orbits of comets and asteroids. Galle was called to become director of the observatory in Breslau in 1851. In 1852 Karl Christian Bruhns was added as second assistant to Encke and in 1854 he became first assistant. In 1855 Wilhelm Foerster received a position as second assistant. From 1857 Giovanni Schiaparelli studied at the institution for two years. When Bruhns transferred to Leipzig in 1860, Foerster became his successor as first assistant. In the same year Foerster, together with his co-worker Otto Lesser, discovered the asteroid (62) Erato. After Encke fell ill in 1863, he stood in as his deputy and in 1865, the year Encke died, he became director of the observatory. The observatory at this time was the most important astronomical research and educational institution in Deutschland. In 1873 Viktor Knorre came as Observator; by 1887 he had discovered the asteroids (158) Koronis, (215) Oenone, (238) Hypatia und (271) Penthesilea. From 1884 until the beginning of the 1890s Karl Friedrich Küstner was also employed as Observator; he discovered in this time the polar motion as a result of his measurement activities. From 1866 to 1900 Arthur Auwers compiled, in Berlin, his Fundamentalkatalog, a comprehensive star catalog containing 170 000 stars. On the north wing of the observatory was the height reference point for Prussia, known in German as Normalnull. The marking was formally presented on the 82nd birthday of Kaiser Wilhelm I. on 22 March 1879. This point was derived from the Amsterdam Ordnance Datum and marked off 37 meters over zero. Wilhelm Foerster led the observatory until the end of his life in 1903. It was his impulse that led to the erection of the Astrophysikalischen Observatoriums Potsdam in 1874 for on the Telegrafenberg in Potsdam. On the Telegrafenberg stood formerly the „Telegraphenstation 4" which given the hill its name. In the same year Foerster founded the Berlin Astronomische Rechen-Institut (as "Rechen-Institut zur Herausgabe des Berliner Astronomischen Jahrbuchs"), on the basis of the ever-growing extent of calculation of astronomical ephemerides, which occupied its own building at ″Lindenstraße 91″, but on the grounds and in association with the observatory. Most of the astronomers now worked in this theoretical section – separate from the practical, observational section. The section was led by Friedrich Tietjen, who had been working at the observatory since 1861. In 1865 he discovered the asteroid (86) Semele. After Tietjens death, Julius Bauschinger was called to