Soon the balloon, taking an oblique ascent, hovered over the darkened landscape, and the paling lights also disappeared. The noises of the city died away at the same time into profound silence: it was the silence of the upper heights which enveloped the air-ship now. Icléa was impressed by this extraordinary stillness, perhaps, above all, by the novelty of the situation, and clung to her rash lover's side. They mounted rapidly. The aurora borealis appeared to descend, and spread itself out under the stars, like an undulating drapery of fleecy gold and purple, overrun with electric flashes. Spero watched his instruments, and by the help of a little crystal globe filled with glow-worms, wrote down the indications corresponding to the heights attained. The balloon went up steadily. What a delight to the investigator! In a few moments he would soar to the crest of the aurora borealis; he would find an answer to the question about the aurora's height which had been asked in vain by so many philosophers, and especially by his beloved masters, the two great "psychologists and philosophers," Oersted and Ampère! Icléa's emotion had calmed itself. "Were you afraid?" asked her lover. "The balloon is safe; you need fear no accident,--everything has been provided for. We will go down in an hour; there is not a breath of wind stirring on the earth." "No," she said, while the celestial light threw over her a roseate and transparent illumination; "but it is so strange, so beautiful, so divine. It is grand for little me! I shuddered for a moment. It seems to me that I love you more than ever!" and throwing her arms about his neck, she kissed him in a long, passionate, clinging embrace. The solitary balloon was moving silently through the aerial heights, a spheroid of transparent gas enclosed in its silken envelope, whose vertical gores, joining each other at the valve on the top, could be seen from the car; the lower part of the balloon being open for the dilation of the gas.