Airy's Altazimuth Instrument was effectively a small transit circle that could be set up to point both along the meridian and at different angles (azimuths) to it. It was proposed in 1843 and erected and brought into use in 1847. It was designed by George Airy and built jointly by Ransomes and May of Ipswich, who were responsible for the heavy engineering, and Troughton and Simms of London, who built the optics and instrumentation. The telescope had a 4 inch diameter object glass and a tube length of 4 feet 2 inches. The last regular observation with the telescope was made on 29 November 1897. It continued in occasional use for observations of occultations of stars by the Moon until 1910, and was dismounted in February 1911. This series is comprised of a set of original large-scale drawings of the Altazimuth Instrument, a box of cut-out 'patterns', and a set of drawings and prints of plates for George Airy's publication, 'Greenwich Astronomical Observations, 1847, Altitude and Altazimuth Instrument'.