 The site agent had shown initiative by artificially ageing a trial area of new stone with peat and milk, but it was insisted that the new stone should remain untreated in order that old and new work could be identified.The original viaduct had not had parapets and had probably never had handrails, which were now essential for safety.It was considered appropriate to make them of steel in an authentic period style, and after examining photographs of the cast iron railings of Chirk Aqueduct and other early examples, masonry copings and light-coloured railings were provided.