The analog computer of decades-gone-by is something ... Looking over the project Wiki there are a few application examples and some explanatory notes. Schematics are shown, albeit only images ...

for example. There was a time when it wasn’t clear analog computers wouldn’t dominate. But although they failed to win the computing architecture war, they are still around. As [Bill] points ...

In the 1930s, the Russian scientist Vladimir Lukyanov built an analog computer known as the "Water Integrator" or "Lukyanov's Integrator." This computer was built to solve partial differential ...