'A very diadem of light': exhibitions in Victorian London, the Parliamentary light and the shaping of the Trinity House lighthouses.

In the midsummer of 1872 a lighthouse apparatus was installed in the Clock Tower of the House of Commons. The installation served the practical function of communicating at a distance when the House was sitting, but also provided a highly visible symbolic indication of the importance of lighthouse technology to national concerns. Further, the installation served as an experimental space in which rival technological designs, with corresponding visions for the lighthouse system, could compete in public. This article considers nineteenth-century lighthouse technology as a case study in the power and political significance of display. Manufacturers of lighthouse lenses, such as the firm of Chance Brothers, sought to manage interpretations of the lights through the framing of exhibitions and demonstrations; so too did scientific authorities, including Michael Faraday and John Tyndall, both of whom served in the role of scientific adviser to Trinity House, the body responsible for lighthouse management. Particularly notable in this process was the significance of urban, metropolitan display environments in shaping the development of the marine lighthouse system around the nation's periphery.