Circular Slide Rule, Bearing Rate Computer, Felsenthal FNR-5
name: label: maker
content: Felsenthal Instrument Co.
notes: label: Description
content: Mathematical instruments have long been used to assist in aiming weapons. This circular slide rule is one such device. Made for use in antisubmarine warfare, it has two scales on the base, two scales on a concentric disc atop this, and a rotating pointer pivoted at the center. The lower disc has scales for the target speed in knots and the range in yards. The upper disc has scales for the bearing rate and angle on bow. The inner scales on both the base and the disc are in green.
label: Description
content: A mark on the lower edge of the base reads: SPECIAL DEVICES CENTER DEVICE 1-BA-2a (/) BEARING RATE COMPUTOR [sic]. A mark on the disc reads:G. FELSENTHAL & SONS, INC. (/) PART NO. FNR-5.
label: Description
content: Felsenthal made bearing rate computers for the U.S. Navy from at least the 1950s until at least the year 2000. A tag received with the object indicates that this model was produced from 1952.
label: Description
content: Compare 1977.1141.33, 1977.1141.34, 1977.1141.35, and 1977.1141.36. Objects 1977.1141.35 and 1977.1141.36 appear to differ only in device number, the color of the two inner scales, and the spelling of “COMPUTER.”
label: Description
content: Reference:
label: Description
content: U.S. Navy, <I>Operations Specialist Volume I, NAVEDTRA 14308</I>, 2000, p. 10-22 through 10-28. This volume was accessed online August 3, 2017.
label: Location
content: Currently not on view
topic: label: Subject
content: Mathematics
setName: label: See more items in
content: Medicine and Science: Mathematics
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content: Military
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content: Science & Mathematics
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content: Slide Rules
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: 1977.1141.34
label: catalog number
content: 336418
label: accession number
content: 1977.1141
objectType: label: Object Name
content: slide rule
physicalDescription: label: Physical Description
content: plastic (overall material)
label: Physical Description
content: metal (overall material)
label: Measurements
content: overall: .2 cm x 15.2 cm x 15 cm; 3/32 in x 5 31/32 in x 5 29/32 in