The papers include correspondence and other papers of professor James Chadwick (regarding the cyclotron) with Bernard B. Kinsey, Ernest O. Lawrence, Henry W. Newson, Malcolm C. Henderson, J. D. Cockcroft, W. H. Hatfield, G.H. Nisbett, E. W. Marchant; correspondence of Professor Chadwick with Metropolitan-Vickers Electrical Co. Ltd. re supply of magnet, coils, etc. for cyclotron, 1936-1939; the minutes of meetings of 156 cyclotron progress committee, 13 July 1948- 16 December 1952), and a typescript memoranda on the 156" Magnet and equipment, 1948; photographs of the cyclotron magnet, the mass spectrometer, 37" cyclotron, and some other apparatus, together with staff and students of the Dept. of Physics; phototcopy of a transcript of a tape-recorded interview with Sir James Chadwick conducted by Charles Weiner for the American Institute of Physics' Center for History of Physics over the period 15-21 April 1969; photocopies of the Monthly Progress Reports of the George Holt Physics Laboratory for the months of July - September 1942 and January - June 1947 and Dr. King's analyses of these reports with respect of the progress of cyclotron work; and Dr. King's calendars of various portions of the collection.