Rochester Bridge: The Roman Bridge in Masonry

ROCHESTER BRIDGE. 141 The road traffic over such a bridge would-be greatly in excess of the capabilities of timber bridges, which in subsequent centuries were a constant source of expense to the Wardens, and were never otherwise than inadequate for.their purpose. We may, therefore, safely assume that a timber bridge would have been quite insufficient for Roman civilisation during its five centuries of continuance. The discovery of an ancient pier of masonry directly under the Strood pier of the present bridge is of the utmost importance from the historical standpoint, and it is to be regretted that more careful and accurate details of its construction were not noted at the time. But what we can do is to examine critically the particulars communicated in 1857 by Mr. Hughes to the Institute of Civil Engineers, and the discussion which followed the reading of his paper. It should, however, be remarked that, according to documents of 1115 A.D., the ancient bridge had nine stone piers, as well as the two abutments, and two openings for the passage of high-masted vessels, whereas, as yet, only one pier has been discovered, so that the remaining ten foundations may still be in the bed of the. river; for, considering'the great depth to which they were sunk, it is extremely improbable that the Bridge Wardens would dig them out. Let us consider the various points of information given in this paper hy Mr. Hughes :— The dry-rubble masonry extended down to from 13 feet to 25 feet below the present bed of the river. I t contained enormous quantities of timber built in the masonry; some laid horizontal, and others vertically, being used as piles, and shod with iron which (the timber being of oak, elm, and beech) penetrated into the gravel from one to two feet. There existed a timber framework at the bottom of the existing foundations, through which the piles were driven into the ballast. During the construction of the bridge (1856) large quantities of timber, some charred, were removed, from the bed of the river, which was without doubt the