Regulator clock. Repro ID F1254 © NMM London, MoD Art Collection

Marine chronometer

Marine chronometers are very accurate portable timekeepers used for navigation. They are designed to remain accurate at wide extremes of temperature.

The first marine timekeeper was invented by John Harrison in the 18th century, and the same basic design was used until the 1960s when chronometers began to be replaced by radio and then satellite navigation.

Regulator clock

This clock was commissioned by the Admiralty in 1904 to control their time signal ball at Windmill Hill Signal Station, Gibraltar. A daily electrical signal direct from the Royal Observatory enabled it to be set to Greenwich time.

In 1935 it was transferred to the Gibraltar Chart & Chronometer Depot.

Deck watch. Repro ID F1139 © NMM London, MoD Art Collection

Deck watch

Deck watches were sometimes used to transport time around a ship to and from box chronometers, primarily for making astronomical observations from the deck. As their performance improved, they were sometimes also used instead of box chronometers.

This fine quality example is by Swiss maker Ulysse Nardin and dates from around 1943.

Acknowldgements