⭕ Very rare Hamilton 221 ships chronometer, five orbit dial, works based on factory modified Hamilton 21. Original inner and outer box, numbers match on all parts and both boxes. Dial marked 1944. One of 27 made by Hamilton at the request of the Air Force for navigation in the Pacific. The Air Force actually commissioned a smaller number, but Hamilton made extras which were later sold for civilian use. The pictured timepiece was one of two used by a pair of tuna boats owned by the same family. It is unusual to find Hamilton marine chronometers with boxes numbered to match the works.