now indisputable; for it is clearly agreed, that the king, as pater patriæ, is universal guardian of all infants, idiots, and lunatics, who cannot take care of themselves, and as this care cannot be exercised otherwise than by appointing them proper curators or committees, it seems also agreed, that the king may, as he has done, delegate the authority to his chancellor: and that therefore at this day the Court of Chancery is the only proper court, that hath jurisdiction in appointing and removing guardiaus, and in preventing them and others from abusing their persons or estates. And as the Court of Chancery is now vested with this authority, hence in every day's practice we find that court determining, as to the right of guardianship, who is the next of kin, and who the most proper guardian; as also orders are made by that court on petition or motion, for the provision of infants during any dispute therein; as likewise guardians removed or compelled to give security; they and others punished for abuses committed on infants, and effectual care taken to prevent any abuses intended them in their persons or estates; all such wrongs and injuries being reckoned a contempt of that court, that hath, by an established jurisdisction, the protection of all persons under natural disabilities. All courts of justice appoint guardians to infants, to see and prosecute their rights in their respective courts, when the occasion calls for it.

There are also some cases where an infant may elect a guardian, and the Court of Chancery allows him to do so after four

teen.

GUARDIAN of the Spiritualties, is he to whom the spiritual jurisdiction of any diocese is committed, during the vacancy of the see. The archbishop is guardian of the spiritualties, on the vacancy of any see within his province; but when the archiepiscopal see is vacant, the dean and chapter of the archbishop's diocese are guardians of the spiritualties.

GUAREA, in botany, a genus of the Octandria Monogynia class and order. Natural order of Meliæ, Jussieu. Essential character: calyx four-cleft; petals four; nectary cylindric, bearing the anthers at its mouth; capsule four-celled, four-valved; seeds solitary. There is only one species, viz. G. trichilioides, ash-leaved guarea. This tree is remarkable for its strong odour of musk, particularly the bark, and is used instead of that perfume for many purposes. The wood is full of a bitter resinous subVOL. III.

stance, which renders it unfit for rum hogsheads, having been observed to communicate both its smell and taste to spirituous liquors. It is a native of South America and the West India islands. The English call it muskwood.

GUDGEONS, in a ship, are the eyes drove into the stern-post, into which the pintles of the rudder go, to hang it.

GUERICKE, Отто, or Отно, a very eminent German experimental philosopher in the seventeenth century, who, with Torricelli, Pascal, and Boyle, greatly contributed to explain the various properties of the air and their effects, was born in the year 1602, and died, at Hamburgh, in the year 1686. He was councellor to the Elector of Brandenburg; and burgomaster, or consul, of Magdeburg; but his memory derives greater honour from his philosophical discoveries, than from the civil dignities to which he was raised. To him is to be attributed the invention of the air-pump, for though Mr. Boyle had, about the same time, made some approaches towards a similar discovery, yet he ingenuously acknowledged in a letter to his nephew, Lord Dungarvon, that the information which he received from Schottus's "Mechanica Hydraulico Pneumatica," published in 1657, in which was an account of Guericke's experiments, first enabled him to bring his design to any thing like maturity. Guericke was also the inventor of the two brass hemispheres, to illustrate the pressure of the air, which, being applied to each other, and the air exhausted, resisted the force of sixteen horses to draw them asunder. He likewise invented an instrument to show the variations in the state of the atmosphere, consisting of a tube, in which was a little image of glass, that descended in rainy or stormy weather, and rose again when the weather became fine and serene. This last machine fell into disuse on the invention of the barometer, and especially after the improvements made in that instrument by Huygens and Amontons. By consulting his tube, Guericke would frequently foretel approaching storms; whence the ignorant populace gave him the character of a sorcerer. In this opinion of him they were confirmed by a thunder storm discharging itseif one day upon his house, and shivering to pieces several machines of which he had made use in his experiments. That event they considered to be an unequivocal indication of the anger of Heaven, and a just punishment inflicted Dd

upon him for his impiety. He was the author of several treatises in natural philosophy, the principal of which is entitled "Experimenta Magdeburgica,” 1672, folio, and contains his experiments on a vacuum. GUETTARDA, in botany, a genus of the Monoecia Heptandria class and order, Natural order of Tricoccæ. Rubiaceæ, Jussieu. Essential character: calyx cylindric; corolla six or seven-cleft, funnelshaped; pistil one; drupe dry. There are four species, natives of the East and West Indies.

GUGLIELMINI (DOMINIC), an eminent Italian mathematician and civil engineer, was descended from an honourable family, and born at Bologna in the year 1655. His favourite studies were the mathematics and medicine, in the former of which he had for tutor the celebrated M. Germ. Montanari; and in the latter, the illustrious Malpighi. He entered into the dispute between M. Montanari and M. Cavina, concerning the extraordinary luminous meteor, which was observed in most parts of Italy in 1676, and supported the opinions of his master. In the year 1678 he was admitted to the degree of doctor of medicine by the university of Bologna. Upon the appearance of the remarkable comet in the years 1680 and 1681, he published a treatise "De Cometarum Natura et Ortec," &c. 1681, in which he proposed a new system on the subject, which he thought would serve to explain all the phenomena of those heavenly bodies; but it did not meet with the approbation of the scientific world. His next astronomical treatise, containing remarks on the solar eclipse which took place on the 12th of July, 1684, and which he published in Latin, at Bologna, in the same year, reflected greater credit on his knowledge and accuracy of observation. Soon afterwards the senate of Bologna appointed him principal professor of mathematics in the university of that city, and, in the year 1686, created him intendant-general of the rivers of the Bolognese. The office last mentioned engaged him to pay more particular attention to the study of hydrostatics and hydraulics; in consequence of which, in the year 1690, he published the first part, and in the following year the second part, of an excel lent bydrostatical treatise, entitled " Aquarum Fluentium Mensura, Novo Methodo Inquisita." Some of his observations in this work were attacked by M. Papin, who also entered into a contest with the

author on the subject of Syphons. Their difference in opinion gave rise to two letters by Guglielmini, which were printed under the title of "Epistolæ Dux Hydrostaticæ." He was engaged in settling the differences which arose between the cities of Bologna and Ferrara respecting the management of the embankments and sluices in their contiguous districts; and received as a reward of his services, from his native city, the appointment to a new office in the university, which was that of professor of hydrometry. In the year 1695 he assisted M. Cassini in repairing the famous meridian line which he had constructed forty years before in the church of St. Petronius, at Bologna; on which occasion our author published a memoir, descriptive of the method pursued in laying it down, and establishing its claims to correctness and accuracy. In the year 1697 he published his grand physico-mathematical treatise on the nature of rivers, entitled "Della Natura de Fiumi," which raised his reputation to the highest pitch, for correct scientific knowledge, ingenuity, and judgment in hydraulics. Montucla commends it in warm terms, and says that it ought to be carefully studied by every person who would wish to become thoroughly master of this branch of science. The reputation which Guglielmini acquired by this performance, occasioned his being employed by the Dukes of Mantua, of Parma, and Modena, the Grand Duke of Tuscany, Pope Clement XI. the Republics of Venice and Lucca, &c. in the invention and construction of the necessary hydraulic works in their respective territories. In the year 1698 he was induced, by the Republic of Verice, to accept of the mathematical chair in the university of Padua; but the senate of Bologna decreed that he should still retain, notwithstanding his new employment, the title of professor in their university, and the emoluments annexed to it. In the year 1702, he exchanged his mathematical chair at Padua, for the more lucrative one of medicine; after which he published different treatises on medical and chemical subjects, &c. He died at Padua in 1710, in the fifty-fifth year of his age. He had been admitted a member of the Academy of Sciences at Paris; in the year 1696, and was also associate, or corresponding member of the Academies of Berlin and Vienna, and of the Royal Society at London. The best edition of his treatise on the nature of rivers, was published at Bologna in 1756,

with the notes of Manfredi; and the whole of his works were printed in a collective form at Geneva, in 1719, in two volumes quarto.

GUIAC. See RESIN.

GUIDE, in music, the name given to that note in a fugue which leads off and announces the subject.

GUILANDINA, in botany, bonduc or nicker-tree, a genus of the Decandria Monogynia class and order. Natural order of Lomentaceæ. Leguminosa, Jussieu. Essential character: calyx one-leafed; salvershaped; petals inserted into the neck of the calyx, nearly equal; seed vessel a legume. There are six species.

GUILD, or GILD, a fraternity or company. As to the original of these guilds or companies, it was a law among the Saxons that every freeman of fourteen years of age should find sureties to keep the peace, or be committed; upon which the neighbours entered into an association, and became bound for each other, either to produce him who committed any offence, or to make satisfaction to the injured party; in order to which they raised a sum among themselves, which they put into a common stock; out of which they, upon occasion, made a pecuniary compensation according to the quality of the offence committed. These guilds are now companies, joined together with laws and orders made by themselves, by the licence of the prince.

GUITAR. See MUSICAL instruments. GULES, in heraldry, signifies the colour red, which is expressed in engraving by perpendicular lines falling from the top of the escutcheon to the bottom.

GUM, a thick transparent tasteless fluid, which exudes occasionally from certain species of trees. It is adhesive, and gradually hardens without losing its transparency. Gum is chiefly obtained from different species of the mimosa, particularly from M. nilotica, a native of Egypt and Arabia, which is known by the name of gum arabic. The specific gravity of gum is about 1.4. It is not changed by exposure to the air, but is deprived of its colour by the action of the sun. By heat it becomes soft, and is speedily reduced to the state of charcoal, which enters largely into its composition. The constituent parts of gum are carbon, hydrogen, and oxygen, with smaller proportions of nitrogen and lime. The oxygen is much less in quantity than the saccharine matter. See SUGAR. The existence of lime and nitrogen in gum renders it essen

tially different from fecula and sugar, to which, in other respects, it bears a near relation; they, however, are able to undergo the vinous fermentation, which is not the case with gum. Gum readily dissolves in water, and the solution, which is thick and adhesive, is known by the name of mucilage. It is soluble also in the vegetable acids. Sulphuric acid decomposes it, and converts it into water, acetic acid, and charcoal. With the assistance of heat, muriatic acid, and nitric acid, produce a similar effect. It is insoluble in alcohol and ether. Such are the chief properties of gum arabic. There are, besides this, other gums, of which the principal is denomi nated tragacanth, from the astragalus tragacantha, a native of the island of Crete, which is in the form of vermicular masses; it is less transparent, and more adhesive than gum arabic, but by distillation it yields similar products. In our garden and or chards we find, in good quantities, gum exuding from the cherry and plumb trees, which differs chiefly from gum arabic in being softer and more soluble. Gum, in a state of mucilage, exists in a number of plants, especially in the roots and leaves. It is most abundant in bulbous roots, and of these the hyacinth seems to contain the largest quantity. A pound of the bulbs of this root, when dried, yields four ounces of a powder, which, when macerated in water, give a mucilage that acts well as a mordant for fixing the colours in calico-printing. Gum is used in medicine, and is considered as a specific against the stranguary occasioned by blisters; it constitutes, under particular forms, a nutritious food, and it is well known as an important article in the manufacture of our ink.

GUM resins, are certain substances that have long been used in medicine. They are all solid, generally brittle and opaque, have a strong smell, and a pungent and bitter taste. They consist chiefly of gum and resin, the proportions varying with the particular substance. They are never obtained by means of spontaneous exudation, but are procured by wounding the plants which contain them. The principal of the gum-resins are, 1. AMMONIAC, which see. 2. Assafoetida, obtained from the ferula assafoetida, a plant found in Persia. The gum resin is extracted from the roots by cutting off the extremities; a milky juice flows out, which is dried in the sun. It is brought to Europe in masses; its smell is very fetid, and its taste acrid. It is par

tially soluble in water and alcohol. 3. Enphorbium, obtained from the euphorbia officinalis, a native of Ethiopia, by making incisions in the plant. It is brought from Africa in the form of tears, is soluble in alcohol. It has no smell; after a time it communicates a burning taste to the tongue. It is regarded as poisonous. 4. GALBANUM, which see. 5. GAMBOGE, which see. 6. Myrrh, which is brought from the East Indies in the form of tears, is light, brittle, of a reddish colour, and has an unctuous feel; it is bitter and aromatic; it is soluble in water and alcohol in slight degrees. 7. Opoponax, obtained from the pastenaca opoponax, a perennial plant which grows wild in the south of Europe. This is extracted by wounding the stock or root, and is known here in the form of round drops or tears, or in irregular masses of a reddish colour. It is bitter and acrid to the taste, and with a peculiar smell. It forms a milky solution with water, and yields an essential oil by distillation. 8. Sapagenum supposed to be had from the ferula persica, and brought in large masses, or distinct tears, from Alexandria. It has a hot taste and disagreeable smell. It is moderately soluble in alcohol, but much more so in water. By distillation it yields a fœtid volatile oil. From some experiments made upon ipecacuanha, it is thought to contain a gum resin. All the gum resins that have been analysed have been found to contain ammonia.

GUN, a fire arm or weapon of offence, which forcibly discharges a ball, shot, or other offensive matter, through a cylindrical barrel, by means of gunpowder. Gan is a general name, under which are included divers, or even most species of fire arms. They may be divided into great and small.

Great guns, called also by the general name cannons, make what we also call ordnance or artillery; under which come the several sorts of cannon. See CANNON, ARTILLERY, &c.

GUN is also a name given to an instrument used by miners in cleaving rocks with gunpowder. It is an iron cylinder of an inch and a half thick, and about six inches long; and having a flat side to receive the side of a wedge; and a hole drilled through it to communicate with the inside of the hole in the rock this hole is made about eight inches deep, and in the bottom of it is put about two or three ounces of gunpowder: then this gun is driven forcibly in, so as to fill up the hole, and the wedges is driven in on its flat side to secure it. The priming

at the hole is then fired by a train, and the orifice being so well stopped by this gum, the force of the powder is determined to the circumadjacent parts of the rock, which it splits.

GUN room, in a ship, the apartment under the great cabin, where the master-gunner and his crew rendezvous, get ready their cartridges, &c. and do all things belonging to their business.

GUNDELIA, in botany, so called in honour of Dr. Andrew Gundelscheimer, who found this plant in his travels, in company with Tournefort, in the Levant; a genus of the Syngenesia Polygamia Segregata class and order. Natural order of Compositæ Capitatæ. Cinarocephala, Jussieu. Essential character: calyx scarcely any, fiveflowered; corolla tubular, male and bermaphrodite; receptacle chaffy; down none. There is but one species, viz. G. tournefortii, a milky plant, with alternate prickly leaves; flowers terminating. It is a native of the Levant.

GUNNER, an officer appointed for the service of the cannon; or one skilled to fire the guns. In the Tower of London, and other garrisons, as well as in the field, this officer carries a field staff, and a large powder horn in a string over his left shoulder; he marches by the guns, and when there is any apprehension of danger, his field staff is armed with match; his business is to lay the gun to pass, and to help to load and traverse her.

GUNNER of a ship, or master-gunner, has the charge of all the ordnance the ship carries, to see that they be serviceably mounted, and sufficiently supplied with spunges, ladles, and rammers; that in foul weather they be traversed within board, especially those of the lower tier, and that the ports be shut, and caulked up; and that at all times they may be well lashed, and made fast, lest any of them break loose, to the imminent danger of foundering the ship. In the time of an engagement, the gunner is to see that every piece be sufficiently manned; he is answerable to give an account of all his charge upon demand. He has a mate and quarter-gunners for his assistance.

GUNNER, master, a patent-officer of the ordnance, who is appointed to teach all such as learn the art of gunnery, and to certify to the master-general the ability of any person recommended to be one of the King's gunners. To every scholar he administers an oath, not to serve, without leave, any other prince or state; or teach any one

the art of gunnery, but such as have taken the said oath.

GUNNERA, in botany, so named in honour of J. E. Gunnerus, Bishop of Drontheim, in Norway, a genus of the Gynandria Diandria class and order. Natural order of Urtica, Jussieu. Essential character: ament with one-flowered scales; calyx and corolla none; germ two-toothed; styles two; seed one. There is but one species, viz. G. perpensa, marsh marygold-leaved gunnera. Native of the Cape.

GUNNERY, is the art of determining the course and directing the motion of bodies shot from artillery, or other warlike engines.

The great importance of this art is the reason it is distinguished from the doctrine of projectiles in general; for it is no more than an application of those laws which all bodies observe when cast into the air, to such as are put in motion by the explosion of guns or other engines of that sort. And it is the same thing whether it is treated in the manner of projectiles in general, or of such only as belong to gunnery; for from the moment the force is impressed, all distinction with regard to the power which put the body first in motion is lost, and it can only be considered as a simple projectile. See PROJECTILES.

Prob. I. The impetus of a ball, and the horizontal distance of an object aimed at, with its perpendicular height or depression, if thrown on ascents or descents, being given, to determine the direction of that ball.

From the point of projection A (Plate VI. Miscell. fig. 8, 9, 10, 11,) draw A m representing the horizontal distance, and B m the perpendicular height of the object aimed at bisect A m in H, and AH inf; on H and ƒ erect HT, ƒF perpendicular to the horizon, and bisecting A B the oblique distance or inclined plane in D, and AD in F. On A raise the impetus AM at right angles with the horizon, and bisect it perpendicularly in c, with the line GG. Let the line AC be normal to the plane of projection A B, and cutting G G in C; from Cas centre, with the radius CA, describe the circle AGM cutting if possible the line FS in S, s, points equally distant from G; lines drawn from A through S, s, will be the tangents or directions required.

Continue AS, As to T, t; bisect DT, Dt, in V, v; and draw lines from M to S, 8; then the angle AS F= angle MA S angle A Ms = angle s A F; and for the

same reason angle As Fangle M As == angle AMS = angle SAF; wherefore the triangles MAS, SAF, s A F are similar, and AM: As:: As: s Ft v; consequently AT is a tangent of the cnrve passing through the points A, v, and B; because tv v D, A D is an ordinate to the diameter TH, and where produced must meet the curve to B.

In horizontal cases (fig. 10.) v is the highest point of the curve, because the diameter Tv H is perpendicular to the họrizon.

When the mark can be hit with two directions (the triangles S A M, SAF being similar) the angle which the lowest direction makes with the plane of projection is equal to that which the highest makes with the perpendicular A M, or angle sAF = angle SAM. And the angle SAs, comprehended between the lines of direction, is equal to the angle S C G, and is measured by the arch S G.

When the points S, s coincide with G, or when the directions A S, As become A G; (fig. 11.) A B will be the greatest distance that can be reached with the same impetus on that plane; because SF coinciding with Gg the tangent of the circle at G, will cut off Ag a fourth part of the greatest amplitude on the plane A B. The rectangular triangle m A B, c A C are similar, because the angle of obliquity m A B

CAC; wherefore m Am B :: one-half impetus: c C; and m A: AB:: Ac: A C.

Horizontal Projections (ibid. fig. 10, 11.)

When the impetus is greater than half the amplitude, there are two directions, TAH, and tA H for that amplitude; when equal to it, only one; and when less, none at all; and conversely. For in the first case the line FS cuts the circle in two points S, s, in the second case it only touches it, and in the last it meets not with it at all; and conversely. When there is but one direction for the amplitude A m, the angle of elevation is 45°; and when the angle of elevation is of 45° Am is the greatest amplitude for that impetus, and equal to twice the impetus. The impetus remaining the same, the amplitudes are in proportion to one another as the signs of double the angles of elevation, and conversely. For drawing & N (fig. 10) parallel and equal to AF a fourth part of the amplitude, and supposing lines drawn from s to the points C and M, the angle A Cs = 2 AM 8 = 2s AF; therefore N s, the sine of ACs is