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      I read the book The Difference Engine about Babbage a few years ago.


      As far as I remember, there’s a museum in Britain that houses Babbage’s original works, i.e. the unfinished difference engine and the analytical engine. I think the difference engine could solve equations, and the analytical engine was basically a Turing complete computer, even connected to a plotter, as mentioned in this blog post. (He didn’t finish the difference engine before starting the analytical engine, which made his funders upset. Talk about scope creep :-) )

      Around the turn of the millenium, the staff at this museum set out to see if Babbage’s works could ACTUALLY be built. How close was he to building a computer?

      I jot down a few notes about each book I read, and here are a few:

      • This book was haunting because Babbage was intellectually alone. He worked on it for decades, and was funded for decades, but they pulled the plug eventually. And he talked about it until his death. His SON worked on some of the designs when the son was 86 years old!! And the son didn’t finish it either.
      • He did have the help of Lovelace, but he worked on it for many years before meeting her (he was significantly older), and for many years after.
      • There were also some interesting stories of other groups inspired by him, closer to his son’s generation as I recall, who ALSO devoted significant effort to the project, and also failed to build or commercialize it.
      • The museum project in the 2000’s just BARELY got by. I think they worked for like 5 or 7 years? In my notes I say that I found their own explanation of what they got working “fishy”. It was something about computing powers of 7. But it very nearly didn’t work, but then they say it worked right at the end. I didn’t understand why it worked from their own explanation.

      So yes I was left with the impression that Babbage was a genius, but also a haunted one. The fact that multiple groups of people found his designs and tried to build them decades and centuries later is truly remarkable.

      For those interested in Ada Lovelace’s story, here’s a very long article from Stephen Wolfram exploring it, which analyzes original documents. As far as I remember he is much more positive on her contribution than “the Difference Engine”. That could be because the authors of that book spent literally years machining and manufacturing parts, and so they appreciated that difficulty a lot more.


      edit: Fixed transposition of difference engine / analytical engine. What’s even more amazing is that this staffed and funded museum group spent years making the difference engine, and just barely made it. The analytical engine was even more ambitious! Looks like an effort to create the analytical engine has also stalled, although that could be somewhat due to incomplete source material:


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      To say nothing of Ada Lovelace - a true genius.

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        This post is pretty interesting because it removes a lot of the doubt and mystery about her contributions to CS - she even wrote the first bug!

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        Did Ada Lovelace have any books or essays? I Would like to have a comprehensive grasp of her work.

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          Her sole published work was her report on Babbage’s engine. At the time it was still difficult for women to be accepted as scientists and interpreting men’s work was one of the few paths open; Ada’s tutor Mary Somerville was (jointly) the first woman ever accepted into the Royal Astronomical Society, and she had made her name by translating Laplace’s work from French into English. (In the previous century Émilie du Châtelet had followed a similar path translating Newton from English into French.) George Boole who was Ada’s contemporary — they were born in the same year — had a daughter who was the first ever female professor of chemistry: it was still early times for women in science… Ada herself was unable to access even the Royal Society’s library, and that with her husband being a Fellow. (The RS would not accept women until 1945!)

          As for what happened after publishing her report, she had a falling-out with Babbage and, while they eventually reconciled, they never properly worked together again. She lived for less than a decade after her article was published and spent many of those years sick. A quote from “The Lovelace–De Morgan mathematical correspondence: A critical re-appraisal”:

          It is the contrast between the mathematics that she actually wrote and her mathematical potential that has fuelled much of the debates regarding Lovelace’s mathematical ability; for despite De Morgan’s prediction that she would “get beyond the present bounds of knowledge”, we have no evidence that she created original mathematics in either published or unpublished form. The reasons for this await further research, but were probably a combination of a lack of training, lack of good health, lack of a collaborator and ultimately a lack of time before her death in 1852 at the early age of 36.

          It is possible that with more time and better health, she would have published more work. But she didn’t.

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      A good cold shower is the Royal Astronomy Society’s report on the analytical engine. It debunks the myth that nobody else saw the value, or that it wasn’t built for political reasons:

      • We are of opinion that the labours of Mr. Babbage, firstly on his Difference Engine, and secondly on his Analytical Engine, are a marvel of mechanical ingenuity and resource.
      • Apart from the question of its saving labour in operations now possible, we think the existence of such an instrument would place within reach much which, if not actually impossible, has been too close to the limits of human skill and endurance to be practically available.
      • We are also of opinion that, in the present state of the design, it is not more than a theoretical possibility; that is to say, we do not consider it a certainty that it could be constructed and put together so as to run smoothly and correctly, and to do the work expected of it.
      • We think there is even less possibility of forming an opinion as to its strength and durability than as to its feasibility or cost.
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      I’ve been fascinated with Babbage’s difference and analytical engines since I read about him in Gödel, Escher & Bach. A true genius for sure. I had a lot of fun understanding and implementing the method of finite differences in software (the one he used in the difference engine):


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      Again, I’ve always known it was the first programmable computer

      Hm, not sure if I would call it the first programmable computer although could be. My mind flies to the antikythera mechanism, when thinking about the first programmable machine but I understand the scope is limited.

      The real question is why on earth did we had to wait centuries to get from the Antikythera mechanism constructed ~ 150 BC to Babbage’s engine conceived in 1837 AD.

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        Pretty sure the Antikythera mechanism is a single-purpose computer that computes astronomical events. It’s no more programmable than a mechanical clock is. As far as I know it certainly can’t do logic and perform different operations on the results.

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          Yeah it’s also an analog computer, while Babbage’s analytical engine and difference engine are digital computers. Big difference.

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        The real question is why on earth did we had to wait centuries to get from the Antikythera mechanism constructed ~ 150 BC to Babbage’s engine conceived in 1837 AD.

        We didn’t. Medieval astronomical clocks regularly matched the complexity of the Antikythera mechanism.

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      As to why Babbage decided on 50-digit numbers, he was very inspired by Prony who had a large team calculating sine values up to 25 decimal places and logarithms up to 19 places, and it’s possible that he wanted to outdo him. Or, perhaps once Babbage had figured out how to do carries in O(1) instead of O(Ndigits) time, he wanted to take advantage of this to the fullest!

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      On The Metal did a very interesting interview with John Graham-Cumming about Babbage and Lovelace a little while ago. I recommend it: https://share.transistor.fm/s/4e9a14a9

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