BRIDGE. A structure with one or more transverse apertures, raised for the convenience of passing a river, canal, valley, &c., and formed of various materials, as timber, stone, iron, &c. It is highly probable that the first bridges were composed of lintels of wood stretching from bank to bank, or, if this were impracticable, resting on piers or posts fixed in the bed of the river; and in China many considerable structures of this kind are still to be seen. As experience showed the defects of these early attempts, improved modes of construction naturally followed. In a strong current, the frequent piers or posts necessary for the support of lintels, would, by contracting the water way, Increase it to a torrent, obstructive of navigation, and ruinous to the piers themselves. In constructing bridges over rapid rivers, it would, therefore, be found essential to their stability that the openings between the supporters should be as wide as possible, and every facility given to the free passage of the water; and as this could only be effected by arches or trusses, there can be no doubt that these inventions were perfected before bridges became common. The most ancient bridges which we know of, are the work of the Romans, unless we except some of the stone bridges in China, with whose antiquity we are unacquainted; some of these latter are turned on arches in the usual manner, and others built with stones from 5 to 10 feet in length, so cut as each to form the segment of an arch. The Roman bridges generally consisted of a horizontal road, supported on one or more semicircular arches. Of the bridges of antiquity, that built by Trajan across the Danube is allowed to have been the most magnificent. It is described by Dion Cassius as consisting of twenty piers of squared stone, each of them rising 120 feet above the foundations, 60 feet in width, with a water way between every two of 170 feet, which was consequently the span of the arch, so that the whole length of the bridge was nearly 1,500 yards. It was destroyed by Adrian, lest it should afford a passage to the barbarians into the empire, and some of the piers are still to be seen near the town of Warkel, in Hungary. The next considerable Roman work of this kind is the Pont du Garde, which serves the double purpose of a bridge over the Gardon, and an aqueduct for supplying the people of Nismes with water. The bridge, which consists of six arches, is 465 feet in length, and supports a second series of eleven arches, which are con tinued beyond the extremities of the bridge, and form a junction with the slope of the mountain on each side; it is about 780 feet long. Over these is a third series of thirty-five arches, much smaller than those below, 850 feet in length, supporting a canal on a level with two mountains, along which the water is conveyed to Nismes by a continued aqueduct. This extraordinary edifice is built with very large stones, held together by iron cramps without cement, and remains in excellent preservation to the present day. The whole height is 190 feet above the lower river. We may also briefly notice the bridge of St. Esprit, near Lyons, which is of Roman origin, and is 800 yards in length; it is very crooked, and bends in several places, forming many unequal angles in those parts where the river has the strongest current. The bridge over the Tajo, at Valenza de Alcantara, about 25 miles from Madrid, built in the time of Trajan, is raised 200 feet above the water, is 670 feet in length, and consists of only six arches. Near the old town of Brionde, in the department of the Upper Loire, is a stupendous bridge of one arch, the largest with which we are acquainted. The span of the arch is 181 feet; its greatest height from the level of the water to the intrados 68 feet 8 inches; and the breadth 13. It is attributed to the Romans, The following are amongst the most celebrated bridges of modern date : The bridge of Avignon, over the Rhone, begun in 1176, and finished in 1188. It consisted of eighteen arches, and was about 1000 feet in length. It was destroyed by a violent inundation of the Rhone in 1699 ; many of the ruinous decayed arches still remain. The Rialto, at Venice, was be in 1588, and finished in 1591, after a design of Michael Angelo Bonarotti. It consists of a bold flat arch, nearly 100 feet wide, and only 23 feet in height from the level of the water. The aqueduct bridge of Alcantara, near Lisbon, begun in 1713, and finished in 1732, consists of thirty-five arches, of various dimensions ; the eighth is the grand arch, which is 108 feet 5 inches in the span, and 227 feet in height ; the other arches run from 21 feet 10 inches to 72 feet in width; the total length of the piers and arches is 2464 feet. The bridge of Neuilly, which crosses the Seine, built between the years 1768 and 1780, by M. Perrone. It is level on the top, and consists of five equal arches, 128 feet (English), with a rise of 32 feet (English). The arches, which are elliptic, are composed of 11 arcs, or circles, of different diameters. The upper portion of the arch was formed with a circle of 160 feet radius, but after removing the centres, became flattened to an aro of a circle of 259 feet radius, the rise of the curve in a length of 33 feet amounting to no more than 6 inches. The bridge of Orleans, over the Loire, built by M. Hupean, between the years 1750 and 1760. It comprises nine oval arches, described from three centres which spring at 12 inches above low water. The centre arch is 106 feet span, with a rise of 30 feet ; the others gradually decrease in width as they approach the shores. The whole length of the bridge is 1,100 feet. We shall now proceed to notice some of the most remarkable bridges in our own country, beginning with those of the greatest antiquity. The Gothic triangular bridge of Croyland, in Lincolnshire, is supposed to be the most ancient structure remaining entire in this country, and for singularity of construction and boldness of design may vie with any bridge in Europe. It was erected about the year 860, and is formed by three semicircles, whose bases stand in the circumferences of a circle, equidistant from each other, and uniting at top. The ascent on either side of the semicircular arches is by steps paved
with small stones, and so steep that foot passengers only can go over the bridge. The first bridge over the Thames at London was of wood, and was built in the reign of Ethelred II., between the years 993 and 1016 ; in 1163 it was repaired, or rather rebuilt of timber ; and in 1176 the late stone bridge was begun under Henry II., and was finished in the reign of John, A.D. 1209. It had originally twenty small locks or arches. The length was 940 feet, the height 44, and the clear width between the parapets 47 feet. In 1758 the bridge underwent a very extensive repair, and two of the centre arches were thrown into one. The piers were from 15 to 35 feet thick, with enormous starlings projecting on each aide, so that when the tide was above the starlings the greatest water way was only 540 feet, scarcely half the breadth of the river; and when the water was below them, the water way became reduced to 204 feet, causing a most dan fall at low water. In 1823 further repairs having become necessary, and which the old bridge opposed to the navigation of the river becoming the subject of much complaint, an Act of Parliament was obtained for the construction of a new bridge, of which we shall presently give a full account. The longest bridge in England is that built by Bernard, abbot of Burton, over the Trent, at Burton, in the twelfth century. It is all of squared free-stone, is strong and lofty, and is 1545 feet in length, consisting of thirty four arches. One of the most extraordinary bridges in Great Britain is that over the Taaf, in Glamorganshire, called, in Welsh, Pont y ty Prydd, built by William Edwards, an uneducated mason of the country. Two bridges which he had constructed at the same spot had failed ; the first, after standing 2; years, had been carried away by a sudden and extraordinary rise of the Taaf, swelled by heavy rains and considerable tributary streams; the second failed in con sequence of the ponderous work over the haunches forcing out the key stones before the parapet was finished. Undismayed by these misfortunes, Edwards resumed the attempt, and by means of cylindrical holes through the haunches, so reduced their weight, that there was no longer any danger from them ; and the third bridge, which he completed in 1751, has stood ever since. The present bridge consists of a single arch of 140 feet span, and 35 feet high, being a seg ment of a circle of 175 feet diameter. In each haunch there are three cylindrical openings running through from side to side. The diameter of the lowest is 9 feet, of the next 6 feet, and of the uppermost 3 feet. The width of the bridge is about 11 feet. To strengthen it horizontally, it is made widest at the abut ments, from which it contracts towards the centre by seven offsets, so that the roadway is 1 foot 9 inches wider at the extremities than in the middle. The bridge over the Thames at Westminster, was constructed by Mr. Labalye. It is 1,220 feet long, and 44 feet wide, and consists of thirteen large, and two small arches. The span of the centre arch is 76 feet, that of the next is 4 feet less; and in the others it goes on progressively decreasing 4 feet in each, except the two small arches, which are 25 feet each. The arches are semicircular, and spring from about 2 feet above low water mark, leaving a free water way of 870 feet. It was opened to the public in 1750, and cost 218,8001. Blackfriars bridge was planned and built by Mr. R. Mylne, between 1760 and 1771. It is 999 feet long, and 43 feet 6 inches wide, and has 9 elliptical arches. The centre arch is 100 feet, and the four arches on either side decrease gradually towards the shore, being 98, 93, 83, and 70 feet respectively, leaving a clear water way of 788 feet. The cost of erection amounted to 152,8401. Numerous neat and elegant stone bridges have since been erected in various parts of Great Britain and Ireland. Of these we shall briefly mention the Tees bridge, at Winston, in Yorkshire, consisting of a single arch of 108 feet span, designed by Sir T. Robinson ; one at Kiln, of five elliptical arches, of 72 feet span each; and the aqueduct bridge on the river Lune, consisting of five arches of 70 feet span, both by Mr. Rennie; Essex bridge, Sarah's bridge, and Carlisle bridge, each over the Liffey ; that at Aberdeen, designed by Mr. Telford; and another, over the Dee, by the same gentleman. But the most magnificent structure of the kind in this country, and, possibly, in Europe, is that across the Thames, nearly midway between Blackfriars and Westminster bridges, named Waterloo bridge. The project for a bridge at this part of the river originated with Mr. G. Dodd, about the year 1805, but from the opposition made by various parties whose interests were affected by the scheme, it was not until June 1809 that an Act of Parliament was obtained, incorporating a company for carrying the idea into effect ; and Mr. Rennie having been appointed engi neer to the company in June, 1810, he furnished two designs, one of seven, and the other of nine arches, the latter of which was finally approved by the committee, and ordered to be put in execution. This noble bridge has a level roadway, and contains nine elliptical arches, each having a span of 120 feet, and a rise of 35 feet, leaving a clear height of 30 feet above high water spring tides, and forming a water way of 1080 feet. The length of the bridge between the abutments is 1380 feet, and its width between the parapets 42 feet 4 inches. The roads or approaches to each end of the pier are 70 feet wide throughout, except just at the entrance from the Strand, and are carried over a series of semicircular brick arches of 16 feet span each. The approach on the Surrey side is formed by thirty-nine of these arches, besides an ellip tical arch of 26 feet span, over the Narrow-Wall road, and a small embank ment about 165 yards long, having an easy and gradual ascent of not more than 1 foot in 34.