It is extremely doubtful whether you will find this word in any dictionary, but it was once well known within a narrow circle to identify a type of analogue computer that was designed to model a national economy. It started with Bill Phillips, a student at the London School of Economics in the late 1940s, who had trouble understanding his lecturers’ explanations of macroeconomic theory. He wanted to be able to visualise the flow of money round the economy and see what happened if (say) inflation went up, or you gave pensioners more money, or increased fuel taxes. Being a good practical engineer, he built a hydraulic device which used water coloured red to simulate money — you poured the money in at the top and it flowed through a complicated set of tubes and tanks and over sluices, finally operating a pen plotter which printed out the results. This was a true analogue computer, which became quite famous for a while; 14 of them were constructed for Harvard University, the Ford Motor Company and the Bank of Guatemala, among others. One is now on permanent display at the Science Museum in London.