“Nothing!” fairly bellowed the watchman. “I saw it plain as the nose on my face. See here, I had the door ajar about a foot to let in a little of the cool evening air. Here I sat in my chair right near it. I must have half snoozed and woke up suddenly. Not five feet away, right near that oil tank yonder, was a horrible shape. It was all white and unearthly. As I started up it let out an unearthly scream and waved its arms. Say, it was curdling! I bolted for the door, locked it, and scooted.”

“Yes, you scooted all right,” grumbled Hiram, rubbing a bump on his head.

Mr. King, with a glance of impatience at the great booby of a watchman, proceeded briskly the length of the building, peering into every odd nook and corner. When he came back he held in his hand a long cotton sheet that had been used to cover some of the machinery.

“That is what you saw,” he declared. “Somebody has been playing a trick on you.”

“Why, how could that be,” chattered the watchman, “seeing nobody was in the building but me?”

“How do you know that?” demanded the aviator; “when you say you had the door open? I tell you some one slipped in, wrapped in the sheet, and half scared the life out of you.”

“Then he must be here now,” insisted the watchman, “for when I bolted I locked the door after me.”

“It all looks rather queer,” remarked Mr. Dale.

“Hi!” suddenly shouted the watchman.

“What’s the matter now?” asked Mr. King.