k in a halo of smoke and dust.
Speed! No runaway had ever traveled faster and kept the rails. The
story of the incident was embalmed in railroad history, and no history
is so full of vivid incident as that of the rail.

When the first relay of excited railroad men reached the electric
locomotive after it had stopped on the long level, even Ned Newton had
pulled himself together and could look out upon the world with some
measure of calmness. Tom Swift was making certain notes and draughting
a curious little diagram upon a page of his notebook.

"What happened to you, Mr. Swift?" was the demand of the first arrival.

"Oh, my foot slipped," said the young inventor, and they got nothing
more out of him than that.

But to Ned, after the crowd had gone, the inventor said:

"Ned, my boy, they used to say that necessity was the mother of
invention. Therefore a loaf of bread was considered the maternal parent
of the locomotive. I've got one that will beat that."

"Whew!" gasped Ned. "How can you? I haven't got my breath back yet."

"It is peril that is the mother of invention," Tom went on, still
jotting down his notes. "Believe me! that jolt gave me a new idea--an
important idea. Suppose that operator at Half Way had been out back
somewhere, and had not seen or heard us flash by?"

"Well, suppose he had? What's the answer?" sighed Ned.

"Like enough we would have rammed something down here."

"And I hardly understand even now why we didn't do just that," muttered
his chum, with a shake of his head.

"Wake up, Ned! It's all over," laughed Tom. "While it was happening I
admit I was guessing just as hard as you were about the finish. But--"

"Your recovery is better," grumbled his friend. "I'm scared yet."

"And it might happen again--"

"No--not--ever!" exclaimed Ned. "I shall never touch those controllers
again. I'll drive your airscout, or your fastest automobile, or
anything like that. But me and this electric locomotive have parted
company for good. Yes, sir!"

"All right. It wasn't your fault. It might happen to any
motor-engineer. And the very fact that it can happen has given me my
idea. I tell you that danger is the mother of invention."

"As far as I am concerned, it can be father and grandparents into the
bargain," Ned declared, with a smile.

"Wake up!" cried his friend again. "I have got a dandy idea. I wouldn't
have missed that trip for anything."

"You are crazy," interrupted Ned. "Suppose we h