Harrison, John

views updated May 29 2018

Harrison, John

(b. Foulby, Yorkshire, England, 24 March [?] 1693; d. London, England, 24 March 1776)


Harrison’s father, Henry, a carpenter and joiner, moved to Barrow-upon-Humber, Lincolnshire, about 1697; his mother was Elizabeth Barber. He worked with his father, as well as doing surveying and clock repairing. With his brother James he made several clocks, one with a frictionless, ’almost continuous-impulse, grasshopper escapement and compensating bimetallic gridiron pendulum. They also used cycloidal cheeks and maintained power as Huygens had done; it is not known whether they knew of his work. The gridiron pendulum, based on experiments on the relative expansion of iron and brass, combined the two metals mechanically to cancel temperature error.

In June 1730, Harrison completed a twenty-three-page manuscript on experiments and inventions applied to clocks and outlined a timekeeper for use on ships to determine longitude. He was, of course, aware of the £20,000 prize offered by Parliament in 1714 for a reliable, accurate method of finding longitude at sea. In London to promote building this sea clock, be discussed it with George Graham, leading maker of clocks, watches, and instruments, who encouraged him with an unsecured, interest-free loan.

Returning home, Harrison produced a cumbersome marine clock using his earlier inventions and with two interconnected bar balances designed to be immune to the lurching of a ship. In 1737 the device was tested on a voyage to Lisbon. Few records survive, but on the return the landfall was identified by dead reckoning as the Start, Harrison’s clock correctly indicated the ship’s position to be off the Lizard, 57.5 nautical miles further west.

The Board of Longitude now granted £500 to encourage further experiment and the brothers moved to London, where a stronger and slightly smaller version of the marine clock was made. Unsatisfactory, it was not tried at sea. James returned home and John began a third machine, not ready for test until 1757. Next Harrison conceived of a radically different timekeeper in the form of a large watch—although, of course, with an entirely different escapement. As accurate as the third machine and far more convenient in size, it alone was tested on a voyage to Jamaica in 1761. On arrival, more than nine weeks later, it was only five seconds slow, about 1.25 minutes of arc, well within the 30 minutes of arc or longitude required. A second trial, to rule out a possibly fortuitous combination of circumstances, was held in 1764, and the results were also well within the limits.

Half the prize was now paid, but many previously unstipulated obstacles were raised. All four machines had to become property of the Board of Longitude; a minute description of the winner was required; it was subjected to extreme and unrealistic tests; and two more examples had to be built Larcum. Kendall, a well-known watchmaker, made one and Harrison, assisted by his son William, made another, slightly simplified. Accusations that the Board of Longitude was unfair and in some degree favored a system of lunar distances for finding longitude reached George III, who took Harrison’s side. Harrison’s last instrument was tested at the king’s private observatory at Kew, and on the basis of its performance there, Harrison petitioned the House of Commons in 1772. The Board of Longitude, now on the defensive, dropped its opposition, and the award was made in 1773. Although soon supplanted by simpler mechanisms, the use of timekeepers to find longitude stemmed directly from Harrison’s persistence and ability.


I. Original Works. The following MSS are available: untitled MS, signed and dated (Barrow-upon-Humber, 10 June 1730), with 2 pp. ink drawings, describing experiments and clock designs, Guildhall Museum, London, MS 6026 (no. 4); “Proposal for Examining Mr. Harrison’s Timekeeper at Sea” (Dec. 1762), British Museum, 717K.15; “A Calculation Showing the Result of an Experiment Made by Mr. Harrison’s Timekeeper... in a Voyage From Portsmouth to Port Royal in Jamaica...” (Dec. 1762), British Museum, 717K.15; “An Explanation of My Watch or Timekeeper for the Longitude... With Some Historical Account Coincident to My Proceedings” (7 Apr. 1763), Guildhall, MS 3972 (no. 1); and “Some Account of the Pallats etc. of My Second Made Watch for the Longitude” (3 May 1771), Guildhall, MS 3972 (no. 2).

Published works are Remarks on a Pamphlet Lately Published by the Rev. Mr. Maskelyne... (London, 1767); and A Description Concerning Such Mechanism as Will Afford a Nice, or True Mensuration of Time; Together With Some Account of the Attempts for the Discovery of the Longitude by the Moon; and Also an Account of the Discovery of the Scale of Music (London, 1775).

II. Secondary Works. See Dictionary of National Biography, XXV. See also the following, listed chroaologically: Rev. Nevil Maskelyne, An Account of the Going of Mr. Harrison’s Watch... (London, 1767); Thomas Reid, A Treatise on Clock and Watchmaking (Edinburgh, 1826); Johan Horrins (pseudonym of John Harrison, grandson of John Harrison), Memoirs of a Trait in the Character of George III... (London, 1835): R. T. Gould, The Marine Chronometer (London, 1923); and “John Harrison and His Timekeepers,” in Mariner’s Mirror, vol. 21 , no. 2 (Apr. 1935); and Humphrey Quill, John Harrison, the Man Who Found Longitude (London-New York, 1966).

Edwin A. Battison

Harrison, John (1693-1776)

views updated May 29 2018

Harrison, John (1693-1776)

English clockmaker and carpenter

John Harrison solved the so-called "longitude problem," that is, he developed the means to enable navigators to calculate their east-west (longitudinal) positions at sea. A ship's north-south (latitudinal) position is easily computed from the Sun , stars, date, and local time, but to calculate longitudinal position a navigator must also know the current time at the home port and compare it with the local time of the ship as determined by observing the Sun and stars. This calculation is based on the fact that every hour represents 15 degrees of longitude . The principle was known centuries before Harrison, but using it was not possible in practical navigation until he invented his portable, durable, and extremely accurate clock, which proved reliable under the harsh conditions of the sea.

Born the son of a carpenter on March 24, 1693, in Foulby, Yorkshire, England, Harrison early learned his father's trade as well as surveying, clockmaking, bell tuning, and several other practical skills. He also enjoyed music and was a singer. The family moved to Barrow-on-Humber, Lincolnshire, while Harrison was still a child. In the 1720s, he began a professional association with his brother James, born in 1704. Together until 1739, they designed and built beautiful, precise, reliable clocks, soon renowned as the most accurate in Britain.

As the world's dominant sea power from the end of the sixteenth century until the middle of the nineteenth, Britain was keenly aware of the longitude problem and was quite serious about solving it. In 1675, King Charles II founded the Royal Observatory at Greenwich, England, mainly to gather data for the longitude problem. In 1714, the British Parliament passed the Queen Anne Act, which offered a prize of £20,000 (about £1,932,917 in 2001 British money or $2,811,860 in 2001 American money) to anyone who could calculate a ship's longitude to within a half-degree throughout its voyage from Britain to the West Indies. Many tried and failed to win that prize.

Fixed on winning the prize, Harrison began working on the longitude problem in 1730 and submitted his first sea clock, known as the H1 chronometer, to the Board of Longitude in London in 1736. On the basis of H1's partial success, the Board gave him financial assistance to continue his research. From 1737 to 1740, he worked on a larger instrument, H2, but it failed. His experiments with H3 from 1740 to 1749 also ended in failure. In 1755, he stumbled across an entirely different design for H4, similar to a pocket watch. The test results of H4 on the voyage of the Deptford to Jamaica in 176162 and on the voyage of the Tartar to Barbados in 1764 exceeded the stipulations of the Queen Anne Act.

Despite the success of H4, the Board of Longitude awarded Harrison only £10,000. The Royal Astronomer Nevel Maskelyne (17321811), even though he was aboard the Tartar during the trial of H4, remained unconvinced that any timepiece could be a more accurate indicator of longitude than the popular "lunar distance method," by which navigators computed longitude from their observations of the Moon's position relative to selected stars, according to tables prepared by the Royal Observatory. Maskelyne was jealous of Harrison, whom he spurned as a mere "mechanic," and changed the rules of the contest to favor astronomers.

Harrison, with his son William, spent the rest of his life trying to claim the second half of his prize. The Board was adamant about not giving it to him but, in 1773, after Harrison appealed to King George III, Parliament grudgingly recognized his having solved the longitude problem and gave him an additional £8,750. All four of his marine chronometers are now in the National Maritime Museum, London. He died in London on his birthday in 1776.

See also History of exploration II (Age of exploration); Latitude and longitude; Time zones

Harrison, John

views updated May 17 2018

Harrison, John (1693–1776). Horologist. From the 15th cent. onwards, when mariners began to make long ocean voyages, the difficulty of estimating the exact longitude at sea had cost the lives of thousands of sailors, most notably of Sir Clowdesley Shovell and his crews off the Scillies in 1707. In 1714 Parliament, in the Longitude Act 12 Anne c. 15, offered a handsome first prize of £20,000 to anyone who could solve the problem. There were two approaches. First was by plotting moon, planets, and stars and observing them: this was difficult in boisterous or stormy weather, and impossible in heavy cloud. The second was to develop an extremely accurate timepiece, which would not be affected by salt water, damp, or violent motion on board, and use it to maintain the time of setting sail for comparison with the time as measured by the sun. Pendulum clocks would not serve since the metal was affected by heat and cold and the swing by the pitching of the vessel. John Harrison, a clock-maker from Foulby near Pontefract in Yorkshire, who later moved to Barrow-on-Humber, devoted his life to making four brilliant clocks, now preserved at Greenwich, and claimed the prize. For 40 years he was frustrated, partly by his own perfectionism, partly by obstruction by his rivals in the astronomic camp, particularly Nevil Maskelyne, appointed astronomer-royal in 1765. In the end the intervention of George III, who had an interest in astronomy, persuaded Parliament in 1773 to allow Harrison his full prize. He was then 80. His clocks were masterpieces of skill, precision, ingenuity, and determination.

J. A. Cannon