They laughed. Both, somehow, felt relieved afterward. Henry had furnished a welcome diversion. The former nervous tension was broken. “Well, so long, old man,” Robert called out the window, as he prepared to close it. “Give my regards to Saint Peter,” shouted Henry. “Cheerful cuss,” contributed the professor, as the heavy glass slammed shut. Robert stopped the gyrostats. A deep silence reigned within the heavy walls as he examined carefully the delicate machinery upon which so much depended. Then he pulled the lever, setting them in motion again. Their steady purr was a relief from the oppressive silence. Professor Palmer’s keen eyes followed him as he moved about. Robert’s excitement of the previous minutes was forgotten as he expertly, almost lovingly, ran his eyes over every detail of the perfect, whirring machinery, most of which his father had produced. His throat contracted strangely as his thoughts dwelt for a moment on his beloved parent. His mother he could scarcely remember, for she had died when he was but a baby of three years. But his father had been his constant companion--his pal. What would he not have given to have him standing by him at this moment, on the eve of his triumph, of the realization of his dreams! Being a shrewd judge of human nature, the professor rightly guessed his thoughts at that moment. A suspicious moisture in Robert’s eyes confirmed his guess. Robert’s next move was to adjust the direction of the disk’s covered face toward the zenith. The gyrostats were revolving smoothly. With bated breath, he again pushed the button which partly bared the disk. The _Sphere_ gave a slight lurch. This was followed by a sensation like that felt in an elevator rising suddenly. A faint shout from below. With one impulse Robert’s and the professor’s glances swept eagerly through the ports. There they saw just what they had expected to see; but the actuality affected them curiously. Oddly enough, they had subconsciously expected till the last moment that the _Sphere_ would fail. The landscape seemed to be dropping from under them. Even the horizon was receding alarmingly. * * * * * Robert’s hand shot out to the control board, closing the disk’s surface. A slight tremor evidenced the abrupt cessation of the disk’s pull. “Six thousand feet,” read Professor Palmer from the altimeter. Robert joined him. A few minutes later it registered seven thousand. They were still rising, but not nearly so rapidly as before. The closing of the disk had checked their speed at once. “A little more and I’d have boosted her right off the earth,” said Robert, breathlessly. “I’ll have to use the disk more sparingly on ordinary sight-seeing excursions hereafter.” “You had it opened only to first power, too, hadn’t you?”