Chapter 8: Water on the Brain

What is a hydraulic computer doing in a book called “electronic brains”? Well in the proposal for the original radio series I just needed a fourth story, one from around this time – the late 1940s – and the idea of a computer that computed by the flow of water instead of the flow of electricity was irresistible. And very quickly as I started to talk to people about Bill Phillips I realised that there was no way I could leave his story out – he was perhaps the most extraordinary man in a book of extraordinary people. It was also a salutary reminder that electronic computing was not always the best answer per se, particularly in its early days. He needed a machine that would demonstrate the flow of money through an economy, and moreover that showed the application of hydro-dynamic equations to monetary relationships. When persuaded to build it he soon realised it made a remarkable teaching tool as well, at a time when nothing in computing could create that kind of visual model.
It’s a curious thing that in some areas of economics he may be better remembered for his definition of the relationship between unemployment and inflation – low inflation tends to bring high unemployment and high unemployment goes with low unemployment. He only intended that to be an observation and a challenge to governments to manage the economy in such a way as to control inflation without causing mass unemployment. Unfortunately many chose to interpret the relationship the other way round, deliberately raising unemployment as a tool to control inflation. It became known as the Phillips Curve, not because he claimed it in his name but because others dubbed it that. Yet it should more properly be known as the Brown Curve after the Leeds Professor who entirely coincidentally was the first to put some money up to build the hydraulic computer.
This is one of those computers that can still be seen complete and original, in this case in the Science Museum in London, England. I have been saddened to see people walk past it with little more than a glance – it repays a few minutes study, wondering at the ingenuity of the interlinked valves, sluice gates, springs, cords, pens and the like. And run the video next to it – some old BBC footage of the machine in action (it can’t be kept in running order due to the corrosive effects of the coloured water, so it is now in effect embalmed). And imagine it taking pride of place in the Central Bank of Guatemala, modelling the national economy in the 1950s.
last update 21/3/05