Civil Defense radiation dosage calculator

Date: c. 1963
Materials: plastic; paper; metal
Dimensions: Height x Width x Depth (Envelope): 5 1/4 x 4 1/2 x 1/8 in. (13.34 x 11.43 x 0.32 cm) Height x Width x Depth (Calculator): 4 5/16 x 4 5/16 x 1/16 in. (10.95 x 10.95 x 0.16 cm) Height x Width x Depth (Directions Open): 5 x 5 1/4 in. (12.7 x 13.34 cm) Height x Width (Directions Closed): 5 x 4 1/8 in. (12.7 x 10.48 cm)
Museum: National Postal Museum
Credit line: Transfer from the United States Postal Inspection Service

Civil Defense radiation dosage calculator with plastic dial chart, instruction sheet, and envelope. This was part of historical items transferred to the museum from the US Postal Inspection Service. This was part of the United States Civil Defense program of which the Post Office Department, and later United States Postal Service, were to serve the public during an emergency.

References:

“The Postal Service’s Role in Civil Defense during the Cold War.” Unites States Postal Service Historian’s Office. July 2021. https://about.usps.com/who-we-are/postal-history/postal-service-role-in-civil-defense.pdf

The museum's own record (Smithsonian, National Postal Museum)