"Perhaps you'd better," said Thorndyke. "It may not be Mr. Britton, and I don't want to be caught and delayed just now."
However, it was Mr. Britton; a breezy alert-looking middle-aged man, who came in escorted by Polton and shook our hands cordially, having been previously warned of my presence. He carried a small but solid hand-bag, to which he clung tenaciously up to the very moment when its contents were required for use.
"So that is the camera," said he, running an inquisitive eye over the instrument. "Very fine one, too; I am a bit of a photographer myself. What is that graduation on the side-bar?"
"Those are the scales," replied Thorndyke, "that shows the degree of magnification or reduction. The pointer is fixed to the easel and travels with it, of course, showing the exact size of the photograph. When the pointer is opposite 0 the photograph will be identical in size with the object photographed; when it points to, say, × 6, the photograph will be six times as long as the object, or magnified thirty-six times superficially, whereas if the pointer is at ÷ 6, the photograph will be a sixth of the length of the object, or one thirty-sixth superficial."
"Why are there two scales?" Mr. Britton asked.
"There is a separate scale for each of the two lenses that we principally use. For great magnification or reduction a lens of comparatively short focus must be used, but, as a long-focus lens 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.