Full Details

Name and Model Number Keuffel & Esser N4135
Power Computing
Country of Origin USA
Date of Manufacture 1923
Front Scales A [ B, CI, C ] D
Back Scales P [ R ,W ] D
Scale Length 5" (12.5 cm)
Type of Rule Slide Rule
Construction Celluloid on mahogany
Area of Use Other
Comment Special slide rule for use by power engineers to make
calculations specific to steam and gas engines.
Serial No. 53681.
Rarity RR
Donor Collection of Dr. Paul J. Tarantolo Jr.
Match Number 44
(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.