John Henry Poynting FRS (9 September 185230 March 1914) was an English

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate caus ...

. He was the first professor of physics at Mason Science College from 1880 to 1900, and then the successor institution, the

University of Birmingham , mottoeng = Through efforts to heights , established = 1825 – Birmingham School of Medicine and Surgery1836 – Birmingham Royal School of Medicine and Surgery1843 – Queen's College1875 – Mason Science College1898 – Mason Univers ...

until his death.

Biography

Poynting was the youngest son of Thomas Elford Poynting, a Unitarian minister. He was born at the parsonage of the Monton Unitarian Chapel in Eccles, Lancashire (his father serving as minister there from 1846 to 1878.) In his boyhood he was educated at the nearby school operated by his father. From 1867 to 1872 he attended Owens College, now the

University of Manchester , mottoeng = Knowledge, Wisdom, Humanity , established = 2004 – University of Manchester Predecessor institutions: 1956 – UMIST (as university college; university 1994) 1904 – Victoria University of Manchester 1880 – Victoria Univer ...

, where his physics teachers included Osborne Reynolds and Balfour Stewart. From 1872 to 1876 he was a student at

Cambridge University , mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Schola ...

, where he attained high honours in mathematics after taking grinds with Edward Routh. In the late 1870s he worked in the

Cavendish Laboratory The Cavendish Laboratory is the Department of Physics at the University of Cambridge, and is part of the School of Physical Sciences. The laboratory was opened in 1874 on the New Museums Site as a laboratory for experimental physics and is named ...

at Cambridge under

James Clerk Maxwell James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish mathematician and scientist responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism and ligh ...

. In 1880, he became the first professor of physics at the

. He was the developer and

eponym An eponym is a person, a place, or a thing after whom or which someone or something is, or is believed to be, named. The adjectives which are derived from the word eponym include ''eponymous'' and ''eponymic''. Usage of the word The term ''epon ...

of the

Poynting vector In physics, the Poynting vector (or Umov–Poynting vector) represents the directional energy flux (the energy transfer per unit area per unit time) or '' power flow'' of an electromagnetic field. The SI unit of the Poynting vector is the watt ...

, which describes the direction and magnitude of electromagnetic energy flow and is used in the

Poynting theorem In electrodynamics, Poynting's theorem is a statement of conservation of energy for electromagnetic fields developed by British physicist John Henry Poynting. It states that in a given volume, the stored energy changes at a rate given by the work ...

, a statement about energy conservation for electric and

magnetic Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particle ...

fields. This work was first published in 1884. He performed a measurement of Newton's

gravitational constant The gravitational constant (also known as the universal gravitational constant, the Newtonian constant of gravitation, or the Cavendish gravitational constant), denoted by the capital letter , is an empirical physical constant involved in ...

by innovative means during 1893. In 1903 he was the first to realise that the Sun's radiation can draw in small particles towards it: this was later named the

Poynting–Robertson effect The Poynting–Robertson effect, also known as Poynting–Robertson drag, named after John Henry Poynting and Howard P. Robertson, is a process by which solar radiation causes a dust grain orbiting a star to lose angular momentum relative to its o ...

. He discovered the torsion-extension coupling in finite strain elasticity. This is now known as the (positive) Poynting effect in torsion. Poynting and the Nobel prizewinner

J. J. Thomson Sir Joseph John Thomson (18 December 1856 – 30 August 1940) was a British physicist and Nobel Laureate in Physics, credited with the discovery of the electron, the first subatomic particle to be discovered. In 1897, Thomson showed that c ...

co-authored a multi-volume undergraduate physics textbook, which was in print for about 50 years and was in widespread use during the first third of the 20th century. Poynting wrote most of it. He was awarded an

honorary An honorary position is one given as an honor, with no duties attached, and without payment. Other uses include: * Honorary Academy Award, by the Academy of Motion Picture Arts and Sciences, United States * Honorary Aryan, a status in Nazi Germany ...

MSc in Pure Science in 1901 by Birmingham University. Poynting lived at 11 St Augustine's Road,

Edgbaston Edgbaston () is an affluent suburban area of central Birmingham, England, historically in Warwickshire, and curved around the southwest of the city centre. In the 19th century, the area was under the control of the Gough-Calthorpe family an ...

with his family and servants for some years. He previously lived at 66 Beaufort Road,

(demolished) and died of a diabetic coma, aged 61, at 10 Ampton Road, Edgbaston in 1914. In 1880 he married Maria Adney Cropper. He was survived by his widow, a son, and two daughters.

Legacy

Alfred J. Lotka Alfred James Lotka (March 2, 1880 – December 5, 1949) was a US mathematician, physical chemist, and statistician, famous for his work in population dynamics and energetics. An American biophysicist, Lotka is best known for his propos ...

was among Poynting's most famous students, being inspired by Poynting to apply the ideas of physical chemistry to biology. Lotka dedicated his classic book on mathematical population biology to Poynting. Poynting predicted the `Poynting-Robertson effect', whereby a particle of dust orbiting a star experiences a drag force which makes it spiral slowly into the star.

Howard P. Robertson Howard Percy "Bob" Robertson (January 27, 1903 – August 26, 1961) was an American mathematician and physicist known for contributions related to physical cosmology and the uncertainty principle. He was Professor of Mathematical Physics at the C ...

later restated the prediction using General Relativity. Poynting also founded and is the namesake of the popular student society at the University of Birmingham, 'The Poynting Physical Society' or PPS. University of Birmingham - Poynting Physics Building - Poynting 02

University of Birmingham - Poynting Physics Building - Poynting 02

Unitarian Church, Monton, Blue plaque - geograph

Crater Crater may refer to: Landforms *Impact crater, a depression caused by two celestial bodies impacting each other, such as a meteorite hitting a planet *Explosion crater, a hole formed in the ground produced by an explosion near or below the surfac ...

s on

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

and the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

are named in his honour, as is the main Physics building at the

and the departmental society there, the Poynting Physical Society. He is credited with coining the expression "

greenhouse effect The greenhouse effect is a process that occurs when energy from a planet's host star goes through the planet's atmosphere and heats the planet's surface, but greenhouse gases in the atmosphere prevent some of the heat from returning directly ...

" in 1909 to explain how infrared-absorbing trace gasses such as carbon dioxide in the atmosphere increases the surface temperature of Earth and Mars.

Works by J. H. Poynting

* 1884 ''A Comparison of the Fluctuations in the Price of Wheat and in the Cotton and Silk Imports into Great Britain'', ''Journal of the Royal Statistical Society''; 47, 1884, pp. 34–64 * 189
''The Mean Density of the Earth''
London, C. Griffin * 1899 (with J. J. Thomson) ''A Text-Book of Physics: volume I: Sound'' London, C. Griffin
2nd edition, 1900
* 1902 (with J. J. Thomson
''A Text-Book of Physics: volume II: Properties of Matter''
London, C. Griffin * 1904 (with J. J. Thomson
''A Text-Book of Physics: volume III: Heat''
London, C. Griffin * 191
''The earth; its shape, size, weight and spin''
Cambridge University Press * 1914 (with J. J. Thomson
''A Text-Book of Physics: volume IV: Electricity and Magnetism. Pts. I and II: Static electricity and magnetism''
London, C. Griffin * 192
''Collected Scientific Papers''
Cambridge University Press

References

External links

* * * {{DEFAULTSORT:Poynting, John Henry 1852 births 1914 deaths English physicists Academics of the University of Birmingham Royal Medal winners Fellows of the Royal Society Presidents of the Physical Society