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.