Dava Sobel


The true story of a lone genius who solved the greatest scientific problem of his time

Book review by Anthony Campbell. Copyright © Anthony Campbell (1999).

Those of us who are not seafarers or naval historians may not be aware of how difficult and dangerous it was to navigate in the days before a ship's longitude could be known precisely. In 1707 four out of five warships foundered on the Scilly Isles, off the south-west tip of England, as the result of an error of longitude; two thousand men were drowned and only two survived, one of whom was the Admiral—and he was murdered by a beachcombing woman for the sake of his emerald ring. Disasters of this sort caused Parliament to offer a twenty-thousand-pound reward for the invention of a means of keeping time accurately at sea, for knowledge of the time was the key to determining longitude. The problem was ultimately solved by John Harrison, a self-taught Yorkshire clockmaker, but not without a prolonged battle not only with the technicalities of clock-making but also with prejudice in high quarters.

The main rival system that Harrison had to compete against was not mechanical but astronomical. It depended on observing the motions of the moon, using the recently invented sextant. This did work, but was extremely difficult to do in practice, owing to the problem of making accurate observations from a moving deck and also the complicated mathematical calculations required. Harrison's clock, in contrast, was simple to use, but this didn't please those who had invested effort and prestige in the astronomical method. The superiority of the clock could not ultimately be denied, but Harrison did not receive the full credit due to him until he was in his seventies, and even then only with the assistance of the King himself. Moreover, although he was paid most of the money he was entitled to, it was in the form of a bounty from Parliament, not the prize itself, which was never finally awarded to anyone.

The story has been well told by Dava Sobell in this short book. She explains the intrigues that went on and also gives a clear account of the nature of the navigational problem that had to be solved. However, there is not a great deal of information about the mechanism of the clocks themselves; I should have liked to have more details of their construction, perhaps with some diagrams, though no doubt this would have made the book a great deal longer.

%T Longitude
%S The true story of a lone genius who solved the greatest scientific problem of his time
%A Dava Sobel
%I Fourth Estate
%C London
%D 1995
%G ISBN 1 85702 571 7
%P viii + 184 pp
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