Amsler Type 3 Polar Planimeter

This brass instrument has a 6" pole arm, an adjustable 9" tracer arm, and white plastic measuring wheel, vernier, and registering dial. The tracer arm is marked for the positions: 21,070; 21,097; 21,320; 22,884. Underneath the pole arm is marked: 19. Underneath the tracer arm is marked a serial number: No 46952. An unvarnished wooden case also holds a cylindrical pole weight, a metal test plate (presumably not original to the instrument), and a brass test plate marked: 83.2 [square] cm.

In 1854 Jacob Amsler, a Swiss teacher and mathematician, devised a planimeter that did not need the cones or wheel-and-disc constructions of earlier instruments, such as 1983.0474.02 and 1986.0633.01. His smaller and simpler device also used polar coordinates rather than the Cartesian coordinate system. The workshop he established in Schaffhausen, Switzerland, ultimately manufactured nine forms of polar planimeters.

This example is a Type 3. The date is based on the serial number, compared to serial numbers on other Amsler planimeters in the collection. For instructions, see 1986.0316.09; 1999.0250.02 is an English translation of this leaflet. In 1907 the Crosby Steam Gage & Valve Co. of Boston sold the Amsler Type 3 planimeter for $30.00.

The instrument was received at the Smithsonian in 1986.

References: Peggy Aldrich Kidwell, "Planimeter," in Instruments of Science: An Historical Encyclopedia, ed. Robert Bud and Deborah Jean Warner (London: Garland Publishing, 1998), 467–469; Michael S. Mahoney, "Amsler (later Amsler-Laffon), Jakob," in Dictionary of Scientific Biography, ed. Charles Coulston Gillispie (New York: Scribner, 1970),

Currently not on view