A story of mechanical genius that may be unequaled
Oct 30, 2007
The last years of the seventeenth century and the first years of the eighteenth century saw the rise of significant global commerce. With few land routes and none capable of handling large amounts of cargo, the only option for shipping was via the oceans. As long as the ships stayed within sight of land, they generally knew where they were. However, that had its' dangers as it was always possible that a storm would dash the ship onto the land. Furthermore, many of the new voyages required movement across vast areas of ocean, and to do so safely it is necessary to have an accurate way to determine the location of the ship. Fixing the latitude was easy, as long as the position of the sun could be determined; it was possible to determine the latitude. Therefore, only the most overcast of days prevented the navigators from computing the latitude. However, fixing the longitude was much more complex and several ways were put forward. All involved some form of timekeeping, if you knew your local time and the time at a fixed point or longitude zero, the difference could be used to fix the longitude. Determining the local time was again easy and also involved determining the current position of the sun. Unfortunately, keeping the time of longitude zero was very difficult. All of the timepieces of the era were inherently inaccurate and grew even more so when they were jostled about by the rolling of a ship. Since being off by even a few minutes could be critical, it was necessary to have a clock that was sturdy and accurate. The problem was considered so significant that in 1714 the English Parliament offered an enormous reward for a solution. John Harrison believed that a solution was possible and after years of effort, he developed one. In the process he solved some very complex mechanical problems. Due to the wide range of temperatures that the clock would be exposed to, the expansion and shrinking of metals would cause the clock to vary. His solution was to put two different metals together so that the changes would offset each other. This strategy is the basis of the modern thermostat. A second problem was one of lubrication. If the moving parts were not lubricated, the friction would cause wear that would lead to imprecision. If a lubricant were used, the changing temperatures would lead to a change in viscosity and also lead to imprecision. His solution was to use a wood that secreted a lubricant and his end result was a clock that was extremely accurate and very sturdy. This is a fascinating story of mechanical genius that has probably never been equaled. Harrison's clocks kept a time so accurate that it was not superseded for centuries. It is a demonstration that humans are so intelligent and resourceful that when a major problem exists that must be solved, a solution will be found. That is a comforting thought as the human race continues to face increasingly greater and more complex environmental problems.
Dava Sobel, like Simon Winchester or Canada's Pierre Berton, has clearly mastered the art of writing history in a form that is not only informative but, perhaps more important, is also compelling and entertaining. In eighteenth century Europe, although scientists had long wrestled with the problem, sailors had no method of determining their longitude. The economic losses and the loss of life was so staggering that finding a solution to the problem was elevated to the … more
The work describes historical attempts to determine the exact position of objects at sea. The author describes the solar and lunar eclipse. Werner used the moon as a location finder. Galileo designed a navigation helmut-the celatone. Harrison constructed a table of the sun rising and setting. Nevil mas Kelyne published a Nautical Almanac which depicted lunar/solar-stellar distances. This book is perfect for science buffs … more
Charlie Ashbacher is a compulsive reader and writer about many subjects. His prime areas of expertise are in mathematics and computers where he has taught every course in the mathematics and computer … more
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The thorniest scientific problem of the eighteenth century was how to determine longitude. Many thousands of lives had been lost at sea over the centuries due to the inability to determine an east-west position. This is the engrossing story of the clockmaker, John "Longitude" Harrison, who solved the problem that Newton and Galileo had failed to conquer, yet claimed only half the promised rich reward.--This text refers to theHardcoveredition.