We could make no further progress; the pass lay at the distance of several hours’ march, up a valley to the north, down which the glacier must have rolled that had deposited this great moraine; the pass had been closed since October, it being very lofty, and the head of this valley was far more snowy than that at Wallanchoon. We halted in the snow from 3 to 4 p.m., during which time I again took angles and observations; the height of this spot, called Pabuk, is 16,038 feet, whence the pass is probably considerably over 17,000 feet, for there was a steep ascent beyond our position. The sun sank at 3 p.m., and the thermometer immediately fell from 35° to 30·75°.[81] [81] At 4 o’clock, to 29·5°, the average dew-point was 16·3°, and dryness 0·55; weight of vapour in a cubic foot, 1·33 grains. After fixing in my note and sketch books the principal features of this sublime scene, we returned down the valley: the distance to our camp being fully eight miles, night overtook us before we got half-way, but a two days’ old moon guided us perfectly, a remarkable instance of the clearness of the atmosphere at these great elevations. Lassitude, giddiness, and headache came on as our exertions increased, and took away the pleasure I should otherwise have felt in contemplating by moonlight the varied phenomena, which seemed to crowd upon the restless imagination, in the different forms of mountain, glacier, moraine, lake, boulder and terrace. Happily I had noted everything on my way up, and left nothing intentionally to be done on returning. In making such excursions as this, it is above all things desirable to seize and book every object worth noticing on the way out: I always carried my note-book and pencil tied to my jacket pocket, and generally walked with them in my hand. It is impossible to begin observing too soon, or to observe too much: if the excursion is long, little is ever done on the way home; the bodily powers being mechanically exerted, the mind seeks repose, and being fevered through over-exertion, it can endure no train of thought, or be brought to bear on a subject. During my stay at Yangma, the thermometer never rose to 50°, it fell to 14·75° at night; the ground was frozen for several inches below the surface, but at two feet depth its temperature was 37·5°. The black bulb thermometer rose on one occasion 84° above the surrounding air. Before leaving, I measured by angles and a base-line the elevations of the great village-terrace above the river, and that of a loftier one, on the west flank of the main valley; the former was about 400 and the latter 700 feet.