"What happened?" cried Jackson to Tom, as he leaned forward in his seat which was in the rear of the young inventor's.
"Don't know, exactly," was the answer, as Tom quickly shifted the rudders to correct the slanting fall of his craft. "Sounded as though there was a tremendous back-fire, or else the muffler blew up. The engine is dead."
"Can you take her down safely?"
"Oh, yes, I guess so. She's a bit out of control, but the stabilizer will keep her on a level keel. Good thing we installed it."
"You're right!" said Jackson.
Now they were falling earthward with great rapidity, but, thanks to the gyroscope stabilizer, the "side-slipping," than which there is no motion more dreaded by an aviator, had nearly ceased. The craft was volplaning down as it ought, and Tom had it under as perfect control as was possible under the circumstances.
"We'll get down all right if something else doesn't happen," he said to Jackson, with grim humor.
"Well, let's hope that it won't," said the mechanic. "We're a good distance up yet."
They were, as a matter of fact, for the explosion, or whatever had happened to the craft, had occurred at a height of over two miles, and they at once began falling. As yet Tom Swift was unaware of the exact nature of the accident or its cause. All he knew was that there had been a big noise and that the engine had stopped working. He could not see the silencer from where he sat, as it was constructed on the underside of the motor, but he had an idea that the same sort of mishap had occurred as on the occasion when the test machine had sailed through the roof of his workshop.
"But, luckily, this wasn't as bad," mused Tom. "Anyhow the motor is out of business."