Keuffel & Esser 4242 Polar Compensating Planimeter

The adjustable tracer arm on this German silver and bronzed brass instrument is evenly divided to tenths of a unit, with each unit equal to 5mm, and numbered from 5 to 36. The measuring wheel, vernier, and registering dial are white plastic. A second vernier is severely tarnished, made of German silver, and used with the scale on the tracer arm. The carriage for the measuring wheel is marked with a serial number: 12960. The pole arm fits inside a square tube and cylindrical weight, allowing the arm's length to be adjusted. The pole arm has a scale like the scale on the tracer arm, but it is numbered from 30 to 35.

Unlike earlier versions of the instrument, such as 1999.0250.01, the tube has an opening with a vernier. The tube is marked on top: K+E KUEFFEL & ESSER CO. (/) PARAGON. It is also marked: MADE IN (/) GERMANY. The side of the tube is marked: 12960. An oblong German silver testing rule is marked for 5 sq. in., 10 sq. in., and 100 sq. cm. A wooden case covered with black leather is lined with chamois leather. The top of the case is marked: K+E. The serial number and tracer and pole arm settings are written in ink on a K&E label pasted inside the lid. The number 20,475 is written in pencil on the label. See 1991.0882.02 for instructions.

K&E imported planimeters from the Coradi firm in Zurich to sell as model 4242 from 1901 to about 1936. When K&E began to offer model 4242 as part of its Paragon line, it changed suppliers to a German company. The instrument was not available during World War II. K&E introduced its K+E logo in 1949, and it added a tracer lens between 1958 and 1960. The price was $98.00 in 1949 and $90.00 in 1956. According to the donor, this instrument was used by her husband, the electrical engineer Robert H. Wieler (1923–1993).

The instrument was received at the Smithsonian in 1998.

References: Clark McCoy, "Collection of Pages from K&E Catalogs for the 4242 Family of Polar Planimeters," http://www.mccoys-kecatalogs.com/PlanimeterModels/ke4242family.htm; accession file.

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