There's also the planimeter - https://en.wikipedia.org/wiki/Planimeter https://en.wikipedia.org/wiki/Planimeter https://www.youtube.com/watch?v=jMvEOmpy8Kw&t=

There's also the planimeter - https://en.wikipedia.org/wiki/Planimeter https://en.wikipedia.org/wiki/Planimeter https://www.youtube.com/watch?v=jMvEOmpy8Kw&t=91s https://www.youtube.com/watch?v=jMvEOmpy8Kw&t=91s