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Longitude: L'histoire vraie du génie solitaire qui résolut le plus grand problème scientifique...
Longitude
Lors des grands voyages d'exploration du XVIIIe siècle, les mauvaises estimations de la longitude, dues à la faible qualité des chronomètres de marine, furent la cause de bien des naufrages. Savants célèbres et techniciens émérites proposèrent quantité de méthodes sophistiquées pour résoudre ce problème. Pourtant, l'histoire des sciences ayant parfois des allures de roman, c'est un humble horloger, John Harrison, qui trouva la solution. Il construisit le premier chronomètre résistant à la houle de grand large, mais dut faire face à l'animosité du milieu scientifique et à la mauvaise foi des représentants de l'Empire britannique.
Une incroyable histoire dont tous les fils – politiques, scientifiques ou académiques – sont ici brillamment dénoués.
Dava Sobel
Journaliste scientifique, elle a longtemps travaillé pour le New York Times . Elle a publié notamment La Fille de Galilée (Odile Jacob, 2001).
Traduit de l'anglais par Gérald Messadié
Lors des grands voyages d'exploration du XVIIIe siècle, les mauvaises estimations de la longitude, dues à la faible qualité des chronomètres de marine, furent la cause de bien des naufrages. Savants célèbres et techniciens émérites proposèrent quantité de méthodes sophistiquées pour résoudre ce problème. Pourtant, l'histoire des sciences ayant parfois des allures de roman, c'est un humble horloger, John Harrison, qui trouva la solution. Il construisit le premier chronomètre résistant à la houle de grand large, mais dut faire face à l'animosité du milieu scientifique et à la mauvaise foi des représentants de l'Empire britannique.
Une incroyable histoire dont tous les fils – politiques, scientifiques ou académiques – sont ici brillamment dénoués.
Dava Sobel
Journaliste scientifique, elle a longtemps travaillé pour le New York Times . Elle a publié notamment La Fille de Galilée (Odile Jacob, 2001).
Traduit de l'anglais par Gérald Messadié
192 pages, Mass Market Paperback
First published October 19, 1995
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About the author
Dava Sobel
47 books951 followersDava Sobel is an American writer of popular expositions of scientific topics. Her books include Longitude, about English clockmaker John Harrison; Galileo's Daughter, about Galileo's daughter Maria Celeste; and The Glass Universe: How the Ladies of the Harvard Observatory Took the Measure of the Stars about the Harvard Computers.
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August 20, 2007I first read Longitude, by Dava Sobel, just after I finished high school, and I devoured it in a sitting or two. It was the first non-fiction book, I think, that I really couldn't put down.
The (true) story is great: legendary historical figures like Isaac Newton, Galileo, James Cook, King George III; scientific conundrums; innovative engineering; a ransom of millions at stake; and a humble, lone man competing against oppressive and manipulative big-wigs.
Background: Latitude lines are the parallel lines that circle the globe above and below the equator, and any sailor could figure out his latitude by measuring the length of the day or looking at the angle of the sun or the north star. But finding one's longitude, the lines that connected the north and south poles, was much more difficult. Anyone could determine that he was on the tropic of cancer, but determining how far along the tropic of cancer was a different challenge--one that, if solved, would revolutionize navigation and save countless lives.
In 1714, Parliament offered a purse worth 20,000 Pounds (millions today) to anyone who could solve the longitude problem. John Harrison was a quiet, hard-working clockmaker who believed he had found the way.
Re-reading this now, many of the details and events in the story remain as compelling as they were ten years ago. Longitude is a tremendous tale of battling scientists and the perseverance of hard work, brilliance, and humility through political intrigue and greed.
Do I recommend it? Yes, to anyone interested in history, science, engineering, geography, politics, astronomy, navigation, clockmaking...
Would I teach it? Not in an English class, but I'd refer to it as a great example of science writing.
Lasting Impression: This book keeps a wonderful balance between the personal, scientific, and political elements of the story. It's history you can escape into.
The (true) story is great: legendary historical figures like Isaac Newton, Galileo, James Cook, King George III; scientific conundrums; innovative engineering; a ransom of millions at stake; and a humble, lone man competing against oppressive and manipulative big-wigs.
Background: Latitude lines are the parallel lines that circle the globe above and below the equator, and any sailor could figure out his latitude by measuring the length of the day or looking at the angle of the sun or the north star. But finding one's longitude, the lines that connected the north and south poles, was much more difficult. Anyone could determine that he was on the tropic of cancer, but determining how far along the tropic of cancer was a different challenge--one that, if solved, would revolutionize navigation and save countless lives.
In 1714, Parliament offered a purse worth 20,000 Pounds (millions today) to anyone who could solve the longitude problem. John Harrison was a quiet, hard-working clockmaker who believed he had found the way.
Re-reading this now, many of the details and events in the story remain as compelling as they were ten years ago. Longitude is a tremendous tale of battling scientists and the perseverance of hard work, brilliance, and humility through political intrigue and greed.
Do I recommend it? Yes, to anyone interested in history, science, engineering, geography, politics, astronomy, navigation, clockmaking...
Would I teach it? Not in an English class, but I'd refer to it as a great example of science writing.
Lasting Impression: This book keeps a wonderful balance between the personal, scientific, and political elements of the story. It's history you can escape into.
September 19, 2018
On October 22, 1707 four English warships crashed into the rocks of the Scilly Isles southwest of England. They quickly sank killing 2,000 men. The cause of this catastrophe was the inability to determine longitude, a problem that beset mariners everywhere. In 1714 the British Parliament set a £20,000 reward for whoever could solve the problem. The Board of Longitude, which would be primarily comprised of astronomers, was set up to award the money. To win the full prize, the method or device had to be accurate to within one-half degree on a trip from England to the West Indies.
There had been many ideas about how to determine longitude, but none worked reliably. They fell into two basic camps: the astronomical and the clock. The idea behind astronomy was to find a pattern of stars, the track of the moon or even the eclipses of the four known moons of Jupiter that would yield longitude. The clock idea was based on time difference. 15 degrees of longitude equals an hour. So a clock that could keep accurate time set to London time could be compared with a clock set to local time. The local time could be determined by sighting the sun at noon. The time difference would give the degrees of longitude from London. But prior to the eighteenth century clocks didn’t work reliably in the rough environment of ships at sea, so the London clock would be off.
In 1727, a self-educated village carpenter and clock maker, John Harrison, heard about the prize. In 1730 he had plans for a chronometer as mariner’s clocks of sufficient accuracy would later be called. He showed his plans to Edmund Halley of comet fame, a board member, who sent him to a prominent clockmaker and fellow Royal Society member who encouraged Harrison to build his clock. Five years later Harrison presented the clock to the board. He had been able to take it on a voyage to Lisbon where it proved its worth. Harrison’s clock was original, intricate and exquisitely crafted. The board was impressed but Harrison himself was not. He felt he could do better and took another five years to build a second chronometer. The Royal Society tested the second clock and gave it accolades but Harrison again decided he could do even better and took twenty years to build a third.
In the thirty years Harrison was building his three clocks astronomers were busily cataloging stars and navigational instruments were vastly improving. By 1760 the board was considering a complicated but effective method of calculating a ship’s longitude from the positions of the moon and stars. And since the board was mostly made up of astronomers, they instinctively preferred an astronomical solution to a simply mechanical one.
Harrison was awarded the prestigious Copley Gold Medal in 1749 at the recommendation of the Royal Society for the many innovations he had made in his clocks that made them so accurate and reliable. But as usual Harrison himself was the hardest to satisfy. Immediately after completing clock three he built a fourth, a pocket watch that ultimately would win the coveted prize. On a West Indies trip the pocket chronometer worked perfectly, but the astronomers on the board dawdled about awarding the prize since they were now enamored with an astronomical solution.
Since presenting his first chronometer, Harrison had been receiving stipends so that his work could continue, but the prize was elusive. Harrison felt his chief nemesis was Astronomer Royal, Nevil Maskelyne, a strong advocate of the astronomical method. Maskelyne took it upon himself to conduct further tests on Harrison’s watch. Finally in 1765 the board awarded Harrison £10,000, half the prize, and ordered him to make two more of the watches to show it could be duplicated. The board also commissioned another clockmaker to build an identical twin of Harrison’s watch. The twin was selected to accompany Captain Cook on his second voyage around the world. The chronometer won high praise from Cook who used it to make accurate maps. Finally through the intervention of King George III, Harrison received a final £8,750 in 1773.
One of the biggest problems with Harrison’s chronometer was the cost, at least £400 to duplicate when a sextant and tables cost £20. But fifteen years later the price would drop to £80 and would keep declining. By 1815 over 5,000 chronometers were in service. The problem of longitude had been solved.
Sobel’s short history reads quickly. The book contains nice photographs of Harrison’s clocks showing their complex inner workings. The chronometers have been restored and now reside in British museums. Sobel explains some of the principles of clock mechanisms and details some of Harrison’s innovations. She also covers failed as well as successful astronomical approaches to finding longitude. But this is also a human interest story of an odd difficult man, a homespun insular genius, who faces the complex scientific society of eighteenth century England. Recommended for the science buff and general reader alike.
There had been many ideas about how to determine longitude, but none worked reliably. They fell into two basic camps: the astronomical and the clock. The idea behind astronomy was to find a pattern of stars, the track of the moon or even the eclipses of the four known moons of Jupiter that would yield longitude. The clock idea was based on time difference. 15 degrees of longitude equals an hour. So a clock that could keep accurate time set to London time could be compared with a clock set to local time. The local time could be determined by sighting the sun at noon. The time difference would give the degrees of longitude from London. But prior to the eighteenth century clocks didn’t work reliably in the rough environment of ships at sea, so the London clock would be off.
In 1727, a self-educated village carpenter and clock maker, John Harrison, heard about the prize. In 1730 he had plans for a chronometer as mariner’s clocks of sufficient accuracy would later be called. He showed his plans to Edmund Halley of comet fame, a board member, who sent him to a prominent clockmaker and fellow Royal Society member who encouraged Harrison to build his clock. Five years later Harrison presented the clock to the board. He had been able to take it on a voyage to Lisbon where it proved its worth. Harrison’s clock was original, intricate and exquisitely crafted. The board was impressed but Harrison himself was not. He felt he could do better and took another five years to build a second chronometer. The Royal Society tested the second clock and gave it accolades but Harrison again decided he could do even better and took twenty years to build a third.
In the thirty years Harrison was building his three clocks astronomers were busily cataloging stars and navigational instruments were vastly improving. By 1760 the board was considering a complicated but effective method of calculating a ship’s longitude from the positions of the moon and stars. And since the board was mostly made up of astronomers, they instinctively preferred an astronomical solution to a simply mechanical one.
Harrison was awarded the prestigious Copley Gold Medal in 1749 at the recommendation of the Royal Society for the many innovations he had made in his clocks that made them so accurate and reliable. But as usual Harrison himself was the hardest to satisfy. Immediately after completing clock three he built a fourth, a pocket watch that ultimately would win the coveted prize. On a West Indies trip the pocket chronometer worked perfectly, but the astronomers on the board dawdled about awarding the prize since they were now enamored with an astronomical solution.
Since presenting his first chronometer, Harrison had been receiving stipends so that his work could continue, but the prize was elusive. Harrison felt his chief nemesis was Astronomer Royal, Nevil Maskelyne, a strong advocate of the astronomical method. Maskelyne took it upon himself to conduct further tests on Harrison’s watch. Finally in 1765 the board awarded Harrison £10,000, half the prize, and ordered him to make two more of the watches to show it could be duplicated. The board also commissioned another clockmaker to build an identical twin of Harrison’s watch. The twin was selected to accompany Captain Cook on his second voyage around the world. The chronometer won high praise from Cook who used it to make accurate maps. Finally through the intervention of King George III, Harrison received a final £8,750 in 1773.
One of the biggest problems with Harrison’s chronometer was the cost, at least £400 to duplicate when a sextant and tables cost £20. But fifteen years later the price would drop to £80 and would keep declining. By 1815 over 5,000 chronometers were in service. The problem of longitude had been solved.
Sobel’s short history reads quickly. The book contains nice photographs of Harrison’s clocks showing their complex inner workings. The chronometers have been restored and now reside in British museums. Sobel explains some of the principles of clock mechanisms and details some of Harrison’s innovations. She also covers failed as well as successful astronomical approaches to finding longitude. But this is also a human interest story of an odd difficult man, a homespun insular genius, who faces the complex scientific society of eighteenth century England. Recommended for the science buff and general reader alike.
April 26, 2024
A short popular science book that examines the invention of the chronometer, or ships clock. Not just a clock, but one that remains uneffected by the humidity, heat and cold, atmospheric pressure and of course the passage in a ship on the high seas, being thrown about. Of course, it must keep time accurately enough to be relied on for navigation, as a clock that accurately keeps time in all conditions is the key to determining longitude. The actual key was knowing the time at a known location (home port or the like) and the current location simultaneously, allowing longitude to be calculated accurately.
And so, it is more than the story of a chronometer. This book describes the circumstances in which the clock finally won out as the recognised way to accurately determine longitude. It was a close thing, with astronomers seemingly unable to allow a mechanic to be recognised where astronomy and mathematics should (in their eyes) have been the way of navigation. The lunar distance method - with sextant, tables of figures and hours of calculations and then adjustments to be made was being put forward by the astronomers as the only reliable way. There were others of course, the mystical powder of sympathy being the most quacky of them (in essence, a powder of secret origin that can heal a wound at a distance, but causes some pain in doing so - the theory proposed an injured dog would be taken aboard a ship and at predetermined times the powder would be administered to the bandages in the home port; on the ship the dog would howl, and the local time could be compared to the home port time, and calculations made to measure the longitude. (This method didn't proceed to testing)).
Overseeing the longitude problem, and able to payout the prize money of twenty thousand pounds, was the (British) Board of Longitude, made up of scientists (astronomers and mathematicians featuring heavily), naval officers and government officials. They continued to adjust the rules and the burden of proof to make it ever harder to claim the prize.
So this is the story of John Harrison, self taught clock maker and his life long development of his chronometers, that became known as the Harrison 1 (H-1 for short) in 1737, the H-2 in 1741, the H-3 in 1759, the H-4 in 1760 and the H-5 in 1770.
A good short book, sadly lacking any photographs other than the one inside the cover. I see from other reviews that a newer edition does provide the photographs, which would be a great addition. Great effort to make the very complex relatively simple.
4 stars
And so, it is more than the story of a chronometer. This book describes the circumstances in which the clock finally won out as the recognised way to accurately determine longitude. It was a close thing, with astronomers seemingly unable to allow a mechanic to be recognised where astronomy and mathematics should (in their eyes) have been the way of navigation. The lunar distance method - with sextant, tables of figures and hours of calculations and then adjustments to be made was being put forward by the astronomers as the only reliable way. There were others of course, the mystical powder of sympathy being the most quacky of them (in essence, a powder of secret origin that can heal a wound at a distance, but causes some pain in doing so - the theory proposed an injured dog would be taken aboard a ship and at predetermined times the powder would be administered to the bandages in the home port; on the ship the dog would howl, and the local time could be compared to the home port time, and calculations made to measure the longitude. (This method didn't proceed to testing)).
Overseeing the longitude problem, and able to payout the prize money of twenty thousand pounds, was the (British) Board of Longitude, made up of scientists (astronomers and mathematicians featuring heavily), naval officers and government officials. They continued to adjust the rules and the burden of proof to make it ever harder to claim the prize.
So this is the story of John Harrison, self taught clock maker and his life long development of his chronometers, that became known as the Harrison 1 (H-1 for short) in 1737, the H-2 in 1741, the H-3 in 1759, the H-4 in 1760 and the H-5 in 1770.
A good short book, sadly lacking any photographs other than the one inside the cover. I see from other reviews that a newer edition does provide the photographs, which would be a great addition. Great effort to make the very complex relatively simple.
4 stars
October 10, 2019
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.
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.
November 20, 2022
4 ☆
Before Britannia could rule the waves, its captains needed to figure out where their ships were going and, just as importantly, how to return home.
Sure, the concept of sectioning off the world by concentric lines of latitude (running east-west) and longitude (aligned by the poles) had existed as early as 300 B.C. The astronomer and cartographer Ptolemy had plotted in 150 C.E. his first world atlas with the Equator as 0° Latitude. Many dedicated astronomers had already witnessed that the sun, moon, and planets passed almost directly overhead at the earth's equator so Ptolemy's decision had been based on scientific observation. But for centuries, where to set 0° longitude was a political selection, so it had bounced around from the Canary Islands (Ptolemy's choice) to Rome to Jerusalem and to many more locations. Finally in 1884, representatives from 26 countries agreed at the International Meridian Conference to make the Greenwich meridian the world's prime meridian.
In Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time, Dava Sobel focused on the 18th century when the British and many others (except perhaps the Polynesians - see Sea People: The Puzzle of Polynesia) were beset by maritime misadventures and tragedies. In the early 1700s, determining a ship's position was a highly imprecise and challenging process as the main method of navigation was by dead reckoning, guided only by compass and the direction of the sun's path. Sailors could reasonably determine which latitude the ship occupied but they were literally and figuratively "at sea" when it came to the question of their longitudinal location. [Sextants weren't invented until the 1730s. Even then celestial navigation would require hours of observation, nautical charts, and an accurate timekeeper.]
The continued loss of ships, lives, and cargoes finally motivated London's various shipping interests to unite in their petition to Parliament to solve the "longitude problem" (which was really a navigation problem). The Longitude Act of 1714 established the Board of Longitude as judges to determine the recipient of prize money which ranged from £10,000 to £20,000, depending on the solution's level of accuracy. According to the Bank of England's inflation calculator, the 1714 prizes would be equivalent to £1.5 to £3 million today.
Dava Sobel wrote an interesting narrative about an unlikely hero, John Harrison, who became enmeshed in a David and Goliath battle that lasted decades. Although John Harrison worked as a carpenter, his mind had mechanical inclinations. He taught himself how to make a clock before he turned twenty. Upon learning of the prize from the Longitude Act, he sought to create the perfect timekeeper, despite the ways a moving vessel with its humid atmosphere eventually rendered all contemporaneous clocks erroneous. When navigators simultaneously knew the local time aboard the ship and the time at another location which had a known longitude, then they could could calculate their ship's longitude.
The Board of Longitude consisted of government officials, naval officers, and scientists from both astronomy and mathematics. By the mid-18th century, one Board member -- the astronomer royal Reverend Nevil Maskelyne -- keenly wanted a solution that reflected his scientific discipline. In particular, Maskelyne favored the lunar distancing method. He/the Board adopted unscrupulous methods to thwart Harrison: sabotage, backstabbing, and theft of intellectual property. Maritime navigation is a technical issue, but this tale reeked of jealousy, competitiveness, and political intrigue. Nothing like money and professional glory to elicit all the ugly sides of human nature.
Be still my geeky heart because this little book (4 hours for the audiobook) touched upon maritime history, astronomy, timekeeping, and even cartography. For an esoteric topic, this story was engaging, concise, and clear. The book only lacked images.
This link shows John Harrison's first submission for consideration. Completed in 1735, the H1 weighed 75 pounds and was housed in a 4' x 4' x 4' case.
https://www.rmg.co.uk/collections/obj...
This link is for Harrison's prize-winning H4, finished in 1759. This elegant chronometer with its pretty detailing had been miniaturized down to a diameter of 5 inches.
https://www.rmg.co.uk/collections/obj...
Harrison was an inventor with a perfectionist's streak. He continued to improve his masterpiece. This link is for John Harrison and Son's H5, made in 1770:
https://collection.sciencemuseumgroup...
Before Britannia could rule the waves, its captains needed to figure out where their ships were going and, just as importantly, how to return home.
Sure, the concept of sectioning off the world by concentric lines of latitude (running east-west) and longitude (aligned by the poles) had existed as early as 300 B.C. The astronomer and cartographer Ptolemy had plotted in 150 C.E. his first world atlas with the Equator as 0° Latitude. Many dedicated astronomers had already witnessed that the sun, moon, and planets passed almost directly overhead at the earth's equator so Ptolemy's decision had been based on scientific observation. But for centuries, where to set 0° longitude was a political selection, so it had bounced around from the Canary Islands (Ptolemy's choice) to Rome to Jerusalem and to many more locations. Finally in 1884, representatives from 26 countries agreed at the International Meridian Conference to make the Greenwich meridian the world's prime meridian.
In Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time, Dava Sobel focused on the 18th century when the British and many others (except perhaps the Polynesians - see Sea People: The Puzzle of Polynesia) were beset by maritime misadventures and tragedies. In the early 1700s, determining a ship's position was a highly imprecise and challenging process as the main method of navigation was by dead reckoning, guided only by compass and the direction of the sun's path. Sailors could reasonably determine which latitude the ship occupied but they were literally and figuratively "at sea" when it came to the question of their longitudinal location. [Sextants weren't invented until the 1730s. Even then celestial navigation would require hours of observation, nautical charts, and an accurate timekeeper.]
The continued loss of ships, lives, and cargoes finally motivated London's various shipping interests to unite in their petition to Parliament to solve the "longitude problem" (which was really a navigation problem). The Longitude Act of 1714 established the Board of Longitude as judges to determine the recipient of prize money which ranged from £10,000 to £20,000, depending on the solution's level of accuracy. According to the Bank of England's inflation calculator, the 1714 prizes would be equivalent to £1.5 to £3 million today.
Dava Sobel wrote an interesting narrative about an unlikely hero, John Harrison, who became enmeshed in a David and Goliath battle that lasted decades. Although John Harrison worked as a carpenter, his mind had mechanical inclinations. He taught himself how to make a clock before he turned twenty. Upon learning of the prize from the Longitude Act, he sought to create the perfect timekeeper, despite the ways a moving vessel with its humid atmosphere eventually rendered all contemporaneous clocks erroneous. When navigators simultaneously knew the local time aboard the ship and the time at another location which had a known longitude, then they could could calculate their ship's longitude.
The Board of Longitude consisted of government officials, naval officers, and scientists from both astronomy and mathematics. By the mid-18th century, one Board member -- the astronomer royal Reverend Nevil Maskelyne -- keenly wanted a solution that reflected his scientific discipline. In particular, Maskelyne favored the lunar distancing method. He/the Board adopted unscrupulous methods to thwart Harrison: sabotage, backstabbing, and theft of intellectual property. Maritime navigation is a technical issue, but this tale reeked of jealousy, competitiveness, and political intrigue. Nothing like money and professional glory to elicit all the ugly sides of human nature.
Be still my geeky heart because this little book (4 hours for the audiobook) touched upon maritime history, astronomy, timekeeping, and even cartography. For an esoteric topic, this story was engaging, concise, and clear. The book only lacked images.
This link shows John Harrison's first submission for consideration. Completed in 1735, the H1 weighed 75 pounds and was housed in a 4' x 4' x 4' case.
https://www.rmg.co.uk/collections/obj...
This link is for Harrison's prize-winning H4, finished in 1759. This elegant chronometer with its pretty detailing had been miniaturized down to a diameter of 5 inches.
https://www.rmg.co.uk/collections/obj...
Harrison was an inventor with a perfectionist's streak. He continued to improve his masterpiece. This link is for John Harrison and Son's H5, made in 1770:
https://collection.sciencemuseumgroup...
July 23, 2023
An epic 40 year struggle!
Dava Sobel, like Simon Winchester or Canada's Pierre Berton, has clearly mastered the art of writing history in a form that is not only informative but, perhaps more important, is also compelling and entertaining.
In eighteenth century Europe, although scientists had long wrestled with the problem, sailors had no method of determining their longitude. The economic losses and the loss of life was so staggering that finding a solution to the problem was elevated to the almost legendary level of finding the Holy Grail or the Fountain of Youth. In the Longitude Act of 1714, the British Parliament offered a prize of 20,000 pounds (equivalent to several million dollars today) to anyone who found a "practicable and useful" means of determining longitude.
One need look no further than the list of stellar minds that were applied to the problem (and failed to find the solution) - Tycho Brahe, Christian Huygens, Robert Cooke, Edmund Halley, Galileo and Vincenzo Galilei, Sir Isaac Newton, Christopher Wren - to appreciate the almost insurmountable difficulty that this issue presented to the navigators of the day.
LONGITUDE presents the story of John Harrison, a self-taught Yorkshire clockmaker, who struggles alone to raise the art of clock making to unheard of levels of accuracy. The story of his ultimately receiving the prize from Britain's Board of Longitude is a dramatic, inspiring and heart-rending portrayal of 40 years of perseverance and struggle against political shenanigans and skullduggery as well as personal feuds, jealousy and outright espionage and sabotage.
From Admiral Sir Clowdisley Shovell's catastrophic loss of over 2000 lives when his fleet crashed at Land's End in 1707 to the refurbishment of Harrison's prize-winning chronometer for posterity in 1833, Dava Sobel has brought this small but important piece of the 18th century to life in a way that few other writers could manage. Two thumbs up for a thoroughly enjoyable piece of non-fiction writing!
Paul Weiss
Dava Sobel, like Simon Winchester or Canada's Pierre Berton, has clearly mastered the art of writing history in a form that is not only informative but, perhaps more important, is also compelling and entertaining.
In eighteenth century Europe, although scientists had long wrestled with the problem, sailors had no method of determining their longitude. The economic losses and the loss of life was so staggering that finding a solution to the problem was elevated to the almost legendary level of finding the Holy Grail or the Fountain of Youth. In the Longitude Act of 1714, the British Parliament offered a prize of 20,000 pounds (equivalent to several million dollars today) to anyone who found a "practicable and useful" means of determining longitude.
One need look no further than the list of stellar minds that were applied to the problem (and failed to find the solution) - Tycho Brahe, Christian Huygens, Robert Cooke, Edmund Halley, Galileo and Vincenzo Galilei, Sir Isaac Newton, Christopher Wren - to appreciate the almost insurmountable difficulty that this issue presented to the navigators of the day.
LONGITUDE presents the story of John Harrison, a self-taught Yorkshire clockmaker, who struggles alone to raise the art of clock making to unheard of levels of accuracy. The story of his ultimately receiving the prize from Britain's Board of Longitude is a dramatic, inspiring and heart-rending portrayal of 40 years of perseverance and struggle against political shenanigans and skullduggery as well as personal feuds, jealousy and outright espionage and sabotage.
From Admiral Sir Clowdisley Shovell's catastrophic loss of over 2000 lives when his fleet crashed at Land's End in 1707 to the refurbishment of Harrison's prize-winning chronometer for posterity in 1833, Dava Sobel has brought this small but important piece of the 18th century to life in a way that few other writers could manage. Two thumbs up for a thoroughly enjoyable piece of non-fiction writing!
Paul Weiss
September 20, 2016
Really lovely and very interesting reading. Everybody knows about longitude but I guess not so many know the struggles and fights behind the tries to 'conquer' it, including myself.
John Harrison was a genius of his times; beside the fact that he produced the first accurate marine watches for calculating longitude, his pieces are works of art:
H1
(http://www.rmg.co.uk/discover/behind-...)
H3
(http://www.rmg.co.uk/discover/behind-...)
And the masterpiece, H4, completed in 1759:
(http://prints.rmg.co.uk/art/520153/ma...)
The book is written on everyone's understanding, full of new historical facts (for me). It was a pleasure and it takes just a few hours to get it done; totally worthy of your time.
John Harrison was a genius of his times; beside the fact that he produced the first accurate marine watches for calculating longitude, his pieces are works of art:
H1
(http://www.rmg.co.uk/discover/behind-...)
H3
(http://www.rmg.co.uk/discover/behind-...)
And the masterpiece, H4, completed in 1759:
(http://prints.rmg.co.uk/art/520153/ma...)
The book is written on everyone's understanding, full of new historical facts (for me). It was a pleasure and it takes just a few hours to get it done; totally worthy of your time.
February 5, 2024
Nowadays we can lose track of how scary and dangerous it can be to be lost.
We have GPS and apps to make location easy and our great and wild planet has been tagged, labeled and thoroughly domesticated.
But there was a time really not very long ago where if you were out at sea, you did not have a very exact idea where you were. Being lost at sea could mean running aground or becoming so off your planned trajectory that food stores could run out and your crew could face a slow death from starvation and dehydration.
There was navigation but it was limited in accuracy east or west, the north and south latitudes being more or less identifiable. Throughout the 1700s we follow the quest to solve this important problem for shipping, mapping, and safe and efficient navigation.
Writer Dava Sobel populates this short history with a cast of scientists, astronomers, engineers, mathematicians and - a carpenter. People who know such things figured out that clockmaking, building a durable and efficient chronometer would solve the longitude puzzle that had been plaguing mariners since time immemorial. We spend the next hundred odd years with behind the scenes story about how we went a long way towards not being lost.
We have GPS and apps to make location easy and our great and wild planet has been tagged, labeled and thoroughly domesticated.
But there was a time really not very long ago where if you were out at sea, you did not have a very exact idea where you were. Being lost at sea could mean running aground or becoming so off your planned trajectory that food stores could run out and your crew could face a slow death from starvation and dehydration.
There was navigation but it was limited in accuracy east or west, the north and south latitudes being more or less identifiable. Throughout the 1700s we follow the quest to solve this important problem for shipping, mapping, and safe and efficient navigation.
Writer Dava Sobel populates this short history with a cast of scientists, astronomers, engineers, mathematicians and - a carpenter. People who know such things figured out that clockmaking, building a durable and efficient chronometer would solve the longitude puzzle that had been plaguing mariners since time immemorial. We spend the next hundred odd years with behind the scenes story about how we went a long way towards not being lost.
August 15, 2023
"For the ocean's silence spoke a single, uniform, terrible message: 'You are lost, you are lost."
In "Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time," I was taken on an exhilarating journey through the fascinating world of 18th-century navigation and the brilliant mind of John Harrison. The book, written by Dava Sobel, chronicles the extraordinary life and achievements of this lone genius who tackled the most pressing problem of his era – determining a ship's longitude at sea.
A quote that emphasizes that despite Harrison's lack of formal education in mathematics and arithmetic, he possessed an extraordinary talent for using simple tools like sticks, pendulums, and loops of gut to calculate and measure time accurately. This unique skill allowed him to devise innovative solutions that ultimately led to the creation of accurate maritime chronometers.
Sobel vividly transported me back to the Age of Exploration, where maritime trade, conquests, and scientific advancements were shaping the world. Navigational accuracy was paramount, yet the elusive concept of determining longitude plagued sailors and explorers, leading to countless shipwrecks and lost lives. Enter John Harrison, a self-taught clockmaker whose determination and ingenuity led him to create a series of groundbreaking timepieces, known as chronometers.
The narrative expertly weaves between the challenges Harrison faced in developing his accurate chronometers and the political and scientific rivalries of the time. The Royal Observatory in Greenwich played a significant role in the story, as did the scientific establishment's skepticism of Harrison's unconventional methods. As I turned the pages, I marveled at the intricacies of clockmaking and the profound impact Harrison's chronometers had on navigation. The book illuminated the relationship between timekeeping and longitude, a connection that had eluded scholars and astronomers for centuries.
This book is a captivating account of a forgotten hero, an unsung genius whose dedication and brilliance reshaped the course of history. A must read!
In "Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time," I was taken on an exhilarating journey through the fascinating world of 18th-century navigation and the brilliant mind of John Harrison. The book, written by Dava Sobel, chronicles the extraordinary life and achievements of this lone genius who tackled the most pressing problem of his era – determining a ship's longitude at sea.
"Harrison never learned to add or multiply. Yet, using little more than sticks, pendulums, and loops of gut, he'd found a way to calculate the new day's noon as soon as the old day's was over. A day's worth of those bits and pieces would eventually add up to the only quantity that meant anything at all to him: time."
A quote that emphasizes that despite Harrison's lack of formal education in mathematics and arithmetic, he possessed an extraordinary talent for using simple tools like sticks, pendulums, and loops of gut to calculate and measure time accurately. This unique skill allowed him to devise innovative solutions that ultimately led to the creation of accurate maritime chronometers.
Sobel vividly transported me back to the Age of Exploration, where maritime trade, conquests, and scientific advancements were shaping the world. Navigational accuracy was paramount, yet the elusive concept of determining longitude plagued sailors and explorers, leading to countless shipwrecks and lost lives. Enter John Harrison, a self-taught clockmaker whose determination and ingenuity led him to create a series of groundbreaking timepieces, known as chronometers.
The narrative expertly weaves between the challenges Harrison faced in developing his accurate chronometers and the political and scientific rivalries of the time. The Royal Observatory in Greenwich played a significant role in the story, as did the scientific establishment's skepticism of Harrison's unconventional methods. As I turned the pages, I marveled at the intricacies of clockmaking and the profound impact Harrison's chronometers had on navigation. The book illuminated the relationship between timekeeping and longitude, a connection that had eluded scholars and astronomers for centuries.
This book is a captivating account of a forgotten hero, an unsung genius whose dedication and brilliance reshaped the course of history. A must read!
September 15, 2022
Dava Sobel has written a very accessible account of a genius who prevailed against the odds. It's concise, absorbing and packed full of fascinating details and interesting characters. A perfect history book for the general reader, and as enjoyable as any novel.
The subtitle says it all, Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time. That lone genius was John Harrison (1693-1776) a self taught clock maker. Over 40 years, he invented and produced four increasingly precise and compact chronometers capable of accurately measuring time over a long, rough sea voyage. By comparing the chronometer's time to local sun time, a navigator could precisely measure longitude. Prior to his invention there was no accurate way of measuring longitude and many lives were lost due to catastrophic miscalculations.
In 1714 the British Parliament offered a reward to whoever could solve the longitude problem with a prize of £20,000 for the winner. At that time astronomy was seen as the best route to a solution despite being time consuming and difficult.
You might think that Harrison's incredible devices would be unanimously welcomed. Alas, no. He was forever battling vested interests until eventually, and after decades, King George III intervened.
John Harrison's marine timekeepers are on display at the Royal Observatory in Greenwich, London and are well worth seeing...
https://www.rmg.co.uk/royal-observato...
4/5
The subtitle says it all, Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time. That lone genius was John Harrison (1693-1776) a self taught clock maker. Over 40 years, he invented and produced four increasingly precise and compact chronometers capable of accurately measuring time over a long, rough sea voyage. By comparing the chronometer's time to local sun time, a navigator could precisely measure longitude. Prior to his invention there was no accurate way of measuring longitude and many lives were lost due to catastrophic miscalculations.
In 1714 the British Parliament offered a reward to whoever could solve the longitude problem with a prize of £20,000 for the winner. At that time astronomy was seen as the best route to a solution despite being time consuming and difficult.
You might think that Harrison's incredible devices would be unanimously welcomed. Alas, no. He was forever battling vested interests until eventually, and after decades, King George III intervened.
John Harrison's marine timekeepers are on display at the Royal Observatory in Greenwich, London and are well worth seeing...
https://www.rmg.co.uk/royal-observato...
4/5
May 2, 2018
This book makes what may sound like a dry technical topic very interesting. The concept of Latitude and Longitude, now commonly understood as GPS coordinates, was not always readily available. While Latitude was relatively easy to deal with as the horizontal position from the equator between earth's two poles, Longitude was a major puzzle that was worked on and studied by many brilliant minds over hundreds of years. Conceptually it is very simple: By comparing the position east or west at your location from a known time at a standard location(called the Prime Meridian), the difference in hours gives your location in increments of 15 degrees (360 degrees around the globe divided by 24 hours) for each hour. Then, by knowing the circumference of the earth, you can convert it to distance or physical position on the earth. But with notoriously error prone time pieces that could gain or lose 10-20 minutes or more per day, especially in a humid, moving environment aboard ships with wide temperature variations, it was easy to be off 50, 100, 200 miles or more. this book presents the stories of the development of more and more accurate time pieces, alternative celestial positioning methods that were useless if overcast, and deciding and agreeing on where the standard time for comparison (today's Greenwich Mean Time) should be. Great diversionary read for anyone looking for something interesting as well as educational.
December 29, 2022
A very interesting, and informative book that for the most part, effectively balances character with information. I did start to feel like the book needed some diagrams or pictures, because it got really difficult forming mental images of such obscure and complex devices.
November 17, 2025
This is a marvellous book - one of those rare, odd books that come out of nowhere and captivate everyone and become best sellers.
I knew the gist of the John Harrison story prior to reading Longitude (and for UK readers of a certain age it was one of Harrisons creations which provided the conclusion of the much loved TV series 'Only Fools and Horses'), but Dava Sobel goes beyond the accomplishments of this single man and charts the course of the problem, and all its proposed solutions. She sets up a context against which the true scope and power of Harrison’s achievement might be measured...More than a simple puzzle that made academics scratch their heads, the problem of longitude affected society and the economy. It drove scientific inquiry and technological innovation. Watching this unfold through Sobel’s storytelling is breathtaking and inspiring.
Harrison’s origins read like something out of a fairy tale or a superhero book. His father was a carpenter, and he was trained as a carpenter, not as a watchmaker. Yet this craft fascinated him, so he trained himself to build clocks. In fact, he built a clock entirely out of wood, a clock that required no lubrication owing to the way he had constructed it and the type of wood he had used. John Harrison was not just a tinker or dabbler; he was a creative genius. So he decided to solve the longitude problem. And he did. But when he went to London for his reward, he was met with scepticism, animosity, and belligerence. Thanks to the politics of London...for the rest of his life, Harrison would improve upon his prototype and receive stipends from the Board, but that recognition and prize money lay beyond his reach...The central conflict of Longitude is not the need to calculate longitude but the antagonistic relationship between the Harrison and the Reverend Maskelyne...(who) championed the “lunar distance” method of calculating longitude. It just so happened, too, that later on in his life he became the Astronomer Royal, and therefore a member of the Board of Longitude. That didn’t go over well for Harrison’s chances at being awarded that prize.
Indeed, echoes of the great rivalries across the ages surface in Longitude, reminding us that science is never as simple nor as objective as we like to think. Invention is partly innovation, partly inspiration, and part imitation. Sobel is careful to stress that Maskelyne was not the villain in this piece, merely the antagonist—like the feud between Newton and Hooke, the feud between Harrison and Maskelyne was a dispute between two men who knew their stuff. But where ego is concerned and establishing primacy is often necessary for the money and prestige that follows a discovery, tempers will flare and harsh words will be exchanged.
So with this centuries-old problem juxtaposed against a feud between a rural carpenter-turned-watchmaker and the Astronomer Royal, Sobel turns Longitude from a history book into an exciting story. The trick to making any historical account interesting lies in exposing the details and connections that a casual reader, like myself, wouldn’t necessarily know. Sobel does this by charting the connections between Harrison and luminary contemporaries, including Isaac Newton, Edmund Halley, and Christopher Wren. She does this even with the considerable handicap of lacking much evidence about Harrison’s early life.
I knew the gist of the John Harrison story prior to reading Longitude (and for UK readers of a certain age it was one of Harrisons creations which provided the conclusion of the much loved TV series 'Only Fools and Horses'), but Dava Sobel goes beyond the accomplishments of this single man and charts the course of the problem, and all its proposed solutions. She sets up a context against which the true scope and power of Harrison’s achievement might be measured...More than a simple puzzle that made academics scratch their heads, the problem of longitude affected society and the economy. It drove scientific inquiry and technological innovation. Watching this unfold through Sobel’s storytelling is breathtaking and inspiring.
Harrison’s origins read like something out of a fairy tale or a superhero book. His father was a carpenter, and he was trained as a carpenter, not as a watchmaker. Yet this craft fascinated him, so he trained himself to build clocks. In fact, he built a clock entirely out of wood, a clock that required no lubrication owing to the way he had constructed it and the type of wood he had used. John Harrison was not just a tinker or dabbler; he was a creative genius. So he decided to solve the longitude problem. And he did. But when he went to London for his reward, he was met with scepticism, animosity, and belligerence. Thanks to the politics of London...for the rest of his life, Harrison would improve upon his prototype and receive stipends from the Board, but that recognition and prize money lay beyond his reach...The central conflict of Longitude is not the need to calculate longitude but the antagonistic relationship between the Harrison and the Reverend Maskelyne...(who) championed the “lunar distance” method of calculating longitude. It just so happened, too, that later on in his life he became the Astronomer Royal, and therefore a member of the Board of Longitude. That didn’t go over well for Harrison’s chances at being awarded that prize.
Indeed, echoes of the great rivalries across the ages surface in Longitude, reminding us that science is never as simple nor as objective as we like to think. Invention is partly innovation, partly inspiration, and part imitation. Sobel is careful to stress that Maskelyne was not the villain in this piece, merely the antagonist—like the feud between Newton and Hooke, the feud between Harrison and Maskelyne was a dispute between two men who knew their stuff. But where ego is concerned and establishing primacy is often necessary for the money and prestige that follows a discovery, tempers will flare and harsh words will be exchanged.
So with this centuries-old problem juxtaposed against a feud between a rural carpenter-turned-watchmaker and the Astronomer Royal, Sobel turns Longitude from a history book into an exciting story. The trick to making any historical account interesting lies in exposing the details and connections that a casual reader, like myself, wouldn’t necessarily know. Sobel does this by charting the connections between Harrison and luminary contemporaries, including Isaac Newton, Edmund Halley, and Christopher Wren. She does this even with the considerable handicap of lacking much evidence about Harrison’s early life.
February 13, 2020
Non-fiction about the quest to develop a reliable method for measuring longitude. The first several chapters describe the difficulties encountered by ships attempting to navigate solely based on latitude. The focus then shifts to a biography of John Harrison, the 18th century clockmaker who attempted to solve this problem based on timekeeping. It also describes his primary competitor and adversary, Nevil Maskelyne, who was keen on proving that the best approach involved astronomical readings. They and many others vied for the monetary prize offered by the British government. Along the way, the author highlights some of the more outlandish ideas, one of which involves barking dogs!
The book is far more than a scientific analysis of the problem of finding longitude. It portrays the intrigue, rivalries, conflicts, and accidental discoveries that make this book a fascinating reading experience. It is a story of the triumph of a perfectionistic genius of humble origins over the well-educated experts of the day. Recommended to those who, like me, enjoy stories related to travel by sea, voyages of exploration and discovery, and maritime adventures in days of yore.
The book is far more than a scientific analysis of the problem of finding longitude. It portrays the intrigue, rivalries, conflicts, and accidental discoveries that make this book a fascinating reading experience. It is a story of the triumph of a perfectionistic genius of humble origins over the well-educated experts of the day. Recommended to those who, like me, enjoy stories related to travel by sea, voyages of exploration and discovery, and maritime adventures in days of yore.
![Profile Image for Terence M [Quot libros, quam breve tempus!].](/_next/image?url=https%3A%2F%2Fi.gr-assets.com%2Fimages%2FS%2Fcompressed.photo.goodreads.com%2Fusers%2F1712357414i%2F6658001._UY200_CR4%2C0%2C200%2C200_.jpg&w=128&q=75)
March 31, 2021
4.0 Stars - "I Really Liked It!"
Longitude - The True Story of a Lone Genius who Solved the Greatest Scientific Problem of His Time
Author: Dava Sobel - Narrator: Kate Reading
This is a review of a wonderfully fascinating book that I read in (say) April 1999 and listened to as an audiobook sometime about 24 May 2015. I thoroughly enjoyed it both times, although the technicalities of measuring Longitude were more difficult to comprehend when reading the paper book. Fortunately my somewhat dim memory assisted my comprehension as I listened to the audiobook.
Highly recommended, and a good read for the 'not-so-technically-minded' about a very technical subject.
Longitude - The True Story of a Lone Genius who Solved the Greatest Scientific Problem of His Time
Author: Dava Sobel - Narrator: Kate Reading
This is a review of a wonderfully fascinating book that I read in (say) April 1999 and listened to as an audiobook sometime about 24 May 2015. I thoroughly enjoyed it both times, although the technicalities of measuring Longitude were more difficult to comprehend when reading the paper book. Fortunately my somewhat dim memory assisted my comprehension as I listened to the audiobook.
Highly recommended, and a good read for the 'not-so-technically-minded' about a very technical subject.
December 20, 2021
3.5 stars
For a very short book—175 pages of text, and they’re small pages—this little work of history packs in a decent amount of information. It’s about the centuries-long quest to discover an accurate way of measuring longitude at sea, and particularly the 18th century British solutions.
With the right instruments and calculations, latitude is fairly easy to determine from the position of the sun and stars; people have been doing that for millennia. Longitude is much harder, because everyone at the same latitude sees the same sun and stars, just at different times of day. Essentially, the earth is a giant clock—so, without satellites, how to figure where on it you are, especially at sea without landmarks? For centuries, thinkers have understood that the answer was measuring time, and eventually two possible solutions emerged. One was observing a celestial event (Galileo chose the eclipses of the moons of Jupiter) and comparing the local time at which it occurs to the time calculated in an almanac at which it will occur at some known location. The other was comparing your local time, determined through the angle of the sun, to the time at some known location, from which you can calculate the degree of difference between the two places. Unfortunately, up through the 18th century, there were no sufficiently accurate instruments to use either of these methods at sea, resulting in great loss of life when navigators didn’t know where they were. (Not helped, in the British fleet, by an apparent rule prohibiting common seamen from keeping tabs on the navigation themselves. One brave soul came forward with his calculations in an attempt to avert a disaster and was promptly hanged for mutiny, his warning ignored; the fleet then foundered and most of the crew died.)
The book summarizes the situation and the journey of 18th century clockmaker John Harrison to building timepieces that could keep sufficiently accurate time (despite the jostling, temperature and humidity changes, etc., that had doomed prior sea clocks) to allow ships to find their way. It’s readable and interesting, and I certainly learned a lot about early clocks and watches and the mathematics of navigation, as well as some fun tidbits on a variety of other topics. There’s also a lot about the jostling for position among the various men who wanted to claim credit (and a large financial reward) for solving the longitude problem.
On the other hand, the book is quite brief, and the author seems overly enamored of Harrison, though she doesn’t actually refer to him as a “lone genius” as stated in the subtitle (he seems to have collaborated as much as anyone else at the time, when there was less apparent need for lab assistants than today). It seems odd that she never addresses what appears to me the reason most people won’t have heard of Harrison: in the sciences we tend to lionize those who came up with big ideas, rather than the hands-on technicians who made them work. And Harrison was an instrument maker, very much a hands-on technician; his wasn’t a conceptual breakthrough but a technical one.
Overall, a perfectly adequate book, though not to my mind a remarkable one. But if you’re interested, it’s worth taking a look as it certainly won’t take long to read.
For a very short book—175 pages of text, and they’re small pages—this little work of history packs in a decent amount of information. It’s about the centuries-long quest to discover an accurate way of measuring longitude at sea, and particularly the 18th century British solutions.
With the right instruments and calculations, latitude is fairly easy to determine from the position of the sun and stars; people have been doing that for millennia. Longitude is much harder, because everyone at the same latitude sees the same sun and stars, just at different times of day. Essentially, the earth is a giant clock—so, without satellites, how to figure where on it you are, especially at sea without landmarks? For centuries, thinkers have understood that the answer was measuring time, and eventually two possible solutions emerged. One was observing a celestial event (Galileo chose the eclipses of the moons of Jupiter) and comparing the local time at which it occurs to the time calculated in an almanac at which it will occur at some known location. The other was comparing your local time, determined through the angle of the sun, to the time at some known location, from which you can calculate the degree of difference between the two places. Unfortunately, up through the 18th century, there were no sufficiently accurate instruments to use either of these methods at sea, resulting in great loss of life when navigators didn’t know where they were. (Not helped, in the British fleet, by an apparent rule prohibiting common seamen from keeping tabs on the navigation themselves. One brave soul came forward with his calculations in an attempt to avert a disaster and was promptly hanged for mutiny, his warning ignored; the fleet then foundered and most of the crew died.)
The book summarizes the situation and the journey of 18th century clockmaker John Harrison to building timepieces that could keep sufficiently accurate time (despite the jostling, temperature and humidity changes, etc., that had doomed prior sea clocks) to allow ships to find their way. It’s readable and interesting, and I certainly learned a lot about early clocks and watches and the mathematics of navigation, as well as some fun tidbits on a variety of other topics. There’s also a lot about the jostling for position among the various men who wanted to claim credit (and a large financial reward) for solving the longitude problem.
On the other hand, the book is quite brief, and the author seems overly enamored of Harrison, though she doesn’t actually refer to him as a “lone genius” as stated in the subtitle (he seems to have collaborated as much as anyone else at the time, when there was less apparent need for lab assistants than today). It seems odd that she never addresses what appears to me the reason most people won’t have heard of Harrison: in the sciences we tend to lionize those who came up with big ideas, rather than the hands-on technicians who made them work. And Harrison was an instrument maker, very much a hands-on technician; his wasn’t a conceptual breakthrough but a technical one.
Overall, a perfectly adequate book, though not to my mind a remarkable one. But if you’re interested, it’s worth taking a look as it certainly won’t take long to read.
June 8, 2021
I was reminded of this book today because in was on the PageADay Book Lover's Calendar for 3-31-2015. I read it back in the year 2000(+-). I have favorable recollections of the book, and I found it to be in interesting story. The following short review is copied from the calendar.
Anyone with an interest in history or things maritime should consider Longitude," said USA Today of this bestseller. Sobel describes 18th-century clockmaker John Harrison's struggle to invent an accurate chronometer, which measured time, necessary to calculate longitude while at sea. Requiring decades of painstaking research, Harrison finally accomplished his goal, but then faded into the mists of time until his reputation was revived by Sobel's book, which is full of little-known facts about science, ships, and England in the 1700s.
LONGITUDE, THE TRUE STORY OF A LONE GENIUS WHO SOLVED THE GREATEST SCIENTIFIC PROBLEM OF HIS TIME, by Dava Sobel (1995; Walker & Company, 2007)
The link below is to an excerpt from the book:
https://t.co/NB5tdBsnKQ
The following is from the "1,000 Books to Read Before You Die" calendar for June 7, 2021.
______
It's surprising to realize that it was not until the middle of the 18th century, when Jon Harrison invented the chronometer—"a clock that would carry the true time from the home port, like an eternal flame, to any remote corner of the world"—that sailors could count on finding their way by reliable devices. Dava Sobel's Longitude tells the story of the search for this ultimate solution to one of the thorniest dilemmas in scientific history: How do you know where you are once you lose sight of land? It's an enticing, exciting chronicle of exploration, experiment, and, not least, mechanical genius.
Anyone with an interest in history or things maritime should consider Longitude," said USA Today of this bestseller. Sobel describes 18th-century clockmaker John Harrison's struggle to invent an accurate chronometer, which measured time, necessary to calculate longitude while at sea. Requiring decades of painstaking research, Harrison finally accomplished his goal, but then faded into the mists of time until his reputation was revived by Sobel's book, which is full of little-known facts about science, ships, and England in the 1700s.
LONGITUDE, THE TRUE STORY OF A LONE GENIUS WHO SOLVED THE GREATEST SCIENTIFIC PROBLEM OF HIS TIME, by Dava Sobel (1995; Walker & Company, 2007)
The link below is to an excerpt from the book:
https://t.co/NB5tdBsnKQ
The following is from the "1,000 Books to Read Before You Die" calendar for June 7, 2021.
______
It's surprising to realize that it was not until the middle of the 18th century, when Jon Harrison invented the chronometer—"a clock that would carry the true time from the home port, like an eternal flame, to any remote corner of the world"—that sailors could count on finding their way by reliable devices. Dava Sobel's Longitude tells the story of the search for this ultimate solution to one of the thorniest dilemmas in scientific history: How do you know where you are once you lose sight of land? It's an enticing, exciting chronicle of exploration, experiment, and, not least, mechanical genius.
January 6, 2009
This book was intended for the general reader. Consequently it did not deal much with the details either of the astronomical or mechanical approaches to solving the problem of finding longitude on the high seas. Instead it focused on description of John Harrison's quest to build an ocean chronometer. The author treats the difficulties Harrison encountered convincing the Board of Longitude of the efficacy of his devices as a matter of petty politics and egotism without offering the reader sufficient detail about the technical disputes to make any judgments about the scientific debate at the center of the controversy.
This book was a bit of a disappointment considering the glowing reviews it received.
This book was a bit of a disappointment considering the glowing reviews it received.
This entire review has been hidden because of spoilers.
March 29, 2020
This book is just about perfection. Why and who decided to venture out and sail the "flat" world and risk dropping off the edge? How did charts and early navigational equipment come to be? There is latitude but what is longitude and who are the pioneers of this science? Answers all contained but in an easy to read and understand book. Well recommended.
August 21, 2013
Finding the latitude in the 17th century was straightforward, but finding the longitude was extremely difficult. This compromised the safety of all seafarers, and in one particular incident around 200 lives were lost of the Isles of Scilly.
The admiralty of the day decided to set up a Longitude board and offer a prize to the inventor of a method to reliably calculate the longitude of a vessel. Various methods were tried, including one that took lunar sightings developed by Nevil Maskelyne.
Enter John Harrison. He taught himself to read and write, and was a proficient musician, his real talent was clocks. His first wooden pendulum clock is still in existence, held at The Worshipful Company of Clockmakers. And it was this talent that he put to good use to start to develop the devices that would enable the navy to know their exact longitude.
His first attempt at a device was called H-1 and has lots of new technologies including frictionless bearings, the gridiron pendulum and the grasshopper escapment. This clock lost a second a month compared to the best clocks of the day that would loose 1 minute a day. The clock is still working.
He presented the drawings to the Longitude board, and they gave permission to make one. The clock passed the tests, but as it improved the board decided to amend the original tests make them tougher. Harrison went on to develop 4 versions to meet these changing requirements, culminating in a 5 inch diameter watch that did the same as the H-1.
By this time Nevil Maskelyne was head of the Longitude board. He made it extremely difficult for Harrison as he wanted his preferred lunar method to win. Harrison complied with the demanding requirements, and surrendered his clocks to the board. It was only with the kings intervention that the reward was finally given to Harrison.
Sobel has written quite a dry account of this tale of engineering excellence and political manipulation. Whilst it get all the facts across, it doesn't convey the emotions of the men involved.
The admiralty of the day decided to set up a Longitude board and offer a prize to the inventor of a method to reliably calculate the longitude of a vessel. Various methods were tried, including one that took lunar sightings developed by Nevil Maskelyne.
Enter John Harrison. He taught himself to read and write, and was a proficient musician, his real talent was clocks. His first wooden pendulum clock is still in existence, held at The Worshipful Company of Clockmakers. And it was this talent that he put to good use to start to develop the devices that would enable the navy to know their exact longitude.
His first attempt at a device was called H-1 and has lots of new technologies including frictionless bearings, the gridiron pendulum and the grasshopper escapment. This clock lost a second a month compared to the best clocks of the day that would loose 1 minute a day. The clock is still working.
He presented the drawings to the Longitude board, and they gave permission to make one. The clock passed the tests, but as it improved the board decided to amend the original tests make them tougher. Harrison went on to develop 4 versions to meet these changing requirements, culminating in a 5 inch diameter watch that did the same as the H-1.
By this time Nevil Maskelyne was head of the Longitude board. He made it extremely difficult for Harrison as he wanted his preferred lunar method to win. Harrison complied with the demanding requirements, and surrendered his clocks to the board. It was only with the kings intervention that the reward was finally given to Harrison.
Sobel has written quite a dry account of this tale of engineering excellence and political manipulation. Whilst it get all the facts across, it doesn't convey the emotions of the men involved.
March 14, 2010
As far as popular science writing, or popular history of science writing (take your pick) goes, I've read better books. This is a book about a self-taught village clock-maker who created a whole new breed of amazingly precise chronometers, which enable the accurate measurement of longitude, and the fight he had with astronomers to get his solution recognised (and rewarded). High stakes (both in terms of the potential benefits to be had from being able to use longitude, and in terms of the reward value placed on finding a solution), but while the author keeps on reminding us that it's very important, and telling us that his struggles with the politics of the board who were supposed to award the reward were very severe, I generally felt underwhelmed by the story, or maybe the way it was being told and structured.
After starting off very dramatically, (at one point even blaming the problems of scurvy on the inability to find longitude), the early part of the story of John Harrison (the clock-maker) seemed pretty bland and lacking in tension. When tension did arrive later on (basically after he'd already solved the problem), everything got kind of rushed through - it is a very short book, and it might have been better with a little more time devoted to rounding out some of the ideas, so that diversions into a brief recap of Captain Cook's death, or the voyage of the Beagle actually felt like they belonged, rather than being shoehorned in for some broader appeal. All in all, I ended up feeling like Sobel had manufactured a bunch of tension and drama, but not actually delivered on filling in the colour and texture of it all.
It's not a bad book, but it itches for a rewrite for hacking and resorting and building into a better flow.
After starting off very dramatically, (at one point even blaming the problems of scurvy on the inability to find longitude), the early part of the story of John Harrison (the clock-maker) seemed pretty bland and lacking in tension. When tension did arrive later on (basically after he'd already solved the problem), everything got kind of rushed through - it is a very short book, and it might have been better with a little more time devoted to rounding out some of the ideas, so that diversions into a brief recap of Captain Cook's death, or the voyage of the Beagle actually felt like they belonged, rather than being shoehorned in for some broader appeal. All in all, I ended up feeling like Sobel had manufactured a bunch of tension and drama, but not actually delivered on filling in the colour and texture of it all.
It's not a bad book, but it itches for a rewrite for hacking and resorting and building into a better flow.
April 27, 2020
"The British Parliament, in its famed Longitude Act of 1714, set the highest bounty of all, naming a prize equal to a king’s ransom (several million dollars in today’s currency) for a “Practicable and Useful” means of determining longitude.”
I read this historical and biographical account in one evening. It's not without flaws, but I was fascinated and gave it 5 stars for holding my attention in a topic I rarely read about, where science, math, politics, and culture intersect with astronomical and nautical history. The technical details may be insufficient for some readers, but there was just enough for me. Author Dava Sobel caught my interest and held it. Kudos to her!
Anyway....Naval ships were crashing against rocks and smashing to bits, off course because finding longitude was rather a guessing game, even though latitude was fairly straightforward. Skippers didn't know how far north or south of their latitudinal orientation they had sailed. They'd run aground in the dark, the fog, etc.
So.... In 1714, King George and Parliament earmarked a HUGE reward (£20,000 pounds!) for whoever was first to come up with a highly reliable way to find longitudinal orientation.
Solving the longitude problem became a national pastime, for decades. All kinds of quacks tried all sorts of crackpot methods. Funny funny stuff!! Sensible seamen, scientists, astronomers, and mathematicians also joined the race.
However, it was a lowly clockmaker who came up with the best method. An enduring method. It became his life's work.
Did John Harrison actually win the prize, or did jealous prigs and political big-wigs cheat him of his due reward? Read it yourself to find out. It's less than 200 pages.
August 17, 2018
An amazing book following the attempts to solve the longitudinal navigation problems. The author’s research covered several hundred years of partial success and many failures. Especially interesting was the English contest for solving the problem. An amazing man, John Harrison, worked tirelessly to conquer the problem. The trials of Harrison, and the jealously of others in his attempts made for a good story.. This genius is credited with producing the first marine machine to accurately calculate longitude. Then he reduced his machine to a marine watch. He made numerous chronometers and many of them may be seen in the Royal Observatory and other places in England.
Well written and documented with bibliography .
Well written and documented with bibliography .
August 22, 2019
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.
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.
November 7, 2022
This is a non-fiction book, which describes why knowing longitude is so important for sea voyages, multiple ways its correct and precise estimation was suggested and finally a life and struggle of John Harrison, the inventor of chronometer. I read it as a part of monthly reading for October 2022 at Non Fiction Book Club group.
The book starts with a calamity: in 1707, the Scillies became unmarked tombstones for two thousand of British troops because in the fog they went significantly off course and ran onto the ground. There are a few more examples of how ships lost their way and wrecked or lost crew to scurvy because they were unable to get their own coordinates. Moreover, it turns out that despite the oceans are vast, it was easy to ambush ships because most followed narrow routes to avoid confusion. So, in 1714 Parliamentary committee assembled to respond to its challenge, with such prominent experts as Sir Isaac Newton, by then a grand old man of seventy-two, and his friend Edmond Halley (one of the famous comet). It was assumed that the solution is in the stellar clocks – e.g. following moons of Jupiter or the movement of the Moon over the star sky to find out the precise time. Mechanical clocks were disregarded because back then a clock running fast/late by 15 minutes daily was assumed quite accurate. Moreover, the movement of a ship, and differences in temperature and humidity led even precise clocks to significant errors.
One of the interesting solutions was presented by William Whiston and Humphrey Ditton, mathematicians and friends. The idea was that sounds might serve as a signal to seamen. Cannon reports or other very loud noises, intentionally sounded at certain times from known reference points, could fill the oceans with audible landmarks. If enough signal boats, therefore, were stationed at strategic points from sea to sea, sailors could gauge their distance from these stationary gun ships by comparing the known time of the expected signal to the actual shipboard time when the signal was heard. Then Whiston hit on the idea of combining sound and light. If the proposed signal guns were loaded with cannon shells that shot more than a mile high into the air, and exploded there, sailors could time the delay between seeing the fireball and hearing its big bang. A well-timed bomb, exploding 6,440 feet in the air (the limit of available technology), could be seen from a distance of 100 miles. Therefore, a new breed of fleet must be dispatched and anchored at 600-mile intervals in the oceans shooting cannons in the air.
This scheme was untenable on a lot of points, but it was one of the more reasonable ones. However, there was no need for it for a self-taught English clockmaker John Harrison, a mechanical genius who devoted his life to the quest for portable precision timekeeping. He accomplished what Newton had feared was impossible: He invented a clock that would carry the true time from the home port, like an eternal flame, to any remote corner of the world. However, due to his own desire to create a perfect chronometer and to machinations of opponents, who favored a stellar clock approach, his first contraption sailed in 1736 on a trial voyage to Lisbon aboard H.M.S. Centurion but he received his prize for solving the problem only in 1773.
A great book with a lot of interesting facts and awesome storytelling.
The book starts with a calamity: in 1707, the Scillies became unmarked tombstones for two thousand of British troops because in the fog they went significantly off course and ran onto the ground. There are a few more examples of how ships lost their way and wrecked or lost crew to scurvy because they were unable to get their own coordinates. Moreover, it turns out that despite the oceans are vast, it was easy to ambush ships because most followed narrow routes to avoid confusion. So, in 1714 Parliamentary committee assembled to respond to its challenge, with such prominent experts as Sir Isaac Newton, by then a grand old man of seventy-two, and his friend Edmond Halley (one of the famous comet). It was assumed that the solution is in the stellar clocks – e.g. following moons of Jupiter or the movement of the Moon over the star sky to find out the precise time. Mechanical clocks were disregarded because back then a clock running fast/late by 15 minutes daily was assumed quite accurate. Moreover, the movement of a ship, and differences in temperature and humidity led even precise clocks to significant errors.
One of the interesting solutions was presented by William Whiston and Humphrey Ditton, mathematicians and friends. The idea was that sounds might serve as a signal to seamen. Cannon reports or other very loud noises, intentionally sounded at certain times from known reference points, could fill the oceans with audible landmarks. If enough signal boats, therefore, were stationed at strategic points from sea to sea, sailors could gauge their distance from these stationary gun ships by comparing the known time of the expected signal to the actual shipboard time when the signal was heard. Then Whiston hit on the idea of combining sound and light. If the proposed signal guns were loaded with cannon shells that shot more than a mile high into the air, and exploded there, sailors could time the delay between seeing the fireball and hearing its big bang. A well-timed bomb, exploding 6,440 feet in the air (the limit of available technology), could be seen from a distance of 100 miles. Therefore, a new breed of fleet must be dispatched and anchored at 600-mile intervals in the oceans shooting cannons in the air.
This scheme was untenable on a lot of points, but it was one of the more reasonable ones. However, there was no need for it for a self-taught English clockmaker John Harrison, a mechanical genius who devoted his life to the quest for portable precision timekeeping. He accomplished what Newton had feared was impossible: He invented a clock that would carry the true time from the home port, like an eternal flame, to any remote corner of the world. However, due to his own desire to create a perfect chronometer and to machinations of opponents, who favored a stellar clock approach, his first contraption sailed in 1736 on a trial voyage to Lisbon aboard H.M.S. Centurion but he received his prize for solving the problem only in 1773.
A great book with a lot of interesting facts and awesome storytelling.
November 14, 2022
Longitude is a fascinating story of a niche science. It was written like a thriller. Short chapters, lots of intrigue and progress in the story. I devoured this in a few days and since I am only able to devote about an hour a day at bedtime to eye-reading these days, that's quite an accomplishment. I thoroughly enjoyed this short book on science and history. Surprisingly, what stood out for me was not the brilliance and drive and meticulousness and ingenuity of the scientists and tinkerers of the time or even of Harrison drive and work ethic. It was the maddening bureaucracy associated with the discovery. All in all, a fascinating story written in a fast paced and interesting manner. A solid piece of history. Thank you goodreads Nonfiction book club; I'm glad I read it!
4+ Stars
Read on kindle
4+ Stars
Read on kindle
April 7, 2010
In Longitude, Dava Sobel chronicles the world's quest to tame time. In 1714, the English Parliament passed the longitude act. It established the Board of Longitude and offered a prize of 20,000 pounds to anyone who could find a simple and practical method for the precise determination of a ship's longitude. In particular Sobel highlights John Harrison's pursuit of the prize. She traces the arc of his career, and details the innovations of each of his subsequent entries (H1-H5) Unfortunately, even though his Chronometers repeatedly proved their worth in Sea trial after sea trial, and the watch quickly gained adherents among sea captains, Harrison was thwarted at every turn in his attempt to claim the prize. Jealous rivals on the board used their influence to change the rules of the contest multiple times. His relations with the board became so acrimonious that eventually his friends went over the board's head and appealed directly to the King himself. George III asked that a special act of Parliament be passed and Harrison finally received his prize.
Despite it's brevity, Longitude is an incredibly engaging and educational book. Sobel writes in a way that makes the science and math accessible to the general reader.
If you're interested in this subject I'd also recommend the 2000 A&E movie, which was based on this book.
Despite it's brevity, Longitude is an incredibly engaging and educational book. Sobel writes in a way that makes the science and math accessible to the general reader.
If you're interested in this subject I'd also recommend the 2000 A&E movie, which was based on this book.
Read
December 21, 2016Interesting story. Reasonably written. Possibly a model for a certain kind of non-fiction book, the type with very long sub-titles that are meant to cast light on a very short main title, the whole presumably being the original elevator pitch that the author made to the publisher. This one is all about the late 18th century watch maker, John Harrison, who builds a series of highly accurate watches in an attempt to win a prize for a device to be able to establish longitude at sea. Nice, does what it says on the tin type book. In the tradition of praising people whose work made it possible to do things a little better - in this case navigate across seas using a map.
November 18, 2015
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.
John Harrison should get his due. Especially within trade ships of earlier periods his work probably saved countless lives. Unsung hero.
September 21, 2017
La Historia está llena de pequeños descubrimientos capaces de cambiar el mundo. Aunque debería decir pequeños vistos desde nuestros días. Este es el caso de la longitud, es decir, esas líneas imaginarias que trazan nuestro planeta desde los polos, dividiéndolo en veinticuatro partes iguales. La longitud era fundamental en tierra firme para trazar mapas lo más exactos posibles, pero sobre todo era esencial para la navegación. El mundo era un gran desconocido cuyos horizontes estaban todavía por descubrir y el único medio para hacerlo era en barco, surcando esos océanos y mares ignotos donde cualquier error de cálculo podía suponer perderse en su inmensidad y morir con seguridad, ya sea por la escasez de agua potable y alimentos como por escorbuto. Un barco podía pensar que estaba arribando a su destino cuando quizás era todo lo contrario, o podía colisionar con elementos desconocidos provocando su hundimiento.
Hay que pensar en la longitud como un elemento asociado al tiempo. Si tenemos en cuenta que circunvalar la Tierra supone 360º, que se dividen en 24 meridianos de longitud, obtenemos una separación entre ellos de 15º, calculándose cada grado en minutos. Por lo tanto es fundamental saber en todo momento el tiempo real tanto en el barco como en el lugar desde el que se ha partido o el de destino. Parece simple, con un simple reloj arreglado. Pero no es tan fácil como parece, porque la temperatura y la presión atmosférica afectan mucho la maquinaria de los relojes, adelantándolos o retrasándolos o simplemente parándolos. El capitán pensaba que estaba a X minutos de su destino y se encontraba con que el tiempo pasaba y no arribaban a lugar alguno. Y aquí entraban en juego los partidarios de los relojes y los que preferían guiarse por el mapa estelar, mirando el cielo.
Era tan importante para los países encontrar una solución al problema de la longitud, que les hacía perder barcos, mercancías, hombres y dinero, que decidieron poner una recompensa a aquél que diese una solución lo más exacta posible. El gobierno inglés llegó a ofrecer 20.000 libras, el equivalente a varios millones en la actualidad, estableciéndose así el Decreto de la Longitud de 1714.
Muchos científicos de renombre hicieron frente al reto pero sólo uno lo consiguió, John Harrison. Esta es su historia, la de él y la de otros tantos que quisieron encontrar una solución al problema. Galileo, Newton, Huygens y un largo etcétera no fueron capaces que dar con la clave. Tuvo que llegar Harrison, un desconocido, un autodidacta aficionado a los relojes, carpintero de profesión para poner fin al problema. Y no lo tuvo nada fácil, porque además de intentar construir sus máquinas de precisión, tuvo que hacer frente a la oposición de los astrónomos, empeñados en que su método era el mejor y más adecuado.
Dava Sobel, periodista científica, nos ofrece un relato claro y apasionante de un descubrimiento que cambió nuestra Historia para siempre. Parece mentira que algo para lo que actualmente son necesarios dos simples relojes de pulsera, trajese de cabeza a medio mundo.
Hay que pensar en la longitud como un elemento asociado al tiempo. Si tenemos en cuenta que circunvalar la Tierra supone 360º, que se dividen en 24 meridianos de longitud, obtenemos una separación entre ellos de 15º, calculándose cada grado en minutos. Por lo tanto es fundamental saber en todo momento el tiempo real tanto en el barco como en el lugar desde el que se ha partido o el de destino. Parece simple, con un simple reloj arreglado. Pero no es tan fácil como parece, porque la temperatura y la presión atmosférica afectan mucho la maquinaria de los relojes, adelantándolos o retrasándolos o simplemente parándolos. El capitán pensaba que estaba a X minutos de su destino y se encontraba con que el tiempo pasaba y no arribaban a lugar alguno. Y aquí entraban en juego los partidarios de los relojes y los que preferían guiarse por el mapa estelar, mirando el cielo.
Era tan importante para los países encontrar una solución al problema de la longitud, que les hacía perder barcos, mercancías, hombres y dinero, que decidieron poner una recompensa a aquél que diese una solución lo más exacta posible. El gobierno inglés llegó a ofrecer 20.000 libras, el equivalente a varios millones en la actualidad, estableciéndose así el Decreto de la Longitud de 1714.
Muchos científicos de renombre hicieron frente al reto pero sólo uno lo consiguió, John Harrison. Esta es su historia, la de él y la de otros tantos que quisieron encontrar una solución al problema. Galileo, Newton, Huygens y un largo etcétera no fueron capaces que dar con la clave. Tuvo que llegar Harrison, un desconocido, un autodidacta aficionado a los relojes, carpintero de profesión para poner fin al problema. Y no lo tuvo nada fácil, porque además de intentar construir sus máquinas de precisión, tuvo que hacer frente a la oposición de los astrónomos, empeñados en que su método era el mejor y más adecuado.
Dava Sobel, periodista científica, nos ofrece un relato claro y apasionante de un descubrimiento que cambió nuestra Historia para siempre. Parece mentira que algo para lo que actualmente son necesarios dos simples relojes de pulsera, trajese de cabeza a medio mundo.
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