Detail of the Kew photoheliograph, the first astronomical instrument specifically designed for photographing celestial objects. Conceived by the British astronomer and physicist Warren de La Rue (1815-1889) in 1857, it was built for the Royal Society by the London instrument maker Andrew Ros (1798-1859). Originally installed at Kew Observatory, it was used by de la Rue to take regular photographs of the Sun. Later it was taken to Rivabellosa in Northern Spain, where it was employed to photograph the 1860 total eclipse of the Sun. The resulting images were used to resolve the debate over whether prominences - the red flames seen at solar eclipses - were intrinsic to the Sun or merely atmospheric effects. It was subsequently used as the model for a whole series of photographic telescopes.
© Science Museum / Science & Society Picture Library