Amazing what you find when you're clearing out

Ten years ago I entered a Sherlock Holmes-inspired flash fiction competition. I forget the exact criteria but I didn't get anywhere, and never knew what to do with the resulting short tale about the impossibility of time travel. Having finally mothballed my decaying laptop I'm tidying up the file structure on the new (second-hand) desktop and stumbling across forgotten stories, including that one. It's less than 500 words long, so if you fancy a small piece of Victorian-set SF, read on, and if you enjoy it you can always buy me a cuppa at https://ko-fi.com/jysaville
When you've eliminated the impossible…
"Carstairs, you simply must come," insisted young Fotherington. "How could you miss the chance to use a time machine?"
Professor Carstairs sighed. In twenty minutes of argument his delightful cousin's foolish husband had failed to take on board the basic principle that such a machine was a physical impossibility. It was all the fault of that bounder Wells and his sensational literature. If only more people had read Conan Doyle's excellent stories in The Strand instead.
"How indeed?" Carstairs said. Fotherington beamed at this apparent capitulation, and set about writing to the friend who had invited them for the weekend.
By the time they boarded the train on Friday, the professor was looking forward to the trip. Since the machine couldn't really transport anyone through time, he wanted to ascertain whether the perception was created through physical or psychological means. In short, did the experience involve the administration of drugs or a subtle blend of auditory stimuli and the power of suggestion.
They had almost arrived when Fotherington said, "I knew you'd come round in the end, Carstairs."
"Fotherington, you do understand that the supposed inventor of this machine, your friend's new acquaintance, is either a fraud or a fool? Or both."
"Carstairs!"
"There are laws of physics which absolutely forbid -"
"Wasn't it once a law of physics that the sun went round the earth?" asked Fotherington, his smile suggesting his clever friend had been caught out.
"That wasn't a law of physics, it was a piece of dogma which has since been overthrown."
#
The breathless Fotherington found Professor Carstairs prowling their host's library later that afternoon.
"Carstairs, it was marvellous. I threw back a lever and fetched up in Elizabethan times, I could hear feasting."
"Hear?" Carstairs raised an eyebrow. This hinted at the drug-free theory of subtle suggestion.
"Yes," said Fotherington. "The chap said stay in the shadows and don't interact with anyone."
Carstairs smiled and followed Fotherington to the contraption which had been built into a closet. He shook hands with the inventor and settled himself inside, nudging the lever gently forwards. There was a prolonged mechanical whirring, a flash of light, and then silence. Carstairs opened the closet door expecting Fotherington, but found an empty room. The light seemed different and he cursed himself – the handshake must have been a means of transferring an hallucinogenic substance.
"…doesn't matter what I saw on Friday, I'm not convinced, Fotherington."
Carstairs heard a familiar voice and two sets of footsteps approaching. As the door to the room opened, he came face to face with himself wearing a look of abject horror.