Correspondence and related papers concerning magnetism, including correspondence with the Carnegie Institute of Washington and the Department of Terrestrial Magnetism regarding the interchange of magnetic data; correspondence with Dr G. Swoboda, Lausanne Magnetical Observatory, regarding magnetic character numbers from the Abinger Magnetic Observatory; and quarterly summaries of days classified according to magnetic disturbances. The papers also include the following material:

Letter from Sir Harold Spencer Jones to Dr M.A. Tuve regarding resuming work on the non-magnetic ship 'Research', 1947.

Correspondence with M. McCaig regarding his cosmic ray investigations, 1945.

Copy of the mean annual values of magnetic declination at the Abinger Magnetic Observatory, 1936-1945, sent to E. Thellier, Paris, 1945.

Review of cosmic data from Moscow, with a notification of distribution, 1945.

Annual mean values of magnetic elements for the San Fernando Magnetic Observatory for 1942 and 1943, compiled 1944.

Chart of tabulations from 24 magnetic observatories for July 1944.

'List of Geomagnetic Observatories and Thesaurus of Values - II' by J.A. Fleming and W.E. Scott, 1944.

Correspondence with the International Meteorological Organisation regarding the death of Dr D. la Cour, Director of the Danish Meteorological Organisation, 1942.

Correspondence with the International Meteorological Organisation regarding 'Giant Pulsations', with two charts attached, 1942.

Correspondence with Dr J. Fleming, International Union of Geodesy and Geophysics Association of Terrestrial Magnetism and Electricity, regarding three-hour range (index K), 1940.

Correspondence with G. Van Dijk, Netherlands Meteorological Institute, regarding magnetic data, 1940.