Full Details

Name and Model Number ADF Products
ARC Extended Scale
Semi-Circular Slide Rule
Country of Origin USA, NYC
Date of Manufacture c.1960
Front Scales L, S, T, & 10-M long scale in 25 semicircular sections.
Back Scales NONE
Scale Length Number scale is 10-m long
Type of Rule Slide Rule
Construction Painted aluminum with 2 transparent cursors
Area of Use Generic
Comment This semi-circular slide rule was designed by Andrew Frankenfield who still lives in New Jersey. He designed and sold this slide rule. The production was limited as no examples are known in circulation.
Rarity RRRR
Donor Collection of Ed Chamberlain
Match Number 103
(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.