I remember seeing parts of the TV movie and liking it, so when the book came up in a Kindle sale, I picked it up. I can see why it was so popular as Sobel has a clear, concise style that is informative, yet not bogged down in minutiae. It is interesting to note not only the knowledge gained in the attempt, but also the way that knowledge is judged and disseminated. Two competing paradigms for computing longitude arose, one (favored by the astronomers), depended on the distance between the moon and sun and moon and stars, the other relied on an accurate seagoing clock (chronometer). To me, the most interesting part of the story was in how far each was willing to go to prove their method was the best, with the politics of science being more important than the science itself. A quick and enjoyable read - I may have to track down the TV movie now to watch it in full.

A matter of time. The earth’s latitude was established long before the longitude, with the former fixed by nature’s physical law and relatively consistent compared to the latter, which was made complicated by a shifting time factor. Without benefit of the longitude, thousands of seafarers in the past had risked their lives on luck and the captain’s judgement to sail the high seas. After almost four centuries of questing for a viable solution, the maritime community finally endorsed the first reliable chronometer from an erstwhile unknown English clockmaker by the name of John Harrison.

Still, due recognition for Harrison was a long time coming. Until 1773, both inventor and inventions - the four iterations were designated H1, H2, H3, and H4 - were met with disdainful opposition from the scientific elite, largely astronomers, who posited the celestial clock, not the mechanical one, as a true gauge of longitude. Harrison’s ingenuity suffered decades of academic skepticism, award sabotage, back-biting, formidable competition, financial challenges and Harrison’s own sense of perfectionism, as recounted in Dava Sobel’s Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of his Time. At times vivid and inspiring, Sobel’s telling breathed much-needed color into an otherwise dry historical event and Harrison’s even dryer personality.

Longitude barely qualified as a biography, as Harrison’s personal life was little known. He seemed to be an extraordinarily reserved person, who had taught himself clock-making without the benefit of apprenticeship or a formal education. In the eyes of most readers, the very mystery of the genius Harrison made him an intriguing historical figure. Most definitely in the eyes of this reader, Harrison’s remarkable achievements made me cheer for an underdog who succeeded against all odds to develop an accurate sea clock for measuring longitude, which also initiated a boom industry in marine timekeeping.

Longitude has enough facts loaded on for those needing details, but dramatized enough to pique my interest. It is the kind of book one might buy from the gift store after a visit to the maritime museum, or for someone into horology. Neither applied to me; the subject, book length (< 200 pages, Kindle) and my mood merely converged favorably. Someday, I hope to see Harrison’s original marine chronometers on display at the Royal Observatory at Greenwich, London. The images here will serve as reference for the time being.

De esas historias que nos hubiera encantado que nos la contaran en la escuela.
Sin duda, Zweig debió incluir a John Harrison en sus Momentos estelares de la humanidad, por todo lo que representó el problema de la longitud por tantos siglos. No me explico como Zweig no lo metió, quizá por falta de tiempo, en fin...
Un libro de divulgación ameno, que nos lleva de la mano a comprender este acertijo que dio tantos dolores a los navegantes, hasta que un humilde relojero-carpintero trajo la solución con un artefacto que parecía venir de otro mundo. Halley, Newton y otros personajes menos amables que fungen como los típicos villanos-antihéroes gravitan alrededor de este maravilloso momento estelar de la mente del ser humano.

An interesting read about the competition between astronomers and horologist to discover an accurate means of helping sailors at sea find a precise reference to their longitudinal location without which many ships were lost at sea or crashed into rocky coastlines miles off course. A somewhat technical read with numerous astronomical references so brushing up on lunar patterns and astronomical terminologies may help in understanding some of the passages. It’s a short book, but it took a bit to look up references and theories of famous mathematicians, astronomers, and horologist of the 16th and earlier centuries.

The book contains a lot of interesting information, and I am glad I read it. I enjoyed the first half. At some point, though, I got tired of reading about how unfairly Harrison was treated in his efforts to claim the longitude prize. The last part of the book seemed to drag, for me.

Longitude from Dava Sobel is a fascinating account of how a virtually unknown watchmaker named John Harrison conquered one of the oldest and thorniest problems surrounding the ocean voyages - the problem of accurately measuring longitude -, which stumped even the best of scientific minds for centuries.

A fascinating problem

It was Ptolemy in ‘Geographia’, written in the 2nd century, who contributed the concept of a co-ordinate system based on the imaginary lines of latitude and longitude, for accurately plotting any spot on the surface of earth. With these imaginary lines he bought a new light in to the maritime explorations and map-making methods of his time. The sailors while at the ocean found it pretty straightforward to find their current latitude - which is drawn parallel to each other while girdling the globe – by measuring the height of the sun or any known celestial bodies.

But accurately measuring their current longitude was an entirely different case, as the longitudinal lines loop from the North Pole to the South Pole and back again in great circles, which converge at the ends of the earth. Since it is an angular measurement, which is based on time, the sailors had to have access to two different times - the current time on-board the vessel and the time at a known and pre-selected longitudinal location – at the same instance for calculating the hour differences to work out the geographical separation and the longitude. From a modern viewpoint with our easy-to-carry accurate time-telling devices and instant communication this problem, which a sailor faced in finding the exact time at two different locations, may feel far-fetched. But a sailor in the middle of an ocean pre-dating 18th century only had limited resources in the form of either a pendulum driven clock which was not at all reliable – as the factors like gravity, motion of the vessel, temperature and atmospheric pressure affected the pendulum and there by the time – or by comparing positions of moon or planets like Mars with their anticipatory positions in working out the longitudinal values; both these methods were crude with a high level of inaccuracy.

Since the days of Ptolemy, legendary scientific and exploratory minds like Amarigo Vespucci, Sir Issac Newton and Galileo Galilei did a lot of research into this matter but it took sixteen more centuries for mankind to finally invent a reliable solution for this problem.

A tragedy & the declaration of a prize money

In 1707, a British fleet of vessels under Admiral Sir Clowdesley Shovell met with a tragic disaster as the result of miscalculations in their whereabouts leading to the sinking of four warships with a death toll of more than 1600 mariners. This disaster and huge protest from the merchants and seamen resulted in the formation of a parliamentary committee for finding a practical solution for the longitude problem. This was followed by the 1714 ‘Longitude Act’ by the parliament, which promised a prize money of £ 20,000 for a suitable solution. Dava Sobel covers this formation of the committee and the announcement of the reward in detail.

Sir Issac Newton, who was consulted by the committee, at first suggested the idea of a ‘watch’ for tackling the longitude problem.

“One method is by a Watch to keep time exactly. But, by reason of the motion of the Ship, the Variation of Heat and Cold, Wet and Dry, and the Difference of Gravity in different Latitudes, such a watch hath not yet been made.”

But he believed that such a watch with too many technical challenges was not going to be a reality and was aligned more towards finding a solution for the longitude problem in the realms of astronomy.

“A good watch may serve to keep a reckoning at Sea for some days and to know the time of a celestial Observation; and for this end a good Jewel watch may suffice till a better sort of Watch can be found out. But when the Longitude at sea is once lost, it cannot be found again by any watch.”

Newton died in 1727, and therefore did not live to see the predecessor of the modern day chronometers become a reality. At the same time another less known figure; a skilled watchmaker from Lincolnshire named John Harrison who was stimulated by the scientific and the monetary factors surrounding this riddle decided to find a solution of his own. Possessed with a brilliant mind he succeeded initially in creating a prototype and then further versions of perfect working models of the world’s first marine-chronometers thereby revolutionizing the ocean travels. His handmade sea-clocks - which are elaborate pieces of engineering marvels and still in display in working condition at the Royal Observatory, Greenwich, England - gave the world the first reliable method for measuring the longitude.

Dava Sobel records the background and each step of this pioneering invention in an easy to read form, by guiding the reader through a tumultuous story of the sheer determination and relentless pursuit for perfection from a self made man and the obstructions, unkempt promises and villainy he had to face from some of his jealous contemporaries. This concise and engaging chronicle of an innovative engineering deed covers a lot of details on the history, science and politics, which led to this invention and is a recommended read for anyone who is interested in maritime history and science.

Since I read an updated fully illustrated edition of ‘Longitude’, which was published later, the book was a treasure trove with a large selection of rare photographs - including Harrison's sea-clocks, documents of declarations, letters, scientific articles, maps and diagrams which added greatly to the value of the volume. The illustrated edition is highly recommended.

The key to determining longitude is knowing what time it is compared to a standard time. Not knowing one's longitude was one of the biggest perils to ships for most of history. Astronomers felt that they would have the answer, measuring the orbit of the moon as it traverses the sky. This theory caused the building of observatories and mapping of the stars. However, what do you do when you can't observe the heavens and the seas are choppy.
Meausuring time was not considered to be a promising solution. Timepieces of the age were just not that accurate. Plus, metals in the salt air corroded, they needed lubrication, and both the metals and lubricants reacted differently in heat and humidity.

Enter one John Harrison, an unschooled woodmaker who invented a clock that used wooden gears and didn't require lubrication. Unfortunately, his ability to express himself was abysmal. That, and the fact that the scientific community of the time favored astronomers caused his theory to languish for decades before being recognized. Fascinating story for the science nerd in me!

3.5 stars

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.

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.
n  LONGITUDE, THE TRUE STORY OF A LONE GENIUS WHO SOLVED THE GREATEST SCIENTIFIC PROBLEM OF HIS TIME,n 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.
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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.

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.

The title of the book sounds boring but it's really a super interesting and quick read, featuring shipwrecks and pirates, neck and neck competition, greed, corruption and progress. I love books about innovations that revolutionized life in their time but that we today take for granted. This book increased my sense of awe for the Lords glory in His creation especially the parts about astronomy (even though some of it went over my head).