Harrison precision pendulum-clock No. 2

Contributed by Leeds Museums and Galleries

Precision pendulum-clock No. 2, 1727. Photograph taken by Jeff Darken

These clocks, because of their technical innovations, achieved unprecedented accuracy and are the direct link to H-1.At a dinner at 10 Downing Street, astronaut Neil Armstrong, not long after his walk on the moon, gave a toast to Englishman John Harrison, inventor of the marine chronometer. "You, ladies and gentlemen, started us on our journey." This clock is part of the story of John Harrison's relentless quest to develop a practical method of determining longitude at sea, using the time difference principle. By having a reliable timekeeper set to the time at a known longitude, for example, a ship's home port, and comparing this to local time, which could be accurately determined by observation of the sun and stars, the time difference could then be converted to an east or west distance from the fixed geographical point that the timekeeper represented. Not being able to fix location accurately was the cause of much loss of shipping, cargoes and lives, and a major impediment to economic growth. Made in response to The Longitude Act of 1714, Harrison achieved extraordinarily accurate timekeeping on land and then set about making a portable version, H-1, the world's first successful marine timekeeper. The eventual outcome was H-4 the acknowledged winner of the Longitude Prize.

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  • 1. At 21:06 on 27 March 2010, Ian Fraser wrote:

    Some of Harrison?s inventions are with us today, for example bi-metallic springs, commonly used in thermostats, and caged roller bearings. These are fundamental bits of technology that are in common usage in all manner of machines. Harrison was not only a brilliant man, he was a truly great man too. He used his intellect and determination to solve the most intractable scientific problem of the time. With his timekeepers he made an exploratory foray into the waters of space-time and he found a way forward. He used time, the 4th dimension, to fix points on the three-dimensional globe, and his solution has had widespread and incalculable benefits for all humanity. Because we have good maps and instruments we can know where we are, and because of that we can plan our travels, and get there with as much safety and certainty as is possible. Thanks to John Harrison and a lot of very clever people like him we can do that. Their tools are their brains, sciences and maths and they use them to solve problems to help people. We take it for granted, but just think what the world and our lives would be like if we could not tell where we are. Sciences and maths can be hard, but they are very important. In a way the Earth is like a ship floating through space and time, and we, and all life on Earth, are its passengers. It?s our only home. We?ve all heard about climate change, how man is affecting and damaging the environment. Now, more than ever, Earth and all the people and life on it need people like John Harrison, problem-solvers, engineers, and scientists to help prepare for the future, whatever it brings.

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