Amundsen (at left) and companions at Polheim, South Pole, December 1911
Polheim, "Home of the Pole", was Roald Amundsen's name for his camp
(the first ever) at the South Pole. He arrived there on December 14, 1911, along
with four other members of his expedition; Helmer Hanssen, Olav Bjaaland, Oscar
Wisting, and Sverre Hassel.
At the first estimated position of the South Pole, Amundsen declared "So we plant you, dear flag, on the South Pole, and give the plain on which it lies the name King Haakon VII's Plateau."
Due to the historical disputes over the claims of polar explorers prior to Amundsen's expedition, particularly the competing claims of Frederick Cook and Robert Peary to have reached the North Pole first, Amundsen took special care in making his polar observations.
Approaching the geographical South Pole (or North Pole) the meridians of longitude converge, eventually making a measure of longitude meaningless, as a degree of longitude will become smaller and smaller. At the pole itself, (assuming one has accurate enough instruments), all meridians meet. Amundsen reasoned that the extra effort in obtaining longitude could be saved, and he focused on latitude. (Amundsen adopted this strategy after attending a lecture at The Royal Geographical Society in London in November 1909, given by A.R. Hinks a lecturer in Surveying and Cartography at Cambridge University, who put forward this theory when discussing the subject of determining positions near the Poles).
With the instruments he had, Amundsen estimated that he could determine the position of the pole by no better than a nautical mile. In order to ensure that there was no doubt that his expedition had in fact reached the South Pole, he determined to encircle, or "box" the pole.
Three members of the expedition were sent out from the current estimated position of the pole, one continuing on the current expedition track and two at right angles to this direction. Each skier continued 10 miles and erected a spare sledge runner with a black flag and note for Robert Falcon Scott when and if he arrived. (He arrived more than a month later.) The note contained the position to Amundsen's camp.
While the skiers erected the encircling markers, Amundsen took altitudes of the sun for fixing his position. Since his theodolite had been damaged, observations were made with a sextant, the sun slowly circling the camp in 24 hours, and never setting.
From these calculations, Amundsen determined that their current position was approximately 5.5 miles from the mathematical South Pole point. This point had been "boxed" by the skiers.
On December 17 Amundsen proceeded to his estimate of the true South Pole position, and took additional observations for 24 hours, two men standing watch for each observation, and co-signing each others navigation books. Again, this was to ensure that there was no doubt as to the expedition attaining the pole.
From these calculations, it was determined that they were still 1.5 miles from the pole, and two men were sent to erect additional pennants.
Finally, Amundsen added still more pennants to cover the remaining area. In this way, the pole had been boxed three times all told.
The official expedition camera had been damaged en route to the pole, so the only photographs taken were from an amateur camera brought by expedition member, Olav Bjaaland.
On December 18, 1911, Amundsen's expedition left Polheim, leaving behind his reserve tent, along with a letter for Scott and a letter intended for Scott to deliver to King Haakon in the event that Amundsen failed to return. Both letters were later found with the bodies of Scott and his companions, and were further proof that Amundsen had attained the pole.
When Amundsen's calculations were verified, it was found that his final camp lay within 2,500 yards of the mathematical South Pole, a remarkable achievement given the instruments available. In addition, it had been ascertained that expedition member Helmer Hanssen - one of the expedition members that had been skiing in a grid pattern between the 'box' markers - came to within two hundred yards of the mathematical South Pole on one of his runs.
Amundsen's Map drawn in 1912 aboard Fram