Inside the mill, individual operations are controlled by the equivalent of a microprogram. The microprogram is stored on cylinders covered in studs (much like in a music box) that Babbage refers to as the barrels. Data is transferred from the store to the mill for processing and returned to the store for later use. In his plans Babbage described an Engine with 100 storage locations holding 40 decimal digits each (which is roughly equivalent to 1.7KB). He even anticipated the need for ever more memory, describing an Engine with 1,000 storage locations (17KB) and external storage (he would have used punched cards where we use disks).

For output, the Analytical Engine plans call for both a printer and a plotter. The entire Engine would likely have been powered by steam and would have been the size of a small steam locomotive. Its programming language — if it can be called that — included loops and conditionals. The only surprising thing about the architecture of the Analytical Engine is when it was invented.

It wasn’t until 100 years later that computers came into existence, with Babbage’s work lying mostly ignored. In the late 1930s and 1940s, starting with Alan Turing’s 1936 paper “On Computable Numbers, with an Application to the Entscheidungsproblem,” teams in the US and UK began to build workable computers by, essentially, rediscovering what Babbage had seen a century before. Babbage had anticipated the impact of his Engine when he wrote in his memoirs: “As soon as an Analytical Engine exists, it will necessarily guide the future course of science.”

During his lifetime Babbage only constructed parts of the Analytical Engine (which can be seen in the Science Museum in London). His son, H. P. Babbage, working from his father’s designs, built a demonstration version of the mill after his father’s death. The elder Babbage left behind extensive documentation and plans for the Engine, all of which are safely stored in London and have been examined by historians.

Babbage came up with the idea of the Analytical Engine while working on a machine to automatically produce mathematical tables (such as tables of logarithms). Mathematical tables were extensively used at the time — and well into the 20th century — and they were calculated by hand by people referred to as “computers.” Babbage hoped to eliminate errors made by these computers by replacing them with a machine capable of performing the relevant calculations automatically.

The machines he invented are called the Difference Engines (because they use the mathematical technique of differences to perform their calculations). These machines were not completed during Babbage’s lifetime partly because of his difficult personality and partly because of the withdrawal of government support for the project. The conception and construction of Babbage’s Engines was an enormous undertaking in the 1800s. Despite repeated setbacks, Babbage continued essentially alone, working on plans and designs up until his death and spending his own fortune on the work. Twentieth-century computer pioneer Maurice Wilkes describes being “haunted by the thought of the loneliness of [Babbage's] intellectual life” while working on the Analytical Engine.

The British government had initially supported Babbage and covered some of the costs of construction of the first Difference Engine. But as costs rose and years wore on, the government was advised that the machines would be of little use, were unlikely to pay for themselves, and the money expended would have been better invested and the dividends used to hire additional human “computers” to do the work.

Soldiering on alone with the conviction that his machines would be of great benefit to mankind by taking what had been mental effort and making it mechanical, Babbage wrote that “Another age must be the judge” of his inventions.

Simply put, we live in that age. In the late 1980s the Science Museum in London undertook a project to demonstrate that Babbage’s Engines could have been built during his lifetime. The museum constructed his Difference Engine No. 2 and the associated printer using historically accurate materials and to within historically accurate tolerances. In 1991, the working machine was unveiled, and it can still be seen on display in the museum (a copy of the machine is also on display at the Computer History Museum in Mountain View, CA).

The Science Museum’s Difference Engine No. 2 project put to rest any doubt about the limits of Victorian engineering. Babbage’s Engines were achievable in Victorian Britain and Babbage’s 100-year leap in inventing the computer could have been realized.

It’s time to build the Analytical Engine

I hope to finish Babbage’s dream and build an Analytical Engine for public display. I’ve launched a project called Plan 28 to raise the money and bring together people to work on the Engine. Babbage left behind extensive documentation of the Analytical Engine, the most complete of which can be seen in his Plan 28 (and 28a), which are preserved in a mahogany case that Babbage had constructed especially for the purpose.

There are three important steps to achieve this goal:

1. A decision must be made on what constitutes an Analytical Engine
2. The Engine should be simulated on a computer to help debug the physical machine
3. The machine must be built

The first step is necessary because Babbage continually refined his designs — he was constantly aiming at simplification and faster computational speed — and left behind a mixed collection of plans and notebooks. Sorting through this material will require the help of historians and specialists in Victorian engineering.

Simulating the machine using 3D modeling software and a physics engine would enable us to bring the machine to life without making any metal parts. Given the size and complexity of the machine, this step is vital. And since the final machine would wear out if constantly used, it would provide a way of demonstrating the Engine.

It might seem a folly to want to build a gigantic, relatively puny computer at great expense 170 years after its invention. But the message of a completed Analytical Engine is very clear: it’s possible to be 100 years ahead of your own time. With support, this type of “blue skies” thinking can result in fantastic changes to the lives of everyone. Just think of the impact of the computer and ask yourself how different the Victorian world would have been with Babbage Engines at its disposal.

What seemed like costly research that was unlikely to have any short-term value turned out to be the seed of one of the greatest revolutions mankind has seen. I hope that future generations of scientists will stand before the completed Analytical Engine, think of Babbage, and be inspired to work on their own 100-year leaps.

Related:

• One of the great inventions that never was – until now?
• How Alan Turing Finally Got a Posthumous Apology

And it’s not just in business and ivory towers that statistical
analysis of masses of data is becoming important: just understanding
the wealth of percentages, risk factors and charts that confront us
all requires a form of ‘data literacy’. As a recent blog post by John
Udell points out, even understanding your electricity bill requires everyday analytical thinking.

For those of us who can code (whatever the language) raw data presents
a rich target for analysis, and some plain fun crunching numbers to
understand them better. A case in point is the recent release of
climate change data which is accessible to anyone with some basic
mathematical and computing skills.

If you don’t have the coding skills you can still follow along and
analyze the output of the program using basic statistical skills like
calculating the mean and standard deviation of a set of data.
Although climate science itself is very complex, much is within the
grasp of someone with basic statistics knowledge.

On December 8, 2009 the UK Met
Office released historical
land surface temperature records spanning 150 years of
measurements from around the globe. The data was a subset of
measurements used to create the CRUTEM3 and
HadCRUT3 datasets.

HadCRUT3 is set of data showing the combined land and marine
temperature anomalies on a 5° by 5° grid-box basis (CRUTEM3 just has
the land temperatures). The globe is divided into grid boxes of 5° of
longitude by 5° of latitude and an average temperature for that box is
calculated from all the temperatures measured at meteorological
stations falling within that square of the Earth’s surface.

Instead of reporting actual temperatures, the CRUTEM3 and HadCRUT3
datasets report temperature anomalies. The anomaly is the difference
between the 1961 to 1990 average temperature for that grid box and the
measured average temperature. Using this anomaly value means that
trends can be clearly seen without having to compare areas with very
different normal temperatures. For example, the north of Scotland and
the south of Spain can be compared just by looking at these deviations
from normal temperatures.

If you’ve seen a chart of global warming you’ve likely seen a graph of
temperature anomalies. Here’s one released by the UK Met Office along
with their historical records:

Although the gridded data in CRUTEM3 and HadCRUT3 had been available
before (just drop in at http://hadobs.org/), the underlying data
released by the UK Met Office was new and I couldn’t resist poking
into it myself. They had promised to release software to analyze it,
but why wait? Using a variety of free (as in speech) and free (as in
beer) software I was able to quickly reproduce the UK Met Office’s
results and produce some visualizations that haven’t been seen before. There was even a surprise lurking in the data that required confirmation from the UK Met Office.

The first step was reading the data. Each meteorological station is
stored in a single text file that contains monthly average
temperatures, plus metadata about the station. For example, here’s
the beginning of file 724940 (which is a measuring station in San
Francisco, CA). The number 724940 is assigned by the World Meteorological Organization and a
quick look in its records says that this station is at San Francisco
International Airport.

Number= 724940
Name= SAN FRANCISCO, CA
Country= UNITED STATES
Lat=   37.6
Long=  122.4
Height= 6
Start year= 1871
End year= 2009
First Good year= 1871
Source ID= 10
Source file= Jones+Anders
Jones data to= 2001
Normals source= Data
Normals source start year= 1961
Normals source end year= 1990
Normals=   9.3  11.2  11.9  13.1  14.5  16.2  17.1  17.6  18.0  16.1   12.6   9.6
Standard deviations source= Data
Standard deviations source start year= 1941
Standard deviations source end year= 1990
Standard deviations=   1.3   1.2   1.1   1.2   1.1   1.3   1.4   1.4   1.4   1.0   1.0   1.4
Obs:
1871 -99.0 -99.0  10.7  11.8  12.4  13.8  13.7  14.4  15.8  16.6  12.7  11.6
1872  11.2  12.3  12.3  11.9  13.3  15.1  14.4  15.4  15.2  14.8  13.4  11.2
1873  12.2   9.9  12.1  12.2  12.7  13.7  14.2  14.9  14.2  14.9  13.9   9.9
1874   9.2  10.3  10.1  12.4  13.8  14.8  14.0  14.6  15.8  14.9  13.3  10.1
1875   9.4  10.5  10.6  12.3  13.3  14.3  14.1  14.1  14.2  15.7  13.7  10.6
1876   9.2  11.3  11.4  12.3  12.9  15.7  14.5  14.6  15.5  14.8  14.0  11.4
1877  12.2  12.8  13.4  12.0  12.6  16.2  15.2  14.7  16.1  14.3  13.4  11.2

There are observations starting in 1871 (although the two -99.0 values
indicate that there are no values available for January and February
of 1871) with one column per month. In the full data file there are
values for every month until October 2009.

The Normals values give the monthly average temperature for San
Francisco, CA based on calculating the averages between 1961 and 1990.
The latitude and longitude (to one decimal place) of the station are
given.

A small amount of Perl later (which you can download here)
and I had read in all 1,729 files and created a single Perl hash that
contained the metadata and all the observations.

Along the way the script checked for inconsistencies in the data (such
as verifying that the Normals values really were the average of the
1961 to 1990 observations) and threw up a small number of errors.
Almost all the differences
were in temperature data for Australasia and I wrote to the UK
Met Office asking for their help in understanding why the Normals
don’t look ‘normal’. More on that later.

With the data verified the script goes on to reproduce gridded data
for the entire globe using the same technique as the UK Met Office.
The full details of how their datasets are created is documented in
the paper Uncertainty
estimates in regional and global observed
temperature changes: a new dataset from 1850. It’s quite
technical, but worth sitting down and reading to understand how the
data is interpreted.

For gridding it’s simply a question of calculating the average
temperature from all the stations in the grid square and subtracting
that from the ‘normal’; temperature for that square to obtain the
anomaly. This is done on a month-by-month basis since January 1850.

Temperature trends are calculated separately for the northern and
southern hemispheres and then combined to get the global trend. For
the hemispheres the average temperature is calculated by averaging the
temperatures given by each grid box to obtain an average hemisphere
temperature for that month.

The average is actually a weighted average based on the latitude of
the grid box. At latitudes far from the equator the grid boxes cover
a much smaller area and so temperature values need to be scaled. The
weight is the cosine of the latitude of the central point of the grid
box.

My Perl program outputs .dat files compatible with gnuplot. Here are the northern
and southern hemisphere trends produced by the program. You can
clearly see the period of global warming starting in the mid-1970s.


The global temperature anomaly is just the average of the northern and
southern temperature anomalies. My program outputs another gnuplot
file which can be used to produce this graph:

But to really show off the data I decided to use Google Earth. The UK
Met Office had released a picture (see here)
of the October 2009 global temperature anomaly, so I decided to start
there and try to reproduce it. It wasn’t much work to get the Perl
script dumping out KML for
import to Google Earth. Once in Google Earth the same pattern of a
colder than average North America and warmer than average Europe was
clearly visible.

But I wasn’t satisfied with just October 2009 and decided to use
Google Earth’s animation capability to show the evolution of October
temperatures since 1850. Any element of a Google Earth KML file can
have a time-stamp or time span associated with it and Google Earth
will automatically create an animation.
The best way to experience this is to either grab my code and create
the 28Mb animation file yourself, or simply watch this YouTube
version:

You can grab the code and files from my blog at
http://www.jgc.org/blog/. If you do something interesting with it, or find problems, please let me know.

Epilogue

It turns out that the errors my program was reporting weren’t caused by my own bugs (as I first suspected) but because of genuine errors in the data. On December 18 I received a reply from the UK Met Office to my email regarding the errors confirming that they are genuine:

First off, thank you for bringing this to our attention. We have undertaken further investigation upon the full dataset and confirmed this. The error affects <1% of the network and is primarily in Oceania. It arises because normals were calculated outside of the update cycle and the normals for these stations were not updated when extra data were added in the normals period as CRUTEM3 was being finalised for publication.

We intend to add this information to our online Q and A for the data and we would like to credit you with pointing out the error. Would you be happy to be mentioned in this way?

Amazing what you can do with perseverance and a bit of Perl.

There's a long tradition in the UK of direct democracy, with citizens
petitioning the Prime Minister themselves. Typically, thousands of
signatures are collected on paper and then delivered directly to the
Prime Minister's home at No. 10
Downing Street in London. The petitioners arrive at No. 10 and
hand the signatures through the open front door.

But the British government has made great strides to bring many
aspects of government relations into the electronic age. Through the
non-profit MySociety.org the
government has created web sites (all with open-source code) for
citizens to interact with local and central government offices.

One such web site is the No. 10 Downing Street petitions page (its code
is open-source and can be found here).

I used the petitions web site, a collection of Web 2.0 technologies,
and a bit of media savvy to successfully petition the government to
apologize for the prosecution of the seminal computer scientist Alan Turing.

And I did most of it from the top of a red London double-decker bus
using an iPhone.

Alan Turing did three amazing things in his working life: he laid the
foundations of computer science by thinking up a theoretical computer
called the Turing
Machine, he worked through the Second World War breaking Nazi
German codes, and after the war he worked on artificial intelligence
and defined the Turing Test. His
life was cut short at 41 when he had begun to work on morphogenesis in
plants.

Alan Turing was also gay and he was prosecuted for “gross indecency” (essentially being gay) in 1952. To avoid prison he agreed to be injected with female hormones as a sort of ‘cure’ for homosexuality. Two years after his prosecution he was dead: he killed himself by eating an apple dipped in potassium cyanide.

June 23, 2009 was the anniversary of Alan Turing's birth (he would
have been 97) and I posted a blog entry entitled Alan
Turing deserves an apology from the British Government. It
generated a few comments and I posted a follow-up entry the next day
with an example of how
I would apologize for my government's actions in 1952.

That night I created a petition on the
No. 10 Downing Street web site asking for a government apology for the
treatment of Alan Turing.

On August 4, 2009 the petition was approved and made public. I
mentioned it on my blog, on Twitter, on Facebook, and posted it to Y
Combinator's Hacker News. At the time I thought I'd have a hard time
getting 500 people to sign. Little did I know the petition would
gather over 30,000 signatures in 37 days and elicit an incredible
apology from the British Prime Minister Gordon Brown preceded by a
personal call to my mobile phone.

This chart shows the number of signatures per day between August 4,
2009 and September 10, 2009. (click for larger view)

The same day the story appeared
on Reddit. Signatures started to come in slowly.

The next day the petition was picked up by the first journalist to
write about it: Jessica Geen of Pink News wrote an online only story
which made the story jump over from being covered just by computer
scientists and into the LGBT community. The LGBT press would turn out
to be a strong ally reporting on the growing petition throughout the
campaign.

Four days later, on August 9, 2009 the petition passed
500 signatures. This was the magic level needed to get a government
response. I was still pretty skeptical of getting an apology but I
certainly wasn't going to be satisfied by 500 names and kept promoting
it on Twitter, my blog, and elsewhere.

The first really big break came on August 16, 2009 when the Manchester
Evening News wrote
about the petition. Manchester was where Alan Turing died and where
he had worked before his death. There's a great deal of local pride
in Manchester's adopted local boy Alan Turing. The following night I
was a guest on
BBC Radio Manchester's gay hour.

On August 18, 2009 the petition made the national news with a major
story in The Independent, and at the same time the first celebrity
name appeared on the list of signatures: Richard
Dawkins.

With one celebrity name and national press I began to think the
petition might really get noticed. The following night Richard
Dawkins and I appeared
on Channel 4 News to talk about the petition (Dawkins was filmed
looking regal in his garden; I was filmed in classic programmer
clothing: bad shoes, dirty shorts and a crumpled shirt). The same day
I appeared
on the BBC World Service and PRI's The World.

Sitting on the bus each morning I would catch up on email regarding
the petition and scan the list of signatures looking for celebrities
who I would then try to contact through their agents. I also plotted
how to get the story in the press. Anyone who wrote about the story
got added to my Turing/Media email list and each morning I would
prepare an update on the story with the number of signatures, who had
signed and any other events, and send it out.

Over the next week many things happened: I appeared on BBC
Radio Ulster, I wrote a letter
to Her Majesty The Queen asking her to consider a posthumous
knighthood for Alan Turing, the veteran human-rights campaigner Peter
Tatchell signed the petition and I received an email from the
writer Ian McEwan to say that he had signed.

I knew it was time to get the story out as widely as possible and so I
emailed two BBC journalists that I knew to say that I thought the
petition was an important story and that they needed to cover it.

Do you think you’d be interested in covering the Alan Turing Petition?
It’s now got backing from Richard Dawkins and has been covered by BBC
Radio Manchester, BBC Radio Northern Ireland, The World Service,
Channel 4 News, The Independent, …

Watch: http://www.channel4.com/news/articles/uk/pardon+for+enigma+codebreaker+alan+turing/3315187
for good background.

There are now 4,800 signatories.

John.

On August 31, 2009 BBC News online covered
the story with a long article about the petition, and its celebrity
backers. The night before I had gone to bed feeling happy that there
were 5,000 signatures on my petition; I woke up to 16,000, by the next
morning there were 20,000. That day I appeared on BBC Radio Scotland.

The single enormous leap in signatures in the chart above happened
because of the BBC News online story.

On September 1, 2009 I appeared on BBC
Radio 4's PM program, CNN covered
the campaign, I appeared
on CBC's As It Happens, and Stephen Fry signed and tweeted
urging his followers to sign.

The same day I received two extraordinary emails. Unbeknownst to
anyone I had written to MI5 asking them to release documents about
Alan Turing's death in an effort to clear up any doubt about whether
his death could have been murder. They denied
my request.

The second email
came from a member of Alan Turing's surviving family. The BBC report
had erroneously said that he had no family. But that was incorrect:
Turing's three nieces remembered him well, and he had a surviving
nephew.

On the bus home I heard directly that Alan Turing's nieces had many
memories of their Uncle Alan. They even still had his teddy bear. I
hung up and sat at the back of the bus and cried quietly. I had
always felt that Alan Turing's treatment was appalling, but to hear
the family speak of the man was too much. I was convinced that I had
to see my campaign, which had started on an impulse, to its
completion.

Two days later I raced up to Bletchley Park to film the definitive
report on the campaign with BBC Newsnight's science editor Susan
Watts. The report ran that night and the same day international
coverage of the campaign exploded with stories in the major press
all over the world. The Newsnight story featured an interview with
Alan Turing's nieces and nephew describing the terrible treatment he
had endured and giving their blessing to the petition.

On September 7, 2009 I did a final piece of radio, appearing on BBC
Radio Ulster. The same day I began to feel unwell with what would
turn out to be a nasty bout of flu.

Lying in bed on September 10, 2009 I had to check my email because of
a work commitment the following day. In my Inbox was the following
email:

John – I wonder if you could call me as a matter of urgency, regarding
your petition. Very many thanks!

Kirsty

Kirsty xxxxxxx
10 Downing St, SW1A 2AA
Tel: 020x xxxx xxxx

Of course, I called back! I was told that the apology was coming that
night and that “Gordon would like a word with you”. At 19:44 that
evening my mobile phone rang and I was handed the Prime Minister.

“Hello John. It's Gordon Brown. I think you know why I'm calling you.”

Update The nice folks at No. 10 Downing Street and the petitions team released a spreadsheet of the actual day-by-day signatures for the petition period that gives an even clearer picture of the effect of different news outlets (the chart above came from my hand written, sporadic notes). (click for larger view)