Note 138 — CHAPTER THE FIFTH

His words run as follows: “I think that it may be prudent, when designing bridges for rivers of great width, to introduce some strong piers, which in case of need may serve as abutments, putting them at distances of three or four arches apart. Moreover, this arrangement will enable us to construct long bridges in different parts successively, and each part may be considered as a complete bridge, having its own independent abutments; but strict care should be taken not to contract the beds of rivers by using too many thick piers.” One of Perronet’s immediate predecessors, the engineer Gabriel, built a bridge of this sort, over the Loire at Blois. He spaced his plan into eleven fine arches, and erected two abutment piers, placing them at four bays from each bankside, and leaving three bays between them. By this means his bridge was divided into three independent parts.