Difference engine

The difference engine is an automatic mechanical calculator designed to tabulate the values of polynomial functions using the method of finite differences, avoiding the multiplication and division that direct calculation would require. The English mathematician Charles Babbage began building a small difference engine around 1819, completed it by 1822, and announced it to the Royal Astronomical Society that June, intending it to produce mathematical tables such as those used in navigation and engineering more cheaply and reliably than tables computed and set by hand. Babbage's own full scale designs were never completed in his lifetime, but the London Science Museum built a fully working Difference Engine No. 2 to his design in the 1980s and 1990s, demonstrating that it could have functioned with the manufacturing technology available in the nineteenth century.