Boarding-joists, joists in naked flooring, to which the boards are fixed. Boarding-pike, a pike used by sailors in boarding an enemy's vessel. Boating, in masonry, the paring of a stone with a broad chisel and mallet. Boasting, in sculpture or carving, is the rough cutting of a stone to form the outline of a statue or ornament. Boats, small open vessels, impelled on the water by rowing or sailing, having different uses, dimensions, etc., either for river or sea service. Boat-hook, an iron hook with a sharp point, fixed on a pole, at the extremity. Boatswain, a warrant officer in the navy, who has the charge of the rigging, and calls the crew to duty. Bob, the miner's engine-beam. Bob, of a pendulum, is the metallic weight which is attached to the lower extremity of a pendulum-rod. Bobstay-holes, those in the fore-part of the knee of the head, for the security of the bobstay. Bob-stays, used to confine the bowsprit down to the stem or the cutwater. Bocatorium, anciently a slaughter| house. Bodium, a crypt, or subterraneous chapel. Body, in physics or natural philoso phy, any solid or extended palpable substance. Body, or solid, in geometry, has three dimensions, length, breadth, and thickness. Bodies are either hard, soft, or elastic. Body-plan, in naval architectural drawing, sectional parts showing fore and after parts of a vessel. Boeria, anciently a manor-house or large country dwelling. Bog, soft, marshy, and spongy matter, or quagmire. Railroads have been made across bogs in Lancashire and in America, by draining, etc., and in the latter by piling as well as draining. Bog-iron ore, an iron ore discoverable in boggy land. Boiler, a wrought-iron vessel containing water, to which heat is applied for the generation of steam. Boilers are made of various forms, according to the nature of their application, and are constructed so as to obtain the largest heating surface with the least cubical content. Boilers. Aboiler for 20-horse power is usually 15 feet long and 6 feet wide; therefore 90 feet of surface, or 4 feet to 1-horse power; a boiler for 14-horse power, 60 feet of surface, or 4.3 feet to 1-horse power; but engineers allow 5 feet of surface to 1-horse power, and Mr. Hicks, of Bolton, proportions his boilers at the rate of 54 square feet of horizontal surface of water to each horsepower: Mr. Watt allows 25 cubic feet of space to each horse-power. Boilers. Iron cement is far preferable to any other material for making iron joints it has the excellent property, that it becomes more sound and tight the longer it stands, so that cemented joints which at first may be a little leaky, soon become perfectly tight. The following is the best mode of preparing this iron cement: take 16 parts of iron filings, free from rust; 3 parts powdered sal-ammoniac (muriate of ammonia); and 2 parts of flower of sulphur mix all together intimately, and preserve the compound in a stoppered vessel, kept in a dry place, until it is wanted for use. Then take 1 part of the mixture, add it to 12 parts of clean iron filings, and mix this new compound with so much water as will bring it to the consistence of a paste, having previously added to the water a few drops of sulphuric acid. Instead of filings of hammered iron, filings, turnings, or borings of cast iron may be used; cement, however, made entirely of cast iron is not so tenacious and firm as if of wrought iron; it sooner crumbles and breaks away. It is better to add a certain quantity, at least onethird, of the latter to the former. : There is but little ground to fear for the soundness of a well-riveted iron boiler; for in time the action of rust and deposit will stop almost any crevices. In order, however, to take all precaution, it is to be recommended that some clammy substance, such as horse-dung, bran, coarse meal, or potatoes, should be boiled in the vessel before it is used. A very small quantity also of the same kind of substance may be put into the boiler when first set to work this will find its way into the crevices by the pressure within, and, gradually hardening, will soon render the vessel perfectly sound. Boilers. Copper is more tough and less liable to crack than iron, and is a most excellent material for high-pressure boilers: it has, however, a less cohesive power; and therefore a greater thickness of metal is necessary to produce an equal strength but since copper boilers never fly in pieces in case of explosion, it is not necessary to be too scrupulous in regard to this point. Even when the metal is thin, especially if the diameter is not great, the use of copper removes all danger of destructive explosion, since at most only a simple tearing asunder of the metal will ensue. Boiling, or ebullition, the agitation of fluids, arising from the action of fire, etc. Bole, an argillaceous mineral, having a conchoidal fracture, an internal lustre, and a shining streak. Bollards, large posts set in the ground at each side of the docks, to lash and secure hawsers for docking and undocking ships. Bollard timbers, in a ship, two tim bers within the stern, one on each side of the bowsprit, to secure its end. Bolognese School, in painting, a Lombard school, founded by Caracci. Bolognese School, the great painters of which were,-Francia Agostino, b. 1558, d. 1601; Domenichino, b. 1581, d. 1641; Guido Remi, b. 1575, d. 1642; Gio. Lanfranco, b. 1678, d. 1744; Ludovico Caracci, b. 1555, d. 1619; Annibale Caracci, b. 1560, d. 1609; Francesco Albani, b. 1578, d. 1660; Guercino, b. 1590, d. 1666. Bolognian stone is derived from sulphate of baryta by calcination and exposure to the rays of the sun. Bolster, a piece of timber placed upon the upper or lower cheek, worked up about half the depth of the hawse-holes, and cut away for the easement of the cable, and to prevent its rubbing the cheek; likewise the solid piece of timber that is bolted to the ship's side, on which the stantients for the linings of the anchors are placed; or any other small piece fixed under the gunwale, to prevent the main sheet from being rubbed, etc. Bolster, a tool used for punching Bolt, a cylindrical pin of iron or other metal, used for various purposes of fastening, planking, etc. Bolt-auger, an auger of a large size, used by shipbuilders. Bolt-rope, the rope to which the edges of sails are sewed, to strengthen them. Bolt-screwing machine, a machine for screwing bolts, by fixing the bolthead to a revolving chuck, and causing the end which it is required to screw to enter a set of dies, which advance as the bolt revolves, Bolts, large iron pins. Bolts, long cylindrical bars of iron or copper, used to secure or unite the different parts of a vessel; the principal ironwork for fastening and securing the ship. Bomb-vessel, a strong-built vessel carrying heavy metal for bombardment. Bomb-ketch, a ship or vessel built with large beams, for carrying and raising of mortars at sea. Bonarroti (Michelangiolo), born 1474, pupil of Domenico Ghir ! 1 landajo,-painter, sculptor, and architect: the most eminent of his country for his very great acquirements in the arts in which be so eminently practised. Bond, in masonry, is that connection of lapping the stones upon one another in the carrying up of the work so as to form an inseparable mass of building. Bond, in bricklaying and masonry, is the arrangement or placing of bricks, etc., so as to form a secure mass of building. Bonders, Bond-stones, Binding stones, stones which reach a considerable distance into, or entirely through, a wall, for the purpose of binding it together. Bond stones, are placed in the thick Bess of a wall, at right-angles to its face, to bind securely together. Bond, in carpentry, a term among workmen, to make good bond by fastening two or more pieces together, either tenoned, mortising, or dovetailing. Bond timber, pieces of timber used to bind in brickwork especially. The naked flooring being laid, in carrying up the second story bond timbers must be introduced opposite to all horizontal mouldings, as bases and surfaces. It is also customary to put a row of bond timber in the middle of the story, of greater strength than those for the bases and surfaces. Bongrace (a sea term), is a frame of oid ropes or junks of cables, laid at the bows, sterns, and sides of ships sailing in cold latitudes, to preserve them from damage by flakes of ice. Bone-brown and Ivory-brown, produced by torrefying or roasting bone and ivory, till, by partial charring, they become of a brown colour throughout. Boning, in carpentry and masonry, the art of making a plane surface by the guidance of the eye: joiners try up their work by boning with two straight-edges, which determine whether it be in or out of winding, that is to say, whether the surface be twisted or a plane. Bonnet, in navigation, an additional piece of canvas attached to the foot of a jib, or a schooner's foresail, by lacings, taken off in bad weather. Bonnets, the cast-iron plates which cover the openings in the valvechambers of a pump: the openings are made so that ready access can be had when the valves need repairing. Bonney (mining), a distinct bed of ore, that communicates with no vein. Bonnington. In landscape his practice was to sketch in the outline and general character, and then make accurate studies of the local light and shade and colour. Boom, in ship-building, a long pole run out from different places in the ship, to extend the bottoms of particular sails, as jib-boom, flyingjib-boom, studding-sail-boom, etc. Boomkin, in ship-building, a beam of timber projecting from each bow of a ship, to extend the clue or lower corner of the foresail to windward. Boor, a parlour, bedchamber, or in ner room. Booth, a stall or standing in a fair or market. Boot-topping, scraping off the grease, or other matter, which may be on a vessel's bottom, and daubing it over with tallow. Borax, in chemistry, a salt in appear ance like crystals of alum; an artificial salt used for soldering metals. Borcer, an instrument of iron, steelpointed, to bore holes in large rocks, in order to blow them up with gunpowder. Bord, anciently a cottage. Bore, in hydrography, a sudden and abrupt influx of the tide into a river or narrow strait. Boreas, the north wind. Borer, a boring instrument, with a piece of steel at the end, called a boring-bolt. Boring, the art of perforating or mak ing a hole through any solid body; as boring the earth for water; boring water-pipes, either wood, iron, zinc, or lead; boring cannon, etc. Boring. Modern steam-engines depend on the improved method of boring their cylinders. The cylinder to be bored is firmly fixed with its axis parallel to the direction in which the borer is to move: the cutting apparatus moves along a bar of iron accurately turned to a cylindrical form. Boring-bar, a bar of a small horizontal boring-machine: it is used for boring the brasses of plummer-blocks, by means of a cutter fixed in it. Boring-collar, in turning, a machine having a plate with conical holes of different diameters: the plate is movable upon a centre, which is equidistant from the centres or axes of the conical holes; the axes are placed in the circumference of a circle. The use of the boringcollar is to support the end of a long body that is to be turned hollow, and which would otherwise be too long to be supported by a chuck. Boring-lathe, a lathe used for boring wheels or short cylinders. The wheel or cylinder is fixed on a large chuck, screwed to the mandril of a lathe. Boring-machine, a machine for turning the inside of a cylinder. Boromino (F.), born in Bissano, near the Lago di Lugano, in 1509. He was architect in the service of the family of the Vconti, and was architect of superb taste; many of his buildings are finely portrayed in M. Letarouilly's great work on Rome. Boron, in chemistry, is an olive-green powder, which, heated out of the air, becomes harder, and darker in colour it burns brilliantly when heated in air or oxygen, forming boracic acid. : Bosco (Jean de Sacro), a celebrated mathematician of the thirteenth century, who was so called from Holywood, a town in England of that name, which was his birth-place. After studying in the University of Oxford, he went to Paris and acquired great reputation by his knowledge of mathematics. He has left two works, valuable for their time, one entitled, De Sphæra Mundi;' the other, 'De Computo Ecclesiastico.' They are printed in one volume. Boss, a sculptured keystone or carved piece of wood, or moulded plaster, placed at intervals of ribs or groins in vaulted and flat roofs of Gothic structures. Boss, a short trough for holding mortar when tiling a roof: it is hung to the laths. Bossage, projecting stones laid rough in building, to be afterwards cut into mouldings or ornaments. Bosquet, a French expression for a piece of ground in gardens, enclosed by a palisade or high hedgerow of trees, etc. Botany Bay oak, resembling in colour full red mahogany, is used as veneer for the backs of brushes, turnery, etc. Bottle-glass, a composition of sand and lime, clay, and alkaline ashes of any kind. Bottom-captain, a superintendent over the miners in the bottoms. Bottom-heat, artificial temperature, produced in hothouses. Bottom-lift, in mining, the deepest or bottom tier of pumps. Bottom-rail, in joinery, the lowest rail of a door. Bottoms, in mining, the deepest working parts of a mine, wrought either by sloping, driving, or otherwise breaking the lode. Bottoms in fork. In Cornwall, when all the bottoms are unwatered, they say, 'the bottoms are in fork ;' and to draw out the water from them, or any dippa, or any other particular part of a mine, is said to be forking the water;' and when accomplished, such dippa, etc., is in fork.' Likewise when an engine has drawn out all the water, they say, the engine is in fork.' Boudoir, a small retiring-room. Boulders, fragments of rocks transported by water, and found on the sea-shore. Boulder walls, walls built of the above. Boultine, in architecture, a convex moulding, whose periphery is a quarter of a circle, next below the plinth in the Doric and Tuscan orders. Bounds, in mining, signifies the right to tin ore over a given district. Boulevard, promenades around a city, shaded by avenues of trees. Bourgeois (Nicolas), an Augustin, was the inventor of the pont-tournant. A reward of 1200 livres a year was offered to him who should invent a movable bridge to be placed over the ditch of the Tuileries. Bourse, a public edifice for the assemblage of merchants to consult on matters of business or money, an exchange. Boutant; in architecture, an arc-bou tant is an arch, or buttress, serving to sustain a vault, and which is itself sustained by some strong wall or massive pile. Bova, anciently a wine-cellar. Bovey coal, wood-coal found at Bovey, in Devonshire. Bow, the round part of a ship forward. Bow, anciently an arch or gateway. Bow-compass, for drawing arches of very large aisles; it consists of a beam of wood or brass with three long screws that bend a lath of wood or steel to any arch. The term also denotes small compasses employed in describing arcs too small to be accurately drawn by the common compasses. Bow and string bridge, or bow-string or tension bridge; in which the horizontal thrust of the arch, or trussed beam, is resisted by means of a horizontal tie attached as nearly as possible to the chord line of the arch. Bow and string beam, a beam so trussed that the tendency of the straight part to sag when loaded is counteracted to some extent by the tension upon its two ends, by a bow of wood or metal attached to those extremities. Bower cables, for ships. Table showing the different kinds of best bower cables at present employed in the British navy, with the corresponding iron cables, and the proof-strain for each: |