following grand divisions:-Exogens, Gymnosperms, Endogens, Rhizanths, and Acrogens.-Vegetable ivory is a name given to the seed of certain South American trees.-Vegetablemarrow, the name given to the Gourd, Cucurbita ovifera, of which there are several varieties. In horticulture, vegetable earth is called mould; and in agriculture, the term is applied to the surface soil of hollows which contain alluvial soil beneath. Vegeta'tion (Lat.), the process of growth, as plants, by means of nourishment imbibed from water and air, and received through roots and leaves. Vein (Lat. vena), in animal physiology, a vessel or canal which receives the blood from the extreme capillary arteries, and conveys it to the heart. -In botany, an assemblage of tubes, by which the sap is transmitted through the leaves.-In geology, a fissure or rent filled with mineral or metallic matter, differing from the rock in which it occurs. Vellica'tion (Lat. vellico to pull), in pathology, a twitching or convulsion of a muscular fibre.

Velocim'eter (Lat. velox swift, and Gr.

metron a measure), a machine for measuring the speed of machinery. Velo'cipede (Lat. velox, and pedes feet), a sort of machine with two wheels, placed one before the other, and connected by a beam, on which a person sits astride; and the vehicle is propelled by the muscular power of the rider acting upon treadles and levers, which communicate with a cranked-wheel axle.

Vena (Lat. a vein. See Vein).-Vena porta (vein of the gate), the large vein which conveys the blood from the intestines into the liver.-The vena cava are the large hollow veins which pour the blood collected from the body into the heart.--Venation, in botany, is the arrangement of the veins in leaves.-Venous system is the collective name for the veins. Veneri'næ, a sub-family of close bivalveshelled Mollusca, of the family Tellinidæ.

Venesec'tion (Lat. vena, and sectio a cutting), the act or operation of opening a vein; phlebotomy. Vene'tian Chalk, a white compact talc or steatite, used for marking on cloth, &c.

Vene'tian Red, a bright red ore, usually prepared from sulphate of iron. Venice Turpentine, an oleo-resinous material obtained from the Larix Europea.

Venter (Lat.), any cavity of the body; the abdomen.

Ven'tricle (Lat.ventriculus, from venter the belly), a small cavity in an animal body. In anatomy, the term is applied to two cavities of the heart which propel the blood into the arteries and also to cavities in different parts of the brain. Ven'tricose (Lat. venter), in botany and zoology, big-bellied.-In conchology, inflated or swelled in the middle of the shell.

Ventriloquism (Lat. venter, and loquor to speak), the art of speaking inwardly, so that the sound appears to issue from some distant spot. Ven'turine, a powder made of fine gold

wire, which is strewed upon the first layer of varnishing laid in japanning. Venus (Lat.), in astronomy, a brilliant planet, the second in order of distance from the sun, and the most brilliant of all the planetary bodies. Her distance from the sun is about 68,000,000 miles.

Vera'trine, a vegetable alkali discovered in white hellebore and some other plants.

Verbe'na, the name of a fine and costly perfume, obtained by distillation from the citron-scented leaves of the Aloysia citriodora.

Verbena'ceæ, in botany, a nat. order of Exogens, consisting of trees, or herbaceous plants, of which Verbena, or Vervain, is the type.

Verd-antique (Fr.), the green incrustation found on the surface of ancient copper and brass coins.-In mineralogy, a beautiful mottled-green

marble.

Verdate (Lat. viridis green), a salt consisting of verdic acid with a salifiable

base.

Verdic Acid (Lat. viridis), an acid so

named from its becoming green when exposed to the atmosphere. Verdigris (Fr.), the blue-green rust of copper or brass.

Ver'diter (Fr.), a blue pigment.-In chemistry, a hydrated percarbonate of

copper.

Vermeol'ogy (Lat. vermis a worm, and Gr. logos a discourse), a treatise on worms; helminthology.

Vermes (Lat. worms), in zoology, a

class of invertebrated animals that have no antennæ, legs, voice, or true blood.

Vermiculite (Lat. vermiculus a little worm), a mineral which consists of micaceous-looking plates, composed of silica, magnesia, peroxide of iron, alumina, and water: sp. gr. 2; H = 1. Ver'mifuge (Lat. worm-expelling), in pathology, a medicine for destroying intestinal worms.

Vermilion (Fr. vermeil), red sulphuret of mercury; cinnabar. Verna'tion (from Lat. ver the spring), the manner in which the young leaves are arranged in their leafbud foliation.

Vernier (Fr.), a contrivance for measuring intervals between the divisions of graduated scales or circular instruments, so named from the inventor. Verruca (Lat.), a wart.-Verrucose, full of warts, or having elevations resembling warts.

Vertebra (Lat.), a joint in the back or spine; pl. Vertebræ, the bones of the spine. Vertebra'ta (Lat. vertebra), one of the great divisions of the animal kingdom, including those animals which are furnished with a back-bone, as the Mammalia, birds, reptiles, and fishes.

Vertex (Lat. from verto to turn), the point of a cone, pyramid, angle, or figure. In astronomy, the zenith or point of the heavens perpendicularly over the head.

Vertical (Lat. vertex), being perpendicular to the horizon. Vertical angles are opposite angles formed by two straight lines which intersect each other. In astronomy, vertical circle is a great circle of the sphere passing through the zenith and nadir. -Vertical line is a line perpendicular to the horizon.-In conic sections, it is a right line drawn on the vertical plane, and passing through the vertex of the cone.-Vertical plane is a plane passing through the vertex, and parallel to the plane of the section.-Prime vertical, a great circle of the sphere, perpendicular to the horizon, and passing through the zenith, and the east and west points. Verticil (Lat.), in botany, a little whorl. -Verticillate is an epithet applied to flowers or leaves which grow in whorls.

Vertigo, or Verti'go, pl. Vertig'ines (Lat. verto), a sense of giddiness or swimming of the head.

Vesa'niæ (Lat. vesanus insane), in pathology, a class of diseases which includes the various forms of insanity. Vesculo'sa (Lat. vesica a bladder), a tribe of dipterous insects (the Tanystoma) which have the abdomen in the form of a bladder.

Ves'icant (Lat. vesica), in medicine, a substance that raises blisters on the skin.

Ves'icle (Lat. vesicula a little bladder), any small membranous cavity in animals or vegetables, as those of the lungs, or of sea-weed.

Vespertilion'ida (Lat. vespertilio a bat),

in ornithology, the Bat family, which comprehends the sub-families Phyllostominæ, Noctilioninæ, Rhinolophinæ, Vespertilioninæ, and Pteropinæ.

Ves'pidæ, in entomology, a family of hymenopterous insects, of which the Vespa, or Wasp, is the type. Vessel (Lat. vus, vasis), any utensil for holding liquors and other things.—In anatomy and botany, a tube; a canal or duct which contains a fluid or other substance.-In vegetable physiology, a tube of very small diameter, in which the vegetable sap is conveyed.

Vesta, in astronomy, one of the four small planets which circulate between the orbits of Mars and Jupiter; an asteroid.-Vesta is also the name of one of the newly-discovered planets, first observed by Olbers in 1807. Its mean distance from the sun is 225,290,000 miles, and its periodical revolution 3 years, 230 days.

Vesu'vian (from Mount Vesuvius), in mineralogy, volcanic garnet; a subspecies of pyramidal garnet; a brownish mineral substance crystallized; a name of the mineral ido

crase.

Vexil'lum (Lat. a standard), in botany, the upper petal of a papilionaceous flower.

Via (Lat.).—In astronomy, Via Lactea is a term applied to the galaxy, or milky way, the white circle which encompasses the whole firmament, composed of an infinite number of

stars.

Vi'aduct (Lat. via a way, and duco to lead), an extensive bridge or series of arches for conducting a road above the level ground in crossing a valley or other declivity.

Viam'eter (Lat. via, and Gr. metron a measure), an instrument to measure the distance passed over; an odo

meter.

Via'rian (Lat. via), pertaining to roads, or travelling by public ways; as, the viarian communications of a country, by railway or otherwise.

Viatec'ture (Lat. via, and tectum a covering), the art of constructing roads, bridges, railroads, canals, and water-works; civil engineering. Vibra'tion (Lat. vibro to move to and fro), in physics, alternate and reciprocal motion, as the vibrations of the nervous fluid.-In music, the undulation of any body by which sound is produced.

Vibrio (Lat. vibro), in entomology, a term applied to certain minute

thread-like animalcules sometimes existing in fluids. Victoria, in astronomy, one of the recently-discovered planets, first observed by Hind in 1850. Its mean distance from the sun is 223,770,000miles, and its periodical revolution 3 years, 207 days.-In botany, a genus of magnificent stove aquatics, with immense spreading white flowers, so named in honour of her Majesty Queen Victoria; order Nymphæacex.-Lindley.

Vil'larsite, a crystallized yellowish mineral, composed of silica, magnesia, protoxide of iron, protoxide of manganese, lime, potash, and water; H=30-35.

Villi (Lat. villus wool or hair), in botany, long, straight, soft hairs on the surface of a plant.-In anatomy, minute projections from the surface of a mucous membrane, presenting the appearance of the nap of cloth. -Villous, having a covering resembling hair or wool.-Villosity, the condition of being covered with villi. Vin'culum (Lat. a band or tie), in algebra, a connecting mark or line drawn over a quantity, by which various terms are compounded into one, as in a+b+cx, (a+b+c) x [a+b+c] x, &c., which are, by the vinculum, prevented from being confounded with a+b+cx.

Viol (Ital. viola), an ancient musical instrument, the parent of all the modern instruments of the violin kind. -Tenor viol is a larger kind of violin, to which the part between the second violin and bass is assigned. Viola'cea (Lat. viola the violet), a nat. order of plants, consisting of herbs and shrubs.

Violoncello (Ital.), a bass viol, with four strings, an octave lower than the violin.

Violo'ne (Ital.), a large bass violin with three strings; a double bass. Vireoni'næ, a sub-family of the Ampelidæ, or Fruit-eaters. Virgin'ia, one of the lately-discovered planets, first observed by Ferguson in 1857.

Virgo (Lat.), in astronomy, the Virgin, one of the twelve zodiacal signs, which the sun enters about the 22nd of August.

Virtual (Lat. virtus force or power), in mechanical science, an epithet applied to the velocity which a body in equilibrium would acquire in the first instant of its motion, if the equilibrium were disturbed.-In optics, a term applied to the focus from which rays which have appeared divergent seem to issue.

Virtuo'so (Ital.), one skilled in antique or natural curiosities, or who has a taste for the fine arts, as painting, statuary, and architecture.

Virus (Lat. poison), the agent for transmitting infectious diseases.-Virulent, very poisonous.

Vis (Lat. force), in physics, any natural force or power.-In anatomy, that property by which a muscle contracts after the death of an animal.-Vis inertia, the resistance of matter to change as respects motion.--Vis insita (Lat. inherent force), in anatomy, the property by which a muscle, when irritated, contracts independently of the will of the animal, and without sensation.-Vis nervosa, the property of nerves by which they convey stimuli to muscles.

Vis'cera (Lat. pl. of viscus), in anatomy, the intestines or inward parts. Viscus (Lat.), an internal organ of the body; an entrail.

Vis'ual (Lat. pertaining to sight).-In optics, visual angle is the angle under which an object is seen.-Visual rays are lines of light conceived to come from the object to the eye.Visual point, in perspective, is a point in the horizontal line in which all the rays meet.

Vita'cea (Lat. vitis the vine), a nat. order of plants, consisting of scrambling, climbing shrubs, of which Vitis, the grape-producing Vine, is the genus. This order has been named Vitis, Viniferæ, Sarmentaceæ, and Ampelideæ.

Vitality (Lat.), the principle of life; the living principle.

Vitel'lary (Lat. vitellus a yolk), belonging to the yolk of an egg. Vitreous (Lat. vitrum glass), belonging to or resembling glass.-Vitreous body is a large, globular, transparent structure, occupying the centre of the eyeball, being the largest of the transparent media of the eye.-Vitreous electricity, a term sometimes applied to positive electricity, because developed by rubbing glass.-Vitrifaction, the process of converting a substance into glass by the action of heat.-Vitrescence, glassiness, or capability of being formed into glass. Vitriol (Ital. vitriolo, from Lat. vitrum glass), a name given to certain combinations of sulphur and oxygen, or of these with the metals; as, oil of vitriol, sulphuric acid; blue vitriol, sulphate of copper; green vitriol, sulphate of iron; white vitriol, the sulphate of zinc.

Vitta (Lat. vitta a fillet), the receptacles of oil found in the fruits of umbelliferous plants.

Viverri'næ, a sub-family of the Gennets, or Musk Weasels, of which Viverra is the type.

Vivianite, in mineralogy, a phosphate of iron, which occurs crystallized in the form of a right oblique-angled prism. Its constituents are protoxide of iron, phosphoric acid, and water. Viviparous (Lat. bringing forth alive), in botany, applied to stems that produce leaf-buds or buds in place of fruit.

Vochya'ceæ, a nat. order of exogenous plants, consisting of trees and shrubs with opposite leaves, so called from Vochy, the name of a species in Guiana.

Volatility (Lat.), capability of rising in an aëriform state.

Volatilize, to cause to pass off in vapour, or in an aëriform state. Volca'no (Ital. from Vulcan), an opening in the surface of the earth or other planet, from which smoke, flames, and lava, ashes or stones, are ejected. There are about 200 active volcanoes on the earth at present, and numbers which have become extinct.-Volcanic rocks are rocks which have been produced from the discharges of volcanic matter. Volkon'skoite, a Siberian mineral containing oxide of chromium. Voltag'raphy, the art of copying in metals any form or pattern which is made the negative surface of a voltaic circuit.

Volta'ic Electric'ity, the form of electrical action discovered by Galvani, but first described by Volta, in which any two conductors of electricity being brought into contact, an electric action is produced.

Vol'taism, galvanism or electricity, as improved or modified by Volta, to whom we owe the first knowledge of the powers of voltaic or galvanic currents.-Voltaic battery is any arrangement of galvanic circles made so as to produce an effect greater than a simple circle could occasion. Vol'taite, in mineralogy, a species of iron alum.

Voltam'eter, an instrument for measuring voltaic electricity. Vol'taplast, a kind of galvanic battery adapted for electrotyping. Vol'tatype, a metallic plate containing a copy of a device upon a medal or coin; called also electrotype. Voltzite, in mineralogy, a sulphuret of zinc, the constituents of which are sulphuret of zinc, oxide of zinc, oxide of iron, and organic matter: sp. gr. 3'60; H = 4'5.

Volume (Lat. volumen), in music, the compass of a voice from grave to

acute.-In philosophy, the apparent space which a body occupies. Voluntary Muscles are those muscles which are thrown into action in obedience to the will; those which act independently of the will are called involuntary muscles.

Volu'ta (Lat. volvo to roll), in malacology, a genus of Mollusca, the shells of which are large and ventricose. Volute (Fr. from Lat. volvo), in architecture, the spiral scroll appended on each side to the capital of the Ionic order. The Corinthian and Composite orders are also decorated with volutes, but they are smaller, and always diagonally placed.

Volu'tida, a family of Gasteropods, characterized by the shells being destitute of a channel.-Volutina, a sub-family of the Volutidæ, constituting the true Volutes.

Vomer (Lat. ploughshare), in anatomy,

a thin bone which constitutes the inferior posterior part of the septum of the nasal fossæ.

Vom'ica (Lat.), in pathology, a collection of pus within the cavity of the thorax, which is expectorated by a kind of vomiting.

Vorant (Lat. voro to devour), in heraldry, an epithet applied to a fish, bird, beast, or reptile represented as swallowing any other creature. Vorticella (Lat. vortex), a genus of Polypiaria; order Gelatinosi. Also, a genus of pedicellate Infusoria. Voussoir (Fr.), in architecture, a stone in the shape of a truncated wedge, which forms the arch in a bridge; a keystone to an arch.

Vulcaniza'tion, a process of preparing india-rubber by impregnating it with sulphur.

Vulca'nian, relating to the Vulcanists, or their theory of the earth.-According to the Vulcanian theory, the present form of the earth has been produced by the action of fire. Vulnerary (Lat. vulnerarius), useful in healing wounds.

Vul'pinite, in mineralogy, an anhydrous sulphate of lime found at Vulpino, in Italy.

Vulsel'lum (Lat.), in surgery, an instrument for drawing parts into a convenient position for performing an operation.

Vultu'rida (Lat. vultur), a family of large rapacious birds, of which the Vulture is the type; head and neck, in general, more or less naked. Vulva (Lat.), in anatomy, the orifice situated between the labia majora, which leads into the vulvo-uterine canal.Vulva cerebri, an orifice which exists anteriorly to the optic thalami.

Wacke (Germ.), in mineralogy, a rock nearly allied to basalt, of which it is a soft and earthy variety, and chiefly composed of silica.

Wagnerite, a rare mineral resembling the Brazilian topaz. It consists of phosphoric and fluoric acids, magnesia, the oxide of iron, and manganese. Wal'lerite, a variety of orthoclase, found in small compact masses, yellowish and translucent.

Wall-plate, in architecture, a piece of timber lying on a wall, on which girders, joists, &c., rest. - Wallspring, a spring issuing from stratified rocks.

Warwickite, a mineral containing titanium.

Watch (Swed.), in mechanical science,

a small portable time-piece, the machinery of which is moved by a spring. Those watches intended for astronomical or nautical observations are called chronometers, sometimes made with such precision as to vary but a few seconds in the course of a year. At Goldsmiths' Hall, from 14,000 to 15,000 gold watches, and from 80,000 to 90,000 silver ones, are annually assayed.-In watchmaking there are various trades or professions called into action, as the watch dial silverer, the watchglass maker, the watch-tool maker, watch balance-wheel maker, watchbarrel maker, watch-cap maker, watch-case maker, &c.

Water (Sax.), a colourless, inodorous, transparent fluid, composed of oxygen and hydrogen, in the relative proportions, by weight, of 8 to 1. Water presents itself in three distinct forms: first, in a state of vapour or steam; secondly, in its liquid state; and, lastly, in its frozen or solidified state. When fluid, it is not in its most simple state, for its fluidity depends on a certain quantity of caloric, which enters into combination with it, and insinuating itself between the particles of the water, renders them capable of moving in all directions. -In the arts and mechanical science there are various combinations of this word as a prefix; as, Water-gauge, an instrument for measuring the depth and quantity of water;-Waterline, in nautical science, the line which distinguishes that part of a ship which is under water from that part which is above;-Water-ram, a machine by which water is raised much above its level by the momentum of a larger

a

stream than the one raised;-Waterspout, a remarkable meteorological phenomenon, which appears as a conical pillar descending from dense cloud;-Water-thermometer, an instrument for ascertaining the degree of cold at which water ceases to be condensed;-Water-wheel, a wheel of a mill moved by water; an engine for raising water out of a deep well;-Water-works, hydraulic engines or structures; artificial spouts of water.

Wa'vellite (in honour of Dr. Wavel, the discoverer), a mineral consisting of small slender crystals radiating from a centre, composed of phosphoric acid, alumina, water, fluoric acid, lime, oxides of iron and manganese: sp. gr. 333; H = 3'5—4'0. Weald, or Wealden (Dutch), in geology,

a term signifying a peculiar formation or strata of rocks, so named from the wealds of Kent or Sussex. The great wealden formation is a series of fresh-water deposits, covering an area 200 miles in length from east to west, and 220 miles from north-west to south-east, the total thickness averaging about 2,000 feet. The organic remains consist of leaves, stems, and branches of plants of a tropical character; bones of enormous reptiles of extinct genera, of crocodiles, turtles, flying reptiles, birds, and fishes. The wealden is supposed to have formed the estuary of an immense river.- Wealden clay is the blue clay which forms part of the wealden group.

Weasand (Sax.), in anatomy, the windpipe or trachea, the canal through which air passes to and from the lungs.

Wedgwood Ware, in the arts, a superior kind of earthenware, so called from its inventor, Mr. Wedgwood.— Wedgwood's pyrometer is an instrument used for ascertaining very high degrees of heat.

Wehrlite, in mineralogy, a mineral containing iron. Weighing Machine, in

mechanical science, a machine for weighing heavy bodies, and particularly wheelcarriages at turnpike gates.

Weight (Sax.), in statics, the pressure which a body exerts vertically downwards, in consequence of the action of gravity; anything to be raised, sustained, or moved by a machine. -In natural philosophy, the weight of a body is synonymous with its