Dietzgen 1734 Decimal Trig Log Log Duplex Slide Rule

Relatively late in its history of making and selling slide rules, the Eugene Dietzgen Co. of Chicago began developing products that competed with the high-end slide rule lines manufactured by Keuffel & Esser (namely, model 4081) and Post (the Versalog). This two-sided, ten-inch wooden slide rule is coated with white plastic and has metal endpieces. On one side the base has LL02, LL03, DF, D, LL3, and LL2 scales, with CF, CIF, L, CI, and C scales on the slide. The top of the base is marked: DIETZGEN MICROGLIDE _TM DECIMAL TRIG TYPE LOG LOG CAT. NO. 1734.

On the other side, the base has LL01, K, A, D, DI, and LL1 scales, with B, T < 45°, T > 45°, ST, and S scales on the slide. The top of the base is marked: EUGENE DIETZGEN CO. PATS. 2,170,144 2,285,722 PAT'S PEND. MADE IN U.S.A. 020038. On both sides the right end of the rule has formulas indicating the functions represented by the scales. The glass indicator has a metal and black plastic frame; both edges are marked: DIETZGEN.

The rule fits in a black leather case with a metal clasp. A Dietzgen logo is on the flap—the letter D inside the letter E inside the letters Co. In 1959 Dietzgen introduced the Microglide line of slide rules, which featured Teflon-lined grooves on the base so that the slide moved more smoothly. According to Ian Lodge's estimated production figures, the serial number suggests a manufacture date for this object of 1962.

Dietzgen ceased the production of slide rules around 1972. The arrangement of scales corresponds to those depicted in a 1960 instruction manual for the "Dietzgen Decimal Trig Type Log Log Slide Rule," although the "Microglide" trademark is not mentioned. See 1986.0790.01 for information on the patents mentioned on the instrument. The indicator is Dietzgen's "framed full vision" type and is covered by U.S. Patent 2,634,912, issued to Clarence P. Davey on April 14, 1953.

The donor, Ed Severino, began his career as an engineer with General Electric Company in Schenectady, N.Y. After eight years, he left to teach mathematics and science at Mont [sic] Pleasant High School in Schenectady, where he became head of the Technical Department. The slide rule is of the type trainees used in the late 1970s and early 1980s, when Severino was director of his high school's General Electric Apprentice Training Educational Program.

References: Rodger Shepherd, "Some Distinctive Features of Dietzgen Slide Rules," Journal of the Oughtred Society 5, no. 2 (1996): 42–45; Robert K. Otnes, "Dietzgen Patents, Runners, and Log-Log Scales," Journal of the Oughtred Society 5, no. 2 (1996): 45–48; Ian Lodge, "Estimating Production Dates for Dietzgen Micromatic and Microglide Log Log Duplex Slide Rules," Journal of the Oughtred Society 21, no. 1 (2012): 26–32; Bruce Babcock, "Dietzgen Catalog Matrix," Journal of the Oughtred Society 5, no. 2 (1996), http://sliderulemuseum.com/Manuals/Dietzgen_CatalogMatrix_BruceBabcock1996_chart.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), http://sliderulemuseum.com/Manuals/Dietzgen_1734_Manual.pdf; "Your Dietzgen Microglide Slide Rule: Instructions for Care and Adjustment" (Chicago, n.d.), http://sliderulemuseum.com/SR_Library_Dietzgen.htm.

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