In this chapter I intend to give the additional remarks to the description of my third crossing of the Transhimalaya which is to be found in Chapter XXXI of Vol. III. This journey across the system begins at Camp CL and comes to an end at Camp CLXVIII or the confluence of Chaktak-lsangpo and the great Tsangpo.
The first day's march, April 30th, takes us 12.3 km. S. W. and south, being a rise of so m. as Tsangdam, Camp CLI, is at a height of 4,758 m. ; the rate is I : 246. Pan. 168, Tab. 3o, shows the Targo å angri in a foreshortened perspective from a point about halfway and situated at the S. E. base of the mountain, from where the highest peak in sight is at N. 62° W. Pan. 18oA and B, Tab. 32, gives a topographically important view of the range west of Shuru-tso, called Gangri-do, or Gangri-to to the W. S. W. and S. W., the peak Pungkar to the N. 73° W., peak Targo-rigüt to the N. 40° W., the culminating Targo-gangri peak to the N. 16° W., Tsangdam camp to the N. E. and the hill Tar larva to the S. E. and S. S. E.
The distance from Camp CL to Camp CLI along the Targo-tsangpo is about I I .I km., and the fall of the river is therefore, as i : 222. If the distance from Camp CL to the southern shore of Dàngra yum-tso be considered to be 44 km. , and supposing the fall of the river would be the same the whole way, it would amount to 200 m., and Dangra yum-lso would be at an altitude of 4,508 m. But according to the general law of erosion and plateau-land morphology the rate of fall diminishes gradually, and it may be regarded as pretty certain that the lower course of the Targo-tsangpo has an extremely slow fall. On our map of I : I o00 000 Colonel Byström has adopted the height of 4,646 m. for the lake, which is the altitude calculated from the observations of Nain Sing and entered (15,240 feet) on the map of Trotter. This observation seems to agree very well with my observations south of the lake. The altitude of Nain Sing becomes the more reliable if we remember that he has given to Ng-angtse-tso an altitude of 4,683 m. which is very near the one I found, 4,694 m., after many days of observations. If the relations were the same in both cases, 1. e. that the altitude of Dangra yum-tso as given by the Pundit
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