The Professor was quite mad, of course. I believe he was an archetype rather than a stereotype but 'what the hell, Archie, ' as Mehitabel was wont to say. I met him in the local supermarket. He was pacing the aisles muttering to himself. Now I'm one of these people who can't help but look at what other folk are buying. It fires my imagination sometimes. You see some little round housewife type with two bottles of gin and a tube of KY jelly hidden among the cornflakes and already you can envisage the party to come. See what I mean? And it never fails to crack me up when I see some crusty old Colonel buying sheer stockings. I bet he's a wow down at the club!

The Professor's trolley was full of unrelated odds and ends. Bottled water, about a dozen packs of needles, tins of beans, chocolate, fuse wire, frozen fish fingers, a disposable camera in a sickly shade of yellow, athlete's foot powder and that stuff for sticking your false teeth in so tight you can bite into a crisp apple without the embarrassment of leaving the old gnashers embedded while your gums slap together. If he hadn't looked like a Mad Professor I would probably have just dismissed as some old fart living on his own. Anyway, to cut a long story shortish, he caught me gawping at him and fixed me with his eye. He had the regulation number of eyes but only one of them seemed inclined to obey him. The other kind of kept wandering off to survey the shelves or the ceiling. It was slightly disconcerting.

I don't know if he thought I was one of the supermarket drones or whether he just thought I might be the type to know because he suddenly lunged towards me.

"Where do they keep the rheostats in this place? Can't find 'em anywhere!"

I was now rapidly forming the opinion that the old boy was off his trolley, despite the fact that he was clearly pushing one. I decided to humour him.

"I think they're between the voltmeters and the pickled cabbage."

He laughed. It wasn't a pleasant sound. It was the kind of laugh that you hear from someone who isn't used to finding anything funny. A kind of cross between a rusty gate and a flatulent donkey.

"You must think I'm mad," he said. I didn't contradict him.

He put his liver-spotted hands on his scrawny hips and thrust his wattled chin towards me. He looked like nothing so much as an oven-ready vulture. He was wearing one of those khaki safari shirts on top of a pair of ancient, faded blue shorts that reached just below his knees. Odd, thigh-length socks and Jesus sandals completed the ensemble. No fashion plate, then, our Professor. I could tell he was appraising me with his one ruly eye. Its unruly partner was now carrying out a detailed survey of the inside of his head.

"What's your name, boy?"

"Jonathon, although most people call me Jonty."

"Right, Jonty. Do you believe in time travel?"

I shrugged. My face must have given me away because he made the farting donkey noise again.

"Quite right. Healthy scepticism, that's what I like to see and that's just what I need. I have a proposition to put to you, my lad. Meet me in the coffee shop in ten minutes."

I still don't really know why but I agreed. I finished my shopping - typical bachelor - ready meals, deodorant and several bottles of wine, and made my way to the coffee shop. There was the usual crowd of aged crones sucking the ersatz cream out of sticky buns and mothers with small jam-smeared children that howled when denied another donut. I remembered then why I always avoided the place like a lazaretto. The Professor had grabbed one of the few tables and was sitting waiting for me. He'd even bought me a cup of the unidentified brown fluid that was the speciality of the house.

"Right, Jonty. What do you do for a living?"

"Not a lot, at present. I used to work for the local radio station."

"Doing what?"

"Bits and pieces. It's not the BBC. You have to turn your hand to anything. I did research, read traffic reports and weather forecasts and stood in when someone was too pissed to show up."

"And why did you leave?"

"I was too pissed to stand in for someone who was too pissed to show up. I made the mistake of showing it, though."

"Oh, that was you, was it? You're the one who invited the Lady Mayoress to show you her tits at the Agricultural Show! Ha, haven't laughed so much in ages."

I shrugged. One of the perils of live broadcasting with a stand-in presenter who is absolutely mullahed. The pompous old trout had got up my nose but I hadn't realised that my mike was still live when I muttered: "Shut up, you old bat, and show us yer tits," in the middle of her toe-curling opening speech. Three thousand odd attendees and all of our dozen listeners heard this little aside. Unfortunately, so did the Mayoress - well, she couldn't have missed it - and the owner of the station, who just happens to be her husband. It was no good protesting that I wasn't even supposed to be working that afternoon. I was just wandering around in an alcoholic stupor when the producer grabbed me.

"Jonty, Big Mel hasn't shown again. Get up there now and introduce the dignitaries."

I honestly tried to get out of it. I was almost incoherent anyway, but he wasn't listening or he couldn't understand my slobbering attempt at an explanation. Well, that's history now; and so was I thirty seconds after my last live broadcast. Back to the Professor:

"I would like to hire you."

"You what?"

"I said, I would like to hire you. Allow me to explain."

And he did. He told me that his name was Professor Gerald Humphreys, formerly Head of Quantum Physics at the local university. He'd retired two years before and had spent the intervening period perfecting a time machine. He'd worked on it for over thirty years and now it was finally ready. He needed an assistant, mainly to act as an objective observer but also to do any heavy donkeywork. I fitted his bill. I was young, fit and pretty well built. I was also a sceptic, which made me ideal.

With nothing better to do I agreed. I figured he was potty anyway and I might as well earn a couple of quid as sit around watching daytime TV. We arranged to meet early the following morning. He told me to dress for travelling, whatever that meant, and to be at his place at seven am sharp. We parted company at the door. His last words to me were:

"They don't sell rheostats in supermarkets."

I had nothing to add.

I presented myself at the Prof's pad at seven the next morning, as instructed. He was his usual picture of sartorial elegance clad in a green brocade smoking jacket, threadbare jogging pants and flip-flops. He grabbed my arm with a scrawny claw and dragged me through to his workshop. What little floor space there once had been was taken up by a large silver dome-shaped affair. It looked a bit like one of those Buddhist dagobas you see in the Far East and was emitting a low humming sound that was almost, but not quite, below the human audible range.

"Ah, I see you are looking at my Temporal Interface Terminal. Beautiful, isn't it?"

It was certainly unusual. The closer I looked at it, the harder it was to see, somehow. The surface of the machine appeared to swirl in and out of focus leaving me with an impression of what I was looking at, rather than an image. The air in the workshop seemed charged with electricity. I could feel the hair on my forearms standing on end and experienced a weird tingling sensation all over my skin, like ants crawling all over me.

"What does it do?"

"Exactly what the name suggests, dear boy. It provides an interface - a gateway, if you will - between the present and other parts of the temporal multiverse."

"Multiverse?"

"Yes, of course. Schrodinger's cat, my boy. You don't seriously imagine that this is the only reality, do you?"

"I've never been that strong on quantum theory. I just kind of thought that this was it, if you know what I mean."

"Limited intelligence often goes hand-in-hand with limited imagination, Jonty. Don't concern yourself. You don't need to understand how or why it works; you need only accept that it does. Once we enter the T.I.T., we are stepping outside this version of reality. We may then choose to journey either forwards, backwards or sideways, as it were."

"Sideways? You mean like to a parallel universe?"

"Crudely, yes. There is an almost infinite combination of reality states, each one slightly out of phase with the next. Under normal conditions we are totally unaware of their existence."

"OK then, Professor. What happens when you go back in time? Do you go to back to 'our' past or one of these alternates?"

"I'm sorry to admit that I really don't know, my boy. You see, I have done all the laboratory testing but, well, I haven't actually attempted a full voyage as yet."

"Whoa! Are you saying that you don't know if this thing works?"

"Of course not! It works but I haven't yet made the maiden voyage, that is all."

"Now hang on a minute. You're suggesting we climb into that thing, press the tit and hope for the best?"

"Crudely put, but essentially accurate."

I was on the verge of backing out of this little game but he grabbed me and propelled towards the machine. There was no door apparent but somehow we kind of glided through the outside and I found myself staring at the strangest 'room' I have ever seen. It was a combination of chrome and chintz. A kind of cross between a 1950's coffee bar and a down-at-heel Victorian country house. Knobs and dials and VDUs were everywhere. Two overstuffed armchairs slouched on a moth-eaten fake Turkish Carpet and one wall was covered in the most tasteless flock wallpaper ever seen outside of an Indian Restaurant. A little posy of flowers sat in a glass jam jar on top of part of what looked like an old mainframe computer, complete with ticking magnetic tape spools. The whole effect made me dizzy.