Part of cast iron plate rail found on the Laigh Milton Viaduct over the River Irvine on the former Kilmarnock & Troon Railway during its refurbishment in 1995. The section is 18 in long being cut to half of its original length.
For description of the railway see Proceedings of the Institution of Civil Engineers, Civil Engineering, 1998, 126, May, 73-85.
For a general description and images of early cast iron plate railways see https://tringlocalhistory.org.uk/Railway/c03_track.htm.
For an article on the viaduct and its restoration see http://www.engineering-timelines.com/scripts/engineeringItem.asp?id=1243.
For a detailed paper on the viaduct and its restoration see here.