Mount Everest, as all know, lies on that part of the Himalaya which is narrowest. It is, therefore, exposed very rapidly to the first assaults of the South-west monsoon, and this monsoon advances up the Bay of Bengal at an earlier period in the year than that of its Western branch, the Gulf current. It is this fact which supplies the greatest difficulty to be faced in an attack on any of the great peaks which lie in this region, giving one an unusually short season. However, to a certain extent this is counteracted by the fact that the winter climate in this portion of the Himalaya is far drier than it is in the West. There is less deposit of snow on the mountains in this section of the Himalaya than there would be, for instance, in the Kashmir mountains, and this, to some extent, makes up for the early advance of the monsoon, and consequent bad weather, which renders any exploration of the great heights during the time that the monsoon blows an impossibility. Towards the end of May the monsoon arrives in Darjeeling, and then, according to the strength of the current, quickly approaches the Southern faces of the Himalaya, and, as the current strengthens, drifts across their summits and through the gorges and over the lower ridges. The problem, therefore, of any party exploring in these mountains resolves itself into the rapidity with which they can establish their base of operations in a suitable locality to explore the mountains and to climb them. During the period of the very great cold, naturally, the upper heights are impossible, and camping on the upper glaciers is in itself also almost impossible. Travelling across Tibet in March, crossing high passes of over 17,000 feet is such that, although it might be perfectly possible to do, it would be a great strain on the stamina of the party, and likely to detract from their condition. We had, therefore, to adapt our advance into Tibet so as to make it at the latest possible moment, in order to avoid the very worst of the weather, and yet at the earliest possible moment, so that we could arrive at the foot of our mountains with sufficient time to attack them before the weather broke up and rendered mountaineering an impossibility at a great height. It resolves itself, then, almost into a race against the monsoon. This was our problem, and it is my special province in these opening chapters to show how we tackled it.