Planimeters for Other Purposes

Polar planimeter for measuring areas on a sphere! (Amsler, 1884)



Measures average radius of a curve from a point

By Green's Theorem this equals a quantity proportional to the electric potential at a point due to a region of uniform electric charge.


Radial Square Root Planimeter


 
This measures 


What do these do?


 


Moment Integrator (Amsler, late 1800's)

Measures area, centroid, and moment of inertia





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