shape of the
gallows reared itself aloft in the gloom; only now I could see that it
was not a gallows at all. For affixed to the top cross-bar was a
large, bottomless glass basin, inside which was a glass bulb that
glowed with a strange green light; and in the heart of the bulb a
bright spot of red.

It was all clear enough so far. The peculiar sound that filled the air
was the hum of the interrupter; the bulb was, of course, a Crookes
tube, and the red spot inside it, the glowing red-hot disc of the
anti-cathode. Clearly an X-ray photograph was being made; but of what?
I strained my eyes, peering into the gloom at the foot of the gallows,
but though I could make out an elongated object lying on the floor
directly under the bulb, I could not resolve the dimly seen shape into
anything recognizable. Presently, however, Dr. Norbury supplied the
clue.

"I am rather surprized," said he, "that you chose so composite an
object as a mummy to begin on. I should have thought that a simpler
object, such as a coffin or a wooden figure, would have been more
instructive."

"In some ways it would," replied Thorndyke, "but the variety of
materials that the mummy gives us has its advantages. I hope your
father is not ill, Miss Bellingham."

"He is not at all well," said Ruth, "and we agreed that it was better
for me to come alone. I knew Herr Lederbogen quite well. He stayed
with us for a time when he was in England."

"I trust," said Dr. Norbury, "that I have not troubled you for nothing.
Herr Lederbogen speaks of 'our erratic English friend with the long
name that I can never remember,' and it seemed to me that he might be
referring to your uncle."

"I should hardly have called my uncle erratic," said Ruth.

"No, no. Certainly not," Dr. Norbury agreed hastily. "However, you
shall see the letter presently and judge for yourself. We mustn't
introduce irrelevant topics while the experiment is in progress, must
we, Doctor?"

"You had better wait until we have finished," said Thorndyke, "because
I am going to turn out the light. Switch off the current, Polton."

The green light vanished from the bulb, the hum of the interrupter
swept down an octave or two and died away. Then Thorndyke and Dr.
Norbury rose from their chairs and went toward the mummy, which they
lifted tenderly while Polton drew from beneath it what presently turned
out to be a huge black paper envelope. The single glow-lamp was
switched off, leav