An instrument for measuring time precisely, originally used at sea.

It is designed to remain accurate through all conditions of temperature and pressure. The first accurate marine chronometer, capable of an accuracy of half a minute a year, was made in 1761 by the English horologist and instrument maker John Harrison.

An instrument for measuring time precisely, originally used at sea.

It is designed to remain accurate through all conditions of temperature and pressure.

The first accurate marine chronometer, capable of an accuracy of half a minute a year, was made in 1761 by the English horologist and instrument maker John Harrison.