over it, in its calm waters.  The soldiers rushed towards the place, frantic with joy, but when they got there they found nothing but the hot sands.  Again they saw the lake at a distance, and made another headlong rush, only to be again disappointed.  This happened frequently, until the men were in despair, and imagined that some demon was tormenting them.  But there happened to be with this army a wise man, who did not trust entirely to his own eyes, and although he saw exactly what the others did, he did not believe that there was anything there but air.  He set to work to investigate it, and found out that the whole thing was an illusion—­it was the reflection of the gardens and villages that were on the river Nile, thrown up into the air, like the ships the sailors saw, only in the clear atmosphere of Egypt these images are projected to a long distance.  And demons had nothing whatever to do with it.

People used to believe in a fairy called Fata Morgana.  Wonderful things were said of her, and her dominions were in the air, where she had large cities which she sometimes amused herself by turning into a variety of shapes.  The cities were often seen by dwellers on the Mediterranean sea-coast.  Sometimes one of them would be like an earthly city, with houses and churches, and nearly always with a background of mountains.  In a moment it would change into a confused mass of long colonnades, lofty towers, and battlements waving with flags, and then the mountains reeling and falling, a long row of windows would appear glowing with rainbow colors, and perhaps, in another instant, all this would be swept away, and nothing be seen but gloomy cypress trees.

[Illustration]

These things can be seen now occasionally, as of old, but they are no longer in Fairyland.  Now we know that they are the images of cities and mountains on the coast, and the reason they assume these fantastic forms is that the layers of air through which the rays of light pass are curved and irregular.

[Illustration]

A gigantic figure haunts the Vosges Mountains, known by the name of “The Spectre of the Brocken.”  The ignorant peasants were, in former times, in great fear of it, thinking it a supernatural being, and fancying that it brought upon them all manner of evil.  And it must be confessed it was a fearful sight to behold suddenly upon the summit of a lofty mountain an immense giant, sometimes pointing in a threatening attitude to a village below, as if dooming it to destruction; sometimes with arms upraised, as if invoking ruin upon all the country; and sometimes stalking along with such tremendous strides as to make but one step from peak to peak; often dwarfing himself to nothingness, and again stretching up until his head is in the clouds, then disappearing entirely for a moment, only to reappear more formidable than before.