Full Details

Name and Model Number Keuffel & Esser Co. N4100
Country of Origin USA
Date of Manufacture Estimate 1920s
Front Scales Unmarked stadia scales
Back Scales None
Scale Length 25 cm (10 inches)
Type of Rule Slide Rule
Construction Celluloid on Mahogany metal frame cursor adjustable body
Area of Use Topography
Comment Used for stadia surveying calculations. Constructed on heavier Mahogany frame than earlier models
Rarity RR
Donor Collection of Clay Castleberry
Match Number 289
(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.