For twenty minutes they roared northward. Then, to their surprize, a vast body of water appeared against the horizon ahead.
“Lake Erie!” gasped Robert, after a moment’s reflection. “Two hundred miles in less than half an hour. Why—that’s about five hundred miles an hour! And without the aid of electric magnetization of the disk!”
“Marvelous!” exclaimed the professor, enthusiastically.
Already they were soaring over the expanse of water. On the horizon the distant Canadian shore was rapidly taking shape. Beneath them several long, slim lake craft could be discerned, crawling at what appeared, from so great a height, to be a snail’s pace. No doubt the Sphere would have presented a much more curious sight to those below had its luminous gray shell been more than a faint speck against the brilliant, cloudless sky.
It was at this juncture that Robert’s alert ears detected a subtle change in the hitherto soft whir of the gyrostats.
“What is it, Robert?” whispered Professor Palmer, as he observed Robert’s suddenly tense attitude.
“Wait!” anxiously.
Outside, the muffled roar sounded in strange contrast to the still air within. The bright sunshine streamed across the gray door in mock cheerfulness. A single captive fly buzzed drowzily against a windowpane.
These commonplace details registered on Robert’s mind indelibly in those fleeting seconds as he listened with palpitating heart for he knew not what.
Taking his cue from Robert, Professor Palmer was listening with equal intensity to the drone of the machinery upon which their lives depended. Even he could now detect the change. The drone was gradually, unmistakably, decreasing in volume. The gyrostats were stopping!