[Dr Alexander M. Kellas and the first Mount Everest expedition].

In 1921 the government of Tibet gave permission for a British party to attempt Mount Everest from the northern Tibetan side. Little was known about the physiological and medical problems associated with ascents to extreme altitudes. The person who knew most about these topics was Dr. Alexander Kellas, lecturer in medical chemistry at the Middlesex Hospital Medical School. He had made a number of expeditions to the Sikkim Himal and the Tibetan border before the first world war, and had become increasingly interested in the problems caused by altitude. He was invited to join the Everest expedition but died on the approach march at Kampa Dzong on the Tibetan plateau, within sight of the mountain. Before he went on the expedition Kellas wrote an article entitled A consideration of the possibility of ascending Mt. Everest. This paper was never published, but the manuscript exists in the archives of the Royal Geographical Society and the Alpine Club in London. As Kellas saw it, the main issue was whether sufficient adaptation could occur to allow a climber to ascend from a camp at about 7,700 m to the summit (8,848 m) in one day without supplementary oxygen. His conclusion was that this was possible and, in fact, the first such ascent by Habeler and Messner in 1978 started from a camp at 7,900 m. Kellas calculated the pressure on the summit to be 251 mmHg, a more accurate figure than estimates based on the "Standard Atmosphere" Kellas estimated maximum oxygen uptake at the summit to be 970 ml/min, and the current value is thought to be about 1,070 ml/min. His estimates of the climbing rate near the summit closely parallels the rate of Habeler and Messner. Kellas had a talent for asking the right questions. He applied his considerable knowledge of physiology to the topic of high altitude, and his suggestions and recommendations were of consistently high quality. He deserves to be better known, both for his geographical surveys and for his pioneer work on high altitude medicine and acclimatisation. The 1921 expedition, after many failed attempts, discovered a possible route to the top of Mount Everest, which was used on all the summit attempts between the two world wars. The route went from Kharta, over the pass Lhakpa La, across East Rongbuk glacier and up via the north col.