Correspondence concerning time signals, including the following material:

Correspondence with E. Dent and Co. regarding irregularities in the Westminster Clock, tables of errors for the clock and newspaper cuttings relating to it, 1902-1906.

Correspondence regarding the installation of a wireless-telegraph receiving station at Greenwich, 1912-1914.

Correspondence of 1912-1915 regarding the inauguration of a wireless-telegraph time service from the Eiffel Tower and concerning the Paris conferences of 1912 and 1913 on the establishment of a Commission Internationale de l'Heure. The papers include a memorandum on the inauguration of the service; proposals, reports, projected statutes, etc., from the four commissions; draft and final reports and remarks and recommendations of the British delegates; a chart showing the time signal w/t stations to be established; Notices to Mariners, Nos 874 and 875, regarding Eiffel Tower signals; and a diagram illustrating the system of transmitting w/t signals.

Correspondence with the Admiralty, the General Post Office and the Marconi Company regarding transmitting time signals from the Poldhu W/T Station in case of interruption at the Eiffel Tower, 1914-1915.

General correspondence regarding w/t time signals, 1912-1914, comprised mainly of requests for advice and information on w/t apparatus and suppliers from other observatories, such as Liverpool, Kew and Hong Kong, and from members of the general public with a special interest in the Royal Observatory equipment. There are also letters concerning Indian sending stations, errors of time signals and experiments.

General correspondence regarding time signals and time balls, 1919-1924, including correspondence with the Hydrographer and Edinburgh Observatory relating to the sending of time signals by the Royal Observatory to the Rosyth Chronometer Depot and the return signals; correspondence with the Air Ministry concerning equipment; and correspondence with the Horological Institute relating to the publication of the Astronomer Royal's lecture.

Correspondence regarding the Mean Time Free Pendulum Clock, Shortt No. 49, 1934-1936, including correspondence with the Synchronome Company concerning its manufacture, including details, estimate, receipt, testing and problems; correspondence with the Hydrographer relating to the contract, testing and cellar for the clock; and correspondence with the Southern Railway Company regarding the performance of Shortt clocks Nos 3, 11, 16 and 49.