What was John Harrison best known for in horology?

John Harrison is best known for his groundbreaking work in solving the problem of calculating longitude at sea. During the 18th century, determining a ship's precise location on the ocean was a significant challenge, as it was critical for navigation and safety. Harrison developed a series of marine chronometers that accurately kept time even in the harsh conditions at sea, enabling sailors to determine their longitude by comparing the time on board with the time at a fixed point (like Greenwich Mean Time).

His invention of the marine timepiece fundamentally transformed navigation, allowing for safer and more reliable sea travel. This achievement earned him recognition as a pioneer in horology and set the stage for future advancements in timekeeping. Harrison's work remains influential in both the fields of horology and navigation to this day.