marine chronometer
Noun
Meaning
marine chronometer (plural marine chronometers)
A timepiece used as a portable time standard at sea so as to enable the determining of longitude by means of celestial navigation.
Synonyms
Examples
A nautical almanac and a marine chronometer are used to compute the subpoint on earth a celestial body is over, and a sextant is used to measure the body's angular height above the horizon.
John Harrison created the first highly accurate marine chronometer in the mid-18th century.
Scientific heritage John Harrison of Barrow upon Humber (but born in Yorkshire at Foulby ), invented the marine chronometer which allowed longitude to be accurately measured, and hence navigation at sea.
Though the Board of Longitude rewarded John Harrison for his marine chronometer in 1773, chronometers remained very expensive and the lunar distance method continued to be used for decades.
Only in the middle of the 18th century, after the marine chronometer was invented and the spatial distribution of magnetic declination was known, could the Mercator projection be fully adopted by navigators.
The book remains the authoritative work on the marine chronometer.