Slide RulesIndex by Purpose
While many slide rules were made as general calculating instruments, for multiplying numbers and solving equations with squares, cubes, trigonometric functions, and logarithms, many others were made to ease the calculations associated with a specific task. Click on items in the list below to see rules in the collection with an identifiable specialized purpose. For comparison, a few illustrative examples of all-purpose slide rules are shown under the link to General Calculation.
"Slide Rules - Index by Purpose" showing 241 items.
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- This circular slide chart consists of two plastic discs of equal size held together at the center by a metal rivet. The bottom disc is white, with a green logarithmic scale around the edge that runs from 8 to 20. The top disc is clear around the edge (making it possible to see the lower scale) and gray in the center. Around the gray region is a circular logarithmic scale that also runs from 8 to 20. According to the instructions on the object, one rotates the upper disc to set the pumped weight on the inner scale opposite the green weight on the outer scale. The “Percent Pump” can then be read through a window in the upper disc. It ranges from 0 to 20.
- The green weight of a processed food is the weight before processing, while the pumped weight is weight after processing. This device allows one to find the percentage by which the weight of a product has increased as a result of processing. USDA regulations require that, if the pumped weight of a meat product exceeds the green weight, the substances added be indicated.
- The top disc is marked: PUMPING (/) PERCENTAGE (/) CALCULATOR. It is also marked: CURAFOS. It is also marked : CALGON CO. (/) PITTSBURGH 30, PENNSYLVANIA. On the bottom disc is marked: Copyright 1959 Hagan Chemicals & Controls, Inc. It is also marked: MANUFACTURED BY (/) GRAPHIC CALCULATOR CO., CHICAGO 5, ILL.
- Graphic Calculator Company was a slide rule manufacturing and design company founded in Chicago in 1940 by Capron R. Gulbransen and apparently still in business at the time of his death in 1969. Curafos was the trademark for a chemical compound used in the treatment of meat and meat products to improve their color and moisture retention. The chemical was introduced by CALGON Co. in 1953, with the trademark granted in 1955. CALGON was a subsidiary of Hagan Corporation until 1956, when Hagan Corporation was renamed Hagan Chemicals and Controls. In 1963, Hagan Chemicals and Controls sold its Controls Division to Westinghouse, and the remaining firm became Calgon Corporation. These changes in corporate name are consistent with the copyright date of 1959 on the instrument.
- References: Processing Inspectors’ Calculations Handbook, United States Department of Agriculture Food Safety Inspection Service, rev. ed. (Washington, DC, 1995), 83, http://www.fsis.usda.gov/OPPDE/rdad/FSISDirectives/7620-3.pdf; Obituaries, Chicago Tribune, August 11, 1969, p. A6.
- Currently not on view
- date made
- Graphic Calculator Co.
- ID Number
- nonaccession number
- catalog number
- Data Source
- National Museum of American History, Kenneth E. Behring Center