ASTRONOMY IS NOT SOMETHING I'M INTERESTED IN BUT I READ THE GLASS UNIVERSE ANOTHER NON-FICTION BY SOBEL AND ENJOYED IT SO I GAVE THIS A TRY. IT WAS INTERSTING HOW THE MAN WHO SOLVED THE GREATEST PROBLEM WENT THRU SO MANY TRIALS TO GET HIS RECOGNOTION, BUT THIS JUST WASN'T FOR ME.

A real gem of a book. I have spent a bit of time sitting in a sailboat dreaming of going places (instead of bobbing around the glorified bathtub we call the Chesapeake). I knew a bit about navigation but if you are starting from scratch, this is the book to read. Part science, part history, and part thriller (I may have stolen this bit from the book jacket or something, but it's true, damn it! And who are you? The plagiarism police?).

I learned several interesting facts in this book. Although an historical explanation of an important issue long since resolved, the author narrates the book in a very engaging manner.

I bought this book recently on e-bay. It is one I have wanted for quite a while, but there is a book-buying ban in operation at my house, so I had to break cover and institute a moratorium on the ban in order to make a few semi-authorised purchases. It’s not that my wonderful wife doesn’t like books, she does, or the cost involved, although Folio Society volumes don’t come cheap; it’s more to do with the size of our house being inadequate for the number of bookcases I need to display them all. I am approaching 600 owned books, so this is a genuine challenge. Anyway, sorry to digress.

Longitude is a wonderful book, and a particularly easy read for what involves, fundamentally, science. It is the story of the search to find a reliable method to find one’s longitude at sea, something that had been perplexing some of mankind’s greatest brains for centuries. What’s the big deal? you may ask. The big deal is that if you don’t know where you are, you are likely to come a cropper (particularly, but not exclusively, in bad weather) and end up smashing your ship against rocks, islands, cliffs and other miscellaneous immoveable objects, resulting in your death. It also stands to reason that in the days when scurvy was a constant problem on board ship, causing hundreds/thousands of deaths, you needed to know when you would next arrive at a land mass or an island so that you could stock up on supplies and water. If you’re not sure whether the island you’re heading for is east or west of your current position, nor how far, you are likely to miss it, again with dire consequences. And many thousands of people did die because these things happened, as well as ships and cargoes lost at sea, and profits foregone. So the quest to find how to measure longitude accurately was a very big deal indeed.

This true story is primarily about Mr John Harrison, a country clockmaker from Lincolnshire, a rural county to this day, and the maritime clocks he spent almost his whole life inventing and developing, manufacturing them himself.

The British government had come under pressure to do something after a highly experienced and well-respected admiral of the Royal Navy had lost three ships and five hundred men in just such an accident as described above, so had put up a prize of £20,000 to the person who could solve the longitude problem. (Using one of the methods to calculate that in today’s money [purchasing power] yields a 2018 equivalent prize of £2.84m, which is about US$3.7m.)

Naturally, the prospect of becoming a millionaire and famous into the bargain stimulated many people to try to solve the problem, most failing completely and some coming up with crazy ideas, including ‘the wounded dog theory’ which was based on using ‘powder of sympathy’ (you’ll have to read the book!)

There were considered two possible methods for divining your longitude at sea:
1) The Lunar Method enabled you to navigate by the relative position of the moon to the sun (daytime) and certain fixed stars at night. This worked quite well as long as there was no or little cloud and good weather. More than one scientist (or natural philosopher, as they were called at that time) spent decades painstakingly tracking and measuring the moon’s relative position every three minutes and publishing tables from which you could calculate your distance from the place the measurements were taken from and arrive at your longitude. This method also required quite complex mathematics to work it all out, so it was not a simple solution;
2) If you knew the exact time in your home port (i.e. the port you departed from), and if you knew the exact time in your current location, you would know how long you had been sailing, and from this could calculate your longitude quite easily.

The main challenge to the second, more straightforward method, was that clocks in the 18th century were highly inaccurate, even the best available gaining or losing a minute a day. A clock or watch on a ship, however, would be even more inaccurate because it was tossed up and down on the waves and its metal components were subjected to extremes of temperature swings during a voyage – freezing cold in a European winter and broiling hot in the tropics. Expansion and contraction of the parts severely affected performance. Finding your exact time and the time elapsed since you left port was, therefore, almost impossible.

John Harrison was a highly skilled clockmaker who worked in isolation in rural Lincolnshire. He built up a local reputation as a reliable man who produced fine clocks that kept good time. He worked alone, although for a while he worked with his brother, James, and in later years he was helped by his son, also highly skilled, though not as good as the father. When he became aware of the prize on offer, Harrison decided he would produce a marine clock accurate enough to enable ships’ captains to know the time in their home port, thus providing the means for them to calculate their longitude. He invented and manufactured several new components that vastly increased the accuracy of clocks – to within a second or two a day, a tremendous improvement over what was available commercially. He built his first marine clock, known as H1, over five years.

He subsequently spent the next forty years building three more, all improved and with new components invented by him. One of these was the bi-metallic strip, a small strip comprising two metals bonded together longways – metals with different characteristics of reaction to heat and cold. If one half of the strip expanded, the other contracted, thus keeping it at a constant length. This made his clocks vastly more accurate. It is also a standard component in thermostats in all our houses and many household appliances.

Harrison had a hard time of it, mainly because the men judging the ‘competition’ were mostly astronomers wedded to the idea of the Lunar Method. Some of them also had a vested interest in using the stars to navigate by, i.e. selling the star charts and tables! Harrison was delayed, argued with, lied to and generally mucked about for decades and, unfortunately, he was his own worst enemy. Instead of hailing H1 as the solution when he demonstrated it to the Longitude Committee, he said yes, it’s good but I can do better, then went away and spent another five years inventing H2!

You’ll need to read this fascinating book for all the details, but the upshot of all this angst was that Harrison was a genius happiest when he was inventing and building his state-of-the-art clocks, which worked incredibly well. One wonders if he may have been somewhat ‘on the spectrum’, because not only was he highly focused and bright, but also very bad at expressing himself and explaining his clocks, both verbally and in writing. Either way, in the end, he got a lot of money, although not the full prize.

Ironically, the Lunar Method survived as the main way of calculating longitude at sea well into the 19th century, mainly because the accurate watches – chronometers – that Harrison invented were prohibitively expensive, making them unavailable to the majority of sea captains.

The book is very well written and Dava Sobel, who conducted extensive research to produce it, keeps you enthralled throughout. It is a fascinating story and one that needed to be told.
A solid five stars.

I read this in high school (so no detailed review) and remember enjoying it immensely.

Stellar nonfiction, exceptionally well-written.
Technical enough to satisfy those who want the details; lucid enough for the non-technical to comprehend the central problem and its attempted solutions; engaging enough to draw in all kinds of readers. This book could get practically anyone excited about applied science through real-world problem solving.

I am an Arts person, not a Science person, yet I find -Longitude- Readable Science History. Enjoyable.

When my dad went to college back in 1958, my grandma spent a small fortune to buy a 17-jewel (or was it 11?) Swiss wrist watch for him. That thing will probably be off only a couple of minutes a year. A few years back, I gave him a different watch, a solar-powered so-called atomic watch which is really a quartz watch that can synchronize to real atomic clocks through broadcast towers on three (or was it 4) continents. Adjusted for inflation, this second watch is probably cheaper. The rate of technological advancement is extraordinary over a long period of time because it's exponential. Backing off to the early part of the exponential function, you'd find glacier speeds of innovations (from today's perspective). But they are every bit as exciting and important. This book tells you the fascinating stories around the end of the 18th century when precision timekeeper was just about to be invented and chronometer was not a word yet. As they say, necessity is the mother of invention. The necessity this time was navigation -- or more specifically, longitudinal navigation.

Determining latitude at sea is relatively easily as the season changes rather slowly and thus the sun stays at stable azimuth at noon. But longitude is an entirely different thing. You need to keep time accurately. Your watch and clock do not tell current time in some magical way, they track cumulative passage of time. Therefore, any small error accumulated over a long voyage can be substantial. So much so, back then the Royal Navy essentially was rather clueless as to where they are (longitudinally) at any particular moment. Yet, uncertainty and ignorance undermine authority and are therefore not allowed to be displayed. Thus any personnel keeping his private navigation on board is capital offense! One such officer risked his life to tell his commanding officer that he thought they are in grave danger. He was hanged for mutiny. The rest of the ship drowned (with two exceptions and one of which is an admiral who despited being washed ashore alive, was later murdered for his beautiful emerald ring -- history makes stories that rival Dumas's).

That's how bad things were back then. And the great Newton himself told the parliament that it's a difficult problem and no easy path lay ahead. The parliament passed the longitude act and promised a prize ($5 million in today's currency) for the first person to tell longitude within half a degree. Then came the heroic effort of Harrison to make a series of time keepers to eventually beat the goal by a large margin. But there were so much drama and delay to his recognition. He eventually made an appeal to King George III. The much maligned king in Lin-Manuel Miranda's broadway hit "Hamilton" turns out to be a very reasonable and scientifically astute monarch. (King George, btw, is my favorite character in the musical. Now, I like him even more.) There are many interesting little stories like that throughout the compact little book. It's well worth a read.

For someone who has read many books about the “Age of Sail,” I was rather ignorant about the intricacies of navigation. I knew that sailors would take noon sightings to determine their position, but little else. I have seen the word chronometer, but not understand its definition or its significance. As a result, my interest was piqued by Dava Sobel’s book Longitude, which tells the story about the historical quest to determine accurate estimations of longitude.

Due to the orientation and spin of the Earth, determining one’s latitude and longitude require quite different approaches, with the latter being much more difficult to find than the former. The impossibility of ascertaining one’s longitude made navigation across open water a risky venture, and of course led to the loss of many ships and lives. Ultimately, it was an 18th century British clockmaker named John Harrison who solved the problem of longitude by making sea clocks that would keep time better than any clock before. These sea clocks became known as chronometers and by the early 19th century became a standard and essential device at sea.

Harrison’s story takes center stage in this book, but he was not the only one looking for solutions. Naturally, this pressing matter interested many of the great scientific minds of the day, particularly the astronomers. Accordingly, the author recounts how at the same time as Harrison was working on his clocks, a series of astronomers worked to catalogue the stars and the movements of the moon against them in search of an astronomical solution.

It is a fascinating story, especially for someone from the 21st century, where issues of navigation and timekeeping have been trivialized by satellite GPS and digital and atomic clocks. The human side of the story is made more complicated by the tensions between the two parties: the Harrisons and the astronomers.

Longitude is a good primer for what I have summarized above, but I wanted a lot more out of it. The book is very short at only 175 small pages of narrative, merely an unhurried afternoon’s read. There is practically no technical details about the chronometers themselves. Instead, most of the book is dedicated to the human and historical elements in this story. Sobel eschews a strictly chronological timeline in favor of one that jumps around, in order to play up the race between Harrison and the astronomers.

The narrative’s structure suffered as a result. For example, the lack of tension over Harrison’s actual creation of the chronometer—which is told early on—undercuts the storytelling aspect of the narrative. In addition, because of the nonlinear aspect, certain facts were repeated a few times, which is very noticeable in such a short book. Another irritation was when the author attempts to build drama over the need to find a solution to the longitude problem. The issue of scurvy on long sea voyages is explained in detail with multiple examples. Implicit is the the suggestion that being unable to determine longitude caused scurvy because sea voyages could be lengthened by the resultant poor navigation, which is an illogical argument.

I have a few other minor complaints. There are a few occasions where the author indulges in some speculation and dramatization—though thankfully not often enough to become truly distracting. It is also a shame that there are no illustrations, especially of the chronometers. Lastly, I would have liked there to be footnotes, though the author does explain that she chose not to include them since this is a popular, not an academic history.

That is the crux of it. I have to credit Dava Sobel with writing a good, non-technical introduction to a little-known but important bit of history. It is not her fault that I want to know a lot more about everything in the book. Fortunately, she includes a bibliography, and there, I will hopefully be able to sate my newfound interest in the subject of navigation and horology.

Longitude is a remarkable achievement. The recipe for sales success in international book sales rarely contains such unpromising ingredients as these – an obsessive carpenter’s son from Yorkshire, an intractable navigational problem and a lot of clocks. Yet Longitude succeeds in weaving a narrative full of clashing of ideas, intriguing personalities, bizarre anecdotes and at its heart a tale of the little guy challenging the Establishment.

The story is one that has long been familiar to both naval historians and lovers of clocks, two introspective groups who had failed to bring it to a wider public. Enter Dava Sorbel , with a journalist’s nose for a good story, and the flare to tell it well. This is a page turner that makes what could be a mire of mechanical and mathematical detail simple, easy to follow and enjoy by anyone, whether they are confirmed landlubbers or have a previous interest in the sea.

From a purest point of view the book does have its faults. Sorbel’s understandable desire to tease a cracking yarn from the history leads her to be partial in choosing her facts. She is unfairly hard on the Halley/Maskylene method of calculating longitude, for example, which worked too, and had the big advantage of only requiring equipment that already exist onboard ships (a good compass, a sextant and a trained navigator). It is small wonder that an unproven machine, full of cogs and springs was viewed with suspicion.

It is also only with hindsight that it is clear the marine chronometers was the right solution. The copy of H4 that Cook used on his second voyage cost £450 and took a skilled watch maker several years to make. To give an indication of cost, building a frigate at the time cost about £14K. Given each ship would need several chronometers (to check against each other), at the time of Harrison’s death, it was still not a practical solution for most vessels. It was those that came after Harrison, especially Thomas Earnshaw, who perfected and then mass produced reliable chronometers.

But that is the grumpy naval historian part of me speaking. The author of popular naval fiction part can only applaud a wonderful book.

Interesting review of the tale toward discovering a correct way to measure longitude for a ship at sea. It's short and informative but actually quite on the dry side. Not told in a fictionalized sense at all, but more a recital of fact, placements, and progression. The clock maker who succeeded with that bio-metal strip that did not alter the time by expansion or shrinking of the components became part of the key. As most innovation of great magnitude, it was a self-appointed task, completely by an individual.

John Harrison should get his due. Especially within trade ships of earlier periods his work probably saved countless lives. Unsung hero.

A wonderful short read about the history of longitude. Highly recommend it for fans of maritime novels and colonialism enthusiasts- coz you gotta know the intricacies that went on in a ship to do something as simple as telling time, and if you want to concur lands, you need to know where you are going.