This dome housed a 13-inch astrographic refracting telescope, that was acquired in 1890 in order to contribute to the international Carte du Ciel project for the photographic mapping of the skies. It was made by Sir Howard Grubb of Dublin and contributed to a regular series of photographs. It was used on expeditions to view solar eclipses in 1903, 1922, 1927 and 1929 and its object glass was taken to Brazil in 1919 on the eclipse expedition that helped to prove the validity of Einstein's theory of relativity. The telescope was taken to Herstmonceux in Sussex, the new home of the Royal Greenwich Observatory, in 1958. The telescopes left behind when the institution moved to Cambridge in 1990 can still be seen at the Observatory Science Centre.