Longitude solved
A clockmaker builds a timepiece accurate at sea, and navigation stops being guesswork.
- When
- —
- Duration
- 43 years
- Known to
- ± 1 year
- Era
- Early Modern, Holocene
Finding longitude requires knowing the time at a reference place, which needs a clock that works on a rolling, damp, temperature-varying ship — where pendulums fail. John Harrison, a self-taught carpenter, spends decades on the problem; his H4 of 1761 loses five seconds on a voyage to Jamaica. The Board of Longitude resisted paying him, favouring astronomical methods. Accurate charts and safe long-distance navigation follow.