1 page typescript note from Edward Appleton to William Roy Piggott on F₂ equinox values, signed and dated 11 January 1946.

'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.

Correspondence and data on F₂ layer from W.R. Piggott to Edward Appleton, dated 1947.

Correspondence and papers from W.R. Piggott to Edward Appleton, dated November-December 1947. The material includes Japanese and German ionospheric research.

Correspondence between Edward Appleton and W.R. Piggott, dated 1947. The material includes an 11 page draft, ‘Note on the problem of the currents which flow during a sudden ionospheric disturbance’.

Correspondence from 1st Viscount Cherwell (F.A. Lindemann) to Edward Appleton, dated 1945. The material includes comments on a draft paper by Appleton, with manuscript notes by Appleton and W.R. Piggott.

The material consists of correspondence from H.W. Newton to Edward Appleton, dated 1938-1939; from W.R. Piggott to Edward Appleton, no date, c. 1939; and from R.L. Smith-Rose to Edward Appleton, dated 1938.

Correspondence from Sir Gordon H. A. MacMillan, W. R. Piggott and R. L. Smith-Rose to Sir Edward Appleton, dated October 1949. The material follows on from Coll-37/A.25 and regards the possible setting up and financing of an ionospheric laboratory in conjunction with Edinburgh research.

Correspondence from T. Penney to Edward Appleton, dated 1943, from W.R.Piggott to Edward Appleton, no date and from B.G. Pressey and G.H. Ramsden to Edward Appleton, dated 1946. The correspondence from Ramsden relates to 'hissing phenomenon' observations in 1941.