effectually aroused from my reverie.

Two men, both tall, stood in the shadow of a doorway on the Opposite
side of the street, staring intently up at the Museum windows. It
was a tropically hot afternoon and they stood in deepest shadow. No
one else was in Orchard Street--that odd little backwater--at the
time, and they stood gazing upward intently and gave me not even a
passing glance.

But I knew one for the Oriental visitor of the morning, and despite
broad noonday and the hum of busy London about me, my blood seemed
to turn to water. I stood rooted to the spot, held there by a most
surprising horror.

For the gray-bearded figure of the other watcher was one I could
never forget; its benignity was associated with the most horrible
hours of my life, with deeds so dreadful that recollection to this
day sometimes breaks my sleep, arousing me in the still watches,
bathed in a cold sweat of fear.

It was Hassan of Aleppo!

If he saw me, if either of them saw me, I cannot say. What I should
have done, what I might have done it is useless to speak of here--for
I did nothing. Inert, thralled by the presence of that eerie,
dreadful being, I watched them leave the shadow of the doorway and
pace slowly on with their dignified Eastern gait.

Then, knowing how I had failed in my plain duty to my fellow-men--how,
finding a serpent in my path, I had hesitated to crush it,
had weakly succumbed to its uncanny fascination--I made my way
round to the door of the Museum.

CHAPTER XIII

THE WHITE BEAM

That night the deviltry began. Mr. Mostyn found himself wholly
unable to sleep. Many relics have curious histories, and the
experienced archaeologist becomes callous to that uncanniness which
seems to attach to some gruesome curios. But the slipper of the
Prophet was different. No mere ghostly menace threatened its
holders; an avenging scimitar followed those who came in contact
with it; gruesome tragedies, mutilations, murders, had marked its
progress throughout.

The night was still--as still as a London night can be; for there
is always a vague murmuring in the metropolis as though the
sleeping city breathed gently and sometimes stirred in its sleep.

Then, distinct amid these usual nocturnal noises, rose another,
unaccountable sound, a muffled crash followed by a musical tinkling.

Mostyn sprang up in bed, drew on a dressing-gown, and took from the
small safe at his bed-head the Museum keys and a loade