BRASS PRODUCTION PLATE FOR SLIDE RULES, American, 1961, signed in the plate “Keuffel & Esser Co., K-12 Prep, K&E 4158.” The substantial 12-1/4″ x 2-3/4″ (31 x 7 cm) brass plate bears in relief the complete highly detailed layout for this single-sided slide rule, with all the divisions, calibrations, and labels. There are nine scales, including those on the slider which here is formed integrally in its zero position on the rule. Condition is excellent. This most rare factory production plate was used for the model 4158 (K12 Prep), which was released in 1961. It was supplanted by the model “68-1892 (K12 Prep)” the following year; consequently it was marketed and sold, but apparently never illustrated in the K&E catalogues. Rare.
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David and Yola Coffeen both have enjoyed academic careers, as planetary astronomer and as linguist/educator. But since 1982 (yes, 1982!) they have been full-time dealers in early scientific and medical instruments, under the name Tesseract. Selling primarily by catalogue (over 100 issued so far) they also have a web presence at www.etesseract.com, and can be contacted at [email protected]