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.

The dusky brightness that falls from the stars, of which Corneille speaks, would have been sufficient without the gleams from the aurora borealis to enable them to distinguish the whole of the aerial skiff. The car was hung to the net which enveloped the silken vessel by strong ropes tied to the basket-work and interlaced under the feet of the aeronauts. The silence was impressively solemn; the beating of their hearts could have been heard. They were sailing at a height of five thousand metres, with an unaccustomed gravity; the upper wind was carrying them along without the faintest breath being felt in the car, for the balloon floated in the moving air like a simple bubble,—motionless, except as the current carried it along. Our travellers—sole inhabitants of these lofty regions, in full enjoyment of the exquisite elation which aeronauts know when once they have breathed that rare and sublimated atmosphere—looked down upon the realms below, forgetful of all earthly cares and associations, in the silence of their vast isolation. But they appreciated and enjoyed their unique situation more than any of those who had preceded them, for they added to the pleasures of an aerial voyage the rapture of their own happiness. They spoke in low tones, as if afraid of being overheard by the angels, and of seeing the magic charm dissolved which held them so near to heaven.... Sometimes sudden flashes came to them,—gleams from the aurora borealis; then darkness, deeper and more unfathomable than before, reigned again.

They were floating thus in their starry dream when a quick, shrill noise, like that of a new whistle, sounded in their ears. They listened, leaned far out over the car, and listened again. The noise did not come from the earth. Was it an electrical blast from the aurora borealis? Was it the hiss of some magnetic storm in the upper air? Lightning coming from the depths of space flashed about them and disappeared. They listened breathlessly again. The sound was quite close to them.... It was the gas escaping from the balloon! Either the valve had partly opened of itself, or they had pressed upon the connecting rope while incautiously moving about in the car; at all events, the gas was escaping.

Spero at once detected the cause of the disquieting noise, and it terrified him, for it was impossible to close the valve again. He examined the barometer, which had begun slowly to rise, while the balloon was beginning to descend. The fall, slow at first, but inevitable, would increase in mathematical proportion. Trying to fathom the abyss below them, he saw the flames of the aurora borealis reflected in the water of an immense lake. The balloon was now descending with great rapidity, and was not more than three thousand metres from the ground. Outwardly calm, but fully conscious of the certain and impending peril, the unfortunate aeronaut threw out one after the other the two sacks left for ballast, then the maps, the instruments, the anchor, and emptied the car; but this lightening of the weight was not enough, and served only to slacken momentarily their accelerated speed. The balloon was now descending, or rather falling, at a tremendous rate, and was but a few hundred metres above the lake. Strong wind-currents blew up and down and whistled in their ears.