Correspondence regarding the temperature control of the dome and telescope. In correspondence with M.H. Jeffery, Redman makes detailed comments on the report by W.E. Bassett and Partners and discusses problems. A letter from M.F. Ingham, Oxford University Observatory, 4 February 1969, encloses a copy of a letter, in French, from G. Courtes, Centre National de la Recherche Scientifique Laboratorie d'Astronomie Spatiale, Marseille, 29 January 1969, on the ventilation of the 76-inch telescope at Haute Provence. There is also correspondence between Redman and Hermann Wehner concerning further information required by the Commonwealth Scientific and Industrial Research Organisation Department of Mechanical Engineering, with an accompanying flow chart on mirror cell air density variation, and also discussing the Tautenburg dome thermal behaviour.