On December i3th our journey proceeds to the S. E. and S. S.E. From Nasa we have 4.2 km. to the pass Gyanyak-la or La-gyanyak, as it is also called, the altitude of which is 5,161 m., meaning a rise of 391 m., or at the unusually steep rate of i : 10.7. On the southern side of the pass we have 2.8 km. to Camp LXXX VI1, where the height is 4,875 m., or a descent of 276 m., being a fall of 1: 1 o.I. The profile of the latitudinal range in which the pass is situated is, therefore, comparatively accentuated.
At about 9 o'clock p. m. a regular S. W. storm set in and continued the whole night and the next day. The minimum temperature was only —10.3°, or 21.2° warmer than the previous night. Such enormous variations are indeed curious. The sky was covered by heavy clouds, hindering the usual strong radiation. All loose material was swept away by the wind. The corrasion of the ground is, to a large extent, stopped by two factors. In the summer the loose material, dust and sand, is bound by moisture and rain and cannot then be moved even by the strongest winds. In winter the same material is frozen, by which the force of the wind is diminished. But at seasons when the ground is dry, and the temperature above zero, the wind has an enormous force, and we have, as I have said before, had occasion to see the results of its energy.
At Nasa wolves were very numerous. As soon as we had left the valley and its ice-sheets, the ground began to rise, and we climbed the slopes of the western hills which were cut through by several small, but deep and tiring, dry watercourses, all going down to the rivulet of Nasa. In the principal bed from the pass, there was a good deal of ice. The western hills are all ramifications from the principal range containing the pass, a range which probably is a water-parting between the Bogtsang-tsang-po and the Tang Yung-tsaka, unless there is another self-contained basin to the north of the last-mentioned lake. Approaching the pass, the ascent becomes very steep. To our left we have the pass-valley with its ice bed, coming from a spring surrounded by good grass. In some of the side valleys there is also some ice. The region is very rich in springs. Finally we reach the
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