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 side, 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 dangerous fall at low water.

In 1823 further repairs having become necessary, and the obstructions 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 21/2 years had been earned away by a sudden and extraordinary rise of the Taaf, swelled by heavy rains and considerable tributary streams; the second failed in consequence 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 segment 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 abutments, 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 218,800f. 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 152,840f. 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 engineer 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 elliptical arch of 26 feet span, over the Narrow-Wall road, and a small embankment about 165 yards long, having an easy and gradual ascent of not more than 1 foot in 34.