line drawn perpendicularly from the vertex to the base. Altitude of the eye in perspective,

a right line let fall perpendicular to the geometrical plane. Altitude of a figure in geometry, the nearest distance between the vortex or a top of that figure and its base.

Altitude, height.

Alto-rilievo, highly relieved sculpture representing figures either entirely or nearly detached from the background.

Alum, a salt extracted from various minerals called alum ores: of great use to chemists, dyers, and artists; acid and sharp to the taste. Aluminium is a metal which by uniting with oxide forms the universally distributed earth, alumina, the chief constituent of clay, and an ingredient of many gums and minerals. This metal was originally discovered in 1808, and Mr. Deville, a French chemist, has recently discovered a method of obtaining it in large pieces, and a bar of it has been presented to the Polytechnic Institution in London by the Emperor Napoleon. The metal is coming into very general use by its becoming cheap. Its colour is white, with a faint blue tinge; it is highly malleable and ductile; a perfect conductor of electricity; it melts at a temperature higher than zinc (773° Fahr.), and resists the action of sulphuretted hydrogen, of water, and of oxygen, if not heated. It is of very light weight, its specific gravity being only 2.60, that of gold being 19-26, and of iron 7·79. Alston Moor, in Northumberland. Mining in this district is of great antiquity: the miners of Alderston had their charter 600 years ago. These mines yielded gold, silver, and lead, but more of the lastnamed, and formerly belonged to Sir Edward Radcliffe, and remained in that family till the confiscation

of the estates of James, Earl of

Derwentwater, in 1716. It was granted in 1734 to the Royal Hospital for Seamen at Greenwich. In form the manor of Alston Moor nearly resembles a square of about 6 miles, containing about 45 square miles, or 29,000 acres. The mines were yielding Greenwich Hospital in 1821 a:.nually £100,000, and the lands £12,000. Alveus, in hydrography, the channel or belly of a river.

Amaasa, such pieces of glass as are used in enamelling.

Amalgam, a mixture of mercury with any other metal, tin, lead, etc. Ambitus, an enclosure: more particu

larly applied to the space around a building, as a churchyard, or a castle-yard.

Ambo, Ambone, a rostrum or raised platform.

Ambulatio, walks, or places of exercise, according to Vitruvius, adjacent to theatres. Ambulatory, a cloister, gallery, or alley.

American wood-boring tools. Some most efficient tools for boring in wood have been invented by Dr. Brown, of the United States, which appear, from the facility with which they may be worked, and the excellent character of their performance, likely to supersede entirely the old-fashioned auger' which is now in use in this country. The form of the implements has been borrowed from the boring apparatus with which the tiny insects who make such havoc in timber are provided.

Amethyst, in heraldry, is a purple colour in noblemen's coats of arms. Ammailare, to enamel.

Ammoniac, a gum used for metallic vessels.

Amphiprostyle, a term applied to a

temple with a portico in front and also behind. Amphitheatre, an edifice formed by the junction of two theatres at the proscenium, so as to admit of seats all round the periphery.

Amphitheatre, in Roman antiquity, a large edifice of an elliptic form, with a series of rising seats or benches disposed around a spacious area, called the arena, in which the combats of gladiators and wildbeasts, and other sports, were exhibited. It consisted exteriorly of a wall pierced in its circumference by two or more ranges of arcades, and interiorly of vaulted passages radiating from the exterior arcades towards the arena, and several tranverse vaulted corridors which opened a free communication to the stairs at the ends of the passage and to every other part of the building, the corridors and ranges of seats forming elliptical figures parallel to the boundary wall. Amphithura, in the Greek Church,

the veil or curtain opening to the folding doors, and dividing the chancel from the rest of the church. Amphora (pl. amphora), an earthen

vase or jar, with a handle on each side of the neck: among the ancients, the usual receptacles of olives, grapes, oil, and wine. Hence, in decoration, amphoral means, shaped like an amphora or

Anaclastics, the doctrine of refracted light.

Anaglyph, an engraved, embossed, or chased ornament.

Anaglypha, chased or embossed vessels made of bronze or the precious metals, which derived their name from the work on them being in relief, and not engraved. Anaglyphic work, a species of sculpture wherein figures are made prominent by embossing.

Analemma, a projection of the meridian; used also to designate a wall, pier, or buttress.

Analogium, a tomb over the bodies of saints; also a term formerly applied to pulpits wherein the gospels and epistles were read. Anamorphosis, a distorted piece of

perspective, occasioned by too near a point of view, and from the injudicious attitude or situation of the object, but perfectly true according to the laws of perspective. Anchor, an instrument used for the mooring of ships; in architecture, a decorative moulding used in the orders, and applied to the echinus; also an ornament in the form of the fluke of an anchor, frequently cut in the ovolo of Ionic capitals, and in the bed-mouldings of Ionic and Corinthian cornices.

Anchor-stock, in ship-building, a method of working planks, by which the abutments are to be disposed near the middle of those planks which are above or below them.

Ancon, in decoration, a carved drinking-cup or horn; an elbow or angle, or corner-stone. The Ancona foot measure is 1.282 of an English foot.

Ancone, a console or ornament cut on the key-stone of an arch. Ancones, trusses or consoles employed in the dressings of apertures; also used to signify the corners or quoins of walls, cross-beams, or rafters, etc.

Andirons, iron bars with legs to support logs of wood in fire-places. Android, in mechanics, an automaton.

Andron, an apartment, cloister, or gallery, assigned to the male part of a monastic establishment; applied also to the space in a church by which the men were separated from the women.

Anemography, a description of the winds.

Anemometer, an instrument for mea

suring the force of the wind. Anemoscope, a machine to denote the changes of the wind or weather.

Angiportum, among the ancients, a narrow lane between two rows of houses.

Angle, in geometry, the mutual inclination of two lines meeting in a point.

Angle-bar, in joinery, the upright bar

at the angle of a polygonal window.

Angle-bead, a vertical bead, commonly of wood, fixed to an exterior angle, and flush with the surface of the plaster, etc. of rooms, arches, etc. Angle-brace, in carpentry, timber fixed to the two extremities of a piece of quadrangular framing, making it to partake of the form of an octagon.

Angle-bracket, a bracket placed in

the vertex of an angle, and not at right angles with the sides. Angle-capital, used in Ionic capitals

to the flank columns which have their volutes placed at an angle of 45° with the planes of the front and returning friezes. Angle-float, in plastering, a float made

to any internal angle to the planes of both sides of a room. Angle-modillion, a modillion placed in a direction parallel to a diagonal drawn through a cornice at its mitring. Angle-staff, vertical head, generally of wood, fixed to exterior angles of a building flush with the service of the plaster.

Angle of application, the angle which the line of direction of a power gives the lever it acts upon.

Angle of inclination, the angle an inclined plane makes with the horizon. Angle of traction, the angle which the direction of a power makes with the inclined plane.

Angular modillions, those which are placed at the return of a cornice in the diagonal vertical plane, passing through the angle or mitre of the cornice. Angular perspective, a term applied to the horizontal lines, both of the front and end of a building, converging to vanishing points, and terminating in the horizon; it is sometimes called oblique perspective.

Anlace, a falchion or sword, shaped like a scythe.

Annealing, the process of softening and restoring the malleability of metals, by heating and allowing them to cool very slowly; and by which means glass, cast-iron, and steel, may be united to other sub

stances.

Annatto, in chemistry, a reddish-yellow vegetable dye, obtained from the seeds of the Bixa Orellana, and used for colouring cheese. Annicut, the Hindostanee term for a

weir or dam: it is a stoppage built out in a river from a bank, as a pier or breakwater, and made use of in the Indian rivers to intercept the current of the stream, and divert a portion of its waters into channels or reservoirs for agricultural purposes.

Annular engine, a direct-action marine engine, having two concentric cylinders; the annular space is fitted with a piston which is attached to a T-shaped cross-head by two piston-rods: the cross-head is formed by two plates with a space between for the connecting-rod to vibrate, and the lower end slides within the inner cylinder, and is connected to the crank. This arrangement has been patented by Messrs. Maudslay.

Annular vault, a vaulted roof supported on circular walls.

Annulated columns, those clustered together or joined by rings or bands. Annulet, in architecture, a small square member in the Doric capital; also the name of a small flat moulding.

Anston, a parish in Yorkshire from whence the stone used for the Houses of Parliament have been brought.

Antarala, the inner vestibule of a Hindoo temple.

Ante, square pilasters terminating the walls of a temple: when a temple had no portico in front, two columns were made to intervene between the antæ, and the aspect of the temple was said to be in antis.

Antechamber, a room or passage to

an inner chamber, for the accommodation of servants and persons in waiting. Ante-capitulum, part of a cloister before the door of a chapter-house. Antefixe (by some called Greek tiles), upright ornamental blocks placed at intervals on the cornice along the side of a roof, to conceal or rather terminate the ridges formed by the overlapping of the roof-tiles; also heads of lions, etc., for waterspouts below the eaves of temples. Antemural, a term applied to the outward wall of a castle; or that which separates a presbytery from a choir; also to a barbican entrance before a castle. Antepagmenta, or Antepagmentum, the jamb of a door-case. Ante-parallels, in geometry, lines which make equal angles with two other lines, but in a contrary direction. Ante-portico, a term sometimes used to denote an outer porch or vestibule; the propylæum in classic architecture.

Anterides, buttresses for strengthening walls.

Ante-solarium, a balcony facing the

sun.

Ante-venna, an awning or projecting

roof of woodwork; a wooden or pent-house before a shop. Anthepsa, a Grecian vessel used for boiling water or keeping it hot; a cooking utensil.

Anthracite, a coal not bituminous, found principally in South Wales and in the United States.

Antics, in architecture, figures of men, beasts, etc., placed as ornaments to buildings.

Anticum, a porch before a door. Antilia, an ancient machine similar to the modern pump.

Antimensium, a portable altar or consecrated table, used as a substitute for a proper altar. Antimeter, an optical instrument for measuring angles.

Antimony, a metal usually found in a

crude state combined with sulphur, of a bluish-white colour, crystalline texture, brittle, and easily pulverized it does not oxidate at ordinary temperatures in the air, but, when heated, it burns with a light flame, producing the oxide; it fuses at 800°, and volatilizes at a white heat.

Antimony yellow, a preparation of antimony, of a deeper colour than Naples yellow, and similar in its properties: it is principally used in enamel and porcelain painting, and is very various in tint; that of a bright colour is not affected by foul air, although blackened by sugar of lead. Antipagments, ornaments in carved work on the architrave, jambs, posts, or puncheons of doors. Antiquarium, a repository for antique monuments.

Antoine (J. D.), born in Paris in 1733 became in after-years an architect of a high position; built several noble edifices, in Paris principally; died in 1807. Antrellum, a small grave or grotto; also a small temple.

Antrum, an early temple for Christian worship.

Antrum tumbale, a sepulchral cave or grotto.

Antwerp blue, light-coloured, and somewhat brighter than Prussian blue, or ferro-prussiate of alumine, having more of the terrene basis, but all the other qualities of that pigment, except its extreme depth. Haarlem blue is a similar pigment. Antwerp brown, a preparation of asphaltum, ground in strong drying oil, by which it becomes less liable to crack.

Anvil, a large block of iron with a very hard, smooth, horizontal surface on the top, in which there is a hole at one end, for the purpose of inserting various tools, and a strong steel chisel, on which a piece of iron may be laid, and cut through by a blow with a hammer. A-peek, a nautical term implying that the cable is hove taut, so as to bring the vessel nearly over her anchor : the yards are a-peek when they are topped up by contrary lifts. Aperture, an opening in a wall, doorway, or window.

Apex, the top or highest point of a cone, mountain, pyramid, spire, roof, etc.

Apiary, a place where bees are kept. Aplome, a mineral of a deep orangecolour.

Aplustre, in early naval architecture,

a carved tablet fixed on the extremity of a ship's head, or ensign. Apodyterium, a dressing-room or anteroom to a bath in Roman villas, contiguous to the laconicum. Apophyge, in architecture, that part

of a column between the upper fillet of the base and the cylindrical shaft, which is usually curved into it by a concave sweep or inverted cavetto.

Apostles (the) of Jesus Christ were his

chief disciples, whom he invested with his authority, filled with his spirit, and instructed particularly in his doctrines and services: they were chosen to raise the edifice of his Church, and, after his resurrection, sent into all the world, commissioned to preach, to baptize, and to work miracles. The names of

the twelve were: 1, Peter; 2, Andrew; 3, John; 4, Philip; 5, James, major; 6, Bartholomew; 7, Thomas; 8, Matthew; 9, Simon; 10, Jude; 11, James, minor; 12, Judas Iscariot. The last betrayed his master, and having hanged himself, Matthias was chosen in his place. Apostles (the), in the tables of symbols of the early ages, were represented by twelve sheep or lambs issuing from Bethlehem and Jerusalem, cities of Christ's birth and death.

Apotheca, a place in the upper part of the house, in which the Romans frequently placed their wines in earthen amphora; also an apothecary's shop, a cabinet, storehouse,

etc.

Apothesis, a recess on the south side of the chancel of a church, fitted up with shelves for books, vestments, etc.

Apparatus, a term denoting a complete set of instruments belonging to an artist or a mechanist. Appian way, a celebrated road lead

ing from Rome to Brundusium: so named from Appius Claudius. Appii forum, the forum built by Appius, the Roman consul, about fifty miles distant from Rome, near the modern town of Piperno, on the way to Naples. The uses to which the Romans applied the forum were so various, that it is not easy to ascertain the nature of the building. It might have been a place for the distribution of justice, or for holding a market. The Three Taverns' were nearer to Rome than the Appii Forum, as Cicero intimates, who, in going from Rome, a little before he came to the forum of Appius, arrived at the Three Taverns; so that probably the chief number of Christians waited for the Apostle Paul at a place of refreshment, while some of their number went forward to meet him, and respecfully to acquaint him with their expectation of seeing him among them.