An Act for Providing a Publick Reward for such Person or Persons as shall Discover the Longitude at Sea.

London: Printed by John Baskett … And by the Assigns of Thomas Newcomb and Henry Hills, 1714.

First edition, and a fine copy, of the Act of 1714 establishing a reward for the discovery of a method of determining longitude at sea. “An early example of a means adopted by a government for encouraging scientific discovery and progress” (Grolier/Horblit). John Harrison (1693-1776), among others, was so encouraged and eventually solved the longitude problem with the invention of his chronometer H4. “Harrison’s chronometer not only supplied navigators with a perfect instrument for observing the true geographical position at any moment during their voyage, but also laid the foundation for the compilation of exact charts of the deep seas and the coastal waters of me world … There has possibly been no advance of comparable importance in aids to navigation until the introduction of radar” (PMM 208). “The Act of 1714 constituted 24 Commissioners either by name or office; 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” (Baker). This and the ensuing longitude acts passed between 1714 and 1828 set a precedent for government funding and, within fifty years, also gave rise to a unique standing body, the Board of Longitude, that encouraged and helped to define British science and technology at large. Although it is its conflict with John Harrison, who claimed the prize, which now most characterizes the Board of Longitude, and Parliament’s longitude legislation, in the public mind, the Board involved itself in wide-ranging scientific, technological, and maritime activities – such as the annual publication of the Nautical Almanac, the improvement of diverse technologies, the establishment of observatories abroad, and voyages including those of Captain Cook and of Arctic exploration. The act was issued both separately, as here, and as part of the collected acts of Parliament for the 12th year of Queen Anne’s reign.

“The latitude at sea could easily be determined from the altitude of celestial bodies, but the early sailors had no way to measure the longitude, other than by estimating the number of miles sailed east or west, which was often little more than inspired guesswork. The lack of method was increasingly felt in the seventeenth century and was, in fact, the main reason for the founding of the Royal Observatory at Greenwich in 1675.

“Two particular incidents accelerated the founding of the Board [of Longitude]. In 1707 a squadron under Sir Clowdisley Shovel ran aground off [the Isles of] Scilly with the loss of some 2,000 lives: Britain’s worst maritime disaster. Then in 1713 the mathematicians William Whiston and Humphrey Ditton suggested a scheme for determining longitude by anchoring ships along the main sea-lanes and firing a shell timed to explode at a height of over a mile. The time between the flash and the corresponding sound would give the distance to any ship within range.

“Although completely impractical it received widespread publicity and encouraged a petition to Parliament by several sea-captains and London merchants which suggested that Parliament should offer a prize for finding a solution. The government took this seriously and a Parliamentary committee was set up to report on the problem. Among others this included Isaac Newton, Edmond Halley and Samuel Clarke, and the committee recommended that a reward should be offered for finding longitude at sea.

“A Bill was presented in June 1714 ‘for Providing a Publick Reward for such Person or Persons as shall Discover the Longitude at Sea.’ It received the Royal Assent by Queen Anne on July 20, 1714, only 12 days before she died.

“The Act offered rewards of up to £20,000 for discovering longitude at sea to within certain limits of accuracy: £10,000 if accurate to one degree of the great circle (60 nautical miles), £15,000 if to 2/3° (40 nautical miles) and £20,000 if to 1/2° (30 nautical miles). This sum was unprecedented by the standard of the day. By comparison, the Astronomer Royal’s salary was originally only £100, rising to £300 under [Nevil] Maskelyne. It is estimated that £20,000 in 1714 is the equivalent of at least £1 million in the currency of the 1980s.

“Half the reward was to be paid if the method extended to 80 nautical miles from shore, the place of greatest danger, the other half if successful over a longer distance, such as the voyage to the West Indies. The method had to be ‘practicable and useful at sea,’ a vague term which was to be the subject of much controversy later.

“Small sums could be advanced towards schemes that seemed promising for further experimentation. If a method did not reach the listed limits of accuracy but was still considered to be useful, a smaller reward could be offered. These rewards were open to people of all nationalities and many applicants came from overseas, especially from France and Spain, the other two leading seafaring nations of the day. The reward also stimulated mathematicians and astronomers the world over to work on the problem.

“The Longitude Act appointed a group of Commissioners who came to be known as the Board of Longitude. Their function was to consider the suitability of schemes and pass on their opinions to the government. They obviously had to be selected so that they were competent in dealing with such scientific and technical matters. They comprised admirals, the Master of Trinity House, the President of the Royal Society, the Astronomer Royal, professors at Oxford and Cambridge, and ten members of Parliament [the Astronomer Royal had the final say as to the suitability of schemes and instruments] …

“The basic theory behind discovering longitude is simplicity itself. As each 15 degrees of longitude corresponds to a time difference of one hour, it is only necessary to compare the local time (using the Sun’s highest altitude to determine noon) with the time at Greenwich (or any other reference meridian). One thus had to have on board a timekeeper from which Greenwich time could be found to the requisite precision. The difficulty was to design such a chronometer which could keep time accurately over months on board ship, with extremes of heat and cold, damp or drought.

“The successful inventor was John Harrison, the man who solved the longitude problem and who eventually won the £20,000 prize. The early years of the Board were dominated by Harrison and his chronometers, his problems, the testing of the timekeepers and his struggle to obtain the reward. The earliest surviving confirmed minutes of 1737 open with the words ‘Mr John Harrison produced a new invented machine, in the nature of Clock Work, whereby he proposes to keep time at sea with more exactness than by any other instrument or method hitherto contrived.’ The trials went on for decades, Harrison’s work being encouraged on many occasions by small payments from the Board.

“It was his fourth timekeeper (a large watch, called H4) which was taken on a trial to Jamaica and back in 1761-62. Although Harrison claimed that H4 more than complied with the 1714 Act, the Board disagreed and insisted on a second trial, in which H4 also performed very well.

“The Board was still not fully satisfied, half only of the reward was paid and on condition that Harrison disclosed the construction so that copies could be made. The first of these was built by Larcum Kendall (K1) and was sent with Captain Cook on his second voyage. Despite glowing praise from Cook, Harrison had to appeal to King George III before he was paid the full reward in 1772, at the age of 78. The often-heated exchanges between Harrison and the Board are well-preserved in the archives.

“At the same time as the Board was dealing with Harrison, another method of finding longitude was being acquired. The Moon moves quite slowly across the background stars and its position can in theory be used as a means of finding Greenwich time. The difficulty here was that the Moon’s motions were not known sufficiently accurately for tables to be drawn up months or years in advance to determine longitude with sufficient precision.

“In 1755 the Board received accurate lunar tables from the German mathematician Tobias Meyer. They were derived from equations by Leonhard Euler and the observations of Mayer and James Bradley (Astronomer Royal 1742-62). These were improved by a second set of tables which Mayer bequeathed to the Board on his death in 1762. They allowed longitude to be found to within a few nautical miles and also permitted the position of the Moon to be calculated several years in advance.

“The Board recommended publication of an annual almanac giving the position of the Moon every three hours, and other information, from which longitude could be found. The Nautical Almanac was first published in 1766, for 1767, most of the planning being done by the Astronomer Royal, Nevil Maskelyne. The computations of tables and the printing on the Almanac remained a major interest of the Board …

“With the award of the main prize to Harrison and the foundation of the Nautical Almanac the Board had fulfilled its role under the 1714 Act. However, it was kept in being by a new Act of 1774 which moved the emphasis away from longitude to navigation in general. The scope of the Board became much wider. Improvements and refinements of navigational instruments were a main concern. Chronometers were improved by men such as Thomas Mudge, John Arnold and Thomas Earnshaw, and sextants were refined using an artificial horizon. Greater accuracy was achieved in the technique of ruling the scale divisions on instruments, notably by Jesse Ramsden.

“The Board also entered into such areas as the accurate measurement of ships’ tonnage, meteorology, magnetism and the production of accurate naval charts. It was mainly for the latter reason that the Board became increasingly linked with world exploration through the great voyages of discovery of the late 18th and early 19th centuries … The explorations round Australia, New Zealand and the Pacific owed much to the Board, most notably the second and third voyages of Captain Cook … the Board in 1819 offered rewards for discovering the north-west passage from the Atlantic to the Pacific, or for progressing towards the North Pole … The last major project undertaken by the Board was the foundation of the observatory at the Cape of Good Hope. Its aim was to increase the knowledge of the southern skies and improve navigation south of the equator. The first mention is at the Board meeting of 3 February, 1820 … By this time, though, the role of the Board was becoming even less well-defined and uncertain. It was increasingly linked with the pure astronomy at the Royal Observatory, Greenwich. The ardour of the great voyages of discovery had cooled … Areas of work into which the Board might have moved were taken over by two societies formed about this time, the Astronomical Society of London (later the Royal Astronomical Society) and the Royal Geographical Society. Its remaining responsibilities were subsumed into the work of the Royal Observatory …

“The Board of Longitude was finally dissolved on July 15, 1828 by Act of Parliament. It had been in existence 114 years. Nevertheless, in its time it had been a colourful and influential body. The rewards offered in 1714 stimulated many advances during the next 114 years over a very wide field, just as Parliament hoped would happen. Progress in astronomy worldwide, as well as in navigation and horology, was greatly furthered by the Board’s activities. The Board of Longitude was certainly one of the most important and interesting bodies in the development of science and technology of that period” (Johnson).

Grolier/Horblit 42a. Baker, ‘Longitude Acts,’ Cambridge Digital Library (cudl.lib.cam.ac.uk/view/ES-LON-00023). Johnson, ‘The Board of Longitude 1714-1828,’ Journal of the British Astronomical Association 99 (1989), pp. 63-69.



Folio (278 x 186 mm), pp. [ii], 355-357, [1, blank], title with woodcut royal arms, factotum initial opening text. Stitched.

Item #4825

Price: $12,500.00