John Harrison’s marine chronometer enabled accurate longitude determination at sea.

Evidence

The problem of accurate timekeeping at sea was finally cracked in the middle of the eighteenth century by John Harrison, who invented a clock – a marine chronometer – which could go on accurately telling the time in spite of fluctuations in temperature and humidity and the constant movement of a ship, thus making it possible for the first time for ships anywhere to establish their longitude. — Neil MacGregor, A History of the World in 100 Objects, 1394

Categorization

• corroborated: 2 independent passages support this claim — Neil MacGregor, A History of the World in 100 Objects, 1394