Smithsonian museums continue to be closed to support the effort to contain the spread of COVID-19. No re-opening date is available at this time. Check our website and social media for updates.

Halpin Coairdinator Made for Aeronautical Information Data Systems

Halpin Coairdinator Made for Aeronautical Information Data Systems

<< >>
Usage conditions apply
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,; 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,; Polk's Greater Miami City Directory (Jacksonville, Fla.: R. L. Polk & Co., 1941), 226; "Flamingo Production," Cincinnati Aviation Society & Museum,
Currently not on view
Object Name
scale rule
date made
Halpin Coairdinator Company
place made
United States: Florida
Physical Description
plastic (overall material)
metal (overall material)
overall: .1 cm x 17.9 cm x 4.1 cm; 1/32 in x 7 1/16 in x 1 5/8 in
ID Number
catalog number
accession number
Credit Line
Gift of Ben Wharton Rau and Margery Felsenthal Rau
Navigation, Aeronautical
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Scale Rules
Data Source
National Museum of American History
Nominate this object for photography.   

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.


Add a comment about this object