1920s Keuffel & Esser Slide Rule Model 4061T in Original Leather Case | Vintage Engineering Instrument

For the engineer … a fine 1920s Keuffel & Esser slide rule, Model 4061T, made in New York and housed in its original leather case. This early K&E rule features a wood body with white celluloid-faced scales, metal end plates, and a clear glass cursor. The front is labeled with A, B, S, C, and D scales, while the reverse carries A, BI, T, CI, D, and L, providing a full range of logarithmic, trigonometric, and reciprocal functions.  A well-preserved early example by America’s best-known slide rule manufacturer, it would make a considered gift for the collector or someone in the engineering profession.

Keuffel & Esser was founded in New York in 1867 by Wilhelm Keuffel and Hermann Esser and for decades was the dominant American manufacturer of slide rules, surveying instruments and drafting equipment.  Before electronic calculators, K&E slide rules were the standard professional tool in American engineering and architecture, comparable in prestige to Faber-Castell in Germany.  

At 7-1/8 inches, this compact model was designed for portability while retaining the full working scale arrangement of a professional instrument.  It carries patent dates for 1900, 1908, and 1918, along with an engraved name (C.A. COURCHESNE) that reflects how important  these tools were to their owners.

Dimensions: (Rule) 7-1/8” x 1-1/16” x 7/16”; (Case) 7-5/8” x 2-7/16” x 5/8"
Weight: (Combined) 3.9 oz.

Condition notes: Very good vintage condition overall with light, age-appropriate wear. Wood body remains straight and stable with uniform age-related yellowing to the celluloid surfaces and minor handling marks throughout; scales are clean and legible on both sides, with front labeled A, B, S, C, and D and reverse carrying A, BI, T, CI, D, and L. Patent markings read “PAT. JUNE 5, 1900,” “DEC. 22, 1908,” and “PAT. 8.17.18,” and stock is marked “K&E CO. N.Y.” and “4061T,” with engraved owner’s name “C.A. COURCHESNE” on one of the metal end plates.  Glass cursor window remains intact and secure; one machine screw is missing from one side of the cursor, but cursor remains stable and slides smoothly without looseness. Slide moves freely and rule operates as intended, though accuracy has not been formally tested.  Metal end plates show light surface wear consistent with age. Original leather case bears age-consistent scuffs and scratches, stitching remains intact with no fraying, and snap closes with rule inside, though fit is tight. Other items in photos not included.

All items are hand-wrapped and packed with care for secure delivery. We offer flat rate shipping via USPS Ground Advantage for $10, or USPS Priority Mail for $15. Orders over $100 (not including taxes) ship free via USPS Priority Mail — any shipping charges for orders over $100 will be refunded after checkout. We pack with safety and care using recycled and recyclable materials whenever possible.

Sorry, no returns or cancellations.  Please view all photos for more detail and feel free to contact the shop with any questions prior to purchase.