Early Marine Chronometer by Hamilton


Signed   Hamilton Watch Co Lancaster Penn   -   Model 21,   14 Jewels - Made in USA - N216 1941
Circa   1942
Diameter   107 mm         

Out of stock


An American 56 hour marine chronometer in a brass bound mahogany box.  Full plate damascened nickel keywind fusee movement, four turned pillars secured by polished steel screws.  Harrison’s maintaining power, polished steel barrel ratchet wheel on the barrel bridge.  Brass fusee and barrel. Two arm uncut balance with brass timing screws, two smaller micrometer adjustment timing nuts and two further even smaller timing nuts. Freesprung helical hairspring.  Earnshaw spring detent escapement, escape pivots with endstones. The movement secured to the gilt dial plate by three polished steel screws.  Engraved signed and numbered silvered brass dial with subsidiaries for seconds and power reserve indication, Arabic numerals, blue steel hands.  Turned brass bowl with knurled screw bezel, sprung rotating shutter to the winding aperture.  Brass gimbals and locking mechanism, brass ratchet key bearing the serial number.  Three tier mahogany box, drop brass handles, corners, and hinges.  Middle tier with two rectangular plaques, one engraved with the maker’s name, the other with the serial number.  Both these plates repeated inside the base below the bowl.  A black plate inside the middle tier bearing the serial number and “Ministry of Defence Hydrographic Dept. Chronometer Marine”.

An unusually early example of a model 21 chronometer with the Naval Observatory number 216.  Later examples added a device to support the balance during transit.  Only weeks after the attack on Pearl Harbour Hamilton delivered two prototypes of the Model 21 to the Navy on 27 February 1942, which passed with an error rate of 1.55 seconds per day. Initial production was limited to about 400 in the first 18 months indicating this example dates to late 1942.