efect in the paper--a loose fibre which had stuck to the thumb and been
detached by it from the paper, leaving a blank space where it had been.
But, on examining the paper under a low power of the microscope, I found
the surface to be perfect and intact. No loose fibre had been detached
from it, for if it had, the broken end or, at least, the groove in which
it had lain, would have been visible. The inference seemed to be that
the loose fibre had existed, not in the paper which was found in the
safe, but in the paper on which the original thumb-mark had been made.
Now, as far as I knew, there was only one undoubted thumb-print of
Reuben Hornby's in existence--the one in the 'Thumbograph.' At my
request, the 'Thumbograph' was brought to my chambers by Mrs. Hornby,
and, on examining the print of Reuben Hornby's left thumb, I perceived
on it a minute, S-shaped white space occupying a similar position to
that in the red thumb-mark; and when I looked at it through a powerful
lens, I could clearly see the little groove in the paper in which the
fibre had lain and from which it had been lifted by the inked thumb. I
subsequently made a systematic comparison of the marks in the two
thumb-prints; I found that the dimensions of the mark were
proportionally the same in each--that is to say, the mark in the
'Thumbograph' print had an extreme length of 26/1000 of an inch and an
extreme breadth of 14.5/1000 of an inch, while that in the red
thumb-mark was one-fortieth larger in each dimension, having an extreme
length of 26.65/1000 of an inch and an extreme breadth of 14.86/1000 of
an inch; that the shape was identical, as was shown by superimposing
tracings of greatly enlarged photographs of each mark on similar
enlargements of the other; and that the mark intersected the ridges of
the thumb-print in the same manner and at exactly the same parts in the
two prints."

"Do you say that--having regard to the facts which you have stated--it
is certain that the red thumb-mark is a forgery?"

"I do; and I also say that it is certain that the forgery was executed
by means of the 'Thumbograph.'"

"Might not the resemblances be merely a coincidence?"

"No. By the law of probabilities which Mr. Singleton explained so
clearly in his evidence, the adverse chances would run into untold
millions. Here are two thumb-prints made in different places and at
different times--an interval of many weeks intervening. Each of them
bears an accidental mar