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Dr. RUDOLF WOLF, the Director of the Observatory at Zurich, died on 1893 December 6, at the age of 77, after a few days' illness. Dr. Wolf was born 1816 July 7, at Fällanden, near Zurich, and first studied astronomy in the Zurich High Schools, and later at the Universities of Vienna and Berlin. He did not devote himself entirely to the pursuit of astronomy until 1847, when he was appointed Director of the Observatory at Berne. In this small observatory he began the researches on Sun-spot phenomena, with which his name will be most intimately associated in future years. These observations he continuously carried on until his death, and his most important conclusions may be briefly summarised. On 1852 July 31, he showed the intimate connection between the periods of Sun-spot activity and of Earth-magnetism. These results were published simultaneously with, but independently of, those of Professor Lamont, of the Munich Observatory, and of Sabine and Gautier. Lamont and Sabine found a period of about 10 or years. Professor Wolf showed that this period might be more accurately represented by 11.11 years, and suggested also a longer period of 55.5 years. He also pointed out that there were considerable deviations from the mean period of 11.11 years, and that the difference in time between two maxima was shortest when their intensities were most marked. He clearly showed the resemblance between Sun-spot curves and those of the variation of light of stars. He collected much evidence connecting the manifestations of auroræ and other luminous phenomena with solar disturbances. Professor Wolf remained at Berne until 1864, when he returned to Zurich as Professor of Astronomy in the Polytechnic, and Director of the Observatory. Dr. Wolf's other contributions to astronomy embrace both pure mathematics and astronomical literature. In 1852 he published the first edition of his Mathematics, Physics, Geodesy, and Astronomy, the sixth edition of which was brought out very shortly before his death. In 1858-1861 he wrote four volumes of the Biographies of Swiss Men of Science. Two volumes of the Handbuch der Mathematik appeared in the years succeeding 1869, followed in 1893 by his Handbuch der Astronomie, ihrer Geschichte und Litteratur; his History of Recent Astronomy was published in 1877. The Astronomische Mittheilungen have continued from 1856 to the present date, and contain descriptions of instruments and scientific relics in the Zurich Observatory, and histories of Swiss mathematicians, physicists and astronomers, as well as important astronomical communications.
Professor Wolf was elected a Foreign Associate of this Society 1864 November 11.
Professor Wolf was elected a Foreign Associate of this Society 1864 November 11.
(Johann) Rudolf Wolf's obituary appeared in Journal of the Royal Astronomical Society 54:4 (1894), 206-207.