Some of this was interesting and some of it not so much. It was ok. 3 stars even

An excellent piece of literary work. Smart, concise, digestable, organized and fun. A must read for all, especially scientific non-fiction lovers.

n  Time is to clock as mind is to brain. The clock or watch somehow contains the time. And yet time refuses to be bottled up like a genie stuffed in a lamp. Whether it flows as sand or turns on wheels within wheels, time escapes irretrievably, while we watch.n

If you read Bryson's A Short History of Nearly Everything, and are eager for more, Longitude will be right up your alley. (I've read so many "history of science" type books, I'm thinking I should create a GR shelf just for them.) A lot of the stars of History make an appearance, including Galileo, Cassini, Newton, Huygens, Hooke, Halley, and Euler.

I read this as a biography of John Harrison, watch-maker and longitude measurer, but that doesn't start until chapter 7, a fulll 33% into the book.

The most accurate description is that this is a micro history of the development of time-keeping instruments that allowed seamen to measure longitude accurately. If that sounds kind of dry, well, it is. This is interesting, well-written, readable, and brief, but it's not exactly scintillating. This tale is a fine example of how beauraucratic red tape is no modern invention, if anything it was even worse back in the early 1700s!

I learned one shocking factoid: keeping track of your location on the ocean was a hanging offense!

n  ...on that foggy night of October 22, 1707, the Scillies became unmarked tombstones for almost two thousand of Sir Clowdisley’s troops.

The flagship, the Association, struck first. She sank within minutes, drowning all hands. Before the rest of the vessels could react to the obvious danger, two more ships, the Eagle and the Romney, pricked themselves on the rocks and went down like stones. In all, four of the five warships were lost.

Only two men washed ashore alive. One of them was Sir Clowdisley himself, who may have watched the fifty-seven years of his life flash before his eyes as the waves carried him home. Certainly he had time to reflect on the events of the previous twenty-four hours, when he made what must have been the worst mistake in judgment of his naval career. He had been approached by a sailor, a member of the Association’s crew, who claimed to have kept his own reckoning of the fleet’s location during the whole cloudy passage. Such subversive navigation by an inferior was forbidden in the Royal Navy, as the unnamed seaman well knew. However, the danger appeared so enormous, by his calculations, that he risked his neck to make his concerns known to the officers. Admiral Shovell had the man hanged for mutiny on the spot.n

Interesting 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.

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.

"What are you reading?" "A book about marine navigation between the 16th and 18th century!" The girlfriend was not impressed.. But in all honesty, this is a page-turner. How did sea vessels navigate the great oceans before the modern-day where we simply look at a magical map with a dot showing our current location? Measuring latitude (north-south co-ordinate) is easy and has been well-known since at least the Age of Discovery: measure the angle from the horizon to the North Star, Polaris. The angle is equal to your north-south (latitude) position.

Great, now how do we know how far east-west (longitude) we are? You didn't.. until the mid 1700s. The best you could do to figure out roughly where you were was to periodically throw a log in the water to figure out how fast you were going. Then, look at your compass and log both in your logbook. Imagine doing that accurately when waves are 10 meters high and the weather is terrible. If you do something slightly wrong or don't have the ability to do it for a while, you're good old fashioned lost at sea. This primitive navigation meant that the same trade routes were plied, making piracy easy in the Atlantic, and whalers stumbling upon each other. The biggest sea-going nations at the time: the Spanish, Portuguese, British, and the Dutch were all losing ships left and right: shipwrecks, pirating, and others that just never returned.

The root cause: the inability to figure out where you were. The inability to determine your longitude. Prizes by the nations mentioned earlier went out at the equivalent of a million dollars today to find a reliable way on ships to measure longitude within half a degree of accuracy. This was one of the greatest scientific problems at the time with Newton, Galileo, and others giving it a shot. The first method that worked was Galileo's method of using Jupiter's moons (this was impossible at sea though, because even your heartbeat would throw the telescope off enough to miss the moons -- meant it was OK at land, but not at sea). When Ole Rømer looked into this method to determine longitude, he discovered discrepancies. He finally explained this by realizing that light did not instantly get from A to B, but that light like sound has a speed. Nifty by-product of solving one of the most important problems of his time.

Finally, in the mid 1700s a method was published that relied on moon's movement. You'd measure the angle from the moon to some known celestial body and consult a table published annually to convert the angle into a longitude. This could take up to four hours (!). However, there was another way that no-one thought possible: using time. If you knew the time in, say, Greenwich, England and you knew your time where you are currently -- you could figure out your longitude. Each hour difference is equal to 360/24 = 15 degrees longitude. So, say you're in tumultuous waters off the Azores and would be delighted to know where you are. At high noon you're measuring your latitude, as per usual. Now, imagine you also had a clock synced to Greenwich and you noted the time of the clock at high noon too. The clock shows 14:13:00 when the sun is at the highest altitude where you are. Your longitude then comes out to ((13.00/60) + 2) * 15 = 33.25. To find the latitude, you take out your good ol' sextant and measure the angle to the sun at 37.0 degrees, so your coordinates are (37.0, 33.25). Ta-da! You're now ready to be sent on an Age of Discovery era ship with just a compass, sextant, and pocket watch.

Problem was... no-one could create a sea-faring clock that was accurate enough. To measure within a half degree accuracy (~40km), which was required by the prize, you couldn't drift more than 3 seconds a day. Most clocks of the 1700s drifted by 5-15 minutes a day! Factor in the humidity, temperature, and vibrations at sea -- you wouldn't get even close. However, John Harrison persevered for something like 50 years finally creating a clock (through much drama with the longitude prize board) that was accurate enough. For example, one of the big problems was that some metals would shrink and others enlarge based on temperature. He'd find materials that complemented each other to keep time syncing, if one shrank, another would enlarge in harmony. The clock worked, but was only available to few as it was expensive and took years to create each one. James Cook had one, and found it invaluable to chart out the Pacific. Over the next 60 years other clock-makers made it cheaper and cheaper by decade. By the 1850s, almost everyone was using a chronometer derived from Harrison's and lunar tables went into the pages of history.

I really enjoyed this book. Great science tale of solving a massive problem, being biased toward a particular type of solution (astronomy), discovering useful other things along the way (speed of light), and perseverance.

The book, unfortunately, can't get the 5th star. The reason comes down to how there's not a single picture in the book, which makes the concepts hard to understand. I had to read up on them independently of the book to understand them properly. Dana seems to skate over the significance of the lunar distance tables that predated Harrison's clocks, which is a shame, because they were a revolution themselves despite their complexity.

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.

Quick, focused history books are underrated, especially when they're as well-written as this one. The subtitle of "The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time" sounds hyperbolic, but it's basically true. Sobel's account of how unknown English clockmaker John Harrison solved the longitude problem - how can sailors tell their position at sea in a quick, accurate, and reliable way in order to avoid sinking or mistaking Caribbean islands for India? - takes an underappreciated scientific issue and explains why it's important, why it was so difficult to solve, who the key players were, and why it matters today. While she doesn't wander down every single potential historical avenue or wring all of the scientific/military/political contextual details out, she's able to give the reader plenty of background for further digging, in case you want more details on the vagaries of star-sighting or constructing astronomical tables, the rivalry between Britain and France, or why exactly Nevil Maskelyne was such a jerk to his fellow astronomers and scientists.

Plus as a bonus it gives you more to ponder on how best to systematically promote scientific research: the debate over the prize system vs investing more in public universities vs offering R&D tax credits to private companies can seem arcane, but the specific example of a life-and-death situation like the longitude problem makes the tradeoffs of each unusually clear. Scientific research offers a great window into society's priorities, and Sobel's book is an excellent look at an often-overlooked example of progress at its most unexpected. Few of us mostly land-locked folks will ever need to determine the nearest meridian line from a ship at sea in a storm, but it's always worth remembering how we've benefitted from humble experimenters like Harrison, and thinking of ways to encourage his spiritual successors.

"He wrested the world's whereabouts from the stars, and locked the secret in a pocket watch."

Every year I teach my world geography students about latitude and longitude and how they aid navigators around the globe, but what I haven't been teaching is what I didn't know until I read this book. While latitude is a straightforward series of concentric parallel circles, the lines and measurement of longitude eluded astronomers and cartographers for centuries.

Learning about this problem and its eventual solution, you can't help but be impressed. This is an innovation that, in its own way, is as important as the development of penicillin or the phonetic alphabet. That the work of one humble man, clockmaker John Harrison, produced a solution to this problem really is incredible.

A bit dry at times...

I don’t think I really thought about it until like the first chapter of this book, but longitude really is just a man made concept. There’s nothing special about greenwich that necessitates the prime meridian running through it. This book was interesting to read. It was short and sweet, all the chapters were bite sized, and it taught me something i probably never would have even thought to learn about.

This dude john harrison took some massive Ls in his life tho ngl. it took him like half of his adult life to make four clocks and then the other half of his adult life to get paid for it, and all the time this dickhead nevil was tryna kill his vibe bc nevil was super into astrology. fuck nevil. i feel like everybody has a nevil in their life. honestly i’ve never thought too fondly of british folks or ever really felt a desire to go visit england. however, now i want to go just to check out john’s clocks.

i think it’s probably a little too far fetched to say his clocks led to the rise of the british empire, but i could see why someone would think that. he basically single handedly made it easy to figure out where you were in the ocean while sailing with a useful level of accuracy and precision. ostensibly, this led to better maritime trade and naval prowess for the brit’s.

it’s cool how technology progresses exponentially. john harrison worked for 40 years to make a mechanical clock that he could use to tell position within ten nautical miles, and now i can use a ten dollar flip phone to triangulate my position to like the nearest 100 feet. makes u appreciate the lil things fr.

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.