Ship's chronometer from HMS Beagle
Encyclopedia
A Nautical chronometer made by Thomas Earnshaw
(1749–1828), and once part of the equipment of HMS Beagle
, the ship that carried Charles Darwin
on his voyage around the world, is held in the British Museum
. The chronometer is object 91 in the BBC Radio 4
series A History of the World in 100 Objects
, scheduled to broadcast in September 2010.
it was being reported in The Nautical Magazine
that the price of chronometers was dropping rapidly while the same quality was being maintained. Earnshaws' chronometer had a novel escapement mechanism, the spring detent escapement, and a bimetallic strip for temperature compensation so that it would continue to maintain accuracy in all climates around the world.
The Beagle was sent in 1831 on a survey mission which involved circumnavigating the globe, a journey described by the naturalist on board the ship, Charles Darwin, in his book The Voyage of the Beagle
and which lasted until 1836. It was on this journey that Darwin began to form the ideas published much later as On the Origin of Species. The Beagle carried twenty-two chronometers, an unusually large number, but necessary to ensure accuracy of the survey. Three would have been commonplace on ships of the time, as this is the minimum number required to easily identify one that has gone faulty. The Admiralty
started a general issue of chronometers to H. M. Ships from 1825, but between about 1800 and 1840 the availability of chronometers could not keep up with the demand. The Admiralty therefore only issued one chronometer to each ship unless the Captain personally owned one. In those cases the Admiralty would issue a second machine to make the total up to three, reasoning that a ship with two was no better off than with one since in the event of a discrepancy it was not possible to identify the faulty instrument. The Beagle however, would be gone for several years and was required to take chronometers ashore and in boat expeditions up rivers to determine the coordinates of specific reference points as instructed by the Admiralty. It could not be guaranteed that any one chronometer would continue to function accurately, or even survive the journey at all. Each chronometer is mounted on gimbals to keep it level in all sea conditions and the whole assembly fixed inside a hinged wooden box for protection. For additional protection, they were stored in sawdust in a special cabin in the Captain's quarters. Only crew who needed to take measurements, or who maintained them, were allowed access, measures which indicate the importance attached to these instruments. The Beagle voyage succeeded, for the first time, in establishing a linked chain of reference points around the globe of known longitude which could be used by subsequent voyages to calibrate their own chronometers.
The chronometers were maintained by an instrument maker, one George James Stebbing, whose salary was paid for personally by the captain of the vessel, Robert FitzRoy
. FitzRoy considered the post to be essential to the mission but the Admiralty had refused to pay for it. FitzRoy bore the cost himself, as he did for much of the ship's equipment, but the Admiralty did concede that Stebbing could be fed from the ship's rations. This concession was not extended to Darwin, who paid £500 for his own keep.
Thomas Earnshaw's Marine Chronometer No.509 was manufactured around 1800 and served on a number of Royal Navy
ships. From 1823 to 1830 it was with HMS Hecla
. Under the command of George Francis Lyon
, Hecla had just returned from William Edward Parry
's second expedition to find the Northwest Passage
. Over 6,000 members of the public visited this ship at Deptford while she waited to set out on Parry's third expedition in 1824. This attempt was abandoned in 1825 after the leading ship, HMS Fury
had to be abandoned due to ice damage. Parry used Hecla again in an 1827 attempt to reach the North Pole. Parry unwillingly gave up Hecla when the admiralty sent her to survey the West African coast under the command of Captain J. Bolder. In July 1830 the chronometer was returned from Hecla and went for cleaning to Robert Molyneux in London. It was returned to Greenwich in November but not immediately issued to another ship. In March 1831 it was delivered to Devonport
where the rate was checked and recorded. In December 1831 it was issued to HMS Beagle. The chronometer served on several other Royal Navy vessels before finally being acquired by the British Museum.
Fitzroy was able to measure the overall accuracy of his entire journey by using his chronometers to measure the time of local noon when he returned to his home port. As he sailed west, local noon occurred progressively later, until finally, when he had circumnavigated the globe, the shift in local noon time, as measured by his chronometers should be exactly twenty-four hours. In fact, Fitzroy's measurements exceeded this by 33 seconds, which is equivalent to just 8.25 nautical miles (15.3 km). This was impressive for a journey of tens of thousands of miles over five years, but nevertheless Fitzroy considered the error to be inexplicably large.
Thomas Earnshaw
Thomas Earnshaw was an English watchmaker who following John Arnold's earlier work, further simplified the process of marine chronometer production, making them available to the general public...
(1749–1828), and once part of the equipment of HMS Beagle
HMS Beagle
HMS Beagle was a Cherokee-class 10-gun brig-sloop of the Royal Navy. She was launched on 11 May 1820 from the Woolwich Dockyard on the River Thames, at a cost of £7,803. In July of that year she took part in a fleet review celebrating the coronation of King George IV of the United Kingdom in which...
, the ship that carried Charles Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
on his voyage around the world, is held in the British Museum
British Museum
The British Museum is a museum of human history and culture in London. Its collections, which number more than seven million objects, are amongst the largest and most comprehensive in the world and originate from all continents, illustrating and documenting the story of human culture from its...
. The chronometer is object 91 in the BBC Radio 4
BBC Radio 4
BBC Radio 4 is a British domestic radio station, operated and owned by the BBC, that broadcasts a wide variety of spoken-word programmes, including news, drama, comedy, science and history. It replaced the BBC Home Service in 1967. The station controller is currently Gwyneth Williams, and the...
series A History of the World in 100 Objects
A History of the World in 100 Objects
A History of the World in 100 Objects was a joint project of BBC Radio 4 and the British Museum, comprising a 100-part radio series written and presented by British Museum director Neil MacGregor...
, scheduled to broadcast in September 2010.
Background
Nautical chronometers were of great importance in the 18th and 19th centuries as aids to navigation. Accurate measurement of time was needed for the determination of longitude. Earnshaw was not the first to make such chronometers, but he was one of the first to make them cheaply enough that they started to become essential equipment for a ship at sea. By the time the Beagle set sailSecond voyage of HMS Beagle
The second voyage of HMS Beagle, from 27 December 1831 to 2 October 1836, was the second survey expedition of HMS Beagle, under captain Robert FitzRoy who had taken over command of the ship on its first voyage after her previous captain committed suicide...
it was being reported in The Nautical Magazine
The Nautical Magazine
The Nautical Magazine is a monthly magazine published by Brown Son & Ferguson containing articles of general interest to seafarers. The magazine was first published in 1832 and has variously been known as The Nautical magazine and naval chronicle for ... and Nautical magazine and journal of the...
that the price of chronometers was dropping rapidly while the same quality was being maintained. Earnshaws' chronometer had a novel escapement mechanism, the spring detent escapement, and a bimetallic strip for temperature compensation so that it would continue to maintain accuracy in all climates around the world.
The Beagle was sent in 1831 on a survey mission which involved circumnavigating the globe, a journey described by the naturalist on board the ship, Charles Darwin, in his book The Voyage of the Beagle
The Voyage of the Beagle
The Voyage of the Beagle is a title commonly given to the book written by Charles Darwin and published in 1839 as his Journal and Remarks, bringing him considerable fame and respect...
and which lasted until 1836. It was on this journey that Darwin began to form the ideas published much later as On the Origin of Species. The Beagle carried twenty-two chronometers, an unusually large number, but necessary to ensure accuracy of the survey. Three would have been commonplace on ships of the time, as this is the minimum number required to easily identify one that has gone faulty. The Admiralty
Admiralty
The Admiralty was formerly the authority in the Kingdom of England, and later in the United Kingdom, responsible for the command of the Royal Navy...
started a general issue of chronometers to H. M. Ships from 1825, but between about 1800 and 1840 the availability of chronometers could not keep up with the demand. The Admiralty therefore only issued one chronometer to each ship unless the Captain personally owned one. In those cases the Admiralty would issue a second machine to make the total up to three, reasoning that a ship with two was no better off than with one since in the event of a discrepancy it was not possible to identify the faulty instrument. The Beagle however, would be gone for several years and was required to take chronometers ashore and in boat expeditions up rivers to determine the coordinates of specific reference points as instructed by the Admiralty. It could not be guaranteed that any one chronometer would continue to function accurately, or even survive the journey at all. Each chronometer is mounted on gimbals to keep it level in all sea conditions and the whole assembly fixed inside a hinged wooden box for protection. For additional protection, they were stored in sawdust in a special cabin in the Captain's quarters. Only crew who needed to take measurements, or who maintained them, were allowed access, measures which indicate the importance attached to these instruments. The Beagle voyage succeeded, for the first time, in establishing a linked chain of reference points around the globe of known longitude which could be used by subsequent voyages to calibrate their own chronometers.
The chronometers were maintained by an instrument maker, one George James Stebbing, whose salary was paid for personally by the captain of the vessel, Robert FitzRoy
Robert FitzRoy
Vice-Admiral Robert FitzRoy RN achieved lasting fame as the captain of HMS Beagle during Charles Darwin's famous voyage, and as a pioneering meteorologist who made accurate weather forecasting a reality...
. FitzRoy considered the post to be essential to the mission but the Admiralty had refused to pay for it. FitzRoy bore the cost himself, as he did for much of the ship's equipment, but the Admiralty did concede that Stebbing could be fed from the ship's rations. This concession was not extended to Darwin, who paid £500 for his own keep.
Thomas Earnshaw's Marine Chronometer No.509 was manufactured around 1800 and served on a number of Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
ships. From 1823 to 1830 it was with HMS Hecla
HMS Hecla (1815)
HMS Hecla was a Royal Navy Hecla-class bomb vessel of 372 tons. Launched on 15 July 1815, she saw wartime service in an attack on Barbary pirates at Algiers in August, 1816...
. Under the command of George Francis Lyon
George Francis Lyon
George Francis Lyon was a rare combination of Arctic and African explorer. By all accounts a fun loving extrovert, he also managed to be a competent British Naval Officer, Commander, explorer, artist and socialite...
, Hecla had just returned from William Edward Parry
William Edward Parry
Sir William Edward Parry was an English rear-admiral and Arctic explorer, who in 1827 attempted one of the earliest expeditions to the North Pole...
's second expedition to find the Northwest Passage
Northwest Passage
The Northwest Passage is a sea route through the Arctic Ocean, along the northern coast of North America via waterways amidst the Canadian Arctic Archipelago, connecting the Atlantic and Pacific Oceans...
. Over 6,000 members of the public visited this ship at Deptford while she waited to set out on Parry's third expedition in 1824. This attempt was abandoned in 1825 after the leading ship, HMS Fury
HMS Fury (1814)
HMS Fury was a Hecla-class bomb vessel. Built in the 1810s, she saw wartime service in an attack on Barbary pirates at Algiers in August, 1816, captained by Constantine Richard Moorsom. The ship after it left his command was converted to an Arctic exploration ship.The Fury made two journeys to the...
had to be abandoned due to ice damage. Parry used Hecla again in an 1827 attempt to reach the North Pole. Parry unwillingly gave up Hecla when the admiralty sent her to survey the West African coast under the command of Captain J. Bolder. In July 1830 the chronometer was returned from Hecla and went for cleaning to Robert Molyneux in London. It was returned to Greenwich in November but not immediately issued to another ship. In March 1831 it was delivered to Devonport
Devonport, Devon
Devonport, formerly named Plymouth Dock or just Dock, is a district of Plymouth in the English county of Devon, although it was, at one time, the more important settlement. It became a county borough in 1889...
where the rate was checked and recorded. In December 1831 it was issued to HMS Beagle. The chronometer served on several other Royal Navy vessels before finally being acquired by the British Museum.
Fitzroy was able to measure the overall accuracy of his entire journey by using his chronometers to measure the time of local noon when he returned to his home port. As he sailed west, local noon occurred progressively later, until finally, when he had circumnavigated the globe, the shift in local noon time, as measured by his chronometers should be exactly twenty-four hours. In fact, Fitzroy's measurements exceeded this by 33 seconds, which is equivalent to just 8.25 nautical miles (15.3 km). This was impressive for a journey of tens of thousands of miles over five years, but nevertheless Fitzroy considered the error to be inexplicably large.
Further reading
- David Thompson, Saul Peckham, Clocks, London, The British Museum Press, 2004 ISBN 0714128120.
- Rupert T. Gould, The Marine Chronometer, Holland Press 1960
- William J. H. Andrewes, The Quest for Longitude, Collection of Historical and Scientific Instruments (US)1996
- Anthony Randall, Richard Good, Catalogue of Watches in the British Museum: Volume 6, Pocket Chronometers, Marine Chronometers and Other Portable Precision Timekeepers, The British Museum Press, 1990 ISBN 0714105511.