Prof. Frantisek Nusl

Abstract

IN honour of Prof. F. Nusl, director of the National Observatory of Prague and professor in the Charles University, who has entered on his seventieth year, a composite work has been compiled with the title “Prage venovaneDr.FrantiskuNuglovi”. Prof. Null's interest in astronomy is well known; he was vice-president of the International Astronomical Union for the Leyden meeting held in 1928. His circum-zenithal instrument for the determination of time was described before the Czech Academy in Prague (see NATURE, 68, 376; 1903) and also in a number of other papers. Twelve authors have contributed to the volume and their papers embrace a wide range of subjects. Z. Kopal discusses the two-bodies problem where the central body is an oblate spheroid, not homogeneous, and shows that a steady advance of periastron will take place. V. Guth develops a graphical method for determining the heights and paths of meteors, and J. StSpanek has a most interesting paper showing the results of photographing Comet Finsler (1937f) from July 13 until August 15, 1937. It is easy to follow the developments of various parts of the head and tail of the comet by examining these photographs, and also the variations of the different luminous rays. J. Prochazka explains his method for investigating the stability of the Bouty meridional telescope at Paris by means of two auxiliary telescopes provided with micrometers, and has found that the stability of the instrument is excellent. J. Svoboda supplies a detailed account of his experimental method for finding the personal error in observations with the NuSl-Fri8 circum-zenithal instrument. Z. Horák deals with Svoboda's method for determining the radiant of a meteor stream with a minimum of error, and towards the end of his paper shows how very satisfactory results can be obtained by a graphical method. These as well as the other papers, with all of which it is impossible to deal in the limited space, form most interesting reading.