A ship's two day marine chronometer by Thomas Mercer, no. 23001, early 20th century silvered dial with black Roman numerals, up and down dial at 12 o'clock, subsidiary dial at 6 o'clock, detent escapement, helical hair spring, fusee movement, gimbled, within a single tier timber box and original outer carry box 21 cm high, 24 cm wide, 23 cm deep