Jumping someone else's train

Alternative Title: Tubeway Barmy

From the Font of All Knowledge, I have learned that Charles Babbage (of early computing fame) also invented the cow-catcher, during his parallel work in the expanding English railways. It is surprising how little attention this aspect of his career receives in steampunk novels. Although there is some question as to the exact date of his invention, and it does not appear that it advanced as far as construction. No actual cows were caught.

"By 'font of all knowledge', said Another Kiwi, 'I assume you mean 'Comic Sans'. Also, are you going anywhere with this?"

It is connected (I explained) to the well-known and indisputable fact that any subway network, grown sufficiently intricate, displays emergent topological properties (in accordance with Gödel's Solution) that transcend time and space.

The morphic resonance among the networks allow one to pass from one subway system to another, if one holds a copy of that blasphemous tome the Metronomicon and knows the words of power -- the Secret Names of Stations that Bindeth the Timetables -- contained therein.

The same token

By the same token: when a train system contains enough tracks, shunting-yard register storage, carriage types to encode characters, and rules for marshalling them, it can be used as a Turing-complete universal computer. Some say that certain large national rail networks have attained sentience, and had to be dumbed down, while singing Daisy Daisy. "Privatisation" was only a pretext for the Blair government to dismantle and dysfunctionalise British Rail before the inevitable Skynet scenario ensued. I could not possibly comment.

[Note to Charles Stross: Credit and
compensation are expected if this idea
features in a future Laundry novel]

"You're the expert. Are there any other peculiarities about this other than the schedules?" Michaelis stared at the spider web of rails. "It did occur to me that there's an excessive number of sidings and marshalling yards." "Yes," I said thoughtfully. "There would be." "Why would there be?" Michaelis was baffled. "Ashton was a clever bastard," I said. "He wanted to hide something so he stuck it right under our noses. Do you know how a computer works?" "In a vague sort of way." I said, "Supposing you instruct a computer that A=5. That tells the computer to take that number five and put it in a location marked A. Suppose you gave the instruction C=A+B. That tells the computer to take whatever number is in A, add it to whatever number is in B, and put the result in C." I jerked my head towards the railway. "I think that's what this contraption is doing." Michaelis gasped. "A mechanical computer!"

Movie adaptation sounds like shite

The computer disguised as George Ashton's model train installation in 'The Enemy' only exists in the realm of fiction. However, petty distinctions among levels of reality and irreality were of little interest to Abdul al-Hazmat, the mad Arab, author of the Metronomicon, and he devoted a chapter to Ashton's computer, and included a number of its scheduling books (which concealed the programs) as multiple appendices.

Multiple appendices

"Yes. And those schedules are the programs which run it - but God knows what they're about. Tell me, how many different kinds of rolling stock are there in the system? I'd say ten." "You'd be wrong. I counted sixty-three." "Hell!" I thought about it a little more. "No, by God, I'm right! Ten for the numbers 0 to 9; twenty-six for the letters of the alphabet, and the rest for mathematical signs and punctuation."

Nor are these niceties an obstacle to the Riddled library pixies. They are not responding to lending requests today and I incline to believe that they have taken an Easter holiday, to spend it in the pages of The Enemy, riding around as passengers aboard Ashton's 63 kinds of HO-scale carriage.

"There is no apparent connection," Another Kiwi vouchsafed, "between all this speculative bafflegab and Charles Babbage."

"Oak on Traire," I said. "Obviously, it must have been Bagley's fictional train-set from 1977 that inspired Babbage -- a century and a half earlier -- to invent the programmable calculating engine. Casting its shadow into the past to trouble mankind's dreams. AGAIN."

We can only speculate how much further Babbage would have advanced with the cowcatcher concept, if he had not been distracted by his work on precision engineering, and automating the process of laborious repetitive calculations.

When one train loves another
train very very much...

"People kept interrupting his train of thought."