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František Nušl, Vice-President of the IAU 1928–1935, and inventor of the circumzenithal telescope

  • Petra Hyklová (a1) and Martin Šolc (a1)


The Czech astronomer František Nušl (1867–1951) was professor of mathematics, practical astronomy and geometrical optics at Prague Charles University. His scientific contribution to astronomy consisted mainly of inventing and constructing of new astronomical and geodetical instruments. Together with his friend Josef Jan Frič, founder of the Ondřejov Observatory, he developed and improved the circumzenithal telescope (1899–1903–1906–1922–1932), a portable instrument with a mercury horizon for determining the geodetic position using the Gauss method of equal altitudes. This instrument won the gold medal at the Exposition Internationale des Arts et Techniques dans la Vie Moderne in Paris in 1937. Nušl, independently of Ernst Öpik, invented the wobbling mirror for determining the velocity of meteors by visual observation, and constructed an unique guiding system for the Ondrejov astrograph etc. The organizational activities of Frantisek Nušl were considerably rich, too: He was one of the founders of the Czech Astronomical Society in 1917, in the years 1922–1948 he served as its president. From 1918 until his retirement in 1937 he was the director of the Ondrejov Observatory, 40 km south of capital city of Prague, lectured astronomy at the Prague university and held many popular lectures including regular courses in radio broadcasting. František Nušl was member of several commisions of international scientific unions; he organized the 3rd General Assembly of IUGG (International Union of Geodesy and Geophysics) in Prague 1927, and in IAU (International Astronomical Union) he was elected as Vice-President in the years 1928–1935. One can conclude that he was the main person who formed the Czech astronomy in the interwar period.



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Chant, C. A., 1932, Journal of the Royal Astronomical Society of Canada, 26, 377
Fowler, F. J. M. (ed.) 1925, Transactions of the IAU Vol. II. Second general assembly held at Cambridge July 14 to July 2, 1925. London: Imperial College Bookstall
Fowler, F. J. M. (ed.) 1922, Transactions of the IAU Vol. I. First general assembly held at Rome, Italy, May 2 to May 10, 1922. London: Imperial College Bookstall
Frič, J. J., & Nušl, F., 1902, Note sur deux appareils sans niveaux pour la determination de l’heure et de la latitude. Paris, Gaulthies-Villars
Frič, J. J., & Nušl, F., 1904, Astronomische Nachrichten 166, 15, 225228
Hyklová 2018, in Science overcoming borders, Dvořáčková, Franc (eds.), in press
Nušl, F. 1922, Říše hvĕzd, 3, 8589
Nušl, F. 1925, Říše hvĕzd, 6, 1017
Oort, J. H. (ed.) 1939, Transactions of the IAU Vol. VI. Sixth General Assembly held at Stockholm August 3 to August 10, 1938. Cambridge: University Press
Sokol, J. M., Grandpa Nušl (in Czech) 2003, Kosmické rozhledy, 1
Stratton, F. J. M. (ed.) 1929, Transactions of the IAU Vol. III. Third general assembly held at Leiden July 5 to July 13, 1928. Cambridge: University Press
Stratton, F. J. M. (ed.) 1933, Transactions of the IAU Vol. IV. Fourth general assembly held at Cambridge, Massachusetts September 2 to September 9, 1932. Cambridge: University Press
Stratton, F. J. M. (ed.) 1936, Transactions of the IAU Vol. V. Fifth general assembly held at Paris July 10 to July 17, 1935. Cambridge: University Press
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