Set Square Signed Desnos

Description
This 4-1/2" brass rule unfolds to form a set square. The outer edge of one leg has a scale for German inches (roughly 31/32 English inches), numbered by ones from 4 to 1. The first unit is divided into twelfths and numbered by threes from 3 to 12. The scale is marked: Pouces du Rhin [inches of the Rhine]. The inner edge of this leg has a scale numbered by tens from 10 to 50. The 5 point is also marked. The scale is marked: Eschelle [scale].
The outer edge of the other leg has a scale for French inches (roughly 1-1/16 English inches), numbered by ones from 1 to 4. The first unit is divided into twelfths and numbered by threes from 3 to 12. The scale is marked: pouces de Roy [inches of the French king]. The inner edge of this leg has a scale numbered by tens from 10 to 60. The 5 point is also indicated. This leg has a pinhole for hanging a plumb line and a rectangular hole with a rounded end (approximately 25/32" long) for viewing the plumb bob. This leg is also marked: Desnos AParis. Compare to 1985.0580.02, 1985.0580.03, MA*316929, and MA*316914.
Louis-Charles Desnos was a cartographer and globemaker in France from about 1753 to 1782. Another plumb rule by Desnos is shown at http://teodolite.it/desnos.htm.
Reference: Adler Planetarium, Webster Signature Database, http://historydb.adlerplanetarium.org/signatures/.
Location
Currently not on view
Object Name
set square
date made
ca 1753-1782
maker
Desnos, Louis-Charles
Physical Description
brass (overall material)
Measurements
overall: 11.3 cm x 1.7 cm x .5 cm; 4 7/16 in x 21/32 in x 3/16 in
place made
France: Île-de-France, Paris
ID Number
MA*317362
accession number
230278
catalog number
317362
subject
Squares and Triangles
Science & Mathematics
Mathematics
Drawing Instruments
See more items in
Medicine and Science: Mathematics
Squares and Triangles
Data Source
National Museum of American History, Kenneth E. Behring Center
Additional Media

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