TEALL, JETHRO JUSTINIAN HARRIS

(b. North-leach, England, 5 January 1849; d. Dulwich, England, 2 July 1924), petrography, geology.

The son of Jethro Teall, a landowner of Sandwich, Kent, and Mary Hathaway of Northleach, Teall was born after the death of his father. He was educated at Northleach Grammar School, at Cheltenham, and at St. John’s College, Cambridge, taking the natural sciences tripos in 1872 and receiving the M.A. in 1876. He was inspired to choose geology instead of mathematics at Cambridge by his tutor, T. G. Bonney, and attended Adam Sedgwick’s geology course as Woodwardian professor. Teall was the first recipient of the Sedgwick Prize, in 1874, for an essay dealing with the phosphatic deposits near Cambridge. Election to a fellowship of his college followed in 1875, and he retained this post until his marriage to Harriet Cowen of Nottingham, in 1879. The years between 1872 and 1888 were divided between lecturing under the University Extension Scheme in the Midlands, in the north and west of England, and in London, and petrographical research at Cambridge. His lectures attracted large audiences; and his association with the early days of University College, Nottingham, is particularly remembered.

The field of petrography was almost new at this time. The polarizing microscope had been developed by W. H. Fox Talbot in 1834 by making use of William Nicol’s single-vision calcite prism (1829). Thin sections were made by H. C. Sorby in the 1850’s and J. Clifton Ward had applied the technique to Lake District lavas during the ensuing decade, but a great avenue of research was opening up. Through his work on the pitchstone of Eigg, the whin sill and dikes of northern England, the Cheviot lavas, the Cornish granites, and Lizard gabbros, Teall gave major impetus to the subject. From 1886 to 1888 he was engaged in publishing the definitive work on British petrography with which his name will always be associated. The encouragement given by Bonney and the influence of Rosenbusch, leading petrographical systematist of the time in Europe, had borne good fruit; and Teall had added many new ideas of his own to both igneous and metamorphic petrography.

In 1888 Sir Archibald Geikie invited Teall to join the Geological Survey of Great Britain as a geologist, to take charge of the petrographical work. The primary geological survey of the northwestern Highlands of Scotland had begun in 1885, and its spectacular results demanded close petrographical study. This Teall provided, for the Highlands and for other parts of the United Kingdom, in a series of contributions to official memoirs and a number of important private papers appearing between 1888 and 1903. In 1901 he was chosen to succeed Geikie as director of the Geological Survey. He was at the same time president of the Geological Society of London; and his influential addresses to the Society on the evolution of petrological ideas (1901, 1902) were considered sufficiently important by the Smithsonian Institution to reproduce in its Report of the Board of Regents. . . .

During his eleven years as director of the Geological Survey, Teall’s output of original work was necessarily curtailed by the demands of administration; but he had the satisfaction of leading the official British geological effort during a productive period. His contributions to science were recognized by his election to the Royal Society in 1890 and by the award of the Bigsby Medal of the Geological Society in 1889 and its highest award, the Wollaston Medal, in 1905. The Paris Academy presented him with its Delesse Prize in 1907; and his official work was recognized with a knighthood in 1916.

BIBLIOGRAPHY

I. Original Works. A full list of Teall’s writings is given in the Geological Magazine article cited below. They include “On the Chemical and Microscopical Characters of the Whin Sill,” in Quarterly Journal of the Geological Society of London, 40 (1884), 640–657; “The Metamorphosis of Dolerite into Hornblende-Schist,” ibid., 41 (1885), 133–144; British Petrography, With Special Reference to the lgneous Rocks (London, 1888); and “The Evolution of Petrological Ideas,” in Quarterly Journal of the Geological Society of London, 57 (1901), lxii–lxxxvi, and 58 (1902), lxiii–lxxviii.

II. Secondary Literature. Biographies are H. H. Thomas, “Sir Jethro Justinian Harris Teall,” in Dictionary of National Biography for 1922–1930 (1937), 826–827; and H. Woodward, “Eminent Living Geologists. Jethro Justinian Harris Teall,” in Geological Magazine, 5th ser., 6 (1909), 1–8. Obituaries are in E. B. Bailey, Geological Survey of Great Britain (London, 1952), 144–170; J. S. Flett, The First Hundred Years of the Geological Survey of Great Britain (London, 1937), 143–160; Proceedings of the Royal Society, B 97 (1925), xv–xvii; Quarterly Journal of the Geological Society of London, 81 (1925), lxiii–lxv.

K. C. Dunham