-The whole of the works are to be under the superintend ence of the surveyor of the public works of the county of Stafford, or of such survey or or su•eepirs, person or persons, as the justices assmibled in quarter sessions shall at any time hereafter appoint. And should it appear. at any time durim: the execution of the works, that the contractor is neglecting, or doing any part contrary to the true spirit and meaning of this speeitication and drawings attached, then the magis trates shall have it in their power to take it out of his hands, and employ any other or persons to complete it ; and a hat money may remain due to him shall remain in the hands of the treasurer of the public stock of the county of Stafford till the whole work is completed ; and any loss that may be sustained through the neglect or misconduct of the said contractor, to be paid for out cif it.
" The whole of the work must be delivered, fixed, and com pleted, on or before the day of in the year "The bridge was erected in the year 1830. The total weight of won-work, which was executed by the Colebrook Dale Company, was 340 tons.
The w hole cost of the bridge was as follows : Iron-work, delivered, fixed, and completed . . .£3.800 0 0 :Masonry 3,193 0 0 Foundations, which were piled according to the most approved method ; and the ap proaches, which are of considerable length and height 2.500 0 0 Total, £9,493 0 0 We come now to the erection alone of the most celebrated structures in the world—the iron bridge over the river Thames—S01"r1IWARK BRIDGE. This splendid work crosses the water between London Brhbre and Blackfriars. The spot seems to have been well selected, and great improve ments and alterations, particularly on the Surrey side, have taken place in consequence of its erection. Southwark Bridge was built in conqiIiinWe with an act of parliament obtained by a company of proprietors in the sear 1811, but not without great opposition on the part of Sir William Curtis and others. The first stone of the south pier was laid by Lord Keith, on the 25th of May, 1815, who, with the gen tlemen of the committee of management. partook of a cold collation on a temporary bridge erected on the works, On the 7th June. 1817, the IZight Ilonourable Matthew' Wood, as Lord Mayor, laid the first stone of the northern abutment, and the works were then carried on with great. energy. The whole was completed in SI iinething less than five years, and opened to the public at midnight, in 1819.
The arches of this gigantic edifice are of the largest span of any known to exist. The soffits consist of solid 'misses of cast-iron. of a depth similar to the voussoirs of a stone bridge, and exhibit the first instance in \illicit such a bold plan has been carried into effect. The middle arch rises 24 feet, with a span of 248 feet, and is .1 feet wider than the famous iron bridge at Sunderland. It is composed of eight ribs, riveted to diagonal braces; each principal rib hieing 6 feet deep at the top of the arch, and gradually extending to ti feet at the abutments, or parts that rest upon the stone-work. Its whole height above low-water mark is 55 feet to the roadway. The other arches are similarly formed ; the span or the two side ones being 210 feet. The abutments are of solid masonry, laid in radiatil g courses. with large blocks of Brainley-fill and Whitby stones. Vertical bond was adopted, running through every two courses at intervals, thereby giving to the whole mass a solidity perfectly bninovable. The masonry of the piers, in like manner. was carried up with horizontal and vertical courses to the springing of the arches; from which points they radiate in a wedgelike form. These piers are 60 feet high from the bed of the river to the top of the parapet, and 24 feet in breadth. The foundations of this bridge were laid in cofir-dams. which were of necessity made very strong, from the irregularities of the bed of the river at this spot. The dams were elliptical in tiirm, and were constructed of three rows of piles of whole timber. In the spaces occupied by the base I if the masonry of the piers, a row of whole timber sheeting piles were driven all round the outer edp-e. of the offsets. making, as it were. a square internal dam. These piles, while they formed a secure barrier to the foundations of the piers, acted as a powerful auxiliary to the main darn in securing its base. The center ings on which the arches were turned were of very ingenious construction ; and with such skill was the whole work designed and carried into execution. that the settling of the centre arch was only 1 inch and 7-8ths. The bridge is 718 feet long between the abutments, and -12 wide 'between the parapets. The width of the roadway is 28 feet, with footways 7 feet wide on each side, The weight of metal in the Mare arch is 1,665 tons; in the side arches, 2 928. The total weight of iron in the whole structure is stated to be about 5,780 tons.