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

84

HENRY STRACHEY.

As a general rule embracing all the lakes of Ngari. Strachey regards the fact that none of them can ever have been much fuller than they are now, or too vertical feet. In this respect he should have found a great difference between them and the lakes of the interior plateau-land, where certain lakes, as Lakor tso, have been up to 43o feet higher than now. The Ngari lakes, he says, are never found below

14,000 feet.   Those with an effluence are invariably freshwater, those without it
invariably salt.»

In his monograph, Strachey has given a good characteristic of the two famous lakes, which he calls, in Tibetan, Tso Mapham and Tso Langak or Oma Tso, i. e. I\Tilk Lake. He believes that the spur of low hills between them consists partly of alluvial material projecting from the foot of Gurla. Both have purest fresh water.' His description of the hydrographical situation of the much debated lakes is very good indeed, and Strachey clearly understood that he had to do with a periodical phenomenon.

well-established (by the explorations of Mr Vigne and subsequent surveys of Lieut. R. Young) as the chief source of the Indus — a fact which English geographers have had to rediscover for themselves within the last half century, though I find it distinctly stated in a book written by a Tibetan monk 250 years ago.

But the Indus is not the only river of West Nari; all the S part of Nari-Khorsum, and a small eastern corner of Maryul, are drained by the heads of the Indian Satadru, v. Sutluj, the chief of which, called by the Tibetans Langchen Tsangspo, i. e. Elephant River, originates in the southern part of the transverse watershed that divides Nari-Khorsum from Mangyul (the heads of the Indus occupying its northern part), and breaks through the Indian Himalaya in Upper Kanor.» Ibidem, p. 8.

I »The eastern lake Mapham is of oblong or oval shape, 15 or 16 miles long E. and W., and I I to 12 broad N. and S., making an area of i 5o square miles. It is known to have several affluents from the high snowy mountains that flank it on the N. and the S., though the English explorers, confined as yet to the W. side, have not actually crossed any of them; and one of them, from the Kangri mountains on the NE., is said to form a small fresh-water lake, called the Tso Khurgyal, shortly before its debouchure into Mapham. Its effluent runs through an opening in the hilly isthmus into the western lake: I found it a swift stream ioo feet broad and 3 deep in October; and its exit from the lake was seen by Mr J. E. Winterbottom and my brother, Richard Strachey, from a height a few furlongs off; though Moor-croft crossed this very place without finding the stream, even in August, the time of highest flood—whether from its being then dry, or from its percolating through a bar of shingle close to the lake, as asserted by some of my native informants, is not apparent.

The Western lake Langak has probably about the same area as Mapham, but an irregular shape, with a length of z o miles N. and S., and extreme breadth of 15, measured obliquely across its S. end, the N. end narrowing off to a point; at the S. end there are two or three small rocky islands, the only known instances of such in the lakes of West Nari. My brother and I have between us completed the circuit of this lake, so as to leave no doubt of its affluents and effluents; the former comprise the effluent of Mapham above mentioned, two streams from the Kangri mountains on the N. E. as large as that, and a much smaller one from the valley of Jungba in the hills on the S.E. The effluence to the Langchen river is from the point, which I crossed however in October without finding any running stream, or any marked channel for one, though the flatness of the ground, its partial inundation in shallow pools, and obvious descent of the level towards the river, entirely corroborated the native accounts of an intermittent effluence in seasons of flood. It is worthy of notice that one branch of the Jungba valley is connected with valleys draining into Gyanima of Guge; and the level of both so nearly flat, and the dividing watershed so insensible, that the depression of a few feet at this end, with an equal elevation at the N. point of the lake, would certainly turn the effluence into the Chu Kar, through the plain of Gyanima, where there now exists a small lake 5 or 6 miles long and i in extreme breadth.»