• The Good: Astronomy, clock-making, and scientific adversaries
  • The Bad: Despite the short length, still some extraneous details
  • The Literary: Great chapter epigraphs

For centuries, maritime countries lost expensive ships, goods, and thousands of men at sea because sailors couldn’t determine their longitude. Latitude is easy. The lines of latitude are parallel to each other, never touching, forming concentric rings that decrease in diameter as they move closer to the poles. The source of latitude begins at the equator, originally derived as the place where the sun, moon, and planets pass directly overhead. Longitude lines, on the other hand, meet at the poles, and there is no “natural” center. Instead, it has been politics that has determined the zero line throughout history, which currently rests near London.

Sailors can easily determine their latitude by the length of the day or the height of the sun or stars. But longitude is not so easy, as a ship must know the precise time aboard ship and the precise time of the home port (or another known place). This seems like an easily solved problem with modern digital watches, but in the 18th century, large pendulum clocks weren’t entirely accurate, and taking them aboard a ship where they would be subjected to changes in temperature and the rolling waves, only worsened their ability to keep time.

So it was that the British Parliament offered a king’s ransom of 20,000 pounds for a practical and useful determination of longitude in the famous Longitude Act of 1718. The Longitude Board assessed applicants for the prize, which mostly consisted of government officials, naval officers, and scientists, particularly astronomers. The most promising method of determining longitude was by mapping the stars—that much seemed clear to all the members of the Royal Society, including Isaac Newton and Edmond  Halley. After all, sailors already knew navigation by the sky and equipment was relatively cheap.

So when John Harrison, a self-educated man, presented a new type of clock for precise measurement of time at sea, no one was quite sure what to do with it. Harrison, a perfectionist, spent decades building four groundbreaking clocks in succession, recreating the mechanism each time. And although his clocks kept near perfect time on sea voyages, Astronomer Royal Nevil Maskelyne contested his claim to the prize, more than once employing underhanded tactics. 

This short book is full of science, history, astronomy, and clock-making, but most of all, personal politics, greed, and envy. Recommended for fans of history and science!