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.
"Protractors - War" showing 1 items.
- 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.
- Currently not on view
- date made
- ca 1918
- Keuffel & Esser Co.
- ID Number
- accession number
- catalog number
- Data Source
- National Museum of American History, Kenneth E. Behring Center