Page:Collier's New Encyclopedia v. 02.djvu/202

LEFT BBIDE, ST. 172 BRIDGE that class of stock brick, in which the problem of statical equilibrium assumes process of manufacture has been to the simplest form, and the conditions of largely reduce the bulk of the plastic strength and stability are steadily de- material by hydraulic pressure before termined. But when there is a shifting burning, giving to the completed brick a or rolling load on the roadway, which is smooth surface and great density of heavy in proportion to the weight of body. Pecking, place, sandal, semel the bridge, as, for example, a railway brick, are local terms applied to imper- train, the conditions are involved. When fectly burned or refuse brick. Bricks the train occupies, say, only one-half of vitrified by excessive heat are termed the bridge, the chain is depressed on one burr bricks or burrs. side, and is raised on the other side. Bricks were manufactured at a re- Thus an undulation is produced in the mote period of antiquity by the Egyp- bridge, which, especially if the train be tians, the Babylonians, the Assyrians, moving rapidly, may seriously disturb and some of them, being inscribed with the equilibrium, and even endanger the written characters, have been of price- stability of the bridge. Various corn- less value in conveying historic facts to binations have been devised to overcome the present age. About A. D. 44, bricks this difficulty. The simplest and prob- were made in England by the Romans, ably the best course is to stiffen the and in a. d. 886 by the Anglo-Saxons roadway, so that the stress ot the pass- under King Alfred. Under Henry VIII. ^^S load may be distributed over a con- and Queen Elizabeth the manufacture siderable length of chain. In this man- greatly flourished. The size was regu- "er large railway bridges have been lated by Charles I. in 1625. constructed, for example, the Roebling The following table gives the value of bridge (1855) over the Niagara, 2^ the brick output in the United States "^i^es below the falls, having a span of in 1918: 822 feet, and being 245 feet above the level of the stream. Common brick $37,208,000 mu^ xt^^^^,^^r^ ^.,^^^»r.;.>.« v«{j»^ Enameled brick 685,000 The Brooklyn suspension bridge, Vitrified paving brick 7,232,000 across the East River, between New Ornamental brick ^ oon'^^^ York and Brooklyn, opened in 1883, is rCrebr^ck ..'.'.".■.■.•.'.•.'.•.•.'.•.'.■.■.'.•.•.■. 63,637',ooo ^uilt of steel. It has a central span of 1,595% feet, and two land spans of 930 BRIDE, ST. See Bridget. feet each; making, with approaches, a BRIDEWELL, in England a house of *^?^,^^ ^^"^^ of 5,989 feet or about one correction for offenders. The name is ^^^^ ^nd one furlong. The anchorage derived from the ancient London house »* each end is a solid cubical structure of correction, originally a hospital ^f stone measuring 119 feet one founded by Edward VI. on the site of ^^^5 J^^ PU^f !^^ other, rising to a St. Bride's Well, in Blackfriars, a well ^^'S}^^ ^ ^9 H^hn^J^ ^'^ "^^t"^ kno^vn object of pilgrimage in Roman f ^^k' "^^'^hing 60,000 tons each. The Catholic times towers are 278 feet high. The weight of the whole structure suspended be- BRIDGE, a structure consisting of an ^ween the towers is nearly 7,000 tons, arch or series of arches supporting a Jhe stress of suspension is borne by roadway above it, designed to unite two four cables of 5,296 steel wires each, banks of a river or the two sides of an 15% inches in diameter. The founda- open space. A bridge is generally made tions of the towers were laid by means of wood, iron, stone, steel, or of brick, of caissons and compressed air, at a The extreme supports of the arches at level of about 80 feet below high water the two ends are called butments, or inark. The Manhattan Bridge (con- abutments; the solid parts between the structed 1901-1911) across the East arches, piers, and the fences on the sides J^^ver between New Yo_rk and Brooklyn, of the road or pathway, parapets, has a river span of 1,470 feet and a Bridges are now of many kinds, the S^V^® ^P^'^ °M^^- ,. •*, ^^ /^ nn.®^ .Tnn ; most usual varieties being the following: The Queensboro bridge _ (1901 - 1909) Suspension Bridges. — These bridges over the East River, joining New York are such in which the roadway is sus- and Long Island City, is 7,144 feet long pended from chains, links, cables or and 90 feet wide. ropes, passing over piers or towers. Cantilever Bridges. — A cantilever is a fixed or anchored at their extremities, bracket. It is a structure overhung Another line of evolution had its origin from a fixed base. The bridge across in the principle of suspension. In the the river Forth on the North British typical modern suspension bridge, when railway system is one of the largest the weight of the roadway is known by and most magnificent bridges in the the stress on the suspending links, the world. The site of the bridge is at