true, not be sufficient to warrant us in positing the existence of a continuous range; but we are also justified in presupposing, almost of necessity, the existence of at least one important water-dividing ridge between Nain Singh's lakes and the Tsangpo. We may further take it that the most north-easterly of the head-feeders of the Indus likewise gathers its waters out of this unknown and mysterious range.
Seeing now that our knowledge of Tibet is so defective, it would be, as the reader will readily see, and as I have already mentioned, a rather thankless task, to seek to unravel its vast concourse of mountains: although the attempt itself would perhaps not be without its interest, the result would be practically worthless. On my general map on the scale of i : I ,000,000 I have considered it inadvisable to enter anything except absolute facts, 1. e. the fragments of the various ranges which have been visited by different travellers, paying no regard to the mutual connections of the ranges themselves either to east or to west. In this respect the map will afford ample opportunity to the speculative ingenuity of geographers, but it will be documentary evidence of the state of our existing knowledge about the mountains of Tibet. However the time will come when it will be completed by fresh itineraries, and then the several fragmentary sections will be linked together into continuous ranges and the dubious patches will grow smaller and smaller in area, until finally they disappear altogether. The geological structure, of which we have as yet but the faintest idea, will likewise in due time be elucidated, and simultaneously therewith the structural conformation of Tibet will be scientifically explained. Had all the travellers who have traversed eastern Tibet meridionally carried with them specimens of rock from the various ranges which they have crossed over, we should possibly have thereby been put in possession of an additional means of disentangling the mutual relations of the several ranges and consequently their connections one with another.
Still for those who have travelled through Tibet it will not be difficult to form an idea of what the map will look like which some day will represent the mountains of that part of the world with the same accuracy as the maps do, for instance, the mountains of Persia, the Tien-schan, or the Nan-schan. Upon studying the admirable new map of »Innerasien» in Slider's Hana'allas we see that the mountains in the west of the country, between 74° and 79° E. long., are fairly well known, and there appear no white patches at all, but the map is entirely covered with the differential signs of surface features. This will eventually be the case too with the middle and eastern parts : there too there will some day be no white patches left, but they will be filled with the conventional representations of mountains, valleys, lakes, and rivers. It is the very fact of there being so many white patches on the map in question which forces upon one nolcns volens the impression, that the whole of the interior of Tibet is practically a flat plateau country, stretching from the Kwen-lun to the Himalaya, and it is easy to forget, that this is due simply to the fact that the great lacuna have not yet been filled up. It is also conceivable, that our future map of Tibet will not only be an object of beauty to the eye, but will also present an astonishing picture of a fantastic and sublime reality — the gigantic mountain-ranges which stretch across that country, with the minor ranges lying between them. The relief will stand out sharply and boldly in the east and west, where lie the deeply trenched valleys of
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