Hard to believe that little more than 250 years ago ships were wandering around the oceans with no accurate means to determine longitude. I recently, for the second time, read the book “Longitude” by Dava Sobel (foreword by Neil Armstrong). The story is beautifully written, giving us more than a glimpse into the lives, minds, and motives of those determined to solve the problem of longitude on the high seas.
Although “lines of latitude and longitude began crisscrossing our worldview in ancient times…” the author begins the story at the year 150 or so, when Ptolemy had plotted latitude and longitude lines “on the 27 maps of his first world atlas,” explaining that natural “lines” of latitude are set by nature based on length of day and sun height in the sky and by the guide stars at night (when the skies were clear). Longitude, on the other hand, has no such obvious natural indicators from the earth’s surface!
Longitude is a space-time entity. Early in the story we learn that one hour of earth spin marks 15 degrees longitude, which means the ship’s navigators would need to know what time it is at the home port relative to the time and location of the ship at any given time.
“Precise knowledge of the hour in two different places at once — a longitude prerequisite so easily accessible today from any pair of cheap wristwatches — was utterly unattainable up to and including the era of pendulum clocks.”
The clocks were impossible to calibrate with the rolling ships, changes in temperature, moisture and humidity affected the viscosity of the oils needed for the mechanical parts, and so on. Even the greatest of sea captain explorers spent much of their time lost or going in circles. Yet trade among far lands was increasing while too many sailors and valuable cargos ended up at the bottom of the sea.
The story is a whose who of famous scientists and stubborn geniuses!
“Renowned astronomers approached the longitude challenge by appealing to the clockwork universe: Galileo Galileo, Jean Dominique Cassini, Christiaan Huygens, Sir Isaac Newton, and Edmond Halley, of comet fame, all entreated the moon and stars for help.”
Of all the famous scientists’ stories in the book (that I’d heard of prior to reading the book), I found Galileo’s 1610 story to be one of the most fascinating!
With his telescope, Galileo observed the moons of Jupiter and calculated their orbital periods over the course of a year and produced the most accurate Longitude determination — on land — to date. Using the moons of Jupiter… (amazing what the mind can observe without TV and social media distractions, ha). But that still didn’t solve the problem on the high seas where it was most needed, although it did start quite a ruckus among barons who quickly learned that their property boundaries were wrong!
Observatories began appearing across Europe with the purpose of charting the stars and planets in order to help the seafaring navigate for longitude until a 24/7 solution could be found.
While the astronomers charted the stars, clockmakers and scientists like Christiaan Huygens were committed to solving the ship-board clock problems as the best solution for solving Longitude at sea. Huygens built the first working pendulum-regulated clock in 1656 (an idea proposed by Galileo but never constructed). Huygens clocks worked great — in smooth waters and calm even-temperatured weather. Huygens’s story is interesting too; he got into a patent fracas with physicist Robert Hooke over his spiral balance spring invention that provided an alternative to his pendulum for rate setting. (Oops, I’m getting off into the details here; can’t help it sometimes; every page is interesting!)
Finally, the Longitude Act of 1714, under Britain’s Queen Anne, offered generous financial prizes to anyone who could solve the Longitude at Sea problem. One degree of longitude crosses 60 nautical miles at the equator. Its easy to imagine how even the slightest error of degree could send ships way off course!
This is where the author introduces us to the eccentric stubborn hero of the Longitude story: self-taught clockmaker John Harrison. After more than 40 years of working on his sea clocks at a level of detail that rivals the great violin makers of old who knew exactly which trees in which locations offered the best tonal qualities, he finally earned his due. Not the prize, but history would ultimately be on his side.
I use the luthier’s intimate knowledge of woods specifically; that’s how Harrison solved the oils problem in some of the mechanics. He crafted wooden pieces from hardwoods that secrete their own natural oils; he used different ages of specific woods based on their age and tightness of grain. And that was just one aspect of what he figured out. But his journey was not without bias and challenge and political intrigue working both for and against him.
“A good watch may serve to keep a reckoning at Sea for some days and to know the time of a celestial Observation: and for this end a good Jewel watch may suffice till a better sort of Watch can be found out. But when the Longitude at sea is once lost, it cannot be found again by any watch.” — Sir Isaac Newton, 1721
As I wrote earlier, after more than 40 years and four versions of sea clocks or chronometers, Harrison’s legacy became the standard and credit given him as was his due. While others would later build upon his original works, it was Harrison’s pioneering stubborn determination over the decades that solved the essential space-time problem at sea. (I can’t help but think of the Albert Einstein quote: “Its not that I’m so smart; I’m just willing to stay on problems longer.”)
Oh yes, the book has a lot to say about Harrison’s nemesis and author of the Lunar Method for longitude, but I see that this little book review is already much longer than I intended!
The book caught my eye a few years ago while building a website for a Future Aviation Navigation Systems (FANS) client project. The opportunity to learn about the high-tech aviation navigation systems while reading the history of navigation with a focus on longitude was an amazing creative learning experience. Yet, as much as I enjoyed reading the book the first time, I am even more amazed with the second reading. I cried at the end — both times. Not because it was sad, but because it was so extraordinary; the author does such a great job of letting us see and understand the characters’ lives within the contexts of their times — times not so long ago.
How far we have come in 250 years. The impact on our lives of one little space-time navigation technology is beyond measure. And the technology evolution in navigation since then…