In the heyday of analog computing, Vladimir Lukyanov designed an advanced computer that used water as the storage media. Various tubes, tanks, valves, pumps and sluices churned out solutions for the user based on variables such as changing tax rates or increasing money supply. From the Russian magazine Science and Life:
Built in 1936, this machine was “the world’s first computer for solving [partial] differential equations,” which “for half a century has been the only means of calculations of a wide range of problems in mathematical physics.” Absolutely its most amazing aspect is that solving such complex mathematical equations meant playing around with a series of interconnected, water-filled glass tubes. You “calculated” with plumbing.