Full Details

Name and Model Number Keuffel & Esser 4018
Pocket Calculator
Country of Origin USA
Date of Manufacture 1909
Front Scales C, N^2 (2 circles)
Back Scales Tan, Log, Sine (2 circles)
Scale Length 5" (front scale)
Type of Rule Watch Type
Construction Metal with glass windows
Area of Use Generic
Comment Metal case with glass front and back.
Large stem wheel turns moveable front metal scale disks.
Small stem wheel turns moveable front and back cursors; fixed cursors on glass front.
Patent Appl. For, fob loop at 7 o'clock, Serial No. 869.
Rarity RR-RRR
Donor Collection of Dr. Paul J. Tarantolo Jr.
Match Number 35
(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.