John HarrisonClockmaker & Inventor
Who was John Harrison?
John Harrison is famous throughout the world for building clocks accurate enough to solve ‘the problem of longitude’. In doing so he enabled safer and swifter travel for thousands of ships.
Why was it a problem?
Ocean-going ships need to know where they are. Without accurate knowledge ships go off course, frequently 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.
To plot their position, ships needed to know latitude (distance north or south of the Equator) and longitude (distance east or west of their point of departure). Latitude could be calculated easily using the Pole Star or other heavenly bodies, but longitude could 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. What was required was a clock which could run precisely for weeks at a time, irrespective of changes in temperature and humidity, and furthermore could function accurately on-board ship, even when the ship is being thrown about by a rough sea.
What did Harrison do?
He built a series of clocks of amazing accuracy able to keep good time even at sea. Eventually he was awarded most of the prize, though the government was reluctant to do so. It took him most of his adult life to achieve it.
What has this to do with Barrow?
The Harrison family moved to Barrow when John was very young and he was in his 40s when 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:
- There is a memorial to him in Westminster Abbey
- He was named 39th in the top 100 Greatest Britons (2002 BBC public poll)
- He was a carpenter with no formal education – he and his brother James taught themselves how to mend and make clocks.
- He was choirmaster of Barrow church and he retuned Barrow church bells so well that he was asked to do the same for a major church in Hull.
- One of his early clocks can be seen (still working) at Brocklesby Park.
- Many of his clocks use ‘lignum vitae’ (a special wood) for moving parts, which requires no lubrication.
- Harrison built his first longcase clock in 1713, at the age of 20. The mechanism was made entirely of wood.
- Harrison spent seventeen years working on this third ‘sea clock’ but still wasn’t satisfied with it.
- Nevertheless, his work led to two inventions which engineering has relied on ever since: the bimetallic strip and the caged roller bearing.
- Harrison finally received most of the prize money by speaking directly to King George III who gave him his support.
- Harrison was also interested in music theory and invented a new musical scale..More
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. www.rmg.co.uk/harrison