, point by point and detail by detail, and the two prints
were found to be identical in every respect.

"Now it has been proved by exact calculations--which calculations I have
personally verified---that the chance that the print of a single finger
of any given person will be exactly like the print of the same finger of
any other given person is as one to sixty-four thousand millions. That
is to say that, since the number of the entire human race is about
sixteen thousand millions, the chance is about one to four that the
print of a single finger of any one person will be identical with that
of the same finger of any other member of the human race.

"It has been said by a great authority--and I entirely agree with the
statement--that a complete, or nearly complete, accordance between two
prints of a single finger affords evidence requiring no corroboration
that the persons from whom they were made are the same.

"Now, these calculations apply to the prints of ordinary and normal
fingers or thumbs. But the thumb from which these prints were taken is
not ordinary or normal. There is upon it a deep but clean linear
scar--the scar of an old incised wound--and this scar passes across the
pattern of the ridges, intersecting the latter at certain places and
disturbing their continuity at others. Now this very characteristic scar
is an additional feature, having a set of chances of its own. So that we
have to consider not only the chance that the print of the prisoner's
left thumb should be identical with the print of some other person's
left thumb--which is as one to sixty-four thousand millions--but the
further chance that these two identical thumb-prints should be traversed
by the impression of a scar identical in size and appearance, and
intersecting the ridges at exactly the same places and producing
failures of continuity in the ridges of exactly the same character. But
these two chances, multiplied into one another, yield an ultimate chance
of about one to four thousand trillions that the prisoner's left thumb
will exactly resemble the print of some other person's thumb, both as to
the pattern and the scar which crosses the pattern; in other words such
a coincidence is an utter impossibility."

Sir Hector Trumpler took off his glasses and looked long and steadily at
the jury as though he should say, "Come, my friends; what do you think
of that?" Then he sat down with a jerk and turned towards Anstey and
Thorndyke with