bed is straight, as well as deeper, there is every likelihood of the stream flowing on unchanged for a score of years, or more. Were another map of the river to be constructed twenty years hence, and to be compared with this which I have been enabled to execute, we should be able to perceive to what extent, and in what directions, the stream had altered its course in the interval ; and should moreover be in a position to estimate its erosive energy, and measure the mass of its alluvial deposits, as well as to infer the law which from time immemorial has governed its excavating power.
Fig. IO. GROUP OF NATIVES AT LAJLIK.
In the region where my journey upon the Tarim commenced, the current flowed at a gentle rate, the fall from Jarkent downwards being inconsiderable. I measured the velocity several times a day. During the first day's journey it amounted to 38.2 m. in the minute; and continued to decrease all the way to the confluence of the Ak-su-darja. It is self-evident, that at the period of high water the velocity is very much greater, and that, had I embarked upon my journey at that season, my progress would have been very appreciably quicker. But the autumn possessed this advantage over • the summer, that, large portions of the river-bed being exposed, I was enabled to study its conformation with greater convenience. As a rule the stream drops intermittently in the autumn, the daily decline being but trifling, as we were easily able to see by studying the sharp-cut edges of the miniature banks round the exposed silt-deposits. Although the erosive power of the current climi-
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