Thomas Mercer, London. No.7261

Fine chronometer by this famous firm with rare 24 hour dial, circa 1905.

Case

Nicely figured 3-piece brass-bound mahogany box retaining its original engraved ivory plaque, the lid with Herstmonceux Castle label showing that it was last issued from the Chronometer Branch of the Royal Navy in March 1967. This box probably being supplied by George Thompson who worked in Hull.

Dial

Silvered dial with twin crests celebrating honours received at the 1867 and 1876 International exhibitions, the dial marked out for 24 hours and with the Government Broad Arrow, blued-steel hands.

Movement

Fullplate fusee movement retaining much of its original hand spotting and bearing an engraved Broad Arrow, the brass-edge, bowl and key all numbered as the dial. Earnshaw spring-detent escapement, the detent of standard footed form and gold passing-spring. Kullberg's 'split-rim' form of auxiliary balance.

This chronometer is notable for its rare 24-hour indication which probably means that it was originally rated to show sidereal time. This is possibly an indication that it may have been intended for polar use where the extended periods of daylight, and the lack of it, can mean a confusion of am and pm.

For more information on the Mercer firm and their different craftsmen, including the irascible Thompson, see the two books by Tony Mercer on the firm he once headed.