probable that nobody—that is, unless some _lusus naturæ_ exists—will reach the summit; if artificially supplied oxygen be used, the acclimatisation may not be necessary; but the danger of an attempt by non-acclimatised men with oxygen apparatus is that a breakdown of the apparatus might lead to serious consequences, while a fully acclimatised man is probably just as capable of standing a height of 29,000 feet, unaided, as you or I would be able to stand the height of Mount Blanc to-morrow. When the Expedition of 1922 started I was personally of opinion that nobody could exist at a height about 25,000 or 26,000 feet without oxygen; but since we have proved that this can be done, it seems that the chances of climbing the mountain are probably greater if oxygen be not used. For the apparatus, and the spare cylinders required, necessitate the use of a large number of coolies; while in an attempt without oxygen only three or four coolies are required for the camping equipment and the food at the highest camp. Therefore it seems that the best chance of getting to the top of Mount Everest lies in the sending out of some nine or ten climbers, who can remain at a high camp, become thoroughly acclimatised, and then make a series of expeditions up the mountain, three or so at a time, as continuously as weather conditions will allow. By adopting these tactics the number of possible attempts up the mountain can be increased; and it seems to me that the chances of climbing to the summit lie in the multiplicity of possible attempts rather than in any other direction. It were better to prepare for a number of attempts each by a small but acclimatised party, rather than to stake all on one or two highly organised endeavours, in which oxygen, and a large number of coolies, are used. It is only a small proportion of coolies who can get up to the heights of 25,000 or 27,000 feet, and they should be used for any one attempt as sparingly as possible. During the war we all had our ideas of how it should be run, and they were generally wrong; the above plan is the writer’s idea of how to climb Mount Everest, and may or may not be right, but is enunciated for what it is worth. Among subsidiary effects of extreme altitudes, were those upon appetite, temper, and mental condition generally. Most of us will admit a good deal of peevishness and irritability while at a level of 22,000 feet and more; for the altitude undoubtedly makes one lose to some extent one’s mental balance, and the first way in which this appears on the surface is by a ruffling of the temper. In addition, one has a certain lack of determination, and when at a height approaching 27,000 feet I remember distinctly that I cared very little whether we reached the top of Everest or not. A good instance of this altered attitude of mind is provided by the fact that Finch and Bruce took a camera with them on their ascent, and forgot to take any photographs of their last day’s climbing.