How Wristwatches Defy Gravity
Unique watches are manufactured by every watchmaker. But one of the single most interesting and unique things about watches is their ability to defy gravity. Even centuries ago, watchmakers realized they had to find a way for watches to overcome Newton’s forces. This was especially true of pocket watches because they remain relatively stable, in a vertical position. Gravity has its way with stable things, gently pulling at them. It results in tiny changes with the accuracy of the watch.
How it all began
You might not be bothered by the small inaccuracies but back in the 18th century sailors’ lives depended on the marine chronometer and the deck watch. Before that, they constantly risked their lives. A Board of Longitude offered a £20,000 prize to entice inventors to solve the longitude problem. This was big big money back in that day! This quest became known as “finding the longitude.” It was believed by many that this was an unsolvable problem. It was seen as a pursuit for lunatics and fools.
A working class joiner with very little formal education, John Harrison, took on the academic and scientific establishment in an attempt to find the longitude. His inventions could probably be described as some of the most unusual watches of all time. Harrison showed a great deal of fortitude, mechanical insight, innate talent and enormous determination.
After building several wooden long-case clocks, Harrison worked with his younger brother James, on making a clock that needed no lubrication. It was a revolutionary idea. Clocks of the 18th century had bad oil used in them and this was a major cause of failure. This kind of radical thinking would serve him well when he took on the problem of a marine timekeeping device. He would ultimately invent a marine chronometer.
Working together through the 1720s, the brothers invented a number of remarkably precise long-case clocks. They invented a pendulum rod made of brass and steel wires that eliminated the problem in warm weather, when the pendulum increased ever so slightly in length, slowing the clock. The Harrisons’ rods had an accuracy of loosing only one second per month.
Between 1730 and 1735, the Harrisons worked on “H1″, a portable version of their earlier precise wooden clocks. It was spring-driven and ran only for one day. (Their wooden clocks could run for eight days). All the moving parts where counterbalanced and controlled by springs, making them independent of gravity.
For the next several years Harrison worked on H2, which was heavier and larger than H1 but essentially the same design. He soon realized that the design was wrong. The problem was in the bar balance. It did not properly counter the ship’s movement. He felt the problem could be corrected if the balance was circular. He needed more money to keep going so he asked the Board of Longitude for more money. He worked on this idea for nineteen years but in the end, his timekeeping piece did not meet the accuracy the Board required.
He next worked on H3, a device that incorporated two of his earlier inventions: the bi-metallic strip that compensated the balance spring during changes in temperature and a caged roller bearing that was an anti-friction device. After all these years, these inventions are still used in a range of machines.
Despite these innovations, work on H3 seemed to lead nowhere and its ultimate role was to convince Harrison that the solution to the longitude problem lay in an entirely different design. Harrison was relentless and in 1753, he asked the watchmaker, John Jefferys to make him a watch using his own specifications. No one at this time gave the pocket watch serious consideration. Harrison, however, realized that his new watch, with a few tweaks, could become an excellent timekeeper. This was the precursor to today’s mechanical watches. Harrison made the following petition to the Board:
He wanted to make two watches, one of such size as may be worn in the pocket & the other bigger… having good reason to think from the performance of one already executed… that such small machines may be rendered capable of being of great service with respect to the Longitude at Sea…
This gave birth to H4. It was very much like a large pocket watch. Harrison gave it to his son for a journey to Jamaica. The watch had kept remarkable time, loosing only 5.1 seconds in the 2-month trip. It still wasn’t enough to please the Board and have the prize awarded to Harrison. H4 made a second voyage to Madeira and this time it predicted the ship’s arrival with exceptional accuracy. It was three times better than the accuracy needed to win the £20,000 prize. The Board said the watch was nothing more than a fluke! They required him to reproduce the watch or hand over his secrets to the Astronomer Royal. Harrison would be given £10,000 if other wrist watches could be made that kept the same accuracy.
The Board would not award Harrison his full prize. He made another watch, the H5. It was actually put on trial by the King in 1772 with superb results. In June 1773, Act of Parliament finally awarded the Harrison brothers £8750. John Harrison had finally been recognized for having solved the longitude problem. His marine chronometer was a precise timekeeper used as a time standard that was portable. It was able to determine longitude through celestial navigation. Marine chronometers were considered very high tech in their day. It took John Harrison 31 years or persistence, a lifetime of trial and error but in the end, the marine chronometer completely revolutionized naval navigation.
A little over a hundred years later, in 1895, the fine Swiss watchmaker Abraham-Louis Breguet came up with the idea of a tourbillon. This was a rotating cage that kept the inner movements of the watch balanced so that gravity’s pull would not affect it. The word “tourbillon” means “whirlwind,” and it is a reference to the motion of the device inside the watch. Watchmakers quickly caught on to the introduction, and tourbillons became a must-have for anyone who wanted an accurate watch. While not used today, they still stand as an exquisite example of the fine watch making craftsmanship developed over centuries.
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