simply applying to ordinary
life a few of those precepts of observation and deduction which I
advocated in that article. Is there anything else that 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 woman's ring there? Above
all, why should the second man write up the German word RACHE before
decamping? I confess that I cannot see any possible way of reconciling
all these facts."

My companion smiled approvingly.

"You sum up the difficulties of the situation succinctly and well," he
said. "There is much that is still obscure, though I have quite made up
my mind on the main facts. As to poor Lestrade's discovery it was simply
a blind intended to put the police upon a wrong track, by suggesting
Socialism and secret societies. It was not done by a German. The A, if
you noticed, was printed somewhat after the German fashion. Now, a real
German invariably prints in the Latin character, so that we may safely
say that this was not written by one, but by a clumsy imitator who
overdid his part. It was simply a ruse to divert inquiry into a wrong
channel. I'm not going to tell you much more of the case, Doctor. You
know a conjuror gets no credit when once he has explained his trick,