Review

Longitude

The Man Who Opened Up the Seas

Review of Longitude, The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time by Dava Sobel.

This book's author is out of step with the times – which is very much to her credit. In an age when historians of science are anxiously trying to show that the great discoveries of the past were made by men with "feet of clay," Sobel adopts the opposite thesis. Her book is a tribute to the inventive genius and heroic effort of an 18^th-century self-educated clockmaker-the man who solved "the greatest scientific problem of his time."

With the enormous increase in shipping during the Enlightenment, the discovery of an accurate method of determining position at sea became critical. Sobel writes:

The wealth of nations floated upon the oceans. And still no ship owned a reliable means of establishing her whereabouts. In consequence, untold numbers of sailors died when their destinations suddenly loomed out of the sea and took them by surprise.

England's Parliament recognized the urgency of the problem; in 1714, it offered a reward (worth about $12 million in today's currency) to anyone who could devise a means of measuring longitude precisely. To gauge longitude requires knowing the time aboard ship and also the time at another place of known longitude – at the very same moment. The time difference can then be converted into a geographical location. However, the standard time-keeping instrument in the 17th century – the pendulum clock – was grossly inaccurate at sea. So most people assumed that the only method of finding longitude would require volumes of impossibly precise astronomical tables.

One man – John Harrison – took a radically different approach. He attempted to construct what others thought hopeless: a clock so accurate that sailors would never lose track of the time at their port of origin.

Harrison had to invent a new type of clock; one that was unaffected by ship motion and insensitive to variations jn temperature and humidity. The story of his success – the story of his brilliant invention, of his lonely, persistent struggle in the face of widespread ridicule, of his courageous defiance of an antagonistic scientific establishment – is fascinating and inspiring.

The book does have one significant flaw. In her effort to make it non-technical, the author occasionally omits necessary explanations-e.g., how one determines local time on a moving ship. However, this is far out- weighed by the book's virtues – especially the author's obvious (and justified) enthusiasm for the whole subject and her admiration for John Harrison. At the end of the book, the reader can understand, and share, her emotional reaction, when she describes being "reduced to tears" upon seeing Harrison's clock at the Maritime Museum in Greenwich.

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Longitude, The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time by Dava Sobel. The heroic saga of John Harrison, who finally solved the problem of determining longitude at sea and thereby opened up the world to safe navigation and trade.

Review

Longitude

The Man Who Opened Up the Seas

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