A two-day marine chronometer the silvered dial signed and numbered Thomas Mercer 20479 Roman hour numerals, subsidiary seconds and up-and-down dials, blue steel hands, Earnshaw escapement, cut bi-metallic balance with circular heat compensation weights, palladium helical balance spring, Mercer flat strip steel detent with jewelled locking pallet, brass bowl gimballed in plain two-tier mahogany box with glazed top, dial diamerter -- 4¼in. (10.5cm.); Case -- 7¼in. (18.5cm.) square