St. John, Charles Edward (15 Mar. 1857-26 Apr. 1935), astronomer and educator, was born in Allen, Michigan, the son of Hiram Abiff St. John, a millwright, and Lois Amanda Bacon. His mother was the intellectual force in the family, and it was from her that St. John received the support and encouragement to complete his education in the face of illnesses and economic difficulties.

In 1876 St. John graduated from the Michigan State Normal School (now Eastern Michigan University), but the effort drained him physically and mentally, and he spent nine years rebuilding his strength. Of this period in his life a colleague later wrote, "It is probable, however, that these were the years in which he built up the philosophy of life which he followed throughout his career" (Adams, p. 286). Needing to work, he became an instructor in physics (1885-1892) at the Normal College. He also resumed his studies at the Michigan Agricultural College (later Michigan State University), from which he earned a B.S. in 1887. Following two years (1890-1892) of graduate work in electricity and magnetism at the University of Michigan, he entered Harvard University, where his instructors included John Trowbridge and Benjamin Peirce. He earned his A.M. in 1893 and was awarded the John Tyndall Fellowship, which included a year of graduate work abroad. St. John spent the following year at the Universities of Berlin and Heidelberg and then returned to Harvard, where he received his Ph.D. in physics in 1896.

At Harvard St. John took up experimental and theoretical problems in electrical conduction and self-induction, light, and magnetic permeability in a curriculum that emphasized the laboratory method of teaching physics and original research work. "Wave-lengths of Electricity on Iron Wires," based on experiments he carried out in the Jefferson Physical Laboratory, appeared in the American Journal of Science in 1894. The following year the Annalen der Physik und Chemie published the results of St. John's earlier work in Berlin on black-body radiation.

Doctorate in hand, St. John returned for one year to the University of Michigan as an instructor in physics. In 1897 he was invited to join the faculty of Oberlin College as associate professor of physics and astronomy. "I anticipate a good deal of pleasure and satisfaction in it," he wrote back. He remained at Oberlin for eleven years, rising to professor in 1899 and dean of the College of Arts and Sciences in 1906. Plunging into his new academic position with characteristic enthusiasm and energy, he chaired the college's athletic committee for many years, served on the town's waterworks board, and headed the Second Congregational Church's board of trustees. He also left an indelible mark in the classroom, saving his best performance for advanced and graduate courses. A former student remembered, "His mathematical presentation possessed a remarkable clarity and his laboratory demonstrations were thoroughly prepared and beautifully carried out. In his lectures he often closed his eyes for considerable periods of time in order to concentrate upon the subject." An avid outdoorsman, St. John often spent the summer months exploring the Far West, tramping through British Columbia and Alaska, hiking and camping in the high Sierras, and visiting Yellowstone National Park.

St. John's association with Oberlin and his career as an educator ended in 1908 when he moved to Pasadena, California, to become a staff member of the Carnegie Institution's Mount Wilson Observatory, founded by George Ellery Hale in 1904. At Hale's invitation he had spent several summers, starting in 1898, at the Yerkes Observatory at Williams Bay, Wisconsin, helping Ernest F. Nichols measure the relative heats of fixed stars. Out of that work and his association there with other staff members came the opportunity to start afresh, at age fifty-one, as a research scientist.

At Mount Wilson St. John worked mainly in solar physics. Early on he investigated the H and K lines of ionized calcium in the solar spectrum. He began by measuring the absolute wavelengths of these lines in terrestrial sources in the laboratory and then compared them with the corresponding emission and absorption lines in the solar spectrum, paying special attention to the spectral lines over sunspots and flocculi (calcium and hydrogen clouds in the solar atmosphere). Spurred on by John Evershed's 1909 discovery of differential velocity displacements of Fraunhofer lines in the penumbras of sunspots, St. John carried out between 1910 and 1912 an extensive series of measurements involving hundreds of lines of different elements. From his study of the flow of gases at different levels in sunspots, he concluded that ionized calcium is present at the highest level in the solar atmosphere, followed by hydrogen, with the heavy and rare elements restricted to the lower portions. As a final check, he compared his results with those of spectrums observed by S. A. Mitchell during solar eclipses; there proved to be a high degree of correlation, which gave him much satisfaction. In 1916 he disputed W. H. Julius's ideas about the importance of anomalous dispersion for the displacements in the spectral lines.

As a research scientist, St. John's reputation rests in part on his work on the revision of Henry Rowland's wavelength tables for the solar spectrum, completed and published in 1928. In this massive work St. John, in collaboration with Charlotte Moore, Louise Ware, Edward Adams, and Harold Babcock, corrected and standardized to the international system the wavelengths of 22,000 lines. Their revisions, based on separate measurements made with both grating spectrographs and an interferometer, included many new identifications, the intensities of the lines in sunspots as well as in the solar disk, temperature and pressure classifications, and excitation potentials. An active member of the International Astronomical Union, St. John served as the president of the Union's Solar Physics Commission from 1919 to 1924.

Between 1917 and 1928 St. John measured the gravitational redshift of spectral lines, as predicted by Albert Einstein's theory of general relativity. On the basis of forty lines, he reported negative results in 1917; in 1923, he reversed himself and announced that he was satisfied that the gravitational displacement of the Sun's Fraunhofer spectrum was detectable. His final publication, in 1928, using 1,537 lines, gave the same results. Referring to his original forty lines reported on in 1917, he wrote, "In view of later work on the complete band, these lines might be called the "Forty Thieves."

In 1930 St. John retired, having published eighty papers. Following retirement he was appointed as a research associate. A lifelong bachelor, he died in Pasadena.

 



Bibliography

The George Ellery Hale Papers in the California Institute of Technology Archives, Pasadena, contain a small amount of St. John's correspondence, as do the Harlow Shapley Papers in the Harvard University Archives. The Oberlin College Archives also have some manuscript material. A survey of his career is provided by Walter S. Adams, National Academy of Sciences, Biographical Memoirs 18 (1937): 285-304, with portrait and bibliography. Details about his early career are in obituaries by Alfred H. Joy, Popular Astronomy 43 (1935): 611-17; C. G. Abbot, Astrophysical Journal 82 (1935): 273-83; and Harold D. Babcock, Publications of the Astronomical Society of the Pacific 47 (1935): 115-20. See also Klaus Hentschel, "The Conversion of St. John: A Case Study on the Interplay of Theory and Experiment," Science in Context 6 (1993): 137-94. An obituary is in the New York Times, 27 Apr. 1935.



Judith R. Goodstein




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