11 pages of notes on integrals. These were sent with a covering note November 1935 by G. Cook, and originally tucked into notebook Coll-37/B.27.

Correspondence between E. Cunningham and Edward Appleton. The material consists of letters on mathematical aspects of Appleton's work, and especially on the positive and negative signs. Also included is the last page of a letter from Appleton on the problem and asking for assistance. Only some of the letters are dated May 1927.

Correspondence between Mary L. Cartwright and Edward Appleton, c. 1943. The material consists of letters and calculations and it includes two letters from J.E. Littlewood (only one dated, 1943), and 1 page of calculations in another hand.

Correspondence between Mary L. Cartwright and Edward Appleton, c. 1946. The material consists of letters, graphs and it includes draft of Cartwright's paper, 'Forced oscillations in nearly sinusoidal systems' and miscellaneous offprints on the subject by Cartwright, Littlewood, Van der Pol, etc., not all dated.

Correspondence between Mary Taylor and Edward Appleton, dated 1931-1933. The material includes a translation by Taylor of a Russian paper by L. Schekulin on the subject of propagation of electromagnetic waves in ionized gas under the influence of a constant magnetic field H.

Large ledger-type notebook. The notebook contains notes on mathematics, some labelled 'Lecture II', etc., perhaps for lectures at Cambridge, c. 1936.