MONIAC

The MONIAC (Monetary National Income Analogue Computer) also known as the Phillips Hydraulic Computer and the Financephalograph, was created in 1949 by the New Zealand economist Bill Phillips (William Phillips) to model the national economic processes of the United Kingdom, while Phillips was a student at the London School of Economics (LSE). The MONIAC was an analogue computer which used fluidic logic to model the workings of an economy. The MONIAC name may have been suggested by an association of money and ENIAC, an early electronic digital computer.

The MONIAC was approximately 2 m high, 1.2 m wide and almost 1 m deep, and consisted of a series of transparent plastic tanks and pipes which were fastened to a wooden board. Each tank represented some aspect of the UK national economy and the flow of money around the economy was illustrated by coloured water. At the top of the board was a large tank called the treasury. Water (representing money) flowed from the treasury to other tanks representing the various ways in which a country could spend its money. For example, there were tanks for health and education. To increase spending on health care a tap could be opened to drain water from the treasury to the tank which represented health spending. Water then ran further down the model to other tanks, representing other interactions in the economy. Water could be pumped back to the treasury from some of the tanks to represent taxation. Changes in tax rates were modeled by increasing or decreasing pumping speeds.

Savings reduce the funds available to consumers and investment income increases those funds. The MONIAC showed this by draining water (savings) from the expenditure stream and by injecting water (investment income) into that stream. When the savings flow exceeds the investment flow, the level of water in the savings and investment tank (the surplus-balances tank) would rise to reflect the accumulated balance. When the investment flow exceeds the savings flow for any length of time, the surplus-balances tank would run dry. Import and export were represented by water draining from the model, and by additional water being poured into the model.

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