There is a small room, reached by mounting a winding skeleton
stairway of iron, and there we were shown Mr. Wildred's apparatus. I
know something of chemistry myself, having had a fad that way when I was
a boy, and I could see that everything he had was straight and
above-board. A big fireplace in the room accounts for the sparks you saw
when you approached the house that day, and Mr. Wildred voluntarily
mentioned that there had been something wrong with the flues, so that
his experiments could not be conducted properly, and he had sent for an
expert to come down from London to look at everything. The man had been
expected on Christmas Eve, then on Christmas, as Mr. Wildred considered
the matter urgent, and finally arrived the day after. Mr. Wildred gave
us his address without waiting to be asked to do so. That accounted for
one more point in your story, sir--the man who was so anxiously looked
for, the man the butler seemed at first to take you to be.

"We then said we had been informed that screams or groans had been heard
issuing from his house on Christmas Day. Mr. Wildred laughed, remarking
that, judging from what he knew of our informant, he had been waiting
for us to come to that point.

"And he repeated the explanation which had been given you, asking us
also if we would care to see the scar (which was not yet quite healed)
made by the burning methylated spirit on the cook's foot or ankle.

"We thought it best to do as he suggested--indeed, if he had not, we
should have proposed the same course ourselves, for the sake of making
assurance doubly sure. The cook was sent for, a very handsome young
woman, sir, bright and ready with her answers. She described the
accident, and whipping off the shoe and stocking from the right foot,
showed us a red mark which spread from the ankle down over the whole
instep."

"So the cook was a handsome young woman, was she?" I asked,
suspiciously, remembering the face which had peered at me through the
narrow window by the door. "Had she great black eyes, a very white face,
and a quantity of dark hair?"

"She had, sir. That would describe her very well. A woman not more than
twenty-five or six, and evidently of a superior class."

I turned this bit of information over in my mind. To be sure, I could
not at the moment make anything of it apropos of the case in hand, but
afterwards I was to remember it under somewhat startling circumstances.

"So you see, sir," the detective co