Scale RulesRules for Drafting
To create technical drawings such as those presented by the traveling exhibition, Doodles, Drafts, and Designs, draftsmen needed drawing instruments with specialized scales. Most often, their goal was to represent a real-life place or object at a reduced proportion. Thus, drafting rules like those shown on this page were typically marked for making drawings at scales such as 1/8-inch to 1 foot. Sometimes, instead of marking the increments throughout a scale, only the first and last segments of a scale were subdivided to the desired proportion. These were called open divided or architect's scales.
Rules for drafting sometimes had plotting scales. These were divided into equal increments of a useful length, such as 1/2-inch, that could be directly transferred to a drawing such as a surveying map. At both ends, plotting scales typically had diagonal scales. These allowed users to reasonably accurately estimate the decimal division between two markings on a scale. Instruments in this category also may have a line of chords. This projected the distance between the end of a quarter-circle arc and each of the degrees along the arc onto a straight line. Finally, the scales for measuring lengths on rules for drafting were often divided into multiples of 1/10-inch, called chain scales, which were advantageous for activities such as construction or machine work.
"Scale Rules - Rules for Drafting" showing 1 items.
- This 6" boxwood pocket ruler has a white celluloid coating along both long edges on both sides. On one side, the top edge has scales for 1-1/2" and 3" to the foot. The bottom edge has scales for 3/8" and 3/4" to the foot. Between these scales is a scale divided to centimeters, numbered from left to right by twos from 2 to 12, and numbered from right to left by ones from 1 to 6. The middle of this side is marked: U.S. ST'D. It is also marked: P. M. LARSEN.
- The top edge of the other side has scales for 1/2" and 1" to the foot. Between these scales is a scale divided to 1/2", numbered from left to right by twos from 2 to 8, and numbered from right to left by ones from 1 to 4. The bottom edge has scales for 1/8" and 1/4" to the foot. Between these scales is a scale divided to 1/8", numbered from left to right by fours from 4 to 44, and numbered from right to left by twos from 0 to 22. The middle of this side is marked: P. M. LARSEN.
- Draftsmen used these scales to make construction drawings. Keuffel & Esser sold a similar scale as model 1399P from 1913 to at least 1936. The price in 1913 was $1.35. This object was probably made about the same time as 1981.0933.14, in the 1910s.
- William J. Ellenberger (1908–2008) donated this object, which he presumably acquired secondhand from P. M. Larsen. Ellenberger studied electrical and mechanical engineering at The George Washington University between 1925 and 1934. He then worked for the Potomac Electric Power Company and the National Bureau of Standards. During World War II, he served in the U.S. Army Signal Corps. He was a civilian construction management engineer for the army from 1954 to 1968, when he became a private consultant.
- References: Catalogue of Keuffel & Esser Co., 34th ed. (New York, 1913), 178; Catalogue of Keuffel & Esser Co., 36th ed. (New York, 1921), 123; Catalogue of Keuffel & Esser Co., 38th ed. (New York, 1936), 212; "The GW Engineering Hall of Fame 2006 Inductees," http://www.weas.gwu.edu/ifaf/hall_of_fame_inductees_2006.php.
- Currently not on view
- date made
- ca 1915
- ID Number
- accession number
- catalog number
- Data Source
- National Museum of American History, Kenneth E. Behring Center