"Watch the hand of the speed indicator, boys," directed Professor Roumann, "while Professor Henderson and I manipulate the motor. Call out the figures to us, for we must keep our eyes on the valves." Slowly the speed indicator hand, which was like that of an automobile speedometer, swept over the dial. "Fifty miles a second," read off Mark. The two professors shoved the levers over still more. "Seventy-five," called Jack. "Give it a little more of the positive current," directed Mr. Roumann. "Ninety miles a second," read Mark a few moments later. "We are creeping up, but we have not yet equalled our former speed," spoke Mr. Henderson. The motor was fairly whining now, as if in protest. "One hundred and five miles," announced Jack. "Ha! That's some better!" ejaculated the German. "I think we shall do it." Once more he advanced the speed lever a notch. "One hundred and thirty!" fairly shouted Mark. "We are beating all records!" "And we will go still farther beyond them!" cried Mr. Roumann. "Watch the gauge, boys!" To the last notch went the speed handle. There was a sharp crackling, snapping sound, as if the metal of which the motor was composed was strained to the utmost. Yet it held together. The hand of the dial quivered. It hung on the one hundred and thirty mark for a second, as if not wanting to leave it, and then the steel pointer swept slowly on in a circle, past point after point. "One hundred and thirty-five--one hundred and forty," whispered Jack, as if afraid to speak aloud. The two professors did not look up from the motor. They looked at the oil and lubricating cups. Already the main shaft was smoking with the heat of friction. "Look! look!" whispered Mark hoarsely. "One hundred and fifty-three miles a second!" exclaimed Jack. "You've done it, Professor Roumann!" "Yes, I have," spoke the German, with a sigh of satisfaction. "That is faster than mortal man ever travelled before, and I think no one will ever equal our speed. We have broken all records--even our own. Now I will slow down, but we must do it gradually, so as not to strain the machinery." He slipped back the speed lever, notch by notch. The hand of the dial began receding, but it still marked one hundred and twenty miles a second. Suddenly, above the roar and hum of the motor, there sounded the voice of Andy. "Professor!" he shouted. "We're heading right toward a big, black stone! Is that the moon?" "The moon? No, we are not half way there," said Mr. Henderson. "Are you sure, Andy?" "Sure? Yes! I saw it from the window in the pilot-house. We are shooting right toward it." "Look to the motor, and I'll see what it is," directed Mr. Henderson to his friend. Followed by the boys, he hurried to the steering tower. His worst fears were confirmed.