s gives
a more perfect image, we use one of very long focus--thirty-six
inches--for copying the same size or for slight magnification or
reduction."

"Are you going to magnify these cheques?" Mr. Britton asked.

"Not in the first place," replied Thorndyke. "For convenience and speed
I am going to photograph them half-size, so that six cheques will go on
one whole plate. Afterwards we can enlarge from the negatives as much as
we like. But we should probably enlarge only the signatures in any
case."

The precious bag was now opened and the twenty-three cheques brought out
and laid on the bench in a consecutive series in the order of their
dates. They were then fixed by tapes--to avoid making pin-holes in
them--in batches of six to small drawing boards, each batch being so
arranged that the signatures were towards the middle. The first board
was clamped to the easel, the latter was slid along its guides until
the pointer stood at / 2 on the long-focus scale and Thorndyke proceeded
to focus the camera with the aid of a little microscope that Polton had
made for the purpose. When Mr. Britton and I had inspected the
exquisitely sharp image on the focusing-screen through the microscope,
Polton introduced the plate and made the first exposure, carrying the
dark-slide off to develop the plate while the next batch of cheques was
being fixed in position.

In his photographic technique, as in everything else, Polton followed as
closely as he could the methods of his principal and instructor; methods
characterized by that unhurried precision that leads to perfect
accomplishment. When the first negative was brought forth, dripping,
from the dark-room, it was without spot or stain, scratch or pin-hole;
uniform in colour and of exactly the required density. The six cheques
shown on it--ridiculously small in appearance, though only reduced to
half-length--looked as clear and sharp as fine etchings; though, to be
sure, my opportunity for examining them was rather limited, for Polton
was uncommonly careful to keep the wet plate out of reach and so safe
from injury.

"Well," said Mr. Britton, when, at the end of the seance, he returned
his treasures to the bag, "you have now got twenty-three of our cheques,
to all intents and purposes. I hope you are not going to make any
unlawful use of them--must tell our cashiers to keep a bright look-out;
and"--here he lowered his voice impressively and addressed himself to
me and Polton--"you u