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Digital Archive of Toyo Bunko Rare Books

shown for Tun-huang, 94° 47′, is itself
affected by the erroneous adjustment of
R. B. Lāl Singh's triangulation which, as
explained above under Sheet No. 30, brought
the easternmost triangulated point on the
Mirān–Tun-huang route by 5′ 10″ too far
to the east, it is possible that the longitude
value adopted for An-hsi is also somewhat
overestimated. This suspicion is borne
out by Mr. Clementi's chronometric longi-
tude value for An-hsi, which is 95° 47′ 20·6″,
and by Dr. Vaillant's values for Tun-huang
and Hung-liu-yüan (D. 2), N.W. of An-hsi,
each derived from observation of two lunar
occultations. These are 94° 36′·5 and 95°
23′·7 against circ. 94° 47′ and 95° 33′ re-
spectively in our sheet. ²⁴

Roborovsky's observations at Tun-huang
(Sha-chou), based on chronometric values
and taken with special care, indicate for his
station (a short distance from the town and
almost due N. of it) the longitude of 94°
42′ 24″. ²⁴ᵃ This agrees very closely with
the position derived from our surveys and
shown in this sheet, 94° 47′, if allowance is
made for the correction of − 5′ 10″ which, as
just mentioned, has to be made in the longi-
tude of the easternmost triangulated point
near the Mirān–Tun-huang route.

It deserves to be further noted that the
plotting of available traverses from the Tibet
side brings An-hsi to a longitude of about
95° 52′, and that the Russian Trans-frontier
map shows one of approximately 95° 58′.
The various routes radiating from Tun-huang
and An-hsi are controlled by the compara-
tively large number of latitude observations
recorded below.

Regarding the historical topography of
the An-hsi–Hāmi 'highroad', see the re-
ferences given above for Sheet No. 37. The
geographical features of the lower Su-lo-ho
basin have been fully discussed in Serindia,
ii. pp. 578 sqq., with special reference to the
natural line of defence offered by the Su-lo-
ho for the earliest Chinese road into the
Tārim basin past Lou-lan. There, too, I

have indicated the importance of the large
oasis of Tun-huang with regard to this road
and the irrigation facilities it derives from
its situation on the alluvial fan of the Tang-
ho, the largest tributary of the Su-lo-ho.

For descriptions of the desert belt, both
marsh-edged and gravel 'Sai', extending
along the Su-lo-ho from the Khara-nōr lake
towards the cultivated area of An-hsi, and
followed by the line of the ancient Chinese
Limes, see Desert Cathay, ii. pp. 5 sqq., 40
sqq., 131 sqq.; for the oases of Tun-huang
and An-hsi, and the important sacred site of
the 'Thousand Buddhas' near the former, see
ibid, ii. pp. 10 sqq., 159 sqq., 233 sqq. The
topography and remains of the Limes sec-
tions falling within this sheet are treated in
Serindia, ii. pp. 585 sqq., 717 sqq.; iii. pp.
1089 sqq.

Within the area of the sheet we distin-
guish three well-marked zones. In the north
the surveyed route towards Hāmi, first opened
by the Chinese in A.D. 73 and since then a
main line for China's Central-Asian expan-
sion, crosses in succession the much-decayed
hill ranges of the Central Pei-shan. Those
shown on the map between the stations Sha-
ch'üan-tzu (B.1) and Pi-ting-tzu (D.3) are
manifestly connected with the five Pei-shan
ranges distinguished by Professor Futterer's
very careful topographical and geological
survey along his more easterly route from
near Mu-t'ou-ching (No. 37. D. 4) to near
the Su-lo-ho bend (No. 40.B.4). ²⁵ On both
routes water and scanty grazing can be found
only in a few isolated depressions of the
broad desert valleys separating those ranges.

The low southernmost range of the Pei-
shan towards the west seems to merge in an
outlier of the Kuruk-tāgh (A,B.3). Be-
tween it and the foothills of the Nan-shan in
the south extends the trough of the lower
Su-lo-ho valley. The portion lying to the
west of Tun-huang entirely shares the cha-
racter of the delta and terminal basin of the
Su-lo-ho, as shown in Sheet No. 35. C,D.4.

The abundant supply of water provided