Wichmann 1192 Compensating Polar Planimeter

Description
This German silver and bronzed brass instrument has an 8" fixed-length pole arm with attached cylindrical weight. The arm is marked in script: Wichmann. An adjustable 9-1/2" tracer arm has a support for the tracer point and is evenly divided by tenths numbered from 5 to 36. The interval for each whole number is 5 mm long. A carriage on the tracer arm has a vernier for the scale on the tracer arm and white plastic measuring wheel, vernier, and registering dial. The carriage is marked with a serial number: 17728. A rectangular German silver test plate is marked for 2, 4, and 6 cm.
A wooden case is covered with black leather and lined with green felt. The top of the case is marked: 1192 Gebr. Wichmann. A loose screw is inside the case. Gebrüder Wichmann (Wichmann Brothers) has sold scientific instruments and office equipment in Berlin since 1873. According to Joachim Fischer, planimeters sold by Wichmann before the 1920s were made by Coradi. Around that time, Wichmann purchased the company founded by Robert Reiss, which thenceforth supplied many of the planimeters sold by Wichmann. It is likely that this example is a Coradi instrument. For a slide rule sold by Wichmann, see MA*293320.2820.
References: Joachim Fischer to Peggy A. Kidwell, October 19, 1992, Mathematics Collection files, National Museum of American History; A. Brachner, "German Nineteenth-Century Scientific Instrument Makers," in Nineteenth-Century Scientific Instruments and Their Makers, ed. P. R. de Clercq (Amsterdam: Rodopi B. V., 1985), 152; G. Coradi, Catalog d'orientation, No. 37 (Zurich, n.d.), 3, in accession file 2011.0043.
Location
Currently not on view
Object Name
planimeter
date made
ca 1930
maker
Gebr. Wichmann
Physical Description
german silver (overall material)
brass (overall material)
plastic (overall material)
wood (overall material)
leather (overall material)
fabric (overall material)
Measurements
overall: 26 cm x 9.6 cm x 4.5 cm; 10 1/4 in x 3 25/32 in x 1 25/32 in
place made
Germany
ID Number
1986.0316.06
catalog number
1986.0316.06
accession number
1986.0316
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 Ursula N. Forbes
Additional Media

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