Imágenes de páginas

must be allowed to cool very slowly; and especial care | brick is 2-4, giving for the weight of a solid foot 150 should be taken to lute up the doors of the fire-cham- pounds; that of common brick varies considerably, but bers and ash-pits, as well as any other openings that may be taken at 1.894, or 118 pounds per foot; of firemay exist, since a current of cold air would injure, if brick the figures are 2-201 = 137.6 pounds; of bricknot wholly destroy, the bricks with which it might work in cement, 18 = 1125 pounds, and in mortar

the come in contact.

same; of soft brick, 1:6 = 100 pounds per cubic foot. Classification. -- Bricks may be classified according Brick absorbs from 15 to its weight of water. to shape, density, methods of manufacture, position in

(L. M. H.) kiln, color, and purpose. Arch brick usually means BRIDGEPORT, a city and seaport, one of the the partly or wholly vitrified product of the arches See Vol. IV. shire-towns of Fairfield co., Conn., on Long forming the fire-boxes of the kilns. A burnt brick is p. 253 Am. Island Sound, at the mouth of the Pequonwholly vitrified. A compass brick is one shaped like a ed. (p: 284 nock River, which affords a good and com

, ed.). truncated wedge or voussoir. A capping or coping

modious haven, somewhat encumbered at brick is one used for the upper courses of a wall or for the entrance by a bar which has seldom over 14 feet a coping. Clinker, a brick from an arch of the clamp, of water. Lat. 41° 10' N., long. 73° 11' W. It is on so named from the sharp, glassy sound when struck the New York and New Haven Railroad, at the juncA feather-edged brick, one of prismatic form for arches, tion of the Housatonic Railroad. The trains of the vaults, niches, etc. Fire-bricks are made of materials Naugatuck Railroad also run to Bridgeport. It has a free from lime, magnesia, and potash, and from those regular passenger-steamboat service to New York. metallic oxides which act as fluxes. Hollow bricks are The city has very extensive and important manufacsuch as contain open spaces for ventilation or warmth. tures of firearms, sewing-machines, cartridges, hardStocks, a name given by makers to various grades, as ware, castings, axles, springs, locks, hats, machinery, gray stock, red stock. Pecking, place, sandal, salmon, carriages, and a great variety of other goods. Many semel, etc., are local terms applied to imperfectly burned of the streets are beautifully shaded, and the town has or refuse bricks. The expression air-brick denotes a a large number of fine houses and churches, including grating let into the wall for ventilation.

places of worship for all the leading denominations. Measuring.–Brick-work is generally measured by There are five national and three savings banks, three the thousand bricks laid in the wall, but sometimes by daily, one semi-weekly, and three weekly newspapers, the perch. There are various methods of estimating systems of public and Catholic schools, a city high the number of bricks in any given work, and the con- school, a training school, and a good library, a Catholic ventionalities adopted in the several sections of the academy and convent; also the Golden Hill Academy country are known as “constructive measurements." and a ladies' seminary. Bridgeport has street railways, The general practice is to allow a certain number of an opera-house, four public halls, two good hotels, and bricks to each square foot of wall-surface, the number all of the conveniences of a large city. It is principally varying with the thickness. The figures generally ac- built on the west side of the river, that part which lies cepted are—for a 44-inch wall

, 7 bricks per square foot; E. of the river being locally known as East Bridgeport. for a 9-inch wall, 14 bricks; for a 13-inch wall, 21 bricks; The city has important fishing and oystering interests. and so on in multiples of seven for each half brick add- Population, in 1870, 18,969 ; in 1880, of the city, ed to the thickness. It is customary in brick walls to 27,643; of the township, 29,148. It ranks as the third deduct all openings for doors, windows, arches, gate city of the State in population, and the seventy-first in ways, etc., but not for flues, ends of joists, trimmers, or the United States. The city in 1880 contained 20,204 girders, nor for the boxes of window-frames, nor any natives of the United States and 7439 foreigners; 443 sills or lintels, account being taken of the extra labor persons were of African descent. There were 3735 in setting and the waste in laying.

dwellings, with an average of 7:4 persons to a dwellTo find the number of bricks required for a wall of ing. Bridgeport's history does not extend beyond 1821, given dimensions, allow one-tenth of the volume for when the town was organized, the city charter dating mortar and deduct all apertures. Brick-work in tun- from 1836. Its recent growth has been extremely nels and arches is usually measured by the cubic yard. rapid. It requires 38 bricks, 81x4x2, with joints from to } BRIDGEPORT, an incorporated village of Belmont inch wide, to lay one square yard if placed flat; if on co., Ohio, is on the Ohio River opposite Wheeling, W, edge it will take 73, and on end 149. Bricklaying, in- Va. It is on the Cleveland and Pittsburg Railroad and cluding mortar and scaffolding, will average for an en- the Cleveland, Tuscarawas Valley, and Wheeling Railtire dwelling $8 per M. The best pressed bricks in road. The Ohio River is here crossed by a suspension first-class work will cost from $15 to $20.

bridge, and there are three others over Wheeling Creek. Sizes of Bricks.-In Cuba the moulds are said to be Bridgeport has four hotels, a national bank, five 11*5£*25 inches; contents, 159 cubic inches; in churches, four schools, two flour-mills, two iron-mills, South America, 124 61x25, or nearly 200 cubic inches. two glass-works, a stove-foundry, planing-mill, machineThe British standard size, as fixed by law, is 8* *43*23 shop, and barrel-factory. There are three veins of coal inches, which gives a volume of 105} cubic inches. In underlying the adjoining country, and extensive coalthe United States the sizes vary considerably, the aver- works are close to the town. It was settled in 1806 and age being about 84 x 4 x2), containing 85 cubic inches, incorporated in 1836, but has only begun to grow rapidly or twenty bricks to the cubic foot, whilst a cubic yard since 1870. Its property is valued at $850,000; its is assumed to contain 600 instead of 540, and a perch public debt is $4700, and its expenses for 1881 were of 22 feet is reckoned as 500 bricks laid in the wall

. In $8000. Population, 2395. the Eastern States a common size is 81x6x2 inches BRIDGEPORT, a borough of Montgomery co., Pa., (= 981 cubic inches), which is less than the size of is pleasantly situated on the Schuylkill River opposite the Cuban brick. In some places 8x28x14 is not an Norristown, 16 miles N. W. of Philadelphia. It is the unusual size; it contains only 38} cubic inches. Stock eastern terminus of the Chester Valley Railroad, which or place bricks commonly measure 83x4+x24 inches, connects here with the Philadelphia and Reading Railand weigh from 5 to 6 pounds each. Paving bricks road. It has two churches, two hotels, one foundry, should measure 9x41x14 inches, and weigh from 4 to three woollen-mills, two paper-mills, and gas-works. 44 pounds. Of this size 1 yard of paving requires 36 There are extensive lime-kilns in the vicinity. Two bricks laid flat, or 82 on edge. Of stock bricks 52 will bridges across the Schuylkill connect this place with be required if laid on edge. A good hand-moulded Norristown. It is surrounded by beautiful scenery. brick of 81 x 4x2 will weigh about 44 pounds, or 118 It was settled about 1760 and incorporated in 1851. Its pounds per cubic foot, or 1.4223 tons per cubic yard, property is valued at $700,000, and its public debt is giving 500 to a ton. Machine-pressed bricks weigh $13,700. Many of the inhabitants are of Swedish deabout 5 pounds each. The specific gravity of pressed scent. Population, 1802.

VOL. I.-20

See Vol.
IV. p. 253

BRIDGES. BRIDGES may be classified with reference to their in twelve years), St, Esprit, and Lyons, which are con

they may be of stone, wood, iron, of wood many places, making unequal angles, especially where

and iron (called "combination "'), and of the stream is strongest. Old London Bridge, which Am. ed. p. steel. According to the second, they may was begun in 1176 and required thirty-three years for

Edin. be classified as truss, arch, girder, suspen- completion, had nineteen arches and a great pier in the ed.).

sion, tubular, pile, pontoon, draw, lift, centre, intended for a steadying of the whole structure, swing, bowstring, etc. They are also designated by instead of making an angle, as in the above-mentioned the relative position of the grade and other surface bridges. passed over as undergrade, overhead, through, half- Among ancient bridges mention is made of a bridge through or low, and deck; or, with reference to the of a single arch in the city of Mostar, in Bosnia, angle between the intersecting ways of communication, much bolder than that of the Rialto in Venice. But as right or askew. Bridges of special construction are these are both excelled by a bridge in China, built sometimes designated by the name of their patentee, from one mountain to another, consisting of one single as the Burr, Town, Long, etc. The first method of semicircular arch 400 cubits (600 feet) long and 500 classification is used in this article, as it conforms most cubits (750 feet) high, whence it is called “the flying closely with the history of bridges, and also enables us bridge.” “The stones which form the archivolt are to illustrate the various subdivisions of the second from 7 to 12 feet in length. The voussoirs are intramethod.

dossed and extradossed from a centre like unto the Until the last half century bridge-building was arches in Europe" (Thomas Pope's Treatise on Bridge merely an art which its masters applied in conformity Architecture, N. Y., 1811). Kircher also speaks of a with their common sense, experience, and observation. bridge in the same country 360 perches long, without The materials employed were those furnished by nature, an arch, supported only by 300 pillars. as wood and stone wrought into proper shape, at great The next longest single span of which any record reexpense and with much labor, by hand tools, and put mains was the bridge of Trezzo, built about 1380 by in place by the aid of heavy staging. No effort was order of Barnabo Visconti, duke of Milan. It was made to compute the strength of the several parts of afterwards destroyed by Carmagnola. It consisted of a bridge, but each constructor modelled his design and a single arch of granite, very well constructed of stones proportioned his details generally upon the precedents in two courses ; the innermost, 31 feet thick in the dialready established. The stone arch and the wooden rection of the radius ; the outermost, 9 inches. The truss were simply the result of intelligent observation span at low water was 251 feet, being the longest sinand centuries of practice.

gle-span arch on record, except that in China, of Squire Whipple (1847) and H. Haupt (1851) were which no very authentic data remain. The rise at the first American writers on the science of bridge- the crown from the surface of low water, which was construction. Their methods and researches were con- also the position of the springing lines, was 87 feet 93 ducted independently, and their results have furnished inches. The radius of the segment was 133 feet 0-5 an invaluable basis for the great progress which has of inches. There remains about 24 feet of the arch near late years been made both in the theory and practice the haunches. It is supposed to have been surmounted of this branch of the profession.

by a crenellated balustrade terminating in two towers In England the first purely theoretical writer on this with battlements. subject was R. H. Bow (Nov., 1850), although data of The Horseshoe Bend or Conemaugh Viaduct (fig. 1), a similar character had been published in the cor- built about 1833, is still standing, and is used by the respondence of Messrs. Stephenson, Fairbairn, Hodg- Pennsylvania Railroad Company as a part of its main kinson, and by Kirkaldy and Barlow, who contributed greatly to the development of iron bridgebuilding through their extensive experiments on the strength of materials in 1845 and subsequently.

Stone Bridges. -Stone bridges may be said to date from the period when man instinctively placed stepping stones in a stream, forming miniature piers in the shallow water. To trace the development of this class of bridges would necessitate an expansion far beyond our limits. We shall therefore merely refer to some of the most important structures of ancient and modern times, and especially since the introduction of railways.

The town of Alcantara (“the bridge"), in Spain, derives its name from the magnificent Roman bridge which there spans the Tagus. It was erected about A. D. 104, in honor of the emperor Trajan, of blocks of granite without cement, and consisted, until its partial destruction, of six arches of various spans. The total length was 670 feet, and height 210. "The second arch on the right bank was blown up by the English in 1809, and its temporary substitute was again destroyed in 1836 to prevent the passage of the Carlist troops. At present only one arch, 40 feet high, remains.

It was the practice in some countries to bow the bridge, in plan, up stream, to resist the rush of floods

Fig. 1.--Conemaugh Viaduct, Pennsylvania R. R. more forcibly. Examples of such structures are found line. It is a substantial and imposing piece of masonry: in the bridges of Avignon (one of which, having eighteen about 75 feet high and with a semicircular arch of 80 arches, was begun by St. Benezet in 1177, and finished feet span. The arch is 31 feet thick at the springing


[merged small][ocr errors]

nne, and 3 feet at the crown; the arch-stones are of there were 3713 cubic yards of stone thrown around
light-colored sandstone, and the backing of silicious the foundations of one of the abutments and of several
limestone found near the spot. The sandstone was of the piers, costing $5973, thus bringing the total cost
split from the erratic blocks, often of great size, which up to $127,690. This work, built after the plans of
were found lying in the woods on the surface of the Mr. B. H. Latrobe, architect, of Baltimore, was com-
ground. The contract price for the masonry was $4.20 menced July 4, 1833, and completed July 4, 1835.
per perch of 25 cubic feet, and the work was remark- The largest existing masonry arch in England is
ably well done. The face-stones were laid in mortar probably that over the Dee at Chester, of 200 feet
made from the silicious limestone, without the addi- span and 42 feet rise. The arch-stones at the crown
tion of any sand. The cost of the viaduct was about are 4 feet 6 inches deep and 7 feet at the springing.
$55,000. Since the completion of that work iron The largest in America is that over Cabin John
bridges have in general taken the place of such struc- Creek, on the Washington Aqueduct, which has a

span of 220 feet and versed sine of 571 feet, the radius The most remarkable structure in rustic work (rubble being 134.2852 feet. The height of the crown above masonry) is a bridge formerly called the Thomas Viaduct, the water is 101 feet. The thickness at this point is 4 now known as the Carrollton Viaduct (fig. 2), upon feet 2 inches, and at the springing 6 feet 2 inches. which the railroad from Baltimore to Washington crosses One of the longest viaducts of early railroad conthe Patapsco at a distance of 8} miles from the former struction in England is that on the London and Greencity. Including the abutments, it has a length of 704 wich Railway, which is 3 miles and 60 chains long, feet 34 inches. The crowns of the arches are 60 feet laid on more than 1000 arches of yellow brick ; 18 feet above the level of low water, and if their thickness of span, 22 feet high, 25 feet wide. It was opened in 6 feet be added, we obtain the height of the roadway. I 1838, at a cost of $1,300,000 per mile, a large portion

of which was consumed in extinguishing title to property.

Another viaduct, on_the London and Blackwall Railway, built in the same manner, is 3 miles 38 chains long, and cost $5,419,755.

Two beautiful masonry structures have recently been erected on the Saxon-Bavarian State Railway over the Elster and Göltzsch valleys, of which the following is a brief description: The Elster Valley bridge, situated about halfway between Elsterberg and Plauen (shown in fig. 3), consists of two tiers of masonry, the lower one of which is 110 32 feet high and 550-5 feet long. It contains two double piers, with their included small arches; two cylindrical arches, each of 95-16 feet span; and two retaining, walls. The spans of the small arches are 23 feet. The second story, consisting of two double piers and six large

arches of 91.43 feet each, has FIG. 2.-Carrollton Viaduct.

a total length of 918 feet and The parapet is a cast-iron railing. The bridge is curved, I height of 113682 feet, making the greatest height above being in the form of an arc of a circle of radius 1273) the stream 224'15 feet. The breadth within the parfeet. The arches, however, are truly cylindrical, as apets is 26.12 feet. This bridge was begun May 31, the horizontal section of the piers is trapezoidal in- 1846, and completed July 15, 1851, under the superstead of rectangular. There are eight full centre arches vision of R. Wilke, consulting engineer, and H. Kell, of 58 feet 4 inches span. The thickness of the piers resident engineer. along the short side of the trapezoid, at the springing The arcade over the Göltzsch valley, erected at the lines of the arches, is 10 feet. The greater part of same time, is a still more extensive structure, consistthis bridge was constructed out of granite from a quarry ing of four stories, as shown in fig. 4. Its total length at a distance of 12 miles on the line of the railroad. is 1900-46 feet, breadth between parapets 26'12 feet. The courses are laid with sufficient regularity. The Greatest height above water, 263-58 feet; greatest stones are from 3 to 4 feet long, 14 to 2 feet wide, and height above the bed of the foundation, 303-27 feet. 1 to 2 feet thick. The arches are of a different granite, The large arch of the lowest story has a span of 94-25 of a more uniform grain, and without feldspathic crys- feet, while that of the upper is 10174 feet. The clear tals. The youssoirs measure from 1 foot 2 inches to height of the crown of the lower is 136'2 feet, and that 1 foot 6 inches along the intrados, about 2 feet 6 inches of the upper from the deck plane of the lower arch is in height, and from 3 to 4 feet in the length of the axis: 1045 feet. The thickness of the lower arch is 7.8 feet, of the arch. The foundation is of stone without mortar, and that of the upper 7:4 feet. all in large pieces. It rests upon the rock, which during The span of the smaller arches, which are built open, the summer is nearly level with the surface of the water. is 42:0 feet in the lower story. In the second story The base of the piers is surrounded by stones of a smaller there are seventeen single piers, in the third twentysize (rip-rap). The bridge, including a large retaining- two, and in the fourth twenty-two, and the cost was wall at its southern extremity, contains 18,195 cubic $1,680,000. yards of masonry, and cost $121,717; thus making Amongst the most celebrated masonry viaducts in the mean cost per cubic yard $6.69. In addition, America is that on the Erie (now New York, Lake

[graphic][ocr errors]

Fig. 3.-Elsterthal Bridge, Saxon-Bavarian State Railway. Erie, and Western) Railroad, over the Starucca Creek, | Philadelphia (built 1872–73), presents some novel feanear its junction with the Susquehanna River. This tures in masonry arches worthy of notice. As the axis bridge is 110 feet high and 1200 feet long.

of the bridge is inclined to the centre-line of South The eastern approach to the South Street Bridge, / Street at an angle of 33° 25', the change of direction

[ocr errors]

FIG. 4.-Göltzschthal Bridge. was made by introducing three right conoidal arches at located on a radial line of the curve. The spans of the the east end (fig. 5). The head-walls are concentric arches are equal, the inner chord measuring 22 feet 1 cylinders with radii of 142 and 197 feet, making the inch, and the outer 32 feet of inches, the rise throughroadway, or length of arches and piers, 55 feet from out being 11 feet 04 inch, as the springing line and out to out. The piers are rectangular in plan, 55 x crown are horizontal. Only the head-walls are of cut 5.5 feet, and 12 feet high. They are of Port De- stone, the soffit being filled in with brick-work. posit granite, rock-faced ashlar, laid in courses from One of the best examples of stone-arch bridges in 17 to 27 inches rise. The centre-line of each pier was America is that spanning the Wissahickon on the line

of the Philadelphia and Reading Railroad, Norristown obliquely to the faces of its abutments. Formerly such branch. It is built of talcose slate, and consists of five bridges were generally built of masonry, and those porlarge, full-centre spans of 65 feet each, and four smaller tions of the arches at the acute angles were not resisted ones. The grade is 79 feet above the level of the creek. and upheld by a corresponding mass of masonry on the

opposite side of the arch. This rendered a modification necessary in the bond or form of joints, leading to great difficulty in cutting them normal to the pressures, and also to a waste of material. The English, or Buck's, and the French systems of overcoming this difficulty are explained in the article on Arch in ENCYCLOPÆDIA BRITANNICA. A simpler method, however, exists, which can readily be executed by any ordinary mason. It consists in dividing the arch into a series of ring courses by planes passed parallel to the end-walls or “heads,'' and sliding these sections back until the proper angle of obliquity is obtained (fig. 6). Thus they will

[ocr errors]




Fig. 6.- Askew Arch on Philadelphia and Reading R. R.

have the same span and rise, but the bond is less perfect FIG. 5.- Eastern approach to South Street Bridge, Phila- in consequence of the interior soffit being broken, as it delphia, Pa.

were, into steps. As, however, each segment is a right The bridge is 492 feet long, 28 feet wide, and contains arch, and the pressure is normal to the joints and bearabout 15,000 cubic yards of masonry. It was begun ings, the advantages are so great that appearance is in May, 1881, and completed Dec. 1, 1882, at a cost sacrificed for utility, safety, and economy. of about $375,000.

The only instance believed to exist in America of an Askew Bridges.-It frequently happens that two askew arch with helicoidal joints, as described by Mr. lines of communication do not intersect at right angles, Buck, is that on the Lebanon Valley (now Philadelphia in which case the bridge crossing one of them is placed and Reading) Railroad over Sixth Street in Reading, Pa.

[graphic][ocr errors][merged small][merged small]

FIG. 7. It was built in 1856-58 by Richard B. Osborn, C. E., on a line, making, with the head-walls, an angle of under great difficulties, as it was almost impossible to 21° 30', which is the angle of the stream with the line secure masons who could prepare the templates and of the bridge. It was built about 1854 by J. Dutton apply them to the joints. This form of arch is clearly Steel, C. E. illustrated in fig. 7.

WOODEN BRIDGES. The present practice for oblique crossings is to use some form of wooden or iron truss, supported, when One of the most striking instances of the early applipossible, upon iron columns and abutments.

cation of science to the construction of wooden bridges The masonry bridge crossing

the Schuylkill River on was that of the famous structure spanning the Rhine at the Philadelphia and Reading Railroad at the Falls of Schaffhausen, erected by Ulric Grubenmann, a common Schuylkill is an example of an askew arch built of seg- carpenter of Teuffen, in 1758. This bridge, 364 feet ments of circles, as shown in fig. 6. In this bridge long and 18 wide, was destroyed by the French in there are six arches, each having a span of 83 feet and April, 1799. But this structure, with its two spans, a rise of 26 feet. The exterior walls are of rock-faced was surpassed in boldness by the one over the Limmat ashlar. There are eight segments in the length of each at Wettingen, near Baden, which had a clear span of arth, so “stepped off” in plan that the front edges are 368 feet. It was built by the same Ulric Grubenmann,

« AnteriorContinuar »