That seemed to make the unknown still more angry, but it was plain he found difficulty in commanding words to express himself.

“You’re a fool!” he finally snapped.

“Thank you!” smiled Frank.

“You’re an idiot!”

“Thank you again.”

“You are the one who is crazy!”

“Still more thanks.”

“How have I acted to make you fancy me demented?”

“You are out here, and you may be contemplating self-destruction by throwing yourself from this train.”

“Don’t worry about that. I am contemplating nothing of the sort.”