Keuffel & Esser 4211 Polar Planimeter

This German-made polar planimeter has a metal tracer arm attached to a brass arm holding a brass weight, both of which are painted black. The weight is marked: KEUFFEL & ESSER Co (/) GERMANY. A black frame, or carriage, on the tracer arm holds a white plastic measuring wheel with vernier and a horizontal white plastic registering dial. The carriage is marked in white: No 3515. A metal test plate is marked: 10 (/) sq. in.

A wooden case is covered with black leather and lined with blue velvet. The top of the case is marked: KEUFFEL & ESSER CO. (/) 4211. A rectangular paper label inside the lid is marked: KEUFFEL & ESSER COMPANIE [sic] (/) PLANIMETER NO 4211 (/) SERIAL NO 3515. The label has a table for different scales and values of units on the vernier. The constant is 16,000 square inches. The circumference of the measuring roller is handwritten as 2.38469 inches.

A square (1-3/4") card in the case is marked: K+E PLANIMETER (/) 4211 (/) Serial No. 3515 (/) Area of Neutral Circle = 16000 sq. in. (/) This value to be used only when (/) planimeter makes a complete (/) revolution around the pole. (See (/) instructions.) (/) KEUFFEL & ESSER CO.

Keuffel & Esser offered model 4211 from 1925 to sometime between 1936 and 1939. It cost $25.00 in 1936. The serial number on this example indicates it was manufactured after MA.317925.03. For instructions, see MA.317925.03.

K&E introduced the logo on the card in 1949. The model number is written by hand, and a printed "4236" is scratched out. K&E sold model 4236 from 1939 to 1962. This model closely resembled model 4211 and may indeed have replaced that model. The markings on the card suggest this instrument may have been leftover stock, sold considerably later than it was manufactured. The U.S. Census Bureau owned the instrument and transferred it to the Smithsonian in April 1962. The National Museum of American History exhibited this instrument in For the People from 1974 to 1979.

References: Clark McCoy, "Collection of Pages from K&E Catalogs for the 4210 Family of Polar Planimeters," http://www.mccoys-kecatalogs.com/PlanimeterModels/ke4210family.htm, and "Collection of Pages from K&E Catalogs for the 4236 Family of Polar Planimeters," http://www.mccoys-kecatalogs.com/PlanimeterModels/ke4236family.htm; Catalogue of Keuffel & Esser, 38th ed. (New York, 1936), 335.

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