| | we saw its crest distinctly south of the two freshwater lakes at Camp XLI. Thus as the mean pass-altitude of Dungbure III I obtain 5228 m., which proves that this crest is higher than the two Koko-schili ranges and only very slightly lower than the loftiest of the Arka-tagh ranges. The corresponding value for Dungbure I is 4973 m. and for Dungbure II 5137 m. The valley which lies between them has, according to existing observations, a mean altitude of 4856 m., whereas the valley between Dungbure II and Dungbure III has an altitude of 4924 m., or almost exactly the same as Wellby's latitudinal valley. The mean altitude of the valley south of Dungbure III is 4915 m. The figure which I give for the latitudinal valley between Dungbure II and Dungdure III may be regarded as trustworthy, seeing that it is calculated from thirteen observations, for the valley is traversed in part both by my own and by Wellby's itineraries. Although I have in the foregoing discussion assumed that Wellby's route ran through one continuous main valley only, in this particular part of it it does look, I confess, as though he really travelled in two separate latitudinal valleys. This is not however apparent from his map; but the direction of the mountain-ranges, from west-north-west to east-south-east, in this region suggests that his itinerary, which just there ran due east, must have crossed over the crest of what I have called Dungbure II, and precisely in the locality where that range ought theoretically to exist Wellby travelled for two short stages due north, not with the view of seeking the shortest and easiest way across a pass, but in order that he might follow the river which flows down to the salt lake of 28th July, so that it would undoubtedly appear to cut through Dungbure II in a transverse glen. This stream has its sources in Dungbure I, the principal chain in that region. One more step towards the south and it is still possible to trace the probable west-north-west to east-south-east direction of the ranges. South of Dungbure III and separated from it by a latitudinal valley, with an altitude of 4915 m., runs a mountain-range; this is bordered on the north by that part of my route towards Tengri-nor which comes between Camp XXXIV and Camp XXXIX. Thanks to the pass-crossings, this same range can be detected on the itineraries of Dutreuil de Rhins, Littledale, my own, and Bonvalot's routes, and farther east it is probably connected with the Buka-magnä range, which is crossed by the usual road of the Mongol pilgrims by the Buka-magnä pass, at a spot where the range is considerably lower than in the part of Tibet with which we are more especially concerned. The passes known along this range lie, from west to east, at 5 12 2, 5099, 5186, and 5750 m. The last of the four is situated on Bonvalot's route and is a highly improbable figure, the altitude being undoubtedly exaggerated. The mean value is however 5289 m. South of the Buka-magnä comes the big latitudinal valley which I followed when I went down to my headquarters Camp XLIV; on the west it seems to be continuous with Dutreuil de Rhins's »Vallée des Lacs Jumeaux». These two lakes stretch from east to west and show that the valley makes a slight curve. The »Lac du Cratère», which lies immediately north of the same two lakes, may be regarded as belonging to this valley, although they are separated by a low crest. The mean of seven altitudes taken in the valley is 5022 m. Consequently this latitudinal valley lies at the same elevation as the crest of Arka-tagh I. |
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