Hans Benndorf

Hans Benndorf (born December 13, 1870 in Zurich , † February 11, 1953 in Graz ) was an Austrian physicist .

Life

Hans Benndorf is the son of the archaeologist Otto Benndorf and the grandson of the physiologist Rudolf Wagner . In 1899 he married his cousin Rosa Wagner, daughter of the economist Adolf Wagner . His marriage had four children: Wolfgang , Otto, Nora and Gottfried. Two of his sons, the chemist Otto and the veterinarian Gottfried, died or disappeared during the Second World War .

From 1890 Benndorf studied physics in Vienna , Heidelberg and Berlin with Josef Stefan , Ludwig Boltzmann and Exner. In 1885 he received his doctorate at the University of Vienna and was assistant to Franz-Serafin Exner . In the winter of 1897/98 he carried out measurements of the air-electric field in Tomsk (Siberia), with which he refuted the theory of his teacher Franz-Serafin Exner, according to which air electricity depends on the humidity of the air. With the results of this work he completed his habilitation in 1899. In later years he has always pointed out the fact that his habilitation was possible with a treatise that refutes the theory of his "superior" in order to show the objective atmosphere in which Franz-Serafin Exner was scientific research.

In addition to the main area of ​​work, air electricity , earthquake research was another scientific focus. In 1904 he became associate professor and in 1910 full professor of physics at the University of Graz . In 1904 he was also elected a member of the Leopoldina Scholars' Academy . In 1907 he was awarded the Ignaz Lieben Prize for his work on the propagation of earthquake waves . During World War I he did military service on the Italian front and in the Ministry of War in Vienna. From 1932 to 1934 he was rector of the university. After Alfred Wegener's arrival in Graz in 1924, close scientific and human contact developed between him and Benndorf. In 1927 he was made a full member of the Academy of Sciences in Vienna. In 1936 he was given early retirement in Austro-Fascist Austria.

He had close ties to Victor Franz Hess and Viktor Conrad . Until his death he remained closely connected to his highly revered teacher Franz-Serafin Exner, on whose 100th birthday he wrote an article in a Viennese newspaper about his work under the title "Ideal image of a university teacher". He also had numerous connections to fields of other disciplines: with the astronomer Karl Hillebrand , he determined the length of Graz-Paris, with the hygienist Wilhelm Prausnitz , he constructed an apparatus to demonstrate the distribution of light and shadow when buildings are illuminated by the sun. He advised his friends, the zoologist Karl von Frisch and the coroner Walther Schwarzacher (1892–1958), on numerous physical issues. He was one of the opponents of the Graz spiritualist Maria Silbert and appeared against her several times in lectures and publications.

meaning

In his time, the physicist Hans Benndorf was one of the world's leading scientists in the field of air electricity and earthquake research, with 102 published papers from the Physics Institute of the University of Graz in the years 1910–1938.

Air electricity

A mechanically registering electrometer named after him, which allows a continuous recording of the earth's field with simple means, was used all over the world. His three manual contributions on air electricity (one of them together with VF Hess) were considered the most important reference works for decades.

Earthquake research

Benndorf made important scientific contributions in the early phase of modern seismology. His oldest work in the field of earthquake research dealt with the installation of two pendulum seismographs in the Příbram mine (1903). A seismograph was set up on the earth's surface, a seismograph 1 km below you, both devices registered a remote quake in exactly the same way, while the microseismic movement from the lower-lying device was displayed significantly weaker. His work on the speed of propagation of earthquake waves at various focal distances was of great importance. Emil Wiechert , who explicitly referred to Benndorf in his first work on earthquake waves, introduced the name "Benndorf's sentence" in 1910 for the relationship between the emergence angle of an earthquake beam when it emerges and the speed at the apex.

Earthquake research connected him with Alfred Wegener . Benndorf wrote about him in the obituary: “He was a character of immaculate purity, simple simplicity and rare modesty. He was a man of action who, with an iron will and tenacious energy, committed his life to accomplish something unusual in pursuit of an ideal goal ”.

literature

• Heinrich Mache:  Benndorf, Hans. In: New German Biography (NDB). Volume 2, Duncker & Humblot, Berlin 1955, ISBN 3-428-00183-4 , p. 50 ( digitized version ).
• D. Angetter:  Benndorf, Hans . In: Austrian Biographical Lexicon 1815–1950 . 2nd revised edition (online only).
• Schweidler, E. v .: Hans Benndorf on the occasion of Gerland's 70th birthday contributions 57, 1941.
• Kurt Reichel: Styria Lexicon . Graz 1955.
• JC Poggendorf's biographical-literary concise dictionary (several times).
• Austria 1918–1934 . Vienna 1935.
• Hans Benndorf: In memory of Franz Exner . In: Physikalische Zeitschrift . Volume 28.1927. Hirzel, Leipzig 1927, pp. 397-409, OBV .
• Angelika Székely, University Professor Hans Benndorf, communications from the Natural Science Association for Styria, 83 Graz 1953 .

Web links

• Literature by and about Hans Benndorf in the catalog of the German National Library
• Entry on Hans Benndorf in the Austria Forum  (biography)