Correspondence on solar flares and sunspots with members of the general public, schools and universities, institutes of science and technology, other observatories and prominent individuals, including Professor G. Abetti, Dr A.C.B. Lovell, Dr J. Klecveky, J.D. Radcliffe, Sir Edward Appleton, A.V. Vrede, Dr N. O. Roberts, Professor A. Danjon, Professor S. Rosseland, Dr F. Bauer, Dr R.T. Hansen, Dr Righini, Dr A.H. Shapley, Professor H.C. Willett, Dr C. Macris, Dr Adamopoulos and Professor J. Xanthakis. The papers including the following items:

Correspondence with the Cavendish Laboratory on solar flares and long wave anomalies and discussions of a radio warning device for incipient anomalies, 1948-1949.

Correspondence with various people, including Dr C.W. Allen and J.S. Hey, concerning solar noise, 1948-1949.

Correspondence on solar photography with the general public, other observatories, universities, publishers, etc., including Dr R.A. Lyttleton, Professor R.O. Redman, Dr R. Michard and Dr H.R. Calveit, 1948-1963.

Receipts of bills of lading for photographs and negatives from various sources, including the South African Observatory, Mount Wilson Observatory and Kodaikanal Observatory, 1948-1963.

Accounts and correspondence on the Eclipse Expedition, 1952.

Correspondence with the Shire Valley Hydrology Project, Nyasaland, 1954-1959, including charts on the possible correlation between sunspots and rainfall.

Correspondence with the Fraunhöfer Institut on sunspots and solar flares, 1956-1959.

Correspondence with Dr Nilo Arriaga on apparent variations of the solar diameter, 1958.

Correspondence regarding long wave communication using high altitude orbiting microwave reflectors, 1961, relating to Project Wert-Ford.