DescriptionLog-log duplex trig slide rule, model 4080-3, made by Keuffel & Esser Co.in Hoboken, no date, circa 1937-1940. White celluloid, engine-engraved in red and black, mounted on mahogany wood with metal strap plates; 10" scale length (indicated by the "-3" after the model number 4080); 12-1/2" overall length x 1-5/8" wide. Lacking cursor. Serial number 167757. No case present. Although engraved as Keuffel & Esser Co., N.Y, manufacturing for K & E was in Hoboken from 1875 to the late 1960s. Patent number 1,930,852 along with two patents pending (applied for in 1937, issued 1939) suggest the early date for manufacture. The lack of a cursor makes this late date as only a suggested one. (n.b.current reference on K&E serial numbers suggests that they are problematic in dating this product.)