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/.