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Book Review: Longitude

© Sara E. Polsky

Longitude
by Dava Sobel
Penguin USA
184 pages

"Here lies the real, hard-core difference between latitude and longitude - beyond the superficial difference in line direction that any child can see: The zero-degree parallel of latitude is fixed by the laws of nature, while the zero-degree meridian of longitude shifts like the sands of time. This difference makes finding latitude child's play, and turns the determination of longitude, especially at sea, into an adult dilemma - one that stumped the wisest minds of the world for the better part of human history."

But one mind wasn't stumped - that of John Harrison, a British clockmaker who used his knowledge of mechanics, rather than complicated theories of math and astronomy, to solve the problem of longitude. His achievement is the basis for Dava Sobel's Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time.

Very little is known of John Harrison's early life. Born in England on March 24, 1693, he grew into a man with a love of clocks, of woodworking, and of knowledge. All of these qualities would stand him in good stead later in life, as he set his eyes on Parliament's £20,000 longitude prize. Where longitude was concerned, he would prove himself over the leading astronomers of his day - Isaac Newton, Edmond Halley, and Galileo Galilei. His is a fascinating story, and Longitude, an equally fascinating book.

The book starts with an explanation of the history of longitude - how scientists throughout history have arbitrarily assigned meridians to various locations for mapping purposes, but have never given sailors an accurate way of finding their longitude at sea. Columbus sailed along a single latitude on his way to the Indies, and would have arrived there following his latitude-driven course if the Americas had not gotten in the way. But others at sea weren't nearly as lucky, and they needed John Harrison's clocks, models H-1 through H-5, to survive. Harrison fought for years to win his prize from the Board of Longitude, whose members favored scientific rather than mechanical means for finding longitude. But Harrison's marine chronometers were eventually accepted and mass-produced.

Dava Sobel's Longitude is a story behind a story, about something seemingly obscure but incredibly important. It is a joy to read, however, as much for the story as for Sobel's amazing writing. I found myself skipping ahead through the book, even though I already knew what would happen, just to see how Dava Sobel would express a thought, and I often went back to reread passages, simply because I loved the way they sounded.