Sunday, March 11, 2007

The Difference Engine

I've just finished reading Doron Swade's "The Difference Engine: Charles Babbage and the Quest to Build the First Computer". In it, Swade (a curator at London's Science Museum) tells two stories: the first is a biography of Charles Babbage, the 19th century polymath who designed a series of mechanical computing devices that were never built, and the other is Swade's own story of building a working version of Babbage's Difference Engine No. 2 for the Science Museum.

I've long been fascinated by the idea of clockwork computers, and had a general idea of Babbage's story, but Swade dispels some common myths that have surrounded him. For example, one often reads that 19th century manufacturing techniques were too crude to create parts with the required tolerances, but Swade's studies on the surviving parts of Babbage's unfinished engines shows that they were sufficient. Rather, the issue was political and personal. Babbage's constant redesigning of his engines rather than creating a working version of any of them, combined with his skill at making enemies in influential places, meant that the British government finally lost patience and discontinued funding. Swade also deflates the romantic idea of Lord Byron's daughter Ada Lovelace being the "first programmer"; While Ada did provide examples of engine programs (really just algorithms) in a series of notes to her translation of a French article about the Analytical Engine, they unfortunately seem to be paraphrases of Babbage's own work.

Oh -- one last note -- the title may lead to confusion with William Gibson & Bruce Sterling's alternative history novel also entitled "The Difference Engine" in which Babbage Engines were built and started the Information Age a century early. That's a different book!


Neil said...

That's a different book!
And a very enjoyable one, I thought. Part sci-fi, part alternate history, part "Boys Own" adventure romp. It flags a bit towards the end for me, but still a favourite.

Jonathan Badger said...

Yes, I'm rather fond of it myself -- and hey, isn't Edward "Leviathan" Mallory a bit of a role model for us? I mean although a paleontologist, he's a bit of a "clacker", interested in developing Engine-analyses of his findings -- a proto bioinformatican, if you will.