Full Details

Name and Model Number Dietzgen Fraction Adder
Country of Origin USA
Date of Manufacture Jaeger patent 169941, June 1953
Front Scales Fractions of an inch
Back Scales none
Scale Length 4.5" diameter
Type of Rule Disc
Construction Aluminum - 3 discs - painted scales
Area of Use Other
Comment Made in Detroit by Shardco Inc. for Dietzgen.
Rarity RR
Donor Collection of Clay Castleberry
Match Number 270
(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.