Perth Bridge construction plans, 18th century. This stone bridge, consisting of a series of nine arches, spans the River Tay in Scotland, connecting Perth to Bridgend. It was designed by British civil engineer John Smeaton (1724-1792) and completed in October 1771. At the time of its construction, it was the longest bridge in Scotland at 272 metres. As these plans show, it was engineered to resist severe flooding which had destroyed the previous bridge. At lower left is the design of the foundation of one of the pillars (piers), with the part of the arch design at lower right. This plan was published in a volume of 'Reports of the late John Smeaton FRS' (1812).