the judge; and _his_ face relaxed into a dry smile, while the
jury broke out into unconcealed grins.

"It was evident to me," continued Thorndyke, "that the experts would be
unable to distinguish the real from the forged thumb-prints, and, that
being so, that they would look for some collateral evidence to guide
them. I, therefore, supplied that collateral evidence. Now, if ten
prints are taken, without special precautions, from a single finger, it
will probably happen that no two of them are exactly alike; for the
finger being a rounded object of which only a small part touches the
paper, the impressions produced will show little variations according to
the part of the finger by which the print is made. But a stamp such as I
have used has a flat surface like that of a printer's type, and, like a
type, it always prints the same impression. It does not reproduce the
finger-tip, but a particular print of the finger, and so, if ten prints
are made with a single stamp, each print will be a mechanical repetition
of the other nine. Thus, on a sheet bearing twenty finger-prints, of
which ten were forgeries made with a single stamp, it would be easy to
pick out the ten forged prints by the fact that they would all be
mechanical repetitions of one another; while the genuine prints could be
distinguished by the fact of their presenting trifling variations in the
position of the finger.

"Anticipating this line of reasoning, I was careful to make each print
with a different stamp and each stamp was made from a different
thumb-print, and I further selected thumb-prints which varied as widely
as possible when I made the stamps. Moreover, when I made the real
thumb-prints, I was careful to put the thumb down in the same position
each time as far as I was able; and so it happened that, on the sheet
submitted to the experts, the real thumb-prints were nearly all alike,
while the forgeries presented considerable variations. The instances in
which the witnesses were quite certain were those in which I succeeded
in making the genuine prints repeat one another, and the doubtful cases
were those in which I partially failed."

"Thank you, that is quite clear," said the judge, with a smile of deep
content, such as is apt to appear on the judicial countenance when an
expert witness is knocked off his pedestal. "We may now proceed, Mr.
Anstey."

"You have told us," resumed Anstey, "and have submitted proofs, that it
is possible to forge a t