hink 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