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cipating alike of them both. This system lours, than the ancient ones. But both had its name and original from Tycho kinds seem to be made of the same whitBrahe, a nobleman of Denmark, who liv. ish clay as our white glazed earthen ware ; ed in the latter part of the last century: the modern ones are commonly painted This philosopher, though he approved with birds, flowers, &c. The ancient of the Copernican system, yet could not ones are only five inches and a quarter reconcile bimself to the motion of the square, and about three-quarters of an earth, and being, on the other hand, inch thick ; the modern ones six inches convinced the Ptolemaic scheme could and a half square, and three-quarters of not be true, he contrived one different an inch thick. from either. In this the earth has no mo. TYMPAN, or TYMPANUM, in architection allowed it, but the annual and diur. ture, the area of a pediment, being that nal phenomena are solved by the motion part which is on a level with the naked of the sun about the earth, as in the Pto. of the frieze. Or it is the space included lemaic scheme ; and those of Mercury between the three cornishes of a trianguand Venus are solved by this contrivance, lar pediment, or the two cornishes of a though not in the same manner, nor so

circular one. Sometimes the tympan is simply and naturally, as in the Copernican cut out, and the part filled with an iron system. The Tychonic system then sup lattice, to give light, and sometimes it is posed the earth in the centre of the enriched with sculpture in basso relievo, world, that is, of the firmament of stars, T'IMPAN, among printers, a double and also of the orbits of the sun and frame belonging to the press, covered moon ; but at the same time it made the

with parchment, on which the blank sun the centre of the planetary motions, sheets are laid in order to be printed off. viz. of the orbits of Mercury, Venus, See PRINTING. Mlars, Jupiter and Saturn. Thus the sun, TYMPANUM, or TIMPAN, in mecha. with all its planets, was made to revolve nics, a kind of wheel placed round an about the earth once a year, to solve the axis, or cylindrical beam, on the top of phenomena arising from the annual mo. which are two levers or fixed staves, for tion; and every twenty-four hours to ac the more easy turning the axis, in order count for those of the diurnal motion. to raise a weight required. The tympaTYGER. See FELIS.

num is much the same with the peritroTYLE, or Tile, in building, a sort of chium, but that the cylinder of the axis thin, fictitious, laminated brick, used on of the peritrochium is much shorter and the roofs of houses; or more properly, a less than the cylinder of the tympanum. kind of fat clayey earth, kneaded and TYMPANUM of a machine, is also used for moulded, of a just thickness, dried and a hollow wheel, wherein one or more burnt in a kiln like a brick, and used in people, or other animals, walk, to turn the covering and paving of houses. See it; such as that of some cranes, calenBпіск. .

ders, &c. There are various kinds of tyles, for TYPE, a copy, image, or resemblance the various occasions of building ; of some model. This word is much used plain, thack, ridge, roof, crease, gutter, among divines, to signify a symbol, sign, pan, crooked, Flemish, corner, hip, dor or figure of something to come ; in which mar, scallop, astragal, traverse, paving, sense it is commonly used with relation to and Dutch tyles.

antitype, which is the thing itself, whereFlemish or Dutch tyles are of two kinds, of the other is a type or figure. ancient and modern. The ancient were TYPHA, in botany, a genus of the Moused for chimney foot-paces; they were noecia Triandria class and order. Natural painted with antique figures, and fre. order of Calamariæ. Typhæ, Jussieu. Esquently with postures of soldiers; some sential character: male, ament cylindriwith compartments, and sometimes with cal; calyx indistinct, three-leaved; comoresque devices : but they come much rolla none; female, ament cylindrical, short of the design and colours of the below the males; calyx a villose hair; modern ones. The modern Flemish corolla none; seed one, placed on a catyles are commonly used plastered up in pillary down. There are two species, viz. the jambs of chimneys, instead of chim T. latifolia, great cat's tail, or reed mace ; ney-corner stones. These are better and T. angustifolia, narrow-leaved cat's glazed, and such as are painted (for tail.

are only white) are done with TYPOGRAPHY, the art of printing. more curious figures, and more lively co See PRINTING and STEREOTYPE.

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Or u, the twentieth letter, and fifth by the more quick descent of light bodies

in a receiver when exhausted of its air, in the voice by a round configuration of there must be some vacuities between the lips, ånd a greater extrusion of the the parts of the remaining air ; which is under one than in forming the letter o, sufficient to constitute a vacuum. Indeed, and the tongue is also more cannulated. to this it may be objected by a Cartesian, The sound is short in crust, must, tun, that those vacuities are filled with matetub: but is lengthened by a final e, as in ria subtilis, that passes freely through the tune, tube, &c. In some words it is rather sides of the vessel, and gives no resistacute than long; as in brute, flute, lute, &c. ance to the falling bodies: but as the exIt is mostly long in polysyllables; as in istence of this materia subtilis can never union, curious, &c. but in some words it be proved, we are not obliged to allow is obscure, as in nature, venture, &c. the objection, especially since Sir Isaac This letter, in the form, V, or v, is pro

Newton bas found that all matter affords perly a consonant, and as such is placed a resistance nearly in proportion to its before all the vowels; as in vacant, venal, density. There are many other arguments vibrate, &c. Though the letter v and u to prove this, particularly the motions of had always two sounds, they had only the the comets through the heavenly regions, form v, till the beginning of the fourth without any sensible resistance, the difcentury, when the other form was intro- ferent weight of bodies of the same bulk, duced, the inconvenience of expressing &c. All the parts of spaces, says Sir two different sounds by the same letter Isaac Newton, are not equally full; for if having been observed long before. In they were, the specific gravity of the fluid numerals V stands for five, and with a which would fill the region of the air, dash added at top, thus, V, it signifies could not, by reason of the exceeding 5000.

great density of its matter, give way to VACCINATION. See SURGERY.

the specific gravity of quicksilver, gold, VACCINIUM, in botany, bilberry, or

or any body, how dense soever; whence whortleberry, a genus of the Octandria Mo. neither gold, nor any other body, could nogynia class and order. Natural order

descend in the air ; for no body can deof Bicornes. Ericæ, Jussieu. Essential

scend in a fluid, unless it be specifically character: calyx superior; corolla one.

heavier than it. But if a quantity of matpetalled; filaments inserted into the re. ter may, by rarefaction, be diminished in ceptacle; berry four-celled, many-seed

a given space, why may it not diminish in ed. There are twenty-seven species.

infinitum ? And if all the solid particles VACUUM, in philosophy, denotes a

of bodies are of the same density, and space empty, or devoid, of all matter or

cannot be rarefied, without leaving pores, body. It has been the opinion of some

there must be a vacuum. philosophers, particularly the Cartesians,

VADE mecum, or VENI mecum, a Latin that nature admits not a vacuum, but that phrase, used in English to express a the universe is entirely full of matter: in thing that is very handy and familiar, and consequence of which opinion they were

which one usually carries

about with them; obliged to assert, that if every thing con

chiefly applied to some favourite book. tained in a vessel could be taken out or VAGINA, properly signifies a sheath, annihilated, the sides of the vessel, how or scabbard : and the term vagina is used, ever strong, would come together; but in architecture, for the part of a terminus, this is contrary to experience, for the because resembling a sheath, out of which greatest part of the air may be drawn out the statue seems to issue. of a vessel by means of the air-pump, not VAGINALIS, the sheath-bill, in natural withstanding which it will remain whole, history, a genus of birds of the order if its sides are strong enough to support

Grallæ. Generic character : bill strong, the weight of the incumbent atmosphere. thick, compressed; upper mandible coShould it be objected here, that it is im vered above with a moveable horny possible to extract all the air out of a ves sheath; nostrils placed before the sheatb; sel, and that there will not be a vacuum face naked and papillous; wings with on that account; the answer is, that since an obtuse excrescence under the Aexa very great part of the air that was in

ure; claws grooved. V. alba, or the the vessel may be drawn out, as appears white sheath-bill, the only species knowo, VOL. XII,

T

is a native of New Zealand and the South manner as the general county rate. 17 Sea Islands. It is in length about sixteen George III c. 5. inches. Its food consists of shell-fish and VAHLIA, in botany, so named in hoputrid carcases. Its legs are long, red, nour of Martin Vahl, regius professor of and naked a little above the knees. botany, at Copenhagen, a genus of the

VAGRANTS are all persons threaten- Pentandria Digynia class and order. Na. ing to run away, and leave their wives and tural order of Succulentæ. Onagræ, Jus. children to the parish. All persons un. sieu. Essential character: calyx fivelawfully returning to the parish or place leaved : corolla five-petalled ; capsule whence they have been legally removed inferior, one-celled, many-seeded. There by order of two justices, without bring. is only one species, viz. V. capensis, a naing a certificate from the parish or place tive of the Cape of Good Hope, in sandy whereto they belong. All persons who places. have not wherewith to maintain them VAIR, in heraldry, a kind of fur, con. selves, live idle, and refuse to work for sisting of divers little pieces, argent, and the usual wages given to other labourers azure, resembling a Dutch U, or a bell. in the like work, in the parishes or places glass. Vairs have their point azure oppo. where they are. All persons going from site their point argent, and the base ardoor to door, or placing themselves in the gent to the base azure. streets, highways, or passages, to beg or VAIRY, VAIRL, VERRY, or VARNY, in gather alms in the parishes or places heraldry, expresses a coat, or the bearwhere they dwell. All these shall be ings of a coat, when charged or chequer. deemed idle and disorderly persons, and ed with vairs : and hence, vairy cuppy, or one justice may commit such offenders vairy tassy, is a bearing composed of (being thereof convicted before him, by pieces representing the tops of crutches. his own view, confession, or oath of one VALANTIA, in botany, cross-wort, a witness) to the house of correction, to genus of the Polygamia Monoecia class hard labour, not exceeding one month. and order. Natural order of Stellatæ. And any person may apprehend and car. Rubiacea, Jussieu. Essential character : ry before a justice any such persons go. hermaphrodite, calyx none; corolla fouring from door to door, or placing them- parted ; stamens four; style bifid; seed selves in the streets, highways, or pas one ; male, calyx none; corolla three or sages, to beg alms in the parishes or four-parted ; stamens three or four; pistil places where they dwell; and if they shall obsolete. There are nine species. resist, or escape from the person appre

VALENTINIA, in botany, a genus of hending them, they shall be punished as the Octandria Monogynia class and order. rogues and vagabonds. And the said jus- Essential character: calyx five-parted, tice, by warrant under his hand and seal, coloured, spreading ; corolla none; capmay order any overseer, where such of. sule berried, four-seeded, pulpy. There fender shall be apprehended, to pay five is but one species, viz. V. illicifolia, a nashillings to any person in such parish or tive of Hispaniola, on the most barren place so apprehending them, for every of. rocks towards the ocean ; also in Cuba, fender so apprehended; to be allowed in about the Havannah. his accounts, on producing the justice's VALERIANA, in botany, valerian, a order and the person's receipt to whom it genus of the Triandria Monogynia class was paid. 17 George II. c. 5. The same and order. Natural order of Aggregatæ. statute also enacts, that such justice shall Dipsaceæ, Jussieu. Essential character: order the person, so apprehended to be calyx none; corolla one-petalled; gibpublicly whipped by the constable, pe bous on one side of the base, superior; tit-constable, or some other person to be

seed one. There are thirty-one species. appointed by such constable or petit-con. VALLISNERIA, in botany, a gestable of the place where such offender nus of the Dioecia Diandria class and was apprehended, or shall order him to order. Natural order of Palmæ. Hy. be sent to the house of correction; and drocharides, Jussieu. Essential characby 27 George III. c. 11, the common gaol, ter: male, spathe two-parted; spadix until the next sessions, or for any less covered with floscules ; corolla threetime, as such justice shall think proper. parted; female, spathe bifid, one-flowTo defray the expenses of apprehending, ered; calyx three-parted: superior; conveying, and maintaining rogues, va. stigma three-parted: capsule one-celled, gabonds, and incorrigible rogues, and all many-seeded. There are two species, other expenses necessary, the justices, viz. V. spiralis, two-stamened vallisneria ; in sessions, may cause such sums as shall and V. octandria, eight-stamened vallis. be necessary to be raised, in the same nеria, ,

on.

VALUE, in commerce, denotes the to the articles EVAPORATION and MEDEONprice or worth of any thing: hence the OLOGY, and shall make a few additional intrinsic value denotes the real and ef. observations on dew, which is a phenofective worth of a thing, and is used menon proper to clear weather. It be. chiefly with regard to money, the popular gins to be deposited about sun-set, is value whereof may be raised and lower. most constant in vallies, and on plains ed at the pleasure of the prince ; but its near rivers, and other collections of wareal, or intrinsic value, depending wholly ters, and abounds on those parts of the on its weight and fineness, is not at all af surface which are clothed with vegetafected by the stamp or impression there. tion. It is often suspended when rain is

approaching, as likewise in windy weaVALVE, in hydraulics, pneumatics, ther, and before thunder storms: an un&c. is a kind of lid, or cover, of a tube usually copious deposition however some. or vessel, so contrived as to open one times precedes rain. The following is way; but which, the more forcibly it is

said to be the usual appearance in the pressed the other way, the closer it shuts valley through which the Thames passes. the aperture ; so that it either admits the After a clear warm day there is gradually entrance of a fluid into the tube or vessel, formed on the horizon a continuous haze, and prevents its return ; or admits its rising sometimes to a considerable height, escape, and prevents its re-entrance. and often tinged by the setting sun with

VALVE, in anatomy, a thin membrane, a fine gradation of red and violet shades. applied on several cavities and vessels of This is the precipitated water become the body, to afford a passage to certain faintly visible in its descent. Dew is alhumours going one way, and prevent ways to be found on the grass by the their reflux towards the place from

time that this haze has become conspi. whence they came. The veins and lym- cuous, and its abundance is proportioned phatics are furnished with valves which to the density and permanence of the open towards the heart, but keep close latter. The following facts are deserving towards the extremities of those vessels ; of notice. that is, they let the blood and lymph pass In this country the dew is observed towards the heart, but prevent their re more copiously in the mornings of spring turning towards the extreme parts from and summer than at other times in the whence they came.

year. Sometimes, however, in autumn VAN, in naval affairs, the foremost and winter, an abundant dew is deposited division of a naval armament, or that part in the night. In countries nearer the which leads the way to battle, or advances equator, the dews are generally observed first in the order of sailing.

in the morning throughout the whole VANDELLIA, in botany, a genus of year; and in some places they are so the Didynamia Angiospermia class and very copious as in a great measure to order. Natural order of Personatæ. Scro. supply the deficiency of rain, which selphulariæ, Jussieu. Essential character: dom falls in those places. The conden. calyx four-parted; corolla ringent; fila. sation of the vapour which forms the ments the two outer from the disk of the dew mostly takes place while the sun is lip of the corolla; anthers connected by

below the horizon; the greatest deposi. pairs; capsule one-celled, many-seeded. tion taking place soon after the setting

of the sun. There are two species, viz. V. diffusa,

In cloudy weather there is and V. pratensis.

little or no dew deposited: the most

considerable quantity is observed in a VANGUERIA, in botany, a genus of the Pentandria Monogynia class and or

morning, 'subsequent to a clear, still, and der. Natural order of Aggregatæ. Ru

cool night, which has followed a pretty

warm day. The lower parts of bodies biacez, Jussieu. Essential character :

that are exposed to the ambient air are calyx five-toothed; corolla tube globu.

first covered with dew. The most singular, with a hairy throat; stigma bilamel.

lar circumstance is, that dew is not deposi. late ; berry inferior; four or five-seeded.

ted upon all kinds of substances indisThere is but one species, viz. V. edulis,

criminately: it falls upon certain bodies supposed to be a native of China.

much more abundantly than on others, VAPOUR, in meteorology, a thin hu and upon some even not at all. The mid matter, which, being rarefied to a drops of dew attach themselves to glass, certain degree by the action of heat, crystals, and porcelain, much more reaascends to a particular height in the at dily than to other bodies; next to these mosphere, where it is suspended, until come the leaves of vegetables, wood, it returns in the form of dew, rain, snow, especially when varnished, and common &c. On this subject we refer our readers earthen ware ; but the dew adheres least

of all to all sorts of metallic bodies. We ance between the declaration and the may now notice Mr. Dalton's observa. writ, it is error, and the writ shall abate; tions, which are the result of a variety of and if there appear to be a material variwell conducted and very accurate experi. ance between the matter pleaded and ments on this subject. 1. That aqueous the manner of pleading it, this is not a vapour is an elastic vapour sui generis, good plea, for the manner and matter of diffusible in the atmosphere, but forming pleading ought to agree in substance, or no chemical combination with it. 2. That there will be no certainty in it. Cro. Jac. temperature alone limits the maximum of 479. vapour in the atmosphere. 3. That there VARIATION of curvature, in geometry, exists at all times, and in all places, a is used for that inequality or change quantity of aqueous vapour in the atmo which happens in the curvature of all sphere, variable according to circum curves except the circle ; and this variastances. 4. That whatever quantity of tion, or inequality, constitutes the quality aqueous vapour may exist in the atmo. of the curvature of any line. Sir Isaac sphere at any time, a certain tempera. Newton makes the index of the inequality, ture may be found, below which a por. or variation of curvature, to be the ratio tion of that vapour would unavoidably of the fluxion of the radius of curvature fall or be deposited, in the form of rain to the fusion of the curve; and Mr. or dew, but above which no such dimi- Maclaurin, to avoid the perplexity that nution could take place with chemical different notions, connected with the agency. This point may be called the same terms, occasion to learners, has extreme temperature of vapour of that adopted the same definition ; but he sugdensity; and 5. That whenever any body, gests, that this ratio gives rather the varicolder than the extreme temperature of ation of the ray of curvature, and that it the existing vapour, is situated in the at might have been proper to have measurmosphere, dew is deposited upon it, the ed the variation of curvature, rather by quantity of which varies as the surface the ratio of the fuxion of curvature itself of the body, and the degree of cold be.

to the fluxion of the curve : so that the low the extreme temperature. The curvature being inversely as the radius reader may be referred to an excellent of the curvature, and consequently its and elaborate article on this sobject in fluxion as the fluxion of the radius itself Dr. Rees's New Cyclopedia, a work, of directly, and the square of the radius inwhich it may be fairly and honourably versely, its variation would have been disaid, that as it advances in its progress, it rectly as the measure of it, according to increases in merit and reputation.

Sir Isaac's definition, and inversely as the VARIABLE quantities, in geometry and square of the radius of curvature. analytics, denote such as are either con VARIATION of the needle, in magnetism. tinually increasing or diminishing; in op. Although the north pole of the magnet position to those which are constant, re in every part of the world, when susmaining always the same. Thus, the ab. pended, points towards the northern scisses and ordinates of an ellipsis, or parts, and the south pole to the southern other curve line, are variable quantities, parts, yet it seldom points exactly north because they vary or change their magni- and south. The angle, in which it devi. tudes together. Some quantities may be ates from due north and south is called variable by themselves alone, while those “ The variation of the needle," or, “ The connected with them are constant: as variation of the compass,” and this varia. the abscisses of a parallelogram, whose tion is said to be east or west, according ordinates may be considered as all equal, as the north pole of the needle is eastward and therefore constant. The diameter of or westward of the meridian of the place. a circle, and the parameter of a conic This deviation from the meridian is not section, are constant, while their abscisses the same in all parts of the world, but is are variabie. Variable quantities, (see different in different places, and it is alFLUXIONS,) are usually denoted by the most perpetually varying in the same last letters of the alphabet z, y, x, while place. When the variation was first ob. the constant ones are denoted by the first served, the north pole of the magnetic letters a, b, c.

needle declined eastward of the meridian VARIANCE, in law, signifies any alter- of London, but it has since that time ation of a thing formerly laid in a plea, or been changing towards the west ; so that where the declaration in a cause differs in the year 1657, the needle pointed due from the writ, or from the deed upon north and south; at present, it declines which it is grounded. If there be a vari towards the west between 24° and 25°

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