The longitude's Marine Chronometer by John Harrison (24th March 1693 – 24th March 1776)
As a great English icon I thought it would be of interest to write the history of John Harrison (24 March 1693 – 24 March 1776) who was a self-educated English Clockmaker and Yorkshire Carpenter who invented the marine chronometer, a long-sought device in solving the problem of establishing the East-West position or Longitude of a ship at sea, thus revolutionising and extending the possibility of safe long distance sea travel in the Age of Sail.The problem was considered so intractable that the British Parliament offered a prize of £20,000 (comparable to £2.87million / €3.65million / $4.72million in modern currency) for the solution.
John Harrison was born in Foulby near Wakefield in West Yorkshire the first of five children in his family. His father worked as a carpenter at the nearby Nostell Priory estate. The house where he was born bears a blue plaque.
Around 1700, the family moved to the North Lincolnshire village of Barrow upon humber. 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, spending hours listening to it and studying its moving parts.
In 1730 Harrison created a description and drawings for a proposed marine clock to compete for the
Longitude Prize and went to London seeking financial assistance. He presented his ideas to Edmond Halley, the Astronomer Royal. Halley referred him to George Graham the country's foremost clockmaker. He must have been impressed by Harrison, for Graham personally loaned Harrison money to build a model of his marine clock.
It took Harrison five years to build Harrison Number One or H1. He demonstrated it to members of the Royal Society who spoke on his behalf to the Board of Longitude. The clock was the first proposal that the Board considered to be worthy of a sea trial. In 1736, Harrison sailed to Lisbon on HMS Centurion and returned on HMS Oxford. On their return, both the captain and the sailing master of the Orford 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 for further development. Harrison moved on to develop H2, a more compact and rugged version. 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. In any event, Harrison suddenly abandoned all work on this second machine when he discovered a serious design flaw in the concept of the bar balances. He was granted another £500 by the Board while waiting for the war to end, which he used to work on H3. Harrison spent seventeen years working on this third 'sea clock' but despite every effort it seems not to have performed exactly as he would have wished. Despite this, it had proved a very valuable experiment. Certainly in this machine Harrison left the world two enduring legacies — the bimetallic strip and the caged roller bearing.
After steadfastly pursuing various methods during thirty years of experimentation, Harrison moved to London in the late 1750's where to his surprise he found that some of the watches made by Graham's successor Thomas Mudge kept time just as accurately as his huge sea clocks. Harrison then realized that a mere watch after all could be made accurate enough for the task and was a far more practical proposition for use as a marine timekeeper. He proceeded to redesign the concept of the watch as a timekeeping device, basing his design on sound scientific principles.
He had already in the early 1750's designed a precision watch for his own personal use, which was made for him by the watchmaker John Jefferys C. 1752 - 53. This watch incorporated a novel frictional rest escapement and was also probably the first to have both temperature compensation and a going fusee, enabling the watch to continue running whilst being wound. These features led to the very successful performance of this "Jefferys" watch and therefore Harrison incorporated them into the design of two new timekeepers which he proposed to build. These were in the form of a large watch and another of a smaller size but of similar pattern. However only the larger No. 1 (or "H4" as it sometimes called) watch appears ever to have been finished. (See the reference to "H6" below) Aided by some of London's finest workmen, he proceeded to design and make the world's first successful marine timekeeper that for the first time, allowed a navigator to accurately assess his ship's position in Longitude. Importantly, Harrison showed everyone that it could be done. This was to be Harrison's masterpiece — an instrument of beauty, resembling an oversized pocket watch from the period. It is engraved with Harrison's signature, marked Number 1 and dated 1759.
This first marine watch (or "Sea watch" as Harrison called it) is a 5.2" diameter watch in silver pair cases. The movement has a novel type of escapement which can be classed as a frictional rest type, and superficially resembles the verge escapement with which it is often incorrectly associated. The pallets of this escapement are both made of diamond, a considerable feat of manufacture at the time. The balance spring is a flat spiral but for technical reasons the balance itself was made much larger than in a conventional watch of the period. The movement also has centre seconds motion with a sweep seconds hand. The Third Wheel is equipped with internal teeth and has an elaborate bridge similar to the balance cocks of the period. It runs at 5 beats (ticks) per second, and is equipped with a tiny remontoire. A balance-brake stops the watch half an hour before it is completely run down, in order that the remontoire does not run down also. Temperature compensation is in the form of a 'compensation curb' (or 'Thermometer Kirb' as Harrison put it). This takes the form of a bimetallic strip mounted on the regulator sector-rack, and carrying the curb pins at the free end. During development of No.1, Harrison abandoned the regulator, but left the regulator disc in place for æsthetic reasons, and the compensation.
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 HMS Deptford reached Jamaica the watch was 5 seconds slow, corresponding to an error in longitude of 1.25 minutes, or approximately one nautical mile. When the ship returned, Harrison waited for the £20,000 prize but the Board believed the accuracy was 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 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 the day one left for Britain, the "proper position" (how it would appear in Greenwich, England at that specific time) of the moon could be calculated. By comparing this with the angle of the moon over the horizon, the longitude could be calculated.
During Harrison's second trial of "H4" the Reverend Neville Maskelyne was asked to accompany HMS Tarter and test the Lunar Distances system. Once again "H4" proved almost astonishingly accurate, keeping time to within 39 seconds, corresponding to an error in the longitude of Bridgetown of less than 10 miles (16km). Maskelyne's measures were also fairly good, at 30 miles (48 km), 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 could not believe it was not just luck. Once again the matter reached Parliament, which offered £10,000 in advance 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.
Harrison began working on his H5 while the H4 testing was conducted, with H4 being effectively held hostage by the Board. After three years 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 obtained an audience by the King, who was extremely annoyed with the Board. King George tested H5 himself at the palace and after ten weeks of daily observations between May and July in 1772, found it to be accurate to within one third of one second per day. King George then advised Harrison to petition Parliament for the full prize after threatening to appear in person to dress them down. In 1773, when he was 80 years old, Harrison received a monetary award in the amount of £8,750 from Parliament for his achievements, but he never received the official award (which was never awarded to anyone). He was to survive for just three more years.
In total, Harrison received £23,065 for his work on chronometers. He received £4,315 in increments from the Board of Longitude for his work, £10,000 as an interim payment for H4 in 1765 and £8,750 from Parliament in 1773. This gave him a reasonable income for most of his life (equivalent to roughly £45,000 per year in 2007, though all his costs, such as materials and subcontracting work to other horologists, had to come out of this). He became the equivalent of a multi-millionaire (in today's terms) in the final decade of his life.
James Cook used K1, a copy of H4, on his second and third voyages, having used the Lunar distance method on his first voyage. K1 was made by Larcum Kendall, who had been apprenticed to John Jeffreys. Cook's log is full of praise for the watch and the charts of the southern Pacific Ocean John Jeffrey's made with its use were remarkably accurate. K2 was on HMS Bounty was recovered from Pitcairn Island, and then passed through several hands before reaching the National Maritime Museum in London.
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 restored in 1879 by the Worshipful Company of Clockmaker's 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 dedicated to Harrison on the wall of Summit House in the south side of the square. A memorial tablet to Harrison was unveiled in Westminister Abbey on 24 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, 7 minutes and 35 seconds West.
The Corpus Clock in Cambridge, unveiled in 2008, is an homage to Harrison's work. Harrison's grasshopper escapement — sculpted to resemble an actual grasshopper — is the clock's defining feature.
Though the British Parliament rewarded John Harrison for his marine chronometer in 1773, his chronometers were not to become standard. Chronometers such as those by Thomas Earnshaw, suitable for general nautical use by the end of the 18th century. However, they remained very expensive and the lunar distance method continued to be used for some decades.
Please visit my Funny Animal Art Prints Collection @ http://www.fabprints.com
My other website is called Directory of British Icons: http://fabprints.webs.com
The Chinese call Britain 'The Island of Hero's' which I think sums up what we British are all about. We British are inquisitive and competitive and are always looking over the horizon to the next adventure and discovery.
Copyright © 2010 Paul Hussey. All Rights Reserved.
John Harrison was born in Foulby near Wakefield in West Yorkshire the first of five children in his family. His father worked as a carpenter at the nearby Nostell Priory estate. The house where he was born bears a blue plaque.
Around 1700, the family moved to the North Lincolnshire village of Barrow upon humber. 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, spending hours listening to it and studying its moving parts.
In 1730 Harrison created a description and drawings for a proposed marine clock to compete for the
Longitude Prize and went to London seeking financial assistance. He presented his ideas to Edmond Halley, the Astronomer Royal. Halley referred him to George Graham the country's foremost clockmaker. He must have been impressed by Harrison, for Graham personally loaned Harrison money to build a model of his marine clock.
It took Harrison five years to build Harrison Number One or H1. He demonstrated it to members of the Royal Society who spoke on his behalf to the Board of Longitude. The clock was the first proposal that the Board considered to be worthy of a sea trial. In 1736, Harrison sailed to Lisbon on HMS Centurion and returned on HMS Oxford. On their return, both the captain and the sailing master of the Orford 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 for further development. Harrison moved on to develop H2, a more compact and rugged version. 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. In any event, Harrison suddenly abandoned all work on this second machine when he discovered a serious design flaw in the concept of the bar balances. He was granted another £500 by the Board while waiting for the war to end, which he used to work on H3. Harrison spent seventeen years working on this third 'sea clock' but despite every effort it seems not to have performed exactly as he would have wished. Despite this, it had proved a very valuable experiment. Certainly in this machine Harrison left the world two enduring legacies — the bimetallic strip and the caged roller bearing.
After steadfastly pursuing various methods during thirty years of experimentation, Harrison moved to London in the late 1750's where to his surprise he found that some of the watches made by Graham's successor Thomas Mudge kept time just as accurately as his huge sea clocks. Harrison then realized that a mere watch after all could be made accurate enough for the task and was a far more practical proposition for use as a marine timekeeper. He proceeded to redesign the concept of the watch as a timekeeping device, basing his design on sound scientific principles.
He had already in the early 1750's designed a precision watch for his own personal use, which was made for him by the watchmaker John Jefferys C. 1752 - 53. This watch incorporated a novel frictional rest escapement and was also probably the first to have both temperature compensation and a going fusee, enabling the watch to continue running whilst being wound. These features led to the very successful performance of this "Jefferys" watch and therefore Harrison incorporated them into the design of two new timekeepers which he proposed to build. These were in the form of a large watch and another of a smaller size but of similar pattern. However only the larger No. 1 (or "H4" as it sometimes called) watch appears ever to have been finished. (See the reference to "H6" below) Aided by some of London's finest workmen, he proceeded to design and make the world's first successful marine timekeeper that for the first time, allowed a navigator to accurately assess his ship's position in Longitude. Importantly, Harrison showed everyone that it could be done. This was to be Harrison's masterpiece — an instrument of beauty, resembling an oversized pocket watch from the period. It is engraved with Harrison's signature, marked Number 1 and dated 1759.
This first marine watch (or "Sea watch" as Harrison called it) is a 5.2" diameter watch in silver pair cases. The movement has a novel type of escapement which can be classed as a frictional rest type, and superficially resembles the verge escapement with which it is often incorrectly associated. The pallets of this escapement are both made of diamond, a considerable feat of manufacture at the time. The balance spring is a flat spiral but for technical reasons the balance itself was made much larger than in a conventional watch of the period. The movement also has centre seconds motion with a sweep seconds hand. The Third Wheel is equipped with internal teeth and has an elaborate bridge similar to the balance cocks of the period. It runs at 5 beats (ticks) per second, and is equipped with a tiny remontoire. A balance-brake stops the watch half an hour before it is completely run down, in order that the remontoire does not run down also. Temperature compensation is in the form of a 'compensation curb' (or 'Thermometer Kirb' as Harrison put it). This takes the form of a bimetallic strip mounted on the regulator sector-rack, and carrying the curb pins at the free end. During development of No.1, Harrison abandoned the regulator, but left the regulator disc in place for æsthetic reasons, and the compensation.
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 HMS Deptford reached Jamaica the watch was 5 seconds slow, corresponding to an error in longitude of 1.25 minutes, or approximately one nautical mile. When the ship returned, Harrison waited for the £20,000 prize but the Board believed the accuracy was 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 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 the day one left for Britain, the "proper position" (how it would appear in Greenwich, England at that specific time) of the moon could be calculated. By comparing this with the angle of the moon over the horizon, the longitude could be calculated.
During Harrison's second trial of "H4" the Reverend Neville Maskelyne was asked to accompany HMS Tarter and test the Lunar Distances system. Once again "H4" proved almost astonishingly accurate, keeping time to within 39 seconds, corresponding to an error in the longitude of Bridgetown of less than 10 miles (16km). Maskelyne's measures were also fairly good, at 30 miles (48 km), 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 could not believe it was not just luck. Once again the matter reached Parliament, which offered £10,000 in advance 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.
Harrison began working on his H5 while the H4 testing was conducted, with H4 being effectively held hostage by the Board. After three years 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 obtained an audience by the King, who was extremely annoyed with the Board. King George tested H5 himself at the palace and after ten weeks of daily observations between May and July in 1772, found it to be accurate to within one third of one second per day. King George then advised Harrison to petition Parliament for the full prize after threatening to appear in person to dress them down. In 1773, when he was 80 years old, Harrison received a monetary award in the amount of £8,750 from Parliament for his achievements, but he never received the official award (which was never awarded to anyone). He was to survive for just three more years.
In total, Harrison received £23,065 for his work on chronometers. He received £4,315 in increments from the Board of Longitude for his work, £10,000 as an interim payment for H4 in 1765 and £8,750 from Parliament in 1773. This gave him a reasonable income for most of his life (equivalent to roughly £45,000 per year in 2007, though all his costs, such as materials and subcontracting work to other horologists, had to come out of this). He became the equivalent of a multi-millionaire (in today's terms) in the final decade of his life.
James Cook used K1, a copy of H4, on his second and third voyages, having used the Lunar distance method on his first voyage. K1 was made by Larcum Kendall, who had been apprenticed to John Jeffreys. Cook's log is full of praise for the watch and the charts of the southern Pacific Ocean John Jeffrey's made with its use were remarkably accurate. K2 was on HMS Bounty was recovered from Pitcairn Island, and then passed through several hands before reaching the National Maritime Museum in London.
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 restored in 1879 by the Worshipful Company of Clockmaker's 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 dedicated to Harrison on the wall of Summit House in the south side of the square. A memorial tablet to Harrison was unveiled in Westminister Abbey on 24 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, 7 minutes and 35 seconds West.
The Corpus Clock in Cambridge, unveiled in 2008, is an homage to Harrison's work. Harrison's grasshopper escapement — sculpted to resemble an actual grasshopper — is the clock's defining feature.
Though the British Parliament rewarded John Harrison for his marine chronometer in 1773, his chronometers were not to become standard. Chronometers such as those by Thomas Earnshaw, suitable for general nautical use by the end of the 18th century. However, they remained very expensive and the lunar distance method continued to be used for some decades.
Please visit my Funny Animal Art Prints Collection @ http://www.fabprints.com
My other website is called Directory of British Icons: http://fabprints.webs.com
The Chinese call Britain 'The Island of Hero's' which I think sums up what we British are all about. We British are inquisitive and competitive and are always looking over the horizon to the next adventure and discovery.
Copyright © 2010 Paul Hussey. All Rights Reserved.
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