Carry lever and drawing, Babbages Difference Engine No 2, 1991.

UNITED KINGDOM - OCTOBER 08: British computing pioneer Babbage (1791-1871) designed Engine No 2 between 1847 and 1849, as part of his attempt to mechanise the production of mathematical tables. The calculating section of the Engine weighs 2.6 tonnes and consists of 4000 separate parts. This Engine was never constructed in Babbage's lifetime. Factors cited include his allegedly difficult personality, disputes with his engineer, Joseph Clement, political instability, the eventual withdrawal of government funding, and limitations in Victorian machine tool technology. The Science Museum began construction of Difference Engine No 2 in 1985, and the calculating section was completed in 1991 for the bicentennial of Babbage's birth. (Photo by SSPL/Getty Images)