In 1821, 30-year-old inventor and mathematician Charles Babbage was poring over a set of printed mathematical tables with his friend, the astronomer John Herschel. Finding error after error in the manually evaluated results, Babbage made an exclamation, the consequences of which would not only dominate the remaining 50 years of his life, but also lay the foundations for the modern computer industry: 'I wish to God these calculations had been executed by steam!'A few days later, he set down a plan to build a machine that would carry out complex mathematical calculations without human intervention and, at least in theory, without human errors. The only technology to which he had access for solving the problem was the cogwheel escapement found inside clocks. Babbage saw that a machine constructed out of hundreds of escapements, cunningly and precisely linked, might be able to handle calculations mechanically. The story of his lifelong bid to construct such a machine is a triumph of human ingenuity, will and imagination.