Longitude, by Dava Sobel and William J.H. Andrews

by Derwood Hunsdale-Talbot on September 21, 2009

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

LongitudeHere’s the problem: Using the sky and simple instruments, ship’s captains of the 18th century could determine fairly accurately how far north or south of the equator their ships were positioned (the latitude). The sky provided few useful clues, however, as to how far east or west of any given point the ship was positioned (its longitude). This lack of knowing exactly where one was on the globe resulted in countless shipwrecks, with the accompanying loss of lives and cargoes.

It’s an issue of accurately determining time. If one can know precisely what the time is on board, and simultaneously know the time in the homeport, one can calculate longitude. Onboard, one can track the position of the sun and determine twelve noon, but that’s just one half of the information necessary. The other half is to know what time it is from port. For that you need a clock. None of the clocks available at that time (most of which used a pendulum) would function accurately onboard a ship tilting and tossing on the sea.

The problem was so vexing, that the Longitude Act of 1714 was put in place by the British Parliament, promising a fortune to whoever could invent a “Practicable and Useful” means of determining longitude.

Here’s where the story starts to read like a thriller, as inventors vie for the prize, and one inventor in particular become the book’s protagonist: John Harrison, clockmaker. Genius.

Seriously, if not for the evidence of his completed works–most thankfully preserved–it would strain credibility to believe that a person using only the tools and materials (much of it wood!) available in eighteenth century, was able to conceive, craft and construct these clocks. Each clock he creates is not a mere enhancement of a previous design, but something an order of magnitude more refined. (For example, his first serious attempt at a chronometer, called the H-1, weighed seventy-five pounds. The model that eventually won for him the prize, most people would describe as a pocket watch.)

His great efforts and great disappointments are chronicled in a prose style that entirely compliments the story. Dava Sobel is a treasure.

By all means, buy the illustrated version of this book. The story and descriptions are wonderful, but the creations of John Harrison are magnificent works of engineering that fully qualify as works of art. You just have to see them to believe them.

Leave a Comment

Previous post:

Next post: