James Challis
Encyclopedia
James Challis FRS was an English
clergy
man, 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
. He is best remembered for his missed opportunity to discover the planet
Neptune
in 1846.
where his father, John Challis, was a stonemason. After attending various local schools, he graduated
from Trinity College, Cambridge
in 1825 as Senior Wrangler and first Smith's prize
man. He was elected a fellow of Trinity in 1826 and was ordained
in 1830. He held the benefice
of Papworth Everard
, Cambridgeshire
from the college until 1852. In 1831 Challis married Sarah Copsey, née Chandler, a widow, and consequently resigned his Trinity fellowship. The couple had a son and a daughter.
and Plumian Professor of Astronomy and Experimental Philosophy
, holding the latter post until his death. He lectured in all areas of physics
. As examiner for the Smith's prize, he appraised the early work of G. G. Stokes, Arthur Cayley
, John Couch Adams
, William Thomson
(later Lord Kelvin), Peter Guthrie Tait
and James Clerk Maxwell
. He was referee for Thomson and for Stokes in their respective applications for chairs at the University of Glasgow
, and for Maxwell at Aberdeen
. He and Thomson together set and examined the Adams prize
topic on Saturn's rings, won by Maxwell in 1857.
at the observatory and gradually improved the instrumentation and accuracy
of observations. He made some early observations of the fracture of comet
3D/Biela
into two pieces on 15 January 1846 and reobserved both fragments in 1852. He published over 60 scientific papers recording other observations of comets and asteroid
s. He invented the meteoroscope (1848) and the transit-reducer (1849). Challis published twelve volumes of Astronomical Observations Made at the Observatory of Cambridge.
He and his wife lived at the observatory as genial hosts for 25 years, though Challis once left his wife to guard an intruder while he summoned assistance. Challis eventually resigned the observatory post because of chronic stress
in his inability to keep up with processing new astronomical observations. His predecessor Airy had taken a more relaxed attitude. He was succeeded by Adams though he maintained his professorship until his death.
in the solar system
. Adams had predicted the location of such a planet
as early as 1844, based on irregularities in the orbit of Uranus
. Adams failed to promote his prediction successfully and there was little enthusiasm for a systematic search of the heavens until Airy's intervention. Challis finally began his, somewhat reluctant, search in July 1846, unaware that Frenchman Urbain Le Verrier had independently made an identical prediction. German astronomer
Johann Gottfried Galle
, assisted by Heinrich Louis d'Arrest
, finally confirmed Le Verrier's prediction on 23 September. The planet
was named "Neptune". It soon became apparent from Challis's notebooks that he had observed Neptune twice, a month earlier, failing to make the identification through lack of diligence.
Challis was full of remorse but blamed his neglect on the pressing business of catching up on the backlog of astronomical observations from the observatory. As he reflected in a letter to Airy of 12 October 1846:
. Challis supported the wave theory of light and advanced the theory of a luminiferous ether as a medium for its propagation. However, he rejected the idea that the ether was an elastic solid
, insisting that it was a fluid
, bringing him into conflict with Airy and Stokes. Driven by Sir Isaac Newton
's somewhat obscure assertion of "a certain most subtle spirit which pervades and lies hid in all gross bodies", Challis was driven to attempt to derive all physical phenomena from a model of intert spherical
atom
s embedded in an elastic
fluid ether, an enterprise described as an attempt at a "Victorian
unified field theory
". His work included a mechanical explanation of gravitation
. His ideas won few supporters.
's views on Genesis expressed in Essays and Reviews
(1860). Challis saw Genesis as an "antecedent plan" for creation, rather than a literal chronology, and argued that the biblical
account could be reconciled with the geological record
. He went on to interpret the word "law", as used in a spiritual
sense by Saint Paul, in the sense of scientific law
.
and was buried beside his wife in Mill Road cemetery
. His wealth at death was £781.
Despite the embarrassment over Neptune, Challis did make genuine contributions to astronomy. His blend of theology and science was in the spirit of Stokes, and his search for a unified theory akin to the endeavours of Thomson and Maxwell. However, despite his tenacity in advocating his physical and theological theories, they had little impact. Olin J. Eggen
claimed that "At a later time, or under less amiable circumstances, he would have been branded a charlatan. He would now be as forgotten as his peculiar ideas had not the events surrounding the discovery of Neptune in 1845 given him a genuine opportunity for scientific immortality. But he fumbled it."
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
clergy
Clergy
Clergy is the generic term used to describe the formal religious leadership within a given religion. A clergyman, churchman or cleric is a member of the clergy, especially one who is a priest, preacher, pastor, or other religious professional....
man, physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
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...
. 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...
and director of the 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...
, he investigated a wide range of physical phenomena though made few lasting contributions outside astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
. He is best remembered for his missed opportunity to discover the 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,...
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...
in 1846.
Early life
Challis was born in Braintree, EssexBraintree, Essex
Braintree is a town of about 42,000 people and the principal settlement of the Braintree district of Essex in the East of England. It is northeast of Chelmsford and west of Colchester on the River Blackwater, A120 road and a branch of the Great Eastern Main Line.Braintree has grown contiguous...
where his father, John Challis, was a stonemason. After attending various local schools, he graduated
Graduation
Graduation is the action of receiving or conferring an academic degree or the ceremony that is sometimes associated, where students become Graduates. Before the graduation, candidates are referred to as Graduands. The date of graduation is often called degree day. The graduation itself is also...
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...
in 1825 as Senior Wrangler and 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 :...
man. He was elected a fellow of Trinity in 1826 and was ordained
Ordination
In general religious use, ordination is the process by which individuals are consecrated, that is, set apart as clergy to perform various religious rites and ceremonies. The process and ceremonies of ordination itself varies by religion and denomination. One who is in preparation for, or who is...
in 1830. He held the benefice
Benefice
A benefice is a reward received in exchange for services rendered and as a retainer for future services. The term is now almost obsolete.-Church of England:...
of Papworth Everard
Papworth Everard
Papworth Everard is a village in Cambridgeshire, England. It lies ten miles west of Cambridge and six miles south of Huntingdon, having along its centre Ermine Street, the old North Road, the Roman highway that for centuries served as a major artery from London to York, which is now the A1198...
, Cambridgeshire
Cambridgeshire
Cambridgeshire is a county in England, bordering Lincolnshire to the north, Norfolk to the northeast, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and Northamptonshire to the west...
from the college until 1852. In 1831 Challis married Sarah Copsey, née Chandler, a widow, and consequently resigned his Trinity fellowship. The couple had a son and a daughter.
Plumian professor
In 1836, he became director of the Cambridge ObservatoryCambridge 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...
and Plumian Professor of Astronomy and Experimental Philosophy
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...
, holding the latter post until his death. He lectured in all areas of physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
. As examiner for the Smith's prize, he appraised the early work of G. G. Stokes, Arthur Cayley
Arthur Cayley
Arthur Cayley F.R.S. was a British mathematician. He helped found the modern British school of pure mathematics....
, 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"....
, William Thomson
William Thomson, 1st Baron Kelvin
William Thomson, 1st Baron Kelvin OM, GCVO, PC, PRS, PRSE, was a mathematical physicist and engineer. At the University of Glasgow he did important work in the mathematical analysis of electricity and formulation of the first and second laws of thermodynamics, and did much to unify the emerging...
(later Lord Kelvin), Peter Guthrie Tait
Peter Guthrie Tait
Peter Guthrie Tait FRSE was a Scottish mathematical physicist, best known for the seminal energy physics textbook Treatise on Natural Philosophy, which he co-wrote with Kelvin, and his early investigations into knot theory, which contributed to the eventual formation of topology as a mathematical...
and James Clerk Maxwell
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...
. He was referee for Thomson and for Stokes in their respective applications for chairs at the University of Glasgow
University of Glasgow
The University of Glasgow is the fourth-oldest university in the English-speaking world and one of Scotland's four ancient universities. Located in Glasgow, the university was founded in 1451 and is presently one of seventeen British higher education institutions ranked amongst the top 100 of the...
, and for Maxwell at Aberdeen
University of Aberdeen
The University of Aberdeen, an ancient university founded in 1495, in Aberdeen, Scotland, is a British university. It is the third oldest university in Scotland, and the fifth oldest in the United Kingdom and wider English-speaking world...
. He and Thomson together set and examined the Adams prize
Adams Prize
The Adams Prize is awarded each year by the Faculty of Mathematics at the University of Cambridge and St John's College to a young, UK based mathematician for first-class international research in the Mathematical Sciences....
topic on Saturn's rings, won by Maxwell in 1857.
Cambridge Observatory
Challis succeeded George Biddell AiryGeorge Biddell Airy
Sir George Biddell Airy PRS KCB was an English mathematician and astronomer, Astronomer Royal from 1835 to 1881...
at the observatory and gradually improved the instrumentation and accuracy
Accuracy and precision
In the fields of science, engineering, industry and statistics, the accuracy of a measurement system is the degree of closeness of measurements of a quantity to that quantity's actual value. The precision of a measurement system, also called reproducibility or repeatability, is the degree to which...
of observations. He made some early observations of the fracture of comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
3D/Biela
3D/Biela
Biela's Comet or Comet Biela was a periodic comet first recorded in 1772 by Montaigne and Messier and finally identified as periodic in 1826 by Wilhelm von Biela. It was subsequently observed to split in two and has not been seen since 1852...
into two pieces on 15 January 1846 and reobserved both fragments in 1852. He published over 60 scientific papers recording other observations of comets and asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
s. He invented the meteoroscope (1848) and the transit-reducer (1849). Challis published twelve volumes of Astronomical Observations Made at the Observatory of Cambridge.
He and his wife lived at the observatory as genial hosts for 25 years, though Challis once left his wife to guard an intruder while he summoned assistance. Challis eventually resigned the observatory post because of chronic stress
Chronic stress
Chronic stress is the response to emotional pressure suffered for a prolonged period over which an individual perceives he or she has no control. It involves an endocrine system response in which occurs a release of corticosteroids...
in his inability to keep up with processing new astronomical observations. His predecessor Airy had taken a more relaxed attitude. He was succeeded by Adams though he maintained his professorship until his death.
The search for the eighth planet
In 1846, Airy finally persuaded a reluctant Challis to join in the search for an eighth planetPlanet
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,...
in the solar system
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
. Adams had predicted the location of such a 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,...
as early as 1844, based on irregularities in the orbit of Uranus
Uranus
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...
. Adams failed to promote his prediction successfully and there was little enthusiasm for a systematic search of the heavens until Airy's intervention. Challis finally began his, somewhat reluctant, search in July 1846, unaware that Frenchman Urbain Le Verrier had independently made an identical prediction. German 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...
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...
, assisted by Heinrich Louis d'Arrest
Heinrich Louis d'Arrest
Heinrich Louis d'Arrest was a German astronomer, born in Berlin. His name is sometimes given as Heinrich Ludwig d'Arrest....
, finally confirmed Le Verrier's prediction on 23 September. The 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,...
was named "Neptune". It soon became apparent from Challis's notebooks that he had observed Neptune twice, a month earlier, failing to make the identification through lack of diligence.
Challis was full of remorse but blamed his neglect on the pressing business of catching up on the backlog of astronomical observations from the observatory. As he reflected in a letter to Airy of 12 October 1846:
Physicist
Challis worked in hydrodynamics and opticsOptics
Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behavior of visible, ultraviolet, and infrared light...
. Challis supported the wave theory of light and advanced the theory of a luminiferous ether as a medium for its propagation. However, he rejected the idea that the ether was an elastic solid
Elasticity (physics)
In physics, elasticity is the physical property of a material that returns to its original shape after the stress that made it deform or distort is removed. The relative amount of deformation is called the strain....
, insisting that it was a fluid
Fluid
In 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....
, bringing him into conflict with Airy and Stokes. Driven by Sir Isaac Newton
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
's somewhat obscure assertion of "a certain most subtle spirit which pervades and lies hid in all gross bodies", Challis was driven to attempt to derive all physical phenomena from a model of intert spherical
Sphere
A sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle in two dimensions, a perfect sphere is completely symmetrical around its center, with all points on the surface lying the same distance r from the center point...
atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
s embedded in an elastic
Elasticity (physics)
In physics, elasticity is the physical property of a material that returns to its original shape after the stress that made it deform or distort is removed. The relative amount of deformation is called the strain....
fluid ether, an enterprise described as an attempt at a "Victorian
Victorian era
The Victorian era of British history was the period of Queen Victoria's reign from 20 June 1837 until her death on 22 January 1901. It was a long period of peace, prosperity, refined sensibilities and national self-confidence...
unified field theory
Unified field theory
In physics, a unified field theory, occasionally referred to as a uniform field theory, is a type of field theory that allows all that is usually thought of as fundamental forces and elementary particles to be written in terms of a single field. There is no accepted unified field theory, and thus...
". His work included a mechanical explanation of gravitation
Mechanical explanations of gravitation
Mechanical explanations of gravitation are attempts to explain the action of gravity by aid of basic mechanical processes, such as pressure forces caused by pushes, and without the use of any action at a distance. These theories were developed from the 16th until the 19th century in connection...
. His ideas won few supporters.
Theological views
Challis took issue with Charles Wycliffe GoodwinCharles Wycliffe Goodwin
Charles Wycliffe Goodwin was a British Egyptologist, lawyer and judge.Goodwin was born in 1817. He studied at St Catherine's and graduated, in 1838, 6th Classic and senior optime in Mathematics. He was called to the bar at Lincoln's Inn in 1843 and in 1865 became assistant judge of the British...
's views on Genesis expressed in Essays and Reviews
Essays and Reviews
Essays and Reviews, published in March 1860, is a broad-church volume of seven essays on Christianity. The topics covered the biblical research of the German critics, the evidence for Christianity, religious thought in England, and the cosmology of Genesis....
(1860). Challis saw Genesis as an "antecedent plan" for creation, rather than a literal chronology, and argued that the biblical
Bible
The Bible refers to any one of the collections of the primary religious texts of Judaism and Christianity. There is no common version of the Bible, as the individual books , their contents and their order vary among denominations...
account could be reconciled with the geological record
Geologic time scale
The geologic time scale provides a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth...
. He went on to interpret the word "law", as used in a spiritual
Spirituality
Spirituality can refer to an ultimate or an alleged immaterial reality; an inner path enabling a person to discover the essence of his/her being; or the “deepest values and meanings by which people live.” Spiritual practices, including meditation, prayer and contemplation, are intended to develop...
sense by Saint Paul, in the sense of scientific law
Scientific law
A scientific law is a statement that explains what something does in science just like Newton's law of universal gravitation. A scientific law must always apply under the same conditions, and implies a causal relationship between its elements. The law must be confirmed and broadly agreed upon...
.
Assessment
Challis published 225 papers in mathematics, physics and astronomy. He was re-elected fellow of Trinity in 1870. He died in CambridgeCambridge
The city of Cambridge is a university town and the administrative centre of the county of Cambridgeshire, England. It lies in East Anglia about north of London. Cambridge is at the heart of the high-technology centre known as Silicon Fen – a play on Silicon Valley and the fens surrounding the...
and was buried beside his wife in Mill Road cemetery
Mill Road Cemetery, Cambridge
Mill Road Cemetery is a cemetery off Mill Road in the Petersfield area of Cambridge, England. The cemetery is listed by English Heritage as a Grade II site, and several of the tombs are also listed as of special architectural and historical interest....
. His wealth at death was £781.
Despite the embarrassment over Neptune, Challis did make genuine contributions to astronomy. His blend of theology and science was in the spirit of Stokes, and his search for a unified theory akin to the endeavours of Thomson and Maxwell. However, despite his tenacity in advocating his physical and theological theories, they had little impact. Olin J. Eggen
Olin J. Eggen
Olin Jeuck Eggen was an American astronomer. Some sources incorrectly give his name as Olin Jenck Eggen.-Biography:...
claimed that "At a later time, or under less amiable circumstances, he would have been branded a charlatan. He would now be as forgotten as his peculiar ideas had not the events surrounding the discovery of Neptune in 1845 given him a genuine opportunity for scientific immortality. But he fumbled it."
Honours and memorials
- Fellow 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...
, (1836); - Fellow of the Royal Society, (1848);
- Bronze medal at the The Great ExhibitionThe Great ExhibitionThe Great Exhibition of the Works of Industry of all Nations or The Great Exhibition, sometimes referred to as the Crystal Palace Exhibition in reference to the temporary structure in which it was held, was an international exhibition that took place in Hyde Park, London, from 1 May to 15 October...
for his transit-reducer, (1851). - The distributed.netDistributed.netdistributed.net is a worldwide distributed computing effort that is attempting to solve large scale problems using otherwise idle CPU or GPU time. It is officially recognized as a non-profit organization under U.S...
UK team, originally Cambridge UniversityUniversity of CambridgeThe University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...
and CIXCIXCIX was one of the earliest British Internet service providers. Founded in 1983 by Frank and Sylvia Thornley, it began as a FidoNet bulletin board system, but in 1987 was relaunched commercially as CIX...
based, is named "Prof. James Challis' Most Excellent UK Team" in his honour http://www.winwaed.com/comp/challis/climateprediction.shtml. - Lunar crater ChallisChallis (crater)Challis is a lunar crater that is located in the northern regions of the Moon's near side, close enough to the limb to appear significantly foreshortened when viewed from the Earth...
is named after him.
By Challis
- Challis, J. (1861) Creation in Plan and Progress
- — (1871) A Translation of the Epistle of the Apostle Paul to the Romans
- — (1873) An Essay on the Mathematical Principles of Physics
- — (1875) Remarks on the Cambridge Mathematical Studies
- — (1880) Essay on the Scriptural Doctrine of Immortality
Obituary
- J. W. L. G.James Whitbread Lee GlaisherJames Whitbread Lee Glaisher son of James Glaisher, the meteorologist, was a prolific English mathematician.He was educated at St Paul's School and Trinity College, Cambridge, where he was second wrangler in 1871...
(1882-3) "James Challis" Monthly Notices of the Royal Astronomical Society, 43: 160–79
About Challis
- [Anon.] (2001) "Challis, James", Encyclopaedia Britannica, CDROM Deluxe edition
- Clerke, A. M. (2006) "Challis, James (1803–1882)", rev. David B. Wilson, Oxford Dictionary of National Biography, Oxford University Press, online edn, Oct 2006, accessed 17 September 2007
- Eggen, O. J.Olin J. EggenOlin Jeuck Eggen was an American astronomer. Some sources incorrectly give his name as Olin Jenck Eggen.-Biography:...
(1970–1981) "Challis, James" in