stance, an ancient block
of wood is more or less transparent to the rays than a new block of the
same size."

"And of what use would the knowledge be, if it were obtained?"

"I can't say. Experiments are made to obtain knowledge without regard
to its utility. The use appears when the knowledge has been acquired.
But in this case, if it should be possible to determine the age of any
organic substance by its reaction to X-rays, the discovery might be
found of some value in legal practise--as in demonstrating a new seal
on an old document, for instance. But I don't know whether Thorndyke
has anything definite in view; I only know that the preparations have
been on a most portentous scale."

"How do you mean?"

"In regard to size. When I went into the workshop yesterday morning, I
found Polton erecting a kind of portable gallows about nine feet high,
and he had just finished varnishing a pair of enormous wooden trays
each over six feet long. It looked as if he and Thorndyke were
contemplating a few private executions with subsequent post-mortems on
the victims."

"What a horrible suggestion!"

"So Polton said, with his quaint, crinkly smile. But he was mighty
close about the use of the apparatus all the same. I wonder if we
shall see anything of the experiments, when we get there. This is
Museum Street, isn't it?"

"Yes." As she spoke, she lifted the flap of one of the little windows
in the back of the cab and peered out. Then, closing it with a quiet,
ironic smile, she said:

"It is all right; he hasn't missed us. It will be quite a nice little
change for him."

The cab swung round into Great Russell Street, and, glancing out as it
turned, I saw another hansom following; but before I had time to
inspect its solitary passenger, we drew up at the Museum gates.

The gate porter, who seemed to expect us, ushered us up the drive to
the great portico and into the Central Hall, where he handed us over to
another official.

"Doctor Norbury is in one of the rooms adjoining the Fourth Egyptian
Room," the latter stated in answer to our inquiries: and, providing
himself with a wire-guarded lantern, he prepared to escort us thither.

Up the great staircase, now wrapped in mysterious gloom, we passed in
silence with bitter-sweet memories of that day of days when we had
first trodden its steps together; through the Central Saloon, the
Medieval Room and the Asiatic Saloon, and so into the long range of the
Ethn