Page:Cyclopaedia, Chambers - Volume 2.djvu/129

 MAG

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MAG

the 49 firft Numbers of the Natural Progreffion. But as we have already obferved, that a Primitive Square of 7 Numbers repeated may have above 20160 feveral Con- structions, the Number 4064.2 5600 mull come valtly iliort of exprelfing all the poflible Constructions of a perfect 2,lagic Square of the 49 firft Numbers.

As to the Even Squares, he conftructs them like the Uneven ones, by two Primitive Squares ; but the Con- ftruction of Primitives is different in the general, and may be fo a great number of ways : and thofe general Diffe- rences admit of a great number of particular Variations, which give as many different Conllructions for the fame even Square. It fcarce feems poflible to determine ex- telly, either how many general Differences there may be between the Construction of the primitive Squares of an even Square and an uneven one ; nor how many particular Variations each general Difference may admit of ; and of confequence we are ftill far from being able to determine the Number of different Conllructions of all thofe that may be. made by the Primitive Squares.

MAGISTER, Mafler, a Title frequently found in old Writings. It noted; the Perfon who bore it had attained fome Degree of Eminency in Scientia aliquaprafertim Lite- raria ; and in old Times thofe we now call DoBors, were called Magiftri.

MAGISTERY, a Term in Chymillry fignifying a Pre- cipitate of fome Diffolution 5 made by a Salt, or fome other Body,which breaks the Force of the Diffolvent. Thus we fay, Ma&Jtery of Bijmuth, which is a very fine Powder made by diffolving the Bifmuth in Spirit of Nitre, and pour- ing on it Salt Water, which precipitates the Magijtery to the bottom. See Bifmuth. Magijiery of Lead is a fine Powder, made by diffolving Saccharum Sautrni in diftill'd Vinegar, and then precipitating it with Oil of Tartar fer Deliquium. The word Magijiery is alfo ufed in fpeaking of Refins, Re- finous Extracts of Scammony, Jalap, Turpeth, t£c. which are made by diffolving the Matter in Spirit of Wine, and precipitating it with Water. Mr. Boyle takes the proper Notion of a Magijiery to confift in a Preparation of a Body, whereby it is wholly, or at leaft in great meafure, by means of fome extraneous Additament converted into a Body of a different kind ; as when Iron or Copper is turned into Chryflals of Mars and Vents.

MAGMA, among Chymifls, l£c. the Dregs or Refi- duum afterlnfufion or Distillation.

MAGNA AR1ER1A, the fame with the Aorta, which

fee.

MAGNA CHARTA, the Great Charter, granted the ninth Year of Henry the Third, and confirmed by Edward the Firft. The Rcafon why it is fo term'd, is either be- caufe of the Excellency of the Laws and Liberties there- in contained, or elfe becaufe there was another Charter, call'd Charta de Forejia, eitabliiti'd with it, which was the lefs of the two ; or becaufe it contained more than any other Charters ; or more than that of K. Henry the Firft ; or in regard of the Wars and Troubles in the obtaining of it; or of the great and remarkable Solemnity in the de- nouncing Excommunications againft the Infringers of it. Holinfi-ed indeed tells us, that King John, to appeafe the Barons, yielded to Laws or Articles of Government much like to 'this great Charter ; but we have now no antienter Law written than this ; which was thought to be fo bene- ficial to the Subjefl, and a Law of fo great Equity, in comparifon of thofe which ivere formerly in ule, that KineWy, for the granting it, had the fifteenth Penny of all the moveable Goods, both of Temporality and Spirituality. Sir Edw. Coke fays, it has been above thirty times confirmed. It is recorded, that when Henry III. confirm'd it, he fwore on the word and Faith of a King, a Chriftian, and a Knight, to obferveit. SctCbarta Magna.

MAGNES ARSENICAL, in Chymiftry, a Mixture of equal Parts of Arfenic, Sulphur, and Antimony melted together over the Fire, and condenfed in manner of a Stone. It is a very gentle Cauftic, and was firft invented by Anielus Sola. It has its Name Magnet, becaufe being wore during Malignant Difeafes, it is fuppofed to preferve the Wearer from Infection by a Magnetical Power.

MAGNET, or Loadftonc, a Mineral Stone, or rather a Metal, or an imperfect Iron ; in Weight and Colour refembli'ng Iron Ore, tho fomewhat harder and more heavy. It is ufually found in Iron Mines, and fometimes in very large pieces, half Magnet, half Iron. Its Colour is different, according to the different Countries it is brought from. Norman obferves, that the beft are thofe brought from China and Bengal, which are of an Iron or Sanouine Colour ; thofe of Arabia are redd.fti, thofe of Macedonia blackifh ; and thofe of Hungary, Germany, Eng- land, &c. the Colour of unwroughr Iron. Neither its Fi- gure nor Bulk are determined, but it is found of all Forms and Sizes. ,.,,,. j-rr

The Antients reckon'd five kinds of Magnets, different in Colour and Virtue : the Ethiofic, Magnefian, Exotic,

Alexandrian, and Natolian. They alfo took it to be Male and Female : but the chief Ufe they made of it was in Medicine ; efpecially for the Cure of Burns, and De- fluxions on the Eyes : the Moderns, more happy, take it to conduct 'em in their Voyages.

The moft diftinguifhing Properties of this wonderful Body, are, That it attracts Iron, arid that it points to the Poles of the World ; and in other Circumftances alfo dips or inclines to a Point beneath the Horizon, directly under the Pole ; and that it communicates thefe Properties by Touch, to Iron. On which Foundation are built the Mariners Needles 5 both Horizontal, and Inclinatory, or Dipping Needles. See Needle.

The AttraBive Power of the Magnet was known to the Antients, and is mention'd even by Plato and Euripides ; who call it the Herculean Stone ; becaufe it commands Iron, which fubdues every thing elfe : But the Knowledge of its Directive Power, whereby it difpofes its Poles along the Meridian of every Place, and occafions Needles, Pieces of Iron, tjje. touch'd with it, to point nearly North and South, is of a much later date ; tho the exact Time of its Difcovery, and the Difcoverer himfelf, are yet in the dark. The firft tidings we hear of it, is in 1260, when Paulus Venetus is faid by fome to have firft introduced the Mariners Compafs ; tho not as an Invention of his own, but as derived from the Cbinefe, who are -laid to have had the Ufe of it long before: but others, and with good rea- fon, think that the Chinefe rather borrow'd it from the Europeans. John de Goia, a Neapolitan, who lived in the 13th Century, is the Perfon ufually fuppofed to have the beft Title to the Difcovery : And yet Sir G. Wheeler men- tions, that he had feen a Book of Aftronomy much older, which fuppofed the Ufe of the Needle; tho not as applied to the Ufes of Navigation, but of Aftronomy. And in Guyot de Provins, an old French Poet, who wrote about the Year 1 180, there is exprefs mention made of the Load- ftone and the Compafs ; and their Ufe in Navigation ob- liquely hinted at. See Compafs.

The Variation of the Needle, or its Declination from the Pole, was firft difcovered by Seb.Calior, a Venetian, in 1500; and the Variation of that Variation by Mr.Gelli- hrand, anEnglifiman, about jrhe Year 1625. Latily, The Dip or Inclination of the Needle, when at liberty to play vertically, to a Point beneath the Horizon, was firft difcover'd by another of our Countrymen, Mr. R. Norman,, about the Year 1576. See Needle.

Some of the Phenomena of the Magnet are as follow. ( l .) In every Magnet there are two Poles, the one whereof points Northward, the other Southward ; and if the Magnet be divided into ever fo many pieces, the two Poles will be found in each piece. (2.) Thefe Poles in diffe- rent parts of the Globe, are differently inclined to- wards a Point under the Horizon. (3.) Thefe Poles, tho contrary to one another, do help mutually towards the Magnet's Attraction and Sufpenfion of Iron. (4.) If two Magnets are Spherical, one will turn or conform itfelf to the other, fo as either of them would do to the Earth 5 and after they have fo conformed or turned them- felves, they endeavour to approach or join each other ; but if placed in a contrary Pofition, they avoid each other. (5.) If a Magnet be cut thro the Axis, the Parts or Segments of the Stone, which before were joined, will now avoid and fly each other. (6.) K" J he Magnet be cur by a Section perpendicular to its Axis, the two Points, which before were conjoined, will become contrary Poles ; one in one, the other in the other Segment. (7.) Iron receives Virtue from the Magnet by application to it, or barely from an approach near ir, tho it doth not touch it ; and the Iron receives this Virtue varioufly, according to the Parts of the Stone it is made to touch, or made approach to. (8.) If an oblong Piece of Iron be any how applied to the Stone, it receives Virtue from ir, only as to its length. (9.) The Magnet lofeth none of its own Vir- tue by communicating any to the Iron ; and this Virtue it can communicate to the Iron very fpeedily ; tho the lon- ger the Iron touches or joins the Stone, the longer will its communicated Virtue hold ; and a better Magnet will com- municate more of it, and fooner, than one not fo good. (10.) Steel receives Virtue from the Magnet, better than Iron. (11.) A Needle touch'd by zMagnet will turn its Ends the fame way towards the Poles of the World, as the Magnet will do it. (12.) Neither Loadftone nor Needles touch'd by it do conform their Poles exactly to thofe of the World, but have ufually fome Variation from them : And this Variation is different in divers pla- ces, and at divers times in the fame place. (15.) A Loadftone will take up much more Iron when arm'd or capp'd than it can alene : And tho an Iron Ring or Key be fufpended by the Loadftone, yet the Magnetical Particles do not hinder that Ring or Key from turning round any way, either to the right or left. (14.) The Force of a Loadftone mav be varioufly increas'd or

leffen'd