In the preceding chapters I have tried to give a resume of the history of exploration in the region of the Manasarovar and the Rakas-tal, and I have especially tried to bring together as many records as possible about the connection between the lakes and between the western lake and the Satlej. In the latter respect the result has not been encouraging. For, as a rule, the earlier records are either unreliable, or, even if they seem to be reliable as regards facts, they do not allow us to fix the date of the observations. The only exception from this is the Lama survey. Then follows a century with uncertain information, and only with MOOR-CROFT do we enter upon solid ground.
The problem is, however, one of very great interest. In itself it is not of great importance whether water at a certain period flowed out of the lakes or not. Only on account of the bright light it spreads over the oscillations in the last, or present, climatic period, does the question become important. But even during the last century the records are very few, and at any rate insufficient to make it possible to follow the periodicity of the curve. This should not be surprising, for it may even be difficult to arrive at reliable conclusions when comparing old maps and descriptions of lakes and rivers in Europe with the present state of things. How much more difficult must it then be to study the oscillations in a couple of Tibetan lakes, which only a hundred years ago were visited by the first scientifically trained European, and since his time have been seen by only a very few reliable visitors.
And still these two lakes present us with a most excellent and sensitive instrument for measuring the changes in the climate, especially the precipitation. The instrument is there, but its records have only in a very few cases been read and understood. With great patience and trouble the glacial geologists have tried to interpret the silent story told by the old • front moraines of Himalayan glaciers to find out the advance and retreat of the ice streams. The general result at which they have arrived may be expressed in the following words by Guy E. PILGRIM :
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