John Harrison
BOB DOUGHTY: While scientists were studying the stars and moon to solve the longitude problem, a man named John Harrison was working on another project. He was trying to build a clock that would help sailors learn longitude.
His task also was difficult and complex. Mister Harrison had to develop a clock that was not affected by the movement of a ship on the ocean or changes in temperature or atmospheric pressure.
He began developing his clock in seventeen thirty. It took five years to complete. The complex device weighed thirty-four kilograms. Several years later, Mister Harrison built a second clock. It was smaller, but weighed more than the first. Mister Harrison was not satisfied and began working on yet another device.
Twenty years later, he completed a device that was smaller than the first two, and weighed less. But still Mister Harrison was not satisfied.
Two years later, in seventeen fifty-seven, he produced a small clock that he could hold in his hand. The clock could tell the correct time in two places, meeting the requirements for learning longitude on the sea.
STEVE EMBER: For many years after Mister Harrison's work was completed, the idea of using a clock to learn longitude was rejected. However, that opinion changed when manufacturers learned how to make better and less costly versions of Mister Harrison's clocks. The clocks became known as chronometers.
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2013-11-25
2013-11-25
2013-11-25
2013-11-25
2013-11-25
2013-11-25