Full Details

Name and Model Number Keuffel & Esser 4133
Roylance Electrical Slide Rule
Country of Origin USA
Date of Manufacture c. 1913-1914
Front Scales A [B C ] D
Back Scales S L T
Scale Length 20 cm
Type of Rule Slide Rule
Construction Mannhiem style mahogany body with celluloid laminate scale surfaces. The cursor is metal framed with three cursor lines.
Area of Use Electrical
Comment This rule appears in a special addendum of the 1913 catalog introducing the Roylance Electrical Slide Rule
Rarity RRR
Donor Collection of Clark McCoy
Match Number 221
(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.