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John Harrison

John Harrison - clockmaker

Born 1693 - Died 1776

picture of John Harrison

John Harrison was the son of a carpenter from Foulby, near Nostell Priory, West Yorkshire. Although he could not write, he taught himself to make clocks. He heard of the prize offered by the Board of Longitude and decided that he would have a go. He knew that the winning clock must not gain or lose more than 2.8 seconds a day while at sea. Harrison built the first 'marine time-keeper' (now known as 'H1'). When it was tested, it was far better than any clock that had ever been to sea before - but it wasn't good enough to win the Longitude prize. He was paid a total of £500 to enable him to work on a modified design.

By the time 'H2' was finished, two years later, Harrison realised that this clock, also, would not win the prize. Without even having it tested at sea, he set to work on yet another - his third design known as 'H3'. He worked on 'H3' for the next 19 years, but, before he had finished it, he knew that it was too big and heavy. He went on to build on 'H4'. From the outside, this clock looked rather like a giant pocket-watch. It was tested at sea in 1761. Harrison was confident that 'H4' had performed well enough to win the £20,000 prize, but the Board of Longitude demanded that further tests be carried out and that copies of 'H4' be made.

It was only after the intervention of King George III, many years later, that Harrison was properly rewarded for his work. He died three years later on his 83rd birthday at his home in Red Lion Square, London. A blue plaque commememorates this.
Harrison's clocks 'H1'to 'H4' are still in full working order at the Old Royal Observatory today.

For more information see the Clockmakers website at and the Royal Observatory website at

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