Brief notes and calulations by Edward Appleton.

'Conductance Effects in Ionospheric Circuits'. The material consists of a 5 page draft of a paper by Edward Appleton and W.R. Piggott, with a letter, dated 1948. Also included is a draft paper 'Electric conductivity of the ionospheric D region', 1948, author unknown.

Correspondence and data from W.R. Piggott to Edward Appleton, dated 1939. The material includes an extensive manuscript report on experiments.

The material consists of correspondence from D.H.Johnson, A.G. Lee, R.G. Lowe and J.H.H. Merriman with Edward Appleton, dated 1937. The correspondence from Lowe contains enclosed a report on the fading of television signals caused by aircraft and the correspondence from Merriman contains Post Office data.

Correspondence from F.G.W. White to Edward Appleton, dated 1937. The material contains a note by White on absorption.

Correspondence from H.D. Poole to Edward Appleton, dated 1937-1938. The material includes mathematical calculations and a draft report.

Correspondence from J.A. Ratcliffe to Edward Appleton, no date, c. 1936 including comments on a paper by Martyn; and correspondence from T. Walmsley to Edward Appleton, dated 1937, including a memorandum by Walmsley, dated 1930

The material consists of correspondence from N. Ashridge, S. Chapman, T.L. Eckersley, D.R. Hartree with Edward Appleton dated 1937 and from L.Harang with Edward Appleton dated 1938.

Correspondence from W.R. Piggott to Edward Appleton, dated 1939-1940. Enclosed with the material is data and reports on research.

The material consists of a 4 page manuscript draft on 'Irregularities', with 3 pages of manuscript notes on same subject by R. Naismith.