Full Details

Name and Model Number Key to the steel square
Country of Origin USA, Lincoln, Nebraska
Date of Manufacture Copywrite 1902
Front Scales Rafter table scales
Back Scales Table of Tangents
Scale Length 2 inch diameter 6.28 in scale length
Type of Rule Disc
Construction Printed on plastic
Area of Use Generic
Comment Used for measuring and cutting rafters and using the steel square. Cost $1.50 in 1902
Rarity RR
Donor Collection of Clay Castleberry
Match Number 313
(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.