[piersj225]

This is something the Russians worked on,

https://en.wikipedia.org/wiki/Water_integrator

I've been told analogue computers got pretty far too,

https://en.wikipedia.org/wiki/Analog_computer

[zdw]

The Computer History Museum has a surprisingly large exhibit on these if you ever get to visit:

https://www.computerhistory.org/revolution/analog-computers/...

It's pretty fascinating, and a great example of working within the limitations of hardware at the time.