Quoted from the Royal Museum Greenwhich website: "Survey Chronometer. An adapted form of the standard two day chronometer was the survey chronometer. Fitted with electrical contacts and rated to sidereal time, the survey chronometer was used in conjunction with a tape chronograph and, by the date of the NMM’s examples, a 45° Admiralty prismatic Astrolabe – an optical instrument for measuring angular distances between a given star and the zenith (the zenith distance). The very accurate timing of the zenith distance of specific stars enables the precise location of the observer to be found and is used in land survey work, enabling precise latitudes and longitudes to be established. A considerable number were issued by the Admiralty for use in accurate surveying of harbours and coastlines during the twentieth century. In order to be sufficiently precise in the determination of the time of observation, the chronometer is used in conjunction with the tape chronograph. The principal of this instrument is to enable the moment of an astronomical observation to be recorded permanently, in a visual form, enabling an accurate determination, at leisure, after the observation is made."
I have used this clock for display purposes only. Prior to listing, I checked the movement and it ran strong. Because it has not been serviced recently, I did not run it for long. The leather strap (using original buckle) and the lock strike were replaced. I will provide the original parts. Also included in the sale are copies of literature describing the clock's function.
The clock and case are sold as is and there are no returns. Only items shown in the photographs are included. Please feel free to ask questions and I will do my best to answer them, but recognize that I am by no means an expert on clocks.