Correspondence and requests concerning magnetic data, including the following material:

Correspondence with the Hydrographer regarding the R.R.S. 'Research', 1948.

Correspondence with the Royal Aircraft Establishment regarding titled cameras and with the Hydrographer regarding magnetic variation, 1946.

Correspondence with S. Chapman regarding polar flights, 1945, with charts.

Correspondence with Dr Fleming regarding the magnetic north pole, 1945.

Correspondence with Major-General E. Fedorov of the U.S.S.R. regarding magnetic data, 1943.

Correspondence with G.P. Lenox-Conyngham regarding declination charts, 1942.

Correspondence with Professor A. Ogg regarding the Magnetic Observatory in the Belgian Congo, 1942.

Correspondence of W. Mitchell, Dr W.A. Harwood and others regarding the visit of N.V. Pushkov of the U.S.S.R. to the Magnetic Department at Abinger and concerning Russian publications, 1942

Correspondence concerning the magnetic storm of 1-2 March 1942, including a description prepared by W. Witchell.

Correspondence with S. Chapman regarding the examination of the vertical gradients of the three elements X, Y and Z from the Astronomer Royal's analysis, 1942.

Correspondence with S. Chapman regarding isoporic charts, 1941-1942.

Correspondence with the Cambridge Instrument Company Limited concerning the R.R.S. 'Research' marine inductor, 1939-1940, with a handwritten list by Witchell of the marine inductor and auxiliary apparatus dated 5 December 1946.

Correspondence regarding the forwarding of observations made by ships, 1938-1937.