Introducing theodolites for mapping in Norway

ABSTRACT Christopher Hansteen, professor of applied mathematics at the University of Oslo, was appointed as a part-time director of geodesy at the Geographical Survey of Norway in 1817. He quickly realized that previous measurements of angles using geographical circles did not produce data of required quality for geodetic surveying. Using archival sources, the article describes how Hansteen acquired a theodolite from Germany and applied it to demonstrate to the National Assembly (Storting) that investment in new instruments for the Survey was required. With funds granted in 1824, he ordered theodolites, sextants and chronometers from German instrument makers. He conducted a field operation in 1827 in preparation for a first-time survey and mapping of the entire coast of Northern Norway. The article draws on observation logbooks to reconstruct the triangle arc established with the new theodolites between 1828 and 1842. The triangulation stations served as reference points for plane table mapping. Map orientation and geodetic coordinates were controlled by astronomical observations of latitude and chronometer determinations of longitude at two temporary observatories and through selected field observations. The resulting ten maps were the first production released to the public by the Geographical Survey of Norway.