System Wern ABC Circular Slide Rule

System Wern ABC Circular Slide Rule

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This plastic circular slide rule has a square white base with a transparent disc and pointer pivoted atop it. The outermost scale runs from 5 degrees to 90 degrees (going counterclockwise). Inside this, still on the base, is a scale from 0 degrees to 85 degrees. Immediately inside this is a scale for converting from degrees to radians. Other scales are for multiplication, division (showing decimal points in results), conversion of metric and standard units, squares, cubes (and square roots and cube roots), logarithms, sines, tangents (and arc sines and arc tangents), and percentages. A scale of equal parts 20 centimeters long, divided to millimeters, runs across the top of the base.
The device fits in a square black plastic envelope. Thie envelope also contains two sets of instructions on paper.
The slide rule is on the design of the American-born Swedish engineer Carl Wern and his younger brothers George and Lars Wern, also Swedes. They licensed rights to manufacture their slide rule to IWA Rechenschieberfabrik in Germany.
Currently not on view
Object Name
slide rule with instructions
date made
ca 1966
IWA Rechenschieberfabrik
place made
Germany: Baden-W├╝rttemberg, Neckar
Physical Description
plastic (case, base, disc, runner material)
metal (pivot material)
paper (instructions material)
overall:.2 cm x 22.4 cm x 22.4 cm; 3/32 in x 8 13/16 in x 8 13/16 in
ID Number
accession number
catalog number
Credit Line
Gift of Carl R. Wern, George H. Wern, and Lars A. Wern
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Slide Rules
Data Source
National Museum of American History
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