Correspondence with the Helwan Observatory concerning the photographing of Halley's Comet, 1909-1910.

Correspondence with W.J. Spratly, 1907, concerning the period of Halley's Comet, the more philosophical aspects of the comet and its connections with early Egyptian history.

Memoranda on and ephemerides of Halley's Comet, mostly by A.D.C. Crommelin, 1908-1910.

Correspondence with J. Franklin Adams concerning his visit to the Royal Observatory and a photograph of Halley's Comet to be shown there, 1910.

Correspondence and memoranda concerning the Lindemann prediction prize awarded to P.H. Cowell and A.C. Crommelin, 1910.

Observations taken by the General Post Office of the possible electrical effects of Halley's Comet at its closest pass on General Post Office telegraph lines, 1910.

Correspondence concerning the exchange of photographs with the Giza Observatory and the loan of photographs to the Lick Observatory, 1910-1912.

Correspondence with the 'Daily Mail' concerning a visit to the Royal Observatory to see Halley's Comet, with telegrams of the observations made, 1908-1909.

Correspondence with newspapers, letters from editors regarding photographs, interviews, etc., with cuttings from newspapers and periodicals, 1909-1910.

General correspondence with private individuals concerning Halley's Comet, letters to J. Franklin-Adams on photographic plates, and ephemerides sent to correspondents, 1908.