Reading history is always an exercise in demonstrating all I don't know. Latitude measures north and south while longitude does east and west. Latitude has been relatively easy to measure for centuries because of one habit. It's been the habit of the sun to rise in the east and set in the west, almost forever. There is no comparable way to easily determine longitude. How can the distance a sailing ship has travelled east or west be measured? That difficulty meant that ships were often far off course at sea until a method of measuring longitude was discovered.
Between 1730-1770, John Harrison built five clocks that could keep accurate time aboard ship. What's the big deal? Until those inventions clocks used pendulums to keep time. What do you think would happen to pendulums at sea. With Harrison's, non-pendulum clocks. a ship leaving London could tell the exact London time, of the sun's apex (noon) at the ship's location. That would give the ship a true reading on how far east/west if had travelled.
This was all news to me that I learned from reading Longitude: The True Story of a Lone Genius Who Solved the Greatest Problem of His Time, Dava Sobel. It's fun to learn new things and the book taught me much. Though I've crossed the Artic Circle, the Equator, and the International Dateline I've known little about navigating and now I know a little more.
Kaia and Al have returned to The Little House On The Prairie.
Takk for alt,
Al
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