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16 Are the Androids Dreaming Yet? of these skills were lost in the Dark Ages but, once the Renaissance was underway in the 16" and 17" centuries, complex mechanical clocks were devised that were capable of predicting the motions of the planets to a high degree of precision. Mechanical, hand-cranked calculators appeared in the mid-18" century, and in 1886 Charles Babbage conceived the first programmable computing machine, The Analytical Engine. It was designed to read programs from cards, and used cogs and wheels to perform the calculations. His first machine - The Difference Engine — was designed to help the Admiralty calculate tide tables, but Babbage realized he could generalize it to compute almost any function. He ran out of money to complete any of his machines, but in the 20th century a dedicated band of enthusiasts built a working model of Difference Engine No.2. One copy sits in the London Science Museum and another in the Computer History Museum in California. These difference machines are not Turing complete and his Analytical Engine has never been built. 19" Century Calculators HOUSE_OVERSIGHT_015706