he came to one which he
apparently recognised, and said--

"Yes, m'lord; this is the book. Mrs. Hornby showed me the thumb-prints
of various members of the family, and then found those of the two
nephews. I compared them with the photograph that I had with me and
discovered that the print of the left thumb of Reuben Hornby was in
every respect identical with the thumb-print shown in the photograph."

"What did you do then?"

"I asked Mrs. Hornby to lend me the 'Thumbograph' so that I might show
it to the Chief of the Finger-print Department, to which she consented.
I had not intended to tell her of my discovery, but, as I was leaving,
Mr. Hornby arrived home, and when he heard of what had taken place, he
asked me why I wanted the book, and then I told him. He was greatly
astonished and horrified, and wished me to return the book at once. He
proposed to let the whole matter drop and take the loss of the diamonds
on himself; but I pointed out that this was impossible as it would
practically amount to compounding a felony. Seeing that Mrs. Hornby was
so distressed at the idea of her book being used in evidence against her
nephew, I promised her that I would return it to her if I could obtain a
thumb-print in any other way.

"I then took the 'Thumbograph' to Scotland Yard and showed it to Mr.
Singleton, who agreed that the print of the left thumb of Reuben Hornby
was in every respect identical with the thumb-print on the paper found
in the safe. On this I applied for a warrant for the arrest of Reuben
Hornby, which I executed on the following morning. I told the prisoner
what I had promised Mrs. Hornby, and he then offered to allow me to take
a print of his left thumb so that his aunt's book should not have to be
used in evidence."

"How is it, then," asked the judge, "that it has been put in evidence?"

"It has been put in by the defence, my lord," said Sir Hector Trumpler.

"I see," said the judge. "'A hair of the dog that bit him.' The
'Thumbograph' is to be applied as a remedy on the principle that
_similia similibus curantur_. Well?"

"When I arrested him, I administered the usual caution, and the prisoner
then said, 'I am innocent. I know nothing about the robbery.'"

The counsel for the prosecution sat down, and Anstey rose to
cross-examine.

"You have told us," said he, in his clear musical voice, "that you found
at the bottom of the safe two rather large drops of a dark fluid which
you considered to be