Correspondence and related papers on the communication of time by the Post Office telegraph. There are papers on the trials, costs and tests of clocks on the network; the regulation of clocks; proposals for time signals to be sent to naval dockyards from Greenwich; time balls at Portsmouth, Devonport, Sheerness, Glasgow, Hamburg, Liverpool and the City Observatory, London; and a report by Airy on the workings of the Devonport Time Ball and sketches of its galvanic arrangement. The correspondents include J. Washington, J.C. Clark, C.P. Smyth, H. Wood, H.C.G. Rumkes, G. Fisher, C.F. Varley, C.V. Walker, E. Sabine, C.C. Parker and R.B. Osborne.