By following the glaciers, the snow-slopes above, and the couloirs rising from them, it is usually possible to get very close to the summits of the great peaks in the Alps. The final climb will, perhaps, necessarily be by an arête. The less of it the better. It occasionally occurs that considerable mountain slopes, or faces, are destitute of snow-gullies. In that case it will, very likely, be best to adhere to the faces (or to the gullies or minor ridges upon them) rather than to take to the _great_ ridges. Upon a face one can move to the right or to the left with more facility than upon the crest of a ridge; and when a difficulty is arrived at, it is, consequently, less troublesome to circumvent. In selecting the routes which were taken in 1865, I looked, first, for places where glaciers and snow extended highest up into the mountains which were to be ascended, or the ridges which were to be crossed. Next, for gullies filled with snow leading still higher; and finally, from the heads of the gullies we completed the ascents, whenever it was practicable, by faces instead of by arêtes. The ascent of the Grand Cornier (13,022), of the Dent Blanche (14,318), Grandes Jorasses (13,700), Aiguille Verte (13,540), Ruinette (12,727), and the Matterhorn (14,780), were all accomplished in this way; besides the other excursions which will be referred to by and by. The route selected, before the start was made, was in every case strictly followed out. We inspected all of these mountains from neighbouring heights before entering upon their ascents. I explained to the guides the routes I proposed to be taken, and (when the courses were at all complicated) sketched them out on paper to prevent misunderstanding. In some few cases they suggested variations, and in every case the route was well discussed. The _execution_ of the work was done by the guides, and I seldom interfered with, or attempted to assist in it. The 13th of June 1865 I spent in the valley of Lauterbrunnen with the Rev. W. H. Hawker and the guides Christian and Ulrich Lauener; and on the 14th crossed the Petersgrat with Christian Almer and Johann Tännler to Turtman (Tourtemagne) in the Valais. Tännler was then paid off, as Michel Croz and Franz Biener were awaiting me. It was not possible to find two leading guides who worked together more harmoniously than Croz and Almer. Biener’s part was subordinate to theirs, and he was added as a convenience rather than as a necessity. Croz spoke French alone, Almer little else than German. Biener spoke both languages, and was useful on that account; but he seldom went to the front, excepting during the early part of the day, when the work was easy, and he acted throughout more as a porter than as a guide.