Scale RulesCalculating Rules
In addition to length measurements, scale rules could be marked with aids for calculation. Perhaps the most notable rule of this type was Gunter's scale, which was similar to a sector or a slide rule. Gunter's scales are named after Edmund Gunter, a 17th-century English mathematical practitioner who figured out how to put a table of logarithms on a rule so that logarithmic calculations could be made with the aid of dividers. These instruments were especially handy for mathematicians and navigators.
The mathematics collections contain several other objects, ranging from the 18th to the 20th centuries, that were used to simplify computations for tasks including designing sundials, keeping track of calendar dates, and plotting data for aeronautical engineering. A few of these rules were designed specifically for positioning artillery.
"Scale Rules - Calculating Rules" showing 1 items.
- This 7" white plastic rule has scales for statute miles and surface speed in miles per hour along both long edges, at proportions of 1:1,000,000 and 1:500,000. The interior of the rule is marked: AERONAUTICAL (/) INFORMATION (/) DATA SYSTEMS (/) HALPIN COAIRDINATOR (/) T.M. REG. U.S. PAT. OFF. (/) COPYRIGHT 1947 BY HALPIN COAIRDINATOR COMPANY WORLD RIGHTS RESERVED. A blue plastic propeller is riveted next to the companies' names. The rule is also marked in English and Spanish: READ SURFACE SPEED BY (/) MEASURING DISTANCE (/) COVERED IN 10 MINUTES (/) ELAPSED TIME (/) SEE REVERSE SIDE FOR SPEED CONVERSIONS.
- The back of the rule gives conversion factors for statute miles, nautical miles, and kilometers. This side also has conversion scales for feet and meters; liters, U.S. gallons, and imperial gallons; and kilometers, statute miles, and nautical miles. The center of the rule is marked: FOR CONVERSIONS ABOVE 100 ADD LIKE NUMBER OF CIPHERS TO EACH SCALE.
- The Halpin Coairdinator Company was founded in Florida in 1943. The firm and Aeronautical Information Data Systems jointly copyrighted a chart in 1947, but that object (38 X 27 cm) was much larger than this object. Halpin Coairdinator later copyrighted devices in Brazil as well as in the United States. The National Air & Space Museum owns a flight-route plan and a dead reckoning computer made by the company. A Thomas E. Halpin was director of training at Embry-Riddle School of Aviation in Miami, Fla., in 1941. Before 1928, he worked for Stout Aircraft and designed airplanes in Cincinnati, Ohio.
- References: Library of Congress, Catalog of Copyright Entries . . . Books . . . January–June 1947, 3rd ser., vol. 1 (Washington, D.C.: Government Printing Office, 1947), 115; Diário Oficial da União de 17 de Maio de 1954, p. 87, http://www.jusbrasil.com.br/diarios/2544433/dou-secao-1-17-05-1954-pg-87; Library of Congress, Catalog of Copyright Entries . . . Books and Pamphlets . . . January–June 1956, 3rd ser., vol. 10 (Washington, D.C.: Government Printing Office, 1957), 259; National Air & Space Museum, "Manufacturer: Halpin Coairdinator Co.," Collections, http://airandspace.si.edu/collections/cons.cfm?id=4932; Polk's Greater Miami City Directory (Jacksonville, Fla.: R. L. Polk & Co., 1941), 226; "Flamingo Production," Cincinnati Aviation Society & Museum, http://www.cahslunken.org/stories/FlamingoHist.htm.
- Currently not on view
- date made
- Halpin Coairdinator Company
- ID Number
- catalog number
- accession number
- Data Source
- National Museum of American History, Kenneth E. Behring Center