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John Harrison 1693-1776

John Harrison

Carpenter and clockmaker

Who was John Harrison?

John Harrison is famous throughout the world for building clocks accurate enough to solve ‘the problem of longitude’. As a consequence travel became safer and swifter for thousands of ships.

Why was it a Problem?

Ocean-going ships need to know where they are. Without this accurate knowledge ships go off course, frequently hitting rocks or running aground with tragic consequences. It was such a problem that the Government in 1714 offered a prize of £20,000 (over £2m today) to anyone who could solve it.


Why Longitude?


To plot their position, ships needed to know latitude (distance north or south) and longitude (distance east or west). Latitude can be calculated by taking sightings on the Pole Star or other stars, but longitude can not. To do so, sailors needed to know the exact time at a fixed point, agreed early on to be the Royal Observatory at Greenwich.

Why not look at a clock?

No clock existed that was accurate enough. As well as needing to run precisely for weeks at a time, it would need to take account of changes in temperature and humidity and to function as the ship rolls and pitches on the uneven, rolling surface of the sea.

What did Harrison do?

He built a series of clocks of amazing accuracy able to keep good time even at sea. The government was reluctant to  awarded John Harrison the prize as he was not well connected. Eventually he was awarded most of the prize money after appealing to the King, George III.

What has this to do with Barrow?

The Harrison family moved to Barrow when John was very young. When he was in his 40s he moved to London. It was here in Barrow that he and his brother James taught themselves to mend and make clocks. As well as taking an active role in the village, for example as choirmaster, he built his first clocks here, including the first famous marine chronometer, the H1 in 1735.  John Harrison is truly a Barrovian, and one of enormous importance.

Ten things you may not know about John Harrison
  1. There is a memorial to him in Westminster Abbey

  2. He was named 39th in the top 100 Greatest Britons (2002 BBC public poll)

  3. He was a carpenter with no formal education – he and his brother James taught themselves how to mend and make clocks.

  4. He was choirmaster of Barrow church and he re-tuned Barrow church bells so well that he was asked to do the same for a major church in Hull. He was so interested in music he invented the rules for a new musical scale.

  5. One of his early clocks can be seen (still working) at Brocklesby Park.

  6. Many of his clocks use ‘lignum vitae’ (a special wood) for moving parts, which requires no lubrication.

  7. Harrison built his first longcase clock in 1713, at the age of 20. The mechanism was made entirely of wood.

  8. Harrison spent seventeen years working on this third ‘sea clock’ but still wasn’t satisfied with it.

  9. His work led to two inventions which engineering has relied on ever since: the bimetallic strip and the caged roller bearing.

  10. Harrison finally received most of the prize money by speaking directly to King George III who gave him his support.

Three of Harrison’s timepieces, together with the H4 watch, which became the basis from which all marine chronometers were devised, can be seen in working order at the National Maritime Museum, Greenwich. See

John Harrison Memorial Westminster Cathedral

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