Thursday, December 10, 2009

Charles Babbage's Difference Engine

I am fascinated by early 19th-century technological breakthroughs, so I was really pleased to be referred to this NPR piece on the Babbage Difference Engine, which includes audio, text, photo slideshow, and video.

Here's an excerpt:
Charles Babbage, the man whom many consider to be the father of modern computing, never got to complete any of his life's work. The Victorian gentleman was a brilliant mathematician, but he wasn't very good at politics and fundraising, so he never got the financial backing to finish any of his elaborate machine designs. For decades, even his fans weren't certain whether his computing machines would have worked.

But Doron Swade, a former curator at the Science Museum in London, has proven that Babbage wasn't just an eccentric dreamer. Using nothing but materials that would have been available to Babbage in the 1840s, Swade and a group of engineers successfully built Babbage's Difference Engine — and a version is now on display at the Computer History Museum in Mountain View, Calif.

The Difference Engine fills half a gallery and stands taller than most men. It's 5 tons of cast iron, steel and bronze woven together from 8,000 distinct parts. Though it looks like it could be a sculpture, the machine is essentially a giant calculator. Tim Robinson, a docent at the museum, says it's "the first automatic calculating machine."

This engine — made from 162-year-old designs — doesn't have a power pack; it has a hand crank. Robinson works up a sweat as he turns it. "As long as you keep turning that crank, it will produce entirely new results," he says.

Most importantly, the machine produces accurate results. In Babbage's time, England reigned over a vast global empire. To navigate the seas, captains used books filled with calculations — but these equations were all done by fallible human minds.

"If the tables had an error," Robinson says, "a ship could either get lost or run aground, so lives and property were thought to be at stake."

The story goes that Babbage was inspired to create the Difference Engine one day when he came across multiple errors in a book of astronomical calculations. "I wish to God these calculations had been executed by steam!" he exclaimed.

Of course, this episode inspired one of the first steampunk novels.

P.s. It was designed to have a printer! And has one now!

Image: Wikipedia picture of the American exemplar.

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