The name of the instrument is printed on the very bottom edge: MAP COORDINATOR AND PROTRACTOR - A-10. The bottom edge has a second scale, divided by hundreds and marked by five hundreds from 500 to 3,000. The bottom of the protractor bears a scale divided by hundreds and marked by thousands from 1,000 to 8,000. On the right edge of the rectangle, there is a scale divided by millimeters and marked by ones from 1 to 7. This scale also repeats on the right side of the rectangle. It is divided and marked by hundreds from 1,000 to 2. On the right side of the top is a scale labeled: 1:20,000. The scale continues on the top of the rectangle, again divided by hundreds and marked by thousands from 5,000 to 1,000. Inside the 3-inch ruler is a scale for mils divided by hundreds and marked by thousands from 5,000 to 1,000. The left edge of the rectangular plastic piece is divided by tenths of an inch and marked by ones from 1 to 3. They are divided and marked by hundreds from 1,000 to 2. The middle also contains scales placed at right angles to each other. The interior of the protractor has cutout stencils for a circle, triangle, square, and two oblong shapes. Pinholes are at the origin point and in the upper left and right corners. Diagonal lines extend some of the measurement markings out to the edges of the rectangle surrounding the protractor. It is also divided by single degrees and marked by tens from 0° to 180° in both directions. 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. The 1936 description matches the illustration printed in 19, as well as this example of the military protractor. Although the illustration is correct in the 1921 catalog, the description is of the form advertised in the 19 catalogs. (New York, 1936), 203 Catalogue of Keuffel & Esser, 39th ed. (New York, 1921), 119 Catalogue of Keuffel & Esser, 38th ed. (New York, 1916), 172 Catalogue of Keuffel & Esser, 36th ed. (New York, 1913), 172 Catalogue of Keuffel & Esser, 35th ed. Cooke, "Scales for Determining Slope from Topographic Maps," The Professional Geographer 20, no. K&E noted in the 1943 catalog that the changed form was manufactured according to the specifications of the Corps of Engineers. The design of the instrument changed again between 19. K&E began to sell this form of military protractor between 19, so this object may have been in use during World War I (as the markings suggest). Army Corps of Engineers in the 19th and 20th centuries. The United States Engineering Department was part of the U.S. Maker's and owner's marks are near the lower edge: KEUFFEL & ESSER CO. 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. Each scale is divided in 100-yard increments. Below that scale are three scales for 1", 3", and 6" to the mile, 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.Ī scale of inches divided to tenths and marked by ones from 0" to 5" appears on the interior of the protractor. 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. 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.įour slope scales appear on the bottom edge of the instrument. It is divided by degree and marked by tens from 10° to 170° and from 190° to 350°, both in the clockwise direction. This yellow xylonite (celluloid-like plastic) rectangular protractor is contained in a paper wrapper marked: MILITARY PROTRACTOR (/) MADE BY (/) KEUFFEL & ESSER CO.
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