pulsations simply depend on the quantity of the annual rainfall in the Himalaya and the Transhimalaya. After dry summers and autumns, the lake has no surplus of water to part with. After copious rainfall, its surface overflows, and a portion of its water runs out through the channel to Rakas-tal. The same climatical changes that characterise the post glacial period, are also to be observed here. Without doubt, the great curve of climatical change has hitherto proceeded towards desiccation, because, as far as I have found, no water has flowed out of Rakas-tal since I 76o. What the future can hold in store in this respect, is unknown to us. Perhaps the curve of rainfall shall again begin to rise from its drift to dessication. The oscillations in the level of water in lake Manasarovar, belong to a curve of lower order than the oscillations of Rakas-tal. The former depend on years and decades, the latter on centuries.
With the support of all this material, there is then no difficulty in proving that the periodicity is a secondary phenomenon, which does not in the least prevent the two lakes from belonging to the course of the Satlej and the river-system of the Indus. This also goes to establish that the source of the Satlej should not be sought for in any of the places formerly designated as such, but only and exclusively at the point where the largest tributary to Manasarovar, or Tage-tsangpo, is born at the front of the glaciers of Ganglung. This view even agrees with that of the Chinese and the Tibetans. It will, moreover, prove to be the only correct one in future, when these parts have been thoroughly mapped and explored.
In Vol. III, I treat the Transhimalaya and analyse in historical order all the expeditions having touched on the periphery of the unknown central parts of this system, whose wings to the East and West were comparatively well known. Desideri, Beligatti and della Penna are the first Europeans who have at all been in contact with this great and attractive orographical problem. After them followed Abbé Huc, Thomson, Hooker, Campbell, Schlagintweit, Drew, Strachey, Cunningham and the Pundits of Montgomerie and, finally, a few modern travellers, last of them Ryder, Rawling and Wood. But even more fertile is an analysis of the descriptions of the mountainland to the North of the Tsangpo, given by prominent geographers, and partly founded on Chinese documents, partly being of theoretical construction. The foremost of these geographers are d'Anville, Klaproth, Ritter, Humboldt, B. Hodgson, Richthofen, Saunders, Markham, Dutreuil de Rhins, E. T. Atkinson and, lastly, S. G. Burrard and Hayden. After having given in turn an account of each of their varying systems, of which not a single one corresponds to reality, I pass on to a description of my own journeys in the Transhimalaya, and
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