It wasn’t more than five minutes before Mr. Tidd and Mark and Plunk came in with Mr. Whiteley.

“Everything ready?” Mr. Whiteley asked the engineer; and Willis nodded that it was. Mr. Tidd went over to his turbine and began fiddling around with it, and I grabbed Mark by the arm and whispered in his ear, “That feller’s here.”

“What feller?”

“The sneakin’ one. That one that’s after your father’s turbine. He’s hidin’ here somewheres. The engineer’s a friend of his’n and telegraphed him to come.”

“Sure?” Mark asked, sharp.

“I saw him and heard him.”

Mark took hold of his fat cheek with his finger and thumb and pinched it. His little eyes were going here and there around the machinery and into corners, and he was thinking hard.

“He’s hidin’ where he can s-s-see,” he says, half to himself.

“Of course,” I told him, “that’s what he came for.”

Now, if it had been me I’d have told Mr. Tidd and Mr. Whiteley right off and had the stranger put out; but that wasn’t Mark’s way. He always wanted to engineer things differently and be original about it. If there was an easy way, like there was now, and some other way that had to be puzzled and figured over, he’d choose that way every time. I knew there wasn’t any use in my saying anything, so I just waited to see what would happen.