The night passed over without anything worth mention, but we had had occasion to observe in the morning an instance of the curious evaporation that is frequently noticeable in the High Alps. On the previous night we had hung up on a knob of rock our mackintosh bag containing five bottles of Rodier’s bad wine. In the morning, although the stopper appeared to have been in all night, about four-fifths had evaporated. It was strange; my friends had not taken any, neither had I, and the guides each declared that they had not seen any one touch it. In fact it was clear that there was no explanation of the phenomenon, but in the dryness of the air. Still it is remarkable that the dryness of the air (or the evaporation of wine) is always greatest when a stranger is in one’s party—the dryness caused by the presence of even a single Chamounix porter is sometimes so great, that not four-fifths but the entire quantity disappears. For a time I found difficulty in combating this phenomenon, but at last discovered that if I used the wine-flask as a pillow during the night, the evaporation was completely stopped. At 4 A.M. we moved off across the glacier in single file towards the foot of a great gully, which led from the upper slopes of the glacier de la Bonne Pierre, to the lowest point in the ridge that runs from the Ecrins to the mountain called Roche Faurio,—cheered by Rodier, who now returned with his wraps to La Bérarde. This gully (or _couloir_) was discovered and descended by Mr. Tuckett, and we will now return for a minute to the explorations of that accomplished mountaineer. In the year 1862 he had the good fortune to obtain from the _Dépôt de la Guerre_ at Paris, a MS. copy of the then unpublished sheet 189 of the map of France, and with it in hand, he swept backwards and forwards across the central Dauphiné Alps, untroubled by the doubts as to the identity of peaks, which had perplexed Mr. Macdonald and myself in 1861; and, enlightened by it, he was able to point out (which he did in the fairest manner) that we had confounded the Ecrins with another mountain—the Pic Sans Nom. We made this blunder through imperfect knowledge of the district and inaccurate reports of the natives;—but it was not an extraordinary one (the two mountains are not unlike each other), considering the difficulty that there is in obtaining from any except the very highest summits a complete view of this intricate group.