The British Parliament consulted with Sir Isaac Newton and Edmond Halley (for whom the comet is named) when they passed the Longitude Act of 1714. Parliament needed brilliant minds like theirs, because the problem the British faced was a difficult one.
Mastery of navigation on the high seas was crucial to the success of the Empire. Yet there was not any reliable means for a ship's captain to know where he was. And if a captain did not know where he was, then navigating to where he wanted to go was fraught with peril. It could mean wandering into unsafe waters. Such was the fate of a whole fleet of British ships in 1707. The fleet struck rocks they did not expect to encounter, sinking four ships with a loss of almost 2000 men.
Using lines of latitude and longitude to determine location is a very old idea. But it turns out that as a practical matter, latitude was much easier for a ship's navigator to determine than longitude. Finding longitude requires that you know the time of day at your location and also at some known reference longitude. The difference between the two times is directly related to the difference in longitudes. With the time difference in hand you can calculate your current longitude. But in the early 1700s no one had been able to come up with a clock that could keep accurate time while at sea.
Longitude is the story of John Harrison. A self-trained carpenter and clockmaker, he provided the first practicable means to solve "the longitude problem" with a clock that could keep accurate time while at sea.
Harrison faced intrigue and double-dealing in presenting his clocks to the Longitude Board, formed after the passage of the 1714 law. The brightest minds of the day held the opinion that the only practical solution would be found by constructing reference tables of star positions at known longitudes. The reference positions would then be compared to the positions seen by a ship's navigator, and longitude calculated from there. This method of determining longitude was known as the "clockwork of the heavens". Those same brightest minds thought that no one would ever devise an accurate seagoing clock.
Unfortunately for Harrison, "heavenly clockwork" thinkers predominated on the Board. They were disinclined to believe he, a lone clockmaker, with no formal training, could provide a solution. That Harrison came up with not one, but four different clock designs that met the needs of navigators was an astonishing achievement. But it took years, and an appeal to the King, for the British government to acknowledge it.
Longitude was first published in 1995 and is today considered a classic of popular science writing. Sobel tells the story in an easily digestible way, and at 175 pages in the paperback edition it's not a long read. If you have an interest in history, science, or navigation and haven't yet read it you're missing out. I give Longitude Four Stars ⭐⭐⭐⭐.
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Title: Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time
Author: Dava Sobel
Publisher: Bloomsbury (US) Publish Date: November 5 2007
ISBN-13: 9780802715296
List Price: $14.40 (Paperback as of 12/12/2021)