I finished reading Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time by Dava Sobel this afternoon. It is a wonderful book.

Before John Harrison invented a clock that could reliably keep accurate time at sea, navigators had no way to tell where they were on the planet. It’s all really fascinating … If you look at the globe, the ‘parallels’ are the lines that are (duh!) parallel … the equator and the tropics of Cancer and Capricorn. If you’re on the open ocean, it’s easy to tell which parallel is the closest based on observing the sun (or the moon). There’s no way to determine your longitude, though – your east / west location on the planet can’t be calculated unless you know two things – the time where you are now and the time at some other reference point … And since there was no way to carry, for example, “London time” with you at sea, you couldn’t tell which longitude was the closest to you, and therefore you couldn’t know how far east or west it was to shore …

I’m doing a terrible job of summarizing it here and it’s a quiet, lazy Saturday afternoon and I don’t really feel like writing a review … Trust me, it’s an awesome book.

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