grass. The mountains in the same quarter consisted partly of conglomerate, partly of a light variety of rock, possibly quartzite: the dip was 6o° towards the S. 35° E. At that point the lake narrows very appreciably, and the mountains which rise on the northern shore are of a somewhat different shape from those which we had hitherto seen. The main range nearest to the lake sends down to it several minor spurs, with short and small glens between them. On the flatter parts of the shore we again observed the tents and flocks of the nomads.
On the 24th September we traversed the last portion of the Tschargut-tso, namely its narrowest and most westerly part running towards the west-south-west. Our course ran nearer to the southern shore, and the depth there amounted to 13.95, 15.00, 5.50, 6.8o, and 1.65 m. The mountain-range on the south is steeper and more craggy, and the gravelly scree at its foot also inclines steeply towards the lake, only one or two of its capes being flatter. On the northern shore there was on the contrary room for a broad strip of level ground. The lake narrowed still further, its tapering extremity swinging away towards the south. It is here that it is entered by the river Tsangmo-rapga, which issues from the large lake in the west, the name of which is, I was told diversely, the Addan-tso and the Nagma-tso. In its mouth lies a low sandy island. The river, which is not more than I km. in length, flows in almost a straight line from north-west to south-east, and is very uniform in breadth. It is so deep that the current is hardly noticeable, except in the relati vely shallow places, where I measured the volume, and there the current was lively. The breadth of the river was 35 m., its mean depth 2.79 m., and its mean velocity 0.205 m. in the second. The volume was consequently 20.02 cub.m. in the second. On 9th Sept. I found that the volume flowing out of the Tscharguttso was 25.9 or in round numbers 26 cub.m.; but on 24th Sept. this lake was receiving 20 cub.m. in the second from the Addan-tso, and this notwithstanding the continuous evaporation. The difference of volume is of course simply due to the fact, that the latter measurement was taken 15 days later than the other, a difference of time calculated to produce a very appreciable effect at that season of the year. I have already stated, that there were no signs to indicate that the Jagju-rapga had been at a higher level during the summer that was just past, and that the river stood on 9th Sept. at what was approximately its maximum level. But I also considered it probable, that a drop might take place during the winter, though to what extent it would be impossible to form any idea, seeing that the conditions which exist in the drainage-area of the Addan-tso are unknown. All that is known to me in this regard seems to suggest, that the Addantso receives a pretty considerable volume. For to the south of this lake there is an extensive mountainous country with ranges running east and west. After a hard and stormy, though fortunately short, voyage across the extreme eastern bay of the lake, we landed at a point upon which we beheld conspicuous peaks, capped with perpetual snow, to the S. 3° W., S. 13° W., and S. 48° W. An hour later we crossed over a pass on the northern shore, from which we obtained another magnificent view of the mountainous country to the south, and especially of two transverse glens opening in the S. 9° W. and S. 29° W. Even at the great distance at which we then were, we could see that streams of no inconsiderable size were making their
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