It was a small cylinder, apparently made of lead, and about three inches long.  Jack picked it up, and for the time being did not attempt to examine it but thrust it into his pocket for safe keeping.  Little did either of the boys think how much that little cylinder was to mean to them, and how it was to influence some of the most important adventures of their lives.

Making the man as comfortable as they could, by rolling up their coats and placing them under his head, the boys hurried back to the Wondership.  When they arrived there they saw that a feature of the radio ’phone, which has not yet been mentioned, was working in urgent appeal.  This was a tiny red electric light attached to the top of the case containing the sensitive parts of the apparatus.

By an ingenious device, worked as a call signal from the transmitting station, the electric waves converted a lighting circuit for this purpose.

It was winking and twinkling, and Jack knew that his father was trying to call them.

He sent out some flashes by starting the dynamo going and pressing a key devised for the purpose.  This, he knew, would cause a similar light attached to his father’s apparatus to flash a reply.  This done he waited a second and then adjusted the receivers to his ears.

“What’s the matter?” came his father’s voice.

Jack gave him a rapid account of the accident, not stopping just then to say anything about the incident of the farmer and his barn.

“What are you going to do about it?” asked his father.

“He appears to be seriously hurt,” said Jack.  “I was thinking of rushing him to the hospital at Nestorville.”

“That seems to be the best plan,” said his father.  “By the way, did those autoists get clear away?”

“I’m afraid so.  They never even waited a second to see if the man was badly injured.  They——­”

Jack suddenly stopped short.  An inspiration had come to him.  The accident had happened on a road that, as he knew, led straight through Nestorville.  He had thought of a plan to bring the autoists to book for their callousness and negligence.

“Dad—­oh, dad!” he called.

“Yes, what is it?” came back Mr. Chadwick’s voice.

“Those fellows will pass through Nestorville.  I had a flash of the number of the car.  It was 4206 Mass.  It’s a red car and a powerful one, with three men in it.”

“What do you want to do?” asked Mr. Chadwick.

“Can’t you ’phone to the Nestorville police, telling them what has happened and have those fellows stopped.  I’m not vindictive, but they ought to be brought to book for running down a man and then speeding off and leaving him like that.”

“I agree with you,” replied Mr. Chadwick.  “I’ll do so at once.  Good-by.”

“Good-by,” said Jack and “rang off.”

“That was a great idea of yours, Jack, old boy,” approved Tom.  “I hope they land those fellows.”