On the New York Times website, there is a column about a water-based analog computer that was used to model the economy back in the 1950s:
Water flows through a series of clear pipes, mimicking the way that money flows through the economy. It lets you see (literally) what would happen if you lower tax rates or increase the money supply or whatever; just open a valve here or pull a lever there and the machine sloshes away, showing in real time how the water levels rise and fall in various tanks representing the growth in personal savings, tax revenue, and so on.
It’s both clever and amusing. Certainly, operating such a machine would have been less tedious than doing all the calculations with a pencil and paper. There is a video of the machine working on Cambridge University’s website.