As soon as we were alone, Badger assumed a friendly and confidential manner and proceeded to give advice. “I gather that Mr. Bidwell wants you to investigate this case, but I don’t fancy it is in your line at all. It is just a matter of tracing that stranger and getting hold of him. Then we shall have to find out what property there was on these premises. The laundress says that there is nothing missing, but of course no one supposes that the man came here to take the furniture. It is most probable that the motive was robbery of some kind. There’s no sign of anything broken open; but then, there wouldn’t be, as the keys were available.” Nevertheless he prowled round the room, examining every receptacle that had a lock and trying the drawers of the writing table and of what looked like a file cabinet. “You will have your work cut out,” I remarked, “to trace that man. The porter’s description was pretty vague.” “Yes,” he replied; “there isn’t much to go on. That’s where you come in,” he added with a grin, “with your microscopes and air-pumps and things. Now if Dr. Thorndyke was here he would just sweep a bit of dust from the floor and collect any stray oddments and have a good look at them through his magnifier, and then we should know all about it. Can’t you do a bit in that line? There’s plenty of dust on the floor. And here’s a pin. Wonderful significant thing is a pin. And here’s a wax vesta; now, that ought to tell you quite a lot. And here is the end of a leather boot-lace--at least, that is what it looks like. That must have come out of somebody’s boot. Have a look at it, doctor, and see if you can tell me what kind of boot it came out of and whose boot it was.” He laid the fragment, and the match, and the pin, on the table and grinned at me somewhat offensively. Inwardly I resented his impertinence--perhaps the more so since I realized that Thorndyke would probably not have been so completely gravelled as I undoubtedly was. But I considered it politic to take his clumsy irony in good part, and even to carry on his elephantine joke. Accordingly, I picked up the three “clues,” one after the other, and examined them gravely, noting that the supposed boot-lace appeared to be composed of whalebone or vulcanite. “Well, inspector,” I said, “I can’t give you the answer off-hand. There’s no microscope here. But I will examine these objects at my leisure and let you have the information in due course.” With that I wrapped them with ostentatious care in a piece of note-paper and bestowed them in my pocket, a proceeding which the inspector watched with a sour smile. “I’m afraid you’ll be too late,” said he. “Our men will probably pick up the tracks while you are doing the microscope stunt. However, I mustn’t stay here any longer. We can’t do anything until we know what valuables there were on the premises; and I must have the body removed and examined by the police surgeon.”