mbone writes "In the New York Times, there is an interesting story about a hydraulic analog computer from 1949 used to model the feedback loops in the economy. According to the article, 'copies of the 'Moniac,' as it became known in the United States, were built and sold to Harvard, Cambridge, Oxford, Ford Motor Company and the Central Bank of Guatemala, among others.' There is a cool video of the computer in operation at Cambridge University. I remember that the Instrumentation Lab at MIT still had an analog computer in its computer center in the mid-1970s. Even then, it seemed archaic, and now this form of computation is largely forgotten. With 14 machines built, it must have been one of the more successful analog computers — a supercomputer of its day. Of course, you have to wonder if it could have been used to predict our current economic difficulties."