Longitude

The inability to find longitude had been a hazard to sea travellers for many years. Then,k in the reign of Queen Anne, there was a disaster: over 2,000 crew were drowned when warships lost in fog were wrecked on the coast. Parliament hastily convened and passed the Longitude Act to try to solve the problem.

The Longitude Act set three prize limits, the top level being £20,000. In 1714 this was more than it sounds as the equivalent modern earnings would be

£30 Million

The calculations to work out longitude from time are very, very, basic. You just need your local time (LMT), and Greenwich Mean Time (GMT). Then you do these three steps:

• Local time - GMT = Time difference
• Time difference divided by 24 hours = Time factor
• Time factor multiplied by 360 degrees = Longitude

These steps can be reduced to a single equation:

(LMT - GMT) * 15 = Longitude

It seems almost laughably simple, but the problem Harrison had to solve was that there simply weren't any clocks accurate enough to keep GMT on a sea voyage.

As a result, most of the establishment believed they would find a solution through astronomical observation, rather than a time, which no device available could measure.

Harrison's main rival for the prize was the astronomer Reverend Nevil Maskalyne. Maskalyne believed that observations of the stars were the best way to determine longitude. An establishment figure to the core Maskalyne was aided by the fact that the Board was comprised of astronomers, not engineers, who naturally supported one of their own.

A short documentary uploaded to youtube details the rivalry between the self educated Yorkshire clockmaker Harrison, and the university educated London astronomer Maskalyne.

Harrison's solution to the Longitude problem was the engineer's answer: to build a more accurate clock. By knowing the time where you were and the time at a known location (e.g. Greenwich) a navigator could calculate their exact location. The problem was the inaccuracy of clocks in the period, meaning that no existing clock was accurate enough.

In total John Harrison produced four versions of his Marine Chronometer, each building on the one before.

"These two people have been cruelly wronged...
...By God sir, I will see you righted!"
George III.

Reverend Maskalyne had been appointed Astronomer Royal, and as such was now a member of the Longitude Board, despite the conflict of interest this caused. His final interference in the Longitude Prize came when he changed the reporting criteria for the test of H4, ensuring that although it had in fact passed the test on the voyage, the report to the board stated that it had failed.

Furious, Harrison's son wrote to King George III who granted them an audience. It is recorded that he was less than pleased with the way Parliament and the Board of Longitude had handled the entire affair.

At the King's insistence, John Harrison got his prize. He was eighty one.

Harrison died three years later, but his Chronometers were used by historic figures such as James Cook, and rapidly replaced astral navigation as the method of determining location at sea. The original Chronometers were found in the 1920's still in the museum, in delapidated condition, by a watchmaker called Rupert Gould who restored them to running condition.

All Harrison's devices can be seen at the Royal Observatory, now part of the National Maritime Museum at Greenwich.

The series juxtaposes the story of John Harrison (Micheal Gambon) with the story of Rupert Gould (Jeremy Irons) the man who rediscovered his watches, neglected and damaged, in the basement of the observatory and restored them. Somewhat dramatised for television, not all the incidents shown actually occurred, and real-life incidents were conflated, but it is unusually accurate for a period drama.

Winner of three Bafta's, and a record breaking eight nominations, this is a gripping piece of drama.

Chronometers H1 to H4 were created directly for the Longitude Challenge. However, there were three further watches linked to Harrison's work on the challenge and his attempts to claim the prize.

H5 was built and given to George III as proof that Harrison had solved the longitude problem. Tests on this watch were what convinced the King that Harrison was right.

H6 is a rumour. Harrison's notes indicate it was built, but if so its fate is a mystery. Many watchmakers would dearly love to find out the truth about this mysterious timepiece, which is described as a large pocket watch. H6 was also the subject of the final episode of "Only Fool's and Horses" when it turned up in Del Boy's garage and the Trotter brothers finally struck it rich. If only they hadn't invested it all in Far East Futures...

K1 was a copy of H4 made by a watchmaker named Kendall to prove to the Longitude board that others could replicate the Harrison watches and that they were not flukes. K1 was also the watch used by Captain Cook on his later voyages. Comparing the picture of K1 on the left, to the H4 image above, shows you how close a copy it was. (Sadly this image is now only available on the wayback machine - here)

More detail on the history of the Harrison Watches can be found in this free e-book available from the National Maritime Museum (of which the Royal Observatory is part).

John Harrison (1693-1776) and Lt. Cdr Rupert T. Gould R.N. (1890-1948) by J.Betts

As part of Maskalyne's attempt to prevent Harrision claiming the prize money he turned up at Harrison's door in 1766. He took the three larger timepieces (H1, H2 and H3) and moved them to the observatory in an unsprung cart. As you can imagine, such handling was not good for the delicate clocks' mechanisms, and they arrived in an unfit state to run. Soon after 1770, still unworkable, they were placed in storage. Fortunately H4 and K1 did not suffer this treatment. Carefully preserved, they never became as damaged as the older machines.

Despite brief interest in restoring them in 1891, the Harrison watches (including H4, by this time unworkable) languished in obscurity until 1920.

The official site for the clocks can be found at:

• National Maritime Museum: John Harrison & Rupert Gould

This lens was originally on Squidoo, as a purple star and multi-award winner, but it appears to have never made the migration to Hubpages. I have recovered and rewritten what I can, but unfortunately this has caused the loss of many years of comments and discussion.