mind, sir," he began, bending forward as soon
as we were seated, and speaking in a tone but a little above a
whisper, "that you shall not have to ask me twice what troubles
me. I took you for some one else yesterday evening. That troubles
me."

"That mistake?"

"No. That some one else."

"Who is it?"

"I don't know."

"Like me?"

"I don't know. I never saw the face. The left arm is across the
face, and the right arm is waved. Violently waved. This way."

I followed his action with my eyes, and it was the action of an
arm gesticulating with the utmost passion and vehemence: "For God's
sake clear the way!"

"One moonlight night," said the man, "I was sitting here, when
I heard a voice cry, 'Halloa! Below there!' I started up, looked
from that door, and saw this Some one else standing by the red
light near the tunnel, waving as I just now showed you. The voice
seemed hoarse with shouting, and it cried, 'Look out! Look out!'
And then again, 'Halloa! Below there! Look out!' I caught up my
lamp, turned it on red, and ran towards the figure, calling, 'What's
wrong? What has happened? Where?' It stood just outside the blackness
of the tunnel. I advanced so close upon it that I wondered at its
keeping the sleeve across its eyes. I ran right up at it, and had
my hand stretched out to pull the sleeve away, when it was gone."

"Into the tunnel?" said I.

"No. I ran on into the tunnel, five hundred yards. I stopped and
held my lamp above my head, and saw the figures of the measured
distance, and saw the wet stains stealing down the walls and trickling
through the arch. I ran out again, faster than I had run in (for I
had a mortal abhorrence of the place upon me), and I looked all
round the red light with my own red light, and I went up the iron
ladder to the gallery atop of it, and I came down again, and ran
back here. I telegraphed both ways, 'An alarm has been given. Is
anything wrong?' The answer came back, both ways, 'All well.'"

Resisting the slow touch of a frozen finger tracing out my spine, I
showed him how that this figure must be a deception of his sense of
sight, and how that figures, originating in disease of the delicate
nerves that minister to the functions of the eye, were known to have
often troubled patients, some of whom had become conscious of the
nature of their affliction, and had even proved it by experiments
upon themselves. "As to an imaginary cry," said I, "do but listen
for a moment to th