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.”