The Ear in the Wall

by Arthur B. Reeve

He seemed merely to be giving the hole in the top of the safe a passing glance, as though it was of no importance that someone should have in such an incredibly short time made a hole through which one might easily reach his arm and secure anything he wanted out of the interior of the powerful little safe.

Langhorne, too, seemed surprised at Kennedy's matter of fact passing by of what was almost beyond the range of possibility.

"After all," remarked Kennedy, "it is not the safe that we care to study so much as the door. For one thing, I want to make sure whether the marks show a genuine breaking and entering or whether they were placed there afterwards merely to cover the trail, supposing someone had used a key to get into the office."

The remark suggested many things to me. Was it that he meant to imply that, after all, the missing Betty Blackwell had had something to do with it? In fact, could the thing have been done by a woman?

"Most persons," remarked Craig, as he studied the marks on the door, "don't know enough about jimmies. Against them an ordinary door-lock or window-catch is no protection. With a jimmy eighteen inches long, even an anemic burglar can exert a pressure sufficient to lift two tons. Not one door-lock in ten thousand can stand this strain. It's like using a hammer to kill a fly. Really, the only use of locks is to keep out sneak thieves and to compel the modern, scientific educated burglar to make a noise. This fellow, however, was no sneak thief."

He continued to adjust the machine which he had brought. Langhorne watched minutely, but did not say anything.

"Bertillon used to call this his mechanical burglar detector," continued Kennedy. "As you see, this frame carries two dynamometers of unequal power. The stronger, which has a high maximum capacity of several tons, is designed for the measurement of vertical efforts. The other measures horizontal efforts. The test is made by inserting the end of a jimmy or other burglar's tool and endeavouring to produce impressions similar to those which have been found on doors or windows. The index of the dynamometer moves in such a way as to make a permanent record of the pressure exerted. The horizontal or traction dynamometer registers the other component of pressure."

He pressed down on the machine. "There was a pressure here of considerably over two tons," he remarked at length, "with a very high horizontal traction of over four hundred pounds. What I wanted to get at was whether this could have been done by a man, woman, or child, or perhaps by several persons. In this case, it was clearly no mere fake to cover up the opening of the door by a key. It was a genuine attempt. Nor could it have been done by a woman. No, that is the work of a man, a powerful man, too, accustomed to the use of the jimmy."

I fancied that a shade of satisfaction crossed the otherwise impassive face of Langhorne. Was it because the Bertillon dynamometer appeared at first sight to exonerate Betty Blackwell, at least so far, from any connection with the crime? It was difficult to say.

Important though it was, however, to clear up at the start just what sort of person was connected with the breaking of the door I could not but feel that Kennedy had some purpose in deferring and minimizing for the present what, to me at least, was the greater mystery, the entering of the safe itself.