and Sons, who were assisted by John Abbot and Co., of Gateshead Park Works, and Losh Wilson and Bell, of Walker Ironworks, in the production of the castings. The tender was accepted at £112,000. The contract for the bridge piers and land arches and for the Newcastle Viaduct were won by John Rush and Benjamin Lawton of York for £94,000 and £82,500 respectively. The total cost of the contracts at 1999 prices would be over £30million. Construction The first masonry was laid on 12 January 1847. A temporary timber viaduct on the east side was ready on 20 August 1848. Timber coffer dams were constructed; they were by with two skins, the space between being filled with puddle clay. James Nasmyth had a novel design of steam pile driver; it had first been used in Devonport Docks in 1845; it could deliver 60 to 70 blows a minute; the cycle time with the hand-operated pile drivers formerly in use was four minutes. The drop weight was 1½tons and its stroke was ; one was purchased from Nasmyth. The ground gave considerable trouble during construction; Stephenson recorded: Many difficulties occurred in driving the piles which considerably retarded the progress of the work, and, among others, the peculiar effect of ebb and flow during this operation is worthy of note. At flood-tide, the sand became so hard as almost totally to resist the utmost efforts of driving, while at ebb the sand was quite loose, and allowed of doing so with facility. It was therefore found necessary to abandon the driving on many occasions during high water. The difference between high and low water is 11 feet 6 inches. Another difficulty arose from the quicksands beneath the foundations. Although the piles were driven to the rock bottom, the water forced its way up, baffling the attempts to fill in between them; this, however, was remedied by using a concrete made of broken stone and Roman cement, which was continually thrown in until the bottom was found to be secure. The arch ribs were erected in section by travelling crane; each arch was temporarily erected at the contractor’s works. The first was placed on 10 July 1848, and the erection of the ironwork was quick. Already on 29 August 1848, it was possible to pass a special train over the first arch, and over a temporary structure for the rest of the crossing: