61. THE MIRAGE.

The delusive mirage excites, in the pilgrim of the desert, hope which, followed by disappointment, adds to the real miseries of his situation. He sees before him lakes of water, which are gone the moment he reaches the spot where he expected to find refreshment. The Arabs are familiar with this remarkable appearance, and are seldom deceived by it, although if the mirage and a real lake could be seen at the same time, it would be difficult to distinguish the reality from the delusion. The guides of a European traveller often amuse themselves by calling to him that water is in sight, when they are upon the most thirsty spots of a sandy or gravelly plain.

Burckhardt has described the mirage with his usual felicity:-" During the whole day's march we were surrounded by lakes of mirage, called by the Arabs serab. Its colour was of the purest azure, and so clear that the shadows of the mountains, which bordered the horizon, were reflected in it with the greatest minuteness, and the delusion of its being a sheet of water was thus rendered still more perfect. I had often seen the mirage in Syria and Egypt, but always found it of a whitish colour, rather resembling a morning mist, seldom lying steady on the plain, but in continual vibration; but here it was very different, and had the most perfect resemblance to water.

The dryness of the air and earth in this desert may be the cause of the difference. The appearance of water approached also much nearer than in Syria and

Egypt, being not more than two hundred paces from us; whereas I had never seen it before at a distance of less than half a mile. There were at one time about a dozen of these false lakes around us, each separated from the other, and for the most part in the low grounds.”

Dr. Clarke gives the following description of this phenomenon :-" Here (at the village of Atko) we procured asses for our party, and setting out for Rosetta, began to recross the desert, appearing like an ocean of sand, but flatter and firmer as to its surface than before. The Arabs, uttering their harsh, guttural language, ran chattering by our side, until some of them calling out 'Raschid,' we perceived its domes and turrets, apparently upon the opposite side of an immense lake or sea, that covered all the intervening space between us and the city.

"Not having at the time any doubt as to the certainty of its being water, and seeing the tall minarets and buildings of Rosetta, with all its groves of dates and sycamores, as perfectly reflected by it as by a mirror, insomuch that the minutest detail of the architecture and of the trees might have been thence delineated, I applied to the Arabs to be informed in what manner we were to pass the water. Our interpreter, though a Greek, and therefore likely to have been informed of such a phenomenon, was as fully convinced as any of us that we were drawing near to the water's edge, and became indignant when the Arabs maintained that within an hour we should reach Rosetta by crossing the sands in the direct line

we were then pursuing, and that there was no water. 'What!' said he; 'do you suppose me to be an idiot, to be persuaded contrary to the evidence of my senses?'

"The Arabs, smiling, soon pacified him, and completely astonished the whole party by desiring us to look back at the desert we had already passed, where we beheld a precisely similar appearance. It was, in fact, the mirage, a prodigy to which all of us were then strangers, although it afterwards became more familiar."

These atmospheric delusions are not confined to the appearance of water in the desert. The traveller, fainting beneath a burning sun, sees a tree in the distance, sufficiently large to afford him shade beneath its boughs. He quickens his pace, hoping to enjoy half an hour of refreshing coolness. The tree is really a miserable shrub that does not afford shade enough to shelter one of his hands. This magnifying of objects is produced by the slight vapour which rises when the heat is greatest.

Humboldt states that in the plains of South America, where the air is very dry, he often saw images of troops of wild oxen suspended in the air, long before the eye could see the oxen themselves; and the currents of air were of such variable temperature that the legs of some appeared to rest on the ground, while others were elevated above it. In Arabia, Niebuhr observed the image of an animal reversed before he saw the direct image. Sometimes towers and large masses of apparent buildings are seen upon the horizon, which disappear at intervals without

the traveller being able to decide upon the true forms of the objects, which are probably little sandhills beyond the ordinary range of vision. All these phenomena

are modifications of the mirage, though the name is generally applied to the unreal lakes of the desert. The same appearance is often seen, when the sun shines, upon the extensive flat sand on the shores of the Bristol Channel, in Somersetshire, and probably on the seashore in other parts of England.

Mr. Belzoni speaks of the mirage in the following terms: It generally appears like a still lake, so unmoved by the wind that everything above is to be seen most distinctly reflected by it. If the wind agitates 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 apparent water seems less united and less deep, for the eyes look down upon it. There is not thickness enough in the vapour on 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, 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 difference in the appearance of the mirage. On approaching it, it becomes thinner, and appears as if agitated by the wind. It gradually vanishes as the traveller approaches, and at last entirely disappears.'

From the Fourth Book of the Christian Knowledge Society.

62. A COMBAT IN THE DESERT.

As the Knight of the Couchant Leopard continued to fix his eyes attentively on the yet distant cluster of palm trees, it seemed to him as if some object was moving amongst them and beside them. The distant form separated itself from the trees, which partly hid its motions, and advanced towards the knight with a speed which soon showed a mounted horseman, whom his turban, long spear, and green caftan floating in the wind, on his nearer approach, showed to be a Saracen cavalier.

In the desert," saith an Eastern proverb, "no man meets a friend." The Crusader was totally indifferent whether the infidel, who now approached on his gallant barb as if borne on the wings of an eagle, came as friend or foe; perhaps, as a vowed champion of the Cross, he might rather have preferred the latter. He disengaged his lance from his saddle, seized it with his right hand, placed it in rest with its point half elevated, gathered up the reins in the left, waked his horse's mettle with the spur, and prepared to encounter the stranger with the calm self-confidence belonging to the victor in many contests.

The Saracen came on at the speedy gallop of an Arab horseman, managing his steed more by his limbs and the inflection of his body than by any use of the reins, which hung loose in his left hand; so that he was enabled to wield the light, round buckler of the skin of the rhinoceros, ornamented with silver loops, which he wore on his arm, swinging