Dietzgen 1735 Maniphase Multiplex Vector Slide Rule

This two-sided, ten-inch wooden slide rule is coated with yellowed plastic and has metal endpieces. A glass indicator is cracked on both sides and has metal and black plastic edges marked: DIETZGEN. On one side, the base has L, LL1, DF, D, LL3, and LL2 scales, with CF, CIF, LCI, and C scales on the slide. The top of the base is marked in red: DIETZGEN MANIPHASE MULTIPLEX VECTOR TYPE LOG-LOG RULE CAT. NO. 1735.

On the other side, the base has LL0, LL00, A, D, Th, Sh2, and Sh1 scales, with B, T, ST, and S scales on the slide. The top of the base is marked: EUGENE DIETZGEN CO. PATS. 2,170,144 2,285,722 MADE IN U.S.A. 108821. The top edge of the rule is marked in script: Dom Petrone. The bottom edge is marked: DP.

An orange leather case is marked on the flap: K+E. The front of the case is marked: P. Inside the flap is marked: GWU (/) Gerald (/) PETRONE (/) U of Md (/) Easton MD (/) MIT (/) PETRONE, RA. Lines 1–3, 4–5, and 6–7 are each in different inks and handwriting.

The Eugene Dietzgen Company of Chicago offered model 1735 from 1941 to 1952. "Maniphase" refers to an arrangement of scales in which the company added K and CI scales to Mannheim rules; the word is printed on several slide rules sold by the Eugene Dietzgen Company. This rule is similar to 1986.0790.01, but it has hyperbolic tangent and sine scales on the back of the base instead of DI and K scales.

Three U.S. Naval Academy professors applied for the patents mentioned on this slide rule in 1937 and 1938. These patents dealt with arranging and coloring scales so that problems could be solved in the fewest steps; they were also cited on Keuffel & Esser slide rule models 4080 and 4801. (See 1992.0437.01, 2007.0181.01, MA.318482, MA.334387, 1990.0687.01, and 1986.0790.03.)

According to the donor, the rule was purchased by his uncle, Rocco Anthony Petrone (1926–2006), while he was studying for a master's degree in mechanical engineering at the Massachusetts Institute of Technology in 1950 and 1951. After graduation he developed rockets for the U.S. Army. From 1966 to 1975, Petrone held various leadership positions at NASA, including director of the Apollo program (1969–1973).

Petrone passed the slide rule on to his brother, Dominic J. Petrone, who earned a BS in electrical engineering from Union College in 1950. Dominic gave the rule to his son, Gerald Petrone, who studied engineering at George Washington University in 1969 and subsequently at the University of Maryland at College Park. Gerald broke the indicator and acquired the replacement now on the instrument. He then passed the instrument to his brother, donor David Petrone, who studied electrical engineering at UMCP from 1971 to 1974. At some point, the original case was also replaced with a case from Keuffel & Esser. Several of the Petrones who used the slide rule marked it or the case with their name or initials.

References: Bruce Babcock, "Dietzgen Catalog Matrix," Journal of the Oughtred Society 5, no. 2 (1996), http://sliderulemuseum.com/Manuals/Dietzgen_CatalogMatrix_BruceBabcock1996_chart.jpg; William K. Robinson, "Slide Rules with Hyperbolic Functions," Journal of the Oughtred Society 14, no. 1 (2005): 55–62; Robert Otnes, "Dietzgen Patents, Runners, and Log Log Scales," Journal of the Oughtred Society 5, no. 2 (1996): 45–48; Lyman M. Kells, Willis F. Kern, and James R. Bland, "Slide Rule" (U.S. Patent 2,170,144 issued August 22, 1939), and "Slide Rule" (U.S. Patent 2,285,722 issued June 9, 1942); accession file; "Candidates for Union College Degrees," Evening Recorder, Amsterdam, N.Y. (June 8, 1950), 5.

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