"By the way, how comes it that the cheques are at the bank? Why were they not returned to Jeffrey with the pass-book in the usual way?"
"I understand from Britton," replied Thorndyke, "that all Jeffrey's cheques were retained by the bank at his request. When he was travelling he used to leave his investment securities and other valuable documents in his bankers' custody, and, as he has never applied to have them returned, the bankers still have them and are retaining them until the will is proved, when they will, of course, hand over everything to the executors."
"What is the object of photographing these cheques?" I asked.
"There are several objects. First, since a good photograph is practically as good as the original, when we have the photographs we practically have the cheques for reference. Then, since a photograph can be duplicated indefinitely, it is possible to perform experiments on it which involve its destruction; which would, of course, be impossible in the case of original cheques."
"But the ultimate object, I mean. What are you going to prove?"
"You are incorrigible, Jervis," he exclaimed. "How should I know what I am going to prove? This is an investigation. If I knew the result beforehand, I shouldn't want to perform the experiment."
He looked at his watch, and, as we rose from the table, he said:
"If we have finished, we had better go up to the laboratory and see that the apparatus is ready. Mr. Britton is a busy man, and, as he is doing us a great service, we mustn't keep him waiting when he comes."
We ascended to the laboratory, where Polton was already busy inspecting the massively built copying camera which—with the long, steel guides on which the easel or copy-holder travelled—took up the whole length of the room on the side opposite to that occupied by the chemical bench. As I was to be inducted into the photographic art, I looked at it with more attention than I had ever done before.
"We've made some improvements since you were here last, sir," said Polton, who was delicately lubricating the steel guides. "We've fitted these steel runners instead of the blackleaded wooden ones that we used to have. And we've made two scales instead of one. Hallo! That's the downstairs bell. Shall I go sir?"