It was late that night that Kennedy and I left Carton after laying out a campaign and setting in motion various forces, official and unofficial, which might serve to keep us in touch with what Dorgan and the organization were doing.

Not until the following morning, however, did anything new develop in such a way that we could work on it.

Kennedy had picked up the morning papers which had been left at the door of our apartment and was hastily running his eye over the headlines on the first page, as was his custom.

"By Jove, Walter," I heard him exclaim. "What do you think of that—a robbery below the deadline—and in Langhorne's office, too."

I hurried out of my room and glanced at the papers, also. Sure enough, there it was:

SAFE ROBBED IN WALL ST. OFFICE

Door Into Office of Langhorne & Westlake, Brokers, Forced and Safe
Robbed.

One of the strangest robberies ever perpetrated was pulled off last night in the office of Langhorne & Westlake, the brokers, at——-Wall Street, some time during the regular closing time of the office and eight o'clock.

Mr. Langhorne had returned to his office after dining with some friends in order to work on some papers. When he arrived, about eight o'clock, he found that the door had been forced. The office was in darkness, but when he switched on the lights it was discovered that the office safe had been entered.

Nothing was said about the manner in which the safe robbery was perpetrated, but it is understood to have been very peculiar. So far no details have been announced and the robbery was not reported to the police until a late hour.

Mr. Langhorne, when seen by the reporters, stated positively that nothing of great value had been taken and that the firm would not suffer in any way as a result of the robbery.

One of the stenographers in the office, Miss Betty Blackwell, who acted as private secretary to Mr. Langhorne, is missing and the case has already attracted wide attention. Whether or not her disappearance had anything to do with the robbery is not known.

"Naturally he would not report it to the police," commented Kennedy; "that is, if it had anything to do with that Black Book, as I am sure that it must have had."

"It was certainly a most peculiar affair if it did not," I remarked.
"There must be some way of finding that out. It's strange about Betty
Blackwell."

Kennedy was turning something over in his mind. "Of course," he remarked, "we don't want to come out into the open just yet, but it would be interesting to know what happened down there at Langhorne's. Have you any objection to going down with me and posing as a reporter from the Star?"

"None whatever," I returned.

We stopped at the laboratory on the campus of the University where Craig still retained his professorship. Kennedy secured a rather bulky piece of apparatus, which, as nearly as I can describe, consisted of a steel frame, which could be attached by screws to any wooden table. It contained a lower plate which could move forward and back, two lateral uprights stiffened by curved braces, and a cross piece of steel attached by strong bolts to the tops of the posts. In the face of the machine was a dial with a pointer.

Kennedy quickly took the apparatus apart and made it up into two packages so that between us we could carry it easily, and at about the time that Wall Street offices were opening we were on our way downtown.

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.

Langhorne now but ill concealed his interest. It was natural, too, for here he had one of the most modern of small strong-boxes, built up of the latest chrome steel and designed to withstand any reasonable assault of cracksman or fire.

I was on the point of inquiring how on earth it had been possible to rob the safe, when Kennedy, standing on a chair, as Langhorne directed, uttered a low exclamation.

I craned my neck to look also.

There, in the very top of the safe, yawned a huge hole large enough to thrust one's arm through, with something to spare.

As I looked at the yawning dark hole in the top of what had been only a short time ago a safe worthy of the latest state of the art, it seemed incomprehensible.

Try as I could to reason it out, I could find no explanation. How it had been possible for a burglar to make such an opening in the little more than two hours between closing and the arrival of Langhorne after dinner, I could not even guess. As far as I knew it would have taken many long hours of patient labour with the finest bits to have made anything at all comparable to the destruction which we saw before us.

A score of questions were on my lips, but I said nothing, although I could not help noticing the strange look on Langhorne's face. It plainly showed that he would like to have known what had taken place during the two or more hours when his office had been unguarded, yet was averse to betraying any such interest.

Mystified as I was by what I saw, I was even more amazed at the cool manner in which Kennedy passed it all by.

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.

He was still studying and comparing the marks on the door and the record made on the dynamometer, when the office telephone rang and Langhorne was summoned to answer it. Instead of taking the call in his own office, he chose to answer it at the switchboard, perhaps because that would allow him to keep an eye also on us.

Whatever his purpose, it likewise enabled us to keep an ear on him, and it was with surprise which both Kennedy and I had great difficulty in concealing, that we heard him reply, "Hello—yes—oh, Mrs. Ogleby, good-morning. How are you? That's good. So you, too, read the papers. No, I haven't lost anything of importance, thank you. Nothing serious, you know. The papers like to get hold of such things and play them up. I have a couple of reporters here now. Heaven knows what they are doing, but I can foresee some more unpaid advertising for the firm in it. Thank you again for your interest. You haven't forgotten the studio dance I'm giving on the twelfth? No—that's fine. I hope you'll come, even if Martin has another engagement. Fine. Well-good-bye."

He hung up the receiver with a mingled air of gratification and exasperation, I fancied.

"Haven't you fellows finished yet?" he asked finally, coming over to us, a little brusquely.

"Just about," returned Kennedy, who had by this time begun slowly to dismember and pack up the dynamometer, determined to take advantage of every minute both to observe Langhorne and to fix in his mind the general lay-out of the office.

"Everybody seems to be interested in me this morning," he observed, for the moment forgetting the embargo he had imposed on his own words.

As for myself, I saw at once that others besides ourselves were keenly interested in this robbery.

"There," remarked Kennedy when at last he had finished packing up the dynamometer into two packages. "At least, Mr. Langhorne, you have the satisfaction of knowing that it was in all probability a man, a strong man, and one experienced in forcing doors who succeeded in entering your office during your brief absence last night."

Langhorne shrugged his shoulders non-committally, but it was evident that he was greatly relieved and he could not conceal his interest in what Kennedy was doing, even though he had succeeded in conveying the impression that it was a matter of indifference to him.

"I suppose you keep a great many of your valuable papers in safety deposit vaults," ventured Kennedy, finishing up the wrapping of the two packages, "as well as your personal papers perhaps at home."

He made the remark in a casual manner, but Langhorne was too keen to fall into the trap.

"Really," he said with an air of finality, "I must decline to be interviewed at present. Good-day, gentlemen."

"A slippery customer," was Craig's comment when we reached the street outside the office. "By the way, evidently Mrs. Ogleby is leaving no stone unturned in her effort to locate that Black Book and protect herself."

I said nothing. Langhorne's manner, self-confident to the point of bravado, had baffled me. I began to feel that even if he had lost the detectaphone record, his was the nature to carry out the bluff of still having it, in much the same manner that he would have played the market on a shoestring or made the most of an unfilled four-card flush in a game of poker.

Kennedy was far from being discouraged, however. Indeed, it seemed as if he really enjoyed matching his wit against the subtlety of a man like Langhorne, even more than against one the type of Dorgan and Murtha.

"I want to see Carton and I don't want to carry these bundles all over the city," he remarked, changing the subject for the moment, as he turned into a public pay station. "I'll ring him up and have him meet us at the laboratory, if I can."

A moment later he emerged, excited, perspiring from the closeness of the telephone booth.

"Carton has some news—a letter—that's all he would say," he exclaimed. "He'll meet us at the laboratory."

We hastily resumed our uptown journey.

"What do you think it is?" I asked. "About Betty Blackwell?"

Kennedy shook his head non-committally. "I don't know. But he has some of his county detectives watching Dorgan and Murtha in that Black Book case, I know. They are worried. It doesn't look as though they, at least, had the record—that is, if Langhorne has really lost it."

I wondered whether Langhorne might not, after all, as Kennedy had hinted, have concealed it elsewhere. The activity of Dorgan and Murtha might indicate that they knew more about the robbery than appeared yet on the surface. Had they failed in it? Had they been double-crossed by the man they had chosen for the work, assuming that they knew of and had planned the "job"?

The safe-breaking and the way Langhorne took it had served to complicate the case even further. While we had before been reasonably sure that Langhorne had the book, now we were sure of nothing.