Woman Reading (is away exploring)'s Reviews > Longitude: The True Story of a Lone Genius who Solved the Greatest Scientific Problem of His Time

4 ☆

Before Britannia could rule the waves, its captains needed to figure out where their ships were going and, just as importantly, how to return home.

Sure, the concept of sectioning off the world by concentric lines of latitude (running east-west) and longitude (aligned by the poles) had existed as early as 300 B.C. The astronomer and cartographer Ptolemy had plotted in 150 C.E. his first world atlas with the Equator as 0° Latitude. Many dedicated astronomers had already witnessed that the sun, moon, and planets passed almost directly overhead at the earth's equator so Ptolemy's decision had been based on scientific observation. But for centuries, where to set 0° longitude was a political selection, so it had bounced around from the Canary Islands (Ptolemy's choice) to Rome to Jerusalem and to many more locations. Finally in 1884, representatives from 26 countries agreed at the International Meridian Conference to make the Greenwich meridian the world's prime meridian.

In Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time, Dava Sobel focused on the 18th century when the British and many others (except perhaps the Polynesians - see Sea People: The Puzzle of Polynesia) were beset by maritime misadventures and tragedies. In the early 1700s, determining a ship's position was a highly imprecise and challenging process as the main method of navigation was by dead reckoning, guided only by compass and the direction of the sun's path. Sailors could reasonably determine which latitude the ship occupied but they were literally and figuratively "at sea" when it came to the question of their longitudinal location. [Sextants weren't invented until the 1730s. Even then celestial navigation would require hours of observation, nautical charts, and an accurate timekeeper.]

The continued loss of ships, lives, and cargoes finally motivated London's various shipping interests to unite in their petition to Parliament to solve the "longitude problem" (which was really a navigation problem). The Longitude Act of 1714 established the Board of Longitude as judges to determine the recipient of prize money which ranged from £10,000 to £20,000, depending on the solution's level of accuracy. According to the Bank of England's inflation calculator, the 1714 prizes would be equivalent to £1.5 to £3 million today.

Dava Sobel wrote an interesting narrative about an unlikely hero, John Harrison, who became enmeshed in a David and Goliath battle that lasted decades. Although John Harrison worked as a carpenter, his mind had mechanical inclinations. He taught himself how to make a clock before he turned twenty. Upon learning of the prize from the Longitude Act, he sought to create the perfect timekeeper, despite the ways a moving vessel with its humid atmosphere eventually rendered all contemporaneous clocks erroneous. When navigators simultaneously knew the local time aboard the ship and the time at another location which had a known longitude, then they could could calculate their ship's longitude.

The Board of Longitude consisted of government officials, naval officers, and scientists from both astronomy and mathematics. By the mid-18th century, one Board member -- the astronomer royal Reverend Nevil Maskelyne -- keenly wanted a solution that reflected his scientific discipline. In particular, Maskelyne favored the lunar distancing method. He/the Board adopted unscrupulous methods to thwart Harrison: sabotage, backstabbing, and theft of intellectual property. Maritime navigation is a technical issue, but this tale reeked of jealousy, competitiveness, and political intrigue. Nothing like money and professional glory to elicit all the ugly sides of human nature.

Be still my geeky heart because this little book (4 hours for the audiobook) touched upon maritime history, astronomy, timekeeping, and even cartography. For an esoteric topic, this story was engaging, concise, and clear. The book only lacked images.

This link shows John Harrison's first submission for consideration. Completed in 1735, the H1 weighed 75 pounds and was housed in a 4' x 4' x 4' case.
https://www.rmg.co.uk/collections/obj...

This link is for Harrison's prize-winning H4, finished in 1759. This elegant chronometer with its pretty detailing had been miniaturized down to a diameter of 5 inches.
https://www.rmg.co.uk/collections/obj...

Harrison was an inventor with a perfectionist's streak. He continued to improve his masterpiece. This link is for John Harrison and Son's H5, made in 1770:
https://collection.sciencemuseumgroup...