September i 7th. We now set our faces for home, our next goal being Ladak. We were again to pass the Jagju-rapga, or Dschaga-tsangpo as others called it. In order to avoid treading again in my own footsteps, I resolved to cross the western part of the Selling-tso by boat. I therefore followed the north-west shore of the northern bay or basin of the Naktsong-tso, and then crossed over the narrow and structurally very interesting isthmus between that lake and the Selling-tso. But this day's march was after all only of a preliminary character, a hasty reconnaissance; for dogged as we were at every step by hundreds of Tibetans, it was impossible to work quietly and collectedly. For this reason I had to abstain from taking accurate levellings across the isthmus between the two lakes, and had to content myself with such observations as I was able to make in the course of my ride to the Selling-tso. Yet even those hurried observations were not without profit. Leaving behind us the fresh, limpid water of the relatively deep Naktsongtso, we rode towards the north, and found it was barely a kilometer to the culminating point of the flat neck of land. The ascent up to that point is remarkably easy and is nowhere diversified by the very slightest indication of an older beach-line. The ground was composed entirely of soft materials — sand and dust — and was overgrown with grass. From that culminating point it is quite easy to see with the naked eye, that there is a real difference between the levels of the two lakes. Upon glancing back, we perceived that we stood only a trifle higher than the surface of the Naktsong-tso, and the prospect across the lake was very little more extensive than it had been from the shore. When, on the other hand, we turned our eyes towards the north, we found that we were able to see an immense distance across the Selling-tso, and that this lake lay at a considerable depth below us, while the distance from the point on which we stood down to the lake-side was four times as great as that which stretched from the shore of the Naktsong-tso up to the summit of the dividing neck of land, that is to say nearly 4 km. I estimated the difference of level between the two lakes at about 4o m., although the hypsometrical observations, calculated afterwards by Dr Ekholm, give the difference as 25 m. only. The northern face of the isthmus bears many indications of higher lake-levels and a wider expansion of the Selling-tso. Our route ran through one
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