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

My second book for the 2021 NONFICTION READER CHALLENGE is in the category of Inventions – “Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time,” by Dava Sobel, 1995. Dava Sobel is an “award-winning former science reporter for the New York Times, and writes frequently about science for several magazines, including Audubon, Discover, Life and Omni,” according to the inner book jacket.

The ‘Greatest Scientific Problem’ before the end of the 18^th century was how to determine longitude throughout a sea voyage. In 1714 the British Parliament created the Longitude Act, which set a huge monetary prize for a “Predictable and Useful” means of determining longitude. The ‘Lone Genius’ of the title is John Harrison, a self-taught Yorkshire clockmaker, who “invented a clock that would carry the true time from the home port, like an eternal flame, to any remote corner of the world.” But he was not awarded the prize money until 1773 (although not the prize itself) due to years of “political intrigue, international warfare, academic backbiting, scientific revolution and economic upheaval.” Of these factors, the ones the book concentrates on are political intrigue and academic backbiting. The book covers the scientific problem, John Harrison himself, and all the reasons why his claiming of the prize was not so straightforward.

The book’s first six chapters are about the difficulties of determining longitude and the various ways scientists of the day tried to solve the problem. The solution that most scientists and innovators focused on was the “lunar distance method.” This involved mapping the positions of the stars along the moon’s path for the entire year, from major cities throughout the world. Unfortunately, at that time, the positions of most stars were not yet known. But there were astronomers and other academics who spent their lives observing the heavens and keeping track of their lunar and stellar calculations, which were eventually published in volumes made available to ship captains.

John Harrison’s approach was the development of a clock – and eventually a watch – that would be able to determine the longitudinal position of a ship in relation to its port of departure. These devices came to be known as chronometers – and eventually every ship would have one. But the resistance of the believers of the lunar method, many of them in positions of power, kept Harrison’s device from being used for decades.

The detailed information about every aspect of this invention reads like a novel – with suspense, intrigue, heroes and villains. And the author writes in both an authoritative and lyrical way. For example, in describing how the moon came to be viewed as a celestial guide, Sobel writes:

• “The moving moon, full, gibbous, or crescent-shaped, shone at last for the navigators of the eighteenth century like a luminous hand on the clock of heaven. The broad expanse of sky served as dial for this celestial clock, while the sun, the planets, and the stars painted the numbers on its face.”

The scientific developments relating to the determination of longitude also led to other inventions, such as the sextant. And Harrison’s chronometers themselves lead to further inventions, such as the bi-metallic strip and an antifriction device. The bi-metallic strip “compensates immediately and automatically for any changes in temperature that could affect the clock’s going rate.” This is found today in thermostats and other temperature-control devices. Harrison’s antifriction device “also survives to the present day – in the caged ball bearings that smooth the operation of almost every machine with moving parts now in use.”

The only aspect of the book that I feel could have been improved is the addition of some illustrations of the five time-pieces that Harrison developed. They are described well in the book, but there are only very small pictures on the inside cover – about the size of postage stamps. Considering that they are the main inspiration for this book, they should have been highlighted more clearly.