A planimeter is a technical drawing instrument used to measure the surface area of an arbitrary two-dimensional shape by tracing the perimeter. The precise way in which they are constructed varies, the main types of mechanical planimeter being polar; linear; and Prytz or "hatchet" planimeters. They can be justified by appealing to Green's theorem and were invented by the Swiss mathematician Jakob Amsler-Laffon in 1854. Electronic versions also exist.

The first planimeter was invented by Hermann in 1814 and there were many subsequent developments before Amsler's famous planimeter.

There was a book written in 1903 on the planimeter, The Polar Planimeter by J. Y. Wheatley.

External links

• Whistleralley site
• Larry's Planimeter Platter
• Wuerzburg Planimeter Page
• Robert Foote's planimeter page
• Computer model of a planimeter

Dimensional instruments | Technical drawing

Planimeter | プラニメータ | Planimetr | planimeter