An American Hamilton type 21 two-day marine chronometer, No 4975 the silvered dial signed and numbered Hamilton Lancaster PA., USA N4975 1941 Arabic hour numerals, subsidiary seconds and up-and-down dials, blued steel hands, Earnshaw escapement, uncut ivar balance, bright metalic balance spring, Hamilton spring detent with jewelled locking spring, balance wheel locking device to side of balance, three tier brass bound mahogany box with Hamilton Watch Co. label to front of centre section, external brass drop handle, dial dia -- 4in.(10.2cm.); case -- 7¾in. (19.3cm) square