Overview of the Collection
Scope and Content
Overview of the Collection
Title: Frederick Hanley Seares Papers
Dates (inclusive): 1909-1945
Bulk dates: 1909-1940
Collection Number: mssSeares papers
Seares, Frederick Hanley, 1873-1964.
Approximately 10,000 items in 21 boxes
The Huntington Library, Art Collections, and Botanical Gardens.
1151 Oxford Road
San Marino, California 91108
Phone: (626) 405-2129
Abstract: This collection contains the papers of Frederick Hanley Seares (1873-1964), a staff astronomer at the Mount Wilson Observatory
known for his photometric studies and his editorial work.
Open to qualified researchers by prior application through the Reader Services Department. For more information, contact Reader
The Huntington Library does not require that researchers request permission to quote from or publish images of this material,
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The responsibility for identifying the copyright holder, if there is one, and obtaining necessary permissions rests with the
[Identification of item]. Frederick Hanley Seares Papers, The Huntington Library, San Marino, California.
Deposit, Observatories of the Carnegie Institution of Washington Collection, 1988.
Approximately fifty additional separate collections form the Mount Wilson Papers of the Observatories of the Carnegie Institution
of Washington and are available for research in the Huntington Library.
Cataloging of the papers was completed in 1989 prior to their transfer to the Huntington.
Frederick Hanley Seares (1873-1964), 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
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
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,
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.
Scope and Content
The collection consists of the correspondence files and manuscripts, notes, and notebooks of American astronomer Frederick
Hanley Seares. While roughly one half of the papers deal with administrative matters of the Mount Wilson Observatory, the
remainder cover his scientific work. There are also some manuscripts, notes and notebooks (Boxes 19-21) related to Seares's
Correspondents represented in the collection include: Walter S. Adams, Robert Grant Aitken, Edward Emerson Barnard, William
Wallace Campbell, Gustav Fock, Edwin Brant Frost, Henry Gordon Gale, Cecilia Helena Payne Gaposchkin, Walter M. Gilbert, George
Ellery Hale, Ejnar Hertzprung, Edwin Powell Hubble, J.C. Kapteyn, Armin Otto Leuschner, C.E. Kenneth Mees, John C. Merriam,
Charlotte Emma Moore, John Adelbert Parkhurst, Francis Gladheim Pease, Edward C. Pickering, P.J. van Rhijn, Frank E. Ross,
Henry Norris Russell, Harlow Shapley, Joel Stebbins, Otto Struve, and Edwin Bidwell Wilson.
Corporate and organizational organizations represented in the collection include: American Association for the Advancement
of Science, Astronomical Society of the Pacific, Carnegie Institution of Washington, William H. Guild & Company, International
Astronomical Union, International Union for Co-operation in Solar Research, Mount Wilson Observatory and the University of
This collection is arranged in the following series:
1. Correspondence, 1909-1945. (Boxes 1-18)
This series contains both incoming and carbons of outgoing correspondence. They are
arranged in alphabetical order by correspondent.
2. Manuscripts, notes, and notebooks. (Boxes 19-21)
The manuscripts are arranged in alphabetical order by the first keyword in the title.
Seares's papers have been arranged, with only minor changes, according to the manner in
which they had been found in the attic of Mt. Wilson.
Seares, Frederick Hanley, 1873-1964 -- Archives.
Carnegie Institution of Washington.
Mount Wilson Observatory -- History -- Sources.
Astronomers -- California, Southern -- Archives.
Astronomers -- Correspondence.
Astronomy -- Research.
Letters (correspondence) -- 20th century.
Manuscripts -- 20th century.
Notebooks -- 20th century.
Notes -- 20th century.
Adams, Walter S. (Walter Sydney), 1876-1956.
Aitken, Robert Grant, 1864-1951.
Barnard, Edward Emerson, 1857-1923.
Campbell, William Wallace, 1862-1938.
Fock, Gustav, 1893-1974.
Frost, Edwin Brant, 1866-1935.
Gale, Henry Gordon, 1874-1942.
Payne-Gaposchkin, Cecilia, 1900-1979.
Gilbert, Walter M.
Hale, George Ellery, 1868-1938.
Hertzsprung, Ejnar, 1873-1967.
Hubble, Edwin, 1889-1953.
Kapteyn, J. C. (Jacobus Cornelius), 1851-1922.
Leuschner, Armin Otto, 1868-1953.
Mees, C. E. Kenneth (Charles Edward Kenneth), 1882-1960.
Merriam, John C. (John Campbell), 1869-1945.
Moore, Charlotte Emma, 1898-1990.
Parkhurst, John Adelbert, 1861-1925.
Pease, F. G. (Francis Gladheim), 1881-
Pickering, Edward C. (Edward Charles), 1846-1919.
Rhijn, P. J. van (Pieter Johannes), 1886-
Ross, Frank E. (Frank Elmore), 1874-1960.
Russell, Henry Norris, 1877-1957.
Shapley, Harlow, 1885-1972.
Stebbins, Joel, 1878-1966.
Struve, Otto, 1897-1963.
Wilson, Edwin Bidwell, 1879-1964.
American Association for the Advancement of Science.
Astronomical Society of the Pacific.
Carnegie Institution of Washington.
William H. Guild & Company.
International Astronomical Union.
International Union for Co-operation in Solar Research.
University of Chicago. Press.