Full Details

Name and Model Number Tröger Rechenscheiben
Country of Origin Germany
Date of Manufacture c. 1930
Front Scales C & D
Back Scales none
Scale Length 72 cm on 39 cm diameter Rechenscheibe
Type of Rule Disc
Construction 39 cm dia heavy cardboard disc with painted scale surfaces; 2 disc nested style with knob on reverse to turn the inner disc.
Area of Use Generic
Comment This 39 cm diameter example is shown with its 30 cm and 15 cm diameter baby sisters.
This circular slide rule was made by K. Emil Tröger of Mylau i. Vogtl. (in eastern Germany.) This is a special large size "suitable for people with low vision." More common sizes were 15 and 30 cm diameter. I found this example in a flea market in Germany. I have never seen another example of the 39 cm diameter Tröger Rechensheibe.
Rarity RRR
Donor Collection of Ed Chamberlain
Match Number 201
(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.