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VINE VOICEon 28 December 2016
This is an engagingly written non-specialist account of the hunt during the 18th century for an accurate way to measure longitude, and thus more accurately track sea voyages between west and east. While latitude had been understood since antiquity and has an absolute meaning relative to the north and south poles, longitude is entirely relative and can in principle be measured from any artificial line connecting the poles. The hunt was turned into a race by the British Parliament's Longitude Act of 1714, establishing a Board to consider proposals to measure longitude accurately, with a top prize of £20,000 for anyone able to measure it to within half a degree of accuracy. Why such a high profile prize? Ignorance of longitude was very costly, including costing the lives of many seamen, including two thousand in one incident in 1707 when four warships ran aground off the Scilly Isles. Ignorance also cost economically as it meant marine trade routes had to follow a very narrow safe path which restricted commercial growth.

The early years of the hunt for a solution were dominated on the one hand by greats such as Isaac Newton, John Flamsteed and Edmond Halley, and on the other hand, by numerous lesser players proposing theoretically ingenious but flawed and wildly impractical solutions, involving for example, anchoring fleets of ships at regular intervals across the ocean, which would fire signals at regular intervals so that passing vessels could measure their distance from land to east or west. Later on the race was a battle between the astronomers and the engineers, between those who saw the solution in the movements of the stars and planets and those who saw technology as the answer. In truth, both were partly right. The movements of celestial bodies had a part to play, but had in practice to be complemented by a mechanical device that could provide a practical and quick solution to the long standing problem. Step forward one of the unsung heroes of science and technology - John Harrison, master clockmaker, who rose from obscure and humble origins in Lincolnshire to become one of the great innovators of all time. He produced four progressively simpler and smaller timepieces, the last of which H-4 was the prototype for slightly later, smaller mass produced timepieces that in the hands of ships' captains were a contributory factor in the expansion of British sea power in the late 18th and early 19th centuries. His arch rival was the Rev Nevil Maskelyne, Astronomer Royal, a man not above changing the rules of the race to suit the astronomers vs. the mechanics. While Maskelyne behaved shabbily, he did make his own considerable contributions to lunar observations as part of the solution, and was responsible for establishing Greenwich as the prime meridian from which longitude would be measured across the world thereafter. But Harrison is the hero of this story, a pioneer who, in the author's words, "With his marine clocks, ... 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."

A good read, though some footnotes would be good and, even more so, a few diagrams and illustrations.
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TOP 1000 REVIEWERon 23 February 2014
Unitil the mid 1700s the world lacked the science to know where ships were at sea - with often tragic results. To help resolve this problem a prize of £20,000 was established to be awarded when a proven solution was established.

Two main camps developed - the lunar distance method, which required numerous measurements of the sky and a clear day, and the method using clocks. The human drama of the battle between these camps, and of the genius of John Harrison, working largely alone to create a workable and accurate solution through the creation and testing of what is now known as a chronometer was for me the most enjoyable aspect of this short but facinating book.

Add to that that this is also a brief history of navigation, astronomy and clockmaking and there was a lot here for me to learn - and what an enjyable way to learn it. I have learned much more about clocks and watches that i ever thought i would want to - but I am glad I did in the company of this great little book.

As others have pointed out some illustrations would have been helpful, but i understand this has been rectified in later editions
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on 4 December 2017
As Sobel himself says, it is written as an informative not an academic book and it succeeds well. It covers the trials and tribulations of Harrison and the rivalry between the astronomers and horologists in the race for the longitude prize. How the academic astronomers, kept trying to do down Harrison, who in the true British fashion of the gifted amateur (being neither a trained watch maker nor scientist but a carpenter) won in the end through persistence and hard graft. The inventor of the first true chronometer should be better known.
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on 15 July 2014
I have just finished reading this authoritative, extremely well-researched yet concise account of one of Man's greatest achievements. Without the achievement of The 'Harrisons', we would not know where we stand on this planet as a human race - literally; we would not have had the chance to explore our surroundings and earthly environment systematically extending to space, outer space and the stars. 'Longitude' is a book that's worth reading and re-reading to learn how ideas can be turned into fact. Ultimately, it also proves the point that 'Genius (or success - my addition) is one per cent inspiration and ninety-nine per cent perspiration' - as Edison told us not so long ago.
Peter Borg-Bartolo
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on 15 June 2017
An interesting but not particularly captivating story of the struggle to find how to measure longitude. The book would have benefited from some diagrams and pictures to illustrate the various clocks featured.
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on 13 October 2013
I watched the C4 dramatization of this book some years ago but had never read it. I have now and it's a real gem - utterly fascinating. My only regret is that there are not really any illustrations worth having in this edition, but that is a minor point.
In opposition to Harrison the Rev Maskelyne appears a nasty and small-minded person, which given his work wandering up and down Scheahallion (Perthshire) to define the pull of gravity makes the history the more readable.
The events following -the work of Dent and particularly Gould's restoration of the clocks are of as great an interest as the story of Harrison's struggle.
An excellent book which ought to be taught in all schools. Would recommend.
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on 11 September 2017
A story of an idea clashing with science and politics. The idea triumphed in the end, but a lack of appreciation of science and politics by the entrepreneur led to much delay. Nicely told.
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on 8 January 2018
This book should be required reading for all schools. It reminds us all that technology which we take for granted in the last 30 years was not always available. The people who strove to understand Longitude were amazing pioneers, and this book explains why. Well researched and refreshingly written, it is a must read book!
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on 24 February 2014
I do not doubt the Harrison's importance in the history of marine chronometer, the whole of XIX century the Navy and the other armadas have been finding the longitude with Joseph de Mendoça y Rios tables.

Dava Sobel takes the micky of Maskelyne an others astronomers like (Hayley, Newton, etc..) who defended the moon distances system when she pretends being an "oraculus" when she asks:

"..and what they do when its cloudy?" here is my answer Dava Sobel.. the same as with the chronometer system "waiting the clouds to disappear".. for the chronometer system needs some astronomical sights (as with lunar distances) to calculate the local hour..

I think Dava Sobel refers to Captain Sumner system of LOP inference in cloudy days, which can be applied as well to the lunar distances..

Lunar distances have disappeared when Marconi crossed the Atlantic with radio signals in 1906 that allowed chronometers to be perfectly synchronized..
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on 29 May 2014
I had read one or two books about ocean voyages in the sixteen, seventeenth and eighteenth centuries. The issue of longitude had been an issue raised - certainly in Batavia's Graveyard and The Caliban Shore. I stumbled across this little book by Dava Sobel and was fascinated by the story of John Harrison, who made it his life's work to solve the problem. He did so, despite the ongoing political intrigues and other obstacles along the way. What a wonderful legacy.
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