Our aëronauts had scarcely gone a distance of fifteen miles, having expended, as on the preceding day, one hundred and thirty-five cubic feet of gas to feed the cylinder, and two pints of water out of the remaining eight had been sacrificed to the demands of intense thirst. The night passed quietly—too quietly, indeed, but the doctor did not sleep! CHAPTER TWENTY-FIFTH. A Little Philosophy.—A Cloud on the Horizon.—In the Midst of a Fog.—The Strange Balloon.—An Exact View of the Victoria.—The Palm-Trees.—Traces of a Caravan.—The Well in the Midst of the Desert. On the morrow, there was the same purity of sky, the same stillness of the atmosphere. The balloon rose to an elevation of five hundred feet, but it had scarcely changed its position to the westward in any perceptible degree. “We are right in the open desert,” said the doctor. “Look at that vast reach of sand! What a strange spectacle! What a singular arrangement of nature! Why should there be, in one place, such extreme luxuriance of vegetation yonder, and here, this extreme aridity, and that in the same latitude, and under the same rays of the sun?” “The why concerns me but little,” answered Kennedy, “the reason interests me less than the fact. The thing is so; that’s the important part of it!” “Oh, it is well to philosophize a little, Dick; it does no harm.” “Let us philosophize, then, if you will; we have time enough before us; we are hardly moving; the wind is afraid to blow; it sleeps.” “That will not last forever,” put in Joe; “I think I see some banks of clouds in the east.” “Joe’s right!” said the doctor, after he had taken a look. “Good!” said Kennedy; “now for our clouds, with a fine rain, and a fresh wind to dash it into our faces!” “Well, we’ll see, Dick, we’ll see!” “But this is Friday, master, and I’m afraid of Fridays!” “Well, I hope that this very day you’ll get over those notions.” “I hope so, master, too. Whew!” he added, mopping his face, “heat’s a good thing, especially in winter, but in summer it don’t do to take too much of it.” “Don’t you fear the effect of the sun’s heat on our balloon?” asked Kennedy, addressing the doctor. “No! the gutta-percha coating resists much higher temperatures than even this. With my spiral I have subjected it inside to as much as one hundred and fifty-eight degrees sometimes, and the covering does not appear to have suffered.” “A cloud! a real cloud!” shouted Joe at this moment, for that piercing eyesight of his beat all the glasses. And, in fact, a thick bank of vapor, now quite distinct, could be seen slowly emerging above the horizon. It appeared to be very deep, and, as it were, puffed out. It was, in reality, a conglomeration of smaller clouds. The latter invariably retained their original formation, and from this circumstance the doctor concluded that there was no current of air in their collected mass.