402 DKIVE OVEK THE SANDHILLS, Book II. 
If the African Sahara has been compared to the sea, 
the little Mexican desert of the Medanos may be likened 
to a lake. A body of shifting sand lies between limestone 
hills, bounded like a lake, but with a surface in waves like 
those of the ocean. Those, however, who have seen the 
snow-fields extending between the pinnacles of the Alps 
can form a still better idea of its appearance. The 
wind which has driven the sand here to form hills of 
a hundred feet in height, produces the same curves and 
hollows, and segments, as those which are seen in the snow- 
drifts of Mont Blanc and Monte Rosa, while the sharp 
peaks of the Sierra de la Rancheria and the Sierra del 
Candelario, may be well compared with the pinnacled 
heights of the Alps. 
We left the watering-place in the afternoon and reached 
the Sandhills at the commencement of night. The road 
from the spring passes first over limestone, then for a short 
distance sandstone appeared. Whether the shifting sand 
of this desert is supplied from this source, or has any other 
origin, I cannot say. On the border of the sand we left 
half our waggons, in order to give our whole mule power to 
the rest. I remained with a portion of our forces to protect 
these. The day had been hot, the night was bitterly cold, 
ice formed on our water vessels, and, with my feet deep in 
the sand, I felt exactly as if I were standing in snow. My 
feet were quite benumbed, and I feared they would be 
frost-bitten. We dared not light afire, lest it should attract 
the Indians. Even when the mules returned after mid- 
night to fetch us, a five-hours' fatiguing march scarcely 
restored warmth to my feet. The toil of this road is very 
great. With the wheels sinking into the sand as far as 
their axles, the waggons have to pass over the short but 
steep acclivities and declivities of the ground, with occa- 
