"It didn't appear to
take long."

"It didn't. It was merely a matter of testing a hypothesis; and you
ought not to have to ask that question," he added, with mock severity,
"seeing that you had what turn out to have been all the necessary facts,
two days ago. But I will prepare a document and demonstrate to you
to-morrow morning."

* * * * *

"So Miller was successful in his quest," said Thorndyke, as we smoked
our morning pipes after breakfast. "The 'entire swag,' as he calls it,
was 'up the chimbly,' undisturbed."

He handed me a note which had been left, with the empty suit-case, by a
messenger, shortly before, and I was about to read it when an agitated
knock was heard at our door. The visitor, whom I admitted, was a rather
haggard and dishevelled elderly gentleman, who, as he entered, peered
inquisitively through his concave spectacles from one of us to the
other.

"Allow me to introduce myself, gentlemen," said he. "I am Professor
Poppelbaum."

Thorndyke bowed and offered a chair.

"I called yesterday afternoon," our visitor continued, "at Scotland
Yard, where I heard of your remarkable decipherment and of the
convincing proof of its correctness. Thereupon I borrowed the
cryptogram, and have spent the entire night in studying it, but I cannot
connect your solution with any of the characters. I wonder if you would
do me the great favour of enlightening me as to your method of
decipherment, and so save me further sleepless nights? You may rely on
my discretion."

"Have you the document with you?" asked Thorndyke.

The Professor produced it from his pocket-book, and passed it to my
colleague.

"You observe, Professor," said the latter, "that this is a laid paper,
and has no water-mark?"

"Yes, I noticed that."

"And that the writing is in indelible Chinese ink?"

"Yes, yes," said the savant impatiently; "but it is the inscription that
interests me, not the paper and ink."

"Precisely," said Thorndyke. "Now, it was the ink that interested me
when I caught a glimpse of the document three days ago. 'Why,' I asked
myself, 'should anyone use this troublesome medium'--for this appears to
be stick ink--'when good writing ink is to be had?' What advantages has
Chinese ink over writing ink? It has several advantages as a drawing
ink, but for writing purposes it has only one: it is quite unaffected
by wet. The obvious inference, then, was that this document was, for
some reas