"Are you sure, boy? Aren't we dreaming?" he asked in a low tone.

"It's going like clock-work, as sure as you're born," the lad answered. "I think your falling down shook it up and started it. That was all it wanted."

The inventor got up slowly, first upon his knees, at last to his feet, never once taking his eyes from the beautiful engine. He went close to it, and put out his hand, till he felt the air thrown off by the wheel, and he gently touched the smooth, swift-turning rim with one finger, incredulous still.

"There's no doubt about it," he said at last, yielding to the evidence of touch and sight. "It works, and it works to perfection. If it doesn't stop soon, it will go on for twenty-four hours!"

Almost as much overcome by joy as he had been by despair, he let himself sink into his seat.

"Get me that tea-bottle," he said unsteadily. "Quick! I feel as if I were going to faint again!"

The draught he swallowed steadied his nerves, and then he sat a long time quite silent in his unutterable satisfaction, and Newton stood beside him watching the moving levers, the rising and sinking valve rods, and the steadily whirling wheel.

"She did it, my boy," Overholt said at last, very softly. "Your mother did it! Without her help the Motor would have been broken up for old metal three weeks ago."

"It's something like a Christmas present," Newton answered. "But then I always said she wouldn't let you give it up. Do you know, father, when you fell just now, I thought you were dead, you looked just awful! And it was quite a long time before I saw that the Motor was moving. And then, when I did see it, and thought you were dead—well, I can't tell you—"

"Poor little chap! But it's all right now, my boy, and I haven't spoilt your Christmas, after all!"