The Longitude Act of 1714 and the Board of Longitude
A British state body that in 1714 offered a reward of up to 20,000 pounds for a way of finding longitude at sea, and a board of Commissioners that included, ex officio, the Astronomer Royal and the professors of mathematics at Oxford and Cambridge. It later came to be called the Board of Longitude.
The arrangement was an unusual one: a state body that did not pick the right method in advance but paid for the trials of everyone who came with a proposal, and kept several lines open at once. Its money built and tested Harrison's timekeepers, and its money paid from 1767 for the Nautical Almanac with its precomputed lunar distances.
The Board lasted until 1828. It was there, and not in any one person's head, that the two rival solutions to the longitude problem, the chronometer and the lunar method, met and were both brought into working order.
Why this date
exact for the Act: 'An Act for Providing a Publick Reward for such Person or Persons as shall Discover the Longitude at Sea' was passed in 1714. The first minuted meeting of the Commissioners took place only in 1737; before that the body existed on paper. On the account of the Royal Observatory Greenwich the Board existed from 1714 to 1828. The axis value is 1714, the year of the Act, not 1737, the year of the first meeting.
What grew out of it
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The longitude problem and the marine chronometer (John Harrison's H4)
influenced · Confidence: high
Harrison did not work in a vacuum or at his own expense: the successful trial of his first sea clock brought the Commissioners to their first minuted meeting, and from that followed a series of payments totalling over 5,000 pounds with which the next timekeepers, H4 among them, were built and tested. The Board also set the standard of accuracy by which the watch was judged.
Dispute: The link is called an influence rather than a hard dependence by deliberate choice. On Higgitt's account Harrison built his first sea clock before the Commissioners' first minuted meeting, and it was the trial of that clock which prompted the meeting: the Board paid for the continuation, not the beginning, of the work. Higgitt also notes that the Board's relationship with Harrison eventually broke down 'irrevocably', so the patronage was both a condition of the work and a drag on it.
Link sources
- Rebekah Higgitt, «Longitude», Encyclopedia of the History of Science, vol. 4, issue 1 (April 2021) (2021) Verified 20 Sep 2026
In Britain, the promising work of John Harrison, and successful trial of his first sea clock, prompted the first minuted meeting of the Commissioners of Longitude. This resulted in the first of a series of payments, totaling over £5000, given to Harrison to improve and test his next two sea clocks and sea watch, before they were considered for the large £10,000 or £20,000 rewards.
- «An Act for Providing a Publick Reward for such Person or Persons as shall Discover the Longitude at Sea» (Longitude Act), Royal Observatory Greenwich (1714) Verified 5 Oct 2026
to a reward, or sum of ten thousand pounds, if it determines the said longitude to one degree of a great circle, or sixty geographical miles
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
- Rebekah Higgitt, «Longitude», Encyclopedia of the History of Science, vol. 4, issue 1 (April 2021) (2021) Verified 20 Sep 2026
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The Nautical Almanac and the lunar-distance method in the mariner's hands
prerequisite for · Confidence: high
The Nautical Almanac was not a private publication: it was paid for and published by the Board of Longitude, under the supervision of the astronomer royal, Maskelyne. Without a state body willing to pay year after year for the computing work, annual precomputed tables do not exist.
Dispute: The hard dependence applies to this particular publication, not to the idea of precomputation. The same passage in Higgitt shows that the Frenchman Lacaille printed precomputed tables in the Connaissance des Temps for 1761 with no British Board at all, and that the British almanac was 'inspired' by them. So without the Board of Longitude there would have been no Nautical Almanac as such, but precomputed lunar distances already existed in Europe.
Link sources
- Rebekah Higgitt, «Longitude», Encyclopedia of the History of Science, vol. 4, issue 1 (April 2021) (2021) Verified 20 Sep 2026
These were published in official ephemerides, Connaissances des Temps in 1761 and inspired the British Nautical Almanac, paid for and published by the Board of Longitude from 1767 under the supervision of the astronomer royal, Nevil Maskelyne.
- Seb Falk, «Ships, Clocks & Stars: The Quest for Longitude», Science Museum Group Journal, Autumn 2014 (2014) Verified 5 Oct 2026
But from then on they met with increasing regularity and bureaucratisation, initially to discuss possible solutions and later, after Harrison's designs were successfully copied and economised and after astronomical work had brought about the Nautical Almanac that greatly simplified the computation of lunar distances, to support methodological refinements and improvements in the production and maintenance of instruments.
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
- Rebekah Higgitt, «Longitude», Encyclopedia of the History of Science, vol. 4, issue 1 (April 2021) (2021) Verified 20 Sep 2026
Node sources
- «An Act for Providing a Publick Reward for such Person or Persons as shall Discover the Longitude at Sea» (Longitude Act), Royal Observatory Greenwich / Board of Longitude (1714) Verified 5 Oct 2026
to a reward, or sum of ten thousand pounds, if it determines the said longitude to one degree of a great circle, or sixty geographical miles
- «The Board of Longitude», Royal Observatory Greenwich Verified 5 Oct 2026
The Board of Longitude is the name given in later years to the group of Commissioners who were appointed to administer a series of Government awards or 'prizes' for finding longitude at sea.
- «The Board of Longitude» Verified 5 Oct 2026
The Board was in existence from 1714 until 1828.
- «The Board of Longitude» Verified 5 Oct 2026
Amongst those appointed as Commissioners were the Astronomer Royal (A.R.) and the Savilian, Lucasian, and Plumian Professors of Mathematicks in Oxford and Cambridge.
- Rebekah Higgitt, «Longitude», Encyclopedia of the History of Science, vol. 4, issue 1 (April 2021) (2021) Verified 5 Oct 2026
As can be seen from the range of rewards paid out by the Board of Longitude and other authorities, any and all workable methods were of interest.
- Seb Falk, «Ships, Clocks & Stars: The Quest for Longitude», Science Museum Group Journal, Autumn 2014 (2014) Verified 5 Oct 2026
But from then on they met with increasing regularity and bureaucratisation, initially to discuss possible solutions and later, after Harrison's designs were successfully copied and economised and after astronomical work had brought about the Nautical Almanac that greatly simplified the computation of lunar distances, to support methodological refinements and improvements in the production and maintenance of instruments.
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.