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Longitude Essays

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Longitude Acts

From 1714 to 1828, the British Parliament passed a number of Acts related to the Commissioners of Longitude. The projectors William Whiston and Humphry Ditton first began a concerted public campaign to lobby Parliament for a longitude reward in 1713. After testimony from learned individuals including Isaac Newton, Parliament passed and Queen Anne approved ‘ An Act for Providing a Publick Reward [RGO 14/1:10] for such Person or Persons as shall Discover the Longitude at Sea’ in July 1714. The authors of the Act cited the importance of finding the longitude for the ‘Safety and Quickness of Voyages, the Preservation of Ships and the Lives of Men’, the ‘Trade of Great Britain’ and ‘the Honour of [the] Kingdom’.

The Act of 1714 constituted 24 Commissioners either by name or office; see the entry on Commissioners of Longitude for more information about their identities and about their actions and changing nature over the decades. If five or more thought a longitude proposal promising, they could direct the Commissioners of the Navy to have their Treasurer issue up to £2000 in total to conduct trials. After experiments were made, the Commissioners of the Longitude or ‘the major part of them’ were to determine whether the tested proposal was ‘Practicable, and to what Degree of Exactness’. The Act set up a three-tiered reward system for methods which were deemed successful, with: £10,000 to be given to the inventor of a method which could find the longitude ‘to One Degree of a great Circle, or Sixty Geographical Miles’; £15,000 if the method could find the longitude to two-thirds of that distance; and £20,000 if it found the longitude to half of the same distance.

Half of a reward would be paid when the Commissioners of ‘the major part of them’ agreed that the method could also secure ships within 80 miles of shore, and the other half when the method had been successfully tried on a voyage to the West Indies. The Commissioners of the Longitude, or the major part of them, could also direct that lesser rewards be given to projectors who could not meet one of the three specific demands for accuracy but developed methods ‘found [to be] of considerable Use to the Publick’. Most of these tenets were closely patterned after Charles II’s appointment of Commissioners to examine a longitude proposal in 1674; the longitude reward established by the will of the Somerset gentleman Thomas Axe in 1691; and commentary from individuals including Newton, Whiston and Ditton.

The Acts passed during the 114 years which followed the foundation of the new longitude rewards and funding were variously intended to assist or to reshape the Commissioners of the Longitude. Some were simply a response to the officials' financial and logistical needs, and others reflect Parliament trying to exert control over them and later over the standing Board. The Act of 1740 [RGO 14/1:13] was 'An Act for surveying the Chief Ports and Head Lands on the Coasts of Great Britain and Ireland, and the Islands and Plantations thereto belonging, in order to the more exact Determination of the Longitude and Latitude thereof.' This allowed the Commissioners to apply up to £2000 to better secure the safety of ships sailing near British, Irish and colonial coasts by surveying them and more accurately determining their latitude and longitude. (William Whiston soon took advantage [RGO 14/5:4] of this change.) Coastal areas were a concern because it was so easy to accidentally run aground or on hidden rocks and reefs.

The Act of 1753 [RGO 14/1:15] allowed the Commissioners to draw up to an additional £2000 from the Treasurer of the Navy for funding projectors. The Act also expanded the number of Commissioners, since so many of those named in 1714 had since died. The new members included the Governors of the Royal Hospital for Seamen at Greenwich, the Judge of the High Court of the Admiralty, the Secretaries of the Treasury, the Secretary of the Admiralty, and the Comptroller of the Navy.

The Longitude Acts which were passed from 1760 on were often just responses to requests made by the Commissioners, as when Parliament allocated them more money via the Treasurer of the Navy. Some, however, resulted from the disagreements which arose between the clock maker John Harrison and key Commissioners from the 1760s to the early 1770s. In addition to exchanges at Board meetings, Harrison published accusations particularly against the Astronomer Royal Nevil Maskelyne in pamphlets and in the newspapers. Supporters of each side sniped back-and-forth in print, sometimes anonymously. The core of the problem was that Harrison was convinced that his timekeepers in and of themselves and the trials which he had already put them to were enough to win a longitude reward. In large part, key Commissioners believed that they had not fulfilled the spirit of the Act of 1714 because it might be impossible to copy them for widespread use.

A number of acts were passed with respect to this difficult situation, to complement or in some cases to overcome previous legislation. For example, the Act of 1763 [RGO 14/1:22] was entitled 'An Act for the Encouragement of John Harrison, to publish and make known his Invention of a Machine or Watch, for the Discovery of the Longitude at Sea.' It was intended to enforce the Commissioners’ directions that Harrison make ‘a full and clear Discovery of the Principles’ of his latest timekeeper to eleven named witnesses so that the details could be published in order to allow other clockmakers to reproduce the designs. Once these witnesses or the majority of them certified that Harrison had done so, then the Treasurer of the Navy was to pay the clockmaker £5000 out of any unapplied funds. If he later won one of the longitude rewards as well, then the £6500 which he would have already gotten from the Commissioners in total was to be subtracted from that reward.

After the requirements of 1763 were not met, the second of the 1765 longitude Acts [RGO 14/1:30] sought to settle the Harrison issue, as well as to clarify the powers of the Board and the requirements for granting longitude rewards. The Act would grant £10,000 to Harrison if he explained his timekeepers and gave them to the Commissioners, and another £10,000 when he had copies made and successfully trialled. It also granted rewards to Leonhard Euler and to the widow of Tobias Mayer for work relevant to Mayer’s lunar tables, set up rewards for any improvements made to those tables, appointed the Lowndes Professor of Astronomy at Cambridge a Commissioner, authorised the Board to begin publishing the Nautical Almanac , and allowed the Board to administer oaths to projectors and employees.

In 1774, John Harrison successfully appealed to Parliament for a reward of £8750 on top of all of the sums which he had received in the past. This was in recognition of his efforts and advanced age, and of it not appearing possible to instead grant him the £20,000 reward. This led to the Longitude Act of the same year [RGO 14/1:37], which repealed all former acts except those which appointed the Commissioners and those regarding the production of publications such as the Nautical Almanac. It stated that if a marine timekeeper or another method achieved one of the three staggered levels of precision required in 1714 to win a longitude reward, that its inventor should receive £5000, £7500 or £10,000 – half the size of the original rewards.

He or she would have had to make a full discovery of their designs, turn over their timekeepers to the Board, and have had two or more copies successfully trialled - at the Greenwich Observatory for a year and on two sea journeys around Great Britain going in the opposite directions. Anyone who improved solar and lunar tables to within certain degrees of precision and had them successfully trialled could obtain an award of £5000. The Commissioners also still had the ability to hear and try other proposals if five or more of them agreed, to grant lesser rewards to proposals which still had merit for general navigation, and to administer oaths. The Treasurer of the Navy was to clear the Board’s existing debts.

Although no one ever won the larger awards established in 1774, the Board continued to be involved in the improvement and testing of chronometers made by clockmakers such as Thomas Mudge, Thomas Earnshaw, and John Arnold. The Commissioners also continued to contribute to other activities related to general navigation, science and technology. This included sending astronomers on a number of voyages of exploration and science, like those of Captain James Cook.

The nineteenth century saw continued participation in diverse scientific and navigational activities as well but also significant changes in the makeup and behaviour of the Board. There were questions being raised by the early 1800s about the usefulness of the institution. Its membership under the influence of Joseph Banks was weighted far more towards the Royal Society than to the Admiralty, which did not even send any representatives to the meetings of 1813 to 1815. The quality of the Nautical Almanac after Maskelyne’s death in 1811 had also been criticised.

The longitude Act of 1818 [RGO 14/1:79r] sought to address some of these complaints and to emphasise the institution’s dedication to improving general science and navigation by repealing all previous Acts and reorganising the Board once more. The Board appears to have essentially became a scientific department for the Admiralty. The new Act appointed three salaried Resident Commissioners and three advisors who were Fellows of the Royal Society. It required four rather than three meetings a year, and dictated that the Board submit annual estimates of its expenditures with the Naval estimates.

It appointed the Foreign Secretary of the Royal Society as the Superintendant of the Nautical Almanac and as the Secretary to the Board. The Act further asserted the Commissioners’ ability to grant rewards for navigating the North West Passage, promising rewards on a sliding scale from £20,000 for reaching the Pacific through a north west passage to £5000 for reaching 110 degrees west or 89 degrees north and £1000 for reaching 83 degrees north. A reward of £5000 for reaching 113 degrees west was granted two years later for the efforts of Lieutenant William Edward Perry and the crews of the Hecla and Griper .

Other relatively large rewards granted during the 1800s included the £1200 given to J. Mendoza y Rios for his improved longitude tables in 1814, and the £1000 given to Captain Edward Sabine for his pendulum experiments in 1826. The Commissioners further participated in activities such as the trigonometric determination of longitude between different observatories and cities, the funding of the Glass Committee alongside the Royal Society, and outfitting the new Royal Observatory at the Cape of Good Hope.

Parliament ultimately abolished the Board of Longitude in 1828. However, they replaced it with a Resident Committee for Scientific Advice for the Admiralty consisting of three scientific advisors: Thomas Young, Michael Faraday and Edward Sabine. The Board was, essentially, transmuted rather than abolished entirely.

Alexi Baker
History and Philosophy of Science
University of Cambridge