LONDON (Reuters Life!) - A rare pamphlet produced by John Harrison -- an 18th century British clockmaker who solved the complex navigational problem of longitude -- will be auctioned in London on Thursday.
The 18-page pamphlet was published by Harrison in 1765 as a protest against a government decision not to award him a vast prize of 20,000 pounds -- around $10 million today -- even though he had designed and built a marine timekeeper that successfully tackled the problem of longitude.
"It's a kind of summary at this critical stage of Harrison's life of where he was at, what he felt he had achieved and why he felt he deserved the reward," said Jonathan Betts, a specialist in horology at the National Maritime Museum in Greenwich.
"It's a very nice little snapshot right in the middle of an absolutely stunningly important and interesting technological story," he said of the pamphlet.
Britain established the longitude prize in 1714, calling on inventors to create a method of determining longitude within 30 nautical miles -- enabling a ship to know how far east or west it had sailed from its home port.
It was an essential problem to resolve at the time, with Britain the dominant world power and ruler of the seas. Today it might be the equivalent of inventing the global satellite positioning system used by navigators everywhere, experts say.
Harrison realized that by setting a clock to London time, a navigator could compare this to the local time as he sailed around the world. An accurate clock would enable the ship's longitude to be calculated, since for every 15 degrees traveled eastward, the local time would have moved ahead one hour.
He spent 35 years developing a clock which could cope with a ship's motion and changes in humidity and temperature at sea.
The H4 marine timekeeper was his fourth version of the clock and was successfully tested on two major voyages, losing just five seconds on a journey to Jamaica in 1761, a navigational error of one nautical mile.
Despite that, the government's Board of Longitude insisted on a second test. The second voyage was also successful but still they wouldn't pay up, prompting Harrison's angry protest.
One of the few surviving copies of his pamphlet, "A narrative of the proceedings relative to the discovery of the longitude at sea" will go on sale at Bloomsbury Auctions in London, where it is estimated to fetch between 25,000 and 35,000 pounds ($37,000-50,000).
Harrison was finally awarded 8,750 pounds in 1773 when he was aged 80. He died three years later. The clock is on display at the Royal Observatory in Greenwich, where it attracts over a million visitors a year.
Editing by Luke Baker and Paul Casciato