born March 19, 1727, Plancemont, Switz.
died June 20, 1807, Groslay, France
Swiss-French clockmaker and writer on timekeeping.
Working in Paris from 1748, his inventiveness and many publications soon made him influential. His interest in the problem of determining longitude at sea (see latitude and longitude ) led to his major achievement, an improved, less expensive marine chronometer . Berthoud's improvements were retained in modern instruments. See also John Harrison .