The material consists of calculations of equinox noon M values for sunspot maximum and minimum. It contains a typescript note by Appleton to 'I. Y. L.’, setting out the problem and method, dated July 1964.

'Changes made in magneto-ionic theory by the introduction of the ⅓'. The material consists of notes for a paper by Edward Appleton, no date, c. 1925-1943.

Chart, correspondence and data relating to radio reception. The material consists of a chart of intensity curves, by Edward Appleton; and correspondence and data on short wave transatlantic reception, all dated 1930.

Charts and graphs by Edward Appleton of sunspot activity for F₂ at Huancayo [Peru]. The dates range from 1938-1944. The material includes later similar data for fE in another hand.

The material consists of charts and graphs of geographical and geomagnetic latitude values for various stations. The date range is 1945-1951 but many of the charts are undated. Some of the sheets are headed '(fF₂)A/(fF₂)B' in Edward Appleton's hand.

The material consists of an original folder of charts and graphs, some on Slough data 1931-1951, written in several hands.

The material consists of charts and tables of noon values, mainly from Slough data, dated 1932-1958. It includes a note from Mrs. Turnbull to Edward Appleton on the data, and a brief reply by him.

The material consists of charts, etc. of sunspot numbers, dated 1954-1958. Some of them are annotated by Edward Appleton.

The material consists of charts, etc. on sunspot cycle from 1937-1940 and 1936-1938.

The material consists of charts of worId values, dated March and September 1958, March 1959, March 1962.