the cellar,
with huge pipes running to every room in the house, great tin
monstrosities bigger round than a man's body, ending in openings in the
wall, with what they call 'registers' to let the heat in or shut it out
as they please. I didn't have the wretched contrivance removed or those
blessed 'registers' plastered up. I simply had them papered over when
the rooms were done up (there's one over there near that settee), and if
a man got into this house, he could get into that furnace thing and hide
in one of those flues until he got ready to crawl up it as easily as
not. It struck me that perhaps it would be as well for you to examine
that furnace and those flues before matters go any further."

"Of course it would. Great Scott! Sir Horace, why didn't you think to
tell me of this thing before?" said Narkom excitedly. "The fellow may be
in it at this minute. Come, show me the wretched thing."

"It's in the cellar. We shall have to go down the kitchen stairs, and I
haven't a light."

"Here's one," said Petrie, unhitching a bull's-eye from his belt and
putting it into Narkom's hand. "Better go with Sir Horace at once, sir.
Leave the door of the gallery open and the light on. Fish and me will
stand guard over the stuff till you come back, so in case the man is in
one of them flues and tries to bolt out at this end, we can nab him
before he can get to the windows."

"A good idea," commented Narkom. "Come on, Sir Horace. Is this the way?"

"Yes, but you'll have to tread carefully, and mind you don't fall over
anything. A good deal of my paraphernalia--bottles, retorts, and the
like--is stored in the little recess at the foot of the staircase, and
my assistant is careless and leaves things lying about."

Evidently the caution was necessary, for a minute or so after they had
disappeared behind the door leading to the kitchen stairway, Petrie and
his colleagues heard a sound as of something being overturned and
smashed, and laughed softly to themselves. Evidently, too, the danger of
the furnace had been grossly exaggerated by Sir Horace, for when, a few
minutes later, the door opened and closed, and Narkom's men, glancing
toward it, saw the figure of their chief reappear, it was plain that he
was in no good temper. His features were knotted up into a scowl, and he
swore audibly as he snapped the shutter over the bull's-eye and handed
it back to Petrie.

"Nothing worth looking into, superintendent?"

"No, not a thing!