While I was on spring break with my wife and kids recently, we got to spend some time with a friend of ours that we hadn’t seen in a while. He and I were talking about his new watch, which had what appeared to be semaphore flags around the bezel of it, and he asked me if I had heard of the book Longitude, by Dava Sobel (foreword by Neil Armstrong!: ed.) . I told him that I hadn’t, but after he described it, I had to track it down (and did so from our friends at Wordsmiths [ring plug bell now]).
I have to confess that I had never really thought about the differences between latitude and longitude; in fact, I typically couldn’t remember which was which. Well, apparently a sailor who can’t tell the difference and can’t accurately calculate his or her latitude or longitude is in deep trouble (or shallow trouble, to double up on the pun). And as it turns out, latitude isn’t that difficult for those in the know to track and measure, going back hundreds and hundreds of years. The simple answer is because latitude (those are the lines that go horizontally around the globe) can be fairly easily calculated based on the positions of the sun and stars, and every latitude line is spaced equally apart from the next.
Longitude, however, is a different story. Calculating longitude is much more difficult, because the spacing between the longitude marks varies depending on how far north or south you are on the globe. Calculating this is apparently very difficult without the right instruments; what those instruments should be is really the crux of the story behind this book.
After way too many shipwrecks caused by incorrect calculations of longitude, in 1714 England’s government offered a reward to whomever could come up with a methodology for accurately determining longitude at sea. This book follows the efforts of several inventors, scientists, and others who sought to earn this prize, and tells the triumphant story of a clockmaker named John Harrison who invested countless years in his quest to prove that a good timepiece was the answer.
As it turns out, in order to determine longitude at sea you have to know what time it is where you are, as well as what time it is a point of known longitude at that exact moment. And clocks didn’t work so well at sea in the old days, as pendulums were victims of heat, cold, moisture, and the turbulence of the ocean. Harrison devised some new schemes for building timepieces that would not be affected by these elements, and against all odds (and some powerful individuals with ulterior motives), he managed to convince the world that the answer lied in the use of these clocks (as opposed to, for instance, tracking the eclipses of the moons of Jupiter). And he built clocks to do the trick — spending nineteen years alone on his third (of four) iterations.
I’ll spare you the details of Harrison’s story, because the book itself is so short. But I will tell you that this book completely changed the way I think about geography and telling time.