such a gun consists in impelling the projectile by the magnetic action of a solenoid, the sectional coils or helices of which are supplied with current through devices actuated by the projectile itself. In other words, the sections of helices of the solenoid produce an accelerated motion of the projectile by acting successively on it, after a principle involved in the construction of electro-magnetic rock drills and dispatch tubes.
"All projectiles used in this gun of Fortescue's evidently must have magnetic properties and projectiles of iron or containing large portions of iron are necessary. You see, many coils are wound around the barrel of the gun. As the projectile starts it does so under the attraction of those coils ahead which the current makes temporary magnets. It automatically cuts off the current from those coils that it passes, allowing those further on only to attract it, and preventing those behind from pulling it back."
He paused to study the scraps of plans. "Fortescue had evidently also worked out a way of changing the poles of the coils as the projectile passed, causing them then to repel the projectile, which must have added to its velocity. He seems to have overcome the practical difficulty that in order to obtain service velocities with service projectiles an enormous number of windings and a tremendously long barrel are necessary as well as an abnormally heavy current beyond the safe carrying capacity of the solenoid which would raise the temperature to a point that would destroy the coils."
He continued turning over the prints and notes in the drawer. When he finished, he looked up at us with an expression that indicated that he had merely satisfied himself of something he had already suspected.
"You were right, Burke," he said. "The final plans are gone."
Burke, who, in the meantime, had been telephoning about the city in a vain effort to locate Baron Kreiger, both at such banking offices in Wall Street as he might be likely to visit and at some of the hotels most frequented by foreigners, merely nodded. He was evidently at a loss completely how to proceed.
In fact, there seemed to be innumerable problems—to warn Baron Kreiger, to get the list of the assassinations, to guard Miss Lowe against falling into the hands of her anarchist friends again, to find the murderer of Fortescue, to prevent the use of the electro-magnetic gun, and, if possible, to seize the anarchists before they had a chance to carry further their plans.
"There is nothing more that we can do here," remarked Craig briskly, betraying no sign of hesitation. "I think the best thing we can do is to go to my own laboratory. There at least there is something I must investigate sooner or later."
No one offering either a suggestion or an objection, we four again entered our cab. It was quite noticeable now that the visit had shaken Paula Lowe, but Kennedy still studiously refrained from questioning her, trusting that what she had seen and heard, especially Burke's report as to Baron Kreiger, would have its effect.
Like everyone visiting Craig's laboratory for the first time, Miss Lowe seemed to feel the spell of the innumerable strange and uncanny instruments which he had gathered about him in his scientific warfare against crime. I could see that she was becoming more and more nervous, perhaps fearing even that in some incomprehensible way he might read her own thoughts. Yet one thing I did not detect. She showed no disposition to turn back on the course on which she had entered by coming to us in the first place.
Kennedy was quickly and deftly testing the stub of the little thin, gold-tipped cigarette.
"Excessive smoking," he remarked casually, "causes neuroses of the heart and tobacco has a specific affinity for the coronary arteries as well as a tremendous effect on the vagus nerve. But I don't think this was any ordinary smoke."
He had finished his tests and a quiet smile of satisfaction flitted momentarily over his face. We had been watching him anxiously, wondering what he had found.
As he looked up he remarked to us, with his eyes fixed on Miss Lowe, "That was a ladies' cigarette. Did you notice the size? There has been a woman in this case—presumably."
The girl, suddenly transformed by the rapid-fire succession of discoveries, stood before us like a specter.
"The 'Group,' as anarchists call it," pursued Craig, "is the loosest sort of organization conceivable, I believe, with no set membership, no officers, no laws—just a place of meeting with no fixity, where the comrades get together. Could you get us into the inner circle, Miss Lowe?"
Her only answer was a little suppressed scream. Kennedy had asked the question merely for its effect, for it was only too evident that there was no time, even if she could have managed it, for us to play the "stool pigeon."
Kennedy, who had been clearing up the materials he had used in the analysis of the cigarette, wheeled about suddenly. "Where is the headquarters of the inner circle?" he shot out.
Miss Lowe hesitated. That had evidently been one of the things she had determined not to divulge.
"Tell me," insisted Kennedy. "You must!"
If it had been Burke's bulldozing she would never have yielded. But as she looked into Kennedy's eyes she read there that he had long since fathomed the secret of her wildly beating heart, that if she would accomplish the purpose of saving the Baron she must stop at nothing.
"At—Maplehurst," she answered in a low tone, dropping her eyes from his penetrating gaze, "Professor Annenberg's home—out on Long Island."
"We must act swiftly if we are to succeed," considered Kennedy, his tone betraying rather sympathy with than triumph over the wretched girl who had at last cast everything in the balance to outweigh the terrible situation into which she had been drawn. "To send Miss Lowe for that fatal list of assassinations is to send her either back into the power of this murderous group and let them know that she has told us, or perhaps to involve her again in the completion of their plans."
She sank back into a chair in complete nervous and physical collapse, covering her face with her hands at the realization that in her new-found passion to save the Baron she had bared her sensitive soul for the dissection of three men whom she had never seen before.
"We must have that list," pursued Kennedy decisively. "We must visit
Annenberg's headquarters."
"And I?" she asked, trembling now with genuine fear at the thought that he might ask her to accompany us as he had on our visit to Fortescue's laboratory that morning.
"Miss Lowe," said Kennedy, bending over her, "you have gone too far now ever to turn back. You are not equal to the trip. Would you like to remain here? No one will suspect. Here at least you will be safe until we return."
Her answer was a mute expression of thanks and confidence.
CHAPTER III
THE MURDER SYNDICATE
Quickly now Craig completed his arrangements for the visit to the headquarters of the real anarchist leader. Burke telephoned for a high-powered car, while Miss Lowe told frankly of the habits of Annenberg and the chances of finding his place unguarded, which were good in the daytime. Kennedy's only equipment for the excursion consisted in a small package which he took from a cabinet at the end of the room, and, with a parting reassurance to Paula Lowe, we were soon speeding over the bridge to the borough across the river.
We realized that it might prove a desperate undertaking, but the crisis was such that it called for any risk.
Our quest took us to a rather dilapidated old house on the outskirts of the little Long Island town. The house stood alone, not far from the tracks of a trolley that ran at infrequent intervals. Even a hasty reconnoitering showed that to stop our motor at even a reasonable distance from it was in itself to arouse suspicion.
Although the house seemed deserted, Craig took no chances, but directed the car to turn at the next crossroad and then run back along a road back of and parallel