Full Details

Name and Model Number Keuffel & Essor 4041
With Very Rare Decimal
Keeper Cursor
Country of Origin USA
Date of Manufacture 1920s
Front Scales A B C D
Back Scales S L T located on back of slider
Scale Length 25 cm (10 inches)
Type of Rule Slide Rule
Construction Celluloid on Mahogany metal framed decimal cursor
Area of Use Generic
Comment Please see my JOS articles on decimal cursors in V18.1-2009-page46.
Rarity RRR
Donor Collection of Clay Castleberry
Match Number 319
(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.