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Trigonometer for Use with Artillery

Trigonometer for Use with Artillery

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The solution of right and oblique triangles is central to firing artillery. This circular disc is marked around the edge with scales labeled D (inverse sine), E (logarithmically divided), B (inverse cosine), and C (tangent and cotangent) This side also is marked: SOLUTION OF RIGHT TRIANGLE. Two clear plastic arms, one long (L) and one short (S), are held by a metal pivot at the center. A table in the center of the disc explains how to set arms L and S to solve for different sides of the triangle and/or an acute angle, given different other sides and/or an angle. The instrument is marked on the other side: SOLUTION (/) OF OBLIQUE ANGLES and has a similar table. It is also marked on this side: SOLUTION TO THE TRIAL SHOT DATA PROBLEM. Below this is a grid of lines like those on graph paper for plotting relevant observations.
A signature on the object reads: CAND. B.C. KEENEY (/) BAIM PLAT (/) AAA CAMP DAVIS, N. C. There is no maker's mark.
According to the Brown University Archives, Barnaby Conrad Keeney (1914-1980) was an officer candidate the Antiaircraft Artillery School at Camp Davis, North Carolina, in 1942. Keeney would be discharged from the Army as a captain. He went on to become the twelfth president of Brown University.
Currently not on view
Object Name
Rule, Circular
calculating instrument, trigonometric
date made
ca. 1942
ca 1942
Wheeler, Albert Harry
place made
United States
associated place
United States: Massachusetts, Worcester
Physical Description
plastic (overall material)
wood (overall material)
white (overall color)
green (overall color)
metal (overall material)
average spatial:.5 cm x 32.5 cm x 31 cm; 3/16 in x 12 25/32 in x 12 7/32 in
ID Number
catalog number
nonaccession number
Credit Line
Gift of Louise D. Campbell
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History
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