Ricoh Duplex Slide Rule Sold by Staedtler-Mars (944-24)

Numerous slide rule manufacturers also sold rules made by other companies. For instance, the German pencil-manufacturer Staedtler, which used the trade name Mars for slide rules, marketed this ten-inch bamboo rule coated with white plastic and held together with metal L-shaped endpieces. Staedtler's own rules had distinctive light blue slides, but this rule is entirely white. It was made as model 151 between about 1960 and 1972 by the Japanese firm known as San-Ai Measuring Instruments and then as Ricoh Measuring Instruments. Several companies besides Staedtler sold these rules, including Lutz.

On one 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 right end of each scale identifies the meaning of the letters, i.e., the C and D scales are marked with an x. The right end of the slide has the company logo of a Greek soldier's head and is marked: STAEDTLER (/) MARS (/) 944 24. On the other 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 indicator is clear plastic with white plastic edges. The bottom edge of the rule is marked: JAPAN.

The rule fits in a brown leather case with a loop for attaching to a belt. The flap is marked: STAEDTLER (/) MARS. The back bottom of the case is marked: JAPAN. A blue and white cardboard box is marked on the end: STAEDTLER MARS (/) 1 BAMBOO SLIDE RULE 944 24 (/) Duplex Log Log 10". See 2009.0019.02.01 for instructions. Compare to 1986.0790.04.

The mathematician and theoretical computer scientist Harley Flanders received this instrument as a gift, but he never used it.

References: "A Modern Brand Rich in Tradition," Staedtler, http://www.staedtler.com/brand_with_tradition_gb.Staedtler?ActiveID=3049; David A. Davis, "Relay/Ricoh Archive," http://www.oocities.org/usra482b/page3.html; Peter M. Hopp, Slide Rules: Their History, Models, and Makers (Mendham, N.J.: Astragal Press, 1999), 213.

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