Full Details

Name and Model Number Keuffel & Esser 4071-T
Country of Origin USA
Date of Manufacture Cox duplex patent date of October 6, 1891
Front Scales A B Tm CI D
Back Scales A B D C D
Scale Length 25 cm (10 inches)
Type of Rule Slide Rule
Construction Celluloid on Mahogany – fixed end frames - open out.
Area of Use Generic
Comment Unusual clam shell cursor –log scale on edge - This example is unmarked as to model. Old Cox patent, K&E duplex
Rarity RRR
Donor Collection of Clay Castleberry
Match Number 296
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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.