Notes on Longitude by Dava Sobel

Fascinating story on John Harrison and his watches and clocks and the problem of longitude, which was one of the biggest problems back in the day. It is even mentioned in Gulliver's Travels together with the discovery of perpetual motion.

I should then see the discovery of the longitude, the perpetual motion, the universal medicine, and many other great inventions, brought to the utmost perfection

In other words, people doubted whether the problem was even solvable. The book tells the story of how the marine chronometer came to be, about the board of longitude and about the battle between the so-called lunar method, which was the astronomers of the day's preferred method, despite the insane amount of data collection needed, and the timekeeping method.

It is a quick read at just above 160 pages and light on technical detail, but just a solid story on how one of the biggest scientific problems finally got solved in a practical way.