Full Details

Name and Model Number Keuffel & Esser 4040
Country of Origin USA
Date of Manufacture 1901
Front Scales 10 inch /, A [ B C ] D, | 27 cm
Back Scales Slide: [ S L T ], Rule: Conversion table
Scale Length 25 cm
Type of Rule Slide Rule
Construction Celluloid on mahogany with brass chisel cursor
Area of Use Generic
Comment Believed to be the forerunner of the popular 4041.
Rarity RR
Donor Collection of Clay Castleberry
Match Number 234
(Click Picture for Details)

In conjunction with our 'donors' we assign a rarity rating to each item, based on the system devised by Herman van Herwijnen
(1929 - 2004), renowned Dutch collector, author, and creator of Herman's Archive, a collection of 5,000 slide rule images on CD.
• RR = Rare - 1 of 25 collectors has one; it may take a year to find an example in the marketplace.
• RRR = Very Rare - only a few known to collectors; may be several years before it comes up for sale.
• RRRR = Extremely Rare - a museum piece; unlikely that an example will come up for sale.