini | excudebat Petrvs Short anno | MDC. || _*j verso_ Gilbert's coat of arms. || _*ij_ Ad Lectorem || _*iij verso_ Ad gravissimvm doctissimvmqve ... || _*vj_ Verborum quorundam interpretatio. || _*vj verso_ Index capitum. || p. 1. GVILIELMI GILBERTI | DE MAGNETE, LIB. I. || p. 240. FINIS. | Errata. Without any colophon, printer's Mark, or date at end. _Folio. 8 ll. of preliminary matter._ ABCDEFGHIKLMNOPQRSTV, _all ternions, making 120 numbered leaves. One blank leaf at front and one at end. Page 114 at end of Liber II. blank. A folded woodcut plate inserted between p. 200 and p. 201. Woodcut initials, headlines and diagrams. All known copies except one have ink corrections in several pages, particularly pp. 11, 22, 47._
II. (THE STETTIN QUARTO OF 1628.) _Four preliminary unnumbered leaves, viz._ (1) _Bastard title_ GULIELMI GILBERTI | Tractatus | DE MAGNETE || _verso_ blank; (2) _Engraved title._ TRACTATVS | Siue | PHYSIOLOGIA NOVA | DE MAGNETE, | MAGNETICISQVE CORPO- | RIBVS ET MAGNO MAGNETE | tellure Sex libris comprehensus | ã | Guilielmo Gilberto Colcestrensi, | Medico Londinensi | ... Omnia nunc diligenter recognita & emen- | datius quam ante in lucem edita, aucta & figu- | ris illustrata operâ & studio | Wolfgangi LOCHMANS I.U.D. | & Mathemati: | Ad calcem libri adjunctus est Index Capi- | tum Rerum et Verborum locupletissimus | EXCVSVS SEDINI | Typis Gotzianis Sumptibus | _Ioh: Hallervordij._ | Anno MDC.XXVIII || _verso_ blank; (3) Præfatio; (4) Amicorum Acclamationes (verses) || _verso_ blank. _Sig._ A Ad Lectorem Candidum. _Sig._ A2 _verso_ Ad Gravissimum Doctissimum[=q] Virum. _Sig._ B2 Verborum quorundam interpretatio. _Verso_ blank, followed by twelve engraved plates numbered I. to XII. _Sig._ B3 is numbered as p. 1, and begins GVILIELMI GILBERTI | DE MAGNETE. | LIBER I. _Sig._ C _begins as p. 5_; _Sig._ D as p. 13; and so forth. The collation therefore is: 4 ll. unnumbered, ABCDEFGHIKLMNOPQRSTVXYZAaBbCcDdEeFfGgHhIiKkLlMm, _all fours. Pagination ends on_ p. 232, _which has Sig._ H_3 _in error for_ Hh_3, _being the end of the text. Verso of_ Hh_3 blank. Index capitum _begins fol._ [Hh_4] _and_ with Index Verborum _continues to verso of_ Mm_3. _Last leaf_ [Mm_4] _contains Errata, and instructions to binder to place plates: verso_ blank. _Quarto. Woodcut initials and diagrams. Without any colophon, printer's Mark, or date at end._ In some copies the engraved title differs, having the words _Ioh: Hallervordij._ replaced by the word _Authoris_.
{iij} III. (THE STETTIN QUARTO OF 1633.) _Four preliminary unnumbered leaves_, viz., (1) _title._ Tractatus, sive Physiologia Nova | de | MAGNETE, | Magneticisq; corporibus & magno | Magnate tellure, sex libris comprehensus, | a GUILIELMO GILBERTO Colce- | strensi, Medico Londinensi. | ... Omnia nunc diligenter recognita, & emendatius quam ante | in lucem edita, aucta & figuris illustrata, opera & studio D. | WOLFGANGI LOCHMANS, I.U.D. | & Mathematici. | Ad calcem libri adiunctus est Index capitum, Rerum & Verborum | locupletissimus, qui in priore æditione desiderabatur | SEDINI, | Typis GOTZIANIS. | ANNO M.DC. XXXII. || _verso_ blank; (2) Præfatio; (3) Amicorum acclamationes (verses) || _verso_ Claudianus de Magnete (verses); (4) _ibid._ _Sig._ A Ad Lectorem Candidum. _Sig._ A2 _verso_ Ad Gravissimum Doctissimumq. Virum. _Sig._ B2 Verborum quorundam interpretatio; _verso_ blank. _Sig._ B3 is numbered as p. 1, and begins GVILIELMI GILBERTI | DE MAGNETE. | LIBER I. _Sig._ C begins as p. 5; _Sig._ D as p. 13; and so forth. The Collation therefore is: 4 _ll._ unnumbered, A _to_ Mm, _all fours_. Pagination _ends on p. 232, which bears Sig._ H3 _in error for_ Hh3. _Verso of Sig._ Hh3. Errata. Index capitum _begins_ Hh4, _and with_ Index Verborum _extends to verso_ of Mm3. _The last leaf_ [Mm4] _bears the Instructions to binder, with verso_ blank. _There is no colophon, printer's Mark, or date at end. Quarto. Woodcut initials, and diagrams. Twelve etched plates of various sizes inserted._
With the exception of the preliminary matter and the Instructions to binder, the pagination is the same as in the edition of 1628, the pages in the body of the work being reprinted word for word; though with exceptions. For example, p. 18 in Ed. 1633 is one line shorter than in Ed. 1628. The etched plates are entirely different. It has been thought from the pagination being alike that these two editions were really the same with different plates, titles, and preliminary matter. But they are really different. The spacing of the words, letters and lines is different throughout, and there are different misprints. The watermarks of the paper also differ.
IV. (THE BERLIN "FACSIMILE" FOLIO OF 1892.) This is a photozincograph reproduction of the London folio of 1600. It lacks the ink emendations on pages 11, 22, 47, &c., found in the original, and is wanting also in some of the asterisks in the margins.
V. (THE AMERICAN TRANSLATION OF 1893.) Frontispiece portrait || _p. i. title_ WILLIAM GILBERT | OF COLCHESTER, | physician of London, | on the | Loadstone and Magnetic Bodies, | and on | the great magnet the earth. | A new Physiology, | demonstrated with many arguments and experiments. | A translation by | P. Fleury Mottelay, | ... | New York: | John Wiley & Sons, | 53 East Tenth Street | 1893. || _p. ii_ bears imprint of Ferris Bros. _Printers_, 326 Pearl Street, New York. || _p. iii._ reduced reproduction of title of 1600 edition || _verso_ the Gilbert arms || _p. v._ Translator's Preface || _p. ix._ Biographical Memoir || _p. xxxi._ Contents || _p. xxxvii._ Address of Edward Wright || _p. xlvii._ Author's Preface. || _p. liii._ Explanation of some terms. || pp. 1-358 text of the work. || p. 359 reduced reproduction of title of 1628 edition. || p. 360 _ditto_ of 1633 edition. || p. 361 _ditto_ of Gilbert's _De Mundo Nostro_ of 1651. || pp. 363 to 368 General Index. || Pages _xxx_, _xlvi_, _lii_, and 362 are blanks. There are no signatures. Octavo. Diagrams reduced from woodcuts of the folio of 1600. Some copies bear on title the imprint | London: | Bernard Quaritch, | 15 Piccadilly. ||
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{1} [Illustration]
NOTES ON THE _DE MAGNETE_ OF DR. WILLIAM GILBERT.
During the work of revising and editing the English translation of _De Magnete_, many points came up for discussion, requiring critical consideration, and the examination of the writings of contemporary or earlier authorities. Discrepancies between the texts of the three known editions--the London folio of 1600, and the two Stettin quartos of 1628 and 1633 respectively--demanded investigation. Passages relating to astrology, to pharmacy, to alchemy, to geography, and to navigation, required to be referred to persons acquainted with the early literature of those branches. Phrases of non-classical Latin, presenting some obscurity, needed explanation by scholars of mediæval writings. Descriptions of magnetical experiments needed to be interpreted by persons whose knowledge of magnetism enabled them to infer the correct meaning to be assigned to the words in the text. In this wise a large amount of miscellaneous criticism has been brought to bear, and forms the basis for the following notes. To make them available to all students of Gilbert, the references are given to page and line both of the Latin folio of 1600 and of the English edition of 1900. S. P. T.
[1] _THE GLOSSARY:_
Gilbert's glossary is practically an apology for the introduction into the Latin language of certain new words, such as the nouns _terrella_, _versorium_, and _verticitas_, and the adjectival noun _magneticum_, which either did not exist in classical Latin or had not the technical meaning which he now assigns to them. His _terrella_, or [Greek: mikrogê], as he explains in detail on p. 13, is a little magnetic model of the earth, but in the glossary he simply defines it as _magnes globosus_. Neither _terrella_ nor _versorium_ appears in any Latin dictionary. No older writer had used either word, though Peter Peregrinus (_De Magnete_, Augsburg, 1558) had described experiments with globular loadstones, and pivotted magnetic needles suitable for use in a compass had been known for nearly three centuries. Yet the pivotted needle was not denominated _versorium_. Blondo (_De Ventis_, Venice, 1546) does not use the term. Norman (_The Newe Attractiue_, London, 1581) speaks of the "needle or compasse," and of the "wyre." Barlowe (_The Navigators Supply_, London, 1597) speaks of {2} the "flie," or the "wier." The term _versorium_ (literally, the _turn-about_) is Gilbert's own invention. It was at once adopted into the science, and appears in the treatises of Cabeus, _Philosophia Magnetica_ (Ferrara, 1629), and of Kircher, _Magnes sive de Arte Magnetica_ (Coloniæ, 1643), and other writers of the seventeenth century. Curiously enough, its adoption to denote the pivotted magnetic needle led to the growth of an erroneous suggestion that the mariners' compass was known to the ancients because of the occurrence in the writings of Plautus of the term _versoriam_, or _vorsoriam_. This appears twice as the accusative case of a feminine noun _versoria_, or _vorsoria_, which was used to denote part of the gear of a ship used in tacking-about. Forcellini defines _versoria_ as "funiculus quo extremus veli angulus religatur"; while _versoriam capere_ is equivalent to "reverti," or (metaphorically) "sententiam mutare." The two passages in Plautus are:
EUT. Si huc item properes, ut istuc properas, facias rectius, Huc secundus ventus nunc est; cape modo vorsoriam; Hic Favonius serenu'st, istic Auster imbricus: Hic facit tranquillitatem, iste omnes fluctus conciet. (in _Mercat._ Act. V., sc. 2.)
CHARM. Stasime, fac te propere celerem recipe te ad dominum domum; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cape vorsoriam Recipe te ad herum. (in _Trinum._ Act. IV., sc. 3.)
The word _magneticum_ is also of Gilbert's own coinage, as a noun; as an adjective it had been certainly used before, at least in its English form, _magneticall_, which appears on the title-page of William Borough's _Discourse of the Variation of the Compasse_ (London, 1596). Gilbert does not use anywhere the noun _magnetismus_, _magnetism_. The first use of that noun occurs in William Barlowe's _Magneticall Aduertisements_ (1616), in the _Epistle Dedicatorie_, wherein, when speaking of Dr. Gilbert, he says "vnto whom I communicated what I had obserued of my selfe, and what I had built vpon his foundation of the _Magnetisme_ of the earth." Gilbert speaks of the _virtus magnetica_, or _vis magnetica_; indeed, he has a rich vocabulary of terms, using, beside _virtus_ and _vis_, _vires_, _robur_, _potestas_, _potentia_, _efficientia_, and _vigor_ for that which we should now call _magnetism_ or _the magnetic forces_. Nor does he use the verb _magnetisare_, or its participle, _magnetisatus_: he speaks of _ferrum tactum_, or of _ferrum excitatum a magnete_. In spite of certain obscurities which occur in places in his work, he certainly shows a nice appreciation of words and their use, and a knowledge of style. One finds occasionally direct quotations from, and overt references to, the classic authors, as in the references to Plato and Aristotle on page 1, and in the passage from the Georgics of Vergil on p. 21. But here and there one finds other traces of unmistakable scholarship, as in the reference to goat's wool on p. 35, or in the use, on p. 210, of the word _perplacet_, which occurs in the letter of Cicero _ad Atticum_, or in that of _commonstrabit_, occurring on p. 203, and found only in Cicero, Terence and Plautus; whilst the phrase on p. 3, in which Gilbert rallies the smatterers on having lost both their oil and their pains, has a delightfully classical echo. {3} The term _orbis virtutis_, defined by Gilbert in the glossary, and illustrated by the cuts on pages 76, 77, and 96, might be effectively translated by _sphere of influence_, or _orbit within which there is sensible attraction_. It has been preferred, however, to translate it literally as the _orbe of virtue_, or _orbe of magnetick virtue_. This choice has been determined by the desire to adopt such an English phrase as Gilbert would himself have used had he been writing English. T. Hood, writing in 1592 in his book _The Vse of both the Globes_, in using the word _orbe_, says that the word _globe_ signifies a solid body, while a _sphere_ is hollow, like two "dishes joyned by the brimme"; "The Latines properly call _Orbis_ an Orbe"; "Moreouer the word _Sphaera_ signifieth that instrument made of brasen hoopes (wee call it commonly a ringed Sphere) wherewith the Astronomers deliuer unto the nouices of that Science the vnderstanding of things which they imagine in the heauen." Further, Dr. Marke Ridley in his _Treatise of Magneticall Bodies and Motions_ (1613), has a chapter (XIIII) "Of the distance and Orbe of the Magnets vertue," throughout which the term Orbe is retained. Sir Thomas Browne also writes of "the orb of their activities."
The word _Coitio_, used by Gilbert for the mutual force between magnet and iron, has been retained in its English form, _coition_. Gilbert evidently adopted this term after much thought. The Newtonian conception of action and reaction being necessarily equal had not dawned upon the mediæval philosophers. The term _attraction_ had been used in a limited sense to connote an action in which a force was conceived of as being exerted on one side only. Diogenes of Apollonia, Alexander Aphrodiseus, Democritus, and others, conceived the magnet to draw at the iron without the iron in any way contributing to that action. Saint Basil specially affirms that the magnet is not drawn by iron. On the other hand, Albertus Magnus had conceived the idea that the iron sought the magnet by a one-sided effort in which the magnet took no part. Gilbert had the wit to discern that the action was mutual, and to mark the new conception he adopted the new term, and defined it as it stands in his glossary. It is "a concourse or concordancy of both," and to emphasize his meaning he adds, "not as if there were an [Greek: helktikê dunamis] but a [Greek: sundromê]" not a tractile power, but a running together. The adjective [Greek: helktikê] is obviously related to the verb [Greek: helkô], I draw: but its meaning puzzled the subsequent editors of the text, for in the two Stettin editions of 1628 and 1633, the phrase appears in the respective forms of [Greek: helêtikê dunamis] and [Greek: helkustikê dunamis]. In Creech's English version of Lucretius (edition of 1722, p. 72a, in the footnote) is the commentary "Galen, disputing against Epicurus, uses the term [Greek: helkein], which seems likewise too violent." It may be noted that the same verb occurs in the passage from the _Io_ of Plato quoted below. The term [Greek: sundromê] applied by Gilbert to explain his term _Coitio_ is used by Diodorus for the mutual onset of two hostile forces.
A picturesque sentence from Sir Thomas Browne's _Pseudodoxia Epidemica_ (London, 1650, p. 51) sets the matter succinctly forth. "If in two skiffs of cork, a Loadstone and Steel be placed within the orb of their activities, the one doth not move the other standing still, but both hoist sayle and steer unto each other; so that if the Loadstone attract, the Steel hath also its attraction; for in this action the Alliency is reciprocall, which jointly felt, they mutually approach and run into each others arms." {4} The page and line references given in these notes are in all cases first to the Latin edition of 1600, and secondly to the English edition of 1900.
[2] PAGE 1, LINE 28. Page 1, line 28. _Plato in Ione._--The passage in the _Io_ of Plato is in chap. v. Socrates addressing the poet Io tells him that his facility in reciting Homer is not really an art: [Greek: theia de dunamis, hê se kinei hôsper en têi lithôi, hên Euripidês men Magnêtin ônomasen, hoi de polloi Hêrakleian. kai gar autê hê lithos ou monon autous tous daktulious agei tous sidêrous, alla kai dunamin entithêsi tois daktuliois, ôst au dunasthai tautou touto poiein, hoper hê lithos, allous agein daktulious, hôst' enioth' hormathos makros panu sidêriôn kai daktuliôn ex allêlôn êrtêtai pasi de toutois ex ekeinês tês lithou hê dunamis anêrtêtai.] The idea is that as the loadstone in attracting an iron ring will make it into a magnet, which can in turn act magnetically on another ring, and this on yet another, so the inspiration of the Muse is transferred to the poet, who in turn hands on the inspiration through the reciter to the listener. After further expanding the same idea of the transference of influence, Socrates again mentions the magnet (chap. vii.): [Greek: Oisth' oun hoti outos estin ho theatês tôn daktuliôn ho eschatos, hôn egô elegon hupo tês Hêrakleiôtidos lithou ap' allêlôn tên dunamin lambanein, ho de mesos su ho rhapsôdos kai hupokritês, ho de prôtos autos ho poiêtês? ho de theos dia pantôn toutôn helkei tên psuchên hopoi an boulêtai tôn anthrôpôn, k.t.l.] (Edition Didot of 1856, vol. i., p. 391; or Stephanus, p. 533 D).
There is another reference in Plato to the magnet, namely, in the _Timæus_ (p. 240, vol. ii., Edit. citat.). See the Note to p. 61.
The reference by Euripides to the magnet occurs in the lost play of Oeneus, in a fragment preserved by Suidas. See _Fragmenta Euripidis_ (Ed. Didot, 1846, p. 757, or Nauck's edition, No. 567).
[Greek: hôs Euripidês en Oinei; tas brotôn gnômas skopôn, hôste Magnêtis lithos tên doxan helkei kai methistêsin palin.]
[3] PAGE 1, LINE 28. Page 1, line 29. The brief passage from Aristotle's _De Anima_ referring to Thales is quoted by Gilbert himself at the bottom of p. 11.
[4] PAGE 2, LINE 1. Page 1, line 29. The edition of 1628 inserts commas between Theophrastus and Lesbius, and between Julius and Solinus, as though these were four persons instead of two.
[5] PAGE 2, LINE 8. Page 2, line 5. _si allio magnes illitus fuerit, aut si adamas fuerit_. An excellent version of this myth is to be found in Julius Solinus, _Polyhistor, De Memorabilibus_, chap. lxiv., of which the English version of 1587, by A. Golding, runs thus: "The Diamonde will not suffer the Lodestone to drawe yron unto him: or if y^e Lodestone haue alreadie drawne a peece of yron to it, the Diamond snatcheth and pulleth away as hys bootye whatsoever the Lodestone hath taken hold of." Saint Augustine repeats the diamond myth in his _De Civitate Dei_, lib. xxi. Baptista Porta says (p. 211 of the English version of 1658): "It is a common Opinion amongst Sea-men, That Onyons and Garlick are at odds with the Loadstone: and Steers-men, and such as tend the Mariners Card are forbid to eat Onyons or Garlick, lest they make the Index of the Poles drunk. But when I tried all these things, found them to be false: for not onely breathing and belching upon the Loadstone after eating of Garlick, did not stop its vertues: but when it was all anoynted over with the juice of Garlick, it did perform its office as well as if it had never been touched with it: and I could observe almost not the least difference, lest I should make void the endeavours of the Ancients. {5} And again, When I enquired of Marines, whether it were so, that they were forbid to eat Onyons and Garlick for that reason; they said, they were old Wives fables, and things ridiculous; and that Sea-men would sooner lose their lives, then abstain from eating Onyons and Garlick."
The fables respecting the antipathy of garlick and of the diamond to the operation of the magnet, although already discredited by Ruellius and by Porta, died hard. In spite of the exposure and denunciations of Gilbert--compare p. 32--these tales were oft repeated during the succeeding century. In the appendix to Sir Hugh Plat's _Jewel House of Art and Nature_, in the edition of 1653, by D. B. Gent, it is stated there (p. 218): "The Loadstone which ... hath an admirable vertue not onely to draw Iron to it self, but also to make any Iron upon which it is rubbed to draw iron also, it is written notwithstanding, that being rubbed with the juyce of Garlick, it loseth that vertue, and cannot then draw iron, as likewise if a Diamond be layed close unto it."
Pliny wrote of the alleged antipathy between diamond and goat's blood. The passage as quoted from the English version of Pliny's _Natural Historie of the World_, translated by Philemon Holland (London, 1601, p. 610, chap, iv.), runs: "But I would gladly know whose invention this might be to soake the Diamond in Goats bloud, whose head devised it first, or rather by what chance was it found out and knowne? What conjecture should lead a man to make an experiment of such a singular and admirable secret, especially in a goat, the filthiest beast ... in the whole world? Certes I must ascribe both this invention and all such like to the might and beneficence together of the divine powers: neither are we to argue and reason how and why Nature hath done this or that? Sufficient is it that her will was so, and thus she would have it."
[6] PAGE 2, LINE 22. Page 2, line 22. _Machometis sacellum._ Gilbert credits Matthiolus (the well-known herbalist and commentator on Dioscorides) with producing the fable as to Mahomet's coffin being suspended in the air by a magnet. Sir Richard Burton, in his famous pilgrimage to El Medïnah in 1855, effectually disposed of this myth. The reputed sarcophagus rests simply on bricks on the floor. But it had long been known that aerial suspension, even of the lightest iron object, in the air, without contact above or below, was impossible by any magnetic agency.
In Barlowe's _Magneticall Aduertisements_ (London, 1616, p. 45) is the following: "As for the Turkes _Mahomet_, hanging in the ayer with his yron chest it is a most grosse untruth, and utterly impossible it is for any thing to hange in the ayer by any _magneticall_ power, but that either it must touch the stone it selfe, or else some intermediate body, that hindreth it from comming to the stone (like as before I haue shewed) or else some stay below to keepe it from ascending, as some small wier that may scantly bee seene or perceived."
[7] PAGE 2, LINE 26. Page 2, line 26. _Arsinoes templum._--The account in Pliny of the magnetic suspension of the statue of Arsinoe in the temple built by Chinocrates is given as follows in the English version (London, 1601) of Philemon Holland (p. 515): "And here I cannot chuse but acquaint you with the singular invention of that great architect and master deviser, of Alexandria in Ægypt _Dinocrates_, who began to make the arched roufe of the temple of _Arsinoe_ all of Magnet or this Loadstone, to the end, that within that temple the statue of the said princesse made of yron, might seeme to hang in the aire by nothing. But prevented he was by death {6} before hee could finish his worke, like as king _Ptolomæe_ also, who ordained that temple to be built in the honour of the said _Arsinoe_ his sister."
There are a number of similar myths in Ausonius, Claudian, and Cassiodorus, and in the writings of later ecclesiastical historians, such as Rusinus and Prosper Aquitanus. The very meagre accounts they have left, and the scattered references to the reputed magical powers of the loadstone, suggest that there existed amongst the primitive religions of mankind a _magnet-worship_, of which these records are traces.
[8] PAGE 2, LINE 37. Page 2, line 41. _Brasevolus_ [or _Brasavola_].--The list of authorities here cited consists mostly of well-known mediæval writers on _materia medica_ or on minerals: the last on the list, _Hannibal Rosetius Calaber_, has not been identified.
The following are the references in the order named by Gilbert:
Antonio Musa Brasavola. _Examen omnium simplicium medicamentorum_, Section 447 (Lugdun., 1537).
Joannes Baptista Montanus. _Metaphrasis summaria eorum quæ ad medicamentorum doctrinà attinet_ (Augustæ Rheticæ, 1551).
Amatus Lusitanus. _Amati Lusitani in Dioscoridis Anazarbei de materia medica libros quinque_ (Venet., 1557, p. 507).
Oribasius. _Oribasii Sardiani ad Eunapium libri 4 quibus ... facultates simplicium ... continentur_ (Venet., 1558).
Aetius Amidenus. _Aetii Amideni Librorum medicinalium ... libri octo nunc primum in lucem editi_ (Greek text, Aldine edition, Venet., 1534). A Latin edition appeared in Basel, 1535. See also his _tetrabiblos ex veteribus medicinæ_ (Basil., 1542).
Avicenna (Ibn Sinâ). _Canona Medicinæ_ (Venice, 1486), liber ii., cap. 474.
Serapio Mauritanus (Yuhanná Ibn Sarapion). In hoc volumine continentur ... _Ioan. Sarapionis Arabis de Simplicibus Medicinis opus præclarum et ingens ..._ (edited by Brunfels, Argentorati, 1531, p. 260).
Hali Abbas ('Alí Ibn Al 'Abb[=a]s). _Liber totius medicinæ necessaria c[=o]tinens ... quem Haly filius Abbas edidit ... et a Stephano ex arabica lingua reductus_ (Lugd., 1523, p. 176 _verso_).
Santes de Ardoniis (or Ardoynis). _Incipit liber de venenis quem magister santes de ardoynis ... edere cepit venetiis die octauo nou[=e]bris_, 1424 (Venet., 1492).
Petrus Apponensis (or Petrus de Abano). The loadstone is referred to in two works by this author.
(1) _Conciliator differentiarum philosophorum: et precipue medicorum clarissimi viri Petri de Abano Patauini feliciter incipit_ (Venet., 1496, p. 72, _verso_, Quæstio LI.).
(2) _Tractatus de Venenis_ (Roma, 1490, cap. xi.).
Marcellus (called Marcellus Empiricus). _De Medicamentis_, in the volume _Medici antiqui omnes_ (Venet., 1547, p. 89).
Arnaldus (Arnaldus de Villa Nova). _Incipit Tractatus de virtutibus herbarum_ (Venet., 1499). See also _Arnaldi Villanovani Opera omnia_ (Basil., 1585).
Marbodeus Gallus. _Marbodei Galli poetae vetustissimi de lapidibus pretiosis Enchiridion_ (Friburgi, 1530 [1531], p. 41).
Albertus Magnus. _De Mineralibus et rebus metallicis_ (Venet., 1542, lib. ii., _de lapidibus preciosis_, p. 192). There is a reference to the loadstone {7} also in a work attributed falsely to Albertus, but now ascribed to Henricus de Saxonia, _De virtutibus herbarum, de virtutibus lapidum_, etc. (Rouen, 1500, and subsequent editions). An English version, _The Secrets of Albertus Magnus of the vertues of hearbs stones and certaine beasts_ was publisht in London in 1617.
Matthæus Silvaticus. _Pandectæ Medicinæ_ (Lugduni, 1541, cap. 446).
Hermolaus Barbarus. His work, _Hermolai Barbari Patritii Veneti et Aqvileiensis patriarchæ Corollarii Libri quinque ..._ Venet., 1516, is an early herbal. On p. 103 are to be found descriptions of _lapis gagatis_ and _lapis magnes_. The latter is mostly taken from Pliny, and mentions the alleged theamedes, and the myth of the floating statue.
Camillus Leonardus. _Speculum Lapidum_ (Venet., 1502, fol. xxxviii.). An English translation, _The Mirror of Stones_, appeared in London in 1750.
Cornelius Agrippa. _Henrici Cor. Agrippæ ab Nettesheym ... De Occulta Philosophia Libri Tres_ (Antv., 1531). The English version _Of the Vanitie and uncertaintie of Artes_ was publisht in London, 1569, and again later.
Fallopius (Gabriellus). _G. F. de simplicibus medicamentis purgantibus tractatus_ (Venet., 1566). See also his _Tractatus de compositione medicamentorum_ (Venet., 1570).
Johannes Langius. _Epistolarum medicinalium volumen tripartitum_ (Paris, 1589, p. 792).
Cardinalis Cusanus (Nicolas Khrypffs, Cardinal de Cusa). _Nicolai Cusani de staticis experimentis dialogus_ (Argentorati, 1550). The English edition, entitled _The Idiot in four books_, is dated London, 1650.
[9] PAGE 3, LINE 1. Page 2, line 42. _Marcellus_.--"Marcellus Empiricus, médecin de Théodose-le-Grand, dit que l'aimant, appelé _antiphyson_, attire et repousse le fer." (Klaproth, _Sur l'invention de la boussole_, 1834, p. 12.) The passage from Marcellus runs: "Magnetes lapis, qui antiphyson dicitur, qui ferrum trahit et abjicit, et magnetes lapis qui sanguinem emittit et ferrum ad se trahit, collo alligati aut circa caput dolori capitis medentur." (Marcellus, _de Medicamentis_: in the volume _Medici antiqui omnes, qui latinis literis morborum genera persecuti sunt_. Venet., 1547, p. 89.)
[10] PAGE 3, LINE 11. Page 3, line 9. _Thomas Erastus_.--The work in question is _Dispvtationvm de Medicina nova Philippi Paracelsi, Pars Prima: in qua quæ de remediis svperstitiosis & Magicis curationibus ille prodidit, præcipuè examinantur à Thoma Erasto in Schola Heydebergensi, professore_. (Basiliæ, 1572. Parts 2 and 3 appeared the same year, and Part 4 in 1573.)
Gilbert had no more love for Paracelsus than for Albertus Magnus or others of the magic-mongers. Indeed the few passages in Paracelsus on the magnet are sorry stuff. They will mostly be found in the seventh volume of his collected works (_Opera omnia_, Frankfurt, 1603). A sample may be taken from the English work publisht in London, 1650, with the title: _Of the Nature of Things, Nine Books; written by Philipp Theophrastus of Hohenheim, called Paracelsvs_.
"For any Loadstone that Mercury hath but touched, or which hath been smeered with Mercuriall oyle, or only put into Mercury will never draw Iron more" (p. 23).
"The life of the Loadstone is the spirit of Iron; which may bee extracted, and taken away with spirit of Wine" (p. 32).
[11] PAGE 3, LINE 13. Page 3, line 11. _Encelius_ (or _Entzelt_, Christoph) {8} wrote a work publisht in 1551 at Frankfurt, with the title _De re metallica, hoc est, de origine, varietate, et natura corporum metallicorum, lapidum, gemmarum, atque aliarum quæ ex fodinis eruuntur, rerum, ad medicine usum deservientium, libri iii_. This is written in a singular medley of Latin and German. Gilbert undoubtedly took from it many of his ideas about the properties of metals. See the note to p. 27 on _plumbum album_.
[12] PAGE 3, LINE 20. Page 3, line 21. _Thomas Aquinas._--The reference is to his commentaries upon the _Physica_ of Aristotle. The passage will be found on p. 96 _bis_ of the Giunta edition (Venet., 1539). The essential part is quoted by Gilbert himself on p. 64.
[13] PAGE 3, LINE 39. Page 3, line 45. _pyxidem._--The word _pyxis_, which occurs here, and in the next sentence as _pyxidem nauticam_, is translated _compass_. Eleven lines lower occurs the term _nautica pyxidula_. This latter word, literally the "little compass," certainly refers to the portable compass used at sea. Compare several passages in Book IV. where a contrasting use is made of these terms; for example, on pp. 177 and 202. Calcagninus, _De re nautica_, uses the term _pyxidecula_ for an instrument which he describes as "vitro intecta." On p. 152, line 9, Gilbert uses the non-classical noun _compassus_, "boreale lilium compassi (quod Boream respicit)," and again on p. 178, line 3.
[14] PAGE 4, LINE 2. Page 4, line 2. _Melphitani._--The inhabitants of Amalfi in the kingdom of Naples. The claim of the discovery or invention of the mariners' compass in the year 1302 by one Joannes Goia, or Gioia, also named as Flavio Goia, has been much disputed. In Guthrie's _New System of Modern Geography_ (London, 1792, p. 1036), in the Chronology, is set down for the year 1302:
"The mariner's compass invented, or improved by Givia, of Naples. The flower de luce, the arms of the Duke of Anjou, then King of Naples, was placed by him at the point of the needle, in compliment to that prince."
In 1808 an elaborate treatise was printed at Naples, by Flaminius Venanson with the title, _De l'invention de la Boussole Nautique_. Venanson, who cites many authorities, endeavours to prove that if Gioia did not discover magnetic polarity he at least invented the compass, that is to say, he pivotted the magnetic needle and placed it in a box, with a card affixed above it divided into sixteen parts bearing the names of the sixteen principal winds. He alleges in proof that the compass-card is emblazoned in the armorial bearings of the city of Amalfi. This view was combatted in the famous letter of Klaproth to Humboldt publisht in Paris in 1834. He shows that the use of the magnetized needle was known in Europe toward the end of the twelfth century; that the Chinese knew of it and used it for finding the way on land still earlier; that there is no compass-card in the arms of the city of Amalfi; but he concedes that Gioia may have improved the compass in 1302 by adding the wind-rose card. The most recent contributions to the question are a pamphlet by Signorelli, _Sull' invenzione della Bussola nautica, ragionamento di Pietro Napoli Signorelli, segretario perpetuo della Società Pontaniana; letto nella seduta del 30 settembre 1860_; Matteo Camera's _Memorie Storico-diplomatiche dell' antica città e ducato di Amalfi_ (Salerno, 1876); and Admiral Luigi Fincati's work _Il Magnete, la Calamita, e la Bussola_ (Roma, 1878). An older mention of Gioia is to be found in Blundevile's _Exercises_ (3rd edition, 1606, pp. 257-258). See also Crescentio _della Nautica Mediterranea_, (Roma, 1607, p. 253), and Azuni, _Dissertazione sull' origine della bussola nautica_ (Venezia, 1797). {9}
There appears to be a slip in Gilbert's reference to Andrea Doria, as he has confounded the town of Amalfi in Principato Citra with Melfi in Basilicata.
One of the sources relied upon by historians for ascribing this origin of the compass is the _Compendia dell' Istoria del Regno di Napoli_, of Collenuccio (Venet., MDXCI.), p. 5.
"Nè in questo tacerò Amalfi, picciola terra, & capo della costa di Picentia, alia quale tutti quelli, che'l mar caualcano, vfficiosamente eterno gratie debono referire, essendo prima in quella terra trovato l'vso, & l'artificio della calamita, & del bussolo, col quale i nauiganti, la stella Tramontana infallibilmente mirando, direzzano il lor corso, si come è publica fama, & gli Amalfitani si gloriano, nè senza ragione dalli piu si crede, essendo cosa certa, che gli antichi tale instromento non hebbero; nè essendo mai in tutto falso quello, che in molto tempo è da molti si diuolga."
Another account is to be found in the _Historiarum sui temporis_, etc., of Paulus Jovius (Florent., 1552), tom. ii., cap. 25, p. 42.
"Quum essem apud Philippum superuenit Ioachinus Leuantius Ligur a Lotrechio missus, qui deposceret captiuos; sed ille negauit se daturum, quando eos ad ipsum Andream Auriam ammirantem deducendos esse iudicaret. Vgonis uerò cadauer, ut illudentium Barbarorum contumeliis eriperetur, ad Amalphim urbem delatum est, in ædeque Andreæ apostoli, tumultuariis exequiis tumulatum. In hac urbe citriorum & medicorum odoratis nemoribus æquè peramoena & celebri, Magnetis usum nauigantibus hodie familiarem & necessarium, adinuentum suisse incolæ asserunt."
Flavius Blondus, whom Gilbert cites, gives the following reference, in which Gioia's name is not mentioned, in the section upon Campania Felix of his Italy (_Blondi Flavii Forlinensis ... Italia Illustrata_, Basiliæ, 1531, p. 420).
"Sed fama est qua Amalphitanos audiuimus gloriari, magnetis usum, cuius adminiculo nauigantes ad arcton diriguntur, Amalphi suisse inuentum, quicquid uero habeat in ea re ueritas, certû est id noctu nauigandi auxilium priscis omnino suisse incognitum."
There is a further reference to the alleged Amalphian in Caelius Calcagninus _De re nautica commentatio_. (_See Thesaurus Græcarum Antiquitatum_, 1697, vol. xi., p. 761.) On the other hand Baptista Porta, who wrote in Naples in 1558 (_Magia Naturalis_) distinctly sets aside the claim as baseless.
William Barlowe, in _The Navigators Supply_ (1597, p. A3), says: "Who was the first inuentor of this Instrument miraculous, and endued, as it were, with life, can hardly be found. The lame tale of one _Flauius_ at _Amelphis_, in the kingdome of _Naples_, for to haue deuised it, is of very slender probabilitie. _Pandulph Collenutius_ writing the Neapolitane historie telleth vs, that they of _Amelphis_ say, it is a common opinion there, that it was first found out among them. But _Polidore Virgil_, who searched most diligently for the Inuentors of things, could neuer heare of this opinion (yet himselfe being an Italian) and as he confesseth in the later ende of his third booke _de inventoribus rerum_, could neuer vnderstand anything concerning the first inuention of this instrument."
According to Park Benjamin (_Intellectual Rise in Electricity_, p. 146) the use of the pivotted compass arose and spread not from Amalfi at the hands of Italians in the fourteenth century, but from Wisbuy, at the hands of the Finns, in the middle of the twelfth century. {10}
Hakewill (_An Apologie or Declaration of the Power and Providence of God_, London, 1673, pp. 284-285) says:
"But _Blondus_, who is therein followed by _Pancirollus_, both _Italians_, will not haue _Italy_ loose the praise thereof, telling vs that about 300 yeares agoe it was found out at Malphis or Melphis, a Citty in the Kingdome of _Naples_ in the _Province_ of _Campania_, now called _Terra di Lovorador_. But for the Author of it, the one names him not, and the other assures vs, he is not knowne: yet _Salmuth_ out of _Ciezus & Gomara_ confidently christens him with the name of _Flavius_, and so doth _Du Bartas_ in those excellent verses of his touching this subject.
"'W' are not to _Ceres_ so much bound for bread, Neither to _Bacchus_ for his clusters red, As Signior _Flavio_ to thy witty tryall, For first inventing of the Sea-mans dyall, Th' vse of the needle turning in the same, Divine device, O admirable frame!'
"It may well be then that _Flavius_ the _Melvitan_ was the first inventor of guiding the ship by the turning of the needle to the _North_: but some _German_ afterwards added to the _Compasse_ the 32 points of the winde in his owne language, whence other Nations haue since borrowed it."
[15] PAGE 4, LINE 14. Page 4, line 14. _Paulum Venetum_.--The reference is to Marco Polo. He returned in 1295 from his famous voyage to Cathay. But the oft-repeated tale that he first introduced the knowledge of the compass into Europe on his return is disposed of by several well-established facts. Klaproth (_op. citat._, p. 57) adduces a mention of its use in 1240 in the Eastern Mediterranean, recorded in a work written in 1242 by Bailak of Kibdjak. And the passages in the Iceland Chronicle, and in Alexander of Neckham are still earlier.
[16] PAGE 4, LINE 17. Page 4, line 17. _Goropius_. See _Hispanica Ioannis Goropii Becani_ (Plantin edition, Antv., 1580), p. 29. This is a discussion of the etymologies of the names of the points of the compass: but is quite unauthoritative.
[17] PAGE 4, LINE 23. Page 4, line 26. _Paruaim_.--Respecting this reference, Sir Philip Magnus has kindly furnisht the following note. A clue to the meaning of _Parvaim_, which should be written in English letters with a _v_, not a _u_, will be found in _2 Chronicles_, iii. 6. In the verse quoted the author speaks of gold as the gold of Parvaim, [Hebrew: WHAZAHAB ZHAB PARWAYIM], and [Hebrew: PRWYM] Parvaim is taken as a gold-producing region. It is regarded by some as the same as Ophir. The word is supposed to be cognate with a Sanskrit word _pûrva_ signifying "prior, anterior, oriental." There is nothing in the root indicating gold. A form similar to Parvaim, and also a proper name, is Sepharvaim, found in _2 Kings_, xix. 13, and in _Isaiah_, xxxvii. 13, and supposed to be the name of a city in Assyria.
[18] PAGE 4, LINE 35. Page 4, line 41. Cabot's observation of the variation of the compass is narrated in the _Geografia_ of Livio Sanuto (Vinegia, 1588, lib. i., fol. 2). See also Fournier's _Hydrographie_, lib. xi., cap. 10.
[19] PAGE 4, LINE 36. Page 4, line 42. _Gonzalus Oviedus_.--The reference is to Gonzalo Fernandez de Oviedo y Valdès. _Summario de la Historia general y natural de las Indias occidentales_, 1525, p. 48, where the author speaks of the crossing of "la linea del Diametro, donde las Agujas hacen la {11} diferencia del Nordestear, ò Noroestear, que es el parage de las Islas de los Açores."
[20] PAGE 5, LINE 8. Page 5, line 11. _Petri cujusdam Peregrini_.--This opusculum is the famous letter of Peter Peregrinus written in 1269, of which some twenty manuscript copies exist in various libraries in Oxford, Rome, Paris, etc., and of which the oldest printed edition is that of 1558 (Augsburg). See also Libri, _Histoire des Sciences Mathématiques_ (1838); Bertelli in Boncompagni's _Bull. d. Bibliogr._ T. I. and T. IV. (1868 and 1871), and Hellmann's _Rara Magnetica_ (1898). A summary of the contents of Peregrinus's book will be found in Park Benjamin's _Intellectual Rise in Electricity_ (1895), pp. 164-185.
[21] PAGE 5, LINE 12. Page 5, line 15. _Johannes Taisner Hannonius._--Taisnier, or Taysnier, of Hainault, was a plagiarist who took most of the treatise of Peregrinus and publisht it in his _Opusculum... de Natura Magnetis_ (Coloniæ, 1562), of which an English translation by Richard Eden was printed by R. Jugge in 1579.
[22] PAGE 5, LINE 18. Page 5, line 23. _Collegium Conimbricense_.--This is a reference to the commentaries on Aristotle by the Jesuits of Coimbra. The work is _Colegio de Coimbra da Companhia de Jesu, Cursus Conimbricensis in Octo libros Physicorum_ (Coloniæ, sumptibus Lazari Ratzneri, 1599). Other editions: Lugd. 1594; and Colon., 1596. The later edition of 1609, in the British Museum, has the title _Commentariorum Collegii Conimbricensis in octo libros physicorum_.
[23] PAGE 5, LINE 25. Page 5, line 31. _Martinus Cortesius_.--His _Arte de Navegar_ (Sevilla, 1556) went through various editions in Spanish, Italian, and English. Eden's translation was publisht 1561, and again in 1609.
[24] PAGE 5, LINE 26. Page 5, line 33. _Bessardus_.--Toussaincte de Bessard wrote a treatise, _Dialogue de la Longitude_ (Rouen, 1574), which gives some useful notes of nautical practice, and of the French construction of the compass. Speaking of the needle he says: "Elle ne tire pas au pole du monde: ains regarde, au Pole du Zodiaque, comme il sera discoursu, cy apres" (p. 34). On p. 50 he speaks of "l'aiguille Aymantine." On p. 108 he refers to Mercator's _Carte Générale_, and denies the existence of the alleged loadstone rock. On p. 15 he gives the most naïve etymologies for the terms used: thus he assigns as the derivation of _Sud_ the Latin _sudor_, because the south is hot, and as that of _Ouest_ that it comes from _Ou_ and _Est_. "Come, qui diroit, Ou est-il? à scauoir le Soleil, qui estoit nagueres sur la terre."
[25] PAGE 5, LINE 28. Page 5, line 35. _Jacobus Severtius_.--Jacques Severt, whose work, _De Orbis Catoptrici sev mapparvm mvndi principiis descriptione ac usu libri tres_ (Paris, 1598), would have probably lapsed into obscurity, but being just newly publisht was mentioned by Gilbert for its follies.
[26] PAGE 5, LINE 30. Page 5, line 38. _Robertus Norman_.--Author of the rare volume _The Newe Attractiue_, publisht in London, 1581, and several times reprinted. This work contains an account of Norman's discovery of the Dip of the magnetic needle, and of his investigation of it by means of the Dipping-needle, which he invented. He was a compassmaker of the port of London, and lived at Limehouse.
[27] PAGE 5, LINE 32. Page 5, line 40. _Franciscus Maurolycus_.--The work to which the myth of the magnetic mountains is thus credited is, _D. Francisci Abbatis Messanensis Opuscula Mathematica_, etc. (Venet, MDLXXV, p. 122a). "Sed cur sagitta, vel obelus à vero Septentrione, quandoque ad dextram, {12} quandoque ad sinistram declinat? An quia sagitta, sicut magnes (cuius est simia) non verum Septentrionem, sed insulam quandam (quam Olaus Magnus Gothus in sua geographia vocat insulam magnetum) semper ex natura inspicere cogitur?"
[28] PAGE 5, LINE 35. Page 5, line 43. _Olaus Magnus_.--The famous Archbishop of Upsala, who wrote the history of the northern nations (_Historia de Gentibus Septentrionalibus_), of which the best edition, illustrated with many woodcuts, appeared in Rome in 1555. An English edition entitled _A Compendious History of the Goths, Swedes, and Vandals, and Other Northern Nations_ was printed in London in 1658; but it is much abbreviated and has none of the quaint woodcuts. The reference on p. 5 appears to be to the following passage on p. 409 (ed. 1555). "Demum in suppolaribus insulis magnetum montes reperiuntur, quorum fragmentis ligna fagina certo tempore applicata, in saxeam duritiem, et vim attractivam convertuntur," or the following on p. 89: "Magnetes enim in extremo Septentrionis veluti montes, unde nautica directio constat, reperiuntur: quorum etiam magnetum tam vehemens est operatio, ut certis lignis fagineis conjuncti, ea vertunt in sui duritiem, & naturam attractivam." On p. 343 is a woodcut depicting the penalties inflicted by the naval laws upon any one who should maliciously tamper with the compass or the loadstone, "qui malitiosè nauticum gnomonem, aut compassum, & præcipuè portionem magnetis, unde omnium directio dependet, falsaverit." He was to be pinned to the mast by a dagger thrust through his hand. It will be noted that the ships carried both a compass, and a piece of loadstone wherewith to stroke the needle.
There is in the Basel edition of this work, 1567, a note _ad lectorem_, on the margin of Carta 16a, as follows:
"Insula 30 milliarium in longitud. & latitud. Polo arctico subjecta.
"Vltra quam directorium nauticum bossolo dic[~u] uires amittit: propterea quòd ilia insula plena est magnetum."
This myth of the magnetic mountains, probably originating with Nicander, appears, possibly from an independent source, in the East, in China, and in the tales of the Arabian Nights.
Ptolemy gives the following account in his _Geographia_ (lib. vii., cap. 2):
[Greek: Pherontai de kai allai sunecheis deka nêsoi kaloumenai Maniolai en ais phasi ta sidêrous echonta hêlous ploia katechesthai, mêpote tês Hêrikleias lithou peri autas genomenês, kai dia touto epiourois naupêgeisthai.] Some editions omit the name of the Manioles from the passage.
No two authorities agree as to the place of these alleged magnetic mountains. Some place them in the Red Sea. Fracastorio, _De Sympathia et Antipathia_, cap. 7 (_Opera omnia_, Giunta edition, 1574, p. 63), gives the following reason for the variation of the compass:
"Nos igitur diligentius rem considerãtes dicimus causam, [~q] perpendiculum illud ad polum vertatur, esse montes ferri, & magnetis, qui sub polo sunt, vt negociatores affirmant, quorum species per incredibilem distantiam vsque ad maria nostra propagata ad perpendiculum vsq;, vbi est magnes, consuetam attractionem facit: propter distantiam autem quum debilis sit, non moueret quidem magnetem, nisi esset in perpendiculo: quare & si non trahit vsq; ac. principium, vnde effluxit, at mouet tam[~e], & propinquiorem facit, quo potest. Quod si naues sorte vllæ propinquiores sint illis montibus, ferrum omne ear[~u] cuellitur, propter quod nauigijs incolæ vtuntur clauis ligneis astrictis."
In the last chapter of his _De Sympathia_, Fracastorio returns to the subject {13} in consequence of some doubts expressed by Giambattista Rhamnusio, seeing that the loadstones in the Island of Elba do not sensibly deflect the magnet. Fracastorio replies thus (p. 76, _op. citat._):
"Primum igitur vtrum sub Polo sint. Magnetis mõtes, nec ne, sub ambiguo relinquamus, scimus enim esse, qui scribãt planas magis esse eas regiones, de quo Paulus Iouius E[~p]us Nucerinus Lucul[~e]tus historiar[~u] nostri t[~e]poris scriptor, circa eã Sarmatiæ partem, quæ Moscouia n[~u]c dicitur, diligent[~e] inquisitionem ab incolis fecit, qui ne eos etiã inueniri montes retulere, qui Rhyphei ab antiquis dicti sunt: meminimus tam[~e] nos quasdam chartas vidisse earum, quas mundi mappas appellãt, in quibus sub polo montes notati erant (qui Magnetis montes inscripti fuerant). Siue igitur sint, siue non sint ij montes, nihil ad nos in præsentiarum attinet, quando per montes polo subiectos cathenam illam montium intelligimus, qui ad septentrionem spectant tanti, & tam vasti, ac Ferri & Magnetis feraces: qui, & si magis distant à nostro mari, [~q] Iluæ insulæ montes, potentiores tamen sunt ad mouendum perpendiculum propter abundantiam & copiã Ferri, & Magnetis. Fortasse autem, & qui in Ilua est Magnes, non multæ actionis est in ea minera: multi enim d[~u] in minera sunt, minus valent, [~q] extracti, [~q] spirituales species sua habeant impedimenta: signum autem parum valere in sua minera Iluæ insulæ Magnetem, [~q] tam propinquus quum sit nauigijs illac prætereuntibus, perpendiculum tamen non ad se cõuertit."
Aldrovandi in the _Musæum Metallicum_ (Bonon., 1648, p. 554) gives another version of the fable:
"Nonnulli, animadversa hac Magnetis natura, scripserunt naves, quibus in Calecutanam regionem navigatur, clavis ferreis non figi, ob magneticorum frequentiam scopulorum, quoniam facilè dissolverentur. Sed Garzias in Historia Aromatum id fabulosum esse tradidit: quandoquidem plures naues Calecutanæ regionis, & illius tractus, ferreis clauis iunctas obseruauit: immò addidit naues in insulis Maldiuis ligneis quidem clauis copulari, non quia à Magnete sibi metuant, sed quoniam ferri inopia laborant."
According to Aldrovandi (p. 563, _op. citat._) the magnetic mountains are stated by Sir John Mandeville to be in the region of Pontus.
Lipenius in his _Navigatio Salomonis Ophritica illustrata_ (Witteb., 1660), which is a mine of curious learning, in discussing the magnetic mountains quotes the reply of Socrates to the inquirer who asked him as to what went on in the infernal regions, saying that he had never been there nor had he ever met any one who had returned thence.
The loadstone rock figures in several early charts. In Nordenskiöld's _Facsimile Atlas_ (Stockholm, 1889) is given a copy of the Map of Johan Ruysch from an edition of Ptolemy, publisht in Rome in 1508, which shows four islands within the ice-bound Arctic regions. South of these islands and at the east of the coast of Greenland is the inscription: _Hic compassus navium non tenet, nec naves quæ ferrum tenent revertere valent._ To which (on p. 63) Nordenskiöld adds the comment: _Sagan on magnetberg, som skulle draga till sig fartyg förande jern, är gamal._ And he recalls the reference of Ptolemy to the magnetic rocks in the Manioles. A second inscription is added to Ruysch's map in the ornamental margin that borders the Arctic islands. _Legere est in libro de inventione fortunati sub polo arctico rupem esse excelsam ex lapide magnete 33 miliarium germanorum ambitu._ This refers to a matter recorded in Hakluyt's _Principall Navigations_ (Lond., 1589, p. 249), namely: "A Testimonie of the learned Mathematician, maister John Dee, {14} touching the foresaid voyage of Nicholas de Linna. Anno 1360 a frier of Oxford, being a good Astronomer, went in companie with others to the most Northren islands of the world, and there leaving his company together, he travelled alone, and purposely described all the Northern islands, with the indrawing seas: and the record thereof at his return he delivered to the king of England. The name of which booke is _Inventio Fortunata_ (_aliter fortunæ_) _qui liber incipit a gradu 54 usq. ad polum_."
The situation of the alleged loadstone rock is thus described by T. Blundevile in his _Exercises_ in the chapter entitled _A plaine and full description of Peter Plancius his vniuersall Map, seruing both for sea and land, and by him lately put foorth in the yeare of our Lord, 1592_.... Written in our mother tongue by M. Blundeuill, Anno Domini 1594. The passage is quoted from p. 253 of the third edition (1606):
"Now betwixt the 72. and 86. degrees of North latitude he setteth downe two long Ilands extending from the West towardes the East somewhat beyond the first Meridian, and from the saide Meridian more Eastward he setteth downe other two long Ilandes ... and hee saith further that right under the North pole there is a certaine blacke and most high rocke which hath in circuite thirtie and three leagues, which is nintie and nine miles, and that the long Iland next to the Pole on the West is the best and most healthfull of all the North parts. Next to the foresaide Ilandes more Southward hee setteth downe the Ilandes of Crocklande and Groynelande, making them to haue a farre longer and more slender shape then all other mappes doe.... Moreouer at the East end of the last Ilande somewhat to the Southwarde, he placeth the Pole of the Lodestone which is called in Latine Magnes, euen as Mercator doth in his Mappe who supposing the first Meridian to passe through Saint Marie or Saint Michael, which are two of the outermost Ilandes of the Azores Eastwarde, placeth the Pole of the stone in the seuentie fiue degree of Latitude, but supposing the first Meridian to passe through the Ile Coruo, which is the furthest Ile of the Azores Westwarde, he placeth the Pole of the Lodestone in the seuentie seuen degree of Latitude."
Further, in the chapter on _The Arte of Nauigation_ in the same work (p. 332, _ed. citat._), Blundevile says:
"But whereas Mercator affirmeth that there should bee a mine or great rocke of Adamant, wherunto all other lesser rockes or Needles touched with the Lodestone doe incline as to their chiefe fountaine, that opinion seemeth to mee verie straunge, for truely I rather beleeue with Robert Norman that the properties of the Stone, as well in drawing steele, as in shewing the North Pole, are secret vertues given of GOD to that stone for mans necessarie vse and behoofe, of which secrete vertues no man is able to shewe the true cause."
The following is one of the inscriptions in the compartments of the great Chart of Mercator entitled _Ad Usum Navigantium_, published in 1569:
"Testatur Franciscus Diepanus peritissimus nauarchus volubiles libellas, magnetis virtute infectas recta mundi polum respicere in insulis C. Viridis, Solis, Bonauista, et Maio, cui proxime astipulantur qui in Tercera, aut S. Maria (insulæ sunt inter Açores) id fieri dicunt, pauci in earundem occidentalissima Corvi nomine id contingere opinantur. Quia vero locorum longitudinis a communi magnetis et mundi meridiano iustis de causis initium sumere oportet, plurium testimonium sequutus primum meridianum per dictas C. Viridis insulas protraxi, et quum alibi plus minusque a polo deuiante {15} magnete polum aliquum peculiarem esse oporteat quo magnetes ex omni mundi parte despiciant, euum hoc quo assignaui loco existere adhibita declinatione magnetis Ratisbonæ obseruata didici. Supputaui autem eius poli situm etiam respectu insulæ Corui, ut iuxta extremo primi meridiani positus extremi etiam termini, intra quos polum hunc inueniri necesse est, conspicui fierent, donec certius aliquod nauclerorum obseruatio attulerit."
Not all the map-makers were as frank as Paulus Merula, the author of a _Cosmographia Generalis_, printed by Plantin in 1605, at Leyden. For in the description of his _tabula universalis_ (_op. citat._ lib. iii., cap. 9) he says that he does not believe in the magnetic islands; but that he has put them into his chart lest unskilful folk should think that he had been so careless as to leave them out!
In the well-known myth of Ogier the Dane, immortalized by William Morris in the _Earthly Paradise_ (London, 1869, vol. i., p. 625), the loadstone rock is an island in the far North. But this story is not one of the Scandinavian sagas, and belongs to the Carlovingian cycle of heroic poems, of which the chief is the _Chanson de Roland_; and Ogier le Danois is really not a Dane but an _Ardennois_.
In the Middle-High German epic of Kudrun, the adventures of the fleet of Queen Hilda when attracted by the loadstone mountain at Givers, in the North Sea, are narrated at some length. (See _Kudrun, herausgegeben und erklärt von Ernst Martin_. Halle, 1872.) One stanza will serve as a sample:
1126. Ze Givers vor dem berge | lac daz Hilden her. swie guot ir anker wæren, | an daz vinster mer. magnêten die steine | heten si gezogen. ir guote segelboume | stuonden alle gebogen.
which may be rendered:
1126. At Givers before the mountain | lay Hilda's ships by. Though good their anchors were, | upon the murky sea. Magnets the stones were | had drawn them thither. Their good sailing masts | stood all bent together.
Recent magnetic research has shown that while there are no magnetic mountains that would account for the declination of the compass in general, yet there are minor local variations that can only be accounted for by the presence of magnetic reefs or rocks. The reader is referred to the account of the magnetic survey of Great Britain in the _Philosophical Transactions_ (1890) by Professors Rücker and Thorpe. The well-known rocky peak the Riffelhorn above Zermatt, in Switzerland, produces distinct perturbations in the direction of the compass within half a mile of its base. Such local perturbations are regularly used in Sweden for tracing out the position of underground lodes of iron ore. See Thalén, _Sur la Recherche des Mines de Fer à l'aide de Mesures magnétiques_ (Soc. Royale des Sciences d'Upsal, 1877); or B. R. Brough, _The Use of the Magnetic Needle in exploring for Iron Ore_ (_Scientific American_, Suppl. No. 608, p. 9708, Aug. 27, 1887).
Quite recently Dr. Henry Wilde, F.R.S., has endeavoured to elucidate the deviations of the compass as the result of the configurations of land and sea on the globe, by means of a model globe in which the ocean areas are covered with thin sheet iron. This apparatus Dr. Wilde calls a _Magnetarium_. See _Proc. Roy. Soc._, June, 1890, Jan., 1891, and June, 1891. {16} An actual magnetic rock exists in Scandinavia, the following account of it being given in the _Electrical Review_ of New York, May 3, 1899:
"The island of Bornholm in the Baltic, which consists of a mass of magnetic iron ore, is much feared by mariners. On being sighted they discontinue steering by compass, and go instead by lighthouses. Between Bornholm and the mainland there is also a dangerous bank of rock under water. It is said that the magnetic influence of this ore bank is so powerful that a balanced magnetic needle suspended freely in a boat over the bank will take a vertical position."
[29] PAGE 5, LINE 35. Page 5, line 43. _Josephus Costa._--This is unquestionably a misprint for _Acosta_ (Joseph de), the Jesuit, whose work _Historia natural y moral de las Indias_ was publisht at Seville in 1590. An Italian edition appeared at Venice in 1596. The English edition, translated by E. Grimestone, _The Naturall and Morall Historie of the East and West Indies_, was publisht in London in 1604 and 1878. There are in Gilbert's book references to two writers of the name of Costa or Costæus, Joannes Costa of Lodi, who edited Galen and Avicenna (see pp. 3 and 62), and Filippo Costa of Mantua, who wrote on antidotes and medicaments (see p. 141). The passage to which Gilbert refers is in Acosta's _Historia_ (ed. 1590, p. 64).
"Deziame a mi vn piloto muy diestro Portugues [~q] eran quatro puntos en todo el orbe, donde se afixaua el aguja con el Norte, y contaualas por sus nombres, de que no me acuerdo bien. Vno destos es el paraje de la Isla del Cueruo, en las Terceras, o Islas de Açores, como es cosa y a muy sabida. Passando di alli a mas altura, Noruestea, que es dezir, [~q] declina al Poniente ... que me digã la causa desta efecto?... Porque vn poco de hierro de fregarse cõ la piedra Iman ...
"Mejor es, como dize Gregorio Theologo, que a la Fe se sujete la razon, pues aun en su casa no sabe bien entenderse...."
[30] PAGE 5, LINE 36. Page 5, line 45. _Livius Sanutus._--Livio Sanuto publisht at Venice in 1588 a folio work, _Geografia distinta in xii Libri; ne' quali, oltre l'esplicatione di nostri luoghi di Tolomeo, della Bussola e dell' Aguglia, si dichiarono le provincie ... dell' Africa_. In this work all Liber i. (pages 1-13) deals with observations of the compass, mentioning Sebastian Cabot, and other navigators. He gives a map of Africa, showing the central lakes out of which flow the _Zaires fluvius_ and the _Zanberes fluvius_.
[31] PAGE 6, LINE 2. Page 6, line 5. _Fortunius Affaitatus._--The work of Affaytatus, _Physicæ ac astronomiæ considerationes_, was publisht in Venice in 1549.
[32] PAGE 6, LINE 3. Page 6, line 6. _Baptista Porta._--The reference is to his celebrated _Magia naturalis_, the first edition of which came out in 1558 at Naples. An English edition, _Natural Magick by John Baptista Porta, a Neapolitaine_, was printed in London, 1658. Book seven of this volume treats "Of the wonders of the Load-stone." In the proem to this book Porta says: "I knew at Venice R. M. Paulus, the Venetian, that was busied in the same study: he was Provincial of the Order of servants, but now a most worthy Advocate, from whom I not only confess, that I gained something, but I glory in it, because of all the men I ever saw, I never saw any man more learned, or more ingenious, having obtained the whole body of learning; and is not only the Splendor and Ornament of Venice or Italy, but of the whole world." The reference is to Fra Paolo Sarpi, better known as the historian of the Council of Trent. Sarpi was himself known to Gilbert. {17}
His relations with Gilbert are set forth in the memoir prefixt to the edition of his works, _Opere di Fra Paolo Sarpi, Servita_ ... in Helmstat, MDCCLXI, p. 83. "Fino a questi giorni continuava il Sarpi a raccorre osservazioni sulla declinazione dell' Ago Calamitato; e poi ch' egli, atteso il variare di tal declinazione, assurdità alcuna non trovava riguardo al pensamento dell' Inglese Guglielmo Gilberto, cioè, che l'interno del nostro Globo fosse gran Calamita...." Here follows a quotation from a letter of Sarpi to Lescasserio:
"... Unde cuspidem trahi a tanta mole terrena, quæ supereminet non absurde putavit Gullielmus Gilbertus, et in eo meridiano respicere recta polum, cave putes observatorem errasse. Est Vir accuratissimus, et interfuit omnibus observationibus, quas plures olim fecimus, et aliquas in sui gratiam, et cum arcubus vertici cupreo innitentibus, et cum innatantibus aquæ, et cum brevibus, et cum longis, quibus modis omnibus et Hierapoli usus suit."
Sarpi had correspondence with Gilbert, Bacon, Grotius, and Casaubon. He also wrote on magnetism and other topics _in materia di Fisica_, but these writings have perisht. He appears to have been the first to recognize that fire destroyed the magnetic properties. (See _Fra Paolo Sarpi, the greatest of the Venetians_ by the Rev. Alexander Robertson, London, 1894; see also the notice of Sarpi in Park Benjamin's _Intellectual Rise in Electricity_.)
[33] PAGE 6, LINE 7. Page 6, line 11.: _R. M. Paulus Venetus_. See preceding note.
[34] PAGE 6, LINE 21. Page 6, line 28.: _Franciscus Rueus_.--Francois de la Rue, author of _De Gemmis Aliquot_ ... (Paris, 1547). Amongst other fables narrated by Rueus is that if a magnet is hung on a balance, when a piece of iron is attracted and adheres to the magnet, it adds nothing to the weight!
[35] PAGE 6, LINE 25. Page 6, line 33.: _Serapio_.--This account of the magnetic mountains will be found in an early pharmacology printed in 1531 (Argentorati, G. Ulricher Andlenus), with the title "In hoc volumine continetur insignium medicorum Joan. Serapionis Arabis de Simplicibus Medicinis opus præclarum et ingens, Averrois Arabis de eisdem liber eximius, Rasis filius Zachariæ de eisdem opusculum perutile." It was edited by Otho Brunsels. Achilles P. Gasser, in his Appendix to the Augsburg edition of Peregrinus, gives a reference to Serapio Mauritanus, parte 2, cap. 394, libri _de medicinis compositis._
[36] PAGE 6, LINE 30. Page 6, line 39.: _Olaus Magnus_. See note to p. 5.
[37] PAGE 6, LINE 34. Page 6, line 44.: _Hali Abas_.--A reference is given in Gasser's (1558) edition of Peregrinus to Haliabbas Arabs, lib. 2, _practicæ_ cap. 45, _Regalis Dispositionis Medicinæ_. The passage to which Gilbert refers is found in the volume _Liber totius medicinæ necessaria c[=o]tinens ... quem Haly filius Abbas ... edidit ... et a Stephano ex arabica lingua reductus_. (Lugd., 1523, 4to.) Liber Primus. Practice, Cap xlv. _de speciebus lapidum_, § 466. "Lapis magnetes filis e [=v]tute sadenego: & aiunt q[=m] si teneat^r in manu mitigat [=q] sunt in pedib^s ipis dolores ac spasm[=u]."
Mr. A. G. Ellis identifies the noun _sadenegum_ as a Latin corruption of the Arabic name of hæmatite, _shâdanaj_.
[38] PAGE 6, LINE 36. Page 6, line 46.: _Pictorius_.--His poem was publisht at Basel, 1567. See also note on Marbodæus, p. 7, line 20, below.
[39] PAGE 6, LINE 36. Page 7, line 1.: _Albertus Magnus_.--Albertus, the celebrated Archbishop of Ratisbon, is responsible for propagating sundry of the myths of the magnet; and Gilbert never loses a chance of girding at him. {18} The following examples are taken from the treatise _De mineralibus et rebus metallicis_ (Liber II. _de lapidibus preciosis_), Venet., 1542.
p. 171. "Et quod mirabile videtur multis his lapis [adamas] quando Magneti supponitur ligat Magnetem et non permittit ipsum ferrum trahere."
p. 193. "Vnctus aut[~e] lapis alleo non trahit, si superponitur ei Adamas iterum non attrahit, ita quod paruus Adamas magn[~u] ligat Magnet[~e]. Inventus aut[~e] est nostris t[~e]poribus Magnes qui ab uno angulo traxit ferr[~u] et ab alio fugavit, et hunc Aristot. ponit aliud genus esse Magnetis. Narrauit mihi quidam ex nostris sociis experim[~e]tator quod uidit Federicum Imperatorem habere Magnetem qui non traxit ferrum, sed ferrum uiceuersa traxit lapidem."
The first edition of this work _de mineralibus_ appears to have been publisht in Venice as a folio in 1495.
[40] PAGE 7, LINE 9. Page 7, line 15. _Gaudentius Merula_.--This obscure passage is from Liber IIII., cap. xxi., _Lapides_, of the work _Memorabilium Gaudentii Merulæ..._ (Lugd., 1556), where we find:
"Qui magneti vrsæ sculpserit imaginem, quãdo Luna melius illuc aspiciat, & filo ferreo susp[~e]derit, compos fiet vrsæ cælestis virtutis: verùm cum Saturni radiis vegetetur, satius fuerit eam imaginem non habere: scribunt enim Platonici malos dæmones septentrionales esse" (p. 287).
"Trahit autem magnes ferrum ad se, quod ferro sit ordine superior apud vrsum" (p. 287).
The almost equally obscure passage in the _De triplici vita_ of Marsiglio Ficino (Basil., 1532) runs:
"Videmus in specula nautarum indice poli libratum acum affectum in extremitate Magnete moueri ad Vrsam, illuc uidelicet trahente Magnete: quoniam & in lapide hoc præualet uirtus Vrsæ, & hinc transfertur in ferrum, & ad Vrsam trahit utrunq;. Virtus autem eiusmodi tum ab initio infusa est, tum continue Vrsæ radijs uegetatur, Forsitan ita se habet Succinum ad polum alterum & ad paleas. Sed dic interea, Cur Magnes trahit ubiq; ferrum? non quia simile, alioquin & Magnetem Magnes traheret multo magis, ferrum[=q]; ferr[=u]: non quia superior in ordine corporum, imò superius est lapillo metallum ... Ego autem quum hæc explorata hactenus habuissem admodum gratulabar, cogitabam[=q]; iuuenis adhuc Magneti pro uiribus inscluperet (_sic_) coelestis Vrsæ figuram, quando Luna melius illuc aspiciat, & ferro t[=u]c filo collo suspendere. Sperabam equidem ita demum uirtutis me sideris illius compotem fore," &c. (p. 172).
[41] PAGE 7, LINE 14. Page 7, line 20. _Ruellius_.--Joannes Ruellius wrote a herbal _De Natura Stirpium_, Paris, 1536, which contains a very full account of amber, and a notice of the magnet (p. 125) and of the fable about garlic. But on p. 530 of the same work he ridicules Plutarch for recording this very matter.
[42] PAGE 7, LINE 20. Page 7, line 27. _Marbodæus Gallus_.--This rare little book is entitled _Marbodei Galli Poetæ vetustissimi de lapidibus pretiosis Enchiridion_. It was printed at Paris in 1531. The Freiburg edition, also of 1531, has the commentaries of Pictorius. The poem is in Latin hexameters. After a preface of twenty-one lines the virtues of stones are dealt with, the paragraph beginning with a statement that Evax, king of the Arabs, is said to have written to Nero an account of the species, names and colours of stones, their place of origin and their potencies; and that this work formed the basis of the poem. The alleged magical powers of the magnet are recited in Caput I., _Adamas_. Caput XLIII., _Magnes_, gives further myths. {19} The commentary of Pictorius gives references to earlier writers, Pliny, Dioscorides, Bartholomæus Anglicus, Solinus, Serapio, and to the book _de lapidibus_ erroneously ascribed to Aristotle.
The following is a specimen of the poem of Marbodeus:
_Magnetes lapis est inuentus apud Trogloditas,_ _Qu[=e] lapid[=a] genetrix nihilominus India mittit._ _Hic ferruginei cognoscitur esse coloris,_ _Et ui naturæ uicinum tollere ferrum._ _Ededon magus hoc primum ferè dic[=i]tur usus,_ _Conscius in magica nihil esse potentius arte._ _Post illum fertur famosa uenefica Circe_ _Hoc in præstigijs magicis specialiter usa._
This poem was reprinted (1854) in Migne's _Patrologia_. In 1799 Johann Beckmann issued an annotated variorum edition of Marbodeus (_Marbodi Liber Lapidvm sev de Gemmis_..., Göttingæ, 1799), in which there is a bibliography of the poem, the first edition of which appears to have been publisht in 1511, at Vienna, thirteen other editions being described. Beckmann adds many illustrative notes, and a notice of the Arabian Evax, who is supposed to have written the treatise _de lapidibus_. Not the least curious part is a French translation alleged to have been written in 1096, of which Chap. XIX. on the Magnet begins thus:
Magnete trovent Trogodite, En Inde e precieus est ditte. Fer resemble e si le trait, Altresi cum laimant fait. Dendor lama mult durement. Qi lusoit a enchantement. Circe lus a dot mult chere, Cele merveillose forciere, &c.
[43] PAGE 7, LINE 21. Page 7, line 28. _echeneidis._--The _echeneis_, or sucking-fish, reputed to have magical or magnetic powers, is mentioned by many writers. As an example, see Fracastorio, _De Sympathia et Antipathia_, lib. i., cap. 8, _De Echineide, quomodo firmare nauigia possit_ (Giunta edition, Venet., 1574, p. 63). For other references to the _Echeneis_ see Gaudentius Merula (_op. citat._) p. 209. Also Dr. Walter Charleton, _Physiologia Epicuro Gassendo-Charltoniana_ (Lond., 1654), p. 375. Compare p. 63, line 3.
[44] PAGE 7, LINE 33. Page 7, line 43. _Thomas Hariotus_, etc.--The four Englishmen named were learned men who had contributed to navigation by magnetic observations. Harriot's account of his voyage to Virginia is printed in Hakluyt's _Voyages_. Robert Hues (or Hood) wrote a treatise _on Globes_, the Latin edition of which appeared in 1593 (dedicated to Sir Walter Raleigh), and the English edition in 1638. It was republisht by the Hakluyt Society, 1889. Edward Wright, the mathematician and writer on navigation, also wrote the preface to Gilbert's own book. Abraham Kendall, or Abram Kendal was "Portulano," or sailing-master of Sir Robert Dudley's ship the _Bear_, and is mentioned in Dudley's _Arcano del Mare_. On the return of Dudley's expedition in 1595, he joined Drake's last expedition, which sailed that year, and died on the same day as Drake himself, 28 January, 1596. (See _Hakluyt_, ed. 1809, iv., p. 73.)
[45] PAGE 7, LINE 36. Page 8, line 1. _Guilielmus Borough._--Borough's book has the title: _A Discours of the Variation of the Cumpas, or magneticall {20} Needle. Wherein is Mathematically shewed, the manner of the obseruation, effectes, and application thereof, made by W. B._ And is to be annexed to _The Newe Attractive_ of R. N., 1581 (London).
[46] PAGE 7, LINE 37. Page 8, line 2. _Guilielmus Barlo_.--Archdeacon William Barlowe (author, in 1616, of the _Magneticall Aduertisements_) wrote in 1597 a little work called _The Navigators Supply_. It gives a description of the ordinary compass, and also one of a special form of meridian compass provided with sights for taking the bearings by the sun.
[47] PAGE 7, LINE 37. Page 8, line 3. _Robertus Normannus_. See Note to p. 5.
[48] PAGE 8, LINE 14. Page 8, line 21. _illo fabuloso Plinij bubulco_.--The following is Pliny's account from Philemon Holland's English version of 1601 (p. 586): "As for the name Magnes that it hath, it tooke it (as _Nicander_ saith) of the first inventor and deviser thereof, who found it (by his saying) upon the mountaine Ida (for now it is to be had in all other countries, like as in Spaine also;) and (by report) a Neat-heard he was: who, as he kept his beasts upon the aforesaid mountaine, might perceive as he went up and downe, both the hob-nailes which were on his shoes, and also the yron picke or graine of his staffe, to sticke unto the said stone."
[49] PAGE 9, LINE 22. Page 9, line 30. _Differentiæ priscis ex colore_.--Pliny's account of the loadstones of different colours which came from different regions is mainly taken from Sotacus. The white magnet, which was friable, like pumice, and which did not draw iron, was probably simply magnesia. The blue loadstones were the best. See p. 587 of Holland's translation of Pliny, London, 1601. St. Isidore (_Originum seu Etymologiarum_, lib. xvi., cap. 4) says: "Omnis autem magnes tanta melior est, quanto [magis] cæruleus est."
[50] PAGE 10, LINE 29. Page 10, line 42. _Suarcebergo ... Snebergum & Annæbergum_.--In the Stettin editions of 1628 and 1633 these are spelled _Swarcebergs ... Schnebergum & Annebergum_. The Cordus given as authority for these localities is Valerius Cordus, the commentator on Dioscorides.
[51] PAGE 11, LINE 3. Page 11, line 12. _Adriani Gilberti viri nobilis_.--"Adrian Gylbert of Sandridge in the Countie of Devon, Gentleman" is the description of the person to whom Queen Elizabeth granted a patent for the discovery of a North-West passage to China. See Hakluyt's _Voyages_, vol. iii., p. 96.
[52] PAGE 11, LINE 17. Page 11, line 28. _Dicitur a Græcis_ [Greek: êraklios].--The discussion of the names of the magnet in different languages by Gilbert in this place is far from complete. He gives little more than is to be found in Pliny. For more complete discussions the reader is referred to Buttmann, _Bemerkungen über die Benennungen einiger Mineralien bei den Alten, vorzüglich des Magnetes und des Basaltes_ (Musæum der Alterthumswissenschaft, Bd. II., pp. 5-52, and 102-104, 1808); G. Fournier, _Hydrographie_ (livre xi., chap. I, 1643); Ulisse Aldrovandi, _Musæum Metallicum_ (Bononiæ, 1648, lib. iv., cap. 2, p. 554); Klaproth, _Lettre à M. le Baron A. de Humboldt, sur l'invention de la Boussole_, Paris, 1834; T. S. Davies, _The History of Magnetical Discovery_ (Thomson's _British Annual_, 1837, pp. 250-257); Th. Henri Martin, _De l'Aimant, de ses noms divers et de ses variétés suivant les Anciens_ (Mémoires présentés par divers savants a l'Academie des Inscriptions et Belles-lettres, I^{re} série, t. vi., I^{re} partie, 1861); G. A. Palm, _Der Magnet in Alterthum_ (Programm des k. württembergischen Seminars Maulbronn, Stuttgart, {21} 1867). Of these works, those of Klaproth and of Martin are by far the most important. Klaproth states that in modern Greek, in addition to the name [Greek: magnêtis], the magnet also has the names [Greek: adamas] and [Greek: kalamita]. The former of these, in various forms, _adamas_, _adamant_, _aimant_, _yman_, and _piedramon_, has gone into many languages. Originally the word [Greek: adamas] (the unconquered) was applied by the Greeks to the hardest of the metals with which they were acquainted, that is to say, to hard-tempered iron or steel, and it was subsequently because of its root-signification also given by them to the diamond for the same reason; it was even given to the henbane because of the deadly properties of that plant. In the writings of the middle ages, in St. Augustine, St. Isidore, Marbodeus, and even in Pliny, we find some confusion between the two uses of _adamas_ to denote the loadstone as well as the diamond. Certainly the word _adamas_, without ceasing to be applied to the diamond, also designated the loadstone. At the same time (says Martin) the word _magnes_ was preserved, as Pliny records, to designate a loadstone of lesser strength than the _adamas_. On the other hand, the word _diamas_, or _deamans_, had already in the thirteenth century been introduced into Latin to signify the diamond as distinguisht from the magnet. _Adamas_ was rendered _aymant_ in the romance version of the poem of Marbodeus on stones (see Beckmann's variorum edition of 1799, p. 102), and in this form it was for a time used to denote both the magnet and the diamond. Then it gradually became restricted in use to the stone that attracts iron.
Some confusion has also arisen with respect to the Hebrew name of the magnet. Sir W. Snow Harris makes the following statement (_Magnetism_, p. 5): "In the Talmud it [the loadstone] is termed _achzhàb'th_, the stone which attracts; and in their ancient prayers it has the European name _magn[=e]s_." On this point Dr. A. Löwy has furnisht the following notes. The loadstone is termed in one of the Talmudical sections and in the Midrash, _Eben Shoebeth_ (lapis attrahens). This would of course be written [Hebrew: 'BN SHW'BT]. Omitting the [Hebrew: W] which marks the participial construction, the words would stand thus: [Hebrew: 'BN SH'BT] A person referring to Buxtorf's _Lexicon_ Talmudicum would in the index look out for "Lapis magnesius," or for "magnes." He would then, in the first instance, be referred to the two words already quoted. Not knowing the value of the letters of the Hebrew alphabet, he reads [Hebrew: 'BN SH'BT] thus: [Hebrew: 'KZSH'BT] achzhab'th. It is true that Buxtorf has inserted in his _Lexicon_ the vocable [Hebrew: MAGNIYSEIS], "corruptum ex gr. [Greek: magnês, magnêtês, magnêtis], named after the Asiatic city Magnesia." He goes on to say, "Inde Achilles Statius istum lapidem vocavit [Greek: magnêsian lithon]. Hinc [Hebrew: 'BN HMGNJSS CHMSHWK HBRZL]. Lapis Magnesius trahit ferrum." Here he quotes from (Sepher) Ikkarem IV., cap. 35.
Kircher, in his _Magnes, sive de Arte magnetica_ (Coloniæ, 1643), gives several other references to Hebrew literature. Others have supposed that the word [Hebrew: CHLMYSH] _khallamish_, which signifies pebble, rock, or hard rock, to be used for the magnet.
As to the other Greek name, [Greek: sidêritis], or [Greek: lithos sidêritis] this was given not only to the loadstone but also to non-magnetic iron. In the _Etymologicum magnum_ (under the word [Greek: magnêtis]), and in Photius (_Quæst. amphiloch._, q. 131), it is stated that the name _sideritis_ was given to the loadstone either because of its action on iron, or of its resemblance in aspect to iron, _or rather_, they say, _because the loadstone was originally found in the mines of this metal_. Alexander of Aphrodisias expressly says (_Quætiones Physicæ_, II. 23) that {22} the loadstone appears to be nothing else than [Greek: gê sidêritis], the earth which yields iron, or the earth of iron.
[53] PAGE 11, LINE 19. Page 11, line 29. _ab Orpheo_.--The reference is to v. 301-328 of the [Greek: Lithika]. The passage, as given in Abel's edition (Berol., 1881), begins:
[Greek: Tolma d' athanatous kai henêei meilissethai] [Greek: magnêssêi, tên d' exoch' ephilato thousios Arês,] [Greek: houneken, hoppote ken pelasêi polioio sidêrou,] [Greek: êute parthenikê terenochroa chersin helousa] [Greek: êitheon sternôi prosptussetai himeroenti,] [Greek: hôs hêg' harpazousa poti spheteron demas haiei] [Greek: aps palin ouk ethelei methemen polemista sidêron.]
[54] PAGE 11, LINE 20. Page 11, line 31. _Gallis aimant_.--The French word _aimant_, or _aymant_, is generally supposed to be derived from _adamas_. Nevertheless Klaproth (_op. citat._, p. 19) suggests that the word _aimant_ is a mere literal translation into French of the Chinese word _thsu chy_, which is the common name of the magnet, and which means _loving stone_, or _stone that loves_. All through the east the names of the magnet have mostly the same signification, for example, in Sanskrit it is _thoumbaka_ (the kisser), in Hindustani _tchambak_.
[55] PAGE 11, LINE 20. Page 11, line 32. _Italis calamita_.--The name _calamita_, universal in Italian for the magnet, is also used in Roumanian, Croatian, Bosnian, and Wendish. Its supposed derivation from the Hebrew _khallamîsh_ is repudiated by Klaproth, who also points out that the use of [Greek: kalamita] in Greek is quite modern. He adds that the only reasonable explanation of the word _calamita_ is that given by Father Fournier (_op. citat._), who says:
"Ils (les marins français) la nomment aussi _calamite_, qui proprement en français signifie une _grenouille verte_, parce qu'avant qu'on ait trouvé l'invention de suspendre et de balancer sur un pivot l'aiguille aimantée, nos ancêtres l'enfermaient dans une fiole de verre demi-remplie d'eau, et la faisaient flotter, par le moyen de deux petits fétus, sur l'eau comme une grenouille." Klaproth adds that he entirely agrees with the learned Jesuit, but maintains that the word _calamite_, to designate the little green frog, called to-day _le graisset_, _la raine_, or _la rainette_, is essentially Greek. For we read in Pliny (_Hist. Nat._ lib. xxxii., ch. x.): "Ea rana quam Græci _calamiten_ vocant, quoniam inter arundines, fruticesque vivat, minima omnium est et viridissima."
[56] PAGE 11, LINE 20. Page 11, line 32. _Anglis_ loadstone & adamant stone.
The English term _loadstone_ is clearly connected with the Anglo-Saxon verb _loedan_, to lead, and with the Icelandic _leider-stein_. There is no doubt that the spelling _lodestone_ would be etymologically more correct, since it means _stone that leads_ not _stone that carries a load_. The correct form is preserved in the word _lode-star_.
The word _adamant_, from _adamas_, the mediæval word for both loadstone and diamond, also occurs in English for the loadstone, as witness Shakespeare:
"You draw me, you hard-hearted adamant But yet you draw not iron; for my heart Is true as steel." _Midsummer Night's Dream_, Act II, Scene 1.
[57] PAGE 11, LINE 21. Page 11, {23} line 33. _Germanis magness_, & _siegelstein_. The Stettin edition of 1628 reads _Germanis_ MAGNETSTEIN, _Belgis_ SEYLSTEEN; while that of 1633 reads _Germanis_ MAGNETSTEIN, _Belgis_ SYLSTEEN.
[58] PAGE 11, LINE 26. Page 11, line 39. In this line the Greek sentence is, in every known copy of the folio of 1600, corrected in ink upon the text, [Greek: thalês] being thus altered into [Greek: Thalês], and [Greek: apomnemonuousi] into [Greek: apomnemoneuousi]. Four lines lower, brackets have been inserted around the words (lapidum specularium modo). These ink corrections must have been made at the printers', possibly by Gilbert's own hand. They have been carried out as errata in the editions of 1628 and 1633. The "facsimile" Berlin reprint of 1892 has deleted them, however. Other ink corrections on pp. 14, 22, 38, 39, 47, 130, and 200 of the folio edition of 1600 are noted in due course.
[59] PAGE 11, LINE 29. Page 11, line 45. _lapis specularis_. This is the mediæval name for _mica_, but in Elizabethan times known as talc or muscovy stone. Cardan, _De Rerum Varietate_ (Basil., 1557, p. 418), lib. xiiii., cap. lxxii., mentions the use of _lapis specularis_ for windows.
[60] PAGE 11, LINE 31. Page 11, line 46.: _Germanis Katzensilbar_ & _Talke_.--In the editions of 1628 and 1633 this is corrected to _Germanis_ KATZENSILBER & TALCKE. Goethe, in _Wilhelm Meister's Travels_, calls mica "cat-gold."
[61] PAGE 12, LINE 30. Page 12, line 35. _integtum_ appears to be a misprint for _integrum_, which is the reading of editions 1628 and 1633.
[62] PAGE 13, LINE 4. Page 13, line 3. [Greek: mikrogê] _seu Terrella_. Although rounded loadstones had been used before Gilbert's time (see Peregrinus, p. 3 of Augsburg edition of 1558, or Baptista Porta, p. 194, of English edition of 1658), Gilbert's use of the spherical loadstone as a model of the globe of the earth is distinctive. The name _Terrella_ remained in the language. In _Pepys's Diary_ we read how on October 2, 1663, he "received a letter from Mr. Barlow with a terella." John Evelyn, in his _Diary_, July, 1655, mentions a "pretty terella with the circles and showing the magnetic deviations."
A Terrella, 4½ inches in diameter, was presented in 1662 by King Charles I. to the Royal Society, and is still in its possession. It was examined in 1687 (see _Phil. Transactions_ for that year) by the Society to see whether the positions of its poles had changed.
In Grew's _Catalogue and Description of the Rarities belonging to the Royal Society and preserved at Gresham College_ (London, 1681, p. 364) is mentioned a Terrella contrived by Sir Christopher Wren, with one half immersed in the centre of a plane horizontal table, so as to be like a Globe with the poles in the horizon, having thirty-two magnet needles mounted in the margin of the table to show "the different respect of the _Needle_ to the several _Points_ of the _Loadstone_."
In Sir John Pettus's _Fleta Minor_, London, 1683, in the _Dictionary of Metallick Words_ at the end, under the word _Loadstone_ occurs the following passage:
"Another piece of Curiosity I saw in the Hands of Sir _William Persal_ (since Deceased also) _viz._, a _Terrella_ or _Load-stone_, of little more than _6 Inches Diameter_, turned into a _Globular Form_, and all the _Imaginery Lines_ of our _Terrestrial Globe_, exactly drawn upon it: _viz._ the _Artick _ and _Antartick Circles_, the _two Tropicks_, the _two Colures_, the _Zodiack_ and _Meridian_; and these _Lines_, and the several _Countryes_, artificially _Painted_ on it, and all of them with their true _Distances_, from the two _Polar Points_, and to find the truth of those _Points_, he took two _little pieces_ of a _Needle_, each of about _half_ {24} _an Inch in length_, and those he laid on the _Meridian line_, and then with _Brass Compasses_, moved one of them towards the _Artick_, which as it was moved, still raised it self at one end higher and higher, keeping the other end fixt to the _Terrella_; and when it had compleated it Journy to the very _Artick Points_, it stood upright upon that _Point_; then he moved the other piece of _Needle_ to the _Antartick Point_, which had its _Elevations_ like the other, and when it came to the _Point_, it fixt it self upon that _Point_, and stood _upright_, and then taking the _Terrella_ in my Hand, I could perfectly see that the two _pieces_ of _Needles_ stood so exactly one against the other, as if it had been one intire _long Needle_ put through the _Terrella_, which made me give credit to those who held, That there is an _Astral Influence_ that _darts_ it self through the _Globe_ of _Earth_ from _North_ to _South_ (and is as the _Axel-Tree_ to the _Wheel_, and so called the _Axis_ of the _World_) about which the _Globe_ of the _Earth_ is turned, by an _Astral Power_, so as what I thought _imaginary_, by this _Demonstration_, I found _real_."
[63] PAGE 13, LINE 20. Page 13, line 22. The editions of 1628 and 1633 give a different woodcut from this: they show the terrella lined with meridians, equator, and parallels of latitude: and they give the compass needle, at the top, _pointing in the wrong direction_.
[64] PAGE 14, LINE 3. Page 14, line 3. The Berlin "facsimile" reprint omits the asterisk here.
[65] PAGE 14, LINE 5. Page 14, line 6. _erectus_ altered in ink in the folio to _erecta_. But _erectus_ is preserved in editions 1628 and 1633. In Cap. IIII., on p. 14, both these Stettin editions insert an additional cut representing the terrella A placed in a tub or vessel B floating on water.
[66] PAGE 14, LINE 34. Page 14, line 39. _variatione quad[=a]._ The whole of Book IIII. is devoted to a discussion of the variation of the compass.
[67] PAGE 16, LINE 28. Page 16, line 34. _aquæ._--This curious use of the dative occurs also on p. 222, line 8.
[68] PAGE 17, LINE 1. Page 17, line 1. _videbis._--The reading _vibebis_ of the 1633 edition is an error.
[69] PAGE 18, LINE 24. Page 18, line 27. _Theamedem._--For the myth about the alleged _Theamedes_, or repelling magnet, see Cardan, _De Subtilitate_ (folio ed., 1550, lib. vii., p. 186).
Pliny's account, in the English version of 1601 (p. 587), runs:
"To conclude, there is another mountaine in the same Æthyopia, and not farre from the said Zimiris, which breedeth the stone Theamedes that will abide no yron, but rejecteth and driveth the same from it."
Martin Cortes, in his _Arte de Nauegar_ (Seville, 1556), wrote:
"And true it is that Tanxeades writeth, that in Ethiope is found another kinde of this stone, that putteth yron from it" (Eden's translation, London, 1609).
[70] PAGE 21, LINE 24. Page 21, line 25. _Hic segetes, &c._--The English version of these lines from Vergil's _Georgics_, Book I., is by the late Mr. R. D. Blackmore.
[71] PAGE 22, LINE 18. Page 22, line 19. _quale_, altered in ink in the folio text to _qualis_. The editions of 1628 and 1633 both read _qualis_.
[72] PAGE 22, LINE 19. Page 22, line 20. _rubrica fabrili_: in English _ruddle_ or _reddle_. See "Sir" John Hill, _A General Natural History_, 1748, p. 47. In the _De Re Metallica_ of Entzelt (Encelius), Frankfurt, 1551, p. 134, is a paragraph headed _De Rubrica Fabrili_, as follows: "Rubrica fabrilis duplex {25} est. à Germanis añt utraque dicitur rottel, röttelstein, wie die zimmerleüt vnd steynmetzen brauchen. à Græcis [Greek: miltos tektonikê]. Est enim alia nativa, alia factitia. Natiua à Germanis propriè dicitur berckrottel. haec apud nos est fossilis.... Porro factitia est rubrica fabrilis, à Germanis braunrottel, quæ fit ex ochra usta, ut Theophrastus et Dioscorides testantur."
[73] PAGE 22, LINE 19. Page 22, line 20. _In Sussexia Angliæ._--In Camden's _Britannia_ (1580) we read concerning the iron industry in the villages in Sussex: "They are full of iron mines in sundry places, where, for the making and founding thereof, there be furnaces on every side; and a huge deal of wood is yearly burnt. The heavy forge-hammers, worked by water-power, stored in hammer-ponds, ceaselessly beating upon the iron, fill the neighbourhood round about, day and night, with continual noise."
[74] PAGE 23, LINE 1. Page 22, line 44. _in libro Aristotelis de admirandis narrationibus._--The reference is to the work usually known as the _De Mirabilibus Auscultationibus_, Cap. XLVIII.: "Fertur autem peculiarissima generatio esse ferri Chalybici Amisenique, ut quod ex sabulo quod a fluviis defertur, ut perhibent certe, conflatur. Alii simpliciter lotum in fornace excoqui, alii vero, quod ex lotura subsedit, frequentius lotum comburi tradunt adjecto simul et pyrimacho dicto lapide, qui in ista regio plurimus reperiri fertur." (Ed. Didot, vol. ii., p. 87.) According to Georgius Agricola, the stone pyrimachus is simply iron pyrites.
[75] PAGE 23, LINE 22. Page 23, line 23. _vt in Italia Comi_, &c.--This is mostly taken from Pliny. Compare the following passage from Philemon Holland's translation (1601), p. 514:
"But the most varietie of yron commeth by the meanes of the water, wherein the yron red-hot is eftsoones dipped and quenched for to be hardened. And verely, water only which in some place is better, in other worse, is that which hath ennobled many places for the excellent yron that commeth from them, as namely, Bilbilis in Spaine, and Tarassio, Comus also in Italie; for none of these places have any yron mines of their owne, and yet there is no talke but of the yron and steele that commeth from thence."
Bilbilis is Bambola, and Tariassona the Tarazona of modern Spain.
[76] PAGE 24, LINE 28. Page 24, line 27. _Quare vani sunt illi Chemici._--Gilbert had no faith in the alchemists. On pp. 19 and 21 he had poked fun at them for declaring the metals to be constituted of sulphur and quicksilver, and for pronouncing the fixed earth in iron to be sulphur. On p. 20 he had denied their proposition that the differences between silver, gold, and copper could arise from proportions of their constituent materials; and he likewise denounced unsparingly the supposed relation between the seven metals and the seven planets. He now denounces the vain dreams of turning all metals into gold, and all stones into diamonds. Later he rejects as absurd the magnetic curing of wounds. His detachment from the pseudo-science of his age was unique if not complete.
[77] PAGE 25, LINE 15. Page 25, line 16. _Petro-coriis, & Cabis Biturgibus._--The Petro-corii were a tribe in the neighbourhood of Perigord; the Cubi Biturges another in that of Bourges.
[78] PAGE 25, LINE 21. Page 25, line 23. Pliny's account, as translated by P. Holland (ed. 1601, p. 515), runs thus:
"Of all mines that be, the veine of this mettall is largest, and spreadeth it selfe into most lengths every way: as we may see in that part of Biscay that coasteth along the sea, and upon which the Ocean beateth: where there {26} is a craggie mountaine very steep and high, which standeth all upon a mine or veine of yron. A wonderfull thing, and in manner incredible, howbeit, most true, according as I have shewed already in my Cosmographie, as touching the circuit of the Ocean."
[79] PAGE 26, LINE 15. Page 26, line 12. _quas Clampas nostri vocant._--The name _clamp_ for the natural kiln formed by heaping up the bricks, with ventilating spaces and fuel within the heap, is still current.
[80] PAGE 26, LINE 39. Page 26, line 38. _Pluebat in Taurinis ferrum._--The occurrence is narrated by Scaliger, _De Subtilitate_, Exercitat. cccxxiii.:
"Sed falsò lapidis pluviam creas tu ex pulvere hausto à nubibus, atque in lapidem condensato. At ferrum, quod pluit in Taurinis, cuius frustum apud nos extat, qua ex fodina sustulit nubes? Tribus circiter annis antè, quàm ab Rege provincia illa recepta esset, pluit ferro multis in locis, sed raris" (p. 434, Editio Lutetiæ, 1557).
"During the latter ages of the Roman Empire the _city_ of Augusta Taurinorum seems to have been commonly known (as was the case in many instances in Transalpine Gaul) by the name of the tribe to which it belonged, and is called simply Taurini in the Itineraries, as well as by other writers, hence its modern name of Torino or Turin" (Smith's _Dictionary of Greek and Roman Geographies_, p. 1113).
There exists a considerable literature respecting falls of meteors and of meteoric iron. Livy, Plutarch, and Pliny all record examples. See also _Remarks concerning stones said to have fallen from the clouds_, by Edward King (London, 1796); Chladni, _Ueber den Ursprung der von Pallas gefundenen und anderer ihr ähnlicher Eisenmassen_ (Riga, 1794); _Philosophical Transactions_, vol. lxxviii., pp. 37 and 183; vol. lxxxv., p. 103; vol. xcii., p. 174; Humboldt's _Cosmos_, vol. i. (p. 97 of London edition, 1860); C. Rammelsberg, _Die chemische Natur der Meteoriten_ (Berlin, 1879); Maskelyne, _Some lecture-notes on Meteorites_ printed in _Nature_, vol. xii., pp. 485, 504, and 520, 1875. Maskelyne denominates as _siderites_ those meteorites which consist chiefly of iron. They usually contain from 80 to 95 per cent. of iron, often alloyed with nickel. This meteoric iron is sometimes so pure that it can at once be forged by the smith. An admirable summary of the whole subject is to be found in L. Fletcher's _An Introduction to the study of Meteorites_, publisht by the British Museum (Nat. Hist.), London, 1896.
[81] PAGE 27, LINE 3. Page 26, line 41. _vt Cardanus ... scribit._--The passage runs:
"Vidimus anno MDX cum cecidisset è coelo lapides circiter MCC in agrum fluvio Abduæ conterminum, ex his unum CXX pondo, alium sexaginta delati fuerunt ad reges Gallor[~u] satrapes, plurimi: colos ferrugineus, durities eximia, odor sulphureus" (Cardan, _De Rerum Varietate_, lib. xiiii., cap. lxxii.; Basil., 1557, p. 545).
[82] PAGE 27, LINE 9. Page 27, line 2. _aut stannum, aut plumbum album._ Although most authorities agree in translating _plumbum album_ or _plumbum candidum_ as "tin" (which is unquestionably the meaning in such examples as Pliny's _Nat. Hist._, xxxiv. 347, and iv. 16; or Strabo, iii. 147), nevertheless it is certain that here _plumbum album_ is not given as a synonym of _stannum_ and therefore is not _tin_. That Gilbert meant either spelter or pewter is pretty certain. He based his metallic terms mainly upon Encelius (Christoph Entzelt) whose _De Re Metallica_ was published at Frankfurt in 1551. From this work are taken the following passages: {27}
p. 61. _De Plumbo candido._ Cap. XXXI.
"Veluti plumbum nigr[~u] uocatur à Germanis blei simpliciter, od' schwartzblei: ita plumb[~u] candid[~u] ab his uocatur weissblei, od' ziñ. Impropriè autem plumbum hoc nostrum candidum ziñ, stannum dicitur. Et non sunt idem, ut hactenus voluerunt, stannum et plumbum candidum, unser ziñ. Aliud est stannum, de quo mox agemus: et aliud plumbum candidum nostrum, unser ziñ, quod nigro plumbo quasi est quiddã purius et perfectius...."
p. 62. _De Stanno._ Cap. XXXII.
"In præcedenti capite indicauimus aliud esse stannum, aliud esse plumb[~u] candid[~u]. Illa ergo definitio plumbi candidi, dess zinnes, etiã apud chimistas nõ de stanno, sed de plumbo candido (ut mihi uidetur) intelligenda est, cum dicunt: Stannum (es soll heyssen plumbum candidum) est metallicum album, non purum, lividum...."
p. 63. "Sic uides stannum, secundum Serapionem, metallicum esse quod reperitur in sua propria uena, ut forsitan apud nos bisemut[~u]: ecõtra nostr[~u] candid[~u] plumb[~u], est Plinij candid[~u] plumb[~u], das zin, quod cõflatur ut plumbum nigrum, ex pyrite, galena, et lapillis nigris. Deinde uides stannum Plinio esse quiddã de plumbo nigro, nempe primum fluorem plumbi nigri, als wann man vnser bley ertz schmeltzet, das erst das do fleüsset, zwäre Plinio stannum. Et hoc docet Plinius adulterari pl[~u]bo candido, mit vnserm zinn, vnd wann du ihm recht nachdenckest, daruon die kannen gemacht werden, das man halbwerck heist.... O ir losen vngelerten, vnckenbrenner. Stannum proculdubio Arabis metallum est preciosius nostro candido plumbo: sicuti apud nos bisemuthum quiddam plumbo preciosius."
[83] PAGE 27, LINE 21. Page 27, line 17. _venas ... venis._--It is impossible to give in English this play on words between veins of ore and veins of the animal body.
[84] PAGE 28, LINE 23. Page 28, line 20. _quem nos verticitatem dicimus._--See the notes on Gilbert's glossary, _ante_. The word verticity remained in the language. On p. 140 of Joseph Glanvill's _Vanity of Dogmatizing_ (Lond., 1661) we read: "We believe the _verticity_ of the _Needle_, without a Certificate from the _dayes_ of _old_."
[85] PAGE 29, LINE 15. Page 29, line 16. _Nos verò diligentiùs omnia experientes._--The method of carefully trying everything, instead of accepting statements on authority, is characteristic of Gilbert's work. The large asterisks affixed to Chapters IX. X. XI. XII. and XIII. of Book I. indicate that Gilbert considered them to announce important original magnetical discoveries. The electrical discoveries of Book II., Chapter II., are similarly distinguished. A rich crop of new magnetical experiments, marked with marginal asterisks, large and small, is to be found in Book II., from Chapter XV. to Chapter XXXIV.; while a third series of experimental magnetical discoveries extends throughout Book III.
[86] PAGE 31, LINE 30. Page 31, line 25. _verticem._--The context and the heading of the Chapter appear to require _verticitatem_. All editions, however, read _verticem_.
[87] PAGE 32, LINE 12. Page 32, line 9. _Gartias ab horto._--The passage from Gartias ab Horto runs as follows in the Italian edition of 1616, _Dell' Historia dei Semplici Aromati._... di Don Garzia dall' Horto, Medico Portughese, ... Venezia MDCXVI., p. 208.
"Nè meno è questa pietra velenosa, si come molti hanno tenuto; imperoche le genti di queste bande dicono che la Calamita presa per bocca, però in poca {28} quantità, conserva la gioventù. La onde si racconta, che il Re di Zeilan il vecchio' s'haveva fatto fare tutti i vasi, dove si cocevano le vivãde per lui, di Calamita. Et questo lo disse à me colui proprio, che fu à questo officio destinato."
[88] PAGE 32, LINE 29. Page 32, line 29. _Plutarchus & C. Ptolemæus._--The garlick myth has already been referred to in the note to p. 1. The originals are Plutarch, _Quæstiones Platonicæ_, lib. vii., cap. 7, § 1; C. Ptolemæus, _Opus Quadripartitum,_ bk. i., cap. 3. The English translation of the latter, by Whalley (London, 1701), p. 10, runs: "For if the _Loadstone_ be _Rubbed_ with _Garlick_, the _Iron will not be drawn by it_."
[89] PAGE 32, LINE 32. Page 32, line 33. _Medici nonnulli._--This is apparently a reference to the followers of Rhazes and Paracelsus. The argument of Gilbert as to the inefficacy of powdered loadstones is reproduced more fully by William Barlowe in his _Magneticall Aduertisements_ (1616, p. 7), as follows:
"It is the goodnesse of the _Loadstone_ ioyned with a fit forme that will shew great force. For as a very good forme with base substance can doe but very litle, so the substance of the _Loadstone_ bee it neuer so excellent, except it haue some conuenient forme, is not auaileable. For example, an excellent _loadstone_ of a pound waight and of a good fashion, being vsed artificially, may take vp foure pounds of Iron; beate it into small pouder, and it shall bee of no force to take vp one ounce of Iron; yea I am very well assured that halfe an ounce of a Loadstone of good fashion, and of like vertue will take vp more then that pound will doe being beaten into powder. Whence (to adde this by the way) it appeareth manifestly, that it is a great error of those Physitions and Surgeons, which to remedy ruptures, doe prescribe vnto their Patients to take the pouder of a _Loadstone_ inwardly, and the small filing of iron mingled in some plaister outwardly: supposing that herein the _magneticall_ drawing should doe great wonders."
[90] PAGE 33, LINE 11. Page 33, line 8. _Nicolaus in emplastrum divinum._...--Nicolaus Myrepsus is also known as Præpositas. In his _Liber de compositione medicamentorum_ (Ingoldstat, 1541, 4to) are numerous recipes containing loadstone: for example, Recipe No. 246, called "esdra magna," is a medicine given for inflammation of the stomach and for strangury, compounded of some forty materials including "litho demonis" and "lapis magnetis." The _emplastrum divinum_ does not, however, appear to contain loadstone. In the English tractate, _Præpositas his Practise, a worke ... for the better preservation of the Health of Man. Wherein are ... approved Medicines, Receiptes and Ointmentes. Translated out of Latin in to English by_ L. M. (London, 1588, 4to), we read on p. 35, "An Emplaister of D. N. [Doctor Nicolaus] which the Pothecaries call Divinum." This contains litharge, bdellium, and "green brasse," but no loadstone.
Luis de Oviedo in his treatise _Methodo de la Coleccion y reposicion de las Medicinas simples_, edited by Gregorio Gonçalez, Boticario (Madrid, 1622), gives (p. 502) the following: "Emplasto de la madre. _Recibe_: Nuezes moscadas, clauos, cinamono, artemisia, piedraimon. De cada uno dos onças.... Entre otras differencias que ay de piedraiman se hallan dos. Vna que por la parte que mira al Septentrion, atrae el hierro, por lo quel se llama magnes ferrugineus. Y otra que atrae la carne, a la qual llaman magnes creaginus."
An "Emplastrum sticticum" containing amber, mummy, loadstone, {29} hæmatite, and twenty other ingredients, and declared to be "vulnerum ulcerumque telo inflictorum sticticum emplastrum præstantissimum," is described on p. 267 of the _Basilica chimica_ of Oswaldus Crollius (Frankfurt, 1612).
[91] PAGE 33, LINE 12. Page 33, line 9. _Augustani ... in emplastrum nigrum_....--Amongst the physicians of the Augsburg school the most celebrated were Adolphus Occo, Ambrosio Jung, and Gereone Seyler. This particular reference is to the _Pharmacopoeia Augustana_ ... _a Collegio Medico recognita_, published at Augsburg, and which ran through many editions. The recipe for the "_emplastrum nigrum vulgo Stichpflaster_" will be found on p. 182 of the seventh edition (1621-2). The recipe begins with oil of roses, colophony, wax, and includes some twenty-two ingredients, amongst them mummy, dried earthworms, and two ounces _lapidis magnetis præparati_. The recipe concludes: "Fiat Emplastrum secundùm artem. Perquàm efficax ad recentia vulnera et puncturas, vndè denominationem habet." The volume is a handsome folio not unlike Gilbert's own book, and bears at the end of the prefatory address _ad Lectorem_ identically the same _cul de lampe_ as is found on p. 44 of _De Magnete_.
The contradictions as to the alleged medicinal virtues of loadstone are well illustrated by Galen, who in his _De facultatibus_ says that loadstone is like hæmatite, which is astringent, while in his _De simplici medicina_ he says it is purgative.
[92] PAGE 33, LINE 14. Page 33, line 12. _Paracelsus in fodicationum emplastrum_.--Paracelsus's recipe for a plaster against stab-wounds is to be found in _Wundt vund Leibartznei_ ... D. Theoph. Paracelsus (Frankf., 1555, pp. 63-67).
[93] PAGE 33, LINE 17. Page 33, line 15. _Ferri vis medicinalis_.--This chapter on the medicinal virtues of iron is a summary of the views held down to that time. Those curious to pursue the subject should consult Waring's _Bibliotheca Therapeutica_ (London, 1878). Nor should they miss the rare black-letter quarto by Dr. Nicholas Monardus, of Seville, _Joyfull Newes out of the New-found Worlde_, translated by John Frampton (London, 1596), in which are recited the opinions of Galen, Rhazes, Avicenna, and others, on the medicinal properties of iron. In addition to the views of the Arabic authors, against whom his arguments are directed, Gilbert discusses those of Joannes Manardus, Curtius, and Fallopius. The treatise of Manardus, _Epistolarum medicinalium libri viginti_ (Basil., 1549), is a _résumé_ of the works of Galen and the Arabic physicians, but gives little respecting iron. Curtius (Nicolaus) was the author of a book, _Libellus de medicamentis præparatibus et purgantibus_ (Giessæ Cattorum, 1614). The works of Fallopius are _De Simplicibus Medicamentis purgentibus tractatus_ (Venet., 1566, 4to), and _Tractatus de Compositione Medicamentorum_ (Venet., 1570, 4to).
[94] PAGE 34, LINE 7. Page 34, line 3. _quorundã Arabum opiniones_.--The Arabian authorities referred to here or elsewhere by Gilbert are:
_Albategnius_ (otherwise known as Machometes Aractensis), Muhammad Ibn J[=a]bir, _Al-Batt[=a]n[=i]_.
_Avicenna_ (otherwise Abohali). Abou-'Ali al-'Hoséin ben-'Abd-Allah Ibn-Sinâ, or, shortly, _Ibn Sîna._
_Averroes._ Muhammad Ibn Ahmed Ibn-Roschd, _Abou Al-Walíd._
_Geber._ Ab[=u] M[=u]s[=a] J[=a]bir Ibn Haiy[=a]n, _Al-Tars[=u]si._
_Hali Abas._ 'Alí Ibn Al-'Abbás, _Al Majúsi_. {30}
_Rhazes_, or _Rasis_. Muhammad Ibn Zakar[=i]y[=a].
_Serapio._ Yuhanná Ibn Sarapion.
_Thebit Ben-Kora_ (otherwise Thabit Ibn Corrah). Ab[=u] Thabit Ibn Kurrah, _Al Harrani._
[95] PAGE 34, LINE 38.: Page 34, line 40. _electuarium de scoria ferri descriptum à Raze._--Rhazes or Rasis, whose Arabic name was Muhammad Ibn Zakar[=i]y[=a], wrote _De Simplicibus, ad Almansorem._ In Chap. 63 of this work he gives a recipe for a stomachic, which includes fennel, anise, origanum, black pepper, cinammon, ginger, and iron slag. In the splendid folio work of Rhazes publisht at Venice in 1542, with the title _Habes candide lector Contin[~e]tem Rasis_, Libri ultimi, cap. 295, under the heading _De Ferro,_ are set forth the virtues of iron slag: "Virtus scorie est sicut virtus scorie [a]eris sed debilior in purgãdo: et erugo ferri est stiptica: et c[~u] superpositur retinet fluxus menstruor[~u].... Ait Paulus: aqua in qua extinguitur ferr[~u] calens.... Dico: certificatus sum experientia [~q] valet contra emorryodas diabetem et fluxum menstruorum."
[96] PAGE 35, LINE 16.: Page 35, line 13. _Paulus._--This is not Fra Paolo Sarpi, nor Marco Polo, nor Paulus Jovius the historian, nor Paulus Nicolettus Venetus, but Paulus Aeginæ.
[97] PAGE 35, LINE 29.: Page 35, line 28. _Sed malè Avicenna._--The advice of Avicenna to administer a draught containing powdered loadstone, reads as follows in the Giunta edition (Venice, 1608):
Lib. ii., cap. 470, p. 356. "Magnes quid est? Est lapis qui attrahit ferrum, quum ergo aduritur, fit hæmatites, & virtus ejus est sicut virtus illius.... Datur in potu [ad bibitionem limaturæ ferri, quum retinetur in ventre scoria ferri. Ipse enim extrahit] ipsam, & associatur ei apud exitum. Et dicitur, quando in potu sumuntur ex eo tres anulusat cum mellicrato, educit solutione humorem grossum malum."
The passage is identical with that in the Venetian edition of 1486, in both of which the liquid prescribed is mellicratus--mead. Gilbert says that the iron is to be given in juice of _mercurialis_. Here he only follows Matthiolus, who, in his _Commentaries on Dioscorides_, says (p. 998 of the Basil. edition of 1598): "Sed (vt idem Auicenna scribit) proprium hujusce ferrei pharmaci antidotum, est lapis magnes drachmæ pondere potus, ex mercurialis, vel betæ succo."
Serapio, in his _De Simplicibus Medicinis_ (Brunfels' edition, Argentorati, 1531), p. 264, refers to Galen's prescription of iron scoriæ, and under the article _de lapide magnetis_, p. 260, quotes Dioscorides as follows: "Et uirtus huius lapidis est, ut quãdo dantur in potu duo onolosat ex eo c[~u] melicrato, laxat humores grossos."
The original passage in Dioscorides, _De Materia Medica,_ ch. 147 (Spengel's edition of 1829) runs: "[Greek: Tou de magnêtou lithou aristos estin ho ton sidêron eucherôs helkôn, kai tên chroan kuanizôn, puknos te kai ouk agan barus. Dunamin de echei pachous agôgon didomenos meta melikratou triôbolou baros; enioi de touton kaiontes anti haimatitou pipraskousin.]."
In the Frankfurt edition of Dioscorides, translated by Ruellius (1543), the passage is:
"Magnes lapis optimus est, qui ferrum facile trahit, colore ad coeruleum uergente, densus, nec admodum gravis. Datur cum aqua mulsa, trium obolorum pondere, ut crassos humores eliciat. Sunt qui magnetem cremat[=u] pro hæmatite vendant...."
In the _Scholia_ of Joannes Lonicerus upon Dioscorides _In Dioscoridæ {31} Anazarbei de re medica libros a Virgilio Marcello versos, Scholia nova, Ioanne Lonicero autore_ (Marburgi, 1543, p. 77), occurs the following:
"_De recremento ferri._ Cap. XLIX.
"[Greek: Skôria sidêrou]. scoria vel recrementum ferri. Quæ per ignem à ferro et cupro sordes separantur ac reijciuntur, et ab aliis metallis [Greek: skôria] uocantur. Omnis scoria, maxime uero ferri exiccat. Acerrimo aceto macerauit Galenus ferri scoriam, ac deinde excocto, pharmacum efficax confecit ad purulentas quæ multo tempore uexatæ erant, aures, admirando spectantium effectu. Ardenti scoria uel recrementum [Greek: helkusma], inquit Galenus."
See also the _Enarrationes eruditissimæ_ of Amatus Lusitanus (Venet., 1597), pp. 482 and 507, upon iron and the loadstone.
[98] PAGE 36, LINE 27. Page 36, line 29. _eijcitur_ for _ejicitur_.
[99] PAGE 37, LINE 18. Page 37, line 22. _ut Cardanus philosophatur._--Cardan's nonsense about the magnet feeding on iron is to be found in _De Subtilitate_, lib. vii. (Basil., 1611, p. 381).
[100] PAGE 38, LINE 4. Page 38, line 7. _ferramenta ... in usum navigantium._--Compare Marke Ridley's _A Short Treatise of Magneticall Bodies and Motions_ (Lond., 1613), p. _a2_ in the _Preface Magneticall_, where he speaks of the "iron-workes" used in building ships. The phraseology of Marke Ridley throws much light on the Latin terms used by Gilbert.
[101] PAGE 38, LINE 36. Page 38, line 42. _vruntur;_ changed in ink to _vrantur_ in the folio of 1600; but _uruntur_ appears in the editions of 1628 and 1633.
[102] PAGE 39, LINE 12. Page 39, line 12. _virumque;_ altered in ink to _virunque_ in all copies of the folio edition of 1600.
[103] PAGE 40, LINE 32. Page 40, line 33. _ad tantos labores exantlandos._--Pumping, as it was in mining before the invention of the steam engine, may best be realized by examining the woodcuts in the _De re metallica_ of Georgius Agricola (Basil., Froben, 1556).
[104] PAGE 40, LINE 34. Page 40, line 36. _quingentas orgyas._--Gilbert probably had in his mind the works of the Rorerbühel, in the district of Kitzbühl, which in the sixteenth century had reached the depth of 3,107 feet. See Humboldt's _Cosmos_ (Lond., 1860, vol. i., p. 149).
[105] PAGE 43, LINE 34. Page 43, line 33. _glis._--This word, here translated _grit_, does not appear to be classical Latin; it may mean _ooze or slime_.
[106] PAGE 45, LINE 25. Page 45, line 26. _Motus igitur ... quinque._ The five kinds of magnetic motions correspond in fact to the remaining sections of the book; as follows: _Coitio_, Book II.; _Directio_, Book III.; _Variatio_, Book IV.; _Declinatio_, Book V.; and _Revolutio_, Book VI.
[107] PAGE 46, LINE 7. Page 46, line 8. _Jofrancus Offusius._--The reference is to the treatise _De divina astrorum faculitate_ of Johannes Franciscus Offusius (Paris, 1570).
[108] PAGE 47, LINE 15. Page 47, line 18. _Græci vocant_ [Greek: êlektron], _quia ad se paleas trahit._ In this discussion of the names given to amber, Gilbert apparently conceives [Greek: êlektron] to be derived from the verb [Greek: helkein]; which is manifestly a doubtful etymology. There has been much discussion amongst philologists as to the derivation of [Greek: êlektron] or [Greek: êlektron], and its possible connection with the word [Greek: êlektôr]. This discussion has been somewhat obscured by the circumstance that the Greek authors unquestionably used [Greek: êlektron] (and the Latins their word _electrum_) in two different significations, some of them using these words to mean amber, others to mean a shining {32} metal, apparently of having qualities between those of gold and silver, and probably some sort of alloy. Schweigger, _Ueber das Elektron der Alten_ (Greifswald, 1848), has argued that this metal was indeed no other than platinum: but his argument partakes too much of special pleading. Those who desire to follow the question of the derivation of [Greek: êlektron] may consult the following authorities: J. M. Gessner, _De Electro Veterum_ (Commentt. Soc. Reg. Scientt. Goetting., vol. iii., p. 67, 1753); Delaunay, _Mineralogie der Alten_, Part II., p. 125; Buttmann, _Mythologus_ (Appendix I., _Ueber das Elektron_), Vol. II., p. 355, in which he adopts Gilbert's derivation from [Greek: helkein]; Beckmann, _Ursprung und Bedeutung des Bernsteinnamens Elektron_ (Braunsberg, 1859); Th. Henri Martin, _Du Succin, de ses noms divers et de ses variétés suivant les anciens_ (Mémoires de l'Académie des Inscriptions et Belles-lettres, Tome VI., 1^{re} série, 1^{re} partie, 1860); Martinus Scheins, _De Electro Veterum Metallico_ (Inaugural dissertation, Berlin, 1871); F. A. Paley, _Gold Worship in relation to Sun Worship_ (Contemporary Review, August, 1884). See also Curtius, _Grundzüge der griechischen Etymologie_, pp. 656-659. The net result of the disputations of scholars appears to be that [Greek: êlektôr] (he who shines) is a masculine form to which there corresponds the neuter form [Greek: êlektron] (that which shines). Stephanus admits the accentuation used by Gilbert, [Greek: êlektron], to be justified from the _Timæus_ of Plato; see Note to p. 61.
[109] PAGE 47, LINE 16. Page 47, line 19. [Greek: harpax] dicitur, & [Greek: chrusophoron].--With respect to the other names given to amber, M. Th. Henri Martin has written (see previous note) so admirable an account of them that it is impossible to better it. It is therefore given here entire, as follows:
"Le succin a reçu chez les anciens des noms très-divers. Sans parler du nom de [Greek: lunkourion], lyncurium, qui peut-être ne lui appartient pas, comme nous le montrerons plus loin, il s'est nommé chez les Grecs le plus souvent [Greek: êlektron] au neutre,^1 mais aussi [Greek: êlektros] au masculin^2 et même au féminin,^3 [Greek: chrusêlektros],^4 [Greek: chrusophoros]^5 et peut-être, comme nous l'avons vu, [Greek: chalkolithanon]; plus tard [Greek: souchion]^6 ou [Greek: souchinos]^7, et [Greek: êlektrianos lithos];^8 plus tard encore [Greek: berenikê], [Greek: beronikê] ou [Greek: bernikê];^9 il s'est nommé [Greek: harpax] chez les Grecs établis en Syrie;^{10} chez les Latins _succinum_, _electrum_, et deux variétés, _chryselectrum_ et _sualiternicum_ {33} ou _subalternicum_;^{11} chez les Germains, _Gless_;^{12} chez les Scythes, _sacrium_;^{13} chez les Egyptiens, _sacal_;^{14} chez les Arabes, _karabé_^{15} ou _kahraba_;^{16} en persan, _káruba_.^{17} Ce mot, qui appartient bien à la langue persane, y signifie _attirant la paille_, et par conséquent exprime l'attraction électrique, de même que le mot [Greek: harpax] des Grecs de Syrie. En outre, le nom de _haur roumi_ (_peuplier romain_) était donné par les Arabes, non-seulement à l'arbre dont ils croyaient que le succin était la gomme, mais au succin lui-même. _Haur roumi_, transformé en _aurum_ par les traducteurs latins des auteurs arabes, et consondu mal à propos avec _ambar_ ou _ambrum_, nom arabe latinisé de l'ambre gris, a produit le nom moderne d'_ambre_, nom commun à l'_ambre jaune_ ou succin, qui est une résine fossile, et à l'_ambre gris_, concrétion odorante qui se forme dans les intestines des cachalots. On ne peut dire avec certitude si le nom de basse grécité [Greek: bernikê] est la source ou le dérivé de _Bern_, radical du nom allemand du succin (_Bernstein_). Quoi qu'il en soit, le mot [Greek: bernikê] a produit _vernix_, nom d'une gomme dans la basse latinité, d'où nous avons fait _vernis_.^{18}"
^1 Voyez Hérodote, III., 115; Platon, _Timée_, p. 80 c; Aristote, _Météor._, IV., 10; Théophraste, _Hist. des plantes_, IX., 18 (19), § 2; _Des pierres_, § 28 et 29; Diodore de Sic., V., 23; Strabon, IV., 6, n^o 2, p. 202 (Casaubon); Dioscoride, _Mat. méd._, I., 110; Plutarque, _Questions de table_, II., 7, § 1; _Questions platoniques_, VII., 1 et 7; Lucien, _Du succin et des cygnes_; le même, _De Pastrologie_, § 19; S. Clément, _Strom._ II., p. 370 (Paris, 1641, in-fol.); Alexandre d'Aphr., _Quest. phys. et mor._, II., 23; Olympiodore, _Météor._, I., 8, fol. 16, t. I., p. 197 (Ideler) et l'abréviateur d'Etienne de Byzance au mot [Greek: Êlektrides].
^2 Voyez Sophocle, _Antigone_, v. 1038, et dans Eustathe, sur l'_Iliade_, II., 865; Elien, _Nat. des animaux_, IV. 46; Quintus de Smyrne, V., 623; Eustathe, sur la _Périégèse_ de Denys, p. 142 (Bernhardy), et sur l'_Odyssée_, IV., 73; et Suidas au mot [Greek: hualê].
^3 Voyez Alexandre, _Problèmes_, sect. 1, prooem., p. 4 (Ideler); Eustathe, sur l'_Odyssée_, IV., 73, et Tzetzès, _Chiliade_ VI., 650.
^4 Voyez Psellus, _Des pierres_, p. 36 (Bernard et Maussac).
^5 Voyez Dioscoride, _Mat. méd._, I., 110.
^6 Voyez S. Clément, _Strom._, II., p. 370 (Paris, 1641, in-fol.). Il paraît distinguer l'un de l'autre [Greek: to souchion] et [Greek: to êlektron], probablement parce qu'il attribue à tort au métal [Greek: êlektron] la propriété attractive du succin.
^7 Voyez le faux Zoroastre, dans les _Géoponiques_, XV., 1, § 29.
^8 Voyez le faux Zoroastre, au même endroit.
^9 Voyez Eustathe, sur l'_Odyssée_, IV., 73; Tzetzès, _Chil._ VI., 650; Nicolas Myrepse, _Antidotes_, ch. 327, et l'Etymol. Gud. au mot [Greek: êlektron]. Comparez Saumaise, Exert. plin., p. 778.
^{10} Voyez Pline, XXXVII., 2, s. 11, n^o 37.
^{11} Voyez Pline, XXXVII., 2, s. 11-13, et Tacite, _Germanie_, ch. 45. La forme _sualiternicum_, dans Pline (s. 11, n^o 33), est donnée par le manuscrit de Bamberg et par M. Sillig (t. V., p. 390), au lieu de la forme _subalternicum_ des éditions antérieures.
^{12} Voyez Tacite et Pline, _ll. cc._
^{13} Voyez Pline, XXXVII., 2, s. 11, n^o 40, Comp. J. Grimm, _Gesch. der deutsch. Sprache_, Kap. x., p. 233 (Leipzig, 1848, in-8).
^{14} Pline, _l. c._
^{15} Voyez Saumaise, _De homon. hyles iatricæ_, c. 101, p. 162 (1689, in-fol.).
^{16} Voyez Sprengel, sur Dioscoride, t. II., pp. 390-391.
^{17} Voyez M. de Sacy, cité par Buttmann, _Mythologus_, t. II., pp. 362-363.
^{18} Voyez Saumaise, _Ex. plin._, p. 778. Il n'est pas probable que le mot [Greek: bernikê] ou [Greek: berenikê] nom du succin dans la grécité du moyen âge, soit lié étymologiquement avec le nom propre [Greek: berenikê], qui vient de l'adjectif macédonien [Greek: berenikos] pour [Greek: pherenikos].
[110] PAGE 47, LINE 17. Page 47, line 20. _Mauri vero Carabem appellant, quià solebant in sacrificijs, & deorum cultu ipsum libare. Carab enim significat offerre Arabicè; ita Carabe, res oblata; aut rapiens paleas, vt Scaliger ex Abohali citat, ex linguâ Arabicâ, vel Persicâ._--The printed text, line 18, has "Non rapiens paleas," but in all copies of the folio of 1600, the "Non" has been altered in ink into "aut," possibly by Gilbert's own hand. Nevertheless the editions of 1628 and 1633 both read "Non." There appears to be no doubt that the origin of the word _Carabe_, or _Karabe_, as assigned by Scaliger, is substantially correct. As shown in the preceding note, Martin adopted this view. If any doubt should remain it will be removed by the following notes which are due to Mr. A. Houtum Schindler (member of the Institution of Electrical Engineers), of Terahan.
Reference is made to the magnetic and electric properties of stones in three early Persian lapidaries. There are three stones only mentioned, amber, loadstone, and garnet. The electric property of the diamond is not mentioned. The following extracts are from the _Tansûk nâmah_, by Nasîr ed dîn Tûsi, A.D. 1260. The two other treatises give the first extracts in the same words.
"_Kâhrubâ_, also _Kahrabâ_ [Amber],
"Is yellow and transparent, and has its name from the property, which it possesses, of attracting small, dry pieces of straw or grass, after it has been rubbed with cloth and become warm. [Note. In Persian, Kâh = straw; rubâ = the robber, hence Kâhrubâ = the straw-robber.] Some consider it a mineral, and say that it is found in the Mediterranean and Caspian seas, floating on the surface, but this is not correct. The truth is that Kâhrubâ {34} is the gum of a tree, called jôz i rûmî [_i.e._, roman nut; walnut?], and that most of it is brought from Rûm [here the Eastern Rome] and from the confines of Sclavonia and Russia. On account of its bright colour and transparency it is made into beads, rings, belt-buckles, &c. ... &c.
* * * * *
"The properties of attraction and repulsion are possessed by other substances than loadstone, for instance, by amber and bîjâdah,^1 which attract straws, feathers, etc., and of many other bodies, it can be said that they possess the power of attraction. There is also a stone which attracts gold; it has a pure yellow colour. There is also a stone which attracts silver from distances of three or two yards. There are also the stone which attracts tin, very hard, and smelling like asafoetida, the stone attracting hair, the stone attracting meat, etc., but, latterly, no one has seen these stones: no proof, however, that they do not exist."
Avicenna (Ibn Sinâ) gives the following under the heading of _Karabe_ (see _Canona Medicinæ_, Giunta edition, Venet., 1608, lib. ii., cap. 371, p. 336):
"Karabe quid est? Gumma sicut sandaraca, tendens ad citrinitatem, & albedinem, & peruietatem, & quandoque declinat ad rubedinem, quæ attrahit paleas, & [fracturas] plantarum ad se, & propter hoc nominatur Karabe, scilicet rapiens paleas, persicè.... Karabe confert tremori cordis, quum bibitur ex eo medietas aurei cum aqua frigida, & prohibet sputum sanguinis valde.... Retinet vomitum, & prohibet materias malas a stomacho, & cum mastiche confortat stomachum.... Retinet fluxum sanguinis ex matrice, & ano, & fluxum ventris, & confert tenasmoni."
Scaliger in _De Subtilitate_, _Exercitatio_ ciii., § 12, the passage referred to by Gilbert says: "Succinum apud Arabas uocatur, Carabe: quod princeps Aboali, rapiens paleas, interpretatur" (p. 163 _bis_, editio Lutetiæ, 1557).
^1 _Bîjâdah_ is classified by Muhammad B. Mansûr (A.D. 1470) and by Ibn al Mubârak (A.D. 1520) under "stones resembling ruby"; the Tansûk nâmah describes it in a separate chapter. From the description it can be identified with the almandine garnet, and the method of cutting this stone _en cabochon_, with hollow back in order to display its colour better is specially mentioned. The Tansûk nâmah only incidentally refers to the electric property of the _bîjâdah_ in the chapter on loadstone, but the other two treatises specially refer to it in their description of the stone. The one has: "_Bîjâdah_ if rubbed until warm, attracts straws and other light bodies just as amber does"; the other: "_Bîjâdah_, if rubbed on the hair of the head, or on the beard, attracts straws." Surûri, the lexicographer, who compiled a dictionary in 1599, considers the _bîjâdah_ "a red ruby which possesses the property of attraction." Other dictionaries do not mention the attractive property, but some authors confound the stone with amber, calling it _Kâbrubâ_, the straw-robber. The _bîjâdah_ is not rubellite (red tourmaline) for it is described in the lapidaries as common, whereas rubellite (from Ceylon) has always been rare, and was unknown in Persia in the thirteenth century.
[111] PAGE 47, LINE 21. Page 47, line 25. _Succinum seu succum._--Dioscorides regarded amber as the inspissated juice of the poplar tree. From the Frankfurt edition of 1543 (_De Medicinali materia, etc._) edited by Ruellius, we have, liber i., p. 53:
_Populus._ Cap. XCIII.
"... Lachrymam populorum commemorant quæ in Padum amnem defluat, durari, ac coire in succinum, quod electrum vocant, alii chrysophorum. id attritu jucundum odorem spirat, et aurum colore imitatur. tritum potumque stomachi ventrisque fluxiones sistit."
To this Ruellius adds the commentary:
"Succinum seu succina gutta à succo dicta, Græcis [Greek: êlektrom] [sic], esse {35} lachryma populi albæ, vel etiam nigræ quibusdam videtur, ab ejusdem arboris resina. Dioscoridi et Galeno dicta differens et [Greek: pterugophoros], id est paleas trahens, quoque vocatur, quantum ei quoque Galenus tribuit li. 37, ca. 9. Succinum scribit à quibusdam pinei generis arboribus, ut gummi à cerasis excidere autumno, et largum mitti ex Germania septentrionali, et insulis maris Germanici. quod hodie nobis est compertissimum: ad hæc liquata igni valentiore, quia à frigido intensiore concrevit. pineam aperte olet, calidum primo gradu, siccum secundo, stomachum roborat, vomitum, nauseam arcet. cordis palpitationi prodest. pravorem humorum generationem prohibet.
"Germani weiss und gelbaugstein et bre[=n]stein.
"Galli ambra vocant: vulgo in corollis precariis frequens."
In the scholia of Johann Lonicer in his edition of Dioscorides, we find, lib. i., cap. xcviii., _De nigra Populo_:
"[Greek: aigeiros], populus nigra ... idem electrum vel succinum [Greek: haigeirou] lachrymam esse adseverat [Paulus], cui præter vires quæ ab Dioscoride recensentur, tribuit etiam vim sistendi sanguinis, si tusum in potu sumatur. Avicennæ Charabe, ut colligitur ex Joanne Jacobo Manlio, est electrum hoc Dioscoridis, attestatur Brunfelsius. Lucianus planè nullum electrum apud Eridanum seu Padum inveniri tradit, quandoquidem ne populus quidem illa ab nautis ei demonstrari potuerit. Plinius rusticas transpadanas ex electro monilia gestare adfirmat, quum à Venetis primum agnoscere didicissent adversus nimirum vitia gutturis et tonsillarum. Num sit purgamentum maris, vel lachryma populi, vel pinus, vel ex radiis occidentis solis nascatur, vel ex montibus Sudinorum profluat, incertum etiam Erasmus Stella relinquit. Sudinas tamen Borussiorum opes esse constat."
Matthiolus (in _P. A. Mattioli ... Opera quæ extant omnia, hoc est Commentarii in vi libros P. Dioscoridis de materia medica_, Frankfurt, 1596, p. 133) comments on the suggestion of Galen that amber came from the _Populus alba_, and also comments on the Arabic, Greek, and Latin names of amber.
The poplar-myth is commemorated by Addison (in _Italy_) in the lines:
No interwoven reeds a garland made, To hide his brows within the vulgar shade; But poplar wreathes around his temples spread, And tears of amber trickled down his head.
Amber is, however, assuredly not derived from any poplar tree: it comes from a species of pine long ago extinct, called by Göppert the _pinites succinifer_.
Gilbert does not go into the medicinal uses, real or fancied, that have been ascribed to amber in almost as great variety as to loadstone. Pliny mentions some of these in his _Natural Historie_ (English version of 1601, p. 609):
"He [Callistratus] saith of this yellow Amber, that if it be worne about the necke in a collar, it cureth feavers, and healeth the diseases of the mouth, throat, and jawes: reduced into pouder and tempered with honey and oile of roses, it is soveraigne for the infirmities of the eares. Stamped together with the best Atticke honey, it maketh a singular eyesalve for to help a dim sight: pulverized, and the pouder thereof taken simply alone, or else drunke in water with Masticke, is soveraigne for the maladies of the stomacke."
Nicolaus Myrepsus (Recipe 951, _op. citat._) gives a prescription for {36} dysentery and diabetes confiding chiefly of "Electri vel succi Nili (Nili succum appellant Arabes Karabem)."
[112] PAGE 47, LINE 22. Page 47, line 26. _Sudauienses seu Sudini._--Cardan in _De Rerum Varietate_, lib. iii., cap. xv. (Editio Basil., 1556, p. 152), says of amber:
"Colligitur in quadam penè insula Sudinorum, qui nunc uoc[=a]tur Brusci, in Prussia, nunc Borussia, juxta Veneticum sinum, & sunt orientaliores ostiis Vistulæ fluuii: ubi triginta pagi huic muneri destinati sunt," etc. He rejects the theory that it consists of hardened gum.
There exists an enormous literature concerning Amber and the Prussian amber industry. Amongst the earliest works (after Theophrastus and Pliny) are those of Aurifaber (_Bericht über Agtstein oder Börnstein_, Königsberg, 1551); Goebel (_De Succino, Libri duo, authore Severino Goebelio, Medico Doctore_, Regiomont., 1558); and Wigand (_Vera historia de Succino Borussico_, Jena, 1590). Later on Hartmann, P. J. (_Succini Prussici Physica et civilis Historia_, Francofurti, 1677); and the splendid folio of Nathaniel Sendel (_Historia Succinorum corpora aliena involventium_, Lipsiæ, 1742), with its wealth of plates illustrating amber specimens, with the various included fossil fauna and flora. Georgius Agricola (_De natura Fossilium_, liber iv.), and Aldrovandi (_Musæeum Metallicum_, pp. 411-412) must also be mentioned. Bibliographies of the earlier literature are to be found in Hartmann (_op. citat._), and in Daniel Gralath, _Elektrische Bibliothek_ (_Versuche und Abhandlungen der Naturforschenden Gesellschaft in Danzig_, Zweiter Theil, pp. 537-539, Danzig and Leipzig, 1754). See also Karl Müllenhoff, _Deutsche Altertumskunde_, vol. i., Zweites Buch, pp. 211-224, Zinn und Bernsteinhandel (Berlin, 1870), and Humboldt's _Cosmos_ (Bohn's edition, London, 1860, vol. ii., p. 493).
The ancient Greek myth according to which amber was the tears of the Heliades, shed on the banks of the river Eridanus over Phaethon, is not alluded to by Gilbert. It is narrated in well-known passages in Ovid and in Hyginus. Those interested in the modern handling of the myth should refer to Müllenhoff (_op. citat._, pp. 217-223, der Bernsteinmythus), or to that delightful work _The Tears of the Heliades_, by W. Arnold Buffum (London, 1896).
[113] PAGE 47, LINE 30. Page 47, line 36. _quare & muscos ... in frustulis quibusdam comprehensos retinet._--The occurrence of flies in amber was well known to the ancients. Pliny thus speaks of it, book xxxvii., chap. iii. (p. 608 of P. Holland's translation of 1601):
"That it doth destill and drop at the first very clear and liquid, it is evident by this argument, for that a man may see diverse things within, to wit, Pismires, Gnats, and Lizards, which no doubt were entangled and stucke within it when it was greene and fresh, and so remain enclosed within as it waxed harder."
A locust embedded in amber is mentioned in the _Musæum Septalianum_ of Terzagus (Dertonæ, 1664).
Martial's epigram (_Epigrammata_, liber vi., 15) is well known:
Dum Phaethontea formica vagatur in umbra Implicuit tenuem succina gutta feram.
See also Hermann (Daniel), _De rana et lacerta Succino Borussiaco insitis_ {37} (Cracov., 1580; a later edition, Rigæ, 1600). The great work on _inclusa_ in amber is, however, that of Nathaniel Sendel. See the previous note.
Sir Thomas Browne must not be forgotten in this connexion. The _Pseudodoxia_ (p. 64 of the second edition, 1650) says:
"Lastly, we will not omit what Bellabonus upon his own experiment writ from Dantzich unto Mellichius, as he hath left recorded in his chapter _De Succino_, that the bodies of Flies, Pismires and the like, which are said oft times to be included in Amber, are not reall but representative, as he discovered in severall pieces broke for that purpose. If so, the two famous Epigrams hereof in Martiall are but poeticall, the Pismire of Brassavolus Imaginary, and Cardans Mousoleum for a flie, a meer phancy. But hereunto we know not how to assent, as having met with some whose reals made good their representments." See also Pope's _Epistle to Dr. Arbuthnot_, line 169.
[114] PAGE 47, LINE 34. Page 47, line 40. _Commemorant antiqui quod succinum festucas et paleas attrahit._--Pliny (book xxxvii., chap. ii., p. 606 of the English edition of 1601) thus narrates the point:
"Hee [_Niceas_] writeth also, that in Aegypt it [amber] is engendered.... Semblably in Syria, the women (saith hee) make wherves of it for their spindles, where they use to call it Harpax, because it will catch up leaves, straws, and fringes hanging to cloaths."
p. 608. "To come to the properties that Amber hath, If it bee well rubbed and chaufed betweene the fingers, the potentiall facultie that lieth within, is set on work, and brought into actual operation, whereby you shall see it to drawe chaffe strawes, drie leaves, yea, and thin rinds of the Linden or Tillet tree, after the same sort as loadstone draweth yron."
[115] PAGE 47, LINE 36. Page 47, line 42. _Quod etiam facit Gagates lapis._--The properties of Jet were well known to the mediæval writers. _Julius Solinus_ writes in _De Mirabilibus_, chapter xxxiv., _Of Britaine_ (English version of 1587 by A. Golding):
"Moreover to the intent to passe the large aboundance of sundry mettals (whereof Britaine hath many rich mynes on all sides), Here is store of the stone called Geate, and y^e best kind of it. If ye demaund y^e beautie of it, it is a black Jewell: if the qualitie, it is of no weight: if the nature, it burneth in water, and goeth out in Oyle; if the power, rubbe it till it be warme, and it holdeth such things as are laide to it; as Amber doth. The Realme is partlie inhabited of barbarous people, who even frõ theyr childhoode haue shapes of divers beastes cunninglye impressed and incorporate in theyr bodyes, so that beeing engraued as it were in theyr bowels, as the man groweth, so growe the marks painted vpon him...."
Pliny describes it as follows (p. 589, English edition of 1601):
"The Geat, which otherwise we call Gagates, carrieth the name of a toune and river both in Lycia, called Gages: it is said also, that the sea casteth it up at a full tide or high water into the Island Leucola, where it is gathered within the space of twelve stadia, and no where else: blacke it is, plaine and even, of a hollow substance in manner of the pumish stone, not much differing from the nature of wood; light, brittle, and if it bee rubbed or bruised, of a strong flavour." (Book xxxvi., chap. xviii.)
In the Commentary of Joannes Ruellius upon Dioscorides, _Pedanii Dioscoridis Anazarbei de medicinali materia libri sex, Ioanne Ruellio Suessionensi interprete_ ... (Frankfurt, 1543, fol., liber quintus, cap. xcii.) is the following description:
{38} "In Gagatarum lapidum genere, præferendus qui celeriter accenditur, et odorem bituminis reddit. niger est plerunque, et squalidus, crustosus, per quam levis. Vis ei molliendi, et discutiendi. deprehendit sonticum morbum suffitus, recreatque uuluæ strangulationes. fugat serpentes nidore. podagricis medicaminibus, et a copis additur. In Cilicia nasci solet, qua influens amnis in mare effunditur, proxime oppidum quod Plagiopolis dicitur. vocatur autem et locus et amnis Gagas, in cujus faucibus ii lapides inveniuntur.
"Gagates lapis colore atro, Germanis Schwartzer augstein, voce parum depravata, dicitur. odore dum uritur bituminis, siccat, glutinat, digerit admotus, in corollis precariis et salinis frequens."
And in the _Scholia_ upon Dioscorides of Joannes Lonicer (Marpurgi, 1643, cap. xcvii., p. 80) is the following:
"_De Gagate Lapide._ Ab natali solo, urbe nimirum Gagae Lyciae nomen habet. Galenus se flumen isthuc et lapidem non invenisse, etiamsi naui parua totam Lyciam perlustravit: ait, se autem in caua Syria multos nigros lapides invenisse glebosos, qui igni impositi, exiguam flammam gignerent. Meminit hujus Nicander in Theriacis nempe suffitum hujus abigere venenata."
There is also a good account of _Gagates_ (and of Succinum) by Langius, _Epistola_ LXXV., p. 454, of the work _Epistolarum medicinalium volumen tripartitum_ (Francofurti, 1589).
[116] PAGE 47, LINE 39. Page 47, line 45. _Multi sunt authores moderni._--The modern authors who raised Gilbert's wrath by ignorantly copying out all the old tales about amber, jet, and loadstone, instead of investigating the facts, were, as he says at the beginning of the chapter, some theologians, and some physicians. He seems to have taken a special dislike to Albertus Magnus, to Puteanus (Du Puys), and to Levinus Lemnius.
[117] PAGE 47, LINE 39. Page 47, line 46. _& gagate._--The editions of 1628 and 1633 both read _ex gagate_.
[118] PAGE 48, LINE 14. Page 48, line 16. _Nam non solum succinum, & gagates (vt illi putant) allectant corpuscula._--The list of bodies known to become electrical by friction was not quite so restricted as would appear from this passage. Five, if not six, other minerals had been named in addition to amber and jet.
(1.) _Lyncurium._ This stone, about which there has been more obscurity and confusion than about any other gem, is supposed by some writers to be the tourmaline, by others a jacinth, and by others a belemnite. The ancients supposed it to be produced from the urine of the lynx. The following is the account of Theophrastus, _Theophrastus's History of Stones. With an English Version_ ..., by "Sir" John Hill, London, 1774, p. 123, ch. xlix.-l. "There is some Workmanship required to bring the Emerald to its Lustre, for originally it is not so bright. It is, however, excellent in its Virtues, as is also the _Lapis Lyncurius_, which is likewise used for engraving Seals on, and is of a very solid Texture, as Stones are; it has also an attractive Power, like that of Amber, and is said to attract not only Straws and small pieces of Sticks, but even Copper and Iron, if they are beaten to thin pieces. This Diocles affirms. The _Lapis Lyncurius_ is pellucid, and of a fire Colour." See also W. Watson in _Philos. Trans._, 1759, L. i., p. 394, _Observations concerning the Lyncurium of the ancients_.
(2.) _Ruby._
(3.) _Garnet._ The authority for both these is Pliny, _Nat. Hist._, book xxxvii., chap. vii. (p. 617 of English edition of 1601).
{39} "Over and besides, I find other sorts of Rubies different from those above-named;... which being chaufed in the Sun, or otherwise set in a heat by rubbing with the fingers, will draw unto them chaffe, strawes, shreads, and leaves of paper. The common Grenat also of Carchedon or Carthage, is said to doe as much, although it be inferiour in price to the former."
(4.) _Jasper._ Affaytatus is the authority, in _Fortunii Affaitati Physici atque Theologi ... Physicæ & Astronomicæ c[=o]siderationes_ (Venet., 1549), where, on p. 20, he speaks of the magnet turning to the pole, likening it to the turning of a "palea ab Ambro vel Iaspide et hujuscemodi lapillis lucidis."
(5.) _Lychnis._ Pliny and St. Isidore speak of a certain stone _lychnis_, of a scarlet or flame colour, which, when warmed by the sun or between the fingers, attracts straws or leaves of papyrus. Pliny puts this stone amongst carbuncles, but it is much more probably _rubellite_, that is to say, red tourmaline.
(6.) _Diamond._ In spite of the confusion already noted, _à propos_ of _adamas_ (Note to p. 47), between loadstone and diamond, there seems to be one distinct record of an attractive effect having been observed with a rubbed diamond. This was recorded by Fracastorio, _De sympathia et antipathia rerum_ (Giunta edition, Venice, MDLXXIIII, chap. v., p. 60 _verso_), "cujus rei & illud esse signum potest, cum confricata quædã vt Succinum, & Adamas fortius furculos trahunt." And (on p. 62 _recto_); "nam si per similitudine (vt supra diximus) fit hæc attractio, cur magnes non potius magnetem trahit, [~q] ferrum, & ferrum non potius ad ferrum movetur, quàm ad magnetem? quæ nam affinitas est pilorum, & furculorum cum Electro, & Adamante? præsertim [~q] si cum Electro affines sunt, quomodo & cum Adamante affinitatem habebunt, qui dissimilis Electro est?" An incontestable case of the observation of the electrification of the diamond occurs in Gartias ab Horto. The first edition of his _Historia dei Semplici Aromati_ was publisht at Goa in India in 1563. In chapter xlviii. on the Diamond, occur these words (p. 200 of the Venetian edition of 1616): "Questo si bene ho sperimentato io più volte, che due Diamanti perfetti fregati insieme, si vniscono di modo insieme, che non di leggiero li potrai separare. Et ho parimente veduto il Diamante dopo di esser ben riscaldato, tirare à se le festuche, non men, che si faccia l'elettro." See also Aldrovandi, _Musæum Metallicum_ (Bonon., 1648, p. 947).
Levinus Lemnius also mentions the Diamond along with amber. See his _Occulta naturæ miracula_ (English edition, London, 1658, p. 199).
[119] PAGE 48, LINE 16. Page 48, line 18. _Iris gemma._--The name _iris_ was given, there can be little doubt, to clear six sided prisms of rock-crystal (quartz), which, when held in the sun's beams, cast a crude spectrum of the colours of the rainbow. The following is the account of it given in Pliny, book xxxvii., chap. vii. (p. 623 of the English version of 1601):
"... there is a stone in name called Iris: digged out of the ground it is in a certaine Island of the red sea, distant from the city Berenice three score miles. For the most part it resembleth Crystall: which is the reason that some hath tearmed it the root of Crystall. But the cause why they call it Iris, is, That if the beames of the Sunne strike upon it directly within house, it doth send from it against the walls that bee neare, the very resemblance both in forme and also in colour of a rainebow; and eftsoones it will chaunge the same in much varietie, to the great admiration of them that behold it. For certain it is knowne, that six angles it hath in manner of the Crystall: but they say that some of them have their sides rugged, and the same {40} unequally angled: which if they be laid abroad against the Sunne in the open aire, do scatter the beames of the Sunne, which light upon them too and fro: also that others doe yeeld a brightnes from themselves, and thereby illuminat all that is about them. As for the diverse colours which they cast forth, it never happeneth but in a darke or shaddowie place: whereby a man may know, that the varietie of colours is not in the stone Iris, but commeth by the reverberation of the wals. But the best Iris is that which representeth the greatest circles upon the wall, and those which bee likest unto rainebowes indeed."
In the English translation of Solinus's _De Mirabilibus_ (_The excellent and pleasant worke of Julius Solinus containing the noble actions of humaine creatures, the secretes and providence of nature, the descriptions of countries ... tr. by A. Golding, gent._, Lond., 1587), chapter xv. on Arabia has the following:
"Hee findeth likewise the Iris in the Red sea, sixe cornered as the Crystall: which beeing touched with the Sunnebeames, casteth out of him a bryght reflexion of the ayre like the Raynebowe."
Iris is also mentioned by Albertus Magnus (_De mineralibus_, Venet., 1542, p. 189), by Marbodeus Gallus (_De lapidibus_, Par. 1531, p. 78), who describes it as "crystallo simulem sexangulam," by Lomatius (_Artes of curious Paintinge_, Haydocke's translation, Lond., 1598, p. 157), who says, "... the Sunne, which casting his beames vpon the _stone Iris_, causeth the _raine-bowe_ to appeare therein ...," and by "Sir" John Hill (_A General Natural History_, Lond., 1748, p. 179).
Figures of the Iris given by Aldrovandi in the _Musæum Metallicum_ clearly depict crystals of quartz.
[120] PAGE 48, LINE 16. Page 48, line 18. _Vincentina, & Bristolla (Anglica gemma siue fluor)_. This is doubtless the same substance as the _Gemma Vincentij rupis_ mentioned on p. 54, line 16 (p. 54, line 18, of English Version), and is nothing else than the so-called "Bristol diamond," a variety of dark quartz crystallized in small brilliant crystals upon a basis of hæmatite. To the work by Dr. Thomas Venner (Lond., 1650), entitled _Via Recta_ or the _Bathes of Bathe_, there is added an appendix, _A Censure concerning the water of Saint Vincents Rocks neer Bristol (Urbs pulchra et Emporium celebre)_, in which, at p. 376, occurs this passage: "This Water of Saint _Vincents_ Rock is of a very pure, cleare, crystalline substance, answering to those crystalline Diamonds and transparent stones that are plentifully found in those Clifts."
In the _Fossils Arranged_ of "Sir" John Hill (Lond., 1771), p. 123, is the following entry: "Black crystal. Small very hard heavy glossy. Perfectly black, opake. Bristol (grottos, glass)" referring to its use.
The name _Vincentina_ is not known as occurring in any mineralogical book. Prof. H. A. Miers, F.R.S., writes concerning the passage: "_Anglica gemma sive fluor_ seems to be a synonym for _Bristolla_, or possibly for _Vincentina et Bristolla_. Both quartz and fluor are found at Clifton. In that case Vincentina and Bristolla refer to these two minerals, and if so one would expect Bristolla to be the Bristol Diamond, and Vincentina to be the comparatively rare Fluor spar from that locality."
At the end of the edition of 1653 of Sir Hugh Plat's _Jewel House of Art and Nature_, is appended _A rare and excellent Discourse of Minerals, Stones, Gums, and Rosins; with the vertues and use thereof_, By D. B. _Gent_. Here, p. 218, we read:
"We have in England a stone or mineral called a Bristol stone (because {41} many are found thereabouts) which much resembles the Adamant or Diamond, which is brought out of Arabia and Cyprus; but as it is wanting of the same hardnesse, so falls it short of the like vertues."
[121] PAGE 48, LINE 18. Page 48, line 19. _Crystallus._--Rock-crystal. Quartz. Pliny's account of it (Philemon Holland's version of 1601, p. 604) in book xxxvii., chap, ii., is:
"As touching Crystall, it proceedeth of a contrarie cause, namely of cold; for a liquor it is congealed by extreame frost in manner of yce; and for proofe hereof, you shall find crystall in no place els but where the winter snow is frozen hard: so as we may boldly say, it is verie yce and nothing else, whereupon the Greeks have give it the right name Crystallos, _i._ Yce.... Thus much I dare my selfe avouch, that crystall groweth within certaine rockes upon the Alps, and these so steepe and inaccessible, that for the most part they are constrained to hang by ropes that shall get it forth."
[122] PAGE 48, LINE 18. Page 48, line 20. _Similes etiam attrahendi vires habere videntur vitrum ... sulphur, mastix, & cera dura sigillaris._ If, as shown above, the electric powers of diamond and ruby had already been observed, yet Gilbert was the first beyond question to extend the list of _electrics_ beyond the class of precious stones, and his discovery that _glass_, _sulphur_, and _sealing-wax_ acted, when rubbed, like amber, was of capital importance. Though he did not pursue the discovery into mechanical contrivances, he left the means of that extension to his followers. To Otto von Guericke we owe the application of sulphur to make the first electrical machine out of a revolving globe; to Sir Isaac Newton the suggestion of glass as affording a more mechanical construction.
Electrical attraction by natural products other than amber after they have been rubbed must have been observed by the primitive races of mankind. Indeed Humboldt in his _Cosmos_ (Lond., 1860, vol. i., p. 182) records a striking instance:
"I observed with astonishment, on the woody banks of the Orinoco, in the sports of the natives, that the excitement of electricity by friction was known to these savage races, who occupy the very lowest place in the scale of humanity. Children may be seen to rub the dry, flat and shining seeds or husks of a trailing plant (probably a _Negretia_) until they are able to attract threads of cotton and pieces of bamboo cane."
[123] PAGE 48, LINE 23. Page 48, line 25. _arsenicum_.--This is _orpiment_. See the _Dictionary of metallick words_ at the end of Pettus's _Fleta Minor_.
[124] PAGE 48, LINE 23. Page 48, line 26. _in convenienti coelo sicco_.--The observation that only in a dry climate do rock-salt, mica, and rock-alum act as electrics is also of capital importance. Compare page 56.
[125] PAGE 48, LINE 27. Page 48, line 31. _Alliciunt hæc omnia non festucas modo & paleas._--Gilbert himself marks the importance of this discovery by the large asterisk in the margin. The logical consequence was his invention of the first _electroscope_, the _versorium non magneticum_, made of any metal, figured on p. 49.
[126] PAGE 48, LINE 34. Page 48, line 36. _quod tantum siccas attrahat paleas, nec folia ocimi._--This silly tale that basil leaves were not attracted by amber arose in the _Quæstiones Convivales_ of Plutarch. It is repeated by Marbodeus and was quoted by Levinus Lemnius as true. Gilbert denounced it as nonsense. Cardan (_De Subtilitate_, Norimb., 1550, p. 132) had already contradicted the fable. "Trahit enim," he says, "omnia levia, paleas, festucas, ramenta {42} tenuia metallorum, & ocimi folia, perperam contradicente Theophrasto." Sir Thomas Browne specifically refuted it. "For if," he says, "the leaves thereof or dried stalks be stripped into small strawes, they arise unto Amber, Wax, and other Electricks, no otherwise then those of Wheat or Rye."
[127] PAGE 48, LINE 34. Page 48, line 38. _Sed vt poteris manifestè experiri...._
Gilbert's experimental discoveries in electricity may be summarized as follows:
1. The generalization of the class of _Electrics_. 2. The observation that damp weather hinders electrification. 3. The generalization that electrified bodies attract everything, including even metals, water, and oil. 4. The invention of the non-magnetic _versorium_ or electroscope. 5. The observation that merely warming amber does not electrify it. 6. The recognition of a definite class of _non-electrics_. 7. The observation that certain electrics do not attract if roasted or burnt. 8. That certain electrics when softened by heat lose their power. 9. That the electric effluvia are stopped by the interposition of a sheet of paper or a piece of linen, or by moist air blown from the mouth. 10. That glowing bodies, such as a live coal, brought near excited amber discharge its power. 11. That the heat of the sun, even when concentrated by a burning mirror, confers no vigour on the amber, but dissipates the effluvia. 12. That sulphur and shell-lac when aflame are not electric. 13. That polish is not essential for an electric. 14. That the electric attracts bodies themselves, not the intervening air. 15. That flame is not attracted. 16. That flame destroys the electrical effluvia. 17. That during south winds and in damp weather, glass and crystal, which collect moisture on their surface, are electrically more interfered with than amber, jet and sulphur, which do not so easily take up moisture on their surfaces. 18. That pure oil does not hinder production of electrification or exercise of attraction. 19. That smoke is electrically attracted, unless too rare. 20. That the attraction by an electric is in a straight line toward it.
[128] PAGE 48, LINE 35. Page 48, line 39. _quæ sunt illæ materiæ._--Gilbert's list of electrics should be compared with those given subsequently by Cabeus (1629), by Sir Thomas Browne (1646), and by Bacon. The last-named list occurs in his _Physiological Remains_, published posthumously in 1679; it contains nothing new. Sir Thomas Browne's list is given in the following passage, which is interesting as using for the first time in the English language the noun _Electricities_:
"Many stones also both precious and vulgar, although terse and smooth, have not this power attractive; as Emeralds, Pearle, Jaspis, Corneleans, Agathe, Heliotropes, Marble, Alablaster, Touchstone, Flint and Bezoar. Glasse attracts but weakely though cleere, some slick stones and thick glasses indifferently: Arsenic but weakely, so likewise glasse of Antimony, but Crocus Metallorum not at all. Saltes generally but weakely, as Sal Gemma, Alum, and also Talke, nor very discoverably by any frication: but if gently warmed at the fire, and wiped with a dry cloth, they will better discover their Electricities." _(Pseudodoxia Epidemica_, p. 79.)
In the _Philosophical Transactions_, vol. xx., p. 384, is _A Catalogue of Electrical Bodies_ by the late Dr. Rob. Plot. It begins "Non solum succinum," and ends "alumen rupeum," being identical with Gilbert's list except that he calls "Vincentina & Bristolla" by the name "Pseudoadamas Bristoliensis."
[129] PAGE 49, LINE 25. Page 49, line 30. _non dissimili modo._--The _modus_ {43} _operandi_ of the electrical attractions was a subject of much discussion; see Cardan, _op. citat._
[130] PAGE 51, LINE 2. Page 51, line 1. _appellunt._--This appears to be a misprint for _appelluntur_.
[131] PAGE 51, LINE 22. Page 51, line 23. _smyris._--Emery. This substance is mentioned on p. 22 as a magnetic body.
[132] PAGE 52, LINE 1. Page 51, line 46. _gemmæ ... vt Crystallus, quæ ex limpidâ concreuit._ See the note to p. 48.
[133] PAGE 52, LINE 30. Page 52, line 32. _ammoniacum._--Ammoniacum, or Gutta Ammoniaca, is described by Dioscorides as being the juice of a ferula grown in Africa, resembling galbanum, and used for incense.
"_Ammoniack_ is a kind of Gum like Frankincense; it grows in Lybia, where _Ammon's_ Temple was." Sir Hugh Plat's _Jewel House of Art and Nature_ (Ed. 1653, p. 223).
[134] PAGE 52, LINE 38. Page 52, line 41. _duæ propositæ sunt causæ ... materia & forma._--Gilbert had imbibed the schoolmen's ideas as to the relations of matter and form. He had discovered and noted that in the magnetic attractions there was always a verticity, and that in the electrical attractions the rubbed electrical body had no verticity. To account for these differences he drew the inference that since (as he had satisfied himself) the magnetic actions were due to _form_, that is to say to something immaterial--to an "imponderable" as in the subsequent age it was called--the electrical actions must necessarily be due to _matter_. He therefore put forward his idea that a substance to be an electric must necessarily consist of a concreted humour which is partially resolved into an effluvium by attrition. His discoveries that electric actions would not pass through flame, whilst magnetic actions would, and that electric actions could be screened off by interposing the thinnest layer of fabric such as sarcenet, whilst magnetic actions would penetrate thick slabs of every material except iron only, doubtless confirmed him in attributing the electric forces to the presence of these effluvia. See also p. 65. There arose a fashion, which lasted over a century, for ascribing to "humours," or "fluids," or "effluvia," physical effects which could not otherwise be accounted for. Boyle's tracts of the years 1673 and 1674 on "effluviums," their "determinate nature," their "strange subtilty," and their "great efficacy," are examples.
[135] PAGE 53, LINE 9. Page 53, line 11. _Magnes vero...._--This passage from line 9 to line 24 states very clearly the differences to be observed between the magnetical and the electrical attractions.
[136] PAGE 53, LINE 36. Page 53, line 41. _succino calefacto._--Ed. 1633 reads _succinum_ in error.
[137] PAGE 54, LINE 9. Page 54, line 11. _Plutarchus ... in quæstionibus Platonicis._--The following Latin version of the paragraph in _Quæstio sexta_ is taken from the bilingual edition publisht at Venice in 1552, p. 17 _verso_, liber vii., cap. 7 (or, _Quæstio Septima_ in Ed. Didot, p. 1230).
"Electrum uero quæ apposita sunt, nequaquàm trahit, quem admodum nec lapis ille, qui sideritis nuncupatur, nec quicqu[=a] à seipso ad ea quæ in propinquo sunt, extrinsecus assilit. Verum lapis magnes effluxiones quasdam tum graves, tum etiam spiritales emittit, quibus aer continuatus & iunctus repellitur. Is deinceps alium sibi proximum impellit, qui in orbem circum actus, atque ad inanem locum rediens, ui ferrum fecum rapit & trahit. At Electrum uim quandam flammæ similem & spiritalem continet, quam quidem {44} tritu summæ partis, quo aperiuntur meatus, foras eijcit. Nam leuissima corpuscula & aridissima quæ propè sunt, sua tenuitate atque imbecillitate ad seipsum ducit & rapit, cum non sit adeo ualens, nec tantum habeat ponderis & momenti ad expellendam aeris copiam, ut maiora corpora more Magnetis superare possit & uincere."
[138] PAGE 54, LINE 16. Page 54, line 18. _Gemma Vincentij rupis._--See the note to p. 48 _supra_, where the name _Vincentina_ occurs.
[139] PAGE 54, LINE 30. Page 54, line 35. _orobi._--The editions of 1628 and 1633 read _oribi_.
[140] PAGE 55, LINE 34. Page 55, line 42. _in euacuati._--The editions of 1628 and 1633 read _inevacuati_.
[141] PAGE 58, LINE 21. Page 58, line 25. _assurgentem vndam ... declinat ab F._--These words are wanting in the Stettin editions.
[142] PAGE 59, LINE 9. Page 59, line 9. _fluore._--This word is conjectured to be a misprint for _fluxu_ but it stands in all editions.
[143] PAGE 59, LINE 22. Page 59, line 25. _Ruunt ad electria._--This appears to be a slip for _electrica_, which is the reading of the editions of 1628 and 1633.
[144] PAGE 60, LINE 7. Page 60, line 9. _tan[=q] materiales radij._--The suggestion here of material _rays_ as the _modus operandi_ of electric forces seems to foreshadow the notion of electric lines of force.
[145] PAGE 60, LINE 10. Page 60, line 12. _Differentia inter magnetica & electrica._--Though Gilbert was the first systematically to explore the differences that exist between the magnetic attraction of iron and the electric attraction of all light substances, the point had not passed unheeded, for we find St. Augustine, in the _De Civitate Dei_, liber xxi., cap. 6, raising the question why the loadstone which attracts iron should refuse to move straws. The many analogies between electric and magnetic phenomena had led many experimenters to speculate on the possibility of some connexion between electricity and magnetism. See, for example, Tiberius Cavallo, _A Treatise on Magnetism_, London, 1787, p. 126. Also the three volumes of J. H. van Swinden, _Receuil de Mémoires sur l'Analogie de Electricité et du Magnétisme_, La Haye, 1784. Aepinus wrote a treatise on the subject, entitled _De Similitudine vis electricæ et magneticæ_ (Petropolis, 1758). This was, of course, long prior to the discovery, by Oersted, in 1820, of the real connexion between magnetism and the electric current.
[146] PAGE 60, LINE 25. Page 60, line 31. _Coitionem dicimus, non attractionem._--See the remarks, at the outset of these Notes, on Gilbert's definitions of words.
[147] PAGE 60, LINE 33. Page 61, line 1. _Orpheus in suis carminibus._--This passage is in the chapter [Greek: Lithika] of Orpheus, verses 301 to 327. See Note to p. 11, line 19.
[148] PAGE 61, LINE 15. Page 61, line 19. _Platonis in Timæo opinio_.--The passage runs (edition Didot, vol. ii., p. 240, or Stephanus, p. 80, C.):
[Greek: Kai dê kai ta tôn hudatôn panta rheumata eti de ta tôn keraunôn ptômata kai ta thaumazomena êlektrôn peri tês helxeôs kai tôn Hêrakleiôn lithôn, pantôn toutôn holkê men ouk estin oudeni pote, to de kenon einai mêden periôthein te hauta tauta eis allêla, to te diakrinomena kai sunkrinomena pros tên hautôn diameibomena hedran hekasta ienai panta, toutois tois pathêmasi pros allêla sumplechtheisi tethaumatourgêmena tôi kata tropon zêtounti phanêsetai.]
[149] PAGE 61, LINE 30. Page 61, line 38. The English version of the lines of Lucretius is from Busby's translation.
[150] PAGE 62, LINE 5. {45} Page 62, line 7. _Iohannes Costæus Laudensis._--Joannes Costa, of Lodi, edited Galen and Avicenna. He also wrote a _De universali stirpium Natura_ (Aug. Taurin., 1578).
[151] PAGE 63, LINE 3. Page 63, line 4. _Cornelius Gemma 10. Cosmocrit._--This refers to the work _De Naturæ Divinis Characterismis ... Libri ii. Avctore D. Corn. Gemma_ (Antv., 1575, lib. i., cap. vii., p. 123).
"Certè vt à magnete insensiles radij ferrum ad se attrahunt, ab echineide paruo pisciculo sistuntur plena nauigia, à catoblepa spiritu non homines solùm, sed & alta serpentum genera interimuntur, & saxa dehiscunt."
See also Kircher's _Magneticum Naturæ Regnum_ (Amsterodami, 1667, p. 172), Sectio iv., cap. iii., De Magnete Navium, quæ Remora seu Echeneis dicitur. See the note to p. 7, line 21.
[152] PAGE 63, LINE 6. Page 63, line 7. _Guilielmus Puteanus._--Puteanus (Du Puys) wrote a work _De Medicamentorum quomodocunque Purgantium Facultatibus_, Libri ii. (Lugd., 1552), in which he talks vaguely about the substantial "form" of the magnet, and quotes Aristotle and Galen.
[153] PAGE 63, LINE 21. Page 63, line 25. _Baptistæ Portæ._--The passage in the translation is quoted from the English version of 1658, pp. 191, 192.
[154] PAGE 64, LINE 4. Page 64, line 9. _Eruditè magis Scaliger._--Gilbert pokes fun at Scaliger, whose "erudite" guess (that the motion of iron to the magnet was that of the offspring toward the parent) is to be found in his book _De Subtilitate, ad Cardanum_, Exercitatio CII. (Lutetiæ, 1557, p. 156 _bis_).
[155] PAGE 64, LINE 7. Page 64, line 11. _Diuus Thomas._--On p. 3 Gilbert had already spoken of St. Thomas Aquinas as a man of intellect who would have added more about the magnet had he been more conversant with experiments. The passage here quoted is from the middle of Liber vii. of his commentaries on the _de Physica_ of Aristotle, _Expositio Diui Thome Aquinatis Doctoris Angelici super octo libros Physicorum Aristotelis_, etc. (Venice, Giunta edition, 1539, p. 96 _verso_, col. 2).
[156] PAGE 64, LINE 16. Page 64, line 24. _Cardinalis etiam Cusanus._--Cardinal de Cusa (Nicolas Khrypffs) wrote a set of dialogues on Statics, _Nicolai Cusani de staticis experimentis dialogus_ (1550), of which an English version appeared in London in 1650 with the title, _The Idiot in four books; the first and second of wisdom, the third of the minde, the fourth of statick experiments. By the famous and learned C. Cusanus._ In the fourth book _of statick Experiments, Or experiments of the Ballance_, occurs (p. 186) the following:
"_Orat._ Tell me, if thou hast any device whereby the vertues of stones may be weighed.
"_Id._ I thinke the vertue of the Load-stone might be weighed, if putting some Iron in one scale, and a Load-stone in the other, untill the ballance were even, then taking away the Load-stone, and some other thing of the same weight being put into the scale, the Load-stone were holden over the Iron, so that that scale wou'd begin to rise; by reason of the Load-stones attraction of the Iron, then take out some of the weight of the other scale, untill the scale wherein the iron is, doe sinke againe to the æquilibrium, or equality still holding the Load-stone unmovable as it was; I beleeve that by weight of what was taken out of the contrary scale, one might come proportionably to the weight of the vertue or power of the Load-stone. And in like manner, the vertue of a Diamond, might be found hereby, because {46} they say it hinders the Load-stone from drawing of Iron; and so other vertues of other stones, consideration, being alwayes had of the greatnesse of the bodyes, because in a greater body, there is a greater power and vertue."
In the 1588 edition of Baptista Porta's _Magiæ Naturalis Libri xx._, in lib. vii., cap. xviii., occurs the description of the use of the balance to which Gilbert refers.
[157] PAGE 67, LINE 21. Page 67, line 22. _aëris rigore._--All editions read thus, but the sense seems to require _frigore_.
[158] PAGE 67, LINE 27. Page 67, line 31. _Fracastorius._--See his _De Sympathia_, lib. i., cap. 5 (Giunta edition, 1574, p. 60).
[159] PAGE 68, LINE 5. Page 68, line 6. _Thaletis Milesij._--See the note to p. 11, line 26.
[160] PAGE 68, LINE 30. Page 68, line 35. _Ità coitio magnetica actus est magnetis, & ferri, non actio vnius._--See the introductory remarks to these notes. There is a passage in Scaliger's _De Subtilitate ad Cardanum_ (Exercitat. CII., cap. 5, p. 156 _op. citat._) which may be compared with Gilbert's for its use of Greek terms: "Nã cùm uita dicatur actus animæ, acceptus est abs te actus pro actione. Sed actus ille est [Greek: entelecheia], nõ autem [Greek: ergon]. At Magnetis attractio est [Greek: ergon], non aut[~e] [Greek: entelecheia]." To which Gilbert retorts: "non actio unius, utriusque [Greek: entelecheia]; non [Greek: ergon], [Greek: sunentelecheia] et conactus potius quam sympathia." He returns on p. 70 to the attack on Scaliger's metaphysical notions. There is a parallel passage in the _Epitome Naturalis Scientiæ_ of Daniel Sennert (Oxoniæ, 1664), in the chapter _De Motu_.
[161] PAGE 71, LINE 4. Page 71, line 8. _vt in 8. physicorum Themistius existimat._--See _Omnia Themistii Opera_ (Aldine edition, 1533, p. 63),