more armchair navigation

[Phil Allen]

I read a really great book over the holidays " Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time" by Dava Sobel. Covers the history and sociology of the quest to find one's longitude at sea. It's not a new book (2007) but I found it quite enjoyable.

best

Phil

[rick stoehrer]

and after all that Harrison had to chase down the prize money...good book!

[leong]

and after all that Harrison had to chase down the prize money...good book!

Unfortunately, I think it’s quite common for scientists to be jealous of another’s accomplishment. Even more so when it’s from one in another field or, heavens forbid an amateur. So the astronomers of Harrison’s day couldn’t conceive of a solution to longitude measurement coming from a lowly clock maker and not a solution using celestial measurements.

By analogy, in the early 1900’s radio scientists theories were that the only really useful frequencies for long-range communication were the very low frequencies (long wave frequencies). “---when the first government regulations were imposed on radio in 1912, the amateur operators ("hams"), whose interest in radio was personal and experimental, rather than commercial, got the short end of the stick., or the very long wavelengths.” Nevertheless, within several years the hams were regularly using short wave lengths for transatlantic communications. The practical results were different than the theory.

This reminds me of a quote that goes something like this “In theory it works perfectly; in practice it doesn’t work”. Perhaps for the two cases above the converse is more appropriate; i.e. In practice it works; in theory it doesn’t work.

-Leon

[rick stoehrer]

regarding Harrison and his clocks - sure wouldn't mind seeing one of them one of these days but don't know how she feels about geeking out THAT much while on vacation....tough sell.

http://www.rmg.co.uk/harrison

[bob budd]

Similarly Hedy Lamarr was denied most (scientific) recognition due until Blazing Saddles was released. Her invention dealt with anti-jamming techniques for torpedos.

[JohnHuth]

Actually, Dava did something of a disservice to the astronomers in Longitude.

The idea of using a clock for measuring longitude was first suggested by Gemma Frisius in the 16th century. He would certainly be called a scientist, I think. The idea was later picked up by Christiaan Huygens, who we could definitely call an astronomer. He developed the grandfather clock, which is quite accurate. The problem is that it could be used on shipboard, because of the jolts and accelerations - in addition to heating issues.

Harrison solved the problems of acceleration and heating issues with some novel concepts, like two weights on springs that swung back and forth - but these, in part, were inspired by Huygens earlier work.

Now, on the flip side of the coin, astronomers had another interest in the moon. It was the so-called "three body problem". Although Newton's laws accounted for universal gravity, the actual calculation of the lunar orbit was a real nightmare, as the motions of the earth, sun, and moon all come into play. It took many years until the proper mathematical treatment, called perturbation theory, was advanced enough to calculate the lunar orbit.

In fact, the so-called lunar method also worked for finding longitude once the orbit was properly described. The calculations as developed by Nevil Maskelyne were kind of clunky, so it took Salem's own Nathaniel Bowditch to simplify them so that people on ship-board could use them.

Early on, chronometers were incredibly expensive and out of the price range for normal merchant vessels, so the American whaling fleets employed lunar sightings to find longitude well until about 1850 and even beyond that.

James Cook, Lewis and Clark, and many other explorers used the lunar method, not chronometers for longitude.

Ultimately the price did come down for nautical chronometers to be used widely, but that wasn't until about 1850 or 1860

[leong]

This thread is the only place I typed “Longitude” in many years. So I don't think it was a coincidence that I just received an email from Amazon suggesting Sobel's book "Longitude". Perhaps more to worry about than NSA’s meta-data.

PS

Dear Amazon,

If you are still following this thread I’d appreciate some inside info on your stock. Please!

-Leon

[djlewis]

This reminds me of a quote that goes something like this “In theory it works perfectly; in practice it doesn’t work”. Perhaps for the two cases above the converse is more appropriate; i.e. In practice it works; in theory it doesn’t work.

-Leon

The way I've heard that is -- In theory, there is no difference between theory and practice; in practice there is

Attributed variously to Yogi Berra and Albert Einstein. But in practice it was Fielding Mellish.