Lost area-measuring tool (2022) [video]

I also found interesting the other devices that have no moving parts, like the Steinhaus Longimeter[1]. It's just a transparent sheet with lots of jumbled lines printed on it, and counting the lines somehow calculates the length of curves!

[1] https://www.youtube.com/watch?v=-ZE2Iv-8tsA

Watch the video from here for 1 minute to get how it works.[1] The device is simple and clever. The YouTuber padded this to 9 minutes.

[1] https://youtu.be/xSgf_wxJIlk?t=170

Nice object. Skip the intro babble and jump straight to the explanation of the working principle: https://www.youtube.com/watch?v=xSgf_wxJIlk&t=242s

There's also the planimeter -

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

https://www.youtube.com/watch?v=jMvEOmpy8Kw&t=91s

I very much enjoy the dry hunour in this series of videos. The exciting tone for something somewhat inherently dry is wonderful.