Dietzgen 1771 Redirule Simplex Slide Rule

This one-sided, five-inch white molded plastic rule has a plastic indicator with a hairline and plastic edges. A, D, and K scales are on the base, with B, CI, and C scales on one side of the slide and S, L, and T scales on the other side of the slide. The top and bottom edges are beveled, with a scale of 5 inches divided to 32nds of an inch on the top and a scale of 12.5 centimeters divided to millimeters on the bottom. The top of the base is marked (in red): No. 1771 REDIRULE ® DIETZGEN MADE IN U.S.A. Three screws for adjusting the rule are on the back of the instrument. The rule fits in a brown leather sheath marked: DIETZGEN. The sheath fits in an orange paper box marked on each end: DIETZGEN Redi-Rule ® (/) 5 INCH POCKET SLIDE RULE (/) Molded Plastic, Leather Sheath 1771. The rule was received with an instruction manual, 1993.0357.02.01.

According to records of the U.S. Patent and Trademark Office, Eugene Dietzgen Company began using the phrase REDIRULE to describe slide rules in 1944, applied for a trademark on the term in 1947, and received the trademark in 1953. According to Peter Hopp and Bruce Babcock, Dietzgen manufactured model 1771 of the Redirule or Redi-rule from 1941 to 1972. (Another Redirule, model 1776, had an additional six scales and metal endpieces.) Dietzgen's catalog for 1948–1949 describes model 1771 as "a real pocket companion" that "weighs no more than your pen."

References: Peter M. Hopp, Slide Rules: Their History, Models, and Makers (Mendham, N.J.: Astragal Press, 1999), 160; Bruce Babcock, "Dietzgen Catalog Matrix," Journal of the Oughtred Society 5, no. 2 (1996), http://sliderulemuseum.com/Manuals/Dietzgen_CatalogMatrix_BruceBabcock1996_chart.jpg; Dietzgen Redirule Instruction Manual (Chicago: Eugene Dietzgen Co., n.d.), http://sliderulemuseum.com/Manuals/M12_Dietzgen_1776_redirule_ref-P023.jpg; Ovid W. Eshbach and H. Loren Thompson, Self-teaching Instruction Manual: Dietzgen Decimal Trig Type Log Log Slide Rule (Chicago: Eugene Dietzgen Co., 1960), 107–108; http://sliderulemuseum.com/Manuals/Dietzgen_1734_Manual.pdf.

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