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 ...

A thermometer is a simple analog computer. As the temperature varies, the mercury moves correspondingly. A slide rule is another example. Although special-purpose, complex analog computers are ...