A polar planimeter (specifically an Allbrit / Amsler-type mechanical planimeter made by W.F. Stanley & Co., London), housed in its original lined presentation case.
Function: A mechanical analog measuring instrument used to calculate the area of a two-dimensional plane shape (such as land parcels on maps, engineering blueprints, or irregular shapes).
How it works: An operator traces the outline of the shape with a pointer (tracer arm), while a small precision wheel rolls and slides on the paper. The mechanical linkage integrates the motion and reads out the area using the dial, vernier scale, and counter drum.
Handwritten calibration date "May 1943" serial number (INST. No. 5347).
Available at La La Vintage 67 Semaphore Road, Semaphore SA 5019 (Next to Odeon Cinema)
