Norfolk Gazette And Publick Ledger

Cast Iron Bridge over the Thames.

The arch of this elegant structure is the flattest segment ever built on a large scale, being a segment of a circle of 252 feet diameter, the chord or span 180, and the versed sine or height 16 feet; it springs from abutments of stone built on piles, and is 27 feet 2 inches in breadth; it consists of 6 ribs, placed 5 feet asunder, kept in their position by perforated cross-bars placed horizontally at the top and bottom of each piece, quite across the bridge; each of the ribs is composed of 39 arch-pieces, 4 feet 7 and a quarter inches long at top, and 4 feet 6 3/8 inches at bottom, 4 feet deep, and 4 1/4 inches thick; they are cast hollow, for the purpose of introducing dowels 4 1/3 inches wide, and 2 inches thick: through these dowels, and also the arch-pieces, are cast holes, into which wedges are driven, which bring the parts into close contact and very considerably lessen the shoot or thrust of the arch. The spandrels are filled up with circles, which diminish from the abutments to the centre: the whole is covered with plates one inch thick, and 2 feet broad, on the ends of which rest the panels, on which the balustrade is placed. The whole weight of iron is 270 tons, of which the covering plates weigh 100--the bridge was cast by the Walkers of Rotherham, on an improved plan, for the invention of which his majesty has been graciously pleased to grant his royal letters patent to Mr. T. Wilson, engineer, of Wearmouth bridge, under whose direction the whole iron-work was thrown across the river Thames, and completed in less than six months.

The first day the bridge was opened for public use, the commissioners had the pleasure of seeing 160 fat oxen, 10 horses, and a great number of people upon the bridge at the same time, without producing the least effect upon it; although the trotting of a horse makes it vibrate. The king and royal family passed over in the first four coaches, drawn by four horses each.