Felsenthal FAE-23 Artillery Protractor

This clear plastic semicircular protractor is divided by tens and marked by hundreds from 100 to 3,100 mils and from 3,300 to 6,300 mils. Mils are units used in artillery and other military applications; 1,000 mils is equivalent to 56.25°. A pinhole is at the origin point. The bottom edge of the protractor is divided by hundreds and marked by five hundreds from 0 to 4,500. A small vernier appears to the left of the scale, and the scale is labeled: 1/25,000 METERS.
The interior of the protractor has a relatively small semicircular opening with a groove parallel to the origin point. Below the opening is a maker's mark: 8 INCH (/) G. FELSENTHAL & SONS, INC. (/) FAE-23. Donor Ben Rau, who worked for Felsenthal, dated the object to 1948. The form of the signature indicates it was probably manufactured for the U.S. Army in the 1950s.
This protractor is very similar to 1977.1141.12. See also 1977.1141.01, 1977.1141.02, 1977.1141.03, 1977.1141.05, 1977.1141.08, 1977.1141.09, 1977.1141.10, 1977.1141.18, 1977.1141.19, 1977.1141.20, 1977.1141.21, 1977.1141.22, 1977.1141.23, 1977.1141.24, 1977.1141.30, and 1977.1141.39.
Currently not on view
Object Name
date made
post 1948
G. Felsenthal & Sons, Inc.
Physical Description
plastic (overall material)
overall: .2 cm x 20.3 cm x 11.2 cm; 3/32 in x 8 in x 4 13/32 in
Place Made
United States: Illinois, Chicago
ID Number
accession number
catalog number
Science & Mathematics
See more items in
Medicine and Science: Mathematics
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Ben Wharton Rau and Margery Felsenthal Rau

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