Copies of correspondence between H. Spencer Jones and G.M. Sisson, 7 March 1950 - 12 January 1951, regarding the supply of a 98-inch disk; the progress of work; test facilities; tolerance and price; a central groove and grinding; and a contract for grinding and figuring agreed by the Isaac Newton Telescope Board of Management. There is also a copy of a report by E.H. Linfoot, 30 December 1950, on his examination of the disk at Sir Howard Grubb, Parsons and Co. Ltd.