The first seventeen stations lie higher than our starting-point, No. 1, which we fixed at Camp CLIX. Then follows a stretch which is sometimes above, sometimes below, No. i, though mostly above it. At Camp CLX the staff was 0.197 m. below station No. I, indicating a fall of barely 2 dm. in a distance of 9140 m. Between station No. 81 and No. 134 there are only three points that lie higher than the starting-point. The interval between No. 135 to No. 149 also lies below the starting-point. Next follows a stretch of extraordinary flatness. Camp CLXII lies 0.100 m. above station No. i, and Camp CLXIII 0.744 m. above the same; so that between these two stations, a distance of 13,007 m., there is a rise of 0.644 m. Of the 51 stations only 4 lie below the starting-point, and the amount is very small, 0.164 m. at the most. This stretch of the route brings us up to the crown of the scarce perceptible swelling, situated, at its highest, 1.415 m. above the point of departure. From this »culminating point», barely the height of a man, the surface falls away towards-Camp CLXIV, which lies 0.440 m. above station No. r. While the ascent up to the culminating point of the swelling which separates these two desert lake-depressions is extraordinarily uniform, the descent to the south, towards the Kara-koschun, is far less uniform; and both the difference of slope and the difference of 2 M. elevation in a few hundred meters of distance begin immediately south of the swelling, and continue down to the shore of the lake. Although the sectional line undulates in waves, the general fall is nevertheless quite perceptible. At Camp CLXV the staff was 1.732 m. below station No. i and 0.550 m. above the Kara-koschun.
The accompanying section (see Plate 37) shows with especial clearness and distinctness not only both the depressions of the Desert of Lop, but also the swelling between them. It is only by exaggerating the vertical scale in this extraordinary way that the differences of level at the different stations can be made evident to the eye. Here the vertical scale is exaggerated 2000 times, that is to say, the 41 cm. long projection would have to be repeated 2000 times before it attained its natural dimensions in relation to the heights here shown; or in other words, if the vertical scale I have employed be retained, the base-line would have to be extended to a length of 819 m., or very little short of a kilometer. In spite of its preposterous dimensions, our plate does give a connected general view of the surface-relations of the desert. First we have Camp CLIX, a purely arbitrary point, where the surface has been excavated by the wind. This is evident from the fact that the houses of Lôulan stand upon pediments of clay 2 to 3 m. high, which have, of course, been formed since the old lake of Lop-nor disappeared. Camps CLX and CLXI lie lower than the first camp, but the three succeeding camps lie above it and indicate the flat step at the threshold of the swelling. Camps CLXV and CLXVI lie lower than the first and belong to the depression of the Kara-koschun. The lowest of all is Camp CLXI, 0.381 m. below the level of even the Kara-koschun ; it is situated in the middle of the Lop-nor depression.
The similarity between the parts of the surveyed line that come north of the old Lop-nor and those north of the Kara-koschun is at once very striking. The irregularities of the surface there are considerably greater than they are south of the two lakes in question. But it should be observed, that, while the tract north of the Kara-koschun has not any other noteworthy hollows or elevations except those
Hedin. Tourney in Central Asia. IL 42
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