DescriptionLog Log Duplex Trig 10" slide rule, 4080-3S, made by Keuffel & Esser Co., New York, no date, circa 1955-1957. Mahogany, machined and laminated, with laminated white celluloid plastic ruled ("engine divided") scales in red and black; 12-1/2" overall length x 1-9/16" high x 3/8" thick. Indicator (cursor) is improved glass, no patent numbers or maker's markings. Accompanied by tan leather case (sheath; as denoted by the 'S' in the model number.) With: original slipcase carton with printed label on tray end; enclosed in container were three publications: two pamphlets: "Instructions for Operating Slide Rules" (non-K&E publication); "How to Take Care of Your K&E Slide Rule" plus 124 page book, "K+E Log Log Duplex Trig No. N4080 Manual." These publications are separately catalogued as archives 2009.006.0138 to .0140. Inlaid plastic on top edge has: "Pat. Pend."; "Made in U.S.A."; model number; rule name; "Copyright 1947"; "Keuffel & Esser Co."; "Patents 2,500,360; 2,170,056; 2,285,722; 2,422,649." Serial number, 140727, appears on back slide at left end; lot number "727" appears twice on stator above and below serial number. K&E logo on front slide at right end. Scales are on the front: LL01, L, K, A, B, S, ST, S, D, DI, LL1 Scales are on the back: LL02, LL03, DF, CF, CIF, CI, C, D, LL3, LL2 K&E had their main office and factories in Hoboken when this item was made.