hall do. You know that skylight which overlooks the central
hall? We will leave the electric lights in the hall, and we will keep
watch in the lumber-room, you and I, and solve the mystery for
ourselves. If our mysterious visitor is doing four stones at a time,
he has four still to do, and there is every reason to think that he
will return tonight and complete the job."

"Excellent!" I cried.

"We will keep our own secret, and say nothing either to the police or
to Simpson. Will you join me?"

"With the utmost pleasure," said I; and so it was agreed.

It was ten o'clock that night when I returned to the Belmore Street
Museum. Mortimer was, as I could see, in a state of suppressed nervous
excitement, but it was still too early to begin our vigil, so we
remained for an hour or so in his chambers, discussing all the
possibilities of the singular business which we had met to solve. At
last the roaring stream of hansom cabs and the rush of hurrying feet
became lower and more intermittent as the pleasure-seekers passed on
their way to their stations or their homes. It was nearly twelve when
Mortimer led the way to the lumber-room which overlooked the central
hall of the museum.

He had visited it during the day, and had spread some sacking so that
we could lie at our ease, and look straight down into the museum. The
skylight was of unfrosted glass, but was so covered with dust that it
would be impossible for anyone looking up from below to detect that he
was overlooked. We cleared a small piece at each corner, which gave us
a complete view of the room beneath us. In the cold white light of the
electric lamps everything stood out hard and clear, and I could see the
smallest detail of the contents of the various cases.

Such a vigil is an excellent lesson, since one has no choice but to
look hard at those objects which we usually pass with such half-hearted
interest. Through my little peep hole I employed the hours in studying
every specimen, from the huge mummy-case which leaned against the wall
to those very jewels which had brought us there, gleaming and sparkling
in their glass case immediately beneath us. There was much precious
gold-work and many valuable stones scattered through the numerous
cases, but those wonderful twelve which made up the urim and thummim
glowed and burned with a radiance which far eclipsed the others. I
studied in turn the tomb-pictures of Sicara, the friezes from Karnak,
the sta