Full Details

Name and Model Number General Motors
Photographic Slide Rule
Country of Origin USA
Date of Manufacture post WWII
Front Scales C, fractions of one, Picas
Back Scales none
Scale Length 5 inch diameter
Type of Rule Disc
Construction Plastic finish on aluminum similar to a Gilson midget
Area of Use Photography
Comment Calculating proportions for photographic images. Must have been made by the Gilson SR Co.
Rarity RR
Donor Collection of Clay Castleberry - California USA
Match Number 282
(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.