U'ranite, a mineral which consists of oxide of uranium, phosphoric acid, lime, magnesia and oxide of manganese, silica and oxide of iron, barytes, and water: sp. gr. 3.12.

Ura'nium, in mineralogy, a rare metal of an iron-grey colour.

Urano'chere, an ore of titanium, containing the metal in an oxidized

state.

Uranog'raphy (Gr. ouranos heaven, and grapho to describe), a description of the heavenly bodies.

Uranology (Gr. ouranos, and logos a treatise), a discourse on the heavens. Ura'nus (Gr. heaven), in astronomy, the name of the planet discovered in 1781 by Dr. Herschel, and called by him the Georgium Sidus. It is about 1,800 millions of miles distant from the sun.

Ura'o (Sp.), in chemistry, the native name of a sesquicarbonate of soda found in Mexico.

Urate, in chemistry, a salt composed of uric acid and a base.

Ur'ceolate (Lat. pitcher-shaped), in conchology, applied to shells which swell in the middle.-In botany, applied to the corolla or calyx swelling out like a pitcher.

U'rea, a principle proper to the animal urine; an organic compound found in the animal body.

Ure'ter (Gr.), in anatomy, the membranous tube which conveys the urine from the kidneys to the urinary bladder.

U'rethane, in chemistry, a white, fusible, volatile substance.

Urethra (Gr.), in anatomy, the membranous tube or canal by which the urine is voided.-Urethritis, inflammation of the urethra.

Urethrot'omy (Gr.), in surgery, incision of the urethra.

Uret'ic (Gr. ouretikos), in pathology, a medicine which increases the secretory action of the kidneys.

Uri'asis (Lat. urina urine), in pathology, the formation of urinary calculi in the animal body.

Uric (Lat. urina), in chemistry, noting

Vac'cina, Vacci'ola (Lat. vacca a cow), in pathology, the disease resulting from vaccination; cow-pox. - Vacci nation is the art or practice of inoculating with the virus of the cow-pox, which protects the individual from the malignant virus of the small-pox. Vaco'a, in commerce, the scientific name for a species of Screw Pine the

an acid obtained from urinary calculi.

Urine (Lat. urina), the water or fluid secreted by the kidneys, and collected by the bladder.-Urination is the act of secreting the urine from the kidneys. Urinometer is an instrument for ascertaining the weight "of urine.

Urocele' (Gr. ouron urine, and kele a swelling), in pathology, infiltration of urine into the tissue of the scrotum.

Uroche'zia (Gr. ouron, and chezo to evacuate), in pathology, evacuation of urine per anum. Urodyn'ia (Gr. ouron, and odyne pain), in pathology, a sense of pain in the passing of urine.

Uropla'nia (Gr.ouron, and plane error), in pathology, deviation of the urine from its usual channel.

Uros'copy (Gr. ouron, and skopeo to view), inspection of the urine for distinguishing diseases.

Ursa (Lat.), in astronomy, the name of two constellations, Ursa Major, the Great Bear, and Ursa Minor, the Lesser Bear.

Ur'sidæ, in zoology, a family of plantigrade animals.

Urtica'ceæ (Lat.), a nat. order of exogenous plants, of which Urtica, the Nettle, is the genus.

Urticaria (Lat. urtica), in pathology, a genus of cutaneous diseases. Ustula'tion (Lat. act of burning), in metallurgy, the operation of expelling one substance from another by heat.

U'terine, pertaining to the structure of the uterus or womb. Uterogesta'tion, gestation in the uterus from conception to birth. U'tricle (Lat. utriculus a little bottle), in botany, a kind of capsule resembling a small bladder.

U'vea (Lat.), in anatomy, the posterior surface of the iris in the eye. U'vula (Lat.), in anatomy, a small fleshy protuberance attached to the soft palate, and hanging over the tongue.

Pandanus utilis, which abounds in the Mauritius and Bourbon, where, from the tough fibres of the leaves, sacks for colonial produce are manufactured. Simmonds.

Vacuum (Lat.), in physics, a portion of space void of matter. - Vacuumpump is a pump attached to a marine steam-engine.

Vair (Fr.), in heraldry, a kind of fur employed in blazonry.

Valeriana'ceæ (Lat. valere to make well), a nat. order of monopetalous Exogens, consisting of annual or perennial herbs or under-shrubs, of which Valeriana is the type.

Vallec'ula (Lat. vallis a valley), in botany, the interval between the ribs in the front of umbelliferous plants. Valves (Lat. valvæ folding doors), in anatomy, membranous folds which exist at the orifices or in the course of certain cavities of the animal body, and are destined to prevent regurgitation. In conchology, a term applied to the pieces or divisions of a shell when it consists of more than one piece. In botany, a valve is the outer coat, shell, or covering of a capsule or other pericarp.-Valvate, opening by valves.

Valvula (Lat. a little valve), in anatomy, a term applied to the valvula Eustachii, a membranous semilunar valve which separates the right auricle from the inferior vena cava.

Vana'dium, in mineralogy, a rare metal remarkable for its ductility. It is soluble in nitric and nitromuriatic acids, with which it yields solutions of a fine dark blue colour.

Vanfoss, in fortification, a ditch outside of the counterscarp, usually full

of water.

Vanilla'ceæ, a nat. order of plants, of which the Vanilla, an aromatic used in confectionery, is the genus.

Van'ishing-point, in painting and perspective, the point at which an imaginary line cuts the horizon.

Vapour (Lat.), an invisible elastic fluid rendered aëriform by heat, and capable of being condensed or brought back to the liquid or solid state by cold.-Vaporization is the rapid conversion of a fluid into a vapour by heat.

Vara'nidæ (Lat. vara a pimple), a family of Lizards, the Broad-backed Saurians.

Variamen'to (Ital.), in music, a free and varied manner.

Varia'tion (Lat.), in astronomy, inequality of motion. In nautical science, the variation of the compass is the deviation of the magnetic needle from an exact parallel with the meridian. -In arithmetic and algebra, a term

applied to the different arrangements that can be made of any number of things.

Varicella (Lat. varix a distended vein), in pathology, a disease characterized by eruptions on the body; the chicken-pox.

Varicocele (Lat. and Gr.), a swelling of the veins of the spermatic cord. Varicom'phalus (Lat. varix, and Gr. omphalos the navel), in pathology, a varicose tumour of the navel. Varicose (Lat.), swelled, as a vein; diseased with dilatation. Variety (Lat. varius differing), in natural history, a plant or animal differing from the rest of its species in some accidental circumstances, which are not constant or perma

nent.

Vari'ola (Lat. small-pox), in pathology, a cutaneous disease introduced from the East into Europe about the twelfth century.

Va'riolite (Lat. and Gr.), in mineralogy, a porphyritic rock, consisting of an imperfectly crystallized aggregate of felspar and quartz.

Vari'oloid, in pathology, small-pox modified by previous inoculation. Var'iscite, in mineralogy, a reniform, green mineral.

Varix (Lat.), in pathology, a dilatation or swelling of a vein. Varnish (Low Lat. varnix), a fluid which, when spread thin upon a solid substance, becomes dry, and forms a glossy coating impervious to air and moisture.

Varvicite, in mineralogy, an ore of manganese found in Warwickshire. Vas (Lat.), in anatomy, a term applied

to arteries, ducts, veins, &c. Vascular (Lat. vasculum a vessel), having vessels that contain air or fluids. Vascular system is that part of the animal economy which relates to the blood-vessels.

Vascula'res (Lat. vasculum), in botany, a term applied to the two principal classes of plants, Exogens and Endogens, on account of their highly vascular tissues.

Vaunt'mure (Fr.), a work raised before the main wall of a fort.

Vauque'linite (so called from auquelin, the French chemist), a dark green or blackish mineral.

Vector (Lat.), in astronomy, a line conceived to be drawn from the centre of a planet to the centre of the sun; called also radius vector.

Vegetable (Lat. vigeo to grow), a plant or organized body destitute of sense and voluntary motion, and fed by means of external roots. The vegetable kingdom is composed of the

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. Velocipede (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 portæ (vein of the gate), the large vein which conveys the blood from the intestines into the liver.- The venæ cave 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.

Venesection (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.

Venetian 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.

Ventricle (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 dif

ferent 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.

Verditer (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.

Vermifuge (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.

Ver'nier (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. Vertebra, 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'ide (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. vas, 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.

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

crase.

a

Vexillum (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.

Viaduct (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 223,770,000 miles, 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 Nymphæaceæ. Lindley.

Vil'larsite, a crystallized yellowish mineral, composed of silica, magnesia, protoxide of iron, protoxide of manganese, lime, potash, and water; H = 3.0-3.5.

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'ceæ (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

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 inertiæ, 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'ceæ (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.

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