A no less remarkable phenomenon is the Mirage, _i. e._ the appearance of seas and rivers, supposed to be observed in the middle of the desert, but which, in fact, are only represented to the eye in this deceptive manner by a rising vapour, and the reflection of the sun. The sensation is indescribable, of descrying at the distance large rivers and lakes, after having travelled for several tedious days through the desert, where nothing is to be seen but sand and heaven, as but water and sky on the high seas, and at a time, moreover, when the traveller is longing after water. We wish for wings, to be able to reach the element of which we have been so long deprived as quickly as possible. We delight in the idea of invigorating the exhausted and enervated body by a bath, and the eye is continually bent upon this pleasing object. But what is our disappointment,—how are the spirits depressed,—when, notwithstanding these ardent wishes, on our approach, the lakes and rivers, which we had discerned at the distance, are resolved, in the literal sense of the word, into thin air; and when we find, in lieu of water, the sand as hot and dry as in the place we had just left! When the traveller has frequently observed this phenomenon, and accustomed himself to it, he will be pleased with the image which diverts his eye, and will look upon it as a variation in the scene. These aerial phenomena are called in the country, Bahr-el-Ghazal, or Gazelle Rivers, probably because, like these animals, they disappear as soon as seen. The rains begin in the month of June, and terminate with the month of October. Those who have not spent this season in a tropical country, can form no idea of the showers which then drench the earth. The storms generally arise in the east or in the south. A small black cloud is, at first, perceived on the horizon, which increases as it approaches, spreads in a few minutes, with incredible velocity, over the whole region, and then descends. A fearful storm now rages: flash upon flash, and peal succeeding peal, the lightning illumines the whole heavens, and the thunder rolls most fearfully, as if the sky were about to open and the earth to burst; streams of water pour down with violence, which the soil is incapable of imbibing, and torrents are thus formed, destined, however, soon to be lost in the sands. Showers of this description generally last over one quarter of an hour, seldom for a longer period, and very rarely, indeed, are they repeated on the same day. They remit frequently during two, three, or even six days, and this is the most unhealthy, and even dangerous time both for strangers and natives; but it is admitted by general consent, that those of white colour suffer more than the blacks. As if by magic, Nature now awakes from her sleep of death; for, immediately after the first shower, the earth is clad with verdure, the trees shoot forth fresh buds, and a vesture of flowers is spread over the whole country.