Model for Descriptive Geometry by A. Jullien - Angle between Two Lines

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The given lines are the black strings: ab’ and dc’. They intersect at (m, m’). Segment ad on the horizontal plane creates a triangle with the given lines as sides. Point n on the horizontal plane is perpendicular to ad through point (m, 0). By rotating the triangle about line ab onto the horizontal plane, point (m, m’) maps to point M2. Angle aM2d is the angle between the two given lines.
For more details, see COLL.1986.0885 and 1986.0885.01.01.
Currently not on view
date made
ca 1880
Jullien, A.
place made
France: Île-de-France, Paris
Physical Description
paper (overall material)
metal (overall material)
overall: 6.5 cm x 7.5 cm x 6.5 cm; 2 9/16 in x 2 15/16 in x 2 9/16 in
ID Number
catalog number
accession number
descriptive geometry
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Jullien Geometric Models
Data Source
National Museum of American History