always snorting and puffing to get rid of their obstinate tormentors.
A belt of extraordinarily regular dunes is crossed by the road. They are as much as i 3 feet high and stand Too yards apart, never running together. The intervals between them are quite free of sand, only here and there a skeleton of a dromedary being imbedded in sand. The dunes are crescent-shaped, but their points are drawn far out to leeward, and their position indicates a north-northwest wind. The whole collection of dunes is therefore moving south-south-east. Probably they are formed at some distance to the north, and are probably dissolved and disappear somewhere to the south. But just where the road runs, and where all the conditions for their construction are present, they are modelled by the wind. They are ephemeral formations which cross the desert like phantom ships. When it is calm they remain immovable as tree stumps. When it blows hard the sand whirls around them and continues its course towards south-south-east.
One of the largest stood now in the midst of the road. Therefore a path ran out to the left round the windward side of the dune. It was much worn as if the dune had not moved appreciably for some time. But 20 yards outside this path there was another which showed that the dune had advanced from this direction. It only needed a summer's storms to sweep the sand-hill out of the way.
Another dune was crossed by the telegraph line between two posts. The highest part of the rounded crest would have come in contact with the wires if a temporary support had not been set up in the middle of the ridge to raise them.
We crossed three strips of dunes, and they seemed to start from three gaps between small hills to the north of our road. They seemed to be so far independent of the configuration that they crossed two erosion furrows 6 feet deep without any marked break. There was a slight breeze, and now and then a close eddy of yellow sand glided like a spectre to the east-north-east. Such a vortex remained for a moment still, humming on the middle of the crest of a dune and sucking up the sand like a pump
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