of course a broken lock has one disadvantage as compared with a skilfully picked lock—it shows at the first glance what has happened. In this case, Mr. Bell, your lock has been broken and taken away, and the thief, having first provided himself with another padlock of precisely the same make and size, has substituted that, locked it with its proper key and so left it!"
"What! Then that was why"
"That, of course, was why you supposed it to be out of order when you attempted to open it with your key. As a matter of fact, it is even now in perfectly good order, except for the damage we have jointly committed with the screw-driver. And now, observe! That lock was shut by another key; if the man that did that is as sharp as I suppose he is, he will have got rid of that key at once. But perhaps he hasn't; and if not, then the man who has that key is the thief. At any rate, the key is the clue we must hunt for. Let us have your clerks in one by one, and look at their keys. Some are out at lunch by this time, probably?"
"No—I said they might be wanted, so kept them. I thought you might prefer to see them before they went out."
"Very well thought of, but perhaps scarcely judicious, on the whole. Because if there is a
