“With this difference, however, my dear Dick, that our wings are unhurt, and I hope that we shall be able to use them again.” “Ah! wind! wind!” exclaimed Joe; “enough to carry us to a stream or a well, and we’ll be all right. We have provisions enough, and, with water, we could wait a month without suffering; but thirst is a cruel thing!” It was not thirst alone, but the unchanging sight of the desert, that fatigued the mind. There was not a variation in the surface of the soil, not a hillock of sand, not a pebble, to relieve the gaze. This unbroken level discouraged the beholder, and gave him that kind of malady called the “desert-sickness.” The impassible monotony of the arid blue sky, and the vast yellow expanse of the desert-sand, at length produced a sensation of terror. In this inflamed atmosphere the heat appeared to vibrate as it does above a blazing hearth, while the mind grew desperate in contemplating the limitless calm, and could see no reason why the thing should ever end, since immensity is a species of eternity. Thus, at last, our hapless travellers, deprived of water in this torrid heat, began to feel symptoms of mental disorder. Their eyes swelled in their sockets, and their gaze became confused. When night came on, the doctor determined to combat this alarming tendency by rapid walking. His idea was to pace the sandy plain for a few hours, not in search of any thing, but simply for exercise. “Come along!” he said to his companions; “believe me, it will do you good.” “Out of the question!” said Kennedy; “I could not walk a step.” “And I,” said Joe, “would rather sleep!” “But sleep, or even rest, would be dangerous to you, my friends; you must react against this tendency to stupor. Come with me!” But the doctor could do nothing with them, and, therefore, set off alone, amid the starry clearness of the night. The first few steps he took were painful, for they were the steps of an enfeebled man quite out of practice in walking. However, he quickly saw that the exercise would be beneficial to him, and pushed on several miles to the westward. Once in rapid motion, he felt his spirits greatly cheered, when, suddenly, a vertigo came over him; he seemed to be poised on the edge of an abyss; his knees bent under him; the vast solitude struck terror to his heart; he found himself the minute mathematical point, the centre of an infinite circumference, that is to say—a nothing! The balloon had disappeared entirely in the deepening gloom. The doctor, cool, impassible, reckless explorer that he was, felt himself at last seized with a nameless dread. He strove to retrace his steps, but in vain. He called aloud. Not even an echo replied, and his voice died out in the empty vastness of surrounding space, like a pebble cast into a bottomless gulf; then, down he sank, fainting, on the sand, alone, amid the eternal silence of the desert.