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tions, or from inattention thereto, many they will, instead of cohering, be obviously vessels, of which no tidings were ever heard, repelled to a distance corresponding with have been cast away; it being obvious that their respective powers of attraction, when a false indication of the northern point, in applied individually to unmagnetised nee. many places amounting to nearly the ex
dles. The south poles will, in like manner, tent of twenty-five degrees, must produce repel each other, but the north pole of one, so important an error in a vessel's course, and the south pole of the other, will, when as to subject her to destruction on those approximated, be evidently attracted, and very shoals, rocks, &c. which the navigator will cohere so as to sustain considerable unhappily thinks he steers wide of. To ob- weights. Iron is the only metal, hitherto viate such danger, as far as possible, all known, which is capable of receiving and modern sea-charts have the variations of communicating the magnetic power ; but the compass in their several parts duly quiet, and the absence of contact, in some noted down; and in reckoning upon the respects, are indispensably necessary to. course steered by compass, an allowance is wards its perfect retention. Thus, when a usually made for the difference between bar has been impregnated, however abunthe apparent course, by the compass, and dantly, with the magnetic principle, if it be the real course, as ascertained by celestial heated or hammered, the power of attracobservation. Under circumstances so com- tion will be dissipated; or if a tube filled pletely contradictory, the principle of mag. with iron filings have their surface magnenetism must remain unknown: we know tised, by shaking the tube the magnetic not of any hypothesis which strikes convic. influence will likewise be lost. In some tion on our minds, or which seems to con- respects the magnetic influence resembles vey any adequate idea of the origin, or mo- caloric; for it very rapidly communicates dus operandi, of this wondrous influence. to iron, devoid of magnetism, a certain por. All we can treat of is the effect; also of the tion of its own powers ; which, however, appearances which guide our practice, and appear to be reproduced instantaneously. of the manner in which the attractive power As various small fires under one large vessel may be generated and increased.
will thereby heat it, and cause the water it In regard to the latter point, namely, the contains to boil, though either of them generation and increase of the magnetic individually would not produce that effect; attraction, we shall endeavour to give a
so many weak magnets may, by causing brief but distinct view of what relates there- each to communicate a power equal to its to : observing that where volcanic eruptions own, be made to create an accumulated are frequent, and in those latitudes where power, larger than that contained by either the aurora borealis is distinctly seen, the of them individually: there is, however, a needle or magnet is sensibly affected. Pre. seeming contradiction to be found in some viously to earthquakes, as well as during their authors, who recommend that the weakest action, and while the northern lights are in magnets should be first applied, and those full lisplay, no reliance can be placed on more forcible in succession according to the the compass ; of which the card will appear power they may possess; the reason assignmuch agitated. This has given rise to the ed being, that the weaker magnets would opinion held by some, that the power is a else, in all probability, draw off some of fluid: to this, however, there appear so the accumulated power from the new magmany objections, that we are more disposed net. Of this there appears no danger, since to reject than to favour it, although under experience proves that magnets rather gain the necessity of confessing that we are not than lose efficiency by contact, not only able to offer one that may account satisfac. with each other, but even with common torily for the various phenomena attendant iron. In fact, the magnetic power may at upon magnetism.
any time be created by various means: the We have already stated, that every mag- friction of two pieces of flat and polished net has two poles; that is, one end is called bars of iron will cause them for a short the north, the other the south, pole: the while to attract, and to suspend, light former being considered as capable of at- weights. Soft iron is more easily influ. traction; the other, as we shall infer from enced, but steel will retain the influence the subjoined explanations, being far more longer. Lightning, electricity, and galva. inert, if at all possessed of an attractive nism, being all of the same nature, equally power. When two magnets are brought render iron magnetic. It is also peculiar, together with their north poles in contact, that when two or more magnets are left for any time with their several north poles in and within the influence of its pole, that contact, the whole will be thereby weak. needle also becomes magnetic; or, rather, ened; whereas, by leaving a piece of com- a conductor, possessing a certain portion of mon iron attached to a magnet, the latter attractive power : and it is no less extraorwill acquire strength. It is also well known dinary, that the magnet retains its power that some pieces of steel quickly receive even in the exhausted receiver of an airthe magnetic influence, while others require pump: this seems to be a formidable ob. considerable labour, and after all are jection to its being influenced by any fluid. scarcely impregnated. The oxide of iron Perhaps the opinion entertained by many cannot be impregnated, and those bars of our most popular lecturers on this subthat have been so, when they become par. ject, riz. that the earth itself is the great tially oxydized, lose their power. Hence attractor, may be nearest the truth. We we see the necessity of preserving the nee. are the more supposed to incline towards dles of compasses from rust.
such an hypothesis, knowing that, at the Magnets have the power to act notwith- true magnetic equator, the needle does standing the intervention of substances in not dip; and from the well ascertained any degree porous between them, and the fact, that bars of iron, placed for a length body to be acted npon: thus, if a needle of time exactly perpendicular, receive a be put on a sheet of paper, and a magnet strong magnetic power, their lower ends be drawn under it, the needle will follow repelling the south, but attracting the north the course of the magnet. The peculiar poles of magnets applied to them reaffinity of the load-stone for iron is em- spectively. The direction of the dipping ployed, with great success, by those who needle was ascertained by one Robert Nor. work in precious metals, for the separation man, about 250 years ago. He suspended of filings, &c. of iron from the smaller parti- a small magnetic needle, by means of a fine cles of gold, &c. A magnet being dipped thread around its centre, so as to balance into the vessel, in which the whole are perfectly, over a large magnet: the south blended, will attract all ferruginous parti- pole of the former was instantly attracted cles.
by the north pole of the latter. He found To communicate the magnetic power to that so long as the needle was held exactly a needle, let it be placed horizontally, and centrical, at about two inches above the with a magnet in each hand, let the north magnet, it remained horizontal; but so soon pole of one, and the south pole of the other as withdrawn a little more towards one end be brought, obliquely, in contact over the than the other of the magnet, the equilicentre of the needle ; draw them asunder, brium was destroyed, and that pole of the taking care to press tirmly, and preserving needle which was nearest to either pole of the same angle or inclination to the very
the magnet was instantly attracted, and ends of the needles, which shonld be sup- pointed downwards thereto. By the magported by two magnets, whose ends ought netic equator, we mean a circle passing to correspond in polarity with those of the round the earth at right angles with the needle. Observe to carry the magnets you magnetic poles, which do not correspond . press with clear away from the ends of the with the geographical' poles, as may be needle, at least a foot therefrom; repeat fully understood by the indications of all the friction in the same manner several compasses to points differing from the lat. times, perhaps six, eight, or ten times, and ter; and as the indications of compasses the needle will be permanently magnetized. vary so much both at different times and As we have already stated, by using other places, we may reasonably conclude, that magnets in succession, the powers of the the magnetic poles are not fixed. The varianeedle will be proportionably increased. tion of the dipping needle has not, in our But no effect will result from the friction latitude at least, varied more than half a if the bars are rusty, or, indeed, not highly degree since its depressive tendency was polished; their angles must be perfect, and first discovered by Norman. their several sides and ends completely The suspension of Mahomet's body, in flat.
the temple where it was deposited, is supIt is, perhaps, one of the most curious of posed to have resulted entirely from magthe phenoniena attendant upou this occult netism, with which the Arabians were comproperty, that the centre of every magnet pletely unacquainted. is devoid of attraction ; yet, that when a MAGNETISM, animal. About 30 years needle is placed in a line with a magnet, ago, Father Hehl of Vienna, imposed on his countrymen, and indeed on the greater under the same or equal angles, appear part of the civilized world, a pretended equal; and, rice versa. Mr. Maclaurin mode of curing all kinds of disease by observes, that geometrical magnitudes may means of a sympathetic affection between be usefully considered as generated or prothe sick person and the operator. The duced by motion. Thus, lines may be conremedy was supposed to depend upon the ceived as generated by the motion of points; motions of the fingers, and the features of surfaces, by the motion of lines; solids, by the latter ; he placing himself immediately the motion of surfaces; angles may be supbefore the invalid, whose eyes were to be posed to be generated by the rotation of fixed on his, and performing a number of their sides. Geometrical magnitude is alantic and ununeaning changes, accompanied ways understood to consist of parts; and to by various grimaces, or inflections of the have no parts, or to have no magnitude, are principal muscles of the visage. This rarely considered as equivalent in this science. failed to excite a certain degree of appre. There is, however, no necessity for consihension in the mind of the sick ; which, bydering magnitude as made up of an infinite creating a new action of the system, often number of small parts; it is sufficient that frightened them into convalescence. That no quantity can be supposed to be so small, such effects may have been produced among but it' may be conceived to be farther dithe credulous and timid, we shall not con- minished : and it is obvious, that we are trovert; but, on the other hand, it is assert. not to estimate the number of parts that ed that numbers have been so far overcome may be conceived in a given magnitude, by withi terror and fatigue, (for, like Dr. San- those which, in particular determinate cirgrado, the operator was never satisfied cumstances, may be actually perceived in it while any strength to undergo the process by sense, since a greater number of parts be. remained) that consequences highly danger- come sensible, by varying the circumstances ous, and in some instances fatal, were in- in which it is perceived. duced. Notwithstanding the obvious folly MAGNOLIA, in botany, so named in of the pursuit, there were found many gen- honour of Pierre Magnol, professor of metlemen of great respectability and talents dicine, and prefect of the botanic garden at among its followers ; hence a certain degree Montpelier, a genus of the Polyandria Po. of credit was established, and there were lygynia class and order. Natural order of not wanting persons foolish enough to cer- Coadunatæ. Magnoliæ, Jussieu. Essentify many cases, and to give a celebrity tial character: calyx three-leaved; petals which was in a very short time found to be nine: capsule one-celled, two-valved; seeds misapplied. It is a lamentable case, that, berried, pendulous. There are seven spethroughout the world, impositions of this cies; of which M. grandiflora, great laurelnature are always tolerated long enough to leaved magnolia, or tulip tree, in the south, answer the purposes of the fabricator, and
ern provinces of North America, grows to to encourage others in similar deceptions. the lieight of eighty feet: the trunk is more Our readers may recollect many instances than two feet in diameter; the leaves are of notorious character, among which the nine or ten inches long, and three broad in metallic tractors, which were at one time the middle, of a thick consistence, resemb. asserted to be allied to metallic-magnetism, ling those of the common laurel, but much may, perbaps, serve as a proper illustration larger ; of a lucid green, sessile, and placed and proof.
without order on every side of the branches; MAGNIFYING, in philosophy, the mak- continuing green all the year, falling off ing of objects appear larger than they would only as the branches extend, and the new otherwise do; whence convex lenses, which leaves are produced. The flowers come have the power of doing this, are called out at the ends of the branches: they are magnifying glasses ; and of such glasses are large, and composed of eight or ten petals, microscopes constructed.
which are narrow at the base, broad, roundMAGNITUDE, whatever is made up of ed, and a little waved at their extremities; parts locally extended, or that hath several they are of a pure white colour, possessing dimensions; as a line, surface, solid. The an agreeable scent. The summers in Eng. apparent magnitude of a body is that mea- land are not warm enough to bring the fruit sured by the visual angle, formed by rays to perfection. This fine tree is a native of drawn from its extremes to the centre of Florida and Carolina, and, in common with He eve; so that whatever things are seen many of the trees and plants of that country, is impatient of cold here, and difficult soils, near the sea coast. The superior va“ to keep in perfection, either abroad or Ine of the Jamaica wood, for beauty of cohoused.
louring, firmness, and durability, may there. MAHERNIA, in botany, a genus of the fore be easily accounted for; and a large Pentandria Pentagynia class and order quantity of balks and planks is brought Natural order of Columniferæ. Tiliaceæ, from the Spanish American coasts to JaJussieu. Essential character: calyx five. maica, to be shipped from thence to Great tvothed; petals five; nectaries five, obcor- Britain. This wood is generally hard, takes date, placed under the filaments; capsule a fine polish, and is found to answer better five-celled. There are three species, na- than any other sort in all kinds of cabinet tives of the Cape of Good Hope.
It is a very strong timber, and was MAHOGANY. The swietenia mahago- frequently nsed as such in Jamaica in former ni, or mahogany tree, is a native of the times. It is said to be used sometimes in warmest parts of America, and grows also ship-building; a purpose for which it would in the island of Cuba, Jamaica, Hispaniola, be remarkably adapted, if not too costly; and the Bahama islands. It abounded for being very durable, capable of resisting merly in the low lands of Jamaica; but it is gun-shots, and burying the shots without now found only on bills, and places difficult splintering. of access. This tree grows tall and straight, MAHOMETANS, believers in the docrising often sixty feet from the spur to the trines and divine mission of Mahomet, the limbs; and is about four feet in diameter. celébrated warrior and pseudo-prophet of The foliage is a beautiful deep green, and Arabia, who was born at Mecca in the year the appearance made by the whole tree 571. The father of Mahomet was Abdolvery elegant. The flowers are of a reddish lech, descended from the Korashites, tribes or saffron colour, and the fruit of an oval who had long enjoyed the regal dignity in form, about the size of a turkey's egg. Arabia. Notwithstanding the royal descent Some of them have reached to a monstrous of the prophet, it appears that a variety of size, exceeding one hundred feet in height. adverse circumstances concurred to render In felling these trees, the most beautiful him, in the early part of his life, indigent part is commonly left behind. The negro and obscure. His father died before he workmen raise a scaffolding of four or five was two years of age, and his mother when feet elevation from the ground, and back he was about eight; so that he was left in a up the trunk, which they cut into balks, manner destitute of subsistence, and his The part below, extending to the root, is education in a great measure, if not altogenot only of larger diameter, but of a closer ther, neglected. After the death of his texture than the other parts, most elegantly mother, he was committed to the care of diversified with shades or clonds, or dotted his grandfather, who dying within a year like ermine with spots : it takes the highest afterwards, he was taken under the protecpolish, with a singular lustre. This part is tion of his uncle Taleb, a merchant of some only to be come at by digging below the respectability. There are various accounts spur, to the depth of two or three feet, and relative to the manner in which Mahomet cutting it through ; which is so laborious an first began to invent and propagate his new operation, that few attempt it, except they system of faith and worship. It appears, are curious in the choice of their wood, or according to the Mahometan historians, that to serve a particular purpose. The mahogany his pretended mission was revealed to him tree thrives in most soils ; but varies in in a dream, in the fortieth year of his age. texture and grain, according to the nature From that time, say his biographers, Mahoof the soil. On rocks it is of a smaller size; met, under the influence of a holy terror, but very hard and weighty, and of a close devoted himself to a solitary life. He regrain, and beautifully shaded; while the tired to a grotto in the mountain of Hira, produce of the low and richer lands is ob- which overlooks Mecca. He there passed served to be more light and porous, of a his days and nights in fasting, prayer, and paler colour, and open grain; and that of meditation. In the midst of one of these mixed soils to hold a medium between both. profound ecstasies, tie angel Gabriel apThis constitutes the difference between the peared to him, with the first chapter of the Jamaica wood and that which is collected Koran, and commanded him to read. Mafrom the coast of Cuba and the Spanish homet replied, he was unable; upon which Main; the former is mostly found on rocky the angel repeatedly embraced him, and eminences; the latter is cat in swampy commanded bim to read in the name of his Creator. A few days after, praying upon by the holy fire of fanaticism, success the same mountain of Hira, Mahomet again attended almost all their engagements, saw the angel of the Lord, sealed in the Mahomet, thus elevated, formed the stumidst of the clouds on a glittering throne, pendous design of creating a new empire. with the second chapter of the Koran ; and Here again success crowned his efforts. was addressed by him in the following His plan was executed with such intrepiwords: “O thou who art covered with a dity, that he died, A. D. 632, master of all celestial mantle, arise and preach!" Thus Arabia, besides several adjacent provinces. the angel Gabriel communicated, by com- It is not our business, nor will our limits mand of the Eternal, to his prophet, in the admit of it, to account for the rapid progress twenty-three last years of his life, the whole of the Mahometan faith. We may, howbook of the Koran, leaf by leaf, chapter by ever, summarily state, as causes of the chapter. There are, however, different ac- eastern prophet's success: the terror of bis counts respecting the portions or parcels in arms; the artful nature of his law, which which the Koran was given to Mabomet. offered such rewards to the faithful, and See ALCORAN.
such punishments to the infidels, as were During the first thirteen years of the best suited to the luxuriant faucies of the prophet's mission he appears to have made Arabians; the plainness and simplicity of very slow progress; but the last ten were some of his doctrines; the adaptation of employed with greater success. Finding the duties which bis law enjoined to the that visions, ecstasies, revelations, and arga- passions and appetites of mankind; the proments did not succeed so rapidly as he found ignorance under which the Arabians, could have wished in making proselytes, he Syrians, Persians, and the greatest part of determined to try the more powerful and the eastern nations, then laboured; and, adventurous inducements of coercion. Af- lastly, the dissentions and animosities that ter his flight from Mecca to Medina, which then ravaged the peace, and destroyed the took place A. D. 622, and from which his union of the Christian sects, particularly the followers compute their time, the prophet Greeks, Nestorians, Eutychians, and Monomade rapid progress. Thousands flocked physites, and which rendered the very name to his standard, and he soon convinced his of Christianity odious to many. These are enemies, that if tliey refused to admit the some of the causes which gave life and divinity of his mission, they should feel the strength to the Mahometan religion in the weight of his arm. He declared, that God east. sent him into the world not only to teach The religion of Mahomet is divided into his will, but to compel mankind to en. two general parts : faith and practice. The brace it. “ The word,” said he, “is the fundamental article of the Maliometan creed key of heaven and he!); a drop of is contained in this confession : THERE is blood shed in the cause of God, or a night BUT ONE GOD, AND MAHOMET IS HIS spent in arms, is of more avail than two PROPHET. Under these two propositions months of fasting and prayer. Whosoever are comprehended six distinct branches : falls in battle, his sins are forgiven at the viz. belief in God; in his angels; in his day of judgment; his wounds sliall be re- scriptures ; in his prophets; in the resursplendant as vermilion, and odoriferous as rection and judgment; and in God's absomusk, the loss of his limbs shall be supplied lute decrees, or predestination. They by the wings of angels and cherubim." Who reckon five points relating to practice ; viz. would not die to be acquitted at the bar of prayer with washings, &c.; alms; fasting ; heaven? Who would not prefer a night in pilgrimage to Mecca; and circumcision. arms to a fast of two months? And what Mahomet admitted the divine mission of mortal but would prefer the odours of musk both Moses and of Jesus Christ. Dr. Jortin to the stench of plaisters or fætid ointmenis; says, that Mahometism is a borrowed systhe wings of angels to the cumbroùs appen- tem, made up for the most part of Judaism dages of human limbs? These representa. and Christianity; and if it be considered, tions were attended with the desired effect the same writer observes, in the most faon the minds and conduct of the prophet's vourable point of view, might possibly be admirers. They assembled in nambers to accounted a sort of Christian heresy. Achfight for God and his prophet. Headed by met Benabdalla, in his letter to Maurice, a chieftain of invincible courage, attractive Prince of Orange, says, “The Lord Jesus eloqnence, and astonishing genius, guarded Christ is held by us (Mahometans) to be a by angels (as they supposed), and enflamed prophet, and the messenger of God, and our