kness, not daring
to throw the light ahead of him for fear of betraying his presence, he
crawled on hands and knees. The draught of air through the passageway
was strong, and he had not proceeded far before he saw ahead faint
bars across the passage, not of light but of lesser darkness.

He decided there was some opening at the end of the passage, but could
not imagine what it might be. When he came up to it, however, the
solution was simple. Immediately under the peak of the roof tree, in a
side wall, was an opening in which was set a slatted shutter. This
admitted air, yet kept rain from beating in.

And in a flash, Jack realized to what ingenious lengths the original
owner of the house had gone in order to provide for his prisoner a
cell that would be virtually soundproof, yet have a supply of fresh
air. So high, too, was the opening of the passage in the cell that one
person could not reach it unaided.

Jubilant at his discovery and with a plan for putting it to use as a
means of escape, Jack, unable to turn about in the narrow passage,
worked his way backward until the projection of his feet into
emptiness warned him he had reached the room. Then he let himself down
and, when once more with his companions, explained the nature of his
discovery.

"We can lift that shutter out," he added, "and swing upward to the
roof tree. There is a cupola, an old-fashioned cupola, on this house,
as I remember it. Once we are on the roof, we can work our way to that
cupola and probably find a trapdoor leading down into the house. If
we decide that is too dangerous, we may be able to slide down the
gutters. Anyhow, once we are in the outer air and on the roof, we'll
be in a better position than here. Come on. I'll go up first, and then
help Captain Folsom up. Do the rest of you follow, and, as Frank is
the lightest, he ought to come last. The last man will have to be
pulled up with our belts, as he will have nobody to stand on."

CHAPTER XIII

THE TABLES TURNED

Negotiation of the entrance of all into the passageway was made
without accident, Tom Barnum staying until next to last and then, with
a number of belts buckled together, aiding Frank to gain the opening.
Meanwhile Jack, who was in the lead, found on closer investigation
that the slatted shutter obscuring the air port was on hinges and
caught with a rusted latch. To open the latch and unhinge the shutter
and then, by turning it sideways, pull it back into th