The English physicist John William Strutt, 3d Baron Rayleigh (1842-1919), was one of the last of the great individual classical physicists whose interests spanned all disciplines.

John William Strutt was born in Maldon, Essex, on Nov. 12, 1842, the eldest son of the 2d Baron Rayleigh, a prosperous Essex farmer and landowner. His talent in mathematics was recognized early, and in 1861 he entered Trinity College, Cambridge. Under the tutelage of a great teacher, E. J. Routh, he captured in 1865 the coveted position of senior wrangler and also won the Smith's Prize. At Terling Place, the family seat in Essex, he converted the stables into a laboratory. There he commenced experimental studies in photography, optics, electricity, and acoustics, working alone for the next 50 years. He remained active in his laboratory until a few days before his death on June 30, 1919.

In 1870 Strutt derived theoretically, and verified experimentally, the mechanism of the scattering of light by small particles (Rayleigh scattering), thus explaining the blue of the sky and red of the sunset. In 1872 he spent 3 months in Egypt convalescing from an attack of rheumatic fever; and although far from any library, he occupied his mind by writing a large part of his book The Theory of Sound (1879), which is still considered the bible of acoustics. On the death of his father in 1873, Strutt became the 3d Baron Rayleigh. After the death of James Clerk Maxwell in 1879, Lord Rayleigh served as the second Cavendish professor of physics at Cambridge, from 1880 to 1885. There he commenced a series of experimental investigations in electricity which led to new standard definitions of the volt, the ohm, and the ampere.

In 1891 Rayleigh succeeded John Tyndall as professor of physics at the Royal Institution in London. In studying carefully the densities of several common atmospheric gases, including hydrogen, oxygen, and nitrogen, he observed that nitrogen separated from the atmosphere was very slightly (1 part in 2,000) heavier than "chemical" nitrogen obtained by the dissociation of ammonia. He suspected the presence of an impurity and cooperated with the chemist William Ramsay, though both worked separately and in great secrecy. They astonished the scientific world in January 1895 by announcing that they had isolated a new element which they named argon (because of its inert chemical nature). They even proposed a new zeroth column for such elements in the periodic table. For this Rayleigh received the Nobel Prize in physics in 1904.

By his marriage to Evelyn Balfour, Rayleigh was brought close to high government circles: her uncle, the Marquis of Salisbury, was prime minister from 1885 to 1901, and her brother, Arthur Balfour, was also prime minister. Consequently, Rayleigh was influential in many government policies relative to science.

Rayleigh's honors are almost too numerous to mention. He was one of the original members of the Order of Merit and was secretary and later president of the Royal Society.

Further Reading

• Robert John Strutt, 4th Baron Rayleigh, wrote John William Strutt, Third Baron Rayleigh (1924; rev. ed., 1968, entitled Life of John William Strutt, Third Baron Rayleigh). Biographical information on Rayleigh can be found in Nobel Foundation, Physics (3 vols., 1964-1967), a collection of Nobel laureates' lectures and biographies. Rayleigh's life and contribution to science are discussed in James Gerald Crowther, Scientific Types (1970).