‘Yes."
"Did anybody else know it?
"We-ell yes, I should certainly think so. He was always cursing the stuff. But he had to drink it; or thought he had to."
"Did he ever have any visitors at his house besides yourself?"
"Only Dr. Keppel. I told you about him."
"Ever meet Keppel yourself?"
"Once." Again Antrim was interested. "I happened to be in Bristol, and I ran into Hogenauer there, and he took me to Keppel's hotel. Interesting chap. Good talker. Very fond of — of gadgets (you know?) like most scientific men. Hogenauer was too. I wonder why? I say, there was one gadget that would have interested you. Eighteenth-century burglar-trap. It seemed the hotel was originally the town-house of some nob who liked things like that. It's in the window. The window's up; you put your hand on the sill directly under the place where the window comes down; this presses it down like a guillotine-plank; weights and pulleys in the frame release the window — well, it's got a knife in it. Devil of a business. Of course, the knife was taken out a hundred years ago. But Keppel found traces of the gadget, and reconstructed it. Just curiosity, to amuse people. Naturally the hotel didn't know about it, or it'd have come out of there pretty quick. Dangerous. Keppel was careful not to tell a police friend of his about it. Also, he kept it locked; and warned the maids never to touch that window or the bogeyman would get 'em. Queer fish, Keppel."
"So the guillotine-window," mumbled H.M., "has got no sinister significance, hey? Tell me, son: why do you talk about Keppel in the past tense?"
Antrim blinked. "Did I? I wasn't conscious of it. Sorry.
"Don't be sorry. You were right. Keppel was murdered tonight, son."