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tion of the hills takes place: the wind sweeping continu- 
ally from the surface the sand with an astonishing rapidity 
the surface of the ground lowers every moment; but the 
quantity of sand in the air increasing as quickly by suc- 
cessive waves, cannot support itself there, but falls in 
heaps, and forms a new hill, and the place which it oc- 
cupied before is level, and looks as if it had been swept. 
It is necessary to guard the eyes and mouth against the 
quantity of sand which is always flying about in the air. 
This second sahara may be, at the place where it 
must be passed; about a mile and a half wide; the trav- 
eller must take care to keep always to the east, in or- 
der to avoid being lost in the windings, which must be 
made in the middle of the hills of sand which bound 
the sight, and which shift from one spot to another so 
often, as to leave nothing to be seen but the sky and 
sand, without any mark by which our position can be 
known; even the deepest footstep in the sand of either 
man or horse disappears the moment the foot is raised. 
The immensity, the swiftness, and the everlasting 
motion of these waves disturbed the sight both of men 
and beasts, so that they are almost continually march- 
ing as if in the dark. The camel gives here a proof 
of his great superiority; his long neck, perpendicularly 
erected, removes his head from the ground and from the 
thick part of the waves; his eyes are well defended by 
thick eye-lids, largely provided with hair, and which 
he keeps half shut; the construction of his feet, broad 
and cushion-like, prevents his treading deep into the 
sand; his long legs enable him to pass the same space 
with only half the number of steps of any other animal, 
and therefore with less fatigue. These advantages give 
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