Thorndyke made a note of the fact in his book); "at any rate, Mrs.
Hornby became possessed of one of these appliances and proceeded to fill
it with the thumb-prints of her friends, including her two nephews. Now
it happened that the detective in charge of this case called yesterday
at Mr. Hornby's house when the latter was absent from home, and took the
opportunity of urging her to induce her husband to consent to have the
thumb-prints of her nephews taken for the inspection of the experts at
Scotland Yard. He pointed out that the procedure was really necessary,
not only in the interests of justice but in the interests of the young
men themselves, who were regarded with considerable suspicion by the
police, which suspicion would be completely removed if it could be shown
by actual comparison that the thumb-print could not have been made by
either of them. Moreover, it seemed that both the young men had
expressed their willingness to have the test applied, but had been
forbidden by their uncle. Then Mrs. Hornby had a brilliant idea. She
suddenly remembered the 'Thumbograph,' and thinking to set the question
at rest once for all, fetched the little book and showed it to the
detective. It contained the prints of both thumbs of Mr. Reuben (among
others), and, as the detective had with him a photograph of the
incriminating mark, the comparison was made then and there; and you may
imagine Mrs. Hornby's horror and amazement when it was made clear that
the print of her nephew Reuben's left thumb corresponded in every
particular with the thumb-print that was found in the safe.

"At this juncture Mr. Hornby arrived on the scene and was, of course,
overwhelmed with consternation at the turn events had taken. He would
have liked to let the matter drop and make good the loss of the diamonds
out of his own funds, but, as that would have amounted practically to
compounding a felony, he had no choice but to prosecute. As a result, a
warrant was issued for the arrest of Mr. Reuben, and was executed this