puzzles you?"

"The finger nails and the Trichinopoly," I suggested.

"The writing on the wall was done with a man's forefinger
dipped in blood. My glass allowed me to observe that the
plaster was slightly scratched in doing it, which would not
have been the case if the man's nail had been trimmed.
I gathered up some scattered ash from the floor. It was dark
in colour and flakey -- such an ash as is only made by a
Trichinopoly. I have made a special study of cigar ashes --
in fact, I have written a monograph upon the subject.
I flatter myself that I can distinguish at a glance the ash of
any known brand, either of cigar or of tobacco. It is just
in such details that the skilled detective differs from the
Gregson and Lestrade type."

"And the florid face?" I asked.

"Ah, that was a more daring shot, though I have no doubt that
I was right. You must not ask me that at the present state
of the affair."

I passed my hand over my brow. "My head is in a whirl,"
I remarked; "the more one thinks of it the more mysterious it
grows. How came these two men -- if there were two men --
into an empty house? What has become of the cabman who drove
them? How could one man compel another to take poison?
Where did the blood come from? What was the object of the
murderer, since robbery had no part in it? How came the