One of the nicest things I learned from writing Longitude is that a book can actually improve by virtue of being read. Numerous attentive readers took the trouble to write to me to point out typos or other errors in the text, which the publisher then corrected in subsequent editions. (For example, the typesetter had inexplicably swapped the word “latitude” for “longitude”—and vice versa—on several pages.)
Many more people wrote to say they'd enjoyed reading the book, and quite a few asked questions that the story had raised in their minds. Almost all of the correspondence about Longitude went back and forth by ordinary mail, and although I still answer reader's letters by hand, with a fountain pen, I see this personal web site as a way to continue and perhaps widen the dialog.
Longitude by Dava Sobel
184 pages, Walker and Company, New York $19.00
Review score: *** out of *****
I have a Seiko watch, that I bought years ago at what is now Cost Co. The watch has been very reliable over the years, needing nothing more than a new battery. My Seiko uses a quartz ossilator and it is probably accurate to a couple of minutes a year. Although by modern standards this does not make my lowly Seiko a chronometer, by the standards of the early 1700 my watch would be considered a miracle.
The clocks of that era lost as much as several minutes a day. For England, the leading maritime power of the era, imperfections in time keeping were not an abstract problem that would cause one to be late for tea. In some cases, they were the difference between life and death.
Ships navigators were able to fix their latitude, but they had no way of calculating their longitude. As a result, they were lost at sea on any voyage of more than a few days. In the first few pages of her book "Longitude", Dava Sobel, describes the horrible cost of these navigational errors. On a foggy night of October 22, 1707, two thousand sailors and officers of the British navy lost their lives to a navigational error, when four ships struck the rocks of off the Scillies Islands. All these lives were lost because the ships officers had no way to fix their longitude and so misjudged their location.
The terrible loss of life prompted the British Parliament to pass the Longitude Act of 1714, which offered the sum of 20,000 pounds to the person who invented a reliable method of calculating longitude at sea. This was a huge sum of money, equal to millions today and the longitude prize caused an avalanche of crack pot schemes.
Mathematicians and navigators realized that an accurate clock would allow a ship's captain to fix his longitude, by comparing the time difference between local high noon with a clock set to the time of the port of origin. But no clock at the time could keep accurate time aboard ship, where there was constant motion and large variation in temperature. The inventor of the first successful chronometer was John Harrison, who has been largely forgotten by the modern world, until Dava Sobel wrote her book.
Sobel is an excellent writer and she engagingly chronicles the attempts of the time to fix longitude, by celestial means and with time pieces. The struggles between Harrison and the astronomers of his day to claim the Longitude prize are recorded in contemporary accounts. But few details are known about Harrison himself and we never get a feel for who John Harrison was and what motivated him to create his revolutionary time pieces. Harrison's intricate time pieces still survive in various English museums, proof of his genius as a clock maker, even though the man remains an enigma.
Ian Kaplan - 2/96