However, Babbage’s Difference Engine No. 2, designed in the 1840s to use 4,000 brass cogs, was actually constructed by the Science Museum in 1991, and with some minor alterations works to this day, capable of calculating to thirty-one places of decimals — an impressive power. It weighs three tons and cost £300,000 — considerably cheaper, in relative terms, than the original.4 ♣
