Far after midnight though it had been when we had at last turned in at our apartment, Kennedy was up even earlier than usual in the morning. I found him engrossed in work at the laboratory.

"Just in time to see whether I'm right in my guess about the illness of
Brixton," he remarked, scarcely looking up at me.

He had taken a flask with a rubber stopper. Through one hole in it was fitted a long funnel; through another ran a glass tube, connecting with a large U-shaped drying-tube filled with calcium chloride, which in turn connected with a long open tube with an up-turned end.

Into the flask Craig dropped some pure granulated zinc coated with platinum. Then he covered it with dilute sulphuric acid through the funnel tube. "That forms hydrogen gas," he explained, "which passes through the drying-tube and the ignition-tube. Wait a moment until all the air is expelled from the tubes."

He lighted a match and touched it to the open upturned end. The hydrogen, now escaping freely, was ignited with a pale-blue flame.

Next, he took the little piece of wall-paper I had seen him tear off in the den, scraped off some powder from it, dissolved it, and poured it into the funnel-tube.

Almost immediately the pale, bluish flame turned to bluish white, and white fumes were formed. In the ignition-tube a sort of metallic deposit appeared. Quickly he made one test after another. I sniffed. There was an unmistakable smell of garlic in the air.

"Arseniureted hydrogen," commented Craig. "This is the Marsh test for arsenic. That wall-paper in Brixton's den has been loaded down with arsenic, probably Paris green or Schweinfurth green, which is aceto-arsenite of copper. Every minute he is there he is breathing arseniureted hydrogen. Some one has contrived to introduce free hydrogen into the intake of his ventilator. That acts on the arsenic compounds in the wall-paper and hangings and sets free the gas. I thought I knew the smell the moment I got a whiff of it. Besides, I could tell by the jaundiced look of his face that he was being poisoned. His liver was out of order, and arsenic seems to accumulate in the liver."

"Slowly poisoned by minute quantities of gas," I repeated in amazement. "Some one in that Red Brotherhood is a diabolical genius. Think of it—poisoned wall-paper!"

It was still early in the forenoon when Kennedy excused himself, and leaving me to my own devices disappeared on one of his excursions into the underworld of the foreign settlements on the East Side. About the middle of the afternoon he reappeared. As far as I could learn all that he had found out was that the famous, or rather infamous, Professor Michael Kumanova, one of the leaders of the Red Brotherhood, was known to be somewhere in this country.

We lost no time in returning again to Woodrock late that afternoon. Craig hastened to warn Brixton of his peril from the contaminated atmosphere of the den, and at once a servant was set to work with a vacuum cleaner.

Carefully Craig reconnoitred the basement where the eavesdropping storeroom was situated. Finding it deserted, he quickly set to work connecting the two wires of the general household telephone with what looked very much like a seamless iron tube, perhaps six inches long and three inches in diameter. Then he connected the tube also with the private wire of Brixton in a similar manner.

"This is a special repeating-coil of high efficiency," he explained in answer to my inquiry. "It is absolutely balanced as to resistance, number of turns, and everything. I shall run this third line from the coil into Brixton's den, and then, if you like, you can accompany me on a little excursion down to the village where I am going to install another similar coil between the two lines at the local telephone central station opposite the railroad."

Brixton met us about eight o'clock that night in his now renovated den. Apparently, even the little change from uncertainty to certainty so far had had a tonic effect on him. I had, however, almost given up the illusion that it was possible for us to be even in the den without being watched by an unseen eye. It seemed to me that to one who could conceive of talking through an incandescent lamp seeing, even through steel and masonry, was not impossible.

Kennedy had brought with him a rectangular box of oak, in one of the large faces of which were two square boles. As he replaced the black camera-like box of the detectaphone with this oak box he remarked: "This is an intercommunicating telephone arrangement of the detectaphone. You see, it is more sensitive than anything of the sort ever made before. The arrangement of these little square holes is such as to make them act as horns or magnifiers of a double receiver. We can all hear at once what is going on by using this machine."

We had not been waiting long before a peculiar noise seemed to issue from the detectaphone. It was as though a door had been opened and shut hastily. Some one had evidently entered the storeroom. A voice called up the railroad station and asked for Michael Kronski, Count Wachtmann's chauffeur.

"It is the voice I heard last night," exclaimed Brixton. "By the Lord Harry, do you know, it is Janeff the engineer who has charge of the steam heating, the electric bells, and everything of the sort around the place. My own engineer—I'll land the fellow in jail before I'll—"

Kennedy raised his hand. "Let us hear what he has to say," remonstrated Craig calmly. "I suppose you have wondered why I didn't just go down there last night and grab the fellow. Well, you see now. It is my invariable rule to get the man highest up. This fellow is only one tool. Arrest him, and as likely as not we should allow the big criminal to escape."

"Hello, Kronski!" came over the detectaphone. "This is Janeff. How are things going?"

Wachtmann's chauffeur must have answered that everything was all right.

"You knew that they had discovered the poisoned wall-paper?" asked
Janeff.

A long parley followed. Finally, Janeff repeated what apparently had been his instructions. "Now, let me see," he said. "You want me to stay here until the last minute so that I can overhear whether any alarm is given for her? All right. You're sure it is the nine-o'clock train she is due on? Very well. I shall meet you at the ferry across the Hudson. I'll start from here as soon as I hear the train come in. We'll get the girl this time. That will bring Brixton to terms sure. You're right. Even if we fail this time, we'll succeed later. Don't fail me. I'll be at the ferry as soon as I can get past the guards and join you. There isn't a chance of an alarm from the house. I'll cut all the wires the last thing before I leave. Good-bye."

All at once it dawned on me what they were planning—the kidnapping of Brixton's only daughter, to hold her, perhaps, as a hostage until he did the bidding of the gang. Wachtmann's chauffeur was doing it and using Wachtmann's car, too. Was Wachtmann a party to it?

What was to be done? I looked at my watch. It was already only a couple of minutes of nine, when the train would be due.

"If we could seize that fellow in the closet and start for the station immediately we might save Yvonne," cried Brixton, starting for the door.

"And if they escape you make them more eager than ever to strike a blow at you and yours," put in Craig coolly. "No, let us get this thing straight. I didn't think it was as serious as this, but I'm prepared to meet any emergency."

"But, man," shouted Brixton, "you don't suppose anything in the world counts beside her, do you?"

"Exactly the point," urged Craig. "Save her and capture them—both at once."

"How can you?" fumed Brixton. "If you attempt to telephone from here, that fellow Janeff will overhear and give a warning."

Regardless of whether Janeff was listening or not, Kennedy was eagerly telephoning to the Woodrock central down in the village. He was using the transmitter and receiver that were connected with the iron tube which he had connected to the two regular house lines.

"Have the ferry held at any cost," he was ordering. "Don't let the next boat go out until Mr. Brixton gets there, under any circumstances. Now put that to them straight, central. You know Mr. Brixton has just a little bit of influence around here, and somebody's head will drop if they let that boat go out before he gets there."

"Humph!" ejaculated Brixton. "Much good that will do. Why, I suppose our friend Janeff down in the storeroom knows it all now. Come on, let's grab him."

Nevertheless there was no sound from the detectaphone which would indicate that he had overheard and was spreading the alarm. He was there yet, for we could hear him clear his throat once or twice.

"No," replied Kennedy calmly, "he knows nothing about it. I didn't use any ordinary means to prepare against the experts who have brought this situation about. That message you heard me send went out over what we call the 'phantom circuit.'"

"The phantom circuit?" repeated Brixton, chafing at the delay.

"Yes, it seems fantastic at first, I suppose," pursued Kennedy calmly; "but, after all, it is in accordance with the laws of electricity. It's no use fretting and fuming, Mr. Brixton. If Janeff can wait, we'll have to do so, too. Suppose we should start and this Kronski should change his plans at the last minute? How would we find it out? By telepathy? Believe me, sir, it is better to wait here a minute and trust to the phantom circuit than to mere chance."

"But suppose he should cut the line," I put in.

Kennedy smiled. "I have provided for that, Walter, in the way I installed the thing. I took good care that we could not be cut off that way. We can hear everything ourselves, but we cannot be overheard. He knows nothing. You see, I took advantage of the fact that additional telephones or so-called phantom lines can be superposed on existing physical lines. It is possible to obtain a third circuit from two similar metallic circuits by using for each side of this third circuit the two wires of each of the other circuits in multiple. All three circuits are independent, too.

"The third telephone current enters the wires of the first circuit, as it were, and returns along the wires of the second circuit. There are several ways of doing it. One is to use retardation or choke-coils bridged across the two metallic circuits at both ends, with taps taken from the middle points of each. But the more desirable method is the one you saw me install this afternoon. I introduced repeating-coils into the circuits at both ends. Technically, the third circuit is then taken off from the mid-points of the secondaries or line windings of these repeating coils.

"The current on a long-distance line is alternating in character, and it passes readily through a repeating-coil. The only effect it has on the transmission is slightly reducing the volume. The current passes into the repeating-coil, then divides and passes through the two line wires. At the other end the halves balance, so to speak. Thus, currents passing over a phantom circuit don't set up currents in the terminal apparatus of the side circuits. Consequently, a conversation carried on over the phantom circuit will not be heard in either side circuit, nor does a conversation on one side circuit affect the phantom. We could all talk at once without interfering with each other."

"At any other time I should be more than interested," remarked Brixton grimly, curbing his impatience to be doing something.

"I appreciate that, sir," rejoined Kennedy. "Ah, here it is. I have the central down in the village. Yes? They will hold the boat for us? Good. Thank you. The nine-o'clock train is five minutes late? Yes—what? Count Wachtmann's car is there? Oh, yes, the train is just pulling in. I see. Miss Brixton has entered his car alone. What's that? His chauffeur has started the car without waiting for the Count, who is coming down the platform?"

Instantly Kennedy was on his feet. He was dashing up the corridor and the stairs from the den and down into the basement to the little storeroom.

We burst into the place. It was empty. Janeff had cut the wires and fled. There was not a moment to lose. Craig hastily made sure that he had not discovered or injured the phantom circuit.

"Call the fastest car you have in your garage, Mr. Brixton," ordered Kennedy. "Hello, hello, central! Get the lodge at the Brixton estate. Tell them if they see the engineer Janeff going out to stop him. Alarm the watchman and have the dogs ready. Catch him at any cost, dead, or alive."

A moment later Brixton's car raced around, and we piled in and were off like a whirlwind. Already we could see lights moving about and hear the baying of dogs. Personally, I wouldn't have given much for Janeff's chances of escape.

As we turned the bend in the road just before we reached the ferry, we almost ran into two cars standing before the ferry house. It looked as though one had run squarely in front of the other and blocked it off. In the slip the ferry boat was still steaming and waiting.

Beside the wrecked car a man was lying on the ground groaning, while another man was quieting a girl whom he was leading to the waiting-room of the ferry.

Brixton, weak though he was from his illness, leaped out of our car almost before we stopped and caught the girl in his arms.

"Father!" she exclaimed, clinging to him.

"What's this?" he demanded sternly, eying the man. It was Wachtmann himself.

"Conrad saved me from that chauffeur of his," explained Miss Brixton. "I met him on the train, and we were going to ride up to the house together. But before Conrad could get into the car this fellow, who had the engine running, started it. Conrad jumped into another car that was waiting at the station. He overlook us and dodged in front so as to cut the chauffeur off from the ferry."

"Curse that villain of a chauffeur," muttered Wachtmann, looking down at the wounded man.

"Do you know who he is?" asked Craig with a searching glance at
Wachtmann's face.

"I ought to. His name is Kronski, and a blacker devil an employment bureau never furnished."

"Kronski? No," corrected Kennedy. "It is Professor Kumanova, whom you perhaps have heard of as a leader of the Red Brotherhood, one of the cleverest scientific criminals who ever lived. I think you'll have no more trouble negotiating your loan or your love affair, Count," added Craig, turning on his heel.

He was in no mood to receive the congratulations of the supercilious Wachtmann. As far as Craig was concerned, the case was finished, although I fancied from a flicker of his eye as he made some passing reference to the outcome that when he came to send in a bill to Brixton for his services he would not forget the high eyebrowed Count.

I followed in silence as Craig climbed into the Brixton car and explained to the banker that it was imperative that he should get back to the city immediately. Nothing would do but that the car must take us all the way back, while Brixton summoned another from the house for himself.

The ride was accomplished swiftly in record time. Kennedy said little. Apparently the exhilaration of the on-rush of cool air was quite in keeping with his mood, though for my part, I should have preferred something a little more relaxing of the nervous tension.

"We've been at it five days, now," I remarked wearily as I dropped into an easy chair in our own quarters. "Are you going to keep up this debauch?"

Kennedy laughed.

"No," he said with a twinkle of scientific mischief, "no, I'm going to sleep it off."

"Thank heaven!" I muttered.

"Because," he went on seriously, "that case interrupted a long series of tests I am making on the sensitiveness of selenium to light, and I want to finish them up soon. There's no telling when I shall be called on to use the information."

I swallowed hard. He really meant it. He was laying out more work for himself.

Next morning I fully expected to find that he had gone. Instead he was preparing for what he called a quiet day in the laboratory.

"Now for some REAL work," he smiled. "Sometimes, Walter, I feel that I ought to give up this outside activity and devote myself entirely to research. It is so much more important."

I could only stare at him and reflect on how often men wanted to do something other than the very thing that nature had evidently intended them to do, and on how fortunate it was that we were not always free agents.

He set out for the laboratory and I determined that as long as he would not stop working, neither would I. I tried to write. Somehow I was not in the mood. I wrote AT my story, but succeeded only in making it more unintelligible. I was in no fit condition for it.

It was late in the afternoon. I had made up my mind to use force, if necessary, to separate Kennedy from his study of selenium. My idea was that anything from the Metropolitan to the "movies" would do him good, and I had almost carried my point when a big, severely plain black foreign limousine pulled up with a rush at the laboratory door. A large man in a huge fur coat jumped out and the next moment strode into the room. He needed no introduction, for we recognised at once J. Perry Spencer, one of the foremost of American financiers and a trustee of the university.

With that characteristic directness which I have always thought accounted in large measure for his success, he wasted scarcely a word in coming straight to the object of his visit. "Professor Kennedy," he began, chewing his cigar and gazing about with evident interest at the apparatus Craig had collected in his warfare of science with crime, "I have dropped in here as a matter of patriotism. I want you to preserve to America those masterpieces of art and literature which I have collected all over the world during many years. They are the objects of one of the most curious pieces of vandalism of which I have ever heard. Professor Kennedy," he concluded earnestly, "could I ask you to call on Dr. Hugo Lith, the curator of my private museum, as soon as you can possibly find it convenient?"

"Most assuredly, Mr. Spencer," replied Craig, with a whimsical side glance at me that told without words that this was better relaxation to him than either the Metropolitan or the "movies." "I shall be glad to see Dr. Lith at any time—right now, if it is convenient to him."

The millionaire connoisseur consulted his watch. "Lith will be at the museum until six, at least. Yes, we can catch him there. I have a dinner engagement at seven myself. I can give you half an hour of the time before then. If you're ready, just jump into the car, both of you."

The museum to which he referred was a handsome white marble building, in Renaissance, fronting on a side street just off Fifth Avenue and in the rear of the famous Spencer house, itself one of the show places of that wonderful thoroughfare. Spencer had built the museum at great cost simply to house those treasures which were too dear to him to entrust to a public institution. It was in the shape of a rectangle and planned with special care as to the lighting.

Dr. Lith, a rather stout, mild-eyed German savant, plunged directly into the middle of things as soon as we had been introduced. "It is a most remarkable affair, gentlemen," he began, placing for us chairs that must have been hundreds of years old. "At first it was only those objects in the museum, that were green that were touched, like the collection of famous and historic French emeralds. But soon we found it was other things, too, that were missing—old Roman coins of gold, a collection of watches, and I know not what else until we have gone over the—"

"Where is Miss White?" interrupted Spencer, who had been listening somewhat impatiently.

"In the library, sir. Shall I call her?"

"No, I will go myself. I want her to tell her experience to Professor Kennedy exactly as she told it to me. Explain while I am gone how impossible it would be for a visitor to do one, to say nothing of all, of the acts of vandalism we have discovered."