myself that De Guerre cared greatly for his wife, except perhaps to be jealous of anyone else having her. He was too attentive to Elsa Hoffman, and she, in turn, was not of the type to care much for anyone. As for Dr. Preston, although he seemed to have had a friendship for Rawaruska, I could not exactly fit him into the scheme of things.
We proceeded up the bay on the Sylvania, but were able to discover nothing further that night. As we left the ship at the dock in the morning we ran across Wade, who was quietly directing a dozen or so of his men.
"Any trace yet of the Invincible?" asked Craig, stopping in an unostentatious corner.
The customs man shook his head gravely. "Not yet," he replied. "But I'm not discouraged. If we miss it here in the customs inspection it will be sure to turn up later. There's a shady jeweler on Fifth Avenue, Margot, who knows these Antwerp people pretty well. I have a man working there, a diamond cutter, and other agents in the trade. Oh, I'll hear about it soon enough, if it is here. Only I'd like to have done something spectacular, something that would count for me at Washington. Have you found out anything?"
Briefly Kennedy told him some of the scattered facts we had discovered, just enough to satisfy him without taking him into our confidence.
"I'm going to be busy in the laboratory, Walter," remarked Kennedy as our taxicab extricated itself from the ruck of the river-front streets. "I don't know that there is anything that you can do—except—well, yes. I wish you'd try to keep an eye on some of these people—that maid, Cecilie, especially."
We had learned that De Guerre was to stop at the Vanderveer and, later in the morning, I dropped into the hotel and glanced over the register. De Guerre was registered there and Cecilie had a little room, also, pending the disposal he would make of her. Miss Hoffman had rooms of her own, which she had evidently re-engaged, with a family in a residential street not far from the hotel.
The clerk told me that De Guerre was out, but that the maid had returned after having been out alone, for a short time, also. The lobby of the Vanderveer was fairly crowded with people by this time, and I found no difficulty in keeping in the background and still seeing pretty much everything that went on.
It was rather tame, however, and I was still debating whether I should not do something active, when I happened to glance up and catch sight of a familiar face. It was Dr. Preston making inquiries for someone of the room clerk. I dodged back of a pillar and waited, covering myself with an early morning war extra that repeated the news of the night before.
A few moments later, Preston, who had received an answer from whomever he was calling, edged his way toward one of the deserted little reception rooms near a side carriage entrance. Carefully, I trailed him.
It was some minutes before I could make up my mind to risk passing the door of the little parlor and being discovered, but I was growing impatient. As I glanced in I was astonished to see him talking earnestly to Cecilie. I did not dare stop, for fear one or the other might look up, but I could see that Preston was eagerly questioning her. Her face was averted from me and I could not read even her expression. The passageway was deserted, and if I paused I would inevitably attract attention. So I kept on, turning instinctively in the labyrinth and coming back to the lobby, where I found a position near the telephone booths which gave me a concealed view at least of the door of the parlor around an angle. I waited.
Perhaps five minutes passed. Then Cecilie and Dr. Preston suddenly emerged from the reception room. Evidently the maid was anxious to get away, perhaps afraid to be seen with him. With a word, she almost ran down the corridor in the direction of the rear elevators, and Preston, with a queer look on his face, came slowly toward me.
Instinctively I drew back into a telephone booth; then it occurred to me that if I emerged just as he passed he would not be likely to suspect anything, and I might have a chance to study him.
I did so, and was quite amused at the look of surprise on his face as I greeted him. Still, I do not think he thought I was shadowing him. We paused for a moment on the street, after a conventional exchange of remarks about the tragedy to poor little Rawaruska.
"That Miss Hoffman seems to be a very capable woman," I remarked, by way of dragging the conversation into channels into which it seemed unlikely to drift naturally.
"Y-yes," he agreed, as I caught a sidelong glance from the corner of his eye. "I believe she has had a rather checkered career. I understand that she was a nurse, a trained nurse, once."
There was something about the remark that impressed me. It was made deliberately, I fancied. What his purpose was, I could not fathom, but I felt that in the instant while he had hesitated he had debated and made up his mind to say it.
My face betraying nothing to his searching glance, he pulled hastily at his watch. "I'm going downtown on the subway—to clear up some of the muss that this European business has got me in with my bankers," he said quickly. "I'd be glad to have you call on me at any time at the Charlton, just up the avenue a bit. Good-day, sir. I'm glad to have met you. Drop in on me."
He was gone, scarcely waiting for me to reply, leaving me to wonder what was the cause of his strange actions.
Mechanically I looked at my own watch and decided that I had left Craig undisturbed long enough.
Chapter IX
The Twilight Sleep
As I entered the laboratory I saw before him a peculiar, telescope-like instrument, at one end of which, in a jar of oxygen, something was burning with a brilliant, penetrating flame.
He paused in his work and I hastened to tell him of the peculiar experience I had had in the forenoon. But he said nothing, even at the significant actions of Dr. Preston.
"How about those things you found in the maid's room?" I asked at length. "Do they explain Rawaruska's death?"
"The trouble with them," he replied, thoughtfully shaking his head, "is that the effects of such things last only for a short time. They might have been used at first—but there was something used afterward."
"Something afterward?" I repeated, keenly interested, and fingering the telescope-like arrangement curiously. "What's this?"
"One of the new quartz lens spectroscopes used by Dr. Dobbie of the English Government laboratories," he answered briefly. "I think chemists, police officials, coroners and physicians are going to find it most valuable. You see, by throwing the ultra-violet part of the spectrum from a source of light as I obtain from the sparking of iron in oxygen through the lenses of a quartz spectroscope, the lines of many dangerous drugs, especially of the alkaloids, can be distinctly and quickly located in the spectrum. Each drug produces a characteristic kind of line. We use a quartz lens because glass cuts off the ultra-violet rays. Why, even the most minute particle of poison can be detected in this revolutionary fashion."
He had resumed squinting through the spectroscope.
"Well," I asked, "do you find anything there?"
He had evidently been using the piece of gauze on which he had preserved the liquid from the peculiar little marks on Rawaruska's spine.
"Narcophin," he muttered, still squinting.
"Narcophin?" I repeated. "What is that?"
