RelayRicoh Duplex Slide Rule for Lutz (151P)

This ten-inch, two-sided bamboo rule is coated on all sides with white plastic and has a plastic indicator with white plastic edges. Metal L-shaped endpieces hold the rule together. On one side, the base has LL/0, L, K, A, D, DI, P, and LL0 scales, with B, S, ST, T, and C scales on the slide. The top left edge of the base has a date stamp: Q.S–3. The right end of the slide is marked: LUTZ (/) NO.151P. It is also marked U.S. The bottom right corner of the base is marked: MADE IN JAPAN.
On the other side, the base has LL/1, LL/2, LL/3, DF, D, LL3, LL2, and LL1 scales, with CF, CIF, CI, and C scales on the slide. The rule fits in an orange leather case marked on the flap: LUTZ (/) SLIDE RULE. Inside the flap is written in pen: PHIL (/) KRUPEN (/) 9518 SEMINOLE ST (/) SILVER SPRING, MD. The back of the case is marked: MADE IN JAPAN.
The Lutz Company began to manufacture drawing instruments and artists' materials in Guttenberg, N.J., around 1892. After World War II, the firm imported slide rules made in Japan by Ricoh Measuring Instruments (known from 1948 to 1950 as the Nippon Slide Rule Company, from 1950 to 1958 as Relay Industries, and from 1958 to 1963 as San-Ai Measuring Instruments). The letter Q in the date stamp suggests that the slide rule was made in 1968. Compare to 2009.0019.02; unlike this rule, that rule defines the mathematical meaning of each scale.
The physicist Philip Krupen (1915–2001) donated this slide rule to the Smithsonian in 1986. Krupen received his B.S. degree from Brooklyn College in 1935, worked on the development of the proximity fuze 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 his retirement in 1973.
References: State of New Jersey, Manual of the Legislature of New Jersey (Trenton: T. F. Fitzgerald, 1902), 296–297; Paul Ross, "Relay/Ricoh Slide Rules," Journal of the Oughtred Society 9, no. 2 (2000): 64; "Philip Krupen," Washington Post, February 23, 2001, B07.
Currently not on view
Object Name
slide rule
date made
Ricoh Measuring Instruments
Physical Description
plastic (laminate material)
bamboo (overall material)
leather (case material)
plastic (cursor material)
overall: 2.5 cm x 36.7 cm x 7.5 cm; 31/32 in x 14 7/16 in x 2 15/16 in
place made
Nihon: Japan
ID Number
accession number
catalog number
Rule, Calculating
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Slide Rules
Data Source
National Museum of American History, Kenneth E. Behring Center


Add a comment about this object