A sad-faced, elderly woman came into the room.
“ Did you dust this bureau yesterday morning?”
“ Yes, sir.”
“ Did you notice this scratch?”
“ No, sir, I did not.”
“ I am sure you did not, for a duster would have swept away these shreds of varnish. Who has the key of this bureau?”
“ The Professor keeps it on his watch-chain.”
“ Is it a simple key?”
“ No, sir, it is a Chubb’s key.”
“ Very good. Mrs. Marker, you can go. Now we are making a little progress. Our lady enters the room, advances to the bureau, and either opens it or tries to do so. While she is thus engaged, young Willoughby Smith enters the room. In her hurry to withdraw the key, she makes this scratch upon the door. He seizes her, and she, snatching up the nearest object, which happens to be this knife, strikes
