![]() He built a clock and then a watch that could keep time at sea, and Dava Sobel, a science writer, tells his story with grace, clarity and affection.Īctually, as Sobel tells us, Harrison devoted his life to the problem and built several sea-going clocks over a period of decades. ![]() Isaac Newton himself wrote: “By reason of the motion of the Ship, the Variation of Heat and Cold, Wet and Dry, and the Difference of Gravity in different Latitudes, such a watch hath not yet been made.”Įnter John Harrison of Yorkshire. in London, the two-hour difference meant you were 30 degrees west.īut in the era of pendulum clocks, no timepiece was reliable at sea. Thus, if it was noon where you were when the clock said it was 2 p.m. Since one hour equals 15 degrees of longitude (360 degrees divided by 24 hours), the difference in time would tell you where you were. Then you could observe local noon wherever you were by the sun and compare it to what time it was at that moment in London. Many years of work went into this approach.Ī completely different approach was to have a clock aboard the ship that would tell what time it was where you started-in, say, London. The longitude problem, as it was called, was so important that in 1714, the British Parliament offered a prize of 20,000 pounds-equivalent to millions today-to anyone who could solve it.įor several centuries, astronomers and mathematicians thought that the answer to the question could be found in observing the heavens. ![]()
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