The history of magnetic measurements in Antarctica and the surrounding oceans can be traced back to the expeditions looking for the South Magnetic Pole (see Fogg, 1992 for a review). Until the turn of the 19th/20th century, all measurements were performed at sea, on ships including Gauss (E. Drygalski expedition, 1901-1903) and Discovery (first R.F. Scott expedition, 1901-1904), both being equipped with a magnetic observatory (Lüdecke, 2003). The first confirmed landing (although certainldy not really the first one), can be credited to C. Borchgrevink's expedition (1893-1895), whose party reached Cape Adare and made some magnetic measurements there (Fogg, 1992). If we define the Antarctic region as that being south of 60° S the longest span of data is that collected at the observatory of Orcadas del Sur (South Orkneys, IAGA code ORC).