“Getting tired, Mary?” called Tom, after a while.
“No!” she called back to him. “I could go on like this forever.”
“Guess I’ll have to invent some new kind of machine if you want to do anything like that,” the youth countered.
“What do you mean?” challenged Mary.
“I mean perpetual motion hasn’t yet been solved, and I don’t believe it ever will be. As long as we have gasoline engines they will have to be given a drink now and then. Which reminds me that I haven’t enough in the tanks of the Hummer to go on for more than a few hours more.”
“I don’t want to ride quite that long, of course! Don’t take any chances. Go back now if you think anything is going to happen.”
“Nothing is likely to happen!” chuckled the young inventor. “But I didn’t want you to go on dreaming that dream of yours about keeping on forever.”
“As if I meant that!” laughed the girl. “Better turn back now.”
“In a little while,” promised Tom, whose eyes were just then fixed on some object or some view just ahead. Mary was quick to notice his preoccupation as he spoke to her and at once asked:
“Is anything the matter, Tom?”