Photograph of an optical disc, with a diameter of 29 to 29.5 inches. The disc reflects the surrounding display area. The disc was exhibited by Chance Brothers and Co. at the Great Exhibition.

This photograph is from Volume II (RCIN 2800001) of ' Exhibition of the Works of Industry of All Nations, 1851: Reports by the Juries on the Subjects in the Thirty Classes into which the Exhibition was Divided'. The incredibly successful Exhibition of the Works of Industry of All Nations, commonly known as the Great Exhibition, ran from May to October 1851.  At the exhibition's conclusion, over 100 copies of the four volume 'Reports by the Juries' were distributed to foreign governments and notable participants. The reports consist of the juries' comments and assessments of the works displayed in the exhibition. The idea and decision to illustrate the reports with photographs is attributed to Prince Albert (1819-61).