The stump was on a steep hillside and swayed noticeably as the temperature changed.
Taking the observations was almost as arduous. Ogilvie used an unheated cabin, in temperatures that ranged between -35 and -46 degrees Celsius, so that his view of the night sky would not be distorted by heat waves. He managed to make 22 observations between November and February, calculating the position of the meridian with impressive accuracy. When he checked his calculations eight years later, he found he had located the meridian only 109 feet too far east, probably because of the tree stump's movements in the cold.
