But how exactly is this to be done? It is to this question that one would wish to deduce an answer from the experience of 1922. It is very unlikely that any future party will find itself in the position to carry out any ideal plan of organisation. Ideally, they ought to start by considering what previous performances might help or hinder the aim of bringing the party of attack in the fittest possible condition to the last camp. What ought they to have done or not to have done, having regard to acclimatisation? It is still impossible to lay down the law on this head. After the first Expedition, I supposed that the limit of acclimatisation must be somewhere about 21,000 feet. It now seems probable that it is higher. One of the physiologists who has been most deeply concerned with this problem of acclimatisation considers that it would probably be desirable, from the physiological point of view, to stay four or five days at 25,000 feet before proceeding to attempt the two last stages on consecutive days. Those of us who slept at Camp V for the first attempt would certainly be agreed in our attitude towards this counsel. The desire to continue the advance and spend another night at a higher elevation, if it persisted at all for so long a time at 25,000 feet, would be chilled to tepidity, and the increasing desire to get away from Camp V might lead to retreat instead of advance. The conditions must be altogether more comfortable if the climbers are to derive any advantage from their rustication at this altitude. It would not be impossible, perhaps, if every effort were concentrated on this end, to make a happy home where the aspiring mountaineers might pass a long week-end in enjoyment of the simplest life at 25,000 feet; it would not be practicable, having regard to other ends to be served by the system of transport. But it might be well to spend a similar period for acclimatisation 2,000 feet lower on the Chang La. There a very comfortable camp, with perfect shelter from the prevailing wind and good snow to lie on, can easily be established. Noel actually spent three successive nights there in 1922, and apparently was the better rather than the worse for the experience.