Mathematical Instruments
Mechanical Instruments for Drawing, Measuring and Integrating
Drafting Instruments
Rechenscheiben und Rechenwalzen
Planimeters and Integrators
Alfred J. Amsler & Co.
Gottlieb Coradi
Ott & Coradi
Coradi AG
Polar Planimeter
Rolling Disc Planimeter
Integraphs
Hünenberger-Murbach
Various Makers