Coradi Polar Compensating Planimeter Sold by Keuffel & Esser (Model 4242)

Description
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 made of German silver and used with the scale on the tracer arm. The carriage for the measuring wheel is marked: No 25743. The pole arm fits inside a tube attached to a 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 34. The tube is marked: G. Coradi, Zürich Switzerland.
An oblong German silver testing rule is marked for 0", 1", 2", and 3". It is also marked: G. Coradi Zürich. A wooden case covered with black morocco leather is lined with purple velvet. A printed paper chart is pasted inside the case. The chart has columns for Scales, Position of the vernier on the tracer bar, Value of the unit of the vernier on the measuring roller, and Constant. The values in the Position and Constant columns are handwritten in the same hand that indicates the Coradi firm manufactured this planimeter with serial number 25,748 in 1917.
The label is also stamped in purple: 4242. This was the model number used by Keuffel & Esser of New York, which sold the instrument from 1901 to 1972. The price was $46.50 in 1909, $33.50 in 1915, and $55.00 in 1921; presumably, World War I affected Coradi's ability to export planimeters. By 1936, a German firm was manufacturing model 4242 for K&E's Paragon product line. Compare to 1998.0032.03. See 1991.0882.02 for a later instruction manual.
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; Catalogue of Keuffel & Esser, 33rd ed. (New York, 1909), 322; Catalogue of Keuffel & Esser, 35th ed. (New York, 1915), 315; Catalogue of Keuffel & Esser, 36th ed. (New York, 1921), 257; Catalogue of Keuffel & Esser, 38th ed. (New York, 1936), 340.
Location
Currently not on view
Object Name
planimeter
date made
1917
maker
Coradi, Gottlieb
Physical Description
german silver (overall material)
bronzed brass (overall material)
plastic (overall material)
wood (overall material)
leather (overall material)
cloth (overall material)
Measurements
case: 4 cm x 25 cm x 9.3 cm; 1 9/16 in x 9 27/32 in x 3 21/32 in
place made
Schweiz: Zürich, Zurich
ID Number
1999.0250.01
accession number
1999.0250
catalog number
1999.0250.01
maker number
25748
subject
Science & Mathematics
Mathematics
Engineering
Planimeters
See more items in
Medicine and Science: Mathematics
Planimeters
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Norton Starr
Additional Media

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