MHR1 Höhenrechenschieber Cylindrical Slide Rule
date: label: date made
content: ca 1940
name: label: maker
content: Dennert and Pape
notes: label: Description
content: This cylindrical calculating rule was designed to solve problems in spherical trigonometry encountered in navigation. For example, it could be used to compute the altitude and azimuth of a celestial body, knowing the latitude of the observer and the hour angle and declination of the body. Such a slide rule was patented by the Englishman Leonard C. Bygrave in 1921. This example, serial number 90143, was manufactured in Germany by Dennert and Pape at about the time of World War II.
label: Description
content: The instrument consists of three concentric cylinders. The innermost cylinder can be extended, and the outermost cylinder then slides up and down on part of the extended tube. Tightening a knob at the top fixes the relative position of the two inner cylinders. The innermost cylinder has a helical scale divided from 0 to 90 degrees (also from 180 down to 90). The middle cylinder has a helical scale marked from 0 to 90 and also from 145 to 90. At the bottom, the middle cylinder has instructions for using the instrument. The outermost cylinder has two marks for reading results, declination tables, formulas, and a window that allows for reading the second scale. The instrument fits in a cylindrical metal case painted black and lined with cloth near the top.
label: Description
content: This object was found in the Naval History collections of the National Museum of American History some time before August 1984.
label: Description
content: References: U.S. Hydrographic Office, <i>American Practical Navigator</i> (Washington, D.C., 1958), 559; L. C. Bygrave, "Improvements in Calculating Apparatus," (U.K. Patent 162,895 issued May 12, 1921); Serge Savoysky, "Calcul de navigation: État courant de l'étude de l'hélice logarithmique MHR1 de Dennert et Pape," http://serge.savoysky.pagesperso-orange.fr/Calcul%20de%20navigation,%20v2%20(WEB).pdf.
label: Location
content: Currently not on view
place: label: place made
content: Germany
topic: label: Subject
content: Rule, Calculating
label: Subject
content: Naval History
label: Subject
content: Mathematics
label: Subject
content: Navigation
setName: label: See more items in
content: Medicine and Science: Mathematics
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content: Science & Mathematics
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content: Trigonometry
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content: Slide Rules
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 2005.0271.03
label: accession number
content: 2005.0271
label: catalog number
content: 2005.0271.03
objectType: label: Object Name
content: calculating rule
label: Object Name
content: slide rule
physicalDescription: label: Physical Description
content: metal (overall material)
label: Physical Description
content: paper (part material)
label: Physical Description
content: plastic (part material)
label: Physical Description
content: cloth (part material)
label: Measurements
content: overall: 28.5 cm x 7.5 cm x 7.5 cm; 11 7/32 in x 2 15/16 in x 2 15/16 in