Measuring area using a planimeter

If you're ever out in the jungle without your planimeter and urgently need to calculate the area of something, remember that you can always use your pocket knife as a planimeter. Instructions on how to do it here...

https://spaco.org/Blacksmithing/FinnishPlanimeter.htm

At the end of the above article is a reference to...

Prytz Planimeters

which describes the process of making a "hatchet" planimeter from a bent rod.

I've tried both the pocket knife and a "hatchet" made from coat hanger wire and they both work well if one exercises a bit of care in the tracing.

Measuring area using a planimeter - GIF