In 1936, Russian scientist Vladimir Lukyanov was confronted with the problem of devising a system to improve the quality of Russian concrete and the efficiency of its manufacture. When furnished with a few requirements for the concrete, Lukyanov was expected to calculate the resulting concrete’s other attributes, such as load capacity, curing time, temperature limits, etc. This involved a lot of tedious manual calculations with partial differential equations.

Lukyanov’s solution was to build one of the world’s first programmable computers. Like all early computers, Lukyanov’s invention was a massive analog calculator, but one design element set it apart: it used water to perform its calculations. Lukyanov outfitted a room-sized array of glass tubes with a series of valves and plugs, and these constituted the data inputs. An operator would turn knobs and move plugs to correspond to the input values, then engage the pumps to slosh water through the intricate plumbing until the water settled into various tanks. The ultimate water level in each tank indicated the results of the calculations, and thus indicated the various properties of the resulting cement.

Lukyanov’s water computer was the first machine in the world capable of solving partial differential equations.