STONEY, GEORGE JOHNSTONE

(b. Oakley Park, Kingstown [now Dún Laoghaire], County Dublin, Ireland, 15 February 1826; d. London, England, 5 July 1911)

mathematical physics.

Stoney was the eldest son of George Stoney and his wife, Anne, who were Protestant landowners. The family was a talented one: Stoney’s younger brother, Bindon Blood Stoney (1828–1909); his son, George Gerald Stoney (1863–1942); and his nephew, George Francis Fitzgerald (1851–1901), made significant contributions to science and technology, and were fellows of the Royal Society.

Stoney graduated from Trinity College, Dublin, in 1848 and became assistant to Lord Rosse in his observatory at Parsonstown (now Birr). After failing to obtain a fellowship at Trinity College, he obtained the chair of natural philosophy at Queen’s College, Galway, which he held for five years. In 1857 he returned to Dublin as secretary to Queen’s University, in which post he spent the rest of his working life. Stoney was a member of the Royal Irish Academy and the Royal Dublin Society, and was secretary of the latter for over twenty years. In 1893 he moved to London and became involved in the affairs of the Royal Society, of which he had been elected a fellow in 1861; in 1898 he was vice-president and a member of the Council.

Stoney had an interest in all fields of science and, like many of his Irish contemporaries, applied mathematics to the solution of scientific problems. He was particularly interested in spectrum analysis. A paper he wrote in 1868 suggested that spectral lines were due to periodic motions inside the atom rather than to the translational motion of molecules. Stoney continued this line of thought for a number of years and, as a result, put forward important ideas on atomic structure. In 1891 he explained the presence of double and triple lines in spectra by apsidal and precessional motions of orbital electrons.

Since his early work in Rosse’s observatory, Stoney maintained an interest in astronomy and wrote many papers on the subject. Using the kinetic theory as a basis of his work, he reached certain conclusions concerning the atmospheres of planets. Stoney’s paper of 1897 suggested that if the velocity of molecules exceeded a limit set by the force of gravity, then the molecules would fly off into space. By this means he explained the absence of an atmosphere on the moon.

Stoney probably is best-known for having coined the term “electron.” He hoped that by a careful choice of fundamental units, science would be simplified; and at the 1874 meeting of the British Association, he presented the paper “On the Physical Units of Nature.” One of the basic units he suggested was the charge carried on a hydrogen ion, which he determined from experimental data. The weight of hydrogen liberated on electrolysis by a given quantity of electricity was known; and by calculating the number of atoms associated with this weight of hydrogen, Stoney found the electric charge associated with each atom. A similar theory of electrical atomicity was advanced by Helmholtz in his Faraday lecture in 1881, and ten years later Stoney introduced the word “electron” for this fundamental unit. The term later came to be used for the “corpuscles” discovered by J. J. Thomson.

BIBLIOGRAPHY

I. Original Works. Stoney’s writings include “The Internal Motions of Gases Compared With the Motions of Waves of Light,” in Philosophical Magazine, 4th ser., 36 (1868), 132–141; “On the Physical Units of Nature,” ibid., 5th ser., 11 (1881), 381–389; “On the Cause of Double Lines and of Equidistant Satellites in the Spectra of Gases,” in Scientific Transactions of the Royal Dublin Society, 4 (1891), 563–608; “Of the ’Electron’ or Atom of Electricity,” in Philosophical Magazine, 5th ser., 38 (1894), 418–420; and “of Atmospheres Upon Planets and Satellites,” in Scientific Transactions of the Royal Dublin Society, 6 (1897), 305–328.

II. Secondary Literature. Biographies are by F. T. Trouton in Nature, 87 (1911), 50–51; and by an anonymous author in Proceedings of the Royal Society, 86 (1912), xx–xxv.

Brian B. Kelham