Langhorne proved to be a tall, rather slim, man of what might be called youngish middle age.  One did not have to be introduced to him to read his character or his occupation.  Every line of his faultlessly fitting clothes and every expression of his keen and carefully cared-for face betokened the plunger, the man who lived by his wits and found the process both fascinating and congenial.

“Mr. Langhorne,” began Kennedy, after I had taken upon myself the duty of introducing ourselves as reporters, “we are preparing an article for our paper about a new apparatus which the Star has imported especially from Paris.  It is a machine invented by Monsieur Bertillon just before he died, for the purpose of furnishing exact measurements of the muscular efforts exerted in the violent entry of a door or desk by making it possible to reproduce the traces of the work that a burglar has left on doors and articles of furniture.  We’ve been waiting for a case that the instrument would fit into and it seemed to us that perhaps it might be of some use to you in getting at the real robber of your office.  Would you mind if we made an attempt to apply it?”

Langhorne could not very well refuse to allow us to try the thing, though it was plainly evident that he did not want to talk and did not relish the publicity that the news of the morning had brought him.

Kennedy had laid the apparatus down on a table as he spoke and was assembling the parts which he had separated in order to carry it.

“These are the marks on the door, I presume?” he continued, examining some indentations of the woodwork near the lock.

Langhorne assented.

“The door was open when you returned?” asked Kennedy.

“Closed,” replied Langhorne briefly.  “Before I put the key into the lock, I turned the knob, as I have a habit of doing.  Instead of catching, it yielded and the door swung open without any trouble.”

He repeated the story substantially as we had already read it in the papers.

Kennedy had taken a step or two into the office, and was now facing the safe.  It was not a large safe, but was one of the most modern construction and was supposed to be burglar proof.

“And you say you lost practically nothing?” persisted Craig.

“Nothing of importance,” reiterated Langhorne.

Kennedy had been watching him closely.  The man was at least baffling.  There was nothing excited or perturbed about his manner.  Indeed, one might easily have thought that it was not his safe at all that had been robbed.  I wondered whether, after all, he had had the Black Book.  Certainly, I felt, if he had lost it he was very cool about the loss.

Craig had by this time reached the safe itself.  In spite of Langhorne’s reluctance, his assurance had taken Kennedy even up to the point which he wished.  He was examining the safe.

On the front it showed no evidence of having been “souped” or drilled.  There was not a mark on it.  Nor, as we learned later from the police, was there any evidence of a finger-print having been left by the burglar.