Charles Babbage was an English mathematician, inventor and engineer from the 19th Century who gave birth to the idea of a programmable computer. To improve on the human-generated tables of natural logarithms and the like, he sought to produce a Difference Engine to approximate polynomials. The difference engine he began constructing in 1822 took advantage of the fact that finite differences could be used to avoid multiplication and division (see some of the methods I describe on my Math Tricks page). According to Wikipedia, the first difference engine comprised 25,000 parts and weighed some 13,600 kg, standing 2.4 m high. Babbage did not manage to complete the Difference Engine although earlier prototypes were found in his laboratory. “Difference Engine 2″ was finally constructed just 10 years ago from 1989–1991 using Babbage’s original plans and with 19th Century manufacturing tolerances. It performed its first calculation at the London Science Museum and its results were correct to 31 significant figures. Babbage ditched the Difference Engine in favour of a more complex punched-card reading machine he called the Analytical Engine. This Babbage Machine would have employed sequential control, branching, and looping, and would have been the first mechanical device to be Turing-complete. It is interesting to note that although the abacus and the mechanical calculator have been replaced by nano-technology, the Economist magazine in its special “end of the millennium” black cover issue, carried an article entitled “Babbage’s Last Laugh” where the use of mechanical computation was resurrected and favoured in the context of high radiation or high temperature environments. Maybe we space weather modellers like myself should take note!
