Refracting telescope of 4½-inch aperture and 5 ft focal length in wooden case with 2 eyepieces and adaptor tube, by Smith Beck & Beck, London, 1863. A Royal Society instrument used by William Radcliff Birt for lunar observations as part of a mapping project of the Moon organised by a committee of the British Association for the Advancement of Science. Refracting telescope used by William Radcliff Birt for lunar observations