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Bletchley Park

Started: 2018-07-26 20:47:57

Submitted: 2018-07-27 00:53:36

Visibility: World-readable

In which the intrepid narrator makes a fourth trip to London and finds more things to see

In April, I visited my SRE team's counterpart in London, for what turned out to be the last time -- though it turns out I'm now working on a new SRE team that has its counterpart in the same office, so I expect I'll have the opportunity to return in the future.

N749UA at SFO
N749UA at SFO

I left San Francisco on Saturday evening, 7 April; and landed at London-Heathrow on Sunday afternoon. I took the Heathrow Express train to London-Paddington and amused myself looking around the station. I found a statue of Paddington Bear, with the label "Please look after this bear, thank you" on his collar.

Jaeger with Paddington Bear at Paddington Station
Jaeger with Paddington Bear at Paddington Station

And a statue of Isambard Kingdom Brunel, on the platform under the magnificent cast iron arch of the terminal station he built more than 150 years ago, in front of a passenger locomotive bearing the livery of the modern incarnation of the Great Western Railway he founded.

Isambard Kingdom Brunel statue at London Paddington with GWR locomotive
Isambard Kingdom Brunel statue at London Paddington with GWR locomotive

And then I got a selfie with The greatest engineer in the world.

Jaeger with Isambard Kingdom Brunel at Paddington Station
Jaeger with Isambard Kingdom Brunel at Paddington Station

I spent the week in my employer's office next to Kings Cross Station, then gave myself the weekend to play tourist in London before returning home to San Francisco on Monday. I stayed at the Great Northern Hotel, immediately in front of Kings Cross Station. The hotel was originally built as the railway hotel for the station, and had been reinvented as a boutique hotel with tiny cozy rooms. It was a fascinating place to stay, though I found perversely that I was too close to the office, and I wanted more time in my commute to disconnect from work and contemplate.

Jaeger with Robert Stevenson at Euston Station
Jaeger with Robert Stevenson at Euston Station

On Saturday morning, I walked to Euston Station, past St. Pancras Station and the British Library, and caught a train up the West Coast Main Line to Bletchley Park. Just outside the train station was the site where, 75 years ago, the Allies broke all of the German codes, giving them complete access to their military plans, helping winning the Second World War.

Lorenz cipher machine
Lorenz cipher machine

I spent much of my time at Bletchley Park in the exhibit hall showing, in detail, how the codebreakers worked. I ended up going through the exhibit backwards, starting with the Lorenz cipher machine used by high command. This machine worked together with a teleprinter machine to encode and transmit the message using a five-bit encoding -- and when I looked at the message punched into teleprinter tape it looked just like a secret message on the wall of my office. (I later decoded the message using the Baudot teleprinter encoding.)

Teleprinter tape
Teleprinter tape

Most of the exhibit was dedicated to the much-more-famous Enigma machine, which was widely used by the German military in the field. Display cabinets held various Enigma machines used by various branches, each with their own implementation details and quirks. The security of the cipher system depended on the selection and arrangement of the wheels and the patch panel. When the system changed every day at midnight, the code-breakers attacked the messages by guessing what the plain text of the message might be, based on triangulation and signal analysis -- a weather station in the North Atlantic would usually start its weather report with a particular phrase. The main work of code-breaking was done in large electromechanical devices that replicated the workings of the Enigma machine and could test many hypothesis at once. All of these machines had been destroyed after the war, but the museum had built a working replica with the assistance of some of the people originally involved in building and operating the decryption machines.

I was amazed by the entire site, as I wandered around the grounds, into the buildings that were open -- where luminaries including Alan Turing worked to form the basis of modern computing, and helped win the war. (I was also reminded that the last time there was a global total war against fascism, the United States and United Kingdom were allied -- and were fighting against fascism and intolerance.) I was moved by what I saw and experienced at the site.

After lunch at the on-site cafe, and a quick walk through the mansion that formed the original estate (and the administrative center of the code-breaking operation during the war), I headed around the corner to the National Museum of Computing.

Operator's panel and tape input on Colossus
Operator's panel and tape input on Colossus

The Lorenz code was broken with the assistance of the world's first programmable computer, Colossus. It too had been dismantled after the war to prevent it from falling in the wrong hands, but the National Museum of Computing had a working replica, built from thousands of vacuum tubes, all glowing softly as they took the message encoded on the teleprinter tape and tried to break the code. (I was unclear precisely how the machine was attacking the code, though it was clear that the cipher scheme did not spread the bits of the plain text, so some patterns in the plain text could be visible in a single bit of the output.)

Circuit boards on Colossus
Circuit boards on Colossus

(One thing I wasn't quite sure about was what Colossus' legacy was: did the lessons learned in building the machine leak out into the greater world despite the official secrecy surrounding it? Or was it an evolutionary dead-end, a computer Neanderthal, that failed to influence its successors?)

Vacuum tubes on Colossus
Vacuum tubes on Colossus

I stood, transfixed, by the machine as it ran, as I tried to imagine how it worked and how it was built (and how the tubes were arranged into gates and flip-flops and registers and accumulators, and whether I could recognize any part of the circuit diagram if I saw it) -- even as I recognized that my watch has orders of magnitude more computing power in a chip the size of my fingernail.

After seeing Colossus I looked at the rest of the museum, which collected various computers (all of them newer than Colossus, of course), most of them notable for some engineering or commercial feature, only to be superseded by the next generation. I saw tubes that counted from 0 to 9 using arcs, relying on the property that current will arc through ionized air. I saw core memory banks the size of dishwashers, and giant hard drives the same size. Most of the displays were complete installed machines, crammed into a couple of adjacent rooms, reminding me somehow of a furniture store with more tables and chairs and couches then it had room to comfortably display. Many of the machines still ran, in some capacity, and were attended by people who were old enough to remember when they were new and in commercial service.

The other wing of the museum had newer hardware from the age of personal computing, with small galleries tracing themes like sound, graphics, and connectivity -- modems and BBSes giving way to the Internet. Many of the machines on display tickled my nostalgia from the 1980s and 1990s. I was impressed by the wiring in the back of a vintage Cray, all of it looping down so that every pair was the same length.

Wires on Cray supercomputer
Wires on Cray supercomputer

I took the train back to London, arriving in time to spend an hour wandering through the Tate Modern and walk across the Millennium Bridge before eating supper and heading back to my hotel.

Looking up in the Tate Modern
Looking up in the Tate Modern

On Sunday I visited a handful of galleries in the British Museum (the world's finest museum of imperial plunder), the Science Museum (with a large exhibit tracing the history of steam power, plus a gallery filled with artifacts from the industrial revolution), and my favorite museum in London, the Victoria and Albert Museum. There I found two artifacts of interest to Willy: a bust of Sir Edwin Lutyens and a model of the unbuilt Governor's Palace in Chandigarh by Le Corbusier.

Caricature Bust of Sir Edwin Lutyens
Caricature Bust of Sir Edwin Lutyens
Model of Governor's Palace in Chandigarh by Le Corbusier
Model of Governor's Palace in Chandigarh by Le Corbusier

I ate supper on my last night in London at Mildred's, a great all-veg restaurant down the street from Kings Cross Station; then flew home to San Francisco on Monday.

I included just about every picture I took in London above, but I left a few for the complete photo set: London 2018.

Most of what I've told you is an absolute fact.
- Doug Logan, 22 December 1999