I followed him in awe as he made a hasty inventory of what we had discovered. There were as many as a dozen finished and partly finished infernal machines of various sizes and kinds, some of tremendous destructive capacity. Kennedy did not even attempt to study them. All about were high explosives, chemicals, dynamite. There was gunpowder of all varieties, antimony, blasting-powder, mercury cyanide, chloral hydrate, chlorate of potash, samples of various kinds of shot, some of the outlawed soft-nosed dumdum bullets, cartridges, shells, pieces of metal purposely left with jagged edges, platinum, aluminum, iron, steel—a conglomerate mass of stuff that would have gladdened an anarchist.

Kennedy was examining a little quartz-lined electric furnace, which was evidently used for heating soldering irons and other tools. Everything had been done, it seemed, to prevent explosions. There were no open lights and practically no chance for heat to be communicated far among the explosives. Indeed, everything had been arranged to protect the operator himself in his diabolical work.

Kennedy had switched on the electric furnace, and from the various pieces of metal on the table selected several. These he was placing together in a peculiar manner, and to them he attached some copper wire which lay in a corner in a roll.

Under the work-table, beneath the furnace, one could feel the warmth of the thing slightly. Quickly he took the curious affair, which he had hastily shaped, and fastened it under the table at that point, then led the wires out through a little barred window to an air-shaft, the only means of ventilation of the place except the door.

While he was working I had been gingerly inspecting the rest of the den. In a corner, just beside the door, I had found a set of shelves and a cabinet. On both were innumerable packets done up in white paper. I opened one and found it contained several pinches of a white, crystalline substance.

"Little portions of cocaine," commented Kennedy, when I showed him what
I had found. "In the slang of the fiends, 'decks.'"

On the top of the cabinet he discovered a little enamelled box, much like a snuff-box, in which were also some of the white flakes. Quickly he emptied them out and replaced them with others from jars which had not been made up into packets.

"Why, there must be hundreds of ounces of the stuff here, to say nothing of the various things they adulterate it with," remarked Kennedy. "No wonder they are so careful when it is a felony even to have it in your possession in such quantities. See how careful they are about the adulteration, too. You could never tell except from the effect whether it was the pure or only a few-per-cent.-pure article."

Kennedy took a last look at the den, to make sure that nothing had been disturbed that would arouse suspicion.

"We may as well go," he remarked. "To-morrow, I want to be free to make the connection outside with that wire in the shaft."

Imagine our surprise, the next morning, when a tap at our door revealed
Loraine Keith herself.

"Is this Professor Kennedy?" she asked, gazing at us with a half-wild
expression which she was making a tremendous effort to control.
"Because if it is, I have something to tell him that may interest Mr.
Carton."

We looked at her curiously. Without her make-up she was pallid and yellow in spots, her hands trembling, cold, and sweaty, her eyes sunken and glistening, with pupils dilated, her breathing short and hurried, restless, irresolute, and careless of her personal appearance.

"Perhaps you wonder how I heard of you and why I have come to you," she went on. "It is because I have a confession to make. I saw Mr. Haddon just before he was—kidnapped."

She seemed to hesitate over the word.

"How did you know I was interested?" asked Kennedy keenly.

"I heard him mention your name with Mr. Carton's."

"Then he knew that I was more than a reporter for the Star," remarked
Kennedy. "Kidnapped, you say? How?"

She shot a glance half of suspicion, half of frankness, at us.

"That's what I must confess. Whoever did it must have used me as a tool. Mr. Haddon and I used to be good friends—I would be yet."

There was evident feeling in her tone which she did not have to assume. "All I remember yesterday was that, after lunch, I was in the office of the Mayfair when he came in. On his desk was a package. I don't know what has become of it. But he gave one look at it, seemed to turn pale, then caught sight of me. 'Loraine,' he whispered, 'we used to be good friends. Forgive me for turning you down. But you don't understand. Get me away from here—come with me—call a cab.'

"Well, I got into the cab with him. We had a chauffeur whom we used to have in the old days. We drove furiously, avoiding the traffic men. He told the driver to take us to my apartment—and—and that is the last I remember, except a scuffle in which I was dragged from the cab on one side and he on the other."

She had opened her handbag and taken from it a little snuff-box, like that which we had seen in the den.

"I—I can't go on," she apologised, "without this stuff."

"So you are a cocaine fiend, also?" remarked Kennedy.

"Yes, I can't help it. There is an indescribable excitement to do something great, to make a mark, that goes with it. It's soon gone, but while it lasts I can sing and dance, do anything until every part of my body begins crying for it again. I was full of the stuff when this happened yesterday; had taken too much, I guess."

The change in her after she had snuffed some of the crystals was magical. From a quivering wretch she had become now a self-confident neurasthenic.

"You know where that stuff will land you, I presume?" questioned
Kennedy.

"I don't care," she laughed hollowly. "Yes, I know what you are going to tell me. Soon I'll be hunting for the cocaine bug, as they call it, imagining that in my skin, under the flesh, are worms crawling, perhaps see them, see the little animals running around and biting me. Oh, you don't know. There are two souls to the cocainist. One is tortured by the suffering which the stuff brings; the other laughs at the fears and pains. But it brings such thoughts! It stimulates my mind, makes it work without, against my will, gives me such visions—oh, I can not go on. They would kill me if they knew I had come to you. Why have I? Has not Haddon cast me off? What is he to me, now?"

It was evident that she was growing hysterical. I wondered whether, after all, the story of the kidnapping of Haddon might not be a figment of her brain, simply an hallucination due to the drug.

"They?" inquired Kennedy, observing her narrowly. "Who?"

"I can't tell. I don't know. Why did I come? Why did I come?"

She was reaching again for the snuff-box, but Kennedy restrained her.

"Miss Keith," he remarked, "you are concealing something from me. There is some one," he paused a moment, "whom you are shielding."

"No, no," she cried. "He was taken. Brodie had nothing to do with it, nothing. That is what you mean. I know. This stuff increases my sensitiveness. Yet I hate Coke Brodie—oh—let me go. I am all unstrung. Let me see a doctor. To-night, when I am better, I will tell all."

Loraine Keith had torn herself from him, had instantly taken a pinch of the fatal crystals, with that same ominous change from fear to self-confidence. What had been her purpose in coming at all? It had seemed at first to implicate Brodie, but she had been quick to shield him when she saw that danger. I wondered what the fascination might be which the wretch exercised over her.

"To-night—I will see you to-night," she cried, and a moment later she was gone, as unexpectedly as she had come.

I looked at Kennedy blankly.

"What was the purpose of that outburst?" I asked.

"I can't say," he replied. "It was all so incoherent that, from what I know of drug fiends, I am sure she had a deep-laid purpose in it all. It does not change my plans."

Two hours later we had paid a deposit on an empty flat in the tenement-house in which the bomb-maker had his headquarters, and had received a key to the apartment from the janitor. After considerable difficulty, owing to the narrowness of the air-shaft, Kennedy managed to pick up the loose ends of the wire which had been led out of the little window at the base of the shaft, and had attached it to a couple of curious arrangements which he had brought with him. One looked like a large taximeter from a motor cab; the other was a diminutive gas-metre, in looks at least. Attached to them were several bells and lights.

He had scarcely completed installing the thing, whatever it was, when a gentle tap at the door startled me. Kennedy nodded, and I opened it. It was Carton.

"I have had my men watching the Mayfair," he announced. "There seems to be a general feeling of alarm there, now. They can't even find Loraine Keith. Brodie, apparently, has not shown up in his usual haunts since the episode of last night."

"I wonder if the long arm of this vice trust could have reached out and gathered them in, too?" I asked.

"Quite likely," replied Carton, absorbed in watching Kennedy. "What's this?"

A little bell had tinkled sharply, and a light had flashed up on the attachments to the apparatus.

"Nothing. I was just testing it to see if it works. It does, although the end which I installed down below was necessarily only a makeshift. It is not this red light with the shrill bell that we are interested in. It is the green light and the low-toned bell. This is a thermopile."

"And what is a thermopile?"' queried Carton.

"For the sake of one who has forgotten his physics," smiled Kennedy, "I may say this is only another illustration of how all science ultimately finds practical application. You probably have forgotten that when two half-rings of dissimilar metals are joined together and one is suddenly heated or chilled, there is produced at the opposite connecting point a feeble current which will flow until the junctures are both at the same temperature. You might call this a thermo-electric thermometer, or a telethermometer, or a microthermometer, or any of a dozen names."

"Yes," I agreed mechanically, only vaguely guessing at what he had in mind.

"The accurate measurement of temperature is still a problem of considerable difficulty," he resumed, adjusting the thermometer. "A heated mass can impart vibratory motion to the ether which fills space, and the wave-motions of ether are able to reproduce in other bodies motions similar to those by which they are caused. At this end of the line I merely measure the electromotive force developed by the difference in temperature of two similar thermo-electric junctions, opposed. We call those junctions in a thermopile 'couples,' and by getting the recording instruments sensitive enough, we can measure one one-thousandth of a degree.

"Becquerel was the first, I believe, to use this property. But the machine which you see here was one recently invented for registering the temperature of sea water so as to detect the approach of an iceberg. I saw no reason why it should not be used to measure heat as well as cold.

"You see, down there I placed the couples of the thermopile beneath the electric furnace on the table. Here I have the mechanism, operated by the feeble current from the thermopile, opening and closing switches, and actuating bells and lights. Then, too, I have the recording instrument. The thing is fundamentally very simple and is based on well-known phenomena. It is not uncertain and can be tested at any time, just as I did then, when I showed a slight fall in temperature. Of course it is not the slight changes I am after, not the gradual but the sudden changes in temperature."

"I see," said Carton. "If there is a drop, the current goes one way and we see the red light; a rise and it goes the other, and we see a green light."

"Exactly," agreed Kennedy. "No one is going to approach that chamber down-stairs as long as he thinks any one is watching, and we do not know where they are watching. But the moment any sudden great change is registered, such as turning on that electric furnace, we shall know it here."

It must have been an hour that we sat there discussing the merits of the case and speculating on the strange actions of Loraine Keith.

Suddenly the red light flashed out brilliantly.

"What's that?" asked Carton quickly.

"I can't tell, yet," remarked Kennedy. "Perhaps it is nothing at all. Perhaps it is a draught of cold air from opening the door. We shall have to wait and see."

We bent over the little machine, straining our eyes and ears to catch the visual and audible signals which it gave.

Gradually the light faded, as the thermopile adjusted itself to the change in temperature.

Suddenly, without warning, a low-toned bell rang before us and a bright-green light flashed up.

"That can have only one meaning," cried Craig excitedly. "Some one is down there in that inferno—perhaps the bomb-maker himself."

The bell continued to ring and the light to glow, showing that whoever was there had actually started the electric furnace. What was he preparing to do? I felt that, even though we knew there was some one there, it did us little good. I, for one, had no relish for the job of bearding such a lion in his den.

We looked at Kennedy, wondering what he would do next. From the package in which he had brought the two registering machines he quietly took another package, wrapped up, about eighteen inches long and apparently very heavy. As he did so he kept his attention fixed on the telethermometer. Was he going to wait until the bomb-maker had finished what he had come to accomplish?

It was perhaps fifteen minutes after our first alarm that the signals began to weaken.

"Does that mean that he has gone—escaped?" inquired Carton anxiously.

"No. It means that his furnace is going at full power and that he has forgotten it. It is what I am waiting for. Come on."

Seizing the package as he hurried from the room, Kennedy dashed out on the street and down the outside cellar stairs, followed by us.

He paused at the thick door and listened. Apparently there was not a sound from the other side, except a whir of a motor and a roar which might have been from the furnace. Softly he tried the door. It was locked on the inside.

Was the bomb-maker there still? He must be. Suppose he heard us. Would he hesitate a moment to send us all to perdition along with himself?

How were we to get past that door? Really, the deathlike stillness on the other side was more mysterious than would have been the detonation of some of the criminal's explosive.

Kennedy had evidently satisfied himself on one point. If we were to get into that chamber we must do it ourselves, and we must do it quickly.

From the package which he carried he pulled out a stubby little cylinder, perhaps eighteen inches long, very heavy, with a short stump of a lever projecting from one side. Between the stonework of a chimney and the barred door he laid it horizontally, jamming in some pieces of wood to wedge it tighter.

Then he began to pump on the handle vigorously. The almost impregnable door seemed slowly to bulge. Still there was no sign of life from within. Had the bomb-maker left before we arrived?

"This is my scientific sledge-hammer," panted Kennedy, as he worked the little lever backward and forward more quickly—"a hydraulic ram. There is no swinging of axes or wielding of crowbars necessary in breaking down an obstruction like this, nowadays. Such things are obsolete. This little jimmy, if you want to call it that, has a power of ten tons. That ought to be enough."

It seemed as if the door were slowly being crushed in before the irresistible ten-ton punch of the hydraulic ram.

Kennedy stopped. Evidently he did not dare to crush the door in altogether. Quickly he released the ram and placed it vertically. Under the now-yawning door jamb he inserted a powerful claw of the ram and again he began to work the handle.

A moment later the powerful door buckled, and Kennedy deftly swung it outward so that it fell with a crash on the cellar floor.

As the noise reverberated, there came a sound of a muttered curse from the cavern. Some one was there.

We pressed forward.

On the floor, in the weird glare of the little furnace, lay a man and a woman, the light playing over their ghastly, set features.

Kennedy knelt over the man, who was nearest the door.

"Call a doctor, quick," he ordered, reaching over and feeling the pulse of the woman, who had half fallen out of her chair. "They will, be all right soon. They took what they thought was their usual adulterated cocaine—see, here is the box in which it was. Instead, I filled the box with the pure drug. They'll come around. Besides, Carton needs both of them in his fight."

"Don't take any more," muttered the woman, half conscious. "There's something wrong with it, Haddon."

I looked more closely at the face in the half-darkness.

It was Haddon himself.

"I knew he'd come back when the craving for the drug became intense enough," remarked Kennedy.

Carton looked at Kennedy in amazement. Haddon was the last person in the world whom he had evidently expected to discover here.

"How—what do you mean?"

"The episode of the telephone booth gave me the first hint. That is the favourite stunt of the drug fiend—a few minutes alone, and he thinks no one is the wiser about his habit. Then, too, there was the story about his speed mania. That is a frequent failing of the cocainist. The drug, too, was killing his interest in Loraine Keith—that is the last stage.

"Yet under its influence, just as with his lobbygow and lieutenant, Brodie, he found power and inspiration. With him it took the form of bombs to protect himself in his graft."

"He can't—escape this time—Loraine. We'll leave it—at his house—you know—Carton—"

We looked quickly at the work-table. On it was a gigantic bomb of clockwork over which Haddon had been working. The cocaine which was to have given him inspiration had, thanks to Kennedy, overcome him.

Beside Loraine Keith were a suit-case and a Gladstone. She had evidently been stuffing the corners full of their favourite nepenthe, for, as Kennedy reached down and turned over the closely packed woman's finery and the few articles belonging to Haddon, innumerable packets from the cabinet dropped out.

"Hulloa—what's this?" he exclaimed, as he came to a huge roll of bills and a mass of silver and gold coin. "Trying to double-cross us all the time. That was her clever game—to give him the hours he needed to gather what money he could save and make a clean getaway. Even cocaine doesn't destroy the interest of men and women in that," he concluded, turning over to Carton the wealth which Haddon had amassed as one of the meanest grafters of the city of graft.

Here was a case which I could not help letting the Star have immediately. Notes or no notes, it was local news of the first order. Besides, anything that concerned Carton was of the highest political significance.

It kept me late at the office and I overslept. Consequently I did not see much of Craig the next morning, especially as he told me he had nothing special, having turned down a case of a robbery of a safe, on the ground that the police were much better fitted to catch ordinary yeggmen than he was. During the day, therefore, I helped in directing the following up of the Haddon case for the Star.

Then, suddenly, a new front page story crowded this one of the main headlines. With a sigh of relief, I glanced at the new thriller, found it had something to do with the Navy Department, and that it came from as far away as Washington. There was no reason now why others could not carry on the graft story, and I left, not unwillingly. My special work just now was keeping on the trail of Kennedy, and I was glad to go back to the apartment and wait for him.

"I suppose you saw that despatch from Washington in this afternoon's papers?" he queried, as he came in, tossing a late edition of the Record down on my desk.

Across the front page extended a huge black scare-head: "NAVY'S MOST
VITAL SECRET STOLEN."

"Yes," I shrugged, "but you can't get me much excited by what the rewrite men on the Record say."

"Why?" he asked, going directly into his own room.

"Well," I replied, glancing through the text of the story, "the actual facts are practically the same as in the other papers. Take this, for instance, 'On the night of the celebration of the anniversary of the battle of Manila there were stolen from the Navy Department plans which the Record learns exclusively represent the greatest naval secret in the world.' So much for that paragraph—written in the office. Then it goes on:

"The whole secret-service machinery of the Government has been put in operation. No one has been able to extract from the authorities the exact secret which was stolen, but it is believed to be an invention which will revolutionise the structure and construction of the most modern monster battleships. Such knowledge, it is said, in the hands of experts might prove fatal in almost any fight in which our newer ships met others of about equal fighting power, as with it marksmen might direct a shot that would disable our ships.

"It is the opinion of the experts that the theft was executed by a skilled draughtsman or other civilian employe. At any rate, the thief knew what to take and its value. There is, at least, one nation, it is asserted, which faces the problem of bringing its ships up to the standard of our own to which the plans would be very valuable.

"The building had been thrown open to the public for the display of fireworks on the Monument grounds before it. The plans are said to have been on one of the draughting-tables, drawn upon linen to be made into blue-prints. They are known to have been on the tables when the draughting-room was locked for the night.

"The room is on the third floor of the Department and has a balcony looking out on the Monument. Many officers and officials had their families and friends on the balcony to witness the celebration, though it is not known that any one was in the draughting-room itself. All were admitted to the building on passes. The plans were tacked to a draughting-board in the room, but when it was opened in the morning the linen sheet was gone, and so were the thumb-tacks. The plans could readily have been rolled into a small bundle and carried under a coat or wrap.

"While the authorities are trying to minimise the actual loss, it is believed that this position is only an attempt to allay the great public concern."

I paused. "Now then," I added, picking up one of the other papers I had brought up-town myself, "take the Express. It says that the plans were important, but would have been made public in a few months, anyhow. Here:

"The theft—or mislaying, as the Department hopes it will prove to be—took place several days ago. Official confirmation of the report is lacking, but from trustworthy unofficial sources it is learned that only unimportant parts of plans are missing, presumably minor structural details of battle-ship construction, and other things of a really trivial character, such as copies of naval regulations, etc.

"The attempt to make a sensational connection between the loss and a controversy which is now going on with a foreign government is greatly to be deplored and is emphatically asserted to be utterly baseless. It bears traces of the jingoism of those 'interests' which are urging naval increases.

"There is usually very little about a battle-ship that is not known before her keel is laid, or even before the signing of the contracts. At any rate, when it is asserted that the plans represent the dernier cri in some form of war preparation, it is well to remember that a 'last cry' is last only until there is a later. Naval secrets are few, anyway, and as it takes some years to apply them, this loss cannot be of superlative value to any one. Still, there is, of course, a market for such information in spite of the progress toward disarmament, but the rule in this case will be the rule as in a horse trade, 'Caveat emptor.'"

"So there you are," I concluded. "You pay your penny for a paper, and you take your choice."

"And the Star," inquired Kennedy, coming to the door and adding with an aggravating grin, "the infallible?"

"The Star," I replied, unruffled, "hits the point squarely when it says that whether the plans were of immediate importance or not, the real point is that if they could be stolen, really important things could be taken also. For instance, 'The thought of what the thief might have stolen has caused much more alarm than the knowledge of what he has succeeded in taking.' I think it is about time those people in Washington stopped the leak if—"

The telephone rang insistently.

"I think that's for me," exclaimed Craig, bounding out of his room and forgetting his quiz of me. "Hello—yes—is that you, Burke? At the Grand Central—half an hour—all right. I'm bringing Jameson. Good-bye."

Kennedy jammed down the receiver on the hook.