I would highly recommend that history buffs or anybody even remotely interested in watches, read the book, Longitude by Dava Sobel. It is a tremendous story and gives the reader real perspective on how accurate timekeeping solved a seemingly insurmountable timekeeping and navigational problem.
Consider this, early global navigators such as Sir Francis Drake, Christopher Columbus and Vasco da Gama, all had no reliable means of confirming their locations at sea. Lack of reliable information meant ships carrying valuable cargo for the crowns of Italy, England, France and Portugal experienced countless shipwrecks and lost important cargo.
The challenge was that to determine your position at sea, you needed to know your latitude and your longitude. As author Dava Sobel, succinctly explains in the book, latitude was rather easy to determine, longitude was not. The rings of latitude started at the Equator (zero degrees) and ran parallel up to the north and south poles. The Equator was determined to be the starting point for latitude as the planets, moon and sun would pass almost directly overhead. Ok fine, but what about longitude, why was this calculation so difficult? Well to make this calculation, the ship’s captain would need 2 pieces of information; the accurate time aboard the ship and the time at the home port. While this sounds rather simple today, consider the challenges of day, timekeeping was neither that accurate or portable in the 16th and 17th centuries.
The book Longitude does a great job of explaining the following, but here goes my lesser attempt; the Earth rotates 360 degrees every 24 hours and 1 hour represents 1/24th of the rotation or 15 degrees. Think about it…… if 1 hour is 15 degrees then at the Equator where the earth is the widest, 15 degrees is equal to 1000 miles and 1 degree of longitude equals 4 minutes of time. Ship navigators tried everything; pendulum clocks, charts and compasses to the famous astronomers of the day and their attempts at solving the problems using celestial calcuations (not much help when it was cloudy). Ships ran off course, became ship wrecked and lives and valuable cargo was lost.
It wasn’t until 1714, when the British Parliament established a huge cash reward for anybody who helped solve the problem of longitude calculation. It was the single minded focus of a carpenter, John Harrison, who spent 25 years of his life inventing a solution small enough and accurate enough to solve this problem. His various clocks, called the H1, H2 and H3 represented his never ending quest to solve the problem.
Dava Sobel’s captivating look at this man’s life and his dedication to accurate timekeeping while being shunned and mocked by the scholars of the day, will make every collector admire their watch with a new found love & apprecation.
P.S. Longitude is also a popular A&E movie for those wanting to rent instead of read.