John Harrison (24 March 1693 – 24 March 1776) was a self-educated English clockmaker. He 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 £2.87 million / €3.65 million / $4.72 million in modern currency) for the solution.
Harrison came 39th in the BBC's 2002 public poll of the 100 Greatest Britons.
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.
He also had a fascination for music, eventually becoming choirmaster for Barrow parish church.
Harrison built his first longcase clock in 1713, at the age of 20. The mechanism was made entirely of wood, which was a natural choice of material for a joiner. Three of Harrison's early wooden clocks have survived; the first (1713) is at the Worshipful Company of Clockmakers' Collection in Guildhall; the second (1715), is in the Science Museum and the third (1717) is at Nostell Priory in Yorkshire, the face bearing the inscription "John Harrison Barrow".
He was a man of many skills and used these to systematically improve the performance of pendulum clocks. He invented the gridiron pendulum, consisting of alternating brass and iron rods assembled so that the different expansions and contractions cancel each other out. Another example of his inventive genius was the grasshopper escapement — a control device for the step-by-step release of a clock's driving power. Developed from the anchor escapement, it was almost frictionless, requiring no lubrication because the pallets were made from the wood lignum vitae. This was an important advantage at a time when lubricants and their degradation were little understood. It is not often recognized that in his earlier work on the "Sea clocks" Harrison was continually assisted both financially and in many other ways by George Graham, the watchmaker and instrument maker who lent him a large sum on the basis of trust even after Harrison's first visit to Graham in 1728 to explain how his timekeeper worked. Harrison was introduced to Graham by the Astronomer Royal Edmond Halley who also championed Harrison and his work. This support was important as Harrison is reputed to have found it difficult to communicate his ideas in a coherent manner.
Longitude
A longitude describes the location of a place on Earth east or west of a north-south line called the Prime Meridian. Longitude is given as an angular measurement ranging from 0° at the Prime Meridian to +180° eastward and −180° westward. Many solutions were proposed for how to determine longitude at the end of an exploratory sea voyage and hence the longitude of the place that was visited (in case one would want to revisit or place it on a map). The practical methods relied on a comparison of local time with the time at a given place (such as Greenwich or Paris). Many of these methods relied on astronomical observations relying on the predictable, "clockwork" nature of motions of heavenly bodies.
Harrison instead set out to solve the problem in a direct way: by producing a reliable clock. The theory was simple and had been first proposed by Frisius. The difficulty, however, was in producing a clock which could maintain accurate time on a lengthy, rough sea voyage with widely-varying conditions of temperature, pressure and humidity. Frisius had realized that to determine longitude, a clock would have to be “of great exactness”. Many leading scientists including Newton and Huygens doubted that such a clock could ever be built and had more optimism for astronomical observations (such as the Method of Lunar Distances). Huygens ran trials using both a pendulum and a spiral balance spring clock as methods of determining longitude. Although both types showed some favourable results, they were both prone to fickleness. Newton observed that “A good watch may serve to keep a reckoning at sea for some days and to know the time of a celestial observation; and for this end a good Jewel may suffice till a better sought of watch can be found out. But when longitude at sea is lost, it cannot be found again by any watch.” However, if such a clock were built and 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, regardless of where you had traveled. By referring to the clock when it is noon locally (i.e. the Sun is at its highest in the sky where you are) you can read, almost directly from the clock face, how far around the world you are from London. For instance, if the clock shows that it is midnight in London when it is noon locally, then you are half way round the world, (e.g. 180 degrees of longitude) from London.
He had already in the early 1750s 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 Maintaining Power, enabling the watch to continue running while 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 pierced and engraved bridge for 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 regulating slide, and carrying the curb pins at the free end. During development of No.1, Harrison dispensed with this regulation using the slide, but left its indicating dial or figure piece in place.
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 Nevil Maskelyne was asked to accompany HMS Tartar 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 (16 km). 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.
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 "going 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. Consequently, the H4 failed the needs of the Board despite the fact that it actually succeeded in two previous trials.
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 Jefferys. 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. K2 was on HMS Bounty, was recovered from Pitcairn Island, and then passed through several hands before reaching the National Maritime Museum in London.
http://en.wikipedia.org/wiki/John_Harrison
Harrison came 39th in the BBC's 2002 public poll of the 100 Greatest Britons.
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.
He also had a fascination for music, eventually becoming choirmaster for Barrow parish church.
Harrison built his first longcase clock in 1713, at the age of 20. The mechanism was made entirely of wood, which was a natural choice of material for a joiner. Three of Harrison's early wooden clocks have survived; the first (1713) is at the Worshipful Company of Clockmakers' Collection in Guildhall; the second (1715), is in the Science Museum and the third (1717) is at Nostell Priory in Yorkshire, the face bearing the inscription "John Harrison Barrow".
He was a man of many skills and used these to systematically improve the performance of pendulum clocks. He invented the gridiron pendulum, consisting of alternating brass and iron rods assembled so that the different expansions and contractions cancel each other out. Another example of his inventive genius was the grasshopper escapement — a control device for the step-by-step release of a clock's driving power. Developed from the anchor escapement, it was almost frictionless, requiring no lubrication because the pallets were made from the wood lignum vitae. This was an important advantage at a time when lubricants and their degradation were little understood. It is not often recognized that in his earlier work on the "Sea clocks" Harrison was continually assisted both financially and in many other ways by George Graham, the watchmaker and instrument maker who lent him a large sum on the basis of trust even after Harrison's first visit to Graham in 1728 to explain how his timekeeper worked. Harrison was introduced to Graham by the Astronomer Royal Edmond Halley who also championed Harrison and his work. This support was important as Harrison is reputed to have found it difficult to communicate his ideas in a coherent manner.
Longitude
A longitude describes the location of a place on Earth east or west of a north-south line called the Prime Meridian. Longitude is given as an angular measurement ranging from 0° at the Prime Meridian to +180° eastward and −180° westward. Many solutions were proposed for how to determine longitude at the end of an exploratory sea voyage and hence the longitude of the place that was visited (in case one would want to revisit or place it on a map). The practical methods relied on a comparison of local time with the time at a given place (such as Greenwich or Paris). Many of these methods relied on astronomical observations relying on the predictable, "clockwork" nature of motions of heavenly bodies.
Harrison instead set out to solve the problem in a direct way: by producing a reliable clock. The theory was simple and had been first proposed by Frisius. The difficulty, however, was in producing a clock which could maintain accurate time on a lengthy, rough sea voyage with widely-varying conditions of temperature, pressure and humidity. Frisius had realized that to determine longitude, a clock would have to be “of great exactness”. Many leading scientists including Newton and Huygens doubted that such a clock could ever be built and had more optimism for astronomical observations (such as the Method of Lunar Distances). Huygens ran trials using both a pendulum and a spiral balance spring clock as methods of determining longitude. Although both types showed some favourable results, they were both prone to fickleness. Newton observed that “A good watch may serve to keep a reckoning at sea for some days and to know the time of a celestial observation; and for this end a good Jewel may suffice till a better sought of watch can be found out. But when longitude at sea is lost, it cannot be found again by any watch.” However, if such a clock were built and 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, regardless of where you had traveled. By referring to the clock when it is noon locally (i.e. the Sun is at its highest in the sky where you are) you can read, almost directly from the clock face, how far around the world you are from London. For instance, if the clock shows that it is midnight in London when it is noon locally, then you are half way round the world, (e.g. 180 degrees of longitude) from London.
He had already in the early 1750s 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 Maintaining Power, enabling the watch to continue running while 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 pierced and engraved bridge for 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 regulating slide, and carrying the curb pins at the free end. During development of No.1, Harrison dispensed with this regulation using the slide, but left its indicating dial or figure piece in place.
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 Nevil Maskelyne was asked to accompany HMS Tartar 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 (16 km). 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.
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 "going 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. Consequently, the H4 failed the needs of the Board despite the fact that it actually succeeded in two previous trials.
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 Jefferys. 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. K2 was on HMS Bounty, was recovered from Pitcairn Island, and then passed through several hands before reaching the National Maritime Museum in London.
http://en.wikipedia.org/wiki/John_Harrison
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