The Marine Chronometer and John Harrison
John Harrison (1693-1776) was the English clockmaker whose marine timekeepers solved the problem of finding longitude at sea.
John Harrison (1693-1776) was the English carpenter and clockmaker whose marine timekeepers solved the problem of finding longitude at sea. He taught himself the trade, worked on the problem from 1730 into the early 1770s, and with the large watch known as H4 made it possible to fix a ship's longitude across the Atlantic to within about one nautical mile. The £20,000 prize offered for this was never formally given to him, though the Board of Longitude and Parliament paid him £23,065 in all.[1]
Foulby and the Move to Barrow
Harrison was born at Foulby, in the parish of Wragby in Yorkshire. By the modern calendar his birthday is 3 April 1693. Old-style dates are given as 23 or 24 March, and the Wragby register records his christening on 31 March.[1][3] His father Henry Harrison (1665-1728) was a carpenter and joiner who had married Elizabeth Barber on 7 June 1692. Some accounts describe Henry as a stepfather, while the Dictionary of National Biography and the Barrow village records call him the father.[1][2][3] John was the eldest of five children, followed by Mary, Henry, James and Elizabeth. James (1704-1766) would later help him with the clocks.[3]
Henry worked on Sir Rowland Winn's estate at Nostell Priory. Winn also held land at Barrow upon Humber in Lincolnshire, and the family moved there, in 1697 according to the village records and around 1700 according to other sources.[1][2][3] Henry became churchwarden and parish clerk at Barrow and died there in 1728.[3]
Written evidence for the childhood is thin. A familiar story has a watch being laid on his pillow when he was six and sick with smallpox. Watches were expensive and no clockmaker is known to have worked nearby, so the story is now treated with suspicion.[1] He had little schooling. A clergyman lent him a manuscript of the Cambridge mathematician Nicholas Saunderson's lectures on natural philosophy, and Harrison copied it out by hand, diagrams included.[2] That copy was his written grounding in mechanics, and the rest came from the bench.
From Carpenter to Clockmaker
His first trade was his father's. He did carpentry, surveyed land, repaired clocks and tuned bells. He also loved music and became choirmaster at Holy Trinity in Barrow, where he retuned the bells well enough for a major church in Hull to ask him to do the same.[3][7] Clockmaking started as spare-time work alongside all this. Wood was the material he knew, so the first longcase clock he finished, in 1713 at the age of 20, had a movement made entirely of it. Two more followed, dated 1715 and 1717, and all three survive.[1]
On 30 August 1718 he married Elizabeth Barret, whose name also appears as Barrel. She died in 1726, or 1724 according to another summary, and on 23 November 1726 he married Elizabeth Scott. Their son William, who would become his main assistant, was born at Barrow in 1728.[1][8][12]
In the early 1720s he built a turret clock for Brocklesby Hall in Lincolnshire, and it still runs. Clock oil thickened with age and changed a clock's rate. Harrison avoided it by using the hard wood lignum vitae for moving parts, which then needed no lubrication. The same clock carried his grasshopper escapement, developed from the anchor escapement.[1][3]
Between 1725 and 1728 he and James built a set of precision longcase clocks. Heat lengthened a pendulum and threw a clock off, so Harrison alternated brass and iron rods in such a way that their expansions cancelled out. This was the gridiron pendulum, and with it the clocks kept to about a second a month.[1][4] The next task was to get that kind of accuracy at sea.
The Longitude Problem and the 1714 Act
A navigator could find latitude from the sun or a star. Longitude needed a clock. The earth turns 15 degrees an hour, so every four minutes between local noon and the time at the home port meant one degree of longitude. That sum was useless without something on board that kept home-port time. The pendulum clocks of the day were upset by a ship's motion, and changes in temperature altered their oil and metal.[10]
The usual way into this story is a disaster. On 22 October 1707 Admiral Sir Cloudesley Shovell's fleet ran onto the rocks of the Isles of Scilly. The flagship Association, Eagle, Romney and Firebrand were lost, with between 1,400 and 2,000 men. Shovell's body came ashore on St Mary's the next day.[5] Dava Sobel's popular book blames longitude error. Historians now point to bad charts and pilot books, poor compasses and the fleet's reliance on dead reckoning after 21 October. No source from the time links the wreck directly to longitude, though the size of the loss may well have added to the anxiety about navigation.[5]
In 1713 William Whiston and Humphrey Ditton brought a longitude proposal to Parliament. Isaac Newton and Edmond Halley advised the committee that looked at it, and the Longitude Act became law on 8 July 1714. The Act named no method and measured only the result. On a voyage of about six weeks from Britain to a West Indies port, an error within 1 degree would earn £10,000, within 40 minutes £15,000 and within 30 minutes £20,000.[6] Most people expected the answer to come from the sky, from the motion of the moon in particular.
Nobody knows exactly when Harrison heard about the prize, though he is said to have decided on it during the 1720s.[8] The target followed from the arithmetic. Half a degree of longitude is two minutes of time, which over six weeks is close to three seconds a day, and Royal Museums Greenwich gives three seconds a day as the accuracy he was after.[4]
First Trip to London and H1
In a manuscript dated at Barrow on 10 June 1730 he set out his experiments and a design for a sea clock. He took his ideas to London, in 1730 according to Wikipedia and in 1728 according to the Dictionary of National Biography.[1][2][7] He went first to Greenwich to see the Astronomer Royal. Halley received him warmly, felt unable to judge the work and sent him on to George Graham, a leading London clockmaker. Graham told him to build the clock first and lent him money for it without interest.[2][4][7]
Back in Barrow he built H1 between 1730 and 1735, probably with James's help. It stood 67 centimetres high and was made of brass, bronze, steel, oak and lignum vitae.[4][13] Because waves would ruin a pendulum, it used two balances instead. He tried it on the Humber, brought it to London in 1735, and it went into Graham's workshop.[4]
In May 1736 he sailed with it to Lisbon on HMS Centurion under Captain George Proctor. The voyage went badly and the clock lost time. He came back on HMS Orford and this time it ran well. As they neared England the officers took the headland in sight for the Start. Harrison said it was the Lizard and that the ship was 60 miles off course, and he was right.[1][4]
H2, H3 and the London Years
The test that counted for the prize was a West Indies voyage, but rather than go there with H1 Harrison proposed to build something better. Eight commissioners met to discuss it on 30 June 1737, and there is no record of the Board meeting before that date. They set aside £500, paid £250 up front, and he promised the new clock within two years.[4][6] He moved to London around this time. James stayed with him for two years and returned to Barrow in 1739 to go on building bell frames.[3]
H2 took three years to build and two to test on land, and it was ready in 1741. Harrison never sent it to sea. He had found a basic fault in its bar balances, and the war with Spain made a trial difficult anyway.[1][4] In 1740 he began H3, which took him 19 years because its circular balances and their springs would not behave as he wanted. The Board paid him £2,000 in instalments over these years, and in 1749 the Royal Society gave him its highest honour, the Copley Medal.[2][6][8] H3 was never a good timekeeper. It did leave behind two inventions still in everyday use, the bimetallic strip and the caged roller bearing.[1]
The way out came from an unexpected direction. Around 1751-52 he had the watchmaker John Jefferys make a watch to his design. That watch, and the good timekeeping of Thomas Mudge's watches, drew him away from the big machines. By about 1755 he had seen H3's basic faults and started on a new instrument in the form of a watch.[1][4][7]
H4 was finished in 1759, when he was 66. It was a silver-cased watch about 13 centimetres across. Its large balance swung faster and wider than an ordinary watch's and ticked five times a second. It ran for 30 hours and had diamond pallets.[1][4]
The Jamaica Voyage, 1761
The Board allowed a trial in 1761. Harrison was 68, so his son William went instead. Before the trial H4 lost 24 seconds in nine days, and its daily rate was set on that basis. HMS Deptford left Portsmouth on 18 November 1761. On the way out William used the watch to predict the landfall at Madeira earlier than the crew expected, and the captain asked to buy the next one.[1][4]
The ship reached Kingston 81 days and 5 hours later. H4 had lost 3 minutes 36.5 seconds in total, which put it only 5 seconds slow against the set rate. That came to an error of about 1.25 minutes of longitude, or about one nautical mile. William returned on HMS Merlin and reached England on 26 March 1762.[1] The Board questioned the observations and demanded another trial. Parliament offered £5,000 and the Harrisons turned it down.[1][4]
Barbados and Maskelyne
The second trial was to Barbados, and this time rival methods were tested too. The astronomer Nevil Maskelyne sailed on the Princess Louisa in September 1763 to try lunar distances and was in Bridgetown by early November. William Harrison boarded HMS Tartar with H4 in March 1764 and arrived in May. The watch was out by 39 seconds, an error of under 10 miles. Maskelyne's method was out by about 30 miles.[1][4]
In February 1765 the Board accepted that H4 had stayed within the limits of the Act and still attached conditions to the money. The first £10,000 depended on Harrison explaining the principles of the watch, the rest on other makers producing similar ones. This became law on 10 May 1765. Harrison believed the whole prize was already due and did not want to give up his secret.[4][8] Once he had explained the watch he received £7,500, with earlier payments taken off.[6]
By then Maskelyne had become Astronomer Royal. On 5 May 1766 he took delivery of H4, tested it at Greenwich for 10 months and published poor results. Harrison disputed them and the quarrel flared again.[4] He saw Maskelyne as a rival favouring the lunar method. In 1767 the Board took H4 and its drawings and commissioned the watchmaker Larcum Kendall to copy it.[8]
H5, the King and the Last Payment
While H4 was under test, Harrison and his son began a fifth timekeeper. After three years he appealed directly to George III. His grandson, also John Harrison, wrote about the episode in Memoirs of a Trait in the Character of George III, published in 1835 under the name Johan Horrins.[7] The king observed H5 himself every day for ten weeks between May and July 1772, and it kept to within a third of a second a day. The Harrisons then petitioned the House of Commons. In 1773, when he was 80, Parliament paid him £8,750.[1][7] It came as a reward for services, not as the prize named in the Act. His total was £23,065, and the full £20,000 was never awarded to anybody.[1][4]
Last Years and Death
His last home was in Red Lion Square, London, and he was still writing. A manuscript dated 1775 brings together his thoughts on time, longitude and music, including his own musical scale worked out from pi and logarithms. It is now in the US Library of Congress.[3] John Harrison died on 24 March 1776, aged 82, and was buried in the churchyard of St John at Hampstead.[1][2]
His wife Elizabeth died a year later aged 72 and joined him there. William became a Fellow of the Royal Society and a governor of the Foundling Hospital, served as High Sheriff of Monmouthshire in 1791 and died in 1815. Harrison had never belonged to the Worshipful Company of Clockmakers, but it was the Company that restored his tomb in 1879.[1][12]
K1 and Cook's Voyages
What settled the argument in practice was that H4 could be copied. Kendall delivered his copy, K1, to the Board on 13 January 1770, and was paid £450 plus a £50 bonus. James Cook took K1 on HMS Resolution for his second voyage (1772-1775), tested it with the astronomer William Wales and told the Admiralty in 1775 that it had done better than its keenest supporters had expected. It went with him on the third voyage, stopped off Kamchatka in 1779 and broke a balance spring. It sailed with the First Fleet to Australia in 1787 and was retired to Greenwich in 1802.[9]
K2, built at about half the price of K1, was on William Bligh's Bounty. Bligh logged its daily rate in 1787, and the mutineers took it when they took the ship. It turned up on Pitcairn Island in 1808 and reached the British Museum around 1840. The cheaper K3 cost £100 in 1774 and fell short of the required accuracy, though it still served on Cook's third voyage and with George Vancouver from 1791 to 1795.[9]
From H4 to the Production Chronometer
Early chronometers could cost about 30 percent of the price of a ship. John Arnold and Thomas Earnshaw took that barrier down, both patenting simpler escapements in 1780. A simple detent escapement with temperature compensation on the balance remained the standard form of the marine chronometer until the electronic age.[1][10] By 1825 the Royal Navy was issuing chronometers to its ships as routine. The same layout went into mass production in the Second World War, when about 13,000 Hamilton Model 21s were made. The US Navy kept them as a backup to Loran-C until 1988, when GPS was approved as reliable.[10]
The Clocks Rediscovered
Harrison's clocks were gradually forgotten at Greenwich. After the First World War they were brought back into view by Rupert Gould, a retired naval officer, who got permission to restore them in 1920 and finished in 1933. His book The Marine Chronometer, published in 1923, was the first scholarly work on the subject.[11] Dava Sobel's Longitude of 1995 took Harrison to a wide audience, and in the 1999 television drama based on it he was played by Michael Gambon. A memorial stone was unveiled in Westminster Abbey on 24 March 2006, and a bronze statue by Marcus Cornish went up at Barrow upon Humber in February 2020. He came 39th in the BBC's 100 Greatest Britons poll of 2002.[1][3]
The Royal Observatory Greenwich now displays the originals of H2, H3 and H4 and a replica of H1. The original H1 is being conserved at the Prince Philip Maritime Collections Centre, and H5 belongs to the Clockmakers' Company.[1][4] A ship's position now comes from satellites. Distance to go and the fuel needed for it are worked out under fuel management and depend on the type of fuel on board.
Frequently asked questions
Who was John Harrison?
John Harrison (1693-1776) was the English carpenter and clockmaker whose marine timekeepers solved the problem of finding longitude at sea. He was born at Foulby in Yorkshire, grew up at Barrow upon Humber in Lincolnshire and taught himself clockmaking.
What did John Harrison invent?
He is best known for the H4 sea watch. He also developed the gridiron pendulum, the grasshopper escapement, the bimetallic strip and the caged roller bearing.
How did H4 solve the longitude problem?
H4 carried home-port time accurately at sea. A navigator compared it with local noon and counted every four minutes of difference as one degree of longitude. On the 1761 Jamaica voyage the watch's error came to only 5 seconds in 81 days.
Did John Harrison win the longitude prize?
The full £20,000 prize was never formally awarded to anyone. Harrison received £23,065 in total from the Board and Parliament, the last £8,750 in 1773 with the support of George III.
Where can Harrison's clocks be seen?
H2, H3 and H4 and a replica of H1 are on display at the Royal Observatory Greenwich in London. H5 belongs to the Worshipful Company of Clockmakers.
Sources
- Wikipedia. John Harrison.
- Gordon Goodwin. Harrison, John (1693-1776), Dictionary of National Biography, vol. 25, Wikisource.
- Better Barrow. John Harrison, Family and Musicologist pages, barrow-upon-humber.co.uk.
- Royal Museums Greenwich. Harrison's Clocks and the Longitude Problem.
- Wikipedia. Scilly Naval Disaster of 1707.
- Wikipedia. Longitude Rewards; Board of Longitude.
- Encyclopedia.com. Harrison, John (Gale and Oxford reference entries).
- EBSCO Research Starters. John Harrison.
- Wikipedia. Larcum Kendall.
- Wikipedia. Marine Chronometer.
- Wikipedia. Rupert Gould.
- Royal Museums Greenwich. Maritime Memorials, M2, St John-at-Hampstead.
- Royal Museums Greenwich. Marine Timekeeper H1, ZAA0034, collection record.
