94 NOTES ON INDIVIDUAL MAP SHEETS [Chap. IV
both in 1207 and 1914 after fresh snow-fall in October.
The historical topography of the Chinese ` highroad ' from An-hsi to Hirai has been discussed by me in Serindia, iii. pp. 1141 sqq., and also in connection with the ad- venturous desert crossing of Hsüan-tsang
( A. D. 631 ). The record of this in the
pilgrim's We throws interesting light on the physical features of the forbidding `Gobi' to the S.E. of Yen-tun; cf. Geograpk. Journal, November 1919, pp. 273 sqq. For a brief account of the route followed in 1914 from Mao-mei to the northern slopes of the Karlik-tâgh, cf. Geograpk. Journal, xlviii. pp. 200 sq.
Here in its easternmost portion the T'ien-shan, as elsewhere along its far-flung line, forms a great geographical divide. To the north of that part of the range which raises its crest above the line of perpetual snow and which is appropriately known as .Karlik-tdgIc, `the Snowy Mountains', we find plateau-like ground (A. 2), typical of 1)zungaria, with abundant grazing and water more than sufficient for the limited area actually under cultivation. But eastwards where the range steadily falls in height, ultimately to merge in the plains of Mongolia, the character of its northern slope rapidly changes and the wide amphitheatre of piedmont gravel surrounding the small village of Bai (C. 2) is as arid as any ` Sai' of the K'un-lun.
Astronomically observed latitudes.
The southern slope of the Karlik-tâgh is extremely barren throughout, and only where subsoil drainage from the snows is available for the irrigation of naturally fertile loess beds at the top of the gravel glacis, is permanent occupation possible, as marked by the string of small oases from Khotun-tam to Tâsh-bulak.
The southern glacis of the Tien-shan sinks down to a trough-like depression which is clearly marked from Chin-érh-ch`üan (D. 4) down to Yen-tun on the An-hsi—Hâmi road (A. 4) and probably extends for some distance beyond to the south-west. This-depression, not unlike that of the Su-lo-ho but without running water throughout, divides the T'ien-shan glacis from the desert uplands of the Pei-shan. The northernmost range of the latter projects into the south-eastern corner of this sheet and is crossed by the Shuang-ch`üan-tzu pass (D. 4). The absolutely bare glacis of the same desert range is crossed further west by the very exposed and much dreaded portion of the caravan road between B`u-shui and Yen-tun (A, B. 4) .
Corrections. B. 3. The road-line west of C. CL%IV should be marked as leading toHâmi.
D. 4. A vegetation area with spring should be shown 8 miles S. E. of Pan-tzuch`üan, with a route diverging to the south.
A pass symbol to be added against Shuang-ch'üan-tzu pass.
1906-08. K`u-shui, Camp 248 (south of station; B. 4)
1913-15. Chin-êrh-ch`üan, Camp 215 (to W. of springs ; D. 4 )
Bai, Camp 220 ( near Beg's house, by stream ; C. 2 )
NOTES ON SHEET No. 38 ( TUN-HUANG, AN-HSI )
The greater portion of this sheet, in the north, comprises the desert ranges and plateaus of the Pei-shan. Here the survey was confined to the ground along the Chinese cart road leading from An-shi to Mimi and followed in 1907; only in the north-eastern corner and in the south-west were hill features observed from routes of the third journey. The southern part of the sheet shows the wide trough-like valley of the lower Su-lo-ho course, together with the foot-hills of the westernmost Nan-shan range. This ground, owing to the archEeological and historical interest of the remains I was able
to trace of the ancient Chinese border-line along the Su-lo-ho course, was surveyed on numerous routes both in 1907 and 1914.
The various traverses were adjusted on the position adopted for An-hsi (D.3). The observed latitude is 40° 31' 38". The longitude 95° 57' was derived from the closely concordant results of the three traverses brought in 1914. from the side of Tun-huang (or Sha-chou; B. 4). This longitude showed a difference of only one minute from the value assigned to An-hsi in Sheet No. 81 of the 1906-08 Map and was hence finally accepted. But inasmuch as the longitude.