John Henry Poynting

"Poynting" redirects here. For the vector, see Poynting vector. For the theorem, see Poynting Theorem.

John Poynting
John Henry Poynting (1852-1914)
Born	(1852-09-09)9 September 1852 Monton, Lancashire, England
Died	Birmingham, England
Residence	England
Nationality	English
Fields	Physicist
Institutions	Mason Science College, University of Birmingham
Alma mater	University of Cambridge University of Manchester
Academic advisors	James Clerk Maxwell
Notable students	Francis William Aston
Known for	Poynting vector Poynting effect Poynting's theorem Poynting–Robertson effect
Influences	Edward Routh
Notable awards	Adams Prize (1893) Hopkins Prize (1893) Royal Medal (1905)
Signature John Poynting's signature

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

Mason Science College, now the University of Birmingham

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 Owen's 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 Cambridge University, where he attained high honours in mathematics after taking grinds with Edward Routh. In the late 1870s he worked in the Cavendish Laboratory at Cambridge under James Clerk Maxwell.

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: 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. Poynting wrote most of it.

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

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, aged 61, at 10 Ampton Road, Edgbaston in 1914.

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
• 1911 A Text-book of Physics: volume III: Heat London, C. Griffin
• 1913 The earth; its shape, size, weight and spin Cambridge University Press
• 1914 A Text-book of Physics: Electricity and Magnetism. Pts. I and II: Static electricity and magnetism London, C. Griffin
• 1920 Collected Scientific Papers Cambridge University Press

Legacy

File:Unitarian Church, Monton, Blue plaque - geograph.org.uk - 681166.jpg

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.

External links

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