Full Details


Name and Model Number Heckendorff Pocket Calculator
Country of Origin Germany
Date of Manufacture unknowm
Front Scales C, D
Back Scales n^3, n^2, n^1, d^2/4
Scale Length 5.2" (13.2 cm)
Type of Rule Watch Type
Construction Metal with glass windows
Area of Use Generic
Comment Metal case with glass front and back and celluloid cursors.
Large stem wheel turns moveable front inner scale disc.
Small stem wheel turns moveable front and back cursors.
Molter style calculator identical to the Schacht U. Westerich pocket watch calculator.
Rarity RRR
Donor Collection of Dr. Paul J. Tarantolo Jr.
Match Number 32
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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.