Title: Frederick Hanley Seares Papers,

Date (inclusive): 1909-1945

Creator: Seares, Frederick Hanley

Extent: Number of containers: 21 boxes (ca 6,200 pieces)

Repository: The Huntington Library

Administrative Information:

Language: English.

Placed on permanent deposit in the Huntington Library by the Observatories of the Carnegie Institution of Washington Collection. This was done in 1989 as part of a letter of agreement (dated November 5, 1987) between the Huntington and the Carnegie Observatories. The papers have yet to be officially accessioned. Cataloging of the papers was completed in 1989 prior to their transfer to the Huntington.

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[Identification of item], Frederick Hanley Seares Papers, The Huntington Library, San Marino, California.

Frederick Hanley Seares, staff astronomer at the Mt. Wilson Observatory, was involved in most of the administrative and research activities of the Observatory. Highly regarded for his photometric studies and his editorial work, Seares was a prominent figure in astronomy during the first half of the twentieth century. The papers in this collection begin in 1909, when he arrived at Mt. Wilson, and end in 1945, when he ended his affiliation with the Observatory.

Seares was born on May 17, 1873, on a farm near Cassopolis, in the southwest corner of Michigan. In 1878, his parents, Isaac Newton Seares and the former Ella Ardelia Swartwout, moved the family to Iowa. They moved again in 1887 to Pasadena, California, where Isaac Seares became involved in the real estate and insurance business. Frederick Seares enrolled at the new Pasadena High School where he was one of its first six graduates in 1890. Seares then matriculated at the University of California in Berkeley and studied under Armin Otto Leuschner. Graduating in 1895 with a B. S. degree (with honors), Seares remained at Berkeley as a Fellow and then Instructor. While at Berkeley, Seares met and on May 28, 1896, married Mabel Urmy, a teacher at Miss Head's School for Girls. In 1899, Seares went to Europe to continue his studies, a practice common among young American scientists of this time. He was accompanied by his wife and they spent one year at the University of Berlin and a second year at the Sorbonne in Paris. Seares's only child, Richard Urmy Seares, was born while the couple resided in Paris. They returned to the United States in 1901, and Seares quickly obtained a position as Professor of Astronomy at the University of Missouri and Director of the Laws Observatory in Columbia. For the next eight years, Seares updated the equipment at the Laws Observatory and engaged in a rich program of astronomical research.

The major turning point in Seares's career came in 1909 when George Ellery Hale invited him to join the staff of the Mt. Wilson Observatory. The new 60-inch reflecting telescope had just come into use on Mt. Wilson, greatly expanding the scope of the Observatory's research. With Walter Sydney Adams being promoted to the head of the new Department of Stellar Spectroscopy, Seares replaced Adams as head of the Computing Division. In addition, Seares was given editorial charge of the Observatory's publications as well as telescope time on the 60-inch to pursue research in stellar photometry.

Mt. Wilson's Computing Department consisted almost entirely of women. Most of them were college-educated with training in mathematics and some experience at their college observatories. Their work consisted of tedious measuring of the wavelengths of spectral lines, stellar positions, or stellar brightness (magnitudes). Located exclusively at the Observatory's office building in Pasadena, the computers' work was so involved that they were often given joint authorship in the astronomers' published papers. Occasionally, a promising young male with a Ph.D. in astronomy would be hired as a computer so that he could be available when a staff position would be created. The men might also be a computer in order to have a summer job between school years. As head of the Department, Seares corresponded greatly with potential computers and this material is in eleven folders separated from his general letters. Included in this section are letters of recommendation from various individuals.

From 1904 to 1948, Mt. Wilson Observatory issued its astronomers' published papers as Contributions from the Mount Wilson [Solar] Observatory.Even though these papers were published elsewhere (mostly in the Astrophysical Journal or Publications of the Astronomical Society of the Pacific),Hale felt the necessity of having a separate identity for his observatory's publications. As a consequence, he wanted to have one person take care of editing his staff's papers in order to provide some type of consistency. This became Seares's job, and he was highly praised by his colleagues in his ability to turn their work into polished scientific papers, in some cases practically re-writing them to do so. Seares would then submit the papers to the various journals and then correct the proofs. In addition, in 1927 he became a Collaborating Editor and in 1934, Associate Editor, of the Astrophysical Journal.In his papers, therefore, there is a great deal of correspondence with the other editors of this journal, Edwin Brant Frost, Henry Gordon Gale and Otto Struve. There is also a large amount of correspondence with the staff of the Carnegie Institution of Washington's Division of Publications and Edwin Bidwell Wilson, the editor of the publications of the National Academy of Sciences. Along similar lines, Seares was given the task of building up the Observatory's library. Much of his Miscellaneous correspondence consists of his efforts in obtaining material for the library as well as requests from others for copies of the Observatory's publications. In recognition of his administrative abilities, Adams, Mt. Wilson's second Director, appointed Seares Assistant Director in 1925. Until his retirement in 1940, Seares would be in charge of the observatory whenever Adams was away (which was not that often) and some of his correspondence reflects this position.

While about one-half of Seares's papers deals with administrative matters, the remainder covers his scientific work. At the Laws Observatory, Seares had gained experience in the field of photometry (measuring the brightness of stars and other celestial bodies). Upon his arrival, he became involved in the photometric research planned for the new 60-inch telescope. The central figure in Mt. Wilson's photometric plans was the Dutch astronomer Jacobus Cornelius Kapteyn. Kapteyn was the leading authority in the field of statistical astronomy. In statistical astronomy, the astronomer worked with a selected statistical sample of stars. Since the stars were too numerous to deal with one at a time, an astronomer would concentrate on a manageable number of stars and extrapolate results for all the stars based on his or her sample. In this way, a research program could be completed within an astronomer's lifetime. In 1906, Kapteyn proposed a scheme of selecting 252 "Selected Areas" spread out over regular intervals across the sky. With international cooperation, the stars in these areas could be studied in detail in order to gain knowledge about the entire Milky Way. When the 60-inch telescope entered service in 1909, it was the most powerful telescope in the world at the time. Kapteyn persuaded Hale to devote some of its time to taking photographs of the 139 Selected Areas within its reach. These photographic plates would then be sent to Kapteyn at Groningen where they could be analyzed. Since the 60-inch telescope would reveal stars fainter than any previously measured, Seares studied the telescope's photographic characteristics in order to develop a proper measurement of stellar magnitudes. After comparisons with other standards of stellar brightness measurements, Seares realized that the prevailing methods of measuring stellar magnitudes were not able to provide him with the accuracy and consistency that he demanded. Starting from scratch, Seares undertook the Herculean task of defining the proper methods and standards of in-focus photographic photometry. He was soon able to establish a common ground for his results and the Harvard North Polar Sequence (a list of magnitudes for stars near the North Celestial Pole. These stars were used since they were always visible to any Northern Hemisphere observatory). Seares began measuring the magnitudes of the stars in the Selected Areas with the assistance of other astronomers at Mt. Wilson and Groningen. By meticulously comparing the stars in one Area to those in nearby Areas and in the North Polar Sequence, they accurately measured the positions and magnitudes of 67,941 stars. The entire process took nine years and the results were published in 1930 as the Mount Wilson Catalogue of Photographic Magnitudes in Selected Areas 1-139, by Seares, Kapteyn, and Pieter Johannes van Rhijn (the latter taking over for Kapteyn who died in 1922), assisted by Mary Cross Joyner and Myrtle L. Richmond. The Catalogue set new standards for accuracy and faintness. The technical accomplishments involved were acknowledged as extraordinary. The only one not totally satisfied was Seares himself. As a final effort, he developed a new, more accurate, set of magnitudes for stars in the North Polar Region. With the aid of Joyner and the astronomer Frank Elmore Ross, their work culminated in 1941 with the publication of Magnitudes and Colors of Stars North of +80°.This work replaced the previous standards which had been adopted internationally in 1932. To document these photometric studies, Seares's papers contains a good deal of correspondence with Kapteyn, van Rhijn, Ross, and Edward Charles Pickering. The manuscripts for the two aforementioned publications are also included in the collection.

Seares's early photometric research gained him enormous respect from his colleagues. This resulted in his being elected President of the Commission on Stellar Photometry (Commission #25) of the new International Astronomical Union (IAU) in 1922. Formed in 1919 out of the International Union for Co-operation in Solar Research, the IAU provided a forum for astronomers of all nations and in various specialties to coordinate their research. Seares served as President of his Commission for sixteen years. In that capacity, he was able to organize a comparison of magnitudes of North Polar stars in seven different catalogues (including Harvard, Yerkes, Greenwich, and Potsdam's measurements) which led to the IAU adopting a homogeneous system as an international standard in 1932. It was this standard which was later surpassed by Seares, Ross, and Joyner's 1941 work (see above). Seares's IAU correspondence is contained in ten folders in the collection. Related material can also be found in the correspondence with Bertil Lindblad, Cecilia Helena Payne (-Gaposchkin), and Harlow Shapley.

Although photometry accounted for most of Seares's scientific work he was also involved in other fields of investigation. These include: (1) studying the structure of the Milky Way based on star counts; (2) the importance of star colors; (3) attempts to measure the magnetic field of the sun; (4) determination of the masses of binary stars. The amount of material on these subjects in the collection is sparse when compared to that on photometry, however.

1940 proved to be a significant year in Seares's life. In that year he retired from the staff at Mt. Wilson. To enable him to continue to do research at the Observatory, however, he was appointed a Research Associate for the next five years. Very few items in Seares's papers are from this period, most being from his active period from 1909 to 1940. In 1940 he also became Director of the Astronomical Society of the Pacific (until 1946) and was awarded the Society's Bruce Gold Medal. In giving Seares the award, the Society cited him in the following way:

Dr. Seares's most important contributions to the science of astronomy pertain to the nature, brightness, and distribution of the stars. His investigations in these and allied subjects are fundamental, and in this field he is recognized as an outstanding authority.... His painstaking work in determining fundamental standards over the whole range of observable photographic magnitudes is recognized by photometric observers the world over as an achievement of the highest importance to astronomy. It was also in 1940 that Seares's wife passed away. Two years later, Seares married his long-time colleague at Mt. Wilson, Mary Joyner.

Seares ended his affiliation with Mt. Wilson and the Astrophysical Journal in 1945. He and his wife soon moved to Santa Barbara, California, then later to Honolulu, Hawaii, where Seares died on July 20, 1964. It is ironic that most of Seares's photometric work was soon surpassed by new technical developments. The introduction of photoelectric devices into photometry after World War II made most photographic photometry techniques obsolete. This is perhaps the major reason why Seares is not thought of today as an important figure in astronomy's history. It would be wrong, however, to underestimate his contributions to the astronomy of his period merely because his techniques are not generally practiced today.