Diwa 601 Rietz Simplex Slide Rule

This five-inch, one-sided white molded plastic slide rule has K, A, D, and L scales on the base. B, CI, and C scales are on one side of the slide, and S, S&T, and T scales are on the other side, which is marked at the left end: Diwa (/) DENMARK. The top edge is beveled and has a scale of inches in red and a scale of centimeters in black. A glass indicator has a hairline and metal edges. A notch covered with clear plastic is on the right end of the base. The right end of the back is marked: No. 601 (/) MADE IN DENMARK. The back is also marked: COOPER-SIMON & CO., INC. (/) TECHNICAL SALES • FIELD ENGINEERS (/) Lehigh 5-2900 (/) 400 EAST 79th STREET • NEW YORK 21, N. Y. A brown leather sleeve has been scratched: PHIL KRUPEN. The previous owner's name is also written inside the case. Compare to 1992.0433.03.
Cooper-Simon, a distributor of ACME electric transformers, Chester cables, AEMCO relays, and various resistance products, presumably handed out this rule to advertise its firm. The Danish slide rule manufacturer, DIWA, was established in 1924 and prospered after World War II. During the postwar era, it often sold model 601 to companies for use as a promotional item. Krupen (1915–2001) was a physicist who graduated B.S. from Brooklyn College in 1935, worked on the development of the proximity fuse during and after World War II, earned a master's degree in physics from George Washington University, and spent a total of 38 years working for the U.S. government before he retired in 1973.
References: Dieter von Jezierski, Slide Rules: A Journey Through Three Centuries, trans. Rodger Shepherd (Mendham, N.J.: Astragal Press, 2000), 77; International Slide Rule Museum, "Miscellaneous Europe," http://sliderulemuseum.com/, with instructions under the directory SR_Library_Europe.htm; accession file.
Currently not on view
Object Name
slide rule
date made
ca 1950
Diwa Manufacturing Co.
Physical Description
plastic (overall material)
glass (cursor material)
metal (part material)
leather (case material)
overall: .3 cm x 16.3 cm x 4.7 cm; 1/8 in x 6 13/32 in x 1 27/32 in
place made
ID Number
catalog number
accession number
Rule, Calculating
Promotional Item
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Slide Rules
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Philip Krupen
Additional Media

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