We do board our boats and push the main switch, all navigational equipment will jump to live and our small GPS receiver will put out our exact position in an instant. We often do not bother about the vastness of the undertaking that was necessary to achieve all this. A small blimp marking our position on a digital plotter-chart showing the landmasses and other vessels. And when we look at the sky, we see the stars and romanticize about the past times when seafarers hat to negotiate their ways over the oceans by means of observing and learning from the stars. Very little is know about the greatest struggle of the 18th Century – the struggle of timekeeping.

“Longitude” by Dava Sobel

Navigation at sea was, up to this time, more or less a gambling game. The shores and coastlines of most of the European countries where known and there already did exist some techniques to calculate the latitude of a ship´s position. Captains would sail south or north to a certain latitude and try to sail exactly on a western course to reach the New World or any other island or continent. Most of the time they tried to remain in sight of the shores. Which was dangerous too: Lee shore in a storm is a bad choice, shallow waters, violent tides, pirates …

Dava Sobel introduces us to a time when going to see was still a great mystery and a great danger even for experienced sailors. She describes the hardship of navigation, the status-quo of a time when still a lot of ships reached their destinations, but a lot of ships vanished due to navigational errors. A time when seafaring was dependent on a whole lot more of luck than today. The Longitude-problem was the greatest problem of that time. Up to a point when a fleet of English warships sank near the Scilly Isles and the Queen finally advertised a prize: Anyone who can build a watch that would be functioning on an oceangoing ship that would not slow down would receive great honour and a big chunk of money. The X-Prize of their time. This is what “Longitude” is about: The magnificent story of John Harrison.

Most enthralling part of the book

The story in short – without spoilering you – for navigational purpose, a skipper needs the exact time from his port of departure which he will “take with him” on the course of the journey. Because of the fact that back in those times the calculation of the longitude was based on measures of the angles to stars, Sun and Moon at certain places (in Great Britain), like Greenwich, the Captain of a ship would have to calculate “his” time and the time in Greenwhich. The exact timekeeping was the key for celestial navigation and the chronometer is still a crucial part of this method of determining one´s position. That´s the most enthralling part: The understanding of the vastness of the undertaking of finding longitude, the work of one single ingenious man, John Harrison, who was working his entire life on building four watches – H1 to H4 – to deliver the proof that it was just possible. A mere 70 year struggle against politics, class conceil, prejudice and greed. And his ingenious ideas, the magnificent watches themselves and the historical implications.

What I like most about this book

This book is thin (just 180 pages) but so huge in its message: That humans can do everything. They can solve every problem, can overcome every obstacle and can fight to success if needed. Harrison dedicated his life – and his son´s life too – to deliver the proof that his watches can keep the time. H1 lost just 5 seconds on one of Captain James Cook´s voyages. Harrison “enjoyed” the company of such persons as Isaac Newton. This single man was responsible for the rise of the British Empire, the success of the British Navy because his chronometers enabled the Brits to navigate faster and more accurate than any other nation. Still today a lot of his ideas can be found in mechanical watches. His H1 is still running. And it´s a very, very accurate running clock too. This book delivers everything why I sail: A good gripping story, lots of history and a huge amount of fascination. “Longitude” by Dava Sobel, a definitive must read!


Other interesting articles on this topic:

Celestial Navigation, Part 1: The Sextant 

Chronometers by Wempe

What makes a good skipper?