Full Details

Name and Model Number Keuffel & Esser 4104
Mystery 2O Inch
Country of Origin USA
Date of Manufacture 1945
Front Scales 50cm / A [ B CI C ] D L | K
Back Scales Slide: [ S A T ] ; NBS Circular No. 47 Conversion Table
Scale Length 20" (25 cm)
Type of Rule Slide Rule
Construction Celluloid on mahogany
Area of Use Generic
Comment Mystery rule with model number 4104 not appearing in any K&E catalog.
Scale set similar to N4053-5 except for location of L and K scale and
the inclusion of A scale on reverse.
Serial No. 118637.
Rarity RRR
Donor Collection of Dr. Paul J. Tarantolo Jr.
Match Number 38
(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.