General correspondence from Breslau and Clarendon Laboratory Contains note: "These early letters 1931-1933 have been left exactly as found amongst the Simon papers. They are filed alphabetically by name of correspondent not in date order, Joan Pye, Harwell, January 1969". The 7 files have therefore been kept in the order passed down, though this does result in an organisational structure in which a number of overlapping files run A-Z. 1930-1938