Kern Semicircular Protractor


This German silver semicircular protractor bears the distinctive italic engraved numbers of Kern & Co. of Aarau, Switzerland. It is graduated by quarter-degrees and marked by tens from 10 to 170 both from left to right and from right to left. There are no other marks. The lower edge of the protractor is beveled, with a groove at the origin point.

Ruth E. Crownfield, the widow of Albert C. Crownfield Jr., a mechanical engineer from Mohawk, N.Y., donated this protractor in 1978. The instrument is quite tarnished and scratched, suggesting Crownfield used it frequently. Similar protractors cost $3.50 in the first decade of the 20th century and $4.50 in 1936.

See also ID numbers MA.247966 and 1977.0460.02.

References: “(Product No.) 1248,” Catalogue of Keuffel & Esser Co. (New York, 1909), 172; Catalogue of Keuffel & Esser Co. (New York, 1936), 201.

Date Made: early 20th century

Maker: Kern & Co.

Location: Currently not on view

Place Made: Switzerland: Aargau, Aarau

Subject: MathematicsProtractor


See more items in: Medicine and Science: Mathematics, Science & Mathematics, Protractors


Exhibition Location:

Credit Line: Gift of Ruth E. Crownfield

Data Source: National Museum of American History

Id Number: 1978.2291.01Accession Number: 1978.2291Catalog Number: 336875

Object Name: protractor

Physical Description: german silver (overall material)Measurements: overall: .2 cm x 15.6 cm x 7.9 cm; 3/32 in x 6 5/32 in x 3 1/8 in


Record Id: nmah_904460

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.