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consequently, a rib 1 foot 1, by 1 foot 6 in. Thecentral ribs, fig. 14, are formed of seven piecesof like dimensions. Twenty-one cross-pieces,1, 2, 3, 4, &c. fig. 12, are laid athwart theupper surfaces of the ribs, (which are set pa-rallel to each other upon stone piers, S, fig. 12,13, and 14,) dividing the arches, longitudinally,into twenty-two equal parts, fig. 13, eleven ofwhich are shown in the half arch, fig. 12. Atthe several parts, 1, 2, 3, &c. the ribs are per-forated, through the middle of their substance,and iron bars set through, to which are sus-pended the beams B, fig. 12, upon which thefloor rests; and each half rib is braced dia-gonally towards it’s centre, by four braces c, c,fastened by iron straps, to the rib at one end,and to the tie-beam B. These braces serve tocounteract the outward thrusts which the archeswould otherwise exert from the weights sus-pended to them. The road-ways, fig. 15, areeach nine feet ten inches wide, with a pathfour feet ten inches wide, on each side, for footpassengers. A light framing is constructedover each of the stone piers, fig. 13, to makegood the roofing; and in this bridge, as in allthe others I have mentioned, the whole is madeweather-tight.

Fig. 16, plate 12, is an elevation of the cele-