Most people think of computers as very modern inventions, products of our new technological age. But actually the idea for a computer had been worked out over two centuries ago by a man (26) Charles Babbage. Babbage was born in 1791 and grew up to be a brilliant mathematician. He drew up plans for several calculating machines which he called "engines". But despite the fact that he (27) building some of these, he never finished any of them. Over the years people have argued (28) his machines would ever work. Recently, however, the Science Museum in London has finished building (29) engine based on one of Babbage's designs. (30) has taken six years to complete and more than four thousand parts have been specially made.