From Belzoni's Narrative.

"This phenomenon is often described by travellers, who assert having been deceived by it, as at a distance it appears to them like water. This is certainly the fact, and I must confess that I have been deceived myself, even after I was aware of it. The perfect resemblance to water, and the strong desire for this element, made me conclude, in spite of all my caution not to be deceived, that it was really water I saw. It generally appears like a still lake, so unmoved by the wind, that every thing above it. is to be seen most distinctly reflected, which is the principal cause of the deception. If the wind agitate any of the plants that rise above the horizon of the mirage, the motion is seen perfectly at a great distance. If the traveller stands elevated much above the mirage, the water seems less united and less deep, for, as the eyes look down upon it, there is not thickness enough in the vapour of the surface of the ground to conceal the earth from the sight; but if the traveller be on a level with the horizon of the mirage, he cannot see through it, so that it appears to him clear water. By putting my head first to the ground, and then mounting a camel, the height of which from the ground might have been ten feet at the most, I found a great differ-ence in the appearance of the mirage. On approaching it, it becomes thinner, and appears as if agitated by the wind, like a field of ripe corn. It gradually vanishes as the traveller approaches, and at last entirely disappears when he is on the spot."