Sliding Chart for Trigonometry - Triangulator
date: label: date made
content: ca 1954
name: label: maker
content: Roeder, George E.
notes: label: Description
content: This small sliding chart for teaching trigonometry shows formulae used to calculate angles, sides, area, sines, cosines and tangents in a right triangle. A plastic card slides in a sleeve that shows a right triangle on each side of it. Windows in the sleeve reveal letters of sides and/or angles of the triangle that are known, as well as a question mark for the side or angle to be found. Another window shows a formula that allows calculation of the unknown from the known. Thirty-two different formulae are listed on the two sides of the card.
label: Description
content: One side of the chart has the mark: “Makes TRIGONOMETRY Easy”. It and the slide also are marked: “TRIANGULATOR” (/) P.O. BOX 4660 (/) WASHINGTON, D. C. The other side of the chart is marked: U. S. Pat. 2166372.
label: Description
content: The chart and a pink leaflet giving instructions (1986.0441.02) fit in a small tan envelope. George E. Roeder copyrighted the term triangulator in 1936. He applied for a patent on June 16, 1938, and was granted U.S. Patent 2166372 July 18, 1939. The object is very similar but not identical to the patent drawing. Roeder (1895-1954) was born in Germany, became a naturalized U.S. citizen, was working as an instrument maker in Washington, D.C. in 1940, and would die in Buffalo, New York. An ad for the Triangulator appeared in the <I>Hartford Courant</I> in 1942. Advertisements for the instrument appeared in <I>Popular Science</I> as late as 1959, although by then it was distributed from Buffalo, New York.
label: Description
content: According to the accession file, the donor had the Triangulator when he was an apprentice mechanic in about 1954.
label: Description
content: References:
label: Description
content: Accession file.
label: Description
content: George E. Roeder, “Formula-Finding Device,” U.S. Patent 2166372, July 18, 1939.
label: Description
content: [Advertisement], <I>Hartford Courant</I>, August 9, 1942, p. 8. The Triangulator sold for 75 cents.
label: Description
content: [Advertisement], <I>Popular Science</I>, 175, #6, December, 1959, p. 47.
label: Location
content: Currently not on view
place: label: place made
content: United States: District of Columbia, Washington
topic: label: Subject
content: Mathematics
setName: label: See more items in
content: Medicine and Science: Mathematics
label: See more items in
content: Trigonometry
label: See more items in
content: Science & Mathematics
creditLine: label: Credit Line
content: Gift of George A. Norton
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1986.0441.01
label: catalog number
content: 1986.0441.01
label: accession number
content: 1986.0441
objectType: label: Object Name
content: calculating instrument, trigonometric
physicalDescription: label: Physical Description
content: plastic (instrument material)
label: Physical Description
content: paper (envelope material)
label: Measurements
content: overall: .1 cm x 13.8 cm x 6.5 cm; 1/32 in x 5 7/16 in x 2 9/16 in