Trent, with his hands in his pockets and a slight frown on his brow, made no reply to this. “I tell you what,” he said after a short pause, “I was just getting to the really interesting part of the job when you came in. Come; would you like to see a little bit of high-class police work? It’s the very same kind of work that old Murch ought to be doing at this moment. Perhaps he is; but I hope to glory he isn’t.” He sprang off the table and disappeared into his bedroom. Presently he came out with a large drawing-board on which a number of heterogeneous objects was ranged.
“First I must introduce you to these little things,” he said, setting them out on the table. “Here is a big ivory paper-knife; here are two leaves cut out of a diary—my own diary; here is a bottle containing dentifrice; here is a little case of polished walnut. Some of these things have to be put back where they belong in somebody’s bedroom at White Gables before night. That’s the sort of man I am—nothing stops me. I borrowed them this very morning when everyone was down at the inquest, and I dare say some people would think it rather an odd proceeding if they knew. Now there remains one object on the board. Can you tell me, without touching it, what it is?”
“Certainly I can,” said Mr. Cupples, peering at it with great interest. “It is an ordinary glass bowl. It looks like a finger-bowl. I see nothing odd about it,” he added after some moments of close scrutiny.
“I can’t see much myself,” replied Trent, “and that is exactly where the fun comes in. Now take this little fat bottle, Cupples, and pull out the cork. Do you recognize that powder inside it? You have swallowed pounds of it in your time, I expect. They give it to babies. Grey powder is its ordinary name—mercury and chalk. It is great stuff. Now, while I hold the basin sideways over this sheet of paper, I want you to pour a little powder out of the bottle over this part of the bowl—just here. … Perfect! Sir Edward Henry himself could not have handled the powder better. You have done this before, Cupples, I can see. You are an old hand.”
“I really am not,” said Mr. Cupples seriously, as Trent returned the fallen powder to the bottle. “I assure you it is all a complete mystery to me. What did I do then?”
“I brush the powdered part of the bowl lightly with this camelhair brush. Now look at it again. You saw nothing odd about it before. Do you see anything now?”
Mr. Cupples peered again. “How curious!” he said. “Yes, there are two large grey fingermarks on the bowl. They were not there before.”
“I am Hawkshaw the detective,” observed Trent. “Would it interest you to hear a short lecture on the subject of glass finger-bowls? When you take one up with your hand you leave traces upon it, usually practically invisible, which may remain for days or months. You leave the marks of your fingers. The human hand, even when quite clean, is never quite dry, and sometimes—in moments of great anxiety, for instance, Cupples—it is very moist. It leaves a mark on any cold smooth surface it may touch. That bowl was moved by somebody with a rather moist hand quite lately.” He sprinkled the powder again. “Here on the other side, you see, is the thumb-mark—very good impressions all of them.” He spoke without raising his voice, but Mr. Cupples could perceive that he was ablaze with excitement as he stared at the faint grey marks. “This one should be the index finger. I need not tell a man of your knowledge of the world that the pattern of it is a single-spiral whorl, with deltas symmetrically disposed. This, the print of the second finger, is a simple loop, with a staple core and fifteen counts. I know there are fifteen, because I have just the same two prints on this negative, which I have examined in detail. Look!”—he held one of the negatives up to the light of the declining sun and demonstrated with a pencil point. “You can see they’re the same. You see the bifurcation of that ridge. There it is in the other. You see that little scar near the centre. There it is in the other. There are a score of ridge-characteristics on which an expert would swear in the witness-box that the marks on that bowl and the marks I have photographed on this negative were made by the same hand.”
“And where did you photograph them? What does it all mean?” asked Mr. Cupples, wide-eyed.
“I found them on the inside of the left-hand leaf of the front window in Mrs. Manderson’s bedroom. As I could not bring the window with me, I photographed them, sticking a bit of black paper on the other side of the glass for the purpose. The bowl comes from Manderson’s room. It is the bowl in which his false teeth were placed at night. I could bring that away, so I did.”
“But those cannot be Mabel’s fingermarks.”
“I should think not!” said Trent with decision. “They are twice the size of any print Mrs. Manderson could make.”
“Then they must be her husband’s.”
“Perhaps they are. Now shall we see if we can match them once more? I believe we can.” Whistling faintly, and very white in the face, Trent opened another small squat bottle containing a dense black powder. “Lampblack,” he explained. “Hold a bit of paper in your hand for a second or two, and this little chap will show you the pattern of your fingers.” He carefully took up with a pair of tweezers one of the leaves cut from his diary, and held it out for the other to examine. No marks appeared on the leaf. He tilted some of the powder out upon one
