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Wood, Robert Williams


(b. Concord, Massachusetts, 2 May 1868; d. Amityville, New York, 11 August 1955)

experimental physics.

Wood’s chief contributions to science lay in physical optics, particularly in spectroscopy, in which he obtained experimental results of great significance for the advance of atomic physics during the first third of the twentieth century. He was an extremely versatile laboratory worker, and his insatiable curiosity took him into many other scientific and technical fields, such as the photography of sound waves, properties of ultrasonic radiation, color photography, molecular physics, the manufacture of high-precision diffraction gratings, fluorescence, and scientific crime detection. His book Physical Optics(1905) became the classic treatise on the experimental aspects of the subject in its day, and went through three editions.

Wood did his undergraduate work at Harvard College, where in 1891 he received the B.A. degree with a major in chemistry. His academic record was undistinguished in the required fields of languages and mathematics, but he early showed enthusiasm for all aspects of science. His graduate work took him to Johns Hopkins, Chicago, Berlin, and the Massachusetts Institute of Technology. This graduate study never led to an earned doctorate, and Wood had to content himself with honorary degrees. Early in his career he shifted from chemistry to physics; and by the time he began teaching at the University of Wisconsin in 1897, he had definitely settled down to the life of a physicist. In 1901 Wood succeeded Henry A. Rowland as professor of experimental physics at Johns Hopkins, where he remained for the rest of his life, retiring officially in 1938 but continuing in an honorary capacity until his death.

Before he assumed his professorial duties at Johns Hopkins, Wood had published more than thirty papers covering a wide range of investigations in physics and chemistry. This early work clearly indicated his Zest for experimentation and his great ingenuity in devising relatively simple ways to exhibit spectacular effects. Color always fascinated him and entered vitally into much of his work. Zeal for mathematical symbolism seems to have been missing from his make-up. He preferred to express his experimental results in terms of physical pictures that he felt he (and many others) could understand better than mathematical equations, which he found rather boring. This trait, which persisted throughout his life, in no way interfered with the fundamental logic of his physical reasoning.

At Johns Hopkins Wood’s teaching duties were light and he devoted himself mainly to research, which for over three decades was concentrated primarily on the optical properties of gases and vapors, a field in which he soon established himself as an internationally recognized authority. His work on sodium vapor was especially noteworthy. The extensive precision measurements of atomic spectra stimulated much similar work in this area, and all of it proved to be of the utmost importance in connection with the growing interest in atomic models during the early years of the twentieth century. The Bohr theory, in particular, leaned very heavily on spectroscopic data such as those provided by Wood and others whose work was suggested by him. This was particularly true of Wood’s fundamental experimental work from 1903 to 1920 on fluorescence and resonance radiation of vapors and also the effect of electric and magnetic fields on spectrum lines. Wood also greatly stimulated research in optical spectroscopy by his improvements in the diffraction grating and his determination to ensure a steady supply of high-quality gratings to investigators throughout the world by keeping Rowland’s ruling engines steadily at work.

Throughout his professional career Wood was continually on the lookout for interesting new phenomena to study, particularly those involving striking effects. During World War I and in the late 1920’s he became interested in high-frequency sound waves and their physical and biological properties. Wood performed many experiments in collaboration with A. L. Loomis at the latter’s Tuxedo Park laboratory. These experiments received considerable publicity through the Colver lectures at Brown University in 1937 and the book based on them, Supersonics, the Science of Inaudible Sounds (1939). This work, although popular in presentation, aroused great interest and undoubtedly stimulated research in the important field of acoustics now known as ultrasonics.

A master lecturer with highly developed showmanship, Wood much enjoyed talking to large audiences and demonstrating his ideas with graphic experiments–the more spectacular the better. His name on the program of a meeting of the American Physical Society always guaranteed the attendance of a large crowed to hear his paper. Much more confident in experimental results than in abstract, mathematical reasoning, Wood was never satisfied until an experimental showed with complete clarity the idea he was trying to communicate. He often carried his showmanship into the perpetration of practical jokes; this led to the invention of a host of stories about his exploits that have become legendary among American physicists.

In his teaching of optics, Wood early felt the need for a book that would emphasize, to a greater extent than available standard texts, the experimental aspects of twentieth-century research on light. His Physical Optics satisfied an existing need for more information about the kind of optical techniques he himself was introducing. A fourth edition was being prepared at the time of his death.

Inevitably, as a result of his zeal for experimentation, Wood made many inventions. He was usually too restless, however, to follow them through the development stage into practical, salable devices. He was more successful financially as a legal consultant in cases involving scientific and related technical matters, as well as with his delightful little book How to Tell the Birds From the Flowers, and Other Woodcuts. First published in 1917, it went through twenty editions. Written to amuse Wood’s children, it entertained hosts of others who knew nothing of his scientific achievements. Also worthy of mention is his experimentation with humorous scientific verse, of which his “Contemptuary Science” (relativity and Michelson optics) is a good example.

Wood traveled widely both in the United States and abroad. He received many honors in recognition of his accomplishments. In addition to his membership in the National Academy of Sciences, he was one of the relatively few foreign members of the Royal Society. He also belonged to numerous other foreign academies and societies, and received six honorary degrees and numerous medals.


I. Original Works. Wood’s complete scientific bibliography includes 2 books and 227 articles. The complete list is in Dieke’s memoir (below). The following is a selection intended to illustrate the breadth of his work.

His books are Physical Optics(New York-London, 1905; 2nd ed., 1911; 3rd ed.,1934) and Supersonics, the Science of Inaudible Sounds (Providence, R. I., 1939).

Wood’s earliest article are “The Kingdom of the Dream. Experience With Hasheesh,” in New York Sunday Herald (23 Sept. 1888); “Effects of Pressure on Ice,” in American Journal of Science, 3rd ser., 41 (1891), 30–33; “Eine einfache Methode die Dauer von Torsions-schwingungen Zu bestimmen,” in Wiedemann’s Annalen der Physik und Chemie, n.s. 56 (1895), 171–172; “Ueber eine neue From der Quecksilber Luftpumpe und die Erhaltung eines guten Vacuums bei Röntgen’schen Versuchen,” ibid., 58 (1869), 205–208; “On the Absorption Spectrum of Solutions of Iodine and Bromine Above the Critical Temperature,” in Philosophical Magazine, 5th ser., 41 (1896), 423–431; Zeitschrift für physikalische Chemie, 19 (1896), 689–695; “A New From of Cathode Dicharge and the Production of X-Rays, Together With Some Notes on Diffraction,” in Physical Review, 5 (1897), 1–10; “Phase-Reversal Zone-Plant and Diffraction Telescope,” in Philosophical Magazine, 5th ser.,45 (1898), 511–522; “The Anomalous Dispersion of Cyanin,” ibid., 46 (1898), 380–386; “An Application of the Diffraction Grating to Colour Photographic,” ibid., 47 (1899), 368–372; and “Photography of Sound Waves by the ‘Schlieren Methode,’” ibid., 48 (1899), 218–227.

Papers written early in the twentieth century are “Zone Plate Photography,” in Photographic Journal, 24 (1900), 248–250; “The Photography of Sound Waves and the Demonstration of the Evolutions of Reflected Wave Fronts With the Cinematograph,” in Philosophical Magazine, 5th ser., 50 (1900), 148–157; Chemical News, 81 (1900), 103; Proceedings of the Royal Society, A66 (1900), 283–290; Report of the Board of Regents of the Smithsonian Institutionfor 1900 (1901), 359; “An Application of the Method of Striate to the Illumination of Object Under the Microscope,” in Philosophical Magazine, 5th ser., 50 (1900), 347–349; “Vortex Rings,” in Nature, 63 (1901), 418–420; “The Problem of the Daylight Observation of the Corona,” in Astrophysical Journal, 12 (1901), 281–286; “The Nature of the Solar Corona,” ibid., 13 (1901), 68–79; “The Anomalous Dispersion of Carbon,” in Philosophical Magazine, 6th ser., 1 (1901), 405–410; “On the Production of a Bright-Line Spectrum by Anomalous Dispersion and Its Application to the ‘Flash-Spectrum,’” ibid., 551–555; Naturwissenschaftliche Rundschau, 16 (1901), 394; Astrophysical Journal, 13 (1901), 63–67; “Anomalous Dispersion of Sodium Vapour,” in Proceedings of the Royal Society, 69 (1901), 157–171; “The Invisibility of Transparent Objects,” in Physical Review, 15 (1902), 123–124; “Absorption, Dispersion, and Surface Colour of Seleninum,” in Philosophical Magazine, 6th ser., 3 (1902), 607–622; “On a Remarkable case of Uneven Distribution of light in a Diffraction Grating Spectrum,” ibid., 4 (1902), 396–402; and “The kinetic Theory of the Expansion of Compressing Gas Into a Vacuum,” in Science, 16 (1902), 908–909.

Also see “Screens Transparent Only to Ultra-Violet Light and Their Use in Spectrum Photography,” in Philosophical Magazine, 6th ser., 5 (1903), 257–263; Physikalische Zeitschrift, 4 (1903), 337–338; and Astrophysical Journal, Journal, 17 (1903), 133–140; “On the Anomalous Dispersion, Absorption and Surface Colour of Nitroso Dimethyl Aniline With a Note on the Dispersion of Toluene,” in Philosophical Magazine, 6th ser., 6 (1903), 96–112; Records of the American Academy of Arts and Sciences, 39 (1903), 51–66; “Electrical Resonance of Metal Particles for Light Waves. Third Communication,” in Philosophical Magazine, 6th ser., 6 (1903), 259–266; “Flourescence and Absorption Spectra of Sodium Vapour,” ibid., 362–374; and Astrophsical Journal, 18 (1903), 94–111; written with J. H. Moore; “The N-Rays (Letter Exposing Delusion),” in Nature, 70 (1904), 530–531; “Apparatus to Illustrate the Pressure of Sound Waves,” in Physical Review, 20 (1905), 113–114; and Physicaliche Zeitschrift, 6 (1905), 22; “The Magnetic Rotation of Sodium Vapour,” in Physical Review, 21 (1905), 41–51, written with H. W. Springsteen: “The Magneto-Optics of Sodium Vapour and the Rotatory Dispersion Formula,” in Philosophical Magazine, 6th ser., 10 (1905), 408–427; “The Fluorescence of sodium Vapour and the Resonance Radiation of Electrons,” ibid., 513–525; “Abnormal Polarization and Colour of Light Scattered by Small Absorbing Particles,” ibid., 12 (1906), 147–149 “Die Temperaturstrahlung des Joddampfes,” in Physikalische Zeitschrift, 8 (1907), 517; “Polarized Fluorescence of Metallic Vapors and the Solar Corona,” in Astrophysical Journal, 28 (1908), 75–78; “An Extension of the Principal series of the Sodium Spectrum,” in Philosophical Magazine, 6th ser., 16 (1908), 945–947; “The Mercury Paraboloid as a Reflecting Telescope,” in Astrophysical Journal, 29 (1909), 164–176; and “The Ultra-Violet Absorption, Fluorescence, and Magnetic Rotation of Sodium Vapour,” in Philosophical Magazine, 6th ser., 18 (1909), 530–535.

During the second decade of the century, Wood wrote, “Determination of Stellar Velocities with the Objective Prism,” in Astrophysical Journal, 31 (1910), 376–377; “The Echelette Grating for the Infra-Red,” in Philosophical Magazine, 6th ser., 20 (1910), 770–778; “The Resonance Spectra of Iodine,” ibid., 21 (1911), 261–265: “Diffraction Gratings With Controlled Groove Form and Abnormal Distribution of Intensity,” ibid., 23 (1912), 310–317; and Physikalische Zeitschrift, 13 (1912), 261–264; “Selective Absorption of Light on the Moon’s Surface and Lunar Petrography,” in Astrophysical Journal, 36 (1912), 75–84; “Method of Obtaining Very Narrow Absorption Lines for Investigations in Magnetic Fields,” in Physikalische Zeitschrift, 14 (1913), 405, written with P. Zeeman; “The Satellites of the Mercury Lines,” in Philosophical Magazine, 6th ser., 25 (1913), 443–449; and Physicalische Zeitschrift, 14 (1913), 273–275; “The Effect of Electric and Magnetic Fields on the Emission Lines of Solids,” in Philosophical Magazine, 6th ser., 30 (1915), 316–320, written with C. E. Mendenhall; “Monochromatic Photographs of Jupiter and Saturn,” in Astrophysical Journal, 43 (1916), 310–319; and “Condensation and Reflection of Gas Molecules,” in Philosophical Magazine, 6th ser., 32 (1916), 364–371.

In the 1920’s Wood produced “Light Scattering by Air and the Blue colour of the Sky,” in Philosophical Magazine, 6th ser., 39 (1920), 423–433; “Extension of the Balmer Series of Hydrogen, and Spectroscopic Phenomena of Very Long Vacuum Tubes,” in Proceedings of the Royal Society, A97 (1920), 455–470; “On the Influence of Magnetic Fields on the Polarization of Resonance Radiation,” ibid., A103 (1923), 396–403, written with A. Ellett; “Fine Structure, Absorption and Zeeman Effect of the 2536 Mercury Line,” in Philosophical Magazine, 6th ser., 50 (1925), 761–774; and Nature, 115 (1925), 461; “Improved Grating for Vacuum Spectrographs,” in Philosophical Magazine, 7th ser., 2 (1926), 310–312, written with T.Lyman; “The Physical and Biological effects of High Frequency Sound Waves of Great Intensity,” ibid., 4 (1927), 417–436, written with A. L. Loomis; “Anti-Stokes Radiation of Fluorescent Liquids,” ibid., 6 (1928), 310–312; “Raman Spectra of Scattered Radiation,” ibid., 729–743; and “Improved Technique for the Raman Effect,” in Physical Review, 33 (1929), 294,and 36 (1930), 1421- 1430.

His last works were “Absorption Spectra of Salts in Liquid Ammonia,” in Physical Review, 38 (1931), 1648–1650; “The Purple Gold of Tut-Ankhamun,” in Journal of Egyptian Archaeology, 20 (1934), 62–65; “Fluorescence of Chlorophyll in Its Relation to photochemical Processes in Plants and Organic Solutions,” in Journal of Chemical Physics, 4 (1936), 551–560, written with J.Franck; and “Improved Diffraction Gratings and Replicas,” in journal of the Optical Society of America, 34 (1944), 509–516.

II. Secondary Literature. See the biographical sketch by G. H. Dieke in Biographical Memoirs of Fellows of the Royal Society, 2 (1956), 327–345; and William Seabrook, Doctor Wood–Modern Wizard of the Laboratory (New York, 1941).

R. B. Lindsay

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Wood, Robert Williams

Robert Williams Wood, 1868–1955, American physicist, b. Concord, Mass., grad. Harvard (B.A., 1891). After studying abroad he became associated with Johns Hopkins as professor of experimental physics in 1901, professor emeritus in 1938, and later research professor. Internationally known for his work in optics and spectroscopy, he made important researches in resonance radiation and in the use of absorption screens in astronomical photography and devised a vastly improved diffraction grating. He also developed a color-photography process, originated the method of thawing street mains by passing an electric current through them, and studied the biological and physiological effects of high-frequency sound waves. He wrote Physical Optics (1905) and Researches in Physical Optics (2 parts, 1913–19). Wood was also the author of The Man Who Rocked the Earth (with Arthur Train, 1915) and nonsense verse, How to Tell the Birds from the Flowers (rev. ed. 1917).

See biography by W. Seabrook (1941).

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"Wood, Robert Williams." The Columbia Encyclopedia, 6th ed.. . 21 Aug. 2017 <>.

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"Wood, Robert Williams." The Columbia Encyclopedia, 6th ed.. . Retrieved August 21, 2017 from