cabinet placed in relatively the same position a similar cabinet
occupies in Mr. Vandam's private seance-room in the Vandam
mansion.

"One night, Mr. Jameson and myself were visiting Mr. Vandam. At
precisely twelve-thirty we heard most unaccountable rappings from
that cabinet. I particularly noted the position of the cabinet.
Back of it ran a hallway. That is duplicated here. Back of this
cabinet is a hallway. I had heard of these rappings before we
went, but was afraid that it would be impossible for me to catch
the ghost red handed. There is a limit to what you can do the
first time you enter a man's house, and, besides, that was no
time to arouse suspicion in the mind of anyone. But science has a
way out of every dilemma. I determined to learn something of
these rappings."

Craig paused and glanced first at Farrington, then at Mrs.
Popper, and then at Mr. Vandam.

"Mr. Jameson," he resumed, "will escort the doctor, the
inspector, Mr. Farrington, Mrs. Popper, and Mr. Vandam into my
imitation hall of the Vandam mansion. I want each of you in turn
to tiptoe up that hall to a spot indicated on the wall, back of
the cabinet, and strike that spot several sharp blows with your
knuckles."

I did as Craig instructed tiptoeing up myself first so that they
could not mistake his meaning. The rest followed separately, and
after a moment we returned silently in suppressed excitement to
the room.