Talk 327

In the 1600 and early 1700, no one knew how to determine the meridian of longitude at sea....

Many tried and failed including Newton, Hooke (the rubber band) , Halley (the Comet) and other very accomplished scientists. It was proclaimed to be unsolvable, until Harrison, a carpenter/mechanic, came along...

The current Lucasian professor of mathematics at Cambridge is Stephen Hawkins. Now, you see they had some equivalent or even more prominent scientists on the Board...

John Harrison, a self-taught person, was a carpenter and mechanic by trade. He decided to make a clock to keep time at sea accurate to within 3 seconds a day for at least 6 weeks. Harrison built his first clock in 1715, the year after the "longitude Act" passed. By 1727, he had made a fine clock with a specially designed pendulum to compensate the effect of temperature changes. It is widely referred to as the H1 ( Harrison 1).It was a large clock weighing about 35 Kg ( more than 70 lbs). H1 was put to test at sea, it behaved well and Harrison was able to tell the captain that the ship was 150km (more than 90 miles) off course. However, Harrison was not happy with his H1 and started building another clock, H2, and then H3, and H4.

By the time H4 was made, Harrison had truly become a master time piece maker. H4 was about 5 inches in diameter, and it was very much like a pocket watch as we know them in present day. The only exception was that H4 was a hell of a lot more accurate then most of the modern mechanical watches. In fact H4 was accurate to 5 seconds in 5 months of sea journey ( accurate to about 0.02 degree in longitude) . It had far exceeded the the requirement of being accurate to 0.5 degree in longitude in 6 weeks of journey.

Harrison had no formal academic training. This lack of formal
education did not sit well with the Board of Longitude. The board was very reluctant to announce Harrison the winner, and unwilling to award him with the prize. Finally at age 81, Harrison received his award after the personal intervention of King George III, but he had only 2 years to enjoy his wealth. One of Harrison's invention, copied by watch makers all over the world, was the winding of a clock without stopping the clock.

I have two mechanical watches ( Omega Seamaster and Constellation), both more than 30 years old. I decided to do an experiment to see how accurate they were by comparing them with two quartz digital watches ( Casio and Seiko). Since quartz watches keep time by the frequency of the the quartz crystal ( 13.6 mhz), they should be much more accurate than mechanical watches. After 5 days, the two quartz digital watches were at about the same time, the Seamaster ( 1969 vintage) was about 5 seconds faster everyday, the Constellation ( much older than the Seamaster) was really off. According to a colleague of mine, who was very much into mechanical watches, both watches should be accurate to 0.1 second a day. If these watches were cleaned and re-calibrated by a master watch maker, they can perform more accurately. These two watches do not come close to the H4 as they are, even though they look very nice.

After 3 weeks, the two quartz digital watches began to show
discrepancy; one was 2 seconds faster than the other. I do not know which one was right, since I did not set them according to the atomic clock (good to 1 second in 300,000 years) located at Colorado (http://www.time.gov/timezone.cgi?Pacific/d/-8/java) when the experiment began. I suppose I could do a better experiment, but the point is that quartz watches are no matches for H4 either.

I was in my colleague's new car the other day. His car has this GPS system and it is tough to get lost with this on-board system. He keyed in the address we wanted to go, and the GPS took over, telling him to turn 10 feet in advance and so on. My colleague told me this satellite based guidance system has a resolution of 2 feet. Well, in this case, even Harrison could not have matched that kind of accuracy. Progress in Science and technology always wins in the end.