At a later occasion I Dr. Longstaff has made a very able and interesting historical analysis of the changes he supposes have taken place with the source of the Satlej. Formerly, he says, the river from Maryum-la and viii Gunchu-tso was the source of the Satlej. So we regarded the Tokchen river, with a course of about 3o miles, as the prime source.» Now, so far as this question has not been thoroughly examined by anybody at the very place, this argument has no value whatever. For, the fact that Alexander Gerard, who never visited the place, creates the salt lake of Gunchu-tso as the source of the Satlej, is no argument. Then, talking of the Tage-tsangpo, he says : »another link in the chain is giving way between Rakastal and Tirthapuri, and when this process is complete, and the Manasarovar basin is quite cut off from the Sutlej, another source will have to be found.» As I have shown in the previous chapter this view is perfectly correct: as soon as the lakes are completely cut off from the Satlej, — but not a day earlier! — another source will be found, probably the Darma-yankti. So, as he agrees with my view in this, the cardinal point of the whole problem, the rest of his discussion is superfluous. But the conclusion, at which he arrives, is surprising: --Indeed, if we accept Dr. Sven Hedin's own definition, we cannot even now locate with certainty the genetic source of the Sutlej.» But, in the preceding passage, he had accepted my definition. So long as the lake basin is not completely cut off, it must belong to the Satlej, and as soon as it is quite cut off, it will have to be regarded as a self-contained (»abflussloses») basin with salt lakes in its lowest part, of the same kind as those which are so very common on the highlands of Chang-tang. This stage in the development has not yet entered, and until it comes we have to content ourselves with the actual state of things and to describe and define the physico-geographical phenomena as they are and not as they may happen to become in a near or distant future, if one or the other eventuality should take place. For of the present state of things we know, of the future we can only guess. Prognostications are always allowed, but compared with observations they have no value at all.
Captain Rawling asks: What is a source ?2 And answers: > I maintain, though it is possible I am in error, that it is the longest visible branch of a river system, and, if there are two branches of equal length, then that which carries the most water at its greatest flood.» This is not the place to discuss the definition of a source. Professor SUPAN 3 shows that no general law can answer the question : where is the source ? Every river system has a character of its own. If really, which is
I Geographical Journal, Vol. XXXIII, April 1909, p. 427.
2 Geographical Journal, Vol. XXXIII, April 1909, p. 424.
3 In his Grundzüge der Physischen Erdkunde, Leipzig 1908 p. 705, SUPAN says that E. \rIs0TZKI is right, (Hauptfluss und Nebenfluss, Stettin 1889) »wenn er den Satz aufstellt, dass kein einzelnes Moment, wie Länge, Wassermenge, Breite, Tiefe, Farbe, Richtung u. dergl. ausreiche, um in jedem einzelnen Falle mit Bestimmtheit Haupt- und Nebenfluss zu unterscheiden, sondern dass man das ganze Stromsystem in allen seinen Beziehungen betrachten müsse; nur ist damit keine exakte Regel gegeben, und der Natur der Sache nach kann eine solche auch nicht gegeben werden. Denn ausserordentlich
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