"That's all right," said the constable. "I was there in my official capacity, and I shoot when I want to."

"But the shot did no harm," Hatch put in.

"I would swear it went right through it, too," said the constable, boastfully. "I can shoot."

Weston was arguing with himself. He was a cold-blooded man of business; his mind was not one to play him tricks. Yet now he felt benumbed; he could conceive no explanation of what he had seen. Again in his room in the little hotel, where they spent the remainder of the night, he stared blankly at the reporter.

"Can you imagine any way it could be done?" Hatch shook his head.

"It isn't a spook, of course," the broker went on, with a nervous smile; "but--but I'm sorry I went. I don't think probably I shall have the work done there as I thought."

They slept only fitfully and took an early train back to Boston. As they were about to separate at the South Station, the broker had a last word.

"I'm going to solve that thing," he declared, determinedly. "I know one man at least who isn't afraid of it--or of anything else. I'm going to send him down to keep a lookout and take care of the place. His name is O'Heagan, and he's a fighting Irishman. If he and that--that--THING ever get mixed up together----"

Like a schoolboy with a hopeless problem, Hatch went straight to The Thinking Machine with the latest developments. The scientist paused just long enough in his work to hear it.

"Did you notice the handwriting?" he demanded.