We commenced the ascent from the Val d’Entraigues, to the west of the most western of these small glaciers, and quitted the valley by the first great gap in its cliffs after that glacier was passed. We did not take to the ice until it afforded an easier route than the rocks; then (8.30) Croz went to the front, and led with admirable skill through a maze of crevasses up to the foot of a great snow _couloir_, that rose from the head of the glacier to the summit of the ridge over which we had to pass. We had settled beforehand in London, without knowing anything whatever about the place, that such a couloir as this should be in this angle; but when we got into the Val d’Entraigues, and found that it was not possible to see into the corner, our faith in its existence became less and less, until the telegraphing of Almer, who was sent up the opposite slopes to search for it, assured us that we were true prophets. [Illustration: A SNOW COULOIR.] Snow _couloirs_ are nothing more or less than gullies partly filled by snow. They are most useful institutions, and may be considered as natural highways placed, by a kind Providence, in convenient situations for getting over places which would otherwise be inaccessible. They are a joy to the mountaineer, and, from afar, assure him of a path when all beside is uncertain; but they are grief to novices, who, when upon steep snow, are usually seized with two notions—first, that the snow will slip, and secondly, that those who are upon it must slip too. Nothing, perhaps, could look much more unpromising to those who do not know the virtues of couloirs than such a place as the engraving represents,(121) and if persons inexperienced in mountain craft had occasion to cross a ridge or to climb rocks, in which there were such couloirs, they would instinctively avoid them. But practised mountaineers would naturally look to them for a path, and would follow them almost as a matter of course, unless they turned out to be filled with ice, or too much swept by falling stones, or the rock at the sides proved to be of such an exceptional character as to afford an easier path than the snow. Couloirs look prodigiously steep when seen from the front, and, so viewed, it is impossible to be certain of their inclination within many degrees. Snow, however, does actually lie at steeper angles in couloirs than in any other situations;—45° to 50° degrees is not an uncommon inclination. Even at such angles, two men with proper axes can mount on snow at the rate of 700 to 800 feet per hour. The same amount can only be accomplished in the same time on steep rocks when they are of the very easiest character, and four or five hours may be readily spent upon an equal height of difficult rocks. Snow couloirs are therefore to be commended because they economise time.