Harrison’s Clocks

by John

I have seen these famous clocks in the past,  before I had read “Longitude”.  But now, knowing how incredibly important it was to have an accurate marine chronometer, and knowing the story of how a carpenter, John Harrison, invented, developed, and made the world’s first accurate marine chronometers in the early eighteenth century, I could not miss the opportunity to revisit the Royal Greenwich Observatory, on my visit to Greenwich.

Amazingly, 3 of the 4 clocks are still working accurately.  I am not sure why the final, wonderful, Harrison 4 is not working.  That is the clock which finally made Harrison a wealthy person.

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Harrison 1.  Intriguing mechanism, but had wooden gears and other wooden parts, and was not quite accurate enough.  It weighs 30kg.

 

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Harrison 3.  More compact.  All brass gears and shafts. No bobbing pendulums.   Still heavy, but a bit less bulky.  19 years in development, and still not up to scratch according to Harrison, who was probably a bit OCD.  One aspect which really impressed me with these clocks, was the incredibly high standard of metal work and metal finishing.

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Harrison 4.   Like a big pocket watch.  But won him the prize, and made him a very rich man.  Unfortunately Harrison died not too long after winning the prize.

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John Harrison with his final chronometer.  And a picture behind him of number 2 (I think)

The board which was determining whether his chronometer (number 4) was worthy, dallied and prevaricated to avoid paying Harrison the 20,000 pound prize.  Fortunately, King George 2 intervened and took up Harrison’s cause, and eventually he was paid a total of 23,000 pounds, which made him the equivalent of a modern multi millionaire.

His Harrison 4 kept time on a moving, rocking ship, within 1 minute in 90 days, which was a quantum leap in accuracy, and resulted in vastly more accurate navigation, and saving sailors lives.

“Longitude” is an excellent read.  And seeing these timepieces in reality, was an experience which I will not forget.