"'You have furnished me with a valuable piece of evidence, Mrs. Middlemore. Papers are easily burnt, and a desk broken up and destroyed. It would not be so easy to get rid of that knife, which, from your description, must be a foreign dagger, and the identification of which would be a simple matter. For instance, you could swear to it, and so could I, who have never seen it.' "'Anybody could swear to it, sir; it couldn't be mistook.' "'Did M. Felix keep this dagger always in his desk?' "'I should say he did, sir. I never saw it laying about loose, and never saw it at all unless the desk was open.' "'Did you see it on the last occasion you saw the desk open, a few hours before M. Felix's death?' "'Yes, sir, it was among 'is papers.' "'Have you any suspicion, Mrs. Middlemore, who at this present moment has possession of the desk and the dagger?' "'Not the least, sir. 'Ave you?' "'I have. A suspicion amounting to a certainty. Have you forgotten the man with a red handkerchief round his neck who escaped from the house on the night of the eventful discovery?' "'I'm not likely to forget 'im,' said Mrs. Middlemore, and then added, in an excited tone, 'do you think it was 'im as took it?' "'Him, and no other. Now we arrive at the motive of his visit; it was robbery. Not a vulgar robbery such as an ordinary thief would have committed, but one of a particular nature, and committed with a knowledge that M. Felix's Indian desk contained a secret or secrets of value, which no doubt he could turn to good account. We are getting on, Mrs. Middlemore, we are getting on,' said our reporter, rubbing his hands in satisfaction. 'In these affairs there is nothing like patience.' "'You're as good as a detective, sir,' said Mrs. Middlemore, 'and you've got the patience of Job. You won't mind my saying that I've thought lots of your questions foolish, and only put for the sake of saying something. I don't think so now, sir.' "'Thank you for the compliment. I assure you I have not asked you one idle question. Recall to mind whether the man with the red handkerchief round his neck carried anything away with him that looked like a desk as he escaped from the house.' "'I don't believe, sir,' said Mrs. Middlemore, with evident reluctance, 'as that will ever be known.' "'Oh, yes, it will. Answer my question.' "'I didn't notice nothing,' replied Mrs. Middlemore. "We pause a moment here to observe that it was these reserved replies, when any question relating to this man was asked, as well as the conflicting testimony of the constables Wigg and Nightingale, that led us to the conclusion, already recorded, that the precise truth was not revealed as to which one of the three witnesses actually saw the man. Having committed themselves to a certain statement for the purpose of exonerating the constables from official blame, they could not afterward contradict themselves, because such a contradiction would have thrown grave doubt upon the whole of their evidence.