The History of the Longitude Problem


Philip II of Spain offers reward (never won)


Philip III of Spain offered 6,000 ducats and a pension (never won)

States General of the Netherlands offered 10,000 florins shortly after (never won)


wrecking of 4 naval vessels on the Scilly Islands (1,550 lost lives = one of the worst British maritime disasters)

1714 July 8

Longitude rewards were established through an Act of Parliament (the Longitude Act), administered by Board of Longitude of the British government

  • £10,000 (equivalent to £1.3 million in 2015) for a method that could determine longitude within 1 degree (equivalent to 60 nautical miles (110 km; 69 mi) at the equator).

  • £15,000 (equivalent to £1.96 million in 2015): determine longitude within 40 minutes

  • £20,000 (equivalent to £2.61 million in 2015): determine longitude within 30 minutes


Recipients of the Awards

John Harrison

- £23,065 awarded overall

- 21 years old when the Longitude Act passed; spent the next 45 years perfecting his timekeepers

- 1737, first awarded £250 in order to improve on his promising H1 sea clock

- 1741 – 1755, £2,000 was rewarded for continued construction and completion of H2 and H3

- 1760 – 1765, £2,865 for expenses related to construction, ocean trials, and development of H4

- Harrison was rewarded £7,500 (£10,000 minus payments he had received in 1762 and 1764)

- 1773, final reward of £8,750

Thomas Mudge

- 1777, Thomas Mudge received £500

- 1793, £3,000 award approved by special committee

Tobias Mayer

- £3,000 awarded to his widow for lunar distance tables

- 1766, published in The National Almanac and used by James Cook in his voyages

Thomas Earnshaw

- £3,000 awarded for years of design and improvements made to chronometers

Charles Mason

- £1,317 awarded for various contributions and improvements on Mayer’s lunar tables

Larcum Kendall

- £800 total for his copy of and improvements and simplifications of Harrison’s sea watch (£500 for K1 – Kendall’s copy of Harrison’s H4, £200 for modified K2, and £100 for last modification model K3)

Jesse Ramsden

- £615 awarded for his engine-divided sextant with the requirement that he share his methods and the design with other instrument makers

John Arnold

- £300 awarded in increments to improve his timekeeping design and experiments, though the accuracy required for the prize was never met

Leonhard Euler

- £300 awarded for contributions to the lunar distance method in aid of Mayer

Nathaniel Davies

- £300 awarded for the design of a lunar telescope for Mayer