Correspondence regarding photographic zenith tubes. There is detailed correspondence relating to the design and installation of the Royal Greenwich Observatory photographic zenith tube, including correspondence with D.S. Perfect and Sir Howard Grubb, Parsons and Co. Ltd regarding its design; correspondence on cable work, lifting gear, the building for housing the telescope, the measuring machine suitable for measuring photographic zenith tube plates, the mercury reflector, the shutter and the dew cap; drawings by D.S. Perfect; and progress reports and reports of meetings.

The papers also include a drawing of the Imhof Photographic Zenith Tube console and mercury reflector, 1949; a list of stars on the observing programme for the Florida Photographic Zenith Tube, received from the United States Naval Observatory, 1949; an article from 'Engineering' regarding the R.G.O. and its photographic zenith tube, 1946; an outline specification for the 25cm photographic zenith tube, 2 October 1945; a detailed report on the design of the photographic zenith tube, 1944; and letters from foreign observatories asking for details of the photographic zenith tube, 1944.