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Ira Sprague Bowen Papers

Identifier: 10007-MS

Scope and Content

The collection is comprised mostly of class notes (primarily physics) made by Bowen between 1916 and 1920 at the University of Chicago. Also included is a small amount of correspondence (primarily 1920-1945); manuscript articles and speeches; and biographical material.


  • 1916-1961



The collection is open for research. Researchers must apply in writing for access.

Publication Rights

Copyright may not have been assigned to the California Institute of Technology Archives. All requests for permission to publish or quote from manuscripts must be submitted in writing to the Caltech Archivist. Permission for publication is given on behalf of the California Institute of Technology Archives as the owner of the physical items and, unless explicitly stated otherwise, is not intended to include or imply permission of the copyright holder, which must also be obtained by the reader.


A distinguished astrophysicist of the twentieth century, Ira Sprague Bowen made fundamental contributions to the analysis of atomic spectra, the physics of gaseous nebulae and practical optics. Born in Seneca Falls, New York, in 1898, he graduated from Oberlin College in 1919 before entering the University of Chicago. There, he studied with Albert Michelson who infused in Bowen a love of optics. He also met Robert A. Millikan, who invited him to the California Institute of Technology in 1921.

By 1926 Bowen had received his doctorate from the institute and was appointed an assistant professor at Caltech. Soon after he made his first outstanding discovery: the identification of the so-called nebulium lines in the spectra of gaseous nebulae. The following decade, Bowen built an innovative device, called an image slicer, which placed the spectra of successive strips across an extended object, side by side upon a photographic plate. This invention enormously increased the efficiency of observations of gaseous nebulae and he received international attention when he provided an explanation for lines appearing in the spectra of planetary nebulae. During World War II he participated in the Caltech ordnance rocket project, developing the use of high-speed cameras in rocket design. Following the Second World War, he continued to research nebulae in collaboration with Rudolf Minkowski and published many significant papers on the subject.

Upon the retirement of Walter Adams, Bowen assumed the directorship of the Mount Wilson Observatory and, in 1948, the combined Mt. Wilson and Palomar venture. Despite his administrative duties, he continued to make significant contributions to optics, even following his retirement in 1964.

Bowen received many honors. He was a Gold Medallist and Halley lecturer of the Royal Astronomical Society. Among the other medals he received were the Ives (Optical Society of America), Draper (National Academy of Sciences), Potts (Franklin Institute), Rumford (American Academy of Arts and Sciences) and Bruce (Astronomical Society of the Pacific). He was a member of the National Academy of Sciences, the Royal Swedish Academy of Sciences and the Indian Academy of Sciences.


2.5 linear feet (5 boxes)

Language of Materials



Ira Sprague Bowen (1898-1973) Astrophysicist; Director, Mt. Wilson Observatory, 1946-1964; Professor of Physics, Caltech 1926-45. Much of his physics research was concerned with studies of spectral lines and spectroscopy; in the 1930s his interests turned more to astronomy and astrophysics and he devised many new instruments and techniques for observational astronomy. Papers include correspondence (ca. 1933-47), notebooks (many from his years at University of Chicago, 1916-21), articles, speeches, and photographs.


The collection is organized into the following three series: Correspondence, Manuscripts, and Biographical.

Finding Aid for the Ira Sprague Bowen Papers, 1916-1961
Processed by Caltech Archives Staff.
Description rules
Describing Archives: A Content Standard
Language of description
Script of description

Repository Details

Part of the California Institute of Technology Archives and Special Collections Repository

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