Maclean Square Navigational Protractor
date: label: date made
content: 1950s-1960s
name: label: maker
content: J. D. Maclean Co.
notes: label: Description
content: This clear Perspex (acrylic glass) square protractor is divided by single degrees and marked by tens in the clockwise direction from 010° to 350°. A red arrow points to the origin. The marks for 090°, 180°, and 270° are replaced by the compass points E, S, and W, respectively. Diagonal lines to the four corners of the protractor are marked with the compass points NE, SE, SW, and NW. A pinhole is at the center of the protractor.
label: Description
content: The interior of the protractor is marked with a grid. Tick marks (four per square) appear along the X and Y axes and around the outside edge of the grid. The top is labeled (in red): MACLEAN PROTRACTOR. Maker's marks are at the bottom: REGD. TRADE MK. AIRNAVA; J. D. MACLEAN ∙ Co. LONDON W.C.2. The protractor is stored in a tan cardboard case, which is printed with instructions for using the instrument. Marine and aviation navigators could employ it as a parallel rule, station pointer, and plotter. John Donald Maclean patented a rectangular protractor and parallel rule in the United States. No record of a trademark for "Airnava" was found in the United States or in Great Britain. This form of protractor is standard and is sometimes called a Douglas type of square protractor. Weems & Plath manufactures similar protractors in the 21st century.
label: Description
content: Reference: <I>Journal of Navigation</I> 15, no. 4 (1962): front matter.
label: Location
content: Currently not on view
place: label: place made
content: United Kingdom: England, London
topic: label: Subject
content: Mathematics
label: Subject
content: Protractor
label: Subject
content: Navigation
setName: label: See more items in
content: Medicine and Science: Mathematics
label: See more items in
content: Science & Mathematics
label: See more items in
content: Protractors
creditLine: label: Credit Line
content: Gift of Howard Chapelle
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1987.0788.05
label: accession number
content: 1987.0788
label: catalog number
content: 1987.0788.05
objectType: label: Object Name
content: protractor
physicalDescription: label: Physical Description
content: cardboard (overall material)
label: Physical Description
content: plastic (overall material)
label: Measurements
content: overall: .6 cm x 13.9 cm x 13.8 cm; 1/4 in x 5 15/32 in x 5 7/16 in