国立情報学研究所 - ディジタル・シルクロード・プロジェクト
『東洋文庫所蔵』貴重書デジタルアーカイブ

Hermann Schlaginweit regards the Lohit as the main river, and he says of the
Dibong: »er mündet nicht ganz unmittelbar in den Hauptstrom Brahmaputra, sondern
er ergiesst sich in den östlichsten der Arme, in welche der nun folgende Strom hier
sich theilt. *Dieser* ist der grosse Strom des östlichen Tibet, der Tsangbochú oder
'das reine (heilige) Wasser' der Tibeter; bei der Assamese wird er Dihóng genannt.¹
Kiepert, Stieler, Petermann followed the same way, and for a short time Tr.
Saunders could not resist such eminent authorities. To their speculations Richthofen
remarks that this fantastic representation which had no foundation whatever had for
30 years dominated the leading and most important cartographers.

Though Saunders was, until 1874, on the wrong side, misled by mere specula-
tion, there were geographers wise enough to consult only reliable exploration, so far
as it reached. In an article: *The Irawady and its sources*, Dr. J. Anderson
says: »I am no disciple of the theory that the Sangpo is the Irawady, and, in view
of Turner's account of the Sangpo and the accurate observations made by Captain
Montgomerie's pundits, I cannot see how it is possible, at the present day, that
anyone could be found prepared to re-advocate its claims.«²

Godwin-Austen was of opinion that neither Lohit nor Dihong were the
upper course of the Brahmaputra, but the Subansiri, the temperature of which, at
the junction, is lower than that of any other tributary. This theory was proved to
be wrong, by the expedition of Captain R. G. Woodthorpe and Lieut. Harman
during the winter of 1877—78. The volume of the Subansiri was found to be only
¹⁄₄ of that of the Dihong, »which thus tends more than ever to identify the latter
with the great river of Tibet.«³

On November 30th, 1874 Nain Sing crossed the river at Chetang after his
great journey through Tibet. He had seen the course of the river for a distance
of about 30 miles below Chetang, and he had been informed that it flowed S.E.
into Assam. At Chetang he describes the Tsangpo thus:

»The valley through which the river flows was here several miles across; on
the left bank of the stream was a stretch of sand fully 1¹⁄₂ mile in breadth, the
whole of which is said to be under water in the months of May, June and July
during which season the river is much flooded, both on account of the increase of
water from the then rapidly melting snows, as well as from the rain which falls in
considerable quantities from April to June. The river is here no longer used for
irrigation, as above Shigátzé, but all the smaller streams which issue from the
mountains on the north and south are thickly bordered with cultivated land.«⁴

Another native explorer, L—, started, in March 1875, from Darjeeling to
Shigatse. After crossing Kangra-lama-la or Lachen-la he was taken prisoner and