Excerpt from Bow-String Bridge Ribs: A Description of Ribs Prepared for a Bridge Over the Regent's Canal, London, for the Blackwall Extension Railway

The ribs are each supported upon the piers at one end by cast-iron shoes, resting upon cast bed plates. At the other end of each rib a set of friction rollers is placed between the shoe and the bed plate, and the proper arrangements and distances left for expansion and contraction the under side of the shoe and the upper side of the bed plate being planed at both ends. The bed plates are secured to the masonry piers by wrought-iron holding-down bolts.

The connexion between the rib and the tie-bars is formed by strengthening the end of the rib next the tie-bars by the introduction of wrought-iron plates, which extend 5 feet from the bottom of the shoe, and are separated by other plates, keeping them at the proper distance, and leaving mortices for the tie-bars; so that, when the tie-bars are introduced into their places, the shoe end of the rib is one entire mass of wrought-iron. All these plates and packing are secured toge ther by wrought-iron bolts and nuts 1 inch diameter see figures 7 and 9.

Plate 1, figure 1, is an elevation of the bridge, which is on the skew, at an angle of 42 deg. 11 min. Figure 2 shows a plan of the bridge, partly with the covering on and rails laid, partly with the covering and rails removed but with timber sleepers laid in, and partly with the rails and covering and timber sleepers removed, showing only the cross girders.

Plate 2 shows a transverse section of the bridge, and various details of the parts, to an enlarged scale, the scale of each being given; figure 3 is the trans verse section; figure 4 is part longitudinal section; figure 5 is a part plan, showing the standards and cross girders; figure 6 is a section of rib and tie-bars.

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