Vintage K&E N9081-3 Slide Rule Complete Box Set with Case Case & N4081 Manual For Sale

Vintage Keuffel & Esser (K&E) Doric N9081-3 Log Log Duplex Decitrig Slide Rule - Complete Estate Set with Original Box, Leather Case, and Period-Correct Manual.
Historical Significance:
Up for sale is a remarkably complete, mid-century piece of mathematical history. TheK&E Doric N9081-3was Keuffel & Esser's very first all-plastic frame duplex slide rule, manufactured only for a brief window between1948 and 1952. It is highly sought after by completionist collectors due to its short production run. Fun historical fact: This exact N9081-3 model line was notably favored and used by original Project Mercury Astronaut Gordon Cooper during his historic military and NASA careers!The Factory Manual Quirk:
Buyers will note that the included original instruction booklet is labeled"No. N4081."This is completely period-correct and accurate to how the set left the factory. Because the N9081-3 was K&E's new plastic conversion of their flagship mahogany N4081 scale set, K&E intentionally packaged these early Doric units with N4081 manuals because the operational scales and mathematical layouts were identical. This pairing is an untouched time capsule showing exactly how the set was sold in the late 1940s/early 1950s.Provenance & Historical Character:
Unlike sterile, dead-stock items that sat forgotten in a warehouse drawer, this slide rule tells a story and has a real history. It belonged to an engineer or academic namedBill Landt. His name is clearly preserved in vintage ink across the front cover of the instruction manual. The inside leather flap of the carrying case is also hand-stamped with his name and location:"Bill Landt, Luana, Iowa", alongside a tiny decorative footprint emblem. This personalization adds an undeniable layer of authentic mid-century provenance, proving it was a trusted tool used during America's golden age of engineering.What is Included & Condition Report:
This vintage set remains in solid collectible condition:

• The Slide Rule:In beautiful mechanical condition. The rule has excellent tension, slides smoothly, and the text remains sharp and highly legible. The glass cursor is fully intact. Serial numbers match across the frame components.
• The Leather Case:The premium textured black leather is in great condition across the main body. It shows some typical vintage edge wear, minor splitting, and scuffing strictly isolated to the flexible opening area and belt attachment loop from real-world field use.
• The Manual:Completely intact, readable, and functional. However, the front paper cover has a clean split/break along the bottom edge near the "Keuffel & Esser Co." text.
• The Outer Box:The original green cardboard textured box shows typical vintage shelf wear along the edges, but it remains structurally sound and has protected the set for over 70 years.

Please review all photos closely, as they serve as the definitive visual guide to this historical set's cosmetic condition.Ships securely packaged to ensure safe arrival to your collection.