The difference engine is a mechanical calculator first developed by Charles Babbage in 1822. It is capable of computing several sets of numbers and making a hard copies of the results. Due to a lack of funding, he was never able to complete a full-scale functional version of this machine. However, in June 1991, the London Science Museum completed the difference engine No 2 for the bicentennial year of Babbage's birth and later completed the printing mechanism in 2000. Below is a video from Wired magazine that gives a good overview of the difference engine No. 2 shown at the Computer History Museum.