cted to navigating streams and rivers.

On quitting Tchong-Wei we passed the Great Wall, which is wholly composed
of uncemented stones, placed one on top of the other; and we re-entered
Tartary, for a few days, in the kingdom of the Alechan. More than once
the Mongol Lamas had depicted in frightful colours the horrors of the
Alechan mountains. We were now in a position to see with our own eyes
that the reality exceeds all description of this frightful district. The
Alechans are a long chain of mountains, wholly composed of moving sand,
so fine, that when you touch it, it seems to flow through your finger
like a liquid. It were superfluous to add that, amid these gigantic
accumulations of sand, you do not find anywhere the least trace of
vegetation. The monotonous aspect of these immense sands is only
relieved by the vestiges of a small insect, that, in its capricious and
fantastical sports, describes a thousand arabesques on the moving mass,
which is so smooth and fine, that you can trace upon it the meanderings
of an ant. In crossing these mountains, we experienced inexpressible
labour and difficulty. At each step our camels sank up to the knees; and
it was only by leaps that they could advance. The horses underwent still
greater difficulties, their hoofs having less purchase on the sand than
the large feet of the camels. As for ourselves, forced to walk, we had
to keep constant watch that we did not fall from the top of these
mountains, which seemed to disappear under our feet, into the Yellow
River, whose waters flowed beneath us. Fortunately, the weather was
calm. If the wind had blown, we should certainly have been swallowed up
and buried alive in avalanches of sand. The Alechan mountains themselves
appear to have been formed by the sand which the north wind incessantly
sweeps before it from the Chamo, or Great Desert of Gobi. The Yellow
River arrests these sandy inundations, and thus preserves the province of
Kan-Sou from their destructive assaults. It is to the great quantity of
sand that falls into it from the Alechan mountains that this river owes
the yellow colour which has given to it its name _Hoang-Ho_ (Yellow
River). Above the Alechan mountains its waters are clear and limpid.

By degrees, hills succeeded to mountains, the sand heaps imperceptibly
diminished, and towards the close of the day we arrived at the village of
Ever-Flowing Waters (_Tchang-Lieou-Chouy_). Here we found, amidst those