John Henry Poynting

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John Poynting
John Henry Poynting
Born(1852-09-09)9 September 1852
Monton, Lancashire, England
Died30 March 1914(1914-03-30) (aged 61)
Birmingham, England
NationalityEnglish
Alma mater
Known forPoynting vector
Poynting effect
Poynting's theorem
Poynting–Robertson effect
Awards
Scientific career
FieldsPhysicist
InstitutionsMason Science College, University of Birmingham
Academic advisorsJames Clerk Maxwell
Notable studentsFrancis William Aston; Alfred J. Lotka
Signature
Mason Science College (demolished in 1964)

John Henry Poynting FRS[1] (9 September 1852 – 30 March 1914[2][3]) was an English physicist. He was the first professor of physics at Mason Science College from 1880 to 1900, and then the successor institution, the University of Birmingham until his death.[4]

Early life and education[edit]

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, where he his father served as minister 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, where his physics teachers included Osborne Reynolds and Balfour Stewart. From 1872 to 1876 he was a student at the University of Cambridge, where he attained high honours in mathematics after taking grinds with Edward Routh.

Career[edit]

In the late 1870s, he worked in the Cavendish Laboratory at Cambridge under James Clerk Maxwell.[5] In 1880, he became the first professor of physics at the University of Birmingham. He was the developer and eponym of the Poynting vector, which describes the direction and magnitude of electromagnetic energy flow and is used in the Poynting theorem, a statement about energy conservation for electric and magnetic fields. This work was first published in 1884. He performed a measurement of Newton's gravitational constant 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:[6] this was later named the Poynting–Robertson effect.

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 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.[7] Poynting wrote most of it.[8]

He was awarded an honorary MSc in Pure Science in 1901 by Birmingham University.[9]

Poynting lived at 11 St Augustine's Road, Edgbaston with his family and servants for some years. He previously lived at 66 Beaufort Road, Edgbaston (demolished) and died of a diabetic coma[citation needed], 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.[10]

Legacy[edit]

Alfred J. Lotka 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 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.[11]

University of Birmingham – Poynting Physics Building – blue plaque
Blue plaque to Poynting erected in Salford by the Institute of Physics

Craters on Mars and the Moon are named in his honour, as is the main physics building at the University of Birmingham and the departmental society there, the Poynting Physical Society. He is credited with coining the expression "greenhouse effect" in 1909 to explain how infrared-absorbing trace gasses such as carbon dioxide in the atmosphere increases the surface temperature of Earth and Mars.[12]

Works by J. H. Poynting[edit]

Electricity and magnetism, 1914

References[edit]

  1. ^ "Poynting, John Henry (PNTN872JH)". A Cambridge Alumni Database. University of Cambridge.
  2. ^ GRO Register of Births: DEC 1852 8c 391 BARTON – John Henry Poynting, mmn = unknown
  3. ^ GRO Register of Deaths: MAR 1914 6d 128 KING'S N. – John Henry Poynting, aged 61
  4. ^ "History of the School of Physics and Astronomy".
  5. ^ "Poynting, John Henry (PNTN872JH)". A Cambridge Alumni Database. University of Cambridge.
  6. ^ Benest, Daniel; Froeschlé, Claude (1992). Interrelations Between Physics and Dynamics for Minor Bodies in the Solar System. Atlantica Séguier Frontières. p. 437. ISBN 2-86332112-9. Extract of page 437
  7. ^ For a lengthy though incomplete listing of the editions of Poynting and Thomson's Text-book of Physics see Worldcat.org.
  8. ^ Reported in the biography of JJ Thomson by Davis & Falconer, previewable at Google Book Search Preview.
  9. ^ "University campus Blue Plaque Trail". Birmingham University. Archived from the original on 6 October 2014. Retrieved 12 November 2014.
  10. ^ "Poynting, John Henry". Who's Who. 1914. p. 1647.
  11. ^ "Poynting Physical Society".
  12. ^ Poynting, J.H. (1907). "LXXIV. On Prof. Lowell's method for evaluating the surface-temperatures of the planets; with an attempt to represent the effect of day and night on the temperature of the earth". The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science. 14 (84): 749–760. doi:10.1080/14786440709463737.
  13. ^ Preston, Erasmus D. (1895). "Review of The Mean Density of the Earth by J. H. Poynting". Physical Review. II. American Physical Society: 76–80.
  14. ^ "Review of A Text-Book of Physics: Sound by J. H. Poynting and J. J. Thomson". Westminster Review. 151: 463–464. April 1899.
  15. ^ "Review of Properties of Matter by J. H. Poynting and J. J. Thomson". The Athenaeum (3939): 534. 25 April 1903.
  16. ^ "Review of The Earth: its Shape, Size, Weight, and Spin by J. H. Poynting". The Geological Magazine. New Series. X: 318. 1913.

External links[edit]

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