"Impossible!" Steel cried. "The blind may be an accident, so might the
fading of the distemper. But the furniture, the engravings, the fittings
generally--"

"Are all capable of an explanation, which we shall arrive at with
patience."

"Can we arrive at the number over the door with patience?"

"Exactly what I was coming to. I noticed an old pair of steps in the back
sitting-room. Would you mind placing them against the fanlight for me?"

David complied readily enough. He was growing credulous and interested in
spite of himself. At Bell's instigation he placed the steps before the
fanlight and mounted them. Over his head were the figures 218 in
elongated shape and formed in white porcelain.

"Now then," Bell said, slowly. "Take this pocket-knife, apply the blade
to the _right-hand_ lower half of the bottom of the 8--to half the small
O, in fact--and I shall be extremely surprised if the quarter section
doesn't come away from the glass of the fanlight, leaving the rest of the
figure intact. Very gently, please. I want you to convince yourself that
the piece comes away because it is broken, and not because the pressure
has cracked it. Now then."

The point of the knife was hardly under the edge of the porcelain before
the segment of the lower circle dropped into Steel's hand. He could feel
the edges of the cement sticking to his fingers. As yet the full force of
the discovery was not apparent to him.