The Machine That Showed the Flow of Money


People have been searching for new ways to combine money and technology for as long as both have existed. Some mergings have worked better than others, while others have fallen into obscurity. Take the MONIAC, for example.


Also known as the financephalograph, the Monetary National Income Analogue Computer, or MONIAC, used “fluid logic” to depict the flow of finances in the British economy. Different aspects of the economic system were represented by tanks of water, connected by tubes. Adjusting the amount of “money” in any tank caused water to flow throughout the system, reflecting the changes. Increasing the tax rate caused water to flow into the treasury tank, while increasing spending would drain it. The MONIAC was found to be accurate to within 2%, and while originally meant as a teaching tool, could also be used as an accurate economic simulator.


“The flow of water between the tanks was determined by economic principles and the settings for various parameters. Different economic parameters, such as tax rates and investment rates, could be entered by setting the valves which controlled the flow of water about the computer. Users could experiment with different settings and note the effect on the model. The MONIAC’s ability to model the subtle interaction of a number of variables made it a powerful tool for its time. When a set of parameters resulted in a viable economy the model would stabilise and the results could be read from scales. The output from the computer could also be sent to a rudimentary plotter.”



The MONIAC was invented by New Zealand economist Williams Phillips in 1949 while he was at school at the London School of Economics. Computers were not widely available at the time, so Phillips scrounged parts to build his machine. Along with ordinary scrap metal and plastic, he also used war surplus parts, some from Lancaster bombers. The MONIAC prototype cost Phillips £400 to create (£13,000 in 2015 money); however, after he demonstrated the machine to economists, he was offered a teaching position at the London School of Economics, so it seems to have been a wise investment.



3As more complex computer systems became available, the MONIAC fell out of use, but the quest for better ways to combine money and technology has continued. Our own machine is the newest part of this search, and can sort and grade coins on an unprecedented scale. We’re currently testing an app that uses the same technology to identify coins by photo; for more information, contact

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