War

Military operations frequently require surveying and navigational activities. In addition to the tasks described on those pages of this exhibit, early modern military architects used protractors to create designs for fortifications. In the 20th century, protractors were utilized to position artillery pieces. The collections are especially rich in examples from the Felsenthal Instruments Company, a Chicago manufacturer of scientific instruments that was influential from the 1940s to the 1970s.

This yellow xylonite (celluloid-like plastic) rectangular protractor is contained in a paper wrapper marked: MILITARY PROTRACTOR (/) MADE BY (/) KEUFFEL & ESSER CO. (/) NEW YORK.
Description
This yellow xylonite (celluloid-like plastic) rectangular protractor is contained in a paper wrapper marked: MILITARY PROTRACTOR (/) MADE BY (/) KEUFFEL & ESSER CO. (/) NEW YORK. It is divided by degree and marked by tens from 10° to 170° and from 190° to 350°, both in the clockwise direction. An arrow points to the origin point. A small hole near the 160° mark permits a weight to be suspended so that the protractor functions as a rough clinometer, to measure angles of elevation or slope.
Four slope scales appear on the bottom edge of the instrument. These allow draftsmen to read or draw topographical contours indicating slopes in landforms of 7° and 3-1/2°; 8°, 4°, 2°, and 1°; 10°, 5°, and 2-1/2°; and 12°, 6°, 3°, and 1-1/2°, respectively. The scales for each set of slope measurements are not indicated, but they presumably are standard scales for American military engineering, such as 1:63,360 and 1:25,000.
A scale of inches divided to tenths and marked by ones from 0" to 5" appears on the interior of the protractor. Below that scale are three scales for 1", 3", and 6" to the mile, respectively. Each scale is divided in 100-yard increments. The first is marked by thousands of yards from 1,000 to 8,000; the second is marked by 500 yards from 500 to 2,500; and the third is marked by 500 yards from 500 to 1,000.
Maker's and owner's marks are near the lower edge: KEUFFEL & ESSER CO.; NEW YORK; ENG. DEPT. U.S.A. 1918. The United States Engineering Department was part of the U.S. Army Corps of Engineers in the 19th and 20th centuries. K&E began to sell this form of military protractor between 1916 and 1921, so this object may have been in use during World War I (as the markings suggest). In 1936, the protractor cost $3.50. The design of the instrument changed again between 1936 and 1943. K&E noted in the 1943 catalog that the changed form was manufactured according to the specifications of the Corps of Engineers.
See also 1977.1141.08 and 1977.1141.09.
References: Norman J. W. Thrower and Ronald U. Cooke, "Scales for Determining Slope from Topographic Maps," The Professional Geographer 20, no. 3 (1968): 181–186; Catalogue of Keuffel & Esser, 34th ed. (New York, 1913), 172; Catalogue of Keuffel & Esser, 35th ed. (New York, 1916), 172; Catalogue of Keuffel & Esser, 36th ed. (New York, 1921), 119; Catalogue of Keuffel & Esser, 38th ed. (New York, 1936), 203; Catalogue of Keuffel & Esser, 39th ed. (New York, 1943), 110. Although the illustration is correct in the 1921 catalog, the description is of the form advertised in the 1913 and 1916 catalogs. The 1936 description matches the illustration printed in 1921 and 1936, as well as this example of the military protractor.
Location
Currently not on view
date made
ca 1918
maker
Keuffel & Esser Co.
ID Number
MA.325515
accession number
257193
catalog number
325515
This clear plastic semicircular protractor is divided by ten mils and marked by hundreds from 100 to 3,100 in both the clockwise and counterclockwise directions. It is also divided by single degrees and marked by tens from 0° to 180° in both directions.
Description
This clear plastic semicircular protractor is divided by ten mils and marked by hundreds from 100 to 3,100 in both the clockwise and counterclockwise directions. It is also divided by single degrees and marked by tens from 0° to 180° in both directions. Diagonal lines extend some of the measurement markings out to the edges of the rectangle surrounding the protractor. Pinholes are at the origin point and in the upper left and right corners. The interior of the protractor has cutout stencils for a circle, triangle, square, and two oblong shapes. The middle also contains scales placed at right angles to each other. They are divided and marked by hundreds from 1,000 to 2[00]. The scales are labeled: 1:21120.
The left edge of the rectangular plastic piece is divided by tenths of an inch and marked by ones from 1 to 3. Inside the 3-inch ruler is a scale for mils divided by hundreds and marked by thousands from 5,000 to 1,000. The scale continues on the top of the rectangle, again divided by hundreds and marked by thousands from 5,000 to 1,000. The scale is labeled: 1:62500. On the right side of the top is a scale labeled: 1:20,000. It is divided and marked by hundreds from 1,000 to 2[00]. This scale also repeats on the right side of the rectangle. On the right edge of the rectangle, there is a scale divided by millimeters and marked by ones from 1 to 7. It is labeled: METRIC.
The bottom of the protractor bears a scale divided by hundreds and marked by thousands from 1,000 to 8,000. It is labeled: 1:62500. The bottom edge has a second scale, divided by hundreds and marked by five hundreds from 500 to 3,000. It is labeled: 1:21120. The name of the instrument is printed on the very bottom edge: MAP COORDINATOR AND PROTRACTOR - A-10. Donor Ben Rau dated the object to 1942.
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, 1977.1141.12, 1977.1141.18, 1977.1141.19, 1977.1141.20, 1977.1141.22, 1977.1141.23, 1977.1141.24, 1977.1141.30, and 1977.1141.39.
Location
Currently not on view
date attributed by donor
1942
maker
Felsenthal
ID Number
1977.1141.21
accession number
1977.1141
catalog number
336405
This clear plastic semicircular protractor is divided to ten mils and marked by hundreds from 100 to 3,100 and from 3,300 to 6,300. The bottom edge is divided by quarter-yards and marked by ones from 0 to 26.
Description
This clear plastic semicircular protractor is divided to ten mils and marked by hundreds from 100 to 3,100 and from 3,300 to 6,300. The bottom edge is divided by quarter-yards and marked by ones from 0 to 26. There is a vernier to the left of the divisions, and the scale is given as 1:10,000. Inside the divisions is a second ruler, divided by two yards and marked by twos from -2 to 52. The scale is given as 1:20,000.
A rectangular slot inside these rulers is divided by half-inches and marked by ones from 0 to 7. A vernier is to the left of this ruler. The upper interior of the protractor contains two scales forming a right-angled point. There are ten divisions between each unit on the scales. The outer markings are by ones from 0 to 10 and are labeled: YARDS 1:20,000. The inner markings are by twos from 2 to 20; they are labeled: YARDS 1:40,000.
The interior of the protractor also bears several marks: U.S. (/) W = (R X M)/1000; M = (W X 1000)/R. The maker's mark is toward the right side: FSN 6675-641-5711 (/) G. FELSENTHAL & SONS, INC. (/) CHICAGO 18, ILL. (/) FAE-18.
Donor Ben Rau identified the object as a machine gun protractor and dated it to 1945. It was manufactured for the U.S. Army.
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, 1977.1141.12, 1977.1141.18, 1977.1141.19, 1977.1141.20, 1977.1141.21, 1977.1141.22, 1977.1141.23, 1977.1141.30, and 1977.1141.39.
Location
Currently not on view
date attributed by donor
1945
date made
ca 1945
maker
G. Felsenthal & Sons, Inc.
ID Number
1977.1141.24
accession number
1977.1141
catalog number
336408
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.
Description
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.
Location
Currently not on view
date made
post 1948
maker
G. Felsenthal & Sons, Inc.
ID Number
1977.1141.11
accession number
1977.1141
catalog number
336395
This clear plastic rectangular protractor is divided by single degrees and marked by tens from 10° to 170° and from 190° to 350°. Pinholes near the 20° and 60° marks allow for positioning the protractor.
Description
This clear plastic rectangular protractor is divided by single degrees and marked by tens from 10° to 170° and from 190° to 350°. Pinholes near the 20° and 60° marks allow for positioning the protractor. The bottom edge is divided by tenths of an inch and marked by ones from 1" to 5". The interior of the protractor contains three scales of equal parts: 1) divided by hundreds and marked by five hundreds from 0 to 2,500 yards, for a scale of 1/20,000; 2) divided by hundreds and marked by thousands from 0 to 7,000 yards, for a scale of 1/62,500; and 3) divided by hundreds and marked by five hundreds from 0 to 2,000 meters, for a scale of 1/20,000. There are verniers to the left of the first and third scales.
Near the top of the protractor is marked: U.S. 1951. The 1951 is believed to refer to the date of the object. The maker's mark is: G. FELSENTHAL & SONS, INC. (/) PART NO. FAE-9.
This protractor is almost exactly like 1977.1141.09. See also 1977.1141.01, 1977.1141.02, 1977.1141.03, 1977.1141.05, 1977.1141.10, 1977.1141.11, 1977.1141.12, 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.
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.
Location
Currently not on view
date attributed by donor
1951
maker
G. Felsenthal & Sons, Inc.
ID Number
1977.1141.08
accession number
1977.1141
catalog number
336392
This semicircular protractor is cut out from the center of a white piece of rectangular plastic. The front is marked in black print. The protractor is divided by half-degrees and marked by tens from 0° to 180° and from 180° to 360°.
Description
This semicircular protractor is cut out from the center of a white piece of rectangular plastic. The front is marked in black print. The protractor is divided by half-degrees and marked by tens from 0° to 180° and from 180° to 360°. An arrow points to the index, or origin, point. The bottom edge of the rectangle is divided by two millimeters and marked by single centimeters from 0 to 20. The number 5731 is printed above the left side of the centimeter ruler.
The upper-left corner is divided by fifties and marked by thousands from 3000 to 1000 to 1000 to 3000. The scale is labeled: YARDS (/) RF = 1:50,000. Between the scale and protractor is printed: USMA (/) MODEL (/) 1953. The upper-right corner is divided by twenties and marked by hundreds from 5 to 1, 1000 to 1[00] to 1000, and 1 to 5. The scale is labeled: YARDS (/) RF = 1:25,000. Between the scale and protractor is printed: PROPERTY OF (/) M. T. AND G. (/) USMA.
The back of the protractor is marked in red print. The protractor is divided into units of twenty mils and marked by two hundreds from 0 to 3200 and from 3200 to 6400. An arrow points to the index point. The bottom edge of the rectangle is divided by tenths of an inch and marked by ones from 0" to 8".
The upper-left corner is divided by fifties and marked by thousands from 3,000 to 1,000 to 1,000 to 3,000. The scale is labeled: METERS (/) RF = 1:50,000. Between the scale and protractor is printed: USMA (/) MODEL (/) 1953. The upper-right corner is divided by twenties and marked by hundreds from 5 to 1, 1,000 to 1[00] to 1,000, and 1 to 5. The scale is labeled: METERS (/) RF = 1:25,000. Between the scale and protractor is printed: PROPERTY OF (/) M. T. AND G. (/) USMA.
Felsenthal Instruments Company manufactured this protractor for the United States Military Academy at West Point, N.Y. Donor Ben Rau, who worked for Felsenthal, dated the object to 1954.
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, 1977.1141.12, 1977.1141.18, 1977.1141.19, 1977.1141.20, 1977.1141.21, 1977.1141.22, 1977.1141.23, 1977.1141.24, and 1977.1141.39.
Location
Currently not on view
date attributed by donor
1954
maker
Felsenthal
ID Number
1977.1141.30
accession number
1977.1141
catalog number
336414
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.
Description
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 8,000 yards. A small vernier appears to the left of the scale, and the scale is labeled: 1/20,000.
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-. The letters U.S. are printed above the origin point. Donor Ben Rau, who worked for Felsenthal, dated the object to 1942. The form of the maker's name indicates it was probably manufactured for the U.S. Army in the 1950s.
This protractor is very similar to 1977.1141.11, although the scale for plotting the distance of fired artillery is in yards rather than in meters.
See also 1977.1141.01, 1977.1141.02, 1977.1141.03, 1977.1141.05, 1977.1141.08, 1977.1141.09, 1977.1141.10, 1977.1141.12, 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.
Location
Currently not on view
date attributed by donor
1942
date made
1950s
maker
G. Felsenthal & Sons, Inc.
ID Number
1977.1141.18
accession number
1977.1141
catalog number
336402
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.
Description
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.
Location
Currently not on view
date attributed by donor
1945
date made
1950s
maker
G. Felsenthal & Sons, Inc.
ID Number
1977.1141.19
accession number
1977.1141
catalog number
336403
This clear plastic rectangular protractor is divided by single degrees and marked by tens from 10° to 170° and from 190° to 350°. Pinholes near the 20° and 60° marks allow for positioning the protractor.
Description
This clear plastic rectangular protractor is divided by single degrees and marked by tens from 10° to 170° and from 190° to 350°. Pinholes near the 20° and 60° marks allow for positioning the protractor. The bottom edge is divided by tenths of an inch and marked by ones from 1" to 5". The interior of the protractor contains three scales of equal parts: 1) divided by hundreds and marked by five hundreds from 0 to 2,500 yards, for a scale of 1/20,000; 2) divided by hundreds and marked by thousands from 0 to 7,000 yards, for a scale of 1/62,500; and 3) divided by hundreds and marked by five hundreds from 0 to 2,000 meters, for a scale of 1/20,000. There are verniers to the left of the first and third scales.
Near the top of the protractor is marked: U.S. 1957. The 1957 is believed to refer to the date of the object. The maker's mark is: G. FELSENTHAL & SONS, INC. (/) PART NO. FAE-9A.
This protractor is almost exactly like 1977.1141.08. See also 1977.1141.01, 1977.1141.02, 1977.1141.03, 1977.1141.05, 1977.1141.10, 1977.1141.11, 1977.1141.12, 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.
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.
Location
Currently not on view
date attributed by donor
1957
maker
G. Felsenthal & Sons, Inc.
ID Number
1977.1141.09
accession number
1977.1141
catalog number
336393
This clear plastic semicircular protractor is divided by twenties and marked by two hundreds from 0 to 3,200 and from 3,200 to 6,400. A pinhole is at the origin point. The interior is labeled: ANGULAR MILS; 8016738. This protractor was item no. FAO-44.
Description
This clear plastic semicircular protractor is divided by twenties and marked by two hundreds from 0 to 3,200 and from 3,200 to 6,400. A pinhole is at the origin point. The interior is labeled: ANGULAR MILS; 8016738. This protractor was item no. FAO-44. Felsenthal Instruments Company manufactured it for the U.S. Army about 1958.
The Felsenthal Instruments Company was the leading supplier of mathematical instruments to the U.S. Army Air Force and the U.S. Navy Bureau of Aeronautics, particularly during World War II (when the firm was known as G. Felsenthal & Sons). After the company ceased operations in approximately 1976, it provided a large sample of its products to the Smithsonian.
See also 1977.1141.01, 1977.1141.02, 1977.1141.03, 1977.1141.05, 1977.1141.08, 1977.1141.09, 1977.1141.11, 1977.1141.12, 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.
Location
Currently not on view
date made
ca 1958
maker
Felsenthal
ID Number
1977.1141.10
accession number
1977.1141
catalog number
336394
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.
Description
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 3,000 to 0. A vernier appears to the right of the scale. The scale is labeled: 1/25,000 METERS. Superimposed on the scale is a second scale, divided by two hundreds and marked (in red) by two thousands from 0 to 6,000. A vernier appears to the left of that scale, which is labeled (in red): 1/50,000 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 (/) FELSENTHAL INSTRUMENTS CO. (/) CHICAGO (/) FAE-23A. The letters U.S. are printed above the origin point. Donor Ben Rau, who worked for Felsenthal, dated the object to 1951. The form of the signature indicates the protractor was probably manufactured for the U.S. Army in the 1960s.
This protractor is very similar to 1977.1141.11. 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.
Reference: Copyright Office, Library of Congress, "Books and Pamphlets," Catalog of Copyright Entries, 3rd ser., 16, part 1, no. 2 (1964): 1392.
Location
Currently not on view
date attributed by donor
1951
date made
1960s
maker
Felsenthal Instrument Co.
ID Number
1977.1141.12
accession number
1977.1141
catalog number
336396
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.
Description
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 of meters from 6,000 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 12,000. A vernier appears to the left of that scale, which is labeled (in red): 1/50,000.
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: FSN 6675-556-0118 (/) PROTRACTOR, 16 INCH (/) FELSENTHAL INSTRUMENTS CO. (/) CHICAGO (/) FAE-22A. The letters U.S. are printed above the origin point. Donor Ben Rau, who worked for Felsenthal, dated the object to 1950, but the form of the signature indicates the protractor was probably manufactured for the U.S. Army in the 1960s.
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, 1977.1141.11, 1977.1141.18, 1977.1141.19, 1977.1141.21, 1977.1141.22, 1977.1141.23, 1977.1141.24, 1977.1141.30, and 1977.1141.39.
Reference: Copyright Office, Library of Congress, "Books and Pamphlets," Catalog of Copyright Entries, 3rd ser., 16, part 1, no. 2 (1964): 1392.
Location
Currently not on view
date attributed by donor
1950
date made
1960s
maker
Felsenthal Instrument Co.
ID Number
1977.1141.20
accession number
1977.1141
catalog number
336404
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.
Description
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 7,000. 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 semicircular opening with a groove parallel to the origin point. Below the opening is a maker's mark: 12 INCH (/) G. FELSENTHAL & SONS, INC. (/) FAE-21. Donor Ben Rau dated the object to 1945, but the form of the signature indicates the protractor was probably manufactured for the U.S. Army in the 1950s.
This protractor is very similar to 1977.1141.11. See also 1977.1141.01, 1977.1141.02, 1977.1141.03, 1977.1141.05, 1977.1141.08, 1977.1141.09, 1977.1141.10, 1977.1141.12, 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.
Location
Currently not on view
date attributed by donor
1945
date made
1960s
maker
G. Felsenthal & Sons, Inc.
ID Number
1977.1141.22
accession number
1977.1141
catalog number
336406
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.
Description
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. A second hole with diameter 3mm appears just above the origin point. The bottom edge of the protractor is divided by hundreds and marked by thousands from 5,000 to 0. A vernier appears to the right of the scale. The scale is labeled: 1/25,000 METERS. Superimposed on the scale is a second scale, divided by two hundreds and marked (in red) by two thousands from 0 to 10,000. A vernier appears to the left of that scale, which is labeled (in red): 1/50,000 METERS. The red markings are significantly faded.
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: 12 INCH (/) FELSENTHAL INSTRUMENTS CO. (/) CHICAGO (/) FAE-21A. The letters U.S. are printed above the origin point. Donor Ben Rau dated the object to 1950, but the form of the signature indicates the protractor was probably manufactured for the U.S. Army in the 1960s.
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, 1977.1141.11, 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.
Reference: Copyright Office, Library of Congress, "Books and Pamphlets," Catalog of Copyright Entries, 3rd ser., 16, part 1, no. 2 (1964): 1392.
Location
Currently not on view
date attributed by donor
1950
date made
1960s
maker
Felsenthal Instrument Co.
ID Number
1977.1141.23
accession number
1977.1141
catalog number
336407
This clear plastic sixth-circle protractor is graduated into 10 groups of 20 divisions, each labeled with the number 50. The unit of angular measure is mils, which was utilized in artillery applications. There are 6,400 mils in a circle (i.e., 1 mil = 0.05625 degrees).
Description
This clear plastic sixth-circle protractor is graduated into 10 groups of 20 divisions, each labeled with the number 50. The unit of angular measure is mils, which was utilized in artillery applications. There are 6,400 mils in a circle (i.e., 1 mil = 0.05625 degrees). The arc on this instrument is 1,000 mils, or 56.25 degrees, in length.
An arm extends from the left side of the protractor. The arm is divided to half-units and marked by five (scaled) meters from 160 to 10. Two holes with diameters of 5mm are next to the 145–140 and 30–25 marks. The vertex of the protractor bears a small notch.
The interior of the protractor is marked: PROTRACTOR, RANGE DEFLECTION (/) SCALE 1:25,000 (/) RANGE 16,000 (/) METERS. Stamped inside a box is the text: THIS TRAINING AID WILL BE RETURNED (/) TO THE FIELD ARTILLERY SCHOOL (/) UPON COMPLETION OF THE SUB-COURSE (/) WITH WHICH ISSUED. Donor Ben Rau dated the instrument to 1965.
See also 1977.1141.01, 1977.1141.02, 1977.1141.05, 1977.1141.08, 1977.1141.09, 1977.1141.10, 1977.1141.11, 1977.1141.12, 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.
Location
Currently not on view
date made
1965
maker
Felsenthal Instrument Co.
ID Number
1977.1141.03
accession number
1977.1141
catalog number
336387
This clear plastic circular protractor is divided by tenths and marked by ones from 1 to 63. In the 48-64 quadrant, it is also marked in red print by ones from 32 to 17. The scale is labeled: AZIMUTH-MILS (100). The interior of the 16–32 quadrant is cut out.
Description
This clear plastic circular protractor is divided by tenths and marked by ones from 1 to 63. In the 48-64 quadrant, it is also marked in red print by ones from 32 to 17. The scale is labeled: AZIMUTH-MILS (100). The interior of the 16–32 quadrant is cut out. Each of the straight sides bears a scale divided by fifties and marked by thousands from 0 to 4,000. The scales are labeled: METERS RF 1: 50,000.
An arm extending from the 0-16 quadrant is divided by tenths and marked by ones from 1 to 17. The scale is labeled: RANGE METERS (1000). The interior of the 32–48 quadrant bears a maker's mark: FELSENTHAL INSTRUMENTS CO. (/) MFR'S CODE 22040 (/) MFR'S PART NO. FAE-28. The protractor was used to predict the direction and distance of artillery rounds. Donor Ben Rau wrote "Massengale" (which may refer to a particular U.S. Army officer) on the tag he provided with this instrument, and he dated the object to 1966.
See also 1977.1141.01, 1977.1141.02, 1977.1141.03, 1977.1141.08, 1977.1141.09, 1977.1141.10, 1977.1141.11, 1977.1141.12, 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.
Location
Currently not on view
date attributed by donor
1966
maker
Felsenthal Instrument Co.
ID Number
1977.1141.05
accession number
1977.1141
catalog number
336389
While many protractors simply measure angles in degrees, others have been adapted for more specialized contexts. For instance, they may be combined with other drawing instruments, such as rulers or templates for flow chart components.
Description
While many protractors simply measure angles in degrees, others have been adapted for more specialized contexts. For instance, they may be combined with other drawing instruments, such as rulers or templates for flow chart components. Or, they may make measurements in other scales for angles, such as radians. Before computerized and satellite navigation equipment was in wide use, protractors were employed in military applications, including positioning artillery.
Thus, this clear plastic protractor, which is in the shape of a sixth-circle, permitted the user to plot the distance traveled by a projectile from the time that elapsed before the sound of the projectile was heard. The outer edge of the protractor's arc is divided by hundredths and marked by tenths from +3.4 to +0.1 (in black print) and from -0.1 to -3.4 (in red print). The scale is labeled: TIME INTERVAL, SECONDS and MIDPOINTS FOR 4-SECOND SUB-BASE, 1/25000.
A scale marked DEGREES is further inside the arc. It is divided by minutes and marked by fives from 55° to 0°. Finally, a scale for MILS is divided by tens and marked by hundreds from 1000 to 100. 1000 mils is equivalent to 56.25°. A scale for THOUSANDS OF YARDS 1/25000 is along the right edge of the protractor. It is divided by five-hundredths and marked by ones from 14 to 1.
The maker's mark is near the vertex: 4 SOUND SECONDS (/) FELSENTHAL INSTRUMENTS CO. (/) MFR'S PART NO. FAE-19A (/) MFR'S CODE 22040.
The Felsenthal Instruments Company was the leading supplier of mathematical instruments to the U.S. Army Air Force and the U.S. Navy Bureau of Aeronautics, particularly during World War II (when the firm was known as G. Felsenthal & Sons). After the company ceased operations in approximately 1976, it provided a large sample of its products to the Smithsonian.
See also 1977.1141.02, 1977.1141.03, 1977.1141.05, 1977.1141.08, 1977.1141.09, 1977.1141.10, 1977.1141.11, 1977.1141.12, 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.
Reference: Deborah J. Warner, “Browse by Maker: Felsenthal,” National Museum of American History Physical Sciences Collection: Navigation, http://amhistory.si.edu/navigation/maker.cfm?makerid=173.
Location
Currently not on view
date attributed by donor
1950
date made
1970s
maker
Felsenthal Instrument Co.
ID Number
1977.1141.01
accession number
1977.1141
catalog number
336385
This clear plastic sixth-circle protractor is divided along its outer edge by hundredths and marked by tenths from +1.7 to +0.1 (in black print) and from -0.1 to -3.4 (in red print). The scale is labeled: TIME INTERVAL, SECONDS.
Description
This clear plastic sixth-circle protractor is divided along its outer edge by hundredths and marked by tenths from +1.7 to +0.1 (in black print) and from -0.1 to -3.4 (in red print). The scale is labeled: TIME INTERVAL, SECONDS. The left edge of the protractor is divided by tens and marked by hundreds from 2000 to 600. The scale is labeled: LENGTH OF SUB-BASE, YARDS. The right edge of the protractor is divided by halves and marked by ones from 14 to 1. The scale is labeled: THOUSANDS OF YARDS (/) 1/25000.
The interior of the protractor is filled with diagonal lines. Three scales are among the diagonal lines, each numbered by tenths in black and in red print. The outermost is numbered from 3.9 to 0.1; the middle scale is numbered from 3.0 to 0.1; and the innermost is numbered from 2.2 to 0.1.
The maker's mark is near the vertex, which is notched: 2 SOUND SECONDS (/) TEMPLATE, 1/25000 (/) FELSENTHAL INSTRUMENTS CO. (/) MFR'S PART NO. FAE-19B (/) MFR'S CODE 22040. There is a large plus sign to the right of the maker's mark.
The Chicago firm that manufactured this protractor was known as Felsenthal Instrument Co. in the 1960s and 1970s. Ben Wharton Rau (1904–1995) and his wife, Margery Felsenthal Rau (1916–2010), arranged the donation of this object and many other instruments to the Smithsonian. Margery's father, Irving (1887–1956), was one of the "Sons" of G. Felsenthal & Sons, as the company was known in the 1940s and 1950s. Margery's grandfather, Gabe Felsenthal, founded the firm in 1899.
Ben Rau worked for the Felsenthals. His duties included touring military facilities with a large display of the company's products. He catalogued hundreds of instruments when the company went out of business in 1976. He dated this protractor and 1977.1141.01 to 1950. While the form was indeed probably older, the maker's name on the instrument indicates it was manufactured in the 1960s or 1970s. Rau also held patents on a collapsible film reel, a proportional divider, and a belt buckle assembly.
See also 1977.1141.01, 1977.1141.03, 1977.1141.05, 1977.1141.08, 1977.1141.09, 1977.1141.10, 1977.1141.11, 1977.1141.12, 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.
References: Deborah J. Warner, “Browse by Maker: Felsenthal,” National Museum of American History Physical Sciences Collection: Navigation, http://amhistory.si.edu/navigation/maker.cfm?makerid=173; "Irving G. Felsenthal," Chicago Tribune, February 26, 1956, http://www.susaneking.com/genealogy/showsource.php?sourceID=S01752&tree=GreenebaumSam; Copyright Office, Library of Congress, "Books and Pamphlets," Catalog of Copyright Entries, 3rd ser., 16, part 1, no. 2 (1964): 1392; Ben W. Rau, "Collapsible Film Reel" (U.S. Patent 3,447,759 issued June 3, 1969), "Proportional Divider" (U.S. Patent D214,399 issued June 10, 1969), "Belt Buckle Assembly" (U.S. Patent 3,475,797 issued November 4, 1969).
Location
Currently not on view
date attributed by donor
1950
date made
1970s
maker
Felsenthal Instrument Co.
ID Number
1977.1141.02
accession number
1977.1141
catalog number
336386

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.