Babbage's Difference Engine

Charles Babbage completed plans for an elaborate, all-mechanical calculator in 1849. His Difference Engine #2 was so complicated, with more than 8,000 separate parts, that it was never built during his lifetime. But now, Babbage's Difference Engine is on display in Silicon Valley ... and it works!

The five-ton bronze, steel and cast iron contraption is operated by a crank handle and can calculate the results of elaborate trigonometric and logarithmic functions with 31 digits of precision. What's more, it has a printer which stamps the results of its calculations on paper and on a plaster tray, which could be used to create lead type for printing books of mathematical tables.