Biographical Memoirs Volume 45 (1974) / Chapter Skim
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Harold Delos Babcock
Harold Delos Babcock
Pages 1-21
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With their help Harold learned to read before reaching school age, and he acquired a lifelong love of music. From an old ~ The Academy is indebted to Horace W
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The discharge of a high-voltage condenser was used to produce the signal, which was received by a "coherer" patterned after Marconi's apparatus. Years later Babcock built his own apparatus for receiving early radio broadcasts and in 1940 received his license as an amateur radio operator.
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M Hall of the Department of Biology of the university on a five hundred-mile botanical collecting expedition in the southern High Sierra.
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In lS96 Zeeman had discovered that spectral lines emitted in a strong magnetic field were split into three or more components, the width of the pattern of lines being proportional to the strength of the field. Twelve years later Hale observed with the sixty-foot solar tower telescope on Mount Wilson the ~.
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During the first decades of the present century, spectroscopy experienced a tremendous development. This was especially so in astronomy, since it was realized that spectroscopy held the key to many problems, including chemical compositions, temperatures, pressures, radial velocities, and magnetic fields of astronomical bodies.
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Because of the important role that these studies played in the establishment of the basic wavelength standards, Babcock was asked in 1925 and again in 1928 to serve as president of the Commission des Etalons du Longueur d'Onde et des Tables de Spectres Solaires of the International Astronomical Union. Using the same precision techniques, St.
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In 1947 Babcock and Charlotte Moore published a second volume repeating many of the earlier infrared measurements and extending them to 13,500 A in the far infrared. The following year Babcock, with Miss Moore and Mary F
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60~6O, 070, and i60~80 molecules. This discovery that oxygen had isotopes of mass seventeen and eighteen and that ordinary oxygen was a mixture of these with the predominant isotope of mass sixteen had a fundamental impact on the atomic weight systems as determined from chemical analyses and from mass-spectrograph observations.
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Moreover, when ruled on aluminum evaporated onto Pyrex blanks, the gratings had a sensitivity to temperature only about one twenty-fifth of that of prisms. Because of these advantages, all prisms in the spectrographs at Mount Wilson were replaced with Babcock's gratings, and noteworthy improvements were achieved in resolving power, speed, and stability.
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In the course of these observations it was found that this general magnetic field of the sun reverses with the eleven-year period of the sunspot cycle. Babcock participated in the Mount Wilson Observatory expeditions to observe solar eclipses in 1918, 1923, 1930, and 1932.
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He was a member of the American Physical Society, the American Astronomical Society, and the Astronomical Society of the Pacific and was an Associate of the Royal Astronomical Society. The University of California conferred the honorary LL.D.
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Soc. Physical Society of London Optical Society Popular Astron.
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l., 55:3647. 1923 A study of the green auroral line by the interference method.
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A revision of Rowland's preliminary table of solar spectrum wavelengths. Carnegie Inst.
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Sci., 15: 471-77. Report of the Commission des Etalons de Longueur d'Onde et des Tables de Spectres Solaires.
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Hoge. New data on the absorption bands of atmospheric oxygen.
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(A) Report to the Commission des Etalons de Longueur d'Onde et des Tables de Spectres Solaires.
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lg50 A derivation of the vacuum wave numbers and the reduction of measured wavelengths to standard atmospheric conditions. Astrophys.
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Phospheric magnetic fields. In: Electromagnetic Phenomena in Cosmical Physics, ed.
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