Magnetic Compass with Sights

Description
This magnetic compass has a paper scale, a metal needle, a wooden case, and a glass cover. The scale is graduated every 10 grads and marked every 20, with a total of 400 grads in the circle. Folding metal sights are attached to the north and south edges. A plumb bob stored in the north edge of the case can be suspended from the east edge.
From ancient times, mathematicians described a right angle as having ninety degrees. In the 1790s, the French introduced a right angle of one hundred decimal degrees or grads. Instruments divided this way were available in France and in the United States into the 20th century.
Location
Currently not on view
Object Name
magnetic compass
Physical Description
paper (scale material)
metal (needle, sights, plumb bob material)
wood (case material)
Measurements
overall: 1 3/4 in x 8 3/8 in x 4 1/2 in; 4.445 cm x 21.2725 cm x 11.43 cm
place made
France
ID Number
PH*314618
catalog number
314618
accession number
208046
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Metric System
Data Source
National Museum of American History, Kenneth E. Behring Center

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