Background
John Henry Poynting was born on September 9, 1852, in Monton, near Manchester, England. He was the youngest son of the Reverend Thomas Elford Poynting (1830-1878), Unitarian Minister of Monton.
1905
Poynting was awarded the Royal Medal for the most important contributions to the advancement of natural knowledge and one for distinguished contributions in the applied sciences.
University of Manchester, Manchester, England, United Kingdom
From 1867 to 1872 Poynting attended Owens College, Manchester (now the University of Manchester).
London University, London, England, United Kingdom
In 1872 Poynting received the Bachelor of Science from London University.
Trinity College, Trinity Street, Cambridge, England, United Kingdom
Poynting studied mathematics at Trinity College, Cambridge, from 1872 to 1876, where he attained high honors in mathematics.
Royal Society, 6–9 Carlton House Terrace, London, England, United Kingdom
Poynting was a member of the Royal Society from 1887.
John Henry Poynting (1852–1914), Professor of Physics, Bernard Munns (1869–1942), photo credit: University of Birmingham.
Birmingham University, Birmingham, West Midlands, United Kingdom
In 1901 Poynting was awarded an honorary Master of Science in Pure Science by Birmingham University.
educator physicist scientist author
John Henry Poynting was born on September 9, 1852, in Monton, near Manchester, England. He was the youngest son of the Reverend Thomas Elford Poynting (1830-1878), Unitarian Minister of Monton.
In his boyhood Poynting was educated at the nearby school operated by his father. Then he attended Owens College, Manchester (now the University of Manchester) from 1867 to 1872. In 1872 he received the Bachelor of Science from London University. He studied at Trinity College, Cambridge, from 1872 to 1876 and was the third wrangler in the mathematical tripos in 1876. He received the Doctor of Science degree from Cambridge in 1887. In 1901 Poynting was awarded an honorary Master of Science in Pure Science by Birmingham University.
After Poynting returned to Owens College as a demonstrator in physics under Balfour Stewart in 1878. Poynting then returned to Cambridge and did research in the Cavendish Laboratory, under the direction of Maxwell. He was appointed a professor of physics at Mason College, Birmingham, on its founding in 1880 and remained there for the rest of his life. When Mason College became the University of Birmingham in 1900, Poynting became dean of the Faculty of Science, a position he held for twelve years.
After receiving his Doctor of Science degree from Cambridge in 1887, he became a fellow of the Royal Society the following year. Poynting was chairman of the Birmingham Horticultural Society; he also served as a Justice of the Peace.
From the time of his stay at the Cavendish Laboratory, Poynting performed painstaking experiments to measure the mean density of the earth or, equivalently, the constant of universal gravitation. Instead of using a torsion balance, as had Cavendish a century before, Poynting employed a beam balance. His best result, reported in 1891, differs from the presently accepted value by about four parts in a thousand. He admitted, however, that the use of the quartz-fiber torsion balance by C. V. Boys for the same purpose had proved to be inherently more accurate; and he employed that instrument in his later experiments on radiation pressure. In research performed with assistants at Birmingham, Poynting placed small upper limits on any dependence of the gravitational force between crystals on their orientation, and on any effect of temperature on gravitation.
The Poynting flux was derived in his paper of 1884 from Maxwell’s electromagnetic field theory. The term flux appears in an equation representing the energy balance in a closed region (“Poynting's theorem”), and the concept was applied to trace the flow of energy around a conducting wire, a discharging capacitor, and a voltaic cell, and in an electromagnetic wave. Other work in electricity included the design of electrical instruments and discussion of Lodge’s models for representing the electromagnetic field. Poynting also did experiments on radiation pressure.
At the turn of the century, P. N. Lebedev, E. F. Nichols, and G. F. Hull demonstrated the pressure exerted normal to a material surface. In 1904, with the aid of his colleague Guy Barlow, Poynting measured the tangential stress when a beam of light was reflected at an angle from a partially absorbing surface. This effect of the momentum carried by radiation had the experimental advantage of being less masked than the normal pressure by forces exerted by the unevenly heated residual gas in the apparatus. Poynting also demonstrated the existence of torque on a prism so arranged that a beam of light emerged parallel to, but shifted from, the line of incidence. Perhaps of greater importance was his work with Barlow on the recoil of a heated, radiating body as a result of its own radiation, which work formed the subject of the Bakerian lecture for 1910.
The effect of radiation pressure on dust in the solar system, and the use of the law for the intensity of radiation from a blackbody to estimate the temperature of the planets, also interested Poynting. Other theoretical work involved a more thorough discussion of the phase transition between the solid and liquid states (1881) and of osmotic pressure (1896).
He developed instruments for research and for lecture-demonstration and performed research confirming his own predictions concerning the behavior of loaded wires under torsion (1905, 1909). Among Poynting's earliest works were statistical studies on drunkenness in England (1877, 1878) and on the fluctuation of commodity prices (1884). Besides his Adams Prize essay, he wrote The Pressure of Light and The Earth and was a co-author with J . J. Thomson of a series of physics textbooks.
John Poynting grew up in the religious family where his father served as a Unitarian minister.
Poynting was a member of the Physical Society and a member of the Royal Society from 1887. He was also a member of the Birmingham Horticultural Society.
Poynting was known as a person with an amiable personality and had a reputation of an excellent and beloved teacher.
In his spare time, he enjoyed rowing joined the Second Trinity Boat Club and rowed in the first boat in 1875.
Physical Characteristics: In his later years, John Poynting suffered from the bad case of influenza which caused him a diabetic attack and became fatal.
In 1880 Poynting married Maria Adney Cropper. Upon his death, he was survived by his widow, a son, and two daughters.