Calculating Disc, Electronic Evaluation Slide Rule, Felsenthal FDN-9
date: label: date made
content: 1969
name: label: maker
content: Felsenthal Instrument Co.
notes: label: Description
content: To check the accuracy of radar measurements, the U.S. Navy used a device called an echo box. This small plastic instrument allowed one to correct echo box dial readings according to the temperature and the form of radar used. A tag received with the object indicates that it was sold by Felsenthal as the FDN-9.
label: Description
content: Reference:
label: Description
content: U.S. Department of the Army, <I>Test Set TS-172A/UP, Technical Manual 11-1262</I>, 1991, p. 2-1 through 3-2.
label: Location
content: Currently not on view
topic: label: Subject
content: Mathematics
label: Subject
content: Radar
setName: label: See more items in
content: Medicine and Science: Mathematics
label: See more items in
content: Military
label: See more items in
content: Science & Mathematics
creditLine: label: Credit Line
content: Gift of Ben Wharton Rau and Margery Felsenthal Rau
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1977.1141.32
label: catalog number
content: 336416
label: accession number
content: 1977.1141
objectType: label: Object Name
content: Calculating Disc
physicalDescription: label: Physical Description
content: plastic (overall material)
label: Physical Description
content: metal (overall material)
label: Measurements
content: overall: .1 cm x 14.6 cm x 15.2 cm; 1/32 in x 5 3/4 in x 5 31/32 in