I have just finished reading this intriguing book, Longitude by Dava Sobel.


The book narrates, with many interesting anecdotes along the way, the search for a method of determining longitude at sea. Without a reliable way of doing so, ships could lose their way and, worse still, run aground. Many ships and many lives were lost as a result.

In nutshell, the problem could be solved if the ship’s navigators had reliable knowledge of what time it was at the home port when they took a bearing on the sun, moon or stars. The bearing would give them the local time and the difference between the two times, together with knowledge of the longitude of the home port, would enable them to calculate the local, ship’s, longitude. But how were they to know what time it was at the home port?

In order to encourage inventors, the government set up a Board of Longitude to vet proposed solutions and award a prize of £20,000 for the first successful entry.

Skipping ahead to the nub of the story, there were two main groups vying for the prize. The first comprised the astronomers who believed that only a solution involving observations of the positions of the stars and moon would be sufficiently accurate. The second comprised the clockmakers striving to built a marine clock (the term “chronometer” was eventually coined for this device) that would be impervious to changes of temperature and atmospheric pressure and the – often violent – movements of the ship.

Like all good stories, this one has heroes and villains. The main villain was Nevil Maskelyn, an astronomer and eventually Astronomer Royal. To his merit and at great labour, he produced the definitive tables of the positions of the moon and stars against GMT which could be used to compute a ship’s longitude… but only when weather and the moon’s orbit allowed. He was the villain of the piece because he despised the “Mechanicals” and their clocks and did his best, dirty tricks not excluded, to prevent the clockmakers from winning the prize.

The heroes were the clockmakers, John Harrison and his son, who set themselves the seemingly impossible task of building a clock that would reliably keep perfect time at sea.

If you have read your history, you will know that the Harrisons eventually triumphed though the Longitude Board, while giving them various sums of money to finance their work, never gave them full recognition for their remarkable achievement, continually adding new conditions and requirements so that the prize remained always just beyond their reach.

The author is clearly enthralled by the story and passes on the excitement of it to the reader. It is a non-technical account, a book that anyone can read with enjoyment.

Highly recommended.

About SilverTiger

I live in Islington with my partner, "Tigger". I blog about our life and our travels, using my own photos for illustration.
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