Coblentz, William Weber
Coblentz, William Weber
(b. North Lima, Ohio, 20 November 1873; d. Washington, D. C., 15 September 1962),
Coblentz, the older son of David Coblentz and Catherine Good, was raised on a farm under relatively primitive conditions. He was graduated from the Case School of Applied Science (now Case Western Reserve University) in 1900. He then entered Cornell University, receiving an M. S. in 1901 and a Ph.D. in 1903. Upon graduation Coblentz accepted an appointment as research associate of the Carnegie Institution of Washington, to work two years as an honorary fellow at Cornell. He began an extension of his thesis topic by measuring the spectral absorptions of thousands of molecular substances.
In 1904 Coblentz joined the staff of the National Bureau of Standards, where he continued his work on the infrared spectroscopy of various molecules. Moreover, he made numerous important contributions to other areas of radiation measurement. He was the first to determine accurately the radiation constants of a blackbody and thus to verify Planck’s law. In 1914 he used the Crossley reflector at the Lick Observatory to measure the heat radiated from 110 stars, as well as from planets and nebulae. Later he extended these measurements, using the facilities at Lowell Observatory and at Mount Wilson Observatory. The thermopiles he constructed at the National Bureau of Standards, sought after for their exceptional sensitivity, were used in studies significant to botany, physiology, and psychology, as well as to physics. However, Coblentz is known more for the studies he made with these instruments than for the instruments themselves.
Coblentz was chief of the radiometry section of the National Bureau of Standards from 1905 until 1945. He was widely honored for his pioneering contributions, which extended from infrared radiometry and spectroscopy through astrophysics to medical problems and ultraviolet therapy. The thoroughness and accuracy of his work established great confidence in him among physicists, so that it has been said that he was responsible for the adoption of radiometric standards, from the extreme ultraviolet to the far infrared.
I. Original Works. Among Coblentz’s papers are “Some Optical Properties of Iodine,” In Physical Review, 16 (1903), 35–50, 72–93; 17 (1903) 51–59, his doctoral thesis; “Methods of Measuring Radiant Energy,” ibid., 17 (1903), 267–276, written with E. L. Nichols; Investigations of Infrared spectra. Part I. Absorption Spectra; Part II. Emission Spectra, Carnegie Institution of Washington, publication no. 35 (Washington, D.C., 1905); Investigations of Infrared Spectra. Part III. Transmission Spectra; Part IV. Reflection Spectra, Carnegie Institution of Washington, publication no. 65 (Washington, D.C., 1906); Investigations of Infrared Spectra. Part V Reflection Spectra; Part VI. Transmission Spectra; Part VII. Emission spectra, Carnegie Institution of Washington, publication no. 97 (Washington, D.C., 1908); “Instruments and Methods Used in Radiometry. I,” in Bulletin of the Bureau of Standards, 4 (1908), 391–480; “The Blanket Effect of Clouds,” in Monthly Weather Review. U.S. Department of Agriculture, 37 (1909), 65–66; A Physical study of the Firefly, Carnegie Institution of Washington, publication no. 164 (Washington, D.C., 1911); “The Constants of Spectral Radiation of a Uniformly Heated Enclosure or So-called Black Body. I,” in Bulletin of the Bureau of standards, 10 (1913), 1–77; “Note on the Radiation from Stars,” in American Astronomical Society Publications, 3 (1914), 76–78; “A Comparison of Stellar Radiometers and Radiometric Measurements of 110 Stars,” in Bulletin of the Bureau of Standards, 11 (1915), 613–656; “Relative Sensibility of the Average Eye to Light of Different Colors and Some Practical Applications to Radiation Problems,” ibid., 14 (1917), 167–236, written with W. B. Emerson; “A Radiometric Investigation of the Germicidal Action of Ultraviolet Radiation,” in Scientific Pa pers of the United states Bureau of Standards, 19 (1924), 641–680, written with H. R. Fulton, “Is There Life on Other Planets?” in The Forum, 74 (1925), 688–696); “Spectral Energy Distribution of the Light Emitted by Plants and Animals,” in Scientific Papers of the United States Bureau of Standards, 21 (1926), 521–534, written with C. W. Hughes; “Instruments for Measuring Ultraviolet Radiation and the Unit of Dosage in Ultraviolet Therapy,” in Medical Journal and Record, 130 (1929), 691–695; “The Biologically Active Component of Ultraviolet in Sunlight and Daylight,” in Transactions of the Illuminating Engineering Society, 26 (1931), 572–578; “The Emergence of the Cicada,” in ScientificMonthly, 43 (1936), 239–243; and “Circulation of Ozone in the Upper Atmosphere,” in Bulletin. American Meteorological Society, 20 (1939), 92–95.
His autobiography, From the Life of a Researcher (New York, 1951), provides a keen insight into his character.
II. Secondary Literature. Many additional facts regarding Coblentz’s career are in Biographical Memoirs. National Academy of Sciences, 49 (1967), 55–102, which also gives a complete bibliography of his scientific writings. The November 1963 issue of Applied Optics was a commemorative volume to him and contains several assessments of his work.
D. J. Lovell