George Ellery Hale
Hale, George Ellery
Hale, George Ellery
(b. Chicago, Illinois, 29 June 1868; d. Pasadena, California, 21 February 1938)
George Hale was the eldest surviving son of William Ellery Hale and Mary Scranton Browne. The family moved from Chicago to the suburb of Hyde Park before the great fire of 1871 destroyed his birthplace and a building erected by William Hale in the heart of Chicago. With the intense energy and engineering ability his son would inherit, William Hale turned to the manufacture of the hydraulic elevators that would make possible the tall buildings of the new Chicago. As his business expanded to other American cities, and even to London and Paris, he prospered.
William Hale’s father had been a minister; Mary Hale, daughter of a Congregational minister who later became a doctor, was raised by her adopted grandfather, a stern Calvinist preacher. In his boyhood George Hale attended the Congregational church but, years later, when his wife asked him to go to church “for the sake of the children,” he wrote: “Of course you must see that it is hard—really impossible—for me to reason one way through the week, and another way on Sunday. My creed is Truth, wherever it may lead, and I believe that no creed is finer than this.”1
Although Hale failed to adopt the religious creed of his parents, he was grateful for the broad cultural outlook they gave him. To his mother, who had been educated at Catharine Beecher’s famous Hartford Female Seminary, he was especially grateful for the love of literature and poetry that he considered vital to the development of his creative scientific imagination. His early reading ranged from Grimm’s Fairy Tales to Don Quixote, from the Iliad and the Odyssey to the poetry of Keats and Shelley, from Cassell’s Book of Sports and Pastimes to Jules Verne’s From the Earth to the Moon.
These wide-ranging interests were consistently pursued in later years. Their diversity is reflected in the role Hale played not only in astronomical and other scientific institutions but also in those dealing with the humanities, in which he worked with equal fervor. The institutions range from the three great observatories he founded—Yerkes. Mt. Wilson, and Palomar (each in its time the greatest in the world)— to the California Institute of Technology and the Henry E. Huntington Library and Art Gallery; from the National Academy of Sciences, which he helped to reform; to the National Research Council, which he initiated; and the International Research Council, out of which evolved the International Council of Scientific Unions.
As a child Hale suffered from intestinal ailments and typhoid; and his mother, who was subject to migraine headaches, worried constantly about her high-strung son. In later life he had three serious breakdowns and was forced to give up work for long periods. At such times he suffered severe depression and acute pain at the back of his head which his doctors called brain congestion. They ascribed his troubles to overanxiety, overintensity, and an inability to relax.
Hale first attended the Oakland Public School, then the Allen Academy. He also took shopwork at the Chicago Manual Training School. Yet, as he wrote:
I never enjoyed the confinements and the fixed duties of school life. Born a free lance, with a thirst for personal adventure, I preferred to work at tasks of my own selection.... As a boy, largely through the constant encouragement of my father, I became interested in tools and machinery at a very early age; I always had a small shop with tools, first in the house, and later in a building of my own construction in the yard. I also had a little laboratory where I performed simple chemical experiments, made batteries and induction coils, worked with a microscope etc. After construction of a small telescope for myself, my father bought me an excellent 4-inch Clark. I used this constantly, but my enthusiasm reached the highest pitch when I learned something about the spectroscope. My greatest ambition was to photograph a spectrum and this I soon succeeded in doing with a small one prism spectroscope purchased for me by my father. I think this was in 1884. Solar spectroscopic work appealed to me above all things and I read everything I could find on the subject. My father always bought for me any books that I needed, but in the case of instruments his policy always was to induce me to construct my own first and then to give me a good instrument if my early experiments were successful. In 1888 he built for me, after my designs, a spectroscopic laboratory, in which a Rowland concave grating of 10 feet local length was erected. This was the nucleus of the Kenwood Observatory.2
This experimental approach to astronomy was in essence the basis for Hale’s scientific goals. He entered astronomy at a time when the majority of astronomers, concerned with the positions, motions, and distances of the stars, evinced little interest in their physical nature. Pioneer work had been done by Angelo Secchi in Italy, William Huggins and J. N. Lockyer in England, P. J. C. Janssen in France, H. C. Vogel in Germany, and a few others. Hale’s influence on the development of the embryonic science of astrophysics was so great that it is often said he contributed more than any other individual to the rise of modern astrophysics. His tools were those he had used in boyhood—the telescope, the spectroscope, the photographic plate; his working place was the observatory combined with laboratory and shop where astrophysical problems might be solved to discover the physical nature of the universe.
In 1886 Hale entered the Massachusetts Institute of Technology. He majored in physics but, in contrast with his own laboratory work, found most of the courses uninspiring. In his spare time he read and abstracted everything he could find on astronomy and spectroscopy at the Boston Public Library. He also persuaded E. C. Pickering, director of the Harvard College Observatory, to let him work there as a volunteer assistant. In August 1889, shortly after his twenty-first birthday, he was riding on a Chicago trolley car when the idea came to him “out of the blue” for an instrument that would solve the problem of photographing the solar prominences in full daylight and would provide a permanent record of these and other solar phenomena. He called it a spectroheliograph.
In 1868 Janssen and Lockyer had observed prominences visually outside of eclipse for the first time. C. A. Young, Károly Braun, and Wilhelm Lohse had tried to photograph the prominences spectroscopically in daylight but without practical success. Later Deslandres would claim priority but this was a full year after Hale had proved the success of his method. (Deslandres did develop successfully what he would call a spectro-enrégisteur des vitesses, or velocity recorder.) In the fall of 1889 Hale tried out his principle at the Harvard Observatory; and in his M.I.T. thesis, “Photography of the Solar Prominences,” he described the results that proved the feasibility of the method. Out of these beginnings was born his lifelong interest in the “typical star”—our sun, the only star near enough to be studied in detail. His contributions to solar research that resulted were, as the Mt. Wilson astrophysicist Robert Howard noted, so vital that “Hale may be said to be the father of modern solar observational astronomy.”3
The day after he graduated from M.I.T., Hale and Evelina Conklin of Brooklyn, New York, were married. On their honeymoon they visited the Lick Observatory, where Hale was inspired by the sight of James Keeler making his classic observations of radial velocities in planetary nebulae with a stellar spectroscope attached to the thirty-six-inch telescope, then the largest in the world.
Back in Chicago, Hale persuaded his father to provide the funds for a telescope with which he could continue his experiments with the spectroheliograph. In June 1891 his twelve-inch refractor with an object glass by John Brashear and mounting by W. R. Warner and Ambrose Swasey was dedicated in his small Kenwood Observatory, located behind their house at 4545 Drexel Boulevard. With it, in 1892, using the H and K lines of calcium in the ultraviolet, Hale photographed the bright calcium clouds (flocculi) and the prominences all around the sun’s limb for the first time, thus proving the success of his instrument.
In 1892 Hale was appointed associate professor of astrophysics at the new University of Chicago. Thai summer he learned of the availability of two fortyinch lenses at the firm of Alvan Clark in Cambridgeport, Massachusetts, and persuaded the traction magnate Charles T. Yerkes to provide for a telescope that would surpass all others in focal length and light-gathering power. In 1893, while plans were being worked out for the new observatory, Hale went to the University of Berlin and worked there with Hermann von Helmholtz, Max Planck, A. A. Kundt, and Heinrich Rubens. At the Potsdam Observatory contacts with Vogel and Julius Scheiner increased his enthusiasm for astrophysical research. Yet before the year’s end Hale abandoned his plans for a Ph.D. and never took time to earn one, although he received many honorary degrees, including one from Berlin. On his way home he attempted to photograph the solar corona outside of eclipse from Mt. Etna. This attempt, tike every other he made, failed. It was not until 1930 that Bernard Lyot in France accomplished this difficult feat.
In 1897 the Yerkes Observatory at Williams Bay, Wisconsin, was dedicated. It was, as Hale noted, based on a revolutionary principle, “in reality a large physical laboratory as well as an astronomical establishment” where “all kinds of spectroscopic, bolometric, photographic and other optical work would be done in its laboratories.”4 Here he gathered a small but devoted staff that included future astronomical leaders. He also encouraged visits from foreign astronomers eager to use the superior facilities, while he himself continued the observation of sunspot spectra begun at Kenwood and designed the Rumford spectroheliograph to be attached to the forty-inch telescope. With this powerful tool, using the Hβ hydrogen line, Hale found the dark hydrogen flocculi and investigated the calcium flocculi at different levels to gain knowledge of the complex circulatory processes in the sun. From the sun he turned to other stars, as he undertook (with Ferdinand Ellerman and J. A. Parkhurst) a study of the spectra of those latetype, low-temperature red stars, known as Secchi’s fourth type, which showed certain marked similarities to sunspot spectra and had never before been photographed.
Meanwhile, Hale promoted the astrophysical cause in other ways. On a triumphal tour abroad in 1891 he had been welcomed by leaders in astronomy and physics. On his return, with their endorsement he and W. W. Payne, editor of the pioneer astronomical journal Sidereal Messenger, founded a journal called Astronomy and Astro-Physics. In 1895, with Keeler as joint editor, he founded the separate Astrophysical Journal with an international board of editors that included astronomers and physicists from England, France, Germany, Italy, and the United States. It is still the leading journal in its field.
In 1899 the first meeting of a new astronomical society was held at Yerkes. Fearful that astrophysics might be overlooked, Hale insisted to Simon Newcomb (who became the first president, with Charles Young and Hale as vice-presidents) that it should be called the American Astronomical and Astrophysical Society. In 1914, when astrophysics was more generally accepted, the name was changed to the American Astronomical Society.
In 1896 Hale persuaded his father to provide the disk for a sixty-inch reflecting telescope with which stellar spectra could be photographed “on so large a scale as to permit the study of their chemical composition, the temperature and pressure in their atmospheres, and their motions with that high degree of precision”5 which could then be reached only in the case of the sun. William Hale offered this disk to the University of Chicago on condition that funds be found to mount it. This condition was never fulfilled.
In 1902 the Carnegie Institution of Washington was founded by Andrew Carnegie to “encourage investigation, research and discovery in the broadest and most liberal manner, and the application of knowledge to the improvement of mankind.” On 20 December 1904, after overcoming many difficulties and gambling $30,000 on a successful outcome, Hale received $150,000 to found the Mt. Wilson Solar Observatory, under Carnegie auspices, on a peak above Pasadena. The story of the pioneer days on that mountain, when the astronomers lived under primitive conditions and all supplies had to be transported by burro and mule, has been dramatically told by Hale’s colleague and successor as director of the Mt. Wilson Observatory, Walter Adams. He describes Hale’s insight, courage, and enthusiasm and his unexpected reaction to the novel conditions:
Apparently combined with a deep-seated love of nature in every form was the spirit of the pioneer, whose greatest joy is the adventure of starting with little and taking an active personal part in every phase of creation and growth. To both of these inborn characteristics of Hale, Mount Wilson in 1904 offered a rich field and scope for their full employment.6
The first instrument was the Snow telescope, brought on a temporary expeditionary basis from the Yerkes Observatory even before Mt. Wilson’s founding. With this instrument, essentially a solar telescope fed by a coelostat, devised to accommodate larger, more powerful spectrographs, than could be attached to the forty-inch, the first photograph of a sunspot spectrum was taken in 1905. By that time a small laboratory had been built on the mountain. Here spectroscopic results, obtained with the Snow telescope and other instruments, could be analyzed and compared with laboratory results obtained under controlled conditions. And here the significant observation was made by Hale, Adams, and Henry Gale that those lines which are strengthened in sunspots are exactly the lines that are strongest in low-temperature sources, such as the electric arc and furnace. Thus it became evident that sunspots are cooler than other regions of the solar disk, as Hale had long suspected.
In 1908, in the hope of overcoming the temperature problems that had plagued the low-lying Snow telescope, Hale designed and built a sixty-foot tower telescope with a thirty-foot spectrograph in an underground pit. With photographic plates sensitive to red light (developed by R. J. Wallace at Yerkes) he detected vortices in the hydrogen flocculi in the vicinity of sunspots. This observation led to the hypothesis that the widening of lines in sunspot spectra might be due to the presence of intense magnetic fields in sunspots. With the new sixty-foot tower telescope—which, with customary vision, he had planned in anticipation of the need—Hale was soon able to prove his hypothesis. Young and W. M. Mitchell at Princeton had observed double lines in sunspot spectra visually but had ascribed the effect to “reversal.” Now Hale became convinced that the splitting was due to the Zeeman effect. In 1908 he compared his observations of the doubling of lines in sunspots with a similar doubling obtained with a powerful electromagnet in his Pasadena laboratory and showed for the first time the presence of magnetic fields in sunspots. This, his greatest discovery, was also the first discovery of an extraterrestrial magnetic field. The mathematical physicist R. S. Woodward, president of the Carnegie Institution of Washington, wrote: “This is surely the greatest advance that has been made since Galileo’s discovery of those blemishes on the sun.”7
This discovery was followed by Hale’s recognition of the reversal of sunspot polarities with the sunspot cycle, and this in turn led to the formulation of his fundamental polarity law. In this law he stated the twenty-two- to twenty-three-year interval between successive appearances in high latitudes of spots of the same magnetic polarity.
Meanwhile, Hale had turned to the puzzling question of whether the sun itself is a magnet. In 1889 F. H. Bigelow, observing the corona during eclipse, had suggested that the sun might possess a magnetic field. In 1912 the 150-foot tower telescope with a seventy-five-foot vertical spectrograph, designed to obtain the spectral resolution needed to measure the sun’s general field, was completed. Preliminary observations with this instrument indicated that the sun has a dipole field with a strength of about twenty gauss. In the 1930’s observations by Hale, Theodore Dunham, Jr., John Strong, Joel Stebbins, and A. E. Whitford indicated a field of approximately four gauss. But these results were still inconclusive.
It was not until 1952 that H. D. and H. W. Babcock, using an electrooptic light modulator, developed the solar magnetograph in the Hale Solar Laboratory in Pasadena and obtained the first reliable method for measuring magnetic fields on the sun’s surface. They found evidence of the existence of a polar field of the sun with a strength of about two gauss and a polarity opposite to that of the earth. At the next solar maximum the polarity was reversed. “It is clear to us now,” Robert Howard said in 1969, “that magnetic fields hold the key to the phenomenon called solar activity, and it is a tribute to the genius of Hale that he recognized, at such an early stage the great importance of these elusive magnetic fields.”8
In 1908, twelve years after his father had given Hale the disk, the sixty-inch reflecting telescope, then the largest in the world, was set up on Mt. Wilson. At last, with its great light-gathering power, steps could be taken in the photographing of stellar spectra on a scale that might eventually approach the great dispersion available for the study of the solar spectrum. The way was prepared for an understanding of stellar evolution that would be realized only when knowledge of atomic processes gained in earthly laboratories could be applied to the interpretation of the nature of stars and nebulae and when, in turn, knowledge derived from studies of those “enormous crucibles,” the stars, could be applied on the earth.
Even before this, in 1906, with the success of the sixty-inch still uncertain, Hale had described the possibilities of a 100-inch telescope to a Los Angeles businessman, John D. Hooker. It would, he said, give two and a half times as much light as the sixty-inch, seven times as much as any other telescope then in use for stellar astronomy. It would “enormously surpass all existing instruments in the photography of stars and nebulae, giving new information on their chemical composition and the temperature and pressure in their atmospheres.”9 Through life talent for convincing wealthy men of the urgent need for supporting his dreams he persuaded Hooker to provide for a 100-inch disk. The first observations with this telescope, built with Carnegie funds, were made in November 1917. Soon afterward, carrying on research begun with the sixty-inch, it was contributing to knowledge of the size and nature of the universe, solving problems that had previously seemed insoluble. With it, using Albert Michelson’s interferometer, Francis Pease and J. A. Anderson measured the diameter of the giant red star Betelgeuse—an extremely difficult feat—and found it to be an astounding 300 million miles.
In 1920 the famous Heber Curtis-Harlow Shapley debate, “The Scale of the Universe,” took place at the National Academy of Sciences. Curtis had made his observations with the thirty-six-inch Crossley at Lick; Shapley had made his with the sixty-inch at Mt. Wilson. Their observations led them to quite different conclusions. No definite answer could be given until the end of 1923, when Edwin Hubble, working with the 100-inch, identified a Cepheid variable in a spiral nebula and found the key to its distance. His results, as Allan Sandage points out, “proved beyond question that nebulae were external galaxies of dimensions comparable to our own. It opened the last frontier of astronomy, and gave, for the first time, the correct conceptual value of the universe. Galaxies are the units of matter that define the granular structure of the universe.”10 Without the 100-inch telescope this, like many other breakthroughs in our knowledge of the universe, would have been impossible.
For his building of large telescopes Hale has been called the “master builder,” but he was also a builder of institutions. All his life he was interested first and foremost in research, yet early in life he realized that to achieve his goals in astronomy, in science, and in the humanities, he must divert some of his energies to the less appealing tasks of organization. In 1902 he was elected to the National Academy of Sciences. From the beginning he felt that this, the leading scientific academy in the United States, should accomplish much more than it was doing if it was ever to occupy its proper position in the scientific world and “acquire a commanding influence of a favorable character, favorable alike to the development of research and the public appreciation of science.”11 To change its hoary ways and increase its influence, Hale proposed an increase in the membership, with an emphasis on younger, more forward-looking scientists. To broaden its outlook, he urged that the membership be expanded to include such branches as engineering and archaeology. To enhance its international position, he urged programs of cooperation, especially in astronomy.
All his life Hale was an internationalist. In 1893 he helped to arrange an international astronomical congress in connection with the Columbian Exposition. In 1904 the Louisiana Purchase Exposition was to be held in St. Louis, and he proposed that a committee be formed to organize the International Union for Cooperation in Solar Research under Academy auspices. To the first meeting, held in St. Louis, came a number of European astronomers, including Henri Poincaré, who was made vice-president (Hale became president). The Union was formally organized at Oxford in 1905. At a large meeting on Mt. Wilson in 1910 its aims were expanded to include all branches of astronomy.
Soon after this, as World War I broke out in 1914, the outlook for international exchange dimmed. At the spring meeting of the Academy in 1915 Hale presented a resolution offering its services to President Woodrow Wilson in case of a diplomatic break with Germany. Out of this move the National Research Council was born in 1916, and Hale became its first chairman. The Council was, as the executive order stated, organized for the purpose “of stimulating research in mathematical, physical and biological sciences, and in the application of these sciences to engineering, agriculture, medicine and other useful arts, with the object of increasing knowledge, of strengthening the national defense, and of contributing in other ways to the public welfare.”12 Through it Hale saw the chance to develop cooperative research on an unprecedented scale, first for war and later as an instrument for peace. Representatives of scientific and technical agencies, medical and engineering bodies soon joined with the government’s scientific bureaus and with the departments of the Army and Navy to solve the scientific problems posed by the war.
In 1918 Hale, foreseeing the possibilities of cooperation not only nationally but internationally, proposed the formation of the International Research Council, to which, as long as the war lasted, only the Allies would be admitted; later, all who wished could join. This Council would replace the moribund International Association of Academies. A preliminary meeting held at the Royal Society in London was followed by an organizational meeting at Paris in November 1918. The Council was formally inaugurated at Brussels in July 1919, at which time the International Astronomical Union and other unions were established under the Council. The Astronomical Union, evolved out of the earlier Solar Union, combined such international groups as the Carte du Ciel and the International Union for Determination of Time and Latitude. By 1931 forty countries had joined the Council, and eight unions had been established. In 1931 it was renamed the International Council of Scientific Unions, and in 1932 Hale became its president.
After the war Hale returned to his plans for the Academy itself. The most compelling of these was his dream for a permanent scientific headquarters in Washington and its official center in both a national and an international sense. Such a center, he had long felt, was fundamental to the Academy’s future growth. In 1919 the Carnegie Corporation agreed to give $5,000,000 to the Academy and National Research Council, with a little over a quarter of it to be used for a building in Washington. This impressive building, designed by Bertram Goodhue, was dedicated in 1924. It stands today on Constitution Avenue across from the Lincoln Memorial.
One of the most significant programs in the development of the scientific life of the United States had been initiated on a limited scale during the war. In 1919 this program, in which Hale played a leading role, was expanded when the Rockefeller Foundation agreed to support the National Research Fellowships. Another scheme for which he had equally high hopes was the National Research Fund, launched in the early 1920’s as a means of persuading industry to support basic research. Large sums were promised but the program failed, largely as a result of the depression in the 1930’s as well as of the lack of vision of many industrial leaders. Nevertheless, all these developments, as well as others within the Academy itself (such as the publication of the Proceedings which Hale initiated in 1915), enhanced its position and increased its usefulness, so that it was no longer just the mutual admiration society that it had been in large part when Hale became a member in 1902.
The Mt. Wilson Observatory was founded in 1904. In 1906 Hale became a trustee of Throop Polytechnic Institute, a Pasadena school with meager resources where a range of courses was taught in an elementary school, a manual training division, an art school, and to a small number of college students. He proposed that its character be changed entirely so that it could become a scientific and technological institution of the first rank—like M.I.T. but broader in outlook. He wrote: “Fundamental science had been unduly subordinated to engineering in all American schools of technology and I therefore emphasized the importance of developing it on the highest plane.” 13 To achieve this goal it was necessary to find the ablest scientists and teachers available and to persuade them to share his faith in the future of this unknown institute. It was also necessary to find the money to support it and raise its standards, as the 500-member student body was radically reduced to a small, select group of thirty students of college caliber.
It was not an easy task. Yet out of these small beginnings the California Institute of Technology, as Throop is known today, evolved. Hale’s plan for Throop was part of a larger dream for Pasadena as a center for scientific research, in which the new Throop would collaborate with Mt. Wilson in research on fundamental physical problems. It was part of a broader dream for Pasadena as a cultural center. In 1906 Hale learned from the transportation magnate Henry Huntington of his plan to give his collection of paintings and rare books to Los Angeles County. He urged that Huntington instead consider the possibilities of a center in the humanities to which scholars from the world over might come to do research. In 1919 Hale was made a trustee of what was to become the Henry E. Huntington Library and Art Gallery. Shortly before his death in 1927 Huntington provided the endowment for such a center as Hale had first proposed and had continued to urge with detailed plans over many years. For these contributions and for his work on a wide-ranging city plan for Pasadena, Hale received the city’s highest award, the Noble Medal.
In 1923, as he continued to be plagued by ill health, Hale gave up the directorship of Mt. Wilson and built the Hale Solar Laboratory in Pasadena, where he could carry on his solar research. Here he invented and built the first spectrohelioscope, a special type of spectroscope, with an oscillating slit, for the visual study of solar phenomena. He also continued work on the sun’s magnetic field with a spectroheliograph there.
Despite his “retirement” Hale launched the last great astronomical project of his career. As soon as the 100-inch had proved successful, he had begun thinking of a still larger telescope. In 1928 he wrote to Wickliffe Rose of the International Education Board of the Rockefeller Foundation. He emphasized once more the progress that had been attained through combining the spectroscope, telescope, and photographic plate with supplementary instruments and pointed out the importance of a 200-inch telescope to future advances in physics and astronomy. In a familiar vein he wrote: “In fact, the range of celestial temperatures, densities, masses and states of matter so enormously transcends that of the physical laboratory that many of the most fundamental advances in physics depend upon the utilization of these conditions.”14
Forty years had passed since Hale first urged on a skeptical astronomical world the concept of an observatory as a physical laboratory. By 1928 this concept was no longer questioned. The International Education Board of the Rockefeller Foundation donated $6,000,000 to the California Institute of Technology for a 200-inch telescope, on condition that a cooperative plan be developed with the Mt. Wilson Observatory and its owner, the Carnegie Institution of Washington. This led to the formation of the Mt. Wilson and Palomar Observatories after the 200-inch instrument was set up on Palomar Mountain in southern California. Hale died before the telescope was finished. Since World War II intervened, ten years passed before the observatory was dedicated in 1948 and the Hale telescope was named after the man “whose vision and leadership made it a reality.”15 In December 1969 the Mt. Wilson and Palomar Observatories were renamed the Hale Observatories.
“It is perhaps symbolic of this man of great gifts and wide horizons,” Walter Adams wrote, “that he who had devoted his life to the nearest star should find his last deepest interest in an instrument destined to meet the remotest objects of our physical universe.”16
1. Hale to E. C. Hale, 29 Apr. 1909, Hale Collection, Pasadena, Calif.
2. Hale to H. H. Turner, 17 Jan. 1903. Carbon copy in the Yerkes Observatory Records, Williams Bay, Wis. The Turner-Hale correspondence at Oxford was apparently destroyed.
3. Robert Howard, “Research an Solar Magnetic Fields from Hale to the Present,” talk given at Hale Centennial Symposium at meetings of the American Association for the Advancement of Science at Dallas. Texas, Dec. 1968. The entire symposium will be published as The Legacy of George Ellery Hale by M.I.T. Press.
4. Hale to James Hall, 12 July 1895; copy of the letter is in the Yerkes Observatory Records, Williams, Bay, Wis.
5. Letter to W. R. Harper, 9 May 1889, University of Chicago archives.
6. Walter Adams, “Early Days at Mount Wilson,” in Publications of the Astronomical Society of the Pacific, 59 (1947), 213.
7. R.S. Woodward to G.E. Hale, 29 July 1908, Hale Collection, Pasadena Calif.
8. Howard, op. cit.
9. Letter to John. D. Hooker, 27 July 1906, Hale Collection, Pasadena, Calif.
10. Allan Sandage, Hubble Atlas of Galaxies (Washington, D.C., 1961), “Galaxies,” p.4.
11. Hale to C. D. Walcott, 25 Jan. 1908. The original letter is in the National Academy of Sciences Archives.
12. Executive order signed by Woodrow Wilson, 11 May 1918.
13. “Autobiographical Notes” (unpublished), Hale Collection, Pasadena, Calif.
14. Letter to Wickliffe Rose, 14 Feb. 1928, Hale Collection, Pasadena, Calif.
15. On the bronze plaque on the Hale bust in the foyer of the two-hundred-inch dome at Palomar these words are inscribed, “The two hundred inch telescope named in honor of George Ellery Hale 1868–1938 whose vision and leadership made it a reality.”
16. Astrophysical Journal, 87 (1938), 388.
I. Original Works. Hale’s bibliography in Adams’ biographical memoir for the National Academy of Sciences (see below) includes some 450 articles and books, in addition to his annual reports as director of Mt. Wilson. Among them are “Photography of the Solar Prominences,” in Technology Quarterly, 3 (1890), 310–316, a condensed version of his thesis (which, in its original form, is in the M.I.T. archives); “The Astrophysical Journal,” in Astronomy and Astro-Physics, 11 (1892), 17–22; “The Yerkes Observatory of the University of Chicago,” ibid., 741; “Ihe Spectroheliograph,” ibid.,12 (1893), 241–257; “The Congress of Mathematics, Astronomy and Astrophysics—Section of Astronomy and Astrophysics,” ibid., 746–749; “On Some Attempts to Photograph the Solar Corona Without an Eclipse,” ibid.,13 (1894), 662–687; “The Astrophysical Journal,” in Astrophysical Journal, 1 (1895), 80–84; “The Aim of the Yerkes Observatory,” ibid.,6 (1897), 310–321; and “The Dedication of the Yerkes Observatory.” ibid., 353–362.
In the first two decades of the twentieth century Hale wrote “The Spectra of Stars of Secchi’s Fourth Type,” in Decennial Publications, University of Chicago, 1st ser., VIII (Chicago, 1903), 251–385, written with F. Ellerman and J. A. Parkhurst; “The Rumford Spectroheliograph of the Yerkes Observatory,” in Publications of the Yerkes observatory of the University of Chicago, 3 , pt 1 (1903) 1–26, written with F. Ellerman; “General Plan for Furthering Special Researches in Astronomy,” in Carnegie Institution Yearbook, I (1902), 94–104: “Cooperation in Solar Research” in Astrophysical Journal,20 (1904), 306–312; “The Solar Observatory of the Carnegie Institution of Washington,” ibid.,21 (1905), 151–172; “The Spectroscopic Laboratory of the Solar Observatory,” ibid.,24 (1906), 61–68; “A 100-Inch Mirror for the Solar Observatory,” ibid. 214–218; “A Vertical Coelostat Telescope,” ibid.,25 (1907), 68–74; “A Plea for the Imaginative Element in a Technical Education,” in The Technology Review, 9 , no. 4 (1907), 467–481; The Study of Stellar Evolution..., Decennial Publications of the University of Chicago, 2nd ser., X (Chicago, 1908); “Solar Vortices,” in Astrophysical Journal, 28 (1908), 100–116; “Solar Vortices and Magnetic Fields,” in Proceedings of the Royal Institution, 19 (1909), 615–630; “Preliminary Results of an Attempt to Detect the Magnetic Field of the Sun,” in Astrophysical Journal, 38 (1913), 27–98; “National Academies and the Progress of Research, I. Work of European Academies,” in Science, n.s. 38 (1913), 681–698; “II. The First Half-Century of the National Academy of Sciences,” ibid.39 (1914), 189–200; “III. The Future of the National Academy of Science,” ibid.,40 (1914), 907–919, and 41 (1915), 12–23; “IV. The Proceedings of the National Academy as a Medium of Publication,” ibid., 815–817; Ten Years’ Work of a Mountain Observatory, Carnegie Institution of Washington Publication no. 235 (Washington, D.C., 1915); and “The National Value of Scientific Research,” in Technology Review, 18 (1916), 801–817.
In the 1920’s Hale produced “The International Organization of Scientific Research,” in international Conciliation, no. 154 (1920), 431–441; “Introduction; Science and War” (ch. 1), “War Services of the National Research Council” (ch. 2), “The Possibilities of Cooperation in Research” (ch. 22), and “The International Organization of Research” (ch. 23), in Robert M. Yerkes, The New World of Science (New York, 1920); “Invisible Sun-spots,” in Monthly Notices of the Royal Astronomical Society, 82 (1922), 168–169; “A Joint Investigation of the Constitution of Matter and the Nature of Radiation,” in Science, n.s. 55 (1922), 332–334; “A National Focus of Science and Research,” in Scribner’s Magazine (Nov 1922), 515–531: The New Heavens (New York, 1922); “The Possibilities of Instrumental Development,” in Report of the Board of Regents of the Smithsonian Institution (1923), 187–193; “Sun-spots as Magnets and the Periodic Reversal of Their Polarity,” in Nature, 113 (supp.) (1924), 105–112; The Depths of the Universe (New York, 1924); “Law of the Sunspot Polarity,” in Astrophysical Journal, 62 (1925), 270–300, written with S. B. Nicholson; Beyond the Milky Way (New York, 1926); “The Huntington Library and Art Gallery: The New Plan of Research,” in Scribner’s Magazine, 82 (1927), 31–43; “Science and the Wealth of Nations,” in Harper’s Magazine, 156 (1928), 243–251; “The Possibilities of Large Telescopes,” ibid., 639–646; ’The Spectrohelioscope and Its Work: I. History, Instruments, Adjustments, and Methods of Observation,” in Astrophysical Journal, 70 (1929), 265–311; and “Building the 200-Inch Telescope,” in Harper’s Magazine, 159 (1929), 720–732.
The 1930’s saw publication of “The Spectrohelioscope and Its Work: II. The Motions of the Hydrogen Flocculi Near Sunspots,” in Astrophysical Journal, 71 (1930), 73–101; “III. Solar Eruptions and Their Apparent Terrestrial Effects,” ibid.73 (1931), 379–412; “IV. Methods of Recording Observations,” ibid.,74 (1931), 214–222; Signals from the Stars (New York, 1931); “Solar Research for Amateurs,” in Amateur Telescope Making, 1st ed. Albert G. Ingalls, ed. (New York, 1928), pp.180–214; “The Astrophysical Observatory of the California Institute of Technology,” in Astrophysical Journal, 82 (1935), 111–139; “Address of the President,” International Council of Scientific Unions, Brussels, 1934, in Reports of Proceedings of the International Council of Scientific Unions (1935), 4–10; and Magnetic Observations of Sunspots, 1917–1924, Carnegie Institution of Washington, pub. no. 498, 2 vols. (Washington, D.C., 1938), written with S. B. Nicholson.
The bulk of the Hale MSS—original correspondence, unpublished papers, and other source materials—is divided between the Hale Observatories’ offices in Pasadena and the archives in the Millikan Library at the California Institute of Technology. In addition, Hale’s correspondence with H. M. Goodwin is in the Henry E. Huntington Library and Art Gallery in San Marino. All these collections have been microfilmed. There is also a large amount of correspondence at the Yerkes Observatory in Williams Bay, Wisconsin. This covers his years as director there and also includes correspondence dealing with the founding of the Mt. Wilson Observatory.
II. Secondary Literature. The only complete biography of Hale is Helen Wright, Explorer of the Universe, A Biography of George Ellery Hale (New York, 1966). Biographical articles on George Hale include Giorgio Abetti, “George Ellery Hale.” in Memorie della Societeà astronamica italiana, 11 (1938), 3; Walter S. Adams, “Biographical Memoir of George Ellery Hale,” in Biographical Memoirs. National Academy of Sciences, 21 (1940), 181–241; “George Ellery Hale,” in Astrophysical Journal, 87 (1938), 369–388: and in Publications of the Astro. Soc. Pac.,50 (June 1938); Harold D. Carew, “A Man of Many Worlds, George Ellery Hale,” in Touring Topics (Oct. 1928), 28–30, 48; Theodore Dunham, Jr., “Obituary Notice of George Ellery Hale,” in Monthly Notices of the Royal Astronomical Society (Feb. 1939), 99, 322–328; Philip Fox, “George Ellery Hale,” in Popular Astronomy, 46 (Oct. 1938), 423–430; F. R. Moulton, “0ur Twelve Great Scientists VII,” in Technical World, 22 (Nov. 1914), 342–347, 462–464; H. F. Newall, “Scientific Worthies, XLVII, George Ellery Hale,” in Nature, 82 (1933), 1–5; F. H. Seares, “The Scientist Afield,” in Isis, 30 (May 1939), 241–267; James Stokley, “A Tribute to George Ellery Hale, June 29, 1868-Feb. 21, 1938,” in The Sky, 2 (July 1938), 10–11; “Obituary Notices of Dr. George Ellery Hale, Foreign Member of the Royal Society of London,” in Nature (19 Mar. 1938), 501–503, which includes articles by F. W. Dyson, J. H. Jeans, H. F. Newall, and F. J. M. Stratton; “The Works of George Ellery Hale—A Survey of the Career of a Great Living Scientist” (in three parts), in Telescope, 3 (May-Dec., 1936), 64–71, 95–100, 117–120, 127; and H. H. Turner, “Address on George Ellery Hale Given at the Time of the Award of the Gold Medal of the Royal Astronomical Society,” in Monthly Notices of the Royal Astronomical Society, 64 (1904), 388–401.
Additional works that contribute to a picture of the development of astronomy in particular, of science in general, and of Hale’s role in that development include Charles G. Abbot, Adventures in the World of Science (Washington, D.C., 1958); Giorgio Abetti, “Solar Physics,” in Handbuch der Astrophysik, IV (Berlin, 1929) and VII (Berlin, 1936); The History of Astronomy, Betty B. Abetti, trans. (New York, 1952); and The Sun, J. B.Sidgwick, trans. (New York, 1957); Walter Adams, “Some Reminiscences of the Yerkes Observatory,” in Science, 106 (1947), 196–200; “Early Days at Mount Wilson,” in Publications of the Astronomical Society of the Pacific, 59 (1947), 213–231, 285–304; “The History of the International Astronomical Union,” ibid.,61 (1949), 5–12; “The Founding of the Mount Wilson Observatory,” ibid.,66 (1954), 267–303; and “Early Solar Research at Mount Wilson,” in Arthur Beer, ed., Vistas in Astronomy (London, 1955), pp. 619–623; Solon I. Bailey, The History and Work of the Harvard Observatory (New York, 1931); Robert Ball, The Story of the Sun (London, 1893); W. Valentine Ball, ed., Reminiscences and Letters of Robert Ball (Boston, 1915); Louis Bell, The Telescope (New York, 1922); Charles Breasted, Pioneer to the Past (New York, 1947); Agnes Clerke, A Popular History of Astronomy During the 19th Century (London, 1885); A. Hunter Dupree, Science in the Federal Government (Cambridge, Mass., 1957); Arthur Eddington, “Some Recent Results of Astronomical Research,” in Proceedings of the Royal Institution, 19 (Mar. 1909), 561–576; Simon Flexner and James T. Flexner, William Henry Welch and the Heroic Age of American Medicine (New York, 1941); Raymond Fosdick, Adventures in Giving. The Story of the General Education Board (New York, 1962); George W. Gray, The Advancing Front of Science (New York, 1937); Wallace K. Harrison, “The Building of the National Academy and the National Research Council” in Architecture, 50 , no. 4 (1924), 328–334, with plates 145–152; Edwin P. Hubble, The Realm of the Nebulae (New Haven, 1936); Bernard Jaffe, Outposts of Science (New York, 1935); Gerard P. Kuiper. ed., The Sun (Chicago, 1953), esp. the introduction by Leo Goldberg; S. P. Langley, The New Astronomy (New York, 1884); J. Norman Lockyer, Contributions to Solar Physics (London, 1874); G. R. Miczaika and William M. Sinton, Tools of the Astronomer (New York, 1903); Robert A. Millikan. Autobiography (New York, 1950); Simon Newcomb, Reminiscences of an Astronomer (New York, 1903); H. W. Newton, The Face of the Sun (Harmondsworth, England, 1958); Alfred Noyes, Watchers of the Sky (New York, 1923); A. Pannekoek, A History of Astronomy (New York, 1961); G. Edward Pendray, Men, Mirrors and Stars (New York, 1935); Michael Pupin, From Immigrant to Inventor (New York, 1924); Angelo Secchi, Le Soleil, 2 vols, (Paris, 1875–1877); Harlow Shapley, Source Book in Astronomy, 1900–1950 (Cambridge, Mass., 1956); Allan Sandage, The Hubble Atlas of Galaxies (Washington, D.C., 1961); Otto Struve, “The Story of an Observatory,” in Popular Astronomy, 55 (May 1947), 223–244; Otto Struve and Velta Zebergs, Astronomy of the 20th Century (New York, 1962); Carol Green Wilson, California Yankee (Claremont, Calif., 1946); Helen Wright, Palomar, the World’s Largest Telescope (New York, 1952); Robert M. Yerkes, ed., The New World of Science (New York, 1920); and Charles A. Young, The Sun (New York, 1895).
In addition, M.I.T. Press is to publish a volume on the Hale centennial meeting in Dallas, Texas, The Legacy of George Ellery Hale, Helen Wright, Joan Warnow, and Charles Weiner, eds. It will include materials from the exhibit; photographs, letters, and other original documents; the republication of some of Hale’s classic papers, including the first publication of his M.I.T. thesis on the spectroheliograph; and the symposium with papers presented by Donald Shane, Ira S. Bowen, Robert Howard, and Daniel Kevles.
"Hale, George Ellery." Complete Dictionary of Scientific Biography. . Encyclopedia.com. (October 20, 2016). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/hale-george-ellery
"Hale, George Ellery." Complete Dictionary of Scientific Biography. . Retrieved October 20, 2016 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/hale-george-ellery
George Ellery Hale
George Ellery Hale
The American astronomer George Ellery Hale (1868-1938) designed and built three great observatories, invented the spectroheliograph, and discovered magnetic fields in sunspots.
George Ellery Hale was born on June 29, 1868, in Chicago, Illinois, the eldest surviving son of William Ellery Hale and Mary Scranton Browne. His father, a wealthy elevator manufacturer, instilled in Hale from an early age a love for tools and machinery and a deep interest in public affairs. Armed with a box of tools and small lathe for turning metal, Hale transformed his bedroom into a laboratory and later built with his own hands a workshop in the yard.
Hale's mother, a graduate of the Hartford Female Seminary in Hartford, Connecticut, cultivated his literary side, reading aloud the Iliad and the Odyssey and stocking the shelves of his personal library with books ranging from the unabridged Robinson Crusoe and Don Quixote in translation to Grimm's Fairy Tales and the poetry of Shelley and Keats. In biographical notes written in 1933 Hale spoke fondly of these and other classics that "helped greatly to arouse my imagination and prepare me for scientific research."
Early Interest in Astronomy
Hale attended the Oakland Public School and later the Allen Academy, taking also a shop course at the Chicago Manual Training School. But what mattered most to Hale were the studies he worked on at home. Astronomy headed the list. He first built a small telescope, then a spectroscope. Attached to the telescope, now a 4-inch Clark refractor purchased for him by his father, the homemade instrument allowed Hale to observe the solar spectrum. In 1884 he photographed a spectrum using a small commercial spectrometer. To measure more accurately the wavelengths of the dark Fraunhofer lines in the solar spectrum, Hale added a one-inch plane grating to the single prism spectrometer.
Reading everything he could find on spectra during these years, Hale bought Norman Lockyer's Studies in Spectrum Analysis. Inspired, he began laboratory observations of spectra and compared them with those of the sun's spectrum. Out of that work was born Hale's lifelong interest in the physical properties of the sun and stars. In explaining why classical astronomy with its emphasis on determining the positions, distances, and motions of celestial bodies did not appeal to him even then, Hale later wrote:"I was born an experimentalist, and I was bound to find the way of combining physics and chemistry with astronomy."
His First Observatory
Determined to leave his mark on the young science of astrophysics, Hale entered the Massachusetts Institute of Technology (MIT) in 1886, where he studied chemistry, physics, and mathematics. For astronomy, he turned to Edward C. Pickering, director of the Harvard College Observatory, who took him on as a volunteer assistant. During summer vacations he continued his own solar and stellar research in a specially-equipped spectroscopic laboratory of his own design built for him by his father in 1888 on a lot adjacent to the family home in the Kenwood section of Chicago. This formed the nucleus of the Kenwood Physical Observatory.
At the time the standard method of recording solar prominences consisted of drawings based on visual observation. In his quest to find an adequate method of photographing prominences, Hale invented the spectroheliograph—an instrument for photographing phenomena in the solar atmosphere that would otherwise be invisible. The first tests of his new instrument, made in the winter of 1889-1890 at the Harvard Observatory, demonstrated that the basic principle was right. Then a senior at MIT, he wrote up the work for his thesis and received a B.S. in physics. Hale married Evelina Conklin in June 1890, two days after graduation. Upon their return to Chicago, Hale's father agreed to finance the construction of a 12-inch refractor telescope.
At the Kenwood Observatory, dedicated in 1891, Hale continued his experiments with the spectroheliograph. In examining the spectra of prominences, he observed two bright lines (H and K), which he had determined to be due to calcium, in the ultraviolet region. They proved ideal for photographing prominences, as photographic plates then in use were more sensitive to light in the ultraviolet. Moreover, his photographs of solar spectra showed H and K as bright lines all over the sun. Armed with this information and an improved instrument, Hale photographed these calcium clouds (flocculi) and prominences both at the solar limb and across the disc in 1892 for the first time. The success of this research tool sealed Hale's international reputation as a solar astronomer. Many of his findings appeared in Astronomy and Astrophysics, the forerunner of the Astrophysical Journal, a publication founded by Hale in 1895 and still the leading astronomical journal in the field.
Two More Observatories
In 1892 Hale joined the faculty of the new University of Chicago as associate professor of astrophysics and director of the observatory. An accomplished organizer and money-raiser, Hale persuaded streetcar millionaire C. T. Yerkes to provide the university with the largest refractor telescope in the world. Hailed in 1897 for its revolutionary design, the Yerkes Observatory at Williams Bay, Wisconsin, was, as Hale stated, "in reality a large physical laboratory as well as an astronomical establishment." There, with the aid of F. Ellerman and J. A. Parkhurst, Hale carried out a study on the spectra of low-temperature red stars (Secchi's fourth type). Besides continuing his own research on sunspot spectra, he also studied the distribution of calcium flocculi at different levels in the solar atmosphere and found the dark hydrogen flocculi using a large spectroheliograph of his own design built for the 40-inch telescope.
Hale lived by his own motto, "Make no small plans." He founded the Mount Wilson Observatory in Pasadena, California, in 1904 with funds provided by the Carnegie Institution and served as its director until 1923. In an effort to eliminate mirror distortion and air turbulence, Hale designed and built in 1908 a 60-foot tower telescope with a long vertical spectroheliograph in an underground well. By then he had discovered the low temperature of sunspots, the vortex structure of the dark hydrogen flocculi in the vicinity of sunspots, and the magnetic fields of sunspots. The discovery of hydrogen vortices around sunspots suggested to Hale that the double lines in sunspot spectra, photographed with the 60-foot tower telescope, were not due, as previously believed, to "reversals, " but rather to intense magnetic fields (the Zeeman effect).
In 1908 Hale compared his astronomical work with the similar doubling of lines obtained with large electromagnets in the observatory's physical laboratory and demonstrated conclusively for the first time the existence of sunspot magnetic fields. Working later with the 150-foot tower telescope, Hale attempted to measure the general magnetic field of the sun; he also formulated the law of sunspot polarities and discovered the reversal of sunspot polarities in successive 11-year cycles.
A solar astronomer primarily, Hale also built stellar telescopes:a 60-inch reflector installed at Mount Wilson in 1908, and a 100-inch telescope inaugurated in 1917. In 1928 the International Educational Board of the Rockefeller Foundation agreed to finance Hale's $6 million proposal to build a 200-inch telescope on Mount Palomar (dedicated in 1948, it bears his name).
A Leader in the Science Community
A scientist bursting with educational, architectural, and civic ideas, Hale was elected to the National Academy of Sciences in 1902 and promptly set about to reform it. He created (and served as first chairman) the National Research Council, the operating arm of the academy, in 1916; aided in establishing a fellowship program in 1919; and raised the endowment for the council and the construction in 1924 of a permanent building for the academy in Washington, D.C. Back in Pasadena, he joined the board of trustees of Throop Polytechnic Institute in 1906 and played a major role in transforming it into the California Institute of Technology, a distinguished school of research and teaching in science and engineering. He influenced the creation of the Henry E. Huntington Library and Art Gallery and worked on the master plan for Pasadena's civic center.
Weakened by a series of nervous breakdowns, Hale resigned as director of the observatory in 1923 and built a small solar laboratory in Pasadena, where he continued to do research on the sun. Honors received during his life-time include the Royal Astronomical Society medal in 1904 and the Copley medal of the Royal Society in 1932 and election to the Accademia dei Lincei and the Royal Society of London, as well as membership in many scientific societies in the United States and abroad. He entered Las Encinas sanitarium in Pasadena following a stroke and died there of heart trouble on February 21, 1938.
Novelist Theodore Dreiser wrote Hale into his novel about Charles Yerkes, The Titan (1914). A first-hand account of Hale's work in California appears in Ten Years' Work of a Mountain Observatory (1915). The only full-length biography of Hale is Helen Wright, Explorer of the Universe (1966). Walter A. Adams, who succeeded Hale as director of the Mount Wilson Observatory, leaned heavily on Hale's unpublished autobiographical notes in the biographical introduction he prepared for the NAS Biog. Mem. (1940). Hale published six books and over 450 articles, all of which are chronologically listed in Adams' bibliography. Hale's work in astronomy and in developing scientific institutions is vividly revealed in pictures, documents, and essays in Helen Wright, Joan N. Warnow, and Charles Weiner (editors), The Legacy of George Ellery Hale (1972). Good background material is in Owen Gingerich (editor), Astrophysics and Twentieth-Century Astronomy to 1950:Part A (1984) and in Daniel Kevles, The Physicists (1978).
Osterbrock, Donald E., Pauper & prince:Ritchey, Hale & big American telescopes, Tucson:University of Arizona Press, 1993.
Wright, Helen, Explorer of the universe:a biography of George Ellery Hale, Woodbury, N.Y.:American Institute of Physics, 1994. □
"George Ellery Hale." Encyclopedia of World Biography. . Encyclopedia.com. (October 20, 2016). http://www.encyclopedia.com/history/encyclopedias-almanacs-transcripts-and-maps/george-ellery-hale
"George Ellery Hale." Encyclopedia of World Biography. . Retrieved October 20, 2016 from Encyclopedia.com: http://www.encyclopedia.com/history/encyclopedias-almanacs-transcripts-and-maps/george-ellery-hale
Hale, George Ellery
George Ellery Hale, 1868–1938, American astronomer, b. Chicago, grad. Massachusetts Institute of Technology, 1890. He founded and directed three great observatories (Yerkes, Mt. Wilson, and Palomar), each in its time the greatest in the world, and was active in organizing interdisciplinary scientific societies nationally and internationally. In 1895 he founded the Astrophysical Journal, which remains the leading publication in its field. He had a unique talent for raising funds from private sources in the days before massive governmental support of scientific research. The 200-in. (508-cm) reflector at Palomar Mt. is named the Hale telescope in his honor, and the Mt. Wilson and Palomar observatories were renamed (1969–86) the Hale Observatories. In his own work he pioneered the experimental study of the physical nature of the sun and stars. His observatories were also laboratories employing the latest in photographic and spectrographic techniques. In 1890 he invented the spectroheliograph, which led to the discovery of magnetic fields and vortices in sunspots. Although he studied in Germany with Helmholtz and Planck, served as the first professor of astrophysics at the Univ. of Chicago, and received many prizes and medals from scientific academies around the world, he never completed the requirements for his Ph.D. Besides technical monographs, he wrote popular books, including Depths of the Universe (1924), Beyond the Milky Way (1926), and Signals from the Stars (1931).
"Hale, George Ellery." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (October 20, 2016). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/hale-george-ellery
"Hale, George Ellery." The Columbia Encyclopedia, 6th ed.. . Retrieved October 20, 2016 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/hale-george-ellery
Hale, George Ellery
"Hale, George Ellery." World Encyclopedia. . Encyclopedia.com. (October 20, 2016). http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/hale-george-ellery
"Hale, George Ellery." World Encyclopedia. . Retrieved October 20, 2016 from Encyclopedia.com: http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/hale-george-ellery