Keuffel & Esser 4236 Polar Compensating Planimeter

This German-made fixed-arm polar planimeter has a 4-1/2" metal and bronzed brass tracer arm and an 8" bronzed brass pole arm welded to a cylindrical weight. A carriage on the tracer arm has a white plastic measuring wheel, vernier, and registering dial. The carriage is marked with a serial number: 1862. The pole arm is marked: K+E KEUFFEL & ESSER CO. It is also marked: MADE IN (/) GERMANY. A rectangular metal test plate with slanted corners is marked: 10 (/) sq. in. A glass magnifier is wrapped in a white facial tissue. The tissue is marked in ink: 1 (/) 1424 (/) 1798 (/) 6.26.
A wooden case covered with discolored black leather is lined with tan chamois leather, which has rust stains. A label pasted inside the lid of the case says that this is Keuffel & Esser model 4236, serial number 1862, with area of the neutral circle of 214.45 square inches. The case fits in a green cardboard box with masking tape along the edges. The top of the box is marked: A. P. M. One end of the bottom of the box has a red and green label marked: K+E (/) 4236 (/) COMPENSATING (/) POLAR PLANIMETER. The instrument was received with instructions, 1991.0882.02.
K&E introduced model 4236 in 1939 and began to use its K+E logo in 1949. Between 1955 and 1962, the open carriage was replaced with a closed top. The donor, biologist Anne P. Merrill (1916–2002), used this planimeter when she was researching the contraceptive effects of progesterone with Gregory Pincus and Min Chueh Chang at the Worcester (Mass.) Foundation for Experimental Biology. They received their initial grant money from Katharine McCormick in 1951, and it is likely Merrill purchased the planimeter around that time. In 1949 the instrument sold for $35.00, and in 1956 it cost $32.50.
References: Clark McCoy, "Collection of Pages from K&E Catalogs for the 4236 Family of Polar Planimeters,"; Kimberly A. Buettner, "John Charles Rock," Embryo Project Encyclopedia (2007),; Lara V. Marks, Sexual Chemistry: A History of the Contraceptive Pill (New Haven: Yale University Press, 2001), 92; Catalogue of Keuffel & Esser, 40th ed. (Hoboken, N.J., 1944), 226; K+E Price List, Applying to the 41st Edition Catalog, Part I (Hoboken, N.J.: Keuffel & Esser Co., 1949), 33; K+E Price List, Applying to the 42nd Edition Catalog, Part I (Hoboken, N.J.: Keuffel & Esser Co., 1956), 44; accession file.
Currently not on view
Object Name
date made
Keuffel & Esser Co.
Physical Description
metal (overall material)
plastic (overall material)
leather (overall material)
wood (overall material)
glass (overall material)
cardboard (overall material)
case: 6 cm x 23.8 cm x 9.5 cm; 2 3/8 in x 9 3/8 in x 3 3/4 in
place made
ID Number
accession number
catalog number
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History, Kenneth E. Behring Center


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