Figure 30.1: Above: Christopher Hansteen (1784–1873); Below: The Observatory in Christiania (Above: Portrait from his Reise-beretninger. Christiania: Chr. Tønsbergs forlag 1859. Below: Draft by Heinrich Chris- tian Grosch sent to Schumacher in 1828. From Elisabeth Seip (ed.): Chr. H. Grosch. Arkitekten som ga form til det nye Norge. Oslo: Pax forlag as (2001) 2007, p. 135.) 260 30. Christopher Hansteen and the Observatory in Christiania Vidar Enebakk (Oslo, Norway) and Bjørn Ragnvald Pettersen (Ås, Norway) 30.1 Introduction tion of a model of the earth consisting of two magnetic axes and four magnetic poles. Based on this theory, The early nineteenth century was a turbulent period in Hansteen carried out an expedition to Siberia between Norway due to Napoleonic wars. As a result Denmark 1828 and 1830 in search of the second magnetic north had to turn over Norway to Sweden at the peace treaty pole.2 Despite a negative result, Hansteen’s expedition in Kiel on 14 January 1814, and the Constitution of was of great importance to the new nation. Upon his Norway was introduced on 17 May 1814. In the preced- return in 1830 Hansteen’s efforts were rewarded by the ing years, however, an important feature of the growing government, who approved the construction of a new nationalism was the insistence on a separate university astronomical observatory. It was completed in 1833. in Norway. Thus, the Royal Frederik’s University in Hansteen and the observatory served many social, Christiania (today: Oslo) was officially created through cultural and political purposes within the new national a royal decree by Frederik VI, the king of Denmark state. Along with his duties at the university, Hansteen and Norway, on 2 September 1811. In the first decades also gave lectures at the military academy in mathe- the most important Norwegian scientist was Christopher matics, mechanics, geodesy, and astronomy. He further Hansteen (1784–1873), professor of applied mathemat- attracted general attention as the editor of the official ics and Director of the observatory in Christiania. Not Almanac of Norway from 1815 to 1862. In 1817 he took only did Hansteen put Norway “on the map” through his up a part time position as Director of Norges geografiske many international networks within geomagnetism, as- Opmaaling (Geographical Survey of Norway) which he tronomy and geodesy, he also located Norway in relation held until 1872. In 1823 he began publishing Magazin to astronomical time and geographical space. In this for Naturvidenskaberne (Journal of Natural Sciences) paper we will primarily focus on the construction and with two other professors, thus creating a forum for instrumentation of the observatory in Christiania during science news and extended papers on specialized topics. a period of gradual political separation from Copen- The following year he was co-founder of a scientific so- hagen. At the same time we will emphasize the close ciety called Den physiographiske Forening, which served collaboration between Christopher Hansteen in Chris- as a precursor to the Academy of Science in Christiania tiania and Heinrich Christian Schumacher (1780–1850) established in 1857. Finally, Hansteen was appointed in Altona at the south border of the Danish-Norwegian to the national commission for weight and measures kingdom, thus highlighting the close relationship be- in 1818. He designed the new Norwegian system of tween Hansteen and the Hamburg area at the beginning standards in 1824, and he served on this body until of the nineteenth century. 1872. Most of his functions, however, were related to his work at the university observatory in Christiania where Hansteen served as Director from 1815 to 1861.3 30.2 Hansteen in Christiania Christopher Hansteen initially studied jurisprudence at 30.3 Schumacher in Altona the University of Copenhagen, but his interests were soon drawn towards geomagnetism and astronomy. In Christopher Hansteen’s most important contact and 1811 he won a gold medal for a treatise on geomag- collaborator on the continent was Heinrich Christian netism which was later expanded and published as Un- Schumacher. He was Director of the new observatory tersuchungen über den Magnetismus der Erde (1819).1 in Altona outside Hamburg from 1823 and is perhaps Meanwhile, on 1 June 1814, he was formally appointed best known as the founder of the journal Astronomis- Lecturer of applied mathematics at the newly estab- che Nachrichten which he edited from 1821 to 1850. lished University in Christiania, and on 4 March 1816 It was the leading international journal in the field of he was promoted to professor. Hansteen is perhaps best astronomy in this period and it made the observatory known for his work on geomagnetism and his elabora- in Altona “the centre of international relations between 261 astronomers.”4 For instance, Hansteen published regu- was close to king Frederik, died early and the mother, larly in Astronomische Nachrichten and he had a total Sophia Hedevig Rebecca Schumacher, moved to Altona. of ten contributions to the first full volume which was Here the young Heinrich Christian attended school from published in 1823. 1794 to 1799 under Rector Jakob Struve, father of the astronomer Friedrich Georg Wilhelm Struve who was born in Altona and later, in 1839, became Director of the new observatory in Pulkovo near St. Petersburg. From April 1799 Schumacher studied jurisprudence in Kiel and two years later in Göttingen. Here he met Carl Friederich Gauß who in 1807 had become Director of the new observatory in Göttingen, and Schumacher studied with him during the winter of 1808–1809.5 In 1810 Schumacher was appointed extraordinary professor of astronomy in Copenhagen. Still, as he did not get along well with Thomas Bugge, the ordinary professor of astronomy and director of the Round Tower observa- tory, he resided in Hamburg in this period and began a three-year observing programme of circumpolar stars with Repsold’s meridian circle. By 1811–1812 he ac- quired a flat at Herrengraben 12 near the observatory at Millerntor so he could collaborate closely with Repsold. 1813 Schumacher temporarily accepted the position as director of Mannheim observatory, but two years later, when Bugge died on 15 January 1815, Schumacher was appointed his successor to the ordinary professorship and called to Copenhagen.6 In the meantime Schumacher actually tried to obtain a position at the proposed university in Norway. Dur- ing the winter of 1811–1812 he wrote to the university planning commission in Copenhagen offering his services and at the same time suggesting the construction of a new and well equipped Norwegian observatory (not Figure 30.2: Heinrich Christian Schumacher (1780–1850) in Christiania, actually, but at Königsberg, which was (Portrait from Einar Andersen: Heinrich Chri- a possible location for the university at this point).7 stian Schumacher. Et mindeskrift. København: About the same time the planning committee received Geodætisk Instituts forlag 1975, p. 102.) an offer for a meridian circle from Johann Georg Repsold in Hamburg. On this occasion, the committee requested In the early nineteenth century the city of Altona, the advice of Thomas Bugge, who was negative to the being a part of Schleswig-Holstein, was subject to the proposal: “Bugge had no confidence in this new idea”; Danish-Norwegian kingdom under king Frederik VI. Hansteen later explained, “the zenith distance of the ce- During the preceding one and a half century the observa- lestial pole would have to be determined with a mural tory on top of the Round Tower in Copenhagen was the quadrant and a 12 foot zenith sector of the kind available centre of the Danish-Norwegian network of astronomical at the Round Tower in Copenhagen.”8 Thus, follow- and geodetic sciences. Both Hansteen in Christiania and ing Bugge’s advice, the committee turned down Rep- Schumacher in Altona developed new and more sophis- sold’s proposal. Instead, the instrument was acquired by ticated observatories in the periphery of the kingdom Gauß and after further modifications during 1817 it was during the 1820s and 1830s. In the following we will mounted by Repsold personally in the eastern meridian focus on the circulation of knowledge, skills and instru- room of the Göttingen observatory.9 Later, Hansteen ments between Hansteen in the north and Schumacher saw the instrument here on his visit to Gauß in 1839 in the south of the double-monarchy. We will emphasize when he was introduced to his geomagnetic observatory Schumacher’s role as Hansteen’s mentor and his me- and its instruments. Yet, Repsold’s proposal may have diator with German scientists and instrument makers been intended to serve an additional purpose, as sup- like Johann Georg Repsold – the Director of the new port for Schumacher’s and as foundation for an even state funded observatory at Millerntor in Hamburg from closer collaboration and integration between Christia- 1825 – in addition to Ertel, Kessels, Merz, Reichenbach, nia and Altona/Hamburg. It was an obvious strategic Utzschneider and Fraunhofer. move to combine Schumacher’s application to the Nor- Schumacher was born in 1780 in the small town of wegian university with an instrument proposal from his Bramstedt in Holstein between Kiel and Hamburg. His close friend and collaborator Repsold, since this new father Andreas Schumacher, a senior civil servant who university had to establish everything from scratch. In 262 his application Schumacher offered to build a first-rank Friedrich G. W. Struve visited regularly to learn more observatory with instruments from Hamburg and Mu- about this scientific enterprise.15 The official triangu- nich, provided sufficient funds were granted. He also re- lation of Hannover was not commissioned to Gauß by quested Gauß to send him a letter about the Mannheim George IV of England until 1820. By this time he had position in such wording that he could use it to influence already learnt much from the collaboration with Schu- decision makers in Copenhagen towards an appointment macher and Repsold in the area of Hamburg: “In Jahren in Christiania, stating to Gauß that he would not seri- 1821 bis 1823 hat Gauß die Messungen zur Bestimmung ously consider going to Mannheim.