Full Details

Name and Model Number Dempster - Dance
Country of Origin USA, Berkeley, California
Date of Manufacture 1930
Front Scales Circular C & D scales
Back Scales NONE
Scale Length 23-cm
Type of Rule Disc
Construction 10-cm dia. thin celluloid disk and transparent cursors.
Area of Use Other
Comment Given out as a party favor at the 1930 Engineer's Day Dance at the University of California, Berkeley. John Dempster, the designer of the Dempster RotaRule was a student at UC Berkeley at that time. He had also begun the manufacture of his Model A RotaRule by this time. He probably made this circular slide rule. Note that it is warped due to the use of unstable celluloid plastic.
Rarity RRRR
Donor Collection of Ed Chamberlain
Match Number 116
(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.