“Guess he’d like that O. K.,” smiled Johnny. “Thanks for the car. If you’ll allow me, I should like to use it driving back and forth from your factory to the School of Engineering. I’d like to spend a half day in each place. There are a lot of things I need to know.”

“A splendid idea!” said Mr. McFarland. And at that Johnny bowed himself out.

A half hour later he and Pant sat drinking coffee and munching doughnuts in the small kitchen of the aged inventor of the dust-burning motor. They were telling their story to the delighted old couple. And that story, better than mere assurance, informed them that the invention was a huge success and that they were rich. No other pleasure could have so fittingly crowned this series of adventures than did this simple story-telling to two old people who appreciated it all as no others could.

Johnny stuck to his purpose of attending the engineering school. He learned there many of the secrets of science and industry. The time soon came, too, when he might put his knowledge to work. For, one day, he received a wire from Pant, who was again on the Pacific coast with the “Dust Eater.”

“Come at once,” the telegram ran. “Need you. Big new sea mystery. Will explain on arrival.”

What that mystery was and how they solved it must be told in our next volume of mystery and adventure, “The Black Schooner.”

Transcriber’s Notes