clipped from: www.fourmilab.ch 
The analytical engine, an important step in the history of computers, was the design of a mechanical general-purpose computer by the British mathematician Charles Babbage. It was first described in 1837, but Babbage continued to work on the design until his death in 1871. Because of financial, political, and legal issues, the engine was never actually built. In its logical design the machine was essentially modern, anticipating the first completed general-purpose computers by about 100 years.