Full Details

Name and Model Number EngPen
Country of Origin USA
Date of Manufacture Unknown
Front Scales [C] D L K A
Back Scales  
Scale Length 13 cm
Type of Rule Other
Construction Two telescoping metal tubes
Area of Use Generic
Comment An unusual tubular slide rule,
intended to fit over a pencil.
See details at https://www.nzeldes.com/HOC/PencilSliderules.htm
Rarity RRRR
Donor Collection of Nathan Zeldes
Match Number 409
(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.