Here is a fabulous sterling silver deck Chronometer dating from 1909, and made for the British military.
This wonderful piece of history is fitted in a solid timber case measuring 5.8cm high x 9.5cm wide and 11.5cm deep.
The front has an ivory seal with the words “L. Mumford 1909” and then CW (denoting Chronometer Watch) and the British Broad Arrow.
At the turn of the 20th Century, destroyers had on board 2 Chronometer Watches and two or three Deck Watches, plus several stopwatches.
The Chronometer Watches (marked with a CW) were kept in the drawer in the Chart Table and were wound and checked against a radio time signal daily, usually at the same time (GMT) each day.
There was a log in which the daily error was recorded and a daily rate of error calculated. The daily rate was important if you could not receive a radio time signal, as it was then used to estimate the daily error to be applied to calculations. These time pieces were never reset, unless for some reason they stopped. If the daily rate exceeded an acceptable maximum the CW was taken to the nearest Chart depot and exchanged. The Deck Watches (DW) were calibrated against the Chronometer Watch and could be taken to the bridge to provide an accurate time for celestial observations (e.g. star sights) , or to the radio office to get the time check, then taken to the Chart Room to calculate the CW error.
The case measures 55mm across and is made in sterling silver.
This is a fantastic find, and one that is for someone who loves maratime history.