Correspondence relating to longitude and its determination, including the following material:

(1) Correspondence regarding the Potsdam-Greenwich Longitude via Emden and Bracton, 1902-1904.

There is correspondence with C.T. Albrecht regarding accommodation, equipment and arrangements with the General Post Office (G.P.O.); correspondence with the G.P.O. regarding the line between the Royal Observatory and Potsdam; and a copy of 'Longitude Difference between Potsdam and Greenwich', a Royal Prussian Geodetic Institute paper, in German, by Professor Albrecht, 1904.

(2) Correspondence regarding the proposed determination of the Cairo-Greenwich Longitude, 1906-1907.

There is correspondence with Professor Turner, Oxford University Observatory, and H.G. Lyons, Director General of the Survey Department of Egypt, regarding observers going to Egypt, their itinerary and equipment, and the funding of the expedition.

(3) Correspondence regarding the determination of the longitude of Ascension Island and the incidental connection of the Royal Observatory and the Cape Observatory, 1907-1909, including the following material:

Correspondence with the Hydrographer regarding transit circle observations, errors and rates of the sidereal clock, loan of equipment, transport arrangements and signals.

Correspondence with the Admiralty Secretary regarding Mr Pett making observations and the loan of equipment.

Correspondence with the G.P.O. regarding the transmission of signals between Ascension Island and the Royal Observatory.

Correspondence with Mr Judd of the Eastern Telegraph Company regarding signalling, relays and siphon arrangements.

Correspondence with the observers Pett (Cape Observatory), Captain Simpson and Captain Monro regarding observations, telegraphic arrangements and signal tapes.

Memoranda and notes, including lists of equipment, observations made and programmes of signalling, with a copy of pages 91-97 of 'Note on the Telegraphic Determination of Longitude Greenwich-Ascension-Cape in the Year 1908' by Sir W.H.M. Christie.

(4) General correspondence regarding the determination of the longitude of Malta, 1908-1928, including the following material:

Memoranda regarding the determination, 1908-1909, including a copy of papers on the longitude of Spencer's Monument, Malta; a list of observations obtained with the transit circle; programmes of signalling; instructions to the electrician at Porthcurno; and lists of equipment, boxes, etc., sent out.

Correspondence with Mr Barrell, the Eastern Telegraph Company electrician at Porthcurno, regarding equipment and arrangements relating to the determination, 1919.

Correspondence with Mr Eddington and H. Christie, observers at Malta, regarding equipment, 1909, including piers, clocks and measurements.

Correspondence with the G.P.O., 1909, regarding a direct wire from the G.P.O. to the Eastern Telegraph Office and other arrangements, with diagrams and blueprints of arrangements, etc., and oscillograms of the G.P.O. standard relay.

Correspondence with the Admiralty, 1908-1928, including correspondence with the Hydrographer regarding a site for the transit instrument and cable communications, 1907-1909; with Captain Nicholson regarding the feasibility of using wireless telegraph equipment, 1909; with the Accountant General regarding expedition expenses, 1909; with the Secretary of the Admiralty regarding employment for the expedition, 1909-1910; and with Admiralty and War Office, 1909-1928, regarding the determination trigonometrically of the difference of longitude and latitude between the site of the longitude station at St George's Bay and the flagstaff on the palace at Valetta, and also the site of Spencer's Monument, with further correspondence on a new triangulation of Malta and a copy of a report showing the results of the various surveys of Malta.

(5) General correspondence regarding the determination of longitudes and latitudes, 1918-1928, including the following material:

Correspondence with the High Commissioner of Canada, 1918, regarding the whereabouts of T.L. Tiarck's papers of his boundary observations along the 45th Parallel (1817).

Correspondence with the President of the International Commission on Longitude regarding longitude observations of Tokyo-Greenwich-Vancouver.

Correspondence with the Admiralty and the Colonial Office regarding the scheme for the standardisation of longitudes.

Correspondence with various observatories regarding w/t time signals and longitudes, including Wellington, New Zealand; Uccle, Belgium; Helwan, Egypt; U.S. Naval Observatory, Washington; Paris; and Adelaide.

Summaries of results for the longitudes of Deakin and Kimberley (1921).