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transition, passing over, change. 3mar
shals, arranges, sets in their proper places. germ, bud.
AN EPISTLE TO JOSEPH HILL.
DEAR Joseph-five-and-twenty years ago—
Lest he should trespass, begg'd to go abroad.
"For what? "An' please you, sir, to see a friend."—
A friend!" Horatio cried, and seem'd to start
"Yea, marry shalt thou, and with all my heart.
I knew the man, and knew his nature mild,
But somewhat at that moment pinch'd him close,
Perhaps, his confidence just then betray'd,
His grief might prompt him with the speech he made ;
Some few, that I have known in days of old,
1 Terence, a famous Roman poet who wrote plays. constant change, like the waves of the sea. 3 morose, peevish, of ill humour. moralise, to write on moral subjects; here, to talk like a tiresome preacher. 5 verbosely, with too many words. triple, threefold, consisting of England, Scotland, and Ireland.
THE 1 phenomenon of the mirage excites in the traveller of the deserts those 2 alternations of hope and disappointment which add to the miseries of his actual situation. He sees before him lakes of water, which are gone the instant he arrives at the spot where he fancied they offered their refreshment to his feverish lips. The Arabs are familiar with this remarkable appearance, and they are seldom deceived by it; although if the mirage and a real stream could be seen at the same time, it would be difficult to distinguish the reality from the delusion. The guides of the 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. 3 Burckhardt has described the mirage with his usual felicity: "During the whole day's march we were surrounded on all sides by lakes of mirage, called by the Arabs, Serab. Its colour was of the purest 5 azure, and so clear that the shadows of the mountains, which bordered the horizon, were reflected in it with the greatest precision, and the delusion of its being a sheet of water was thus rendered 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 great 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 often 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."
The mirage is caused by the extraordinary refraction
which the rays of the sun undergo in passing through masses of air in contact with a surface greatly heated. 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 for him to find a shade beneath its boughs. He quickens his pace, hoping to enjoy half an hour of refreshing coolness before his camels shall have passed. 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. When the sun gleams on the sand-hills, they appear at an immense distance; the traveller hopes that his camels may be spared the pain of crossing these slippery ascents; when, in a few minutes, he is close upon them, and sees a man or a camel within a stone's throw, toiling to the top.
As the sun ascends towards the zenith, and the earth and the currents of the air assume different temperatures, the phenomena of the mirage present numerous modifications. Humboldt states, that, in the plains of South America, where the air is very dry, he often saw the images of troops of wild oxen suspended in the air, long before the eye could see the oxen themselves; and the small currents of air were of such a variable temperature, that the legs of some appeared to rest upon the ground, while others were elevated above it. In Arabia, 1o 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; they disappear at intervals without the traveller being able to decide upon the true forms of the objects, which are probably little sand-hills, beyond the ordinary range of vision. All these phenomena are modifications of the