A Vernon Harcourt, chemist, 1914.
© Science Museum / Science & Society Picture Library
Portrait photograph of Augustus George Vernon Harcourt (1834-1919). Harcourt was a reader in chemistry at Christ Church, Oxford, and spent 20 years developing a standard lamp which would produce a known intensity of light, an important innovation in the field of photometry (measurement of the intensity of light). His invention was 10 candle-power, and used pentane, an inflammable and volatile hydro-carbon distilled from petroleum. The Metropolitan Gas Referees adopted the Vernon Harcourt standard lamp in 1898 and used it to set British illumination standards. Dimensions: 330mm x 290mm.