Water integrator
More info
- Creator
- Vladimir Lukyanov
- Released
- 1936
- Type
- Analog computer
A Soviet computer that solved differential equations using water in connected vessels — the level was the variable and the flow was its derivative.
Lukyanov built it in 1936 for a thoroughly concrete problem: freshly poured concrete on Soviet railway works was cracking as curing heat spread unevenly, and the heat equation could not be solved by hand fast enough to matter. His answer was to build the equation physically. Vessels of perspex and sheet metal are joined by tubes whose restriction stands for the material's thermal resistance; fill them, release, and the water levels settle according to precisely the same partial differential equation that temperature obeys. You read the answer off a glass scale.
The machine does not calculate, it imitates. It was also easy to reprogram — swap tubes and vessels and you have a different equation — which gave it a long life well outside concrete. Production versions designated IGL were used for permafrost, mine ventilation, oilfield flow and rocket engine cooling into the 1980s, decades after digital machines should have rendered them pointless.