Longitude

[mildred_of_midgard]

Finally having a chance to read again, I read a book called Longitude, about the problem of figuring out your longitude at sea. It's more interesting than it sounds!

Caveats first: even a few pages into the Kindle sample, I started getting suspicious about how hard the author was taking her protagonist's side and ragging on his opponents. Then shortly after buying the book and reading a little further, I hit two "Really?" anecdotes, to which Wikipedia promptly said, "No, not really." Both were described as local legends that were first recorded much later, and were contradicted by documentary evidence.

So how much of this I should be believing, I don't know. But the book was a very readable piece of popular science history, and I definitely learned a lot.

On to the book!


Finding your location at sea is a super important problem, for the following important reasons, among others:
1. Finding land and not dying of scurvy.
2. Not having to adhere to the same handful of well-known shipping lanes as all the other countries and getting ambushed and raided by them.
3. Not suddenly getting run aground and dying in shipwreck because you had no idea you were this close to land.

Re 3, I didn't realize just how bad it was before reading this book, but in 1707, during the War of the Spanish Succession, 4 English warships returning to England crashed into the Isles of Scilly, because the crew didn't know how close they were to England, and sank. The death toll was somewhere between 1,400 and 2,000 sailors. (This is where two local legends arose that apparently have no bearing in reality, which is too bad, because they're really good stories.)

This was a really, really bad experience, obviously, and it led directly to the Longitude Act of 1714 (i.e. as soon as the war was over). Parliament offered 20,000 pounds to anyone who could solve the problem of determining longitude at sea.

The problem with determining longitude is that the earth rotates, so the stars keep moving in the sky (or appearing to). So their position changes with time. The North Star makes latitude easy, but for longitude, you have to know exactly what time it is where you are and exactly what time it is in some position of known longitude (like London).

This sounds easy to us, but in the 18th century, determining exactly what time it was was a really, really hard problem. Because of friction, clocks lost time and had to be rewound. While they were rewound, they didn't measure time, so they had to be set with reference to some other clock. Pendulums in pendulum clocks were made out of materials that would shrink in the cold and expand in the heat, so they would swing faster or slower. Finally, at sea, with all the tossing and turning due to the winds and waves, it was insanely hard to keep a clock from getting thrown out of sync by all the agitation.

So this problem of knowing what time it is, and therefore where you are, was an extremely unsolved problem in those days.

The author presents one hilarious method that was suggested in 1688, which she can't tell whether it's satire or not, but having read the original pamphlet as well as Wikipedia, I am extremely convinced is satire. The idea was that there was this thing in medical quackery called "sympathy powder," which worked kind of like voodoo dolls. You would take a wounded dog and create sympathy powder on port. Then the dog would go on board the ship, and the sympathy powder would stay behind. By doing the equivalent of voodoo back at home at regular intervals with the sympathy powder, you would make the dog on the ship yelp in pain. Then, two or three months later, the sailors would know what time it was back home by when the dog on the ship barked.

SATIRE.

Anyway, because of the economic and military payoffs, both governments and leading scientists took a huge interest in the subject. The book is full of names like Galileo, Newton, Hooke, Halley, Louis XIV, and George III.

Now, there were two main schools of thought for how to tackle this problem. One was the celestial measurement approach, and one was the timekeeping approach. According to the celestial measurement approach, you needed astronomers to plot the motions of some body or bodies in the sky, determine what was predictable over time, make up tables containing the data, give the tables in the form of an almanac to the sailors, have the sailors take measurements at sea, and then have them consult the books.

Galileo came up with a very good method for doing this, but unfortunately, it only really worked on land, under ideal conditions. It led to huge improvements in mapmaking! This is when people finally realized that 1) the Atlantic Ocean was a whole lot wider than they'd thought, 2) certain countries were not as big as thought. Allegedly, Louis XIV quipped that he was losing more of his territory to the astronomers than to his enemies. But he did keep funding them.

That's the astronomy approach. It was worked on by royal societies and observatories and funded by monarchs and parliaments.

Then there was the timekeeper approach, according to which all you had to have was a device that told the time and didn't gain or lose more than 3 seconds a day. You'd set it before you sailed from port, you'd take the local time using astronomical measurements, and you'd compare the time of your device (the time back in London or wherever) to local time (the time in the middle of the Pacific or wherever), and knowing the difference in times and the longitude of London, you could solve easily for the longitude of your current location.

This was worked on by one probably autistic Englishman of humble origins who decided to devote his life to tinkering with making clocks better. He first got assistance from his brother, and then his son. His name was John Harrison. [To quote the author, His family, in keeping with the custom of the time, dealt out names so parsimoniously that it is impossible to keep track of all the Henrys, Johns, and Elizabeths without pencil and paper. To wit, John Harrison served as the son, grandson, brother, and uncle of one Henry Harrison or another, while his mother, his sister, both his wives, his only daughter, and two of his three daughters-in-law all answered to the name Elizabeth.]

By 1730, he was introducing himself to Edmund Halley and presenting him with the drawings for the sea clock he had in mind. Halley sent him to a clockmaker friend, who gave him a loan to work on the clock.

In 1735, Harrison got to do a trial run with his clock. The admiralty decided to send it to Lisbon with Admiral Norris in 1736.

Now, if you're me, the words "Lisbon with Admiral Norris in 1736" is a magic phrase that means "Peter Keith." Given Peter's already demonstrated scientific interests in the early 1730s, and his later honorary Academy of Sciences membership, I was super hoping they were on the same ship! But alas, Peter (according to his eulogy) was on the flagship Britannia, which sailed in May, and Harrison was on the Centurion, which joined the main fleet in Lisbon in late September. But Harrison and Peter were in Lisbon at the same time as part of the same fleet, and they could have met there.

I also learned, while doing a bit of detective work, that the Englishmen who arrived in Lisbon in the second half of 1736 got so sick and so many of them died, due to a combination of an outbreak of smallpox and dysentery due possibly to local food that the English hadn't adjusted to, that Norris requested permission to sail home asap, and when he couldn't get it, demanded and received a hospital ship. 1 in 6 of the 12,000 men were recorded as sick. (Look, I just want to know every single detail I can reconstruct about the elusive Peter's life, it's my detective case.)

Anyway, back home in 1737, Harrison was presenting the results to the Board of Longitude (no, really, it was called that). His device had barely lost any time on the trial runs to and from Lisbon.

Everyone was super impressed! England was going to get a huge advantage over her enemies if this worked out! This was the time to demand the trial voyage to the West Indies required by the 1714 act as a prerequisite for the £20,000 prize.

But instead of advertising how great his invention was, Harrison proved himself a true engineer by pointing out its defects and talking about how he knew he could make a better one, and make it smaller, if they just gave him £500 and some more time to work on it. Once it was up to his standards, he'd submit it for a trial run, but not now. (I laughed so hard in recognition and knew I immediately had to share with cahn. Engineer mentality at its finest!)

"Uh, okay. Works for us," said the board that didn't have to pay £20,000.

Then Harrison disappeared for 20 years to work nonstop on 3 more iterations of his clock, which he eventually got down to a watch. A largish watch, but still a watch. He sacrificed his health and his work-life balance to this obsession.

Unfortunately, this dedication to his craft proves to be a political error, because in the meantime, his open-minded buddy Halley dies and is replaced as Astronomer Royal by a succession of astronomers who believe that astronomy is the One True Way for solving the longitude problem, and who are out to persecute poor lone genius John Harrison.

This is where the narrative becomes incredibly one-sided and I'm not sure we have the full story. But there seems to have been a rivalry between the astronomers and Harrison once he was ready to claim his prize. Eventually, George III, the noble, scientifically minded king takes the part of Our Hero and all is right with the world. Harrison doesn't get the prize because of politicking, but he gets an equivalent amount of money from Parliament by taking George's advice on presenting himself favorably during the trial. (Spends 20 years of his life tinkering with clocks and only emerging from his workshop to ask for a little more money to kepe working, talks shop for 10 solid hours with another clockmaker, is described as stubborn and argumentative, can't write readable prose to save his life, apparently has limited people skills...sounds spectrumish to me, based on what little data I have.)

Euler gets a cameo in the book for winning a prize for his role in furthering the cause, by reducing certain celestial motions to elegant equations and corresponding with an English astronomer who was able to apply those equations to the longitude problem.

In the end, the longitude problem seems to have been solved by a combination of astronomical (though you have to read between the lines and recall some other history you have read to get that from this rather biased-seeming book) and mechanical advances. But the ability to make a clock that does lose several minutes a day was a huge win for many other reasons, and led directly to the mass-production of pocket watches and wrist-watches that were actually reliable.

One thing that Harrison apparently invented that I had actually heard of was the bimetallic strip, which is used in thermostats even today (the context in which I learned about it in physics class). Since metals expand and contract at different rates at different temperatures, you can get something that will keep the temperature from getting too hot or too cold by combining two metals together in a strip, which will keep the temperature within a certain range by flexing in one direction or the other, depending on which of its two metals is reacting to it being too hot or too cold.

Harrison invented this to compensate for the fact that all previous timekeeping devices lost or gained time depending on the temperature. He used a combination of metals in first rods--in his first, large clocks--and then a bimetallic strip in his smaller, more sophisticated watches.

So that was cool.

The devices he built are called the H1, H2, H3, and H4 ('H' for 'Harrison'), and you can view them today (or some post-pandemic utopian future) at the National Maritime Museum, and online in the meantime. The H1, the original giant clock that went to Lisbon.

The H2, the improved version.

The H3, the one that took 20 years of his and then his son's life.

The H4, the one where he went from "This can never be made watch-sized" to "Oh, wait, it can!" because someone made him a really good watch for his personal use, incorporating many of his inventions (including the bimetallic strip), and that made him go "Hmmm."


selenak: Hang on, wasn't there a tv two parter with Michael Gambon as Harrison and Jeremy Irons as a 20th century creature rediscovering him, based on this book? I haven't watched it, but it got recced to me a couple of times.

Mind you, checking out wiki, it also seems to think G3 saved the day for Harrison. And while he was still compos mentis, he was interested in the sciences and very supportive. (One of many reasons why the decadent King Britpop version of him in Hamilton cracks me up was that of all the Hannovers, G3 was the least like that for sure. (Not even when mad.) I mean, this is "Farmer George" we're talking about, he who was way more into gardening and the natural sciences than partying and was the most bourgois of monarchs this side of FW in that century.

Greenwich and the Royal Observatory (and the Maritime Museum), btw, is very worth a visit, if you two haven't been there in ye olde days when it was still possible to travel. You can take the subway, but I went per boat in 2016, which a fabulous ride where you see lots of London from the Thames.

Alas I don't recall the Harrison clockworks, which look gorgeous in the pics you linked, but I did take photos of the Royal Observatory, the Cutty Sark and the Navy Museum (located in the former palace; the fact that they have the Armada portrait there reminds me Elizabeth I was actually born at Greenwich, though only a tiny part of the old structure survives):

Selena's amaaaazing pictures.

mildred_of_midgard: Mind you, checking out wiki, it also seems to think G3 saved the day for Harrison. And while he was still compos mentis, he was interested in the sciences and very supportive.

Oh, sure, the factual aspect of G3 saving Harrison is not the part I'm questioning! That seems well enough documented. It's the fairy-tale vibe of good triumphing over evil and the monarch as a symbol of good that I'm side-eyeing. Maybe it was that one-sided! But I feel like a book written from the perspective of the astronomers miiiight have more to say about their contributions and not just how they persecuted poor Harrison.

cahn: Oh, thank you for reading this and summarizing it for us! I've seen this book around but never read it.

Hilariously, one of the reasons I never read it is because all I knew about the longitude problem I learned from Carry On, Mr. Bowditch which is a Newbery Award winner which is a fictionalization of the life of Nathaniel Bowditch, an American mathematician/navigator. I'd forgotten most of what I learned from it, but I did a bit of browsing and Bowditch's contributions were all in the "astronomy" way of doing things (since even after Harrison, chronometers were pretty expensive) -- he figured out a better way of taking/computing the lunar measurement needed to get Greenwich/London time, and even more importantly he redid all the computations of the mathematical tables that are needed to get the time from the astronomical measurement, because the tables had many errors in them. So basically this was a HUGE deal at the time, but isn't particularly today because once good timekeepers were a thing, no one really needed these huge tables anymore. (I actually bought a real biography of Bowditch a while back which I never got all the way through, but this might be a good impetus.) Anyway, I once picked up Longitude many years ago, and on seeing there was no Bowditch, put it back down and wandered away :P (Yes, indeed, all I know about history comes from historical fiction and SF/fantasy novels.)

Euler gets a cameo in the book for winning a prize for his role in furthering the cause, by reducing certain celestial motions to elegant equations and corresponding with an English astronomer who was able to apply those equations to the longitude problem.

This may be a different thing from what you're talking about, but when I was browsing today to remember about Bowditch, I found that Euler made the calculation of astronomical time (vs. chronograph time) possible by inventing Euler's method, which is basically a very simple way (at least, in these days of computers it's simple) to numerically approximate the solution to a differential equation (here, to predict the position of the moon for those lunar calculations, which is a complex earth-sun-moon three-body problem that one can't generally solve analytically). In the age of computers, this is basically Baby's First Numerical Method, but I'd never known the historical context behind why it was formulated in the first place!

mildred_of_midgard: Ha, so I had also read Carry On, Mr. Bowditch and was approaching this book with that as context. Which is one reason I'm side-eyeing the author's severe downplaying of the role of astronomical calculations after Harrison had solved the chronometer problem, because last I checked, both Bowditch and, a hundred years later, Worsley in 1917 in Antarctic waters, were doing the "taking sightings, looking up tables in a book, doing calculations" thing that she disparages. The book briefly mentions that astronomical measurements and calculations continued to be necessary, but wow is the treatment one-sided.

That said, because I knew a few things about the astronomical aspects of navigation, and none at all about the engineering problem of chronometers, this book was valuable for that. But I'm very glad I went in with even the little background I did!

Incidentally, her take is that astronomy had more prestige than engineering (legit), and the fact that the longitude problem was hard meant to some people that only a hard solution was acceptable, and so the fact that taking measurements on a ship that moves up and down, having to compensate for your own height plus that of anything you're standing on, looking things up, trying to keep the book dry, etc. were all really hard were a feature rather than a bug. She says that a century or so earlier and Harrison's devices, which incorporated all the calculations into the hardware and made working them out unnecessary (except for taking local time, which I feel like she also downplays), would have been witchcraft! Since it was the 18th century, he was just dismissed as "It couldn't possibly be that easy," and that was why people kept pursuing the astronomical approach.

All of this comes with a big "Maybe these were factors, but I wish I trusted the author more, because I feel like there was more to it." Since like you said,

(since even after Harrison, chronometers were pretty expensive)

Comments

[luzula]

Thanks for the write-up, this was interesting! : ) Although I wonder at that board sending him off to perfect his clock further--wouldn't they jump at the opportunity to improve navigation NOW?

Don't know if I've mentioned, but I'm a mathematician and teach some courses related to this stuff. I teach math to students who will become sea captains (they grumble and protest at having to learn spherical trigonometry, great circle calculations, etc, because in practice they're just going to plot their course using GPS and computer programs), and also an evening course on the history of navigation. That last one I teach together with an astronomer, and it's just eight lectures, so it necessarily just skims the surface. But it's a fascinating subject.

I do have a proper sextant (well, I loan it indefinitely...) and have tried using it on a boat--I ended up about 2.5 nautical miles from the true latitude when I took the height of the sun at noon, heh. It's not easy! I keep meaning to try the Marcq St Hilaire method to get both latitude and longitude, but I haven't yet.

[mildred_of_midgard]

Wow, that's really cool! I majored in math but know zero about sailing, navigation, boats, or sea captains. ;)

Although I wonder at that board sending him off to perfect his clock further--wouldn't they jump at the opportunity to improve navigation NOW?

If my understanding is correct, they did both. They kept the designs for version 1.0, which they put into use immediately, and then paid him to work on version 2.0. The key here is that they didn't have to pay him for version 1.0, which any normal person would have insisted on, but he was an engineer. ;)

[luzula]

Ha, well, there's plenty I don't know about those subjects as well. : )

Well, the board acted in self-interest, then...but Harrison seems to have needed someone to look out for his interests better!

[mildred_of_midgard]

Well, eventually he got George III, which is not bad!

[luzula]

Hee, very true!