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John Harrison: Inventor and Longitude Hero
szczys writes: Here's an interesting fact: when at sea you can't establish your longitude without a reliable clock. You can figure out latitude with a sextant, but not longitude. Early clocks used pendulums that don't work on a rocking boat. So in the 1700s the British government offered up £20,000 for a reliable clock that would work at sea. John Harrison designed a really accurate ocean-worthy clock after 31 years of effort and was snubbed for the prize which would be £2.8 Million at today's value. After fighting for the payout for another 36 years he did finally get it at the ripe old age of 80. The methods he used to build this maritime chronometer were core to every wrist and pocket watch through the first third of the 20th Century. One of his timepieces, designated Clock B, was declared by Guinness to be the world's most accurate mechanical clock with a pendulum swinging in free air' more than 250 years after it was designed.
sure I do! and the first!
Please, read Dava Sobel's book, Longitude, about the trials and travails of Harrison -- it's a tremendous read. And if you ever get to the Royal Observatory in Greenwich (England), look at the Harrison models, they are amazing.
This is a guy who was a Maker -- self taught and more.
And it wasn't a bomb?
Here's an interesting fact: when at sea you can't establish your longitude without a reliable clock.
Not true. You can use GPS.
The article doesn't specify if modern machining and materials were used in the construction of Clock B.
If the clock could be produced using 1700's machining and metallurgical technology, only then would it prove Harrison's contemporary critics incorrect.
If the clock was impossible to build to that level of accuracy using 1700's technology, then Harrison's critics were indeed correct in calling him out.
Play it nice and cool, son.
You do not need a clock to determine longitude. In fact, a sextant can be used, as long as you have the appropriate tables that map various celestial angles to the correct date and time. These tables were originally overseen by Nevil Maskelyne, one of Harrison's rivals to the longitude prize. The two methods are an early instance of the closed-tech vs open-tech argument we're so used to now. Maskelyne argued that mariners should not depend on Harrison's (closed) bespoke clocks. Instead, he said that open information (the Royal Observatory's tables) should be used with open tech (the sextant) to solve the problem. But Harrison's clocks were so easy to use that his solution won the prize. Sound familiar? Do read Dava Sobel's excellent book on the subject; it's excellent.
I'll bet he could have designed it in an hour if he had a good 3D Printer and access to a Maker Faire. And he could have done a TED talk about it afterwards.
Yes, amazing story, invention, and ........ ...written about. At length. Recently. Best seller in the field [loosely defined as good authors writing about interesting subjects, though perhaps not of mass appeal].
Preemptively, may I recommend:
http://www.amazon.co.uk/Feynman-Lectures-Physics-boxed-set/dp/0465023827/ref=sr_1_6?ie=UTF8&qid=1443491481&sr=8-6&keywords=richard+feynman
http://www.amazon.co.uk/Fermats-Last-Theorem-Simon-Singh-ebook/dp/B009UKUGXC/ref=sr_1_2?ie=UTF8&qid=1443491379&sr=8-2&keywords=enigma+singh
http://www.amazon.co.uk/Seven-Daughters-Eve-Bryan-Sykes/dp/0552152188/ref=sr_1_1?ie=UTF8&qid=1443491415&sr=8-1&keywords=seven+sisters+of+eve
http://www.amazon.co.uk/Colossus-secrets-Bletchley-code-breaking-computers/dp/0199578141/ref=sr_1_6?ie=UTF8&qid=1443491379&sr=8-6&keywords=enigma+singh
Et cetera.
If the clock could be produced using 1700's machining and metallurgical technology, only then would it prove Harrison's contemporary critics incorrect.
Harrison built his clocks in the 1700's (although apparently Slashdot only just heard about it). They were incredible machines for their time and, after much wrangling with the astronomers of the time (who thought that schemes like making detailed observations of the moons of Jupiter through a telescope on the heaving deck of a ship in the mid-atlantic were better ideas) he won 1700's X-prize equivalent for inventing a machine to accurately measure longitude. You can actually see the clocks he made in the old Royal Greenwich Observatory building in London.
"when at sea you can't establish your longitude without a reliable clock"
But you could on land?
Imagine if you were in the middle of the prairie in the early 1800's - is it any easier to find your location than at sea.
You do not need a clock to determine longitude.
Yes you do. Maskelyne's method just uses the moon as a clock and required being able to accurately measure the angular separation between the moon and a bright star near its path to determine the time. Since the moon moves ~0.5 degrees every hour you need to measure the angle to at least this accuracy to get a time. While it worked it required great care measuring the angles, complex tables to convert the angle to a time and a clear view of the night sky. Even with all this extra effort on the one voyage where they were compared directly this method produced an error three times greater than Harrison's clock.
I would also disagree with your open tech argument. Have a look at the 1775 Nautical Almanac. Apart from copyright on the tables you had to have a government license to print them and the calculations on which the tables are based are not given anywhere (although there is some reassurance that the calculations have been checked multiple times). Worse this is a something you had to purchase every year. I don't see how this is any more open than Harrison's clock whose mechanism you could examine and tweak if you though you could do better.
Why is this a Slashdot article, today? Yes, it was interesting when the book was released, and when the documentaries aired, but if Slashdot ran an article each time a reader rediscovered history....
You use the sextant to measure the position of the moon relative to stars, which tells you the time, Computationally complex, back in Isaac Newton's time, not so hard today.
A few years ago I measured my longitude myself, just for fun. I measured the time of local noon, using a portable shortwave radio tuned to WWV. Correct local solar time to mean time with the equation of time, read off my longitude. I would have won the prize. Shows what an accurate clock can do.
I've read Captain Cook's logs and in his time they observed things like the moons of Jupiter to get a time reference. Reasonably accurate, but time-consuming.
...laura
The Jeremy Irons movie is great and its on YouTube.
Seastead this.
It was far too expensive to practically manufacture in the day. The prize authors should have included a clause to limit the manufacturing expense, but they didn't think of it at the time, and were surprised. But, it was not an open society, and monarchies can change the rules on a whim.
Table-ized A.I.
Thanks for the history lesson
... His name is Khan.
and knew his longitude, but it is apparently hard to do and few people were good at it.
There are lots of very nice books, documentaries and even movies, on this subject.
This blurb is a little off. The challenge from the British Government was to solve the longitude problem, not "build a clock". Harrison decided to build a clock to do it which likely played a part in the prize being held from him for so long as the board was chock full of nasty astronomers. We all know astronomers are hateful and spiteful and sad on the inside.
If this were invented TODAY, and he got a patent on it, how much money would that be worth? If he had gotten a patent on it THEN, how much money could he have made from licensing the patent?
Building a mechanical clock is about the most difficult thing I've ever tried to do (I've worked in laser labs, built an electric car, etc.etc). Never mind one that is accurate to within 2 second in 60 days (Harrison's H4 to Jamaica). Anyone interested? Give it a try: http://www.projectclock.org.
By facts from real security pros instead of a NOOB ROOKIE like him http://slashdot.org/comments.p...
Several of Harrison's clocks are on display at Greenwich Observatory in London. The more interesting ones to see are the larger ones because the mechanism can be determined. Amazingly the larger clocks are accurate despite being made largely out of WOOD. As well as the rolling of the ship not affecting the mechanism, temperature and humidity are compensated for. Often friction and wear and the need for lubrication are avoided by axles rolling back and forth rather then revolving in a bearing. Dana Sobel's book popularised the prize, the man and the clocks but I think she does not convey properly the engineering achievement. The clocks must be seen.
Paul Beardsell