requisite for service in the vanguard, it is customary to choose for this purpose the most active troops in the army, and to give them an experienced leader. This captain must know how to conduct skirmishes, and to direct all his movements conformably to the object of the advancing army. The vanguard are often employed in improving the roads, where they are impassable, in procuring provisions, in spreading reports, &c.; and it is always their duty to collect authentic information. VANINI, Lucilio, or, as he afterwards styled himself, Julius Cæsar, a learned Italian of the school of Pomponatius, was born at Tauresano, in the kingdom of Naples, in 1585, and early devoted himself with ardor to letters, studying philosophy, theology, law and astrology at Rome and Padua. He took orders, and began to preach, but soon abandoned his clerical duties for study. He may be considered in some sort as a polyhistor; at least he made pretensions to that character. Having travelled in Germany, Bohemia and the Netherlands, he resided some time at Geneva and Lyons, where he occupied himself with instruction, but was finally obliged to flee to England, and in that country was thrown into prison. Wherever he had appeared, he had become obnoxious to suspicions, on account of his peculiar religious views. Returning to Lyons, after his release from prison, he published his Amphitheatrum Eterna Providentia (1615), which appears to have been directed against Cardan (q. v.) and others of his way of thinking, but which drew upon Vanini himself the suspicion of atheistical notions, and compelled him to quit Lyons. Retiring to Paris, he here published his De admirandis Naturæ, Reginæ, Deaque Mortalium Arcanis (1616), in sixty dialogues, which is more of a physical than a theological treatise. Although published with the permission of the theological faculty of Sorbonne, it subjected Vanini anew to the charge of atheism. In 1617, he went to Toulouse, where he was accused of atheism and sorcery, and condemned to the flames. He was drawn to the place of execution, and, after his tongue had been torn out, was strangled and burnt, at the age of thirty-four years. His death has given Vanini more celebrity than his writings would have procured him. His punishment was entirely undeserved, as there is no ground for the accusation brought against him; but he appears to have created enemies by his imprudent conduct, his vanity, and his satirical spirit. Voltaire and Bayle have

defended him; and a German work, Vanini's Life and Fate, Spirit, Character and Opinions (Leipsic, 1800), contains an account of wha, has been written for and against him.

VANLOO; the name of a distinguished family of artists, which originated in Ecluse, in Flanders. Two members of this family have contributed most to its fame. They were the sons of Louis Vanloo, known as a fresco painter.—The eldest of the two, John Baptist, born at Aix, in 1684, a portrait and historical painter, lived in France, Italy and England. He died in 1745. His historical paintings are chiefly in Paris, Toulon, Turin, Rome and London.-The second, Charles Andrew, was born at Nizza, in 1705, painted landscapes and historical subjects, became, in 1735, a member of the academy of arts in Paris, and died in 1765. His pictures have mostly remained in France.-John Baptist had four sons, who all became skilful artists, though the two youngest, Claudius and Francis, died young; the eldest, Charles Andrew Philip, became painter to the court of Berlin, and Louis Michael to the king of Spain.

VANNUCCHI; the proper name of Andrea del Sarto. (See Sarto.)

VANSITTART, Nicholas, lord Bexley, born in 1766, is the youngest son of Henry Vansittart, governor of Bengal, and was educated at Christ-church, Oxford. He afterwards studied the law, and was called to the bar in 1792. In 1796, he was elected member of parliament for Hastings, in Sussex, and in the next parliament sat for Old Sarum. Mr. Vansittart spoke occasionally in the house, and made himself known to the public by several pamphlets, which he published at that period:-Reflections on the Propriety of an immediate Peace (1793); Letters to Mr. Pitt on the Conduct of the Bank Directors (1795); and an Inquiry into the State of the Finances of Great Britain (1796). In February, 1801, he was sent on a special mission to Copenhagen, and in April he was made secretary to the treasury. In 1805, he resigned that place, and was appointed chief secretary of Ireland, which place also he gave up in the same year. In 1806, under lord Grenville's administration, he was again appointed secretary to the treasury, and was elected member of parliament for Helstone, in Cornwall, and quitted place when the Grenville administration went out. In 1811, he published Two Speeches on the Report of the Bullion Committee. On the assassination of Mr. Percival, Mr. Van

sittart was made choice of by lord Liverpool to be his chancellor of the exchequer, in which office he continued till 1823, when he was succeeded by Mr. Robinson (see Goderich), and created chancellor of the duchy of Lancaster, with a peerage. He retained this post under Canning and Goderich, but, in 1828, gave way to the Wellington ministry.

VANUCCI. (See Perugino.)
VAPOR. (See Evaporation.)

VAPOR BATH. The vapor or steam bath may be regarded as a modification of the hot bath; but its effects are much less violent. The most usual mode of employing it is to expose the naked body in a room, into which the steam of hot water may be admitted. This room is generally heated to a temperature considerably above that of the atmosphere, and the body is suffered to remain for some time in this heated air, the common effect of which is, to increase its temperature, and to accelerate the circulation of the blood. After some time, the steam is admitted, when the former symptoms are removed, and a profuse perspiration is produced. This is usually promoted by friction, and removal to a warm bed. The general effect of this process is to relax the boby, remove obstructions of the skin, alleviate pain and spasmodic contractions, and promote sleep. In the vapor bath, the stimulant power of heat is modified and tempered by the moisture diffused through the air; and, as the elastic vapor, like air, is a less powerful conductor of heat than a watery fluid, the effect of vapor in raising the temperature of the body is much less than that of the hot bath. Its heating effect is also further diminished by the copious perspiration that ensues; so that, on all accounts, the vapor bath is safer, and, in most cases, more effectual, than the hot water bath. (See Bath.)

VAPORS. (See Hysterics.)
VAR. (See Departments.)

VARANGIANS, or VARAGIANS (i. e. hunters, or corsairs); a Scandinavian race, who seem to have received this name in Russia, where they established several principalities. Some of them afterwards entered the service of the Byzantine emperors, and performed the duty of imperial guards at Constantinople. Here they were recruited, according to the Byzantine writers, by bands of their countrymen from Thule; i. e. by Saxons and Danes, who fled from England to escape the Norman yoke. They continued to speak the Saxon or Danish language till

the overthrow of the empire. The peculiar weapon of these Varangian guards, to whom the keys of the palace and the capital were entrusted, was the two-edged battle-axe.

VARCHI, Benedetto, an eminent man of letters, born at Florence, in 1502, was educated at the university of Padua, where he made a great progress in the belles-lettres, but was designed for the law, which he studied during the life of his father, and was even admitted a notary. When the decease of his parents left him at liberty to pursue his own inclinations, he forsook the law, and devoted himself entirely to literature. He accordingly studied the Greek language and philosophy, until driven from Florence by his attachment to the Strozzi: he then returned to Padua, where he read public lectures on morals and literature. The grand duke of Tuscany, Cosmo I, invited him back to Florence, although he had opposed the Medici, and assigned to him the office of writing a history of the late revolution. Whilst thus employed, he was attacked, at night, by some persons who feared that his strictures might be unfavorable to them, and stabbed in several places. He, however, recovered, and had either the prudence or the lenity not to name the parties, although he knew them. He was carried off by an apoplexy, in 1565, at the age of sixty-three. Varchi was a man of indefatigable industry, and there is scarcely a branch of literature which he did not cultivate. His Storia Fiorentina, comprising only the period of eleven years, is very voluminous, and written in a diffuse, languid manner. It is also charged with adulation to the house of Medici. Varchi likewise wrote poems and a comedy, and, as a grammarian, obtained reputation by his dialogue entitled L'Ercolano, on the Tuscan language. His Lezioni lette nella Academia Fiorentina display a multifarious erudition.

VARENNES; a petty town in the northeast of France, one hundred and fifty miles north-east of Paris, and eighteen north-west of Verdun. It has about 1300 inhabitants, with manufactures of leather and paper; but is chiefly remarkable as the place where Louis XVI was stopped in his imprudent flight from Paris, in June, 1791. (See Louis XVI.)

VARIABLE QUANTITIES, in geometry and analytics, denote such as are either continually increasing or diminishing, in opposition to those which are constant, remaining always the same. Thus the

abscisses and ordinates of an ellipsis, or other curve line, are variable quantities, because they vary or change their magnitudes together. Some quantities may be variable by themselves alone, while those connected with them are constant; as the abscisses of a parallelogram, whose ordinates may be considered as all equal, and therefore constant. The diameter of a circle, and the parameter of a conic section, are constant, while their abscisses are variable. Variable quantities are usually denoted by the last letters of the alphabet, z, y, x, while the constant ones are denoted by the first letters, a, b, c. VARIATION, in music, is the different manner of singing or playing the same air, tune or song, either by subdividing the notes into several others of less value, or by adding graces, in such a manner, however, that the tune itself may still be discovered, through all its embellishments. These repetitions or variations were formerly called doubles. Mozart's variations for the piano, and those of Rode for the violin, are particularly excellent. Generally speaking, variations are more suited to instrumental than vocal music. The latter sort are chiefly intended for practice, or to show the splendid talents of the singer; e. g. those sung by madame Catalani. (q. v.) There are also variations in poetry, called glosses, used in Spanish and Portuguese poetry. (See Gloss.)

VARIATION OF CURVATURE, in geometry, is used for that inequality or change which happens in the curvature of all curves except the circle; and this variation, or inequality, constitutes the quality of the curvature of any line.

VARIATION OF THE MAGNETIC NEEDLE. (See Magnetism.)

VARIATIONS, CALCULUS OF; that branch of the differential calculus (see Calculus) in which the mathematician ascends from the theory of the maximum and minimum to the more important and difficult investigation of that curve, or those, among all possible curves, to which belong certain given qualities in the highest or lowest degree. If, for instance, the question is, to find the brachystochrones (i. e. those among all curves of equal length, which a body, moved by given powers, passes through in the shortest time), the analytical answer to this and similar questions leads to the calculus of variations, which, therefore, appears as an extended theory of the maximum and minimum, and, instead of confining itself to differentiation, rather requires us to deduce from a derived equation already found

the primitive one possessing the required quality. The method of variations, which owes its origin to John Bernoulli's proposing the above-mentioned problem of the brachystochrones, in 1693, crowns the admirable fabric of modern geometry. See Dicksen's Analytische Darstellung der Variationsrechnung (Berlin, 1826, 4to.).

VARIATIONS OF THE MOON; inequalities in the revolution of the moon, known only since the time of Tycho Brahe.

VARIETY, in natural history, a subdivision of a species, as a species is a subdivision of a genus. What one naturalist considers a variety, another sometimes considers a distinct species. Most of the various kinds of dogs are varieties which can be reduced to a few species. A variety cannot be preserved without much care left to nature, it returns, in a succession of generations, to the species.

VARIORUM, CUM NOTIS. Certain editions of ancient and modern Latin and Greek authors, published mostly in Holland, in the seventeenth and eighteen centuries, and containing the notes of many commentators, are termed editiones cum notis variorum. These editions do not stand in very high estimation with scholars, but are, nevertheless, sought for by collectors. The number is given differently by bibliographers, accordingly as they enumerate more or fewer new cditions of this kind published out of Holland.

VARIOUS READINGS (lectiones variantes, lectiones variæ) are differences in the text of a work, which sometimes originate from the ignorance or negligence of the early transcribers of manuscripts, sometimes from the changes which an author makes himself in the later editions of his works. To restore the true text of ancient works is the business of verbal criticism, and is often very important; e. g. in classic authors, the Bible, &c. Some editions contain all the various readings in notes.

VARNA; a town of European Turkey, in Bulgaria; one hundred and twelve miles north-east of Adrianople, and one hundred and forty-four north of Constantinople; lon. 27° 59′ E.; lat. 43° 71 N.; population, 16,000. It has an old castle, twelve mosques, two Greek churches, the most commodious port in Bulgaria, and a large trade with Constantinople. It is situated on a gulf or bay of the Black sea, to which it gives name, at the mouth of the river Varna. In 1444, Ladislaus, king of Hungary, was defeated and slain by Amurath I, sultan of the Turks, near this town. In 1783,

Varna resisted the attacks of the Russians; but, Oct. 11, 1828, it was taken possession of by the Russian forces. (See Russia.) VARNISH. Lac varnishes, or lacquers, consist of different resins in a state of solution, of which the most common are mastich, sandarach, lac, benzoin, copal, amber, and asphaltum. The menstrua are either expressed or essential oils or alcohol. For a varnish of the first kind, the common painters' varnish is to be united, by gently boiling it, with some more mastich or colophony, and then diluted with a little more oil of turpentine. The latter addition promotes both the glossy appearance and drying of the varnish. Of this sort also is the amber varnish. To make this varnish, half a pound of amber is kept over a gentle fire, in a covered iron pot, in the lid of which there is a small hole, till it is observed to become soft, and to be melted together into one mass. As soon as this is perceived, the vessel is taken from the fire, and suffered to cool a little, when a pound of good painters' varnish is added to it, and the whole suffered to boil up again over the fire, keeping it continually stirring. After this, it is again removed from the fire, and, when it is become somewhat cool, a pound of oil of turpentine is to be gradually mixed with it. Should the varnish, when it is cool, happen to be yet too thick, it may be attenuated with more oil of turpentine. This varnish has always a dark-brown color, because the amber is previously half-burned in the operation; but, if it be required of a bright color, amber powder must be dissolved in transparent painters' varnish, in Papin's machine, by a gentle fire. As an instance of the second sort of lac varnishes with ethereal oils alone, may be adduced the varnish made with oil of turpentine. For making this, mastich alone is dissolved in oil of turpentine by a very gentle, digesting heat, in close glass vessels. This is the varnish used for the modern transparencies, employed as window-blinds, fire-screens, and for other purposes. These are commonly prints, colored on both sides, and afterwards coated with this varnish on those parts that are intended to be transparent. Sometimes fine thin calico, or Irish linen, is used for this purpose; but it requires to be primed with a solution of isinglass before the color is laid on. Copal may be dissolved in genuine Chio turpentine, by adding it in powder to the turpentine, previously melted, and stirring till the whole is fused. Oil of turpentine may

then be added to dilute it sufficiently. A varnish of the consistence of thin turpentine is obtained by the digestion of one part of elastic gum, or caoutchouc, cut into small pieces, in thirty-two parts of naphtha. Previously to its being used, however, it must be passed through a linen cloth, in order that the undissolved parts may be left behind. The third sort of varnishes consists of the spirit varnishes. The most solid resins by themselves produce brittle varnishes; therefore something of a softer substance must always be mixed with them, whereby this brittleness is diminished. For this purpose, elemi, turpentine, or balsam of copaiva, are employed in proper proportions. For the solution of these bodies, the strongest alcohol ought to be used. In conformity to these rules, a fine-colored varnish may be obtained by dissolving eight ounces of gum sandarach and two ounces of Venice turpentine in thirty-two ounces of alcohol by a gentle heat. Five ounces of shell-lac, and one of turpentine, dissolved in thirtytwo ounces of alcohol, by a very gentle heat, give a harder varnish, but of a reddish cast. To these the solution of copal is undoubtedly preferable in many respects. This is effected by triturating an ounce of powdered gum copal, which has been well dried by a gentle heat, with a drachm of camphor, and, while these are mixing together, adding, by degrees, four ounces of the strongest alcohol, without any digestion. Between this and the gold varnish there is only this difference, that some substances that communicate a yellow tinge are to be added to the latter. Take two ounces of shell-lac, of annotto, and turmeric, of each one ounce, and thirty grains of fine dragon's blood, and make an extract with twenty ounces of alcohol, in a gentle heat. Oil varnishes are commonly mixed immediately with the colors; but lac or lacquer varnishes are laid on by themselves upon a burnished colored ground. When they are intended to be laid upon naked wood, a ground should be first given them of strong size, either alone or with some earthy color, mixed up with it by levigation. The gold lacquer is simply rubbed over brass, tin or silver, to give them a gold color. Before a resin is dissolved in a fixed oil, it is necessary to render the oil drying. For this purpose, the oil is boiled with metallic oxides, in which operation, the mucilage of the oil combines with the metal, while the oil itself unites with the oxygen of the oxide. To accelerate

the drying of this varnish, it is necessary to add oil of turpentine. The essential varnishes consist of a solution of resin in oil of turpentine. The varnish being applied, the essential oil flies off, and leaves the resin. This is used only for paintings. When resins are dissolved in alcohol, the varnish dries very speedily, and is subject to crack; but this fault is corrected by adding a small quantity of turpentine to the mixture, which renders it brighter, and less brittle when dry. The colored resins or gums, such as gamboge, dragon's blood, &c., are used to color varnishes. To give lustre to the varnish after it is laid on, it is rubbed with pounded pumice-stone and water, which being dried with a cloth, the work is afterwards rubbed with an oiled rag and tripoli. The surface is, last of all, cleaned with soft linen cloths, cleared of all greasiness with powder of starch, and rubbed bright with the palm of the hand. The following receipt for a good spirit varnish is given by Tingry-Take strong alcohol, thirtytwo parts; pure mastich, four; sandarach, three; clear Venice turpentine, three; coarsely ground glass, four. Reduce the mastich and the sandarach to fine powder; introduce them, with the glass and spirit, into a matrass, which is to be placed in hot water for one or two hours, taking care to stir up the materials from time to time with a glass spatula; then pour in the turpentine, and keep the vessel for half an hour longer in the water. Next day decant off the liquor, and filter it through cotton. It will be perfectly limpid. This varnish is usually applied to objects of the toilet, as work-boxes, card-cases, &c.-Essence varnish, by the same; Take mastich in powder, twelve parts; pure turpentine, one and a half; camphor in bits, one half; crystal glass, ground, five; rectified oil of turpentine, thirty-six. Put the mastich, camphor, glass and oil into a matrass, and dissolve as above prescribed. This varnish is applied to paintings.-Fat varnish. Take copal, sixteen parts; linseed or poppy oil, made drying with litharge, eight; oil of turpentine, sixteen. Melt the copal in a matrass, by exposing it to a moderate heat; pour then upon it the boiling hot oil; stir the mixture, and, when the temperature has fallen to about 200° Fahr., add the oil of turpentine heated. Strain the whole immediately through linen cloth, and keep the varnish in a widemouthed bottle. It becomes very clear in a little while, and is almost colorless when well made. Copal varnish is ap

plied on coaches, also generally on polished iron, brass, copper and wood.-Varnish, among medallists, is the term used to signify those hues which antique medals have acquired by lying in the earth. The beauty which nature alone is able to impart to medals, and which art has never yet attained the power of counterfeiting, enhances their value. The colors acquired by certain metals, from having lain a long while in the ground, are various, and some of them exquisitely beautiful. The blue nearly rivals that of the turquoise: others have an inimitable vermilion color; others, again, a polished, shining brown. But that most usually found is a delicate green, which hangs to the finest strokes without effacing them. No metal except brass is susceptible of this. The green rust which gathers on silver always spoils it, and must be removed with vinegar or lemon juice. Falsifiers of medals have a varnish which they use on their counterfeits, to give them the appearance of being antique; but there are means of discovering these deceptions. (See Numismatics.)

VARRO, Marcus Terentius, one of the most learned men and prolific writers of ancient Rome, born B. C. 116, served, in his youth, in the army, and, at a later period, obtained the dignity of tribune, with other public offices. Varro was the intimate friend of Cicero, and was banished by Antony, but returned to Rome under Augustus, and died there, at the age of eighty-nine years, with the reputation of being the most learned Roman, or at least the most learned critic, of his time. The number of his writings, chiefly on language, history and philosophy, is stated to have amounted to about 500, of which only two have come down to us-a treatise upon agriculture (De Re Rustica), in three books, which is contained in the collection Scriptores Rei Rustice, and fragments of a treatise on the Latin language (De Lingua Latina), which treats principally of etymology and analogy. Good editions of the latter have appeared at Dort, in 1619 (2 vols.), and (by Sprengel) at Berlin, in 1826. The former has been translated into English by Owen (1800).

VARUS, Quintilius. (See Arminius.} VASA, Gustavus. (See Gustavus I.) VASARI, Giorgio, the first writer who gave a complete history of all modern artists, and also himself a practical artist, was born at Arezzo, in the grand duchy of Tuscany, in 1512, and studied under Luca Signorelli, Michael Angelo Buonarotti, and Andrea del Sarto. The cardi