DescriptionSlide rule, model 4054 (advanced Mannheim type), 10 inch, made by Keuffel & Esser Co. in Hoboken, no date, circa 1937-1944. Mahogany with white celluloid, engine engraved; chart on back printed with clear covering; "frameless" (thin aluminum frame) glass cursor with white celluloid slides. Serial number: 268728. Front scales: A [B C1 C] D K. Back scales: S, L , T. Front has has company name and the patent number 1,934,232 which was granted in 1933 to Adolf Keuffel for advances in adjustments of this slide rule type (it is related to the three screws on the back.) The cursor has patent number 2,086,502 granted in 1937 for an advanced cursor. With a low serial number in this range, its probable date of manufacture was ca. 1940. Although marked "N.Y." the company did its manufacturing in Hoboken at this time.