A Hamilton model 21 marine chronometer the matt silvered dial signed 'Hamilton Lancaster PA, USA, Property of US Army' and numbered (N) 2189 1941, Arabic hour numerals, subsidiary seconds and up-and-down dials, black finish hands, Earnshaw escapement, uncut stainless steel balance with start/stop yolk assembly above the balance rim (operated by allan key through bottom of the bowl). Helical balance spring, Hamilton spring detent with jewelled locking stone, brass bowl, gimballed in brass-bound mahogany Hamilton box, with external drop handle. Dial diameter -- 4 1/8in. (10.4cm.)