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Biography of John Harrison

Portrait of John Harrison

John Harrison was an eighteenth century inventor of accurate clocks and watches which solved the longitude problem of navigation at sea.

When and Where was he Born?

31st March 1693, Foulby near Wakefield, Yorkshire, England.

Family Background:

John Harrison was the son of Henry Harrison a Carpenter and mechanic and eldest of five children.


Little formal education.

Timeline/Biography of John Harrison:

1700: The Harrison family moves to the Lincolnshire village of Barrow on the Humber where John becomes involved in carpentry. He had a fascination for music and eventually became the local choirmaster.

1713: John and his brother James decide to confine themselves to the repair and refinement of clocks although they have been taught all sorts of carpentry skills by their father. He builds his first long case clock entirely made out of wood.

1714: The English Admiralty set up an award of £20,000 for anyone who could provide seafarers with a reliable clock that, when used alongside celestial sightings, could show their longitude at sea. At this point mariners had to use dead reckoning whose unreliability often lead to deaths. Clocks of this period where wholly dependent upon weights and the earth’s gravity for their operation. They could not be used at sea due to the motions of the waves.

1718: He marries Elizabeth Barrell.

1725: John Harrison makes the first of three precision pendulum clocks. He develops the grid-iron pendulum which was made of a grid of iron and brass that compensated for changes in temperature. Their different rates of expansion cancelled each other out.

1726: Death of his first wife Elizabeth and he marries Elizabeth Scott.

1728: The Harrison brothers set to work on developing a marine chronometer to try and win the prize. Harrison is introduced to George Graham another clockmaker by the Astronomer Royal Edmond Halley who was a great champion of his work. Graham lends him a large sum of money so that he can continue his work once he saw the original drawings for the marine clock.

Harrison Clocks
John Harrison’s H1 and H2 Clocks at the Royal Observatory, Greenwich (copyright Anthony Blagg)

1736: He demonstrates the finished chronometer to members of the Royal Society who in turn represent him to the Board of Longitude. This was the first clock sent to them that they deemed worthy of a sea trial. Harrison sails to Lisbon on HMS Centurion and comes back on HMS Orford. The Captain of the Orford was particular in praising the design and said that the H1 clock had placed them more accurately than traditional calculations. The board refuses to give the prize as it was not the transatlantic voyage called for in the rules. Harrison sets about building H2.

1741: H2 is now ready, but Britain has entered into the War of Austrian Succession with Spain and it was not thought worth the risk of it being captured by the Spanish. By now Harrison had discovered a design fault in the bar balances. He is given a sum of £500 to tide him over to the end of the war and with this he builds H4.

1752: John Jefferys builds a precision watch from Harrison’s own designs for him.

Harrison's clocks
John Harrison’s h4 sea clock and H4 Sea Watch 
at the Royal Observatory, Greenwich 
(copyright Anthony Blagg)

1759: This watch becomes his first marine watch or “Sea watch”. It is a 5.2 inches in diameter in silver cases and was known as Number One or sometimes H4.

1761: The H4 model proves to be the most accurate chronometer. The Harrison plan was to not only design an internally accurate watch but one that was also externally stable. On a testing voyage to Jamaica on HMS Deptford the watch only showed a five-second error corresponding to an error in longitude of 1.25 minutes, or one nautical mile. Again the Board of Longitude refuse to give up the £20,000 prize as they believed the accuracy to be just luck. Outraged the Harrisons complain and parliament then offered them £5,000 for the design which they refuse. Another trial, this time to Barbados is arranged. The Reverend Nevil Maskelyne is also asked sail on HMS Tartar and test the Lunar Distances system against the H4 watch. Again Harrison’s work is accurate to within ten miles.

1765: The results are presented to the Board of Longitude and once again the Board put it down to just luck. Once again complaints reached the ears of Parliament which offered an advance of £10,000 if the Harrisons turned the design over to other watchmakers to duplicate. H4 was given to the care of the Astronomer Royal to test on the ground. Nevil Maskelyne had been appointed Astronomer Royal on his return from the Barbados trip and therefore a member of the Board of Longitude. His report of H4 was in the negative saying that as it lost and gained some time each day it was inaccurate and refused to certify it for the longitude problem.

1772: The Harrison’s complaints by now had reached King George the Third who tested the new version H5 himself at the palace for ten weeks of daily observations between May and July. He found it to be accurate to within one third of one second per day. King George advised Harrison to petition Parliament for the full prize after threatening to appear himself to admonish them. Harrison finally receives a reward of £8,750 for his work but never received the full prize. (No one else ever got the award either). Harrison’s chronometers had been used by Captain Cook on his charting of the southern Pacific Ocean and one version was even carried on HMS Bounty to Pitcairn Island with William Bligh.

1774: John Harrison writes about his researches into the tuning of musical instruments and the manufacture of bells.

When and Where did he Die?

24th March 1776, at home at 12 Red Lion Square, Holborn, London, England of natural causes.

Age at Death:


Written Works:

1775: “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: As Also an Account of the Discovery of the Scale of Musick .”

“A true and full Account of the Foundation of Musick, or, as principally therein, of the Existence of the Natural Notes of Melody” (Manuscript found in 2002 in the Library of Congress Washington).


  1. 1718 to Elizabeth Barrell (died 1726).
  2. 1726 To another Elizabeth Scott.

Site of Grave:

St. John at Hampstead Churchyard, Hampstead London.

Places of Interest:


Turret clock at Brocklesby Park.


The National Maritime Museum, Greenwich has a copy of K2 watch from HMS Bounty.

Royal Observatory
Royal Observatory, Greenwich (copyright Anthony Blagg)

Royal Observatory, Greenwich has restored versions of H1, H2, H3 and H4 clocks.
Clock Museum, The Guildhall, Worshipfull Company of Clockmakers.
Science Museum.
12, Red Lion Square, Holborn was the last house he lived in.


Clock in the billiards room of Nostell Priory.
Leeds Museum and Art Gallery.