Calculating Disc by Felsenthal, Dial-A-Base

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On September 19, 1972, George M. Boyd of Witchita, Kansas, took out U.S. patent 3,692,238 for this “navigation aid.” It consists of two discs with a slightly larger disc between them, all rotating about a pivot at the center. The outer discs have maps – one of southern Florida, and the other of northern Florida, Georgia, and Alabama. Listed around the rim are the names of air bases in the regions shown. Rotating an outer disc brings up a table of the distance from a given base to all the others. The device also provides such information as the runway patterns of the air bases, cruising altitude rules, and international Morse code. A mark on the object reads: DIAL-A-BASE (/) WITCHTA, KANSAS 67208 (/) PAT. 3692238 (/) 4 JAN 73.
George Mills Boyd, born in New Jersey, was a Tuskegee Airman, and spent his career in the United States Army (later the U.S. Air Force). He retired from the Air Force in 1971, taking up positions in Kansas.
Accession file.
U.S. Patent 3,692,238.
Website, accessed March 28, 2018.
Currently not on view
date made
Boyd, George M.
Physical Description
plastic (overall material)
metal (overall material)
overall: .2 cm x 19.1 cm x 19.1 cm; 3/32 in x 7 17/32 in x 7 17/32 in
ID Number
catalog number
accession number
Credit Line
Gift of Ben Wharton Rau and Margery Felsenthal Rau
See more items in
Medicine and Science: Mathematics
Data Source
National Museum of American History


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