Full Details

Name and Model Number Keuffel & Esser
Decimal Keeping
Slide Rule Type II
Unknown Model
Country of Origin USA
Date of Manufacture c. 1915
Front Scales A [ B C ] D K -- Top beveled edge: inch scale
Back Scales S B L T -- Bottom square edge: centimeter scale
Scale Length 25 cm
Type of Rule Slide Rule
Construction Closed frame mahogany body with celluloid laminate scale surfaces. Frameless cursor with tabs.
Area of Use Generic
Comment Instructions for keeping track of the position of the decimal point on the reverse.
Curious "B" scale on back of slide. Slide extends outside frame on the right end.
No model number & does not appear in K&E catalogs.
Sometimes referred to as the "K&E Mystery Rule"
Rarity RR
Donor Collection of Ed Chamberlain
Match Number 186
(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.