Longitude: The True Story of a Lone Genius who Solved the Greatest Scientific Problem of His Time

by Dava Sobel

Penguin Books, 1995, 184 pages, paperback

ISBN 0140258795 ($9.56)

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The Village Carpenter Who

Humbled the Astronomer Royal


This little book was first published in 1995, the result of an extended essay on the topic (the subtitle is either a grabber or a turn-off!) by the author in the Harvard alumni magazine. It came to attention again this year when the cable network A&E ran a four-hour documentary based on the book, which was rich in photography and English actors such as Michael Gambon, Jeremy Irons and Ian Hart.

In the early 18th century, one of the greatest scientific problems was calculating longitude on the high seas. At the time, navigators had two choices, both treacherous. They either traveled well-known routes, thus opening them to the threat of pirate attacks, or they used imprecise navigational methods to avoid that danger. But the latter method presented its own problems: it was more deadly because ships often got lost at sea or ran aground. Many sailors lost their lives and vast fortunes were dashed as ships crashed into rocks.

The problem was so serious that the English Parliament passed the Longitude Act in 1714. The Act established a panel of judges including the Astronomer Royal to study the problem and announced a prize of 20,000 (worth millions of dollars today) to anyone who could determine longitude accurately.

Enter John Harrison, a village carpenter and self-educated amateur clockmaker from Yorkshire. He believed that the solution lay in time, not in the heavens as the scientific establishment had postulated. Harrison devoted his entire life to the pursuit of the longitude prize, all the while battling university scholars who thought him an incompetent crank.

In Longitude author Dava Sobel tells Harrison's story with vigor and insight. It is clear that she greatly admires Harrison's genius and determination. She describes how he "went fromhumble beginnings to riches by virtue of his own inventiveness and diligence, in the manner of Thomas Edison or Benjamin Franklin."

Throughout Harrison's illustrious career, he invented a number of innovative techniques for keeping accurate time and solved many problems that had plagued clockmakers for centuries. Sobel writes: "Most pendulums of Harrison's day expanded with heat, so they grew longer and ticked out time more slowly in hot weather. When cold made them contract, they speeded up the seconds, and threw the clock's rate off in the opposite direction." Harrison solved this by "combining long and short strips of two different metals brass and steel in one pendulum" Another invention of Harrison was caged ball bearings which are still used today.

Harrison did eventually win the longitude prize, but not until he was in his late 70s. The debate over the way longitude would be found raged on throughout his many trials over the decades between the 1720s and the 1770s. He submitted two clocks to the Longitude Board between 1737 and 1741 (named H1 and H2), but spent nearly twenty years perfecting H3 which he finally submitted in 1769. During this time, a rival 40 years younger than Harrison, Reverend Nevil Maskelyne, insisted that the lunar distance method was the way that longitude was to be found.

Because Longitude is a popular account, there are few technical details. For the most part, this lack of detail does not detract from the book, but occasionally the lack of technical description confuses the reader. For example, Sobel does not explain how one determines local time on a moving ship. Nevertheless, this flaw does not detract from the overall value of the book. Sobel tells her tale well and brims with enthusiasm for John Harrison and his wonderful invention that solved a centuries-long obstacle to safe navigation on the high seas. At the end of the book, Sobel touchingly describes her reaction to seeing Harrison's clocks for the first time.

"Coming face-to-face with these machines at last after having read countless accounts of their construction and trial, after having seen every detail of their insides and outsides in still and moving pictures reduced me to tears."

Jason Lockwood


Copyright 2005 - The Frederick A. Cook Society