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.

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not the best quality, TBH!

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.

I had gotten glowing recommendations for this book, but it left me disappointed. For a book about the history of technology, there's precious little technology in the book: Harrison's marine chronometers are repeatedly praised, but there's little in the way of description of how they work, or why they represented such an advance in clockmaking. Sobel will frequently describe a piece of clockwork, then say that Harrison didn't or couldn't use it in his marine timepieces, but without ever saying what Harrison did instead. H4 and H5, the miniaturized sea watches, are given particularly short shrift, with almost zero description of how they work. Sobel describes what they look like, their external appearance, but opts not to go deeper, beyond the surface, and explain their workings.

My other disappointment is that there are no pictures or illustration of any of the clocks or even clock mechanisms to support the text. Early in the book, Sobel tries in vain to describe what a grasshopper escapement looks like, but it seems like she gives up on this by the end of the book, and simply references clock pieces without attempting any description at all.

"Longitude" is a narrative, not, as Sobel admits/claims in the acknowledgements, "a scholarly study." The story is certainly engaging, and well told, but Sobel sometimes lets the narrative arc of the Harrisons' shabby treatment by the Longitude Board overwhelm common sense. Quoting from Chapter 13,

"""
Seeking proof positive of H-4's true reproducibility, the board also hired the watchmaker Larcum Kendall to attempt an exact copy. These efforts evince the board's ferocious pursuit of the spirit of the law as they interpreted it, for the original Longitude Act never stipulated that the "Practicable and Useful" method must be copied by its inventor or anyone else.
"""

A marine chronometer that cannot be reproduced at scale is not "Practicable and Useful". Citing this as evidence of John Harrison's misuse by the Board is letting the story get ahead of the facts.

Overall, I found "Longitude" a good popular overview of this piece history, but it left me wanting more detail about the technology being chronicled. Have Google handy when reading it so you can look up terms like "backstaff", "reflecting quadrant", "winding rods", "grasshopper escapement", etc, as you go.

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. Essentially the Europeans were looking for a way of determining their geographic location while at sea. They offered prize money for the discovery. Once Harrison fulfilled their requirements, they changed the rules of the game. Constantly. Additionally, the judges for the contest had hidden agendas, competing theories that were well funded, and a stake in the failure of some of the ideas in the competition. As such it was severely rigged and handicapped for certain ideas and thoughts. The good news was that even back in the 1600's Europeans were working across borders to address this problem. Interesting that the finest minds in England, Spain, Italy, Portugal, Spain etc were all searching for an answer and were working together to address it. The bad news, greed, ego and envy ruled created obstacles to a solution. Basically, Harrison's innate goodness and a few scientific benefactors are the reason that chronometers were invented during that time. 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

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A friend of mine told me about this book - I never knew that longitude was beyond navigators' collective grasp as late as it was, or that it was monumentally harder to determine than latitude. It's fascinating.

Besides the central story of how a self-taught clock-maker, John Harrison, spent his lifetime perfecting a clock accurate and hardy enough to remember Greenwich time on long voyages through various temperatures, the rolling of the sea, and different humidities and barometric pressures, the book explains other ways to determine longitude using the skies (if you can get an accurate reading and the data exists to predict where the moon should be with respect to the sun for 3 hour periods for the length of your voyage, and it's not cloudy).

Navigators also were able to determine longitude, theoretically, by observing the moons of Jupiter, whose orbits were easier to predict, but were much harder to see on a rocking boat.

So Galileo, who discovered the Jovian moons, gets a couple of cool points here (like he needed any more). In fact, the Jupiter moon method (and every method is about figuring out what time it is in Greenwich right now - if we know when a person in Greenwich would see what we just saw - for example, a moon of Jupiter going behind the planet - we know how far ahead or behind Greenwich we are), while so impractical on ships that navigators on ships had to wait for a good clock (although that took 150 years after the invention of Galileo's method), was great on land, and it's the cause of maps suddenly looking accurate and not grossly distorted east/west-wise just after 1600.

Isaac Newton also makes a special appearance (you know, predicting our moon's orbit well).

Oh yeah - you also have to see the wonderful clocks this guy made (there are color plates in some editions)- they're steampunk perfection.

Anyway, I hope I've conveyed the enthusiasm I feel for this short, but just-right-length, science history.

Harrison stood alone against the vested navigational interests of the scientific establishment. He became entrenched in this position by virtue of his own high standards and the high degree of skepticism expressed by his opponents.

Fascinating but too much fluff. Should have left it as the magazine article it originally was. I’ve learned to be wary of books with paragraph-length subtitles. This one was a unnecessary as most.

A novel antifriction device that Harrison developed for H-3 also survives to the present day—in the caged ball bearings that smooth the operation of almost every machine with moving parts now in use.

John Harrison was one of those lonely geniuses who labors against the scientific (and wrong) tide of his day. All the great and worthy members of the Board of Longitude knew he was wrong; some actively sabotaged his efforts. Harrison never got the credit (or credits) he was due, but the world of navigation (and beyond) benefited by his monomania.

With his marine clocks, John Harrison tested the waters of space-time. He succeeded, against all odds, in using the fourth—temporal—dimension to link points on the three-dimensional globe. He wrested the world’s whereabouts from the stars, and locked the secret in a pocket watch.

An excellent non-fiction account of a watch maker. A man who would not give up despite vainglorious individuals who attempted to thwart his every step to test and prove his chronometer could accurately function on board a ship in the days of sail. Why is it important to have accurate time pieces in the middle of oceans? Longitude determination. Finding latitude was known. Using a compass was a given. Without longitude a sailor would find his ship wrecked on rocks in a moments notice or be so far off course as to have no chance to find drinking water or replenish stores in time to spare the crew disease or death.

Well done, Dava Sobel.

In my 4-star review of the original Longitude, I said that "my sole complaint is that the book would have really benefited from illustrations" - and now here it is! So I really have to give this the full 5-stars based on that alone.

However, THAT SAID...maybe 180 illustrations (Sobel's total as noted in the introduction; I didn't count them) is a few too many? There are pictures on nearly every page, and while it makes for a much more enjoyable overall experience, one quickly notes that the pictures all fall into one of five categories: old-timey maps; near-identical paintings of 17th-18th century scientists; only-slightly-less identical covers of early scientific pamphlets*; paintings of ships at sea (cool); and finally, drawings and photos of the various clocks and other devices invented along the way (very cool). Of course, I don't know what ELSE you could have pictures of, (although inexcusably, the one thing that isn't shown is Galileo's brilliantly dorky "celatone!**).

My original review covers the text itself - although turns out I had totally forgotten about the delightful "powder of sympathy," a bizarre magical powder that could purportedly heal instantaneously over great distances. Long story short, the plan would ultimately have called for wounded dogs to go out with all ships, who would then yelp at a fixed time every day when someone back in England dipped one of their bandage in the magic powder. Of course, on longer voyages the dogs would have had to be re-injured at regular intervals (remember, this was pre-PETA) - but thankfully, this technique was never tested.

Anyway - absolutely great book that is even superior to the wonderful original. Only wish it was better known, as the original Longitude has some 48,ooo GR ratings, while this illustrated update has only 260!

* Typical example: "THE LONGITUDES EXAMIN'D, Beginning with a fhort Epiftle to the Longitudinarians, AND Ending with the Defcription of a fmart, pretty MACHINE Of my Own, Which I am (almoft) fure will do for the LONGITUDE, and procure me the Twenty Thoufand Pounds."

** Would love to include a photo of the celetone here, but despite seeing other people do so in their reviews, I still haven't been able to figure out how to do so. But you can one see for yourself here: https://en.wikipedia.org/wiki/Celaton...

I 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.

A short and entertaining history of the development of a sea-worthy clock which could be used to calculate longitude. Well written, with a story-like narrative, and lots of political intrigue. Yet another book that shows how science can be subverted by ideology, and how wealth and privilege can allow someone to remain in a position of power despite a clear conflict of interest. I would have liked a bit more science, and more detail on the technological innovations that Harrison and other accomplished, but this book was more focused on the history. Still a worthwhile read.

"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.