John Harrison in a 1767 portrait.

If I could bring back Google Maps to early eighteenth-century Britain, I’d be a millionaire. See, figuring out a ship’s longitudinal coordinates was a huge problem back then. So much so that the British Parliament offered a prize of what amounts to $2.2 million in today’s dollars to anyone who could produce a practical method for pinpointing a ship’s location.

Latitude was pretty easy: All you needed was the sun and some charted data. But longitude had theretofore only been discernible by sheer instinct and guesswork, which often led to ships crashing into unforeseen hazards and hundreds of casualties. Even renowned navigators armed with a compass (which were still unreliable at the time) had to basically hope they weren’t going the opposite way or that the ship didn’t run aground.

That’s where John Harrison came in. Dava Sobel’s Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time tells the story of this lovably odd son of a carpenter with no formal scientific training who created a revolutionary maritime clock. Previous ship clocks couldn’t keep time in bad weather, but Harrison’s was self-stabilizing and self-lubricating so that it wouldn’t wear down and wouldn’t be affected by the briny sea air and turbulent waters.

Harrison responded to Parliament’s challenge for a longitudinal tool, but unlike other people with crackpot submissions, he wasn’t in it for the money. He was like the Nikola Tesla of maritime horology: eccentric, hermetic, obsessive, but in it only for the joy of the scientific challenge itself. And like Tesla with Thomas Edison, Harrison had a natural antagonist in Nevil Maskelyne, a royal astronomer appointed to Parliament’s “Board of Longitude,” which controlled the terms of the prize money. Maskelyne had his heart set on the lunar distance method, which involved gauging the moon’s distance from another star to calculate the local time, and gave Harrison all kinds of politically motivated headaches along the way in order to get the lunar method some headway. Harrison’s son even had to resort to writing King George III (the King George) to get some help moving the intransigent Board along. Turns out the young monarch was a science geek himself and gladly helped the Harrisons out (just as he was levying heavy taxes on an increasingly disgruntled colonial America).

Overall, Sobel’s book, though heavily biased toward Harrison, is an accessible, breezy account of his engineering process, the radical innovations he made in every version of his “chronometer,” and the obstacles he had to surmount to achieve recognition from a skeptical scientific community. Take some time to read it.