All things that the Himalaya gives are big things, and now that the mountaineer has conquered the lesser ranges, he turns to the Himalaya, where the peaks stand head and shoulders above all others. Up to the present, however, owing to the difficulties of distance and size, none of the greater peaks have been climbed. In climbing the great peaks of the Himalaya, the difficulties are far greater than those of less lofty ranges. On most of the highest the mere climbing presents such difficulties that it would be foolish to attempt their ascent. Thousands of feet of steep rock or ice guard their summits. Unless climbing above 24,000 feet is moderately easy, and no strenuous work is required, it could not be accomplished. For in the rarefied air at high altitudes there is insufficient oxygen to promote the normal oxidation of bodily tissue. Above 20,000 feet a cubic foot of air contains less than half the amount of oxygen that it does at sea-level. As the whole metabolism of the body is kept in working order by the oxygen supplied through the lungs, the obvious result of high altitudes is to interfere with the various processes occurring in the system. The combustion of bodily material is less, the amount of energy produced is therefore less also, and so capacity for work is diminished progressively as one ascends. But that one is able still to work, and work hard, at these altitudes is evident by the experiences of Dr. Longstaff and Mr. Meade. On Trisul, 23,360 feet, Dr. Longstaff in ten and a half hours ascended from 17,450 feet to the summit. Whilst on Kamet, Mr. Meade's coolies carried a camp up to 23,600 feet. Dr. Kellas also in 1920 found his ascent on moderately easy snow above 21,000 feet approximated to 600 feet per hour. All these climbers were, however, acclimatised to high altitudes. The effect on anyone making a balloon or aeroplane ascent from sea-level would be different. Tissaudier in a balloon ascent fainted at 26,500 feet and on regaining consciousness found both his companions dead. Even on Pike's Peak, 14,109 feet, in the United States, many of those who go up in the railway suffer from faintness, sickness, breathlessness and general lassitude. Yet there are places on the earth,--the Pamirs,--where people live their lives at higher altitudes than Pike's Peak, without any effects of the diminished pressure being felt. They are acclimatised; their bodies, being accustomed to their surroundings, are good working machines.