MONIAC

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.

MONIAC had been designed to be used as a teaching aid but was discovered also to be an effective economic simulator. At the time that MONIAC was created, electronic digital computers that could run complex economic simulations were unavailable. In 1949 the few computers in existence were restricted to government and military use. Neither did they have adequate visual display facilities, so were unable to illustrate the operation of complex models. Observing the MONIAC in operation made it much easier for students to understand the interrelated processes of a national economy. The range of organisations that acquired a MONIAC showed that it was used in both capacities.