George Biddell Airy
Encyclopedia
Sir George Biddell Airy PRS
KCB
(27 July 1801 – 2 January 1892) was an English mathematician
and astronomer
, Astronomer Royal
from 1835 to 1881. His many achievements include work on planet
ary orbit
s, measuring the mean density of the Earth, a method of solution of two-dimensional problems in solid mechanics
and, in his role as Astronomer Royal, establishing Greenwich
as the location of the prime meridian
. His reputation has been tarnished by allegations that, through his inaction, Britain lost the opportunity of priority in the discovery of Neptune
.
, one of a long line of Airys who traced their descent back to a family of the same name residing at Kentmere
, in Westmorland
, in the 14th century. The branch to which he belonged, having suffered in the English Civil War
, moved to Lincolnshire
and became farmers. Airy was educated first at elementary schools in Hereford
, and afterwards at Colchester Royal Grammar School
. An introverted child, Airy gained popularity with his schoolmates through his great skill in the construction of peashooters.
From the age of 13, Airy stayed frequently with his uncle, Arthur Biddell at Playford, Suffolk
. Biddell introduced Airy to his friend Thomas Clarkson
, the slave trade abolitionist who lived at Playford Hall. Clarkson had an MA in mathematics from Cambridge, and examined Airy in classics and then subsequently arranged for him to be examined by a Fellow from Trinity College, Cambridge
on his knowledge of mathematics. As a result he entered Trinity in 1819, as a sizar
, meaning that he paid a reduced fee but essentially worked as a servant to make good the fee reduction. Here he had a brilliant career, and seems to have been almost immediately recognised as the leading man of his year. In 1822 he was elected scholar of Trinity, and in the following year he graduated as senior wrangler and obtained first Smith's prize
. On 1 October 1824 he was elected fellow of Trinity, and in December 1826 was appointed Lucasian professor of mathematics
in succession to Thomas Turton
. This chair he held for little more than a year, being elected in February 1828 Plumian professor
of astronomy
and director of the new Cambridge Observatory
. In 1836 he was elected a Fellow of the Royal Society and in 1840, a foreign member of the Royal Swedish Academy of Sciences
.
, and eight to the Cambridge Philosophical Society
. At the Cambridge observatory Airy soon showed his power of organisation. The only telescope
in the establishment when he took charge was the transit instrument, and to this he vigorously devoted himself. By the adoption of a regular system of work, and a careful plan of reduction, he was able to keep his observations up to date, and published them annually with a punctuality which astonished his contemporaries. Before long a mural circle was installed, and regular observations were instituted with it in 1833. In the same year the Duke of Northumberland
presented the Cambridge observatory with a fine object-glass of 12-inch aperture, which was mounted according to Airy's designs and under his superintendence, although construction was not completed until after he moved to Greenwich
in 1835.
Airy's writings during this time are divided between mathematical physics and astronomy. The former are for the most part concerned with questions relating to the theory of light arising out of his professorial lectures, among which may be specially mentioned his paper On the Diffraction of an Object-Glass with Circular Aperture, and his enunciation of the complete theory of the rainbow
. In 1831 the Copley Medal
of the Royal Society was awarded to him for these researches. Of his astronomical writings during this period the most important are his investigation of the mass of Jupiter
, his report to the British Association on the progress of astronomy during the 19th century, and his work On an Inequality of Long Period in the Motions of the Earth
and Venus
.
One of the sections of his able and instructive report was devoted to "A Comparison of the Progress of Astronomy in England with that in other Countries," very much to the disadvantage of England. This reproach was subsequently to a great extent removed by his own labours.
s a multiplier of about 2,200,000, Airy was led to infer the existence of a sensible inequality extending over 240 years (Phil. Trans. cxxii. 67). The investigation was probably the most laborious that had been made up to Airy's time in planet
ary theory, and represented the first specific improvement in the solar tables effected in England since the establishment of the theory of gravitation
. In recognition of this work the Gold Medal of the Royal Astronomical Society
was awarded to him in 1833 (he would win it again in 1846).
in succession to John Pond
, and began his long career at the national observatory which constitutes his chief title to fame. The condition of the observatory at the time of his appointment was such that Lord Auckland
, the first Lord of the Admiralty, considered that "it ought to be cleared out," while Airy admitted that "it was in a queer state." With his usual energy he set to work at once to reorganise the whole management. He remodelled the volumes of observations, put the library on a proper footing, mounted the new (Sheepshanks
) equatorial
and organised a new magnetic observatory. In 1847 an altazimuth was erected, designed by Airy to enable observations of the moon
to be made not only on the meridian
, but whenever it might be visible. In 1848 Airy invented the reflex zenith tube to replace the zenith sector previously employed. At the end of 1850 the great transit circle of 203 mm (8 inch) aperture and 3.5 m (11 ft 6 in) focal length
was erected, and is still the principal instrument of its class at the observatory. The mounting in 1859 of an equatorial of 330 mm (13 inch) aperture evoked the comment in his journal for that year, "There is not now a single person employed or instrument used in the observatory which was there in Mr Pond's time"; and the transformation was completed by the inauguration of spectroscopic work in 1868 and of the photographic registration of sunspots in 1873.
The formidable undertaking of reducing the accumulated planetary observations made at Greenwich from 1750 to 1830 was already in progress under Airy's supervision when he became Astronomer Royal. Shortly afterwards he undertook the further laborious task of reducing the enormous mass of observations of the moon made at Greenwich during the same period under the direction, successively, of James Bradley
, Nathaniel Bliss
, Nevil Maskelyne
and John Pond, to defray the expense of which a large sum of money was allotted by the Treasury. As a result, no less than 8,000 lunar observations were rescued from oblivion, and were, in 1846, placed at the disposal of astronomers in such a form that they could be used directly for comparison with the theory and for the improvement of the tables of the moon's motion.
For this work Airy received in 1848 a testimonial from the Royal Astronomical Society
, and it at once led to the discovery by Peter Andreas Hansen
of two new inequalities in the moon's motion. After completing these reductions, Airy made inquiries, before engaging in any theoretical investigation in connection with them, whether any other mathematician was pursuing the subject, and learning that Hansen had taken it in hand under the patronage of the king of Denmark, but that, owing to the death of the king and the consequent lack of funds, there was danger of his being compelled to abandon it, he applied to the admiralty on Hansen's behalf for the necessary sum. His request was immediately granted, and thus it came about that Hansen's famous Tables de la Lune were dedicated to La Haute Amirauté de sa Majesté la Reine de la Grande Bretagne et d'Irlande.
In 1851 Airy established a new Prime Meridian
at Greenwich. This line, the fourth "Greenwich Meridian," became the definitive internationally recognised line in 1884.
were due to a so-far unobserved body. Aware that Cambridge Astronomer John Couch Adams
had suggested that he had made similar predictions, on 9 July Airy entreated James Challis
to undertake a systematic search in the hope of securing the triumph of discovery for Britain. Ultimately, a rival search in Berlin by Johann Gottfried Galle
, instigated by Le Verrier, won the race for priority. Though Airy was "abused most savagely both by English and French" for his failure to act on Adams's suggestions more promptly, there have also been claims that Adams's communications had been vague and dilatory and further that the search for a new planet was not the responsibility of the Astronomer Royal.
experiments at the top and bottom of a deep mine
. His first attempt, made in the same year, at the Dolcoath mine
in Cornwall, failed in consequence of an accident to one of the pendulum
s. A second attempt in 1828 was defeated by a flooding of the mine, and many years elapsed before another opportunity presented itself. The experiments eventually took place at the Harton pit near South Shields
in 1854. Their immediate result was to show that gravity at the bottom of the mine exceeded that at the top by 1/19286 of its amount, the depth being 383 m (1,256 ft) From this he was led to the final value of Earth's specific density of 6.566. This value, although considerably in excess of that previously found by different methods, was held by Airy, from the care and completeness with which the observations were carried out and discussed, to be "entitled to compete with the others on, at least, equal terms." (The currently accepted value for Earth's density is 5.5153 g/cm³.)
, Airy in 1871 looked for a change in stellar aberration through the refracting water due to an ether drag
. Like in all other aether drift experiments, he obtained a negative result.
's final numerical expressions for longitude
, latitude
, and parallax
, with a symbolic term attached to each number, the value of which was to be determined by substitution in the equations of motion.
In this mode of treating the question the order of the terms is numerical, and though the amount of labour is such as might well have deterred a younger man, yet the details were easy, and a great part of it might be entrusted to "a mere computer". (Note that at the time that this was written, the term "computer" referred to a human being who performed calculating work, either manually or with mechanical aids).
The work was published in 1886, when its author was eighty-five years of age. For some little time previously he had been harassed by a suspicion that certain errors had crept into the computations, and accordingly he addressed himself to the task of revision. But his powers were no longer what they had been, and he was never able to examine sufficiently into the matter. In 1890 he tells us how a grievous error had been committed in one of the first steps, and pathetically adds, "My spirit in the work was broken, and I have never heartily proceeded with it since."
In 1862, Airy presented a new technique to determine the strain
and stress
field within a beam. This technique, sometimes called the Airy stress function method, can be used to find solutions to many two-dimensional problems in solid mechanics
(see Wikiversity). For example, it was used by H. M. Westergaard to determine the stress and strain field around a crack tip and thereby this method contributed to the development of fracture mechanics
.
Airy was consulted about wind speeds and pressures likely to be encountered on the proposed Forth suspension bridge being designed by Thomas Bouch
for the North British Railway
in the late 1870s. He thought that pressures no greater than about 10 pounds per square foot could be expected, a comment Bouch took to mean also applied to the first Tay railway bridge then being built. Much greater pressures however, can be expected in severe storms. Airy was called to give evidence before the Official Inquiry into the Tay Bridge disaster
, and was criticised for his advice. However, little was known about the problems of wind resistance of large structures, and a Royal Commission on Wind Pressure was asked to conduct research into the problem.
In July 1824, Airy met Richarda Smith (1804–1875), "a great beauty", on a walking tour of Derbyshire
. He later wrote, "Our eyes met ... and my fate was sealed ... I felt irresistibly that we must be united," and Airy proposed two days later. Richarda's father, the Revd Richard Smith, felt that Airy lacked the financial resources to marry his daughter. Only in 1830, with Airy established in his Cambridge position, was permission for the marriage granted.
The Airys had nine children, the eldest three dying in childhood. The eldest survivor, Wilfrid Airy, was the designer and engineer for "Colonel" George Tomline's Orwell Park observatory
. Wilfrid's daughter was the artist Anna Airy
.
Their eldest daughter, Hilda (1840–1916), married Edward Routh
in 1864.
Airy retired in 1881, living with his two married daughters at Croom's Hill near Greenwich. In 1891, he suffered a fall and an internal injury. He survived the consequential surgery only a few days. His wealth at death was £27,713. Airy and his wife and three pre-deceased children are buried at St. Mary's Church in Playford, Suffolk
. A cottage owned by Airy still stands, adjacent to the church and now in private hands.
President of the Royal Society
The president of the Royal Society is the elected director of the Royal Society of London. After informal meetings at Gresham College, the Royal Society was founded officially on 15 July 1662 for the encouragement of ‘philosophical studies’, by a royal charter which nominated William Brouncker as...
KCB
Order of the Bath
The Most Honourable Order of the Bath is a British order of chivalry founded by George I on 18 May 1725. The name derives from the elaborate mediæval ceremony for creating a knight, which involved bathing as one of its elements. The knights so created were known as Knights of the Bath...
(27 July 1801 – 2 January 1892) was an English mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
and astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
, Astronomer Royal
Astronomer Royal
Astronomer Royal is a senior post in the Royal Household of the Sovereign of the United Kingdom. There are two officers, the senior being the Astronomer Royal dating from 22 June 1675; the second is the Astronomer Royal for Scotland dating from 1834....
from 1835 to 1881. His many achievements include work on planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
ary orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
s, measuring the mean density of the Earth, a method of solution of two-dimensional problems in solid mechanics
Solid mechanics
Solid mechanics is the branch of mechanics, physics, and mathematics that concerns the behavior of solid matter under external actions . It is part of a broader study known as continuum mechanics. One of the most common practical applications of solid mechanics is the Euler-Bernoulli beam equation...
and, in his role as Astronomer Royal, establishing Greenwich
Greenwich
Greenwich is a district of south London, England, located in the London Borough of Greenwich.Greenwich is best known for its maritime history and for giving its name to the Greenwich Meridian and Greenwich Mean Time...
as the location of the prime meridian
Prime Meridian
The Prime Meridian is the meridian at which the longitude is defined to be 0°.The Prime Meridian and its opposite the 180th meridian , which the International Date Line generally follows, form a great circle that divides the Earth into the Eastern and Western Hemispheres.An international...
. His reputation has been tarnished by allegations that, through his inaction, Britain lost the opportunity of priority in the discovery of Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...
.
Biography
Airy was born at AlnwickAlnwick
Alnwick is a small market town in north Northumberland, England. The town's population was just over 8000 at the time of the 2001 census and Alnwick's district population was 31,029....
, one of a long line of Airys who traced their descent back to a family of the same name residing at Kentmere
Kentmere
Kentmere is a valley, village and civil parish in the Lake District National Park, a few miles from Kendal in the South Lakeland district of Cumbria, England. It is historically part of Westmorland...
, in Westmorland
Westmorland
Westmorland is an area of North West England and one of the 39 historic counties of England. It formed an administrative county from 1889 to 1974, after which the entirety of the county was absorbed into the new county of Cumbria.-Early history:...
, in the 14th century. The branch to which he belonged, having suffered in the English Civil War
English Civil War
The English Civil War was a series of armed conflicts and political machinations between Parliamentarians and Royalists...
, moved to Lincolnshire
Lincolnshire
Lincolnshire is a county in the east of England. It borders Norfolk to the south east, Cambridgeshire to the south, Rutland to the south west, Leicestershire and Nottinghamshire to the west, South Yorkshire to the north west, and the East Riding of Yorkshire to the north. It also borders...
and became farmers. Airy was educated first at elementary schools in Hereford
Hereford
Hereford is a cathedral city, civil parish and county town of Herefordshire, England. It lies on the River Wye, approximately east of the border with Wales, southwest of Worcester, and northwest of Gloucester...
, and afterwards at Colchester Royal Grammar School
Colchester Royal Grammar School
Colchester Royal Grammar School is a grammar school in Colchester, Essex, founded in AD 1206 and granted two Royal Charters by Henry VIII and by Elizabeth I .-Admissions:...
. An introverted child, Airy gained popularity with his schoolmates through his great skill in the construction of peashooters.
From the age of 13, Airy stayed frequently with his uncle, Arthur Biddell at Playford, Suffolk
Playford, Suffolk
Playford is a small village in Suffolk, England, on the outskirts of Ipswich. It has about 220 residents in 90 households. The River Fynn runs through the village, and many footpaths from Playford lead into the Fynn Valley. Villages nearby include Rushmere, Little Bealings, Great Bealings, Culpho...
. Biddell introduced Airy to his friend Thomas Clarkson
Thomas Clarkson
Thomas Clarkson , was an English abolitionist, and a leading campaigner against the slave trade in the British Empire. He helped found The Society for Effecting the Abolition of the Slave Trade and helped achieve passage of the Slave Trade Act of 1807, which ended British trade in slaves...
, the slave trade abolitionist who lived at Playford Hall. Clarkson had an MA in mathematics from Cambridge, and examined Airy in classics and then subsequently arranged for him to be examined by a Fellow from Trinity College, Cambridge
Trinity College, Cambridge
Trinity College is a constituent college of the University of Cambridge. Trinity has more members than any other college in Cambridge or Oxford, with around 700 undergraduates, 430 graduates, and over 170 Fellows...
on his knowledge of mathematics. As a result he entered Trinity in 1819, as a sizar
Sizar
At Trinity College, Dublin and the University of Cambridge, a sizar is a student who receives some form of assistance such as meals, lower fees or lodging during his or her period of study, in some cases in return for doing a defined job....
, meaning that he paid a reduced fee but essentially worked as a servant to make good the fee reduction. Here he had a brilliant career, and seems to have been almost immediately recognised as the leading man of his year. In 1822 he was elected scholar of Trinity, and in the following year he graduated as senior wrangler and obtained first Smith's prize
Smith's Prize
The Smith's Prize was the name of each of two prizes awarded annually to two research students in theoretical Physics, mathematics and applied mathematics at the University of Cambridge, Cambridge, England.- History :...
. On 1 October 1824 he was elected fellow of Trinity, and in December 1826 was appointed Lucasian professor of mathematics
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...
in succession to Thomas Turton
Thomas Turton
Thomas Turton, DD was the Lucasian Professor of Mathematics at the University of Cambridge. He was Dean of Peterborough, Bishop of Ely and composer of Anglican hymns....
. This chair he held for little more than a year, being elected in February 1828 Plumian professor
Plumian Professor of Astronomy and Experimental Philosophy
The Plumian chair of Astronomy and Experimental Philosophy is one of the two major Professorships in Astronomy at Cambridge University, alongside the Lowndean Professorship. The chair is currently held at the Institute of Astronomy in the University...
of astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
and director of the new Cambridge Observatory
Cambridge Observatory
Cambridge Observatory is an astronomical observatory at the University of Cambridge in the East of England. It was first established in 1823 and is now part of the site of the Institute of Astronomy...
. In 1836 he was elected a Fellow of the Royal Society and in 1840, a foreign member of the Royal Swedish Academy of Sciences
Royal Swedish Academy of Sciences
The Royal Swedish Academy of Sciences or Kungliga Vetenskapsakademien is one of the Royal Academies of Sweden. The Academy is an independent, non-governmental scientific organization which acts to promote the sciences, primarily the natural sciences and mathematics.The Academy was founded on 2...
.
Research
Some idea of his activity as a writer on mathematical and physical subjects during these early years may be gathered from the fact that previous to this appointment he had contributed no less than three important memoirs to the Philosophical Transactions of the Royal SocietyRoyal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
, and eight to the Cambridge Philosophical Society
Cambridge Philosophical Society
The Cambridge Philosophical Society is a scientific society at University of Cambridge. It was founded in 1819. The name derives from the medieval use of the word philosophy to denote any research undertaken outside the fields of theology and medicine...
. At the Cambridge observatory Airy soon showed his power of organisation. The only telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...
in the establishment when he took charge was the transit instrument, and to this he vigorously devoted himself. By the adoption of a regular system of work, and a careful plan of reduction, he was able to keep his observations up to date, and published them annually with a punctuality which astonished his contemporaries. Before long a mural circle was installed, and regular observations were instituted with it in 1833. In the same year the Duke of Northumberland
Hugh Percy, 3rd Duke of Northumberland
Hugh Percy, 3rd Duke of Northumberland KG, PC , styled Earl Percy until 1817, was a British aristocrat and Tory politician who served as Lord Lieutenant of Ireland under the Duke of Wellington from 1829 to 1830....
presented the Cambridge observatory with a fine object-glass of 12-inch aperture, which was mounted according to Airy's designs and under his superintendence, although construction was not completed until after he moved to Greenwich
Greenwich
Greenwich is a district of south London, England, located in the London Borough of Greenwich.Greenwich is best known for its maritime history and for giving its name to the Greenwich Meridian and Greenwich Mean Time...
in 1835.
Airy's writings during this time are divided between mathematical physics and astronomy. The former are for the most part concerned with questions relating to the theory of light arising out of his professorial lectures, among which may be specially mentioned his paper On the Diffraction of an Object-Glass with Circular Aperture, and his enunciation of the complete theory of the rainbow
Rainbow
A rainbow is an optical and meteorological phenomenon that causes a spectrum of light to appear in the sky when the Sun shines on to droplets of moisture in the Earth's atmosphere. It takes the form of a multicoloured arc...
. In 1831 the Copley Medal
Copley Medal
The Copley Medal is an award given by the Royal Society of London for "outstanding achievements in research in any branch of science, and alternates between the physical sciences and the biological sciences"...
of the Royal Society was awarded to him for these researches. Of his astronomical writings during this period the most important are his investigation of the mass of Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
, his report to the British Association on the progress of astronomy during the 19th century, and his work On an Inequality of Long Period in the Motions of the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
and Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...
.
One of the sections of his able and instructive report was devoted to "A Comparison of the Progress of Astronomy in England with that in other Countries," very much to the disadvantage of England. This reproach was subsequently to a great extent removed by his own labours.
Planetary inequalities
Airy's discovery of a new inequality in the motions of Venus and the Earth is in some respects his most remarkable achievement. In correcting the elements of Delambre's solar tables he had been led to suspect an inequality overlooked by their constructor. The cause of this he did not long seek in vain; eight times the mean motion of Venus is so nearly equal to thirteen times that of the earth that the difference amounts to only a small fraction of the Earth's mean motion, and from the fact that the term depending on this difference, although very small in itself, receives in the integration of the differential equationDifferential equation
A differential equation is a mathematical equation for an unknown function of one or several variables that relates the values of the function itself and its derivatives of various orders...
s a multiplier of about 2,200,000, Airy was led to infer the existence of a sensible inequality extending over 240 years (Phil. Trans. cxxii. 67). The investigation was probably the most laborious that had been made up to Airy's time in planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
ary theory, and represented the first specific improvement in the solar tables effected in England since the establishment of the theory of gravitation
Gravitation
Gravitation, or gravity, is a natural phenomenon by which physical bodies attract with a force proportional to their mass. Gravitation is most familiar as the agent that gives weight to objects with mass and causes them to fall to the ground when dropped...
. In recognition of this work the Gold Medal of the Royal Astronomical Society
Gold Medal of the Royal Astronomical Society
-History:In the early years, more than one medal was often awarded in a year, but by 1833 only one medal was being awarded per year. This caused a problem when Neptune was discovered in 1846, because many felt an award should jointly be made to John Couch Adams and Urbain Le Verrier...
was awarded to him in 1833 (he would win it again in 1846).
Astronomer Royal
In June 1835 Airy was appointed Astronomer RoyalAstronomer Royal
Astronomer Royal is a senior post in the Royal Household of the Sovereign of the United Kingdom. There are two officers, the senior being the Astronomer Royal dating from 22 June 1675; the second is the Astronomer Royal for Scotland dating from 1834....
in succession to John Pond
John Pond
John Pond FRS was a renowned English astronomer who became the sixth Astronomer Royal, serving from 1811 to 1835.- Biography :...
, and began his long career at the national observatory which constitutes his chief title to fame. The condition of the observatory at the time of his appointment was such that Lord Auckland
George Eden, 1st Earl of Auckland
George Eden, 1st Earl of Auckland, GCB, PC was a British Whig politician and colonial administrator. He was thrice First Lord of the Admiralty and also served as Governor-General of India between 1836 and 1842....
, the first Lord of the Admiralty, considered that "it ought to be cleared out," while Airy admitted that "it was in a queer state." With his usual energy he set to work at once to reorganise the whole management. He remodelled the volumes of observations, put the library on a proper footing, mounted the new (Sheepshanks
Richard Sheepshanks
Richard Sheepshanks was an English astronomer.He graduated from Trinity College of Cambridge University in 1816...
) equatorial
Equatorial mount
An equatorial mount is a mount for instruments that follows the rotation of the sky by having one rotational axis parallel to the Earth's axis of rotation. This type of mount is used for astronomical telescopes and cameras...
and organised a new magnetic observatory. In 1847 an altazimuth was erected, designed by Airy to enable observations of the moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
to be made not only on the meridian
Meridian (astronomy)
This article is about the astronomical concept. For other uses of the word, see Meridian.In the sky, a meridian is an imaginary great circle on the celestial sphere. It passes through the north point on the horizon, through the celestial pole, up to the zenith, through the south point on the...
, but whenever it might be visible. In 1848 Airy invented the reflex zenith tube to replace the zenith sector previously employed. At the end of 1850 the great transit circle of 203 mm (8 inch) aperture and 3.5 m (11 ft 6 in) focal length
Focal length
The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus...
was erected, and is still the principal instrument of its class at the observatory. The mounting in 1859 of an equatorial of 330 mm (13 inch) aperture evoked the comment in his journal for that year, "There is not now a single person employed or instrument used in the observatory which was there in Mr Pond's time"; and the transformation was completed by the inauguration of spectroscopic work in 1868 and of the photographic registration of sunspots in 1873.
James Bradley
James Bradley FRS was an English astronomer and served as Astronomer Royal from 1742, succeeding Edmund Halley. He is best known for two fundamental discoveries in astronomy, the aberration of light , and the nutation of the Earth's axis...
, Nathaniel Bliss
Nathaniel Bliss
The Reverend Nathaniel Bliss was an English astronomer of the 18th century, serving as Britain's fourth Astronomer Royal between 1762 and 1764....
, Nevil Maskelyne
Nevil Maskelyne
The Reverend Dr Nevil Maskelyne FRS was the fifth English Astronomer Royal. He held the office from 1765 to 1811.-Biography:...
and John Pond, to defray the expense of which a large sum of money was allotted by the Treasury. As a result, no less than 8,000 lunar observations were rescued from oblivion, and were, in 1846, placed at the disposal of astronomers in such a form that they could be used directly for comparison with the theory and for the improvement of the tables of the moon's motion.
For this work Airy received in 1848 a testimonial from the Royal Astronomical Society
Royal Astronomical Society
The Royal Astronomical Society is a learned society that began as the Astronomical Society of London in 1820 to support astronomical research . It became the Royal Astronomical Society in 1831 on receiving its Royal Charter from William IV...
, and it at once led to the discovery by Peter Andreas Hansen
Peter Andreas Hansen
Peter Andreas Hansen was a Danish astronomer, was born at Tønder, Schleswig.-Biography:The son of a goldsmith, Hansen learned the trade of a watchmaker at Flensburg, and exercised it at Berlin and Tønder, 1818–1820...
of two new inequalities in the moon's motion. After completing these reductions, Airy made inquiries, before engaging in any theoretical investigation in connection with them, whether any other mathematician was pursuing the subject, and learning that Hansen had taken it in hand under the patronage of the king of Denmark, but that, owing to the death of the king and the consequent lack of funds, there was danger of his being compelled to abandon it, he applied to the admiralty on Hansen's behalf for the necessary sum. His request was immediately granted, and thus it came about that Hansen's famous Tables de la Lune were dedicated to La Haute Amirauté de sa Majesté la Reine de la Grande Bretagne et d'Irlande.
In 1851 Airy established a new Prime Meridian
Prime Meridian
The Prime Meridian is the meridian at which the longitude is defined to be 0°.The Prime Meridian and its opposite the 180th meridian , which the International Date Line generally follows, form a great circle that divides the Earth into the Eastern and Western Hemispheres.An international...
at Greenwich. This line, the fourth "Greenwich Meridian," became the definitive internationally recognised line in 1884.
Search for Neptune
In June 1846, Airy started corresponding with French astronomer Urbain Le Verrier over the latter's prediction that irregularities in the motion of UranusUranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...
were due to a so-far unobserved body. Aware that Cambridge Astronomer John Couch Adams
John Couch Adams
John Couch Adams was a British mathematician and astronomer. Adams was born in Laneast, near Launceston, Cornwall, and died in Cambridge. The Cornish name Couch is pronounced "cooch"....
had suggested that he had made similar predictions, on 9 July Airy entreated James Challis
James Challis
James Challis FRS was an English clergyman, physicist and astronomer. Plumian Professor and director of the Cambridge Observatory, he investigated a wide range of physical phenomena though made few lasting contributions outside astronomy...
to undertake a systematic search in the hope of securing the triumph of discovery for Britain. Ultimately, a rival search in Berlin by Johann Gottfried Galle
Johann Gottfried Galle
Johann Gottfried Galle was a German astronomer at the Berlin Observatory who, on 23 September 1846, with the assistance of student Heinrich Louis d'Arrest, was the first person to view the planet Neptune, and know what he was looking at...
, instigated by Le Verrier, won the race for priority. Though Airy was "abused most savagely both by English and French" for his failure to act on Adams's suggestions more promptly, there have also been claims that Adams's communications had been vague and dilatory and further that the search for a new planet was not the responsibility of the Astronomer Royal.
Mean density of the Earth
One of the most remarkable of Airy's researches was his determination of the mean density of the Earth. In 1826, the idea occurred to him of attacking this problem by means of pendulumPendulum
A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced from its resting equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position...
experiments at the top and bottom of a deep mine
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...
. His first attempt, made in the same year, at the Dolcoath mine
Dolcoath mine
Dolcoath mine was a copper and tin mine in Camborne, Cornwall, in the United Kingdom. Its name derives from the Cornish for 'Old Ground', and it was also affectionately known as The Queen of Cornish Mines. The site is north-west of Carn Brea. Dolcoath Road runs between the A3047 road and Chapel Hill...
in Cornwall, failed in consequence of an accident to one of the pendulum
Pendulum
A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced from its resting equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position...
s. A second attempt in 1828 was defeated by a flooding of the mine, and many years elapsed before another opportunity presented itself. The experiments eventually took place at the Harton pit near South Shields
South Shields
South Shields is a coastal town in Tyne and Wear, England, located at the mouth of the River Tyne to Tyne Dock, and about downstream from Newcastle upon Tyne...
in 1854. Their immediate result was to show that gravity at the bottom of the mine exceeded that at the top by 1/19286 of its amount, the depth being 383 m (1,256 ft) From this he was led to the final value of Earth's specific density of 6.566. This value, although considerably in excess of that previously found by different methods, was held by Airy, from the care and completeness with which the observations were carried out and discussed, to be "entitled to compete with the others on, at least, equal terms." (The currently accepted value for Earth's density is 5.5153 g/cm³.)
Ether drag test
By means of a water-filled telescopeTelescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...
, Airy in 1871 looked for a change in stellar aberration through the refracting water due to an ether drag
Aether drag hypothesis
In the 19th century, the theory of the luminiferous aether as the hypothetical medium for the propagation of light was widely discussed. An important part of this discussion was the question concerning the state of motion of Earth with respect to this medium. The aether drag hypothesis dealt with...
. Like in all other aether drift experiments, he obtained a negative result.
Lunar theory
In 1872 Airy conceived the idea of treating the lunar theory in a new way, and at the age of seventy-one he embarked on the prodigious toil which this scheme entailed. A general description of his method will be found in the Monthly Notices of the Royal Astronomical Society, vol. xxxiv, No. 3. It consisted essentially in the adoption of Charles-Eugène DelaunayCharles-Eugène Delaunay
Charles-Eugène Delaunay was a French astronomer and mathematician. His lunar motion studies were important in advancing both the theory of planetary motion and mathematics.-Life:...
's final numerical expressions for longitude
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....
, latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
, and parallax
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. The term is derived from the Greek παράλλαξις , meaning "alteration"...
, with a symbolic term attached to each number, the value of which was to be determined by substitution in the equations of motion.
In this mode of treating the question the order of the terms is numerical, and though the amount of labour is such as might well have deterred a younger man, yet the details were easy, and a great part of it might be entrusted to "a mere computer". (Note that at the time that this was written, the term "computer" referred to a human being who performed calculating work, either manually or with mechanical aids).
The work was published in 1886, when its author was eighty-five years of age. For some little time previously he had been harassed by a suspicion that certain errors had crept into the computations, and accordingly he addressed himself to the task of revision. But his powers were no longer what they had been, and he was never able to examine sufficiently into the matter. In 1890 he tells us how a grievous error had been committed in one of the first steps, and pathetically adds, "My spirit in the work was broken, and I have never heartily proceeded with it since."
Stress function method
In 1862, Airy presented a new technique to determine the strain
Strain (materials science)
In continuum mechanics, the infinitesimal strain theory, sometimes called small deformation theory, small displacement theory, or small displacement-gradient theory, deals with infinitesimal deformations of a continuum body...
and stress
Stress (physics)
In continuum mechanics, stress is a measure of the internal forces acting within a deformable body. Quantitatively, it is a measure of the average force per unit area of a surface within the body on which internal forces act. These internal forces are a reaction to external forces applied on the body...
field within a beam. This technique, sometimes called the Airy stress function method, can be used to find solutions to many two-dimensional problems in solid mechanics
Solid mechanics
Solid mechanics is the branch of mechanics, physics, and mathematics that concerns the behavior of solid matter under external actions . It is part of a broader study known as continuum mechanics. One of the most common practical applications of solid mechanics is the Euler-Bernoulli beam equation...
(see Wikiversity). For example, it was used by H. M. Westergaard to determine the stress and strain field around a crack tip and thereby this method contributed to the development of fracture mechanics
Fracture mechanics
Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in materials. It uses methods of analytical solid mechanics to calculate the driving force on a crack and those of experimental solid mechanics to characterize the material's resistance to fracture.In...
.
Tay Bridge Disaster
Thomas Bouch
Sir Thomas Bouch was a British railway engineer in Victorian Britain.He was born in Thursby, near Carlisle, Cumberland, England and lived in Edinburgh. He helped develop the caisson and the roll-on/roll-off train ferry. He worked initially for the North British Railway and helped design parts of...
for the North British Railway
North British Railway
The North British Railway was a Scottish railway company that was absorbed into the London and North Eastern Railway at the Grouping in 1923.-History:...
in the late 1870s. He thought that pressures no greater than about 10 pounds per square foot could be expected, a comment Bouch took to mean also applied to the first Tay railway bridge then being built. Much greater pressures however, can be expected in severe storms. Airy was called to give evidence before the Official Inquiry into the Tay Bridge disaster
Tay Bridge disaster
The Tay Bridge disaster occurred on 28 December 1879, when the first Tay Rail Bridge, which crossed the Firth of Tay between Dundee and Wormit in Scotland, collapsed during a violent storm while a train was passing over it. The bridge was designed by the noted railway engineer Sir Thomas Bouch,...
, and was criticised for his advice. However, little was known about the problems of wind resistance of large structures, and a Royal Commission on Wind Pressure was asked to conduct research into the problem.
Private life
Derbyshire
Derbyshire is a county in the East Midlands of England. A substantial portion of the Peak District National Park lies within Derbyshire. The northern part of Derbyshire overlaps with the Pennines, a famous chain of hills and mountains. The county contains within its boundary of approx...
. He later wrote, "Our eyes met ... and my fate was sealed ... I felt irresistibly that we must be united," and Airy proposed two days later. Richarda's father, the Revd Richard Smith, felt that Airy lacked the financial resources to marry his daughter. Only in 1830, with Airy established in his Cambridge position, was permission for the marriage granted.
The Airys had nine children, the eldest three dying in childhood. The eldest survivor, Wilfrid Airy, was the designer and engineer for "Colonel" George Tomline's Orwell Park observatory
Observatory
An observatory is a location used for observing terrestrial or celestial events. Astronomy, climatology/meteorology, geology, oceanography and volcanology are examples of disciplines for which observatories have been constructed...
. Wilfrid's daughter was the artist Anna Airy
Anna Airy
Anna Airy was an oil painter, pastel artist and etcher, working in Britain.She was born in Greenwich, London, daughter of engineer Wilfrid Airy and Anna née Listing, and granddaughter of Astronomer Royal George Biddell Airy....
.
Their eldest daughter, Hilda (1840–1916), married Edward Routh
Edward Routh
Edward John Routh FRS , was an English mathematician, noted as the outstanding coach of students preparing for the Mathematical Tripos examination of the University of Cambridge in its heyday in the middle of the nineteenth century...
in 1864.
Airy retired in 1881, living with his two married daughters at Croom's Hill near Greenwich. In 1891, he suffered a fall and an internal injury. He survived the consequential surgery only a few days. His wealth at death was £27,713. Airy and his wife and three pre-deceased children are buried at St. Mary's Church in Playford, Suffolk
Playford, Suffolk
Playford is a small village in Suffolk, England, on the outskirts of Ipswich. It has about 220 residents in 90 households. The River Fynn runs through the village, and many footpaths from Playford lead into the Fynn Valley. Villages nearby include Rushmere, Little Bealings, Great Bealings, Culpho...
. A cottage owned by Airy still stands, adjacent to the church and now in private hands.
Legacy and honours
- He was elected president of the Royal Astronomical SocietyRoyal Astronomical SocietyThe Royal Astronomical Society is a learned society that began as the Astronomical Society of London in 1820 to support astronomical research . It became the Royal Astronomical Society in 1831 on receiving its Royal Charter from William IV...
four times. - Foreign Honorary Member of the American Academy of Arts and SciencesAmerican Academy of Arts and SciencesThe American Academy of Arts and Sciences is an independent policy research center that conducts multidisciplinary studies of complex and emerging problems. The Academy’s elected members are leaders in the academic disciplines, the arts, business, and public affairs.James Bowdoin, John Adams, and...
(1832) - The Martian crater Airy is named for him. Within that crater lies another smaller crater called Airy-0Airy-0Airy-0 is a crater on Mars whose location defines the position of the prime meridian of that planet. It is about across and lies within the larger crater Airy in the region Sinus Meridiani....
whose location defines the prime meridianPrime MeridianThe Prime Meridian is the meridian at which the longitude is defined to be 0°.The Prime Meridian and its opposite the 180th meridian , which the International Date Line generally follows, form a great circle that divides the Earth into the Eastern and Western Hemispheres.An international...
of that planet, as does the location of Airy's 1850 telescope for Earth. - winner of the Lalande PrizeLalande PrizeThe Lalande Prize was an award for scientific advances in astronomy, given from 1802 through 1970 by the French Academy of Sciences.The prize was named for, and endowed by, astronomer Jérôme Lalande in 1801...
for astronomy from the French Academy of SciencesFrench Academy of SciencesThe French Academy of Sciences is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research...
, 1834 - There is also a lunar crater AiryAiry (lunar crater)Airy is a lunar impact crater located in the southern highlands. It is named in honour of British astronomer George Biddell Airy. It forms the southern-most member of a chain of craters consisting of Vogel, Argelander, and Airy. A little further to the south lies Donati. Airy has a worn, and...
named in his honour. - Airy wave theoryAiry wave theoryIn fluid dynamics, Airy wave theory gives a linearised description of the propagation of gravity waves on the surface of a homogeneous fluid layer. The theory assumes that the fluid layer has a uniform mean depth, and that the fluid flow is inviscid, incompressible and irrotational...
is the linear theory for the propagation of gravity wavesOcean surface waveIn fluid dynamics, wind waves or, more precisely, wind-generated waves are surface waves that occur on the free surface of oceans, seas, lakes, rivers, and canals or even on small puddles and ponds. They usually result from the wind blowing over a vast enough stretch of fluid surface. Waves in the...
on the surface of a fluidFluidIn physics, a fluid is a substance that continually deforms under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
.
External links
- Awarding of RAS gold medal, 1833: MNRAS 2 (1833) 159
- Awarding of RAS gold medal, 1846: MNRAS 7 (1846) 64
- Mathematical Tracts on the Lunar and Planetary Theories 4th edition (London, McMillan, 1858)
- Full texts of some of the papers by Airy are available at Gallica: bibliothèque numérique de la Bibliothèque nationale de France
Obituaries
- E. J. R.Edward RouthEdward John Routh FRS , was an English mathematician, noted as the outstanding coach of students preparing for the Mathematical Tripos examination of the University of Cambridge in its heyday in the middle of the nineteenth century...
, Proceedings of the Royal Society, 51 (1892), i–xii - The TimesThe TimesThe Times is a British daily national newspaper, first published in London in 1785 under the title The Daily Universal Register . The Times and its sister paper The Sunday Times are published by Times Newspapers Limited, a subsidiary since 1981 of News International...
, 5 January 1892 - East Anglian Daily Times, 11 January 1892
- Suffolk Chronicle, 9 January 1892
- Daily Times, 5 January 1892
- Proceedings of the Institution of Civil Engineers, 108 (1891–2), 391–394
- Astronomical Journal 11 (1892) 96
- Astronomische Nachrichten 129 (1892) 33/34
- The Observatory 15 (1892) 73