These eight white plastic rules have scales dividing 10 centimeters into proportions of 1:75, 1:50, 1:40, 1:33-1/3, 1:30, 1:25, 1:15, and 1:10. They are fastened together inside a brown leather sleeve marked: BLUE (/) WHITE. The words form a logo with a triangle and T-square. The 1:75 rule is marked: ARISTO (/) Nr. 1324. Inside the sleeve is a price tag marked: BLUE & WHITE (/) ESCALA (/) ARISTO (/) NO. 1324 (/) $30.00.
In 1948 the German slide rule company, Dennert & Pape, was renamed Aristo, after the brand of plastic slide rules the firm was then manufacturing. Aristo stopped manufacturing mathematical instruments in 1978 and turned to computer-aided design. Model 1324 is shown in a 1955 catalog, alongside other rulers and architect's scales. The donor, Sebastian J. Tralongo (1928–2007), served in the U.S. Navy during World War II and then worked for the Vitro Corporation in Rockville, Md., for 35 years. He patented a device for signaling from deeply submerged submarines.
References: International Slide Rule Museum, "Aristo," http://sliderulemuseum.com/Aristo.htm; Walter Shawlee II, Ted Hume, and Paul Ross, "Aristo Slide Rule Archive," Sphere Research Corporation, http://www.sphere.bc.ca/test/aristo.html; Aristo Slide Rules & Drafting Instruments (Germany, [1955]), 36; "Tralongo, Sebastian James 'Subby'," Hartford Courant, May 26, 2007; Sebastian J. Tralongo, "Submarine Signal Device" (U.S. Patent 2,989,024 issued June 20, 1961); "Vitro Corp. – Company Profile," http://www.referenceforbusiness.com/history2/25/Vitro-Corp.html.
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