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.Poynting was the youngest son of Thomas Elford Poynting, a Unitarian minister. In his boyhood he was educated at a 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.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.