Sanahill Mechanical Planimeter With Box Manometer

Engineers and cartographers normally use planimeters to find the area of an irregular shape, such as the area of a city. Medical researchers also used this small instrument to measure biologic phenomena. Jakob Amsler, professor of mathematics at the University of Sscaffen hausen in Switzerland developed this instrument in 1854. It consists of two arms: one affixed to the page using a pin, the other containing a stylus used to trace around the unknown area. As the region is traced, a small wheel rotates against the paper, recording the area on a dial.