John Tyndall (2.08.1820-4.12.1893) was an English physicist and a Fellow of the Royal Society (1852). He was born in Leighlinbridge (Ireland). He graduated from the Mechanics' Institute in Preston (1844). In 1853-87 he was professor at the Royal Institution in London, and in 1867-87 its director.
His work was in the fields of acoustics, heat, optics and magnetism. He studied the absorption of thermal rays by various gases and vapours. In particular, he showed that dry air absorbs thermal rays poorly, and demonstrated (1881) their strong absorption by water vapour. He studied the scattering of light, in particular by turbid media. He discovered the phenomenon of the scattering of light on passing through an optically inhomogeneous medium (the Tyndall effect). He was the first to investigate in detail (1869) the scattering of sunlight by the molecules of the atmosphere, and explained the blue colour of the sky. He was a brilliant lecturer and populariser of science and the biographer of M. Faraday; he is the author of the book “Faraday as a Discoverer”.
The B. Rumford Medal (1864).