Just over a year ago when chilling in a hostel in Pula, Croatia, a friend lent me a book: Longitude. Cool, I thought, seeing it simply as something that would help me pass the time as I laid around on the beach. A literary dork, I don’t often read nonfiction, so I was surprised how much I ended up enjoying this story of sea clocks that I read through as quickly as I would have a novel. If you have the slightest interest in British history, seafaring, navigation, clocks, or astronomy, I cannot recommend it enough.
To get on with it, the book chronicles John Harrison‘s journey toward solving the problem of longitude. We take for granted the globes we’ve grown up with that are stratified by their degrees in both longitude and latitude, never really thinking about what mankind had to undergo to come up with this. How on Earth did they figure this out way back before today’s technology? The problem was so dire that, in 1714, the British Parliament offered a monetary prize of £20,000 (worth millions in today’s terms) to whomever could solve it.
As Harrison (a self-taught clockmaker by trade) determined that being able to accurately track time was at the crux of the matter (such that the local time of a destination could be compared with a basis such as Greenwich Mean Time), what was needed was an accurate clock. Sounds easier to us than what the issue really was at the time. In the 18th century, clocks didn’t exist that could keep ticking with accuracy for a long duration of time, and certainly not against conditions at sea of varying temperature, moisture, and pressure. And so, Harrison proceeded to build his clock, refining it through 5 different versions for over 4 decades of his life, all the while running neck and neck with competing clocks and the other dominant school of thought, 
astronomy (which relied on the stars as a measure of position…which works great until it gets cloudy!). It’s a fascinating story of dedication and precision and such a testament to man’s perseverance and innovation.
Harrison’s “H5,” is located in the Worshipful Company of Clockmakers‘ collection in London. H1 through H4 of the sea clocks (technically referred to as “chronometers”) are on display and still tickin’ in the National Maritime Museum‘s Royal Observatory in Greenwich, where time begins 
