August Herman Pfund (December 28, 1879 – January 4, 1949) was an American
physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe.
Physicists generally are interested in the root or ultimate cau ...
,
spectroscopist, and inventor.
Early life
Pfund was born in
Madison, Wisconsin
Madison is the county seat of Dane County and the capital city of the U.S. state of Wisconsin. As of the 2020 census the population was 269,840, making it the second-largest city in Wisconsin by population, after Milwaukee, and the 80th ...
and attended Wisconsin public schools until his entry into the
University of Wisconsin–Madison
A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United Stat ...
, where he earned a B.S. degree in physics and studied under
Robert W. Wood.
Career
Both Wood and Pfund left Wisconsin for
Johns Hopkins University
Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hemisphere. It consi ...
in 1903. From 1903 to 1905 Pfund was a Carnegie research assistant and continued to work under Wood. In 1906 Pfund earned his Ph.D. in physics and was a Johnston scholar from 1907 to 1909. He remained at Hopkins for the remainder of his career, eventually becoming a full professor and later chair of the physics department. From 1943 to 1944 Pfund served as the president of the
Optical Society of America
Optica (formerly known as The Optical Society (OSA) and before that as the Optical Society of America) is a professional society of individuals and companies with an interest in optics and photonics. It publishes journals and organizes conference ...
.
Within the
hydrogen spectral series Pfund discovered the fifth series, where an electron jumps up from or drops down to the fifth fundamental level. This Series is known as the "
Pfund series
The emission spectrum of atomic hydrogen has been divided into a number of spectral series, with wavelengths given by the Rydberg formula. These observed spectral lines are due to the electron making transitions between two energy levels in an ...
". He also invented the
Pfund telescope, which is a method for achieving a fixed telescope focal point regardless of where the telescope line of sight is positioned, and the
Pfund sky compass, which arose from Pfund's studies of the polarization of scattered light from the sky in 1944, and which greatly helped
transpolar flights by allowing the determination of the Sun's direction in twilight.
[John Howard,]
Presidents of the Late 1940s
, ''Optics and Photonics News'', June 2010. Pfund is also noted for his work into the area of infrared gas analysis.
See also
*
Current and past presidents of the Optical Society of America
*
Medieval sunstone
The sunstone ( is, sólarsteinn) is a type of mineral attested in several 13th–14th-century written sources in Iceland, one of which describes its use to locate the Sun in a completely overcast sky. Sunstones are also mentioned in the inventori ...
References
Further reading
* Dr. John Andraos
''Named Concepts in Chemistry (L-Z)'' York University
York University (french: Université York), also known as YorkU or simply YU, is a public research university in Toronto, Ontario, Canada. It is Canada's fourth-largest university, and it has approximately 55,700 students, 7,000 faculty and sta ...
, 2001
* Pelletier, Paul A. (ed.), Prominent Scientists: An index to collective biographies, 2nd ed., Neal-Schuman Publishing, Inc.: New York, 1985 (citations only)
* Cattell, J.M.; Cattell, J. American Men of Science, 6th ed., The Science Press: New York, 1938
* Journal of the Optical Society of America, 39:4 (April, 1949) 325. Obit.
External links
Articles Published by early OSA Presidents Journal of the Optical Society of America
{{DEFAULTSORT:Pfund, August Herman
1879 births
1949 deaths
American physicists
University of Wisconsin–Madison College of Letters and Science alumni
Spectroscopists