Felsenthal FAE-8 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 thousands from 7,000 to 0. A vernier appears to the right of the scale. The scale is labeled: 1/25,000. Superimposed on the scale is a second scale, divided by two hundreds and marked (in red) by two thousands from 0 to 14,000. A vernier appears to the left of that scale, which is labeled (in red): 1/50,000 YARDS.
The interior of the protractor has a semicircular opening with a groove parallel to the origin point. Below the opening is a maker's mark: 16 INCH (/) G. FELSENTHAL & SONS, INC. (/) -CHICAGO- (/) FAE-8. The letters U.S. are printed above the origin point. Donor Ben Rau dated the object to 1945, but the form of the signature indicates the protractor may not have been manufactured for the U.S. Army until the 1950s.
This protractor is very similar to 1977.1141.12, although the scale for plotting the distance of fired artillery is in yards rather than in meters. The red ink on this instrument is particularly vibrant. See also 1977.1141.01, 1977.1141.02, 1977.1141.03, 1977.1141.05, 1977.1141.08, 1977.1141.09, 1977.1141.10, 1977.1141.11, 1977.1141.18, 1977.1141.20, 1977.1141.21, 1977.1141.22, 1977.1141.23, 1977.1141.24, 1977.1141.30, and 1977.1141.39.
Reference: Deborah J. Warner, “Browse by Maker: Felsenthal,” National Museum of American History Physical Sciences Collection: Navigation, http://americanhistory.si.edu/collections/navigation/maker.cfm?makerid=173.
Currently not on view
Object Name
date attributed by donor
date made
G. Felsenthal & Sons, Inc.
Physical Description
plastic (overall material)
overall: .2 cm x 40.3 cm x 21.7 cm; 3/32 in x 15 7/8 in x 8 17/32 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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