John Harrison
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- For other people with this name, see John Harrison (disambiguation).
John Harrison (March 24 1693–March 24 1776) was an English clock maker, who designed and built the world's first successful maritime clock, one whose accuracy was great enough to allow the determination of longitude over long distances.
A place's Longitude is how far around the earth it is from a reference point, say London - usually measured in degrees (360 degrees is a complete circuit of the world). Many solutions were proposed for how to determine longitude at the end of a sea voyage, and therefore the longitude of the place you have just discovered (in case, for instance, you want to go back one day, or simply put it on a map). Harrison set out to solve the problem in probably the most direct way: by producing a reliable clock.
The theory was simple, the difficulty was producing a clock which could maintain accurate time on a long sea voyage in the roughest conditions and in widely-varying temperature, pressure, and humidty. However, if such a clock were set at noon in London at the start of a voyage, it would subsequently always tell you how far from noon it was in London at that second, regadless of where you had travelled to. By referring to the clock when it is noon locally (ie the sun is at its highest in the sky where you are) you can almost read directly from the clock face how far round the world you are from London. For instance, if it is midnight in London when it is noon locally, then you are half way round the world, (eg 180 degrees of longitude) from London.
Harrison in Lincolnshire
Harrison was born at Foulby, near Wakefield, in Yorkshire. Around 1700, the family moved to the North Lincolnshire village of Barrow upon Humber. First following his father's trade as a carpenter, Harrison built and repaired clocks in his spare time. Legend has it that at the age of six while in bed with smallpox, he was given a watch to amuse himself, supposedly spending hours listening to it and studying its moving parts. As clocks and watches of all kinds were rare and expensive at the time, and Harrison came from a family of only modest means, it is likely the legend is false or the timepiece was broken enough to be worth little.
He built his first longcase clock in 1713, at the age of 20. The mechanism was made entirely of wood, which was not a curious choice of material for a joiner. Three of Harrison's early wooden clocks have survived; the first (1713) is an old device for the step-by-step release of a clock's driving power. Being almost frictionless, it required no oiling.
The First Three Marine Timekeepers
In 1730 Harrison made a description and drawings for a proposed marine clock to compete for the Longitude Prize and headed for London seeking financial assistance. He met with Edmond Halley, the Astronomer Royal, and presented his ideas. Halley sent him to meet George Graham, the country's foremost horologist (clockmaker). He must have been impressed by Harrison, for Graham personally loaned him money and told him to build a model of his marine clock.
It took Harrison seven years to build Harrison Number One or H1. He showed it to members of the Royal Society who spoke on his behalf to the Board of Longitude. After fourteen years of failures, the Board was so skeptical of any such design that they demanded a sea trial. Harrison sailed to Lisbon and back aboard two naval vessels, and on their return both the Captain and the Master (navigator) praised the design. The Master noted that his own calculations had placed the ship sixty miles east of its true landfall which had been correctly predicted by Harrison using H1.
This was not the transatlantic voyage demanded by the Board of Longitude, but the Board was impressed enough to grant Harrison 500 pounds for continued work. Harrison moved on to develop a more compact and rugged version, H2. In 1741, after three years of building and two of on-land testing, H2 was ready, but by then Britain was at war with Spain in the War of Austrian Succession and the mechanism was deemed too important to risk falling into Spanish hands. He was granted another £500 by the Board while waiting for the war to end, which he used to work on H3. But by 1755 he had become convinced that large machines were not the right route to a marine timekeeper. H3 had proved a very valuable experiment, teaching Harrison a huge amount about the design and making of balance springs and it left the world two enduring legacies - the bimetallic strip thermometer and the caged roller bearing.
The Longitude Watches
Based on a watch made to his designs by John Jefferys he proposed to build two new timekeepers, a larger and a smaller watch. It was the larger H4 that was to be his masterpiece - an instrument of beauty, having the shape of a large pocketwatch but the size of a soup plate.
H4 took six years to construct, and Harrison, by then 68 years old, sent it on its transatlantic trial in the care of his son, William, in 1761. When the ship reached Jamaica the watch was only two miles in error. When the ship returned Harrison waited for the £20,000 prize, but the Board refused to believe the accuracy was not just luck, and demanded another trial. The Harrisons were outraged and demanded their prize, a matter that eventually worked its way to Parliament, which offered £5,000 for the design. The Harrisons refused but were eventually obliged to make another trip, to the Caribbean city of Bridgetown, on the island of Barbados to settle the matter.
At the time of the trial, another method for measuring longitude was being developed to the point where it was ready for testing, the Method of Lunar Distances. The moon moves fast enough, some twelve degrees a day, to easily measure the movement from day to day. By comparing the angle between the moon and the sun for today and when you left Britain (or more typically over Greenwich), the "proper position" of the moon could be calculated. By then comparing this with the angle of the moon over the horizon, the longitude could be calculated.
On Harrison's second H4 trial, the Reverend Nevil Maskelyne was asked to accompany the ship and test the Lunar Distances system. Once again H4 proved almost astonishingly accurate, measuring Bridgetown to within 10 miles. Maskelyne's measures were also fairly good, at 30 miles, but required considerable work and calculation in order to use. At a meeting of the Board in 1765 the results were presented, and once again they couldn't believe it wasn't just luck. Once again the matter reached Parliament, which offered £10,000 up front, and the other half once he turned over the design to other watchmakers to duplicate. In the meantime H4 would have to be turned over to the Astronomer Royal for long-term on-land testing.
Unfortunately, Nevil Maskelyne had been appointed Astronomer Royal on his return from Barbados, and was therefore also placed on the Board of Longitude. He returned a report of the H4 that was negative, claiming that the "drift rate" of the clock, the amount of time it gained or lost per day, was actually an inaccuracy, and refused to allow it to be factored out when measuring longitude. This made the H4 fail the needs of the Board, even though in reality it had already proven itself twice.
Harrison started work on his H5 while the testing was continuing, with H4 being effectively held hostage by the Board. After three years of this he had had enough;Harrison felt "extremely ill used by the gentlemen who I might have expected better treatment from" and decided to enlist the aid of King George III. He asked for and was granted an audience with the King, who became extremely annoyed with the Board. King George tested H5 himself at the palace and when it had lost only four and a half seconds in ten days he was outraged and is said to have stormed "By God Harrison, I'll see you righted!", and told Harrison to petition Parliament for the full prize after threatening to appear in person to dress them down. So in 1773, Harrison finally received his reward.
James Cook used a copy of H4, made by Larcum Kendall who had been apprenticed to John Jefferys on his voyages. Cook's log is full of praise for the watch and the charts of the southern Pacific Ocean he made with its use were remarkably accurate. The cost of these clocks was so high that the Lunar Distances method would also go on to be widely used for the next hundred years.
Memorials
Harrison died on his eighty-third birthday and is buried in the graveyard of St John's Church, Hampstead along with his second wife, Elizabeth and their son William. His tomb was comprehensively rebuilt in 1879 by the Worshipful Company of Clockmakers even though Harrison had never been a member of the Company.
Harrison's last home was in Red Lion Square in London, now a short walk from the Holborn Underground station. There is a plaque to Harrison on the wall of Summit House in the south side of the square. A memorial tablet to Harrison was unveiled in Westminster Abbey on the 24th of March 2006 finally recognising him as a worthy companion to his friend George Graham and Thomas Tompion,"The Father of English Watchmaking" who are both buried in the Abbey. The memorial shows a meridian line (line of constant longitude) in two metals to highlight Harrison's most widespread invention, the bimetallic strip thermometer. The strip is engraved with its own longitude of 0 degrees, 7minutes and 35seconds West.
Subsequent History
After World War I, Harrison's timepieces were found in a highly decrepit state in storage at the Royal Greenwich Observatory, by a retired Naval officer, Rupert Gould, who spent many years documenting, repairing and restoring them. It was Gould, not Harrison, who gave them the designations H1 through H5. Gould is the author of the book "the Marine Chronometer", covering the entire history of chronometers from the Middle ages through to the 1920s. It includes a very detailed description of the work of Harrison, as well as discussion of the subsequent evolution of the chronometer. It still remains the authoritative work on the marine chronometer.
Today the restored H1, H2, H3 and H4 can be seen on display in the National Maritime Museum at the Royal Observatory, Greenwich. H1, 2 and 3 are still running; H4 is kept stopped as, unlike the first three, it requires oil for lubrication, and degrades when run. H5 is owned by the Worshipful Company of Clockmakers of London and is on display at the Clockmakers' Museum in the Guildhall, London, as part of the Company's collection.
In the final years of his life, John Harrison wrote about his research into musical tuning and manufacturing methods for bells. His tuning system, (a meantone system derived from π), is described in his book "Concerning Such Mechanism ........ (CSM)." This system challenges the traditional view that "harmonics" occur at integer frequency ratios, and in consequence all music using this tuning produces low frequency beating. In 2002, Harrison's last manuscript, "A true and (short, but) (*crossed out) full Account of the Foundation of Musick, or, as principally therein, of the Existense of the Natural Notes of Melody:" was rediscovered in The US Library Of Congress. His theories on the mathematics of bell manufacturing, (using "Radical Numbers") are yet to be clearly understood.[link]
Following a major Symposium on the Longitude Problem at Harvard University, Dava Sobel wrote a book in 1995 chronicling the history of John Harrison's invention, titled, "Longitude: The true story of a lone genius who solved the greatest scientific problem of his time." An illustrated volume co-written with William J. H. Andrewes was printed in 1998: "The Illustrated Longitude" (ISBN 0-8027-1344-0). The account was dramatised in the 2000 film Longitude starring Michael Gambon as Harrison and Jeremy Irons as Gould.
See also
External links
- [John Harrison and the Longitude Problem, at the National Maritime Museum site]
- [PBS Nova Online: Lost at Sea, the Search for Longitude]
- [John 'Longitude' Harrison and musical tuning]
References
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